A TEXT-BOOK 
OF 
HUMAN PHYSIOLOGY. PRESS NOTICES 
OF PREVIOUS EDITIONS 
LANDOIS and STIRLING’S PHYSIOLOGY. 
“ Most effectively aids the busy physician to trace from morbid phenomena back 
the course of divergence from healthy physical operations, and to gather in this way 
new lights and novel indications for the comprehension and treatment of the 
maladies with which he is called upon to cope.”—American Journal of Medical 
Sciences. 
“ I know of no book which is its equal in the applications to the needs of clinical 
medicine.”—Prof. Harrison Allen, late Professor of Physiology, University of 
Pennsylvania. 
“ We have no hesitation in saying that this is the work to which the Prac- 
titioner will turn whenever he desires light thrown upon the phenomena of a 
complicated or important case.”—Edinburgh Medical Journal. 
“So great are the advantages offered by Prof. Landois’ Text-Book, from the 
exhaustive and eminently practical manner in which the subject is treated, 
that it has passed through four large editions in the same numberof years. . . . 
Dr. Stirling’s annotations have materially added to the value of the work. Ad- 
mirably adapted for the Practitioner. . . . With this Text-book at command, 
no Student could fail in his examination.”—The Lancet. 
“One of the most practical works on Physiology ever written, forming a 
* bridge ’ between Physiology and Practical Medicine. ... Its chief merits are 
its completeness and conciseness. . . . The additions by the Editor are able 
and judicious. . . . Excellently clear, attractive, and succinct.”—British 
Medical Journal. 
“The great subjects dealt with are treated in .an admirably clear, terse, and 
happily illustrated manner.”—Praditio7ter. 
“Unquestionably the most admirable exposition of the relations of Human 
Physiology to Practical Medicine ever laid before English readers.”—Students' 
Journal. 
“As a work of reference, Landois and Stirling’s Treatise ought to take 
the foremost place among the text-books in the English language. The wood- 
cuts are noticeable for their number and beauty.”—Glasgow Medical Journal. 
“Landois’ Physiology is, without question, the best text-book on the subject that 
has ever been written.”—New York Medical Record. 
“The chapter on the Brain and Spinal Cord will be a most valuable one for the 
general reader, the translator’s notes adding not a little to its importance. The 
sections on Sight and Hearing are exhaustive. . . . The Chemistry of the Urine 
is thoroughly considered. ... In its present form, the value of the original has 
been greatly increased. . . . The text is smooth, accurate, and unusually free 
from Germanisms; in fact, it is good English.”—New York Medical Journal. 
“ It is not for the physiological student alone that Prof. Landois’ book possesses 
great value, for it has been addressed to the practitioner of medicine as 
well, who will find here a direct application of physiological to pathological pro- 
cesses.”—Medical Bulletin. 
P. BLAKISTON, SON & CO., Publishers, Philadelphia. A TEXT-BOOK 
OF 
HUMAN PHYSIOLOGY 
INCLUDING 
HISTOLOGY AND MICROSCOPICAL ANATOMY 
WITH SPECIAL REFERENCE TO THE REQUIREMENTS OF 
PRACTICAL MEDICINE 
BY 
DR. L. LANDOIS, 
PROFESSOR OF PHYSIOLOGY AND DIRECTOR OF THE PHYSIOLOGICAL INSTITUTE, 
UNIVERSITY OF GREIFSWALD. 
TRANSLATED FROM THE SEVENTH GERMAN EDITION. 
WILLIAM STIRLING, M. D., Sc. D., 
WITH ADDITIONS BY 
BRACKENBURY PROFESSOR OF PHYSIOLOGY AND HISTOLOGY IN THE OWENS COLLEGE AND PROFESSOR IN THE 
VICTORIA UNIVERSITY, MANCHESTER ; EXAMINER IN PHYSIOLOGY, 
UNIVERSITY OF OXFORD. 
WITH 845 ILLUSTRATIONS, 34 IN COLORS. 
FOURTH EDITION. 
PHILADELPHIA: 
P. BLAKISTON, SON & CO., 
1012 WALNUT STREET. 
18 91. 
[All Rights Reserved. ] TO 
SIR JOSEPH LISTER, Baronet, 
M.D., D.C.L., LL.D., F.R.SS. (lOND. AND EDIN.), 
PROFESSOR OF CLINICAL SURGERY IN KING*S COLLEGE, LONDON; SURGEON-EXTRAORDINARY TO THE QUEEN 
FORMERLY REGIUS PROFESSOR OF CLINICAL SURGERY IN THE UNIVERSITY OF EDINBURGH. 
IN ADMIRATION OF 
Paw of gtitntt, 
WHOSE BRILLIANT DISCOVERIES HAVE REVOLUTIONIZED 
MEDICAL PRACTICE, AND CONTRIBUTED INCALCULABLY TO THE 
WELL-BEING OF MANKIND 
AND IN GRATITUDE TO 
WHOSE NOBLE EARNESTNESS IN INCULCATING 
THE SACREDNESS OF HUMAN LIFE 
STIRRED THE HEARTS OF ALL WHO HEARD HIM: 
SHork is mpwtfullj ficiruatO 
BY HIS FORMER PUPIL, 
THE TRANSLATOR. Prefatory Note to the Fourth English Edition. 
The Fourth English Edition of the Text-book now laid before the Profession 
has again been thoroughly revised, so as to bring every Section as far as possible 
into harmony with the most recent advances in Physiological Science. 
A new feature introduced—that of printing some of the illustrations of 
Microscopical subjects in Colors—will, it is hoped, be found helpful. For 
drawing several of these colored figures I am indebted to Arthur Clarkson, 
m.b., c.m., formerly my junior Demonstrator of Physiology, and for others 
to my pupils, Mr. V. E. H. Lindesay and Mr. F. J. S. Mathwin. 
A large number of new figures, many of them original, have also been added, 
so that the total number of illustrations is now 845. My acknowledgments 
are due, specially, in regard to some of these, to the Cambridge Scientific 
Instrument Company, Messrs Alvergniat, Verdin, Petzold, Curry & Paxton, 
and to my friends Professors Roy, Fredericq, Leech, Burdon-Sanderson, Mr. 
Gotch, Dr. Adami, and Dr. Macnaughton Jones. 
Further, I have to thank the last mentioned for some hints which have 
enabled me to improve the Section on the “ Ear and Hearing.” I am also 
indebted to Professor Ramon y Cayal, of Barcelona, for his courtesy in send- 
ing me his original Papers recording the results of his investigations on the 
Central Nervous System, some of which I have ventured to epitomize and 
introduce into the text. The sources of the other illustrations are given else- 
where. 
WILLIAM STIRLING. Preface to the First English Edition. 
The fact that Professor Landois’ “ Lehrbuch der Physiologie des Menschen” 
has already passed through Four large Editions since its first appearance in 
1880, shows that in some special way it has met the wants of Students and 
Practitioners in Germany. The characteristic which has thus commended 
the work will be found mainly to lie in its eminent practicality ; and it is this 
consideration which has induced me to undertake the task of putting it into 
an English dress for English readers. 
Landois’ work, in fact, forms a Bridge between Physiology and the Practice 
of Medicine. It never loses sight of the fact that the Student of to-day 
is the practicing Physician of to-morrow. Thus, to every Section is appended 
—after a full description of the normal processes—a short resume of the 
pathological variations, the object of this being to direct the attention of the 
Student, from the outset, to the field of his future practice, and to show him 
to what extent pathological processes are a disturbance of the normal 
activities. 
In the same way, the work offers to the busy physician in practice a ready 
means of refreshing his memory on the theoretical aspects of Medicine. 
He can pass backwards from the examination of pathological phenomena 
to the normal processes, and, in the study of these, find new indications and 
new lights for the appreciation and treatment of the cases under consideration. 
With this object in view, all the methods of investigation which may with 
advantage be used by the Practitioner, are carefully and fully described ; and 
Histology, also, occupies a larger place than is usually assigned to it in Text- 
books of Physiology. 
A word as to my own share in the present version :— 
(1) In the task of translating, I have endeavored throughout to convey 
the author’s meaning accurately, without a too rigid adherence to the 
original. Those who from experience know something of the difficulties of 
such an undertaking will be most ready to pardon any shortcomings they may 
detect. 
(2) Very considerable additions have been made to the Histological and 
also (where it has seemed necessary) to the Physiological sections. All such 
additions are enclosed within square brackets [ ]. I have to acknowledge 
my indebtedness to many valuable Papers in the various Medical Journals— 
British and Foreign—and also to the Histological Treatises of Cadiat, Ranvier, 
and Klein; Quain’s Anatomy, vol. 11, ninth edition; Hermann’s Handbuch 
der Physiologie; and the Text-books on Physiology by Rutherford, Foster, and X 
PREFACE. 
Kirkes ; Gamgee’s Physiological Chemistry ; Ewald’s Digestion; and Roberts’s 
Digestive Ferments. 
(3) The illustrations have been greatly increased in number, viz., from 
275 in the Fourth German Edition to 494 in the English version. These 
additional Diagrams, with the sources whence derived, are distinguished in 
the List of Wood-cuts by an asterisk. 
There only remains for me now to express my thanks to all who have kindly 
helped in the progress of the work, either by furnishing Illustrations or other- 
wise—especially to Drs. Byrom Bramwell, Dudgeon, Lauder Brunton, and 
Knott; Mr. Hawksley; Professors Hamilton and M’Kendrick; to my 
esteemed teacher and friend, Professor Ludwig, of Leipsic ; and finally to 
my friend, Mr. A. W. Robertson, m. a., formerly Assistant Librarian in the 
University, and now Librarian of the Aberdeen Public Library, for much 
valuable assistance while the work was passing through the press. 
In conclusion—and forgetting for the moment my own connection with 
it—I heartily commend the work per se to the attention of Medical Men, and 
can wish for it no better fate than that it may speedily become as popular in 
this country as it is in its Fatherland. 
WILLIAM STIRLING. 
Aberdeen University, 
November, 1884. GENERAL CONTENTS. 
INTRODUCTION. 
The Scope of Physiology and its Relation to the other Branches of Natural Science, . . xxxv 
Matter, , xxxvi 
Forces, ..... . xxxvii 
Law of the Conservation of Energy, x]j 
Animals and Plants, x]jj 
Vital Energy and Life, x]jv 
I. PHYSIOLOGY OF THE BLOOD. 
SECTION 
1. Physical Properties of the Flood, x 
2. Microscopic Examination of the Blood, 3 
3. Histology of the Human Red Blood-Corpuscles, ... 6 
4. Conservation of the Blood-Corpuscles, g 
5. Preparation of the Stroma—Making Blood “ Lake-Colored,” . 9 
6. Form and Size of the Blood-Corpuscles of Different Animals, 10 
7. Origin of the Red Blood-Corpuscles, u 
8. Decay of the Red Blood-Corpuscles, 14 
9. The Colorless Corpuscles—Leucocytes—Blood Plates—Granules, 15 
10. Abnormal Changes of the Blood-Corpuscles, 20 
11. Chemical Constituents of the Red Blood-Corpuscles, 21 
12. Preparation of Haemoglobin Crystals, 22 
13. Quantitative Estimation of Haemoglobin, 23 
14. Use of Spectroscope, 25 
15. Compounds of Haemoglobin—Methaemoglobin, 25 
16. Carbonic Oxide-Haemoglobin—Poisoning with Carbonic Oxide, . 28 
17. Other Compounds of Haemoglobin, 30 
18. Decomposition of Haemoglobin, 30 
19. Haemin and Blood Tests, 21 
20. Haematoidin, 32 
21. The Colorless Proteid of Haemoglobin, 32 
22. Proteids of the Stroma, • 32 
23. The other Constituents of Red Blood-Corpuscles, 33 
24. Chemical Composition of the Colorless Corpuscles 34 
25. Blood-Plasma, and its Relation to Serum, 34 
26. Preparation of Plasma, 35 
27. Fibrin—Coagulation of the Blood, 33 
28. General Phenomena of Coagulation, 36 
29. Cause of the Coagulation of Blood, 39 
30. Source of the Fibrin-Factors, 43 
31. Relation of the Red Blood-Corpuscles to the Formation of Fibrin, 44 
32. Chemical Composition of the Plasma and Serum, 44 
33. The Gases of the Blood, 46 
34. Extraction of the Blood Gases, 47 
35. Quantitative Estimation of the Blood Gases, . . 30 
36. The Blood Gases, • 31 CONTENTS. 
SECTION PAGE 
37. Is Ozone (03) present in Blood ? 52 
38. Carbon Dioxide and Nitrogen in Blood, 53 
39. Arterial and Venous Blood, 54 
40. Quantity of Blood, . . 55 
41. Variations from the Normal Conditions of the Blood, 56 
II. PHYSIOLOGY OF THE CIRCULATION. 
42. General View of the Circulation, 59 
43. The Heart, 60 
44. Arrangement of the Cardiac Muscular Fibres, 60 
45. Arrangement of the Ventricular Fibres, 62 
46. Pericardium, Endocardium, Valves, .... 63 
47. Automatic Regulation of the Heart, 64 
48. The Movements of the Heart, 66 
49. Pathological Disturbance of Cardiac Action, 69 
50. The Apex-Beat—The Cardiogram, 71 
51. The Time occupied by the Cardiac Movements, 77 
52. Pathological Disturbance of the Cardiac Impulse, ... ... . .... 82 
53. The Heart-Sounds, 84 
54. Variations of the Heart-Sounds, 87 
55. Persistence of the Movements of the Heart, 88 
56. Physical Examination of the Heart, 89 
57. Innervation of the Heart—Cardiac Nerves, 90 
58. The Automatic Motor-Centres of the Heart, 92 
59. The Cardio-Pneumatic Movements 102 
60. Influence of the Respiratory Pressure on the Heart, . 103 
THE CIRCULATION. 
61. The Flow of Fluids through Tubes, 105 
62. Propelling Force, Velocity of Current, Lateral Pressure, 105 
63. Currents through Capillary Tubes, 107 
64. Movements of Fluids and Wave Motion in Elastic Tubes, 107 
65. Structure and Properties of the Blood-Vessels, , . ' 108 
66. Investigation of the Pulse, .. 115 
67. Pulse Tracing or Sphygmogram, . . . 119 
68. Origin of the Dicrotic Wave, 121 
69. Dicrotic Pulse, 125 
70. Characters of the Pulse, 126 
71. Variations in the Strength, Tension, and Volume of the Pulse, 127 
72. The Pulse-Curves of various Arteries, 128 
73. Anacrotism, 128 
74. Influence of the Respiratory Movements on the Pulse-Curve, 130 
75. Influence of Pressure upon the Form of the Pulse-Wave, 132 
76. Rapidity of Transmission of Pulse-Waves, 133 
77. Propagation of the Pulse-Wave in Elastic Tubes 133 
78. Velocity of the Pulse-Wave in Man, 133 
79. Other Pulsatile Phenomena, 134 
80. Vibrations Communicated to the Body by the Action of the Heart, 135 
81. The Blood-Current, 136 
82. Schemata of the Circulation, . . 138 
83. Capacity of the Ventricles, 138 
84. Estimation of the Blood-Pressure, 139 
85. Blood-Pressure in the Arteries, 143 
86. Blood-Pressure in the Capillaries, 149 
87. Blood-Pressure in the Veins, 150 
88. Blood-Pressure in the Pulmonary Artery, 151 
89. Measurement of the Velocity of the Blood-Stream, ... 153 
90. Velocity of the Blood in Arteries, Capillaries, and Veins, 156 
91. Estimation of the Capacity of the Ventricles, 157 
92. The Duration of the Circulation, 158 
93. Work of the Heart, 158 CONTENTS. 
SECTION PAGE 
94. Blood-Current in the Smaller Vessels, 159 
95. Passage of the Blood-Corpuscles out of the Vessels—[Diapedesis], . ...... 161 
96. Movement of the Blood in the Veins, 162 
97. Sounds or Bruits within Arteries, 162 
98. Venous Murmurs, 163 
99. The Venous Pulse—Phlebogram, 164 
100. Distribution of the Blood, ... 166 
101. Plethysmography, 166 
102. Transfusion of Blood 168 
THE BLOOD-GLANDS. 
103. The Spleen—Thymus—Thyroid—Supra-Renal Capsules—Hypophysis Cerebri— 
Coccygeal and Carotid Glands, 170 
104. Comparative, 182 
105. Historical Retrospect 183 
III. PHYSIOLOGY OF RESPIRATION. 
106. Structure of the Air-Passages and Lungs, 185 
107. Mechanism of Respiration, 195 
108. Quantity of Gases Respired, 196 
109. Number of Respirations, 197 
no. Time Occupied by the Respiratory Movements, 199 
in. Pathological Variations of the Respiratory Movements, 201 
112. General View of the Respiratory Muscles, 203 
113. Action of the Individual Respiratory Muscles, 205 
114. Relative Size of the Chest, 208 
115. Pathological Variations of the Percussion Sounds, 211 
116. The Normal Respiratory Sounds, 212 
117. Pathological Respiratory Sounds, 213 
118. Pressure in the Air-Passages during Respiration, 214 
119. Appendix to Respiration, 215 
120. Peculiarly Modified Respiratory Sounds, 216 
121. Quantitative Estimation of C02, O, and Watery Vapor, 217 
122. Methods of Investigation, 219 
123. Composition and Properties of Atmospheric Air 219 
124. Composition of Expired Air, 220 
125. Daily Quantity of Gases Exchanged, 221 
126. Daily Gaseous Income and Expenditure, 222 
127. Conditions influencing the Gaseous Exchanges, 222 
128. Diffusion of Gases within the Lungs, 225 
129. Exchange of Gases between the Blood and Air, 225 
130. Dissociation of Gases, 225 
131. Cutaneous Respiration, 228 
132. Internal Respiration, 228 
Comparative Physiology of Respiration, 231 
133. Respiration in a Closed Space, 232 
134. Dyspnoea and Asphyxia, 232 
135. Respiration of Foreign Gases, 236 
136. Accidental Impurities of the Air, 236 
137. Ventilation of Rooms, 237 
138. Formation of Mucus, 238 
139. Action of the Atmospheric Pressure, 240 
140. Comparative and Historical, 242 
IV. PHYSIOLOGY OF DIGESTION. 
141. The Mouth and its Glands, 243 
142. The Salivary Glands, 247 
143. Histological Changes in Salivary Glands, 250 
144. The Nerves of the Salivary Glands, 251 
145. Action of Nerves on the Salivary Secretion, 252 XIV 
CONTENTS. 
SECTION PAGE 
146. The Saliva of the Individual Glands, 258 
147. The Mixed Saliva in the Mouth, 259 
148. Physiological Action of Saliva, 260 
149. Tests for Sugar, 263 
150. Quantitative Estimation of Sugar, 264 
151. Mechanism of the Digestive Apparatus, 265 
152. Introduction of the Food 265 
153. The Movements of Mastication, 266 
154. Structure and Development of the Teeth, 267 
155. Movements of the Tongue, 271 
156. Deglutition, 273 
157. Movements of the Stomach, 280 
158. Vomiting, 281 
159. Movements of the Intestine, 283 
160. Excretion of Faecal Matter, 284 
161. Conditions Influencing the Movements of the Intestines, 287 
162. Structure of the Stomach, 291 
163. The Gastric Juice, 294 
164. Secretion of Gastric Juice, 296 
165. Methods of Obtaining Gastric Juice, 300 
166. Process of Gastric Digestion, «... 301 
167. Gases in the Stomach, 308 
168. Structure of the Pancreas, 308 
169. The Pancreatic Juice, 310 
170. Digestive Action of the Pancreatic Juice, 312 
171. The Secretion of the Pancreatic Juice 316 
172. Preparation of Peptonized Food, 317 
173. Structure of the Liver, 318 
174. Chemical Composition of the Liver-Cells, 325 
175. Diabetes Mellitus and Glycosuria, 330 
176. The Functions of the Liver, 332 
177. Constituents of the Bile 333 
178. Secretion of Bile, 337 
179. Excretion of Bile, 340 
180. Reabsorption of Bile—Jaundice, 340 
181. Functions of the Bile, 342 
182. Fate of the Bile in the Intestine, 344 
183. The Intestinal Juice, 345 
184. Fermentation Processes in the Intestine, 348 
185. Processes in the Large Intestine, 353 
186. Pathological Variations, 356 
187. Comparative Physiology, 359 
188. Historical Retrospect 360 
V. PHYSIOLOGY OF ABSORPTION. 
189. The Organs of Absorption, 362 
190. Structure of the Small and Large Intestines, 362 
191. Absorption of the Digested Food, 370 
192 Absorptive Activity of the Wall of the Intestine, 372 
193. Influence of the Nervous System, 379 
194. Feeding with “ Nutrient Enemata,” 379 
195. Chyle-Vessels and Lymphatics, ... 379 
196. Origin of the Lymphatics, 382 
197. The Lymph-Glands 387 
198. Properties of Chyle and Lymph, 391 
199. Quantity of Lymph and Chyle, 394 
200. Origin of Lymph, 395 
201. Movement of Chyle and Lymph, 396 
202. Absorption of Parenchymatous Effusions, 399 
203. Dropsy, Qidema, Serous Effusions, 399 
204. Comparative Physiology, 400 
205. Historical Retrospect, 401 CONTENTS. 
XV 
VI. PHYSIOLOGY OF ANIMAL HEAT. 
SECTION PAGE 
206. Sources of Heat, 402 
207. Homoiothermal and Poikilothermal Animals, .... 405 
208. Methods of Estimating Temperature—Thermometry, 406 
209. Temperature Topography, 409 
210. Conditions Influencing the Temperature of Organs, 410 
211. Estimation of the Amount of Heat—Calorimetry, 411 
212. Thermal Conductivity of Animal Tissues, 413 
213. Variations of the Mean Temperature, 413 
214. Regulation of the Temperature, 416 
215. Income and Expenditure of Heat, 420 
216. Variations in Heat Production, 421 
217. Relation of Heat Production to Bodily Heat, 421 
218. Accommodation for Different Temperatures, 422 
219. Storage of Heat in the Body, 423 
220. Fever 423 
221. Artificial Increase of the Temperature, 425 
222. Employment of Heat, 425 
223. Increase of Temperature post-mortem, 426 
Action of Cold on the Body, 426 
225. Artificial Lowering of Temperature, 427 
226.. Employment of Cold, 428 
227. Heat of Inflamed Parts, 428 
228. Historical and Comparative, 428 
VII. PHYSIOLOGY OF THE METABOLIC PHENOMENA 
OF THE BODY. 
229. General View of Food-Stuffs, 431 
230. Structure and Secretion of the Mammary Glands, 433 
231. Milk and its Preparations, 435 
232. Eggs, 441 
233. Flesh and its Preparations, 442 
234. Vegetable Foods, 444 
235. Condiments—Coffee, Tea, and Alcohol, 447 
236. Equilibrium of the Metabolism, 449 
237. Metabolism during Hunger and Starvation, 456 
238. Metabolism during a purely Flesh Diet, 458 
239. A Diet of Fat or of Carbohydrates, 459 
240. Mixture of Flesh and Fat, 460 
241. Structure and Origin of Fat in the Body, . . 460 
242. Corpulence, 463 
243. The Metabolism of the Tissues, 464 
244. Regeneration of Organs and Tissues, 466 
245. Transplantation of the Tissues, 469 
246. Increase in Size and Weight during Growth, 470 
GENERAL VIEW OF THE CHEMICAL CONSTITUENTS OF 
THE ORGANISM. 
247. Inorganic Constituents, 471 
248. Organic Compounds—Proteids, 473 
249. The Animal and Vegetable Proteids and their Characters, 476 
250. The Albuminoids and Ferments, 480 
251. The Fats, 485 
252. The Carbohydrates, 487 
253. Historical Retrospect, 490 
VIII. THE SECRETION OF URINE. 
254. Structure of the Kidney, 491 
255. The Urine, 499 
256. Organic Constituents of Urine—Urea, 502 XVI 
CONTENTS. 
SECTION PAGE 
257. Qualitative and Quantitative Estimation of Urea, 506 
258. Uric Acid, 507 
259. Qualitative and Quantitative Estimation of Uric Acid, 510 
260. Kreatinin and other Substances, 511 
261. Coloring Matters of the Urine, 514 
262. Indigo, Phenol, Kresol, Pyrokatechin 515 
263. Spontaneous Changes in Urine, Fermentations, 520 
264. Albumin in Urine, 521 
265. Blood in Urine, 524 
266. Bile in Urine, 526 
267. Sugar in Urine 527 
268. Cystin, 530 
269. Leucin, Tyrosin, 530 
270. Deposits in Urine, 531 
271. General Scheme for Detecting Urinary Deposits, 532 
272. Urinary Calculi, 534 
273. The Secretion of Urine, 535 
274. Formation of the Urinary Constituents, 541 
275. Passage of Various Substances into the Urine, 544 
276. Influence of Nerves on the Renal Secretion, 544 
277. Uraemia, Ammoniaemia 548 
278. Structure and Functions of the Ureter, 549 
279. Urinary Bladder and Urethra, . 551 
280. Accumulation and Retention of Urine, 553 
281. Retention and Incontinence of Urine, 556 
282. Comparative and Historical, 556 
IX. FUNCTIONS OF THE SKIN. 
283. Structure of the Skin, Nails, and Hair, . 557 
284. The Glands of the Skin, 564 
285. The Skin as a Protective Covering, 565 
286. Cutaneous Respiration and Secretion—Sweat, • 565 
287. Conditions Influencing the Secretion of Sweat, 568 
288. Pathological Variations, 570 
289. Cutaneous Absorption—Galvanic Conduction, 571 
290. Comparative—Historical, 572 
X. PHYSIOLOGY OF THE MOTOR APPARATUS. 
291. Ciliary Motion, Pigment Cells, 573 
292. Structure and Arrangement of the Muscles, 576 
293. Physical and Chemical Properties of Muscle 589 
294. Metabolism in Muscle, 592 
295. Rigor Mortis, 596 
296. Muscular Excitability, 599 
297. Changes in a Muscle during Contraction, 605 
298. Muscular Contraction, 607 
299. Rapidity of Transmission of a Muscular Contraction, 620 
300 Muscular Work, 622 
301. The Elasticity of Muscle, 624 
302. Formation of Heat in an Active Muscle, 627 
303. The Muscle-Sound, . . 628 
304. Fatigue and Recovery of Muscle, 630 
305. The Structure and Mechanism of Bones and Joints, i 634 
306. Arrangement and Uses of the Muscles of the Body, 639 
307. Gymnastics—Pathological Motor Variations, 642 
308. Standing, 643 
309. Sitting . . ■ 645 
310. Walking, Running, and Leaping, 645 
311. Comparative, 648 CONTENTS. 
XVII 
VOICE AND SPEECH. 
SECTION PAGE 
312. Voice and Speech, 649 
313. Arrangements of the Larynx, 650 
314. Organs of Voice—Laryngoscopy, 656 
315. Conditions Modifying the Laryngeal Sounds, 658 
316. Range of the Voice, 659 
317. Speech—The Vowels, 660 
318. The Consonants 662 
319. Pathological Variations of Voice and Speech, 663 
320. Comparative—Historical, 664 
XI. GENERAL PHYSIOLOGY OF THE NERVES AND 
ELECTRO-PHYSIOLOGY. 
321. Structure and Arrangement of the Nerve-Elements, 666 
322. Chemical and Mechanical Properties of Nerve-Substance, 674 
323. Metabolism of Nerves, 676 
324. Excitability of Nerves—Stimuli, 676 
325. Diminution of Excitability—Degeneration and Regeneration of Nerves, 682 
326. The Galvanic Current, 687 
327. Action of the Galvanic Current—Galvanometer, 689 
328. Electrolysis, 690 
329. Induction—Extra-Current—Magneto-Induction, 696 
330. Du Bois-Reymond’s Inductorium, 699 
331. Electrical Currents in Passive Muscle and Nerve, 702 
332. Currents of Stimulated Muscle and Nerve, 705 
333. Currents in Nerve and Muscle during Electrotonus, 711 
334. Theories of Muscle and Nerve Currents, 713 
335. Electrotonic Alteration of the Excitability, 716 
336. Electrotonus—Law of Contraction, 718 
337. Rapidity of Transmission of Nervous Impulses, 722 
338. Double Conduction in Nerves 724 
339. Therapeutical Uses of Electricity—Reaction of Degeneration, 726 
340. Electrical Charging of the Body, 731 
341. Comparative—Historical, 73x 
XII. PHYSIOLOGY OF THE PERIPHERAL NERVES. 
342. Classification of Nerve-Fibres, 734 
343. Nervus Olfactorius, 737 
344. Nervus Opticus, 738 
345. Nervus Oculomotorius, 741 
346. Nervus Trochlearis, 743 
347. Nervus Trigeminus, 744 
348. Nervus Abducens, 754 
349. Nervus Facialis, 754 
350. Nervus Acusticus, 759 
351. Nervus Glosso-pharyngeus, 762 
352. Nervus Vagus, ’ ' 763 
353. Nervus Accessorius, 77 x 
354. Nervus Hypoglossus, 772 
355. The Spinal Nerves, 772 
356. The Sympathetic Nervous System, 777 
357. Comparative—Historical, 783, 
XIII. PHYSIOLOGY OF THE NERVE-CENTRES. 
358. General, 785 
359. Structure of the Spinal Cord, 786 
360. Spinal Reflexes, 805 
361. Inhibition of the Reflexes, 809 CONTENTS. 
SECTION PAGE 
362. Centres in the Spinal Cord, 814 
363. Excitability of the Spinal Cord, 815 
364. The Conducting Paths in the Spinal Cord, 817 
365. General Scheme of the Brain . . 821 
366. The Medulla Oblongata, 830 
367. Reflex Centres of the Medulla Oblongata, 835 
368. The Respiratory Centre, 837 
369. The Cardio-Inhibitory Centre, 848 
370. The Accelerans Cordis Centre, 851 
371. Vaso-motor Centre and Vaso-motor Nerves, 854 
372. Vaso-dilator Centre and Vaso-dilator Nerves, 863 
373. The Spasm Centre—The Sweat Centre, 866 
374. Psychical Functions of the Cerebrum, 867 
375. Structure of the Cerebrum—Motor Cortical Centres, 874 
376. The Sensory Cortical Centres, . 895 
377. The Thermal Cortical Centres, 899 
378. Topography of the Cortex Cerebri, 901 
379. The Basal Ganglia—The Mid-brain, 911 
380. The Structure and Functions of the Cerebellum, 921 
381. The Protective Apparatus of the Brain, 925 
382. Comparative—Historical, 930 
XIV. PHYSIOLOGY OF THE SENSE ORGANS. 
1. SIGHT. 
383. Introductory Observations, 931 
384. Histology of the Eye, 933 
385. Dioptric Observations, 946 
386. Formation of a Retinal Image, 950 
387. Accommodation of the Eye, 953 
388. Normal and Abnormal Refraction, 958 
389. The Power of Accommodation, 960 
390. Spectacles, 961 
391. Chromatic Aberration and Astigmatism, 962 
392. The Iris, . . 964 
393. Entoptical Phenomena, 968 
394. Illumination of the Eye—The Ophthalmoscope, 970 
395. Activity of the Retina in Vision, 974 
396. Perception of Colors, 981 
397. Color-blindness 986 
398. Stimulation of the Retina, 987 
399. Movements of the Eyeballs, 991 
400. Binocular Vision, 996 
401. Single Vision—Identical Points, 996 
402. Stereoscopic Vision, 998 
403. Estimation of Size and Distance, tool 
404. Protective Organs of the Eye, 1003 
405. Comparative—Historical, 1006 
2. HEARING. 
406. Structure of the Organ of Hearing, 1008 
407. Physical Introduction, 1009 
408. Ear Muscles, • 1010 
409. Tympanic Membrane, ion 
410. The Auditory Ossicles and their Muscles, 1013 
411. Eustachian Tube—Tympanum 1017 
412. Conduction of Sound in the Labyrinth, 1019 
413. Structure of the Labyrinth, 1020 
414. Auditory Perceptions of Pitch, 1024 
415. Perception of Quality—Vowels, 1027 CONTENTS. 
XIX 
SECTION PAGE 
416. Action of the Labyrinth 1030 
417. Harmony—Discords—Beats, 1032 
418. Perception of Sound, 1033 
419. Comparative—Historical, 1034 
3. SMELL. 
420. Structure of the Organ of Smell io35 
421. Olfactory Sensations, 1039 
4. TASTE. 
422. Position and Structure of the Organs of Taste, 1040 
423. Gustatory Sensations, 1042 
5. TOUCH. 
424. Terminations of Sensory Nerves, 1044 
425. Sensory and Tactile Sensations, 1048 
426. The Sense of Locality, 1049 
427. The Pressure Sense, 1052 
428. The Temperature Sense, 1053 
429. Common Sensation—Pain, 1056 
430. The Muscular Sense, io57 
XV. PHYSIOLOGY OF REPRODUCTION AND DEVELOPMENT. 
431. Forms of Reproduction, io59 
432. Testis—Seminal Fluid, 1061 
433. The Ovary—Ovum—Uterus, 1067 
434. Puberty, 1073 
435. Menstruation, 1073 
436. Penis—Erection, 1076 
437. Emission—Reception of the Semen, 1078 
438. Fertilization of the Ovum, 1079 
439. Impregnation and Cleavage of the Ovum, 1080 
440. Structures formed from the Epiblast, 1088 
441. Structures formed from the Mesoblast and Hypoblast, 1091 
442. Formation of the Heart and Embryo, 1093 
443. Further Formation of the Body, 1094 
444. Formation of the Amnion and Allantois, 1096 
445. Human Foetal Membranes—Placenta, io97 
446. Chronology of Human Development, 1102 
447. Formation of the Osseous System, *...., 1103 
448. Development of the Vascular System, 1109 
449. Formation of the Intestinal Canal, 1112 
450. Development of Genito-Urinary Organs, 1114 
451. Formation of the Central Nervous System 1118 
452. Development of the Sense Organs, 1120 
453. Birth, . . . 1122 
454. Comparative—Historical, 1123 
Appendix A; Bibliography, 1126 
Appendix B; Tables of Measure (Metric and Ordinary) and of Temperature, . . 1130 
Index, 1131 LIST OF ILLUSTRATIONS. 
FIGURE PAGE 
1. Human colored blood-corpuscles, 3 
2. Apparatus of Abbe and Zeiss for estimating the blood-corpuscles, 4 
3. Mixer, 4 
*4. Gowers’ haemacytometer (Hawksley), 5 
*5. Human blood-corpuscles {Funke), 6 
*6. Crenation of human blood-corpuscles, 6 
7. Red blood-corpuscles showing various changes of shape, 7 
*8. Effect of heat on blood-corpuscles {Stirling), 7 
*9. Effect of reagents on blood-corpuscles {Stirling'), 8 
*10. Action of syrup on frog’s blood {Stirling), 9 
*11. Frog’s blood {Ranvier), 10 
12. Vaso-formative cells, 12 
*13. Blood-corpuscles undergoing mitosis {Bizzozero), . . 14 
14. White blood-corpuscles and fibrin, 15 
*15. White blood-corpuscles {Klein) 17 
16. Amoeboid movements of colorless corpuscles, 18 
17. Blood-plates and their derivatives 19 
*18. Blood-plates from human blood {v. Jaksch), 20 
19. Haemoglobin crystals, 22 
*20. Gowers’ hsemoglobinometer {Hawksley), 23 
*21. Fleischl’s haemometer {Reichert), 24 
22. Scheme of a spectroscope 25 
23. Various spectra of haemoglobin and its compounds, 26 
*24. Absorption spectrum of Hb02 {Rollett), . 27 
*25. Absorption spectrum of Hb {Rollett), 27 
26. Haemin crystals, 31 
27. Haematoidin crystals, 32 
*28. Hewson’s experiment, 39 
29. Scheme of Pfliiger’s gas-pump, ... 48 
*30. Alvergniat’s gas-pump, 49 
*31. Scheme of Alvergniat’s pump {Stirling), 50 
*32. Micrococcus, bacterium, vibrio, 58 
33. Scheme of the circulation, 59 
34. Muscular fibres from the heart, 60 
35. Muscular fibres in the left auricle, 61 
36. Muscular fibres in the ventricles 62 
*37. Section of the endocardium (Cadiat), 63 
*38. Purkinje’s fibres {Ranvier), 64 
*39- Scheme of a cardiac cycle {Jolyet), 66 
40. Cast of the ventricles of the human heart, 68 
41. The closed semilunar valves, 69 
*42. Gaule’s maximum and minimum manometer {Gsckeidlen), 69 
*43. Various cardiographs {Hermann), 71 
*44. Cardiogram {Edgren), 72 
*45. Arteriogram and Cardiogram {Edgren), 72 
*46. Cardiogram of dog {Fredericq), 72 
47. Curves of the apex-beat, 73 
48. Changes of the heart during systole, and sections of thorax, 74 
49. Cardiographic tracings from case of ectopia cordis (Franfois Franck), and from 
exposed heart of a cat, 75 
50. Cardiogram of the apex-beat (dog) 76 
*51. Dog’s heart—posterior, anterior, and left lateral surfaces {Ludwig and Hesse), . 77 LIST OF ILLUSTRATIONS. 
FIGURE _ _ PAGE 
*52. Base of heart in systole and diastole (.Ludwig and Hesse), 77 
*53. Base of heart {Ludwig and Hesse), . . 77 
54. Curves from a rabbit’s ventricle, 78 
*55. Marey’s registering tambour {Hermann), 79 
*56. Marey’s cardiac sound, 
57. Curves obtained with a cardiac sound, 81 
58. Curves of the cardiac impulse, 83 
*59. Scheme of cardiac cycle 84 
*60. Position of the heart in the chest (Luschka and Gairdner), 86 
*61. Curves of excised rabbits’ hearts (Stirling, after Waller), 88 
62. Topography of the chest and its contents, 90 
*63. Heart of frog from the front (Ecker), 91 
*64. Heart of frog from behind {Ecker), 91 
*65. Auricular septum (Ecker), 92 
*66. Bipolar pyriform nerve cells from a frog’s heart, 92 
*67. Scheme of frog’s heart (Brunton), 92 
*68. Stannius’s experiment (Brunton) 92 
*69. Luciani’s groups of cardiac pulsations (Hermann), 96 
*70. Scheme of Kronecker’s frog manometer (Stirling), 97 
*71. Perfusion cannula (Kronecker), 97 
*72. Scheme of Roy’s tonometer (Stirling), 98 
*73. Roy’s tonometer, 98 
*74. Curves of a frog’s heart at different temperatures (Hermann), 99 
75. Cardio-pneumograph of Landois, 102 
76. Apparatus for showing the effects of respiration, 104 
77. Cylindrical vessel filled with water, 106 
78. Cylindrical vessel with manometers, 106 
79. Small artery with its various coats, 109 
*80. Transverse section of an artery and a vein (Stirling), 109 
81. Capillaries injected with silver nitrate, no 
*82. Longitudinal section of a vein at a valve (Cadiat), in 
83. Sphygmometer of Herisson, 115 
84. Scheme of Marey’s sphygmograph, 116 
*85. Marey’s improved sphygmograph (B. Bramwell), 116 
*86. Dudgeon’s sphygmograph (Dudgeon), 117 
*87. Ludwig’s sphygmograph, 117 
88. Scheme of Brondgeest’s pansphygmograph, 118 
89. Scheme of Landois’angiograph, Il8 
90. Haemautographic curve, . . 119 
*91. Sphygmogram of radial artery (Dudgeon), 120 
*92. Radial pulse-curve (Marey), 120 
*93. Irregular pulse, mitral regurgitation, 121 
94. Sphygmograms of various arteries, 122 
*95. Soft and hard pulse-tracings (Gibson and Russell), 123 
*96. Pulse-tracings after amyl-nitrite (Stirling, after Murrell), ... ..... 124 
*97. Aortic regurgitation, 124 
98. Pulsus dicrotus, P. caprizans, P. monocrotus, 125 
*99. Hyperdicrotic pulse, 125 
100. Pulsus alternans, 127 
*101. Pulsus bigeminus (Leech), 127 
102. Curves of the posterior tibial artery 128 
103. Anacrotic pulse-curves, 129 
104. Anacrotic pulse-curves, 13° 
105. Influence of the respiration on the sphygmogram, 130 
106. Pulse-curves during Muller’s and Valsalva’s experiments, 132 
107. Pulsus paradoxus, 132 
108. Various radial curves altered by pressure, 133 
109. Pulse tracings of the radial artery, '. . . 134 
no. Tracings from the posterior tibial and carotid arteries, 135 
in. Apparatus for registering the molar motions of the body, 136 
112. Vibration and heart curves, 136 
113. Ludwig and Fick’s kymographs, 139 
*114. Ludwig’s improved revolving cylinder (Hermann), 14° 
*115. Blood-pressure tracing of the carotid of a dog (Hermann), 141 LIST OF ILLUSTRATIONS. 
FIGURE PAGE 
*116. Fick’s spring manometer, by Hering [Hermann), 142 
117. Fick’s flat spring kymograph, 142 
*118. Scheme of height of blood-pressure {Jolyet), . 143 
*119. Depressor curve of blood-pressure [Stirling), 145 
*120. Blood-pressure and respiration tracings taken simultaneously [Stirling), .... 145 
*121. Blood pressure tracing during stimulation of the vagus [Stirling), 148 
*122. Blood-pressure tracings in different animals {Jolyet), 149 
*123. Apparatus of v. Kries for capillary pressure {C. Ludwig), 149 
*124. Scheme of the blood-pressure, 149 
125. Volkmann’s htemadromometer, 154 
126. Ludwig and Dogiel’s rheometer, 154 
127. Vierordt’s hsematachometer—Dromograph, 155 
128. Photohsematachometer, 156 
*129. Scheme of sectional area (after Yeo), 156 
130. Diapedesis, - j6i 
131. Various forms of venous pulse, 163 
132. Mosso’s plethysmograph, 167 
*133. Section of spleen {Stohr), 170 
*134. Trabeculae of the spleen {Cadiat), 171 
*135. Adenoid tissue of spleen {Cadiat), 171 
*136. Malpighian corpuscle of the spleen {Cadiat), 172 
*137. Elements of splenic pulp {Stohr), 172 
*138. Roy’s spleen oncometer {Cambridge Scientific Instrument Co.), 175 
*139. Fig. 138 shown open {ditto) 173 
*140. Tracing of the splenic curve {Roy), 176 
*141. Thymus gland {Cadiat), 177 
*142. Elements of the thymus gland {Cadiat), 178 
*143. Thyroid gland {Cadiat), 179 
*144. Supra-renal capsule {Stohr), 181 
*145. Human supra-renal capsule {Stohr), 181 
146. Schemata of the circulation, 183 
*147. Human bronchus {Hamilton), 186 
*148. Bronchiole and arteriole {Ziegler), 188 
*149. Scheme of a lung lobule {Stirling), • 189 
*150. Bronchiole and air-cells, 190 
*151. Air-vesicles injected with silver nitrate {Hamilton), 191 
*152. Blood vessels of lung injected, 192 
153. Scheme of the air-vesicles of lung, 193 
*154. Interlobular septa of lung {Hamilton), .... 195 
155. Scheme of Hutchinson’s spirometer, 197 
156. Brondgeest’s tambour and curve, 198 
157. Marey’s stethograph, 199 
158. Pneumatograms, 201 
*159. Cheyne-Stokes’ respiration {Gibson and Russell), 202 
160. Section through diaphragm {Hermann), 205 
161. Action of intercostal muscles, 207 
162. Cyrtometer curve, .... 208 
163. Sibson’s thoracometer, 208 
164. Topography of the lungs and heart, 210 
*165. Nerves of coughing {Stirling), 216 
166. Andral and Gavarret’s respiration apparatus, 217 
167. Scharling’s apparatus 218 
168. Regnault and Reiset’s apparatus, 218 
169. v. Pettenkofer’s apparatus, 220 
170. Valentin and Brunner’s apparatus, 221 
171. Objects found in sputum, 239 
*172. Scheme of the digestive tract {Struthers), 244 
173. Mucous follicle and salivary corpuscles {Schenk), 245 
*174. Section of tonsil {Stohr), 245 
*175. Scheme of glands {Stohr), 246 
176. Histology of the salivary glands 247 
177. Rodded epithelium of a salivary duct, .... 248 
*178. Submaxillary gland of dog {Stirling), .... 248 
*179. Retro-lingual gland of dog {Stirling), 249 XXIV 
LIST OF ILLUSTRATIONS. 
FIGURE PAGE 
*180. Human sub maxillary gland (Heidenhain) 249 
*181. Parotid gland of rabbit at rest (Heidenhain), 250 
*182. Scheme of the nerves of the salivary glands [Stirling), 252 
*183. Secretory and vascular nerves of a salivary gland {Stirling), 253 
*184. Diagram of a salivary gland [Stirling), 256 
*185. Saliva [v. Jaksch), 259 
186. Potato starch, 261 
187. Apparatus for estimation of sugar, 264 
188. Polarization apparatus, 265 
189. Vertical section of a dry tooth, 267 
190. Dentine, 267 
191. Interglobular spaces, 267 
192. Dentine and enamel, 268 
193. Dentine and crusta petrosa, 268 
*194. Vertical section of developing teeth [Stohr), 269 
*195. Transverse section of the jaw of a new-born dog [Stohr), 270 
*196. Lower jaw of child, 271 
*197. Nerves of the tongue, 272 
*198. Vertical section through the head and pharynx, 273 
*199 Scheme of deglutition [Stirling) • 275 
*200. Deglutition curve [Meltzer and Kronecker), 276 
*201. Nerves of deglutition [Stirling), 277 
202. Section of oesophagus [Schenk), ... 279 
203. Perinseum and its muscles 285 
204. Levator ani externus and internus, 286 
*205. Vertical section of Auerbach’s plexus [Cadiat), 286 
*206. Auerbach's plexus (Cadiat) 287 
*207. Meissner’s plexus [Cadiat), 288 
*208. Vertical section of stomach [Stohr), 290 
209. Goblet-cells, 290 
210. Surface section of gastric mucous membrane, 290 
211. Transverse section of a fundus-gland of the stomach, 290 
212. Pyloric gland, 291 
213. Scheme of the gastric mucous membrane, 292 
*214. Junction of stomach and duodenum [Mall), 294 
*215 Pyloric mucous membrane [Heidenhain) 295 
*216. Pyloric glands during digestion [Heidenhain), 295 
*217. Fundus glands during digestion [Heidenhain), 297 
218. Scheme of pyloric fistula [Stirling) 298 
*219. Pancreas, 308 
220. Section of the acini of the pancreas [Hermann), 309 
*221. Section of pancreas stained with picro-carmine [Stirling), 309 
222. Changes of the pancreatic cells during activity, 310 
*223. Pancreas of rabbit [Bernard), 310 
*224. Portal vein and its rootlets (Testut), 317 
*225. Blood-vessels of the liver injected [Stirling), 318 
*226. Section of human liver [Stohr), 319 
227. Scheme of a liver-lobule, 320 
228. Hepatic lobule [Stirling), 321 
*229. Human liver-cells [Cadiat), 321 
*230. Liver-cells during fasting [Hermann), 321 
231. Bile-ducts, 322 
*232. Liver cells [Stirling, after Stolnikow), 322 
233. Various appearances of the liver-cells 323 
*234. Bile-ducts injected [Chrzonszczewsky), 323 
235. Interlobular bile-duct, 324 
*236. Cholesterin [Stirling), 336 
*237. Biliary fistulse [Stirling), 339 
*238. Section of duodenum [Stohr), 345 
*239. Lieberkuhn’s gland [Hermann], 346 
240. Transverse section of Lieberkuhn’s follicles [Schenk), 346 
*241. Schemata of intestinal fistulae [Stirling), 346 
*242. Moreau’s fistula [after Brunton), 348 
243. Bacterium aceti and B. butyricus, 349 LIST OF ILLUSTRATIONS. 
XXV 
FIGURE PAGE 
244. Bacillus, . . . . ; 351 
245. Microscopic appearance of faeces (v. Jaksch), 355 
246. Bacteria of faeces 356 
*247. Reaction of contents of the intestinal tract (Krukenberg), 356 
*248. Scheme of intestinal absorption (Beaunis), 362 
*249. Longitudinal section of small intestine (Schenk) 363 
250. Scheme of an intestinal villus, 364 
251. Injected villus (Schenk), 365 
*252. Villi of small intestine injected (Cadiat') 366 
*253. Duodenum injected (Stohr), 366 
*254. Section of a solitary follicle (Cadiat), 367 
*255. Section of a Peyer’s patch (Cadiat) 367 
*256. Scheme of blood vessels of small intestine (Mall), 368 
257. Section of large intestine (Schenk), 369 
258. Endosmometer, 371 
*259. Transverse section of villus of dog (Heidenhain), 373 
*260. Vertical section of villus absorbing fat {Heidenhain), 377 
*261. Pancreas of rabbit and iacteals during absorption [Bernard), 377 
*262. Lymphatics of arm (Testut), 380 
*263. Silvered lymphatic, 381 
264. Origin of lymphatics in the tendon of diaphragm, 381 
*265. Lymphatics of diaphragm silvered (Ranvier), 382 
*266. Fixed connective-tissue corpuscles (Renaut), 383 
*267. Relation of cell to a fibre (Renaut), 384 
*268. Elastic fibres of omentum (.S'. Mayer) 385 
*269. Elastic fibres of ligamentum nuchse (Kolliker), 385 
270. Perivascular lymphatics, 387 
271. Stomata from lymph-sac of frog, 387 
272. Section of two lymph-follicles, 387 
*273. Scheme of a lymphatic gland (Sharpey), 388 
*274. Adenoid tissue (Stirling), 389 
*275. Lymph knot with mitosis (Ziegler), 389 
276. Part of a lymphatic gland, 390 
*277. Section of the central tendon of diaphragm (Brunton), 397 
*278. Section of fascia lata of a dog (Brunton), 397 
*279. Lymph hearts (Ecker), 398 
280. Water-calorimeter of Favre and Silbermann, 402 
*281. Water-calorimeter of Dulong (Rosenthal), 403 
*282. Clinical thermometers, 407 
283. Walferdin’s metastatic thermometer, 407 
284. Scheme of thermo-electric arrangements, 407 
285. Kopp’s apparatus for specific heat 412 
286. Daily variations of temperature, 414 
287. Acini of the mammary gland of a sheep (Cadiat), 434 
*288. Milk-glands during inaction and secretion, 434 
*289. Milk and colostrum (Stirling), ; . 436 
290. Section of a grain of wheat, 444 
291. Section of a potato, 446 
292. Yeast-cells growing, 448 
293. Composition of animal and vegetable foods, 453 
*294. Fat cells (S. Mayer) 461 
*295. Fat cells with margarine crystals, 461 
*296. Longitudinal section of the kidney (Henle), 492 
*297. Malpighian pyramid (Tyson, after Ludwig), 493 
298. Scheme of the uriniferous tubules (Klein and Noble Smith), 494 
299. Scheme of the structure of the kidney, 495 
300. Glomerulus and renal tubules, 496 
301. Convoluted renal tubule (Heidenhain), 497 
302. Irregular tubule (Tyson, after Klein), ....... 497 
*303. Transverse section of the apex of a Malpighian pyramid (Cadiat), 498 
*304. Development of a glomerulus (Cadiat), 499 
305. Graduated urinary flask, 499 
306. Urinometer, 499 
307. Graduated burette, 5°3 XXVI 
LIST OF ILLUSTRATIONS. 
FIGURE PAGE 
308. Urea and urea nitrate, 504 
*309. Oxalate of urea (1after Beale), 505 
310. Ureameter (Charteris), 506 
*311. Graduated pipette, 507 
*312. Uric acid, .' 508 
313. Kreatinin-zinc-chloride, 511 
*314. Oxalate of lime, . 512 
315. Hippuric acid, 513 
316. Deposit in urine during the “ acid fermentation,” 520 
317. Deposit in ammoniacal urine, 521 
318. Micrococcus urea;, 521 
319. Esbach’s albuminimeter, .... 524 
320. Blood-corpuscles in urine, 525 
321. Peculiar forms of blood-corpuscles, 525 
322. Colored and colorless corpuscles in urine, 525 
323. Blood-corpuscles and triple phosphate, 525 
324. Spectroscopic examination of urine, 526 
*325. Phenyl glucosazon [v. Jaksch), 528 
*326. Picro-saccharimeter [G. Johnson), 529 
*327. Inosit [Beale, after Funke), 530 
328. Cystin and oxalate of lime, 531 
329. Leucin, tyrosin, and ammonium urate, 531 
330. Fungi in urine, 532 
331. Epithelial casts, 532 
332. Blood casts 532 
333. Leucocyte cast, 532 
334. Cast of urate of soda, 532 
335. Finely granular casts, 532 
336. Coarsely granular casts, 533 
337. Hyaline casts, < 533 
338. Calcic carbonate and phosphate, 533 
339. Triple phosphate, 533 
340. Imperfect forms of triple phosphate, 533 
341. Acid ammonium urate 534 
342. Basic magnesic phosphate, .... 534 
*343. Kidney after sulphindigotate (Heidenhain), 538 
*344. Kidney colored with sulphindigotate [Heidenhain) 538 
*345. Kidney cauterized [Heidenhain), 538 
*346. Veins of frog [Ecker), 539 
*347. Oncograph [Cambridge Scientific Instrument Co.), 545 
*348. Oncometer [Stirling, after Roy), 546 
*349. Oncograph [Stirling, after Roy), 546 
*350. Renal oncograph curve [Stirling, after Roy), 547 
*351. Section of ureter [Stohr), 550 
*352. Epithelium of bladder [Stohr), 550 
*353. Transitional epithelium [Stirling), 551 
354. View of the trigone of the bladder, 551 
*355. Nervous mechanism of micturition [Stirling, after Gowers), 555 
*356. Human skin [Kolliker), 557 
*357. Section of epidermis and its nerves [Ranvier), 558 
358. Scheme of the structure of the skin, 559 
*359. Papillae of the skin injected, 560 
360. Transverse section of a nail, 561 
361. Transverse section of a hair-follicle, 562 
362. Longitudinal section of a hair-follicle, 563 
363. Sebaceous gland, 563 
364. Ciliated epithelium, 573 
*365. Pigment and guanin cells of frog [Stirling), 575 
366. Histology of muscular tissue, . . : 577 
*367. Muscular fibre [Ranvier), 579 
*368. Insect’s muscle [Rollett) 580 
*369. Insect’s muscle [Rollett) 580 
*370. Network in muscle [Melland), 581 
371. Tendon attached to a muscle, 581 LIST OF ILLUSTRATIONS. 
FIGURE . PAGE 
*372'. Injected blood-vessels of muscle (.Kolliker), 582 
*373. Red muscle of rabbit injected (Ranvier), 582 
374. Motorial end-plates 582 
*375. Motor end-plates of lizard (Dogiel), 583 
*376. Termination of a nerve in a frog’s muscle (Kiihne), 
*377. Scheme of nerve-ending in muscle (Rollett, after Kiihne), 584 
*378. Smooth muscle, \ 586 
*379. Non-striped muscle-cell (Stirling) 586 
*380. Nerve-ending in smooth muscle (Cadiat), 586 
*381. Tendon-cells, tail of rat {Stirling), 587 
*382. Transverse section of tendon, gold chloride (Renaut), 588 
*383. Termination of nerves in tendon, 589 
*384. Frog with one sciatic artery ligatured {Stirling), 601 
*385. Scheme of the curare experiment {after Rutherford) 601 
*386. Excitability in a frog’s sartorius {Stirling, after Pollitzer), 602 
*387. Excitability in a curarized sartorius {Stirling, after Pollitzer), 602 
388. Microscopic appearances in contracting muscle, 606 
389. Helmholtz’s myograph 607 
*390. Pendulum myograph, 608 
*391. Muscle chamber {Ludwig), 609 
*392. Scheme of the pendulum myograph {Stirling), 609 
*393. Du Bois-Reymond’s spring myograph, ...... 610 
394. Muscle-curve, 610 
*395. Electrical and mechanical response of a muscle {B. Sanderson), 611 
*396. Muscle-curve of pendulum myograph {Stirling), 612 
*397. Method of studying a muscular contraction {after Rutherford), 612 
*398. Effect of make and break induction shocks ( Stirling), 612 
399. Muscle-curves, 613 
400. Muscle-curve, opening and closing shocks, 614 
*401. Veratrin-curve (Stirling) 615 
402. Muscle-curves, tetanus, 616 
*403. Analysis of tetanus {Stirling), 617 
*404. Staircase contractions (Buckrnaster), 618 
405. Curves of voluntary impulses, 618 
*406. Curves of a red and pale muscle {Kronecker and Stirling), 619 
*407. Muscle-curves (Kronecker and Stirling), 619 
*408. Tone-inductorium (Kronecker and Stirling), 620 
409. Pinces myographiques (Marey), 621 
*410. Muscle-curves (Marey), 621 
*411. Height of the lift by a muscle, 623 
*412. Dynamometer, 624 
*413. Curve of elasticity (after Marey), 624 
*414. Curve of elasticity of a muscle (after Marey), 624 
*415. Curve of elasticity (Marey), 624 
*416. Fatigue curve (Stirling), 631 
*417. Fatigue curve (Waller), . . 632 
*418. Ergograph (Mosso), 632 
*419. Ergograph curves (Mosso), 633 
*420. Section of dry bone (Ranvier), 635 
*421. Longitudinal section of bone (Kolliker), 635 
*422. Softened bone with periosteum (Stirling), 636 
*423. Vertical section of articular cartilage (Stirling), 637 
*424. Orders of levers, 640 
*425. Scheme of the action of muscles on bones, 640 
426. Phases of walking, 645 
427. Instantaneous photograph of a person walking, 646 
428. Instantaneous photograph of a runner, 646 
429. Instantaneous photograph of a person jumping, 647 
430. Larynx from the front, "... 650 
431. Larynx from behind, 650 
432. Larynx from behind, 651 
433. Nerves of the larynx, 651 
434. Action of the posterior crico-arytenoid muscle, 652 
435. Action of the arytenoid muscles, 652 XXVIII 
LIST OF ILLUSTRATIONS. 
FIGURE . • PAGE 
436. Action of the lateral crico-arytenoid muscles, 653 
437. Vertical section of the head and neck; laryngoscopic mirrors, 655 
438. Examination of the larynx, 656 
439. Laryngoscopic view of the larynx, 657 
440. View of the larynx during a high note, 657 
441. View of the larynx during a deep inspiration, 657 
442. Rhinoscopy, 658 
443. View of the posterior nares, . 658 
444. Parts concerned in phonation, 661 
• 445. Tumors on the vocal cords, 664 
446. Histology of nervous tissues, 667 
*447. Transverse section of nerve-fibres of the cord [Cadiat), 668 
*448. Sympathetic nerve-fibre [Ranvier), 668 
*449. Medullated nerve-fibre [Stirling), 668 
450. Medullated nerve-fibre, 670 
*451. Medullated nerve-fibres [Schwalbe), . . 670 
*452. Ranvier’s crosses [Ranvier), 671 
453. Transverse section of a nerve, 672 
*454. Cell from the Gasserian ganglion [Schwalbe), 673 
455. Scheme of Rutherford’s experiment [Stirling), 680 
456. Degeneration and regeneration of nerve-fibres 682 
*457. Waller’s experiment [after Dalton), 684 
458. Rheocord of du Bois-Reymond, 689 
459. Scheme of a galvanometer, 689 
*460. Astatic needles [Jamieson), 690 
*461. Large Grove’s battery [Gscheidlen), 691 
*462. Grove’s cell [Jamieson), 691 
*463. Section of a Grove’s cell [Jamieson), 692 
*464. Bunsen’s cell (Jamieson), 692 
*465. Daniell’s cell [Stirling), 693 
*466. Grennet’s battery [Gscheidlen), 693 
*467. Leclanche’s element [Gscheidlen), 693 
*468. Two voltaic cells in series [Jamieson), 694 
*469. Non-polarizable electrodes (Elliott Brothers), 694 
*470. Fleischl’s non-polarizable electrodes [Petzoldt), 694 
*471. Thomson’s galvanometer [Elliott Brothers), 695 
*472. Lamp and scale [Elliott Brothers), 695 
*473. Galvanometer shunt [Elliott Brothers), 696 
*474. Scheme of induced currents [Jamieson), • 696 
*475. Scheme of the induced currents [Hermann), 698 
*476. Helmholtz’s modification [Hermann) 698 
477. Scheme of an induction machine, 699 
*478. Inductorium [Elliott Brothers), 7°° 
*479. Inductorium [Petzoldt), 700 
*480. Stohrer’s apparatus 701 
*481. Friction key [Elliott Brothers) 7o1 
*482. Plug key [Elliott Brothers), 701 
*483. Capillary contact [Kronecker and Stirling), 701 
484. Scheme of the muscle-current, . 7°2 
485. Capillary electrometer, 702 
486. Nerve-muscle preparation, 704 
487. Kiihne’s experiment [Stirling), 705 
488. Electrometer curve, frog’s muscle (Waller), 706 
489. Electrometer curve, frog’s heart (Waller), 7°7 
490. Secondary-contraction, 708 
491. Scheme of Bernstein’s differential rheotome, • . 710 
*492. Differential rheotome, 710 
493. Nerve current in electrotonus, 711 
494. Scheme of electrotonic excitability, 7*6 
495. Method of testing electrotonic excitability, 717 
496. Distribution of an electrical current, 718 
*497. Scheme of law of contraction [Stirling), 72° 
*498. Scheme of Engelmann’s experiment 721 
*499. Scheme for testing velocity of a nerve-impulse, 723 LIST OF ILLUSTRATIONS. 
XXIX 
FIGURE PAGR 
*500. Curves of a nerve-impulse (Marey), 724 
*501. Kiihne’s gracilis experiment, 725 
*502. Sponge rheophores ( Weiss), 726 
*503. Disk rheophore ( Weiss), 726 
*504. Metallic brush (Weiss), 726 
505. Motor points of the arm, 727 
506. Motor points of the arm, 727 
507. Motor points of the leg, 728 
508. Motor points of the leg, . . . • 729 
*509. Electrical organ of skate (Sanderson), 732 
*5x0. Scheme of a reflex act {Stirling), 737 
*511. Schemata of reflex acts {Stirling), 737 
512. Optic chiasma, 739 
*513. Relation of field of vision, retina, and optic tracts {Gosoers), . . 739 
*514. Decussation of the optic tracts (Charcot), . 740 
*515. Scheme of images in squinting {Bristowe), 742 
516. Medulla oblongata, 743 
*5x7. Undersurface of the brain, 744 
518. Connections of the cranial nerves, 746 
519. Sensory nerves of the face, 752 
*520. Scheme of the nerve nuclei in the bulb {Edinger), 755 
521. Motor points of the face and neck, . 757 
*522. Disposition of the semicircular canals {Stirling), 761 
523. Scheme of the branches of vagus and accessorius, 764 
*524. Cardiac nerves of the rabbit {Stirling), 767 
*525. Diagram of a spinal nerve {Ross), 773 
*526. Spinal ganglion {Cadiat), 774 
*527. Nerve-cell from a spinal ganglion {Ranvier), 774 
528. Cutaneous nerves of the arm, 775 
529. Cutaneous nerves of the leg {Henle), 776 
*53°. Visceral nerves of the dog (Gaskell), . • 778 
*531. Isolated sympathetic nerve-cell {Ranvier), 779 
*532. Ear of rabbit {Stirling), 781 
533. Transverse section of the human spinal cord, 787 
*534. Transverse section of the white matter of the cord {Obersteiner), 788 
*535. Multipolar nerve-cells of the cord {Cadiat), 788 
*536. Relation of white and gray matter of the cord (Woroschiloff), 788 
*537. Transverse sections of the spinal cord, 789 
*538. Transverse sections of the human cord {Obersteiner), • ... 790 
*539. Nerve cell from Clarke’s column (Obersteiner), 792 
*540. Transverse section of the cord {Cadiat) 792 
*541. Longitudinal section of the cord {Cadiat), 793 
*542. Multipolar nerve-cell, 793 
*543. Scheme of nerve-fibres in the cord {Obersteiner), 793 
*544. Glia cell {Obersteiner), 794 
*545. Glia cells of cord {Obersteiner) 794 
*546. Blood vessels of spinal cord injected (Obersteiner), 795 
*547. Injected blood-vessels of the cord {Kolliker), 795 
*548. Longitudinal section of cord of embryo-sheep {Kolliker), 796 
*549. Lateral column of rabbit {Kolliker), 796 
*550. Spinal cord of rabbit {Kolliker) 797 
551. Nerve-cell of cord {Kolliker), 797 
*552. Spinal cord of fowl {Ramon y Cayal), 798 
*553. Conducting paths in the cord, 799 
554. Conducting paths in cord, • 800 
*555. Ascending degeneration {Obersteiner), 802 
*556. Descending degeneration (Obersteiner), 802 
*557. Scheme of paths in cord {Stirling), ' 804 
*558. Degeneration paths in the cord {Bratnwell), 804 
*559. Scheme of a reflex arc {Stirling), 806 
*560. Section of a spinal segment {Stirling), • 806 
*561. Propagation of reflex movements {Beaunis), 807 
*562. Effect of section of one half of the cord {Erb), ... 820 
*563. Brain, ventricles, and basal ganglia, 821 XXX 
LIST OF ILLUSTRATIONS. 
FIGURE . PAGE 
564. Scheme of the brain, 822 
*565. Connections of the cerebellum, 823 
566. Course of the pyramidal tracts, 825 
567. Course of motor and sensory paths, 826 
568. Course of sensory impulses, 827 
*569. Diagram of a spinal segment (Bramwell), 828 
*570. Section across the pyramids [Schwalbe), 830 
*571. Section of the medulla oblongata (Schwalbe) 832 
*572. Section of the olivary body [Schwalbe), 832 
*573. Scheme of bulb (Obersteiner), . 834 
*574. Scheme of the respiratory nerves and centres [Rutherford), 839 
*575. Respiratory curves [Stirling), 842 
*576. Effect of stimulus of vagus [Stirling), 843 
*577. Respiratory curves [Stirling), 843 
578. Reflex arrest of respiration [Fredericq), K/|/| 
*579. Inspiratory reflex arrest [Fredericq), 844 
*580. Arrest of respiration [Stirling), 844 
581. Excitation of respiration [Stirling), 846 
*582. Effect on respiration and blood-pressure [Stirling), 847 
*583. Reflex arrest of heart [Jolyet), 849 
*584. Action of vagus on frog’s heart [Stirling), 850 
*585. Arrest of heart by vagus [Stirling), 850 
*586. Scheme of the accelerans fibres [Stirling), 852 
*587. Cardiac plexus of a cat [Rohm) 852 
*588. Effect of accelerans on heart [Jolyet), 853 
589. Effect of stimulation of the sciatic nerve [Jolyet), 857 
590. Effects on blood-pressure [Jolyet), 858 
591. Depressor curve [Stirling), 859 
592. Brain of frog, 869 
*593. Frog with its cerebrum removed [Stirling, after Goltz), 869 
*594. Frog with its cerebrum removed [Stirling, after Goltz), 869 
*595. Brain of pigeon, ’ 869 
*596. Pigeon with its cerebrum removed [after Dalton), 870 
*597. Vertical section of a cerebral convolution [Meynert), 875 
*598. Motor area of a cerebral convolution [Ferrier and B. Lewis), 875 
*599. Cerebral convolution; sensory area [Ferrier and B. Lewis), 875 
*600. Hippocampal convolution [Obersteiner), 876 
*601. Perivascular lymph-spaces (Obersteiner), 877 
*602. Frontal convolution stained by Weigert’s method [Obersteiner), 877 
*603. Cerebral convolution by Golgi’s method, 877 
*604. Cerebral cortex [Cayal), 879 
*605. Blood-vessels of a cerebral convolution injected 880 
*606. Left side of the human brain [Ecker), 881 
607. Inner aspect of right hemisphere [Ecker), 882 
*608. Brain from above [Ecker), 884 
*609. Cerebrum of dog, carp, frog, pigeon, and rabbit, 885 
*610. Relation of the cerebral convolutions to the skull, 888 
*611. Motor areas of a monkey’s brain [Horsley and Schafer), 889 
*612. Motor areas of the marginal convolution [Horsley and Schafer), 889 
*613. Pyscho-optic fibres (Munk), 896 
*614. Motor areas [after Gowers), 901 
*615. Motor centres [after Schafer and Horsley), 901 
*616. Section of a cerebral hemisphere [Horsley), 902 
*617. Innervation of associated muscles [Ross), 902 
*618. Secondary degeneration in one crus [Charcot), 904 
*619. Transverse section of the crus cerebri [Charcot), 904 
*620. Scheme of aphasia [Lichtheim) 907 
*621. Scheme of aphasia [Lichtheim), 907 
*622. Scheme of aphasia [Ross), .... 908 
*623. Relation of the convolutions to the skull [R. IV. Reid), 9x0 
*624. Relation of motor centres to skull [Hare), 910 
*625. Outline markings on skull [Hare), 910 
*626. Basal ganglia and the ventricles, 9x3' 
*627. Transverse section of the right hemisphere [Gegenbaur), 915 LIST OF ILLUSTRATIONS. 
XXXI 
FIGURE PAGE 
*628. Transverse section of the crura cerebri ( Wernicke and Gowers), 917 
*629. Transverse section of the pons (Wernicke), 918 
*630. Course of the fibres in pons (Erb) 918 
*631. Longitudinal section of a human brain (Wiedersheitn), 920 
*632. Section of the cerebellum (Sankey), 921 
*633. Purkinje’s cell (Obersteiner) 921 
*634. Purkinje’s cell (Obersteiner), 922 
*635. Pigeon with its cerebellum removed {Dalton), 923 
*636. Cortex cerebri and its membranes [Schwalbe), 925 
*637. Circle of Willis [Charcot), • x _ 928 
*638. Ganglionic arteries (Charcot), 929 
*639. Corneal corpuscles [Ranvier), 933 
*640. Corneal spaces [Ranvier), 933 
641. Junction of the cornea and sclerotic, 934 
*642. Vertical section of cornea with nerve fibrils [Ranvier), 935 
*643. Horizontal section of cornea with nerve fibrils [Ranvier), 937 
*644. Vertical section of choroid and sclerotic [Stohr), 937 
645. Blood-vessels of the eyeball, 938 
*646. Vertical section of human retina [Cadiat), 940 
647. Layers of the retina 940 
*648. Vertical section of the fovea centralis [Cadiat), 941 
*649. Fibres of the lens [Kolliker), . . . 943 
650. Section of the optic nerve, 944 
651. Action of lenses on light, 947 
652. Refraction of light, 948 
653. Construction of the refracted ray, 948 
654. Optical cardinal points, 949 
655. Construction of the refracted ray, 930 
656. Construction of the image, 930 
657. Refracted ray in several media, 931 
658. Visual angle and retinal image, 952 
659. Scheme of the ophthalmometer, 933 
660. Horizontal section of the eyeball, 954 
661. Scheme of accommodation, 955 
662. Sanson-Purkinje’s images, 936 
*663. Phakoscope [M'Kendrick), 957 
664. Scheiner’s experiment, 937 
665. Refraction of the eye, 938 
666. Myopic eye, 959 
667. Hypermetropic eye, 939 
668. Power of accommodation, 960 
*669. Diagram of astigmatism [Frost), 963 
670. Cylindrical glasses, , 963 
*671. Astigmatic clock [Curry and Paxton), 964 
*672. Scheme of the nerves of the iris [Erb), 966 
*673. Pupilometer [E. Browne), 967 
*674. Pupilometer [Gorham), 967 
*675. Pupilometer (Gorham), 967 
676. Entoptical shadows, 968 
677. Scheme of the original ophthalmoscope, 971 
678. Scheme of the indirect method, 971 
679. Action of a divergent lens in ophthalmoscopy, 972 
680. Action of a divergent lens in ophthalmoscopy, 972 
681. View of the fundus oculi, 972 
*682. Morton’s ophthalmoscope [Curry and Paxton), 972 
*683. Frost’s artificial eye [Frost), 974 
*684. Action of the orthoscope,* 974 
*685. Mariotte’s experiment, 974 
*686. Horizontal section of the right eye, 976 
*687. M’Hardy’s perimeter [Pickard and Curry), 977 
*688. Priestley Smith’s perimeter [Curry and Paxton), 978 
689. Perimetric chart, 979 
*690. Prism and spectrum, 981 
691. Geometrical color cone, 983 LIST OF ILLUSTRATIONS. 
FIGURE PAGE 
692. Action of light-rays on the retina, 984 
*693. Cones of the retina (Stirling, after Engelmann), 988 
*694. Irradiation, 989 
*695. Irradiation, 989 
696. Scheme of the action of the ocular muscles, 993 
*697. Muscles of orbit, 995 
698. Identical points of the retina, 997 
699. The horopter, 997 
*700. Stereoscopic views, 998 
701. Two stereoscopic drawings, 999 
702. Wheatstone’s stereoscope, 1000 
703. Brewster’s stereoscope, 1000 
704. Telestereoscope, • .... 1001 
705. Wheatstone’s pseudoscope, 1001 
706. Rollett’s apparatus, 1002 
*707. Zollner’s lines, 1003 
*708. False estimate of size, • 1003 
709. Section of an eyelid, 1004 
*710. Pineal eye, 1006 
711. Scheme of the organ of hearing, 1008 
712. External auditory meatus, 1010 
713. Left tympanic membrane and ossicles, 1011 
714. Membrana tympani and ossicles, 1011 
715. Tympanic membrane from within, ion 
*716. Ear specula, . . • • 1012 
*717. Toynbee’s artificial membrana tympani, 1013 
718. Right auditory ossicles, 1014 
719. Tympanum and auditory ossicles, 1014 
720. Tensor tympani and Eustachian tube, 1015 
721. Right stapedius muscle, . 1016 
722. Section of Eustachian tube, 1017 
*723. Eustachian catheter and bellows, 1018 
*724. Eustachian catheter in position, 1018 
*725. Ear manometer, 1019 
726. Right labyrinth, 1019 
*727. Aural tuning-fork, 1020 
728. Scheme of the cochlea, 1021 
*729. Interior of the right labyrinth, 1021 
*730. Semicircular canals, 1021 
*731. Section of the macula acustica (Ranvier), 1022 
732. Scheme of the canalis cochlearis, 1023 
*733- Galton’s whistle (Krohne and Sesemann), 1026 
734. Curve of a musical note and its overtones, 1028 
*735. Koenig’s manometric capsule {Koenig), 1029 
*736. Flame-pictures of vowels {Koenig), 1029 
*737. Koenig’s analyzing apparatus {Koenig), 1031 
738. Nasal and pharyngo-nasal cavities, 1036 
*739. Section of the olfactory region {Stohr), 1036 
740. Olfactory cells, 1037 
*741. Olfactory bulb and tract {Obersteiner), 1037 
*742. Olfactory bulb {Obersteiner), 1037 
*743. Olfactory bulb {Cayal) 1038 
*744. Filiform papillae {Stohr), 1040 
*745. Fungiform papillae {Stohr), 1040 
746. Circumvallate papilla and taste-bulbs, 1041 
*747. Papillae foliatae {Stohr), 1041 
748. Vertical section of skin, 1044 
749. Wagner’s touch corpuscle {Ranvier), 1044 
750. Pacini’s corpuscle, . , , 1045 
*751. End-bulb from conjunctiva (Quain), 1045 
*752. Tactile corpuscle from clitoris {Quain) 1045 
753. Ending of nerves in cornea, 1046 
*754. Tactile corpuscles from a duck’s bill {Quain) 1046 
*755. Bouchon epidermique {Ranvier), 1047 LIST OF ILLUSTRATIONS. 
figure' page 
*756. Nerves in a hair-follicle (Ranvier) 1047 
757. .Esthesiometer, 1049 
*758. .Esthesiometer of Sieveking, 1050 
*759. Aristotle’s experiment, 1051 
760. Pressure spots, 1052 
761. Cold-and hot-spots, 1054 
762. Cold- and hot spots, 1054 
763. Topography of temperature-spots, 1056 
764. Ovum of Taenia solium, 1060 
765. Cysticercus, 1060 
766. Taenia solium and mediocanellata, 1060 
767. Cysticerci of Taenia solium 1061 
768. Scolex, 1061 
769. Echinococcus, 1061 
770. Taenia mediocanellata 1061 
*771. Section of testis [Schenk) 1062 
*772. Tubule of testis {Schenk), 1063 
*773. Section of epididymis {Schenk), 1063 
774. Spermatic crystals 1064 
775. Spermatozoa, 1065 
776. Spermatogenesis, 1066 
*777. A cat’s ovary {Hart and Barbour, after Schron), 1067 
778. Section of an ovary {Turner), 1068 
779. Ripe ovum of rabbit, 1068 
780. Ovary, ovarian tubes, and polar globules, 1069 
781. Scheme of a meroblastic ovum, 1070 
782. White and yellow yolk, 1070 
*783. Hen’s egg, .... 1070 
784. Mucous membrane of the uterus, . 1071 
785. Surface section of the uterine mucous membrane, 1071 
*786. Fallopian tube and its annexes {Hen/e), 1072 
*787. Section of Fallopian tube {Schenk), io73 
*788. Uterus before menstruation {J. Williams), 1074 
*789. Uterus after menstruation {J. Williams), 1074 
790. Fresh corpus luteum, io75 
791. Corpus luteum of a cow, 1075 
792. Lutein cells, 1075 
*793. Transverse section of penis, . 1076 
*794. Erectile tissue {Cadiat), 1077 
• 795. The urethra and adjoining muscles, 1078 
796. Formation of polar globules, 1080 
797. Extrusion of a polar globule, 1080 
798. Polar globules, male and female pronucleus, . 1081 
799. Segmentation of a rabbit’s ovum {Quain, after v. Beneden), 1081 
800. Cleavage of the yolk, 1082 
801. Blastodermic vesicle of rabbit ( Quain, after v. Beneden), 1082 
802. The blastoderm, 1082 
*803. Formation of blastula 1083 
804. Ovum of rabbit, 1084 
805. Blastoderm and its evolution, 1084 
*806. Primitive streak {Balfour), 1085 
*807. Transverse section of an embryo newt {Hertwig), 1085 
*808. Vertical section of a blastoderm {Klein), 1086 
*809. Typical nucleated cell {Carnoy), 1087 
*810. Mitosis or indirect nuclear division {Flemming), 1088 
811. Schemata of development, 1089 
*812. Embryo fowl, 2d day {Kolliker), 1090 
*813. Transverse section of an embryo duck {Balfour), 1091 
814. Formation of chorda and coelom, 1092 
*815. Uterine mucous membrane {Coste), 1098 
*816. Placental villi {Cadiat), io99 
817. Section of placenta and uterine wall 1100 
*818. Foetal circulation {Cleland), 1101 
*819 Head of embryo rabbit {Kolliker), . 1104 XXXIV 
LIST OF ILLUSTRATIONS. 
FIGURE FACE 
820. Harelip, 1105 
*821. Meckel’s cartilage (IV. K. Parker) 1105 
822. Formation of the face, 1105 
823. Centres of ossification in the innominate bone, 1107 
*824. Growth of a bone in thickness (Flourens), 1108 
*825. Growth of a bone in length {Flourens), 1108 
826. Development of the heart, 1110 
827. The aortic arches, mi 
828. Veins of the embryo, mi 
829. Development of the veins and portal system, 1112 
830. Development of the intestine, 1113 
831. Development of the lungs, 1113 
832. Formation of the omentum, 1113 
833. Development of the internal generative organs, 1114 
*834. Development ol ova (Idiedersheim), . . 1115 
*835. Development of the external genitals, 1117 
*836. 1 f 1117 
*838 f Changes in the external organs of generation in the female (after Schroeder), -J * J 
*839. J _ . L 1117 
*840. Transverse section of an embryo brain (Kolliker), 1118 
*841. Embryo brain of fowl {Quain, after Mihalkovics) 1119 
*842. Spongioblasts {His), 1120 
*843. Neuroblasts {His), 1120 
844. Development of the eye, 1121 
*845. Development of the vertebrate ear (from Haddon), . . 1121 
[The illustrations indicated by the word Hermann are from Hermann’s Handbuch der 
Physiologie; by Cadiat, from Cadiat’s Traite d’Anatomie Generate; by Ranvier, from Ran- 
vier’s Traite Technique d' Histologie ; by Brunt on, from Brunton’s Text-book of Pharmacology, 
Therapeutics, and Materia Medica; by Schenk, from Schenk’s Grundriss der normalen Histo- 
logie; by Ecker, from Ecker’s Anatomie des Frosches, 2d ed.; by Quain, from Quain’s 
Anatomy; by Stohr, from Stohr’s Lehrbuch der Histologie, Jena, 1887; by Obersteiner, from H. 
Obersteiner’s Anleitung beim Sludium des Baues der nervosen Centralorgane, Wien, 1888; by 
Jolyet, from Viault and Jolyet’s Traite de Physiologie, 1889; by Renaut, from Traite d'histo- 
logie pratique, Paris, 1889.] Introduction. 
The Scope of Physiology and its Relation to other Branches 
of Natural Science. 
Physiology is the science of the vital phenomena of organisms, or, broadly, it is 
the Doctrine of Life. Corresponding to the classification of organisms, we dis- 
tinguish—(i) Animal Physiology ; (2) Vegetable Physiology ; and (3) the Physi- 
ology of the Lowest Living Organisms, which stand on the border line of animals 
and plants, i. e., the so-called Protistce of Haeckel, micro-organisms, and those 
elementary organisms or cells which exist on the same level. 
The object of Physiology is to establish these phenomena, to determine their 
regularity and causes, and to refer them to the general fundamental laws of 
Natural Science, viz., the Laws of Physics and of Chemistry. 
The following Scheme shows the relation of Physiology to the allied branches 
of Natural Science : — 
The science of organized beings or organisms (animals, plants, protistse, and 
elementary organisms). 
BIOLOGY. 
I. Morphology. 
The doctrine of the form of organisms. 
General 
Special 
Morphology. 
Morphology. 
The doctrine of the The doctrine of the 
formed elementary 
parts and organs of 
constituents of or- 
organisms. 
ganisms. 
(Organology— 
(Histology)— 
Anatomy)— 
(a) Histology of Plants. 
(a) Phytotomy. 
(£) Histology of Animals. 
(6) Zootomy. 
II. Physiology. 
The doctrine of the vital phenom- 
ena of organisms 
General 
Special 
Physiology. 
Physiology. 
The docrine of vital 
The doctrine of the 
phenomena in gen- 
activities of the in- 
eral— 
dividual organs— 
(a) Of Plants. 
(a) Of Plants. 
($) Of Animals. 
(£) Of Animals. 
III. Embryology. 
The doctrine of the generation and development of organisms. 
i. History of the development of 
single beings, of the individual 
Morphological part of the 
doctrine of development, 
{e.g.,oi man) from the ovum 
onwards (Ontogeny)— 
(a) In Plants. 
Physiological part of the 
doctrine of development, 
i. e., the doctrine of form 
i. e., the doctrine of the 
in its stages of develop- 
(h) In Animals. 
activity during develop- 
opment— 
(tf) General. 
2. History of the development of 
ment— 
a whole stock of organisms from 
the lowest form of the series 
upwards (Phylogeny)— 
(a) General. 
(h) Special. 
(<5) Special. 
(a) In Plants. 
f (b) In Animals. INTRODUCTION. 
Morphology and Physiology are of equal rank in biological science, and 
a previous acquaintance with Morphology is assumed as a basis for the compre- 
hension of Physiology, since the work of an organ can only be properly under- 
stood when its external form and its internal arrangements are known. De- 
velopment occupies a middle place between Morphology and Physiology ; it 
is a morphological discipline in so far as it is concerned with the description of 
the parts of the developing organism ; it is a physiological doctrine in so far as 
it studies the activities and vital phenomena during the course of development. 
MATTER.—The entire visible world, including all organisms, consists of 
matter, i. e., of substance which occupies space. 
We distinguish ponderable matter which has weight, and imponderable matter 
which cannot be weighed in a balance. The latter is generally termed ether. 
In ponderable materials, again, we distinguish their form, i. e., the nature of 
their limiting surfaces; further, their volume, i. e., the amount of space which 
they occupy; and lastly, their aggregate condition, i. e., whether they are solid, 
fluid, or gaseous bodies. 
Ether.—The ether fills the space of the universe, certainly as far as the most 
distant visible stars. This ether, notwithstanding its imponderability, possesses 
distinct mechanical properties; it is infinitely more attenuated than any known 
kind of gas, and behaves more like a solid body than a gas, resembling a gelati- 
nous mass rather than the air. It participates in the luminous phenomena due 
to the vibrations of the atoms of the fixed stars, and hence it is the transmitter 
of light, which is conducted by means of its vibrations, with inconceivable 
rapidity (42,220 geographical miles per second) to our visual organs (Tyndall). 
Imponderable matter (ether) and ponderable matter are not separated sharply 
from each other; rather does the ether penetrate into all the spaces existing 
between the smallest particles of ponderable matter. 
Particles.—Supposing that ponderable matter were to be subdivided con- 
tinuously into smaller and smaller portions, until we reach the last stage of 
division in which it is possible to recognize the aggregate condition of the mat- 
ter operated upon, we should call the finely-divided portions of matter in this 
state particles. Particles of iron would still be recognized as solid, particles of 
water as fluid, particles of oxygen as gaseous. 
Molecules.—Supposing, however, the process of division of the particles to 
be carried further still, we should at last reach a limit, beyond which, neither 
by mechanical nor by physical means, could any further division be effected. 
We should have arrived at the molecules. A molecule, therefore, is the smallest 
amount of matter which can still exist in a free condition, and which as a unit 
no longer exhibits the aggregate condition. 
Atoms.—But even molecules are not the final units of matter, since every 
molecule consists of a group of smaller units, called atoms. An atom cannot 
exist by itself in a free condition, but the atoms unite with other similar or dis- 
similar atoms to form groups, which are called molecules. Atoms are incapable 
of further subdivision, hence their name. We assume that the atoms are inva- 
riably of the same size, and that they are solid. From a chemical point of view, INTRODUCTION. 
the atom of an elementary body (element) is the smallest amount of the element 
which can enter into a chemical combination. Just as ponderable matter con- 
sists in its ultimate parts of ponderable atoms, so does the ether consist of 
analogous small ether-atoms. 
Ponderable and Imponderable Atoms.—The ponderable atoms within 
ponderable matter are arranged in a definite relation to the ether-atoms. The 
ponderable atoms mutually attract each other, and similarly they attract the 
imponderable ether-atoms; but the ether-atoms repel each other. Hence, in 
ponderable masses, ether-atoms surround every ponderable atom. These masses, 
in virtue of the attraction of the ponderable atoms, tend to come together, but 
only to the extent permitted by the surrounding ether-atoms. Thus the pon- 
derable atoms can never come so close as not to leave interspaces. All matter 
must, therefore, be regarded as more or less loose and open in texture, a con- 
dition due to the interpenetrating ether-atoms, which resist the direct contact 
of the ponderable atoms. 
Aggregate Condition of Atoms.—The relative arrangement of the mole- 
cules, i. e., the smallest particles of matter which can be isolated in a free con- 
dition, determines the aggregate condition of the body. 
Within a solid body, characterized by the permanence of its volume as well 
as by the independence of its form, the molecules are so arranged that they 
cannot readily be displaced from their relative positions. 
Fluid bodies, although their volume is permanent, readily change their 
shape, and their molecules are in a condition of continual movement. 
When this movement of the molecules takes so wide a range that the indi- 
vidual molecules fly apart, the body becomes gaseous, and as such is character- 
ized by the instability of its form as well as by the changeableness of its volume. 
Physics is the study of these molecules and their motions. 
Forces. 
i. Gravitation — Work done.—All phenomena appertain to matter. 
These phenomena are the appreciable expression of the forces inherent in matter. 
The forces themselves are not appreciable; they are the causes of the phenomena. 
Gravitation.—The law of gravitation postulates that every particle of pon- 
derable matter in the universe attracts every other particle with a certain force. 
This force is inversely as the square of the distance. Further, the attractive 
force is directly proportional to the amount of the attracting matter, without 
any reference to the quality of the body. We may estimate the intensity of 
gravitation by the extent of the movement which it communicates to a body 
allowed to fall, for one second, through a given distance, in a vacuous space. 
Such a body will fall in vacuo at the surface of the earth 9.809 metres per 
second. This fact has been arrived at experimentally. 
Let us = 9.809 metres, the final velocity of the freely falling body at the end of 
one second. The velocity, V, of the freely falling body is proportional to the time, (, so that 
V=gt (1); 
1. <?., at the end of the 1st sec., and V = g, 1 — g = 9.809 M—the distance traversed— 
s= It2 (2); 
2 INTRODUCTION. 
i. e., the distances are as the squares of the times. Hence, from (i) and .(2) it follows (by 
eliminating t) that— 
V = V 2gs (3)- 
The velocities are as the square roots of the distances traversed— 
V2 
Therefore - - =s (4). 
2<? 
The freely falling body, and in fact every freely moving body, possesses 
kinetic energy, and is in a certain sense a magazine of energy. The kinetic 
energy of any moving body is always equal to the product of its weight (esti- 
mated by the balance), and the height to which it would rise from the earth, if 
it were thrown from the earth with its own velocity. 
Let W represent the kinetic energy of the moving body, and P its weight, then W = P, s, so 
that from (4) it follows that— 
w = Pv (5). 
Hence, the kinetic energy of a body is proportional to the square of its 
velocity. 
Work.—If a force (pressure, strain, tension) be so applied to a body as to 
move it, a certain amount of work is performed. The amount of work is equal 
to the product of the amount of the pressure or strain which moves the body, 
and of the distance through which it is moved. 
Let K represent the force acting on the body, and S the distance, then the work W = KS. 
The attraction between the earth and any body raised above it is a source of work. 
It is usual to express the value of K in kilogrammes, and S in metres, so that 
the “ unit of work ” is the kilogram-metre, i. e., the force which is required 
to raise 1 kilo, to the height of 1 metre. 
2. Potential Energy.— The Transformation of Potential into Kinetic Energy, 
and conversely: Besides kinetic energy, there is also “potential energy,” or 
energy of position. By this term is meant various forms of energy, which are 
suspended in their action, and which, although they may cause motion, are not 
in themselves motion. A coiled watch-spring kept in this position, a stone 
resting upon a tower, are instances of bodies possessing potential energy, or the 
energy of position. It requires merely a push to develop kinetic from the 
potential energy, or to transform potential into kinetic energy. 
Work, w, was performed in raising the stone to rest upon the tower. 
w = p, s, where p = the weight and j = the height, 
p = m .g, is = the product of the mass (»t), and the force of gravity (_»■), so that w = m g s. 
This is at the same time the expression for the potential energy of the stone. 
This potential energy may readily be transformed into kinetic energy by merely 
pushing the stone so that it falls from the tower. The kinetic energy of the 
stone is equal to the final velocity with which it impinges upon the earth. 
V =1/2g s (see above (3) ). 
V2 = 2g s. 
v/V2 = 2 mgs. 
m\T2 
— V 2 = mgs. 
2 6 
m g s was the expression for the potential energy of the stone while it was still INTRODUCTION. 
XXXIX 
m . . 
resting on the height; —V2 is the kinetic energy corresponding to this potential 
energy (.Briicke). 
Potential energy may be transformed into mechanical energy under the most 
varied conditions; it may also be transferred from one body to another. 
The movement of a pendulum is a striking example of the former. When the pendulum is 
at the highest point of its excursion, it must be regarded as absolutely at rest for an instant, and 
as endowed with potential energy, thus corresponding with the raised stone in the previous 
instance. During the swing of the pendulum this potential energy is changed into kinetic 
energy, which is greatest when the pendulum is moving most rapidly towards the vertical. As 
it rises again from the vertical position, it moves more slowly, and the kinetic energy is 
changed into potential energy, which once more reaches its maximum when the pendulum 
comes to rest at the utmost limit of its excursion. Were it not for the resistances continually 
opposed to its movements, such as the resistance of the air and friction, the movement of the 
pendulum, due to the alternating change of kinetic into potential energy and vice versa, would 
continue uninterruptedly, as with a mathematical pendulum. Suppose the swinging ball of the 
pendulum, when exactly in a vertical position, impinged upon a resting but movable sphere, 
the potential energy of the ball of the pendulum would be transferred directly to the sphere, 
provided that the elasticity of the ball of the pendulum and the sphere were complete; the 
pendulum would come to rest, while the sphere would move onward with an equal amount of 
kinetic energy, provided there were no resistance to its movement. This is an example of the 
transference of kinetic energy from one body to another. Lastly, suppose that a stretched 
watch-spring on uncoiling causes another spring to become coiled ; and we have another example 
of the transference of kinetic energy from one body to another. 
The following general statement is deducible from the foregoing examples : — 
If, in a system, the individual moving masses approach the final position of 
equilibrium, then in this system the sum of the kinetic energies increases ; if, on 
the other hand, the particles move away from the final position of equilibrium, 
then the sum of the potential energies is increased at the expense of the kinetic 
energies, i. e., the kinetic energies diminish (Briicke). 
The pendulum, which, after swinging from the highest point of its excursion, approaches the 
vertical position, i e., the position of equilibrium of a passive pendulum, has in this position 
the largest amount of potential energy; as it again ascends to the highest point of its excursion 
on the other side, it again gradually receives the maximum of potential energy at the expense 
of the gradually diminishing movement, and therefore of the kinetic energy. 
3. Heat.—Its Relation to Potential and Kinetic Energy.—If a lead weight 
be thrown from a high tower to the earth, and if it strike an unyielding sub- 
stance, the movement of the mass of lead is not only arrested, but the kinetic 
energy (which to the eye appears to be lost) is transformed into a lively vibra- 
tory movement of the atoms. When the lead meets the earth, heat is produced. 
The amount of heat produced is proportional to the kinetic energy, which is trans- 
formed through the concussion. At the moment when the lead weight reaches 
the earth, the atoms are thrown into vibrations; they impinge upon each other; 
then rebound again from each other in consequence of their elasticity, which op- 
poses their direct juxtaposition ; they fly asunder to the maximum extent per- 
mitted by the attractive force of the ponderable atoms, and thus oscillate to and 
fro. All the atoms vibrate like a pendulum, until their movement is communi- 
cated to the ethereal atoms surrounding them on every side, i. e., until the heat 
of the heated mass is ‘ *' radiated.’ ’ Heat is thus a vibratory movement of the atoms. 
As the amount of heat produced is proportional to the kinetic energy, which 
is transformed through the concussion, we must find an adequate measure for 
both forces. 
Heat-Unit.—As a standard of measure of heat, we have the “ heat-unit” or INTRODUCTION. 
calorie. The “heat-unit” or calorie is the amount of energy required to raise 
the temperature of i gram of water i° centigrade. The “ heat-unit” corresponds 
to 425.5 gram-metres, i.e., the same energy required to heat 1 gram of water 
i° C. would raise a weight of 425.5 grams to the height of 1 metre ; or, a weight 
of 425.5 grams, if allowed to fall from the height of 1 metre, would by its con- 
cussion produce as much heat as would raise the temperature of 1 gram of water 
i° C. The “mechanical equivalent ” of the heat-unit is, therefore, 425.5 
gram-metres. 
It is evident that from the collision of moving masses an immeasurable amount of heat can 
be produced. Let us apply what has already been said to the earth. Suppose the earth to be 
disturbed in its orbit, and suppose further that, owing to the attraction of the sun, it were to 
impinge on the latter (whereby, according to J. R. Mayer, its final velocity would be 85 
geographical miles per second), the amount of heat produced by the collision would be equal to 
that produced by the combustion of a mass of pure charcoal more than 5000 times as heavy 
(Julius Robert Mayer, Helmholtz). 
Thus, the heat of the sun itself can be produced by the collision of masses of cold matter. 
If the cold matter of the universe were thrown into space, and there left to the attraction of its 
particles, the collision of these particles would ultimately produce the light of the stars. At 
the present time, numerous cosmic bodies collide in space, while innumerable small meteors 
(94,000 to 188,000 billions of kilos, per minute) fall into the sun. The force of gravity is 
perhaps, in fact, the only source of all heat (J. R. Mayer, Tyndall). 
We have a homely example of the transformation of kinetic energy into heat in the fact that a 
blacksmith may make a piece of iron red-hot by hammering it. Of the conversion of heat into kinetic 
energy we have an example in the hot watery vapour (steam) of the steam-engine raising the 
piston. An example of the conversion of potential energy into heat occurs in a metallic spring, 
when it uncoils and is so placed as to rub against a rough surface, producing heat by friction. 
4. Chemical Affinity : Relation to heat.—Whilst gravity acts upon the 
particles of matter without reference to the composition of the body, there is 
another atomic force which acts between atoms of a chemically different nature; 
this is chemical affinity. This is the force in virtue of which the atoms of 
chemically different bodies unite to form a chemical compound. The force 
itself varies greatly between the atoms of different chemical bodies; thus we 
speak of strong chemical affinities and weak affinities. Just as we were able to 
estimate the potential energy of a body in motion from the amount of heat 
which was produced when it collided with an unyielding body, so we can 
measure the amount of heat which is formed when the atoms of chemically 
different bodies unite to form a chemical compound. As a rule, heat is formed 
when separate chemically-different atoms form a compound body. When, in 
virtue of chemical affinity, the atoms of 1 kilo, of hydrogen and 8 kilos, of 
oxygen unite to form the chemical compound water, an amount of heat is 
thereby evolved which is equal to that produced by a weight of 47,000 kilos, 
falling and colliding with the earth from a height of 1000 feet above the surface 
of the earth If 1 gram of H be burned along with the requisite amount of O 
to form water, it yields 34,460 heat-units or calories: and 1 gram carbon 
burned to carbonic acid (carbon dioxide) yields 8080 heat-units. Wherever, 
in chemical processes, strong chemical affinities are satisfied, heat is set free, i. e., 
chemical affinity is changed into heat. Chemical affinity is a form of potential 
energy obtaining between the most different atoms, which during chemical 
processes is changed into heat. Conversely, in those chemical processes where 
strong affinities are dissolved, and chemically-united atoms thereby pulled asun- 
der, there must be a diminution of temperature, or, as it is said, heat becomes INTRODUCTION. 
latent—that is, the energy of the heat which has become latent is changed into 
chemical energy, and this, after decomposition of the compound chemical body, 
is again represented by the chemical affinity between its isolated different atoms. 
LAW OF THE CONSERVATION OF ENERGY.—Julius Robert 
Mayer and Helmholtz have established the important law that, in a system 
which does not receive an influence and impression from without, the sum of 
all the forces acting within it is always the same. The various forms of energy 
can be transformed one into the other, so that kinetic energy may be transformed 
into potential energy and vice versa, but there is never any part of the energy lost. 
The transformation takes place in such measure that, from a certain definite 
amount of one form of energy, a definite amount of another can be obtained. 
The various forms of energy acting in organisms occur in the following 
modifications:— 
1. Molar motion (ordinary movements), as in the movements of the whole 
body, of the limbs, or of the intestines, and even those observable microscopi- 
cally in connection with cells. 
2. Movements of atoms as heat.—We know, in connection with the 
vibration of atoms, that the number of vibrations in the unit of time deter- 
mines whether the oscillations appear as heat, light, or chemically-active vibra- 
tions. Heat-vibrations have the smallest number, while chemically-active vibra- 
tions have the largest number, light-vibrations standing between the two. In 
the human body we only observe heat-vibrations, but some of the lower animals 
are capable of exhibiting the phenomena of light. 
In the human organism the molar movements in the individual organs are 
constantly being transformed into heat, e. g., the kinetic energy in the organs 
of the circulation is transformed by friction into heat. The measure of this is 
the “unit of work” = i gram-metre, and the “unit of heat” — 425.5 
gram metres. 
3. Potential Energy.—The organism contains many chemical compounds 
which are characterized by the great complexity of their constitution, by the 
imperfect saturation of their affinities, and hence by their great tendency to 
split up into simpler bodies. 
The body can transform the potential energy into heat as well as into kinetic 
energy, the latter always in conjunction with the former, but the former always 
by itself alone. The simplest measure of the potential energy is the amount of 
heat which can be obtained by complete combustion of the chemical compounds 
representing the potential energy. The number of work-units can then be 
calculated from the amount of heat produced. 
4. The phenomena of electricity, magnetism, and diamagnetism may 
be recognized in two directions, as movements of the smallest particles, which 
are recognized in the glowing of a thin wire when it is traversed by strong elec- 
trical currents (against considerable resistance), and also as molar movement, as 
in the attraction or repulsion of the magnetic needle. Electrical phenomena 
are manifested in our bodies by muscle, nerve, and glands, but these phenomena 
are relatively small in amount when compared with the other forms of energy. 
It is not improbable that the electrical phenomena of our bodies become almost INTRODUCTION. 
conpletely transformed into heat. As yet experiment has not determined with 
accuracy a “unit of electricity” directly comparable with the “ heat-unit ” 
and the “work-unit.” 
It is quite certain that within the organism one form of energy can be trans- 
formed into another form, and that a certain amount of one form will yield a 
definite amount of another form ; further, that new energy never arises sponta- 
neously, nor is energy already present ever destroyed, so that in the organism 
the law of the conservation of energy is continually in action. 
ANIMALS AND PLANTS.—The animal body contains a quantity of 
chemically-potential energy stored up in its constituents. The total amount of 
the energy present in the human body might be measured by burning completely 
an entire human body in a calorimeter, and thereby determining how many 
heat-units are produced when it is reduced to ashes (see Animal Heat). 
The chemical compounds containing the potential energy are characterized 
by the complicated relative position of their atoms, by a comparatively imper- 
fect saturation of the affinities of their atoms, by the relatively small amount of 
oxygen which they contain, by their great tendency to decomposition, and the 
facility with which they undergo decomposition. 
If a man were not supplied with food he would lose 50 grams of his body- 
weight every hour; the material part of his body, which contains the potential 
energy, is used up, oxygen is absorbed, and a continual process of combustion 
takes place ; by the process of combustion simpler substances are formed from 
the more complex compounds, whereby potential is converted into kinetic 
energy. It is immaterial whether the combustion is rapid or slow; the same 
amount of the same chemical substances always produces the same amount of 
kinetic energy, i. <?., of heat. 
A person, when fasting, experiences after a certain time the disagreeable feel- 
ing of exhaustion of his reserve of potential energy, hunger sets in, and he takes 
food. All food for the animal kingdom is obtained, either directly or indirectly, 
from the vegetable kingdom. Even carnivora, which eat the flesh of other ani- 
mals, only eat organized matter which has been formed from vegetable food. 
The existence of the animal kingdom presupposes the existence of the vege- 
table kingdom. 
All substances, therefore, necessary for the food of animals occur in vegetables. 
Besides water and the inorganic constituents, plants contain, amongst other 
organic compounds, the following three chief representatives offood-stuffs—fats, 
carbohydrates, and proteids. 
All these contain stores of potential energy, in virtue of their complex 
chemical constitution. 
The fats contain 
CnH.2n.10(0H) = fatty acids 
+ CaH5(OH)s — glycerin 
(§ 251)* 
The carbohydrates contain :—C6H10O5 (§252). 
c. 51-5-54-5 
H. 6.9- 7.3 
N. 15.2-17.0 
O. 20.6-23.5 
S. 0.3- 2.0 
The proteids contain per cent. 
(§§ 248 and 249). INTRODUCTION. 
A man who takes a certain amount of this food adds thereto oxygen from 
the air in the process of respiration. Combustion or oxidation then takes 
place, whereby chemically-potential energy is transformed into heat. 
It is evident that the products of this combustion must be bodies of simpler 
constitution—bodies with less complex arrangement of their atoms, with the 
greatest possible saturation of the affinities of their atoms, of greater stability, 
partly rich in O, and possessing either no potential energy, or only very little. 
These bodies are carbon dioxide, C02; water, H20 ; and as the chief rep- 
resentative of the nitrogenous excreta, urea (CO(NH2)2), which has still a small 
amount of potential energy, but which outside the body is readily converted 
into C02 and ammonia (NH3). 
The human body is an organism in which, by the phenomena of oxidation, 
the complex nutritive materials of the vegetable kingdom, which are highly 
charged with potential energy, are transformed into simple chemical bodies, 
whereby the potential energy is transformed into the equivalent amount of 
kinetic energy (heat, work, electrical phenomena). 
But how do plants form these complex food-stuffs so rich in potential energy ? 
It is plain that the potential energy of plants must be obtained from some other 
form of energy. This potential energy is supplied to plants by the rays of the 
sun, whose chemical light-rays are absorbed by plants. Without the rays of the 
sun there could be no plants. Plants absorb from the air and the soil C02,H20, 
NH3, and N, of which carbon dioxide, water, and ammonia (from urea) are 
also produced by the excreta of animals. Plants absorb the kinetic energy of 
light from the sun1 s rays and transform it into potential energy, which is accumu- 
lated during the growth of the plant in its tissues, and in the food-stuffs pro- 
duced in them during their growth. This formation of complex chemical com- 
pounds is accompanied by the simultaneous excretion of O. 
Occasionally, kinetic energy, such as we universally meet with in animals, is liberated in plants. 
Many plants develop considerable quantities of heat in their flowers, e.g., the arum tribe. We 
must also remember that during the formation of the solid parts of plants, when fluid juices are 
changed into solid masses, heat is set free. In plants, under certain circumstances, O is absorbed, 
and C02 is excreted, but these processes are so trivial as compared with the typical condition in 
the vegetable kingdom, that they may be regarded as of small moment. 
Plants, therefore, are organisms which, by a reduction process, transform 
simple stable combinations into complex compounds, whereby potential solar 
energy is transformed into the chemically-potential energy of vegetable tissues. 
Animals are living beings, which by oxidation decompose or break up the 
complex grouping of atoms manufactured by plants, whereby potential is trans- 
formed into kinetic energy. Thus, there is a constant circulation of matter 
and a constant exchange of energy between plants and animals. All the energy 
of animals is derived from plants. All the energy of plants arises from the sun. 
Thus the sun is the cause, the original source of all energy in the organism, 
i. e., of the whole of life. 
As the formation of solar heat and solar light is explicable by the gravitation 
of masses, gravity is perhaps the original form of energy of all life. 
We may thus represent the formation of kinetic energy in the animal body INTRODUCTION. 
from the potential energy of plants. Let us suppose the atoms of the sub- 
stances formed in organisms, as simply small bodies, balls, or blocks. As long 
as these lie in a single layer, or in a few layers, upon the surface, there is a stable 
arrangement, and they continue to remain at rest. If, however, an artificial 
tower be built of these blocks, so that an unstable erection is produced, and the 
same tower be afterwards knocked down, then for this purpose we require—(i) 
the motor power of the workman who lifts and carries the blocks; (2) a blow or 
other impulse from without applied to the unstable structure—when the atoms 
will fall together, and as they fall collide with each other and produce heat. 
Thus, the energy employed by the workman is again transformed into the last- 
named form of energy. 
In plants the complex unstable building of the groups of atoms is carried on, 
the constructor being the sun. In animals, which eat plants, the complex groups 
of the atoms are tumbled down, with the liberation of kinetic energy. 
Vital Energy and Life.—The forces which act in organisms, in plants 
and animals are exactly the same as are recognizable as acting in dead matter. 
A so-called “vital force,” as a special force of a peculiar kind, causing and 
governing the vital phenomena of living beings, does not exist. The forces of 
all matter, of organized as well as unorganized, exist in connection with their 
smallest particles or atoms. As, however, the smallest particles of organized 
matter are, for the most part, arranged in a very complicated way, compared 
with the much simpler composition of inorganic bodies, so the forces of the 
organism connected with the smallest particles yield more complicated phe- 
nomena and combinations, whereby it is excessively difficult to ascribe the vital 
phenomena in organisms to the simple fundamental laws of physics and chemistry. 
The Exchange of Material, or Metabolism (“ Stoffwechsel") as a 
Sign of Life.—Nevertheless, there appears to be a special exchange of matter 
and energy peculiar to living beings. This consists in the capacity of organ- 
isms to assimilate the matter of their surroundings, and to work it up into their 
own constitution, so that it forms for a time an integral part of the living being, 
to be given off again. The whole series of phenomena is called metabolism 
or “ Stoffwechsel,” which consists in the introduction, assimilation, integra- 
tion, and excretion of matter. 
We have already shown that the metabolism of plants and that of animals are 
quite different. The processes, as already described, actually occur in the 
typical higher plants and animals. 
But there is a large group of organisms which, throughout their entire organi- 
zation, exhibit so low a degree of development, that by some observers they 
are considered as undifferentiated “ground-forms.” They are regarded as 
neither plants nor animals, and are the most simple forms of animated matter. 
Haeckel has called these organisms Protistae, as being the original and primi- 
tive forms. 
We must assume that, corresponding with their simpler vital conditions, their 
metabolism is also simpler, but on this point we still require further observations 
and experiments. Physiology of the Blood. 
[The blood is aptly described by Claude Bernard as an internal medium 
which acts as a “go-between ” or medium of exchange for the outer world 
and the tissues. Into it are poured those substances which have been subjected 
to the action of the digestive fluids, and in the lungs or other respiratory organs 
it receives oxygen. It thus contains new substances, but in its passage 
through the tissues it gives up some of these new substances, and receives in ex- 
change certain waste products, which have to be got rid of. Its composition is 
thus highly complex. Besides carrying the new nutrient fluids to the tissues, it is 
also the great oxygen-carrier, as well as the medium by which some of the waste 
products, e.g., C02, urea, are removed from the tissues, and brought to the organs, 
e.g., the lungs, kidneys, skin, which eliminate them from the body. It is at once 
a great pabulum-supplying medium and a channel forgetting rid of useless ma- 
terials. As the composition of the organs through which the blood flows varies, 
it is evident that its composition must vary in different parts of the circulatory 
system; and it also varies in the same individual under different conditions. 
Still with slight variations, there are certain general physical, histological, and 
chemical properties which characterize blood as a whole.] 
i. PHYSICAL PROPERTIES.—(i) Color.—The color of blood 
varies from a bright scarlet-red in the arteries to a deep, dark, bluish-red in the 
veins. Oxygen (and, therefore, the air) makes the blood bright red ; want of 
oxygen makes it dark. Blood free from oxygen (and also venous blood) is 
dichroic—i. e., by reflected light it appears dark red, while by transmitted light 
it is green. [Arterial blood is monochroic.] 
In thin layers blood is opaque, as is easily shown by shaking blood so as to form 
bubbles, or by allowing blood to fall upon a plate with a pattern on it, and pour- 
ing it off again. [Printed matter cannot be read through a thin layer of blood 
spread on a glass slide.] Blood behaves, therefore, like an “ opaque color,” as its 
coloring matter is suspended in the form of fine particles—the blood-corpuscles. 
Hence, it is possible to separate the coloring-matter from the fluid part of the blood by 
filtration. This is accomplished by mixing the blood with the fluids which render the blood- 
corpuscles sticky or rough. If mammalian blood be treated with one-seventh of its volume of 
solution of sodic sulphate, or if frog’s blood be mixed with a 2 per cent, solution of sugar (Joh. 
Milller) and filtered, the Shrivelled corpuscles, now robbed of part of their water, remain upon 
the filter. 
(2) Reaction.—The reaction is alkaline, owing to the presence of disodic 
phosphate, Na2HP04, and bicarbonate of soda. After blood is shed, its alka- 
linity rapidly diminishes, and this occurs more rapidly the greater the alkalinity 
of the blood. This is due to the formation of an acid, in which, perhaps, the 
colored corpuscles take part, owing to the decomposition of their coloring 
matter. A high temperature and the addition of an alkali favor the formation 
of the acid (N. Zuntz). 2 
ALKALINITY OF THE BLOOD. 
[Sec. I. 
The alkaline reaction of blood is diminished: (a) by great muscular exertion, owing to the 
formation of a large amount of acid in the muscles; (/3) during coagulation ; (y) in old blood, 
or blood dissolved by water from old blood-stains, such blood being usually acid; fresh cruor 
has a stronger alkaline reaction than serum; (<5) after the prolonged use of soda the alkalinity 
is increased, after the use of acids it is decreased. In women and children the alkalescence is 
less than in man, and it is less in lying-in women than in pregnant women {Peiper). 
Methods.—Owing to the color of the blood we cannot employ ordinary litmus paper to test 
its reaction. One of the following methods may be used : (i) Moisten a strip of glazed red 
litmus paper with solution of common salt, and allow a drop of blood to fall on the paper; 
than rapidly wipe it off before its coloring matter has time to penetrate and tinge the paper 
iyZuntz). (2) Liebreich used thin plates of plaster-of-Paris of a perfectly neutral reaction. 
These are dried, and afterwards moistened with a neutral solution of litmus. When a drop of 
blood is placed upon the porous plate, the fluid part of the blood passes into it, the cor- 
puscles are then washed off with water, and the altered color of the litmus-stained slab is 
apparent. [(3) Schafer uses dry faintly-reddened glazed litmus paper, and on it is placed a 
drop of blood, which is wiped off after a few seconds. The place where the blood rested is 
indicated by a blue patch upon a red or violet ground.] 
Estimation of the Alkalinity.—A very dilute solution of tartaric acid (1 cubic centimetre 
combines with 3.1 milligrams of soda, i. e., I litre of water contains 7.5 grams of crystallized 
tartaric acid) is added to blood until a blue litmus paper is turned red (by Zuntz’s method). 
100 grams of rabbit’s blood have an alkalinity corresponding to 150 milligrams of soda; the 
blood of carnivora to about 180 milligrams (Lassar), while 100 c. c. of normal human blood have 
an alkalinity equal to 260-300 milligrams of soda (v. Jakscfi). 
The following method can be used with a few drops of blood: To neutralize the blood, tar- 
taric acid in the above concentration is used. Prepare the following mixtures by mixing the 
tartaric acid solution with a concentrated neutral solution of sodic sulphate, and then adding 
sodic sulphate until the mixture is completely saturated. I, 10 parts of solution of tartaric 
acid to 100 parts of concentrated sodic sulphate solution ; II, 20 parts tartaric acid solution ta 
90 sodic sulphate solution ; III, contains these substances in the proportion of 30 to 80; IV, 
40 to 70; V, 50 to 60; VI, 60 to 50; VII, 70 to 40; VIII, 80 to 30; IX, 90to 20; and 
X, 100 to 10. Excess of sodic sulphate is present in all the flasks. 
A known volume of the blood to be investigated is mixed with an equal volume of each of 
the mixtures, in a small tube, which is made by drawing out a glass tube 1 millimetre in 
diameter to a fine point. To calibrate the tube, suck up water, say, to the height of 8 mm., 
make a mark on the tube with a fine file, then suck up the water until its lower level corre 
sponds with the mark. Again mark the upper limit of the water. To test the blood, suck a 
drop of the mixture I up to the level of the first mark on the glass pipette, and, after wiping 
its point, suck up an equal quantity of blood. Again clean the point of the pipette, and blow 
its contents into a watch-glass ; then mix, and test the reaction with sensitive violet-colored 
litmus paper. Proceed in the same way with the several mixtures, II to X, until the 
alkaline reaction disappears or the acid appears. The narrow strips of litmus paper are dipped 
into each of the mixtures, the corpuscles remain in the wetted part of the paper, while the 
fluid permeates further and shows the reaction. As a rule, the degree of alkalinity in human 
blood of adults corresponds to VI, and in children to IV. Human blood can be sucked directly 
from a small wound made by a needle, either by attaching an elastic tube or a small hypodermic 
syringe to the pipette (Landois). 
Pathological.—The alkalinity is increased during persistent vomiting, and decreased in 
pronounced anaemia, cachexia, uraemia, rheumatism, high fever, diabetes, in poisoning with CO, 
degenerations of the liver, and cholera. [Immediately before death by cholera it may be acid 
(Cantani) 
(3) Odor .—Blood emits a peculiar odor, the halitus sanguinis, which differs 
in animals and man. 
It depends upon the presence of volatile fatty acids. If concentrated sulphuric acid 
vols.] be added to blood, whereby the volatile fatty acids are set free from their combinations 
with alkalies, the characteristic odor, somewhat similar to that of butyric acid, becomes much 
more perceptible. 
(4) Taste.—Blood has a saline taste, depending upon the salts dissolved in 
the fluid of the blood. 
(5) Specific Gravity.—The specific gravity is 1056-1059 in man 1051- 
1055 in woman ; in children less. The specific gravity of the blood-corpuscles 
is 1105, that of the plasma 1207. Hence the corpuscles tend to sink. Sec. I.] 
MICROSCOPIC EXAMINATION OF BLOOD. 
3 
Clinical Method.—A thin glass tube is drawn out till it is of small calibre, and then bent at 
a right angle, and closed above with a caoutchouc cap, thus forming a small pipette. With 
this pipette, suck up a drop of freshly-drawn blood obtained by pricking the finger. The fine 
capillarv-iube is at once immersed in a solution of sodic sulphate, and a drop of the blood 
expressed into the saline solution. It is necessary to prepare several solutions of sodic sulphate 
with specific gravities varying from 1050-1070. The solution in which the corpuscles remain 
suspended indicates the specific gravity of the blood {Roy, Landois). 
The drinking of water and hunger diminish the specific gravity temporarily, while thirst and 
the digestion of dry food raise it. If blood be passed through an organ artificially, its specific 
gravity rises in consequence of the absorption of dissolved matters and the giving off of water. 
It falls after hemorrhage, and is diminished in badly-nourished individuals. [By working 
with solutions of glycerine, Jones finds that it is the highest at birth, and at a minimum 
between the second week and the second year; it rises gradually until the 35th-45th year. It 
is usually higher in the male than the female, is diminished by pregnancy, the ingestion of solid 
or liquid food, and gentle exercise.] 
[(6) Temperature.—Blood is viscid, and its temperature varies from 36.5° C. 
(97.70 F.) to 37.8° C. (ioo° F.). The warmest blood in the body is that of the 
hepatic vein (§ 210).] 
2. MICROSCOPIC EXAMINATION.—[Blood, when examined tbv 
the microscope, is seen to consist of an enormous number of corpuscles— 
colored and colorless—floating in a transparent fluid, the plasma, or liquor 
sanguinis, together with the blood-plates or platelets.] 
Fig. 1. 
A, human colored blood-corpuscles—1, on the flat; 2, on edge; 3, rouleau of colored cor- 
puscles. B, amphibian colored blood-corpuscles—1, on the flat; 2, on edge. C, ideal 
transverse section of a human colored blood-corpuscle magnified 5000 times linear—a,b, 
diameter; c, d, thickness. 
I. Human Red Blood-Corpuscles.—(a) Form.—They are circular, 
coin-shaped, homogeneous discs, with saucer-like depressions on both surfaces, 
and with rounded margins; in other words, they are bi-concave, circular non- 
nucleated discs (figs, i, A; 5). 
('b) Size.—The diameter {a, b) is 7.7/a,1 (6.7-9.3/a) the greatest thickness (c, d) 
1.9/a (fig. 1, C), [/. <?., it is 3 0- to °f an inch in diameter, and about one- 
fourth of that in thickness]. 
They are slightly diminished in size by septic fever, inanition, morphia, increased bodily 
temperature, and C02; and increased by O, watery condition of the blood, cold, consumption 
of alcohol, quinine, and hydrocyanic acid. Compare £ 10, 2. 
If the total amount of blood in a man be taken at 4400 cubic centimetres, the corpuscles 
1 The Greek letter /z represents one-thousandth of a millimetre (/z = o.ooi mm.), and is the 
sign of a micro-millimetre, or a micron. 4 
MICROSCOPIC EXAMINATION OF BLOOD. 
[Sec. 2. 
therein contained have a surface of 2816 square metres, which is equal to a square surface with 
a side of 80 paces ; 176 cubic centimetres of blood pass through the lungs in a second, and the 
blood-corpuscles in this amount of blood have a superficies of 81 square metres, equal to a square 
surface with a side of 13 paces (Welcker). 
(e) The Weight of a blood-corpuscle is 0.00008 milligram. 
[(V) Color and Transparency.—Each corpuscle is of a light straw-3'ellow 
color; but when seen e?i masse the corpuscles are red. They are fairly transparent; 
thus the outline of one corpuscle can be distinctly seen through another cor- 
puscle lving above it.] 
(e) The number exceeds 5,000,000 per cubic millimetre in the male, and 
4,500,000 in the female; so that, in 10 lbs. of blood, there are 25 billions of 
corpuscles. The number is in inverse ratio to the amount of plasma; hence, 
the number must vary with the state of contraction of the blood-vessels, the 
pressure, diffusion currents, and other conditions. 
The number of red corpuscles is increased : in venous blood (especially in the small cutaneous 
veins), after the use of solid food, after much sweating, and the excretion of much water by 
the bowel and kidneys; during inanition, because the blood-plasma undergoes decomposition 
sooner than the blood-corpuscles themselves; in the blood of the newly-born child, especially 
Apparatus of Abbe and Zeiss for counting the 
corpuscles. A, in section ; C, surface view 
without cover-glass; B, microscopic appear- 
ance with the blood-corpuscles. 
Fig. 2. 
The MHangeur pipette 
or mixer. 
F>g- 3- 
when the umbilical cord is long in being tied (§ 40), from the 4th day onward the number is 
diminished; in persons of robust constitution, and in those who live in the country. The 
number is diminished, during pregnancy, and after copious draughts of water. In the earlier 
period of foetal life the number is only y^-1 million in x cubic millimetre. (For the pathological 
conditions see § 10.) Sec. 2.J 
NUMBER OF BLOOD-CORPUSCLES. 
5 
Methods of Counting the Blood-Corpuscles.—The pointed end of a glass pipette (fig. 3), 
the mixer, is dipped into the blood, and by sucking the elastic tube f, blood is drawn into the 
tube until it reaches the mark *4, on the stem of the pipette, or until the mark 1 is reached. 
The carefully-cleaned point of the pipette is dipped into the artificial serum, and this is sucked 
into the pipette until it reaches the mark, 101. The artificial serum consists of 1 vol. of solu- 
tion of gum arabic (sp. gr. 1020) and 3 vols. of a solution of equal parts of sodic sulphate and 
sodic chloride (sp. gr. 1020). The process of mixing the two fluids is aided by the presence of a 
little glass ball (a) in the bulb of the pipette. If blood is sucked up to the mark strength 
of the mixture is 1:200; if to the mark 1, it is 1:100; a small drop of the mixture is 
allowed to run into the counting-chamber of Abbe and Zeiss (fig. 2). The first portions are 
not used, in order to obtain a uniform sample from the bulb of the pipette. This chamber con- 
sists of a glass receptacle 0.1 mm. deep, with its base divided into squares, and cemented to a 
glass slide, the whole being covered with a thin covering-glass. The space over each square = 
cubic millimetre. Count, with the aid of a microscope, the number of blood-corpuscles in 
each square, and the number found, multiplied by 4000, will give the number of blood- 
corpuscles in 1 c.mm. This number, again, must be multiplied by 100 or 200, according as 
the blood was diluted 100 or 200 times. To ensure greater accuracy, it is well to count the 
number in several squares, and to take the mean of these. 
[Gowers’ method.—“ The Haemacytometer (fig. 4) consists of—(1) a small pipette, which, 
when filled to the mark on its stem, holds exactly 995 cubic millimetres. It is furnished with 
an india-rubber tube and mouthpiece to facilitate filling and emptying. (2) A capillary tube 
Fig. 4. 
Gowers’ apparatus. A, pipette for measuring the diluted solution; B, capillary tube for 
measuring the blood; C, cell with divisions on the floor, mounted on a slide; D, vessel 
in which the dilution is made; E, glass stirrer; F, guarded spear-pointed needle. 
marked to contain exactly 5 cubic millimetres, with india-rubber tube for filling, etc. (3) A 
small glass jar in which the dilution is made. (4) A glass stirrer for mixing the blood and 
solution in the glass jar. (5) A brass stage plate, carrying a glass slip, on which is a cell, i of 
a millimetre deep. The bottom of this is divided into millimetre squares. Upon the top of 
the cell rests the cover-glass, which is kept in its place by the pressure of two springs proceed- 
ing from the ends of the stage plate.” The diluting solution used is a solution of sodic sulphate 
in distilled water, sp. gr. 1025, or the following: sodic sulphate, 104 grains; acetic acid, x 
drachm; distilled water, 4 oz. 
“995 cubic millimetres of the solution are placed in the mixing jar; 5 cubic millimetres of 
blood are drawn into the capillary tube from the puncture in the finger, and then blown into 
the solution. The two fluids are well mixed by rotating the stirrer between the thumb and 
finger, and a small drop of this dilution is placed in the centre of the cell, the covering-glass 
gently put upon the cell, and secured by the two springs, and the plate placed upon the stage 6 
HISTOLOGY OF BLOOD-CORPUSCLES. 
[Sec. 2. 
of the microscope. The lens is then focussed for the squares. In a few minutes the corpuscles 
have sunk to the bottom of the cell, and are seen at rest on the squares. rl he number in ten 
squares is then counted, and this, multiplied by 10,000, gives the number in a cubic millimetre 
of blood.” 
To estimate the colorless corpuscles only, mix the blood with 10 parts of 0.5 per cent, 
solution of acetic acid, which destroys all the red corpuscles (Tkoma). 
3. HISTOLOGY OF THE HUMAN RED BLOOD-CORPUS- 
CLES AND THE EFFECT OF REAGENTS.—When observed 
- singly, human red blood-corpuscles are 
bi-concave circular discs of a yellow color 
with a slight tinge of green ; they seem to 
be devoid of an envelope, are certainly 
non-nucleated, and appear to be homo- 
geneous throughout (fig. 5). Each cor- 
puscle consists (1) of a framework, an 
exceedingly pale, transparent, soft proto- 
plasm—the stroma ; and (2) of the pig- 
ment or haemoglobin, which impreg- 
nates the stroma, much as fluid passes 
into and is retained in the interstices of a 
bath-sponge. 
(A) Effects of reagents on their 
Vital Phenomena.—The blood-corpus- 
cles present in shed blood—or even in 
defibrinated blood, when it is reintro- 
duced into the circulation—retain their 
vitality and functions undiminished. 
Heat acts powerfully on their vitality, for if blood be heated to 520 C., the 
vitality of the red corpuscles is destroyed. Mammalian blood may be kept for 
four or five days in a vessel under iced water, and still retain its functions; but 
if it be kept longer, and reintroduced into the circulation, the corpuscles 
rapidly break up—a proof that they have lost their vitality. 
The red corpuscles in freshly shed blood sometimes exhibit 
a peculiar mulberry-like appearance (figs. 6, 7, g, h). [This 
is called crenation of the colored corpuscles. It occurs in 
cases of poisoning with Calabar bean ; and also by the addi- 
tion of a 2 per cent, solution of common salt.] The blood 
of many persons crenates spontaneously—a condition as- 
cribed to an active contraction of the stroma, but it is 
doubtful if this is the cause. The red corpuscles of the 
embryo-chick undergo active contraction. 
(B) On their External Characters.—(a) The color is changed by many 
gases. O makes blood scarlet, want of O renders it dark bluish-red, CO makes 
it cherry-red, NO violet-red. There is no difference between the shape of the 
corpuscles in arterial and venous blood. All reagents (e.g., a concentrated 
solution of sodic sulphate), which cause great shrinking of the colored cor- 
puscles, produce a very bright scarlet or brick-red color. The red color so 
produced is quite different from the scarlet-red of arterial blood. Reagents 
which render blood-corpuscles globular darken the blood, e.g., water. 
[The contrast is very striking, if we compare blood to which a 10 per cent, solution of common 
salt has been added with blood to which water has been added. With reflected light the one 
is bright red, and the other a very dark deep crimson, almost black.] 
(fr) Formation of Rouleaux.—A very common phenomenon in shed blood 
is the tendency of the fcorpuscles to run into rouleaux (figs. 1, A3; 5). 
Fig- 5- 
Drop of human blood showing some of the 
red corpuscles in rouleaux. 
Fig. 6. 
Crenation of human 
red blood-corpus- 
cles. X 3°°- Sec. 3.] 
CHANGES IN BI.OOD-CORPUSCLES. 
7 
Conditions that increase the coagulability of the blood favor this phenomenon, which is 
ascribed by Uogiel to the attraction of the discs and the formation of a sticky substance. [The 
cause of the formation of rouleaux is by no means clear. The corpuscles may be detached from 
each other by gently touching the cover-glass, but the rouleaux may re-form. Lister suggested 
that the surfaces of the corpuscles were so altered that they became adhesive. Norris made ex- 
periments with corks weighted with tacks or pins, so as to produce partial submersion of the cork 
discs. These discs rapidly cohere, owing to capillarity, and form rouleaux. If the discs be 
completely submerged they remain apart, as occurs with unaltered blood-corpuscles within the 
blood-vessels. If, however, the corpuscles be dipped in petroleum, and then placed in water, 
rouleaux are formed.] If reagents which cause the corpuscles to swell up be added to the blood, 
the corpuscles become globular and the rouleaux break up. According to E. Weber and Suchard, 
the uniting medium is not fibrin (although it may sometimes assume a fibrous form), but belongs 
to the peripheral layer of the corpuscles. 
(c) Changes of Form.—The discharge of a Leyden jar causes the 
Fig. 7. 
Red blood-corpuscles, a, b, normal human red corpuscles, the central depression more or less 
in focus; c, d, e, mulberry, and g, h, crenated forms; k, pale corpuscles decolorized by 
water; /, stroma: f, frog’s blood-corpuscle acted on by a strong saline solution. 
corpuscles to crenate, so that their surfaces are beset with coarse or fine projec- 
tions (fig. 7, c, d, e, g, h'i); it also causes the corpuscles to assume a spherical 
form (/, z), and they become smaller than normal. 
The corpuscles so altered are sticky, and run to- 
gether like drops of oil, forming larger spheres. 
The prolonged action of the electrical spark 
causes the haemoglobin to separate from the 
stroma (/£), whereby the fluid part of the blood is 
reddened, while the stroma is recognizable only 
as a faint shadow (/). Similar forms are to be 
found in decomposing blood, as well as after the 
action of many other reagents. Heat.—When 
blood is heated, on a warm stage, to 520 C. the 
corpuscles exhibit remarkable changes. Some of 
them become spherical, others biscuit-shaped; 
some are perforated, while in others small por- 
tions become detached and swim about in the 
surrounding fluid, a proof that heat destroys the 
histological individuality of the corpuscles (fig. 8). If the heat be continued, 
the corpuscles are dissolved (§ 10, 3). 
The addition of a concentrated solution of urea to blood acts like heat on the blood cor- 
puscles. If strong pressure be exerted upon a microscopic preparation, the blood-corpuscles 
may break in pieces. The latter process is called haemocytotrypsis, in contradistinction to 
that of solution of the corpuscles or haemocytolysis. 
If a finger moistened with blood be rapidly drawn across a warm slip of glass, so that the 
fluid dries rapidly, the corpuscles exhibit very remarkable shapes, showing their great ductility 
and softness. 
[Water renders the red corpuscles spherical, although some of them do not become quite so, 
Effect of heat on human colored 
blood-corpuscles. {Stirling) 
X 400. 
Fig. 8. 8 
STAINING OF BLOOD-CORPUSCLES. 
[Sec. 4. 
as there remains a slight depression or umbilicus on one side of the corpuscle. Gradually they 
are decolorized, and only the stroma—the outline of which is difficult to see—remains in the 
field of the microscope (fig. 7, k, l). The water passes into the corpuscles by osmosis, and dis- 
solves out the hsemoglobin.] 
Saline solutions in certain concentrations (2-3 per cent.) make them crenated (fig. 6). 
[Acetic acid renders them clear and transparent, and dissolves out the haemoglobin. See 
p. 9, for other acids. Alkalies in very dilute solutions make them spherical, and ultimately 
completely dissolve them.] 
[Hamburger has studied the action of saline solutions of various strengths. The strength of 
a solution in which the corpuscles remain unaltered he calls the isotonic or neutral point 
(0.64 per cent, for NaCl, and 5.59 per cent, of sugar).] 
Cytozoon—Gaule’s Experiment.—A few drops of freshly-shed frog’s blood are mixed with 
5 c. c. of 0.6 per cent, solution of common salt, and the mixture defibrinated by shaking it along 
with a few c. c. of mercury. A drop of the defibrinated blood is examined on a hot stage 
(3°0_32° C.) under a microscope, when a protoplasmic mass, the so-called “ Wurmchen,” 
escapes with a lively movement from many corpuscles, and ultimately dissolves. Similar 
“cytozoa” were discovered by Gaule in the epithelium of the cornea, of the stomach and 
intestine, in connective-tissue, in most of the large glands, and in the retina (frog, triton). In 
mammals also he found similar but smaller structures. Most probably these structures are 
parasitic in their nature, as suggested by Ray Lankester, who called the parasite Drepanidium 
ranarum. 
[Staining Reagents.—Such reagents as magenta, picro-carmine, carmine, 
and many of the aniline dyes, stain the nucleus deeply when such is present, and 
although they must traverse the haemoglobin to reach the nucleus, the haemoglobin 
itself is not stained. When no nucleus is present, therefore, the corpuscles are not 
stained. Magenta causes one or more small spots or maculae to appear on the edge 
of the corpuscles (fig. 9, a). What its significance is is entirely unknown. Normal 
a, b, human red blood-corpuscles; a, acted on by magenta; b, by tannic acid. The others are 
amphibian red blood-corpuscles; c, d, e, effect of tannic acid; f, of dilute acetic acid; g, of 
dilute alcohol; d, of boracic acid [Stirling). 
Fig. 9. 
saline solution (0.6 per cent. NaCl), tinged with methyl violet, is a good staining 
and preservative agent. Red corpuscles become green when they are treated 
with indigo-carmine and borax, and then with oxalic acid. By means of this 
reaction Bayerl discovered the formation of red corpuscles in ossifying cartilage 
(P- T3)- 
[Agitation with Mercury.—If ox blood be shaken up with mercury for 7 or 8 hours, the 
corpuscles completely disappear, no trace of stroma or corpuscles being found in the fluid 
(Meltzer and Welch). The addition of pyrogallic acid (20 per cent.), potassic chlorate (6 per 
cent.), and silver nitrate (3 per cent.), completely prevents dissolution of the corpuscles, even 
though the shaking be kept up for fourteen days.] 
If blood be mixed with concentrated gum solution, and if concentrated salt solution be added to 
it under the microscope, the corpuscles assume elongated forms. Similar forms are obtained by 
mixing blood with an equal volume of gelatine at 36° C., allowing it to cool, and then making 
sections- of the coagulated mass. The corpuscles may be broken up by pressing firmly on the 
cover-glass. In all these experiments no trace of an envelope around the corpuscles is observed. 
4. CONSERVATION OF THE CORPUSCLES.—The blood-corpuscles retain their 
form in the following fluid :— 
Pacini's Fluid:— 
Mercuric chloride, 2 grams. 
Sodic chloride, 4 “ 
Glycerine, 26 c.c. 
Water, 226 “ 
Before using it dilute it with 2 parts water. 
Haye7n's Fluid :— 
Mercuric chloride, 0.5 grams. 
Sodic sulphate, 5 “ 
Sodic chloride, 1 “ 
Water, 200 c.c. Sec. 4.] 
LAKE-COLORED BLOOD. 
9 
1 per cent, osmic acid, 0.6 per cent. NaCl, and other fluids, have also been recommended for 
this purpose. In order to investigate fresh human blood without contact with air, place a drop 
of Hayem’s or Pacini’s fluid on the skin and prick the skin through the drop of fluid. The 
blood runs into and mixes with the fluid without coming into contact with the air. If a drop 
of blood be rapidly dried in a thin layer on a slide, the corpuscles retain their form and color ; 
and if the process be done with sufficient rapidity, even the blood-platelets are retained. 
In investigating blood with the microscope for forensic purposes, it is necessary to have a 
solvent for the blood when it occurs as stains on a garment or instrument. Dried stains are 
dissolved by a concentrated, or a 30 per cent., solution of caustic potash, or with one of the pre- 
serving fluids. If the stain be softened with concentrated tartaric acid, the colorless corpuscles 
are specially distinct (Struve.) Nevertheless, corpuscles are often not found in such stains. If 
the corpuscles have become very pale, their color may be improved by adding a solution of 
iodide of potassium, a saturated solution of picric acid, 20 per cent, pyrogallic acid, or 3 per 
cent, solution of silver nitrate. 
5. STROMA—LAKE-COLORED BLOOD.—Many reagents cause 
the haemoglobin to separate from the stroma. The haemoglobin dissolves in the 
serum ; the blood becomes dark red and transparent, as it contains its color- 
ing matter in solution, and hence it is called “lake-colored” (.Rollett). 
The aggregate condition of the haemoglobin is not altered when the corpuscles 
are dissolved—it only changes its place, leaving the stroma and passing into 
the serum. Hence, the temperature of the blood is not lowered thereby. 
Methods.—To obtain a large quantity of the stroma for chemical purposes add io vols. 
of a solution of common salt (i vol. concentrated solution and 15 to 20 vols. of water) to I vol. 
of defibrinated blood, when the stromata are thrown down as a whitish precipitate. 
For microscopical purposes mix blood with an equal volume of a concentrated solution of 
sodic sulphate, and cautiously add a 1 per cent, solution of tartaric acid. 
The following reagents cause a separation of the stroma from the haemoglobin, and thus make 
blood transparent :— 
(a) Physical Agents.—I. Heating the blood to 6o° C. (Schultze); the temperature, however, 
varies for the blood of different animals. 2. Repeated freezing 
and thawing of the blood (Rollett). 3. Sparks from an electrical 
machine (but not after the addition of salts to the blood) 
(.Rollett) ; the constant and induced currents (Neumann). 
(b) Chemically active Substances produced within the Body. 
—4. Bile (Hilnefeld) or bile salts (Plattner, v. Dusch). 5. 
Serum of other species of animals (Landois); thus dog’s serum 
and frog’s serum dissolve the blood-corpuscles of the rabbit in a 
few minutes. 6. The addition of lake-colored blood of many 
species of animals (Landois). 
(c) Other Chemical Reagents.—7. Water. 8. The vapor of 
chloroform (Bottcher); ether (v. Wittich); amyls, small quanti- 
ties of alcohol (Rollett) ; thymol (Marchand) ; nitrobenzol, 
paraldehyde, ethylic ether, aceton, petroleum ether, etc. 
(Z. Lewin). 9. Antimoniuretted hydrogen, arseniuretted 
hydrogen; carbon bisulphide; boracic acid (2 per cent.), added 
to the amphibian blood, causes the red mass (which also encloses me nucleus wnen sucn is pre- 
sent), the so called zooid, to separate from the cecoid (fig. 9, d). The zooid may shrink from 
the periphery of the corpuscle, or it may pass out of the corpuscle altogether (Briicke); Briicke 
regards the stroma in a certain sense as a house, in which the remainder of the substance of the 
corpuscle, the chief part endowed with vital phenomena, lives. 11. Strong solutions of acids 
dissolve the corpuscles; more dilute solutions cause precipitates in the haemoglobin. This is 
easily seen with carbolic acid (Hills and Stirling and Rannie). 12. Alkalies of 
moderate strength cause sudden solution. A 10 per cent, solution of potash placed at the edge 
of a cover-glass, shows the process of solution going on under the microscope. At first the cor- 
puscles become globular, and so appear smaller, but afterwards they burst like soap-bubbles. 
13. Such salt solutions, which in plants cause a separation of the protoplasm from the cell-mem- 
brane (plasmolysis), make ox-blood lake-colored. [14. NH4C1 injected into the blood causes 
vacuolation of the red corpuscles (Bobrilzky). 15. Sodic salicylate, benzoate, and colchicin 
dissolve the red corpuscles (Ar. Baton).'] 
[Tannic Acid.—A freshly prepared solution of tannic acid has a remarkable effect on the 
colored blood-corpuscles of man and animals—causing a separation of the haemoglobin from 
the stroma ( W. Roberts). The usual effect is to produce one or more granular buds of haemo- 
Red blood-corpuscles of the 
frog acted upon by syrup 
[Stirling). 
Fig. io. FORM AND SIZE OF BLOOD-CORPUSCLES. 
[Sec. 5. 
globin on the side of the corpuscles (fig. 9, b c); more rarely the haemoglobin collects aronnd 
the nucleus, if such be present (fig. 9, d), or is extruded, as shown in fig. 9, e.~\ 
[Ammonium or Potassium Sulphocyanide removes the haemoglobin, and reveals a reticular 
structure—intra-nuclear plexus of fibrils (Stirling and Ronnie).] 
[Syrup causes some of the red corpuscles to become twisted, and to exhibit redder patches in 
them (fig. 10).] 
The Amount of Gases in the blood exercises an important influence on their solubility. The 
corpuscles of venous blood, which contains much CO,2, are more easily dissolved than those of 
arterial blood; while between both stands blood containing CO. When the gases are com- 
pletely removed from the blood, it becomes lake-colored. 
Salts increase the resistance of the corpuscles to physical means of solution, 
while they facilitate the action of chemical solvents. 
If certain salts be added in substance to blood, they make blood lake colored; potassic 
sulphocyanide, sodic chloride, etc. (Kozvalewsky). 
Resistance to Solvents.—The red blood-corpuscles offer a certain degree 
of resistance to the action of solvents. 
Method.—Mix a small drop of blood with an equal volume of a 3 per cent, solution of sodic 
chloride, and then add distilled water until all the colored corpuscles are dissolved. Fill the 
mixer (fig. 3) up to the mark I with blood obtained by pricking the finger, and blow this blood 
into an equal volume of a 3 per cent, solution of NaCl previously placed in a hollow in a glass- 
slide. Mix the fluids, and the corpuscles will remain undissolved. By means of the pipette 
add distilled water, and go on doing so until all the corpuscles are dissolved; which is ascertained 
with the microscope. In normal blood, solution of the corpuscles occurs after 30 volumes of 
distilled water have been added to the blood (Landois). 
There are some individuals whose blood is more soluble than that of others; their corpuscles 
are soft, and readily undergo changes. Many conditions, such as cholsemia, poisoning with 
substances which dissolve the corpuscles, and a markedly venous condition of the blood, affect 
the corpuscles. Interesting observations may be made on the blood in infectious diseases, 
hsemoglobinuria, and in cases of burning. In anaemia and fever, the capacity for resistance 
seems to be diminished. 
6. FORM AND SIZE OF THE BLOOD-CORPUSCLES OF 
ANIMALS.—All mammals (with the excep- 
tion of the camel, llama, alpaca, and their allies), 
and the cyclostomata amongst fishes, e. g., Pet- 
romyzon, possess circular bi-concave non-nuclea- 
ted disc-shaped colored corpuscles. Elliptical 
corpuscles without a nucleus are found in the 
above-named mammals, while all birds, reptiles, 
amphibians (fig. i, B, i, 2), and fishes (except 
cyclostomata) have nucleated elliptical bi-convex 
corpuscles (fig. 11). [The corpuscles have a 
yellow color, and are transparent. The area 
occupied by the nucleus is less colored than 
the homogeneous perinuclear part]. 
Amongst vertebrates amphioxus has colorless blood. 
The large blood-corpuscles of many amphibia, e. g., am- 
phiuma, are visible to the naked eye. The blood-cor- 
puscles of the frog (fig. 11) contain, in addition to a 
nucleus, a nucleolus (Auerbach, Ranvier), [and the same 
is true of the colored corpuscles of the newt (Stirling). 
The nucleolus is revealed by acting on the corpuscles 
with dilute alcohol (1, alcohol; 2, water; Ranvier’s 
<l alcool au tiers'" fig- It is evident that the larger the blood-corpuscles are the smaller 
must be the number and total superficies of the corpuscles in a given volume of blood. In 
birds, however, the number is relatively larger than in other classes of vertebrates, notwith- 
standing the larger size of their corpuscles; this, doubtless, has a relation to the very energetic 
metabolism that takes place in birds (Malassez). Amongst mammals, carnivora have more 
blood-corpuscles than herbivora. Goat’s blood contains 9.720,000 corpuscles per cubic milli- 
Fig. II. 
Blood of frog, a, red-blood corpuscle 
seen on the flat, b in profile, c 
three-quarter face; some of the 
red corpuscles show vacuoles (zi); 
11, colorless corpuscle at rest; 
m, one with amoeboid processes. Sec. 6.J 
ORIGIN OF BLOOD-CORPUSCLES. 
11 
metre; llama’s, 13,000,000; bullfinch’s, 3,600,000; lizard’s, 1,420,000; frog’s, 404,000; and 
that of proteus, 36,000 (Welcker) In hibernating animals the number diminishes from 
7,000,000 to 2,000,000 per cubic millimetre. No relation exists between the size of the animal 
and that of its blood-corpuscles. 
The invertebrata generally have colorless blood, with colorless corpuscles; but the earth- 
worm and the larvae of the large gnats, etc., have red blood whose plasma contains haemoglobin, 
while the blood-corpuscles themselves are colorless. Many invertebrates possess red, violet, 
brown, or green opalescent blood with colorless corpuscles (amoeboid cells). In cephalopods, 
and some crabs the blood is blue, owing to the presence of a coloring matter (haemocyanin), 
which contains copper, and combines with O. 
Size (/u. = 
0.001 Millimetre) 
Of the Disc-sha 
Corpuscles. 
ped 
Of the Elliptical Corpuscles. 
Short Diameter. 
Long Diameter. 
Elephant, . . . 
. 9.4 (i 
Llama, . 
. . . . 4.0^ 
8.0 u 
Man, 
7.7 “ 
Dove, . . 
. . . . 6.5“ 
I4.7 “ 
Dog. 
• 7-3 “ 
Frog, . . 
.... 15.7“ 
22.3 <• 
Rabbit, .... 
. 6.9 •* 
Triton, 
.... 19-5 “ 
29.3 “ 
Cat, 
• 6.5“ 
Proteus, . 
.... 35.0“ 
58.0 “ 
Sheep, 
. 5.0“ 
Goat, 
. 4.1 “ 
The corpuscles of Amphiuma are nearly one-third larger 
Musk-deer, . . . 
• 2.5 “ 
than those of Proteus (Riddel). 
7. ORIGIN OF THE RED BLOOD-CORPUSCLES.—(A) Dur- 
ing Embryonic Life.—Blood-corpuscles are developed in the fowl during 
the first days of embryonic life. [They appear in groups within the large 
branched cells of the mesoblast, in the vascular area of the blastoderm outside 
the developing body of the chick, where they form the “ blood-islands ” of 
Pander. The mother-cells form an irregular network by the union of the pro- 
cesses of adjoining cells, and meantime the central masses split up, and the 
nuclei multiply. The small nucleated masses of protoplasm, which represent 
the blood-corpuscles, acquire a reddish hue, while the surrounding protoplasm, 
and also that of the processes, becomes vacuolated or hollowed out, constituting 
a branching system of canals; the outer part of the cells remaining with their 
nuclei to form the walls of the future blood-vessels. A fluid appears within 
this system of branched canals in which the corpuscles lie, and gradually a 
communication is established with the blood-vessels developed in connection 
with the heart. According to Klein, the nuclei of the protoplasmic wall also 
proliferate, and give rise to new cells, which are washed away to form blood- 
corpuscles.] At first the corpuscles exhibit amoeboid movements, are devoid 
of pigment, nucleated, globular, larger and more irregular than the permanent 
corpuscles. They become colored, retain their nucleus, and are capable of 
undergoing multiplication by division; Remak observed all the stages of the 
process of division, which is best seen from the 3d to the 5th day of incubation. 
Increase by division also takes place in the larvae of the salamander, triton, and 
toad (Flemming) ; and during the intra-uterine life of a mammal, in the spleen, 
bone-marrow, the liver, and the circulating blood (Bizzozero). 
Neumann found in the liver of the embryo protoplasmic cells containing red 
blood-corpuscles. Cells, some with, others without, haemoglobin, but with large 
nuclei, have been found. These cells increase by division, their nucleus shrivels, 
and they ultimately form blood-corpuscles (Lowit). The spleen is also regarded 
as a centre of their formation, but this seems to be the case only during embry- 
onic life (Neumann). Here the red corpuscles are said to arise from yellow, 
round, nucleated cells, which represent transition forms. Foa and Salvioli 12 
ORIGIN OF BLOOD-CORPUSCLES. 
[Sec. 7. 
found red corpuscles forming endogenously within large protoplasmic cells in 
lymphatic glands. In the later period of embryonic life the characteristic 
non-nucleated corpuscles seem to be developed from the nucleated corpuscles. 
The nucleus becomes smaller and smaller, breaks up, and gradually disappears. 
In the human embryo at the fourth week only nucleated corpuscles are found ; 
at the third month their number is still of the total corpuscles, while at 
the end of foetal life nucleated blood-corpuscles are very rarely found. Of 
course, in animals with nucleated blood-corpuscles the nucleus of the embryonic 
blood-corpuscles remains. 
(B) During Post-Embryonic Life.—Kolliker assumed that in the tail of 
the tadpole capillaries are formed by the anastomoses of the processes of 
branched and radiating connective-tissue corpuscles. These corpuscles lose 
their nuclei and protoplasm, become hollowed out, join with neighboring capil- 
laries, and thus form new blood-channels. J. Arnold and Golubew oppose this 
view, asserting that the blood-capillaries in the taii of the tadpole give off solid 
buds at different places, which grow more and more into the surrounding tissues, 
and anastomose with each other ; after their protoplasm and contents disappear, 
they become hollow, and a branched system of capillaries is formed in the 
tissues. Ranvier noticed the same mode of growth in the omentum of newly- 
born kittens. 
Young rabbits, a week old, have in their omentum small white or milk spots 
(.Ranvier), in which lie “ vaso-formative cells,” i. e., highly refractive cells 
of variable shape, with long cylindrical protoplasmic processes (fig. 12). In its 
refractive power the protoplasm 
of these cells resemble that of 
lymph-corpuscles. Long rod- 
like nuclei lie within these cells 
(K, K), and also red blood- 
corpuscles (r, r), and both are 
surrounded with protoplasm. 
These vaso-formative cells give 
off protoplasmic processes (a, a), 
some of which end free, while 
others form a net work. Here 
and there elongated connective- 
tissue corpuscles lie on the 
branches, and ultimately form 
the adventitia of the blood- 
vessel. The vaso-formative cells 
have many forms : they may be 
elongated cylinders ending in 
points, or more round and oval, 
resembling lymph cells, or modified connective-tissue corpuscles. These cells 
are always the seat of origin of non-nucleated red blood-corpuscles, which arise 
in the protoplasm of vaso-formative cells, as chlorophyll grains or starch gran- 
ules arise within the cells of plants. The corpuscles escape and are washed 
into the circulation, when the cells, by means of their processes, form connec- 
tions with the circulatory system. Probably the vessels so formed in the omen- 
tum are only temporary. May it not be that there are many other situations 
in the body where blood is regenerated ? 
[The observations of Schafer also prove the intra-cellular origin of red 
blood-corpuscles, and although this mode usually ceases before birth, still it is 
found in the rat at birth. The protoplasm of the subcutaneous connective- 
tissue corpuscles, which are derived from the mesoblast, has in it small col- 
ored globules about the size of a colored corpuscle. The mother-cells elongate, 
Fig. 12. 
Formation of red blood-corpuscles within “ vaso-forma- 
tive cells,” from the omentum of a rabbit seven days 
old. r, r, the formed corpuscles; K, K, nuclei of the 
vaso-formative cell; a, a, processes which ultimately 
unite to form capillaries. Sec. 7.] 
ORIGIN OF BLOOD-CORPUSCLES. 
13 
become pointed at their ends, and unite with processes from adjoining cells. 
The cells become vacuolated ; fluid or plasma, in which the liberated corpuscles 
float, appears in their interior, and ultimately a communication is established 
with the general circulation.] 
Neumann observed similar formations in the embryonic liver; Wissotzky in the rabbit’s 
amnion; Klein in the embryo chick; and Bayerl in ossifying cartilage (p. 8). All these obser- 
vations go to show that at a certain early period of development blood-corpuscles are formed 
within other large cells of the mesoblast, and that part of the protoplasm of these blood-forming 
cells remains to form the wall of the future blood-vessel. 
(C) Later Formation.—Most observers agree that the red blood-corpuscles 
are formed from special nucleated cells, which gradually assume the form and 
color of the perfect red corpuscle. According to Neumann, however, these cor- 
puscles are pigmented from the first. In the tailed amphibians and fishes, the 
spleen, in all other vertebrates the red marrow of bone, are the seats of 
formation of these corpuscles, which subsequently increase by division (Neu- 
mann,, Rindfleisch, Bizzozero). In the red marrow of bone we can study all the 
stages of the transformation ; especially pale contractile cells similar to colorless 
corpuscles, and also red nucleated corpuscles, which are similar to the nucleated 
corpuscles of the embryo, and the progenitors of the red corpuscles. These 
transition cells are said by Erb to be more numerous after severe hemorrhage, 
the number of them occurring in the blood corresponding with the energy of 
the formative process. After copious hemorrhage these transition forms appear 
in numbers in the blood-stream. The small veins, and perhaps the capillaries 
of the red marrow of bone and the spleen have no proper walls, so that the red 
corpuscles when formed can pass into the circulation. 
Red or blood-forming marrow occurs in tbe bones of the skull, and in most of the bones of 
the trunk, while the bones of the extremities either contain yellow marrow (which is essentially 
fatty in its nature), or, at most, it is only the heads of the long bones that contain red marrow. 
Where the blood-regeneration process is very active, however, the yellow marrow may be 
changed into red, even throughout all the bones of the extremities (Neumann). 
[The most recent observers (Low it, Bizzozero, and Denys), regard the red and 
white blood-corpuscles as being developed independently of each other. Lowit 
calls the early stages of the former erythroblasts and of the latter leucoblasts. 
In the red marrow of the bones of birds, the red corpuscles are developed within 
the blood-vessels of the marrow, and the colorless ones in the tissue which lies in 
the v-ascular meshes. The erythroblasts are originally colorless, and between 
them and the complete red corpuscle there is a complete series of gradations. The 
erythroblasts have a large, spherical, central nucleus with a pronounced nuclein 
network and homogeneous or slightly granular protoplasm. The leucoblasts, on 
the contrary, contain a small nucleus of variable form, with numerous nucleoli, and 
often placed peripherally. The protoplasm contains many eosinophile granules. 
Both exhibit amoeboid movement, but this is more active in the leucoblasts. Both 
divide by mitosis. Some of the erythroblasts pass out directly in the blood-stream, 
while the leucocytes in virtue of their amoeboid movements pass by diapedesis 
into the vessels. Repeated hemorrhages lead to rapid mitotic division of both 
forms.] 
[In extra-uterine life, in mammals, the red marrow of bone is undoubt- 
edly the chief seat of the formation of red blood-corpuscles. In it are to be 
found a large number of nucleated red blood-corpuscles, i. <?., embryonic forms, 
which ultimately lose their nuclei, pass into the circulation as perfect red 
corpuscles. After copious hemorrhage, when the animal forms a larger number 
of corpuscles than usual, as if it were striving to make up the deficiency, the 
number of nucleated red corpuscles in the red blood-forming marrow is greatly 
increased, and even parts of what was previously yellow marrow appear somewhat DECAY OF BLOOD-CORPUSCLES. 
[Sec. 7. 
reddish. The blood-forming function of the red marrow is greatly increased 
after hemorrhage (.Neumann and Bizzozero). Often, however, there is an 
additional factor, as shown by Bizzozero and Salvioli in the case of guinea-pigs 
and dogs. In these animals after severe anaemia, due to repeated hemorrhages, 
the spleen also participates in the formation of red corpuscles, for in it are found 
nucleated red corpuscles similar to those of the red marrow.] 
[In birds also red blood-corpuscles are formed in the red marrow, but so far 
as the spleen has been investigated, Bizzozero has not found any reason to be- 
lieve that this organ is concerned in the formation of red blood-corpuscles in 
these animals.] 
[According to Bizzozero, there is no evidence to show that the white corpus- 
cles are precursors of the red ; the red corpuscles are derived from special 
corpuscles (erythroblasts), and so are the white (leucoblasts). The red ones seem 
to be formed within the blood-vessels 
of the red marrow, and the colorless 
ones in the extra-vascular parts of the 
marrow. The red corpuscles are formed 
by the mitotic division of pre-existing 
cells, which are quite different from 
the colorless corpuscles; their proto- 
plasm is never granular, but almost al- 
ways homogeneous, never colorless, 
but slightly tinged by haemoglobin ; 
they never exhibit the lively amoeboid 
movements of the white corpuscles. If 
the red marrow of any of the classes 
of the vertebrata be examined, especially after repeated hemorrhages—there will 
always be found numerous erythroblasts undergoing mitosis (fig. 13).] 
[In all classes of the Vertebrata, then, the red marrow is the great seat of the 
formation of red corpuscles during adult life. But how is it during the develop- 
ment of the young animals ? It is not necessary to assume that the red are derived 
from the colorless corpuscles. If we study the fate of the red corpuscles we find 
that their presence is not due absolutely to any one organ. In the first phases of 
embryonic life, the red corpuscles develop and divide within the whole vascular 
system. At a later period this ceases and they are developed in the liver and 
spleen; at a later period still—in extra-uterine life—and when the bone marrow 
is greatly developed, the blood-forming activity of the liver and spleen is gradually 
diminished and ceases. But the loss is not absolute in the case of the last organ,, 
as it can again be caused to produce red corpuscles after copious hemorrhage. 
The blood-plates are in no way concerned in the formation of red corpuscles, 
they have to do with the coagulation and other vital phenomena of the blood.] 
[The balance of evidence points to the formation of red blood-corpuscles in 
extra-uterine life—both in animals with nucleated and in those with non- 
nucleated corpuscles—by the same process as in embryonic life (i. e., by indi- 
rect division or mitosis of a typical cellular element, which during extra- 
uterine life is chiefly found in the marrow of bone (Bizzozero).] 
8. DECAY OF THE RED BLOOD-CORPUSCLES.—The blood- 
corpuscles undergo decay within a limited time, and the liver is regarded as 
one of the chief organs in which their disintegration occurs, because bile-pig- 
ments are formed from haemoglobin, and the blood of the hepatic vein con- 
tains fewer red corpuscles than the portal vein. 
The splenic pulp contains cells which indicate that colored corpuscles are 
broken up within it. These are the so-called “blood-corpuscle containing cells ” 
(§ 103). Quincke’s observations go to show that the red corpuscles—which 
Fig. 13. 
A, Red blood-corpuscle of a chick undergoing 
mitotic division at 5th-6th day of incubation. 
B, red blood-corpuscle of frog dividing ; Y 
shows a thin colorless thread of protoplasm 
still connecting the two daughter corpuscles. Sec. 8.] 
COLORLESS BLOOD-CORPUSCLES. 
15 
may live from three to four weeks—when about to disintegrate, are taken up by 
the white blood-corpuscles in the hepatic capillaries, by the cells of the spleen 
and the bone-marrow, and are stored up chiefly in the capillaries of the liver, 
in the spleen, and in the marrow of bone. They are transformed partly 
into colored, and partly into colorless proteids which contain iron, and are 
either deposited in a granular form, or are dissolved. Part of the products of 
decomposition is used for the formation of new blood-corpuscles in the marrow 
and in the spleen, and also perhaps in the liver, while a portion of the iron is 
excreted by the liver in the bile. 
That the normal red blood-corpuscles and other particles suspended in the blood-stream are 
not taken up in this way, may be due to their being smooth and polished. As the corpuscles 
grow older and become more rigid, they, as it were, are caught by the amoeboid cells. As cells 
containing blood-corpuscles are very rarely found in the general circulation, one may assume 
that the occurrence of these cells within the spleen, liver and marrow of bone is favored by the 
slowness of the circulation in these organs ( Quincke). 
Pathological.—In certain pathological conditions, ferruginous substances derived from the 
red blood-corpuscles are found in masses in the spleen, the marrow of bone, and the capillaries 
of the liver: (i) When the disintegration of blood-corpuscles is increased, as in anaemia 
(Stahel). (2) When the formation of red blood-corpuscles from the old material is diminished. 
If the excretion from the liver cells be prevented, iron accumulates within them ; it is also more 
abundant in the blood-serum, and it may even accumulate in the secretory cells of the cortex 
of the kidney and pancreas, in gland cells, and in the tissue elements of other organs. When 
the amount of blood in dogs is greatly increased, after four weeks an enormous number of 
granules containing iron occur in the leucocytes of the liver capillaries, the cells of the spleen, 
bone-marrow, lymph-glands, liver cells, and the epithelium of the cortex of the kidney. The 
iron reaction in the last two situations occurs after the introduction of hsemoglobin, or of salts 
of iron into the v. Stark). In thrombi and in extravasations of blood into the 
neighborhood of living tissues, there is formed besides hsematoidin, the body haematosiderin. 
When we reflect how rapidly 
large quantities of blood are re- 
placed after hemorrhage and after 
menstruation, it is evident that 
there must be a brisk manufactory 
somewhere. As to the number of 
corpuscles which daily decay, we 
have in some measure an index in 
the amount of bile-pigment and 
urine-pigment resulting from the 
transformation of the liberated 
hsemoglobin (§ 20). 
9. II. COLORLESS COR 
PUSCLES, BLOOD 
PLATES, AND GRAN- 
ULES.—White Blood-Cor- 
puscles. — Blood, like many 
other tissues, contains a number 
of cells or corpuscles which reach 
it from without; the corpuscles 
vary somewhat in form, and are 
called colorless or white 
blood-corpuscles or “leu- 
cocytes” (Hewson, 1770). 
Similar corpuscles are found in 
lymph, adenoid tissue, marrow 
of bone, and as wandering cells 
or leucocytes in connective-tissue, and also between glandular and epithelial 
A, human white blood-corpuscles, without any reagent; 
B, after the action of water; C, after acetic acid; 
D, frog’s corpuscles, changes of shape due to amoe- 
boid movement; E, fibrils of fibrin from coagulated 
blood; F, elementary granules. 
Fig. 14. [Sec. 9. 
COLORLESS BLOOD-CORPUSCLES. 
cells [so that their ubiquity is a marked feature, thus differing from the colored 
corpuscles which normally remain within the blood-vessels]. So that these 
corpuscles are by no means peculiar to blood alone. They all consist of more or 
less spherical masses of protoplasm, which is sticky, highly refractile, soft, 
capable of movement, and devoid of an envelope (fig. 14). When they are 
quite fresh (A) it is difficult to detect the nucleus, but after they have been 
shed for some time, or after the addition of water (B) or acetic acid, the nu- 
cleus (which is usually a compound one) appears; acetic acid clears up the 
perinuclear protoplasm, and reveals the presence of the nuclei, of which the 
number varies from one to four, although generally three are found. The sub- 
sequent addition of magenta solution causes the nuclei to stain deeply. Water 
makes the contents more turbid, and causes the corpuscles to swell up. One or 
more nucleoli may be present in the nucleus. The size of the corpuscles varies 
from 4-13,a, and as a rule they are about -g-girir of an inch in diameter ; in the 
smallest forms the layer of the protoplasm is extremely thin. They all exhibit 
amoeboid movements, which are very apparent in the larger corpuscles, and 
were discovered by Wharton Jones in the skate (1846), and by Davine in the 
corpuscles of man (1850). Max Schultze describes three different forms in 
human blood:— 
(1) The smallest, spherical forms, less than the red corpuscles, with one or 
two nuclei, and a very small amount of protoplasm. 
(2) Spherical forms, the same size as the colored blood-corpuscles. 
(3) The large amoeboid corpuscles, with much protoplasm and distinctly 
evident movements. 
[On examining human blood microscopically, more especially after the colored blood-cor- 
puscles have run into rouleaux, the colorless corpuscles may readily be detected, there being 
usually three or four of them visible in the field at once (fig. 5). They adhere to the glass slide, 
for if the cover-glass be moved, the colored corpuscles readily glide over each other, while the 
colorless can be seen still adhering to the slide.] 
[White Corpuscles of Newt’s Blood.—The characters of the colorless corpuscles are best 
studied in a drop of newt’s blood, which contains the following varieties :— 
(1) The large finely granular corpuscle, which is about of an inch in diameter, 
irregular in outline, with fine processes or pseudopodia projecting from its surface. It rapidly 
changes its shape at the ordinary temperature, and in its interior a bi- or tri-partite nucleus may be 
seen, surrounded with fine granular protoplasm, whose outline is continually changing. Some- 
times vacuoles are seen in the protoplasm. 
(2) The coarsely granular variety is less common than the first-mentioned, but when de- 
tected its characters are distinct. The protoplasm contains, besides a nucleus, a large number 
of highly refractive granules, and the corpuscle usually exhibits active amoeboid movements ; 
suddenly the granules may be seen to rush from one side of the corpuscle to the other. The 
processes are usually more blunt than those emitted by (1). The relation between these two 
kinds of corpuscles has not been ascertained. 
(3) The small colorless corpuscles are more like the ordinary human colorless corpuscle, 
and they too exhibit amoeboid movements.] 
Two kinds of colorless corpuscles like (1) and (2) exist in frog’s blood. In the coarsely- 
granular corpuscles the glancing granules may be of a fatty nature, since they dissolve in 
alcohol and ether, but other granules exist which are insoluble in these fluids. The nature of 
the latter is unknown. Very large colorless corpuscles exist in the axolotl’s blood. 
[In the blood of birds there are four varieties of colorless corpuscles:— 
(1) Leucocytes of 7-8 // in diameter, very numerous, which exhibit lively movements, and 
send out processes; the protoplasm is tolerably dark, but this is not due to granules as in the 
case of the leucocytes of mammals, but to the presence of glancing crystals, which are usually 
pointed at their ends, and arranged radially from the centre to the periphery of the corpuscles. 
They are not fatty in their nature. 
(2) Leucocytes about the size of (1), but with spherical fine granules. They are nucleated, 
contractile, but the latter to a less degree than (1). 
(3) Small (5-6 /jl in diameter) finally granular leucocytes, which are contractile, but do not 
send out processes. 
(4) Colorless cells, having an oval nucleolated refractive nucleus, and the protoplasm of the 
cell vacuolated. They do not exhibit contractile movements. The last variety was regarded by Sec. 9.] 
COLORLESS BLOOD-CORPUSCLES, 
17 
Hayem as corpuscles that developed into red corpuscles, but there is no evidence confirmatory of 
this view] (Bizzozero). 
[Action of Reagents on the Colorless Corpuscles.—(a) Water, when 
added slowly, causes the colorless corpuscles to become globular, and the gran- 
ules within them to exhibit Brownian movements (fig. 14B). (b) Pigments, 
such as magenta or carmine, stain the nuclei very deeply, and the protoplasm 
to a less extent, (e) Dilute Acetic Acid clears up the surrounding proto- 
plasm and brings clearly into view the composite nucleus, which may be stained 
thereafter with magenta, (d) Iodine gives a faint port-wine color, especially 
in horse’s blood, indicating the presence of glycogen. (<?) Dilute Alcohol 
causes the formation of clear blebs on the surface of the corpuscles, and brings 
the nuclei into view (.Ranvier, Stirling).] 
[A delicate plexus of fibrils—intra-nuclear plexus—exists within the nucleus 
just as in other cells. It is very probable that the pro- 
toplasm itself is pervaded by a similar plexus of fibrils, and 
that it is continuous with the intra-nuclear plexus (fig. 
15).] The colorless corpuscles divide by mitosis, and in 
this way reproduce themselves. 
The Number of Colorless Corpuscles is very 
much less than that of the red corpuscles, and is subject 
to considerable variations. It is certain that the color- 
less corpuscles are very much fewer in shed blood than 
in blood still within the blood-vessels. Immediately after 
blood is shed an enormous number of white corpuscles 
disappear (§ 30). 
Al. Schmidt estimates the number that remain at of the whole 
originally present in the circulating blood. The proportion is greater 
in children than in adults. The following table gives the number in shed blood : — 
Fig- 15- 
Plexus of fibrils in a color- 
less blood-corpuscle. 
Number of White in Proportion 
to Red Blood-Corpuscles. 
In Normal Condition. 
In Different Places. 
In Different Conditions. 
I : 335 ( Welcker). 
i : 357 (Moleschott). 
Splenic Vein, I : 60 
Splenic Artery, i : 2,260 
Hepatic Vein, 1 : 170 
Portal Vein, 1 : 740 
Generally more numerous 
in Veins than Arteries. 
Increased by Digestion, Loss 
of Blood, Prolonged Sup- 
puration, Parturition, Leu- 
kaemia, Quinine, Bitters. 
Diminished by Hunger, Bad 
Nourishment. 
[The number also varies with the Age and Sex :— 
Age. Sex. 
White. Red. 
General Conditions. 
White. Red. 
Girls, 
I : 405 
While fasting, 
I : 716 
Boys 
1 : 226 
After a meal, 
I : 347 
Adults, . . 
1 •• 334 
During pregnancy, . . . 
1 : 281] 
Old Age, 
1 : 381 
The amoeboid movements of the white corpuscles (so called because they 
resemble the movements of amoeba) consist in an alternate contraction and 
relaxation of the protoplasm surrounding the nucleus. Processes are pushed 
out from the surface, and are retracted again (fig. 16). There is an internal 
current in the protoplasm, and the nucleus has also been observed to change 
its form [and exhibit contractions without the corpuscle dividing. The 18 
COLORLESS BLOOD-CORPUSCLES. 
[Sec. 9. 
mitotic aster, and convolution of the intra-nuclear plexus have been seen]. Two 
series of phenomena result from these movements:—(x) The “ wandering ,r 
or locomotion of the corpuscles due to 
the extension and retraction of their 
processes; (2) the absorption of small 
particles into their interior (fat, pig- 
ment, foreign bodies). The particles 
adhere to the sticky external surface, are 
carried into the interior by the internal 
currents, and may eventually be excreted, 
just as particles are taken up by amoeba 
and the effete particles excreted. [Max 
Schultze observed that colored particles 
were readily taken up by these corpuscles. 
Conditions for movement.—In order 
that the amoeboid movements of the 
leucocytes may take place, it is necessary 
that there be—(1) a certain temperature 
and normal atmospheric pressure; (2) the 
surrounding medium, within certain 
limits, must be t: indifferent,” and contain a sufficient amount of water and 
oxygen; (3) there must be a basis or support to move on.] 
Effect of Reagents.—On a hot stage (35°-4o° C.)the colorless corpuscles of 
warm-blooded animals retain their power of moving for a long time; at 40° C. 
for two to three hours ; at 50° C. the proteids are coagulated and cause “ heat 
rigor” and death [when their movements no longer recur on lowering the 
temperature]. In cold-blooded animals (frogs), colorless corpuscles maybe 
seen to crawl out of small coagula, in a moist chamber, and move about in the 
serum. [Draw- a drop of newt’s blood into a capillary tube, seal up the ends of the 
latter and allow the blood to coagulate. After a time, examine the tube in clove 
oil, when some of the colorless corpuscles will be found to have made their way 
out of the clot.] Induction shocks cause them to withdraw their processes 
and become spherical, and, if the shocks be not too strong, their movements 
recommence. Strong and continued shocks kill them, causing them to swell 
up, and completely disintegrating them. 
Diapedesis.—These amoeboid movements are of special interest on account 
of the “ wandering out ” (diapedesis) of colorless blood-corpuscles through the 
walls of the blood-vessels (§ 95). 
[Effect of Drugs.—Acids and alkalies, if very dilute, at first increase, but afterwards arrest 
their movements. Sodic chloride in a 1 per cent, solution at first accelerates their movements, 
but afterwards produces a tetanic contraction, and, it may be, expulsion of any food particles 
they contain. The Cinchona alkaloids—quinine, quinidine, cinchonidine (1 : 1500)—quickly 
arrest the locomotive movements, as well as the protrusion of pseudopodia, although the leucocytes 
of different animals vary somewhat in their resistance to the action of drugs. Quinine not only 
arrests the movements of the leucocytes when applied to them directly, but when injected into 
the circulation of a frog the leucocytes no longer pass through the walls of the capillaries 
The chyle contains leucocytes, which are more resistant than those of the blood, but less so 
than those of the coagulable transudations. The leucocytes of the lymphatic glands may also 
be dissolved (Rnuschenbach). 
Relation to Aniline Pigments.—Ehrlich has observed a remarkable relation of the white 
corpuscles to acid (eosin, picric acid, aurantia), basic (dahlia, acetate of rosanilin), or neutral 
(picrate of rosanilin) reactions. The smallest protoplasmic granules of the cells have different 
chemical affinities for these pigments. Thus Ehrlich distinguishes “ eosinophile,” “ baso- 
phile,” and “ neutrophile,” granules within the cells. Eosinophile granules occur in the 
leucocytes which come from bone-marrow, the myelogenic leucocytes. The small leucocytes, i. e., 
those about the size of a colored blood-corpuscle or slightly larger, are formed in the lymphatic 
Human leucocytes showing amoeboid 
movements. 
Fig. 16. Sec. 9.] 
BLOOD-PLATES. 
19 
glands, the lymphogenic. The large amoeboid multi-nucleated cells, which are found outside 
the vessels in inflammations, exhibit a neutrophile reaction. Their origin is unknown, and so is 
that of the large uni-nucleated cells, and the large cells with constricted nuclei. The eosinophile 
corpuscles are considerably increased in leukaemia. The basophile granules occur also in con- 
nective-tissue corpuscles, especially in the neighborhood of epithelium; they are always greatly 
increased where chronic inflammation occurs. 
Struggle between Microbes and the Organism.—Metschnikoff emphasizes the activity of 
the leucocytes in retrogressive processes, whereby the parts to be removed are taken up by them 
in fine granules, and, as it were, are “ eaten'' Hence, he calls such cells “ phagocytes.” They 
may be found in the atrophied tails of batrachians, the cells containing in their interior whole 
pieces of nerve-fibre and primitive muscular bundles. Schizomycetes, which have found their 
way into the blood ($ 184), have been found to be partly taken up by the colorless corpuscles. 
[The spores of a kind of yeast are similarly attacked in the transparent tissues of the water flea 
by the leucocytes, and the connective-tissue cells also destroy microbes.] 
[It must not be forgotten in this connection that albumoses are produced by various microbes, 
and that these soluble products are capable when injected into an animal of producing immunity 
against the attack of certain microbes, i.e., a chemical as distinguished from a vaccinal immunity 
(8 166).] 
III. Blood-Plates.—Special attention has recently been directed to a third 
element of the blood, the “blood-plates,” “blood-platelets,” or “blood- 
tablets ” of Bizzozero (figs. 17 and 18); pale, colorless, oval, round, or len- 
ticular discs of variable size (mean 3 d). In a healthy man Fusari found 18,000 
to 250,000 in 1 cubic millimetre of blood. These blood-plates may be recognized 
in the circulating blood of the mesentery of a chloralized guinea-pig and the 
“Blood-plates” and their derivatives. 1, a red blood-corpuscle on the flat; 2, on the side; 3, 
unchanged blood-plates; 4, lymph-corpuscle, surrounded by blood-plates; 5, altered blood- 
plates ; 6, lymph-corpuscle with two heaps of fused blood-plates and threads of fibrin; 7, group 
of fused blood-plates; 8, small group of partially dissolved blood-plates with fibrils of fibrin. 
Fig. 17. 
wing of the bat. They are precipitated in enormous numbers upon threads 
suspended in fresh shed blood [or if blood be beaten with a linen thread]. They 
may be obtained from blood flowing directly from a blood-vessel, on mixing it 
with one per cent, solution of osmic acid. They rapidly change in shed blood 
(fig. 17, 5), disintegrating, forming small particles, and ultimately dissolving. 
When several occur together they rapidly unite, form small groups (7), and 
collect into finely granular masses. These masses may be associated in coagu- 
lated blood with fibrils of fibrin (fig. 17). 
[These blood-plates are best seen in the shed blood of the guinea-pig, especially if it be mixed 
with a solution of sodic sulphate (sp. gr. 1022) or per cent. NaCl tinged with methyl-violet. 
Bizzozero regards them as the agents which immediately induce coagulation and take part in 
the formation of fibrin during coagulation of the blood; Eberth and Schimmelbusch ascribe 20 
CHANGES IN BLOOD-CORPUSCLES. 
[Sec. g. 
the initial formation of white thrombi to them. According to Lowit they are formed from 
partially disintegrated leucocytes, as a consequence of alteration of the blood. Along with the 
leucocytes they are concerned in the formation of fibrin (Hlava). These structures were known 
to earlier observers; but their significance has been variously interpreted. Hayem called them 
hsematoblasts. Halla found that they increased in pregnancy, Afanassiew in conditions of 
regeneration of the blood, and Fusari in febrile anaemia; they are diminished in fever. 
[As to the haematoblasts, or, as they have also been called, the “globules of Donne ” by 
Pouchet, there seems to be some confusion, for both colored and colorless granules are de- 
scribed under these names. As Gibson suggests, the former are, perhaps, parts of disintegrated 
colored corpuscles, whilst the latter are the blood-plates. The “ invisible blood-corpuscles ” 
described by Norris seem to be simply decolorized red corpuscles (Hart, Gibson). 
[If frogs be bled repeatedly, thus leading to active blood-formation, it is stated that on the 
third to the sixth day all stages of mitotic division of the blood-platelets are to be seen (Mondino). 
The same observer has described mitosis of mammalian blood-platelets. These observations, 
however, have still to be confirmed. 
IV. Elementary Granules.—Blood contains elementary granules (fig. 
14, F), [i.e., the elementary particles of 
Zimmermann and Beale. They are ir- 
regular bodies, much smaller than the 
ordinary corpuscles, and appear to con- 
sist of masses of protoplasm detached 
from the surface of leucocytes, or derived 
from the disintegration of these cor- 
puscles or of the blood-plates. Others, 
again, are completely spherical granules, 
either consisting of some proteid sub- 
stance or fatty in their nature. The pro- 
toplasmic and the proteid granules dis- 
appear on the addition of acetic acid, 
while the fatty granules (which are most 
numerous after a diet rich in fats) dis- 
solve in ether.] 
V. In coagulated blood, delicate 
threads of fibrin (figs. 14, E, and 17, 6, 
7, 8) are seen, more especially after the 
corpuscles have run into rouleaux. At 
the nodes of these fibres are found 
granules which closely resemble those described under III. 
[When the blood-forming process is particularly active, as after repeated hemorrhages, 
“nucleated colored corpuscles” or the “corpuscles of Neumann” are sometimes found 
in the blood. They are identical with the nucleated colored blood corpuscles of the foetus, 
being somewhat larger than the non-nucleated colored corpuscle (f 7).] 
xo. ABNORMAL CHANGES OF THE BLOOD-CORPUSCLES.—(1) Hemor- 
rhages diminish the number of red corpuscles (at most one-half), and so does menstruation. 
The loss is partly covered by the absorption of fluid from the tissues. Menstruation shows us 
that a moderate loss of red corpuscles is replaced within twenty-eight days. When a large 
amount of blood is lost, so that all the vital processes are lowered, the time may be extended to 
five weeks. In acute fevers, as the temperature increases, the number of red corpuscles 
diminishes, while the white corpuscles increase in number. By greatly cooling peripheral parts 
of the body as by keeping the hands in iced water, in some individuals possessing red blood- 
corpuscles of low resisting power, these corpuscles are dissolved, the blood-plasma is reddened, 
and even hsemoglobinuria may occur ($ 265). 
Diminished production of new red corpuscles causes a decrease, since blood-corpuscles are 
continually being used up. In chlorotic females there seems to be a congenital weakness in 
the blood-forming and blood-propelling apparatus, the cause of which is to be sought for in some 
faulty condition of the mesoblast. In them the heart and the blood-vessels are small, and the 
absolute number of corpuscles may be diminished one-half, although the relative number may be 
retained, while in the corpuscles themselves the haemoglobin is diminished almost one-third; but 
it rises again after the administration of iron (Hayem). The administration of iron increases 
Fig. 18. 
Blood-corpuscles and blood-plates from normal 
human blood, (a) Red blood-corpuscles; 
(£) colorless corpuscles; (c) blood-plates. Sec. 10.] 
HAEMOGLOBIN. 
21 
the amount of hemoglobin in the blood. [The action of iron in anemic persons has been 
known since the time of Sydenham. Hayem also finds in certain forms of anemia that there is 
considerable variation in the size of the red corpuscles, and that in chronic anemia the mean 
diameter of the corpuscles is always less than normal (y p to 6p). There is, moreover, a persistent 
alteration in the volume, coloring power, and consistence of the corpuscles, consequently a want 
of accord between the number of the corpuscles and their coloring power, i. e., the amount of 
haemoglobin which they contain. In pernicious anaemia, in which the continued decrease in 
the red corpuscles may ultimately produce death, there is undoubtedly a severe affection of the 
blood-forming apparatus. The corpuscles assume many abnormal and bizarre forms, often being 
oval or tailed, irregularly shaped, and sometimes very pale; while numerous cells containing 
blood-corpuscles are found in the marrow of bone. In this disease, although the red blood- 
corpuscles are diminished in number, some may be larger and contain more hsemoglobin than 
normal corpuscles. The number of colored corpuscles is also diminished in chronic poisoning 
by lead or miasmata, and also by the poison of syphilis.] 
(2) The size of the corpuscles varies in disease from 2.9-12.9 p (mean 6-8 p); “ dwarf cor- 
puscles” or microcytes (6 p and less) are regarded as young forms, and occur plentifully in 
nearly all cases of anaemia. “ Giant blood-corpuscles ” or macrocytes (10 p and more) are con- 
stant in pernicious anaemia, and sometimes in leukaemia, chlorosis, and liver cirrhosis (Gram). 
(3) Abnormal forms of the red corpuscles have been observed after severe burns (Lesser); 
the corpuscles are much smaller, and under the influence of the heat particles seem to be detached 
from them, just as can be seen happening under the microscope as the effect of heat (p. 7). Dis- 
integration of the corpuscles into fine droplets has been observed in various diseases, as in severe 
malarial fevers. The dark granules of a pigment closely related to haematin are derived from the 
granules arising from the disintegration of the blood-corpuscles, and these particles float in the 
blood (melanaemia). This condition can be produced artificially by injecting bisulphide of 
carbon (7 to 10 of oil) subcutaneously into rabbits (Schwalbe). They are partly absorbed by the 
colorless corpuscles, but they are also deposited in the spleen, liver, brain, and bone-marrow. 
(4) Sometimes the red corpuscles are abnormally soft, and readily yield to pressure. 
Parasites of blood-corpuscles.—Within the red blood-corpuscles of birds, fishes, and tor- 
toises, parasites are occasionally developed in the form of round “ pseudo-vacuoles ” from which 
free parasites are subsequently discharged (Danilewsky). In malarial conditions in man, pro- 
tozoon like organisms have been seen within the red corpuscles, the plasmodium malariae 
(Marchiafava). 
The white corpuscles are enormously increased in number in leukaemia (J. H. Bennett, 
Virchow). In some cases the blood looks as if it were mixed with milk. The colorless cor- 
puscles seemed to be formed chiefly in bone-marrow (E. Netvnann), and also in the spleen and 
lymphatic glands (myelogenic, splenic, and lymphatic leukaemia). 
ii. CHEMICAL CONSTITUENTS OF THE RED BLOOD- 
CORPUSCLES.—(1) The coloring matter or haemoglobin (Hb) is 
the cause of the red color of blood ; it also occurs in muscle and in traces in 
the fluid part of blood, but in the last case only as the result of the solution of 
some red corpuscles. Its percentage composition is, according to Hiifner, 
in the blood of the pig (and ox in brackets), C 54.71 (54.66), H 7.38 (7.25), 
N 17-43 (i7-7°)>.S °-479 (°-447> Fe °-399 (°-4o), O 19.602 (19.543). Its 
rational formula is unknown, but Preyer gives the empirical formula C600, H960, 
N154, Fe, S3, 0179. Although it is a colloid substance it crystallizes in all 
classes of vertebrates, according to the rhombic system, and chiefly in rhombic 
plates or prisms; in the guinea-pig in rhombic tetrahedra; in the squirrel, how- 
ever, it yields hexagonal plates. The varying forms, perhaps, correspond to 
slight differences in the chemical composition in different cases. Crystals sepa- 
rate from the blood of all classes of vertebrata during the slow evaporation of 
lake-colored blood, but with varying facility (fig. 19). 
[The following analysis shows the composition of the haemoglobin of the horse and dog, so 
that they do not seem to be quite identical in composition.] 
Haemoglobin of Horse. 
Haemoglobin of Dog. 
C 51.15 
53-91 
H 6.76 
6.62 
N 17.94 
15.98 
S 0.390 
0.542 
Fe 0.335 
o-333 
0 23 43 (.Zinoffsky). 
22.62 ( Jaquel).~\ 22 
HEMOGLOBIN. 
[Sec. 11. 
The coloring matter crystallizes with great difficulty from the blood of the calf, pig, pigeon, 
and frog; with difficulty from that of man, monkey, rabbit, and sheep; readily from that of the 
dog, cat, mouse, and horse; and very readily 
from that of the rat and guinea-pig \Preyer). 
[Copeman finds that colored crystals can be ob- 
tained from the blood of the frog. More rarely a 
crystal is formed from a single corpuscle enclosing 
the stroma. Crystals have been found near the 
nucleus of the large corpuscles of fishes, and in this 
class of vertebrates colorless crystals have been 
observed. Crystals of haemoglobin are readily 
found in the prepared blood of the salamander.] 
Dichroism. — Haemoglobin crystals 
are doubly refractive and pleo-chro- 
matic ; they are bluish-red with trans- 
mitted light, scarlet-red by reflected light. 
They contain from 3 to 9 per cent, water 
of crystallization, and are soluble in water, 
but more so in dilute alkalies. They are 
insoluble in alcohol, ether, chloroform, 
and fats. The solutions are dichroic ; red 
in reflected light, and green in transmitted 
light. In contact with protoplasmic cells, 
e.g., leucocytes, haemoglobin is destroyed 
in five days and regenerated again after 
twelve days (Schwartz). 
In the act of crystallization the haemoglobin 
seems to undergo some internal change. Before 
it crystallizes it does not diffuse like a true colloid, 
and it also rapidly decomposes hydric peroxide. 
If it be redissolved after crystallization, it diffuses, 
although only to a small extent, but it no longer 
decomposes hydric peroxide, and is decolorized 
by it. [The presence of O favors crystallization.] 
Haemoglobin crystals from blood, a, b, 
human; c, cat; d, guinea-pig; e, ham- 
ster ; f, squirrel. 
Fig. 19. 
12. PREPARATION OF HEMOGLOBIN CRYSTALS.—Method of Rollett.- 
Put defibrinated blood in a platinum capsule placed on a freezing mixture, freeze the blood, and 
then thaw it; pour the lake-colored blood into a plate until it forms a stratum not more than i]/2 
mm. in thickness and allow it to evaporate slowly in a cool place, when crystals will separate. 
Method of Hoppe-Seyler.—Mix defibrinated blood with io volumes of a 20 per cent, salt 
solution, and allow it to stand for two days. Remove the clear upper fluid with a pipette, 
wash the thick deposit of blood-corpuscles with water, and afterwards shake it for a long time 
with an equal volume of ether, which dissolves the blood-corpuscles. Remove the ether, filter 
the lake-colored blood, add to it % of its volume of cold alcohol (o°), and allow the mixture to 
stand in the cold for several days. The numerous crystals can be collected on a filter and pressed 
between folds of blotting-paper. 
Method of Gscheidlen.—Take defibrinated blood, which has been exposed for twenty-four 
hours to the air, and keep it in a closed tube of narrow calibre for several days at 370 C. When 
the blood is spread on glass, the crystals form rapidly. [Vaccine tubes answer very well.] 
[Method of Stirling and Brito.—It is in many cases sufficient to mix a drop of blood with 
a few drops of water on a glass slide, and to seal up the preparation. After a few days beautiful 
crystals are developed. The addition of water to the blood of some animals, such as the rat 
and the guinea-pig, is rapidly followed by the formation of crystals of haemoglobin. Very 
large crystals of reduced haemoglobin may be obtained from the stomach of the leech several 
days after it has sucked blood.] 
[Crystals of Reduced Haemoglobin may be .obtained from human blood ; (1) by the addi- 
tion to blood of decomposed serum, or of pericardial fluid; (2) treatment with bile, especially 
the bile of a cat; (3) agitation with ether; (4) semi-digestion in the stomach of the leech 
(Stirling, Bond, Copeman). They may also be obtained as reddish-violet colored prisms, but 
green in transmitted light if they are thin, by sealing up some putrefying Hb02 in a tube in an 
atmosphere of hydrogen (.Nencki and Sieber).] Sec. 13.] 
ESTIMATION OF HAEMOGLOBIN. 
23 
13. QUANTITATIVE ESTIMATION OF HEMOGLOBIN.—(a) From the 
Amount of Iron.—As dry (ioo° C.) haemoglobin contains 0.42 per cent, of iron, the amount 
of haemoglobin may be calculated from the amount of iron. If in represents the percentage 
IO0171 
amount of metallic iron, then the percentage of haemoglobin in blood is = — —. The procedure 
is the following: Calcine a weighed quantity of blood, and exhaust the ash with HC1 to obtain 
ferric chloride, which is transformed into ferrous chloride. The solution is then titrated with 
potassic permanganate. 
(b) Colorimetric Method.—Prepare a dilute watery solution of haemoglobin crystals of a 
known strength. With this compare an aqueous dilution of the blood to be investigated, by 
adding water to it until the color of the test solution is obtained. Of course, the solutions 
must be compared in vessels with parallel sides and of exactly the same width, so as to give 
the same thickness of fluid {Hoppe-Seyler). [In the vessel with parallel sides, or haematinometer, 
the sides are exactly 1 centimetre apart. Instead of using a standard solution of oxyhsemoglobin, 
a solution of picro-carminate of ammonia may be used (Rajewsky, Malassez).~\ 
(c) By the Spectroscope.—Preyer found that an 0.8 per cent, watery solution (1 cm. thick), 
allowed the red, the yellow, and the first strip of green to be seen (fig. 25, 1). Take the blood 
to be investigated (about o 5 c.cm.), and dilute it with water until it shows exactly the same 
optical effects in the spectroscope. If k is the percentage of Hb which allows green to pass 
through (o-8 per cent.), b, the volume of blood investigated (about 0.5 c.cm.), w, the necessary 
amount of water added to dilute it, then x — the percentage of Hb in the blood to be investi- 
gated— 
k(w + b) 
b '• 
It is very convenient to add a drop of caustic potash to blood and then to saturate it with 
€0. 
[(r/) The Hsemoglobinometer of Gowers is used for the clinical estimation of haemoglobin 
(fig. 20). “ The tint of the dilution of a given volume of blood with distilled water is taken 
as the index of the amount of 
haemoglobin. The distilled water 
rapidly dissolves out all the hae- 
moglobin, as is shown by the fact 
that the tint of the dilution 
undergoes no change on standing. 
The color of a dilution of average 
normal blood (one hundred times) 
is taken as the standard. The 
quantity of haemoglobin is indi- 
cated by the amount of distilled 
water needed to obtain the tint 
with the same volume of blood 
under examination as was taken 
of the standard. On account of 
the instability of a standard dilu- 
tion of blood, tinted glycerine- 
jelly is employed instead. This 
is perfectly stable, and by means 
of carmine and picro-carmine the 
exact tint of diluted blood can be 
obtained. The apparatus consists 
of two glass tubes of exactly the 
same size. One contains (D) a 
standard of the tint of a dilution 
of 20 cubic mm. of blood, in 2 cubic 
centimetres of water (1 in 100). The 
second tube (C) is graduated 100 
degrees = 2 centimetres (100 times 20 cubic millimetres). The 20 cubic millimetres of blood 
are measured by a capillary pipette (B). This quantity of the blood to be tested is ejected 
into the bottom of the tube, a few drops of distilled water being first placed in the latter. The 
mixture is rapidly agitated to prevent the coagulation of the blood. The distilled water is 
then added drop by drop (from the pipette stopper of a bottle (A) supplied for that purpose), 
until the tint of the dilution is the same as that of the standard, and the amount of water 
which has been added (*. e., the degree of dilution) indicates the amount of haemoglobin.” 
“ Since average normal blood yields the tint of the standard at 100 degrees of dilution, the 
Gowers’ hsemoglobinometer. A, pipette bottle for distilled 
water; B, capillary pipette ; C, graduated tube; D, tube 
with standard dilution; F, lancet for pricking the finger. 
Fig. 20. [Sec. 13. 
24 
ESTIMATION OF HAEMOGLOBIN. 
number of degrees of dilution necessary to obtain the same tint with a given specimen of blood 
is the percentage proportion of the hsemoglobin contained in it, compared to the normal. For 
instance, the 20 cubic millimetres of blood from a patient with anaemia gave the standard tint 
of 30 degrees of dilution. Hence it contained only 30 per cent, of the normal quantity of 
haemoglobin. By ascertaining with the haemacytometer the corpuscular richness of the blood, 
we are able to compare the two. A fraction, of which the numerator is the percentage of 
haemoglobin, and the denominator the percentage of corpuscles, gives at once the average value 
per corpuscle. Thus the blood mentioned above containing 30 per cent, of haemoglobin, con- 
tained 60 per cent, of corpuscles; hence the average value of each corpuscle was or yz of the 
normal. Variations in the amount of haemoglobin may be recorded on the same chart as that 
employed for the corpuscles. The instrument is only expected to yield approximate results, 
accurate within 2 or 3 per cent. It has, however, been found of much utility in clinical obser- 
vation.”] 
(e) Fleischl’s Haemometer.—For clinical purposes this instrument (fig. 21) is useful. A 
cylinder G, of two compartments a and af rests on a metallic table. Both compartments are 
filled with water, but in one (a) is placed a known quantity of blood measured in a measuring- 
tube of known capacity. The red color of the solution of hsemoglobin thus obtained is com- 
pared with a red wedge of glass (K), which is moved by means of a wheel (R and T) under the 
other compartment (a') until the two colors are identical. The illumination of the dilute 
blood solution and the red glass wedge is done from below by lamp light reflected from the 
white reflecting surface (S). The frame in which the red glass wedge is fixed bears numbers, 
and when the color is identical in the two compartments a and a', the percentage of haemo- 
globin as compared with normal blood 
can be read off directly. Suppose it to 
be 80 on the scale, then the blood ex- 
amined contains 80 per cent, of the 
haemoglobin of normal blood. 
[Bizzozero’s chromocytometer is 
largely used in Italy for the same 
purpose.] 
The amount of haemoglobin 
in man is 13.77 per cent., in the 
woman 12.59 Per cent., during 
pregnancy 9 to 12 per cent. 
(Preyer). According to Leichten- 
stern, Hb is in greatest amount in 
the blood of a newly-born infant, 
but after ten weeks the excess 
disappears. Between six months 
and five years it is smallest in 
amount; it reaches its second 
highest maximum between 
twenty-one and forty-five, and 
then sinks again. From the tenth 
year onwards, the blood of the 
female is poorer in Hb. The tak- 
ing of food causes a temporary 
decrease of the Hb owing to the 
dilution of the blood. 
[In Animals.—The quantity of blood varies with the animal investigated. The following 
Table by Beaunis gives the proportion of haemoglobin per 100 grams of blood :— 
Fig. 21. 
Fleischl’s haemometer. K, red colored wedge of glass 
moved by R; G, mixing vessel with two compart- 
ments a and a'; M, table with hole to read off the 
percentage of haemoglobin on the scale P; T, to 
move K; S, mirror of plaster of Paris. 
Sheep, 11.2 per ioo. 
Rabbit, 8.4 “ 
Fowl, 8.5 
Duck, 8.1 “] 
Man, 12.3 per 100. 
Dog, 13.8 “ 
Pig I3-2 
Ox, 12.3 “ 
Pathological.—A decrease is observable during recovery from febrile conditions, and also 
during phthisis, cancer, ulcer of the stomach, cardiac disease, chronic diseases, chlorosis, 
leukaemia, pernicious anaemia, and during the rapid mercurial treatment of syphilitic persons. 
During hunger the Hb seems to be more resistant than the other constituents of the blood 
(Groll). Sec. 14.] 
SPECTROSCOPE. 
25 
14. THE SPECTROSCOPE. —As the spectroscope is frequently used in the investigation 
of blood and other substances, a short description of the instrument is given here (fig. 22). It 
consists of—(1) a tube, A, which has at its peripheral end a slit, S (that can be narrowed or 
widened). At the other end a collecting lens, C (called a collimator), is placed, so that its 
focus is in exact line with the slit. Light (from the sun or a lamp) passes through the slit, and 
thus goes parallel through C to—(2) the prism, P, which decomposes the parallel rays into a 
colored spectrum, r, v. (3) An astronomical telescope is directed to the spectrum r, v, and 
the observer, B, with the aid of the telescope, sees the spectrum magnified from six to eight 
times. (4) A third tube, D, contains a delicate scale, M, on glass, whose image, when illumi- 
nated, is reflected from the prism to the eye of the observer, so that he sees the spectrum, and 
over or above it the scale. To keep out other rays of light the inner ends of the three tubes are 
covered by metal or by a black cloth (see also § 265). 
[The micro-spectroscope, e.g., as made by Browning or Zeiss, may be used when small 
quantities of a solution are to be examined. Every spectroscope ought to give two spectra, so 
that the position of any absorption-band may be definitely ascertained. The spectroscope is 
fitted into the ocular end of the tube of a microscope instead of the eye-piece. Small cells for 
containing the fluid to be examined are made from short pieces of barometer-tubes cemented to 
a plate of glass.] 
Fig. 22. 
Scheme of a spectroscope for observing the spectrum of blood A, tube; S, slit; m, my 
layer of blood with flame in front of it; P, prism; M, scale; B, eye of observer looking 
through a telescope; r', v', spectrum. 
Absorption Spectra.—If a colored medium (e. g., a solution of blood) be placed between 
the slit and a source of light, all the rays of colored light do not pass through it—some are 
absorbed; many yellow rays are absorbed by blood, hence that part of the spectrum appears 
dark to the observer. On account of this absorption, such a spectrum is called an “ absorption 
spectrum.” 
Flame Spectra.—If mineral substances be burned on a platinum-wire in a non-luminous 
flame or Bunsen’s burner in front of the slit, the elements present in the mineral or ash give 
a special colored band or bands, which have a definite position. Sodium gives a yellow, 
potassium a red and violet line. These substances are found on burning the ashes of almost all 
organs. 
If sunlight be allowed to fall upon the slit, the spectrum shows a large number of lines 
(Fraunhofer’s lines) which occupy definite positions in the colored spectrum. These lines are 
indicated by the letters A, B, C, D, etc., a, b, c, etc. (fig. 23). 
15. COMPOUNDS OF Hb WITH O; OXYHEMOGLOBIN 
AND METHEMOGLOBIN.—1. Oxyhaemoglobin (Hb02) behaves as 
a weak acid, and occurs to the extent of 86.78 to 94.3° per cent, in dry human 
red corpuscles (Jiidell). It is formed very readily whenever Hb comes into 26 
COMPOUNDS OF HAEMOGLOBIN. 
[Sec. 15. 
contact with O or atmospheric air. According to Bohr, x gramme Hb unites 
with 1.56 cubic centimetre of O at o° and 760 mm. Hg pressure, the union 
being stronger in weak than in concentrated solutions. Oxyhagmoglobin is a 
very loose chemical compound, and is slightly less soluble than Hb; its 
spectrum shows in the yellow and the green two dark absorption-bands, 
whose length and breadth in a 0.18 per cent, solution are given in fig. 23 (2). 
It occurs in the blood-corpuscles circulating in arteries and capillaries, as can 
Red. 
Orange. 
Yellow. 
Green. 
Cyan blue. 
Oxy- 
haemoglobin 
0.8 
Oxy- 
haemoglobin 
0.18 # 
Carbonic 
Oxide- 
Haemoglobin. 
Reduced 
Haemoglobin. 
Methse- 
moglobin. 
Haematin in 
Acid 
Solution. 
Haematin in 
an Alkaline 
Solution. 
Haemo- 
chromogen 
in Alkaline 
Solution. 
Reduced 
Hasmatin. 
Fig. 23. 
Spectra of haemoglobin and its compounds. 
be shown by the spectroscopic examination of the ear of a rabbit, of the prepuce, 
and the web of the fingers ( Vierordt). 
[Spectrum of Oxyhaemoglobin.—In the spectrum of a dilute solution of 
haemoglobin crystals or arterial blood, part of the red and violet rays are 
absorbed, but two well-marked absorption-bands exist between D and E. 
The line nearest D, i.e., next the red end of the spectrum, sometimes designated 
by the letter (a) is narrow, sharply defined, and black at its centre, and its 
position corresponds to the wave-length 579. The other absorption-band near 
E, conveniently designated by (/?), is broader, not so dark, and its edges are Sec. 15.] 
REDUCED HAEMOGLOBIN. 
27 
less sharply defined. Its centre corresponds to the wave-length 553.8. In 
very dilute solutions the a band is the only one visible. In a strong solution, 
as shown in fig. 23, the two bands fuse, but are again made visible as two on 
dilution of the blood.] 
[The spectrum necessarily varies with the concentration of the solution. Fig. 
24 shows how the absorption-bands increase with increase in the strength of the 
solution. With a 1 per cent, solution all the spectrum disappears, with the 
exception of the extreme red, and as the dilution continues we see successively 
the orange, green, yellow, blue, indigo, and violet. With .65 per cent, of 
Hb02 there is only one absorption-band.] 
Reduction of Oxyhsemoglobin.—It gives up its O very readily, however, 
even when means which set free absorbed gases are used. It is reduced (1) 
by the removal of the gases by the air-pump, (2) by the conduction through its 
solution of other gases (CO), and (3), by heating to the boiling-point. In the 
circulating blood its O is very rapidly given up to the tissues, so that in suffo- 
cated animals only reduced hcemoglobin is found in the arteries. Some con- 
stituents of the serum and sugar remove its O. 
Figs. 24 and 25. 
Fig. 24, graphic representation of the spectrum of Hb02. Fig. 25, the same of Hb, showing the 
amount of absorption with varying strengths of haemoglobin, the thickness of the fluid 
remaining the same. The numbers indicate the percentage of coloring matter. 
Spectrum of reduced Haemoglobin.—By adding to a solution of oxy- 
hsemoglobin reducing substances—e.g., ammonium sulphide, iron filings, or 
Stokes’s fluid [tartaric acid, iron proto-sulphate, and excess of ammonia]—the 
two absorption-bands of the spectrum disappear, and reduced haemoglobin 
(gas free), with one absorption-band, is formed. The color changes from 
a bright red to a purplish or claret tint. The two bands are reproduced by 
shaking the reduced haemoglobin with air, whereby Hb02 is again formed. 
Solutions of oxyhaemoglobin are readily distinguished by their scarlet color 
from the purplish tint of reduced haemoglobin. 
[The single absorption-band (fig. 23, 4), designated by the letter (j), lying 
about midway between the position of the two previous bands, is broader, 
fainter, less deeply shaded, and its centre is about, but not quite, intermediate 
between D and E. It extends between the wave-lengths 595 and 538, and 
is blackest opposite the wave-length 550, so that it lies nearer D than E. At 
the same time more of the blue rays are transmitted. On dilution the band is 
not resolved into two, but simply becomes fainter and disappears.] 
[According to Hermann, the absorption-band of Hb is not a single band, there being in 
addition a very narrow band towards the red end of the spectrum, but separate from the chief 
absorption-band by a very small interval.] 28 
CARBONIC OX IDE-HAEMOGLOBIN. 
[Sec. 15. 
[Haemoglobin has certain remarkable characters : (i) Although it is a crystal- 
loid body it diffuses with difficulty through an animal membrane, owing to the 
large size of its molecule. (2) It readily combines with O to form an unstable 
and loose chemical compound, oxyhaemoglobin. (3) This O it gives up readily 
to the tissues or other deoxidizing reagents. (4) Its composition is very com- 
plex, for, in addition to the ordinary elements present in proteids, it contains a 
remarkable amount of iron (0.4 per cent).] 
If a string be tied round the base of two fingers so as to interrupt the circulation, spectroscopic 
examination shows that the oxyhaemoglobin rapidly passes into reduced Hb (Vierordt). 
Cold delays this reduction; it is accelerated in youth, during muscular activity, or by suppressed 
respiration, and usually also during fever. 
The spectroscopic examination of small blood-stains is often of the utmost forensic import- 
ance. A minimal drop is sufficient. Dissolve the stain in a few drops of distilled water, and 
place the solution in a thin glass tube in front of the slit of the spectroscope. 
Para-haemoglobin.—If Hb02 be preserved under alcohol it passes into a modified form, 
which is insoluble in water (Nencki and Sieber). 
2. Methaemoglobin is a more stable, crystalline compound (Hoppe-Seyler). 
It contains the same amount of O as Hb02, but in a different chemical 
union, while the O is also more firmly united with it. It shows four absorp- 
tion-bands like haematin in acid solution (fig. 23, 5), of which that between 
C and D is distinct; the second is very indistinct, while the third and fourth 
readily fuse, so that these last two bands are only well seen with good apparatus. 
It is produced spontaneously in old brown blood-stains, in the crusts of bloody wounds, in cysts 
with sanguinolent contents, and in bloody urine. Chemically, it can be prepared from a solution 
ofllb by the action of potassic ferricyanide ( Jdderholm) or potassic chlorate (Marchand), [or by 
adding to a solution of Hb a freshly-prepared solution of potassic permanganate, by nitro-benzol, 
azobenzol, kairin, sodium nitrite, pyrogallic' acid]; and in nonlaky blood by alloxantin 
(.Kowalewsky). It crystallizes if defibrinated blood is shaken with amyl nitrite and the mahog- 
any-brown laky fluid be allowed to evaporate slowly (Halliburton). 
If a trace of ammonia be added to a solution of methaemoglobin, it gives an alkaline solution 
of methaemoglobin, which shows two bands like oxyhaemoglobin, of which the first one is the 
broader, and extends more towards the red. If ammonium sulphide be added to the methaemo- 
globin solution, reduced Hb is formed. 
[Action of Nitrites.—The addition of amyl nitrite dissolved in alcohol, or 
sodic or potassic nitrite to defibrinated blood causes the latter to assume a 
chocolate color, which, on the addition of ammonia, changes to red. The 
chocolate-colored fluid shows one well-defined band in the red, and less dis- 
tinctly other three bands like methaemoglobin (Gamgee').~\ 
[The nitrites therefore form a compound with its oxygen more firmly fixed than the O in 
Hb02, so that large doses of nitrites arrest the internal respiration and are poisonous. It is, 
however, affected by the products formed in the blood during asphyxia, while CO-Hb is not, 
the methaemoglobin formed by the nitrites is reduced by these products to Hb, which as it 
passes through the lungs takes up O.] 
16. CARBONIC OXIDE - HAEMOGLOBIN, POISONING 
WITH CO.—3. CO-Haemoglobin is a more stable chemical compound 
than the foregoing, and is produced at once when carbonic oxide is brought 
into contact with pure Hb or Hb02 (67. Bernard, 1857). It has an intensely 
florid ox che7'ry-red color, is not dichroic, and its spectrum shows two absorp- 
tion-bands, very like those of Hb02, but they are slightly closer together and 
lie more towards the violet (fig. 23, 3). Reducing substances which act upon 
Hb02, e.g., ammonium sulphide or Stokes’s fluid, do not affect these bands, 
i. <?., they cannot convert the CO-Hb into reduced Hb. If a 10 per cent, 
solution of caustic soda be added to a solution of CO-Hb, and heated, it gives 
a cinnabar-red color; while, with an Hb02 solution, it gives a dark brown, 
greenish, greasy mass. Spectrum analysis and the soda test enable one to dis- 
tinguish y HbCO, mixed with T7-jj Hb02. Oxidizing substances [solutions of Sec. 16.] 
CARBONIC OXIDE-HA£MOGLOBIN. 
29 
potassic permanganate (0.025 Per cent.), potassic chlorate (5 per cent.), and 
dilute chlorine solution] make solutions of CO-Hb cherry-red in color, while 
they turn solutions of Hb02 pale yellow. After this treatment both solutions 
show the absorption-bands of methsemoglobin, but those of the CO-Hb appear 
considerably later. If ammonium sulphide be added, Hb02 and CO-Hb are 
re-formed. 
Hb-CO Reactions.—Modified Soda Test.—Dilute the blood 20 times and add an equal 
volume of caustic soda (S. G. 1340) (Salkowskt). [Dilute 1 c.cm. HbCO with 50 c.cm. of 
water, to 10 c.cm. of this mixture add 0.2 c.cm. orange colored ammonium sulphide (2 grms. of 
sulphur are added to 100 c.cm. yellow ammonium sulphide), and then 0.2 c.cm. of 30 per cent, 
acetic acid. The HbCO blood becomes bright red, while normal blood becomes greenish-gray 
(Katayama).~\ 
On account of its stability, CO-Hb resists external influences and even putrefaction for a long 
time, and the two bands of the spectrum may be visible after many months. Landois obtained 
the soda test and spectroscopic bands in the blood of a woman poisoned eighteen months pre- 
viously by CO, and after great putrefaction of the body had taken place. [Stirling has kept 
CO-Hb in a stoppered bottle for five years without putrefaction taking place.] 
If CO or air containing it be inspired, it gradually displaces the O, volume 
for volume, out of the red blood-corpuscles, and death soon occurs; 1000 
c.cm. inspired at once will kill a man. A very small quantity in the air (T^T- 
TWo) suffices> in a relatively short time, to form a large quantity of CO-Hb. 
As continued contact with other gases (such as the passing of O through it for 
a very long time) gradually separates the CO from the Hb, with the formation 
of Hb02, it happens that, in very partial poisoning with CO, the blood grad- 
ually gets rid of the CO by the respiratory organs. It does not appear that any 
part is further oxidized into C02 in the organism. [CO-hgemoglobin, being a 
stable compound when once formed, circulates in the blood-vessels; but it 
neither gives up oxygen to the tissues, nor takes up oxygen in the lungs, hence 
its very poisonous properties. The real cause of death in animals poisoned with 
it is, that the internal respiration is arrested.] 
Poisoning with Carbonic Oxide.—Carbonic oxide is formed during the incomplete com- 
bustion of coal or coke, and passes into the air of the room, provided there is not a free outlet 
for the products of combustion. It occurs to the extent of 12-28 per cent, in ordinary gas, 
which largely owes its poisonous properties to the presence of CO. If the O be gradually dis- 
placed from the blood by the respiration of air containing CO, life can only be maintained as 
long as sufficient O can be obtained from the blood to support the oxidations necessary for life. 
Death occurs before all the O is displaced from the blood. CO has no effect when directly ap- 
plied to muscle and nerve. When it is mixed with air, as in coal-gas poisoning, and inhaled, 
there is first stimulation and afterwards paralysis of the nervous system, as shown by the symp- 
toms induced, e.g., violent headache, great restlessness, excitement, increased activity of the 
heart and respiration, salivation, tremors, and spasms. Later, unconsciousness, weakness, and 
paralysis occur, labored respiration, diminished heart-beat, and lastly, complete loss of sensibility, 
cessation of the respiration and heart-beat, and death. At first the temperature rises several 
tenths of a degree, but it soon falls i° or more. The pulse is also increased at first, but after- 
wards it becomes very small and frequent. In poisoning with pure CO there is no dyspnoea, 
but sometimes muscular spasms occur, the coma not being very marked. There is also tem- 
porary but pronounced paralysis of the limbs, followed by violent spasms. After death the 
heart and brain are congested with intensely florid blood. In poisoning with the vapor of 
charcoal, where CO and C02 both occur, there is a varying degree of coma; pronounced 
dyspnoea, muscular spasms which may last several minutes, gradual paralysis and asphyxia, 
moniliform contractions and subsequent dilatation of the blood-vessels, with congestion of various 
organs, occur, accompanied by a fall of the blood-pressure (Klebs), indicating initial stimulation 
and subsequent paralysis of the vaso-motor centre. This also explains the variations in the 
temperature and the occasional occurrence of sugar in the urine after poisoning with CO. After 
death, the blood-vessels are found to be filled with fluid blood of an exquisitely bright cherry-red 
color, while all the muscles and viscera and exposed parts of the body (such as the lips) have 
the same color. The brain is soft and friable; there is catarrh of the respiratory organs and 
degeneration of the muscles, and great congestion and degeneration of the liver, kidneys, and 
spleen. The spots of lividity, post-mortem, are bright red. After recovery from poisoning with 
CO there may be paraplegia and (although more rarely) disturbances of the cerebral activity. [Sec. 17. 
30 
COMPOUNDS OF HAEMOGLOBIN. 
17. OTHER COMPOUNDS OF HAEMOGLOBIN—4. Nitric 
Oxide-Haemoglobin (NO-Hb) is formed when NO is brought into contact 
with Hb (L. Hermann). 
As NO has a great affinity for O, red fumes of nitrogen peroxide (N02) being formed when- 
ever the two gases meet, it is clear that, in order to prepare NO-Hb, the O must first be removed. 
This may be done by passing Id through it [or ammonia may be added to the blood, and a stream 
of NO passed through jt; the ammonia combines with all the acid formed by the union of the 
NO with the O of the blood]. NO-Hb is a more stable chemical compound than CO-Hb, which, 
as we have seen, is again more stable than Hb02. It has a bluish-violet tint, and also gives 
two absorption-bands in the spectrum similar to those of the other two compounds, but not so 
intense. These bands are not abolished by the action of reducing agents. As NO-Hb cannot 
be formed in the body, it has no practical significance. 
The three compounds of Hb, with O, CO, and NO, are crystalline, like 
reduced Hb j they are isomorphous, and their solutions are not dichroic. 
All three gases unite in equal volumes with Hb. If O be conducted through a 
concentrated solution of Hb devoid of gases, a crystalline mass of Hb02 is 
thereby readily formed. 
5. Cyanogen, CNH {Hoppe-Seyler), and acetylene, C2H4 (.Bristow and Liebreich), form 
easily decomposable compounds with Hb. The former occurs in poisoning with hydrocyanic 
acid, and has a spectrum nearly identical with that of Hb02, and, like Hb02, it is reduced, but 
very slowly, by special reagents. [The existence of these compounds is, however, highly doubt 
ful ( Gamgee).~\ 
18. DECOMPOSITION OF HEMOGLOBIN.-In solution and in 
the dry state Hb gradually becomes decomposed, whereby the iron-containing 
pigment’ hsematin (along with certain bye-products, formic, lactic, and butyric 
acids), is formed. Haemoglobin, however, may be decomposed at once into— 
(1) Haematin, a body containing iron, and (2) a colorless proteid closely 
related to globulin ; by (a) the addition of all acids, even by C02 in the 
presence of plenty of water ; (b) strong alkalies ; (r) all reagents which coagu- 
late albumin, and by heat at 7o°-8o° C. ; (d) by ozone. 
(A) Haematin, C32H32N4Fe04 (.Nencki and Sieber), is a bluish-black amor- 
phous body, which forms about 4 per cent, of haemoglobin (dog). It is in- 
soluble in water, alcohol, and ether; soluble in dilute alkalies and acids, and 
in acidulated ether and alcohol. 
(1) Acid Haematin.—Lecanu extracted it from dry blood corpuscles by 
using alcohol containing sulphuric and tartaric acids. [If acetic acid be added 
to a solution of Hb and slightly heated, a mahogany-brown fluid is obtained, 
containing hcematin in acid solution, which gives a spectrum with one absorp- 
tion-band to the red side of D near C (fig. 23, 5). There is at the same 
time a considerable absorption of the blue end of the spectrum. If an ethereal 
extract of the acid-haematin be made, the ether is colored brown and shows 
four absorption-bands, as in fig. 23, 5.] 
(2) Alkali-haematin.—[If to the above solution ammonia or caustic soda 
be added, on heating gently, the color changes and the fluid becomes dichroic, 
showing a greenish tinge. On mixing the solution thoroughly with air the 
spectrum of oxy-alkali-haematin is obtained, i. e., one absorption-band just 
to the red side of D (fig. 23, 6), so that it is much nearer D than the corre- 
sponding band of acid-haematin. Much of the blue end of the spectrum is 
absorbed as well.] 
[(3) Reduced Alkali-haematin or Haemochromogen.—If the solution 
of alkali-haematin be reduced by ammonium sulphide, the spectrum of haemo- 
chromogen is obtained, viz., two absorption-bands between D and E, but 
they are nearer the violet end than in the case of Hb02 and Hb-CO (fig. 
23> 7)-] Sec. 18.] 
ILEMIN AND BLOOD TESTS. 
31 
[(4) Hsematoporphyrin or Iron-free Haematin.—On adding blood to 
concentrated sulphuric acid a clear purplish-red solution is obtained, which 
shows two absorption-bands, one close to and on the red side of D, and a 
second half-way between D and E. If water be added a brown precipitate is 
thrown down. When this precipitate is dissolved in caustic soda, it gives a 
fluid which shows four absorption-bands.] 
Action of CO,2.—If C02 be passed through a solution of oxyhemoglobin for a considerable 
time, reduced Hb is first formed; but if the process be prolonged the Hb is decomposed, a pre- 
cipitate of globulin is thrown down, and an absorption-band, similar to that obtained when Hb 
is decomposed with acids, is observed (p. 30). 
An alkaline solution of haematin, when reduced by tin and hydrochloric acid, 
yields urobilin (compare § 261). 
When haemoglobin is extravasated into the subcutaneous tissue, it becomes so altered that at 
first hsematoidin (§ 20), and ultimately hydrated oxide of iron, appear in its place. 
19. H./EMIN AND BLOOD TESTS.—In 1853 Teichmann prepared 
crystals of haemin from blood, which Hoppe-Seyler showed to be chloride 
of haematin (Haematin, -f- 2HCI), with the formula C32H31ClN4Fe03 (.Nencki 
and Sieber). The presence of these crystals is used as a test for blood-stains or 
blood in solution. They (fig. 26) are prepared by adding a small crystal of 
common salt to dry blood on a glass slide, and then an excess of glacial acetic 
acid ; the whole is gently heated until bubbles of gas are given off. On allow- 
ing the preparation to cool, the characteristic haemin crystals are obtained. 
Characters.—When well formed, the crystals are small microscopic rhombic 
plates, or rods ; sometimes they are single—at other times they are aggregated 
in groups, often crossing each other (fig. 26). Some kinds of blood (ox and 
pig) yield very irregular, scarcely crystalline, masses. The crystalline forms of 
haemin are identical in all the different kinds of blood that have been examined. 
They are doubly refractive ; under the polarization microscope they are a 
glancing yellow, appearing raised on the dark field, with a strong absorption of 
the light parallel to the long axis of the crystals (Falk and Morache). They 
are pleo-chromatic : by transmitted light they are mahogany-brown, and by 
reflected light bluish-black, glancing like steel. 
(1) Preparation from Dry Blood-Stains.—Place a few particles of the blood-stain on a 
glass slide, add 2 to 3 drops of glacial acetic acid and a small crystal of common salt; cover 
with a cover-glass, and heat gently over 
the flame of a spirit-lamp until bubbles of 
gas are given off. On cooling, the crys- 
tals appear in the preparation (fig. 26). 
(2) From Stains on Porous Bodies. 
—The stained object (cloth, wood, blot- 
ting-paper, earth) is extracted with a 
small quantity of dilute caustic potash, 
and afterwards with water in a watch- 
glass. Both solutions are carefully fil- 
tered, and tannic acid and glacial acetic 
acid are added until an acid reaction is 
obtained. The dark precipitate which is 
formed is collected on a filter and washed. 
A small part of it is placed on a micro- 
scope slide, a granule of common salt is 
added, and the whole dried; the dry 
stain is treated as in (1) (Struwe). 
(3) From Fluid Blood.—Dry the blood slowly at a low temperature, and proceed as in (1). 
(4) From Dilute Solutions of Haemoglobin.—(a) Struwe's Method.—Add to the fluid, 
ammonia, tannic acid, and afterwards glacial acetic acid, until it is acid; a black precipitate of 
tannate of haematin is thrown down. This is isolated, washed, dried, and treated as in (1), but 
instead of NaCl a granule of ammonium chloride is added. 
Hsemin crystals. I, human; 2, seal; 3, calf; 
4, pig; 5, lamb; 6, pike; 7, rabbit. 
Fig. 26. [Sec. 19. 
32 
PROTEIDS OF THE STROMA. 
Hgemin crystals may sometimes be prepared from putrefying or lake-colored 
blood, but they are very small, and the test often fails. When mixed with iron- 
rust, as on iron weapons, the blood-crystals are generally not formed. In such 
cases, scrape off the stains and boil them with dilute caustic potash. If blood 
be present, the dissolved hgematin forms a fluid, which in a thin layer is green, 
in a thick layer red (.H'. Rose). 
Haemin crystals have been prepared from all classes of vertebrates and from the blood of the 
earth-worm. From the blood of the ox and pig they may be almost amorphous. 
Chemical Characters.—They are insoluble in water, alcohol, ether, chloroform; but con- 
centrated H2S04 dissolves them, expelling the HC1, and giving a violet-red color. Ammonia 
also dissolves them, and if the resulting solution be evaporated, heated to 130° C., and treated 
with boiling water (which extracts the ammonium chloride), haematoporphyrin—identical with 
Mulder’s iron-free haematoin, and with Preyer’s haematoin, is obtained {Hoppe-Seyler). It is 
a bluish-black substance, which on being pounded forms a brown and amorphous powder. Its 
solutions in caustic alkalies aredichroic; in reflected light brownish-red; in transmitted light, 
in a thick stratum, red—in a thin one, olive green. The acid solutions are monochromatic and 
brown. 
Preparation in Bulk.—To obtain it in quantity, heat dried horse’s blood with 10 parts of 
formic acid. If the crystals be suspended in methyl alcohol, on adding iodine and heating them 
they dissolve with a purple color; after adding bromine, brown ; and after passing chlorine gas, 
green; all these give a characteristic spectrum (Axenfeld). 
The glacial acetic acid may be replaced by oxalic or tartaric acid, the common salt by salts of 
iodine or bromine; in the latter case similar bromine- or iodine-haematin is formed (.Bikfalvi). 
20. H/EMATOIDIN.—Virchow discovered this important derivative in 
haemoglobin. It occurs in the body wherever blood stagnates outside the cir- 
culation, and becomes decomposed—as when blood is extravasated into the 
tissues—e. g., the brain—in solidified blood-plugs or thrombi, especially in 
veins; invariably in the Graafian follicles. It contains no iron (C32H36N406), 
and crystallizes in clino-rhombic prisms (fig. 27) of a yellowish-brown color. 
It is soluble in warm alkalies and chloroform. Very probably it is identical 
with the bile pigment—bilirubin. [When acted upon by impure nitric acid 
(Gmelin’s reaction), it gives the same play of colors as bile.] 
Pathological.—In cases where a large amount of blood has undergone solution within the 
blood-vessels (as by injecting foreign blood) haematoidin crystals have been found in the urine. 
For their occurrence in the urine in jaundice ($ 180), and in the sputum (§ 138). 
21. (B.) THE COLORLESS PROTEID OF HAEMOGLOBIN.— 
It is closely related to globulin ; but while the latter is precipitated by all 
acids, even by C02, and re-dissolved on passing O 
through it, the proteid of haemoglobin, on the other 
hand, is not dissolved after precipitation on passing 
through it a stream of O. 
As crystals of haemoglobin can be decolorized under special 
circumstances, it is probable that these owe their crystalline form 
to the proteid which they contain. Landois placed crystals of 
haemoglobin along with alcohol in a dialyser, putting ether acidu- 
lated with sulphuric acid outside, and thereby obtained colorless 
crystals. [If frog’s blood be sealed up on a microscopic slide 
along with a few drops of water for several days, long colorless 
acicular crystals are developed in it (Stirling and Brito)i\ 
22. II. PROTEIDS OF THE STROMA.—Dry red human blood- 
corpuscles contain from 5.10-12.24 percent, of these proteids, but little is 
known about them (Jiidell). One of them is globulin, which is combined 
with a body resembling nuclein ( Wooldridge), and traces of a diastatic fer- 
ment {v. Wittich). The stroma tends to form masses which resemble fibrin. 
L. Brunton found a body resembling mucin in the nuclei of red blood-corpuscles, and Miescher 
■detected nuclein (§ 250, 2). 
Fig. 27. 
Haematoidin crystals. Sec. 22.] 
CONSTITUENTS OF RED BLOOD-CORPUSCLES. 
33 
[Stromata of the Red Corpuscles.—When mammalian red blood-corpuscles are treated 
with water—or other reagents, such as dilute acids, ether, etc.—the 80 or 90 per cent, of haemo- 
globin which they contain is dissolved out from the corpuscles, and the colorless less soluble part 
which remains is called the “ stroma.” The stromata retain somewhat the shape of the origi- 
nal corpuscles, and are composed of proteid, lecithin, cholesterin, and inorganic salts (chiefly 
potassium phosphate).] 
[The stromata are obtained by treating defibrinated blood with a very large volume of 1 per 
cent, sodic chloride. The proteids can be extracted from the stromata with various saline media, 
e.g.. Na2S04 (half-saturated), NaCl (5 per cent.), MgS04 (5 per cent.). 
The saline extract contains abundance of what Halliburton calls cell-globulin—a globulin 
that in heat-coagulation temperature, precipitability by salts and other reagents, and in ferment 
activity resembles the proteid called cell-globulin derived from lymph cells or white blood-corpus- 
cles (p. 34), so that stroma-globulin and cell-globulin are probably identical. Cell-Albumin is 
either absent or only present in minute traces, nor does nuclein or nucleo-albumin appear to be 
present, while the albumoses and peptones are certainly absent.] 
[The proteid cell globulin has fibrino-plastic properties, i. <?., it can cause the formation of fibrin 
to take place in a suitable fluid, e.g., hydrocele and pericardial fluid, but it is not decided whether 
the cell-globulin and fibrin-ferment are identical, or merely in close relationship with one another, 
the balance of evidence, however, being in favor of the former view [Halliburton). 
There is thus seen to be a very great difference between the proteids of the colored and the 
colorless corpuscles (p. 34), a matter of some importance in connection with the views one may 
hold regarding the true cellular nature of the colored corpuscles.] 
23. OTHER CONSTITUENTS OF RED BLOOD-CORPUS- 
CLES.—III. Lecithin (0.35-0.72 per cent.) in dry blood-corpuscles (§ 250, 
2). Cholesterin (0.25 per cent.) (§ 250, III), no Fats. 
Lecithin is regarded as a glycerin-phosphate of neurin, in which, in the radical of gly- 
cerin-phosphoric acid, two atoms of H are replaced by two molecules of the radical of stearic 
acid. By gentle heat glycerin-phosphoric acid is split up into glycerine and phosphoric acid 
(8 25o). 
These substances are obtained by extracting old stromata or isolated blood-corpuscles with 
ether. When the ether evaporates, the characteristic globular forms (“ myelin-forms ”) of 
lecithin and crystals of cholesterin are recognized. The amount of lecithin may be determined 
from the amount of phosphorus in the ethereal extract. 
IV. Water (681.63 per 1000—C. Schmidt). 
V. Salts (7.28 per 1000), chiefly compounds of potash and phosphoric acid; 
the phosphoric acid is derived only from the burned lecithin ; while the greater 
part of the sulphuric acid is derived from the burning of the haemoglobin in 
the analysis. 
Analysis of Blood.—1000 parts, by weight, of horse’s blood contain :— 
344.18 blood-corpuscles (containing about 128 per cent, of solids). 
655.82 plasma (containing about 10 per cent, of solids). 
1000 parts, by weight, of moist blood-corpuscles contain :— 
Solids, 367.9 (pig); 400.1 (ox). 
Water, 632.1 “ 599-9 “ 
The solids are :— 
Pig. Ox. 
Haemoglobin, 261 280.5 
Proteids, 86.1 107 
Lecithin, Cholesterin, and other Organic Bodies, . 12.0 7.5 
Inorganic salts, 8.9 4.8 
Potash 5.543 0.747 
Magnesia, 0.158 0.017 
Chlorine, 1.504 1.635 
Phosphoric Acid, 2.067 0-7°3 
Soda, o 2.093 [Bunge). 
Including - 
[An approximate estimate of the composition of human blood is given in 
the following table :— 34 
COMPOSITION OF BLOOD. 
[Sec. 23 
Composition of Human Blood as a Whole. 
Water, 780 
Solids—of these— 
Haemoglobin, 134 
Serum-albumin, 
Serum-globulin, 
70 
Fibrin of Clot (? Fibrinogen), 2.2 
Inorganic Salts (of serum), 6.0 
Extractives, 6.2 
Fatty matters, 1.4 
220 
Gases, O, C02, N.] 
Moist red blood-corpuscles contain 30-40 per cent, of solids and 70-60 per cent, of water. 
Of the dry solids of the red corpuscles at least 90 per cent, is haemoglobin, 8 proteid matter, and 
2 other substances.] 
24. CHEMICAL COMPOSITION OF THE WHITE CORPUS- 
CLES.—Investigations have been made on pus cells (Miescher), which closely 
resemble colorless blood-corpuscles. They contain several proteids ; alkali- 
albuminate, a proteid which coagulates at 48° C., an albuminate resembling 
myosin, paraglobulin, peptone, and a coagulating ferment; nuclein in the 
nuclei (§ 250, 2), glycogen (§ 252), lecithin, cerebrin, cholesterin, and fat. 
100 parts, by weight, of dry pus contain the following Salts :— 
[Proteids of the white corpuscles.—Halliburton used the lymph-corpuscles of lymphatic 
glands, from which the proteids were dissolved out by a partially saturated solution of sodium 
sulphate. These cells contain :— 
(1) Cell-globulin a, in small quantity. It coagulates at 48°-50° C. 
(2) Cell-globulin (3, in large quantity, and is either identical with or closely associated with 
the fibrin ferment. It coagulates in 5 per cent. MgS04 solution at 750 C. 
(3) Cell-albumin, which coagulates at 730 C. 
(4) Mucin-like body (Miescher), and called hyaline substance by Rovida. It is, however, not 
mucin, is rich in phosphorus, and yields nuclein on gastric digestion, in addition to albumoses 
and peptones, so that it belongs to the class of nucleo-albumins. 
(5) If the cells be not examined when they are quite fresh, they become acid from the forma- 
tion of sarcolactic acid, and the proteolytic action of a ferment (pepsin ?) found in the cell, 
comes into play with the subsequent formation of albumoses and peptones. 
The foregoing list of proteids may be taken as those present in a typical cell and in protoplasm 
generally.] 
25. BLOOD-PLASMA AND ITS RELATION TO SERUM.— 
The unaltered fluid in which the blood-corpuscles float is called blood-plasma, 
or liquor sanguinis. This fluid, however, after blood is withdrawn from the 
vessels, rapidly undergoes a change, owing to the formation of a solid fibrous 
substance—fibrin. After this occurs, the new fluid which remains no longer 
coagulates spontaneously (it is plasma, minus the fibrin-factors), and is called 
blood-serum. Apart from the presence of the fibrin-factors, the chemical 
composition of plasma and serum is the same. 
When blood coagulates, Table I shows what takes place, while Table II 
shows what occurs when it is beaten : — 
Earthy Phosphates, 0.416 
Sodic Phosphate, 0.606 
Potash, 0.201 
Sodic Chloride, 0.143 
I. 
II. 
Coagulation 
Blood. 
When beaten. 
Blood. 
Plasma. 
Corpuscles. 
Plasma. 
Corpuscles. 
Serum. 
Fibrin-factors. 
Fibrin-factors. 
Serum. 
Blood-clot. 
Fibrin. 
Defibrinated blood. Sec. 26.] 
BLOOD-PLASMA. 
35 
Plasma is a clear, transparent, slightly thickish fluid, which, in most animals 
(rabbit, ox, cat, dog), is almost colorless; in man it is yellow, and in the horse 
citron yellow. 
26. PREPARATION OF PLASMA.—(A) Without Admixture.— 
Taking advantage of the fact that plasma, when cooled to o° outside the body, 
does not coagulate for a considerable time, Briicke prepares the plasma thus : 
The blood of the horse (because it coagulates slowly, and its corpuscles sink 
rapidly to the bottom) is received, as it flows from an artery, into a tall narrow 
glass, placed in a freezing-mixture, and cooled to o°. The blood remains fluid, 
the colored corpuscles subside in a few hours, while the plasma remains above 
as a clear layer, which can be removed with a cooled pipette. If this plasma 
be then passed through a cooled filter, it is robbed of all its colorless corpuscles. 
[Burdon-Sanderson uses a vessel consisting of three concentric compartments— 
the outer and inner contain ice, while the blood is caught in the central com- 
partment, which does not exceed half an inch in diameter.] The quantity of 
plasma may be roughly (but only roughly) estimated by using a tall, graduated 
measuring-glass. If the plasma be warmed, it soon coagulates (owing to the 
formation of the fibrin), and passes into a trembling jelly. If, however, it be 
beaten with a glass rod, the fibrin is obtained as a white stringy mass, adhering 
to the rod. The quantity of fibrin in a given volume of plasma is very small 
(p. 36), although it varies much in different cases. 
(B) With Admixture.—Blood flowing from an artery is caught in a tall 
vessel containing of its volume of a concentrated solution of sodic sulphate 
(.Hewsori)—or in a 25 per cent, solution of magnesic sulphate (1 vol. to 4 vols. 
blood—Simmer)—or 1 vol. blood with 2 vols. of a 4 per cent, solution of 
monophosphate of potash (Masia). When the blood is mixed with these fluids 
and put in a cool place, the corpuscles subside, and the clear stratum of plasma 
mixed with the salts may be removed with a pipette. [The plasma so obtained 
is called “salted plasma.’’] If the salts be removed by dialysis, coagulation 
occurs; or it may be caused by the addition of water (Joh. Muller). Blood 
which is mixed with a 4 per cent, solution of common salt does not coagulate, so 
that it also may be used for the preparation of plasma. [For frog’s blood 
Johannes Muller used a per cent, solution of cane-sugar, which permits the 
corpuscles to be separated from the plasma by filtration. The plasma mixed 
with the sugar coagulates in a short time.] 
27. COAGULATION OF THE BLOOD.-FIBRIN.-[Blood within 
the living body is fluid, and when first shed it remains so for a short time. After 
a brief interval it becomes viscid, and then the whole mass becomes solid, clots, or 
coagulates, forming a complete jelly, so that at first the whole mass can be 
emptied out of the vessel in which it has set, and forms a mould having the shape 
of the vessel. The coagulation is due to the formation of a body called fibrin.] 
General Characters.—Fibrin is that substance which, becoming solid in 
shed blood, in plasma and in lymph causes coagulation of these fluids. In 
these fluids, when left to themselves, fibrin is formed, consisting of innumerable, 
excessively delicate, closely-packed, microscopic, doubly refractive fibrils, (fig. 
9, E). These fibrils entangle the blood-corpuscles as in a spider’s web, and 
form with them a jelly-like solid mass called the blood-clot, crassamentum, 
or placenta sanguinis. At first the clot is very soft, and after the first 2 to 
15 minutes a few fibres may be found on its surface; these may be removed 
with a needle, while the interior of the clot is still fluid. The fibres ultimately 
extend throughout the entire mass, which, in this stage, has been called cruor. 
After from 12 to 15 hours the fibrin contracts, or at least shrinks more and 
more closely round the corpuscles, and a fairly solid, trembling, jelly-like 36 
COAGULATION OF THE BLOOD. 
[Sec. 27. 
clot, which can be cut with a knife, is formed. During this time the clot takes 
the shape of the vessel in which the blood coagulates, and expresses from its 
substance a fluid—the blood-serum. Fibrin may be obtained by washing 
away the corpuscles from the clot with a stream of water. 
Crusta Phlogistica.—If the corpuscles subside very rapidly, and if the 
blood coagulates slowly, the upper stratum of the clot is not red, but only yel- 
lowish, on account of the absence of colored corpuscles. This is regularly the 
case in horse’s blood, and in human blood it is observed especially in inflamma- 
tions; hence this layer has been called crusta phlogistica. Such blood con- 
tains more fibrin, and so coagulates more slowly. 
The crusta is formed under other circumstanes, e. g., with increased sp. gr. of the corpuscles, 
or diminished sp. gr. of the plasma (as in hydrasmia and chlorosis), whereby the corpuscles sink 
more rapidly, and also during pregnancy. The taller and narrower the glass, the thicker is 
the crusta (compare \ 41). The upper end of the clot, where there are few corpuscles, shrinks 
more, and is therefore smaller than the rest of the clot. This upper, lighter-colored layer is 
called the “ buffy coat ” ; but it gradually passes both in size and color into the normal dark- 
colored clot. [Sometimes the upper surface of the clot is concave or “cupped.” The older 
physicians attached great importance to this condition, and also to the occurrence of the buffy 
coat.] 
Defibrinated Blood.—If freshly-shed blood be beaten or whipped with a 
glass rod, or with a bundle of twigs, fibrin is deposited on the rod or twigs in 
the form of a solid, fibrous, yellowish-white, elastic mass, and the blood which 
remains is called “ defibrinated blood” (p. 35.) [The twigs and fibrin must be 
washed in a stream of water to remove adhering corpuscles.] 
Coagulation of Plasma.—Plasma shows phenomena exactly analogous, 
save that the clot is not so well marked, owing to the absence of the resisting 
corpuscles; there is, however, always a soft trembling jelly formed when plasma 
coagulates. [In Hewson’s experiment on the blood of a horse tied in a vein, he 
found -that the plasma coagulated—fibrin being formed, so that he showed 
coagulation to be due to changes in the plasma itself (§ 29).] 
Properties of Fibrin.—Although the fibrin appears voluminous, it only 
occurs to the extent of 0.2 per cent. (0.1 to 0.3 per cent.) in the blood. The 
amount varies considerably in two samples of the same blood. It is insoluble in 
water and ether; alcohol shrivels it by extracting water ; dilute hydrochloric acid 
0.1 per cent.) causes it to swell up and become clear, and changes it into 
syntonin or acid-albumin (§ 249, III). When fresh, it has a grayish-yellow 
fibrous appearance, and is elastic ; when dried, it is horny, transparent, brittle, 
and friable. 
When fresh it dissolves in 6-8 per cent, solution of sodium nitrate or sulphate, in dilute 
alkalies, and in ammonia, thus forming alkali-albuminate. Heat does not coagulate these 
solutions. [It is also soluble in, or rather decomposed by, 5-10 per cent, solutions of neutral 
salts, e.g., NaCl, yielding two fibro-globulins (Green).] Hydric peroxide is rapidly decomposed 
by fibrin into water and O (Thenard). Fibrin which has been exposed to the air for a long 
time is no longer soluble in solution of potassic nitrate, but in neurin (Mauthner). During 
putrefaction it passes into solution, albumin being formed. Fibrin contains, entangled in it, 
ferric, calcic, and magnesic phosphates, and calcium sulphate, whose origin is unknown. [The 
ash of fibrin contains .88 to .95 per cent, of calcic phosphate.) 
Time for Coagulation.—The first appearance of a coagulum occurs in man’s blood after 
3 minutes 45 seconds, in woman’s blood after 2 minutes 20 seconds (H. Nasse). Age has no- 
effect ; withdrawal of food accelerates coagulation (//. Vierordt). 
28. GENERAL PHENOMENA OF COAGULATION.—I. Blood 
in direct contact with living unaltered blood-vessels does not 
coagulate. [Hewson (1772) found that when he tied the jugular vein of a 
horse in two places, and excised it, the blood did not coagulate fora long time.) 
Briicke filled the heart of a tortoise with blood which had stood 15 minutes 
exposed to the air at o°, and kept it in a moist chamber; at o° C. the blood was Sec. 28.] 
PHENOMENA OF COAGULATION. 
37 
still uncoagulated in the contracting heart after eight days. Blood in a con- 
tracting frog’s heart preserved under mercury does not coagulate. If the wall 
of the blood-vessel be altered by pathological processes (<?. g., if the intima 
becomes rough and uneven, or undergoes inflammatory change), coagulation is 
apt to occur at these places. Blood rapidly coagulates in a dead heart, or in 
blood-vessels (but not in capillaries) or other canals (<?. g., the ureter). If blood 
stagnates in a living vessel, coagulation begins in the central axis, because here 
there is no contact with the wall of the living blood-vessel. 
II. Conditions which Hinder or Delay Coagulation.—(a) The addition 
of small quantities of alkalies, ammonia, or concentrated solutions of neutral salts 
of the alkalies and earths (alkaline chlorides, sulphates, phosphates, nitrates, 
carbonates). Magnesic sulphate acts most favorably in delaying coagulation 
(i vol. solution of 28 per cent, to vols. blood of the horse). 
(b) Precipitation of the fibrino-plastin by adding weak acids, or C02. 
By the addition of acetic acid until the reaction is acid, coagulation is completely arrested. A 
large amount of C02 delays it, hence venous blood coagulates more slowly than arterial, and the 
blood of suffocated persons remains fluid for the same reason. 
(c) The addition of egg albumin, syrup, glycerine, and much water. If un- 
coagulated blood be brought into contact with a layer of already-formed fibrin, 
coagulation occurs later. 
(d) By cold (o° C.) coagulation may be delayed for one hour. If blood is 
frozen at once, after thawing it is still fluid, and then coagulates (Hewson). 
When shed blood is under high pressure it coagulates slowly. 
(e) Blood of embryo-fowls does not coagulate before the twelfth or fourteenth 
day of incubation (.Boll); that of the hepatic vein very slightly ; menstrual blood 
shows little tendency to coagulate when alkaline mucus from the vagina is mixed 
with it. If it be rapidly discharged, it coagulates in masses. Foetal blood at 
the moment of birth coagulates soon. 
(/) Blood rich in fibrin from inflamed parts coagulates slowly, but the clot so 
formed is firm. 
Of) [Blood coagulates more slowly in a smooth than a rough vessel, and also 
in a shallow vessel than in a deep one.] 
\fh) Blood in contact with pure oil coagulates more slowly than when it is in 
contact with glass or metal. Even a tube or vessel smeared with oil or vaseline 
delays coagulation, so that blood flows longer through such a tube without 
coagulating than through a glass or metal tube. The action seems to be a purely 
physical one between the blood and the oil.] 
if) Absence of oxygen. 
Injection of Peptones (albumoses) and other bodies.—Albertoni observed that if tryptic 
pancreas ferment (dissolved in glycerine) be injected into the blood of an animal, the blood 
when shed does not coagulate. Schmidt-Miilheim found that after the injection of peptone into 
the blood (0.5 gram per kilo.) of a dog, the blood lost its power of coagulating. [This occurs in 
the dog, but not in the rabbit. Peptonized blood coagulates when it is treated with C02 or water. 
It appears, however, that it is not the peptone which prevents the coagulation, but the albumoses 
adhering to it which do so.] A substance is formed in the plasma, which prevents coagulation, 
but which is precipitated by C02. Lymph behaves similarly (Fano). After peptones are 
injected, there is a great solution of leucocytes in the blood (y. Samson-Himmelstjerna). The 
secretion of the mouth of the medicinal leech [although its action is not due to a ferment 
(.Haycraft)~\, and snake poison also prevent coagulation ( Wall). [Diastatic ferment (Salvioli) 
and the poisonous substance in the serum of eels’ blood (Mosso) also prevent coagulation]. 
Haemophilia.—A very slight scratch in some persons may cause very free bleeding. These 
persons are called colloquially “bleeders,” and are said to have haemophilia or the haemor- 
rhagic diathesis. In “ bleeders ” coagulation seems not to take place, owing to a want of the 
substances producing fibrin; hence, in these cases, wounds of vessels are not plugged with 
fibrin. [A tendency to hemorrhage occurs in scurvy, purpura, in some infectious diseases, 
such as typhus, plague, yellow fever, and in poisoning with phosphorus.] 38 
RAPIDITY OF COAGULATION. 
[Sec. 28. 
[Leech Extract.—A watery extract of the buccal cavity of the leech—the secretion probably 
is derived from the epithelial cells lining the sucker and buccal cavity—when injected into the 
blood-vessels of a dog or rabbit, or mixed with the uncoagulated blood of these animals, prevents 
coagulation for a much longer time than is the case with the injection of so called peptones, for 
it is really the albumoses mixed with the peptones which prevent coagulation in the blood of the 
dog. The action of leech-extract, like that of the products of digestion, is not permanent. 
When injected it produces far milder constitutional symptoms than albumose, but its action on 
the blood is far more powerful. It is eliminated by the kidneys. So far this active principle has 
not been isolated, although it is soluble in water, saline solutions, and insoluble in alcohol, ether, 
and chloroform (Haycraft).~\ 
III. Coagulation is accelerated—(a) By contact with foreign Sub- 
stances of all kinds, but only when the blood adheres to them, hence threads 
or needles introduced into arteries are rapidly covered with fibrin. [The 
coagulation always begins around the foreign body.] Blood does not coagulate 
in contact with bodies covered with fat or vaseline (.Freund). Even the intro- 
duction of air-bubbles into the circulation or the passage of indifferent gases, N 
or H, through blood, accelerates it. The pathologically altered wall of a vessel 
acts like a foreign body. Blood shed from an artery rapidly coagulates on the 
walls of vessels, on the surfaces exposed freely to air, and on the rods or twigs 
used to beat it. 
(t?) The products of the retrogressive metabolism of proteids (uric acid, 
glycin, leucin, taurin, kreatin, sarkin, but not urea) favor coagulation by 
increased ferment-formation ; but if they are added in excess, they retard the 
process. 
(c) From a watery extract of the testis or thymus, on the addition of acetic acid, is precipitated 
a substance which is soluble in sodic carbonate. It is a mixture of lecithin and albumin, and 
when it is injected into the blood-stream it causes almost instantaneous death by intravascular 
coagulation ( Wooldridge). [Injection of a watery extract of the thymus, supra-renal capsules, 
and testis suffice to produce extensive intra-vascular clotting, and even the injection of laky blood 
accelerates coagulation.] 
(d) During rapid hemorrhage, the last portions of blood coagulate most 
rapidly (Holzmann). 
(<?) Heating the blood from 390 to 550 C. (Hewson). 
{/) Agitation of the blood (.Hewson and Hunter). 
[(£•) The addition of a small quantity of water. 
(h) A watery condition of the blood. The clot is small and soft. 
(1) Contact with oxygen, or free exposure to the air. 
But contact with oxygen is not necessary for coagulation to take place, as 
this occurs in contact with indifferent gases, as well as in a vacuum.] 
IV. Rapidity of Coagulation.—Amongst vertebrates, the blood of birds 
(especially of the pigeon) coagulates almost momentarily; in cold-blooded 
animals coagulation occurs much more slowly, while mammals stand midway 
between the two. 
[The blood of a fowl begins to coagulate in x/2 to \]/2 minute; pig, sheep, rabbit, in y'2 to \l/2 
minute; dog, 1 to 3 minutes; horse and ox, 5 to 13 minutes; man, 3 to 4 minutes; solidifica- 
tion is completed in 9 to 11 minutes (Nasse).~\ The blood of invertebrates, which is usually 
colorless when it is oxidized ($ 32), forms a soft, whitish clot of fibrin. Even in lymph and 
chyle a small soft clot is formed. 
V. When coagulation occurs, the aggregate condition of the fibrin-factors is 
altered, so that heat must be set free ( Valentin, 1844). 
VI. In blood shed from an artery, the degree of alkalinity diminishes 
from the time of its being shed until coagulation is completed (Pfliiger and 
Zuntz). This is probably due to a decomposition in the blood, whereby an 
acid is developed, which diminishes the alkalinity (p. 2). 
VII. During coagulation there is a diminution of the O in the blood, 
although a similar decrease also occurs in non-coagulated blood. Traces of Sec. 28.] 
CAUSE OF COAGULATION OF BLOOD. 
39 
ammonia are also given off, which Richardson erroneously supposed to be the 
cause of the coagulation of the blood. 
[This is refuted—(i) by the fact that blood, when collected under mercury (whereby no escape 
of ammonia is possible) also coagulates; and (2) by the following experiment of Lister:—He 
placed two ligatures on a vein containing blood, moistening one-half of the outer surface of the 
vein with ammonia, leaving the other half intact. The blood coagulated in the first half, and 
not in the other, owing to the properties of the wall of the vein of the former being altered. 
Neither the decrease of O nor the evolution of ammonia seems to have any causal connection 
with the formation of fibrin.] 
Pathological.—When the blood coagulates within the vessels during life, the process is called 
thrombosis, and the coagulum or plug so formed is termed a thrombus. When a clot of 
blood or other body is carried by the blood-stream to another part of the vascular system where 
it blocks up a vessel, the plug is called an embolus, and the result embolism. 
Coagulable Fluids.—With regard to coagulability, fluids containing 
proteids may be classified thus :— 
(1) Those that coagulate spontaneously, i. e., blood, lymph, chyle. 
(2) Those capable of coagulating, e. g., fluids secreted pathologically in serous cavities; for 
example, hydrocele fluid, which, as usually containing fibrinogen only, does not coagulate spon- 
taneously, but it coagulates on the addition of fibrino-plastin and ferment (or of blood-serum, in 
which both occur). 
(3) Those which do not coagulate, e. g., milk or seminal fluid, which do not seem to contain 
fibrinogen. 
29. CAUSE OF THE COAGULATION OF BLOOD.—[Hewson’s Experiments 
(1772).—Hewson tied the jugular vein of a horse between two ligatures, removed it, and then 
suspended it by one end (Fig. 28). He found that the blood remained fluid for 
a long time (48 hours), the red corpuscles sank (RC), and left a clear layer of 
plasma on the surface (P). On drawing off some of this clear plasma it coagu- 
lated, thus proving coagulation to be due to changes in the plasma. If a glass 
rod be pushed through the wall of the vessel into the fluid, coagulation begins 
around the foreign body. The glass rod, however, must not be perfectly smooth. 
Lister repeated this experiment, and found that, even if the upper end of the 
tube be opened and the blood freely exposed to the air, coagulation is but slightly 
hastened. He showed that the blood might be poured from one vein into 
another, just as one might pour fluid from one test-tube into another. In this 
case there were two test-tubes, i. e., the veins—and although the blood, on being 
poured from the one to the other, came into contact with the air, it did not 
coagulate. Hewson, however, found that blood poured from the vein into a 
glass vessel coagulated, so that, in his opinion, the blood-vessels exerted a 
restraining influence on coagulation. By cooling the blood and preventing it from 
coagulating, he proved that coagulation was not due to the loss of heat. Nor 
could it be a vital act, as sodic sulphate or other neutral salt prevented coagu- 
lation indefinitely, but coagulation took place when the blood was diluted with 
water.] 
[Buchanan’s Researches.—The serous sacs of the body contain a fluid 
which in some respects closely resembles lymph. The pericardial fluid of some 
animals coagulates spontaneously (e. g., in the rabbit, ox, horse, and sheep) if 
the fluid be removed immediately after death. If this be not done till several 
hours after death, the fluid does not coagulate spontaneously. The fluid of the 
tunica vaginalis of the testis sometimes accumulates to a great extent, and con- 
stitutes hydrocele, but this fluid shows no tendency to coagulate spontaneously. Andrew 
Buchanan found, however, that if to the fluid of ascites, pleuritic fluid, or hydrocele fluid, there 
be added clear blood-serum, then coagulation takes place, i.e., two fluids—neither of which 
shows any tendency by itself to coagulate—form a clot when they are mixed (1831). He also 
found that if “ washed blood-clot” (which consists of a mixture of fibrin and colorless cor- 
puscles) be added to hydrocele fluid, coagulation occurred. He compared the action of washed 
blood-clot to the action cf rennet in coagulating milk, and he imagined the agents which deter- 
mined the coagulation to be colorless corpuscles. Thus, the buffy coat of horses’ blood is a power- 
ful agent, and it contains numerous colorless corpuscles. He finally concluded that some con- 
stituent in the plasma, to which he gave the name of a “ soluble fibrin,” is acted upon by the 
colorless corpuscles and converted into fibrin. The soluble fibrin of Buchanan is comparable to 
the fibrinogen in Hammarsten’s theory. Buchanan, however, did not separate the substance.] 
[Denis’s Plasmine (1859).—Denis mixed uncoagulated blood with a saturated solution of 
sodic sulphate, and allowed the corpuscles to subside. The salted plasma thus obtained he pre- 
Fig. 28. 
Vein of horse 
tied between 
two ligatures. 
P, plasma; 
WC, white; 
and RC, red 
corpuscles. 40 
THEORIES OF BLOOD COAGULATION. 
[Sec. 29. 
cipitated with sodic chloride. The precipitate, when washed with a saturated solution of sodic 
chloride, he called plasmine. If plasmine be mixed with water, it coagulates spontaneously, 
resulting in the formation of fibrin, while another proteid remains in solution. According to 
the view of Denis, fibrin is produced by the splitting up of plasmine into two bodies—fibrin and 
a soluble proteid.] 
[If to plasma, e. g., from horse’s blood, there be added NaCl to the extent of 13 per cent., a 
white viscid precipitate is thrown down. If this precipitate be removed, and more NaCl added, 
or MgS04 crystals, another proteid, white and granular, is precipitated. The former is fibri- 
nogen, and the latter para-globulin, so that the so-called plasmine of Denis really consists of 
two proteids; only the former, however, is converted into fibrin.] 
[Briicke’s experiments were directed to the question why the blood does not coagulate 
within the vessels. Hewson had shown that blood remains fluid for 6-14 hours in the vessels 
after the death of the animal (dog). In the case of cold-blooded animals, e.g., the turtle at -f- 
i° C., the blood remained fluid for six to eight days. Again, the blood remained fluid in the 
excised heart of a turtle kept moist under a bell jar as long as the heart continued to beat and 
until the cardiac walls lost their excitability. A foreign body introduced into the blood-vessels 
was soon surrounded with a clot of fibrin, which was always deposited on the foreign body itself 
and not on the walls of the blood-vessels. The same results were obtained in mammals, and 
especially in new-born animals. This action of the vascular wall in preventing coagulation 
only exists as long as the wall itself is intact and alive.] 
[Lister maintained that the blood has no spontaneous tendency to clot, as Briicke supposed, 
but that it only clots when brought into contact with foreign matter, and this is the view now 
generally held.] 
[A. Schmidt’s Researches (i86x).—This observer rediscovered the chief facts already 
known to Buchanan, viz., that some fluids which do not coagulate spontaneously clot when 
mixed with other fluids, which show no tendency to coagulate spontaneously, e.g., hydrocele 
fluid and blood-serum. He isolated from these fluids the bodies described as fibrinogen and 
fibrino-plastin. The bodies so obtained were not pure, but Schmidt supposed that the formation 
of fibrin was due to the interaction of these two proteids. The reason hydrocele fluid does not 
coagulate, he says, is that it contains fibrinogen and no fibrino-plastin, while blood-serum con- 
tains the latter, but not the former. Schmidt afterwards discovered that these two substances 
maybe present in a fluid, and yet coagulation may not occur (e.g., occasionally in hydrocele fluid). 
He supposed, therefore, that blood or blood-serum contained some other constituent necessary 
for coagulation. This he afterwards isolated in an impure condition and called fibrin-ferment.} 
A. Schmidt’s theory of Coagulation is that fibrin is formed by the 
coming together of two proteid substances which occur dissolved in the plasma, 
viz. : (1) fibrinogen, i. e., the substance which yields the chief mass of the 
fibrin, and (2) fibrino-plastic substance or fibrino-plastin. The latter 
terms are now rarely used, having been replaced by either of the following— 
serum-globulin or para-globulin, § 32. In order to determine the coagulation 
a ferment seems to be necessary, and this is supplied by (3) the fibrin- 
ferment. [Reviewing all the evidence, it seeme quite certain that para- 
globulin is not concerned in the process of coagulation, so that Schmidt’s 
theory has now given place to that of Hammarsten (p. 42).] 
1. Properties of Fibrinogen and fibrino-plastin.—They belong to the 
group of proteids called globulins, i. e., they are insoluble in pure water, but 
are soluble in dilute saline solutions (e.g., common salt, § 249), and are not 
distinguished from each other by well-marked chemical characters. Still they 
differ as follows :— 
Fibrino-plastin or Serum-globulin is more easily precipitated from its 
solutions than fibrinogen. It is more readily redissolved when once it is pre- 
cipitated. It forms when precipitated a very light granular powder [and its 
saline solution coagulates at 750 C.]. 
Fibrinogen adheres as a sticky deposit to the side of the vessel. It coagu- 
lates at 56° C. 
On account of their great similarity, both substances are not usually prepared 
from blood-plasma. Fibrinogen is prepared from serous transudations (pericar- 
dial, abdominal, or pleuritic fluid, or the fluid of hydrocele), which contain 
no fibrino-plastin. Fibrino-plastiti is most readily prepared from serum, in which 
there is still plenty of fibrino-plastin, but no fibrinogen. Sec. 29.] 
FIBRIN AND ITS FACTORS. 
41 
2. Preparation of Fibrino-plastin, Serum-globulin, or Paraglobulin. 
—(a) Dilute blood-serum with twelve times its volume of ice-cold water, and 
almost neutralize it with acetic acid [add 4 drops of a 25 per cent, solution of 
acetic acid to every 120 c.c. of diluted serum]; or (b) pass a stream of carbon 
dioxide through the diluted serum, which soon becomes turbid ; after a time a 
fine white powder, copious and granular, is precipitated. 
[(V) Method of Hammarsten for Serum-globulin.—All the serum- 
globulin in serum is not precipitated either by adding acetic acid or by C0.2. 
Hammarsten found, however, that if crystals of magnesium sulphate be added 
to complete saturation, it precipitates the serum-globulin, but does not precipi- 
tate serum-albumin ; serum-globulin is more abundant than serum-albumin in 
the serum of the ox and horse, while in man and the rabbit the reverse obtains; 
(compare § 32).] 
Schmidt found that 100 c.c. of the serum of ox-blood yielded 0.7 to 0.8 grm.; horse’s serum, 
0.3 to 0.56 grm. of dry fibrino-plastin. Fibrino-plastin occurs not only in serum, but also in red 
blood-corpuscles, in the fluids of connective-tissue, and in the juices of the cornea. 
3. Preparation of Fibrinogen.—This is best prepared from hydrocele 
fluid, although it may also be obtained from the fluids of serous cavities, e.g., 
the pleura, pericardium, or peritoneum. It does not exist in blood-serum, 
although it does exist in blood-plasma, lymph, and chyle, from which it may be 
obtained by a stream of C02, after the paraglobulin is precipitated. (a) Dilute 
hydrocele fluid with ten to fifteen times its volume of water, and pass a stream 
of C02 through it for a long time. ([b) Add powdered common salt to satura- 
tion to a serous transudation, when a sticky, glutinous (not very abundant) pre- 
cipitate of fibrinogen is obtained. 
[Hammarsten and Eichwald find that, although paraglobulin and fibrinogen are soluble in 
solutions of common salt (containing 5 to 8 per cent, of the salt), a saline solution of 12 to 16 
per cent, is required to precipitate the fibrinogen, leaving still in solution paraglobulin, which is 
not precipitated until the amount of salt exceeds 20 per cent.] 
Properties of the so-called Fibrin-Factors.—They are insoluble in 
pure water, but dissolve in water containing O in solution. Both are soluble 
in very dilute alkalies, e. g., caustic soda, and are precipitated from this solution 
by C02. They are soluble in dilute saline solutions, e.g., of common salt— 
like all globulins—but if a certain amount of common salt and some other salts, 
e.g., MgS04, be added in excess, they are precipitated. Very dilute hydro- 
chloric acid dissolves them, but after several hours they become changed into 
a body resembling syntonin or acid-albumin (§ 249, III). Fibrinogen held 
in solution by common salt coagulates at 520 to 550 C. [Fredericq finds the 
fibrinogen exists as such in the plasma; it coagulates at 56° C., and the plasma 
thereafter is uncoagulable spontaneously.] 
4. Preparation of the Fibrin-Ferment.—(a) Mix blood-serum (ox) 
with twenty times its volume of strong alcohol, and after one month filter off 
the deposit thereby produced. The deposit on the filter consists of coagulated 
insoluble albumin and the ferment; dry it carefully over sulphuric acid, and 
reduce to a powder. Triturate 1 gram of the powder with 65 c.c. of water for 
ten minutes, and filter. The ferment is dissolved by the water, and passes 
through the filter, while the coagulated albumin remains behind. 
[(£) Gamgee’s Method.—Buchanan’s “washed blood-clot” (p. 39) is digested in an 8 per 
cent, solution of common salt. The solution so obtained possesses in an intense degree the 
properties of Schmidt’s fibrin-ferment.] 
In the preparation of fibrino-plastin, the ferment is carried down with it mechanically. The 
ferment seems to be formed first in fluids outside the body, very probably by the dissolution of 
the colorless corpuscles. More ferment is formed in the blood the longer the interval between 
its being shed and its coagulation. It is destroyed at 70° C. Blood flowing directly from an 
artery into alcohol contains no ferment. It is also formed in other protoplasmic parts (Rausch- 42 
hammarsten’s theory. 
[Sec. 2g. 
enback), e. g., in dead muscle, brain, supra-renal capsule, spermatozoa, testicle (Foa and Pel- 
lacani), and in vegetable micro-organisms [e.g., yeast] and protozoa (Grohmann), [so that it 
would seem to be a general product of protoplasm. As the ferment does not pre-exist in color- 
less blood-corpuscles, it seems to be formed from some mother-substance in them, the blood- 
plasma itself decomposing this substance.] 
Coagulation Experiments.—According to A. Schmidt, if pure solutions of (i) fibrinogen, 
(2) fibrino-plastin, and (3) fibrin-ferment be mixed, fibrin is formed. [As we have already seen, 
(2) is not essential.] The process goes on best at the temperature of the body; it is delayed at 
o°; and the ferment is destroyed at the boiling-point. The presence of O seems necessary for 
coagulation. The amount of the ferment appears to be immaterial; large quantities produce 
more rapid coagulation, but the amount of fibrin formed is not greater. 
[Foa and Pellacani find that a filtered watery extract of fresh brain, supra-renal capsules, 
testis, thymus, and some other tissues, when injected into the blood-vessels of a rabbit, causes 
coagulation of the blood in the pulmonary circulation and the heart, death being caused by the 
action of a substance identical with the fibrin-ferment ] 
[Nature of the fibrin-ferment.—-It is a proteid belonging to the group of the globulins, 
and, according to Halliburton, it has the properties of a cell-globulin, i. e., a globulin obtained 
from the disintegration of cells, e.g., leucocytes or lymph-corpuscles (p. 34). The fibrin-ferment 
is (almost) identical with this cell-globulin. A very considerable quantity of active blood-fer- 
ment may be injected into the blood-vessels of a living animal without causing coagulation within 
the blood-vessels. It may be that the ferment is destroyed within the vascular system.] 
[What the exact nature of the action of fibrin-ferment is on the fibrinogen in shed blood we 
do not know; but the amount of fibrin formed is always slightly less than the amount of 
fibrinogen acted on, there being always formed a small amount of another globulin. If the 
solution of fibrin-ferment be boiled, all its coagulation-determining properties are at once and 
permanently destroyed.] 
The amount of salts present has a remarkable relation to coagulation. 
Unless a certain amount of salts be present in the fluid (1 per cent. NaCl), 
coagulation takes place slowly or partially. Freund has shown that the process 
of coagulation is always accompanied by an excretion of phosphates of the 
alkaline earths. Fibrin contains a constant amount of phosphates of the alka- 
line earths (p. 37). Coagulable fluids coagulate after the addition of these 
salts; they do not coagulate in the absence of these salts. The action of adhe- 
sion (p. 38) in accelerating coagulation is said to depend on the occurrence of 
the interaction during life of the phosphoric acid or alkaline phosphates present 
specially in the cellular elements of the blood with the lime and magnesia salts 
present especially in the plasma. [Green finds that calcium sulphate brings 
about coagulation in plasma which shows little or no tendency to clot, while 
coagulation in its absence is almost or quite prevented.] 
[Ringer and Sainsbury have studied the influence of salts on the clotting of blood (and also 
certain pathological fluids, e.g., of ascites, hydrocele fluid, and milk). They confirm Green’s 
statement that calcium sulphate is an essential to the act of clotting, but they find that calcium 
chloride also acts very efficiently in determining coagulation. The salts of strontium and barium 
act like those of calcium sulphate, but are less powerful. The soda and potash salts (NaCl and 
KC1), on the other hand, restrain, prolong, or prevent the act of coagulation ; but the soda salts 
are rather more powerful than the potassium salts. The addition of lime salts overcomes the 
restraining influence of the soda and potash salts, so that there is an antagonism between the 
salts of lime on the one hand, and of potassium and sodium on the other.] 
When blood or blood-plasma coagulates, all the fibrinogen is used up, so that 
the serum contains only fibrino-plastin and fibrin-ferment; hence the addition 
of hydrocele fluid (which contains fibrinogen) to serum causes coagulation. 
[Hammarsten’s Theory of Coagulation.—Hammarsten’s researches 
led him to believe that fibrino-plastin is quite unnecessary for coagulation. 
According to him, fibrin is formed from one body, viz., fibrinogen, which is 
present in plasma when it is acted upon by the fibrin-ferment; the latter, 
however, has not been obtained in a pure state. Neither he nor Schmidt assert 
that this body is of the nature of a ferment, although they use the term for con- 
venience. It is quite certain that fibrin may be formed when no fibrino-plastin 
is present, coagulation being caused by the addition of calcic chloride or casein Sec. 29.] 
SOURCE OF THE FIBRIN-FACTORS. 
43 
prepared in a special way. One of the conditions necessary for the action of 
fibrin-ferment on fibrinogen seems to be the presence of neutral salts. If the 
latter be completely removed the formation of fibrin does not take place. Lime 
salts seem to be in some way essential to the process, e. g., calcic sulphate, while 
others attach importance to the presence of NaCl.] 
[The main drift of the foregoing evidence points to the presence of one proteid 
—fibrinogen—which exists dissolved in the blood-plasma, and which under 
certain circumstances yields fibrin. In shed blood this act seems to be deter- 
mined by a ferment, perhaps derived from the disintegration of colorless cor- 
puscles (and blood-platelets?), which occurs when blood is shed.] 
[It must not be forgotten that the presence of certain salts seems necessary 
to the act of coagulation. As the question at present stands, three factors are 
recognized in the equation :— 
(1) A coagulable proteid (fibrinogen). 
(2) A ferment. 
(3) Certain salts. 
Up till recently the first two have attracted the greatest amount of attention, 
but that the third factor is also an important one is shown by the above-men- 
tioned researches.] 
30. SOURCE OF THE FIBRIN-FACTORS. —Al. Schmidt maintains that all the 
three substances out of which fibrin, according to him, is formed arise from the breaking up of 
colorless blood-corpuscles. In the blood of man and mammals fibrinogen exists dissolved in the 
circulating blood as a dissolution-product of the retrogressive changes of the white corpuscles. 
Plasma contains dissolved fibrinogen and serum-albumin. The circulating blood is very rich in 
colorless blood-corpuscles—much richer, indeed, than was formerly supposed. As soon as blood 
is shed from an artery, enormous numbers of the colorless corpuscles are dissolved—according 
to Al. Schmidt, 71.7 per cent, (horse). First the body of the cell disappears and then the 
nucleus. The products of their dissolution are dissolved in the plasma, and one of these pro- 
ducts is Jibrino-plastin. At the same time the fibrin-ferment is also produced, so that it would 
seem not to exist in the intact blood-corpuscles. Fibrino-plastin and fibrin-ferment are also pro- 
duced by the “transition forms” of blood-corpuscles, i. e., those forms which are intermediate 
between the red and the white corpuscles. They seem to break up immediately after blood is 
shed. The blood plates (p. 19) are also, probably, sources of these substances. 
The leucocytes have different degrees of resistance; those of the lymph and chyle are more 
resistant than those of the blood, and amongst the latter themselves there are various degrees 
{Heyl). 
In amphibians and birds the red nucleated corpuscles rapidly break up after blood is shed, 
and yield the substance or substances which form fibrin. Al. Schmidt convinced himself that 
in these animals fibrinogen is originally a constituent of the blood-corpuscles. 
It is clear, therefore, according to Schmidt’s view, that as soon as the blood-corpuscles, white 
or red, are dissolved, the fibrin-factors pass into solution, and the formation of fibrin by the inter- 
action of the three substances will ensue. 
If a large number of leucocytes be introduced into the circulation of an animal, the leucocytes 
are dissolved in great numbers in the blood, so that death takes place by diffuse coagulation. 
Should the animal survive the immediate danger of death, the blood, owing to the want of leu- 
cocytes, is completely incapable of coagulating (Groth). 
[And. Buchanan thought that the potential element of his “ washed blood-clot ” resided in the 
colorless corpuscles, “ primary cells or vesicles.” He, like Schmidt, found that the buffy coat 
of horse’s blood, which is very rich in white corpuscles, produced coagulation rapidly. Buchanan 
compared the action of his washed clot to that of rennet in coagulating milk.] 
Pathological.—Al. Schmidt and his pupils have shown that some ferment, probably derived 
from the dissolution of colorless corpuscles, is found in circulating blood, and that it is more 
abundant in venous than in arterial blood, while it is most abundant in shed blood. It is 
specially remarkable that in septic fever the amount of ferment in blood may increase to such 
an extent as to permit the occurrence of spontaneous coagulation (thrombosis), which may even 
produce death [Am. Kohler). In febrile cases generally, the amount of ferment is somewhat 
more abundant [Edelberg and Birk). Afier the injection of ichor into the blood an enormous 
number of colorless corpuscles are dissolved [F. Hoffmann). The injection of peptone, Hb, and 
to a less degree of distilled water, is followed by dissolution of numerous leucocytes. 
There are changes in the blood, constituting true blood diseases, in which the physiological 
metabolism of the colorless corpuscles is enormously increased, so that the metabolic products 44 
COMPOSITION OF PLASMA. 
[Sec. 31. 
accumulate in the blood [Alex. Schmidt'). The result of this is spontaneous coagulation within 
the circulatory system, and death even may occur; there is always an increase of temperature. 
After such a condition the coagulability of the blood is diminished. 
31. Formation of Fibrin.—After several observers had shown that the red blood-corpuscles 
(bird, horse, frog) participate in the production of fibrin, Landois observed, in 1874, under the 
microscope that the stromata of the red blood-corpuscles of mammals passed into fibrin. If a 
drop of defibrinated rabbit’s blood be placed in serum of frog’s blood, without mixing them, the 
red corpuscles can be seen collecting together ; their surfaces are sticky, and they can only be 
separated by a moderate pressure on the cover-glass, whereby some of the now spherical cor- 
puscles are drawn out into threads. The corpuscles soon become spherical, and those at the 
margin allow the haemoglobin to escape; the decolorization progresses, from the margin inwards, 
until at last there remain masses of stroma adhering together. The stroma-substance is very 
sticky, but soon the cell-contours disappear, and the stromata adhere and form fine fibres. Thus 
(according to Landois) the formation of fibrin from red blood-corpuscles can be traced step by 
step. The red corpuscles of man and animals, when dissolved in the serum of other animals, 
show much the same phenomena. 
Stroma-Fibrin and Plasma-Fibrin.—Landois calls fibrin formed direct from stroma, 
stroma-fibrin ; fibrin formed in the usual way, plasma-fibrin. The stroma-fibrin is closely related 
chemically to stroma itself; as yet, however, the two kinds of fibrin have not been sharply dis- 
tinguished chemically. Substances which rapidly dissolve red corpuscles cause extensive coagula- 
tion, e.g., injection of bile or bile salts, or lake-colored blood, into arteries. After the injection 
of foreign blood the newly-injected blood often breaks up in the blood-vessels of the recipient, 
while the finer vessels are frequently found plugged with small thrombi (§ 102). 
32. CHEMICAL COMPOSITION OF PLASMA AND SERUM. 
—I. Proteids occur to the amount of 8 to 10 per cent, in the plasma. Only 
0.2 per cent, of these go to form fibrin. After the formation of the fibrin the 
plasma is converted into serum. The sp. gr. of human serum is 1027 to 1029. 
It contains several proteids. [According to Hammarsten, human serum contains 
9.207 per cent, of solids,—of these, 3.103 = serum-globulin, and 4.5i6 = serum- 
albumin, i.e., in the ratio of 1 : 1.511. In horse-serum the proportion is 
4.5 : 2.6, in ox-serum 4.16 : 3.329, and rabbit-serum 1.78 : 4.43. The total 
amount of proteids in blood seems to be much more constant than are the 
relative proportions of serum-albumin and serum-globulin (Salvioli').~\ 
[The following table compiled by Gamgee from Hammarsten’s researches, shows that the 
proportion of serum-globulin to serum-albumin varies remarkably; in some cases serum- 
globulin is the most abundant proteid in the serum of some animals, while in others it is the 
reverse:— 
Variety of Serum. 
Total solids 
in too parts. 
Total pro- 
teids in 100 
parts. 
Serum- 
globulin in 
100 parts. 
Serum- 
albumin in 
100 parts. 
Lecithin, 
fat, salts, 
etc., in 100 
parts. 
Ratio of 
Serum- 
globulin to 
Serum- 
albumin. 
From blood of horse, 
8.597 
7-257 
4-565 
2.677 
I.34O 
I : 0.591 
“ “ OX, . 
8.965 
7-499 
4.I69 
3-329 
I.466 
I : O.S42 
“ “ man,. 
9 207 
7.619 
3-103 
4-5i6 
1-587 
I : 1.511 
“ “ rabbit, 
7-525 
6.225 
1.788 
4-436 
I.299 
I : 2.5 ] 
(a) Serum-globulin or Paraglobulin (2 to 4 per cent.). If crystals of 
magnesium sulphate be added to saturation to serum at 350 C., serum-globulin 
is precipitated, but not serum-albumin. It is soluble in 10 per cent, solution of 
common salt, and coagulates at 69-75° C. Its specific rotatory powers is 
—47°.8 (.Fredericq). 
[Serum-globulin was described by Panum under the name of “serum-casein”; by Al. 
Schmidt, as “ fibrino-plastic substance” ; and by Kuhne, as “paraglobulin.”] 
ib) Serum-albumin (3-4 per cent.). Its solution begins to be turbid at 
6o° C., and coagulation occurs at 73° C., the fluid becoming slightly more 
alkaline at the same time. If sodium chloride be cautiously added to serum, Sec. 32.] 
COMPOSITION OF SERUM. 
45 
the coagulating temperature may be lowered to 50° C. Its specific rotatory 
power is from - 62.6 to - 64.5° {Starke). It is changed into syntonin or acid- 
albumin by the action of dilute HC1, and by dilute alkalies into alkali-albumi- 
nate. 
[Effects of Starvation.—Starvation diminishes the quantity of albumin, and increases the 
quantity of globulin. During the time a Rhine salmon is in fresh water, it eats nothing; the 
muscles lose 30 per cent, of their weight, and the testes and ovaries increase at the expense of 
the muscles {Miescher), and at the same time the globulins of the blood—closely related to the 
globulins of muscle—are increased in amount, the maximum of this increase corresponding to 
the maximum growth of the ovary {Bunge). The globulins are increased at the expense of the 
albumins.] 
Serum-albumin is absent from the blood of starving snakes (the alimentary canal being empty), 
and reappears after they are fed {Tiegel), so that in a digesting snake the blood contains both 
proteids. 
[Serum-Albumin v. Egg-Albumin.—Although serum-albumin is closely related to egg- 
albumin, they differ—{a) as regards their action upon polarized light; {b) the precipitate pro- 
duced by adding HC1 or HN03 is readily soluble in 4 c.c. of the reagent in the case of serum- 
albumin, while the precipitate in egg-albumin is dissolved with very great difficulty; (c) egg- 
albumin, injected into the veins, is excreted in the urine as a foreign body, while serum-albumin 
is not; {d) serum-albumin is not coagulated by ether, while egg-albumin is, if the solution is not 
alkaline (§ 249). Serum-albumin has never been obtained free from salts, even when dialyzed 
for a very long time.] 
After all the serum-globulin in serum is precipitated by magnesium sulphate, serum-albumin 
still remains in solution. If this solution be heated to 40 or 50° C. a copious precipitate of non- 
coagulated serum-albumin is obtained, which is soluble in water. If the serum-albumin be 
filtered from the fluid, and if the clear fluid be heated to over 6o° C., Fredericq found that it 
becomes turbid from the precipitation of other proteids; the amount of these other bodies, 
however, is small. 
[Proteids of the Serum.—Halliburton has shown by the method of 
“ fractional heat-coagulation ” (/.<?., ascertaining the temperature at which 
a proteid is coagulated, filtering the fluid and again heating the filtrate to a 
higher temperature), that from the same fluid perhaps two or more proteids, 
all with different temperatures of coagulation, may be obtained. Care must 
be taken to keep the reaction constant. He finds that serum-globulin coagu- 
lates at 750 C., while serum-albumin in reality consists of three proteids, which 
coagulate at different temperatures: (a) at 730, (/?) at 770, and (y) at 84° C.] 
[Precipitation by Salts.—Sulphate of magnesia not only precipitates serum-globulin, but 
also fibrinogen. The fluid must be shaken for several hours to get complete saturation. Sodic 
sulphate, when added to serum deprived of its globulin by MgS04, precipitates serum-albumin, 
but it produces no precipitate with pure serum. In this way serum-albumin may be obtained 
in a pure, uncoagulated, and still soluble condition. Serum-globulin is thrown down by sodic 
nitrate, acetate, or carbonate; while all the proteids of the serum are precipitated by potassic 
acetate or phosphate, and the same result is brought about by adding two salts, eg., MgSO+ 
and Na2S04 (in this case sodio-magnesia sulphate is formed); MgS04 and NaN03; MgS04 and 
KI; NaCl and Na2S04. After serum-globulin is thrown down by MgS04, the addition of 
MgS04 and Na2S04 or the double salt, precipitates the serum-albumin, which is still soluble in 
water. As sulphate of ammonia precipitates all the proteids except peptones, it may be used 
{Halliburton).) 
[The plasma of Invertebrata (decapod crustaceans, some gasteropods, cephalopods, etc.) 
clots like vertebrate blood, and contains fibrinogen, but, in addition, there is found in it a sub- 
stance corresponding to haemoglobin, and called by Fredericq, haemocyanin. It exists like Hb 
in two conditions, one reduced and the other oxy-haemocyanin, the former being colorless, the 
latter blue. In its general characters it resembles Hb, although it contains copper instead of iron, 
and gives no absorption-bands {Halliburton). In the blood of some decapod crustaceans there 
is a reddish pigment, tetronerythrin, which is identical with that in the exoskeleton and 
hypoderm. It belongs to the group of lipochromes, like some of the pigments of the retina. 
The haemocyanin is respiratory in function, and it is remarkable that it is contained in the plasma, 
and not in the formed elements like the Hb of vertebrates. So that, stated broadly, in these 
invertebrates the plasma is both nutritive and respiratory in its functions, while in vertebrates 
the red corpuscles chiefly are respiratory and the plasma nutritive.] 
II. Fats (0.1 to 0.2 per cent.). — Neutral fats (tristearin, tripalmitin, 46 
BLOOD GASES. 
[Sec. 32. 
triolein) occur in the blood in the form of small microscopic granules, which, 
after a meal rich in fat (or milk), render the serum quite milky. 
[The amount of fat in the serum of fasting animals is about 0.2 per cent.; during digestion 
0.4 to 0.6 per cent.; and in dogs fed on a diet rich in fat it may be 1.25 per cent. There are 
also minute traces of fatty acids (succinic). Rohrig showed that soluble soaps, i. e., alkaline 
salts of the fatty acids, cannot exist in the blood. Cholesterin may be considered along with 
the fats. It occurs in considerable amount in nerve-tissues, and, like fats, is extracted by ether 
from the dry residue of blood serum. Hoppe-Seyler found 0.019 to 0.314 per cent, in the serum 
of the blood of fattened geese. There is no fat in the red blood-corpuscles. Lecithin (its de- 
composition-products, glycerin-phosphoric acid and protagon) occur in serum and also in the 
blood-corpuscles. ] 
III. Traces of Grape-Sugar [o. 1 to o. 15 per cent, (more in the hepatic vein, 
0.23 per cent.)] derived from the liver and muscles, and increased after hemor- 
rhage (§ 175) ; some glycogen, and another reducing fermentative substance. 
The amount of grape-sugar in the blood increases with the absorption of sugar from the 
intestine, and this increase is most obvious in the blood of the portal and hepatic veins; there is 
also a slight increase in the arterial blood, but there it is rapidly changed. The presence of 
sugar is ascertained by coagulating blood by boiling it with sodium sulphate, pressing out the 
fluid, and testing it for sugar with Fehling’s solution (C/. Bernard). Pavy coagulates the blood 
with alcohol. 
IV. Extractives.—Kreatin, urea (0.016 per cent., increased after nitro- 
genous food), succinic acid, and uric acid (more abundant in gouty conditions), 
guanin (?), carbamic acid, sarcolactic acid, all occur in very small amounts. 
V. Salts (0.85 percent.), especially sodic chloride, (0.5 per cent.) and sodic 
carbonate. [It is most important to note that the soda salts are far more abun- 
dant in the serum than the potassium salts. The ratio may be as high as 10: 
1.] Animal diet increases the amount of salts, vegetable food diminishes it 
temporarily. 
Salts in human blood-serum (Hoppe-Seyler). 
Sodic Chloride, . . . 4.92 per 1000 
“ Sulphate, . . . 0.44 “ 
“ Carbonate, ... 0.21 “ 
Sodic Phosphate, . . . .0.15 per 1000 
Calcic Phophate, . . . 
Magnesic “ ... 
0.73 
If large quantities of salts are introduced into the blood, they almost entirely disappear from 
the blood-stream within a few minutes, chiefly by diffusion into the tissues. They are gradually 
eliminated by the kidneys. The same is true of sugar and peptones (Ludwig and Klicowicz). 
VI. Water about 90 per cent. 
VII. A yellow pigment. 
The pigment may be extracted with methylic alcohol. It shows two absorption-bands of a 
lipochrome like lutein (.Krukenberg). Thudichum regards the pigment of the serum as lutein; 
Maly, as hydrobilirubin; and MacMunn as choletelin. 
[Poisonous Blood-serum.—The blood-serum of the following genera of fishes—Anguilla, 
Muraena, and Conger—acts as a powerful poison. Mosso calls the poisonous substances ichthi- 
toxin. A dose of 0.02 c. c. per kilogramme weight of a dog is fatal. The action of this body 
is analogous to that of snake-poison.] 
33. THE GASES OF THE BLOOD.—Absorption by Solid Bodies.—A consider- 
able attraction exists between the particles of solid porous bodies and gases, whereby the latter 
are attracted and condensed within the pores of solid bodies, i. e., the gases are absorbed. Thus, 
x volume of boxwood charcoal (at 12° C. and ordinary barometric pressure) absorbs 35 volumes 
C02, 9.4 vol. O, 7.5 vol. N, 1.75 vol. H. Heat is always formed when gases are absorbed, and 
the amount of heat evolved bears a relation to the energy with which the absorption takes place. 
Non-porous bodies are similarly invested by a layer of condensed gases on their surface. 
By Fluids.—Fluids can also absorb gases. A known quantity of fluid at different pressures 
always absorbs the same volume of gas. Whether the pressure be great or small, the volume of 
the gas absorbed is equally great ( W. Henry). But according to Boyle (1662) and Marriotte’s 
law (1679) on the compression of gases, when the pressure within the same volume of gas is 
increased, the volume varies inversely as the pressure. Hence it follows that, with varying 
pressure, the volume of gas absorbed remains the same, but the quantity of gas (weight) is 
directly proportional to the pressure. If the pressure — o, the weight of the gas absorbed must 
also = 0. As a necessary result of this, we see that (1) fluids can be freed of their absorbed 
gases in a vacuum under an air-pump. Sec. 33.] 
BLOOD GASES. 
47 
Coefficient of Absorption means the volume of a gas (o° C.) which is absorbed by a unit of 
volume of a liquid (at 760 mm. Hg) at a given temperature. The volume of a gas absorbed, 
and therefore the coefficient of absorption, is quite independent of the pressure, while the weight 
of the gas is proportional to it. Temperature has an important influence on the coefficient of 
absorption. With a low temperature it is greatest; it diminishes as the temperature increases; 
and at the boiling point it = o. Hence it follows that—(2) absorbed gases may be expelled 
from fluids simply by causing the fluids to boil. The coefficient of absorption diminishes for 
different fluids and gases, with increasing temperature, in a special, and by no means uniform, 
manner, which must be determined empirically for each liquid and gas. Thus the coefficient 
of absorption for C02 in water diminishes with an increasing temperature, while that for H in 
water remains unchanged between o° and 20° C. 
Diffusion of Gases.—Gases which do not enter into chemical combinations with each other 
mix with each other in definite proportions. If the necks of two flasks be placed in communi- 
cation by means of a glass or other tube, and if the lower flask contain C02, and the upper one 
H, the gases mix quite independently of their different specific gravities, both gases forming in 
each flask a perfectly uniform mixture. The phenomenon is called the diffusion of gases. If 
a porous membrane be previously inserted between the gases, the exchange of gases still goes on 
through the membrane. But (as with endosmosis in fluids) the gases pass with unequal rapidity 
through the pores, so that at the beginning of the experiment a larger amount of gas is found 
on one side of the membrane than on the other. According to Graham, the rapidity of the 
diffusion of the gases through the pores is inversely proportional to the square root of their 
specific gravities. (According to Bunsen, however, this is not quite correct.) 
Different Gases in a Gaseous Mixture do not Exert Pressure upon one another.— 
Gases, therefore, pass into a space filled with another gas, as they would pass into a vacuum. If 
the surface of a fluid containing absorbed gases be placed in contact with a very large quantity 
of another gas, the absorbed gases diffuse into the latter. Hence, absorbed gases can be removed 
by (3) passing a stream of another gas through the fluid, or by merely shaking up the fluid with 
another gas. 
Partial Pressure.—If two or more gases are mixed in a closed space over a fluid, as the 
different gases existing in a gaseous mixture exert no pressure upon each other, the several gases 
are absorbed. The weight of each absorbed is proportional to the pressure under which each 
gas would be, were it the only gas in the space. The pressure is called the partial pressure of 
a gas (.Bunsen). The absorption of gases from their mixtures, therefore, is proportional to the 
partial pressure. The partial pressure of a gas in a space is at the same time the expression for 
the tension of the gas absorbed by a fluid. 
The air contains 0.2096 volume of O and 0.7904 volume N. If 1 volume of the air be placed 
under a pressure, P, over water, the partial pressure under which O is absorbed = 0.2096 P; 
that for N = 0.7904 P. At o° C., and 760 mm. pressure, 1 volume of water absorbs 0.02477 
volume of air, consisting of 0.00862 volume O, and 0.01615 volume N. The absorbed air 
contains, therefore, 34 per cent. O and 66 per cent. N. Therefore, water absorbs from the air a 
mixture of gases containing a larger percentage of O than the air itself. 
34. EXTRACTION OF THE BLOOD GASES.—[The blood to be analyzed must be 
collected over mercury so as to avoid contact with air. This is done by means of a special appa- 
ratus, consisting of a graduated tube filled with mercury and communicating with a glass globe 
also filled with mercury, which can be lowered as the blood flows into the graduated tube.] The 
extraction of the gases from the blood, and their collection for chemical analysis, are carried out 
by means of the mercurial pump (C. Ludzvig). Fig. 29 shows in a diagrammatic form the 
arrangement of Pfhiger’s gas-pump. 
Pfluger’s Gas-pump.—It consists of a receptacle for the blood, or “ blood bulb ” (A), a 
glass globe capable of containing 250 to 300 c. c., connected above and below with tubes, each of 
which is provided with a stop-cock, a and b ; b is an ordinary stop-cock, while a has through its 
long axis a perforation which opens at x, and is so arranged that, according to the position of the 
handle, it leads up into the blood-bulb (position x, a) or downwards through the lower tube 
(position x', a/). This blood-bulb is first completely emptied of air (by means of a mercurial 
air-pump), and then carefully weighed. One end [x/) of it is tied into an artery or vein of an 
animal, and when the lower stop cock is placed in the position x, a, blood flows into the 
receptacle. When the necessary amount of blood is collected, the lower stop-cock is put into 
the position x/, a', and the blood-bulb, after being cleaned most carefully, is weighed to ascertain 
the weight of the amount of blood collected. The second part of the apparatus consists of the 
froth-chamber, B, leading upwards and downwards into tubes, each of which is provided 
with an ordinary stop-cock, c and d. The froth-chamber, as its name denotes, is to catch the froth 
which is formed during the energetic evolution of the gases from the blood. The lower aperture 
of the froth-chamber is connected by means of a well-ground tube with the blood-bulb, while 
above it communicates with the third part of the apparatus, the drying-chamber. G. This 
consists of a U-shaped tube, provided below with a small glass bulb, which is half filled with [Sec. 34. 
48 
GAS PUMPS. 
sulphuric acid, while in its limbs are placed pieces of pumice-stone, also moistened with sulphuric 
acid. As the blood gases pass through this apparatus (which may be shut off by the stop-cocks 
e and f), they are freed from their watery vapor by the sulphuric acid, so that they pass quite 
dry through the stop-cock,/! The short, well-ground tube, D, is fixed to f and to the former 
is attached the small barometric tube or manometer, y, which indicates the extent of the vacuum. 
From D we pass to the pump proper. This consists of two large glass bulbs, which are con- 
Scheme of Pfliiger’s gas pump. A, blood-bulb; a, stop-cock, with a longitudinal perforation, 
opening upwards; a', the same, opening downwards; b and c, stop-cocks; B, froth-chamber; 
d, e,f stop cocks; G, drying-chambers, containing sulphuric acid and pumice-stone; D. 
tube, with manometer, y. 
Fig. 29. 
tinued above and below into open tubes; the lower tubes, Z and W, being united by a caoutchouc 
tube G. Both the bulbs and the caoutchouc tube contain mercury—the bulbs being about half 
full, and F larger than E. The bulb, E, is fixed; but F can be raised or lowered by means of a 
pulley with a rack and pinion motion. If F be raised, E is filled; if F be lowered, E is emptied. 
The upper end of E divides into two tubes, g and h, of which g is united to D. The ascending 
tube, h (gas-delivery tube), is very narrow, and is bent so that its free end dips into a vessel 
containing mercury, v (a pneumatic trough), and the opening is placed exactly under the tube Sec. 34.] 
GAS-PUMP AND BLOOD GASES. 
49 
for collecting the gases, the eudiometer, J, which is also filled with mercury. When g and H 
unite, there is a two way stop-cock, which in one position, H, places E in communication with 
A, B, G, D, the chambers to be exhausted, and in the position K shuts off A, B, G D. and 
places the bulb, E, in communication with the gas-delivery tube, h, and the eudiometer, J. 
B, G, D are completely emptied of air thus: The 
stop cock is placed in the position, K; raise F until 
drops of mercury issue from the fine tube, i (not yet 
placed under J); place the stop-cock in the position 
H, lower F; stop-cock in position, C, and so on until 
the barometer, y, indicates a complete vacuum. J is 
now placed over i. Open the cocks, c and b, so that 
the blood-bulb, A, communicates with the rest of the 
apparatus, and the blood gases froth up in B, and 
after being dried in G pass towards E. Lower F, 
and they pass into E; stop-cock in position, K, raise 
F, and the gases are collected in J under mercury. 
The repeated lowering and raising of F with the 
corresponding position of the stop-cocks ultimately 
drives all the gases into J. The removal of the gases 
is greatly facilitated by placing the blood-bulb, A, in 
a vessel containing water at 6o° C. [Non-defibrinated 
blood may be used with this pump, and the gases are 
kept dry by being connected with the chamber, G, 
containing sulphuric acid.] 
It is well to remove the gases from the blood im- 
mediately after it is collected from a blood-vessel, 
because the O undergoes a diminution if the blood be 
kept. Of course, in making several analyses, it is 
difficult to do this, and the best plan to pursue in 
the case is to keep the receptacles containing the 
blood on ice. 
[Alvergniat’s Pump.—A simpler form of gas- 
pump, first used by Grehant, modified and used by 
Paul Bert, and called after its present maker, is fre- 
quently adopted (figs. 30 and 31). It is the one most 
frequently employed in the French laboratories. The 
receptacle (R) receives the blood from the tube (r). 
The bulb (A and B), connected by a caoutchouc tube 
and containing mercury, represent the pump. The 
bulb (B) can be raised or lowered by means of the 
handle (M), a flat band being attached to B and 
working over a pulley (P). By alternately raising and 
depressing (B) a vacuum is created in the reservoir 
(R) and the tubes connected with it. The gases pass 
over into the eudiometer which has its lower end 
in the cup (c) containing mercury.] 
[The mercury pump (A, B) is composed of a thick, 
vertically placed barometer tube (<r) communicating 
below by thick caoutchouc tubing with the bulb (B) 
containing Hg. The bulb (A) communicates superiorly 
by means of the three way stop-cock (T) with the cup 
of mercury (c), and thus with the eudiometer [A), 
while horizontally it communicates with the tubes 
connected with the reservoir (R). The stop-cock 
(T) can be so placed as to cut off all communication 
between the bulb (A) and the exterior, or the bulb 
can be placed in communication with h, or with R.] 
[This is done as follows: Place the tap (T) in the 
position (2), raise B until it is filled with Hg, and all the air is driven out at b. Turn the tap 
into the position (1) so that all connection between A and g is cut off; lower B, and a vacuum is 
established in A and a. Place the tap in the position (3), and connect A with g, and therefore 
with R, the tap in t being closed, when at once a partial vacuum is established in the system R, g, 
A, a. Turn the tap T into the position (2), raise B and expel the air through I b. Turn the tap 
T into the position (1), lower B, turn the tap into the position (2), and part of the remainder of 
the air in g and R passes into A and a, so that the vacuum in R and g is still further increased. 
Fig. 30. 
Grehant’s and Bert’s gas-pump, as made 
by Alvergniat of Paris. ESTIMATION OF THE BLOOD GASES. 
[Sec. 34. 
Repeat the process as above until a complete vacuum exists in R and g. Collect too c. c. of 
blood under mercury, and introduce 50 c. c. of it through the tube t into the large receiver R, 
when it gives up its gases to the vacuum. The blood immediately froths up and loses its bright 
red color, becoming of a dark claret tint. Fill the tube or eudiometer (h) with mercury and 
insert it over b. By turning the tap T into the position (3), on lowering B the blood gases pass 
into A <7, on turning the tap into the position (2) and raising B the gases are forced into and 
collected in h. The escape of 
the gases from the blood is 
greatly facilitated by placing 
the bulb R in warm water as 
shown in the figure; and, 
moreover, the escape of watery 
vapor helps to carry over the 
gases more rapidly into A a. 
In some forms of the instru- 
ment a drying-vessel contain- 
ing pumice stone and sulphuric 
acid is introduced between R 
and T. The joints of the appa- 
ratus are surrounded with caps 
of caoutchouc, which are filled 
with mercuiy when the appa- 
ratus is in use; thus any leak- 
age at a joint is detected at 
once.] 
Mayow (1670) observed that 
gases were given off from blood 
in vacuo. Magnus (1837) in- 
vestigated the percentage com- 
position of the blood gases. 
The more important recent in- 
vestigations have been made by 
Lothar Meyer (1857), and by 
the pupils of C. Ludwig and 
E. Pfluger. 
35. QUANTITA- 
TIVE ESTIMA- 
TION OF THE 
BLOOD GASES.— 
The gases obtained from 
blood consist of O, C02, 
and N. Pfluger obtained 
(at o° C. and 760 mm. 
Hg pressure) in round 
numbers about 60 vols. 
per cent, from the arterial 
blood of a dog (large artery) and from venous blood (right side of heart). As 
is shown in figs. 29 (J) and 30, the gases are collected in an eudiometer, i.e., 
in a narrow tube, closed at one end, and with a very exact scale marked on it, 
and having two fine platinum wires melted into its upper end, with their free 
ends projecting into the tube (p and ri). 
(1) Estimation of the C02.—A small ball of fused caustic potash, fixed on a platinum wire, 
is introduced into the mixture of gases through the lower end of the eudiometer under cover of 
the mercury. The surface of the potash ball is moistened before it is introduced. The C02 
unites with the potash to form potassium carbonate. The potash bulb is withdrawn after 24 
hours. The diminution in volume indicates the amount of C02 absorbed. 
(2) Estimation of the O.—(a) Just as in estimating the C02, a ball of phosphorus on a 
platinum wire is introduced into the eudiometer; it absorbs the O and forms phosphoric acid. 
Another plan is to employ a small papier-mache ball saturated with pyrogallic acid in caustic 
potash, which rapidly absorbs O. After the ball is removed, the diminution in volume indicates 
the quantity of O. 
Fig. 31. 
Scheme of Alvergniat’s gas-pump. R, receptacle for blood; 
t, thick tube with tap communicating with it; A and B, 
bulbs for mercury; a, barometer tubing; M, windlass; P, 
pulley ; T, tap; g, connecting tube to R ; c, cup for mer- 
cury; h, eudiometer; II, i, 2, 3, positions that can be given 
to the three-way stop-cock or tap T. I, Small part of c 
and T enlarged to show the eudiometer. Sec. 35.] 
THE BLOOD GASES. 
51 
(b) The O is most easily and accurately estimated by exploding it in the eudiometer. Intro- 
duce a sufficient quantity of H into the eudiometer, and accurately ascertain its volume ; an 
electrical spark is now passed between the wires, / and «, through the mixture of gases; the O 
and H unite to form water, which causes a diminution in the volume of the gases in the eudio- 
meter, of which is due to the O used to form water (H20). 
(r) Estimation of the N.—When the C02 and O are estimated by the above method, the 
remainder is pure N. 
36. THE BLOOD GASES.—[In human blood the average total 
gases are estimated to be in round numbers 60 vols. per cent, at o° C. and 
760 mm. pressure, made up as follows; — 
O 
co2 
N 
Arterial blood, 
20 
39 
1.4 per cent. 
Venous blood, 
8 to I 2 
46 
1.4 “ ] 
or, 47.3 vols. per cent, calculated at o° C. and 1 metre pressure, 
Arterial blood, 
17 
3° 
1 to 2 per cent. 
Venous blood, 
6 to 10 
35 
1 to 2 “ 
[Thus venous blood contains 8-12 per cent, less O and 6 per cent, more C02 
than arterial blood. The amount of gases obtained from venous blood under 
different conditions varies greatly, as is stated below.] 
1. Oxygen exists in arterial blood (dog) on an average to the extent of 17 
volumes per cent, (at o° C. and 1 metre Hg. pressure) Pfliiger), or 20 volumes 
per cent, (at o° C. and 760 mm. pressure). According to PfKiger, arterial blood 
(dog) is saturated to with O, while, according to Hiifner, it is saturated to the 
extent of -[i. In venous blood the quantity varies very greatly; in the blood 
of a passive muscle 6 volumes per cent, have been found; while in the blood 
after asphyxia it is absent, or occurs only in traces. It is certainly more abund- 
ant in the comparatively red blood of active glands (salivary glands, kidney) 
than in ordinary dark venous blood. 
[Modifying Conditions.—The amount of O obtainable from the blood depends upon the 
organ from which the.blood comes, or whether the organ be active or at rest. Thus the O present 
in the 
Carotid artery is, 21 per cent. 
Renal artery, 19 “ 
Renal vein (kidney active), 17 per cent. 
Renal vein (kidney at rest), 6 “ 
Bert finds that increase of the atmospheric pressure from 1 to 10 atmospheres raises the 
amount of O in arterial blood from 20 to over 24 per cent, and the N from 1.8 to over 9 per 
cent., while the C02 is but slightly affected. Only 10-15 volumes per cent, of O are obtained 
from the blood of herbivora (sheep, rabbit), as these animals have a small number of corpuscles, 
and haemoglobin. The amount of haemoglobin and O is much less in cold-blooded animals. 
The amount of C02 in peptone blood is diminished by about one-half, while the O is slightly 
increased (Lahousse).] 
The O in Blood occurs—(a) simply absorbed in the plasma. This is only a 
minimal amount, and does not exceed what distilled water at the temperature 
of the body would take up at the partial pressure of the O in the air of the 
lungs (Lothar Meyer). 
(b) Almost the total O of the blood is chemically united, and therefore not 
subject to the law of absorption. It is loosely united to the haemoglobin of the 
red corpuscles, with which it forms oxyhsemoglobin (§ 15). With regard to 
the taking up of O, the total quantity of blood behaves exactly like a solution 
of haemoglobin free from O (Preyer). The absorption of O is more rapid in 
blood than in a solution of Hb. 
The absorption of this quantity of O is completely independent of pressure ; hence, animals 
confined in a close space, until they are nearly asphyxiated, can use up almost all the O from 
the surrounding atmosphere. The fact of the union being independent of pressure is proved by 
the following: The blood only gives off copiously its chemically united O when the atmo- 
spheric pressure is lowered to 20 millimetres Hg ( Worm Muller); and, conversely, blood only 
takes up a little more O when the pressure is increased to 6 atmospheres (Bert). 52 
OZONE IN BLOOD. 
[Sec. 36. 
Physical Methods of obtaining O from Blood.—Notwithstanding the 
chemical union between the Hb and O, all the O of the blood can be expelled 
from its state of combination by those means which set free absorbed gases— 
(a) by introducing blood into a Torricellian vacuum. 
(b) by boiling. 
(c) by the conduction of other gases [H, N, CO, or NO] through the blood, 
because the oxyhsemoglobin compound is so loose that it is decomposed 
even by these physical means. 
Reducing Reagents.—Amongst chemical reagents the following reducing 
substances—ammonium sulphide, sulphuretted hydrogen, alkaline solutions of 
sub-salts or Stokes’s fluid, iron filings, etc., rob blood of its O (§ 15). 
Relation to Fe.—The amount of iron in the blood (0.55 in 1000 parts) stands in direct rela- 
tion to the amount of Hb; this to the quantity of blood-corpuscles; and this, in turn, to the 
specific gravity of the blood. The amount of O in the blood, therefore, is nearly proportional to 
the specific gravity of the blood, and it is also in proportion to the amount of iron in the blood. 
The total amount of iron in the blood is about 3 grams. 
During morphia narcosis the amount of O in the blood is diminished (Ewald)\ after hemor- 
rhage the arterial blood is saturated with O (J. G. Otl). 
Disappearance of O in Shed Blood.—Even immediately after blood is shed there is a slight 
disappearance of O, as a physiological index of respiration of the tissues within the living blood 
itself (§ 131). When blood is kept long outside of the blood-vessels, the quantity of O gradually 
diminishes, and if it be kept for a length of time at a high temperature it may disappear alto- 
gether. This depends upon decomposition occurring in the blood, whereby reducing substances 
are formed which consume the O. All kinds of blood, however, do not act with equal energy 
in consuming O, e. g., venous blood from active muscles acts most energetically, while that from 
the hepatic vein has very little etfect. C02 appears in the blood in place of the O, and the color 
darkens. The amount of 0O2 produced is sometimes greater than that of the O consumed. 
Relation to Acids.—If blood (or a soluth n of oxyhmmoglobin) be acted upon by acids f. g., 
tartaric acid) until it is strongly acid, O can be pumped out in considerably less amount, while 
the formation of C02 is not increased. We must therefore assume that, during the decomposi- 
tion of the Hb caused by the acids (§ 18), a decomposition product becomes more highly oxidized, 
by the intense chemical union of the O at the moment of its origin (Lothar Meyer, Zuntzy 
Strassburg). The same phenomenon occurs when oxyhsemoglobin is decomposed by boiling. 
37. IS OZONE PRESENT IN BLOOD? —On account of the num- 
erous and energetic oxidations which occur in connection with the blood, the 
question has often been raised as to whether the O of the blood exists in the 
form of ozone (03). Ozone, however, is contained neither in the blood itself 
(Schonbein) nor in the blood gases obtained from it. Nevertheless, the red 
corpuscles (and Hb) have a distinct relation to ozone. 
(1) Tests for Ozone.—Haemoglobin acts as a conveyer of ozone, i. e., it is able to remove the 
active O of other bodies and to convey or transfer it at once to other easily oxidizable substances. 
(a) Turpentine which has been exposed to the air for a long time always contains ozone. The 
tests for the latter are starch and potassium iodide, the ozone decomposing the iodide, when the 
iodine strikes a blue with the starch. (£) Freshly-prepared tincture of guaiacum is also rendered 
blue by ozone. If some tincture of guaiacum be added to turpentine there is no reaction, but on 
adding a drop of blood a deep blue color is immediately produced, i. e., blood takes the ozone 
from the turpentine and conveys it at once to the dissolved guaiacum, which becomes blue. It is 
immaterial whether the Hb contains O or not. 
(2) It is also asserted that haemoglobin acts as an ozone prodticer, i. e., that it can convert the 
ordinary O of the air into ozone. Hence the reason why red blood-corpuscles alone render 
guaiacum blue. This reaction succeeds best when the guaiacum solution is allowed to dry on 
blotting-paper, and a few drops of blood (diluted 5 to 10 times) are poured on it. That the Hb 
forms ozone from the surrounding O is shown by the fact that red blood-corpuscles containing 
carbonic oxide cause the blue color (Kuhne and Sckolz). According to Pfliiger, however, these 
reactions only occur from decomposition of the Hb, so that on this view the blood corpuscles 
cannot be regarded as producers of ozone. 
Sulphuretted hydrogen is decomposed by blood (as by ozone itself) into sulphur and water. 
Hydric peroxide is decomposed by blood into O and water [but this reaction is prevented by the 
addition of a small amount of hydrocyanic acid (Schonbein')]. Crystallized Hb does not do this, 
and H202 may be cautiously injected into the blood-vessels of animals. This would show that 
unchanged Hb does not produce ozone. Sec. 37.] 
CARBON DIOXIDE IN BLOOD. 
53 
Various Forms of Oxygen.—There are three forms of oxygen : (i) The ordinary oxygen (02) 
in the air. (2) Active or nascent oxygen (O), which never can occur in the free state, but the 
moment it is formed acts as a powerful oxidizing agent and produces chemical compounds. It 
converts water into hydric peroxide—the N of the air into nitrous and nitric acids, and even 
CO into C02, which ozone does not. It certainly plays an important part in the organism. 
(3) Ozone (03), which is formed by the decomposition of several molecules of ordinary oxygen 
(02) into two atoms of O, and the appropriation of each of these atoms by a molecule of unde- 
composed oxygen. It is oxygen condensed to % of its volume. 
38. C02 AND N IN BLOOD.—II. Carbon Dioxide.—In arterial 
blood there are about 39 volumes per cent, at o° C. and 760 mm. Hg pressure 
or 30 volumes per cent, of C02 at o° C. and 1 metre pressure (Setschenow) ; 
but in venous blood the amount is very variable, e.g., in the venous blood of 
passive muscles there are 35 volumes per cent. (' Sczelkow), while in the blood of 
asphyxia there may be 52.6 volumes per cent. The C02 in the lymph of 
asphyxia is less than that in the blood {Buchner, Gaule). The C02 of the 
blood may be extracted from it or completely pumped out, without, however, the 
alkaline reaction of the blood undergoing any change (Zuutz). 
(A) The C02 in Plasma (or Serum). 
(a) A minimal part is simply absorbed by the fluid part of the blood. 
(b) The largest portion of the CO-2 belongs to the plasma (or serum), and it all 
appears to be in a state of chemical combination. Serum takes up C02 quite 
independently of pressure, hence it cannot be merely absorbed. The C02 may 
exist in the following combinations :— 
(1) A portion of the C02 is loosely united to sodic carbonate in the form of 
sodic bicarbonate; the carbonate takes up 1 equivalent of C02; Na2C03 + 
C02 -f- H20 = 2NaHC03. This C02 may be pumped out, as in the process 
the bicarbonate splits up again into the neutral carbonate and C02. 
(2) As the bicarbonate only gives up its C02 very slowly in vacuo, while blood 
gives off its C02 very energetically, perhaps the soda, united with an albumi- 
nous body (serum-globulin-alkali [Torup\) combines with the C02 and forms a 
complex compound, from which the C02 is rapidly given off in vacuo. 
(3) A minimal portion of the C02 may be chemically united with neutral 
sodic phosphate in the plasma {Fernet). One equivalent of this salt can fix one 
equivalent of C02, so acid sodium phosphate and acid sodium carbonate are 
formed, Na2HP04 -f- CO -|- 2H20 = NaH2P04 -f- NaH,C03 {Hermann). 
When the gases are removed the C02 escapes, and neutral sodic phosphate 
remains. 
It is probable, however, that almost all the sodic phosphate found in the blood-ash arises from 
the burning of lecithin ; we have, therefore, to consider only the very small amount of this salt 
which occurs in the plasma {Hoppe-Seyler and Sertoli). 
(B) The C02 in the Blood-Corpuscles. 
The red corpuscles contain C02 in loose chemical combination; for (1) a 
volume of blood can fix nearly as much C02 as an equal volume of serum 
{Ludwig, Al. Schmidt) ; and (2) with increasing pressure the absorption of C02 
by blood takes place in a different ratio from what occurs with serum {Pfliiger, 
Zuntz). The red corpuscles can fix more C02 than their own volume, and the 
union of the C02 seems to depend upon the Hb, for Setschenow found that, 
when Hb was acted on by C02, its power of fixing the latter was increased, 
which is perhaps due to the formation of some substance more suited for fixing 
C02. Bohr found that 1 gram of dissolved Hb (dog) at 120 mm. Hg pressure 
unites with 3.5 c.c. C02, i. e., more than double the quantity of O absorbed 
(p. 26). It seems also to be partly united to the globulin-alkali compound 
{Bohr, Torup). The leucocytes, after the manner of the serum-constituents, 
also fix C02 to the extent of to of the absorbing power of serum. 54 
ARTERIAL AND VENOUS BLOOD. 
[Sec. 38. 
After the use of I, Hg, sodic oxalate, and nitrite, there is a diminution of C0.2 in arterial 
blood (Feitelberg), and also in fever (Geppert, Minkowski). [In the last case it is perhaps due 
to the diminished alkalinity, and this is in part owing to the acid products formed during the 
decomposition of the tissues.] 
III. Nitrogen exists in the blood to the extent of 1.4 to 1.6 vol. per cent., 
and it appears to be simply absorbed. 
It is doubtful if any part of the N exists chemically united in the red corpuscles. Blood 
warmed outside the body, and with a free supply of oxygen, gives off a minute quantity of 
ammonia, which is perhaps derived from the decomposition of some salt of ammonia as yet un- 
known (Kiihne and Strauch). 
39. ARTERIAL AND VENOUS BLOOD.—Arterial blood con- 
tains in solution all those substances which are necessary for the nutrition of the 
tissues, those which are employed in secretion, and it also contains a rich sup- 
ply of O, and, as we have seen, a considerable amount of C02. Venous blood 
contains less of the nutrient matter, but in addition it holds the used-up or 
effete substances derived from the tissues, and the products of their retrogressive 
metabolism are more numerous; there is in venous blood a larger amount of 
C02, and also a considerable amount of O. 
[The fundamental difference between Arterial and Venous blood 
is due to the relative proportion of oxygen and carbon dioxide contained in 
each. The difference in color depends on this. If venous blood be shaken up 
with air or oxygen it becomes arterial, while if arterial blood be submitted to a 
current of an indifferent gas such as N or H, it becomes venous. It also does so 
if it be sealed up in a vessel for some time, whereby the oxygen is used up, and 
gradually more and more of the oxyhsemoglobin is changed into reduced 
haemoglobin.] 
It is evident also that the blood of certain veins, the portal and hepatic, must 
have special characters. 
The following are the most important points of difference between arterial 
blood and venous blood :— 
more O, 
less CO, 
more water, 
more fibrin, 
more extractives, 
Arterial Blood contains— 
more salts, 
more fat, 
more sugar, 
fewer blood corpuscles, 
less urea. 
It is redder and not 
dichroic. 
As a rule it is i° C. warmer. 
It coagulates more rapidly. 
The bright red color of arterial blood depends on the presence of oxyhae- 
moglobin, whilst the dark color of venous blood is due to its smaller proportion 
of oxyhsemoglobin, and the quantity of reduced haemoglobin which it contains. 
The dark change of color is not to be attributed to the larger quantity of C02 
in venous blood (.Marchand) ; for if equal quantities of O be added to two 
portions of blood, and if C02 be added to one of them, the color is not 
changed (Pfluger). 
[According to C. Schmidt, the blood of the portal vein contains more water, plasma, salts, 
and fats, but less extractives and corpuscles than the blood of the hepatic vein; while (when 
an animal is not digesting) sugar is absent, or at least only in traces in the portal vein, and in 
considerable amount in the hepatic vein ($ 175). 
[Blood of the hepatic vein is said to contain more corpuscles than that of 
the portal vein, and it is supposed not to coagulate after death, but this is very 
doubtful. According to Drosdoff, it contains more water, cholesterin, and 
lecithin than the portal vein except during digestion ; it also contains more 
sugar, and it is the warmest blood in the body.] 
[Splenic Vein.—Some observers say that this vein contains more, and 
others fewer, red-blood corpuscles than that of the artery. The statement is 
also made that it contains more white corpuscles, but this, again, is denied by Sec. 39.] 
QUANTITY OF BLOOD. 
55 
Tarchanoff. The notion that its serum contains haemoglobin has been dis- 
proved by Schafer. In this latter respect it does not differ from that of serum 
of blood generally.] 
Renal Vein.—Here the blood is bright red, and holds more O and less C0.2 
than the blood of the renal artery. It contains less water, NaCl, uric acid and 
urea, and coagulates with difficulty.] 
40. QUANTITY OF BLOOD.—In the adult the quantity of blood is 
equal to part of the body-weight (.Bischoff), [/. e., on an average 4-4.5 kilos 
(8.8-9.9 lbs.)] ; in newly-born children tl ( Welcker). 
According to Schiicking, the amount of blood in a newly-born child depends to some extent 
upon the time at which the umbilical cord is ligatured. The amount = TV of the body-weight 
when the cord is tied at once, while if it is tied somewhat later it may be J. Immediate 
ligature of the cord may, therefore, deprive a newly-born child of 100 grams of blood. 
Further, the number of corpuscles is less in a child after immediate ligature of the umbilical 
cord than when it is tied somewhat later (Helot). 
The methods of Valentin (1838), and Ed. Weber (1850), are not now used, as the results 
obtained are not sufficiently accurate. 
Method of Welcker (1854).—Begin by taking the weight of the animal to be experimented 
on; place a cannula in the carotid, and allow the blood to run into a flask previously weighed, 
and in which small pebbles (or Hg) have been placed, in order to defibrinate the blood by 
shaking. Take a part of this defibrinated blood, and make it cherry-red in color by passing 
through it a stream of CO (because ordinary blood varies in color according to the amount of 
O contained in it—Gscheidlen, Heidenkain). Tie a 1— shaped cannula in the two cut ends of 
the carotid, and allow a 0.6 per cent, solution of common salt to flow into the vessel from a 
pressure bottle; collect the colored fluid issuing from the jugular veins and inferior vena cava 
until the fluid is quite clear. The entire body is then chopped up (with the exception of the 
contents of the stomach and intestines, which are weighed, and their weight deducted from the 
body-weight), and extracted with water, and after twenty-four hours the fluid is expressed. 
This water, as well as the washings with salt solution, are collected and weighed, and part of 
the mixture is saturated with CO. A sample of this dilute blood is placed in a vessel with 
parallel sides (1 cm. apart) opposite the light (the so-called hfematinometer), and in a second 
vessel of the same dimensions a sample of the undiluted CO blood is diluted with water from a 
burette, until both fluids give the same intensity of color. From the quantity of water required 
to dilute the blood to the tint of the washings of the blood-vessels, the quantity of blood in the 
washings is calculated. On chopping up the muscles alone, we obtain the amount of Fib present 
in them, which is not taken into calculation. 
Quantity of Blood in Various Animals.—The quantity of blood in the 
mouse = -jV to ; guinea-pig = ,T to 2V) ’> rabbit = 2V (tV t0 2V) » dog 
= tV (tt to vs■).»cat =. ix-5;blrds=tV to tV ; fr°g=it to -h yfishes—tt to tV 
of the body-weight (without the contents of the stomach and intestines). 
The specific gravity of the blood ought always to be taken when estimating the amount of 
blood. The amount of blood is diminished during inanition; fat persons have relatively less 
blood; after hemorrhage the loss is at first replaced by a watery fluid, while the blood-corpuscles 
are gradually regenerated. 
The estimation of the quantity of blood in different organs is done by 
suddenly ligaturing their blood-vessels infra vitam. A watery extract of the 
chopped-up organ is prepared, and the quantity of blood estimated as described 
above. [Roughly it may be said that the lungs, heart, large arteries, and veins 
contain the muscles of the skeleton, y-, the liver, and other organs, 
y (Ranke).] 
[Fate of Salts injected into the blood-stream.—One of the most noteworthy facts about 
the composition of the blood is the remarkable constancy in the proportion of its chemical con- 
stituents, and this is specially true of its salts. It is impossible to render blood acid by giving 
animals repeated doses of acid, and when salts are administered in excess, the blood rapidly gets 
rid of them. If salts (Na2S04,Na2HP04,NaCl) be injected into the blood-vessels, the salts 
immediately diffuse into the tissues, so that within a few minutes only traces can be recovered 
from the blood. At the same time the tissues give up water to the blood, and gradually the 
salts re-enter the blood and are given off by the kidneys ] 56 
ABNORMAL CONDITIONS OF THE BLOOD. 
[Sec. 41. 
41. ABNORMAL CONDITIONS OF THE BLOOD—(A) i. Polyaemia.—(i) An in- 
crease in the entire mass of the Wood,uniformly in all organs, constitues polycemia or plethora, 
and in over-nourished individuals it may approach a pathological condition. A bluish-red color 
of the skin, swollen veins, large arteries, hard full pulse, injection of the capillaries and smaller 
vessels of the visible mucous membranes are signs of this state, and, when accompanied by con- 
gestion of the brain, there is vertigo, congestion of the lungs, and breathlessness. After major 
amputations with little loss of blood, a relative but transient increase of blood has been found (?) 
(plethora apocoptica). 
Transfusion.—Polyaemia may be produced artificially by the injection of blood of the same 
species. If the normal quantity of blood be increased 83 percent, no abnormal condition occurs, 
because the blood-pressure is not permanently raised. The excess of blood is accommodated in 
the greatly distended capillaries, which may be stretched beyond their normal elasticity. If it be 
increased to 150 per cent, there are variations in the blood-pressure, life is endangered, and there 
may be sudden rupture of blood-vessels ( Worm Muller). 
Fate of Transfused Blood.—After the transfusion of blood the formation of lymph is 
greatly increased ; but in one or two days the serum is used up, the water is excreted chiefly by 
the urine, and the albumin is partly changed into urea. Hence, the blood at this time appears 
to be relatively richer in blood-corpuscles [Panum, Lesser, Worm Muller). The red corpuscles 
break up much more slowly, and the products thereof are partly excreted as urea and partly (but 
not constantly) as bile pigments. Even after a month an increase of colored blood-corpuscles 
has been observed (Tschirjew). That the blood-corpuscles are broken up slowly in the economy 
is proved by the fact, that the amount of urea is much larger when the same quantity of blood is 
swallowed by the animal than when an equal amount is transfused (Tschirjew, Landois). In 
the latter case there is a moderate increase of the urea, lasting for days, a proof of the slow 
decomposition of the red corpuscles. Pronounced over-filling of the vessels causes loss of appetite 
and a tendency to hemorrhage of the mucous membranes. 
(2) Polyaemia serosa is that condition in which the amount of serum, i. e., the amount of 
water in the blood, is increased. This may be produced artificially by the transfusion of blood- 
serum from the same species. The water is soon given off in the urine, and the albumin is 
decomposed into urea, without, however, passing into the urine. An animal forms more urea 
in a short time from a quantity of transfused serum than from the same quantity of blood, a proof 
that the blood corpuscles remain longer undecomposed than the serum (Forster, Landois). If 
serum from another species of animal be used (e. g., dog’s serum transfused into a rabbit), the 
blood-corpuscles of the recipient are dissolved; haemoglobinuria is produced [Ponfick); and if 
there be general dissolution of the corpuscles, death may occur [Landois). 
(3) Polyaemia aquosa is a simple increase of the water of the blood, and occurs temporarily 
after copious drinking, but increased diuresis soon restores the normal condition. Diseases of 
the kidneys which destroy their secreting parenchyma, produce this condition, and often also 
general dropsy, owing to the passage of water into the tissues. Ligature of the ureter produces 
a watery condition of the blood. 
(4) Plethora polycythaemica Hyperglobulie.—An increase of the red corpuscles has been 
assumed to occur when periodically recurring hemorrhages are interrupted, e. g., menstruation, 
bleeding from the nose, etc.; but the increase of corpuscles has not been definitely proved. There 
is a proved case of temporary polycythaemia, viz., when similar blood is transfused, a part of the 
fluid being used up, while the corpuscles remain unchanged for a considerable time. There is a 
remarkable increase in the number of blood-corpuscles (to 8.82 millions per cubic millimetre) in 
certain severe cardiac affections where there is great congestion, and much water transudes 
through the vessels. In cases of hemiplegia, for the same reason, the number of corpuscles is 
greater on the paralyzed congested side (Pensoldt). After diarrhoea, which diminishes the water 
of the blood, there is also an increase (Brouardel), and the same is the case after profuse sweating 
and polyuria. Drugs (alcohol, chloral, amyl nitrite) which act on the blood-vessels affect the 
number of corpuscles; during contraction of the blood-vessels their number increases, during 
dilatation they diminish in number (Andreesen). There is a temporary increase in the haemato- 
blasts as a reparative process after severe hemorrhage ($ 7), or after acute diseases. In cachectic 
conditions this increase continues, owing to the diminished non-conversion of these corpuscles 
into red corpuscles. In the last stages of cachexia the number diminishes more and more until 
the formation of haematoblasts ceases (Hayeni). 
(5) Plethora hyperalbuminosa is a term applied to the increase of albumins in the plasma, 
such as occurs after taking a large amount of food. A similar condition is produced by trans- 
fusing the serum of the same species, whereby, at the same time, the urea is increased. Injection 
of egg-albumin produces albuminuria (Stokvis, Lehmann). 
[The subcutaneous injection of human blood has been practiced with good results in 
anaemia (v. Ziemssen). When defibrinated human blood is injected subcutaneously, while its 
passage into the circulation is aided by massage, it causes neither pain nor inflammation, but the 
blood of animals, and a solution of haemoglobin, always induce abscess [Benczur). Blood is 
also rapidly absorbed when injected in small amount into the respiratory passages.] . Sec. 41.] 
ABNORMAL CONDITIONS OF THE BLOOD. 
57 
Mellitsemia.—The sugar in the blood is partly given off by the urine, and in “diabetes 
mellitus ” i kilo. (2.2 lbs.) may be given off daily, when the quantity of urine may rise to 25 
kilos. To replace this loss of grape sugar a large amount of food and drink is required, whereby 
the urea may be increased threefold. The increased production of sugar causes an increased 
decomposition of albuminous tissues; hence the urea is always increased, even though the supply 
of albumin be insufficient. The patient loses flesh; all the glands, and even the testicles, atrophy 
or degenerate (pulmonary phthisis is common); the skin and bones become thinner; the nervous 
system holds out longest. The teeth become carious on account of the acid saliva, the crystalline 
lens becomes turbid from the amount of sugar in the fluid of the eye which extracts water from 
the lens, and wounds heal badly because of the abnormal condition of the blood. Absence of all 
carbohydrates in the food causes a diminution of the sugar in the blood, but does not cause it 
to disappear entirely. [The sugar in the blood is also increased after the inhalation of chloro- 
form or amyl nitrite, and after the use of curara, nitro-benzole, and chloral ($ 175).] An 
excessive amount of inosite has been found in the blood and urine (£ 267), constituting mel- 
lituria inosita (Vohl). 
Lipsemia, or an increase of the Fat in the Blood, occurs after every meal rich in fat 
(.e. g., in sucking kittens), so that the serum may become turbid like milk. Pathologically, this 
occurs in a high degree in drunkards and in corpulent individuals. When there is great decom- 
position of albumin in the body (and therefore in very severe diseases), the fat in the blood 
increases, and this also takes place after a liberal supply of easily decomposable carbohydrates 
and much fat. 
After injuries to bones affecting the marrow, not unfrequently fatty granules pass from the 
marrow through the imperfect walls of the blood-vessels into the blood-.stream. These fatty 
particles may form fat emboli, e. g., in the liver or lungs, or they may appear in the urine. 
If granules of cinnabar or indigo are injected into the blood, they are taken up by the 
leucocytes, and by them are carried outside the blood-stream. The cells of the splenic pulp, 
marrow of bone, and the liver also take up these particles [Siebel). 
The salts remain very persistently in the blood. The withdrawal of common salt produces 
albuminuria, and, if all salts be withheld, paralytic phenomena occur [Forster). Over-feeding 
with salted food, such as salt meat, has caused death through fatty degeneration of the tissues, 
especially of the glands. Withdrawal of lime and phosphoric acid produces atrophy and soften- 
ing of the bones. In infectious diseases and dropsies the salts of the blood are often increased, 
and diminished in inflammation and cholera. [NaCl is absent from the urine in certain stages 
of pneumonia, and it is a good sign when the chlorides begin to return to the urine.] [In 
scurvy the corpuscular elements are diminished in amount, but we have not precise information 
as to the salts, although this disease is prevented, in persons forced to live upon preserved and 
salted food, by a liberal use of the salts—especially potash salts—of the organic acids, as con- 
tained in lime juice. In gout, the blood during an acute attack, and also in chronic gout, 
contains an excess of uric acid (Garrod).\ 
The amount of fibrin is increased in inflammations of the lung and pleura, [croupous 
pneumonia, erysipelas], hence such blood forms a crusta phlogistica (§ 27). Jn other diseases, 
where decomposition of the blood-corpuscles occurs, the fibrin is increased, perhaps because the 
dissolved red corpuscles yield material for the formation of fibrin. After repeated hemorrhages, 
Sigm. Mayer found an increase of fibrin. Blood rich in fibrin is said to coagulate more slowly 
than when less fibrin is present—still there are many exceptions. 
(B) (I) Diminution of the Quantity of Blood, or its Individual Constituents.— 
(1) Oligsemia vera, Anaemia, or diminution of the quantity of blood as a whole, occurs 
whenever there is hemorrhage. Life is endangered in newly born children when they lose a 
few ounces of blood; in children a year old, on losing half a pound; and in adults, when one- 
half of the total blood is lost. Women bear loss of blood much better than men. The periodical 
formation of blood after each menstruation seems to enable blood to be renewed more rapidly in 
their case. Stout persons, old people, and children do not bear the loss of blood well. The 
more rapidly blood is lost, the more dangerous it is. [A moderate loss of blood is soon made 
up, but the fluid part is more quickly restored than are the corpuscles.] 
Symptoms of Loss of Blood.—Great loss of blood is accompanied by general paleness and 
coldness of the cutaneous surface, increased oppression, twitching of the eyeballs, noises in the 
ears and vertigo, loss of voice, great breathlessness, stoppage of secretions, coma; dilatation of 
the pupils, involuntary evacuations of urine and faeces, and lastly, general convulsions, are sure 
signs of death by hemorrhage. In the gravest cases recovery is only possible by means of 
transfusion. Animals can bear the loss of one-fourth of their entire blood without the blood- 
pressure in the arteries permanently falling, because the blood-vessels contract and accommodate 
themselves to the smaller quantity of blood (in consequence of the stimulation of the vasomotor 
centre in the medulla). The loss of one-third of the total blood diminishes the blood-pressure 
considerably (one-fourth in the carotid of the dog). If the hemorrhage is not such as to cause 
death, the fluid part of the blood and the dissolved salts are restored by absorption from the 
tissues, the blood-pressure gradually rises, and then the albumin is restored, though a longer [Sec. 41. 
58 
ABNORMAL CONDITIONS OF THE BLOOD. 
time is required for the formation of red corpuscles. At first, therefore, the blood is abnormally 
rich in water (hydraemia), and at last abnormally poor in corpuscles (oligocythaemia, hypo- 
globulie). With the increased lymph-stream which pours into the blood, the colorless corpuscles 
are considerably increased above normal, and during the period of restitution fewer red cor- 
puscles seem to be used up (e. g., for bile). 
After moderate bleeding from an artery in animals, Buntzen observed that the volume of the 
blood was restored in several hours; after more severe hemorrhage in 24 to 48 hours. The red 
blood-corpuscles, after a loss of blood equal to 1.1 to 4.4 per cent, of the body-weight, are 
restored only after 7 to 34 days. The regeneration begins after 24 hours. During the period 
of regeneration the number of the blood-corpuscles in an early stage of development is increased. 
The newly-formed corpuscles contain less Hb than normal (Jac. G. Ott). Even in man the 
duration of the period of regeneration depends upon the amount of blood lost (Lyon). The 
amount of haemoglobin is diminished nearly in proportion to the amount of the hemorrhage 
(Bizzozero and Salvioli). 
[Hemorrhages in cold-blooded animals.—These animals can bear very considerable loss 
of blood, and, in fact, the frog can live for a considerable time without blood. In the experi- 
ment of Cohnheim known as the “salt frog,” all the blood is washed out of its vessels by means 
of normal saline solution (.75 per cent. NaCl) and the blood-vessels are filled with the same fluid. 
Such a frog will live for several days, and the elimination of CO,2 goes on as in an intact frog. 
This experiment obviously has a very important bearing on the question as to the seat of the 
formation of C02—i.e., whether it is formed in the blood or in the tissues. It clearly points to 
the latter view.] 
Metabolism in Ajiaemia.—The condition of the metabolism in the case of persons suffering 
from anaemia is important. The decomposition of proteids is increased (the same is the case in 
hunger), hence the excretion of urea is increased (Bauer). The decomposition of fats, on the 
contrary, is diminished, which stands in relation with the diminution of C02 given off. 
Anaemic and chlorotic persons put on fat easily. The fattening of cattle is aided by occasional 
bleedings and by intercurrent periods of hunger (Aristotle). 
(2) An excessive thickening of the blood through loss of water is called Oligaemia sicca. 
This occurs in man after copious watery evacuations, as in cholera, so that the thick tarry blood 
stagnates in the vessels. Perhaps a similar condition —though to a less degree—may exist after 
very copious perspiration. 
(3) If the proteids in blood be abnormally diminished the condition is called Oligaemia 
hypalbuminosa; they may be diminished about one-half. They are usually replaced by an 
excess of water in the blood [so that the blood is watery, constituting hydraemia]. Loss 
of albumin from the blood is caused directly by albuminuria (25 grams of albumin may be 
given off by the urine daily), persistent suppuration, great loss of milk, extensive cutaneous 
ulceration, albuminous diarrhoea (dysentery). Frequent and copious hemorrhages, however, 
by increasing the absorption of water into the vessels, at first produces oligaemia hypalbuminosa. 
For the abnormal changes of the red and white 
blood-corpuscles, see g 10; for Haemophilia, \ 28. 
[Organisms in the Blood.—The presence of animal 
and vegetable parasites in the blood gives rise to certain 
diseases. Some of these, and especially the vegetable 
organisms, have the power of multiplying in blood. The 
vegetable forms belonging to the schizomycetes or 
fission fungi are frequently spoken of collectively under 
the title bacteria. They are classified by Cohn into 
I. Sphaerobacteria 
II. Microbacteria 
III. Desmobacteria 
IV. Spirobacteria 
exhibit movements. 
These forms are shown in fig. 32. The micrococci (A) 
are examples of I; while Bacterium termo (B) is an ex- 
ample of II. In III the members are short cylindrical 
rods, straight (Bacillus, D) or wavy (Vibrio, C). Splenic 
fever of cattle is due to the presence of Bacillus anthracis 
(fig. 32). These rod-shaped bodies under proper condi- 
tions divide transversely and elongate, but they also form spores in their interior, which in turn under 
appropriate conditions may germinate. Class IV is represented by two genera, Spirochaeta and 
Spirillum (fig. 32), the former with close, and the latter with open spirals. The Spirochaeta 
Obermeieri (often spoken of as “spirillum”) is present in the blood during the paroxysms in 
persons suffering from relapsing fever. Amongst animal parasites are Filaria sanguinis, and 
Bilharzia Haematobia, which occurs in the portal vein and in the veins of the urinary apparatus ] 
A, micrococcus ; B, bacterium ; C, 
vibrios; D. bacilli; E, spirillum. 
Fig. 32. Physiology of the Circulation. 
42. GENERAL VIEW. —The blood within the vessels is in a state of 
continual motion, being carried from the ventricles by the large arteries (aorta 
and pulmonary) and their branches to the system of 
capillary vessels from which again it passes into the 
veins that end in the atria of the auricles ( W. Harvey, 
1628). 
The cause of the circulation is the difference 
of pressure which exists hetween the blood in the 
aorta and pulmonary artery on the one hand, and 
the two venae cavae and the four pulmonary veins on 
the other. The blood, of course, moves continually 
in its closed tubular system in the direction of least 
resistance. The greater the difference of pressure, the 
more rapid the movement will be. The cessation of 
the difference of pressure (as after death) naturally 
brings the movement to a standstill (§ 81). The 
circulation is usually divided into— 
(1) The greater, or systemic circulation, 
which includes the course of the blood from the left 
auricle and left ventricle, through the aorta and all 
its branches, the capillaries of the body and the veins, 
until the two venae cavge terminate in the right 
auricle. 
(2) The lesser, or pulmonic circulation, 
which includes the course from the right auricle and 
right ventricle, the pulmonary artery, the pulmonary 
capillaries, and the pulmonary veins springing from 
them, until these open into the left auricle. 
(3) The portal circulation is sometimes spoken 
of as a special circulatory system, although it repre- 
sents only a second set of capillaries (within the liver) 
introduced into the course of a venous trunk. It con- 
sists of the vena portarum—formed by the union of 
the intestinal or mesenteric and splenic veins, and it 
passes into the liver, where it divides into capillaries, 
from which the hepatic veins arise. The hepatic 
vein joins the inferior vena cava. 
Strictly speaking, however, there is no special portal circula- 
tion. Similar arrangements occur in other animals in different 
organs, e.g., snakes have such a system in their supra renal 
capsules, and the frog in its kidneys. When an artery splits up 
into fine branches during its course, and these branches do not 
form capillaries, but reunite into an arterial trunk, a rete mirabile is formed, such as occurs in 
apes and the edentata. Microscopic retia mirabilia exist in the human mesentery (Schobl). 
Similar arrangements may exist in connection with veins, giving rise to venous retia mirabilia. 
Fig- 33- 
Scheme of the circulation.—ar 
right, b, left auricle; A, 
right, B, left ventricle; 
I, pulmonary artery; 2, 
aorta ; /, area of pul- 
monary, K, area of sys- 
temic circulation ; o, the. 
superior vena cava; G, area 
supplying the inferior vena 
cava, u ; d, d, intestine; m, 
mesenteric artery; </, portal 
vein ; L, liver ; h, hepatic 
vein. 60 
STRUCTURE OF THE HEART FIBRES. 
[Sec. 43. 
43. THE HEART.—The muscular fibres of the mammalian heart consist of short (50 to 
70 [x in man), very fine, transversely striated fibres, which are actual unicellular elements, devoid 
of a sarcolemma (15 to 25 u broad), and usually divided at their blunt ends, by which means 
they anastomose and form a network (fig. 34, A, B). The individual muscle-cells contain in 
their centre an oval nucleus, and are held together by a cement-substance, which is blackened 
by silver nitrate, and dissolved by a 33 per cent, solution of caustic potash. This cement is also 
dissolved by a 40 per cent, solution of nitric acid. The transverse striae are not very distinct, 
and not unfrequently there is an appearance of longitudinal striation, produced by a number of 
very small granules arranged in rows within the fibres. The fibres are gathered lengthwise in 
bundles, or fasciculi, surrounded and separated from each other by delicate processes of the 
perimysium. When the connective-tissue is dissolved by prolonged boiling, these bundles can 
be isolated, and constitute the so-called “fibres” of the heart. The transverse sections of the 
bundles in the auricles are polygonal or rounded, while in the ventricles they are somewhat 
flattened. [The muscular mass of the heart is called the myocardium, and is invested by 
fibrous tissue. It is important to notice that the connective tissue of the visceral pericardium 
(epicardium) is continuous with that of the endocardium by means of the perimysium surround- 
ing the bundles of muscular fibres.] The fine spaces which exist between these bundles 
form narrow lacunae, lined with epithelium, and constituting part of the lymphatic system of 
the heart. 
[The cardiac muscular fibres occupy an intermediate position between striped and plain 
muscular fibres. Although they are striped, they are involuntary, not being directly under the 
influence of the will, while they contract more slowly than a voluntary muscle of the skeleton.] 
Fig- 34- 
A, muscular fibres from the heart of a mammal, and C from a frog; B, transverse section of 
the cardiac fibres; b, connective-tissue corpuscles ; c, capillaries. 
In the frog’s heart the muscular fibres are in shape elongated spindles, or fusiform, in this 
respect resembling the plain muscle cells, but they are transversely striped (fig. 34, C). They 
are easily isolated by means of a 33 per cent, solution of potash or dilute alcohol. 
44. ARRANGEMENT OF THE CARDIAC MUSCULAR 
FIBRES.—The study of the embryonic heart is the key to a proper under- 
standing of the complicated arrangement of the fibres in the adult heart. The 
simple tubular heart of the embryo has an outer circular and an imier longitu- 
dinal layer of fibres. The septum is formed later; hence, it is clear that a part, 
at least, of the fibres must be common to the two auricles, and a part also to the 
two ventricles, since there is, originally, but one chamber in the heart. The 
muscular fibres of the auricles are, however, completely separated from those 
of the ventricles by the fibro-cartilaginous rings. In the auricles the fundamental 
arrangement of the embryonic fibres partly remains, while in the ventricles it 
becomes obscured as the cavities undergo a sac-like dilatation, and also become 
twisted in a spiral manner. . 
(1) The muscular fibres in the auricles are completely separated from 
the fibres of the ventricles by the fibrous rings which surround the auriculo- 
ventricular orifices, and which serve as an attachment for the auriculo-ventri- 
cular valves (fig. 35, I). The auricles are much thinner than the ventricles, 
and their fibres are generally arranged in two layers ; the outer transverse layer Sec. 44.] 
ARRANGEMENT OF THE HEART FIBRES. 
61 
is continuous over both auricles, whilst the inner one is directed longitudinally. 
The outer transverse fibres may be traced from the openings of the venous 
trunks anteriorly and posteriorly over the auricular walls. The longitudinal 
fibres are specially well marked where they are inserted into the fibro-cartila- 
ginous rings, while in some parts of the anterior auricular wall they are not 
continuous. In the auricular septum, some fibres, circularly disposed around 
the fossa ovalis (formerly the embryonic opening of the foramen ovale), are 
well marked. Circular bands of striped muscles exist around the veins where 
they open into the heart; these are least marked on the inferior vena cava, and 
are stronger and reach higher (2.5 cm.) on the superior vena cava (fig. 35, II). 
Similar fibres exist around the pulmonary veins, where they join the left auricle, 
and these fibres (which are arranged as an inner circular and an outer longi- 
tudinal layer) can be traced to the hilus of the lung in man and some mammals ; 
in the ape and rat they extend on the pulmonary veins right into the lung. In 
the mouse and bat, again, the striped muscular fibres pass so far into the lungs 
that the walls of the smaller veins are largely composed of striped muscle 
(Stieda). 
I. Course of the muscular fibres on the left auricle with the outer transverse and inner longi- 
tudinal fibres, the circular fibres on the pulmonary veins (v. pi) ; V, the left ventricle (John 
Reid). II. Arrangement of the striped muscular fibres on the superior vena cava (Elischer) 
—a, opening of vena azygos; v, auricle. 
Fig- 35- 
Circular muscular fibres are found where the vena magna cordis enters the 
heart, and in the Valvula Thebesii which guards it. 
Physiological Significance.—(x) The auricles contract independently of 
the ventricles. This is seen when the heart is about to die; when there may 
be several auricular contractions for one ventricular, and at last only the 
auricles pulsate. The auricular portion of the right auricle beats longest; 
hence it is called the “ ultimum moriens.” Independent rhythmical contrac- 
tions of the venae cavae and pulmonary veins are often noticed after the heart 
has ceased to beat. [This beating can also be observed in those veins in a rab- 
bit after the heart is cut out of the body.] 
(2) The double arrangement of the fibres (transverse and longitudinal) pro- 
duces a simultaneous and uniform diminution of the auricular cavity (such as 
occurs in most of the hollow viscera). 
(3) The contraction of the circular muscular fibres around the venous orifices, 
and the subsequent contraction of the auricle, cause these veins to empty them- 
selves into the auricle; and by their presence and action they prevent any large 
quantity of blood from passing backward into the veins when the auricle con- 62 
ARRANGEMENT OF THE VENTRICULAR FIBRES. 
[Sec. 45. 
tracts. [No valves are present in the superior and inferior vena cava in the adult 
heart, or in the pulmonary veins, hence the contraction of these circular muscular 
fibres plays an important part in preventing any reflux of blood during the 
contraction of the auricles.] 
45. ARRANGEMENT OF THE VENTRICULAR FIBRES. 
—(2) The muscular fibres in the thick wall of the ventricles are arranged 
in several layers under the pericardium (fig. 36, A). First, there is an outer 
longitudinal layer (A), which is in the form of single bundles on the right 
ventricle, but forms a complete layer on the left ventricle, where it measures 
about one-eighth of the thickness of the ventricular wall. A second longitudinal 
layer of fibres lies on thdinner surface of the ventricles, distinctly visible at the 
orifices, and within the vertically placed papillary muscles, whilst elsewhere it is 
replaced by the irregularly arranged trabeculae carnse. Between these two layers 
there lies the thickest layer, consisting of more or less transversely arranged 
bundles, which may be broken up into single layers more or less circularly 
disposed. The deep lyjjiphatic vessels run between the layers, whilst the blood- 
vessels lie within the substance of the layers, and are surrounded by the primi- 
Course of the ventricular muscular fibres. A, on the anterior surface ; B, view of the apex with 
the vortex; C, course of the fibres within the ventricular wall; D, fibres passing into a 
papillary muscle (/). 
Fig. 36. 
tive bundles of muscular fibres. All three layers are not completely independent 
of each other; on the contrary, the fibres which run obliquely form a gradual 
transition between the transverse layers and the inner and outer longitudinal 
layers. It is not, however, quite correct to assume that the outer longitudinal 
layer gradually passes into the transverse, and this again into the inner longi- 
tudinal layer (as is shown schematically in C) ; because, as Henle pointed out, 
the transverse fibres are relatively far greater in amount. In general, the outer 
longitudinal fibres are so arranged as to cross the inner longitudinal layer at an 
acute angle. The transverse layers lying between these two form gradual tran- 
sitions between these directions. At the apex of the left ventricle, the outer 
longitudinal fibres bend or curve so as to meet at the so-called vortex B, where 
they enter the muscular substance, and, taking an upward and inward direction, 
reach the papillary muscles, P, D; although it is a mistake to say that all the 
bundles which ascend to the papillary muscles arise from the vertical fibres of 
the outer surface ; many seem to arise independently within the ventricular wall. 
According to Henle, all the external longitudinal fibres do not arise from the 
fibrous rings or the roots of the arteries. The mitral orifice is surrounded by 
circular fibres which act like a sphincter (.Henle). Sec. 45-] 
PERICARDIUM, VALVES. 
63 
[The assumption that the muscles of the ventricle are arranged so as to form a figure of 8, or 
in loops, seems to be incorrect; thus, fibres are said to arise at the base of the ventricle, to pass 
over it, and to reach the vortex, where they pass into the interior of the muscular substance, to 
end either in the papillary muscles or high up on the inner surface of the heart at its base. 
Figs. C and D give a schematic representation of this view.] 
Only the general arrangement of the ventricular muscular fibres has been indicated. Accord- 
ing to Pettigrew, there are seven layers in the ventricle, viz., three external, a fourth or 
central layer, and three internal. These internal layers are continuous with the corresponding 
external layers at the apex, thus—one and seven, two and six. 
46. PERICARDIUM, ENDOCARDIUM, VALVES.—The pericardium encloses 
within its two layers [visceral and parietal] a lymph space—the pericardial space—which con- 
tains a small quantity of lymph—the pericardial fluid. It has the structure of a serous 
membrane, i.e., it consists of connective-tissue mixed with fine elastic fibres arranged in the form 
of a thin delicate membrane, and covered on its free surfaces with a single layer of epithelium 
or endothelium, composed of irregular, polygonal, flat cells. [Like serous cavities generally, it 
is a closed cavity, and does not communicate with the exterior.] A rich lymphatic network lies 
under the pericardium (fig. 29) and endocardium ; also in the deeper layers of the visceral peri- 
cardium next the heart and between muscular bundles (Salvioli). No stomata exist either on its 
visceral or parietal layers. Around the coronary arteries of the heart exist lymph-vessels and 
deposits of fat, which lie in the furrows and grooves in the subserosa of the epicardium 
(visceral layer). 
The endocardium, next the cavity of the heart, consists of a single layer of polygonal, flat, 
nucleated endothelial cells. [Under this there is a nearly homogeneous hyaline layer (fig. 37,a), 
slightly thicker on the left side, which 
gives the endocardium its polished ap- 
pearance.] Then follows, as the basis of 
the membrane, a layer offine elastic fibres 
—stronger in the auricles, and in some 
places thereof assuming the characters of 
a fenestrated membrane. Between these 
fibres a small quantity of connective- 
tissue exists, which is in larger amount 
and more areolar in its characters next 
the myocardium. Bundles of non-striped 
muscular fibres (few in the auricles) are 
scattered and arranged for the most part 
longitudinally between the elastic fibres. 
These seem evidently meant to resist the 
distention which is apt to occur when the 
heart contracts and great pressure is put 
upon the endocardium. In all cases where 
high pressure is put upon walls composed 
of soft parts, we always find muscular 
fibres present, and never elastic fibres alone. No blood-vessels occur in the endocardium (Langer). 
The valves also belong to the endocardium—both the semi-lunar valves of 
the aorta and pulmonary artery, which prevent the blood from passing back into 
the ventricles, and the tricuspid (right auriculo-ventricular) and mitral (left 
auriculo-ventricular), which protect the auricles from the same result. The 
lower vertebrata have valves in the orifices of the venae cavse, which prevent 
regurgitation into them; while in birds and some mammals these valves exist 
in a rudimentary condition. The valves are fixed by their base to resistant 
fibrous rings, consisting of elastic and fibrous tissue. They are formed of two 
layers—(1) the fibrous, which is a direct continuation of the fibrous rings, and 
(2) a layer of elastic elements. The elastic layer of the auriculo-ventricular 
valves is an immediate prolongation of the endocardium of the auricles, and is 
directed towards the auricles. The semi-lunar valves have a thin elastic layer 
directed towards the arteries, which is thickest at their base. The connective- 
tissue layer directed towards the ventricle is about half the thickness of the 
valve itself. 
The auriculo-ventricular valves also contain striped muscular fibres. 
Radiating fibres proceed from the auricles and pass into the valves, which, 
Section of the endocardium, a, hyaline layer; b, 
network of fine elastic fibres; c, network of 
stronger elastic fibres ; d, myocardium with 
blood-vessels, which do not pass into the endo- 
cardium. 
Fig. 37- 64 
purkinje’s fibres. 
[Sec. 46. 
when the atria contract, retract the valves towards their base, and thus make a 
larger opening for the passage of the blood into the ventricles; according to 
Paladino, they raise the valves after they have been pressed down by the blood- 
current. This observer also described some longitudinal fibres which proceed 
from the ventricles to enter these valves. There is also a concentric layer of 
fibres arranged near their point of attachment, and directed more towards their 
ventricular surface. These fibres seem to contract sphincter-like when the 
ventricle contracts, and thus approximate the base of the valves, and so prevent 
too great tension being put upon them. The larger chordse tendineae also con- 
tain striped muscle, while a delicate muscular network exists in the valvula 
Thebesii and valvula Eustachii. 
Purkinje’s Fibres consist of an anastomosing system of grayish fibres which exist in the 
sub-endocardial tissue of the ventricles, especially in the heart of the sheep and ox. The fibres 
are made up of polyhedral clear cells, containing some granular protoplasm, and usually two 
nuclei (fig. 38). The margins of the cells are striated. Transition-forms are found between 
these cells and the ordinary cardiac 
fibres; in fact, these cells become con- 
tinuous with the true fully developed 
cardiac fibres. They represent cells 
which have been arrested in their de- 
velopment. They are absent in man 
and the lower vertebrates, but in birds 
and some mammals they are well marked 
(Schweigger- Seidel, Ranvier). 
Blood-Vessels occur in the auricu- 
lo-ventricular valves only where muscu- 
lar fibres are present, while the semi- 
lunar valves are usually devoid of vessels 
except at their base. The best figures 
of the blood-vessels of the valves are 
given by Langer and Darier. The 
network of lymphatics in the endo- 
cardium reaches towards the middle of 
the valves. 
Weight of the Heart.—According 
to W. Muller the proportion between the weight of the body and the heart in the child, and until 
the body reaches 40 kilos., is 5 grms. of heart-substance to 1 kilo, of body-weight; when the 
body-weight is from 50 to 90 kilos, the ratio is 1 kilo, to 4 grms. of heart-substance; at 100 
kilos. 3.5 grms. As age advances, the auricles become stronger. The right ventricle is half the 
weight of the left. The weight of the heart of an adult man is about 309 grm«.; female, 274 
grms. [According to the heart is about the size of the closed fist of the individual.] 
Blosfeld and Dieberg give 346 grms. for the male, and 310 to 340 grms for the female heart. 
The specific gravity of the heart-muscle ,is 1.069. The thickness of the left ventricle in the 
middle in man is 11.4 mm., and in woman 11.15 ; that of the right is 4.1 and 3.6 mm. respec- 
tively. 
47. AUTOMATIC REGULATION OF THE HEART.—Anatomical Investiga- 
tions.—The two coronary arteries arise from the first part of the aorta in the region of the sinus 
of Valsalva. The position of origin varies—(1) either the orifices lie within the sinus, or (2) 
their openings are only partially reached by the margins of the setni-lunar valves (which is usually 
the case in the left coronary artery of man and the ox), or (3) their orifices lie clear above the 
margins of the valves. Post-mortem observations seem to snow that during contraction of the 
ventricle it is very improbable that the semi-lunar valves constantly cover the origin of the 
coronary arteries. 
Automatic Regulation of the Heart.—Briicke attempted to show that 
during the systole, or contraction of the ventricle, the semi-lunar valves covered 
the openings of the coronary arteries, so that these vessels could be filled with 
blood only during the diastole or relaxation of the ventricle. To him it seemed 
that (a) the diastolic filling of the coronary arteries would help to dilate the 
ventricles; (f?) on the contrary, a systolic filling of these arteries would oppose 
the contraction, because the systolic filling and expulsion of the blood from the 
Purkinje’s fibres isolated with dilute alcohol. c, cell; 
f, striated substance; n, nucleus. X 3°°- 
Fig. 38. Sec. 47.] 
AUTOMATIC REGULATION OF THE HEART. 
65 
coronary arteries would diminish the force of the ventricular contraction. [To 
this supposed arrangement Briicke gave the name “ Selbststeuerung,” which 
may be rendered as above, or as “self-controlling” action of the heart by the 
aortic valves.] 
Arguments against Briicke’s View.—The following considerations militate against this 
theory: (i) Filling the coronary vessels under a high pressure in a dead heart causes a diminu- 
tion of the ventricular cavity [v. Wittich). (2) The chief trunks of the coronary arteries lie in 
loose sub-pericardial fatty tissue in the cardiac sulci, hence a dilatation of the ventricle through 
this agency is most unlikely (Landois). (3) Experiments on animals have shown that a coronary 
artery spouts, like all arteries, during the systole of the ventricle. Von Ziemssen found that in 
the case of a woman who had a large part of the anterior wall of the thorax removed by an 
operation, the heart being covered only by a thin membrane, the pulse in the coronary arteries 
was synchronous with the pulse in the pulmonary artery. H. N. Martin and Sedgwick placed 
a manometer in connection with the coronary artery, and another with the carotid in a large dog, 
and they found that the pulsations occurred simultaneously. When a coronary artery is divided, 
the blood flows out continuously, but undergoes acceleration during the systole of the ventricles 
(.Endemann, Peris'). (4) If a strong intermittent current of water be allowed to flow through 
a sufficiently wide tube into the left auricle of a fresh pig’s heart, so that the water passes into 
the aorta, and if the aorta be provided with a vertical tube, the water flows continuously from 
the coronary arteries, and is accelerated during the systole. (5) It is exceedingly improbable 
that the coronary arteries should be filled during the diastole, while all the other arteries are filled 
during systole of the ventricle. (6) There is always a sufficient quantity of blood in the sinus 
of Valsalva to fill the arteries during the first part of the systole. (7) The valves, when raised, 
are not applied directly to the aortic wall (Hamberger, Riidinger) even by the most energetic 
pressure from the ventricle (Sandborg and IVorm Muller). (8) Observations on voluntary 
muscles have shown that the small arteries dilate during contraction of the muscle, and the 
blood-stream is accelerated. (9) By the systolic filling of the aorta the arterial path is elongated 
—this elastic distention is compensated before the diastole occurs. By the recoil of the aortic 
walls the layer of blood in them is driven backwards and closes the valves (Ceradini). Accord- 
ing to Sandborg and Worm Muller, the semi-lunar valves close just after the ventricles have begun 
to relax, which agrees with the curve obtained from the cardiac impulse (fig. 39). 
During the systole, the small arterial trunks lying next the ventricular cavi- 
ties have to bear a higher pressure than that borne by the aorta, and their lumen 
must be compressed during the systole so that their contents are propelled 
towards the veins. 
Peculiarities of the Cardiac Blood-Vessels.—The capillary vessels of the myocardium 
are very numerous, corresponding to the energetic activity of the heart. Where they pass into 
veins, several unite at once to form a wide venous trunk, whereby an easy passage is offered to 
the blood. The veins are provided with valves so that (1) during systole of the right auricle 
the venous stream is interrupted; (2) during contraction of the ventricles, the blood in the 
coronary veins is similarly accelerated as in the veins of muscles. The coronary arteries are 
characterized by their very thick connective-tissue and elastic intima, which perhaps accounts 
for the frequent occurrence of atheroma of these vessels (.Henle). Some observers maintain that 
the coronary arteries do not anastomose, but this is denied by Langer and Krause. [West has 
injected the one artery from the other.] Many of the small lower vertebrates have no blood- 
vessels in their heart-muscle, e.g., frog (Hyrtl). 
Ligature of the Coronary Arteries.—The phenomena produced by par- 
tial obliteration or ligature of the coronary arteries are most important. In 
man analogous conditions occur, as in atheroma or calcification of these arteries. 
See and others have ligatured the coronary arteries in dogs, and found that after 
two minutes the cardiac contractions gave place to twitchings of the muscular 
fibres, and ultimately the heart ceased to beat. Ligature of the anterior coro- 
nary artery alone, or of both its branches, is sufficient to produce this result. 
If the coronary arteries be compressed or tied in a rabbit in the angle between 
the bulbus aortae and the ventricle, the heart’s action is soon weakened, owing 
to the sudden anaemia and to the retention of the decomposition-products of 
the metabolism in the heart-muscle. Ligature of one artery first affects the 
corresponding ventricle, then the other ventricle, and last of all, the auricles. 
Hence, compression of the left coronary artery (with simultaneous artificial 66 
CARDIAC CYCLE. 
[Sec. 47. 
respiration in a curarized animal), causes slowing of the contractions, especially 
of the left ventricle, whilst the right one at first contracts more quickly, and 
then gradually its rhythm is slowed. The contractions of the left ventricle are 
not only slowed but also weakened, whilst the right pulsates with undiminished 
force. Hence it follows that, as the left half of the heart cannot expel the 
blood in sufficient quantity, the left auricle becomes filled, whilst the right 
ventricle, not being affected, pumps blood into the lungs. (Edema of the 
lungs is produced by the high pressure in the pulmonary circulation, which is 
propagated from the right heart through the pulmonary vessels into the left 
auricle (Samuelson and Griinhageri). According to Sig. Mayer, protracted 
dyspnoea causes the left ventricle to beat more feebly sooner than the right, so 
that the left side of the heart becomes congested. Perhaps this may explain 
the occurrence of pulmonary oedema during the death-agony. 
Cohnheim and v. Schulthess-Rechberg found, after ligature of one of the large branches of a 
coronary artery in a dog, that at the end of a minute the pulsations became intermittent. This 
intermittence becomes more pronounced, the two sides of the heart do not contract simultaneously 
(arhythmia), the heart beats more slowly, and the blood-pressure falls. Suddenly, about 105 
seconds after the ligature is applied, both ventricles cease to beat, and there is a great fall of 
F'g. 39- 
Diagram of the sequence of events in the heart during a cardiac cycle. 
the blood-pressure. After an arrest lasting for about io to 20 seconds, twitching movements 
occur in the ventricles, while the auric'es pulsate regularly, and may continue to do so for many 
minutes, but the ventricles cease to beat altogether after 50 seconds. According to Lukjanow, 
there is a peristaltic condition which operates upwards and downwards, and occurs in the period 
between the regular contraction and the twitching vibratory movement. Stimulation of the 
vagus does not arrest these peristaltic movements. 
Pathological. — In so-called sclerosis of the coronary arteries in old age, there are attacks of 
diminished cardiac activity, weakness of the heart, and altered rhythm and frequency, with 
consequent breathlessness; there may also be loss of consciousness, congestions, and attacks of 
pulmonary oedema. Death may take place unexpectedly from sudden arrest of the heart’s action. 
48. MOVEMENTS OF THE HE ART.—Cardiac Revolution.— 
The movement of the heart is characterized by an alternate contraction and re- 
laxation of its walls. The total cardiac movement is called a “cardiac 
revolution,’’ or a “cardiac cycle,” and consists of three acts—the contrac- 
tion or Systole of the auricles, the contraction or Systole of the ven- 
tricles, and the pause (fig. 39). During the pause the auricles and ventricles 
are relaxed ; during the contraction of the auricles the ventricles are at rest; 
whilst during the contraction of the ventricles the auricles are relaxed. The rest 
during the phase of relaxation is called the diastole. Sec. 48.] 
EVENTS DURING A CARDIAC CYCLE. 
67 
The three events— 
Systole of the auricles, 
Systole of the ventricles, 
Pause, 
may be represented by the preceding diagram, while the table shows their 
relative duration (§ 51). 
Landois. 
Gibson. 
Duration of the auricular systole, 
o 
M 
O 
! 
O 
0.100-0.130 
do. ventricular systole, 
• 0.309-0.346 
o-325-o.395 
do. pause, 
°-393-°-4°7 
o.455-o-69° 
The following is the sequence of events in the heart during a cardiac 
cycle :— 
(A) The blood flows into the auricles, and thus distends them and the 
auricular appendices. This is caused by— 
(i) The pressure of the blood in the venae cavae (right side) and the pul- 
monary veins (left side) being greater than the pressure in the auricles. 
(2) The elastic traction of the lungs (§ 68), which, after complete systole of the 
auricles, pulls asunder the now relaxed and yielding auricular walls. The 
auricular appendages are also filled at the same time, and they act to a certain 
extent as accessory reservoirs for the large supply of blood streaming into the 
auricles. 
(B) The auricles contract, and we observe in rapid succession— 
(1) The contraction and emptying of the auricular appendix towards the 
atrium. Simultaneously the mouths of the veins become narrowed, owing to the 
contraction of their circular muscular fibres (more especially the superior vena 
cava and the pulmonary veins) ; (2) the auricular walls contract simultaneously 
towards the auriculo-ventricular valves and the venous orifices, whereby (3) the 
blood is driven into the relaxed ventricles, which are considerably distended 
thereby. 
The contraction of the auricles is followed by— 
(a) A slight stagnation of the blood in the large venous trunks, as can be 
observed in a rabbit after division of the pectoral muscles so as to expose the 
junction of the jugular with the subclavian vein. There is no actual regurgita- 
tion of the blood, but only a partial interruption of the inflow into the auricles, 
because the mouths of the veins are contracted, and the pressure in the superior 
vena cava and pulmonary veins soon holds in equilibrium any reflux of blood; 
and lastly, because any reflux into the cardiac veins is prevented by valves. 
The movement of the heart causes a regular pulsatile phenomenon in the blood 
of the venae cavae, which under abnormal circumstances may produce a venous 
pulse (see § 99). 
(b) The chief motor effect of the contraction of the auricles is the dilatation 
of the relaxed ventricle, which has already been dilated to a slight extent by the 
elastic traction of the lungs. 
Aspiration of the Ventricles.—The dilatation of the ventricles has been ascribed to the 
elasticity of the muscular walls—the strongly contracted ventricular walls (like a compressed 
india-rubber bag), in virtue of their elasticity, are supposed, in returning to their normal resting 
form, to suck in or aspirate the blood under a negative pressure; this power on the part of the 
ventricle is not great (p. 69). 
('c) When the ventricles are distended by the inflowing blood, the auriculo- 
ventricular valves are floated up, partly by the recoil or reflexion of the blood 
from the ventricular wall, and partly owing to their lighter specific gravity, 
whereby they easily float into a more or less horizontal position. The valves 
are also raised to a slight extent by the longitudinal muscular fibres, which pass 
from the auricles into the cusps of the valve. 68 
EVENTS DURING A CARDIAC CYCLE. 
[Sec. 48. 
(C) The ventricles now contract, and simultaneously the auricles relax, 
whereby— 
(1) The muscular walls contract forcibly from all sides, and thus diminish 
the ventricular cavity. (2) The blood is at once pressed against the under 
surface of the auriculo-ventricular valves, whose curved margins are opposed to 
each other like teeth, and are pressed hermetically against each other (fig. 40). 
It is impossible for the blood to push the cusps backwards into the auricle, as 
the chordae tendineae hold fast their margins and surfaces like a taut sail. The 
Cast of the ventricles of the human heart viewed from behind and above; the walls have been 
removed, and only the fibrous rings and the auriculo-ventricular valves are retained. Z, 
left, R, right ventricle; S, septum ; F, left fibrous ring, with mitral valve closed; Z>, right 
fibrous ring, with tricuspid closed; A, aorta, with the left (C\) and right (C) coronary 
arteries; S, sinus of Valsalva; F, pulmonary artery. 
Fig. 40. 
margins of the neighboring cusps are also kept in apposition, as the chordae 
tendineae from one papillary muscle always pass to the adjoining edges of two 
cusps. The extent to which the ventricular wall is shortened is compensated 
by the contraction of the papillary muscle, and also of the large muscular 
chordae, so that the cusps cannot be pushed into the auricle. When the valves 
are closed, their surfaces are horizontal, so that, even when the ventricles are 
contracted to their greatest extent, there remains in the supra-papillary space a 
small amount of blood which is not expelled (Sandborg and Worm Muller). Sec. 48.] 
ENDOCARDIAL PRESSURE. 
69 
(3) When the pressure within the ventricles exceeds that in the arteries, the 
semi-lunar valves are forced open and stretched like a sail across the pocket-like 
sinus, without, however, being directly applied to the wall of the arteries 
(pulmonary and aorta), and thus the blood enters the arteries. 
(D) Pause.—As soon as the ventricular contraction ends, and the ventricles 
begin to relax, the semi-lunar valves close (fig. 41). The diastole of the 
ventricles is followed by the pause. Under normal circumstances, the right 
and left halves of the heart always contract or relax uniformly and simultane- 
ously. 
Endocardial Pressure and Negative Pressure in the Ventricle.—Goltz and Gaule 
found that there was a negative pressure of 23.5 mm. Hg. (dog) in the interior of the ventricle 
during a certain phase of the heart’s action. This they determined by a maximal and minimal 
manometer. They surmised that this phase coincided with the 
diastolic dilatation, for which they assumed a considerable power 
of aspiration. Moens is of opinion that this negative pressure 
within the ventricle obtains shortly before the systole has reachea 
its height, i. e., just before the inner surface of the ventricles and 
the valves, after the blood is expelled, are nearly in apposition. 
He explains this aspiration as being due to the formation of an 
empty space in the ventricle caused by the energetic expulsion oi 
the blood through the aorta and pulmonary artery. 
[Maximum and Minimum Manometer.—Into the tube 
connecting the interior of the ventricle of the heart with the 
ordinary U-shaped mercury manometer, is introduced the maxi- 
mum manometer, which is constructed on the principle of a ball 
and cup valve (fig. 42), the ball A, being kept closed in B by a 
spring C. To make it a maximum manometer the end A is con- 
nected with the heart, and B with the mercurial manometer 
(fig. 42). When a clamp is placed on the upper limb the valve 
is acted on only at each systole of the heart, blood is driven 
beyond it, but during diastole it closes and no blood can return. 
This goes on until the pressure beyond the valve in the mercury manometer is the same as in the 
heart. If the valve be reversed, it is converted into a minimum manometer.] 
49. PATHOLOGICAL CARDIAC ACTION.—Cardiac Hypertrophy.—All re- 
sistances to the movement of the blood through the various chambers of the heart, and through 
the vessels communicating with it, cause a greater amount of work to be thrown upon the portion 
of the heart specially related to this part of the circulatory system; consequently, there is 
produced an increase in the thickness of the muscular walls and dilatation of the heart. If the 
Fig. 41. 
The closed semi-lunar valve of 
the pulmonary artery seen 
from below. 
Fig. 42. 
Gaule’s maximum and minimum manometer A B. ] shows the actual size and arrangement of 
the valve. 
resistance or obstacle does not act upon one part of the heart alone, but on parts lying in the 
onward direction of the blood-stream, these parts also subsequently undergo hypertrophy. If in 
addition to the muscular thickening of a part of the heart, the cavity is simultaneously dilated, it 
is spoken of as eccentric hypertrophy or hypertrophy with dilatation. The obstacles most 
likely to occur in the blood vessels are narrowing of the lumen or want of elasticity in their walls; 
in the heart, narrowing of the arterial or venous orifices or insufficiency or incompetency of 
the valves. Incompetency of the valves forms an obstruction to the movement of the blood, 
by allowing part of the blood to flow back or regurgitate, thus throwing extra work upon the 
heart. 
Thus arise—(i) Hypertrophy of the left ventricle, owing to resistance in the area of the 
systemic circulation, especially in the arteries and capillaries—not in the veins. Amongst the 
causes are—constriction of the orifice or other parts of the aorta, calcification, atheroma, and 
want of elasticity of the large arteries and irregular dilatations or aneurisms in their course; 70 
PATHOLOGICAL CARDIAC ACTION. 
[Sec. 49. 
insufficiency of the aortic valves, in which case the same pressure always obtains within the 
ventricle and in the aorta; and, lastly, cirrhosis of the kidneys, whereby the excretion of water 
by these organs is diminished. Even in mitral insufficiency, compensatory hypertrophy of the 
left ventricle must occur, owing to the hypertrophy of the left atrium in consequence of the 
increased blood-pressure in the pulmonary circuit. 
(2) Hypertrophy of the left auricle occurs in stenosis or constriction of the left auriculo- 
ventricular orifice, or in insufficiency of the mitral valve, and it occurs also as a result of aortic 
insufficiency, because the auricle has to overcome the continual aortic pressure within the 
ventricle. 
(3) Hypertrophy of the right ventricle occurs (a) when there is resistance to the blood- 
stream through the pulmonary circuit. The resistance may be dhe to (a) obliteration of large 
vascular areas in consequence of destruction, shrinking or compression of the lungs, and the 
disappearance of numerous capillaries in emphysematous lungs; (fi) overfilling of the pulmo- 
nary circuit with blood in consequence of stenosis of the left auriculo-ventricular orifice, or 
mitral insufficiency—consequent upon hypertrophy of the left auricle resulting from aortic 
insufficiency. (b) When the valves of the pulmonary artery are insufficient, thus permitting the 
blood to flow back into the ventricle, so that the pressure within the pulmonary artery prevails 
within the right ventricle (very rare). 
(4) Hypertrophy of the right auricle occurs in consequence of the last-named condition, 
and also from stenosis of the tricuspid orifice, or insufficiency of the tricuspid valve (rare). 
Artificial Injury to the Valves.—If the aortic valves are perforated, with or without 
simultaneous injury to the mitral or tricuspid valves, the heart does more work; thus the 
physical defect is overcome for a time, so that the blood-pressure does not fall. The heart seems 
to have a store of reserve energy which is called into play. Soon, however, dilatation takes 
place, on account of the regurgitation of the blood into the heart. Hypertrophy then occurs, 
but the compensation meanwhile must be obtained through the reserve energy of the heart 
(O. Rosenbach). 
Impeded Diastole.—Among causes which hinder the diastole of the heart are—copious 
effusion into the pericardium, or the pressure of tumors upon the heart. The systole is 
greatly interfered with when the heart is united to the pericardium and to the connective tissue 
in the mediastinum. As a consequence, the connective tissue, and even the thoracic wall, are 
drawn in during contraction of the heart, so that there is a retraction of the region of the apex- 
beat during systole, and a protrusion of this part during the diastole. 
[Palpitation is a symptom indicating generally very rapid and quick action of the heart, the 
pulsations often being unequal in time and intensity, while’the person is generally conscious of 
the irregularity of the cardiac action. It may be due to some organic condition of the heart 
itself, especially where the cardiac muscles are weak, in cases of dilatation and hypertrophy of 
the left ventricle, where the heart is gradually becoming unable to overcome the resistances offered 
to its work, and especially during exertion when the heart is taxed above its strength. It may 
also occur where the blood-pressure is low, as in anaemia, so that the heart contracts quickly, 
there being little resistance opposed to its action. The excitability of the cardiac muscle may 
be increased as in fatty heart, when very slight exertion may excite it often in a paroxysmal 
way. In other cases, it is nervous in its origin, being either direct or reflex. In very emotional 
and excitable people (especially in women) it is easily set up, and in some people it may be 
produced reflexly by gastric or intestinal irritation or dyspepsia. It also frequently results from 
excesses of all kinds and the over-use of tobacco. The remedies to be used obviously depend 
on the cause. Where the blood-pressure is low, as in anaemia, digitalis and iron will do good; 
the former by increasing the blood-pressure, and the latter by improving the general nutrition of 
the body and the blood in particular. In neurotic cases cardiac sedatives are indicated, while 
in cases due to indigestion hydrocyanic acid is useful (Brunton).~\ 
[Fainting or Syncope.—Tn fainting the person loses consciousness, owing to a sudden arrest 
of the blood-supply to the brain, the face is pallid, the respiration is feeble or ceases, while the 
heart beats but feebly or not at all. The defective supply of blood to the brain may depend 
upon sudden arrest of the heart’s action, caused, it may be, by a fright, or the heart’s action 
may be arrested reflexly. Any cause which suddenly diminishes the blood-pressure may pro- 
duce it, or when pressure is suddenly removed from the large vessels, as in tapping the abdomen 
in ascites, without at the same time giving sufficient support to the abdominal viscera. When 
a person has been long in the recumbent position, on being rapidly set up in bed he may faint. 
In some forms of heart disease, sudden exertion or change of posture may produce it.] 
[Treatment.—The object is to restore consciousness and the action of the heart. Place the 
person in the horizontal position, keep the head low, even lower than the body, and do not 
support it with pillows. Dashing cold water on the face, so as to stimulate the fifth nerve, 
usually succeeds in causing the person to take a deep inspiration. In other cases a sniff of 
smelling salts or ammonia, acting through the nasal branch of the fifth nerve, will excite the 
cardiac and respiratory functions (§ 368).] Sec. 50.] 
CARDIOGRAM. 
71 
5o. THE APEX-BEAT CARDIOGRAM —Cardiac Impulse.— 
By the term “ apex-beat ” or “ cardiac impulse, ” or “ precordial pulsa- 
tion” is understood under normal circumstances an elevation (perceptible to 
touch and sight), in a circumscribed area of the fifth left intercostal space, and 
caused by the movement of the heart. [The term “ precordial ” is applied to the 
part of the chest situated in front of the heart. The cardiac impulse is felt, and 
is normally visible in the fifth left intercostal space, 2 inches below the nipple, 
and to 1 inch to its sternal side, or at a point 2 inches to the left of the 
sternum, i. e., about 3 inches from mid-sternum.] The impulse is more rarely 
felt in the fourth intercostal space, and it is much less distinct when the heart 
beats against the fifth rib itself. The position and force of the cardiac impulse 
vary with changes in the position of the body. [The term “apex-beat” is 
very loosely applied, but normally it is produced by the impulse of the apex 
of the left ventricle against the thoracic wall.] 
[The cardiac impulse is synchronous with the systole of the heart, but although this name 
and apex-beat are frequently used as synonymous terms, it is to be remembered that the 
impulse may be caused by different parts of the heart being in contact with the chest-wall. 
The cardiac impulse is usually higher than normal in children, while it is lower during inspira- 
tion than expiration.] 
Fig- 43- 
Cardiographs. A, Marey’s original form; B, Marey’s improved form ; C, pansphygmo- 
graph of Brondgeest; D, cardiograph of Burdon-Sanderson ; E, that of v. Knoll. 
[Methods.—To obtain a curve of the apex-beat or a cardiogram, we may use one or other 
of the following cardiographs (fig. 43). ■ Fig. 43, A, is the first form used by Marey, and it con- 
sists of an oval wooden capsule applied in an air-tight manner over the apex-beat. The disc, /, 
capable of being regulated by the screw, s, presses upon the region of the apex-beat, while t is a 
tube which may be connected with a recording tambour (fig. 55). B is an improved form of 
the instrument, consisting essentially of a tambour, while attached to the membrane is a button, 
p, to be applied over the apex-beat. The movements of the air within the capsule are com- 
municated by the tube, t, to a recording tambour. Fig. 43, C, is the pansphygmograph of 
Brondgeest, which consists of a Marey’s tambour, in an iron horse-shoe frame, and adjustable 
by means of a screw, s. Burdon-Sanderson’s cardiograph is shown in D. The button,/, carried 
by the spring, e, does not rest upon the caoutchouc membrane, but on an aluminium plate 
attached to it. The apparatus is adjusted to the chest by three supports. Fig. 43, E, shows CARDIAC IMPULSE. 
[Sec. 50. 
a modified instrument on the same principle by Grummach and v. Knoll. In all these 
figures the t indicates the exit-tube communicating with a recording tambour (fig. 55). D and 
E may be used for other 
purposes, e.g., for the 
pulse, so that they are 
polygraphs. See also 
fig. 88.] 
[ For studying the 
curve of contraction and 
expansion of the ventri- 
cles Roy and Adami 
used a special myo- 
cardiograph. Fine 
hooks were inserted into 
the ventricular wall, the 
hooks were attached to 
threads which hooked 
over pulleys and were 
then connected with recording levers. To 
obtain tracings of the contraction of the 
papillary muscles a fine hooked wire 
was inserted through the auricular wall 
and hooked over one of the mitral flaps. 
It slides easily in a collar which is tied to 
the edges of the opening in the auricular 
wall. To the wire is attached a thread, 
which, after passing round a pulley, is 
attached to a recording lever.] 
Fig. 47, A, shows the cardio- 
gram or the impulse-curve of the 
heart of a healthy man ; B, that 
of a dog, obtained by means of a 
sphygmograph. In both, the fol- 
lowing points are to be noticed : 
ab, corresponds to the time of the 
pause and the contraction of the auricles. As 
the atria contract in the direction of the axis 
of the heart from the right and above towards 
the left and below, the apex of the heart moves 
towards the intercostal space. The two or 
three smaller elevations are perhaps caused by 
the contractions of the ends of the veins, the 
auricular appendices, and the atria themselves. 
The portion be, which communicates the 
greatest impulse to the instrument, and also to 
one’s hand when it is placed on the apex-beat, 
is caused by the contraction of the ventricles, 
and during it the first sound of the heart occurs. 
By some observers the cardiac impulse has been 
ascribed to. the contraction of the ventricles 
alone. It, however, is due to all those con- 
ditions which cause an elevation in the region 
of the cardiac impulse. 
[Edgren recorded a human cardiogram, and listened 
at the same time to the heart-sounds, recording the latter 
by means of an electric signal. The curve rises at a, 
with the beginning of the first sound, i. e., with the contraction of the ventricles, and reaches the 
abscissa at the beginning of the second sound, i.e., when the semi-lunar valves are closed. 
The relation between a and the points intermediate between it and f\ and to the pulse-curve of 
Fig. 44. 
Cardiogram. a-f\ 1, beginning of 1st, and 2, 2d sound, 
The upper curve from the human carotid ; the lower 
a cardiogram taken simultaneously. 
Fig. 45- 
Cardiogram of dog, showing the various 
points of a cardiogram to which 
different observers have referred the 
occurrence of the second sound 
(closure of the semi-lunar valves). 
Fig. 46. Sec. 50.] 
CARDIAC IMPULSE. 
73 
the carotid, is shown in fig. 45. The letters with the dash correspond to the unmarked letters in 
the cardiogram.] 
[While all observers are agreed as to the position of the occurrence of the first sound in a 
cardiogram, they differ very considerably as to the position of the second sound, i.e., the closure 
of the semi-lunar valves (fig. 46). Martius places it in the depression between c and d(fig. 47, E); 
Landojs at the two projections d and e, d corresponding to the closure of the aortic, and e to that 
of the pulmonary valves; Marey and Fredericq about the middle between e and f and Edgren at 
the point f. According to Landois, the part be (fig. 47, A) is due to the contraction of the 
ventricles, and from c onwards the ventricular musculature begins to relax and lasts from e to f 
It is plain from the diagram that according to Landois the closure of the semi-lunar valves takes 
place earlier (at d and e) than according to Marey is the case. Fredericq has recently re-investi- 
the subject on the dog’s heart, and agrees with Marey that the closure of the semi-lunar 
valves takes place at e. See also fig. 46.] 
Fig. 47- 
Curves from the apex-beat. A, normal curve (man) ; B, from a dog, C, very rapid curve 
(dog); D and E, normal curves (man) registered on a vibrating glass plate where each 
indentation = 0.01613 sec. In all the curves ab means contraction of the auricles, and 
be of the ventricles; d, closure of the aortic, and e, of the pulmonary valves; ef, diastole 
of the ventricle. 
The cause of the cardiac impulse has been much discussed. It depends 
upon the following :— 
(i) The base of the heart (auriculo-ventricular groove) represents during 
diastole a transversely-placed ellipse (fig. 48, I, FG), while during contraction 
it has a more circular figure, ab. Thus, the long diameter of the ellipse (FG) 
is diminished, the small diameter dc is increased, while the base is brought 
nearer to the chest-wall e. This alone does not cause the impulse, but the basis 
of the heart, being hardened during the systole and brought nearer to the 
chest-wall, allows the apex to execute the movement which causes the impulse 
(P- 70- 74 
CARDIAC IMPULSE. 
[Sec. 50. 
(2) Daring relaxation the ventricle lies with its apex (fig. 48, II, /) 
obliquely downwards, and with its long axis in an oblique direction—so that 
the angles (bci, aci) formed by the axis of the ventricles with the diameter of 
the base are unequal—during systole it represents a regular cone, with its axis 
at right angles to its base. Hence the apex (z) must be erected from below 
and behind (/), forwards and upwards (.Harvey—“cor sese erigere ”), and 
when hardened during systole presses itself into the intercostal space (fig. 
43, II). 
(3) The ventricles undergo during systole a slight spiral twisting on their 
long axis (“ lateralem inclinationem ”—Harvey), so that the apex is brought 
from behind more forward, and thus a greater portion of the left ventricle is 
turned to the front. This rotation is caused 
by the muscular fibres of the ventricles, 
which proceed from that part of the fibrous 
rings between the auricles and ventricles 
which lies next the anterior thoracic wall. 
The fibres pass from above obliquely down- 
wards, and to the left, and also run in part 
I. 
II. 
I. Schematic horizontal section through the heart, lungs, and thorax, to show the change of 
shape which the base of the heart undergoes during contraction of the ventricle—F, G, 
transverse diameter of the ventricle during diastole; c, position of the thoracic wall; a, b, 
transverse diameter of the heart during systole, with e, position of the anterior thoracic 
wall during systole. II. Side-view of the heart—i,apex during diastole; p, during systole. 
Fig. 48. 
upon the posterior surface of the ventricles. When they contract in the axis 
of their direction, they tend to raise the apex, and also to bring more of the 
posterior surface of the heart in relation with the anterior thoracic wall. It is 
favored by the slightly spiral arrangement of the aorta and pulmonary artery. 
These are the most important causes, but the minor causes are— 
(4) The “ reaction impulse" or “ recoil," or that movement which the ven- 
tricles are said to undergo (like an exploded gun or rocket) at the moment 
when the blood is discharged into the aorta and pulmonary artery, whereby the 
apex goes in the opposite direction, i. e., downwards and slightly outwards. 
Landois, however, has shown that the mass of blood is discharged into the 
vessels 0.08 of a second after the beginning of a systole, while the cardiac 
impulse occurs with the first sound. Sec. 50.] 
CARDIOGRAM AND INTRA-VENTRICULAR PRESSURE. 
(5) When the blood is discharged into the aorta and pulmonary artery, these 
vessels are slightly elongated, owing to the increased blood-pressure. As the 
heart is suspended from above by these vessels, the apex is pressed slightly 
downwards and forwards towards the intercostal space (?). 
As the cardiac impulse is observed in the empty hearts of dead animals, (4) and (5) are cer- 
tainly of only second-rate importance. Filehne and Pentzoldt maintain that the apex during 
systole does not move to the left and downwards, as must be the case in (4) and (5), but that it 
moves upward and to the right—a result corroborated by v. Ziemssen. [Barr attributes the cause 
of the impulse to the rigidity or hardening of the ventricle during systole to the rotary movement 
and lengthening downwards of the blood column in the aorta and pulmonary artery, while 
towards the end of the systole the maximum of recoil takes place and also contributes to cause it.] 
It is to be remembered that as the apex is always applied to the chest-wall, separated from it 
merely by the thin margin of the lung, it only presses against the intercostal space during systole 
(.Kiivisch). 
After the apex of the curve, c, has been reached at the end of the systole, the 
curve falls rapidly, as the ventricles quickly become relaxed. In the descend- 
ing part of the curve, at d and e, are two elevations, which occur simultaneously 
with the second sound. These are caused by the sudden closure of the semi- 
lunar valves, whereby an impulse is propagated through the axis of the ven- 
tricle to its apex, and thus causes a vibration of the intercostal space; d corre- 
sponds to the closure of the aortic valves, and e to the closure of the pulmonary 
valves. The closure of the valves in these two vessels is not simultaneous, but 
is separated by an interval of 0.05 to 0.09 sec. The aortic valves close sooner 
on account of the greater blood-pressure there. Complete diastolic relaxation 
of the ventricle occurs from e to f in the curve. 
It is clear, then, that the cardiac impulse is caused chiefly by the contraction 
of the ventricles, while the auricular systole and the vibration caused by the 
closure of the semi-lunar valves are also concerned in its production. 
[Fig. 49 (1) shows a cardiogram obtained from a case of ectopia cordis, and 
side by side with it is (2) a tracing from the heart of a cat, which was obtained 
by resting a light lever 
on the anterior wall of 
the left ventricle, the 
organ being exposed by 
making a hole in the 
thorax. The two curves 
are identical in charac- 
ter. In each a rounded 
wave (a to F) is followed 
by a rapid ascent of the 
curve (b toF), while the 
summit or plateau shows 
a notch (//), and a more 
or less rounded shoulder 
(e) preceding the de- 
scent. The part of the 
curve between b and e 
corresponds to the con- 
traction of the ventri- 
cle, and from 
to its relaxation.] 
[Some light is thrown 
on the cardiogram if 
simultaneously with the taking of a cardiographic tracing the intra-ventricular 
pressure be measured. Rolleston’s method (p. 76), fig. 50 (A) shows such a 
1. Cardiographic tracing from a case of ectopia cordis (.Francois 
Franck). 2. Cardiographic tracing from the exposed heart of 
a cat, obtained by placing a light lever on the ventricle. The 
tuning-fork curve marks 50 vibrations per sec. 
Fig. 49. 76 
CHANGES IN SHAPE OF HEART. 
[Sec. 50. 
tracing. A shows the changes in the antero-posterior diameter of the ven- 
tricles, but it is to be noted that the highest point of A does not correspond with 
the maximum pressure within the ventricle, but that the latter occurs at the same 
time as the notch (4) of A. The notch (4) in A corresponds in time with the 
interposed wave (4) of B. The descent in A from 3-4 is due to the ventricles 
having reached their maximum of contraction, and forcing out some blood into 
the aorta and pulmonary artery, so that their antero-posterior diameter neces- 
sarily diminishes. What is the cause of the notch at the moment of maximum 
intra-ventricular pressure ? It corresponds in time with the rapid contraction 
of the papillary muscles, which thus pull down the auriculo-ventricular valves, 
thus raising the intra-ventricular pressure ; 
but at the same time the part of the ventri- 
cular wall from which the papillary muscles 
originate becomes indented {Roy and 
Adami ).] 
[Change in Shape of Heart.—The 
experiments of Ludwig and Hesse on the 
heart of the dog show that the shape of the 
ventricles varies remarkably in systole and 
diastole, and that the shape of the heart as 
found post-mortem is not its natural shape. 
Broadly speaking, the ventricles during 
systole become tense and resisting and they 
are smaller than during diastole, the differ- 
ence being equal to the amount of blood 
expelled at systole. As regards form, they 
change from a somewhat hemispherical 
figure with an irregular elliptical base, and 
assume a more regular cone-like form with 
a circular base, so that the transverse diame- 
ter is diminished, the antero-posterior 
diameter increased.] 
[Method.—Bleed a dog rapidly from the carotids, 
defibiinate the blood, expose the heart, tie graduated 
straight tubes into the pulmonary artery and aorta, 
and ligature the auricular vessels. Pour the blood 
into the heart until it is dilated under a pressure 
equal to the mean arterial pressure (150 mm.). The 
ventricles are in the diastolic phase, the auricles still 
pulsate. A plaster cast is now rapidly made of the 
ventricles. This represents the diastolic phase. To 
obtain what may be regarded as the systolic phase, 
a heart, similarly prepared but emptied of blood, is 
suddenly plunged into a hot (50° C.) saturated solu- 
tion of potassic bichromate, when the heart gives one 
rapid and final contraction and remains permanently 
contracted owing to the heat-rigor, its proteids being 
coagulated (g 295). This is the systolic phase. 
Little pins with twisted points are previously inserted 
in the organ to mark certain parts of both hearts for 
comparison.] 
[In diastole, the shape of the ventricle is hemispheroidal, the apex being 
rounded, while the posterior surface is flatter than the anterior (fig. 51, A). 
In the plane of the ventricular base, the greatest diameter is from right to left, 
and the shortest from base to apex. The conus arteriosus is above the plane of 
the base. During systole the apex is more pointed, the ventricle more 
A, Cardiogram of the apex-beat (dog); 
B, intra-ventricular pressure taken simul- 
taneously. The corresponding parts of 
the two curves are indicated by letters. 
Dg. 50. Sec. 50.] 
TIME FOR CARDIAC MOVEMENTS. 
77 
conical, while all the diameters in the plane of the base are equally diminished, 
hence the vertical measurement from base to apex is longer now than either of 
the diameters at the base (fig. 51, C). The conus arteriosus sinks towards the 
plane of the base, while the base of the ventricle becomes more circular, so 
that the difference of the curvatures of the anterior and posterior surfaces 
vanishes (fig. 51, B). In all these figures the shaded part represents diastole and 
the clear part systole. The most remarkable point is that the vertical measure- 
ment remains unchanged. This refers to the left ventricle, which of course forms 
the apex; the right is shortened. The plane of the ventricular base in systole is 
about one-half of what it is in diastole, as is shown in fig. 52. Thus the heart 
Fig. 51- 
A, Projection of a dog’s heart—posterior surface; B, anterior surface; C, left lateral surface. 
is. diminished in all its diameters except one, the arterial orifices are scarcely 
affected, while the area of the auriculo-ventricular orifices (M, T) is diminished 
about one-half (fig. 53). This is most important in connecti&n with the 
closure of the auriculo-ventricular valves; as it shows that the muscular fibres 
of the heart, by diminishing these orifices during systole, greatly aid in the 
perfect closure of these valves. Thus we explain why defective nutrition of the 
cardiac muscle may give rise to incompetency of these valves, without the 
valves themselves being diseased 
(Maca/ister). ] 
[In order to account for the 
vertical diameter remaining un- 
changed, we may represent the 
ventricular fibres as consisting of 
three layers, viz., an inner and 
outer set, more or less longitudinal, 
and a middle set, circular. Both 
sets will tend, when they contract, 
to diminish the cavity, but the 
shortening of the longitudinal 
layers is compensated for by the 
contraction, i.e., the elongation 
produced by the circular set.] 
[In order to obtain the shape of the cavities, dogs were taken of the same litter and as 
nearly alike as possible. One heart was filled with blood, as already described, and placed in a 
cool solution of potassic bichromate, whereby it was slowly hardened in the diastolic form, while 
the other was plunged as before into a hot solution. Casts were then made of the cavities.] 
51. THE TIME OF THE CARDIAC MOVEMENTS.—Methods.—The time 
occupied by the various phases of the movements of the heart may be determined by studying 
the apex-beat curve. 
(1) If we know at what rate the plate on which the curve was obtained moved during the ex- 
periment, of course all that is necessary is to measure the distance, and so calculate the time 
occupied by any event (see Pulse, § 67). 
(2) It is preferable, however, to cause a tuning-fork, whose rate of vibration is known, to write 
Fig. 52- 
Fig- 53- 
Projection of the base in 
systole and diastole; RV, 
right, and LV, left ven- 
tricle. 
A, aorta; PA, pulmonary 
artery; M, mitral, and 
T tricuspid orifice. TiME FOR CARDIAC MOVEMENTS. 
[Sec. 51- 
its vibrations under the curve of the apex-beat (fig. 49, 2), or the curve may be written upon a 
plate attached to a vibrating tuning-fork (fig. 47, D, E). Such a curve contains fine teeth caused 
by the vibrations of the tuning-fork. D and E are curves obtained from the cardiac impulse in 
this way from healthy students. In D the notch d is not indicated. Each complete vibration or 
the tuning-fork, reckoned from apex to apex of the teeth =0.01613 second, so that it is simply 
necessary to count the number of teeth and multiply to obtain the time. The values obtained 
vary within certain limits even in health. 
The value of a b = pause -f contraction of the auricles, is subject to the 
greatest variation, and depends chiefly upon the number of heart-beats per 
minute. The more quickly the heart beats, the shorter is the pause, and con- 
versely. In some curves, even when the heart beats slowly, it is scarcely pos- 
sible to distinguish the auricular contraction (indicated by a rise) from the part 
of the curve corresponding to the pause (indicated by a horizontal line). In 
one case (heart-beats 55 per minute) the pause = 0.4 second, the auricular con- 
traction = 0.177 second. In fig. 47, A, the time occupied by the pause -j- the 
auricular contraction (74 beats per minute) = 0.5 second. In D, a b = 19 to 
20 vibrations = 0.32 second; in E = 26 vibrations = 0.42 second. 
The ventricular systole is calculated from the beginning of the contrac- 
tion b, to e, when the semi-lunar valves are closed; it lasts from the first to the 
second sound. It also varies somewhat, but is more constant. When the 
heart beats rapidly, it is somewhat shorter—during slow action longer. 
In £ = 0.32 second; in D = o.29 second ; with 55 beats per minute Landois 
found it =0.34, with a very high rate of beating = 0.199 second. 
Fig- 54- 
Curves recorded by the ventricle of a rabbit upon a vibrating plate attached to a tuning-fork 
(vibration =0.01613 sec.). A, soon after death; B, from the dying ventricle. 
When the ventricles beat feebly, they contract more slowly, as can be shown by applying the 
registering apparatus to the heart of an animal just killed. In fig. 54> from the ventricle of a 
rabbit just killed, the slow heart-beats, B, are seen to last longest. In cases of enormous 
hypertrophy and dilatation of the left ventricle, the duration of the ventricular systole is not 
longer than normal (Landois). 
In calculating the time occupied by the ventricular systole we must remember—(i) The time 
between the two sounds of the heart, i. <?., from the beginning of the first to the end of the second 
sound (b to if). (2) The time the blood flows into the aorta, which comes to an end at the 
depression between c and d (in fig. 47, E). Its commencement, however, does not coincide with 
b, as the aortic valves open 0.085 t° °-°73 second after the beginning of the ventricular systole. 
Hence the aortic current lasts 0.08 to 0.09 second. This is calculated in the following way : 
The time between the first sound of the heart and the pulse in the axillary artery is 0.137 
second, and of this time 0.052 second is occupied in the propagation of the pulse-wave along the 
30 cm. of artery lying between the root of the aorta and the axilla. Thus the pulse-wave in 
the aorta occurs 0.137 minus 0.052 — 0.085 second after the beginning of the first sound. The 
current in the pulmonary artery is interrupted in the depression between d and e. (3) Lastly, 
the time occupied by the muscular contraction of the ventricle, which begins at b, reaches its 
greatest extent at c, and is completely relaxed at f. The apex of the curve, c, may be higher or 
lower according to the flexibility of the intercostal space, hence the position of c varies. In 
hypertrophy with dilatation of the left ventricle, the duration of the ventricular contraction does 
not greatly exceed the normal. 
The time which elapses between d and e—i. e., between the complete closure 
of the aortic and pulmonary valves—is greater the more the pressure in the Sec. 51.] 
ENDOCARDIAL PRESSURE. 
79 
aorta exceeds that in the pulmonary artery, as the valves are closed by the pres- 
sure from above, and the difference in time may be 0.05 second, or even double 
that time, in which case the second sound appears double (compare § 54). If 
the aortic pressure diminishes while that in the pulmonary artery rises, d and e 
may be so near each other that they are no longer marked as distinct elements 
in the curve. 
The time, ef. during which the ventricles relax varies somewhat: 0.1 second 
may be taken as a mean. 
Accelerated Cardiac Action.—When the action of the heart is greatly accelerated, the pause 
is considerably shortened in the first instance (Bonders), and to a less extent the time of con- 
traction of the auricles and ventricles. When the pulse-rate is very rapid, the systole of the 
atria coincides with the closure of the arterial valves of the preceding contraction, as is shown 
in fig. 47, C. (dog). 
In registering the cardiac impulse, the apparatus is separated by a greater or less depth of 
soft parts from the heart itself, so that in all cases the intercostal tissues do not follow exactly 
the movements of the heart, and thus the curve obtained may not coincide mathematically with 
the movements of the heart. It is desirable that curves be obtained from persons whose hearts 
are exposed, r.e., in cases of ectopia cordis (fig. 49, 1). 
Cleft Sternum.—Gibson inscribed cardiograms from the heart of a man with cleft sternum. 
The following were the results obtained: Auricular contraction — o. 115 ; ventricular contrac- 
tion (b, d) =0.028; difference between closure of valves (d, e) = 0.09; ventricular diastole 
(<?,/) = o. 11 ; pause _ 0.45 second (§ 48). 
Fig- 55- 
A. Marey’s registering tambour. 7, metallic capsule, with thin india-rubber stretched over it and 
bearing an aluminium disc, which acts upon the writing lever, H. By means of a thick- 
walled caoutchouc tube, it may be connected with any system containing air, so as to record 
variations of pressure. B. Natural size of the tambour, T. 
Endocardial Pressure.—In large mammals, such as the horse, Chauveau 
and Marey (1861) determined the duration of the events that occur within the 
heart, and also the endocardial pressure, by means of a cardiac sound (fig. 
56). Small elastic bags attached to tubes were introduced through the jugular 
vein into the right auricle and ventricle. 'Each of these tubes was connected 
with a registering tambour (fig. 55), and simultaneous tracings of the variations 
of pressure within the cavities of the heart were obtained by causing the writing- 
points of the levers of the tambours to write upon a revolving cylinder. [This 
method is better adapted for showing the sequence of events than for measuring 
the actual endocardial pressure during the several phases of a cardiac cycle.] 
[Marey’s Cardiac Sound.—The sound (fig. 56, upper fig.) was introduced through the 
jugular vein into the heart until the elastic ampulla V, covered with thin india-rubber, came to 
be in the right ventricle, and O in the right auricle. The middle figure shows a section of the 
upper one, and how the ampulla V was connected to a tambour by means of the tube TV, and 
the ball O to another similar tambour by the tube TO.] 80 
[Sec. 51. 
ENDOCARDIAL PRESSURE. 
Fig. 57, A, gives the result obtained when one elastic bag was placed in the right auricle, 
being introduced through the jugular vein and superior vena cava; B, when the other bag 
pushed through the tricuspid orifice was in the right ventricle; D, in the root of the aorta, pushed 
in through the carotid; C, pushed past the semi lunar valves into the left ventricle; while at 
E a similar bag has been placed externally between the heart’s apex and the inner wall of the 
chest. In all cases v— auricular contraction ; V, that of the ventricle ; s, closure of semi-lunar 
valves, sooner in C than B; P = pause. 
Methods.—(i) The cardiac sound consists of a tube containing two separate air-passages, 
and in connection with each of these there is a small elastic bag or ampulla. One of the bags is 
fixed to the free end ofthe sound, and communicates with one of the air-passages (fig. 56). The 
other bag is placed in connection with the second air-passage in the sound, and at such a distance 
that when the former bag lies within the ventricle, the latter is in the auricle. Each bag and 
air tube communicating with it is connected with a Marey’s tambour (fig. 55), provided with a 
lever which inscribes its movements upon a revolving cylinder. Any variation of pressure within 
the auricle or ventricle will affect the elastic ampullae, and thus raise or depress the lever. Care 
must be taken that the writing points of the levers are placed exactly above each other. A trac- 
ing of the cardiac impulse is taken simultaneously by means of a cardiograph attached to a 
separate tambour. 
It has still to be determined whether the auricles and ventricles act alternately, 
so that at the moment of the beginning of the ventricular contraction the 
The upper and middle diagrams represent Marey’s sound, the middle figure showing a section of 
the upper one. The lowest (a) is a simple cardiac sound. The bulbous portion is covered 
with thin india-rubber stretched over an open metallic framework so as to form an elastic 
bag or ampulla. By means of the tube it can be introduced into cavity. 
Fig. 56. 
auricles relax, or whether the ventricles are contracted while the auricles still 
remain slightly contracted, so that the whole heart is contracted for a short 
time at least. The latter view was supported by Harvey, Donders, and others, 
while Haller and many of the more recent observers support the view that the 
action of the auricles and ventricles alternates. In the case of Frau Serafin, 
whose heart was exposed, v. Ziemssen obtained curves from the auricles, which 
showed that the contraction of the auricles continued even after the commence- 
ment of the ventricular systole. In Marey’s curve the contraction of the ven- 
tricle is represented as following that of the auricle (fig. 57). 
(2) [The pressure within the heart has also been measured by means of the 
maximum and minimum manometer (p. 69). In the dog the maximum 
positive pressure in the left ventricle is during systole greater than that in the 
aorta, and may reach 140 mm. Hg—that in the right ventricle 60 mm., and the 
right auricle about 20 mm. Hg. The minimum manometer, however, during 
the diastole of the ventricles records a negative pressure of -52 to -20 mm. 
Hg in the left and -16 mm. in the right ventricle, and -7 mm. in the right 
auricle. Sec. 51.] 
ENDOCARDIAL PRESSURE. 
81 
Even after the chest is opened, the negative pressure in the left ventricle may 
fall as low as -25 mm. Hg.] 
[(3) Method of Rolleston and Roy.—These observers used a special apparatus which was 
connected with the interior of the heart, and they find that there is no distinct rise of pressure in 
the dog within the ventricles corresponding to the auricular systole such as was obtained by 
Marey in the horse. During the ventricular diastole in certain cases the pressure falls below the 
atmospheric pressure and may be equal to -20 mm. mercury or more in the left ventricle ($ 48). 
It is probably caused by the elastic expansion of the ventricle continuing after the blood in the 
auricle at the moment of the cessation of the ventricular systole has entered the ventricle—i. e., 
- Right Auricle. 
Right Ventricle. 
Left Ventricle. 
- Aorta. 
Cardiac Impulse 
Curves obtained from the heart of a horse by the cardiac sound. 
Fig- 57- 
the quantity of blood in the auricle is not sufficient in all cases to distend the left ventricle to the 
point at which its suction action ceases. Magini, operating on dogs with a trocar which per- 
forated the cavities of the heart, found none of the secondary elevations obtained by Marey with 
his sound. There is considerable difficulty in interpreting the curves obtained (fig. 50, B).] 
A. Fick regards the alternating contraction as a means whereby the pressure in the large 
venous trunks is kept nearly constant. At the moment of ventricular systole the auricles 
relax, and the venous blood flows freely into the latter, while if the auricles remained contracted, 
the blood in the veins would be kept back. Further, at the moment of ventricular diastole 
the auricles contract, so that there is not an abnormal diminution of the pressure in the veins. 
Thus the pressure in the auricle is more equable, while the current in the terminal parts of the 
veins is kept more constant. 82 
PATHOLOGICAL CARDIAC IMPULSES. 
[Sec. 52. 
52. PATHOLOGICAL CARDIAC IMPULSES.—Change in the Position of the 
Apex-Beat.—The position of the cardiac impulse is changed—(i) by the accumulation of 
fluids (serum, pus, blood) or gas in one pleural cavity. A copious effusion into the left pleural 
cavity compresses the lung, and may displace the heart towards the right side, while effusion on 
the right side may push the heart more to the left. As the right heart must make a greater effort 
to propel the blood through the compressed lung, the cardiac impulse is usually increased. 
Advanced emphysema of the lung, causing the diaphragm to be pressed downwards, displaces 
the heart downwards and inwards, while pushing and pulling up of the diaphragm (by con- 
traction of the lung, or through pressure from below) causes the apex-beat to be displaced 
upwards, and also slightly to the left. Thickening of the muscular walls with dilatation of the 
cavities of the left ventricle makes that ventricle longer and broader, while the increased cardiac 
impulse may be felt in the axillary line in the sixth, seventh, or even eighth intercostal 
space to the left of the mammary line. Hypertrophy, with dilatation of the right side, 
increases the breadth of the heart, so that the cardiac impulse is felt more to the right, even 
to the right of the sternum. In the rare cases where the heart is transposed, the apex- 
beat is felt on the right side. When the cardiac impulse goes to the left of the left mammary 
line, or to the right of the parasternal line, the heart is increased in breadth, and there is 
hypertrophy of the heart. A greatly increased cardiac impulse may extend to several inter- 
costal spaces. 
The cardiac impulse is abnormally weakened in cases of atrophy and degeneration of the 
cardiac muscle, or by weakening of the innervation of the cardiac ganglia. It is also weakened, 
when the heart is separated from the chest-wall owing to the collection of fluids or air in the 
pericardium, or by a greatly distended left lung; and, indeed, when the left side of the chest is 
filled with fluid, the cardiac impulse may be extinguished. The same occurs when the left ven- 
tricle is very imperfectly filled during its contraction (in consequence of marked narrowing of 
the mitral orifice), or when it can only empty itself very slowly and gradually as during marked 
narrowing of the aortic orifice. 
An increase of the cardiac impulse occurs during hypertrophy of the walls, as well as under 
the influence of various stimuli (psychical, inflammatory, febrile, toxic) which affect the cardiac 
ganglia. Great hypertrophy of the left ventricle causes the heart to heave, so that a part of the- 
left chest-wall may be raised and also vibrate during systole. 
A pulling in of the anterior wall of the chest during the cardiac systole occurs in the third 
and fourth interspaces, not unfrequently under normal circumstances, sometimes during in- 
creased cardiac action, and in eccentric hypertrophy of the ventricles. As the heart’s apex is 
slightly displaced, and the ventricle becomes slightly smaller during its systole, the empty 
space is filled by the yielding soft parts of the intercostal space. When the heart is united 
with the pericardium and the surrounding connective-tissue, which renders systolic locomotion 
of the heart impossible, retraction of the chest-wall during systole takes the place of the 
cardiac impulse [Skoda). During the diastole, a diastolic cardiac impulse of the corresponding 
part of the chest-wall may be said to occur. 
Clinically, changes in the cardiac impulse are best ascertained by taking graphic representa- 
tions of the cardiac impulse, and studying the curves so obtained (fig. 58). 
In curve P (much reduced), from a case of marked hypertrophy with dilatation, the ven- 
tricular contraction, be, is usually very great, while the time occupied by the contraction is not 
much increased. P and Q were obtained from a case of marked eccentric hypertrophy of the 
left ventricle, due to insufficiency of the aortic valves. Curve Q was taken intentionally over 
the auriculo-ventricular groove, where retraction of the chest-wall occurred during systole; 
nevertheless the individual events occurring in the heart are indicated. 
Fig. E is from a case of aortic stenosis. The auricular contraction (ab) lasts only a short 
time; the ventricular systole is obviously lengthened, and after a short elevation (be) shows a 
series of fine indentations (c, e) caused by the blood being pressed through the narrowed and 
roughened aorta. 
Fig. F, from a case of insufficiency of the mitral valve, shows (ab) well marked on 
account of the increased activity of the left auricle, while the shock [d) from the closure of the 
aortic valves is small, on account of the diminished arterial tension. On the other hand, the 
shock from the accentuated pulmonary sound (e) is very great, and is in the apex of the curve. 
On account of the great tension in the pulmonary artery, the second pulmonary tone may be so 
strong, and succeed the second aortic sound (</) so rapidly, that both almost merge completely 
into each other (H and K). 
The curve of stenosis of the mitral orifice (G) shows a long, irregular, notched, auricular 
contraction [ab), caused by the blood being forced through an irregular narrow orifice. The ven- 
tricular contraction [be) is feeble because the ventricle is imperfectly filled. The closures of the 
two valves, d and e, are relatively far apart, and one can hear distinctly a reduplicated second 
sound. The aortic valves close rapidly, because the aorta is imperfectly supplied with blood,. Sec. 52.] 
PATHOLOGICAL CARDIAC IMPULSES. 
83 
while the more copious inflow of blood into the pulmonary artery causes its valves to close 
later. 
If the heart beats rapidly and feebly—if the blood-pressure in the aorta and pulmonary 
artery be low, the signs of closure of the pulmonary valves may be absent—as in curve L— 
taken from a girl suffering from nervous palpitation and morbus Basedowii. 
In very rare cases of insufficiency of the mitral valve, it has been observed that at certain 
times both ventricles contract simultaneously, as in a normal heart, but that this alternates 
with a condition where the right ventricle alone seems to contract. Curve M is such a curve 
obtained by Malbranc, who called this condition intermittent hemisystole. The first curve 
Fig. 58 
Curves of the cardiac impulse, ab, contraction of auricles; be, ventricular systole; d, closure 
of aortic, and e, of pulmonary valves; ef, diastole of ventricle; P, Q, hypertrophy and 
dilatation of the left ventricle; E, stenosis of the aortic orifice; F, mitral insufficiency; 
G, mitral stenosis; L, nervous palpitation in Basedow’s disease; M, so-called hemisystole. 
(I) is like a normal curve, during which the whole heart acted as usual. The curve II, how- 
ever, is caused by the right side of the heart alone; it wants the closure of the aortic valves d, 
and there was no pulse in the arteries. Owing to insufficiency of the tricuspid valve, the same 
person had a venous pulse with every cardiac impulse, so that the arterial and venous pulses 
first occurred together and then the venous pulse alone occurred. In these cases the mitral 
insufficiency leads to the right ventricle being over-distended, while the left is nearly empty, so 
that the right side requires to contract more energetically than the left. It does not seem that 
the right ventricle alone contracts in these cases, but rather that the action of the left side is 
very feeble. 84 
THE HEART-SOUNDS. 
[Sec. 53. 
53. THE HEART-SOUNDS.—On listening 
over the region of the heart in a healthy man, either 
with the ear applied directly to the chest-wall (Harvey), 
or by means of a stethoscope (.Laennec, 1819), we hear 
two characteristic sounds, the so-called “ heart- 
sounds.” The two sounds are called first and 
second, and together they correspond to a single cardiac 
cycle. These sounds are separated by silences. [Fig. 
59 shows the relation of the events occurring in the 
heart during a cardiac cycle to the sounds and silences.] 
1. The first sound. 
2. The first or short silence. 
3. The second sound. 
4. The second or long silence. 
[Relative Duration.—There is no absolute dura- 
tion of each phase of a cardiac cycle, but we may take 
the average relative duration calculated from the 
measurements of Gibson, in a case of fissure of the sternum, to be as follows: — 
Fig- 59- 
Scheme of a cardiac cycle. 
The inner circle shows 
what events occur in 
the heart, and the 
outer, the relation of 
the sounds and silences 
to these events. 
Auricular systole, 
Ventricular systole, 
368 “ 
Ventricular diastole, 
-578 “ 
Cardiac cycle, 
Suppose we divide the cycle into tenths ( Walshe), then the first sound will 
last the first silence the second sound T and the long silence of the 
entire period.] 
The first sound [long or systolic] is twice as long as, somewhat duller, and 
one-third or one-fourth deeper, than the second sound; it is less sharply 
defined at first, and is synchronous with the systole of the ventricles. 
The second sound [short or diastolic] is clearer, sharper, shorter, more 
sudden, and is one-third to one-fourth higher in pitch; it is sharply defined 
and synchronous with the closure of the semi-lunar valves. It marks the begin- 
ning of ventricular diastole. The sounds emitted during each cardiac cycle 
have been compared to the pronunciation of the syllables lubb, dupp. [If one 
listens over the apex one hears the sounds like lupp, dupp ; where the accent is 
on the first sound, but at the base, it is on the second sound, and is like lupp, 
dupp.~\ Or the result may be expressed thus:— 
[It is to be remembered that in reality four sounds are produced in the heart, 
but the two first sounds occur together and the two second, so that only a single 
first and a single second sound are heard.] 
The causes of the first sound are due to two conditions. As the sound 
is heard, although enfeebled, in an excised heart in which the movements of 
the valves are arrested, and also when the finger is introduced into theauriculo- 
ventricular orifices so as to prevent the closure of the valves (C. Ludwig and 
Dogiel), one of the factors lies in the “ muscle sound" produced by the con- 
tracting muscular fibres of the ventricles. This sound is supported and increased 
by the sound produced by the tension and vibration of the auriculo-ventricular Sec. 53.] 
CAUSES OF THE HEART-SOUNDS. 
85 
valves and their chordse tendineae, at the moment of the ventricular systole. 
Wintrich, by means of proper resonators, has analyzed the first sound and dis- 
tinguished the clear, short, valvular part from the deep, long, muscular sound. 
[Krehl has made additional experiments to show that the first sound is partly muscular. An 
apparatus was devised whereby, while the heart was still within the body and the circulation 
going on, modifications of the first sound were obtained when the auriculo-ventricular valves were 
held apart. Again, when a dog is bled from the carotids, as soon as a considerable amount of 
blood is removed, the second sound is no longer heard, while the first sound lasts for some time 
longer and is even fairly loud. It is also said that the auricles produce a sound during their 
contraction. Kasem-Beck has also recently confirmed Dogiel’s previous statements and sup- 
ported them by new experiments.] 
The muscle-sound produced by transversely-striped muscle does not occur with a simple con- 
traction (p. ioi), but only when several contractions are superposed to produce tetanus (§ 303). 
The ventricular contraction is only a simple contraction, but it lasts considerably longer than 
the contraction of other muscles, and herein lies the cause of the occurrence of the muscle-sound 
during the ventricular contraction. 
Defective Heart-Sounds.—In certain conditions (typhus, fatty degeneration of the heart), 
where the muscular substance of the heart is much weakened, the first sound may be completely 
inaudible. In aortic insufficiency, in consequence of the reflux of blood from the aorta into the 
ventricle, the mitral valve is gradually stretched, and sometimes even before the beginning of the 
ventricular systole, the first srund may be absent. Such pathological conditions seem to show 
that, for the production of the first sound, muscle-sound and valve-sound must eventually work 
together, and that the tone is altered, or may even disappear, when one of these causes is absent. 
[Yeo and Barrett state that the sound is purely muscular (?).] 
The cause of the second sound is undoubtedly due to the prompt 
closure, and therefore sudden stretching or tension, of the semi-lunar valves of 
the aorta and pulmonary artery, so that it is purely a valvular sound. Perhaps 
it is augmented by the sudden vibration of the fluid-particles in the large arterial 
trunks. [The second sound has all the characters of a valvular sound. That 
the aortic valves are concerned in its production was proved by Hope, who 
introduced a curved wire through the left carotid artery and hooked up one or 
more segments of the valve, when the sound was modified. It may even dis- 
appear or be replaced by an abnormal sound or “murmur.” Again, when 
these valves are diseased, the sound is altered, and it may be accompanied or 
even displaced by murmurs.] Although the aortic and pulmonary valves do 
not close simultaneously, usually the difference in time is so small that both 
valves make one sound, but the second sound may be double or divided when, 
through increase of the difference of pressure in the aorta and pulmonary artery, 
the interval becomes longer. Even in health this may be the case, as occurs at 
the end of inspiration or the beginning of expiration (y. Dusch). 
Where the Sounds are Heard Loudest.—[Clinicians, for convenience, 
in describing the cardiac sounds as heard on auscultation speak of four areas, 
viz.: the mitral area, a circular area about 2 inches in diameter, with the apex 
as a centre; the tricuspid area, from the third to the fifth interspaces on the 
left side, and the adjoining part of the sternum; the aortic area, second right 
interspace near the sternum, or the inner t nd of the second costal cartilage; the 
pulmonary area, the inner end of the second left intercostal space. The first 
sound is heard best at the apex, and much fainter at the base. The second sound 
is heard best over the base.] The sound produced by the triaispid valve is 
heard loudest at the junction of the lower right costal cartilages with the 
sternum; as the mitral valve lies more to the left and deeper in the chest, and 
is covered in front by the arterial orifice, the mitral sound is best heard at the 
apex-beat, or immediately above it, where a strip of the left ventricle lies next 
the chest-wall. [The sound is conducted to the part nearest the ear of the 
listener by the muscular substance of the heart.] The aortic and pulmonary 
orifices lie so close together that it is convenient to listen for the second (aortic) 
sound in the direction of the aorta, where it comes nearest to the surface, i. e., 86 
WHERE THE HEART-SOUNDS ARE HEARD LOUDEST. 
[Sec. 53. 
over the second right costal cartilage or aortic cartilage close to its junction 
with the sternum. The sound, although produced at the semi-lunar valves, is 
carried upwards by the column of blood, and by the walls of the aorta. The 
The heart—its several parts and great vessels in relation to the front of the thorax. The lungs 
are collapsed to their normal extent, as after death, exposing the heart. The outlines of 
the several parts of the heart are indicated by very fine dotted lines. The area of pro- 
pagation of valvular murmurs is marked out by more visible dotted lines. A, the circle of 
mitral murmur, corresponds to the left apex. The broad and somewhat diffused area, 
roughly triangular, is the region of tricuspid murmurs, and corresponds generally with the 
right ventricle, where it is least covered by lung. The letter C is in its centre. The cir- 
cumscribed circular area, D, is the part over which the pulmonic arterial murmurs are com- 
monly heard loudest. In many cases it is an inch, or even more, lower down, correspond- 
ing to the conus arteriosus of the right ventricle, where it touches the wall of the thorax. 
The internal organs and parts of organs are indicated by letters as follows:—r.au, right 
auricle, traced in fine dotting; ao, arch of aorta, seen in the first intercostal space, and 
traced in fine dotting on the sternum; v.i., the two innominate veins; r.v., right ventricle ; 
l.v., left ventricle. 
Fig. 60. 
sound produced by the pulmonary artery is heard most distinctly over the end 
of the second right intercostal space, or the third left costal cartilage, somewhat 
to the left and external to the margin of the sternum (fig. 60). Sec. 53.] 
VARIATIONS OF THE HEART-SOUNDS. 
87 
[It is important to remember that the position of the cardiac valves is one 
thing, and the situation where the heart-sounds are heard loudest is another. 
The following indicates the topographical arrangement of the orifices: — 
Aortic orifice.—At the sternum adjoining the third left cartilage and space. 
Pulmonary orifice.—Second left space and sternum adjoining. 
Mitral orifice.—Left half of sternum from fourth to fifth cartilage. 
Tricuspid orifice.—Right half of sternum from fourth to sixth cartilage. 
The aortic and mitral orifices are deeply situated in the chest, while the pul- 
monary and tricuspid orifices are comparatively superficial.] 
[Events occurring in the heart during the sounds.—Coincident with the 
first sound the following events are taking place within the heart: (i) Con- 
traction of both ventricles, (2) firmer closure and stretching of the auriculo- 
ventricular valves, (3) propulsion and rushing of blood into the aorta and 
pulmonary artery, (4) the impulse of the heart against the chest-wall, (5) the 
gradual filling of the auricles with blood. Coincident with the second sound 
are—(1) the closure and stretching of the semi-lunar valves of the aorta and 
pulmonary artery, (2) relaxation of the contracted ventricles, (3) opening of 
the auriculo-ventricular valves and flow of some blood from the auricles into 
the ventricles, (4) diminished pressure of the apex against the chest-wall. 
During the long pause : (1) The auricles are being filled, and blood flows 
freely from them into the dilated ventricles, (2) contraction of the auricles to 
fill the ventricles with blood.] During the short silence, which is very short, 
the ventricles are contracting, and are near their maximum of shortening. 
54. VARIATIONS OF THE HEART-SOUNDS.—Increase of the first sound of 
both ventricles indicates a more energetic contraction of the ventricles and a simultaneously 
greater and more sudden tension of the auriculo-ventricular valves. Increase of the second sound 
is a sign of increased tension in the interior of the corresponding large arteries. Hence increase 
of the second (pulmonary) sound indicates overfilling and excessive tension in the pulmonary 
circuit. A feeble action of the heart, as well as abnormal want of blood in the heart, causes 
weak heart-sounds, which is the case in degenerations of the heart-muscle. 
Irregularities in structure of the individual valves may cause the to become 
“ impure.” If a pathological cavity, filled with air, be so placed, and of such aTorm as to act 
as a resonator to the heart-sounds, they may assume a “ metallic ” character. The first and 
second sound may be “ reduplicated ” or [although “ duplication ” is a more accurate term 
{Barr)'] doubled. The reduplication of the first sound is explained by the tension of the 
tricuspid and that of the mitral valves not occurring simultaneously. Sometimes in disease a 
sound is produced by a hypertrophied auricle producing an audible presystolic sound, i. e., a 
sound or “murmur” preceding the first sound. [This has been questioned quite recently.] 
As the aortic and pulmonary valves do not close quite simultaneously, a reduplicated secondsotmd 
is only an increase of a physiological condition. All conditions which cause the aortic valves to 
close rapidly (diminished amount of blood in the left ventricle) and the pulmonary valves to 
elose later (congestion of the right ventricle—both conditions together in mitral stenosis), favor 
the production of a reduplicated second sound. 
Cardiac Murmurs.—If irregularities occur in the valves, either in cases of stenosis or in 
insufficiency, so that the blood is subjected to vibratory oscillations and friction, then, instead 
of the heart-sounds, other sounds—murmurs or bruits—arise or accompany these. A com- 
bination of these sounds is always accompanied by disturbances of the circulation. [These 
murmurs may be produced within the heart, when they are termed endocardial; or outside it, 
when they are called exocardial murmurs. But other murmurs are due to changes in the 
quality or amount of the blood, when they are spoken of as haemic murmurs. In the study of 
all murmurs, note their rhythtn or exact relation to the normal sounds, their point of maximum 
intensity, and the direction in zvhich the murmur is propagated. ] It is rare that tumors or other 
deposits projecting into the ventricles cause murmurs, unless there be present at the same time 
lesions of the valves and disturbances of the circulation. The cardiac murmurs are always re- 
lated to the systole or diastole, and usually the systolic are more accentuated and louder. 
Sometimes they are so loud that the thorax trembles under their irregular oscillations {fremitus, 
fremissement cataire). 
In cases where diastolic murmurs are heard, there are always anatomical changes in the 
cardiac mechanism. These are insufficiency of the arterial valves, or stenosis of the auriculo- 
ventricular orifice (usually the left). Systolic murmurs do not always necessitate a disturb- 
ance in the cardiac mechanism. They may occur on the left side, owing to insufficiency of the 88 
PERSISTENCE OF HEART MOVEMENTS. 
[Sec. 54. 
mitral valve, stenosis of the aorta,* and in cases of calcification and dilatation of the ascending 
part of the aorta. These murmurs occur very much less frequently on the right side, and are 
due to insufficiency of the tricuspid and stenosis of the pulmonary orifice. 
Functional Murmurs.—Systolic murmurs often occur without any valvular lesion, although 
they are always less loud, and are caused by abnormal vibrations of the valves or arterial 
walls. They occur most frequently at the orifice of the pulmonary artery [and are generally 
heard at the base], less frequently at the mitral, and still less frequently at the aortic or 
the tricuspid orifice. Anaemia, general malnutrition, acute febrile affections, are the causes of 
these murmurs. [Some of these are due to an altered condition of the blood, and are called 
haemic, and others to defective cardiac muscular nutrition, and are called dynamic (Walshe').~\ 
Sounds may also occur during a certain stage of inflammation of the pericardium (pericarditis) 
from the roughened surfaces of this membrane rubbing upon each other. Audible friction sounds 
are thus produced, and the vibration may even be perceptible to touch. [These are “ friction 
sounds,” and quite distinct from sounds produced within the heart itself.] 
55. PERSISTENCE OF THE MOVEMENTS OF THE 
HEART.—The heart continues to beat for some time after it is cutout of the 
body. The movement lasts longer in cold-blooded animals (frog, turtle)— 
extending even to days—than in mammals. A rabbit’s heart beats from 3 
minutes up to 36 minutes after it is cut out of the body. The average of many 
experiments is about 11 minutes. [Waller and Reid recorded the ventricular 
contractions of a rabbit’s heart 72 minutes after its excision. Fig. 61 shows 
the prolongation of the ventricular systole in an excised rabbit’s heart, the 
movements being recorded by a lever resting on the heart.] Panum found the 
last trace of contraction to occur in the right auricle (rabbit) 15 hours after 
death; in a mouse’s heart, 46 hours; in a dog’s, 96 hours. An excised frog’s 
heart beats, at the longest, 2)4 days (Valentin). In a human embryo (third 
month) the heart was found beating after 4 hours. In this condition stimulation 
causes an increase and acceleration of the action. The ventricular contraction 
weakens, and soon each auricular contraction is not followed by a ventricular 
contraction, two or more of the former being succeeded by only one of the 
latter. At the same time the ventricles contract more slowly (fig. 61), and 
soon stop altogether, while the auricles continue to beat. If the ventricles be 
stimulated directly, as by pricking them with a pin, they may execute a con- 
traction. The left auricle soon ceases to beat, while the right auricle still con- 
tinues to contract. The right auricular appendix continues to beat longest, as 
was observed by Galen and Cardanus (1550), and it is termed “ ultimum 
moriens.” Similar observations have been made upon the hearts of persons 
who have been executed. 
If the heart has ceased to beat, it may be excited to contract for a short time 
by direct stimulation, more especially by heat (Harvey); even under these 
circumstances the auricles and their appendices are the last parts to cease con- 
tracting. As a general rule, direct stimulation, although it may cause the 
heart to act more vigorously for a short 
time, brings it to rest sooner. In such 
cases, therefore, the regular sequence of 
events ceases, and there is usually a 
twitching movement of the muscular 
fibres of the heart. C. Ludwig found 
that, even after the excitability is ex- 
tinguished in the mammalian heart, it 
may be restored by injecting arterial 
blood into the coronary arteries: con- 
versely, lesion of these vessels is followed 
by enfeebled action of the heart (§ 47). 
Hammer found that in a man, whose 
left coronary artery was plugged, the 
pulse fell from 80 to 8 beats per minute. 
Fig. 61. 
Curves of excised rabbit’s heart—I, 6 mins, 
after excision; 2, io mins.; 3, 20 mins.; 4, 
70 mins, (after Waller and Reid). Sec. 55.] 
PHYSICAL EXAMINATION OF HEART. 
89 
[The beats of the excised heart of a rabbit gradually decline in force and frequency, the latent 
period and contraction become longer, and the excitability more obtuse. The duration of a 
contraction may be .6 sec., the normal being .3 sec. The beats have often a bigeminal character. 
An excised heart may be frozen quite hard, yet on being thawed it contracts spontaneously. 
The contraction -proceeds in a wave from the spot stimulated in the frog’s heart, at 8° to 120 C. 
at 30 to 90 mm. per sec.; in the mammalian excised heart about 8 metres per sec. ( Waller and 
Reid).'] 
Action of Gases on the Heart.—During its activity the heart uses O, and produces C02 so 
that it beats longest in pure O (12 hours), and not so long in N,—H (1 hour)—C02 (10 minutes) 
—CO (42 minutes)—Cl (2 minutes), or in a vacuum (20 to 30 minutes), even when there is 
watery vapor present to prevent evaporation. If the heart be reintroduced into O it begins to 
beat again. [Gases seem to have the same effect in the chick’s heart on the second and third 
days of incubation as in the adult heart (Fano). A frog’s heart ceases to beat in compressed O 
(10 to 12 atmospheres) in about one-third of the time it would do were it simply excised and 
left to itself. An excised heart suspended in ordinary air beats three to four times as long as a 
heart which is placed upon a glass plate.] 
[56. PHYSICAL EXAMINATION OF THE HEART.—The 
physical methods of diagnosis enable us to obtain precise knowledge re- 
garding the actual state of the heart. The methods available are :— 
1. Inspection. 
2. Palpation. 
3. Percussion. 
4. Auscultation. 
To arrive at a correct diagnosis all the methods must be employed.] 
[Inspection.—The person is supposed to have his chest exposed and to be in the recumbent 
position. It is important to remember the limits of the heart. The base corresponds to a 
line joining the upper margins of the third costal cartilages, the apex to the fifth interspace, while 
transversely it extends from a little to the right of the sternum to within a little of the left nipple; 
this area occupied by the heart being called the deep cardiac region (fig. 62). By the eye we 
can detect any alteration in the configuration of the prsecordia, bulging or retraction of the region 
as a whole or of the intercostal spaces, and we may detect variations in the position, character, 
extent of the cardiac impulse, or the presence of other visible pulsations.] 
[Palpation.—By placing the whole hand flat upon the praecordia, we can ascertain the 
presence or absence, the situation and extent, and any alterations in the characters of the apex- 
beat; or we may detect the existence of abnormal pulsations, vibrations, thrills, or friction in 
this region. In feeling for the apex-beat, if it be at all feeble, it is well to make the patient 
lean forward. Of course, it must be remembered that the whole heart may be displaced by 
tumors or accumulations of fluids pressing upon it, i. e., conditions external to itself, or the 
apex-beat may be displaced from causes within the heart itself, as in hypertrophy of the left 
ventricle.] 
[Percussion.—As the heart is a solid organ, and is surrounded by the lungs, which contain 
air, it is evident that the sound emitted by striking the chest over the region of the former must 
be different from that produced over the latter. Not only is there a difference in the sound or 
note emitted, but the “ sensation of resistance” which one feels on percussing the two organs is 
different. We may ascertain— 
1. The superficial or absolute cardiac dulness. 
2. The deep or relative dulness.] 
[Superficial Cardiac Dulness.—This theoretically is the part of the heart in direct contact 
with the chest-wall and uncovered by lung, but obviously as the lungs vary in size during respira- 
tion, it must be smaller during inspiration and larger during expiration. It forms a roughly 
triangular space, whose base cannot be accurately determined, as the heart-dulness merges into 
that of the liver, situate below it, but it corresponds to a horizontal line inches long, extending 
from the apex-beat to the middle of the sternum. The internal side corresponding to the left 
edge of the sternum is 2 inches long, and reaches from the junction of the fourth costal cartilage 
with the sternum—apex of the triangle—to the sternal end of the base line. The superior, outer, 
or oblique line, 3 inches in length, is somewhat curved, and passes downwards and outwards 
from the apex of the triangle to the apex of the heart. The clinical value of the superficial 
dulness is not great.] 
[Deep Cardiac Dulness.—By this method theoretically we seek to define the exact limits of 
the heart as a whole, and thus to ascertain its absolute size, and of course percussion has to be 
done through a certain thickness of lung tissue, and hence one must strike the pleximeter 
forcibly. It extends vertically from the third rib and ends at the sixth, but owing to the 
cardiac merging in the hepatic dulness, this lower limit cannot be accurately ascertained ; while 
transversely at the fourth rib it extends from just within the nipple line to slightly beyond the 90 
INNERVATION OF THE HEART. 
[Sec. 56. 
right of the sternum. By these means we may detect increase in the size of the heart or altera- 
tions in the relation of the lungs to the heart, fluid in pericardium, etc. Thus it is of great 
importance to the clinician, enabling him to determine the size and position of the heart.] 
[Auscultation.—This is one of the most valuable methods, for by it we can detect variations 
and modifications in the healthy sounds of the heart, the rhythm and frequency of the heart- 
beat, the existence of abnormal sounds, and their exact relation to the normal sounds, also 
their characters and relation to the cardiac cycle, and the direction in which these sounds are 
propagated ($ 54).] 
Fig. 62. 
Topography of the thorax and its contents, a. d., right atrium; o. s., left auricle; v. d., right 
ventricle; I, left ventricle, with Ix, position of cardiac impulse; A, aorta; II, pulmonary 
artery; C, V, vena cava superior; L, L, limits of the lungs; P, P, limits of the attachment 
of the parietal pleura; the space between L, L, and P, P, is called the “ complemental 
space.” 
57. INNERVATION OF THE HEART.—[Intra- and Extra- 
Cardiac Nervous Mechanism.—When the heart is removed from the body, 
or when all the nerves which pass to it are divided, it still beats for some time, 
so that its movements must depend upon some mechanism situated within itself. 
The ordinary rhythmical movements of the heart are undoubtedly associated 
with the presence of nerve ganglia, which exist in the substance of the heart— 
the intra-cardiac ganglia. But the movements of the heart are influenced by Sec. 57.] 
THE FROG’S HEART. 
91 
nervous impulses which reach it from without, so that there falls to be studied 
an intra-cardiac and an extra-cardiac nervous mechanism.] 
The cardiac plexus is composed of the following nerves : (1) The cardiac 
branches of the vagus, the branch of the same name from the external branch ot 
the superior laryngeal, a branch from the inferior laryngeal, and sometimes 
branches from the pulmonary plexus of the vagus (more numerous on the right 
side); (2) the superior, middle, inferior, and lowest cardiac branches of the 
three cervical ganglia and the first thoracic ganglia of the sympathetic; (3) the 
inconstant twig of the descending branch of the hypoglossal nerve, which, 
according to Luschka, arises from the upper cervical ganglion. From the 
plexus there proceed—the deep and the superficial nerves (the latter usually at 
the division of the pulmonary artery under the arch of the aorta, and containing 
the ganglion of Wrisberg) (§ 370). The following nerves may be separately 
traced from the plexus :— 
(a) The plexus coronarius dexter and sinister, which contains the 
vaso-motor nerves for the coronary vessels (physiological proof still wanting) as 
well as the nerves (sensory?) proceeding from them (to the pericardium?). 
Fig. 63. 
Fig. 64. 
Heart of frog from the front. V, single ven- 
tricle; Ad, As, right and left auricles; 
B, bulbus arteriosus; 1, carotid, 2, aorta, 
and 3, pulmo-cutaneous arteries; C, ca- 
rotid gland. 
Heart of frog from behind, s. v., sinus ve- 
nosus opened; ci, inferior; csd, css, right 
and left superior venre cavse; vp., pul- 
monary vein; Ad and As, right and left 
auricles ; Ap, communication between 
the right and left auricle. 
(b) Intra-cardiac nerves and ganglia.—The nerves lying in the grooves 
of the heart and in its substance contain numerous ganglia (Remak), and are 
regarded as the automatic motor centres of the heart. A nervous ring contain- 
ing numerous ganglia corresponds to the margin of the septum atriorum ; there 
is another in the auriculo-ventricular groove. Where the two meet, they ex- 
change fibres. The ganglia usually lie near the pericardium-. In mammals, 
the two largest ganglia lie near the orifice of the superior vena cava—in birds, 
the largest ganglion (containing thousands of ganglionic cells) lies posteriorly 
where the longitudinal and transverse sulci cross each other. Fine branches, 
also provided with small ganglia, proceed from these ganglia, and penetrate the 
muscular walls of the auricles and ventricles. 
[Frog’s Heart.—The frog’s heart consists of the sinus venosus, into which open the single 
inferior and the two superior venae cavse (fig. 64). There are two auricles; the right one com- 
municates with the sinus venosus, and opens into the single ventricle; the left auricle also 
opens into the single ventricle (fig. 63, v), and in the latter are mixed the venous blood returned 
by the right auricle and the arterial blood from the left auricle. The aorta with its bulbus 
arteriosus conducts the blood from the ventricle. The various orifices are guarded by projec- 
tions of tissue, which act like valves. The two auricles are completely separated by a septum. 
This septum ends posteriorly in a free concave margin, so as to divide the auriculo-ventricular 
orifice into a right and left orifice. Each orifice is guarded by two thick fleshy valves, which 
close it.] THE FROG’S HEART. 
[Sec. 57. 
[Nerves.—The two cardiac branches of the vagi—the nervi cardiaci—proceed to the 
posterior surface of the sinus venosus, and where the latter joins the auricle they interlace, and are 
mixed with a number of ganglion cells (fig. 67). This spot is called Remak’s ganglion, is 
sometimes single, at others double, and it can be seen as a white “ crescent ” when the heart is 
lifted up and looked at from behind (fig. 64). The cardiac nerves pass on to the auricular 
septum—which contains nerve-cells, known as Ludwig’s ganglion—exchanging fibres in their 
course to join two ganglia at the auriculo ventricular groove, and known as Bidder’s ganglia 
(fig. 67). It has been stated that the bulbus arteriosus also contains ganglionic cells.] 
Fig 65. 
Fig. 66. 
Auricular septum of a frog’s heart, a, anterior, 
and p, posterior branch of the cardiac vagus ; 
B, Bidder’s ganglion. 
Pyriform ganglionic bi-polar nerve-cell 
from the heart of a frog, m, sheath; 
n, straight process; o, spiral process. 
According to Openchowsky, every part of the heart (frog, triton, tortoise) contains nerve- 
fibres which are connected with the muscular fibres. In the auricles, at the end of the non- 
medullated fibre, a tri-radiate nucleus exists which gives off fibrils to the muscular bundles. 
There is a network of fine nerve-fibres distributed immediately under the endocardium—these 
fibres act partly in a centripetal direction on the cardiac ganglia, and are partly motor for the 
endocardial muscles. The parietal layer of the pericardium contains (sensory) nerve-fibres. 
The following kinds of nerve-cells are found—unipolar cells, the single processes of which after- 
Fig. 67. 
Fig. 68. 
Scheme of nerves of frog’s heart. R. 
Remak’s, and B, Bidder’s ganglia; 
S. V., sinus venosus; A, auricles; 
V. ventricle ; B. A., bulbus ar- 
teriosus ; vag, vagi. 
Stannius’s experiment. A, auricle; 
V, ventricle ; S. V., sinus venosus. 
The zig-zag lines indicate which 
parts continue to beat; in 2 the 
ventricle beats at a different rate. 
wards divide; bipolar pyriform cells (fig. 66), which in the frog possess a straight («) and 
also a spiral process (0) (f 321). 
58. THE AUTOMATIC MOTOR CENTRES OF THE HEART. 
—(1) It is generally assumed that the nervous centres which excite the cardiac 
movements, and maintain the rhythm of these movements, lie within the heart, 
and that they are probably represented by the ganglia. [The heart, however, Sec. 58.] 
NERVOUS CENTRES IN HEART. 
93 
can execute rhythmical pulsations without the presence of ganglionic structures, 
P- 97-] 
(2) There are—not one, but several of these centres in the heart, which are 
connected with each other by conducting paths. As long as the heart is intact, 
all its parts move in rhythmical sequence from a principal central point, an 
impulse being conducted from this centre through the conducting paths. What 
the “ discharging forces ” of these regular progressive movements are is un- 
known. If, however, the heart be subjected to the action of diffuse stimuli 
(<?. g., strong electrical currents), all the centres are thrown into action, and a 
spasm-like action of the heart occurs. The dominating centre lies in the auricles, 
hence the regular progressive movement usually starts from them. If the 
excitability is diminished, as by touching the septum with opium, other centres 
seem to undertake this function, in which case the movement may extend from 
the ventricles to the auricles. According to Kronecker and Schmey, in the 
dog's heart there is a spot above the lower limit of the upper third of the ven- 
tricular septum, which, when it is injured, e.g., by destroying it with a stout 
needle, brings the heart to a stand-still; this has been called a co-ordinating 
centre. [The existence of this centre is denied by some observers.] 
(3) All stimuli of moderate strength applied directly to the heart cause at 
first an increase of the rhythmical heart-beats ; stronger stimuli cause a diminu- 
tion, and it may be paralysis, which is often preceded by a convulsive movement. 
Increased activity exhausts the energy of the heart sooner. 
(4) Single very weak stimuli, which have no effect on the heart when applied 
singly, if repeated sufficiently often, may become active owing to “ summation 
of the stimuli ” (v. Busch'). 
(5) Even the weakest stimulus which can excite a contraction always causes 
an energetic contraction, i. e., “ the minimal stimulus causes a maximal effect” 
{Bowditch, Kronecker and Stirling). 
(6) After every contraction of the heart there is a short period of “ dimin- 
ished excitability” or Marey’s “refractory period,” during which the heart is 
less susceptible to further stimulation. 
(7) The non-ganglionic apex of the heart, when it is not stimulated, no longer 
beats spontaneously, but it responds each time by a single contraction to a single 
direct stimulus. If, however, a continuous stimulus, e.g., a continuous current 
of electricity, be applied to it, it executes a series of beats. Such continuous 
stimuli are obtained through a continuous pressure of fluid, exerted on the 
interior of the heart, or by moistening the heart with chemical substances. 
(8) The auricular centres seem to be more excitable than those of the 
ventricle ; hence, in a heart left to itself the auricles pulsate longest. 
(9) The heart may be excited (reflexly) from its inner surface. Weak stimuli 
applied to the inner surface of the heart greatly accelerate the heart’s action, the 
stimulus required being much feebler than that applied to the external surface 
of the heart. Strong stimuli, which bring the heart to rest, also act more easily 
when applied to its inner surface than when they are applied to its outer surface. 
The ventricle is always the first part to be paralyzed. 
(10) In order that the heart may continue to contract, it is necessary that it 
be supplied with a fluid which, in addition to O, must contain the necessary 
nutritive materials. The most perfect fluid, of course, is blood. Hence the heart 
after a time ceases to beat in an indifferent fluid (0.6 percent, sodium chloride), 
but its activity may be revived by supplying it with a proper nutritive fluid. 
Cardiac Nutritive Fluids.—These nutritive fluids are such as contain serum-albumin, e.g., 
blood, serum, or lymph. Serum retains its nutritive properties even after it has been subjected 
to diffusion (Martins and Kronecker). Milk and whey (v. Ott), normal saline solution mixed 
with blood, albumin, or peptone, and 0.3 per cent, sodium carbonate (.Kronecker, Merunowicz and 
Stienon), a trace of caustic soda ( Gaule), or a solution of the salts of serum, are suitable. Alka- 94 
EXPERIMENTS ON THE HEART. 
[Sec. 58. 
line solution of soda revives a feebly beating heart by neutralizing the acid formed in the cardiac 
muscle, and so does normal saline containing calcic phosphate and potassic chloride ( S. Ringer). 
(n) The independent pulsations of parts of the heart which are devoid of 
ganglia show that the presence of ganglia is not absolutely necessary in order to 
have rhythmical pulsation. Direct stimulation of the heart may cause these 
movements. But the ganglia are more excitable than the heart muscle itself, 
and they conduct the impulses which lead to the regular alternating action of the 
various parts of the heart, so that, under normal circumstances, we must assume 
that the action of the heart is governed by the ganglia. 
(12) If a heart be cut in pieces, so that the individual pieces still remain 
connected with each other, the regular peristaltic or wave-like movements pro- 
ceeding from the auricles to the ventricle may continue for a long time 
(.Bonders, Engelmanti). If the heart, however, be completely divided into two 
distinct pieces (auricle and ventricle), the movements of both parts continue, 
but not in the same sequence—they beat at different rates. 
The chief experiments upon which the above statements are based are as 
follows:— 
I. Experiments by cutting and ligaturing the heart. These experiments 
have been made chiefly upon the heart of the frog. The ligature experiments 
are performed by tightening and then relaxing the ligature placed around the 
heart, so that the physiological connection is destroyed, while the anatomical or 
mechanical connections (continuity of the cardiac wall, intact condition of its 
cavities) still exist. The most important of these experiments are— 
(1) Stannius’s Experiment.—If the sinus venosus of a frog’s heart be 
separated from the auricles, either by an incision or by a ligature, the auricles and 
ventricle stand still in diastole, whilst the veins and the remainder of the sinus 
continue to beat (fig. 68, 1). If a second incision be made at the auriculo- 
ventricular groove, as a rule the ventricle begins at once to beat again, whilst 
the auricles remain in the condition of diastolic rest. [Thus the sinus venosus 
and ventricle continue to beat, while the auricle stands still, but the two former 
no longer beat with the same rhythm, the ventricle usually beats more slowly, as 
is shown in fig. 68, 2, by the large zig-zags.] According to the position of the 
second ligature or incision, the auricles may also beat along with the ventricles, 
or the auricles alone may beat while the ventricles remain at rest. 
Theoretical.—Various explanations of these experiments have been given : (A) Remak’s 
ganglion in the sinus venosus is distinguished by its great excitability, while Bidder’s ganglion 
in the auriculo-ventricular groove is less excitable; in the normal condition of the heart the 
motor impulse is carried from the former to the latter. If the sinus venosus be separated from 
the heart, Remak’s ganglion has no action on the heart. The heart stops for two reasons— 
first, because Bidder’s ganglion alone has not sufficient energy to excite it to action, and because 
the inhibitory fibres of the vagus going to the heart have been stimulated by being divided at 
this point (Heidenhain). [That stimulation of the inhibitory fibres of the vagus is not the 
cause of the standstill is proved by the fact that the standstill occurs even after the adminis- 
tration of atropine, which paralyzes the cardiac inhibitory mechanism.] The passive heart, 
however, may be made to contract by mechanically stimulating Bidder’s ganglion, e.g., by a 
slight prick with a needle in the auriculo-ventricular groove, or by the action of a constant 
current of moderate strength (Eckhard), the ventricular pulsation at the same time preceding 
the auricular [v. Bezold, Bernstein). If the auriculo-ventricular groove be divided, the ventricle 
pulsates again, because Bidder’s ganglion has been stimulated by the act of dividing it; while, 
at the same time, the ventricle is withdrawn from the inhibitory influence of the vagus pro- 
duced by the first division at the sinus venosus. If the line of separation is so made that 
Bidder’s ganglion remains attached to the auricles, these pulsate, and the ventricle rests; if it 
be divided into halves, the auricles and ventricles pulsate, each half being excited by the portion 
of the ganglion in relation with it. (B) According to another view, both Remak’s (a) and 
Bidder’s ganglia (b) are motor centres, but in the auricles there is in addition an inhibitory 
ganglionic system (c) (Bezold, Traube). Under normal circumstances zz -f- is stronger than c, 
while c is stronger than a or b separately. If the sinus venosus be separated it beats in virtue 
of a; on the other hand, the heart rests because c is stronger than b. If the section be made Sec. 58.] 
LIGATURE AND SECTION OF HEART. 
at the level of the auriculo-ventricular groove, the auricles stand still owing to c, while the 
ventricle beats owing to b. 
(2) Descarte’s Experiment (1644).—If the ventricle of a frog’s heart be 
separated from the rest of the heart by means of a ligature, or by an incision 
carried through’it at the level of the auriculo-ventricular groove, the sinus and 
atria pulsate undisturbed as before, but the ventricle stands still in diastole. A 
single local stimulus applied to the ventricle is responded to by a single con- 
traction. If the incision be so made that the lower margin of the auricular 
septum remains attached to the ventricle, the latter pulsates. Even the ven- 
tricles of a rabbit’s heart, when separated along with a part of the auricles in 
connection with them, pulsate (Tigerstedt). 
[Gaskell’s Clamp.—Gaskell uses a clamp, regulated by a millimetre screw, to compress the 
heart, and thus to obstruct the passage of impulses from one part of the heart to the other, or 
to “block” the way, the pulsations of the auricles and ventricles being separately registered. 
By compressing the heart at the auriculo-ventricular groove, the ratio of auricular and ventricular 
beats alters, and instead of being I : I, there may be 2, 3, or more auricular beats for each beat 
A II III IV 
of the ventricle, expressed thus— y> j > j > —j-* After the heart is fixed by the clamp, 
levers are placed horizontally above and below the heart. These levers are fixed to a part of 
the auricles and to the apex by means of threads. Each part of the heart attached to a lever, as 
it contracts, pulls upon its own lever, so that the extent and duration of each contraction may be 
registered. This method is applicable for studying the effect of the vagus and other nerves upon 
the heart.] 
(3) Section.—A. Fick showed that the process of excitement in the con- 
tractile tissue of the frog’s heart is propagated in all directions (1874), so that 
to a certain extent the whole frog’s heart behaves like one continuous muscular 
fibre; thus one transverse cut into the ventricle does not prevent contraction 
from taking place in the separated parts. Engelmann’s experiments also show 
that if the ventricle of a frog’s heart be cut up into two or more strips in a 
zig-zag way, so that the individual parts still remain connected with each other 
by muscular tissue, the strips still beat in a regularly progressive rhythmical 
manner, provided one strip is caused to contract. The rapidity of the trans- 
mission is about 10 to 15 mm. per sec. Hence it appears that the conducting 
paths for the impulse causing the contraction are not nervous, but must be the 
contractile mass itself. It has not been proved that nerve-fibres proceed from 
the ganglia to all the muscles. 
[According to Marchand’s experiments, it takes a very long time for the excitement to pass 
from the auricle to the ventricle—a much longer time, in fact, than it would require to conduct 
the excitement through muscle—so that it is probable that the propagation of the impulse from 
the auricles to the ventricle is conducted by nervous channels to the auriculo-ventricular nervous 
apparatus. In fact, in the mammalian heart the muscular fibres of the auricles are quite distinct 
from those of the ventricles.] 
(4) When the apex of a frog’s heart is ligatured off from the rest of the heart, 
it no longer pulsates (.Heidenhain, Goltz), but such an apex, if stimulated 
directly, e.g., by a prick of a pin, responds with a single contraction. If the 
“heart-apex” be filled with normal saline solution under pressure, which acts 
as a stimulus, the heart begins to pulsate, and the same is the case with a solu- 
tion of delphinin or quinine. If a cannula be tied into the heart over the 
auriculo-ventricular groove, the ventricle does not beat, but if the ventricle be 
filled through the cannula with blood containing oxygen, under a constant and 
sufficient pressure, it pulsates (Ludwig and Merunowicz). 
[(5) Luciani found that a heart ligatured above the auriculo-ventricular groove, 
when filled with pure serum, produced groups of pulsations with a long diastolic 
pause between every two groups (fig. 69). The successive beats in each group 
assume a “staircase” character(p. 100). These periodic groups undergo many 96 
[Sec. 58. 
ACTION OF FLUIDS ON HEART. 
changes ; they occur when the heart is filled with pure serum free from blood- 
corpuscles, and they disappear and give place to regular pulsations when defib- 
rinated blood or serum containing haemoglobin or normal saline solution is 
used (.Rossbach). They also occur when the blood within the heart has become 
dark-colored, i. <?., when it has been deprived of certain of its constituents, 
and if a trace of veratrin be added to bright red blood they occur.] 
(6) An apex preparation, when stimulated with even a weak induction shock, 
always gives its maximal contraction, and when a tetanizing current is applied 
tetanus does not occur {Kronecker and Stirling). When the opening and clos- 
ing shocks of a sufficiently strong constant current are applied to the heart-apex, 
it contracts with each closing or opening shock. [When a constant current is 
applied to the lower two-thirds of the ventricle (heart-apex), under certain con- 
ditions the apex contracts rhythmically. This is an important fact in connection 
with any theory of the cardiac beat.] 
(7) If the bulbus aortse (frog) be ligatured, it still pulsates, provided the 
internal pressure be moderate. Should it cease to beat, a single stimulus makes 
it respond by a series of contractions. Increase of temperature to 350 C., and 
raising the pressure within it, increase the number of pulsations (.Engebnann). 
Action of Fluids.—Haller was of opinion that the venous blood was the 
natural stimulus which caused the heart to contract. That this is not so is 
proved at once by the fact that the heart beats rhythmically when it contains 
Fig. 69. 
Four groups of pulsations with intervening pauses, with their “staircase” character. The 
points on the abscissa were marked every 10 seconds. 
no blood. Blood and other fluids which are supplied to an excised heart are 
not the cause of its rhythmical movements, but only the conditions on which 
these movements depend. 
[Methods.—The study of the action of fluids upon the excised frog’s heart has been rendered 
possible by the invention of Ludwig’s “ frog-manometer.” The apparatus, as modified by 
Kronecker (fig. 70), consists of (1) a double-way cannula, c, which is tied into the heart, h; (2) 
a manometer, m, connected with c, and registering the movements of its mercury on a revolv- 
ing cylinder, cyl\ (3) two Marriotte’s flasks, a and b, which are connected with the other limb 
of the cannula. Either a or b can be placed in communication with the interior of the heart 
by means of the stop-cock, s. To the fluid in one graduated tube may be added the substance 
whose effect on the heart it is proposed to investigate, while the fluid in the other vessel 
remains without the addition of any substance and can be used as a control-fluid; d is a glass 
vessel for fluid, in which the heart pulsates, e' and e are electrodes, e is inserted into the fluid in 
d, e' is attached to the German silver cannula which is shown in fig. 71.] 
[In the tonometer of Roy (figs. 72 and 73) the ventricle, h, or the whole heart, is placed in 
an air-tight chamber, o, filled with oil. As before, a “ perfusion” cannula is tied into the heart. 
A piston,/, works up and down in a cylinder, and is adjusted by means of a thin flexible animal 
membrane, such as is used by perfumers. Attached to the piston by means of a thread is a 
writing-lever, l, which records the variations of pressure within the chamber, 0. When the 
ventricle contracts, it becomes smaller, diminishes the pressure within 0, and hence the piston 
and lever rise; conversely, when the heart dilates, the lever and piston descend. Variations in 
the volume of the ventricle may be registered without in any way interfering with the flow of 
fluids through it.] 
[Two preparations of the frog’s heart have been used—(1) The “ heart,” in which case the Sec. 58.] 
HEART PREPARATIONS AND MANOMETER. 
97 
cannula is introduced into the heart through the sinus venosus, and a ligature is tied over it 
around the auricle, i. e., above the auriculo-ventricular groove. Thus the auriculo ventricular 
ganglia and other nervous structures remain in the preparation. This was the heart preparation 
employed by Luciani and Rossbach. (2) In the “ heart-apex ” or apex preparation, the 
cannula is introduced as before; but the ligature is tied on it over the ventricle several millimetres 
below the auriculo-ventricular groove, so that this preparation contains none of the auriculo- 
ventricular ganglia, and, according to the usual statement, this part of the heart is devoid of 
nerve ganglia. This is the preparation which was used by Bowditch, Kronecker and Stirling, 
Merunowicz, and others.] 
[The first effect of the application of the ligature in both cases is, that both preparations cease 
to beat, but the “ heart ” usually resumes its rhythmical contractions within several minutes, 
while the “heart-apex” does not contract spontaneously until after a much longer time (10 to 
90 mins.).] 
[If the “ heart-apex” be filled with a 0 6 per cent, solution of common salt, the contractions 
are at first of greater extent, but they afterwards cease, and the preparation passes into a condition 
■of “ apparent death,” lasting 30—90 mins.; while, if the action of the fluid be prolonged, the heart 
•may not contract at all, even when it is stimulated electrically or mechanically. It may be made, 
Fig. 70. 
Fig. 71. 
Scheme of Kronecker’s frog-mano- 
meter. a, b, Marriotte’s flasks for 
the nutrient fluids; s, stop-cock; c, 
cannula; m, manometer; h, heart; 
d, glass cup for h ; e', e, electrodes; 
cyl, revolving cylinder. 
Perfusion cannula for a frog’s 
heart, c, for fixing an elec- 
trode; d, the heart is tied 
over the flanges preventing 
it from slipping out; e, sec- 
tion of d. 
however, to pulsate again, if it be supplied with saline solution containing blood (i to io per 
cent.). If the ventricle be nipped with wire forceps at the junction of the upper with its middle 
third, so as to separate the lower two-thirds of the ventricle, physiologically but not anatomically, 
from the rest of the heart, then the apex will cease to contract, although it is still supplied with 
the frog’s own blood (.Bernstein, Bowditch). The physiologically isolated apex may be made 
to beat by clamping the aortic branches so as to prevent blood passing out of the heart, and thus 
raising the intracardiac pressure. The rate of the beat of the apex is independent of and slower 
than that of the rest of the heart. This experiment proves that the amount of pressure within 
the apex-cavity is an important factor in the causation of the spontaneous beats of the apex. If 
blood-serum, to which a trace of delphinin is added, be transfused or “perfused” through the 
heart, the heart begins to beat within a minute, continues to beat for several seconds, and then 
stands still in diastole (B'ow ditch). Quinine and a mixture of atropine and muscarin have a 
similar action. These experiments show that, provided no nervous apparatus exists within the 
heart-apex, the cause of the varying contraction is to be sought for in the musculature of the 
heart, and that the stimulus necessary for the systole of the heart’s apex may arise within itself. 
If there is no nervous apparatus of any kind present, then we must assume that the heart-muscle 
may execute rhythmical movements independently of the presence of any nervous mechanism, 
-although it is usually assumed that the ganglia excite the heart-muscle to pulsate rhythmically. 98 
TONOMETER. 
[Sec. 58. 
It is by no means definitely proved that the heart-apex is devoid of all nervous structures, which 
may act as originators of these rhythmical impulses.] 
[Action of Drugs.—If the heart-apex contains no nervous structures, it must form a good 
object for the study of the action of drugs on the cardiac muscle. Some of these have been 
mentioned already. Ringer finds that a calcium 
salt makes the contractions higher and longer. 
Dilute acids added to saline solution, e. g., 
lactic, cause complete relaxation of the cardiac 
musculature, while dilute alkalies produce an 
opposite effect or tonic contraction, even though 
the apex be not pulsating. The action of a 
dilute acid may be set aside by a dilute alkali 
and vice versa. Digitalin, antiarin, barium, 
and veratria act like alkalies, while saponin, 
muscarin, and pilocarpin have the effect of 
acids (| 65). An isolated frog’s heart, fatigued 
after being supplied with a solution of blood, 
is caused to beat more vigorously by a solution 
of kreatinin, or extract of meat (Mays).] 
[The “ heart ” preparation in many respects 
behaves like the foregoing, i. e., it is exhausted 
after a time by the continued application of 
normal saline solution (0.6 per cent. NaCl), 
while its activity may be restored by supplying 
it with albuminous and other fluids (p. 93).] 
II. Direct Stimulation of the 
Heart.—All direct cardiac stimuli act 
more energetically on the inner than 
on the outer surface of the heart. If 
strong stimuli are applied for too long 
a time, the ventricle is the part first 
paralyzed. 
(a) Thermal Stimuli.—[Heat affects the number or frequency and the amplitude of the 
pulsations, as well as the duration of the systole and diastole and the excitability of the heart.] 
Descartes (1644I observed that heat increased the number of pulsations of an eel’s heart. As 
the temperature increases, the number of beats is at first considerably 
increased, but afterwards the beats again become fewer, and if the 
temperature is raised above a certain limit the heart stands still, the 
myosin of which its fibres consist is coagulated, and “ heat-rigor ” 
occurs. Even before this stage is reached, however, the heart may 
stand still, the muscular fibres appearing to remain contracted. The 
ventricles usually cease to beat before the auricles (Schelske). The 
size and extent of the contractions increase up to about 20° C., but 
above this point they diminish (fig. 74). The time occupied by any 
single contraction at 20° C. is only about fa of the time occupied 
by a contraction occurring at 50 C. A heart which has beenw armed 
is capable of reacting pretty rapidly to intermittent stimuli, while a 
heart at a low temperature reacts only to stimuli occurring at a con- 
siderable interval (Gaule). 
Cold.—When the temperature of the blood is diminished, the heart 
! beats more slowly. A frog’s heart, placed between two watch-glasses 
and laid on ice. beats verv much more slowly. The pulsations of a 
frog’s heart stop when the heart is 
exposed to a temperature of 40 C. 
to o°. If a frog’s heart be taken 
out of warm water, and suddenly 
placed upon ice, it beats more 
rapidly, and conversely, if it be 
taken from ice and placed over 
warm water, it beats more slowly at first and more rapidly afterwards (Aristow). 
[Methods.—The effect of heat on a heart may be studied by the aid of the frog-manometer, 
the fluid in which the heart is placed being raised to any temperature required. For demonstra- 
tion purposes, the heart of a pithed frog is excised and placed on a glass slide under a light 
Roy’s tonometer, as made by the Cambridge 
Scientific Instrument Company. 
Fig. 72. 
Fig- 73- 
Roy’s heart tonometer, h, heart; o, air-tight chamber; 
p, piston; /, writing-lever; e, outflow tube. Sec. 58.] 
MECHANICAL AND ELECTRICAL STIMULATION OF HEART. 
99 
lever, such as a straw. The slide is warmed by means of a spirit-lamp. In this way the 
frequency and amplitude of the contractions are readily made visible at a distance.] 
(£) Mechanical Stimuli.—Pressure applied to the heart from without accelerates its action. 
In the case of Frau Serafin, v. Ziemssen found that slight pressure on the auriculo-ventricular 
groove caused a second short contraction of both ventricles after the heart-beat. Strong pressure 
causes a very irregular action of the cardiac muscle. This may readily be produced by 
compressing the freshly excised heart of a dog between the 
fingers. The intra-cardiac pressure also affects the heart- 
beat (p. 97). If the pressure within the heart be increased, 
the heart-beats are gradually increased; if it be diminished, 
the number of beats diminishes (Ludwig and Thiry). If the 
intra-cardiac pressure be very greatly increased, the heart’s 
action becomes very irregular and slower. A heart which has 
ceased to beat may under certain circumstances be caused to 
execute a single contraction if it be stimulated mechanically. 
(r) Electrical Stimuli.—A constant electrical current 
of moderate strength increases the number of heart-beats. 
V. Ziemssen found, in the case of Frau Serafin (£ 47, 3), 
that the number of beats was doubled while a constant un- 
interrupted strong current was passed through the ventricles. 
[If the constant current be very strong, or if tetanizing 
A, contraction of a frog’s heart at 190 C.; B, at 340 C.; C, at 30 C. 
Fig- 74- 
induction currents be applied to the heart, e.g., of a dog, the normal heart-beat is abolished, 
the ventricular muscle being thrown into a state of irregular, arhythmic contraction, whilst ther 
is a great fall of blood-pres sure (Ludwig and Hoff a'). This condition is spoken of as delirium 
cordis or fibrillar contraction. It is caused by some change in the muscular fibres of the 
ventricles themselves; the movements are very complex, last long, and occur rapidly; the per- 
sistence seems to be due to the great excitability of the ventricular tissue. It appears to consist 
of a rapid succession of incoordinated peristaltic contractions, which may be brought about as 
described above, or by the action of some depressing agents, e.g., potassic bromide. These ven- 
tricular fibrillar contractions are not affected by stimulation of the vagus. Similar electrical 
stimulation of the auricles causes a fluttering movement, more like a series of contractions, with- 
out any distinct sign of incoordination. These auricular movements are arrested by stimulation 
of the vagus [Mac William).'] If the auriculo-ventricular groove be compressed so as to cause the 
ventricle of a frog’s heart to cease to beat, on placing one electrode of a constant current on the 
ventricular wall and the other electrode on an indifferent part of the body, we obtain, on making 
the current, a systolic contraction of the ventricle only when the cathode touches the ventricle; 
and conversely on breaking, only when the anode is on the heart [Biedermann). 
When a single induction shock is applied to the ventricle of a frog’s heart during systole, it 
has no apparent effect; but if it is applied during diastole, the succeeding contraction takes 
place sooner. The auricles and also the apex behave in a similar manner. Whilst they are 
contracted, an induction shock has no effect; if, however, the stimulus is applied during 
diastole, it causes a contraction, which is followed by systole of the ventricle. Even when strong 
tetanizing induction shocks are applied to the heart, they do not produce tetanus of the entire 
cardiac musculature, or, as it is said, “ the heart knows no tetanus ” [Kronecker and Stirling). 
Small white, local wheal-like elevations—such as occur when the intestinal musculature is 
stimulated—appear between the electrodes. They may last several minutes. A frog’s heart, 
which yields weak and irregular contractions, may be made to execute regular rhythmical con- 
tractions synchronous with the stimuli, if electrical stimuli are used [Bowditch). 
[Break induction shocks, if of sufficient strength, cause the heart to contract, while weak 
stimuli have no effect; on the other hand, moderate stimuli, when they do cause the heart to 
contract, always cause a maximal contraction, so that a minimal stimulus acts at the same time CHEMICAL STIMULI AND CARDIAC POISONS. 
[Sec. 58. 
like a maximal stimulus. The heart either contracts, or it does not contract, and when it con- 
tracts the result is always a “ maximal contraction ” (.Kronecker and Stirling). Bowditch found 
that the excitability of the heart was increased by its own movements, so that after a heart had 
once contracted, the strength of the stimulus required to excite the next contraction may be 
greatly diminished, and yet the stimulus be effectual. Usually the amplitude of the first beat 
so produced is not so great as the second beat, and the second is less than the third, so that a 
“ staircase” (“ Treppe”) of beats of successively greater extent was produced (fig. 69). Under 
certain circumstances, however, a skeletal muscle gives contractions of a “staircase” character. 
This staircase arrangement occurs even when the strength of the stimulus is kept constant, so 
that the production of one contraction facilitates the occurrence of the succeeding one. A 
staircase arrangement of the pulsations is also seen in Luciani’s groups (p. 96). The question, 
whether a stimulus will cause a contiaction, depends upon what particular phase the heart is in 
when the shock is applied. Even comparatively weak stimuli will cause a heart to contract, 
provided the stimuli are applied at the proper moment and in the proper tempo, i. e. to say, they 
become what are called “ infallible.” If stimuli are applied to the heart, at intervals which are 
longer than the time the heart takes to execute its contraction, they are effectual or “adequate,” 
but if they are applied before the period of pulsation comes to an end, then they are ineffectual 
{Kronecker). It is quite clear, therefore, that the relation of the strength of the stimulus to 
the extent of the contraction of the cardiac muscle is quite different from what occurs in a muscle 
of the skeleton, where within certain limits the amplitude of the contraction bears a relation to 
the stimulus, while in the heart the contraction is always maximal.] 
Human Heart.—V. Ziemssen found that he could not alter the heart-beats of the human 
heart (Frau Serajin, \ 47, 3), even with strong induction currents. The ventricular diastole 
seemed to be less complete, and there were irregularities in its contraction. By opening and 
closing, or by reversing a strong constant current applied to the heart, the number of beats 
was increased, and the increase corresponded with the number of electrical stimuli; thus, when 
the electrical stimuli were 120, 140, 180, the number of heart-beats was the same, the pulse 
beforehand being 80. The normal pulse-rate of 80 was reduced to 60 and 50 when the number 
of shocks was reduced in the same ratio. [In Frau Serafin’s case the electrodes were applied to 
the heart, separated from it merely by the pericardium. Ziemssen found that the Faradic current 
did not modify the heart’s action when the thorax was intact, but that the constant current did, 
if of sufficient strength. Herbst and Dixon Mann obtained negative results with both kinds of 
electricity in the normal thorax.] 
(d) Chemical Stimuli.—Many chemical substances, when applied in a dilute solution to the 
inner surface of the heart, increase the heart-beats, while if they are concentrated, or allowed to 
act too long, they diminish the heart-beats, and paralyze it. Bile, and bile salts, diminish the 
heart beats (also when they are absorbed into the blood as in jaundice); in very dilute solu- 
tions both increase the heart-beats. A similar result is produced by acetic, tartaric, citric, and 
phosphoric acids. Chloroform and ether, applied to the inner surface, rapidly diminish the 
heart-beats, and then paralyze it; but very small quantities of ether (1 per cent.) accelerate the 
heart-beat of the frog (Kronecker and M' Gregor-Robertson), while a solution of to 2 per 
cent, passed through the heart arrests it temporarily or completely. Dilute solutions of opium, 
strychnia, or alcohol applied to the endocardium increase the heart-beats; if concentrated they 
rapidly arrest its action. Chloral-hydrate paralyzes the heart. [Normal saline (0.6 percent.) fails to 
sustain ventricular contractions in the excised batrachian and eel’s heart. When the saline is per- 
fused through the heart, in about twenty minutes the heart ceases to beat spontaneously, and is in- 
excitable to strong induction shocks; but the weakened action may be revived by perfusing normal 
saline saturated with calcium phosphate and containing a trace of potassium chloride (Ringer).] 
Action of Gases.—When blood containing different gases was passed through a frog’s heart, 
Klug found that blood containing sulphurous acid rapidly and completely killed the heart; 
chlorine stimulated the heart at first, and ultimately killed it; and laughing-gas rapidly killed it 
also. Blood containing sulphuretted hydrogen paralyzed the heart without stimulating it. 
Carbonic oxide also paralyzed it, but if fresh blood was transfused the heart recovered. [Blood 
containing O excites the heart (Castell), while the presence of much C02 paralyzes it, and the 
presence of CO,2 is more injurious than the want of O. Blood or serum completely saturated with 
C02 exhausts the heart (Saltet and Kronecker), but it recovers itself when the C02 is removed. 
H and N have no effect.] 
Cardiac Poisons are those substances whose action is characterized by special effects upon 
the movements of the heart. Amongst these are neutral potash salts, which cause the heart 
to stand still in diastole. [An excised frog’s heart ceases to beat after one-half to one minute 
when it is placed in a 2 per cent, solution of potassic chloride.] Even a very dilute solution of 
yellow prussiate of potash injected into the heart of a frog causes the ventricle to stand still in 
systole. Antiar (Java arrow-poison) causes the ventricle to stand still in systole and the auricles 
in diastole. Some heart-poisons, in small doses, diminish the heart’s action, and in large doses 
not unfrequently accelerate it, e.g., digitalis, morphia, nicotin. Others, when given in small 
doses, accelerate its action, and in large doses slow it—veratria, aconitin, camphor. Sec. 58.] 
ACTION OF CARDIAC POISONS. 
Special Actions of Cardiac Poisons.—The complicated actions of various poisons upon the 
heart have led observers to suppose that there are various intra-cardiac mechanisms on which 
these substances may act. Besides the muscular fibres of the heart and its automatic ganglia, 
some toxicologists assume that there are inhibitory ganglia into which the inhibitory fibres of 
the vagus pass, and accelerator ganglia, which are connected with the accelerating nerve-fibres 
of the heart. Both the inhibitory and accelerator ganglia are connected with the atitomatic 
ganglia by conducting channels. 
Muscarin and all other trimethylammonium bases stimulate permanently the inhibitory 
ganglia, so that the heart stands still (Schmiedeberg and Koppe\ [According to Gaskell, how- 
ever, when the action of the sinus is arrested by muscarin, there is no deflection of the galvano- 
meter similar to that produced by the excitation of the vagus. He infers that muscarin does not 
cause arrest of the beat by acting as an excitant of inhibitory mechanisms, but as a depressant 
to motor activity.] As atropin and daturin paralyze these ganglia, the standstill of the heart 
brought about by muscarin may be set aside by atropin. [If a frog’s heart be excised and placed 
in a watch-glass, and a few drops of a very dilute solution of muscarin be placed on it with a 
pipette, it ceases to beat within a few minutes, and will not beat again. If, however, the 
muscarin be removed, and a solution of atropin applied to the heart, it will resume its con- 
tractions after a short time.] Physostigmin or Calabar bean excites the energy of the cardiac 
muscle to such an extent that stimulation of the vagus no longer causes the heart to stand still. 
Iodine-aldehyd, chloroform, and chloral-hydrate paralyze the automatic ganglia. The heart 
stands still, and it cannot be made to contract again by atropin. The cardiac muscle itself 
remains excitable after the action of muscarin and iodine-aldehyd, so that if it be stimulated 
it contracts. [According to Gaskell, antiarin and digitalin solutions produce an alteration in 
the conditions of the muscular tissue of the apex of the heart of the same nature as that pro- 
duced by the action of a very dilute alkali solution, while the action of a blood-solution contain- 
ing muscarin closely resembles that of a dilute acid solution (p. 112, \ 65).] 
[Some Cardiac Poisons.—The cardiac muscle is stimulated, i. e., its contractions become 
more energetic, the rate of heart-beat remaining the same or becoming slower—under the influence 
of veratria, digitalin, strophanthus, antiarin, etc., while it is depressed—as shown by diminished 
energy of contraction, and with final stoppage in diastole—by muscarin, pilocarpin, saponin, 
apomorphin, potash salts in large doses, etc. Guanidin, physostigmin and camphor will cause 
the heart to beat rhythmically after complete standstill in diastole by muscarin.] 
On the theory that inhibitory ganglia are present in the heart, the following drugs— 
muscarin and physostigmin—by stimulating these ganglia cause arrest of heart’s beat in 
diastole, but the heart still contracts to a mechanical or electrical stimulus. These ganglia are 
depressed or paralyzed by atropin, sparttin, duboisin, hyoscyamin, daturin, as shown by the 
fact that stimulation of the vagus or the sinus venosus no longer arrests the heart’s action, nor 
does the application of muscarin cause any effect. 
Nicotin, saponin, and curare depress or paralyze the vagus-ends in the heart, as shown 
by the fact that stimulation of the vagus itself no longer slows or arrests the heart, while muscarin 
applied to the heart, or stimulation of the sinus venosus, will do so. 
[Drugs, besides acting directly on the cardiac muscle, or its intra-cardiac nerve-ends and 
ganglia may influence the heart in many other ways. One of these is by their action on the 
vagus centre in the medulla oblongata, as shown by the fact that if they stimulate this centre 
the slowing of the heart-beats thereby produced disappears after the vagi are cut. Amongst 
drugs acting in this way are digitalis and aconite (after Boehm and Brunton).] 
[Nature of a Cardiac Contraction.—The question as to whether this is a 
simple contraction or a compound tetanic contraction has been much discussed. 
So much is certain, that the systolic contraction of the heart is of very much 
longer duration (8 to 10 times] than the contraction of a skeletal muscle pro- 
duced by stimulation of its motor nerve. When the sciatic nerve of a nerve- 
muscle preparation is adjusted upon a contracting heart, a simple secondary 
twitch of the limb, and not a tetanic spasm, is produced when the heart (auricle 
or ventricle) contracts. This of itself is not sufficient proof that the systole is 
a simple spasm, for tetanus of a muscle does not in all cases give rise to sec- 
ondary tetanus in the leg of a rheoscopic limb. Thus, a simple “initial” 
contraction occurs when the nerve is applied to a muscle tetanized by the 
action of strychnia, and the contracted diaphragm gives a similar result. The 
question whether the heart can be tetanized has been answered in the negative, 
and as yet it has not been shown that the heart can be tetanized in the same 
way that a skeletal muscle is tetanized.] 
[MacWilliam finds, when the quadriceps extensor cruris contracts to cause the knee-jerk, [Sec. 58. 
102 
CARDIO-PNEUMATIC MOVEMENT. 
that a sound similar to the first sound of the heart is heard. As the former is regarded as a 
simple contraction, it is argued that a simple contraction can produce a muscle-sound. Fredericq 
regards the ventricular systole not as a simple contraction, but as composed of three or more 
fused contractions corresponding to tetanus. This he concludes from a study of cardiograms as 
well as from the electro-motive phenomena of the heart.] 
The peripheral or extra-cardiac nerves (§§ 369 and 370). 
59. CARDIO-PNEUMATIC MOVEMENT.—As the heart within 
the thorax occupies a smaller space during the systole than during the diastole, 
it follows that when the glottis is open air must be drawn into the chest when 
the heart contracts ; whenever the heart relaxes, i. e., during diastole, air must 
be expelled through the open glottis. But we must also take into account the 
degree to which the larger intra-thoracic vessels are filled with blood. These 
movements of the air within the lungs, although slight, seem to be of impor- 
tance in hibernating animals. In animals in this condition the agitation of 
the gases in the lungs favors the exchange of C02 and O in the lungs, and this 
slow current of air is sufficient to aerate the blood passing through the lungs. 
[Ceradini called the diminution of the volume of the entire heart which occurs 
during systole meiocardia, and the subsequent increase of volume, when the 
heart is distended to its maximum, auxocardia.] 
Landois’ cardio-pneumograph, and the curves obtained therewith. A and B, from man; 1 and 
2 correspond to the periods of the first and second heart-sounds ; C, from dog; D, method 
of using the apparatus. 
Fig. 75- 
Method.—A manometricflame may be used. Insert one limb of a Y-tube into the opened 
trachea of an animal, while the other limb passes to a small gas-jet, and connect the other 
tube with the gas supply. The movements of the heart affect the column of gas, and thus 
affect the flame. It may also be done in man by inserting the tube into one nostril, while the 
other nostril and the mouth are closed. [A simpler and less irritating plan is to fill a wide 
curved glass-tube with tobacco smoke, and insert one end of the tube into one nostril while the 
other nostril and the mouth are closed. If the glottis be kept open, and respiration be stopped, 
then the movements of the column of smoke within the tube are obvious. Or a manometer 
containing a drop of a colored fluid may be used under the same conditions.] 
The cardiac pneumograph (fig. 75) consists of a tube (D), about 1 inch in diameter and 
6 to 8 inches in length ; the tube is bent at a right angle, and communicates with a small metal 
capsule about the size of a saucer (T), over which a membrane composed of collodion and castor 
oil. is loosely stretched. To this membrane is attached a glass-rod (H) used as a writing style, 
which records its movements on a (S) moved by clock-work. A small valve (K) is 
placed on the side of the tube (D), which enables the experimenter to breathe when necessary. Sec. 59.] 
INFLUENCE OF RESPIRATORY PRESSURE ON HEART. 
103 
The tube (D) is held in an air-tight manner between the lips, the nostrils being closed, the 
glottis open, and respiration stopped. In the curves (fig. 75, A, B) we observe that— 
(1) At the moment of the first sound (1) the respiratory gases undergo a sharp expiratory 
movement, because at the moment of the first part of the ventricular systole the blood of the 
ventricle has not left the thorax, while venous blood is streaming into the right auricle through 
the venae cavae, and because the dilating branches of the pulmonary artery compress the accom- 
panying bronchi. The blood of the right ventricle has not yet left the thorax, it passes merely 
into the pulmonary circuit. The expiratory movement is diminished somewhat (a) by the mus- 
cular mass of the ventricle occupying slightly less bulk during the contraction, and (/?) owing to 
the thoracic cavity being slightly increased by the fifth intercostal space being pushed forward 
by the cardiac impulse. 
(2) Immediately after (1) there follows a strong inspiratory current of the respiratory gases. 
As soon as the blood from the root of the aorta reaches that part of the aorta lying outside the 
thorax, more blood leaves the chest than passes into it simultaneously through the venae cavae. 
(3) After the second sound (at 2), indicated sometimes by a slight depression in the apex of 
the curve, the arterial blood accumulates, and hence there is another expiratory movement in the 
curve. 
(4) The peripheral wave-movements of the blood from the thorax cause another inspiratory 
movement of the gases. 
(5) More blood flows into the chest through the veins, and the next heart-beat occurs. 
60. INFLUENCE OF THE RESPIRATORY PRESSURE 
ON THE HEART. 
The variation in pressure to which all the intra-thoracic organs are subjected, 
owing to the increase and decrease in the size of the chest caused by the respi- 
ratory movements, exerts an influence on the movements of the heart. Examine 
first the relations in different passive conditions of the thorax, when the glottis 
is open. 
The diastolic dilatation of the cavities of the heart, besides the pres- 
sure of the venous blood and the elastic stretching of the relaxed muscle-wall, 
is fundamentally due to the elastic traction of the lungs. This is stronger 
the more the lungs are distended (inspiration), and is less active the more the 
lungs are contracted (expiration). Hence it follows :— 
(1) When the greatest possible expiratory effort is made (of course, with 
the glottis open), only a small amount of blood flows into the heart; the heart 
in diastole is small and contains a small amount of blood. Hence the systole 
must also be small, thus causing a small pulse-beat. 
(2) On taking the greatest possible inspiration (with the glottis open), and 
therefore causing the greatest stretching of the elastic tissue of the lungs, the 
elastic traction of the lungs is, of course, greatest = 30 mm. Hg, and may 
interfere with the contraction of the thin-walled atria and appendices, in conse- 
quence of which these cavities do not completely empty themselves into the 
ventricles. The heart is in a state of great diastolic distention, and filled with 
blood; nevertheless, in consequence of the limited action of the auricles, only 
small pulse-beats are observed. In several individuals Donders found the pulse 
to be smaller and slower; afterwards it became larger and faster. 
(3) When the chest is in a position of moderate rest, whereby the elastic 
traction is moderate =7.5 mm. Hg, we have the condition most favorable to 
the action of the heart—sufficient diastolic dilatation of the cavities of the heart, 
as well as unhindered emptying of them during systole. 
Voluntary increase or diminution of the intra-thoracic pressure 
affects the action of the heart. 
(1) Valsalva’s Experiment (1740).—If the thorax is fixed in the position 
of deepest inspiration, and the glottis be then closed, and if a powerful expira- 
tory effort be made by bringing into action all the expiratory muscles, so as to 
contract the chest, the cavities of the heart are so compressed that the circulation 
of the blood is temporarily interrupted. In this expiratory phase the elastic 
traction is very limited, and the air in the lungs being under a high pressure 104 
muller’s experiments. 
[Sec. 60. 
also acts upon the heart and the intra-thoracic great vessels. No blood can 
pass into the thorax from without; hence the visible veins swell up and become 
congested, the blood in the lungs is rapidly forced into the left ventricle by the 
compressed air in the lungs, and the blood soon passed out of the chest, so that 
the heart and lungs contain little blood, thus leading to a greater supply of 
blood in the systemic than in the pulmonary circulation and the heart. The 
heart-sounds disappear, and the pulse is absent (E. H. Weber, Donders). 
(2) J. Muller’s Experiment (1838).—Conversely, if after the deepest 
possible expiration the glottis be closed, and the chest be now dilated with a 
great inspiratory effort, the heart is powerfully dilated, the elastic traction of 
the lungs, and the very attenuated air in these organs, act so as to dilate the 
cavities of the heart. More blood flows into the right heart, and, in proportion 
Apparatus for demonstrating the action of expiration (I), and inspiration (II), on the heart and 
blood-stream. P, p, lungs; Id, h, heart; L, /, closed glottis; M, m, manometers; E, e, 
in-going blood-stream, vein; A, a, out-going blood-stream, artery; D, diaphragm during 
expiration; d, during inspiration. 
Fig. 76. 
as the right auricle and ventricle can overcome the traction outwards, the 
blood-vessels of the lungs become filled with blood, and thus partly occupy the 
lung--space. Much less blood is driven out of the left heart, so that the pulse 
may disappear. Hence the heart is distended with blood and the lungs are 
congested, while the aortic system contains a small amount of blood, i. e., the 
systemic circulation is comparatively empty, while the heart and the pulmonary 
vessels are engorged with blood. 
In normal respiration, the air in the lungs during inspiration is under 
slight pressure, while during expiration the pressure is higher, so that these con- 
ditions favor the circulation ; inspiration favors the occurrence of diastole, the 
supply of blood (and lymph) through the venae cavae. In operations where the Sec. 60.] 
FLOW OF FLUIDS THROUGH TUBES. 
105 
axillary or jugular vein is cut, air may be sucked into the circulation during 
inspiration, and cause death. Expiration favors the flow of blood in the aorta 
and its branches, and aids the systolic emptying of the heart. 
The elastic traction of the lungs aids the lesser circulation through the 
lungs; the blood of the pulmonary capillaries is exposed to the pressure of the 
air in the lungs, while the blood in the pulmonary veins is exposed to a less 
pressure, as the elastic traction of the lungs, by dilating the left auricle, favors 
the outflow from the capillaries into the left auricle. The elastic traction of the 
lungs acts slightly as a disturbing agent on the right ventricle, and therefore, 
on the movement of blood through the pulmonary artery, owing to the over- 
powering force of the blood-stream through the pulmonary artery, as against 
the elastic traction of the lungs (Donders). 
The above apparatus (fig. 76) shows the effect of the inspiratory and expiratory movements 
on the dilatation of the heart, and on the blood-stream in the large blood-vessels. The large 
glass vessel represents the thorax; the elastic membrane, D, the diaphragm; P, p, the lungs; 
L, the trachea supplied with a stop-cock to represent the glottis; H, the heart; E, the venae 
cavae; A, the aorta. If the glottis be closed, and the expiratory phase imitated by pushing up 
D as in I, the air in P, P and the heart H are compressed, the venous valve closes, the arterial 
is opened, and the fluid is driven out through A. The manometer, M, indicates the intra- 
thoracic pressure. If the glottis be closed, and the inspiratory phase imitated, as in II,/, p, 
and h are dilated, the venous valve opens, the arterial valve closes; hence, venous blood flows 
from e into the heart. Thus, inspiration always favors the venous stream, and hinders the 
arterial; while expiration hinders the venous, and favors the arterial stream. If the glottis 
L and / be open, the air in P, Y,p,p, will be changed during the respiratory movements D and 
d, so that the action on the heart and blood-vessels will be diminished, but it will still persist, 
although to a much less extent. 
The Circulation of the Blood. 
61. FLOW OF FLUIDS THROUGH TUBES.—Toricelli’s Theorem states that 
the velocity of efflux (v) of a fluid—through an opening at the bottom of a cylindrical vessel— 
is exactly the same as the velocity which a body falling freely would acquire, were it to fall from 
the surface of the fluid to the base of the orifice of the outflow. If h be the height of the pro- 
pelling force, the velocity of efflux is given by the formula— 
The rapidity of outflow increases with increase in the height of the propelling force, h. The 
former occurs in the ratio 1, 2, 3, when h increases in the ratio 1,4, 9, i. e., the velocity of 
efflux is as the square root of the height of the propelling force. Hence it follows that the 
velocity of efflux depends upon the height of the liquid above the orifice of outflow, and not 
upon the nature of the fluid. 
Resistance.—Toricelli’s theorem, however, is only valid when all resistance to the outflow 
is absent; but in every physical experiment such resistance exists. Hence, the propelling force, 
h, has not only to cause the efflux of the fluid, but has also to overcome resistance. These two 
forces may be expressed by the heights of two columns of water placed over each other, viz., by 
the height of the column of water causing the outflow, F, and the height of the column, D, 
which overcomes the resistance opposed to the outflow of the fluid. So that 
v — -[/2gfi (where g = 9.8 metres). 
. 6z. VELOCITY OF THE CURRENT. RESISTANCE.—In the case of a fluid 
flowing through a tube, which it fills completely, we have to consider the propelling force, h, 
causing the fluid to flow through the various sections of the tube. The amount of the propelling 
force depends upon two factors :— 
(i) On the velocity of the current, v; (2) on the pressure (amount of resistance) to which the 
fluid is subjected at the various parts of the tube, D. 
(1) The velocity of the current, v, is estimated—(a) from the lumen, /, of the tube; and (b) 
from the quantity of fluid, q, which flows through the tube in the unit of time. So that v—q : /. 
Both values, q as well as /, can be accurately measured. (The circumference of a circular tube, 
3.14 
whose diameter = «' is 3.14 d. The sectional area (lumen of the tube) is /— —d2). Hav- 
ing in this way determined v, from it we may calculate the height of the column of fluid, F, 
A = F + D. VELOCITY AND RESISTANCE IN TUBES. 
[Sec. 62. 
which will give this velocity, i. e., the height from which a body must fall in vacuo, in order to 
v2 
attain the velocity v. In this case F = where g = the distance traversed by a falling body in 
1 sec. =4.9 metres). 
(2) The pressure, D (amount of resistance), is measured directly by placing manometers at 
different parts of the tube (fig. 78). 
The propelling force at any part of the tube is— 
h = F + D 
v2 
or h + F> {Bonders). 
This is proved experimentally by taking a tall cylindrical vessel, A, of sufficient size, which is 
kept filled with water at a constant level, h. The rigid outflow tube, a b, has in connection with 
it a number of tubes, placed vertically, 1, 2, 3, constituting a piezometer. At the end of the 
tube, b, there is an opening with a short tube fixed in it, from which the water issues to a con- 
stant height, provided the level of h is kept constant. The height to which it rises depends on 
the height of the column of fluid causing the velocity, F. As the pressure in the manometric 
tubes, D1, D2, D3, can be read off directly, the propelling force of the water at the sections of 
the tubes, I, II, III, is— 
At the end of the tube, b, where D4 = o, h=F -)-o, i.e., h = F. In the cylinder itself it is the 
constant pressure, h, which causes the movement of the fluid. It is clear that the propelling 
k = F + D1; F + D2; F + D3. 
Fig. 77- 
Cylindrical vessel filled with water. 
h, height of the column of fluid; 
D, height required to overcome 
the resistance; F, height causing 
the efflux. 
A, cylindrical vessel filled with water; a b, 
outflow tube, along which are placed 
at intervals vertical tubes, i, 2, 3, to 
estimate the pressure. 
force of the water gradually diminishes as we pass from the inflow towards the outflow of the 
tube, b. The water in the pressure-cylinder, falling from the height, h, only rises as high as F 
at b. This diminution of the propelling power is due to the presence of resistances, which oppose 
the current in the tube, i. e., part of the energy is transformed into heat. As the propelling 
force at b is represented only by F, while in the vessel it is h, the difference must be due to the 
sum of the resistances, D — h — F; hence it follows that h — F -)- D. 
Estimation of the Resistance.—When a fluid flows through a tube of uniform calibre, the 
propelling force, h, diminishes from point to point on account of the uniformly acting resistance, 
hence the sum of the resistance in the whole tube is directly proportional to its length. In a. 
uniformly wide tube, fluid flows through each sectional area with equal velocity, hence v and 
also F are equal in all parts of the tube. The diminution which h (propelling force) undergoes 
can only occur from a diminution of pressure D, as F remains the same throughout (and 
h — F -f- D). Experiment with the pressure-cylinder shows that the pressure towards the 
outflow end of the tube gradually diminishes. In a uniformly wide tube, the height of the 
pressure in the manometers expresses the resistances opposed to the current of fluid which it has 
to overcoi?ie in its course from the point investigated to the free orifice of efflux. 
Nature of the Resistance.—The resistance opposed to the flow of a fluid depends upon the 
cohesion of the particles of the fluid amongst themselves. During the current, the outer layer 
of fluid which'is next the wall of the tube, and which moistens it, is at rest. All the other 
layers of fluid, which may be represented as so many cylindrical layers, one inside the other, Sec. 62.] 
FLOW IN CAPILLARY AND ELASTIC TUBES. 
107 
move more rapidly as we proceed towards the axis of the tube, the axial thread or stream being 
the most rapidly moving part of the liquid. On account of the movement of the cylindrical 
layers, one within the other, a part of the propelling energy must be used up. The amount of 
the resistance greatly depends upon the amount of the cohesive force which the particles of the 
fluid have for each other; the more firmly the particles cohere the greater will be the resistance, 
and vice versa. Hence, the sticky blood-current experiences greater resistance than water or 
ether. 
Heat diminishes the cohesion of the particles, hence it also diminishes the resistance to the 
onflow. These resistances are first developed by, and result from, the movement of the particles 
of the fluid, they being, as it were, torn from each other. The more rapid the current, therefore, 
i. e., the larger the number of particles of fluid which are pulled asunder in the unit of time, the 
greater will be the sum of the resistance. As the layer of fluid lying next the tube, and moisten- 
ing it, is at rest, the material which composes the tube exerts no influence on the resistance. 
Tubes of Unequal Diameter.—When the velocity of the current is uniform, the resistance 
depends upon the diameter of the tube—the smaller the diameter the greater the resistance, the 
greater the diameter the less the resistance. The resistance in narrow tubes, however, increases 
more rapidly than the diameter of the tube decreases, as has been proved experimentally. 
In tubes of unequal calibre, at different parts of their course, the velocity of the current varies— 
it is slower in the wide part of the tube and more rapid in the narrow parts. As a general rule, 
in tubes of unequal diameter the velocity of the current is inversely proportional to the diameter 
of the corresponding section of the tube; i. e., if the tube be cylindrical, it is inversely propor- 
tional to the square of the diameter of the circular transverse section. In tubes of uniform 
diameter, the propelling force of the moving fluid diminishes uniformly from point to point, but 
in tubes of tmequal calibre it does not diminish uniformly. As the resistance is greater in 
narrow tubes, of course the propelling force must diminish more rapidly in them than in wide 
tubes. Hence, within the wide parts of the tube the pressure is greater than the sum of the 
resistances still to be overcome, while in the narrow portions it is less than these. 
Tortuosities and bending of the vessels add new resistance, and the fluid presses more 
strongly on the convex side than on the concave side of the bend, and there the resistance to the 
flow is greater than on the concave side. 
Division of a tube into two or more branches is a source of resistance, and diminishes the 
propelling power. When a tube divides into two smaller tubes, of course some of the particles 
of the fluid are retarded, while others are accelerated on account of the unequal velocities of the 
different layers of the fluid. Many particles which had the greatest velocity in the axial layer 
come to lie more towards the side of the tube where they move more slowly; and conversely 
many of those lying in the outer layers reach the centre, where they move more rapidly. Hence, 
some of the propelling force is used up in this process, and the pulling asunder of the particles 
where the tube divides acts in a similar manner. If two tubes join to form one tube, new resist- 
ance is thereby caused, which must diminish the propelling force. The sum of the mean veloci- 
ties in both branches is independent of the angle at which the division takes place (Jacobson). 
If a branch be opened from a tube, the principal current is accelerated to a considerable extent, 
no matter at what angle the branch may be given off. 
63. FLOW IN CAPILLARY TUBES. —Poiseuille proved experimentally that the flow 
in the capillaries is subject to special conditions— 
(1) The quantity of fluid which flows out of the same capillary tube is proportional to the 
pressure. 
(2) The time necessary for a given quantity of fluid to flow out (with the like pressure, 
diameter of tube and temperature), is proportional to the length of the tube. 
(3) The product of the outflow (other things being equal) is as the fourth power of the 
diameter. 
(4) The velocity of the current is proportional to the pressure and to the square of the 
diameter, and inversely proportional to the length of the tube. 
(5) The resistance in the capillaries is proportional to the velocity of the current. 
64. FLOW IN ELASTIC TUBES.—( 1) When an uninterrupted uniform current flows 
through an elastic tube, it follows exactly the same laws as if the tube had rigid walls. If the 
propelling power increases or diminishes, the elastic tubes become wider or narrower, and they 
behave, as far as the movement of the fluid is concerned, as wider or narrower rigid walls. Hamel 
has shown that elastic tubes transmit more fluid when they undergo a rhythmical pulsatory 
movement than when the fluid flows into them under constant pressure. The advantage of 
rhythmical impulses for the onward flow in relation to a fluid in motion, as compared with 
a continuous uniform pressure, seems to be due to the alternate movement keeping the elasticity 
of the arterial walls intact. 
(2) Wave-Motion.—If, however, more fluid be forced in jerks into an elastic tube, i. e., in- 
terruptedly, the first part of the tube dilates suddenly, corresponding to the quantity of fluid [Sec. 64. 
STRUCTURE OF BLOOD-VESSELS. 
propelled into it. The jerk communicates an oscillatory movement to the particles of the fluid, 
which is communicated to all the fluid particles from the beginning to the end of the tube; a 
positive wave is thus rapidly propagated throughout the whole length of the tube. If we imagine 
the elastic tube to be closed at its peripheral end, the positive wave will be reflected from the 
point of occlusion, and it may be propagated to and fro through the tube until it finally dis- 
appears. In such a closed tube a sudden jet of fluid produces only a wave-movement, i. e., 
only a vibratory movement, or an alteration in the shape of the liquid, there being no actual 
translation of the particles along the tube. 
(3) If, however, fluid be pumped interruptedly or by jerks into an elastic tube filled with 
fluid, in which there is already a continuous current, the movement of the current is combined 
with the wave movement. We must carefully distinguish the movement of the current of the 
fluid, i. e., the translation of a mass of fluid through the tube, from the wave-movement, the 
oscillatory movement, or movement of change of form in the column of fluid. In the former 
the particles are actually translated, while in the latter they merely vibrate. The current in 
elastic tubes is slower than the wave-movement, which is propagated with great rapidity. This 
last case obtains in the arterial system. The blood in the arteries is already in a state of con- 
tinual movement, directed from the aorta to the capillaries; by means of the systole of the left 
ventricle a quantity of fluid is suddenly pumped into the aorta, and causes a positive wave, the 
pulse-wave which is propagated with great rapidity to the terminations of the arteries, while 
the current of the blood itself moves much more slowly. 
Rigid and Elastic Tubes.—If a quantity of fluid be forced into a rigid tube under a certain 
pressure, the same quantity of fluid will flow out at once at the other end of the tube, provided 
there be no special resistance. In an elastic tube, immediately after the forcing in of a quantity 
of fluid, at firff only a small quantity flows out, and the remainder flows out only after the 
propelling force has ceased to act. If an equal quantity of fluid be periodically injected into 
a rigid tube, with each jerk an equal quantity is forced out at the other end of the tube, and 
the outflow lasts exactly as long as the jerk or the contraction, and the pause between two 
periods of outflow is exactly the same as between the two jerks or contractions. In an 
elastic tube it is different, as the outflow continues for a time after the jerk; hence it 
follows that a continuous outflow current will be produced in elastic tubes, when the time 
between two jerks is made shorter than the duration of the outflow after the jerk has been 
completed. When fluid is pumped periodically into rigid tubes, it causes a sharp abrupt out- 
flow synchronous with the inflow, and the outflow becomes continuous only when the inflow 
is continuous and uninterrupted. In elastic tubes, an intermittent current under the above con- 
ditions causes a continuous outflow, which is increased with the systole or contraction. 
65. STRUCTURE AND PROPERTIES OF THE BLOOD 
VESSELS.—In the body the large vessels carry the blood to and from the 
various tissues and organs, while the thin-walled capillaries bring the blood into 
intimate relation with the tissues. Through the excessively thin walls of the 
capillaries the fluid part of the blood transudes, to nourish the tissues outside 
the capillaries, so that the capillary wall is permeable to fluids and gases, and, 
we shall see, also to the red and white corpuscles of the blood. [At the same 
time fluids pass from the tissues into the blood. Thus, there is an exchange 
between the blood and the fluids of the tissues. The fluid after it passes into 
the tissues constitutes the lymph, and acts like a stream irrigating the tissue 
elements.] 
I. The arteries are distinguished from veins by their thicker walls, due to 
the greater development of smooth muscular and elastic tissues—the middle 
coat (tunica media) of the arteries is specially thick, while the outer coat (t. ad- 
ventitia) is relatively thin. [When cut across, the walls do not collapse, as is 
the case with the thin-walled veins. The absence of valves is by no means 
a characteristic feature.] 
A typical artery consists of three coats (figs. 79, 80). (x) The tunica intima, or inner 
coat, consists of a layer of [a) irregular, long, fusiform, nucleated, squamous cells forming the 
excessively thin transparent endothelium immediately in contact with the blood-stream. [Like 
other endothelial cells, these cells are held together by a cement substance, which is blackened 
by the action of silver nitrate and subsequent exposure to light.] Outside this lies a 
very thin, more or less fibrous, layer—sub-epithelial layer—in which numerous spindle or 
branched protoplasmic cells lie embedded within a corresponding system of plasma canals. 
Outside this is an elastic lamina (b), basement membrane, or membrana propria, which in the 
smallest arteries is a structureless or fibrous elastic membrane—in arteries of medium size it is Sec. 65.] 
STRUCTURE OF THE ARTERIES. 
a fenestrated membrane (Henle), while in the largest arteries there may be several layers of 
elastic laminte or fenestrated elastic membrane mixed with connective tissue. [In some arteries 
the elastic membrane is distinctly fibrous, the fibres being 
chiefly arranged longitudinally. It can be stripped off, whei 
it forms a brittle elastic membrane, which has a great tend 
ency to curl up at its margins. In a transverse section of r 
middle-sized empty artery it appears as a bright wavy line 
but the curves are produced by the partial collapse of the 
vessel. It forms an important guide to the pathologist, ir 
enabling him to determine which coat of the artery is 
diseased.] In middle-sized and large arteries a few non 
striped muscular fibres are disposed longitudinally between 
the elastic plates or laminae. Along with the circular mus- 
cular fibres of the middle coat, they may act so as to narrow 
the artery, and they may also aid in keeping the lumen ol 
the vessel open and of uniform calibre. 
(2) The tunica media, or middle coat, contains much 
non-striped muscle (e), which in the smallest arteries, some- 
times called arterioles, consists of transversely disposed 
non-striped muscular fibres lying between the endothelium 
and the T. adventitia, while a finely granular tissue with 
few elastic fibres forms the bond of union between them. 
As we proceed from the very smallest to the small arteries, 
the number of muscular fibres become so great as to form a 
well-marked fibrous tube of non-striped muscle, in 
which there is comparatively little connective-tissue. In 
the large arteries the amount of connective-tissue is con- 
siderably increased, and between the layers of fine con- 
nective-tissue numerous (as many as 50) thick, elastic 
fibrous or fenestrated laminse are concentrically arranged. 
A few non-striped fibres lie scattered amongst these, and 
some of them are arranged transversely, while a few have 
an oblique or longitudinal direction. 
The first part of the aorta and pulmonary artery, and the 
retinal arteries, are devoid of muscle. The descending 
aorta, common iliac, and popliteal have longitudinal fibres 
between the transverse ones. Longitudinal bundles lying 
inside the media occur in the renal, splenic, and internal spermatic arteries. Longitudinal bundles 
occur both on the outer and inner surfaces of the umbilical arteries, w'hich are very muscular. 
Fig. 79. 
Coats of a small artery. #, endothe- 
lium ; b, internal elastic lamina; 
c, circular muscular fibres of the 
middle coat; d, the outer coat. 
Fig. 80. 
Transverse section of a small artery, vein, and nerve. A, artery; a, its endothelium ; b, elastic 
lamina; c, muscular coat, with its rod-shaped nuclei; */, adventitia. V, vein ; a, its endo- 
thelium; b, thin elastic lamina; c, thin muscular coat; d, adventitia; f, fat. N, trans- 
verse section of a nerve. 
(3) The tunica adventitia, or outer coat, in the smallest arteries consists of a structureless 
membrane with a few connective-tissue corpuscles attached to it; in somewhat larger arteries 110 
structure of capillaries. 
[Sec. 65. 
there is a layer of fine fibrous elastic tissue mixed with bundles of fibrillar connective-tissue (d). 
In arteries of middle-size, and in the largest arteries, the chief mass consists of bundles of 
fibrillar connective-tissue containing connective-tissue corpuscles. The bundles cross each other 
in a variety of directions, and fat cells often lie between them. Next the media there are 
numerous fibrous or fenestrated elastic lamellae. In medium-sized and small arteries the 
elastic tissue next the media takes the form of an independent elastic membrane (Henle’s 
external elastic membrane). Bundles of non-striped muscle, arranged longitudinally, occur in 
the adventitia of the arteries of the penis, and in the renal, splenic, spermatic, iliac, hypogastric, 
and superior mesenteric arteries. 
[The following tabular statement may facilitate the study of the arterial 
coats :— 
Medium Artery. 
(a) Endothelium. 
(b) Sub-endothelial layer. 
(<r) Elastic lamina. 
Tunica intima 
{Inner coat). 
Composed of layers of smooth muscular fibres disposed 
circularly, and scattered amongst these there are 
sometimes elastic fibres. 
Tunica media 
(Middle coat). 
Tunica adventitia 
{Outer coat). 
Composed of connective-tissue, i, e., white fibrous tis- 
sue mixed with elastic fibres, the latter more abun- 
dant at the inner part of the coat.] 
II. The capillaries (fig. 81), while retaining their diameter, divide and reunite so as to form 
networks, whose shape and arrangement differ considerably in different tissues. As to their size, 
the diameter of the capillaries varies con- 
siderably, but as a general rule it is such as 
to admit freely a single row of blood-cor- 
puscles. In the retina and the muscles the 
diameter is 5-6 fi and in bone-marrow, 
liver, and choroid 10-20 /*. [In the lungs 
the capillaries are rather wider than else- 
where.] The tubes consist of a single 
layer of transparent, excessively thin, nu- 
cleated endothelial cells joined to each 
other by their margins. [Each cell con- 
sists of a flattened nucleated plate, for 
the most part converted into a transparent 
material. In capillaries the nuclei project 
slightly and alternately into the lumen 
of the vessel. The nuclei contain a well- 
marked intra-nuclear plexus of fibrils, like 
other nuclei.] The cells are more fusiform 
in the smaller capillaries and more poly- 
gonal in the larger. The body of the cells 
presents the characters of very faintly 
refractive protoplasm, but it is doubtful 
whether the body of the cell is endowed 
with the property of contractility (p. 
112.) 
If a dilute solution per cent.) of 
silver nitrate be injected into the blood- 
vessels, the cement substance of the endo- 
thelium [and of the muscular fibres as well] is revealed by the presence of the black “ silver 
lines.” The blackened cement substance shows little specks and large black slits at different 
points. It is not certain whether these are actual holes through which colorless corpuscles may 
pass out of the vessels, or are merely larger accumulations of the cement-substance.- [If a 
capillary is examined in a perfectly fresh condition (while living) and without the addition of 
any reagent, it is impossible to make out any line of demarcation between adjacent cells owing 
to the uniform refractive index of the entire wall of the tube.] 
[Arnold called these small areas in the black silver lines when they are large stomata, and 
when small stigmata. They are most numerous after venous congestion, and after the dis- 
turbances which follow inflammation of a part. They are not always present. The existence 
Capillaries. The outlines of the nucleated endo- 
thelial cells with the cement blackened by the 
action of silver nitrate. 
Fig. 81. Sec. 65.] 
STRUCTURE OF VEINS. 
of cement-substance between the cells may also be inferred from the fact that indigo-sulphate 
of soda is deposited in it (Thoma), and particles of cinnabar and China ink are fixed in it, when 
these substances are injected into the blood (•/$>«).] 
Fine anastomosing fibrils derived from non-medullated nerves terminate in small end-buds 
in relation with the capillary wall; ganglia in connection with the nerves of capillaries occur 
only in the region of the sympathetic. 
The small vessels next in size to the capillaries, and continuous with them, have a completely 
structureless covering in addition to the endothelium. 
III. The veins are generally distinguished from the arteries by their lumen 
being wider than the lumen of the corre- 
sponding arteries; their walls are thinner on 
account of the smaller amount of non-striped 
muscle and elastic tissue (the non-striped 
muscle is not unfrequently arranged longi- 
tudinally in veins). [The walls contain 
relatively much more white fibrous and less 
elastic tissue.] They are also more extensile 
(with the same strain). The adventitia is 
usually the thickest coat. The occurrence 
of valves is limited to the veins of certain 
areas (fig. 82, A). [When empty and cut 
across, their walls collapse.] 
Structure.—(1) The Tunica intima consists of a 
layer of shorter and broader endothelial cells, under 
which in the smallest veins there is a structureless 
elastic membrane, sub-epithelial layer, which is 
fibrous in veins somewhat larger in size, but in all 
cases is thinner than in the arteries. [It can scarcely 
be called a lamina. It is rather an elastic basis, com- 
posed of a felted net-work of elastic and white fibres.] 
In large veins it may assume the characters of a 
fenestrated membrane, which is double in some parts 
of the crural and iliac veins. Isolated muscular 
fibres exist in the intima of the femoral and popliteal 
veins. 
(2) The T. media of the larger veins consists of 
alternate layers of elastic and muscular tissue united 
to each other by a considerable amount of connective- 
tissue, but this coat is always thinner than in the cor- 
responding arteries. This coat diminishes in the 
following order in the following vessels :—popliteal, 
veins of the lower extremity, veins of the upper ex- 
tremity, superior mesenteric, other abdominal veins, 
hepatic, pulmonary, and coronary veins. The follow- 
ing veins contain no muscle:—veins of bone, central 
nervous system and its membranes, retina, the superior 
cava, with the large trunks that open into it, the upper 
part of the inferior cava. Of course, in these cases 
the media is very thin. In the smallest veins the 
media is formed of fine connective-tissue, with very 
few muscular fibres scattered in the inner part. 
(3) The T. adventitia is thicker than that of the corresponding arteries; it contains much 
cofinective-tissue, usually arranged longitudinally, and not much elastic tissue. Longitudinally 
arranged muscular fibres occur in some veins (renal, portal, inferior cava near the liver, veins of 
the lower extremities). The valves consist of fine fibrillar connective-tissue with branched 
cells. An elastic network exists on their convex surface, and both surfaces are covered 
by endothelium. The valves contain many muscular fibres (fig. 82). [Ranvier has shown that 
the shape of the epithelial cells on the side over which the blood passes are more elongated 
than on the cardiac side of the valve, where the long axes of the cells are placed transversely.] 
The sinuses of the dura mater are spaces covered with endothelium. The spaces are either 
duplicatures of the membrane, or channels in the substance of the tissue itself. 
Fig. 82. 
A, valves in the saphena vein. B, Longi- 
tudinal section of a vein at the level of 
a valve, a, hyaline layer of the inter- 
nal coat; b, elastic lamina; c, groups 
of smooth muscular fibres divided trans- 
versely; d, longitudinal muscular fibres 
in the adventitia. PROPERTIES OF THE BLOOD-VESSELS. 
[Sec. 65. 
Cavernous spaces we may imagine to arise by numerous divisions and anastomoses of tol- 
erably large veins of unequal calibre. The vascular wall appears to be much perforated and 
like a sponge, the internal space being traversed by threads and strands of tissue, which are cov- 
ered with endothelium on their surfaces, that are in contact with the blood. The surrounding 
wall consists of connective-tissue, which is often very tough, as in the corpus cavernosum, and 
it not unfrequently contains non-striped muscle. 
Cavernous formations of an analogous nature on arteries are the carotid gland of the frog, 
and a similar structure on the pulmonary arteries and aorta of the turtle, and the coccygeal 
gland of man. The last structure is richly supplied with sympathetic nerve-fibres, and is a con- 
voluted mass of ampullated or fusiform dilatations of the middle sacral artery, surrounded and 
permeated by non striped muscle. 
Vasa Vasorum.— [These are small vessels which nourish the coats of the arteries and veins. 
They arise from one part of a vessel and enter the walls of the same, or another vessel at a 
lower level. They break up chiefly in the outer coat, and none enter the inner coat.] In 
structure they resemble other small blood-vessels. The blood circulating in the arterial or 
venous wall is returned by small veins. 
[Lymphatics.—There are no lymphatics on the inner surface of the muscular coat, or under 
the intima in large arteries. They are numerous in a gelatinous layer immediately outside the 
muscular coat, and the same relation obtains in large muscular veins and lymphatic trunks 
(Hoggan).] 
Intercellular Blood-Channels.—Intercellular blood-channels of narrow calibre, and with- 
out walls, occur in the granulation tissue of healing wounds. At first blood-plasma alone is 
found between the formative cells, but afterwards the blood-current forces blood-corpuscles 
through the channels. The first blood-vessels in the developing chick are formed in a similar 
way from the formative cells of the mesoblast. 
Properties of the Blood-Vessels.—The larger blood-vessels are cylin- 
drical tubes with relatively stout walls composed of several layers of various 
tissues, more especially elastic tissue and smooth muscular fibres, and the whole 
is lined by a smooth polished layer of endothelium. One of the most import- 
ant properties is the contractility of the vascular wall, in virtue of which the 
calibre of the vessel can be varied, and therefore the supply of blood to a part 
is altered. The contractility is due to the plain muscular fibres, which are, for 
the most part, arranged circularly. It is most marked in the small arteries, 
and of course is absent where no muscular tissue occurs. The amount and 
intensity of the contraction depend upon the development of the muscular 
tissue; in fact, the two go hand in hand. [If an artery be exposed in the 
living body it soon contracts under the stimulus of the atmosphere acting upon 
the muscular fibres. It may also be made to contract by the application of an 
electrical current, or mechanical stimuli, and in the intact body the vaso-motor 
nerves govern the muscular fibres.] The contraction takes place slowly, lasts a 
long time, and has a long latent period like smooth muscle generally. 
[Action of Drugs on the Vascular System.—Gaskell finds that a very dilute solution of 
lactic acid (1 : 10,000 parts of saline solution), passed through the blood-vessels of a frog, 
always enlarges the calibre of the blood-vessels, while an alkaline solution (1 part sodium 
hydrate to 10,000 saline solution) always diminishes their size, usually to absolute closure, and 
indeed the artificial constriction of the blood-vessels may be almost complete. These fluids are 
antagonistic to each other as far as regards their action on the calibre of the arteries. Dilute 
alkaline solutions act on the heart in the same way. After a series of beats the ventricle stops 
beating, the standstill being in a state of contraction. Very dilute lactic acid causes the ventricle 
to stand still in the phase of complete relaxation. The acid and alkaline saline solutions are 
antagonistic in their action on the ventricle. Cash and Brunton find that dilute acids have a 
tendency to increase the transudation through the vessels and produce oedema of the surrounding 
tissues. They also observed that barium, calcium, strontium, copper, iron, and tin produce con- 
traction of the blood-vessels when solutions of their salts are driven through them, while the 
same effect is produced by very dilute solutions of potassium. Nicotin, atropin, and chloral 
differ in their action according to the dose. In these experiments the effect was ascertained by 
the amount of fluid which flowed out of the vessels in a given time.] If blood containing cer- 
tain drugs be perfused through the blood-vessels of a freshly excised organ, the blood-vessels are 
dilated ; e.g., by amyl nitrite, chloral hydrate, morphia, CO, paraldehyde, kairin, quinine, atropin, 
ferricyanide of potassium (urea and sodic chloride in the renal vessels),—they are contracted Sec. 65.] 
PHYSICAL PROPERTIES OF BLOOD-VESSELS. 
by digitalin, veratria, helleborin (Kobert). Heat causes contraction of the blood-vessels of 
the frog’s mesentery (Gartner). According to Roy the blood-vessels shorten when heated. 
That the capillaries undergo expansion and contraction, owing to varia- 
tions in the size of the protoplasmic elements of their walls, must be admitted. 
Strieker has described capillaries as “ protoplasm in tubes,” and observed that in the tadpole 
they exhibited movements when stimulated. Golubew described an active state of contraction 
of the capillary wall, but he regarded the nuclei as the parts which underwent change. Rouget 
observed the same result in the capillaries of new-born mammals. Tarchanoff found that 
mechanical or electrical stimulation caused a change in the shape and size of the nuclei, so that 
he regards these as the actively contractile parts. [Severini also attaches great importance to 
the contractility of the capillaries, and especially of their nuclei, as influencing the blood-stream. 
Oxygen acts on the nuclei of the capillary wall (membrana nictitans of frog) and causes them 
to swell, while C02 has an opposite effect. The circulation through a lung suddenly filled with 
O or atmospheric air is at first very rapid, but it soon diminishes, while witn C02 the circula- 
tion remains constant.] As the capillaries are excessively thin, soft, and delicate, it is obvious 
that the form of the individual cells must depend to a considerable extent upon the degree to 
which the vessels are filled with blood. In vessels which are distended with blood the en- 
dothelial cells are flattened, but when the capillaries are collapsed they project more or less into 
the lumen of the vessel (Renaut). 
[It is well known that the capillaries present great variations in their diameter at different 
times. As these variations are usually accompanied by a corresponding contraction or dilatation 
of the arterioles, it is usually assumed that the variations in the diameter of the capillaries are 
due to differences of the pressure within the capillaries themselves, viz., to the elasticity of their 
walls. Every one is agreed that the capillaries are very elastic and extensile, but the 
experiments of Roy and Graham Brown show that they are contractile as well as elastic, and 
these observers conclude that, under normal conditions, it is by the contractility of the capillary 
wall as a whole that the diameter of these vessels is changed, and to all appearance their con- 
tractility is constantly in action. “ The individual capillaries (in all probability) contract or 
expand in accordance with the requirements of the tissues through which they pass. The regu- 
lation of the vascular blood-flow is thus more complete than is usually imagined.” It must be 
mentioned, however, that some regard the walls of the capillary as playing purely a passive 
part in the variations of their calibre, although they admit that they are contractile in young 
animals.] 
Physical Properties of Blood-Vessels—Elasticity.—Amongst the 
physical properties of the blood-vessels, elasticity is the most important; 
their elasticity is small in amount, i. e., they offer little resistance to any force 
applied to them so as to distend or elongate them, but it is perfect in quality, 
i. e., the blood-vessels rapidly regain their original size and form after the force 
distending them is removed. [An artery, in virtue of its thick elastic walls, 
when empty or when cut across, does not collapse, but remains open.] 
. According to E. H. Weber, Volkmann, and Wertheim, the elongation of a blood-vessel (and 
moist tissues generally) is not proportional to the weight used to extend it, the elongation being 
relatively less with a large weight than with a small one, so that the curve of extension is nearly 
[or, at least, bears a certain relation to] a hyperbola. According to Wundt, we have not only to, 
consider the extension produced at first by the weight, but also the subsequent “ elastic 
after-effect,” which occurs gradually. The elongation which takes place during the last few 
moments occurs so slowly and so gradually that it is well to observe the effect by means of a 
magnifying lens. Variations from the general law occur to this extent, that if a certain weight 
is exceeded, less extension, and, it may be, permanent elongation of the artery not unfrequently 
occur. K. Bardeleben found, especially in veins elongated to 40 or 50 per cent, of their original 
length, that when the weight employed increased by an equal amount each time, the elongation 
was proportional to the square-root of the weight. This is apart from any elastic after-effect. 
Veins may be extended to at least 50 per cent, of their length without passing the limit of their 
elasticity. 
[Roy experimented upon the elastic properties of the arterial wall. A portion of an 
artery, so that it could be distended by any desired internal pressure, was enclosed in a small 
vessel containing olive oil arranged in the same way as in fig. 72 for the heart. The variations 
of the contents were recorded by means of a lever writing on a revolving cylinder. The instru- 
ment is termed a sphygmotonometer. The aorta and other large arteries are most elastic 
and most distensible at pressures corresponding more or less exactly to their normal blood- 
pressure, while in veins the relation between internal pressure and the cubic capacity is very DIVISION AND LIGATURE OF BLOOD-VESSELS. 
[Sec. 65. 
different. In them the maximum of distensibility occurs with pressures immediately above zero. 
Speaking generally, the cubic capacity of an artery is greatly increased by raising the intra- 
arterial tension, say from zero to about the normal internal pressure which the artery sustains 
during life. Thus in the rabbit, the capacity of the aorta was quadrupled by raising the intra- 
arterial pressure from zero to 200 mm. Hg, while that of the carotid was more than six times 
greater at that pressure than it was in the undistended condition. The pulmonary artery is 
distinguished by its excessive elastic distensibility. Its capacity (rabbit) was increased more 
than twelve times on raising the internal pressure from zero to about 36 mm. Hg. Veins, on 
the other hand, are distinguished by the relatively small increase in their cubic capacity pro- 
duced by greatly raising the internal pressure, so that the enormous changes in the capacity of 
the veins during life are due less to differences in the pressure than to the great differences in 
the quantity of blood which they contain.] 
Pathological.—Interference with the nutrition of an artery alters its elasticity [and that in 
cases where no structural changes can be found]. Marasmus preceding death causes the arteries 
to become wider than normal. In some old people they become atheromatous and even 
calcified. 
[The capillaries by the thinness and permeability of their walls are well adapted for the 
exchange between the fluids and gases of the blood which they contain, and the tissues lying 
outside them; while by their extensibility and elasticity they can adapt their calibre to the 
pressure and quantity of blood within them.] 
[Uses of Elasticity.—The elasticity of the arteries is of the utmost importance in aiding the 
conversion of the unequal movement of the blood in the large arteries into a uniform flow in the 
capillaries. E. H. Weber compared the elastic wall of the arteries with the air in the air- 
chamber of a fire-engine. In both cases an elastic medium is acted upon—the air in the one 
case and the elastic tissue in the other—which in turn presses upon the fluid, propelling it 
onwards continually, while the action of the pump or the heart, as the case may be, is intermit- 
tent. The ordinary spray-producer acts on this principle. A uniform spray or jet is obtained by 
pumping intermittently, but only when the resistance is such as to bring into action the elasticity 
of the bag between the pump and the spray-orifice.] 
Cohesion.—The cohesion of blood-vessels is very great, and in virtue of 
this they are able to resist even considerable internal pressure without giving 
way. The carotid of a sheep is ruptured only when fourteen times the usual 
pressure it is called upon to bear is put upon it (Volkmann). Given a vein 
and an artery of the same thickness, a greater pressure is required to rupture the 
former than the latter. The human carotid or iliac artery resists a pressure of 8 
atmospheres, the veins about the half of this. 
[Division of an Artery.—When an artery is divided in the living 
body, the blood spouts in jets from the proximal cut end of the tube, i. e., the 
heart end. Each jet forms a parabolic curve, and the flow does not cease 
between the jets. If a large artery be severed, the blood may be projected for 
a distance of several feet, this being greater the larger the artery and the 
nearer it is to the heart. A very small amount of blood may flow from the' 
distal cut end. This will depend on the extent to which collateral anastomosis 
takes place.] 
[In the case of a divided vein, the blood flows chiefly from the distal end, 
and it does not come in jets, but as a slow continuous flow. The flow from 
the central end may be almost nil or very slight, but this again depends on 
the amount of collateral circulation.] 
[Ligature of an Artery ruptures the inner coat, and the vessel swells on 
the proximal side of the ligature, while immediately after the ligature is applied 
the distal part of the vessel, i. e., the part beyond the ligature, collapses and 
becomes smaller, and no pulse is felt in it, while the pulse is felt in the proximal 
part right up to the ligatured spot.] 
[Ligature of a Vein causes the vein to swell on the distal side of the 
ligature, while on the proximal or cardiac side it collapses, unless there be a 
very free collateral circulation. No pulse is felt on either side of the ligature. 
These results necessarily follow from the course of the blood-stream—moving 
as it does in opposite directions—in the two vessels.] Sec. 66.] 
VARIOUS SPHYGMOGRAPHS. 
66. INVESTIGATION OF THE PULSE.—[The characters of 
the pulse may be investigated by— 
(1) The eye (inspection). 
(2) The finger {palpation). 
(3) Instruments. 
The examination is usually confined to that part of the radial artery which 
lies immediately above the wrist, with the flexor tendons internal to it, and the 
ridge of the radius on its outer aspect, while the shaft of the radius forms a firm 
bony support against which the artery can be compressed by means of the 
finger. When a finger is placed on the radial artery—covered here only by 
skin and subcutaneous tissue—or on any artery in the living body, one feels a 
distinct sense of resistance, which becomes more marked at regular intervals 
corresponding to each heart-beat. It feels as if the artery expanded somewhat 
under the finger. This is the pulse. One can also feel that in the intervals it 
seems to recede from the finger. In some situations the pulse can be seen. 
No such pulse or beat is felt in a vein.] 
[Two or three fingers are placed over the course of the radial artery, and the 
various phenomena in connection with the pulse are noted. 
It takes much practice for the physician to acquire the tactus 
eruditus, and notwithstanding the value of instruments, every 
physician should make a careful study of the pulse-beat with 
his finger. In order to feel the pulse-beat or to take a pulse- 
tracing, there must be some resistant body, e. g., a bone be- 
hind the artery, and a certain degree of pressure must be 
exerted on the artery.] 
The individual phases of the movement of the pulse can 
only be accurately investigated by the application of instru- 
ments to the arteries. 
(1) Poiseuille’s Box Pulse-Measurer (1829).—An artery is exposed 
and placed in an oblong box filled with an indifferent fluid. A vertical 
tube with a scale attached communicates with the interior of the box. 
The column of fluid undergoes a variation with every pulse-beat. 
(2) Herisson’s Tubular Sphygmometer consists of a glass tube 
whose lower end is covered with an elastic membrane (fig. 83). The tube 
is partly filled with Hg. The membrane is placed over the position of a 
pulsating artery, so that its beat causes a movement in the Hg. Chelius 
used a similar instrument, and he succeeded with this instrument in 
showing the existence of the double beat (dicrotism) in the normal pulse 
(1850). 
(3) Vierordt’s Sphygmograph (1855).—In this, one of the earliest 
sphygmographs, Vierordt departed from the principle of a fluctuating 
fluid column, and adopted the principle of the lever. Upon the artery 
rested a small pad, which moved a complicated system of levers. At 
first he used a straw 6 inches long, which rested on the artery. The point 
of one of the levers inscribed its movements upon a revolving cylinder. 
This instrument was soon discarded. 
(4) Marey’s Sphygmograph consists of a combination of a lever with an elastic spring. 
The elastic spring (fig. 84, A) is fixed at one end, z, free at the other end, and provided with an 
ivory pad, y, which is pressed by the spring upon the radial artery. On the upper surface of the 
pad there is a vertically-placed fine-toothed rod, k, which is pressed upon by a weak spring, e, so 
that its teeth dovetail with similar teeth in the small wheel, t, from whose axis there projects a 
long, light, wooden lever, v, running nearly parallel with the elastic spring. This lever has a 
fine style at its free end, s, which writes upon a smoked plate, P, moved by clockwork, U, in 
front of the style. Marey’s instrument, as improved by Mahomed and others, has been very 
largely used. 
[Its more complete form, as in fig. 85, where it is shown applied to the arm, consists of—(1) 
a steel spring, A, which is provided with a pad resting on the artery, and moves with each 
movement of the artery; (2) the lever, C, which records the movement of the artery and spring 
in a magnified form on the smoked paper, G; (3) an arrangement, L, whereby the exact pressure 
Fig- 83. 
Sphygmometer of 
Herisson and Chelius. 116 
marey’s and dudgeon’s sphygmographs. 
[Sec. 66. 
exerted upon the artery is indicated on the dial, M; (4) the clockwork, H, which moves the 
smoked paper, G, at a uniform rate; (5) a framework to which the various parts of the instru- 
ment are attached, and by means of which the instrument is fastened to the arm by straps, K, K 
(Byrom Bramwell).~\ 
[Application.—In applying the sphygmograph, cause the patient to seat himself beside a 
low table, and place his arm on the double-inclined plane (fig. 85). In the newer form of in- 
strument, the lid of the box is so arranged as to unfold to make this support. The fingers ought 
Scheme of Marey’s sphygmograph. A, spring with ivory pad, y, which rests on the artery; e, 
weak spring pressing k into t; v, writing lever ; P, piece of smoked glass or paper moved 
by clockwork, U; H, screw to limit excursion of A; S, arrangement for fixing the instru- 
ment to the arm of the patient. 
Fig. 84. 
to be semi-flexed. Mark the position of the radial artery with ink. See that the clockwork is 
wound up, and apply the ivory pad exactly over the radial artery where it lies upon the radius, 
fixing it to the arm by the non-elastic straps, K, K. Fix the slide holding the smoked paper 
in position. The best paper to use is that with a very smooth surface, or an enamelled card 
smoked over the flame of a turpentine lamp, over a piece of burning camphor, or over a fan- 
tailed gas-burner. The writing-style is so arranged as to write upon the smoked paper with the 
least possible friction. It is most important to regulate the pressure exerted upon the artery by 
means of the milled head, L. This must be determined for each pulse, but the rule is to gradu- 
Fig. 85. 
Marey’s improved sphygmograph. A, steel spring; B, first lever; C, writing lever; O', its free 
writing end ; D, screw for bringing B in contact with C; G, slide with smoked paper; H, 
clockwork; L, screw for increasing the pressure; M, dial indicating the pressure; Iv, Iv, 
straps for fixing the instrument to the arm, and the arm to the double-inclined plane or 
support. 
ate the pressure until the greatest amplitude of movement of the lever is obtained. Set the 
clockwork going, and a tracing is obtained, which must be “ fixed ” by dipping it in a rapidly 
drying varnish, e. g., photographic. In every case scratch on the tracing with a needle the 
name, date, and amount of pressure employed.] 
[(5) Dudgeon’s Sphygmograph.—This is a convenient form of sphygmograph, although 
Broadbent and Roy regard its results as untrustworthy. The instrument after being carefully 
adjusted upon the radial artery is kept in position by an inelastic strap. The pressure of the 
spring is regulated by the eccentric wheel to any amount from 1 to 5 ounces. As in other Sec. 66.] 
ludwig’s sphygmograph. 
117 
instruments, the tracing paper is moved in front of the writing-needle by means of clockwork. 
The writing levers are so adjusted that the movements of the artery are magnified fifty times 
(fig. 86).] 
[(6) Ludwig’s improved form is a very serviceable instrument (fig. 87).] 
Fig. 86. 
Dudgeon’s sphygmograph. 
(7) Marey’s tambours are also employed for registering the movements of the pulse. They 
are used in the same way as the pansphygmograph. Two pairs of metallic cups (fig. 88, S, S, 
and S', S', Upham’s capsules) are pierced in the middle by thin metal tubes, whose free ends 
are connected with caoutchouc tubes, K and K/. All the four metallic vessels’are covered with 
Fig. 87. 
Ludwig’s sphygmograph. 
elastic membranes. On S and S/ are fixed two knob-like pads, p and p', which are applied to 
the pulsating arteries, and the metal arcs, B and B/, retain them in position. On the other 
tambours are arranged the writing-levers, Z and Z'. Pressure on the one tambour necessarily 
compresses the air, and makes the other, with which it is connected, expand, so as to move the 118 
[Sec. 66. 
ANGIOGRAPH. 
writing-lever. This arrangement does not give absolutely exact results; still, it is very easily 
used, and is convenient. In fig. 88 a double arrangement is shown, whereby one instrument, B, 
may be placed over the heart, and the other, B', on a distant artery. 
Fig. 88. 
Scheme of Brondgeest’s sphygmograph. S, S', receiving and recording (S, S') tambours with 
writing levers, Z and Z/; K, KZ, conducting tubes: p, over heart, p/, over a distant artery. 
(8) Landois’ Angiograph.—To a basal plate (fig. 89), G, G, are fixed two upright supports, 
p, which carry between them at their upper part the movable lever, d, r, carrying a rod bearing a 
pad, e, directed downwards, which rests on the pulse. The short arm carries a counterpoise, d, 
Fig. 89. 
so as exactly to balance the long arm. The long arm has fixed to it at r a vertical 
rod provided with teeth, h, which is pressed against a toothed wheel firmly fixed 
on the axis of a very light writing-lever, e,f which is supported between two up- 
rights, q, hxed to the opposite end of the basal plate, G, G. The writing-lever is equilibrated 
Dy means of a light weight. The writing-needle, £, is fixed by a joint to e, and it writes on the 
olate, t. The first mentioned lever, d, r, carries a shallow cup, Q, just above the pad, into 
which weights may be put to press on the pulse. In this instrument the weight can be measured 
ind varied; the writing-lever moves vertically, and not in a curve as in Marey’s apparatus, 
which greatly facilitates the measuring of the curves (fig. 89). 
Other sphygmographs are used, both in this country and abroad, including that of Sommer- 
jrodt, which is a complicated form of Marey’s sphygmograph, and those of Pond and Mach. 
[Whatever the form of the sphygmograph, the pressure is applied to the artery either by 
means of a spring (Marey, Dudgeon, etc.) or by actual weights which press upon the artery 
[Sommerbrodt, Landois). In Marey’s form the lever moves in an arc of a circle on the paper so 
Scheme of Landois’ angiograph. Sec. 66.] 
SPHYGMOGRAM. 
119 
that the upstroke has always a backward inclination, while in Sommerbrodt’s the lever moves at 
right angles to the paper, and makes a vertical line. Thus the form of the curve obtained will 
vary to a certain extent with the sphygmograph employed. As a matter of fact, the sphygmo- 
graph does not aid one so much in diagnosis as has been claimed for it. It, however, accentuates 
certain phenomena, which cannot be so well studied with the unaided fingers.] 
In every pulse-curve—sphygmogram or arteriogram—we can distin- 
guish the ascending part (ascent) of the curve, the apex, and the descendmg 
part (descent). Secondary elevations scarcely ever occur in the ascent, which 
is usually represented by a straight line, while they are always present in the 
descent (fig. 91). Such elevations occurring in the descent are called cata- 
crotic, and those in the ascent, anacrotic. When the recoil elevation or 
dicrotic wave occurs in a well-marked form in the descent, the pulse is said to 
be dicrotic, and when it occurs twice, tricrotic. 
Measuring Pulse-Curves.—If the smoked surface on which the tracing is inscribed is moved 
at a uniform rate by means of the clockwork, then the height and length of the curve are 
measured by means of an ordinary rule. If we know the 
rate at which the paper was moved, then it is easy to cal- 
culate the duration of any event in the curve. 
Gas-Sphygmoscope.—A small metallic or glass cap- 
sule provided with an inlet and an outlet tube, and closed 
below by a fine membrane, is placed over an artery. The 
inlet tube is connected to a gas supply, and the outlet to a 
rat-tailed gas-burner. The gas-jet responds to every pulse- 
beat. Czermak photcgraphed a beam of light set in motion 
by the movements of the pulse. 
Haemautography.—Expose a large artery of an animal, 
and divide it so that the stream of blood issuing fiom it 
strikes against a piece of paper drawn in front of the blood- 
stream. The curve so obtained (fig. 90) shows, in addition 
to the primary wave, P, a distinct dicrotic wave R, and slight 
vibrations, e. e., due to the variations in the elasticity of the 
arterial wall, which shows that the movements occur in the 
blood itself, and are communicated as waves to the arterial 
wall. By estimating the amount of blood in the various 
parts of the curve, we obtain a knowledge of the amount of 
blood discharged by the divided artery during the svstole 
and diastole (*. e., the narrowing and dilatation) of the 
artery—the ratio is 7 : 10. Thus in the unit of time, during 
arterial dilatation, rather more than twice as much bicod 
flows out as compared with what occurs during arteiial 
contraction. 
67. PULSE-TRACING OR SPHYG- 
MOGRAM.—[The Pulse.—With each systole 
of the heart, a certain quantity of blood is forced 
into the already filled and partially distended 
arteries, the resistance in the vessels is lowest 
between the pulsations, and at this time the arterial tubes are somewhat 
flattened, but with each systole of the left ventricle the pulse-wave, or rather 
the liquid pressure within the vessel, is increased, thus forcing the artery back 
into the circular form. “ The change of shape, from the flattened condition im- 
pressed upon the vessel by the finger or the sphygmograph lever, to the round 
cylindrical shape which it assumes under the distending force of the blood within 
it, constitutes the pulse,” and it indicates the degree and duration of the increased 
pressure in the arterial system caused by the ventricular systole (.Broadbent).~\ 
Analysis.—A sphygmogram or pulse-tracing consists of a series of 
curves (figs. 91, 92) each of which corresponds with one beat of the heart. 
Each pulse-curve consists of— 
1. The line of ascent (a to b in fig. 91). 
2. The apex (P in fig. 94, and b in fig. 91). 
3. The line of descent (b to h in fig. 91). 
Fig. 90. 
Hpemautographic curves of the 
posterior tibial artery of a dog. 
P, primary pulse-wave; R, di- 
crotic wave ; e, e, elevations due 
to elasticity. 120 
ANALYSIS OF A PULSE-TRACING. 
[Sec. 67. 
. (1) The line of ascent, or up stroke, is nearly vertical, and occurs during 
the dilatation of the artery produced by the systole of the left ventricle, when 
the aortic valves are forced open and the ventricular contents are projected 
into the arterial system. [The ascent is a nearly vertical, uninterrupted line, 
A 
Fig. 91. 
B 
A, Pulse-tracing by Dudgeon’s sphygmograph. Sphygmogram of radial artery : pressure 2 oz. 
Each part of the curve between the base of one up-stroke and the base of the next up-stroke 
corresponds to a beat of the heart, so that this figure shows five heart-beats and part of a 
sixth. B, normal pulse-tracing taken with Marey’s sphygmograph : pressure 2]/z oz. 
but in some cases, where the ventricle contracts very suddenly, as occasionally 
happens in aortic regurgitation, it is quite vertical (fig. 97).] 
(2) The apex or percussion wave in a normal pulse is pointed. 
(3) The line of descent is gradual, and corresponds to the diminution of 
diameter or more gradual contraction of the artery after the cesssation of the 
cardiac systole. It is inter- 
rupted by two completely dis- 
tinct elevations of secondary 
waves. Such elevations are 
called “ catacrotic.” The 
more distinct of the two oc- 
curs as a well-marked eleva- 
tion about the middle of the 
descent (R in fig. 94 and f in 
fig. 91); it is called the di- 
crotic wave, or, with ref- 
erence to its mode of origin, 
the “ recoil wave. ” [As the 
descent corresponds to the 
time when blood is flowing 
out of the arteries at the peri- 
phery into the capillaries, its 
direction will depend on the 
rapidity of the outflow. Thus 
it will be more rapid in pa- 
ralysis of the arterioles and very rapid in aortic regurgitation, where, of course, 
much of the blood flows backward into the left ventricle (fig. 97). In this case, 
the artery will recoil suddenly from under the finger or pad of the instrument, 
and this constitutes the “ pulse of empty arteries.”] 
The dicrotic wave, or recoil wave, corresponds to the time following the 
closure of the aortic valves, and is preceded in the descent by a slight depres- 
sion, the aortic notch. 
[The tidal, or pre-dicrotic wave, occurs between the apex and the di- 
crotic wave (fig. 91, d). It occurs on the descent, and during the contraction 
of the ventricle. The tidal wave is best marked in a hard pulse, i. e., where 
the blood-pressure is high, so that it is usually well marked in cirrhotic disease 
of the kidney, accompanied by hypertrophy of the left ventricle.] 
There may be other secondary waves in the lower part of the descent. 
Fig. 92. 
Radial pulse-tracing by Roy and Adami’s method, 
Extra-vascular pressure = 100 mm. Hg. Sec. 67.] 
ORIGIN OF THE DICROTIC WAVE. 
[Respiratory or Base Line.—If a line be drawn so as to touch the bases 
of all the up-strokes, we obtain a straight line, hence called by this name. The 
base line is altered in disease and during forced respiration (§ 74).] 
[Pulse-tracings obtained in different ways from different animals and man 
resemble each other in that they all show an uninterrupted rapid up-stroke, cul- 
minating in the point of the curve which forms the percussion-wave or first 
secondary wave of the pulse. Between the apex and the next small wave is a 
notch, the pre-dicrotic notch immediately by the tidal wave. After this is the 
deeper dicrotic notch, and then the dicrotic wave. This is followed by a more 
or less prominent short wave, between which and the lowest part of the curve 
is a large flattened wave.] 
[Roy and Adami adopt a somewhat different terminology, based on the 
views they hold as to the cause of the several parts of a pulse-tracing. The 
term up-stroke is retained, but the percussion-wave they call the papillary 
wave or first secondary wave. According to them, it is due to the contrac- 
tion of the papillary muscles, and results from the rise of pressure due to con- 
traction of the papillary muscles. The next secondary or tidal wave they call 
outflow remainder wave, and it corresponds in time with the outflow from 
the ventricles, and with it the outflow from the ventricles terminates. After 
this comes the dicrotic notch, which they ascribe to “ the inertia of the blood 
in the aorta and larger arteries, which has gained a certain velocity during the 
period of outflow from the ventricle, and which upon the blood ceasing to 
leave the ventricle necessarily causes a negative wave, commencing at the root 
of the aorta, and propagated in the same direction as the positive wave.” Then 
follows the dicrotic wave, which they ascribe to inertia, and then the long 
slow descent marked by a rounded shoulder, and perhaps another small inertia 
wave.] 
[In some cases, e.g., mitral regurgitation, the pre-dicrotic wave may be present in some 
pulse-beats and absent in others (fig. 93), where the tidal wave is present in the largest pulse, 
and absent in the others, 
while the base line is un- 
even. In mitral stenosis 
the amount of blood dis- 
charged into the left ven- 
tricle frequently varies, 
hence the variations in 
the characters of the ar- 
terial pulse.] 
The pulse-curve indi- 
cates the variations of 
pressure which the blood exerts on the arterial walls, for the lever rises and falls with the 
pressure, hence v. Kries calls it the “ pressure-pulse.” 
68. ORIGIN OF THE DICROTIC WAVE.—The dicrotic, or re- 
coil wave, which is always present in a normal pulse, is caused thus: During 
the ventricular systole a mass of blood is propelled into the already full aorta, 
whereby a positive wave is rapidly transmitted from the aorta throughout the 
arterial system, even to the smallest arterioles, in which this primary wave is 
extinguished. As soon as the semi-lunar valves are closed, and no more blood 
flows into the arterial system, the arteries, which were previously distended by 
the mass of blood suddenly thrown into them, recoil or contract, so that in 
virtue of the elasticity (and contractility) of their walls, they exert a counter- 
pressure upon the column of blood, and thus the blood is forced onwards. 
There is a free passage for it towards the periphery, but towards the centre 
(heart) it impinges upon the already closed semi-lunar valves. This develops 
a new positive wave, which is propagated peripherally through the arteries, 
where it disappears in their finest branches. In those cases where there is- 
Irregular pulse of mitral regurgitation. 
Fig. 93- [Sec. 68. 
122 
THE DICROTIC WAVE. 
sufficient time for the complete development of the pulse-curve (as in the short 
course of the carotids, and in the arteries of the upper arm, but not in those of 
the lower extremity, on account of their length), a second reflected wave may 
be caused in exactly the same way as the first. Just as the pulse occurs later 
i 
ii 
in 
IV 
V 
VI 
VII 
VIII 
IX 
X 
XI 
XII 
XIII 
XIV 
XV 
I, II, III, sphygmograms of carotid artery; IV, axillary; V to IX, radial; X, dicrotic radial 
pulse; XI, XII, crural; XIII, posterior tibial; XLV, XV, pedal. In all the curves P 
indicates apex; R, dicrotic wave ; e, e, elevations due to elasticity; K, elevation caused by 
the closure of the semi-lunar valves of the aorta. 
Fig. 94. 
in the more peripherally placed arteries than in those near the heart, so the 
secondary wave reflected from the closed aortic valves must appear later in the 
peripheral arteries. Both kinds of waves, the primary pulse-wave, the secondary, 
and eventually even the tertiary reflected wave—arise in the same place, and Sec. 68.] 
SOFT AND HARD PULSES. 
123 
take the same course, and the longer the course they have to travel to any part 
of the arterial system, the later they arrive at their destination. 
[Amongst the conditions which favor dicrotism are low blood-pressure and a rapid sharp 
cardiac contraction. When the blood-pressure is low, there is less resistance to the inflow of 
blood at the aorta from the left ventricle, so that its systole occurs sharply, forcing on the blood 
and distending the arterial walls. The elastic coats rebound on the contained blood, and thus 
start a wave from the closed semi-lunar valves.] 
[Roy and Adami have shown that increased depth of the dicrotic notch is obtained “by any 
cause which diminishes the volume of blood which is thrown out by the ventricle at each con- 
traction, and (contrary to the usual teaching on this subject), also by any cause which, cceteris 
paribus, raises the pressure within the systemic arteries. Again, a pulse-wave with greatly 
increased dicrotism may occur with intra-arterial pressures at or above the normal.” There are, 
however, differences between the increased dicrotism of high and of low pressure. From this it 
follows that the mere form of the pulse-wave is not a safe guide to the height of the medium 
arterial pressure.] 
The following points regarding the dicrotic wave have been ascertained 
experimentally, chiefly by Landois :— 
1. The dicrotic wave occurs later in the descending part of the curve, the 
further the artery experimented upon is distant from the heart. Compare the 
curves, fig. 94. 
The shortest accessible course is that of the carotid; where the dicrotic wave reaches its 
maximum 0.35 to 0.37 sec. after the beginning of the pulse. In the upper extremity the apex 
of the dicrotic w'ave is 0.36 to 0.38 or 0.40 sec. after the beginning of the pulse-beat. The 
F>g- 95- 
Schemata of pulse-tracings. 1, normal; 2, low tension and soft pulse; 3, high tension and 
hard pulse; 4, soft pulse fully dicrotic ; 5, very soft pulse and hyperdicrotic ; R, respiratory 
or base line. The dotted line is put in to show the relation of the tidal wave. 
longest course is that of the arteries of the lower extremity. The apex of the dicrotic wave 
occurs 0.45 to 0.52 or 0.59 sec. after the beginning of the curve. It varies with the height of 
the individual. 
2. The dicrotic elevation in the descent is lower, and is less distinct, the fur- 
ther the artery is situated from the heart, so that the. longer the distance which 
the wave has to travel the less distinct it becomes. 
3. It is best marked in a pulse where the primary pulse-wave is short and 
energetic. It is greatest relatively when the systole of the heart is short and 
energetic. 
4. It is better marked the lower the, tension of the blood within the arteries, 
[and is best developed in a soft pulse]. In fig. 94, IX and X were obtained 
when the tension of the arterial was low ; V and VI, medium : and VII with 
high tension. 
[Soft and Hard Pulse.—A soft pulse may be one with low arterial tension; 
in a hard pulse the tension is high. In a soft pulse the dicrotic wave is always 
well marked, and the tidal wave small or absent. In a soft pulse and pulse of 
low tension, if a line be drawn from the apex of the sphygmogram to the lowest 
point of the aortic notch, the tidal wave, if present at all, falls below this line, 
as in the diagram (fig. 95). [Sec. 68. 
124 
SECONDARY ELEVATIONS IN A PULSE-CURVE. 
In a hard pulse the tension is high, and the tidal wave is well marked, extend- 
ing above a line drawn from the apex to the lowest point of the aortic notch.] 
Conditions influencing Arterial Tension.—It is diminished at the beginning of inspira- 
tion ($ 74) by hemorrhage, stoppage of the heart, heat, an elevated position of parts of the body, 
amyl nitrite, nitro-glycerin, and the nitrites generally. [Both drugs accelerate the pulse- 
beats, and produce marked dicrotism; with amyl nitrite the full effect is obtained in from 15 to 
20 sec. after the inhalation of the dose (fig. 96, A, A/), but with nitro-glycerin not until 6 or 7 
min. (fig. 96, B, B') and in the latter case the effects last longer.] It is increased at the 
beginning of expiration by accelerated action of the heart, stimulation of vaso-motor nerves, 
diminished outflow of blood at the periphery, and by inflammatory congestion due to certain 
Fig. 96. 
Pulse-tracings. A, normal; A', one minute after inhalation of amyl nitrite; B, normal; 
W after a dose of nitro-glycerine (Stirling, after Murrell). 
poisons, as lead; compression of other large arterial trunks, action of cold and electricity on the 
small cutaneous vessels, and by impeded outflow of venous blood. When a large arterial trunk 
is exposed, the stimulation of the air causes it to contract, resulting in an increased tension 
within the vessel. In many diseased conditions the arterial tension is greatly increased—[*•£■, 
in Bright’s disease, where the kidney is contracted (“ granular”), and where the left ventricle is 
hypertrophied.] 
In all these conditions increased arterial tension is indicated by the dicrotic wave being less 
high and less distinct, while with diminished arterial tension it is a larger and apparently more 
independent elevation. Moens has shown that the time between the primary elevation and the 
dicrotic wave increases with increase in the diameter of the tube, with diminution of its thickness, 
and when its coefficient of elasticity diminishes. 
[The dicrotic wave is absent or but slightly marked in cases of atheroma and in aortic regurgi- 
tation (fig 97). In this fig. observe also the vertical character of the up-stroke.] 
Elastic Elevations.—Besides the dicrotic 
wave, a number of small less-marked elevations 
occur in the course of the descent in a sphygmo- 
gram (fig. 94, e, e). These elevations are caused 
by the elastic tube being thrown into vibrations 
by the rapid energetic pulse-wave, just as an 
elastic membrane vibrates when it is suddenly 
stretched. The artery also executes vibratory 
movements when it passes suddenly from the dis- 
tended to the relaxed condition. These small 
elevations in the pulse-curve, caused by the elastic 
vibrations of the arterial wall, are called “ elastic elevations” by Landois. 
(1) The elastic vibrations increase in number in one and the same artery 
with the degree of tension of the elastic arterial wall. A very high tension oc- 
curs in the cold stage of intermittent fever, in which case these elevations are 
well marked. 
(2) If the tension of the arterial wall be greatly diminished, these elevations 
may disappear, so that, while diminished tension favors the production of the 
dicrotic wave, it acts in the opposite way with reference to the “ elastic eleva- 
tions.” (3) In diseases of the arterial walls affecting their elasticity, these 
elevations are either greatly diminished or entirely abolished. (4) The farther 
the arteries are distant from the heart, the higher are the elastic elevations. (5) 
When the mean pressure within the arteries is increased by preventing the out- 
Aortic regurgitation. 
Fig. 97- Sec. 68.] 
DICROTIC PULSE. 
125 
flow of blood from them, the elastic vibrations are higher and nearer the apex 
of the curve. (6) They vary in number and length in the pulse-curves obtained 
from different arteries of the body. 
When the arm is held in an upright position, after five minutes the blood-vessels empty them- 
selves, and collapse, while the elasticity of the arteries is diminished. 
69. Dicrotic Pulse.—Sometimes during fever, especially when the tem- 
perature is high, a dicrotic pulse may be felt, each pulse-beat as it were, being 
composed of two beats (fig. 94, X), one beat being large and the other small, 
and more like an after-beat. Both beats correspond to one beat of the heart. 
The two beats are quite distinguishable by the touch. The phenomenon is 
only an exaggerated condition of what occurs in a normal pulse. The sensible 
second beat is nothing more than the greatly increased dicrotic elevation, which, 
under ordinary conditions, is not felt by the finger. 
Conditions for Dicrotism.—The occurrence of a dicrotic pulse is favored (1) by a short 
primary pulse-wave, as in fevers, where the heart beats rapidly. 
(2) By diminished arterial tension. A short systole and diminished arterial blood-pressure 
are the most favorable conditions for causing a dicrotic pulse. [So that dicrotism is best marked 
in a soft pulse (p. 120).] The double beat may be felt only at certain parts of the arterial sys- 
tem, whilst at other parts only a single beat is felt. A favorite site is the radial artery of one or 
other side, where conditions favorable to its occurrence appear to exist. This seems to be due 
to a local diminution of the blood-pressure in this area, owing to the paralysis of its vaso-motor 
nerves (Landois). If the tension be increased by compressing other large arterial trunks or the 
veins of the part, the double beat becomes a simple pulse beat. The dicrotic pulse in fever 
seems to be due to the increased temperature (390 to 40° C.), whereby the arteiy is more dis- 
tended, and the heart-beat is shorter and more prompt. 
Development of the Pulsus dicrotus—P. caprizans; P. monocrotus. 
Fig. 98. 
(3) It is absolutely necessary that the elasticity of the arterial wall be normal. The dicrotic 
pulse does not occur in old persons with atheromatous arteries. 
Monocrotic Pulse.—In fig. 98, A, B, C, we observe a gradual passage of the normal radial 
curve, A, into the dicrotic beat, B, and C, where the dicrotic wave, r, appears as an independent 
elevation. If the frequency of the pulse 
increases more and more in fever, the 
next following pulse-beat may occur in 
the ascending part of the dicrotic wave, 
D, E, F, and it may be even close to the 
apex of the latter (G) (P. caprizans). 
If the next following beat occurs in the 
depression, i, between the primary ele- 
vation, p and the dicrotic elevation, r, the 
latter entirely disappears and the curve, H, assumes what Landois’ calls the “ monocrotic ” type. 
[Degrees of Dicrotism.—When the aortic notch reaches the respiratory or base line, the 
tidal wave having disappeared, the pulse is said to be fully dicrotic (fig. 95). When the aortic 
notch falls below the base line, i. e., below where the up-stroke begins, the pulse is said to be 
hyperdicrotic (figs. 95, 99). This form occurs during high fever (io4°F.), and is usually a 
grave sign, indicating exhaustion and the need for stimulants.] 
Flyperdicrotic pulse. 
Fig. 99. 126 
CHARACTERS OF THE PULSE. 
[Sec. 70. 
70. CHARACTERS OF THE PULSE.—[The three factors con- 
cerned in the production of the pulse are, (1) the action of the heart, (2) the 
elasticity of the large vessels, (3) the resistance in the small arteries and capil- 
laries. Any or all or several of these factors may be modified.] 
(1) Frequency.—According as a greater or less number of beats occurs in a given time, 
e. g., per minute, the pulse is said to be frequent or infrequent. The normal rate, in man = 71 
per minute, and somewhat more in the female; in fever it may exceed 120 (250 have been 
counted by Bowles), while in other diseases it may fall to 40, and even 10 to 15 ; but such 
cases are rare and are probably due to an affection of the cardiac nerves ($ 41). The frequency 
of the pulse is usually increased when the respirations are deeper, but not more numerous, i. e., 
rapid shallow respirations do not affect the frequency of the pulse, but deep respirations do. 
[The frequency may be regular or irregular with regard to time.] 
(2) Celerity or Rapidity.—If the pulse-wave is developed, so that the distention of the artery 
slowly reaches its height, and the relaxation also takes place gradually, we have the p. tardus 
or slow or long pulse; the opposite condition gives rise to the p. celer or quick or short pulse. 
The rapidity of the pulse is increased by quick action of the heart, power of expansion of the 
arterial walls, easy efflux of blood owing to the dilatation of the small arteries, and by nearness 
to the heart. [The quickness has reference to a single pulse beat, the frequency to a number of 
beats.] In a quick pulse, the curve is high and the angle at the apex is acute, while in a slow 
pulse the ascent is low and the angle at the apex is large. 
(3) Conditions affecting the Pulse-rate.—Frequency in Health.—In man the normal 
pulse-rate = 71 to 72 beats per minute, in the female about 80. In some individuals the pulse- 
rate may be higher (90 to 100), in others lower (50), and such a fact must be borne in mind. 
(a) Age 
Beats per 
Minute. 
Newly born, . 130 to 140 
1 year, . . 120 to 130 
2 years, . . 105 
3 “ . . 100 
4 “ • 97 
Beats per 
Minute. 
| 5 years, . . 94 to 90 
10 “ . . about 90 
10 to 15 years, . . 78 
15 to 20 “ . -70 
\ 20 to 25 “ . 70 
Beats per 
Minute. 
25 to 50 years, , . 70 
60 years, ... 74 
80 “ ... 79 
80 to 90 years, over 80 
(b) The length of the body has a certain relation to the frequency of the pulse. The fol- 
lowing results have been obtained by Czarnecki from the formulae of Volkmann and Rameaux :— 
Lengtlf of Body Pulse. 
in cm. Calculated. Observed. 
80 to 90, 90 103 
90 to too, ... 86 91 
IOO to IIO, ... 81 87 
no to 120, ... 78 84 
120 tO I30, ... 75 78 
130 to 140, ... 72 76 
Length of Body Pulse. 
in cm. Calculated. Observed. 
140 to 150, ... 69 74 
150 to 160, ... 67 68 
160 to 170, ... 65 65 
170 to 180, . . . 63 64 
Above 180, ... 60 60 
(r) The pulse-rate is increased by muscular activity, by every increase of the arterial blood- 
pressure, by taking of food, increased temperature, painful sensations, by psychical disturbances, 
and [in extreme debility~\. Increased heat, fever, or pyrexia increases the frequency, and as a 
rule the increase varies with the height of the temperature. [Dr. Aitken states that an increase 
of the temperature of i° F. above 98° F. corresponds with an increase of ten pulse-beats per 
minute; thus— 
Temp. F. Pulse-rate. 
98° ... 60 
990 . . . 70 
IOO° ... 80 
Temp. F. Pulse-rate. ] 
ioi° ... 90 
102° . . . IOO 
IO30 . . .IIO* 
Temp. F. Pulse-rate. 
IO40 . . . 120 
105° . . .130 
1060 . . . 140 
This is merely an approximate estimate]. It is more frequent when a person is standing than 
when he lies down. Music accelerates the pulse and increases the blood-pressure in dogs and 
men. Increased barometic pressure diminishes the frequency. 
The Variation of the Pulse-rate during the day.—3 to 6 A. M. = 61 beats; 8 to ii)4 
A. M. == 74. It then falls towards 2 p. M ; towards 3 (at dinner-time) another increase takes place 
and goes on until 6 to 8 p. M. = 70; and it falls until midnight = 54. It then rises again towards 
2 A. M., when it soon falls again, and afterwards rises as before towards 3 to 6 A. M. Sec. 70.] 
VARIATIONS IN THE CHARACTERS OF THE PULSE. 
127 
[Pulse-rate in Animals.—(Colin.) 
Per Min. 
Elephant, . . 25-28 
Camel, . . 28-32 
Giraffe, • 66 
Horse, . . 36-40 
Ox, . . . 45-50 
Tapir, 43 
Ass, . . . 46-50 
Pig, . 70-80 
Lion, ... 40 
Per Min. 
Lioness, . . 68 
Tiger, 74 
Sheep, . . 70-80 
Goat, . . 70-80 
Leopard, 60 
Wolf (female), . 96 
Hycena, . . 55 
Dog, . 90-100 
Cat, . . . 120-140 
Per Min.. 
Rabbit, . . 120-150 
Mouse, 120 
Goose, no 
Pigeon, 136 
Hen, . 140 
Snake, ... 24 
Carp, ... 20 
Frog, ... 80 
Salamander, . . 77] 
(4) Variations in the Pulse-Rhythm (Allorhythmia).—On applying the fingers to the 
normal pulse, we feel beat after beat occurring at apparently equal intervals. Sometimes in a nor- 
mal series a beat is omitted — pulsus intermittens, or intermittent pulse. [In feeling an inter- 
mittent pulse, we imagine 
or have the impression 
that a beat is omitted. 
This may be due to a re- 
flex arrest of the ventricu- 
lar contraction caused by 
digestive derangement, in 
which case it has no great 
significance ; but if it be 
due to failure of the ven- x r * . - 
tricular action, intermittent pulse is a serious symptom, being frequently present when the 
muscular walls are degenerated]. At other times the beats become smaller and amaller, and 
after a certain time begin as before = p. 
myurus. When an extra beat is intercal- 
ated in a normal series = p. intercurrens. 
The regular alternation of a high and low 
beat= p. alternans (fig. ioo). In the p. 
bigeminus of Traube the beats occur in 
pairs, so that there is a longer pause after 
every two beats (fig. ioi). Traube found 
that he could produce this form of pulse 
in curarized dogs by stopping the artificial 
respira’ion for a long time. The p. trigemius and p. quadrigeminus occur in the same way, 
but the irregularities occur after every third and fourth beat. Knoll found that in animals such 
irregularities of the pulse were apt to occur, as well as great irregularity in the rhythm generally 
when there is much resistance to the circulation, and consequently the heart has great demands 
upon its energy. The same occurs in man where an improper relation exists between the force 
of the cardiac muscle and the work it has to do (Riegel). Complete irregularity of the heart’s 
action is called arhythmia cordis. 
71. VARIATIONS IN THE CHARACTERS OF THE PULSE—Compressi- 
bility.—The relative strength or compressibility of the pulse (p. fortis and debilis), i, e., 
whether the pulse is strong or weak, is estimated by the weight which the pulse is able to raise. 
A sphygmograph, provided with an index indicating the amount of pressure exerted upon the 
spring pressing upon the artery, may be used (fig. 85). In this case, as soon as the pressure 
exerted upon the artery overcomes the pulse-beat, the lever ceases to move. The rveight e7nployed 
indicates the strength of the pulse. [The finger may be, and generally is used. The finger is 
pressed upon the artery until the pulse-beat in the artery beyond the point of pressure is oblit- 
erated. In health it requires a pressure of several ounces to do this. Handheld Jones uses a 
sphygmometer for this purpose. It is constructed like a cylindrical letter-weight, and the 
pressure is exerted by means of a spiral spring which has been carefully graduated.] The pulse 
is hard and soft when the artery, according to the mean blood pressure, gives a feeling of greater 
or less resistance to the finger, and this quite independent of the energy of the individual pulse- 
beats (p. durus and mollis). In estimating the tension of the attery, i. e., whether it is hard or 
soft, it is important to observe whether the artery has this quality only during the pulse-wave, i. e , 
if it is hard during diastole, or whether it is hard or soft during the period of rest of the arterial 
wall. All arteries are harder and less compressible during the pulse-beat than during the period 
of rest, but an artery which is very hard during the pulse beat may be hard also during the 
pause between the pulse-beats; or it may be very soft, as in insufficiency of the aortic valves. 
In the latter case, after the systole of the left ventricle, owing to the incompetency of the aortic 
semi lunar valves, a large amount of blood flows back into the ventricle, so that the arteries are 
Fig. 100. 
Pulsus alternans. 
Pulsus bigeminus. 
Fig. 101. 128 
THE PULSE CURVES OF VARIOUS ARTERIES. 
[Sec. 71. 
thereby suddenly rendered partially empty. [The sudden collapse of the artery gives rise to 
the characteristic “ pulse of unfilled arteries ” (fig. 97), sometimes also called “ Corrigan’s pulse.”] 
Under similar conditions, the volume of the pulse is obvious from the size of the sphvgmo- 
gram, so that we speak of a large and a small or thready pulse (p. magnus and parvus). Some- 
times the pulse is so thready and of such diminished volume that it can scarcely be felt. A 
large pulse occurs in disease when, owing to hypertrophy of the left ventricle, a large amount 
of blood is forced into the aorta. A small pulse occurs under the opposite condition, when a 
small amount of blood is forced into the aorta, either from a diminution of the total amount of 
the blood, or from the aortic orifice being narrowed [aortic stenosis], or from disease of the 
mitral valve; again, where the ventricle contracts feebly, the pulse becomes small and thready. 
Compare the two radials. Sometimes the pulse differs on the two sides, or it may be absent 
•on one side. [The pulse-wave in the two radials is often different when an aneurism is present 
on one side.] 
Angiometer.—Waldenburg constructed a “ pulse-clock” to register the tension, the diameter 
of the artery, and the volume of the pulse upon a dial. It does not give a graphic tracing, the 
results being marked by the position of dn indicator. 
72. THE PULSE CURVES OF VARIOUS ARTERIES.—1. Carotid (fig. 94,1, 
II, III; fig. 94, C and Cj). The ascending part is very steep—the apex of the curve (fig. 94, P) 
is sharp and high. Below the apex there is a small notch—the “ aortic notch ” (fig. 94, K)— 
which depends on a positive wave formed in the root of the aorta, owing to the closure of the 
aortic valves, and propagated with almost wholly undiminished energy into the carotid artery. 
Quite close to this notch, if the curve be obtained with minimal friction, the first elastic vibration 
occurs (fig. 94, II, e). Above the middle of the descending part of the curve is the dicrotic eleva- 
vation, R, produced by the reflection of a positive wave from the already closed semi-lunar valves. 
The dicrotic wave is relatively small on account of the high tension in the carotid artery. After 
this the curve falls rapidly, but in its lowest third two small elevations may be seen. Of these 
the former is due to elastic vibration. The latter represents a second dicrotic wave (fig. 94, III, 
R). Here there is a true tricolism, which is more easily obtained from the carotid on account of 
the shortness of the arterial channel. 
2. Axillary Artery (fig 94, IV). In this curve the ascent is very steep, while in the descent 
near the apex there is a small (aortic) elevation, K, caused by a positive wave, produced by the 
•closure of the aortic valves. Below the middle there is a tolerably high dicrotic elevation, R, 
higher than in the carotid curve; because in the axillary artery the arterial tension is less, and 
permits a greater development of the dicrotic wave. Further on, two or three small elastic vibra- 
tions occur, e, e. 
3. Radial Artery (fig. 94, V to X ; fig. 106, R and RQ. The line of ascent (fig. 94) is toler- 
ably high and sudden—somewhat in the form of a long f. The apex P is well marked. Below 
this, if the tension be high, two elastic vibrations may occur (V, e, e), but if it be low only one 
(VI to IX, e). About the middle of the curve is the well-marked dicrotic elevation, R. This 
wave is least pronounced in a small hard pulse, and when the artery is much distended (fig. 94, 
VII, R); it is larger when the tension is low (fig. 94, IX, R), and is greatest of all when the 
pulse is dicrotic (X. R). Two or three small elastic elevations occur in the lowest part of the 
curve. 
4. Femoral Artery (fig. 94, XI, XII). The ascent is steep and high—the apex of the curve 
is not unfrequently broad, and in it the closure of the aortic 
valves (K) is indicated. The curve falls rapidly towards its 
lowest third. The dicrotic elevation, R, occurs late after the 
beginning of the curve, and there are also small elastic eleva- 
tions (e, e). 
Pedal Artery (fig. 94, XIV, XV), and Posterior Tibial 
(XIII). In pulse-curves obtained from these arteries there are 
well-marked indications that the apparatus (heart) producing 
the waves is placed at a considerable distance. The ascent is 
oblique and low—the dicrotic elevation occurs late. Two elastic 
vibrations (fig. 94, XIV, e, e) occur in the descent, but they are 
very close to the apex, while the elastic vibrations at the lower 
part of the curve are feebly marked. Fig. 102 is from the pos- 
terior tibial. When measured, it gives the following results :— 
Fig. 102. 
Curve of posterior tibial. 
Written by the angio- 
graph upon a vibrating 
plate. 
1 to 2 . . 9.5 
1 to. 3 . . 20 
I to 4 . . 30.5 
i to 6 . . 68 
I vibration is = 0.01613 sec. 
73- Anacrotism.—As a general rule, the line of ascent of a pulse-curve has the form of an f, 
and is nearly vertical. The arterial walls are thrown into elastic vibration by the pulse-beat, and Sec. 72.] 
ANACROTIC AND RECURRENT PULSES. 
129 
the number of vibrations depends greatly upon the tension of the arterial walls. The disten- 
tion of the artery, or what is the same thing, the ascent of the sphygmogram, usually occurs 
so rapidly that it is equal to one elastic vibration. The elongated f shape of the ascent is funda- 
mentally just a prolonged elastic vibration. When the number of vibrations causing the elastic 
variation is small, and when the line of ascent is prolonged, two elevations occasionally occur in 
the line of ascent. Such a condition may occur normally (fig. 94, VIII, at 1 and 2; X, at 1 and 
2). When a series of closely-placed elastic vibrations occur in the upper part of the line of ascent, 
so that the apex appears dentate and forms an angle with the line of ascent, then the condition 
becomes one of anacrotism (fig. 103, a, a,), which, when it is so marked, may be characterized 
as pathological. Anacrotism of the pulse occurs when the time of the influx of the blood is 
longer than the time occupied by an elastic vibration. Hence it takes place :— 
(1) In dilatation and hypertrophy of the left ventricle, e. g., fig. 103, A, a tracing from 
the radial artery of a man suffering from contracted kidney, the large volume of blood expelled 
with each systole requires a long time to dilate the tense arteries. 
(2) When the extensibility of the arterial wall is diminished, even the normal amount of 
blood expelled from the heart at every systole requires a long time to dilate the artery. This 
occurs in old people where the arteries tend to become rigid, e. g., in atheroma. Cold also 
stimulates the arteries so that they become less extensile. Within one hour after a tepid bath, 
the pulse assumes the anacrotic form (fig. 103, D) [G. v. Liebig). 
(3) When the blood stagnates in consequence of great diminution in the velocity of the blood- 
stream, as occurs in paralyzed limbs, the volume of blood propelled into the artery at every 
systole no longer produces the normal distention of the arterial coats, and anacrotic notches 
occur (fig. 103, B). 
(4) After ligature of an artery, when blood slowly reaches the peripheral part of the vessel 
through a relatively small collateral circulation, it also occurs. If the brachial artery be com- 
pressed so that the blood slowly reaches the radial, the radial pulse may become anacrotic. 
A 
B 
C 
D 
Anacrotic radial pulse-tracings, a, a, the anacrotic parts. 
Fig. 103. 
It often occurs in stenosis of the aorta, as the blood has difficulty in getting into the aorta (fig. 
103, C). 
Recurrent Pulse.—If the radial artery be compressed at the wrist, the 
pulse-beat reappears on the distal side of the point of pressure through the 
arteries of the palm of the hand (Janand, Neiderf). The curve is anacrotic, 
and the dicrotic wave is diminished, while the elastic elevations are increased. 
(5) A special form of anacrotism occurs in cases of well-marked insufficiency of the aortic 
valves. Practically, in these cases, the aorta remains permanently open. The contraction of 
the left auricle causes in the blood a wave-motion, which is at once propagated through the 
open mouth of the aorta into the large blood-vessels. This wave is followed by the wave caused 
by the contraction of the hypertrophied left ventricle, but of course the former wave is not so 
large as the latter. In insufficiency of the aortic valves, the auricular wave occurs before the 
ventricular wave in the ascending part of the curve. The auricular is well marked only in the 
large vessels, for it soon becomes lost in the peripheral vessels. Fig. 104, I, was obtained from 
the carotid of a man suffering from well-marked insufficiency of the aortic valves, with con- 
siderable hypertrophy of the left ventricle and the left auricle. The ascent is steep, caused by the 
force of the contracting heart. In the apex of the curve are two projections; A is the anacrotic 
auricular wave, and V is the ventricular wave. Fig. 104, II, is a curve obtained from the sub- 
clavian artery of the same individual. In the femoral artery the auricular projection is only 
obtained when the friction of the writing-style is reduced to the minimum, and when it occurs 
it immediately precedes the beginning of the ascent (fig. 98, III, a). The pulse-curve, in cases 
of aortic insufficiency, is also characterized by—(1) its considerable height; (2) the rapid fall 
of the lever from the apex of the curve, because a large part of the blood which is forced into 
the aorta regurgitates into the left ventricle when the ventricle relaxes; (3) not unfrequently a 
projection occurs at the apex, due to the elastic vibration of the tense arterial wall; (4) the 
dicrotic wave (R) is small compared with the size of the curve itself, because the pulse-wave, 130 
INFLUENCE OF RESPIRATION ON THE PULSE. 
[Sec. 73. 
owing to the lesion of the aortic valves, has not a sufficiently large surface to be reflected from 
(fig. 97). The great height of the curve is explained by the large amount of blood projected 
nto the aortic system by the greatly hypertrophied and dilated ventricle. 
74. INFLUENCE OF RESPIRATION ON THE PULSE- 
CURVE.—The respiratory movements influence the pulse in two different 
ways—(1) in a purely physical way. Stated broadly, the blood-pressure is 
lowest at the beginning of inspiration and highest at the beginning of expira- 
tion ; but when we consider the effect on the pulse-curve, it is found that it 
varies with the depth, rapidity, and ease of respiration ; (2) the respiratory 
I. 
II. 
Fig 104. 
III. 
movements are accompanied by stimulation of the vasomotor centre, which 
produces variations of the blood-pressure. 
1. Normal Respiration.—Fig. 105 shows what sometimes, but by no 
means always, happens. During inspiration, owing to the dilatation of the 
thorax, more arterial blood is retained within the chest, while at the same time 
Venous blood is sucked into the right auricle by the inspiration of the thorax; 
as a consequence of this, at first the tension in the arteries must be less during 
inspiration. The diminution of the chest during expiration favors the flow 
in the arteries, while it retards the flow of the venous blood in the venae cavae, 
two factors which raise the tension in the arterial system. The expiration pre- 
I, II, III, curves with anacrotic elevations, a, in insufficiency of the aortic valves. 
Influence of the respiration upon the pulse. J, inspiration; E, expiration. 
Fig. 105. 
ceding an inspiration causes less blood to flow to the heart, hence the contrac- 
tions of the heart at the beginning of inspiration do not fill the aorta so full; 
the opposite result obtains with the inspiration preceding the expiration. The 
difference of pressure explains the difference in the form of the pulse-curve 
obtained during inspiration and expiration, as in fig. 105 and fig. 94, I, III, IV, 
in which J indicates the part of the curve which occurred during inspiration, 
and E the expiratory portion. The following are the points of difference : — 
(1) The greater distention of the arteries during expiration causes all the parts 
of the curve occurring during this phase to be higher; (2) the line of ascent is 
lengthened during expiration, because the expiratory thoracic movement helps Sec. 74.] 
VALSALVA AND MULLER’S EXPERIMENTS. 
to increase the force of the expiratory wave; (3) owing to the increase of the 
pressure, the dicrotic wave must be less during expiration ; (4) for the same 
reason the elastic elevations are more distinct and occur higher in the curve 
near its apex. The frequency of the pulse is slightly less during expiration 
than during inspiration. 
2. This purely mechanical effect of the respiratory movements is modified by 
the simultaneous stimulation of the vasomotor centre which accompanies 
these movements. At the beginning of inspiration the blood-pressure in the 
arteries is lowest, but it begins to rise during inspiration, and increases until 
the end of the inspiratory act, and reaches its maximum at the beginning of 
expiration ; during the remainder of the expiration the blood-pressure falls until 
it reaches its lowest level again at the beginning of inspiration (compare d 
85,/); the pulse-curves are similarly modified, and exhibit the signs of greater 
or less tension of the arteries corresponding to the phases of the respiratory 
movements. [There is, as it were, a displacement of the blood-pressure curve 
relative to the respiratory curve.] 
Forced Respiration.—With regard to the effect produced on the pulse- 
curve by a powerful expiration and a forced inspiration, observers are by no 
means agreed. 
Valsalva’s Experiment.—Strong expiratory pressure is best produced by 
closing the mouth and nose, and then making a great expiratory effort (§ 60); 
at first there is increase of the blood-pressure, while the form of the pulse-waves 
resembles that which occurs in ordinary expiration, the dicrotic wave being less 
developed; but, when the forced pressure is long continued, the pulse-curves 
have all the signs of diminished tension. The effect is due to the action of the 
vasomotor centre, which is affected reflexly from the pulmonary nerves. We 
must assume that forced expiration, such as occurs in Valsalva’s experiment, 
acts by depressing the activity of the vasomotor centre (§371, II.). Coughing, 
singing, and declaiming act like Valsalva’s experiment, while the frequency of 
the pulse is increased at the same time. After the cessation of Valsalva’s ex- 
periment, the blood-pressure rises above the normal state (Sommerbrodt) almost 
as much as it fell below it, the normal condition being restored within a few 
minutes (.Lenzmann). 
Muller’s Experiment.—When the thorax is in the expiratory phase, close 
the mouth and nose, and take a deep inspiration so as forcibly to expand the 
chest (§ 60). At first the pulse-curves have the characteristic signs of dimin- 
ished tension, viz., a higher and more distinct dicrotic wave; then the tension 
can, by nervous influences, be increased, just as in fig. 106, where C and R are 
tracings taken from the carotid and radial arteries respectively, during Muller’s 
experiment, in which the dicrotic waves r, r, indicate the diminished tension 
in the vessels. In Q and Rx, taken from the same person during Valsalva’s 
experiment, the opposite condition occurs. 
Compressed Air.—On expiring into a vessel resembling a spirometer (see Respiration), 
(Waldenburg’s respiration apparatus), and filled with compressed air, the same result is obtained 
as in Valsalva’s experiment—the blood-pressure falls and the pulse-beats increase; conversely 
the inspiration from this apparatus of air under less pressure acts like Muller’s experiment, i. e., 
it increases the effect of the inspiration, and afterwards increases the blood-pressure, which may 
either remain increased on continuing the experiment, or may fall (Lenzmann). 
The inspiration of compressed air diminishes the mean blood-pressure (Zuntz), and the after- 
effect continues for some time. The pulse is more frequent both during and after the experi- 
ment. Expiration in rarefied air increases the blood-pressure. The effects which depend upon 
the action of the nervous system do not occur to the same extent in all cases. Exposure to 
compressed air in a pneumatic cabinet lowers the pulse-curve, the elastic vibrations become 
indistinct, and the dicrotic wave diminishes and may disappear (v. Vivenot). The heart’s beat 
is slowed, and the blood-pressure raised (Bert). Exposure to rarefied air causes the opposite 
result, which is a sign of diminished arterial tension. INFLUENCE OF PRESSURE ON THE PULSE-CURVE. 
[Sec. 74. 
Pulsus Paradoxus.—Under pathological conditions, especially when there is union of the 
heart or its large vessels with the surrounding parts, the pulse during inspiration may be 
extremely small and changed, or may even be absent, while it is increased in expiration (fig. 107). 
This condition has been called pulsus paradoxus (Griesinger, Kussmaul). It depends upon 
a diminution of the arterial lumen during the inspiratory movement [as in contraction of the air- 
passages, and in cases of pericardial adhesions]. Even in health it is possible by a change of 
the inspiratory movement to produce the p. paradoxus (Riegel, Sommerbrodt). 
75. INFLUENCE OF PRESSURE ON THE PULSE-CURVE. —It is most im- 
portant to know the actual pressure which is applied to an artery while a sphygmogram is 
being taken. The changes affect the form of the curve as well as the relation of individual parts 
C, curve from the carotid, and R, radial, during Muller’s experiment; Cj and Rj during 
Valsalva’s experiment. Curves written on a vibrating surface. 
Fig. 106. 
thereof. In fig. 108, a, b, c,d, e, are radial curves; a was taken with minimal pressure, b with 
100, c, 200, d 250, and e 450 grams pressure, while A, B, C, D show the relations as to the time 
of occurrence of the individual phenomena where the weight was successively increased. The 
study of these curves yields the following results: (1) When the weight is small, the dicrotic 
wave is relatively less; the whole curve is high; (2) with a moderate weight (100 to 200 grams) 
the dicrotic wave is best marked, the whole curve is somewhat lower; (3) on increasing the 
weight the size of the dicrotic wave again diminishes; (4) the fine elastic vibrations preceding 
the dicrotic wave appear first when a weight of 220 to 300 grams is used; (5) the rapidity of the 
pulse changes with increasing weight, the time occupied by the ascent becoming shorter, the 
descent becoming longer; (6) the height of the entire curve decreases as the weight increases. 
In every sphygmogram the pressure under which it was obtained ought always to be stated. 
Fig. 107. 
Pulsus paradoxus (after Kussmaut). E, expiration; J, inspiration. 
In fig. 108, A, B, are curves obtained from the radial artery of a healthy student. The pressure 
exerted upon the artery for A was ioo; B, 220 grms. (1 vibration = 0.01613 sec.). 
If pressure be exerted upon an artery for a long time, the strength of the pulse is gradually 
increased. If, after subjecting an artery to considerable pressure, a lighter weight be used, not 
unfrequently the pulse-curve assumes the form of a dicrotic pulse, owing to the greater develop- 
ment of the dicrotic elevation. When strong pressure is applied, the blood is forced to find its 
way through collateral channels. When the chief artery ceases to be compressed, the total area 
is, of course, considerably and suddenly enlarged, which results in the production of a dicrotic 
elevation. Fig. 94 X, is such a dicrotic curve obtained after considerable pressure had been 
applied to the artery. Sec. 76.] 
TRANSMISSION OF PULSE-WAVES. 
133 
76. TRANSMISSION OF PULSE-WAVES. —The pulse-wave pro- 
ceeds throughout the arterial system from the root of the aorta, so that the pulse 
is felt sooner in parts lying near the heart than in the peripheral arteries. E. H. 
Weber calculated the velocity of the pulse-wave as 9.240 meters 
feet] per second, from the difference in time between the pulse in the external 
maxillary artery and the dorsal artery of the foot. Czermak showed that the 
elasticity was not equal in all the arteries, so that the velocity of the pulse-wave 
cannot be the same in all. The pulse-wave is propagated more slowly in the 
arteries with soft extensile walls than in arteries with resistant and thick walls, so 
that it is transmitted more rapidly in the arteries of the lower extremities than 
in those of the upper. It is still slower in children. 
77. PULSE-WAVE IN ELASTIC TUBES.—Waves similar to the pulse may be pro- 
duced in elastic tubes. (1) According to E. H. Weber the velocity of propagation of the waves 
is 11.205 metres per sec. ; according to Donders, 11-13 metres (34-42 feet). (2) According to 
E. H. Weber increased internal tension causes only an inconsiderable decrease; Rive found a 
great decrease ; Donders found no obvious difference; while Marey found an increased velocity. 
(3) Donders found the velocity to be the same in tubes 2 mm. in diameter as in wider tubes, but 
Marey believes that the velocity varies when the diameter of the tube changes. (4) The velocity 
Fig. 108 
Various forms of curves (radial) obtained by gradually increasing the pressure 
is less, the smaller the elastic coefficient. (5) The velocity increases with increased thickness ot 
the wall, while it diminishes when the specific gravity of the fluid increases. 
Moens has recently formulated the following laws as to the velocity of propagation of waves 
in elastic tubes : (1) It is inversely proportional to the square root of the specific gravity of the 
fluid; (2) it is as the square root of the thickness of the wall, the lateral pressure being the 
same; (3) it is inversely as the square root of the diameter of the tube, the lateral pressure being 
the same; (4) it is as the square root of the elastic coefficient of the wall of the tube, the lateral 
pressure being the same ( Valentin). 
(A) The velocity of the wave is 11.809 metres per second. 
(B) The intra-vascularpressure has a decided influence on the velocity; thus, in the tube, 
A, with 18 cm. (Hg) pressure, the velocity per metre = 0.093 second, while with 21 cm. pres- 
sure (Hg) = 0.095 second per metre. 
(C) The specific gravity of the liquid influences the velocity of the pulse-wave. In mercury 
the wave is propagated four times more slowly than in water. 
(D) The velocity in a tube which is more rigid and not so extensile is greater than in a tube 
which is easily distended. 
78. VELOCITY OF THE PULSE-WAVE IN MAN.—Landois obtained the follow- 
ing results in a student:—Difference between carotid and radial = 0.074 second (the distance 
being taken as 62 centimetres ); carotid and femoral = 0.068 second ; femoral (inguinal region) 
and posterior tibial — 0.097 second (distance estimated at 91 centimetres). [Waller obtained 
between the heart and carotid o. 10 second; heart and femoral,0.18 sec.; heart and dorsalis 
pedis, 0.22 ] 134 
VELOCITY OF THE PULSE-WAVE. 
[Sec. 78. 
The velocity of the pulse-wave in the arteries of the upper extremi- 
ties — 8.43 metres per second, and in those of the lower extremity 9.40 metres 
per second, [/. <?., about 30 feet per second.] The velocity is greater in the 
less extensile arteries of the lower extremities than in those of the upper limb. 
For the same reason it is less in the peripheral arteries and in the yielding 
arteries of children (Czerniak). 
E. H. Weber estimated the velocity at 9.24 metres per second; Garrod, 9-10.8 metres; 
Grashey, 8.5 metres; Moens, 8.3 metres,and with diminished pressure during Valsalva’s experi- 
ment 7.3 metres ($ 60, § 74). 
Influencing Conditions.—In animals, hemorrhage, slowing of the heart produced by 
stimulation of the vagus (Moens), section of the spinal cord, deep morphia-narcosis, and dilata- 
tion of the blood vessels by heat, produce slowing of the velocity, while stimulation of the 
spinal cord accelerates it (Grunmach). 
The wave-length of the pulse-wave is obtained by multiplying the 
duration of the inflow of blood into the aorta — 0.08 to 0.09 second (§ 51), 
by the velocity of the pulse-wave. 
Method.—Place the knobs of two tambours (fig. 88) upon the two arteries to be investigated, 
or place one over the apex-beat and the other upon an artery. These receiving tambours are 
connected with two registering tambours, as in Brondgeest’s pansphygmograph (§ 67, fig. 88), 
so that their writing-levers are directly over each other, and so arranged as to write simultane- 
ously on one vibrating plate attached to a tuning-fork. [Or they may be made to write upon a 
revolving cylinder, whose rate of movement is ascertained by causing a tuning-fork of a known 
rate of vibration to write under them.] The apparatus is improved by using rigid tubes and fill- 
ing them with water, in which all impulses are rapidly communicated. In arteries which are 
distant from each other, or in the case of the heart and an artery, the two knobs of the 
receiving tambours may be connected by means of a Y-tube with one writing lever. In fig. 109, 
B is a curve from the radial artery taken in this way. In it v H P indicates contraction of the 
ventricle; II, the apex of the ventricular contraction; P, the primary apex of the radial curve ; 
v, the beginning of the ventricular contraction ; p, of the radial pulse. A is the curve of the 
radial artery alone. From these curves it is evident that in 
this instance nine vibrations occur between the beginning of 
the ventricular contraction and the beginning of the pulse 
in the radial artery =0.15 sec. 
Fig. 109. 
A, curve of radial artery on a vibrating surface (1 vib. = 0.01613 sec.); P, apex of curve; <?, e, 
elastic vibrations; R, dicrotic wave. B, curve of same radial taken along with the heart- 
beat ; v, H, P, contraction of the ventricle. 
In fig. no the difference between the carotid and the posterior tibial pulse = 0.137 sec. 
Pathological.—In cases of diminished extensibility of the arteries, e.g., in atheroma ($ 77, D), 
the pulse wave is propagated more rapidly. Local dilatations of the arteries, as in aneurisms, 
cause a retardation of the wave, and a similar result arises from local constrictions. Relaxation 
of the walls of the vessels in high fever retards the movement (Hamernjk). 
79. OTHER PULSATILE PHENOMENA.—1 In the mouth and nose, when they 
are filled with air, and the glottis closed, pulsatile phenomena (due to the arteries in their soft 
parts), may be found communicating a movement to the contained air. The curves obtained are 
relatively small, and closely resemble the curve of the carotid. A similar pulse is obtained in 
the tympanum with intact membrana tympani, and when the soft parts of the tympanum are 
congested (Schwartze, Troltsch). 
2. Entoptical Pulse.—After violent exercise, an illumination, corresponding to each pulse- 
beat, occurs on a dark optical field. When the optical field is bright, an analogous darkening 
occurs. The ophthalmoscope occasionally reveals pulsation of the retinal arteries (Jager), 
which becomes marked in insufficiency of the aortic valves. 
3. Pulsatile Muscular Contraction.—The orbicularis palpebrarum muscle contracts under Sec. 79.] 
PULSATILE PHENOMENA IN THE BODY. 
135 
similar conditions synchronously with the pulse; and it is perhaps due to the pulse-beat 
exciting the sensory nerves reflexly. The Brothers Weber found that not unfrequently, while 
walking, the step and pulse gradually and involuntarily coincide. 
4. When the legs are crossed as one sits in a chair, the leg which is supported is raised with 
each pulse beat, and it gives also a second or dicrotic elevation. 
5. If, while a person is quite quiet, the incisor teeth of the lower jaw be made just to touch 
the upper incisors very lightly, we detect a double beat of the lower against the upper teeth, 
owing to the pulse-beat in the external maxillary artery raising the lower jaw. The second 
elevation is due to the closure of the semi-lunar valves, and not to a dicrotic wave. 
6. Brain and Fontanelles.—The large arteries at the base of the brain communicate a 
movement to it, while similar movements occur with respiration—rising during expiration and 
falling during inspiration. These movements are visible in the fontanelles of infants. The 
respiratory movements depend upon variations in the amount of blood in the veins of the 
cranial cavity, and also upon the respiratory variations of the blood-pressure. 
7. Amongst pathological phenomena are (a) the beating in the epigastrium, e. g., in hyper- 
trophy of the right or left ventricle, caused, it may be, by deep insertion of the diaphragm, and 
it may be, partly, by the beating of a dilated abdominal aorta or coeliac axis. 
(b) Aneurisms or abdotninal dilatations of the arteries cause an abnormal pulsation, while 
they produce a slowing in the velocity of the pulse-wave in the corresponding artery. Hence 
the pulse appears later in such an artery than in the artery on the healthy side. Hypertrophy 
and dilatation of the left ventricle cause the arteries near the heart to pulsate strongly. In the 
analogous condition of the right ventricle, the beat of the pulmonary artery may be seen and 
felt in the second left intercostal space. 
Fig. no. 
Curves of the carotid and posterior tibial taken simultaneously with Brondgeest’s pansphygmo- 
graph writing upon a vibrating-plate attached to a tuning-fork. The arrows indicate the 
identical moment of time in each curve. 
8o. VIBRATIONS OF THE BODY DUE TO THE HEART.—The beating of 
the heart and large arteries communicates compound vibrations to the body as a whole. If a 
person be placed in an erect attitude in the scale-pan of a large balance, the index oscillates, 
and its movements coincide with the heart’s movements [Gordon). 
Method.—Take a long four-sided box, K, open at the top, and arrange several coils, a, b, 
of stout caoutchouc tubing round one end (fig. hi). A wooden board, B, is so placed that it 
rests with one end on the caoutchouc tubing, and with the other on the narrow end of the box. 
The person to be experimented upon, A, stands vertically and firmly on this board. A receiv- 
ing tambour, /, is placed against the surface of the board next the elastic tube, which registers 
the vibrations of the foot-support. Fig. Ill is a curve showing such vibrations, each heart-beat 
being followed in this case by four oscillations. To ascertain the relations and causes of these 
vibrations, it is necessary to obtain, simultaneously, a tracing of the heart and the vibratory 
curve. For this purpose use the two tambours of Brondgeest’s pansphygmograph (§ 67, 76), 
placing one knob or pad over the heart and the other on the foot-support, and allow the 
writing-tambours to inscribe their vibrations on a glass plate attached to a tuning-fork 
( Gordon). 
In the lower or cardiac impulse curve (fig. 111), the rapidly-rising part is due to the ventricular 
systole. It contains eight vibrations (1 vib. = 0.01613 sec). The beginning of the ventricular 
systole is indicated in the fig. by -36, -3, -17. 
If the corresponding numbers in the upper or vibratory curve are studied, it is obvious that 
at the moment of ventricular systole the body makes a downward vibratioti, i. e., it exercises 
greater pressure upon the foot-support. Gordon interprets his curve as giving exactly the oppo- 
site result. This downward motion, however, lasted only during five vibrations of the tuning- 
fork ; during the last three vibrations, corresponding to the systole, there is an ascent of the 
body corresponding to a less pressure upon the foot-plate. When the ventricle empties itself, it 
undergoes a movement in a downward and outward direction—Gutbrodt’s “ reaction impulse.” CAUSE OF THE BLOOD CURRENT. 
[Sec. 80. 
In the upper curve analogous numbers are employed to indicate the vibrations occurring 
simultaneously, viz., -28, -11, -10. The closure of the semi-lunar valves is well marked in the 
three heart beats at 20, -20. This closure is indicated in analogous points in both curves, after 
which there is a descent of the foot-support, and this corresponds to the downward propagation 
of the pulse wave through the aorta to the vessels of the feet. 
I. Elastic support for registering the molar motions of the body—K, wooden box; B, feet of 
patient; p, cardiograph; a, b, elastic tubing. II. Vibration curves of a healthy person, 
III. Curve obtained from a patient with insufficiency of the aortic valves and great 
hypertrophy of the heart. 
Fig. ill. 
Pathological.—In insufficiency of the aortic valves as shown in fig. Ill, III, the vibration 
communicated to the body is very considerable. 
81. THE BLOOD CURRENT.—Cause.—The closed and much- 
branched vascular system, whose walls are endowed with elasticity and 
contractility, is not only completely filled with blood, but it is over-filled. 
The total volume of the blood is somewhat greater than the capacity of the 
entire vascular system. Hence it follows that the mass of blood must exert 
Fig. 112. 
The upper curve is the vibration-curve of a healthy person, and the lower one a tracing of the 
apex-beat. 
pressure on the walls of the entire system, thus causing a corresponding dila- 
tation of the elastic vascular walls (Brunner). This occurs only during life; 
after death the muscles of the vessels relax, and fluid passes into the tissues, so 
that the blood-vessels come to contain less fluid, and some of them may be 
empty. Sec. 81.] 
CAUSES OF THE CONTINUOUS BLOOD-FLOW. 
137 
If the blood were uniformly distributed throughout the vascular system, and 
under the same pressure, it would remain in a position of equilibrium (as after 
death). If, however, the pressure be raised in one section of the tube, the 
blood will move from the part where the pressure is higher to where it is lower; 
so that the blood-current is a result of the difference of pressure 
within the vascular system. If either the aorta or the vense cavas be suddenly 
ligatured in a living animal, the blood continues to flow, but gradually more 
slowly, until the difference of pressure is equalized throughout the entire vas- 
cular system. 
The velocity of the current will be greater the greater the difference of 
pressure, and the less the resistance opposed to the blood-stream. 
The difference of pressure which causes the current is produced 
by the heart. Both in the systemic and pulmonary circulation the point of 
greatest pressure is in the root or beginning of the arterial system, while the 
point of lowest pressure is in the terminal portion of the venous orifices at the 
heart. Hence the blood flows continually from the arteries through the capil- 
laries into the venous trunks. The heart keeps up the difference of pressure 
required to produce this result; with each systole of the ventricles a certain 
quantity of blood is forced into the beginning of the arteries, while at the 
same time an equal amount flows from the venous orifices into the auricles- 
during their diastole H. Weber). 
Donders showed that the action of the heart not only causes the difference 
of pressure necessary to abolish a blood-current, but also raises the mean- 
pressure within the vascular system. The terminations of the veins at the 
heart are wider and more extensible than the arteries where they arise from the 
heart. As the heart propels a volume of blood into the arteries equal to that 
which it receives from the veins, it follows that the arterial pressure must rise 
more rapidly than the venous pressure diminishes, since the arteries are not so- 
wide nor so extensible as the veins. Thus the total pressure must also increase.. 
Cause of Continuous Flow.—The volume of blood expelled from the 
ventricles at every systole would give rise to a jerky or intermittent movement 
of the blood-stream—(i) if the tubes had rigid walls, as in such tubes any 
pressure exerted upon their contents is propagated momentarily throughout the- 
length of the tube, and the motion of the fluid ceases when the propelling 
force ceases; (2) the flow would also be intermittent in character in elastic 
tubes if the time between the two successive systoles were longer than the dura- 
tion of the current necessary for the compensation of the difference of pressure 
caused by the systole. If the time between two successive systoles be shorter 
than the time necessary to equilibrate the pressure, the current will become 
continuous, provided the resistance at the periphery of the tube be sufficiently 
great to bring the elasticity of the tube into action. The more rapidly systole 
follows systole, the greater the difference of pressure becomes, and the more 
distended the elastic walls. Although the current thus produced is continuous, 
a sudden rise of pressure is caused. by the forcing in of a mass of blood at 
every systole, so that with every systole there is a sudden jerk and acceleration 
of the bloodstream corresponding to the pulse (compare § 64). 
This sudden jerk-like acceleration of the blood-current is propagated through- 
out the arterial system with the velocity of the pulse-wave ; both phenomena 
are due to the same fundamental cause. Each pulse-beat causes a temporary- 
rapid progressive acceleration of the particles of the fluid. But just as the form- 
movement of the pulse is not a simple movement, neither is the pulsatile accel- 
eration a simple acceleration. It follows the course of the development of the 
pulse-wave. The pulse-curve is the graphic representation of the pulsatory 
acceleration of the blood-stream. Every rise in the curve corresponds to an. 
acceleration, every depression to a retardation of the current. 138 
[Sec. 81. 
CURRENT IN THE CAPILLARIES. 
[Method : Rigid and Elastic Tubes.—These facts are easily demonstrated. Tie a Higgin- 
son’s syringe to a piece of gas-pipe. On forcing water through the rigid tube, by compressing 
the pump, the water will flow out at the other end of the tube in jets, while during the inter- 
vals of pulsation no water will flow out. As the walls of the tube are rigid, just as much fluid 
flows out as is forced into the tube. If a similar arrangement be made, and a long elastic tube 
be used, a continuous outflow is obtained, provided the pulsation occur with sufficient rapidity 
and the length of the tube, or the resistance at its periphery, be sufficient to bring the elasticity 
of the tube into action. This can be done by putting a narrow cannula in the outflow end of 
the tube, or by placing a clamp on it so as to diminish the exit aperture. This apparatus con- 
verts the intermittent inflow into a continuous current.] The fire-engine is a good example of 
the conversion of an intermittent inflow into a uniform outflow. The air in the reservoir is in a 
state of elastic tension, and it represents the elasticity of the vascular walls. When the pump 
is worked slowly, the outflow of the water occurs in jets, and is interrupted. If the pumping 
movement be sufficiently rapid, the compressed air in the reservoir causes a continuous outflow, 
which is distinctly accelerated at every movement of the pump. [The ordinary spray-producer 
is another good example.] 
[Thus, there are two factors—a central one, the heart,—and a peripheral 
one, the amount of resistance especially in the arterioles. Either or both 
■may be varied, and as this is done, so will the pressure and velocity vary.] 
Current in the Capillaries.—In the capillaries the pulsatile accelera- 
tion of the current ceases with the extinction of the pulse-wave. The great 
resistance which is offered to the current towards the capillary area causes both 
to disappear. It is only when the capillaries are greatly dilated, and when the 
arterial blood-pressure is high, that the pulse is propagated through the capil- 
laries into the beginning of the veins. A venous pulse is observed in the 
veins of the sub-maxillary gland after stimulation of the chorda tympani nerve, 
which contains the vasodilator nerves for the blood-vessels of this gland. If 
the finger be constricted with an elastic band, so as to hinder the return of the 
venous blood, and to increase the arterial blood-pressure, while at the same 
time dilating the capillaries, an intermittent increased redness occurs, which 
•corresponds with the well-known throbbing sensation in the swollen finger. 
This is due to the capillary pulse. [Roy and Graham Brown found that 
pulsatile phenomena were produced in the capillaries by increasing the extra- 
vascular pressure (§ 86). Quincke called attention to the capillary pulse, which 
can often be seen under the finger-nails. * Extend the fingers completely, when 
a whitish area appears under the nails. A red area near the free margin of the 
nail advances and retires with each pulse-beat. It is well marked in some dis- 
eased conditions of the heart, especially in incompetence of the aortic valves, 
and is probably produced by increased extra-vascular pressure. If the finger be 
drawn over the skin, e.g., of the forehead, in such a person the alternate flush- 
ing and paling due to the capillary pulse is readily observed.] 
82. SCHEMATA OF THE CIRCULATION.—E. H. Weber constructed a scheme of 
the circulation. It consisted of a force-pump with properly arranged valves to represent the 
heart, portions of gut for the arteries and veins, and a piece of glass tubing containing a piece 
of sponge to represent the capillaries. Various schemes have been invented, including the very 
complicated one of Marey, [the extremely ingenious one of v. Thanhoffer, and the thoroughly 
practical one of Rutherford], 
83. CAPACITY OF THE VENTRICLES.—Since the right and left 
ventricles contract simultaneously, and just the same volume of blood passes 
through the pulmonary as through the systemic circulation, it follows that the 
right ventricle must be just as capacious as the left. The capacity of the ven- 
tricles has been estimated in the following ways:— 
Methods.—(1) Directly, by filling the dead relaxed ventricle with blood or an injection mass. 
This method is unsatisfactory and inaccurate. 
(2) Indirectly, Volkmann (1850) estimated it thus: Estimate the sectional area of the aorta, 
and the velocity of the blood-stream in it 91). From this calculate the amount of blood passing 
through the aorta in the unit of time. As the total quantity of blood in the body is known Sec. 83.] 
ESTIMATION OF THE BLOOD-PRESSURE. 
139 
(—Tu of the body-weight), we can easily calculate how long this takes to flow' through the aorta. 
We must also know the number of beats during the time of the circulation. From these data, 
and from experiments on animals, Volkmann estimated the volume of blood discharged at each 
systole by the ventricle to be of the body-wreight. For a man weighing 75 kilos, this is 
187.5 grams. This estimate still leaves much to be desired. 
Place calculates it in the following manner: A man uses about 500 litres of O in 24 hours. 
To absorb this into the venous blood (which contains about 7 vols. per cent, less O than arterial), 
about 7000 litres of blood must pass through the lungs in 24 hours. If one calculates 100,000 
heart-beats in 24 hours, then at each systole only 70 cubic centimetres are discharged. 
[Capacity of the pulmonary and systemic circulation.—Taking the 
quantity of blood in an average adult as equal to litres, according to Jolyet 
and Tanziac the ratio is 2 : 11, /. e., 1 litre in the pulmomary and in the sys- 
temic circuit. This estimate for the pulmonary circuit is somewhat too low. 
As to the relative quantity of blood in the arterial and venous tubes as a whole, 
the ratio is about x to 2.] 
84. ESTIMATION OF THE BLOOD-PRESSURE.—(A) In Animals: (1) 
Method of Hales.—The Rev. Stephen Hales (1727) was the first to introduce a long glass 
tube into a blood-vessel in order to estimate the blood-pressure by measuring the height of the 
column of blood. 
I. Scheme of C. Ludwig’s kymograph. II. Fick’s spring-kymograph 
Fig- II3- 
The tube was provided at its lower end with a copper tube bent at a right angle. [The tube 
he used was one-sixth of an inch bore and about 9 feet long, and was imerted into the femoral 
artery of a horse. The height to which the blood rose in the tube was noted, as well as the 
oscillations of the blood that occurred with every pulsation. From the height of the column of 
fluid he calculated the force of the heart.] 
(2) The Haemadynamometer of Poiseuille (1828).—This observer used a U-shaped tube 
partially filled with mercury—a gauge or manometer—which was brought into connection with 
a blood-vessel by means of a rigid tube. [The mercury oscillated with every pulsation, and the 
extent of the oscillations were read off on a scale attached to the bent tube. He called the 
instrument a h<zmadynamometer.~\ 
[(3) Vierordt used a tube 5 or 6 feet long, and filled it with a solution of sodium carbonate, 
thus preventing much blood from entering the tube, while at the same time the soda solution 
prevented the coagulation of the blood.] 
(4) C. Ludwig’s Kymograph.—C. Ludwig employed a U-shaped man- 
ometer, but he placed a light float upon the surface of the mercury in the open 
limb of the tube (fig. 113, I, d, s'). A writing-style, f, placed transversely on ludwig’s kymograph. 
[Sec. 84. 
140 
the free end of the float, inscribed the movements of the float—and, therefore, 
of the mercury—upon a cylinder, c, caused to revolve at a uniform rate. This 
apparatus registered the height of the blood-pressure, as well as the pulsatile 
and other oscillations occurring in the mercury. Volkmann called this instrument 
a kymograph or “ wave-writer.” The difference of the height of the column 
of mercury, c, d, in both limbs of the tube indicates the pressure within the vessel. 
If the height of the column of mercury be multiplied by 13.5, this gives the 
height of the corresponding columns of blood. Setschenow placed a stop-cock 
in the lower bend, h, of the tube. If this be closed so as just to permit a small 
aperture of communication to remain, the pulsatile vibrations no longer appear, 
and the apparatus indicates the mean pressure. By the term mean pressure is 
meant the limit of pressure, above and below which the oscillations occurring 
in an ordinary blood-pressure-tracing range. [Briefly, it is the average eleva- 
tion of the mercurial column.] 
In a blood-pressure tracing, such as fig. 115, each of the smaller 
waves corresponds to a heart-beat, the ascent corresponds to the systole, 
and the descent to the diastole. The large undulations are due to the 
respiratory movements. It is clear that the heart-beat is expressed as a 
simple rise and fall (fig. 115), so that 
the curve of the heart-beat obtained 
with a mercurial kymograph differs 
from a sphygmographic curve. 
[Faults of a Mercurial Manometer.— 
A perfect recording instrument ought to indi- 
cate the height of the blood-pressure, and 
also the size, form, and duration of any 
wave-motion communicated to it. The mer- 
curial manometer does not give the true form 
of the pulse-wave, as the mercury, when 
once set in motion, executes vibrations of its 
own, owing to its great inertia, and thus the 
liner movements of the pulse-wave are lost. 
Hence a mercurial kymograph is used for 
registering the blood-pressure, and not for 
obtaining the exact form of the pulse-wave. 
Instruments with less inertia, and with no 
vibrations peculiar to themselves, are required 
for this purpose.] 
[Method of Measuring Blood-Pres- 
sure.—Expose the carotid of a chloralized 
rabbit, and isolate a portion of the vessel 
between two ligatures. Make an oblique slit 
in the artery, and into it tie a straight glass 
cannula, directing the pointed end of the 
cannula towards the heart. Fill the cannula 
with a saturated solution of sodium carbonate, 
taking care that no air-bubbles enter, and 
connect it with the lead tube which goes to 
the ascending limb of the manometer. The 
tube which connects the artery with the ma- 
nometer must be flexible and yet inelastic, 
and a lead tube is best. It is usual to connect 
a pressure-bottle, containing a saturated 
solution of sodium carbonate, by means of an 
elastic tube, with the tube attached to the 
manometer. This bottle can be raised or 
lowered. Before beginning the experiment, raise the pressure-bottle until there is a positive 
pressure of mercury in the manometer about equal to the estimated blood-pressure, and then 
clamp the tube of the pressure-bottle where it joins the lead tube. This positive pressure 
prevents the escape of blood from the artery into the solution of sodium carbonate. When all 
Ludwig’s improved revolving cylinder, J?, moved 
by the clockwork in the box, A, and regulated 
by a Foucault’s regulator placed on the top of 
the box. The disc, D, moved by the clock- 
work, presses upon the wheel, «, which can be 
raised or lowered by the screw, L, thus alter- 
ing the position of n on D, so as to cause the 
cylinder to rotate at different rates. The cyl- 
inder itself can be raised by turning the handle, 
U. On the left side of the figure is a mercurial 
manometer. When the cylinder is used, it is 
covered with smoked smooth paper. 
Fig. 114. Sec. 84.] 
ESTIMATION OF THE BLOOD-PRESSURE. 
141 
is ready, the ligature on the cardiac side of the cannula is removed, and immediately the float 
begins to oscillate and inscribe its movements upon the recording surface. The fluid within 
the artery exerts pressure latterly upon the sodium carbonate solution, and this in turn transmits 
it to the mercury. Albumoses, when injected into the blood, keep it from coagulating (p. 37). 
Roy finds that oil may take the place of sodic carbonate.] 
[Precautions.—In taking a blood-pressure-tracing, after seeing that the apparatus is perfect, 
care must be taken that the animal is perfectly quiescent, as every movement causes a rise of 
blood-pressure. This may be secured by giving curare and keeping up artificial respiration, or 
by the carefully regulated inhalation of ether. When a drug is to be injected to test its action, 
if it be introduced into the jugular vein it is apt to affect the heart directly. This may be 
avoided by injecting it into a vein of the leg, or under the skin. The solution of the drug must 
not contain particles which will block up the capillaries. Care should also be taken that the 
carbonate of soda does not flow back into the artery.] 
[Continuous Tracing.—When we have occasion to take a tracing for any length of time, 
it must be written upon a strip of paper which is moved at a uniform rate in front of the 
Blood-pressure curve of the carotid of a dog obtained with a mercurial manometer, o-x = line 
of no pressure, zero line, or abscissa ; y-y' is the blood-pressure-tracing with small waves, 
each one caused by a heart-beat, and the large waves due to the respiration. A millimetre 
scale shows the height of the pressure in millimetres of mercury. 
Fig. 115- 
writing-style on the float (fig. 113). Various arrangements are employed for this purpose, but 
it is usual to cause a cylinder to revolve, so as to unfold a roll of paper placed on a movable 
bobbin. As the cylinder revolves, it gradually winds off the strip of paper which is kept applied 
to the revolving surface by ivory friction-wheels. In Hering’s complicated kymograph a long 
strip of smoked paper is used. The writing-style may consist of a sable brush, or a fine glass 
pen filled with aniline blue dissolved in water, to which a little alcohol and glycerin are added.] 
[In order to measure the height of the pressure, we must know the position of the 
abscissa or line of no pressure, and it may be recorded at the same time as the blood-pressure, 
or afterwards. In fig. 115 O—x is the zero-line or the abscissa, and the height of the vertical 
lines or ordinates may be measured by the millimetre scale on the left of the figure. The 
height of the blood-pressure is obtained by drawing ordinates from the curve to the abscissa, 
measuring their length, and multiplying by two.] 
(5) Spring Kymograph.—A. Fick (1864) uses a hollow spring-kymograph 
on the principle of Bourdon’s manometer (fig. 113, II). 
A hollow C-shaped metallic spring, F, is filled ■with alcohol. One end of the hollow spring 
is closed, and the other end, covered by a membrane, is brought into connection with a blood- 142 
OTHER FORMS OF KYMOGRAPH. 
[Sec. 84. 
vessel by a junction piece filled with a solution of sodium carbonate. As soon as the com- 
munication with the artery is opened, the pressure rises, and the spring, of course, tends to 
straighten itself. To the closed end, b, there is fixed a vertical rod attached to a series of levers, 
h, i, k, e, one of which writes its movements upon a surface moving at a uniform rate. The 
blood-pressure and the periodic variations of the pulse are both recorded, although the latter is 
not done with absolute accuracy. 
[Hering improved Fick’s instrument (fig. 116). The hollow spring filled with alcohol com- 
municates at a with the lead tube, d, passing to the cannula in the artery. To c is attached a 
series of light wooden levers with a writing-style, s. The lower part of 4 dips into a vessel, e, 
filled with oil or glycerin, which serves to damp the vibrations of the levers. At /is a syringe 
communicating with the tube, d, filled with a solution of sodic carbonate, and used for regu-' 
lating the amount of fluid in the tube connecting the manometer with the blood-vessel. The 
whole apparatus can be raised or lowered on the toothed rod, h, by means of the millhead 
opposite, g, to which all the parts of the apparatus are attached.] 
(6) Fick’s Flat Spring-Kymograph.—The narrow tube, a, a (1 mm. diam.) is placed in 
connection with a blood-vessel by means of the cannula, c, and over its vertical expanded end, 
A, is fixed a caoutchouc membrane, with a projecting point, s, which presses against a horizontal 
spring, F, joined to a writing-lever, 
H, by an intermediate piece, b. The 
whole is held in the metallic frame, 
R R (fig. 117). In order to estimate 
the absolute pressure, the instrument 
must be compared previously with a 
mercurial manometer. 
(B) In man the blood-pres- 
sure maybe estimated by means 
of—(1) a properly graduated 
sphygmograph (§ 67). The 
pressure required to abolish the 
movement of the lever indicates 
approximately the vascular ten- 
sion. The mean blood-pressure 
in the radial artery is equal to 
55° grams. 
(2) Sphygmomanometer 
of v. Basch.—A capsule con- 
taining fluid was placed upon a 
pulsating artery, while the cap- 
sule itself communicated with 
a mercurial manometer. As 
soon as the pressure within the 
manometer slightly exceeded that within the artery, the artery was compressed 
so that a sphygmograph placed on a peripheral portion of the vessel ceased to 
beat. Both arrangements do not give the exact pressure within the artery; they 
only indicate the pressure 
which is required to compress 
the artery and the overlying 
soft parts. The pressure re- 
quired to compress the walls 
of an empty artery, however, 
is very small compared with 
Fig. 1x6. 
Fick’s Spring Manometer, as improved by Flering. 
Fick’s Flat Spring Kymograph. 
Fig. 117. 
the blood-pressure. It is only 4 mm. Hg. V. Basch estimated the pressure 
in the radial artery of a healthy man to be 135 to 165 millimetres of mercury. Sec. 84.] 
influences AFFECTING THE BLOOD-PRESSURE. 
Variations.—In children the blood-pressure increases with age, height, and weight. In 
the superficial temporal artery, at 2 to 3 years, it is == 97 mm.; 12 to 13 years, 113 mm. Hg 
(A. Eckert, c. \ 100). The blood-pressure is raised immediately after bodily movements ; it 
is higher when a person is in the horizontal position than when sitting, and in sitting than in 
standing. After a cold as well as after a warm bath, the first effect is an increase of blood - 
pressure and of the quantity of urine. 
85. BLOOD-PRESSURE IN THE ARTERIES.—The following 
results have been obtained by experiment on systemic arteries :— 
(a) Mean Blood-Pressure.—The blood-pressure is very considerable,, 
varying within pretty wide limits; in the large arteries of large mammals, and 
perhaps in man, it = 140 to 160 millimetres [5.4 to 6.4 inches] of a mercurial 
column. 
The following results have been obtained, those marked thus * by Poiseuille, and thus -f by 
Volkmann :— 
* Carotid, Horse 161 mm. 
-)- “ “ 122 to 214 mm. 
* “ Dog, 151 mm. 
“ “ 130 to 190 mm. (Ludwig). 
-f- “ Goat, 118 to 135 mm. 
-j- “ Rabbit, 90 mm. 
+ Carotid, Fowl, 88 to 171 mm. 
-j- Aorta of Frog, 22 to 29 mm. 
-j- Gill Artery of Pike, 35 to 84 mm. 
Brachial artery of Man during an operation, 
110 to 120 mm. (Faivre). Perhaps too 
low owing to the injury. 
E. Albert estimated the blood-pressure by means of a manometer, placed in connection with 
the anterior tibial artery of a boy whose leg was to be amputated, to be ioo to 160 mm. Hg.. 
The elevation with each pulse-beat was 17 to 20 mm.; coughing raised it to 20 or 30 mm.; 
tight bandaging of the healthy leg, 15 mm.; while passive elevation of the body, whereby the 
hydrostatic action of the column of blood was brought into play, raised it 40 mm. 
The pressure in the aorta of mammals varies from 200 to 250 mm. Hg. As a general rule, 
the blood-pressure in large animals is higher than in small animals, because in the former the 
blood-channel is considerably longer, and there is a greater resistance to be overcome. In very 
young and in very old animals the pressure is lower than in individuals in the prime of life. 
The arterial pressure in the foetus is scarcely half that of the newly born, while the venous 
pressure is higher, the difference of pressure between arterial and venous blood being scarcely 
half so great as in adult animals (Cohnstein and Zuntz). 
The arterial blood-pressure is highest in the aorta, and falls towards the 
smaller vessels, but the fall is very gradual, as shown in fig. 118. A great fall 
takes place on passing from the 
area of the arterioles into the ca- 
pillary area (C), while it is less in 
the venous area, and negative in 
the veins near the heart, as indi- 
cated in the dotted line passing 
below the abscissa, so that the 
pressure is lowest in the cardiac 
ends of the venae cavae (compare 
fig. 124). 
(£) Branching of the Blood- 
Vessels.—Within the large arte- 
ries the blood-pressure diminishes 
relatively little as we pass toward 
the periphery, because the difference of the resistance in the different sections 
of large tubes is very small. As soon, however, as the arteries begin to divide 
frequently, and undergo a considerable diminution in their lumen, the blood- 
pressure in them rapidly diminishes because the propelling energy of the 
blood is much weakened, owing to the resistance which it has to overcome 
(§ 99)- 
Fig. 118. 
Scheme of the blood-pressure, in A, the arteries; 
C, capillaries, and V, veins; 0-0 is the abscissa 
or line of no pressure ; L. V., left ventricle, and 
R. A., right auricle; B. P., the height of the 
blood-pressure. 144 
INFLUENCES AFFECTING BLOOD-PRESSURE. 
[Sec. 85. 
(c) Amount of Blood.—The blood-pressure is increased with greater filling 
«of the arteries, and vice versa ; hence it 
Increases. 
1. With increased and accelerated action of 
the heart; 
2. In plethoric persons; 
3. After a very considerable increase of the 
quantity of blood by direct transfusion, 
or after a copious meal. 
Decreases. 
1. During diminished and enfeebled action of 
the heart; 
2. In anaemic persons; 
3. After hemorrhage or considerable excre- 
tions from the blood by sweating, the 
urine, severe diarrhoea. 
The blood-pressure does not vary in the same proportion as the variations in the amount of 
blood. The vascular system, in virtue of its muscular tissue, has the property, within liberally 
wide limits, of accommodating itself to larger or smaller quantities of blood (C. Ludivig and 
Worm Miiller, g 102, d). [In fact, a large amount of blood may be transfused without materi- 
ally raising the blood-pressure. Small and moderate hemorrhages (in the dog to 2.8 per cent, 
of the body-weight) have no obvious effect on the blood-pressure. After a slight loss of blood 
the pressure may even rise ( Worm Muller). If a large amount of blood be withdrawn, it causes 
a great fall of the blood-pressure, and when hemorrhage occurs to 4-6 per cent, of the body- 
weight, the blood-pressure = o. The transfusion of a moderate amount of blood does not raise 
the mean arterial blood-pressure. There are important practical deductions from these experi- 
ments, viz., that the arterial blood-pressure cannot be diminished directly by moderate blood- 
letting, and that the blood-pressure is not necessarily high in plethoric persons.] 
{d') Capacity of the Vessels.—The arterial pressure rises when the 
capacity of the arterial system is diminished, and conversely. The circularly- 
disposed smooth muscular fibres of the arteries are the chief agents concerned 
in this process. When they relax, the arterial blood-pressure falls, and when 
they contract, it rises. These actions of muscular fibres are controlled and 
regulated by the action of the vasomotor nerves (§ 371). 
(e) Collateral Vessels.—The arterial pressure within a given area of the 
vascular system must rise or fall according as the neighboring areas are dimin- 
ished, whether by the application of pressure, or a ligature, or are rendered 
impervious, or as these areas dilate. The application of cold or warmth to 
limited areas of the body—increasing or diminishing the atmospheric pressure 
on a part—the paralysis or stimulation of certain vasomotor areas all produce 
remarkable variations in the blood-pressure (§ 371). [The effect of dilatation 
of a large vascular area on the arterial pressure is well shown by what happens 
when the blood-vessels of the abdomen are dilated.] Divide both vagi in the 
neck of a rabbit and stimulate the central end of the superior cardiac 
branch of the vagus or depressor nerve ; after a few seconds the blood- 
vessels of the abdomen dilate, and gradually there is a steady fall of the blood- 
pressure in the systemic arteries. Fig. 119 is a blood-pressure tracing showing 
the height of the blood-pressure before stimulation, a. The stimulation was 
continued from a to b, and after a rather long latent period there is a steady fall 
of the blood-pressure. 
(/) Respiratory Undulations.—The arterial pressure also undergoes 
regular variations or undulations owing to the respiratory movements. These 
undulations are called respiratory undulations (figs. 115, 119, 120). Stated 
broadly, on the whole, during inspiration the blood-pressure rises, and during 
expiration it falls (§ 74). This is not strictly correct. These undulations may 
be explained by the fact that, with every expiration, the blood in the aorta is 
subjected to an increase of pressure through the compressed air in the chest; 
with every inspiration, on the other hand, it is diminished owing to the rare- 
faction of the air in the lungs acting upon the aorta. Besides, the inspiratory 
movements of the chest aspirate blood from the venae cavae towards the heart, 
while expiration retards it, and thus influences the blood-pressure. The undu- 
lations are most marked in the arteries lying nearest to the heart. The respi- 
ratory undulations are due in part to a stimulation or condition of excitement Sec. 85.] 
EFFECT OF RESPIRATION ON BLOOD-PRESSURE. 
145 
of the vaso-motor centre, which runs parallel with the respiratory movements. 
This stimulation of the vaso-motor centre causes the arteries to contract, and 
thus the blood-pressure is raised. The variations in the pressure which depend 
upon a varying activity of the vaso-motor centre are known as the “curves 
Fig. 119. 
Kymographic tracing showing the effect on the blood-pressure of stimulation of the central end 
of the depressor nerve in the rabbit after section of both vagi in the neck. Stimulation 
began at a and ended at b; o-x, the abscissa. 
of Traube and Hering.” Fig. 120 shows the carotid blood-pressure tracing of 
a dog. In this curve, when inspiration begins (1) the blood-pressure is still 
falling slightly, but gradually rises until it reaches its maximum shortly after the 
beginning of expiration (E). [The maxima and minima of the respiratory and 
blood-pressure curves do not coincide exactly, but in addition the number of 
Carotid blood-pressure tracing of dog; vagi not divided ; I = inspiration. E = expiration 
(Stirling). 
Fig. 120. 
pulse-beats is greater in the ascent than in the descent. This is well marked in 
a blood-pressure tracing from a dog’s carotid (fig. 120) while in a rabbit this 
difference of the pulse-rate is but slightly marked (fig. 119). The smaller num- 
ber of pulse-beats during the descent, i. e., during the greater part of expiration, [Sec. 85. 
146 
TRAUBE-HERING CURVES. 
is due to the activity of the cardio-inhibitory centre in the medulla oblongata. 
This is proved by the fact that section of both vagi in the dog causes the differ- 
ence of pulse-rate to disappear, while other conditions remain the same as before, 
except that the heart beats more rapidly. It would seem that, during the ascent, 
the cardio-inhibitory centre is comparatively inactive. It is clear, therefore, 
that the respiratory and cardio-inhibitory centres in the medulla oblongata 
act to a certain extent in unison, so that it is reasonable to suppose that other 
centres situated in close proximity to these may also act in unison with them, 
or, as it were, “in sympathy.” As already stated, the vaso-motor centre 
is also in action during a particular part of the time.] 
[If a dog be curarized and artificial respiration established, the respiratory 
undulations still occur, although in a modified form. In artificial respiration, 
the mechanical conditions, as regards the intra-thoracic pressure, are exactly 
the reverse of those which obtain during ordinary respiration. Air is forced 
into the chest during artificial respiration, so that the pressure within the chest 
is increased during inspiration, while in ordinary inspiration the pressure is di- 
minished. Thus, the same mechanical explanation will not suffice for both cases.] 
If the artificial respiration be suddenly interrupted in a curarized animal, the 
blood-pressure rises steadily and rapidly. This rise is due to the stimulation of 
the vaso-motor centre in the medulla*oblongata by the impure blood. This 
causes contraction of the small arteries throughout the body, which retards the 
outflow from the large arteries, and thus the pressure within them is raised. 
[Stated broadly, the arterial pressure depends on the central organ—the 
heart, and on the condition of the peripheral organs—the small arteries. 
Both are influenced by the nervous system. If the action of the vaso-motor 
centre be eliminated by dividing the spinal cord in the cervical region, arrest 
of the respiration causes a very slight rise of the blood-pressure; hence, it is 
evident that venous blood acts but slightly on the heart, or on any local peri- 
pheral nervous mechanism, or on the muscular fibres of the arteries. This ex- 
periment shows that it is the vaso-motor centre which is specially acted upon 
by the venous blood.] 
[Traube-Hering Curves.—The following experiment proves that the vary- 
ing activity of the vaso-motor centre suffices to produce undulations in the blood- 
pressure tracing. In a curarized dog expose both vagi; establish artificial 
respiration ; and estimate the blood-pressure in the carotid. After section of 
the vagi, the heart will beat more rapidly, but it will be undisturbed by the 
cardio-inhibitory centre. Thus the central factor in the causation of the blood- 
pressure remains constant. Suddenly interrupt the respiration, and, as already 
stated, the blood-pressure will rise steadily and uniformly, owing to the stimu- 
lation of the vaso-motor centre by the venous blood. In this case the peri- 
pheral factor, or state of tension of the small arteries throughout the body, is 
influenced by the condition of the nerve-centre, which controls their action. 
After a time, the blood-pressure tracing shows a series of bold curves higher than 
the original tracing. These can only be due to an alteration in the state of the 
small arteries, brought about by a condition of rhythmical activity of the vaso- 
motor centre. These curves were described and figured by Traube and are called 
the Traube or Traube-Hering curves. As in other conditions, stimulation causes 
exhaustion, and soon the venous blood paralyzes the vaso-motor centre, and the 
small arteries relax, blood flows freely out of the larger arteries, and the blood 
pressure rapidly sinks. Variations in the blood-pressure have been observed after 
a mechanical pump has been substituted for the heart, i. e., after all respiratory 
movements have been set aside, so that the only factor which would account 
for the phenomena of the Traube-Hering curves is the variation in the peripheral 
resistance in the small arteries, determined by the condition in the vaso-motor 
centre.] Sec. 85.] 
EFFECT OF STIMULATION OF THE VAGUS. 
147 
Variations.—The respiratory undulations of the blood-pressure become more pronounced 
the greater the force of the respirations, which produce greater variations of the intra-thoracic 
pressure. In man, the diminution of the pressure within the trachea is I mm. Hg. during 
tranquil inspiration, while during forced respiration, when the respiratory passage is closed, it 
may be 57 mm. Conversely, during ordinary expiration, the pressure is increased within the 
trachea 2-3 mm. Hg, while during forced expiration, owing to the compression of the abdominal 
muscles, it may reach 87 mm. Hg. 
Other Factors.—The increase of the blood-pressure during inspiration, as well as the fall 
during expiration, must in part depend upon the pressure within the abdomen. As the dia- 
phragm descends during inspiration, it presses upon the abdominal contents, including the 
abdominal vessels, whereby the blood-pressure must be increased. The reverse effect occurs 
during expiration (,Sckweinburg). [Section of both phrenic nerves and opening of the abdominal 
cavity cause the respiratory undulations almost entirely to disappear. The respiratory undula- 
tions, therefore, depend in great part upon the changes of the abdominal pressure and the effect 
of these changes on the amount of blood in the abdominal vessels. When making a blood- 
pressure experiment, pressure upon the abdomen of the animal with the hand causes the blood- 
pressure to tise rapidly.] 
Kronecker and Heinricius ascribe the undulations to mechanical causes, and as due to the 
simultaneous compression of the heart by the lungs during respiration. Everything which 
hinders the diastole of the heart diminishes the blood-pressure. As soon, therefore, as the 
lungs during inspiration have become distended so far as to compress the heart, the diastole is 
affected, and thereby a decrease in the blood-pressure of the aorta is brought about. As soon 
as air passes out of the lungs, and the latter retract, the heart becomes fuller and the arterial 
pressure rises. 
(g) Variations with each Pulse-Beat.—The mean arterial pressure 
undergoes a variation with each heart-beat or pulse-beat, causing the so-called 
pulsatory undulations (fig. 120). The mass of blood forced into the arteries 
with each ventricular systole causes a positive wave and an increase of the pres- 
sure corresponding with it, which of course corresponds in its development and 
in its form with the pulse-curve. 
In the large arteries Volkmann found the increase during the heart-beat to be = (horse) 
and fa (dog) of the total pressure. 
None of the apparatus described in § 84 gives an exact representation of the pulse-curve. 
They all show simply a rise and fall, a simple curve. The sphygmograph alone gives a true 
expression of the undulations in the blood-pressure which are due to the heart-beat. 
Arrest of the Heart’s Action.—If the heart’s action be arrested or in- 
terrupted by continued stimulation of the vagus, or by high positive respira- 
tory pressure, the arterial blood pressure falls enormously, while it rises in the 
veins as the blood flows into them from the arteries to equilibrate the difference 
of pressure in the two sets of vessels. This experiment shows that, even when 
the difference of pressure is almost entirely set aside, the passive blood presses 
upon the arterial walls, i. e., on account of the overfilling of the blood-vessels 
a slight pressure is exerted upon the walls, even when there is no circulation. 
[As already stated, the arterial pressure depends on the condition of the central 
organ—the heart—and on the peripheral organs—the small arteries. If the 
action of the heart be arrested, then the blood-pressure rapidly falls. Fig. 121 
shows the effect on the blood-pressure of arresting the action of the heart by 
stimulation of the peripheral end of the vagus in a rabbit. There is a 
sudden fall of the arterial pressure, as shown by the rapid fall of the curve 
from a.~\ 
[Variations in Animals.—The pressure in the arterial system depends upon the balance 
between the inflow and outflow, i. e., upon the heart and the state of the arterioles. But it is 
to be noted that the central factor, the heart, varies in different animals. In the rabbit the 
heart normally beats rapidly, so that section of the vagi does not cause any great increase in 
the number of beats, nor is the blood-pressure much raised thereby. In the dog, on the other 
hand, the beats are considerably increased by section of the vagi, while the blood-pressure 
rises considerably. Atropin paralyzes the cardiac terminations of the vagus, and thereby trebles 
the number of heart-beats in the dog, while it only raises it 25 per cent, in the rabbit; in man, 
again, the number may be doubled. As Brunton has shown, this difference of the initial [Sec. 85. 
148 
RELATION OF BLOOD-PRESSURE TO PULSE-RATE. 
number of heart-beats and the action of the vagus have important relations to the action of 
drugs on the blood-pressure. For example, if an intact rabbit be caused to inhale amyl nitrite 
the blood-pressure falls at once and rapidly, while in the dog the fall may be slight. The pulse 
of the dog, however, is greatly accelerated, so much so as to be nearly as rapid as that of the 
rabbit. In both, the vessels are dilated, but in the dog, notwithstanding this dilatation, which 
per se would cause the pressure to fall, the heart of the dog beats now so rapidly as to com- 
pensate for this, and thus keeps the blood-pressure nearly normal; while the increased rate of 
beating in the rabbit is not sufficient for this purpose. If the vagi in the dog be divided, the 
subsequent inhalation of amyl nitrite causes a fall of blood-pressure like that in the rabbit 
(Brunton). Fig. 122 shows that the arterial tension has no direct relation to the position of an 
animal in the zoological scale.] 
[Relation of Blood-Pressure to Pulse-Rate.—When the blood- 
pressure rises in an intact animal, as a rule the pulse-rate falls, owing to stimu- 
lation of the vagus centre increasing the cardio-inhibitory action, while a fall 
of blood-pressure is accompanied by an increase of the number of pulse-beats 
Fig. 121. 
Blood-pressure tracing taken with a mercurial kymograph from the carotid of a rabbit. 
o-x, abscissa; stimulation of vagus begun at a and stopped at b. 
for the opposite reason, the action of the medullary cardio-inhibitory centre 
being increased. But the blood-pressure may be increased either by the action 
of the heart or the arterioles. If we divide the vagi the pulse beats more 
quickly, and in some animals the blood-pressure rises; in this case, the rise in 
the two curves occurs together, and if the vagi be stimulated there is a sudden 
fall of the blood-pressure, due to arrest of the heart’s action, so that again the 
two curves are parallel. If the arterioles contract the blood-pressure rises, but 
by and by the pulse-rate falls, owing to the cardio-inhibitory action of the 
vagus; while on the other hand, if the arterioles are dilated, the blood-pressure 
falls, and the heart beats faster. Thus, in both of these cases the pulse-curve 
and blood-pressure curve run in opposite directions. These results only obtain 
when the vagi are intact (Brunto?i).~\ 
[The increase in the pulse-rate and blood-pressure following section of the vagi do not run 
parallel. Both sooner or later reach a maximum, but the blood-pressure gradually falls to or 
below the normal while the pulse-rate remains above the normal (Miinzel).] Sec. 85.] 
BLOOD PRESSURE IN THE CAPILLARIES. 
For the effects of the nervous system upon the blood-pressure, see § 371. 
Pathological.—In persons suffering from granular or contracted kidney and sclerosis of the 
arteries, in lead poisoning, and after the injection of ergotin, which causes contraction of the 
small arteries, it is found, on employing the method of v. Basch, that the blood-pressure is 
raised. It is also increased in cases of cardiac hypertrophy with dilatation, and by digitalis 
in cardiac affections, while it falls after the injection of morphia. The blood-pressure 
falls in fever, a fact also indicated in the sphygmogram ($ 69), and it is low in chlorosis and 
phthisis. 
86. BLOOD-PRESSURE IN THE CAPILLARIES.—Methods.—Direct estima- 
tion of the capillary pressure is not possible on account of the smallness of the capillaries. If a 
glass plate of known dimensions be placed on a vascular portion of the skin, and if it be 
weighted until the capillaries become pale, we obtain approximately the pressure necessary to 
overcome the capillary pressure. N. v. Kries placed a 
small glass plate (fig. 123) 2.5-5 scl- mm-> on the skin 
at the root of the nail on the terminal phalanx, or on 
the ear in man, and on the gum in rabbits. Into a 
scale-pan attached to this weights were placed until the 
skin became pale. The pressure in the capillaries of 
the hand, when the hand is raised, Kries found to be 
24 mm. Hg.; when the hand hangs down, 54 mm. Hg.; 
in the ear, 20 mm.; and in the gum of a rabbit, 32 mm. 
Roy and Graham Brown compressed from below 
transparent vascular membranes against a glass plate by 
means of an elastic bag connected with a manometer, 
while the variations in the capillaries were observed 
from above by a microscope. 
Fig. 123. 
Scheme of the blood-pressure. H, 
heart; a, auricle; v, ventricle; A, 
arterial; C, capillary; and V, ve- 
nous areas. The circle indicates 
, the parts within the thorax; B.P., 
pressure in the aorta. 
Fig. 124. 
Blood-pressure tracings from different 
animals. The scale of centimetres is 
reduced one-half. 
Fig. 122. 
V. Kries’s appara- 
tus for capillary 
pressure, a, 
square of glass. 
Conditions influencing Capillary Pressure.—The capillary blood- 
pressure in a given area increases—(i) When the afferent small arteries dilate, 
so that the blood-pressure within the large arteries is propagated more easily 
into them. (2) By increasing the pressure in the small afferent arteries. (3) By 
narrowing the diameter of the veins leading from the capillary area. Closure 
of the veins may quadruple the pressure. (4) By increasing the pressure in the 
veins, e. g., by altering the position of a limb. A diminution of the capillary 
pressure is caused by the opposite conditions. 
Changes in the diameter of the capillaries influence the internal pressure. We have to 
consider the movements of the capillary wall itself as well as the pressure, swelling, and con- 
sistence of the surrounding tissues The resistance to the blood-stream is greatest in the capillary [Sec. 86. 
150 
CONDITIONS INFLUENCING THE VENOUS PRESSURE. 
area, and it is evident that the blood in a long capillary must exert more pressure at the com- 
mencement than at the end of the capillary; in the middle of the capillary area the blood- 
pressure is just about one-half of the pressure within the large arteries (Donders). The capillary 
pressure must also vary in different regions of the body. Thus, the pressure within the intestinal 
capillaries, in those constituting the glomeruli of the kidney, and in those of the lower limbs 
when a person is in the erect posture, must be greater than in other regions, depending in the 
former cases partly upon the double resistance caused by two sets of capillaries, and in the 
latter case partly on purely hydrostatic causes. 
87. Blood-Pressure in the Veins.—In the large venous trunks near 
the heart (innominate, subclavian, jugular) a mean negative pressure of about 
- o. 1 mm. Hg. prevails (H. Jacobson). Hence, the lymph-stream can flow un- 
hindered. As the distance of the veins from the heart increases, there is a gradual 
increase of the lateral pressure; in the external facial vein (sheep) = -|- 3 mm.; 
brachial, 4.1 mm., and in its branches 9 mm. ; crural, 11.4 mm. [The pressure 
is said to be negative when it is less than that of the atmosphere. The gradual 
fall of the blood-pressure from the capillary area (C) to the venous area (V) is 
shown in fig. 124, while within the thorax, where the veins terminate in the 
right auricle, the pressure is negative.] 
Modifying Conditions.—(1) All conditions which diminish the difference 
of pressure between the arterial and venous systems increase the venous pressure, 
and vice versa. 
(2) General plethora of blood increases it; anaemia diminishes it. 
(3) Respiration, or the aspiration of the thorax, affects specially the 
pressure in the veins near the heart; during inspiration, owing to the dimin- 
ished tension, blood flows towards the chest, while during expiration it is 
retarded. The effects are greater the deeper the respiratory movement, and 
these may be very great when the respiratory passages are closed (§ 60). 
[When a vein is exposed at the root of the neck, it collapses during inspiration, and fills dur- 
ing expiration. The respiratory movements do not affect the venous stream in peripheral veins. 
The veins of the neck and face become distended with blood during crying, and on making 
violent expiratory efforts, as in blowing upon a wind instrument. Every surgeon is acquainted 
with the fact that air is particularly liable to be sucked into the veins during inspiration in opera- 
tions near the root of the neck. This is due to the negative intra-thoracic pressure occuriing 
during inspiration.] 
(4) Aspiration of the Heart.—Blood is sucked or aspirated into the 
auricles when they dilate (p. 67), so that there is a double aspiration—one syn- 
chronous with inspiration, and the other, which is but slight, synchronous with 
the heart-beat. There is a corresponding retardation of the blood-stream in 
the venae cavae, caused by the contraction of the auricle (p. 67, a). The 
respiratory and cardiac undulations are occasionally observable in the jugular 
vein of a healthy person (§ 99). 
(5) Change in the position of the limbs or of the body, for hydrostatic reasons, 
greatly alters the venous pressure. The veins of the lower extremity bear the 
greatest pressure, and Bardeleben has shown that the walls of these veins contain 
much smooth muscle (§ 65). Hence, when these muscles from any cause become 
insufficient, dilatations occur in the veins, giving rise to the production of 
varicose veins. 
[Braune showed that the femoral vein under Poupart’s ligament collapsed when the lower 
limb was rotated outwards and backwards, but filled again when the limb was restored to its 
former position. All the veins which open into the femoral vein have valves, which permit blood 
to pass into the femoral vein, but prevent its reflux. This mechanism acts to a slight degree as 
a kind of suction and pressure apparatus when a person walks, and thus favors the onward 
movement of the blood.] 
[(6) Muscular Movements.—Veins which lie between muscles are com- 
pressed when these muscles contract, and as valves exist in the veins, the flow of 
blood is accelerated towards the heart; if the outflow of the blood be obstructed Sec. 87.] 
BLOOD-PRESSURE IN THE PULMONARY ARTERY. 
151 
in any way, then the venous pressure on the distal side of the obstruction may 
be greatly increased. When a fillet is tied on the upper-arm, and the person 
moves the muscles of the fore-arm, the superficial veins become turgid, and can 
be distinctly traced on the surface of the limb.] 
(7) Gravity exercises a greater effect upon the blood-stream in the extensile 
veins than upon the stream in the arteries. It acts on the distribution of the 
blood, and thus indirectly on the motion of the blood-stream. It favors the 
emptying of descending veins, and retards the emptying of ascending veins, 
so that the pressure becomes less in the former and greater in the latter. If the 
position of the limb be changed, the conditions of pressure are also altered. If 
a person be suspended with the head hanging downwards, the face soon becomes 
turgid, the position of the body favoring the inflow of blood through the arte- 
ries and retarding the outflow through the veins. If the hand hangs down it 
contains more blood in the veins than if it is held for a short time over the 
head, when it becomes pale and bloodless. [As Lister has shown, the condi- 
tion of the vessels in the limb is influenced not only by the position of, the 
limb, but also by the fact that a nervous mechanism is called into play.] 
[Ligature of the portal vein causes congestion of the rootlets and dilatation of all the blood- 
vessels in the abdomen; gradually nearly all the blood of the animal accumulates within its 
belly, so that, paradoxical as it may seem, an animal may be bled into its own belly. As a con- 
sequence of sudden and complete ligature of this vein, the arterial blood-pressure gradually and 
rapidly falls, and the animal dies very quickly. If the ligature be removed before the blood- 
pressure falls too much, the animal may recover. Schiff and Lautenbach regard the symptoms 
as due chiefly to the action of a poison, for when the blood of the portal vein in an animal treated 
in this way is injected into a frog, it causes death within a few hours, while the ordinary blood of 
the portal vein has no effect.] 
[Ligature of the Veins of a Limb.—The effect of ligaturing or compressing all the veins 
of a limb is well seen in cases where a bandage has been applied too tightly. It leads to con 
gestion and increase of pressure within the veins and capillaries, increased transudation of fluid 
through the capillaries, and consequent oedema of the parts beyond the obstruction. Ligature 
of one vein does not always produce oedema, but if several veins of a limb be ligatured, and the 
vaso-motor nerves be divided at the same time, the rapid production of oedema is ensured. In 
pathological cases the pressure of a tumor upon a large vein may produce similar results ($ 203).] 
88. BLOOD-PRESSURE IN THE PULMONARY ARTERY.—Methods.—(1) 
Direct estimation of the blood-pressure in the pulmonary artery by opening the chest was made 
by C. Ludwig and Beutner (1850). Artificial respiration was kept up, and the manometer was 
placed in connection with the left branch of the pulmonary artery. The circulation through the 
left lung of cats and rabbits was thereby completely cut off, and in dogs to a great extent inter- 
rupted. There was an additional disturbing element, viz., the removal of the elastic force of the 
lungs, owing to the opening of the chest, whereby the venous blood no longer flowed normally 
into the right heart, while the heart itself was under the full pressure of the atmosphere. The 
estimated pressure in the dog = 29.6 ; in the cat =17.7; in the rabbit =12 mm. Hg., i. e., in 
the dog 3 times, the rabbit 4 times, and the cat 5 times less than the carotid pressure. 
(2) Hering (1850) experimented upon a calf with ectopia cordis. He introduced glass tubes 
directly into the heart, by pushing them through the muscular walls of the ventricles. The blood 
rose to the height of 21 inches in the right tube, and 33.4 inches in the left. 
(3) (F’aivre (1856) introduced a catheter through the jugular vein into the right ventricle, and 
placed it in connection with a recording tambour. 
Indirect measurements have been made by comparing the relative thickness of the walls of 
the right and left ventricles, or the walls of the pulmonary artery and aorta. 
Beutner and Marey estimated the relation of the pulmonary artery to the 
aortic pressure as 1 to 3; Goltz and Gaule as 2 to 5 ; Fick and Badoud found 
a pressure of 60 mm. in the pulmonary artery of the dog, and in the carotid 
111 mm. Hg. The blood-pressure within the pulmonary artery of a child is rela- 
tively higher than in the adult. 
Elastic Tension of Lungs.—The lungs within the chest are kept in a 
state of distention, owing to the fact that a negative pressure exists on their 
outer pleural surface. When the glottis is open, the inner surface of the lung 
and the walls of the capillaries in the pulmonary air-vesicles are exposed to the 152 
ELASTIC TENSION OF LUNGS. 
[Sec. 88. 
full pressure of the air. The heart and large blood-vessels within the chest 
are not exposed to the full pressure of the atmosphere, but only to the pressure 
which corresponds to the atmospheric pressure minus the pressure exerted by 
the elastic traction of the lungs (§ 60). The trunks of the pulmonary artery 
and veins are subjected to the same conditions of pressure. The elastic traction 
of the lungs is greater the more they are distended. The blood of the pulmo- 
nary capillaries will, therefore, tend to flow towards the large blood-vessels. 
As the elastic traction of the lungs acts chiefly on the thin-walled pulmonary 
veins, while the semi-lunar valves of the pulmonary artery, as well as the systole 
of the right ventricle, prevent the blood from flowing backwards, it follows 
that the blood in the capillaries of the lesser circulation must flow towards the 
pulmonary veins. 
If tubes with thin walls be placed in the walls of an elastic distensible bag, 
the lumen of these tubes changes according to the manner in which the bag 
enclosing them is distended. If the bag be directly inflated so as to increase 
the pressure within it, the lumen of the tubes is diminished (Funke and Lat- 
schenberger). If the bag be placed within a closed space, and the tension within 
this space be diminished so that the bag thereby becomes distended, the tubes 
in its wall dilate. In the latter case—viz., by negative aspiration—the lungs 
are kept distended within the thorax, hence the blood-vessels of the lungs con- 
taining air are wider than those of collapsed lungs ( Quincke and Pfeiffer, Bow- 
ditch a?id Garland, De Jdger). Hence also more blood flows through the 
lungs distended within the thorax than through collapsed lungs. The dilatation 
which takes place during inspiration acts in a similar manner. The negative 
pressure that obtains within the lungs during inspiration causes a considerable 
dilatation of the pulmonary veins, into which the blood of the lungs flows 
readily, whilst the bbood under high pressure in the thick-walled pulmonary 
artery scarcely undergoes any alteration. The velocity of the blood-stream in 
the pulmonary vessels is accelerated during inspiration (De Jdger, Lalesque). 
The blood-pressure in the pulmonary circuit is raised when the lungs are inflated. 
Contraction of small arteries, which causes an increase of the blood-pressure in 
the systemic circulation, also raises the pressure in the pulmonary circuit, be- 
cause more blood flows to the right side of the heart. 
The vessels of the pulmonary circulation are very distensible and their tonus 
is slight. [Occlusion of one branch of the pulmonary artery does not raise the 
pressure within the aorta. Even when one pulmonary artery is plugged with an 
embolon of paraffin, the pressure within the aortic system is not raised (.Lich- 
theim.) When a large branch of the pulmonary artery becomes impervious, 
the obstruction is rapidly compensated for, and this is not due to the action of 
the nervous system. The vaso-motor system has much less effect upon the pul- 
monary blood-vessels than upon those of the systemic circulation. The com- 
pensation seems to be due chiefly to the great distensibility and dilatation of 
the pulmonary vessels (LichtJieini).~] We know little of the effect of physio- 
logical conditions upon the pulmonary artery. According to Lichtheim sus- 
pension of the respiration causes an increase of the pressure. [In one experi- 
ment he found that the pressure within the pulmonary artery was increased, 
while it was not increased in the carotid, and he regards this experiment as 
proving the existence of vaso-motor nerves in the lung. While asphyxia in- 
creases enormously the blood-pressure in the systemic arteries, it has very little 
or no effect on the pressure as measured in the pulmonary system, although the 
latter is provided with vaso-motor nerves (§ 371)-] 
During the act of great straining the blood at first flows rapidly out of the pulmonary veins, 
and afterwards ceases to flow, because the inflow of blood into the pulmonary vessels is inter- 
fered with. As soon as the straining ceases, blood flows rapidly into the pulmonary vessels 
(Lalesque). Sec. 88.] 
VELOCITY OF THE BLOOD-STREAM. 
Severini found that the blood-stream through the lungs is greater and more rapid when the 
lungs are filled with rich air in C02 than when the air within them is rich in O. He supposes 
that these gases act upon the vascular ganglia within the lung, and thus affect the diameter of 
the vessels. 
Pathological.—Increase of the pressure within the area of the pulmonary artery occurs- 
frequently in man, in certain cases of heart disease. In these cases the second pulmonary 
sound is always accentuated, while the elevation caused thereby in the cardiogram is always- 
more marked and occurs earlier ($ 52). Electrical and mechanical stimulation of abdominal 
organs raises the blood-pressure in the pulmonary artery (Morel). 
[The action of drugs on the pulmonary circulation may be tested by Holmgren’s apparatus 
(£ 94), which permits of distention of the lung and retention of the normal circulation in the 
frog. Cold contracts the pulmonary capillaries to one-third of their diameter, and anaesthetics 
arrest the pulmonary circulation, chloroform being most and ether least active, while ethidene 
is intermediate in its effect.] 
[Influence of the Nervous System on the Pulmonary Circula- 
tion.—It is much less dependent on the nervous system than the systemic cir- 
culation, but recent experiments have shown that the pulmonary vessels are 
supplied by vaso-motor nerves through the roots of the uppermost (2-7) dorsal 
nerves (§ 371). Very considerable variations of the blood-pressure within the 
other parts of the body may occur, while the pressure within the right heart 
and pulmonary artery is but slightly affected thereby. The pressure is in- 
creased by electrical stimulation of the medulla oblongata, and it falls when 
the medulla is destroyed. Section and stimulation of the central or peripheral 
ends of the vagi, stimulation of the splanchnics, and of the central end of the 
sciatic, have but a minimal influence on the pressure of the pulmonary artery 
(Aubert).J 
[Relation of pressure in pulmonary and systemic circulations.— 
If the blood-pressure be measured simultaneously, in a curarized dog, in the 
carotid, and in a branch of the pulmonary artery—the chest being opened and 
artificial respiration being kept up—it is found that the pulmonary circulation 
is comparatively independent of the systemic, and alterations in the blood-pres- 
sure of the latter must be of large amount to affect the pulmonary blood-pres- 
sure. While stimulation of the peripheral end of the splanchnic nerve raised 
the pressure from 50 mm. Hg. in the carotid to 104 mm., it raised that in the 
pulmonary artery from 13 to 16 mm. Hg. Even stimulation of the lower end 
of the divided spinal cord, which raised the carotid pressure from 52 to 232 mm. 
(i. e., quadrupled it) only raised the pulmonary artery blood-pressure from 20 
to 26 mm. The rise in the pulmonary blood-pressure is but a small fraction of 
the total pulmonary artery pressure. The increased pressure in the aortic sys- 
tem must be of considerable duration to effect the rise in the pulmonary vessels.] 
[If the anterior roots of the dorsal nerves—between the second and seventh 
dorsal nerves—be stimulated, an increase is obtained in the pulmonary artery 
blood-pressure. This is due to the vaso-motor nerves, or vaso-constrictor 
nerves for the lungs, which leave the cord by these channels. The vaso-motor 
mechanism of the mammalian lung is but poorly developed as compared with 
that regulating the systemic arteries. Asphyxia, of course, raises the systemic 
pressure enormously, but it also raises that in the pulmonary artery, and the rise 
lasts longer in the latter than in the former. No vaso-motor nerves are con- 
veyed by the vagi to the lungs (Bradford and Dean).~\ 
89. VELOCITY OF THE BLOOD-STREAM.—Methods: (1) A. W. Volk- 
mann’s Haemadromometer (1850).—A glass tube of the shape of a hair-pin, 60-130 cm. long 
and 2 or 3 mm. broad, with a scale attached to it, is fixed to a metallic basal plate B, so that 
each limb passes to a three-wayed stop cock. The basal plate is perforated along its length, and 
carries at each end short cannulm, c, c, which are tied into the ends of a divided artery. The 
whole apparatus is first filled with salt solution. The stop-cocks are moved simultaneously, as 
they are attached to a toothed wheel, and have at first the position given in fig. 125, I, so that 
the blood simply flows through the passage in the basal piece, i. <?., directly from one end of the 154 
ESTIMATION OF THE VELOCITY OF THE BLOOD. 
[Sec. 89. 
.artery to the other. If at a given moment the stop-cock is turned in the direction indicated in 
fig. 125, II, the blood has to pass through the glass tube, and the time it takes to make the circuit 
is noted; and as the length of the tube is known, we can easily calculate the velocity of the 
blood. The method has very obvious defects arising from the narrowness of the tube; the in- 
troduction of such a tube offers new resistance, while there are no res- 
piratory or pulse variations observable in the stream in the glass tube. 
Volkmann found the velocity in the carotid (dog) = 
205 to 357 mm. [10-12 inches] ; carotid (horse) = 306 ; 
maxillary (horse) = 232; metatarsal = 56 mm. per second. 
(2) C. Ludwig and Dogiel (1867) devised a “ stro- 
muhr ” or rheometer for measuring the amount of blood 
which passed through an artery in a given time (fig. 126). 
It consists of two glass bulbs, A and B, of exactly the same capacity. 
These bulbs communicate with each other above, their lower ends being 
fixed by means of the tubes, c and d, to the metal disc, e, ev This disc 
rotates round the axis, X, Y, so that, after a complete revolution, the 
tube c communicates with f, and d with g; f and g are provided with 
horizontally placed cannulas, h and k, which are tied into the ends of 
the divided artery. The cannula h is fixed in the central end, and k in 
the peripheral end of the artery (e.g., carotid); the 
bulb, A, is filled with oil. and B with defibrinated 
blood; at a certain moment the communication 
through h is opened, the blood flows in, driving the 
oil before it, and passes into B, while the defibrinated 
blood flows through k into the peripheral part of the 
artery. As soon as the oil reaches m—a moment 
which is instantly noted, or, what is better, inscribed 
upon a revolving cylinder—the bulbs, A, B, are rotated 
upon the axis X, Y, so that B comes to occupy the 
position of A. The same experiment is repeated, 
and can be continued for a long time. The quantity 
of blood which passes in the unit of time (1 sec.) is 
calculated from the time necessary to fill the bulb 
with bh od. Important results are obtained by means 
of this instrument. 
[Suppose the capacity of the bulb to be 5000 cubic 
millimetres, and that it was filled in 10 secs., then 
500 cubic millimetres are discharged in 1 sec. The 
velocity (V) = quantity or volume of blood, (v) divi- 
ded by the sectional area of the vessel (j), i. <?., V sc ? 
c ,, , .. soo cubic millimetres s 
therefore the velocity V = A 
3-14 
159 mm. per second. In this cace the diameter of the 
Ludwig and Dogiel’s 
rheometer. X,Y,axis 
of rotation; A, B, 
glass bulbs ; h, k, can- 
nulas inserted in the di- 
vided artery; e, ev ro- 
tates on g, f; c, d, 
tubes. 
Fig. 126 
Fig. 125. 
Volkmann’s haemadromometer (B). I, blood flows from artery to 
artery; II, blood must pass through the glass tube of B; c, c, can- 
nula for the divided artery. 
tube is taken as 2 mm., so that the sectional area of the artery is equal to 3.14 mm. The 
sectional area is calculated from the diameter of the circular tube by the following formula: 
the sectional area s = 1 d2 when d is the diameter of the tube; or s = rrr2. where n = 3.1416, 
r — radius. Or the sectional area (s) is equal to the d2 X 0.7854, i. e., 4 X 0.7854 = 3.1416.] Sec. 89.] 
ESTIMATION OF THE VELOCITY OF THE BLOOD. 
155 
[As albumose injected into the blood prevents it from coagulating (dog), this fact has been 
turned to account in using the rheometer.] 
(3) Vierordt’s Haematachometer (1858) consists of a small metal box (fig. 127, I) with 
parallel glass sides. To the narrow sides of the box are fitted an inlet e, and an exit cannula a. 
In its interior is suspended, against the entrance opening, a pendulum, p, whose vibrations may 
be read off on a curved scale. [This instrument, as well as Volkmann’s apparatus, has only an 
historical interest.] 
(4) Chauveau and Lortet’s Dromograph (i860) is constructed on the same principle. 
A tube, A, B (fig. 127, II), of sufficient diameter, with a side tube fixed to it, C, which can be 
placed in connection with a manometer, is introduced into the carotid artery of a horse. At a 
a small piece is cut out and provided with a covering of gutta percha which has a small hole in 
it; through this a light pendulum, a, b, with a long index, b, projects into the tube, i. e., into 
the blood-current, which causes the pendulum to vibrate, and the extent of the vibrations can 
be read off on a scale, S, S. G is an arrangement to permit the instrument to be held. Both 
this and the former instrument are tested beforehand with a stream of water sent through them 
with varying velocities. 
1 he curve of the velocity may be written off on a smoked glass plate, moving parallel with the 
index, b. The dromograph curve, III, shows the primary elevation P, and the dicrotic eleva- 
tion R. 
i 
III 
T1 
I. Vierordt’s hsematachometer. A, glass; e, entrance, a, exit cannula; p, pendulum, II. 
DromogTaph. A, B, tube inserted in artery; C, lateral tube connected with a mano- 
meter; b, index moving in a caoutchouc membrane, a; G, handle. III. Curve obtained 
by dromograph. 
Fig. 127. 
(5) Cybulski’s Photohaematachometer.—When fluid flows into a tube (fig. 128, II, d, e) 
in the direction of the arrow, the fluid stands higher in the manometer, p, than in m. The 
tube, m,y, indicates the lateral pressure,but p,x gives this plus the velocity of the fluid (p. 105). 
The velocity of the current may be estimated from the difference in the level in the two tubes. 
Pitot’s tube as used by Cybulski is bent at a right angle (I, c,p), the end, c, being inserted 
and tied into the central, and p into the peripheral, part of a divided artery. As the blood flows 
through the tube, the blood rises higher in a than b. 
To avoid having the manometers, a and b, too long, they are connected with each other by a 
capillary tube filled with air and provided above with a stop-cock, i. The blood is allowed to 
rise to the height of 1 and 2, the stop cock, i, is closed, and practically an air-manometer is 
made, which shows a marked difference in the level of the blood of the two tubes. The level 
of the blood in 1 and 2 is continually changed by the movements of the heart and those of 
respiration, and these variations are photographed by means of a camera, n, with a rapidly 
moving plate, K. 
Fig. C shows a curve obtained from the carotid of a dog. The velocity of 
the current at ij - 1 = 238 mm., in the phase 2X - 2 = 225 mm., and at 3j - 156 
VELOCITY OF THE BLOOD. 
[Sec. 89. 
3=177 mm- The velocity is greatest at the end of inspiration and the begin- 
ning of expiration. Asphyxia increases it at first. Paralysis of the sympa- 
thetic increases it, while stimulation of this nerve diminishes it. Section of the 
vagi increases the velocity, while their stimulation of course diminishes it. 
90. VELOCITY OF THE BLOOD.—(1) Division of Vessels.— 
Arteries.—In estimating the velocity of the blood, it is important to remem- 
ber that the sectional area of all the branches of the aorta becomes greater as 
we proceed from the aorta towards the capillaries, so that the capillary area is 
700 times greater than the sectional area of the aorta. As the veins join and 
form larger trunks, the venous area gradually becomes smaller, but the sectional 
area of the venous orifices at the 
heart is greater than that of the cor- 
responding arterial orifices. [We 
may represent the result as two 
cones placed base to base (fig. 129), 
the bases meeting in the capillary 
area. The sectional area of the 
venous orifice (V) is represented 
larger than that of the arterial (A). 
The increased sectional area 
influences the velocity of the 
blood-current, while the resistance 
affects the pressure.] 
(2) Sectional Area.—An equal 
quantity of blood must pass through 
i. 
n. 
Fig. 129. 
Scheme of the sectional area. A, arterial, 
and V, venous orifice. The common 
iliacs are an exception; the sum of 
their sectional areas is less than that of 
the aorta; the sections of the four pul- 
monary veins are together less than 
that of the pulmonary artery. 
Fig. 128. 
I. Scheme of the photohsematachometer ; II. 
Pitot’s tube. 
every section of the circulatory system, through the pulmonic as well as through 
the systemic circulation, so that the same amount of blood must pass through the 
pulmonary artery and aorta, notwithstanding the very unequal blood-pressure 
in these two vessels. 
(3) Lumen or Sectional Area.—The velocity of the current, therefore, 
in various sections of the vessels, must be inversely as their sectional area. 
(4) Capillaries.—Hence the velocity must diminish very considerably as 
we pass from the root of the aorta and the pulmonary artery towards the capil- 
laries, so that the velocity in the capillaries of mammals = 0.8 millimetre 
per sec. ; frog = 0.53; man = 0.6 to 0.9 mm. [average 2 inches per minute]. Sec. 90.] 
CAPACITY OF THE VENTRICLES. 
157 
According to A. W. Volkmann, the blood in mammalian capillaries flows 500 
times slower than the blood in the aorta, so that the total sectional area of all 
the capillaries must be 500 times greater than that of the aorta. Donders found 
the velocity of the stream in the small afferent arteries to be 10 times faster 
than in the capillaries. 
Veins.—The current becomes accelerated in the veins, but in the larger 
trunks it is 0.5 to 0.75 times less than in the corresponding arteries. 
(5) Mean Blood-Pressure.—The velocity of the blood does not depend 
upon the mean blood-pressure, so that it may be the same in congested and in 
anaemic parts. 
(6) Difference of Pressure.—On the other hand, the velocity in any 
section of a vessel is dependent on the difference of the pressure which exists at 
the commencement and at the end of that particular section of a blood-vessel; 
it depends, therefore, on (1) the vis a tergo (/. e., the action of the heart), and 
(2) on the amount of the resistance at the periphery (dilatation or contraction 
of the small vessels). 
Corresponding to the smaller difference in the arterial and venous pressure in the foetus (§ 85), 
the velocity of the blood is less in this case (Cohnstein and Zuntz). 
(7) Pulsatory Acceleration.—With every pulse-beat a corresponding 
acceleration of the blood-current (as well as of the blood-pressure) takes place 
in the arteries (pp. 147, 154). In large vessels Vierordt found the increase of 
the velocity during the systole to be greater by to y2 than the velocity 
during the diastole. The variations in the velocity caused by the heart-beat 
are recorded in fig. 127, III, obtained by Chauveau’s dromograph from the 
carotid of a horse. The velocity curve corresponds with a sphygmogram—P 
represents the primary elevation and R the dicrotic wave. This acceleration, 
as well as the pulse, disappears in the capillaries. A pulsatory acceleration, 
more rapid during its first phase, is observable in the small arteries, although 
the arteries themselves are not distended thereby. 
(8) Respiratory Effect.—Every inspiration retards the velocity in the 
arteries, every expiration aids it somewhat ; but the value of these agencies is 
very small. 
If we compare what has already been said regarding the effect of the respiration on the con- 
traction and dilatation of the heart and on the blood-stream (§ 60), it is clear that respiration 
favors the blood-stream, and so does artificial respiration. When artificial respiration is inter- 
rupted, the blood-stream becomes slower (Dogiel). If the suspension of respiration lasts some- 
what longer, the current is again accelerated on account of the dyspnoeic stimulation of the 
vaso-motor centre (.Heidenhain) (§ 371, I.). 
(9) Modifying Conditions.—Many circumstances affect the velocity of 
the blood in the veins. There are regular variations in the large veins near 
the heart due to the respiration and the movements of the heart (§§ 50 and 60). 
(2) Irregular variations due to pressure, e. g., from contracting muscles 
(§ 87), friction on the skin in the direction or against the direction of the 
venous current; the position of a limb or of the body. The pump-like action 
of the veins of the groin on moving the leg has been referred to (§ 87). When 
the lower limb is extended and rotated outwards, the femoral vein in the iliac 
fossa collapses, owing to an internal negative pressure ; when the thigh is flexed 
and raised, it fills under a positive pressure (.Braune). A similar condition 
obtains in walking. 
91. CAPACITY OF THE VENTRICLES.—Vierordt calculated the capacity of the 
left ventricle from the velocity of the blood-stream, and the amount of blood discharged per 
second by the right carotid, right subclavian, the two coronary arteries, and the aorta below the 
origin of the innominate artery. He estimated that with every systole of the heart, 172 cubic 
centimetres (equal to 180 grams) of blood were discharged into the aorta; this, therefore, must 
be the capacity of the left ventricle (compare \ 83). 158 
WORK OF THE HEART. 
[Sec. 92. 
92. THE DURATION OF THE CIRCULATION. —The time re- 
quired by the blood to make a complete circuit through the course of the 
circulation was first determined by Hering (1829) in the horse. He injected 
a 2 per cent, solution of potassium ferrocyanide into a special vein, and ascer- 
tained (by means of ferric chloride) when this substance appeared in the blood 
taken from the corresponding vein on the opposite side of the body. The ferro- 
cyanide may also be injected into the central or cardiac end of the jugular 
vein, and the time noted at which its presence is detected in the blood of the 
peripheral end of the same vein. Vierordt (1858) improved this method by 
placing under the corresponding vein of the opposite side a rotating disc, on 
which was fixed a number of cups at regular intervals. The first appearance 
of the potassium ferrocyanide is detected by adding ferric chloride to the serum 
which separates from the samples of blood after they have stood for a time. 
The duration of the circulation is as follows:— 
Horse, . . 31.5 seconds. 
Dog, . . 16.7 “ 
Rabbit, . . 7.79 “ 
Hedgehoe, . 7.61 seconds. 
Cat, . . 6.69 “ 
Goose, . . 10.86 “ 
Duck, . 10.64 seconds. 
Buzzard, . 6.73 “ 
Fowl, . 5.17 “ 
Results.—When these numbers are compared with the frequency of the 
normal pulse-beat in the corresponding animals, the following deductions are 
obtained :— 
(1) The mean time required for the circulation is accomplished during 27 
heart-beats, i. e., for man = 32.2 seconds, supposing the heart to beat 72 times 
per minute. 
(2) Generally, the mean time for the circulation in two warm-blooded 
animals is inversely as the frequency of the pulse-beats. 
Modifying Conditions.—The time is influenced by the following fac- 
tors :— 
1. Long vascular channels [e. g., from the metatarsal vein of one foot to the other foot) 
require a longer time than short channels (as between the jugulars). The difference may be equal 
to 10 per cent, of the time required to complete the entire circuit. 
2. In young animals (with shorter vascular channels and higher pulse-rate) the time is 
shorter than in old animals. 
3. Rapid and energetic cardiac contractions (as during muscular exercise) diminish the 
time. Hence rapid and at the same time less energetic contractions (as after section of both 
vagi), and slow but vigorous systoles (e. g., after slight stimulation of the vagus) have no effect. 
C. Vierordt estimated the quantity of blood in a man in the following manner: In all 
warm blooded animals, 27 systoles correspond to the time for completing the circulation. Hence, 
the total mass of the blood must be equal to 27 times the capacity of the ventricle, i. <?., in man, 
187.5 grams. X 27 = 5062.5 grams. This is equal to of the body-weight in a person weigh- 
ing 65.8 kilos, (compare § 40). 
It is not to be forgotten that the salt used is to some extent poisonous, but Hermann uses the 
corresponding innocuous soda salt (25 per cent.). 
Pathological.—The duration of the circulation seems to be increased during septic fever 
{£. Wolff). 
93. WORK OF THE HEART.—The left ventricle expels 0.188 kilo, 
of blood with each systole, and in doing so it overcomes the pressure in the 
aorta, which is equal to a column of blood 3.21 metres in height. [The 
amount of blood expelled from each ventricle during the systole is about 188 
grams (6 oz.). It is forced out against a pressure of 250 mm. Hg. = 3.21 
metres of blood.] The work of the heart at each systole is 0.188 X 3.21 = 
0.604 kilogram-metre. If the number of beats = 75 per minute, then the 
work of the left ventricle in 24 hours == (0.604 X 75 X 60 X 24) = 65,230 
kilogram-metres ; while the “ work” done by the right ventricle is about one- 
third that of the left, and therefore = 21,740 kilogram-metres. Both ventricles 
do work equal to 86,970 kilogram-metres. A workman during eight hours 
produces 300,000 kilogram-metres, i. e., about four times as much as the heart. Sec. 93.] 
BLOOD-CURRENT IN SMALL ARTERIES. 
As the whole of the work of the heart is consumed in overcoming the resistance 
within the circulation, or rather is converted into heat, the body must be partly 
warmed thereby—(425.5 gram-metres are equal to 1 heat-unit, i. e., the force 
required to raise 425.5 grams to the height of 1 metre may be made to raise 
the temperature of 1 cubic centimetre of water i° C.). So that 204,000 “ heat- 
units” are obtained from the transformation of the daily kinetic energy of the 
heart. 
One gram of coal when burned yields 8080 heat-units, so that the heart yields 
as much energy per day for heating the body as if about 25 grams of coal were 
burned within it to produce heat. 
94. BLOOD-CURRENT IN THE SMALLER VESSELS.— 
Methods.—The most important observations for this purpose are made by 
means of the microscope on transparent parts of living animals. Malpighi 
was the first to observe the circulation in this way in the lung of a frog (1661). 
The following parts have been employed: The tails of tadpoles and small fishes; the web,, 
tongue, mesentery, and lungs of curarized frogs; the wing of the bat; the third eyelid of the 
pigeon or fowl; the mesentery; the vessels of the liver of frogs and newts, pia mater of rabbits, 
the skin on the belly of the frog, the mucous membrane of the inner surface of the human lip 
[Hilter's Cheilangioscope, 1879); the conjunctiva of the eyeball and eyelids. All these may be 
examined by reflected light. 
[Holmgren’s Method.—In studying the circulation in the frog’s lung, it must be inflated.. 
A cannula with a bulge on its free end is placed in the larynx, while to the other end is fixed a 
piece of caoutchouc tubing. The lung is inflated and then the caoutchouc tube is closed,, 
after which the lung is placed in a chamber with glass above and below, and examined micro- 
scopically.] 
[Entoptical appearances of the circulation [Purkinje, 1815). Under certain conditions a 
person may detect the movement of the blood-corpuscles within the blood-vessels of his own 
eye. The best method is that of Rood, viz., to look at the sky through a dark blue glass, or 
through several pieces of cobalt glass placed over each other [Helmholtz).'] 
Form and Arrangement of Capillaries.—Regarding the form and arrangement of the 
capillaries, we find that— 
1. The diameter which, in the finest, permits only the passage of single corpuscles in a row— 
one behind the other—may vary from 5 fi to 20 n, so that two or more corpuscles may move 
abreast when the capillary is at its widest. [The capillaries are relatively wide in the lungs,, 
and narrow in the brain, retina, and liver.] 
2. The length is about 0.5 mm. They terminate in small veins. 
3. The number is very variable, and the capillaries are most numerous in those tissues where 
the metabolism is most active, as in the lungs, liver, muscles—less numerous where the meta- 
bolism is slight, as in the sclerotic and in the nerve-trunks. [Many tissues are devoid of blood- 
vessels, e.g., the cornea, nails, hairs.] 
4. They form numerous anastomoses, and give rise to networks, whose form and arrange- 
ment are largely determined by the arrangement of the tissue elements themselves. They form, 
simple loops in the skin, and polygonal networks in the serous membranes, and on the surface 
of many gland tubes; they occur in the form of elongated networks, with short connecting 
branches in muscle and nerve, as well as between the straight tubules of the kidney; they con- 
verge radially toward a central point in the lobules of the liver, and form arches in the free 
margins of the iris, and on the limit of the sclerotic and cornea. 
[Direct Terminations of Arteries in Veins.—Arteries sometimes terminate directly in 
veins, without the intervention of capillaries, e.g., in the ear of the rabbit, in the terminal 
phalanges of the fingers and toes in man and some animals, in the cavernous tissue of the penis. 
They may be regarded as secondary channels which protect the circulation of adjacent parts, 
and they may also be related to the heat-regulating mechanisms of peripheral parts [Hoyer).] 
In connection with the termination of arteries in capillaries, it is important to ascertain if the 
arterioles are terminal arteries, i. e., if they do not form any further anastomoses with other 
similar arterioles, but terminate directly in capillaries, and thus only communicate by capillaries- 
with neighboring arterioles—or the arteries may anastomose with other arteries just before they 
break up into capillaries. This distinction is important in connection with the nutrition of parts 
supplied by such arteries [Cohnheim). 
Capillary Circulation.—On observing the capillary circulation, we notice 
that the red corpuscles move only in the axis of the current (axial current), THE CAPILLARY CIRCULATION. 
[Sec. 94. 
while the lateral transparent plasma-current flowing on each side of this central 
thread is free from these corpuscles. [The axial current is the more rapid.] 
This plasma layer or “Poiseuille’s space” is seen in the smallest arteries 
and veins, where -§- are taken up with the axial current, and the plasma layer 
occupies £ on each side of it (fig. 130). A great many, but not all, of the 
colorless corpuscles move in this layer. It is much less distinct in the capilla- 
ries. Rud. Wagner stated that it is absent in the finest vessels of the lung and 
gills [although Gunning was unable to confirm this statement]. The colored 
corpuscles move in the smallest capillaries in single file one after the other; in 
the larger vessels, several corpuscles may move abreast, with a gliding motion, 
and in their course they may turn over and even be twisted if any obstruc- 
tion is offered to the blood-stream. As a general rule, in these vessels the 
movement is uniform, but at a sharp bend of the vessel it may partly be retarded 
and partly accelerated. Where a vessel divides, not unfrequently a corpuscle 
remains upon the projecting angle of the division, and is doubled over it so 
that its ends project into the two branches of the tube. There it may remain 
for a time, until it is dislodged, when it soon regains its original form on account 
of its elasticity. Not unfrequently we see a red corpuscle becoming bent 
where two vessels meet, but on all occasions it rapidly regains its original form. 
This is a good proof of the elasticity of the colored corpuscles. The motion of 
the colorless corpuscles is quite different in character; they roll directly 
on the vascular wall, moistened on their peripheral zone by the plasma in 
Poiseuille’s space, their other surface being in contact with the thread of col- 
ored corpuscles in the centre of the stream. Schklarewsky (1868) has shown 
by physical experiments that the particles of least specific gravity in all capilla- 
ries (e.g., of glass) are pressed toward the wall, while those of greater specific 
gravity remain in the middle of the stream. [Graphite and particles of car- 
mine were suspended in water, and caused to circulate through capillary tubes 
placed under a microscope, when the graphite kept the centre of the stream, 
and the carmine moved in the layer next the wall of the tube.] 
When the colorless corpuscles reach the wall of the vessel, they must roll 
along, partly on account of their surface being sticky, whereby they readily 
adhere to the vessel, and partly because one surface is directed towards the axis 
of the vessel where the movement is most rapid, and where they receive im- 
pulses directly from the rapidly moving colored blood-corpuscles (Bonders). 
The rolling motion is not always uniform ; not unfrequently it is retrograde in 
direction, which seems to be due to an irregular adherence to the vascular wall. 
The slower movement (10 to 12 times slower than the red corpuscles) is partly 
due to their stickiness, and partly to the fact that, as they are placed near the 
wall, a large part of their surface lies in the peripheral threads of the fluid, which 
of course move more slowly (in fact, the layer of fluid next the wall is passive 
—p. 106). 
[D. J. Hamilton finds that when a frog’s web is examined in a vertical position, by far the 
greater proportion of leucocytes float on the upper surface, and only a few on the lower surface, 
of a small blood-vessel. In experiments to determine why the colored corpuscles float or glide 
exclusively in the axial stream, while a great many, but not all, of the leucocytes roll in the 
peripheral layers, Hamilton ascertained that the nearer the suspended body approaches to the 
specific gravity of the liquid in which it is immersed, the more it tends to occupy the centre of 
the stream. He is of opinion that the phenomenon of the separation of the blood-corpuscles in 
the circulating fluid is due to the colorless corpuscles being specifically lighter, and the colored 
either of the same or of very slightly greater specific gravity than the blood-plasma. Hamilton 
•controverts the statement of Schklarewsky, and he finds that it is the relative specific gravity 
of a body which ultimately determines its position in a tube. These experiments point to the 
immense importance of a due relation subsisting between the specific gravity of the blood-plasma 
and that of the corpuscles.] 
In the vessels first formed in the incubated egg, as well as in young tadpoles, the movement 
■of the blood from the heart occurs in jerks (Spallanzani, 1768). Sec. 94.] 
DIAPEDESIS. 
161 
The velocity of the blood-stream is influenced by the diameter of the vessels, 
which undergo periodic changes of calibre. This change occurs not only in 
vessels provided with muscular fibres, but also in the capillaries, which vary 
in diameter, owing to the contraction of the cells composing their walls 
(P- II3> 
The amount of water in the blood is of importance ; when it is increased, the 
circulation is facilitated and accelerated (§ 62). 
The velocity of the blood is greater in the pulmonary than in the systemic 
capillaries; so that the total sectional area of the pulmonary capillaries is less 
than that of all the systemic capillaries. 
g5. DIAPEDESIS.—If the circulation be studied in the vessels of the mesentery, we may 
observe colorless corpuscles passing out of the vessels in greater or less numbers (fig. 130). 
Mere contact with the air suffices to excite slight inflammation. At first the colorless cor- 
puscles in the plasma-space move more slowly; several accumulate near each other, and adhere 
to the walls;—soon they bore into the wall, ultimately they pass quite through it, and may 
wander for a distance into the perivascular tissues. It is doubtful whether they pass through 
the so-called “ stomata ” which exist between the endothelial cells, or whether they simply pass 
through the cement substance between the endothelial cells (p. no). This process is called 
diapedesis, and consists of several acts:—(a) The adhesion of colorless corpuscles to the inner 
surface of the vessel (after moving more slowly along the wall up to this point). (£) They send 
processes into and through the vascular wall, (r) The body of the cell is drawn after or follows 
the processes, whereby the corpuscle appears constricted in the centre (fig. 130, c). (d) The 
complete passage of the corpuscle through the wall, and its farther motion in virtue of its own 
amoeboid movements. Hering observed that in large vessels with perivascular lymph-spaces, the 
corpuscles passed into the spaces, hence cells are found in lymph beffire it has passed through 
lymphatic glands. The cause of the diapedesis is partly due to the independent locomotion of 
the corpuscles, and it is partly a physical act, viz., a filtration of the colloid mass of the cell 
under the force of the blood-pressure (Hering)—in the latter respect depending upon the intra- 
vascular-pressure and the velocity of the blood stream. Hering regards this process, and even 
the passage of the colored corpuscles through the vascular wall, as a normal process. The red 
corpuscles pass out of the vessels when the venous outflow is obstructed, which also causes the 
transudation of plasma through the vascular wall. The plasma carries the colored corpuscles 
along with it, and at the moment of their passage through the wall they assume extraordinary 
shapes, owing to the tension put upon them, regaining their shape as soon as they pass out 
(Cohnheim). This remarkable phenomenon wasdescribed by Waller in 1846. It was redescribed 
by Cohnheim, and according to him the out-pandering is a sign of inflammation, and the 
colorless corpuscles which accumulate in the tissues are to be regarded as true pus-corpuscles, 
which may undergo further increase by division. 
Inflammation and Stasis.—When a strong 
stimulus acts on a vascular part, hypersemic 
redness and swelling occur. Microscopic ob- 
servation shows that the capillaries and the small 
vessels are dilated and overfilled with blood cor- 
puscles; in some cases, a temporary narrowing 
precedes the dilatation ; simultaneously the ve- 
locity of the stream changes, rarely there is a 
temporary acceleration, more frequently it be- 
comes slower. If the action of the stimulus 
or irritant be continued, the retardation be- 
comes considerable, the stream moves in jerks, 
then follows a to-and-fro movement of 
the blood-column—a sign that stagnation has 
taken place in other vascular areas. At last the 
blood-stream comes completely to a standstill— 
stasis — and the blood-vessels are plugged 
with blood-corpuscles. Numerous colorless 
blood-corpuscles are found in the stationary 
blood. Whilst these various processes are 
taking place, the colorless corpuscles—more 
rarely the red—pass out of the vessels. Under 
favorable circumstances the stasis may dis- 
appear. The swelling which occurs in the neighborhood of inflamed parts is chiefly due to the 
exudation of plasma into the surrounding tissues. 
Fig. 130. 
Small vessel of a frog’s mesentery showing 
diapedesis. w, w, vascular walls; a, a, 
Poiseuille’s space; r, r, red corpuscles; /, /, 
colorless corpuscles adhering to the wall, and 
c, c, in various stages of extrusion ; f, ex- 
truded corpuscles. BLOOD-CURRENT IN THE VEINS. 
[Sec. 96. 
96. MOVEMENT OF THE BLOOD IN THE VEINS.—In the 
smallest veins coming from the capillaries the blood-stream is more rapid than 
in the capillaries themselves, but less so than in the corresponding arteries. 
The stream is uniform, and if no other conditions interfered with it, the venous 
stream towards the heart ought to be uniform, but many circumstances affect 
the stream in different parts of its course. Amongst these are:—(1) The rela- 
tive laxness, great distensibility, and the ready cotnpressibility of the walls, even 
of the thickest veins. (2) The incomplete filling of the veins, which does not 
amount to any considerable distention of their walls. (3) The numerous and 
free anastomoses between adjoining veins, not only between veins lying in the 
same plane, but also between superficial and deep veins. Hence, if the course 
of the blood be obstructed in one direction, it readily finds another outlet. 
(4) The presence of numerous valves which permit the blood-stream to move 
only in a centripetal direction. They are absent from the smallest veins, and 
are most numerous in those of middle size. 
Position of Valves.—The venous valves always have two pouches, and are placed at definite 
intervals, which correspond to the 1, 2, 3, or nth power of a certain “ fundamental distance,” 
which is = 7 mm. for the lower extremity and 5.5 mm. for the upper. Many of the original 
valves disappear. On the proximal side of every valve a lateral branch opens into the vein, 
while on the distal side of each branch lies a valve. The same is true for the lymphatics 
[K. Bardeleben). 
Effect of Pressure.—As soon as pressure is applied to the veins, the next 
lowest valves close, and those immediately above the seat of pressure open and 
allow the blood to move freely toward the heart. The pressure may be exerted 
from without, as by anything placed against the body ; the thickened contracted 
muscles, especially the muscles of the limbs, compress the veins. That the 
blood flows out of a divided vein more rapidly when the muscles contract is 
shown during venesection. If the muscles are kept contracted, the venous blood 
passing out of the muscles collects in the passive parts, e. g., in the cutaneous 
veins. The pulsatile pressure of the arteries accompanying the veins favors the 
venous current. From a hydrostatic point of view the valves are of consid- 
erable importance, as they serve to divide the column of blood into segments 
(e.g., in the crural vein in the erect attitude), so that the fine blood-vessels in 
the foot are not subjected to the whole amount of the hydrostatic pressure in 
the veins. 
The velocity of the venous blood has been measured directly (with the haemadromometer and 
the rheometer—§ 89). Volkmann found it to be 225 mm. per sec. in the jugular vein. Reil 
observed that 2*4 times more blood flowed from an arterial orifice than from a venous orifice of 
the same size. The velocity of the venous current obviously depends upon the sectional area of 
the vessel. Borelli estimated the capacity of the venous system to be 4 times greater than that 
of the arterial; while, according to Haller, the ratio is 9 to 4. 
Large Veins.—As we proceed from the small veins towards the venae cavae, 
the sectional area of the veins, taken as a whole, becomes less, so that the 
velocity of the current increases in the same ratio. The velocity of the current 
in the venae cavae may be about half of that in the aorta (Haller). As the 
pulmonary veins are narrower than the pulmonary artery, the blood moves 
more rapidly in the former. 
97. SOUNDS WITHIN ARTERIES. —The sounds produced within arteries are, speak- 
ing from a physical point of view, only noises or bruits. Still, following Skoda’s lead, they are 
spoken of by physicians as “ tones.” Clinically, there is no sharp distinction between “ tones,” 
sounds, noises, or bruits. In four-fifths of all healthy men two sounds—corresponding in dura- 
tion and other characters to the two heart-sounds—are heard in the carotid (Conrad, Weil). 
Sometimes only the second heart-sound is distinguishable, as its place of origin is near to the 
carotid. They are not true arterial sounds, but are simply “ propagated heart-sounds.” 
Sometimes the sound of the pulmonary artery can be heard in this way ( Weil, Bettelheim). Sec. 97.] 
SOUNDS PRODUCED WITHIN BLOOD-VESSELS. 
163 
These murmurs, sounds, or bruits occur either spontaneously, or are produced by the application 
of external pressure, whereby the lumen of the vessel is diminished. Hence one distinguishes : 
(i) Spontaneous Murmurs, and (2) Pressure Murmurs. 
Arterial Sounds or murmurs are readily produced by pressing upon a 
strong artery, e.g., the crural in the inguinal region, so as to leave only a nar- 
row passage for the blood (“ stenosal murmur ”). A fine blood-stream 
passes with great rapidity and force through this narrow part into a wider 
portion of the artery lying behind the point of compression. Thus arises the 
“ pressure-stream ” (P. Niemeyer), or the “ fluid vein ” (“ veine fluide ” of 
Chauveau). The particles of the fluid are thrown into rapid oscillation, and 
undergo vibratory movements, and by their movements produce the sound 
within the peripheral dilated portion of the tube. A sound is produced in the 
fluid by pressure (Corrigan). The sounds are not caused by vibrations of the 
vascular wall, as supposed by Bouillaud. 
A murmur of this sort is the “ sub-clavicular murmur” (/loser), occasionally heard during 
systole in the subclavian artery; it occurs when the two layers of the pleura adhere to the apex 
of the lung (especially in tubercular diseases of the lungs), whereby the subclavian artery 
undergoes a local constriction due to its being made tense and slightly curved (Friedreich). 
This result is indicated in a diminution or absence of the pulse-wave in the radial artery ( Weil). 
It is obvious that arterial murmurs will occur in the human body: (a) When, owing to 
pathological conditions, the arterial tube is dilated at one part, into which the blood-current is 
forcibly poured from the normal narrow tube. Dilatations of this sort are called aneurisms, 
in which murmurs are generally audible, (b) When pressure is exerted upon an artery, e. g., 
by the pressure of the greatly enlarged arteries during pregnancy, or by a large tumor pressing 
upon a large artery. 
Spontaneous Murmurs.—In cases where no source of external pressure is discoverable, and 
when no aneurism is present, the spontaneously occurring sounds are favored, when at the 
moment of arterial rest (cardiac systole) the arterial walls are distended to the slightest extent, 
and when during the movement of the pulse (cardiac diastole) the tension is most rapid (Traube, 
Weil), i. e., when the low systolic minimum tension of the arterial wall passes rapidly into the 
high maximum tension. This is especially the case in insufficiency of the aortic valves, in 
which case the sounds in the arteries are audible over a wide area. If the minimum tension of 
the arterial wall is relatively great, even during diastole, the sounds in the arteries are greatly 
diminished. 
Arterial murmurs are favored by—(1) Sufficient delicacy and elasticity of 
the arterial walls. (2) Diminished peripheral resistance, e. g., an easy outflow 
of the fluid at the end of the stream. (3) Accelerated current in the vascular 
system generally. (4) A considerable difference of the pressure in the narrow 
and wide portions of the tube. (5) Large calibre of the arteries. 
In normal pulsating arteries, sounds may be heard especially at an acute bend of the artery. 
Murmurs of this sort, are loudest where several large arteries lie together; hence, during 
pregnancy, we hear the uterine murmur, or placental bruit, or souffle in the greatly dilated 
uterine arteries. It is much less distinct in the umbilical arteries of the cord (umbilical 
murmurs). Similar sounds are heard through the thin walls of the head of infants, and a 
murmur is sometimes heard in the enlarged spleen in ague (Maissurianz). 
Auscultation of the Normal Pulse.—On auscultating the radial artery under favorable 
circumstances, and especially in old thin persons with wide arteries and dicrotic pulse, one may 
hear two sounds corresponding to the primary and dicrotic waves. 
In insufficiency of the aortic valves, characteristic sounds may be heard in the crural 
artery. If pressure be exerted upon the artery, a double blowing murmur is heard; the first one 
is due to a large mass of blood being propelled into the artery synchronously with the heart-beat, 
the second to the fact that a large quantity of blood flows back into the heart during diastole. If 
no pressure be exercised two sounds are heard, and these seem to be due to a wave propagated 
into the arteries by the auricles and ventricles respectively—compare $ 73, fig. 95, III. In 
atheroma a double sound may sometimes be heard ($ 73, 2). 
98. VENOUS MURMURS.—I. Bruit de Diable.—This sound is 
heard above the clavicles in the furrow between the two heads of the sterno- 
mastoid, most frequently on the right side, and in 40 per cent, of all persons 
examined. It is either a continuous or a rhythmical murmur, occurring during 164 
VENOUS PULSE AND PHLEBOGRAM. 
[Sec. 98. 
the diastole of the heart or during inspiration ; it has a whistling or rushing 
character, or even a musical quality, and arises within the bulb of the common 
jugular vein. When this sound is heard without pressure being exerted by the 
stethoscope, it is a pathological phenomenon. If, however, pressure be exerted, 
and if, at the same time, the person examined turn his head to the opposite 
side, a similar sound is heard in nearly all cases. The pathological bruit de 
diable occurs especially in anaemic persons, in lead-poisoning, in syphilitic and 
scrofulous persons, sometimes in young persons, and less frequently in elderly 
people. Sometimes a thrill of the vascular wall may be felt. 
Causes.—It is due to the vibration of the blood flowing in from the rela- 
tively narrow part of the common jugular vein into the wide bulbous portion of 
the vessel, and seems to occur chiefly when the walls of a thin part of the vein 
lie close to each other, so that the current must purl through it. It is clear that 
pressure from without, or lateral pressure, as by turning the head to the opposite 
side, must favor its occurrence. Its intensity will be increased when the velocity 
of the stream is increased, hence inspiration and the diastolic action of the heart 
(both of which assist the venous current) increase it. The erect attitude acts 
in a similar manner. A similar bruit is sometimes, though rarely, heard in the 
subclavian,axillary, thyroid, facial,innominate and crural veins, and superior cava. 
II. Regurgitant Murmurs.—On making a sudden effort, a murmur may be heard in the 
crural vein during expiration, which is caused by a centrifugal current of blood, owing to the 
incompetence or absence of the valves in this region. If the valves at the jugular bulb are not 
tight, there may be a bruit with expiration (expiratory jugular vein bruit—Hamernjk), or 
during the cardiac systole (systolic jugular vein bruit—v. Bamberger). 
III. Valvular Sounds in Veins.—When the tricuspid valve is incompetent during the ven- 
tricular systole, a large volume of blood is propelled backwards into the venae cavae. The 
venous valves are closed suddenly thereby and a sound produced. This occurs at the bulb or 
dilatation on the jugular vein (v. Bamberger), and in the crural vein at the groin (W. Friedreich), 
i. e., only as long as the valves are competent. Forced expiration may cause a valvular sound 
in the crural vein. No sound is heard in the veins under perfectly normal circumstances. 
99. THE VENOUS PULSE—PHLEBOGRAM.—Methods.—A tracing of the move- 
ments of a vein, taken with a lightly weighted sphygmograph, has a characteristic form, and is 
called a phlebogram (fig. 131). In order to interpret the various events of the phlebogram it 
is most important to record simultaneously the events that take place in the heart. The auricular 
contraction (compare fig. 47) is synchronous with a b; be, with the ventricular systole, during 
which time the first sound occurs, whilst a b is a presystolic movement. The carotid pulse 
coincides nearly with the apex of the cardiogram, *. e., almost simultaneously with the descending 
limb of the phlebogram (Riegel). 
Occasionally in healthy individuals a pulsatile movement, synchronous with 
the action of the heart, may be observed in the common jugular vein. It is either 
confined to the lower part of the vein, the so-called bulb, or extends farther up 
along the trunk of the vein. In the latter case, the valves above the bulb are 
insufficient, which is by no means rare, even in health. The wave-motion 
passes from below upwards, and is most obvious when the person is in the 
passive horizontal position, and it is more frequent on the right side, because 
the right vein lies nearer the heart than the left. It is propagated more slowly 
than the arterial pulse-wave. The venous pulse resembles very closely the 
tracing of the cardiac impulse. Compare fig. 131, 1, with fig. 47. 
It is obvious that, as the jugular vein is in direct communication with the 
right auricle, and as the pressure within it is low, the systole of the right auricle 
must cause a positive wave to be propagated towards the peripheral end of the 
jugular vein. Fig. 131,9 and 10, are venous pulse-tracings of a healthy person 
with insufficiency of the valves of the jugular vein. In these curves the part a b 
corresponds to the contraction of the auricle. Occasionally this part consists of 
two elevations, corresponding to the contraction of the atrium and auricle 
respectively. As the blood in the right auricle receives an impulse from the Sec. 99.] 
VENOUS PULSES. 
165 
sudden tension of the tricuspid valve, synchronous with the systole of the right 
ventricle, there is a positive wave in the jugular vein in fig. 131, 9 and 10, in- 
dicated by b, c. Lastly, the sudden closure of the pulmonary valves may even 
be indicated (<?). As the aorta lies in direct relation with the pulmonary 
artery, the sudden closure of its valves may also be indicated (fig. 131, 9, at d). 
During the diastole of the auricle and ventricle, blood flows into the heart, so 
that the vein partly collapses and the lever of the recording instrument 
descends. 
Sinus and Retinal Pulse.—The blood in the sinuses of the brain also undergoes a pulsatile 
movement, owing to the fact that during cardiac diastole much blood flows into the veins 
(Mosso). Under favorable circumstances, this movement may be propagated into the veins ot 
the retina, constituting the venous retinal pulse of the older observers (Helfreich). 
Pathological Jugular Vein Pulse.—The venous pulse in the jugular vein is far better 
marked in insufficiency of the tricuspid valve, and the vein may pulsate violently, but if its valves 
Fig. 131. 
Venous pulses (Friedreich). 1-8, from insufficiency ot the tricuspid; 9, 10, pulse of the jugular 
vein of a healthy person. In all the curves, a b = contraction of the right auricle ; be, ot 
the right ventricle; d, closure of the aortic valves; e, closure of the pulmonary valves; f, 
diastole of the right ventricle. 
be perfect, the pulse is not propagated along the vein, so that a pulse in the jugular vein is not 
necessarily a sign of insufficiency of the tricuspid valve, but only of insufficiency of the valve of 
the jugular vein {Friedreich). 
Liver Pulse.—The ventricular systole is propagated into the valveless inferior vena cava, and 
causes the liver pulse. With each systole blood passes into the hepatic veins, so that the liver 
undergoes a systolic swelling and injection. 
Fig. 131, 2-8, are curves of the pulse in the common jugular vein. Although at first sight 
the curves appear to be very different, they all agree in this, that the various events occurring 
in the heart during a cardiac revolution are indicated more or less completely. In all the 
curves, a b = auricular contraction. The auricle, when it contracts, excites a positive wave in 
the veins. The elevation, b c, is caused by the large blood-wave produced in the veins, owing 
to the emptying of the ventricle. It is always greater, of course, in insufficiency of the tricuspid 
valves than under normal circumstances (fig. 131,9 and 10). In the latter case, the closure of 
the tricuspid valve causes only a slight wave-motion in the auricle. The apex, c, of this wave 
may be higher or lower, according to the tension in the vein and the pressure exerted by the 
sphygmograph. As a general rule, at least one notch (4, 5, 6, e) follows the apex, due to the [Sec. gg. 
DISTRIBUTION OF THE BLOOD. 
prompt closure of the valves of the pulmonary artery. The closure of the closely adjacent 
aortic valves may cause a small secondary wave near to e (as in I and 2, d). The curve falls 
towards f, corresponding to the diastole of the heart. 
A well-marked venous pulse occurs when the right auricle is greatly congested, as in cases of 
insufficiency of the mitral valve or stenosis of the same orifice. In rare cases, in addition to 
the pulse in the common jugular vein, the external jugular, the facial, thyroid, external 
thoracic veins, or even the veins of the upper and lower extremities may pulsate. A similar 
pulsation must occur in the pulmonary veins in mitral insufficiency, but of course the result is 
not visible. 
On rare occasions a pulse occurs in the veins on the back of the hand and foot, owing to the 
arterial pulse being propagated through the capillaries into the veins. This may occur under 
normal circumstances, when the peripheral ends of the arteries become dilated and relaxed 
(Quincke), or when the blood-pressure within these vessels rises rapidly and falls as suddenly, 
as in insufficiency of the aortic valves. [Venous pulse in submaxillary vein (p. 138).] 
In progressive effusion into the pericardium, the carotid pulse at first becomes smaller and the 
venous pulse larger; beyond a certain stage of pressure the latter ceases i^Riegel). 
100. DISTRIBUTION OF THE BLOOD.—In the rabbit, one-fourth 
of the total amount of the blood is found in each of the following :—a, in the 
passive muscles; b, in the liver; c, in the organs of the circulation (heart and 
great vessels) ; d, in all other parts together. 
Methods.—The methods adopted do not give exact results. J. Ranke ligatured the parts 
during life, removed them, and investigated the amount of blood while the tissues are still warm. 
Influencing Conditions.—The amount of blood is influenced by—(1) the anatomical distri- 
bution of the vessels (vascularity or the reverse) as a whole; (2) the diameter of the vessels, 
which depends upon physiological causes— (a) on the blood pressure within the vessels; (b) on 
the condition of the vaso-motor or vaso-dilator nerves; (r) on the condition of the tissues in 
which the blood-vessels are distributed, e.g., the vessels of the intestine during absorption; the 
vessels of muscle during muscular contraction; and the vessels in inflamed parts. 
The most important factor, however, is the state of activity of the organ 
itself; hence the saying, “ubi irritatio, ibi affluxus.” We may instance the 
congestion of the salivary glands and the gastric mucous membrane during 
digestion, and the increased vascularity of muscles during contraction. As the 
activity of organs varies at different times, the amount of blood in the. part or 
organ goes hand in hand with the variations in its states of activity. When some 
organs are congested, others are at rest; during digestion there is muscular 
relaxation and less mental activity : violent muscular exertion retards digestion 
—during great congestion of the cutaneous vessels the activity of the kidneys 
diminishes. Many organs (heart, muscles of respiration, certain nerve centres) 
seem always to be in a nearly uniform state of activity and vascularity. Dur- 
ing the activity of an organ, the amount of blood in it may be increased 30 per 
cent., nay, even 47 per cent. The motor organs of young muscular persons 
are relatively more vascular than those of old and feeble persons (f. Ranke). 
In the condition of increased activity, a more rapid renewal of the blood seems 
to occur; after muscular exertion the duration of the circulation diminishes 
( Vierordt). 
During a condition of mental activity, the carotid is dilated, the dicrotic wave in the carotid 
curve is increased (the radial shows the opposite condition), and the pulse is increased in fre- 
quency (Gley). 
Age.—The development of the heart and large vessels determines a different distribution of the 
blood in the child from that which obtains in the adult. The heart is relatively small from 
infancy up to puberty, the vessels are relatively large; while after puberty the heart is large, 
and the vessels are relatively smaller. Hence it follows that the blood-pressure in the arteries 
of the systemic circulation must be lower in the child than in the adult. The pulmonary artery 
is relatively wide in the child, while the aorta is relatively small; after puberty both vessels 
have nearly the same size. Hence it follows that the blood-pressure in the pulmonary vessels of 
the child is relatively higher than that in the adult (Beneke). 
101. PLETHYSMOGRAPHY.—In order to estimate and register the 
amount of blood in a limb Mosso devised the plethysmograph (fig. 132). Sec. IOI.] 
PLETHYSMOGRAPHY. 
167 
It consists of a long cylindrical glass vessel, G, suited to accommodate a limb. The opening 
through which the limb is introduced is closed with caoutchouc, and the vessel is filled with 
water. There is an opening in the side of the vessel in which a manometer tube, filled to a 
certain height with water, is fixed. As the arm is enlarged owing to the increased supply of 
arterial blood passing into it at each pulse-beat, of course the water column in the manometer is 
raised. Fick placed a float upon the surface of the water, and thus enabled the variations in 
the volume of the fluid to be inscribed on a revolving cylinder. The curve obtained resembled 
the pulse-curve ; it was even dicrotic. In fig. 132 the movement of the fluid is represented as 
conveyed to a Marey’s tambour, T, similar to the recording apparatus employed in Brondgeest’s 
pansphygmograph (fig. 88). 
The cylinder C may be filled with air. Kries fills it with gas and connects the tube leading 
to T to a gas-burner. The variations in the gas-flame are then photographed. 
Results.—(1) Pulsatile Variations in the Volume.—As the venous 
current is regarded as uniform in the passive limb, every increase of the volume- 
curve indicates a greater velocity of the arterial current towards the periphery, 
and vice versa (Fick). The curves registered by the apparatus are volume 
pulses, and they resemble the curve of the dromograph (fig. 127, III). The 
ascent of the curve indicates a greater, the descent a diminished inflow of 
arterial blood. 
At first sight the plethysmograph curve (volume-pulse, § 90, 7) is very like the pulse curve 
(pressure pulse); both are dicrotic. But there are differences; the volume pulse-curve beyond 
Fig. 132. 
Mosso’s plethysmograph. G, glass vessel for holding a limb; F, flask for varying the water- 
pressure in G; T, recording apparatus. 
the apex falls more rapidly. The rapid fall, which is not accompanied by a corresponding fall 
of the pressure, is attributed by v. Kries to peripheral reflexion. The dicrotic wave occurs 
sooner in the volume-pulse than in the pulse-curve. 
(2) The respiratory undulations correspond to similar variations in the 
blood-pressure tracing (§ 85,/). Vigorous respiration and cessation of the 
respiration cause a diminution of the volume. The limb swells during straining 
and coughing, but diminishes during sighing. (3) Certain periodic undula- 
tions occur, due to the regular periodic contractions of the small arteries. 
(4) Other undulations, due to various accidental causes, affect the blood- 
pressure ; changes of the position of a limb acting hydrostatically, and dilata- 
tion or contraction of the vessels in other vascular regions. (5) Movement of 
the muscles of the limb under observation causes diminution of volume, as the 
venous current is accelerated, the musculature is also very slightly diminished 
in volume, even when the intra-muscular vessels are dilated. (6) Mental exer- 
cise causes a diminution in the volume of the limb, and so does sleep (Mosso). 
Music influences the blood-pressure in dogs, the pressure rising or falling under 
different conditions. The state of excitement of the auditory nerve is trans- 
mitted to the medulla oblongata, where it acts so as to cause acceleration of 
the action of the heart (Dogiel). (7) Compression of the afferent artery causes 
a decrease, and compression of the vein an increase in the volume of the limb 168 
[Sec. 101. 
TRANSFUSION OF BLOOD. 
(Mosso). (8) Stimulation of the vaso-motor nerves causes a decrease, that of 
the vaso-dilators an increase in the volume (Bowditch and Warren). 
102. TRANSFUSION OF BLOOD.—Transfusion is the introduction 
of blood from one animal into the vascular system of another animal. 
(a) The red corpuscles are the most important elements in connection 
with the restorative powers of the blood. They seem to preserve their functions 
even in blood which has been defibrinated outside the body (§ 4, A). 
(b) With regard to the gases present in the blood, arterial blood never acts 
injuriously; but venous blood overcharged with carbonic acid ought only to be 
transfused when the respiration is sufficient to oxygenate the blood as it passes 
through the pulmonary capillaries, whereby venous is transformed into arterial 
blood. If the respiratory movements have ceased, or are imperfectly performed, 
the blood becomes rapidly richer in carbonic acid, and in this condition reaches 
the heart; thence it is propelled into the blood-vessels of the medulla oblongata, 
where it acts as a powerful stimulus of the respiratory centre, causing dyspnoea, 
convulsions, and death. 
(V) The fibrin, and the substances from which it is formed, do not seem to 
play any part in connection with the restorative powers of the blood; hence, 
defibrinated blood performs all the functions of non-defibrinated blood within 
the body (Panum, Landois). 
(,d) The investigations of Worm Muller showed that an excess of 83 per 
cent, of blood may be transfused into the vascular system of an animal (dog) 
without producing any injurious effects. Hence it follows that the vascular 
system has the power of accommodating large quantities of blood within it. 
That the vascular system can accommodate itself to a diminished amount of 
blood has been known for a long time (§ 85, c). It is very important to observe 
that the transfusion of a large quantity of blood does not materially or perma- 
nently raise the blood-pressure. 
When Employed.—The transfusion of blood is used—(1) in acute 
anaemia (§ 41, 1), e. g., after copious hemorrhage. New blood (150 to 
500 c.c.), from the same species of animal, is introduced directly into the ves- 
sels, to supply the place of the blood lost by the hemorrhage. 
(2) In cases of poisoning, where the blood has been rendered useless by 
being mixed with a poisoning substance, and hence is unable to support life. 
In such cases remove a considerable quantity of the blood, and replace it by 
fresh blood. Carbonic oxide is a poison of this kind, and its effects on the 
body have already been described (§ 16). Asimilar practice is indicated in poi- 
soning with ether, chloral,chloroform, opium, morphia, strychnine, cobra poison, 
and such substances as dissolve the blood-corpuscles, e.g., potassic chlorate. 
(3) Under certain pathological conditions the blood may become so 
altered in quality as to be unable to support life. The morphological elements 
of the blood may be altered, and so may the relative proportion of its other 
constituents. Amongst these conditions may be cited the pathological condi- 
tion of uraemia, due, it may be, to the accumulation of urea or the products of 
its decomposition within the blood ; accumulation of the biliary constituents 
in the blood, and great increase of the carbonic acid. All these three condi- 
tions, when very pronounced, may cause death. In these cases, part of the 
impure blood may be replaced by normal human blood. 
Amongst conditions where the morphological constituents of the blood 
are altered qualitatively or quantitatively are: hydrsemia (excessive amount of 
water in the blood, §41, 1); oligocythsemia (abnormal diminution of red 
blood-corpuscles). When these conditions are highly developed, more especially 
in pernicious anaemia (§ 10, 2), healthy blood may be substituted. Transfusion 
is not suited for persons suffering from leukaemia (compare p. 21). Sec. 102.] 
EFFECTS OF TRANSFUSION OF BLOOD. 
169 
After Effects.—A quarter or half an hour after normal blood has been 
injected into the blood-vessels of a man, there is a greater or less febrile reaction, 
according to the amount of blood transfused (Fever, § 220). 
Operation.—The operative procedure to be adopted in the process of transfusion varies ac" 
cording as defibrinated or non-defibrinated blood is used. In order to defibrinate blood, some 
blood is withdrawn from a vein of a healthy man in the ordinary way, collected in an open ves- 
sel, and whipped or beaten with a glass rod until all the fibrin is completely removed from it. It 
is then filtered through an atlas filter, heated to the temperatnre of the body (by placing it in a 
vessel in warm water), and injected by means of a syringe into an artery opened for the purpose. 
A vein (e.g., basilic or great saphenous) may be selected for the transfusion, in which case the 
blood is driven inward in the direction of the heart; if an artery is selected (radial or posterior 
tibial) the blood is injected towards the periphery, or towards the heart. 
If non-defibrinated human blood is used, the blood may be passed directly from the arm of 
the giver to the arm of the receiver by means of a flexible tube. The tube used must be filled 
with normal saline solution to prevent the entrance of air. [J. Duncan collects the blood shed 
during an operation in a 5 per cent, solution of sodic phosphate (Pavy), and injects the mixture, 
especially where much blood has been lost previously.] 
Dangers.—It is most important that no air be allowed to pass into the circulation, for if it 
be introduced in sufficient quantity it may cause death. When air enters the circulation it reaches 
the right side of the heart, where, owing to the movement of the blood, it forms air-bubbles and 
makes a froth. The air-bubbles are pumped into the branches of the pulmonary artery, in 
which they become impacted, arrest the pulmonary circulation, and rapidly cause death. 
Peritoneal Transfusion.—Recently, the injection of defibrinated blood into the peritoneal 
cavity has been recommended. The blood so injected is absorbed (Ponfick). Even after twenty 
minutes the number of blood-corpuscles in the blood of the recipient (rabbit) is increased, and 
tha number is greatest on the first or second day. The operation, however, may cause death, 
and one fatal case, owing to peritonitis, is recorded (Mosler). It is evident that this method of 
transfusion is not applicable in cases where blood must be introduced into the circulation as rap- 
idly as possible (e.g, after severe hemorrhage or in certain cases of poisoning. [Blood has been 
injected into the subcutaneous cellular tissue of the abdomen in cases of great debility.] 
Heterogeneous Blood.— The blood of animals ought never to be transferred into the blood- 
vessels of man. It is to be remembered, however, that the blood-corpuscles of the sheep are 
rapidly dissolved by human blood, so that the active constituents of the blood are rendered use- 
less (Landois). As a general rule, the blood-serum of some mammals dissolves the blood-cor- 
puscles of other mammals (§ 5, 5). 
Solution of the Blood-Corpuscles.—The serum of dog’s blood is a powerful solvent, while 
that of the blood of the horse and rabbit dissolves corpuscles relatively slowly. The blood-cor- 
puscles of mammals vary very greatly with reference to their power to resist the solvent action of 
the serum of other animals. The red blood-corpuscles of rabbits’ blood are rapidly dissolved by 
the blood-serum of other animals,whilst those of the cat and dog resist the solvent action much 
longer. Solution of the corpuscles occurs in defibrinated as well as in ordinary blood. When the 
blood of a rabbit or lamb is injected into the blood-vessels of a dog, the red blood-corpuscles are 
dissolved in a few minutes. If blood be withdrawn by pricking the skin with a needle, the 
partially dissolved corpuscles may be detected. 
Liberation of Haemoglobin and Haemoglobinuria.—As a result of the solution of the 
colored corpuscles, the blood-plasma is reddened by the liberated haemoglobin. Part of the dis- 
solved material may be used up in the body of the recipient, some of it for the formation of bile, 
but if the solution of the corpuscles has been extensive, the haemoglobin is excreted in the urine 
(haemoglobinuria), in less amount in the intestine, the bronchi, and the serous cavities. Bloody 
urine has been observed in man after the injection of 100 grams of lamb’s blood. Even some of 
the recipient’s blood corpuscles are dissolved by the serum of the transfused blood, e.g., on trans- 
fusing dog’s blood into man. In the rabbit, whose corpuscles are readily dissolved, the transfu- 
sion of the blood-sertim of the dog, man, pig, sheep, or cat produces serious symptoms, and even 
death. The dog, whose corpuscles are more resistant, bears transfusion of other kinds of blood 
well. 
Dangers.—When foreign or heterogeneous blood (i.e., blood from a different species) is trans- 
fused, two phenomena, which may be dangerous to life, occur:— 
(1) Before the corpuscles are dissolved, they usually run together and form sticky masses, 
consisting of 10 or 12 corpuscles, which are apt to occlude the capillaries. After a time they 
give up their haemoglobin, leaving the stroma, which yields a sticky fibrin-like mass that may 
occlude fine vessels ($31). 
(2) The presence of a large quantity of dissolved haemoglobin may cause extensive coagulation 
within the blood-vessels. The injection of dissolved haemoglobin causes extensive coagulations 
'Naunyn and Francken). 170 
STRUCTURE OF THE SPLEEN. 
[Sec. 102. 
The coagulation occurs usually in the venous system and in the larger vessels, and may cause 
death either suddenly or after a considerable time. 
Dissolved haemoglobin seems greatly to increase the activity of the fibrin-ferment (§ 30), per- 
haps by accelerating the disintegration of the colorless corpuscles. Haemoglobin exposed to the 
air gradually loses this property; and the fibrin-ferment, when in contact with haemoglobin, is 
either destroyed or rendered less active (Sachssendahl). 
Vascular Symptoms.—As a result of the above-named causes of occlusion of the vessels, 
there are often signs of the circulation being impeded in various organs. In man, after transfu- 
sion of lamb’s blood, the skin is bluish-red, in consequence of the stagnation of blood in the cuta- 
neous vessels. Difficulty of breathing occurs from obstruction in the capillaries of the lung; 
while there may be rupture of small bronchial vessels, causing sanguineous expectoration. The 
dyspnoea may increase, especially when the circulation through the medulla oblongata—the seat 
of the respiratory centre—is interfered with. In the digestive tract, for the same reason, increased 
peristalsis, evacuation of the contents of the rectum, vomiting, and abdominal pain may occur. 
These phenomena are explained by the fact that disturbances of the circulation in the intestinnl 
vessels cause increased peristaltic movements. Degeneration of the parenchyma of the kidney 
occurs as a result of the occlusion of some of the renal vessels. The uriniferous tubules become 
plugged with cylinders of coagulated albumin (Ponjick). Owing to the occlusion of numerous 
small muscular branches, the muscles may become stiff, or coagulation of their myosin may occur. 
Other symptoms, referable to the nervous system, sense-organs, and heart, are all due to the in- 
terference with the circulation through them. An important symptom is the occurrence of a 
considerable amount of fever half an hour or so after the transfusion of heterogeneous blood (§ 
200). When many vessels are occluded, rupture of some small blood-vessels may take place. 
This explains the occurrence of slight, yet persistent hemorrhages, which occur on the free sur- 
faces of the mucous and serous membranes, and in the parenchyma of organs, as well as in 
wounds. The blood coagulates with difficulty, and imperfectly. 
Transfusion of other Fluids.—Other substances have been transfused. Normal saline 
solution (0.6 per cent. NaCl), or serum from the same species, aids the circulation in a purely 
mechanical way (Goltz), and it even excites the circulation (Kronecker). In severe anaemia 
this fluid cannot maintain life (Eulenburg and ’Landois). The injection of peptone, or rather 
the albumoses, even in moderate amount, is dangerous to life, as it causes paralysis of the 
vessels (p. 37). 
The Blood Glands. 
103.—I.—THE SPLEEN.—Structure.—The spleen is covered by the 
peritoneum, except at the hilum. Under 
this serous covering there is a tough, 
thick, elastic, fibrous capsule, which 
closely invests the organ and gives a 
covering to the vessels which enter or 
leave it at the hilum, so that fibrous tis- 
sue is carried into the organ along the 
course of the vessels (fig. 133). [The cap- 
sule cannot be separated without tearing 
the splenic pulp.] Numerous trabeculae 
pass into the spleen from the deep surface 
of the capsule, where they branch and 
anastomose so as to produce a network of 
sustentacular tissue, which is continuous 
with the connective-tissue, prolonged in- 
wards and surrounding the blood-vessels 
(fig. 134). Thus, the connective-tissue in 
the spleen, as in other viscera, is continu- 
ous throughout the organ. In this way an 
irregular dense network is formed, com- 
parable to the meshes of a bath sponge. 
[This network is easily demonstrated by 
washing out the pulp lying in its meshes by 
A, capsule; B, trabeculae; C, splenic pulp ; 
D, splenic corpuscle; E, artery. 
Fig- 133- 
Section of human spleen X io times. Sec. 103.] 
STRUCTURE OF THE SPLEEN. 
171 
means of a stream of water, when a beautiful soft semi-elastic network or 
framework of rounded and flattened threads is obtained.] The capsule 
(fig. 133) is composed of interlacing bundles of connective-tissue mixed with 
numerous fine fibres of elastic tissue and some non-striped fibres. 
Reticulum.—Within the meshes of the trabecular framework there is dis- 
posed a very delicate network or reticulum of adenoid tissue, which, with the 
other colored elements that fill up the meshes, constitute the splenic pulp (fig. 
135). The reticulum is continuous with the fibres of the trabeculse. [If a fine 
section of the spleen be “ pencilled ” in water, so as to remove the cellular ele- 
ments, the preparation presents much the same characters as a section of a 
lymph-gland similarly treated, viz., a very fine network of adenoid tissue, con- 
tinuous with, and surrounding the walls of, the blood-vessels. The spaces of this 
tissue are filled with lymph- and blood-corpuscles.] 
The pulp is a dark reddish-colored, semi-fluid material, which may be 
squeezed or washed out of the meshes in which it lies. It contains a large 
number of colored blood-corpuscles, and becomes brighter when it is exposed 
to the action of the oxygen of the air. 
Blood-Vessels and Malpighian Corpuscles.—The large splenic artery, 
accompanied by a vein, splits up into several branches before it enters the 
spleen. Both vessels and their branches are enclosed in a fibrous sheath, which 
becomes continuous with the trabeculae. The smaller branches of the artery 
gradually lose this fibrous investment, and each one ultimately divides into a 
group or pencil of arterioles or penicilli which do not anastomose with each 
other. [Thus each branch is terminal—a condition which is of great impor- 
tance in connection with the pathology of embolism or infarction of the vessels 
of the spleen.] At the points of division of the branches of the artery, or 
scattered along their course, are small oval or globular masses of the adenoid 
tissue to -jV inch in diameter), the Malpighian corpuscles. [These 
bodies are visible to the 
naked eye as small, round, 
or oval white structures, 
about the size of millet 
Trabeculae of the spleen of a cat with the splenic pulp washed 
out. a, trabecula; b, vein. 
Fig- 134- 
Adenoid reticulum of 
spleen of cat. 
Fig. 135- 
seed, in a section of a fresh spleen. They are very numerous—[70,000 in 
man]—and are readily detected in the dark reddish pulp. One must be careful 
not to mistake sections of the trabeculae for them. These corpuscles consist of 
adenoid tissue, whose meshes are filled with lymph-corpuscles, and they present 
exactly the same structure as the solitary follicles of the intestine (§ 197). 
They are small lymphatic accumulations around the arteries—peri-arterial 
masses of adenoid tissue similar to those masses that occur in a slightly 
different form in other organs, e. g., the lungs. In a section of the spleen the 
artery may pass through the centre of the mass or through one side of it, and 
in some cases the tissue is collected unequally on opposite sides of the vessel, FUNCTIONS OF THE SPLEEN. 
[Sec. 103. 
so that it is lob-sided. They are not surrounded by any special envelope. In 
some animals the lymphatic tissue is continued for some distance along the small 
arteries, so that to some extent it resembles a peri-vascular sheath of adenoid 
tissue. In a well-injected spleen, a few fine capillaries are to be found within 
these corpuscles. The capillaries distributed in the substance of the Malpighian 
corpuscle (fig. 136) form a network, and ultimately pour their blood into the 
spaces in the pulp. According to Cadiat, the corpuscles are separated from the 
splenic pulp by a lymphatic sinus, which is traversed by efferent capillaries 
passing to the pulp (fig. 136). 
Connection of Arteries and Veins.—It is very difficult to determine 
what is the exact mode of termination of the arteries within the spleen, more 
especially as it is extremely difficult to inject the blood-vessels of the spleen. 
According to Stieda and others, the fine “ capillary arteries ” formed by the 
division of the small arteries do not open directly into the capillary veins, but 
the connection between the arteries and veins is by means of the “ interme- 
diary intercellular spaces” of the reticulum of the spleen, so that, accord- 
Fig- 137- 
Elements of human splenic 
pulp. I, colorless cells; 
2, endothelium; 3, col- 
ored blood-corpuscles; 
4, cells containing gran- 
ules, the upper one with 
a colorless blood-cor- 
puscle b, enclosed in it 
Fig. 136. 
Malpighian corpuscle of a cat’s spleen injected. 
a, artery; b, meshes of the pulp injected; c, 
the artery of the corpuscle ramifying in the 
lymphatic tissue composing it. 
ing to this view, there is no continuous channel lined throughout by epithelium 
connecting these vessels one with another. Thus the blood of the spleen flows 
into the spaces of the adenoid reticulum just as the lymph-stream flows through 
the spaces in a lymph-gland. According to Billroth and Kdlliker, a closed 
blood-channel actually does exist between the capillary arteries and the veins, 
consisting of dilated spaces (similar to those of erectile tissue). These inter- 
mediary spaces are said to be completely lined by spindle-shaped epithelium, 
which abuts externally on the reticulum of the pulp. [According to Frey, 
owing to the walls of the terminal vessels being incomplete, there being clefts 
or spaces between the cells composing them, the blood passes freely into spaces 
of the adenoid tissue of the pulp “in the same way as the water of a river 
finds its way among the pebbles of its bed,” these “ intermediary pas- 
sages ” being bounded directly by the cells and fibres of the network of the 
pulp. From the passages the venous radicles arise. At first their walls are 
imperfect and cribriform, and they often present peculiar transverse markings, 
due to the circular disposition of the elastic fibres of the reticulum. The small Sec. 103.] 
FUNCTIONS OF THE SPLEEN. 
veins have at first a different course from the arteries. They anastomose 
freely, but they soon become ensheathed, and accompany the arteries in their 
course.] 
Elements of the Pulp (fig. 137).—The morphological elements are very 
various—(1) Lymph-corpuscles of various sizes, sometimes partly swollen, and 
at other times with granular contents. (2) Red blood-corpuscles. (3) Tran- 
sition forms between 1 and 2 [although this is denied by some observers (§ 7, 
C)]. (4) Cells containing red blood-corpuscles and pigment granules. [These 
cells exhibit amoeboid movements.] (Compare § 8.) 
[Lymphatics undoubtedly arise within the spleen, but they are not numer- 
ous. There are two systems—a superficial or capsular, and trabecular system ; 
and a peri-vascular set. The superficial lymphatics in the capsule are rather 
more numerous. Some of them seem to communicate with the lymphatics within 
the organ (Tomsa Kolliker). In the horse’s spleen they communicate with the 
lymphatics in the trabeculse, and with the peri-vascular lymphatics. The exact 
mode of origin of the peri-vascular system is unknown, but in part at least 
it begins in the spaces of the adenoid tissue of the Malpighian corpuscles and 
peri-vascular adenoid tissue, and runs along the arteries towards the hilum. 
There seem to be no afferent lymphatics in the spleen such as exist in a lym- 
phatic gland.] 
The nerves of the spleen are composed for the most part of non-medul- 
lated nerve-fibres, and run along with the artery. Their exact mode of termi- 
nation is unknown, but they probably go to the blood-vessels and to the mus- 
cular tissue in the capsule and trabeculae. [They are well seen in the spleen 
of the ox, and in their course very small ganglia, placed wide apart, have been 
found by Remak and W. Stirling.] 
Chemical Composition.—Several of the more highly oxidized stages of albuminous bodies 
exist in the spleen. Besides the ordinary constituents of the blood, there exist:—leucin, 
tryosin, xanthin, hypoxanthin; lactic, butyric, acetic, formic, succinic, and uric acids, and 
perhaps glycero-phosphoric acid (Salkowski); cholesterin, a glutin-like body, inosit, a pigment 
containing iron, and even free iron oxide The ash is rich in phosphoric acid and iron 
(p.174); poor in chlorine compounds. The splenic juice is alkaline in reaction; the specific 
gravity of the spleen = 1059-1066. 
The functions of the spleen are obscure, but we know some facts on 
which to form a theory. [The spleen differs from other organs in that no very 
apparent effect is produced by it, so that we must determine its uses in the 
economy from a consideration of such facts as the following : (1) The effects 
of its removal or extirpation. (2) The changes which the blood undergoes as 
it passes through it. (3) Its chemical composition. (4) The results of experi- 
ments upon it. (5) The effects of diseases.] 
(1) Extirpation.—The spleen may be removed from an animal—old or 
young—without the organism suffering any very obvious change (Galen). 
The human spleen has been successfully removed by Koberle, Pean, and 
others. As a result (compensatory?) the lymphatic glands enlarge, but not 
constantly, while the blood-forming activity of the red marrow of bone is 
increased. Small brownish-red patches were observed in the intestines of frogs 
after extirpation of the spleen. These new formations are regarded by some 
observers as compensatory organs. Tizzoni asserts that new splenic structures 
are formed in the omentum (horse, dog) after the destruction of the parenchyma 
and blood-vessels of the spleen. The spleen is absent extremely seldom. 
[The weight of the animal (dog) diminishes after the operation, but afterwards increases. 
The number of red blood-corpuscles is lessened, reaching its minimum about the 150th to the 
200th day, while the colorless corpuscles are increased in number. The lymphatic glands 
(especially the internal, and those in the neck, mesentery, and groin) enlarge, while on section 
the cortical substance of these structures is redder, owing to the great number of red corpuscles 174 
FUNCTIONS OF THE SPLEEN. 
[Sec. 103. 
many of them are nucleated in the lymph spaces (Gibson). The marrow of all the long boues 
(those of the foot excepted), becomes very red and soft, with the characters of embryonic bone- 
marrow. Such animals withstand hemorrhage (to of the total amount of blood) without any 
special bad results ( Tizzoni, Winogradow). Schindeler observed that animals after extirpation 
of the spleen became very ravenous.] 
[Regeneration.—After entire removal of the spleen, nodules of splenic tissue are repro- 
duced (fox) ; while new adenoid tissue is formed in the lymphatic glands, and in Peyer’s 
patches, the parenchyma of the former coming to resemble splenic tissue (Tizzoni Eternod).~\ 
(2) According to Gerlach and Funke the spleen is a blood-forming gland. 
The blood of the splenic vein contains far more colorless corpuscles than the 
blood of the splenic artery (p. 54). Many of these corpuscles undergo fatty 
degeneration, and disappear in the blood-stream. That colorless blood-cor- 
puscles are found within the spleen seems to be proved by the enormous num- 
ber of these corpuscles which are found in the blood in cases of leukaemia 
{Bennett (1852), Virchow). Bizzozero and Salvioli found that, several days 
after severe hemorrhage, the spleen became enlarged, and its parenchyma con- 
tained numerous red nucleated haematoblasts. 
(3) Other observers {Kolliker and Ecker) regard the spleen as an organ 
in which colored blood-corpuscles are destroyed, and they consider 
the large protoplasmic cells containing pigment granules as a proof of this 
(p. 172). According to the observations of Kusnetzow, these structures are 
merely lymph-corpuscles, which, in virtue of their amoeboid movements, have 
entangled colored blood-corpuscles. [Such corpuscles exhibit similar proper- 
ties when placed upon a warm stage.] Similar cells occur in extravasations of 
blood. The colored blood-corpuscles within the lymph-cells gradually become 
disintegrated, and give rise to the production of granules of haematin and other 
derivatives of haemoglobin. [The spleen contains so much free iron that a 
section of this organ, especially from a young animal, when treated with Tiz- 
zoni’s fluid, i. e., with potassic ferrocyanide and hydrochloric acid, gives a 
distinct blue color (§ 174, 4).] Hence the spleen contains more iron than 
corresponds to the amount of blood present in it. When we consider that the 
spleen contains a large number of extractives derived from the decomposition 
of proteids, it is very probable that colored blood-corpuscles are destroyed in 
the spleen. Further, the juice of the spleen contains salts similar to those that 
occur in the red blood-corpuscles. 
The blood from the spleen is said to have undergone other changes, but the following state- 
ment must be accepted with caution: The blood of the splenic vein contains more water and 
fibrin, its red blood-corpuscles are smaller, brighter, less flattened, more resistant, and do not 
form rouleaux; its haemoglobin crystallizes more easily, and there is a large proportion of O 
during digestion. [The serum of the blood of the splenic vein does not differ from that of the 
blood of the body generally.] 
[The spleen has therefore very direct relations to the blood ; in it colored 
blood-corpuscles undergo disintegration, it produces colorless corpuscles, and it 
is said to transform white corpuscles into red. The last statement, however, 
does not agree with the view that the red and white corpuscles are each developed 
from special corpuscles, and that, in fact, they are developed independently of 
each other (p. 13).] 
(4) Contraction.—In virtue of the plain muscular fibres in its capsule and 
trabeculae, the spleen undergoes variations in its volume. Stimulation of the 
spleen or its nerves, by cold, electricity, quinine, eucalyptus, ergot of rye, and 
other “splenic reagents” causes it to contract, whereby it becomes paler, 
and its surface may even appear granular. After a meal, the spleen increases 
in size, and it is usually largest about five hours after digestion has begun, i. e., 
at a time when the digestive organs have almost finished their work and have 
again become less vascular. After a time it regains its original volume. For Sec. 103.] 
THE SPLENIC ONCOGRAPH. 
175 
this reason the spleen was formerly regarded as an apparatus for regulating 
the amount of blood in the digestive organs. [The congestion of the spleen after 
a meal is more probably related to the formation of new colorless corpuscles 
than to the destruction of red corpuscles. It may be, however, that some of 
the products of digestion are par- 
tially acted upon in the spleen, 
and undergo further change in the 
liver. ] There is a relation between 
the size of the spleen and that of 
the liver, for it is found that when 
the spleen contracts—e.g., by 
stimulation of its nerves—the liver 
becomes enlarged, as if it were 
injected with more blood than 
usual (.Drosdow). 
[Oncograph.—Botkin, and 
more recently Roy, have studied 
various conditions which affect the 
size of the spleen. Roy enclosed 
the spleen of a dog in a box with 
rigid walls (figs. 138, 139) the 
oncometer (oyzoc, volume) and 
filled with oil after the manner of 
the plethysmograph (§§ 101, 276). 
Any variations in the size of the 
organ caused a variation in the 
amount of oil within the box, and these variations were recorded by means of 
the oncograph (§ 276). The blood-pressure was recorded at the same time. 
The circulation through the spleen is peculiar, and is not due to the blood- 
pressure within the arteries, but is carried on chiefly by a rhythmical con- 
traction of the muscular fibres of 
the capsule and trabeculae. The 
spleen undergoes very regular 
rhythmical contractions (systole) 
and dilatations (diastole). This 
alternation of systole and diastole 
may last for hours, and the two 
events together occupy about one 
minute (fig. 140). Changes in the 
arterial blood-pressure have com- 
paratively little influence on the 
volume of the spleen. The rhyth- 
mical contractions,although modi- 
fied, still go on after section of 
the splenic nerves. This would 
seem to indicate that the spleen 
has an independent (nervous) 
mechanism within itself, causing 
its movements.] 
[Influence of Nerves.—Sec- 
tion of the splenic nerves is fol- 
lowed by an increase in the size of the spleen. The nerves have their centre in the 
medulla oblongata. Stimulation of the medulla oblongata, either directly or by 
means of asphyxiated blood, causes contraction of the spleen, hence the spleen is 
Roy’s Oncometer for the spleen. T, T, tubes to 
be connected to the oncograph. 
Fig. 138. 
Fig. 138 shown open. 
Fig. 139- 176 
INFLUENCE OF NERVES ON THE SPLEEN. 
[Sec. 103. 
“small and contracted ” in death from asphyxia. The fibres proceed down 
the cord, and leaving it in the dorsal region, enter the left splanchnic, pass 
through the semi-lunar ganglion, and thus reach the splenic plexus. Stimula- 
tion of the peripheral ends of these nerves causes contraction of the spleen, 
and so does cold applied to the spleen directly or over the region of the organ. 
In the last case the result is brought about reflexly. Botkin found that the 
application of the induced current to the skin over the spleen, in a case of 
leukaemia, caused well-marked contraction of the spleen in all its dimensions, 
and the result lasted some time. After every stimulation the number of color- 
less corpuscles in the blood increased, and the condition of the patient 
improved.] 
[There is a popular notion that the spleen is influenced by the condition of 
the nervous system. Botkin found that depressing emotions increased its size, 
while exhilarating ideas diminished it. The causes of these changes are refera- 
ble not only to changes in the amount of blood in the spleen, but also to the 
Tracing of a splenic curve, reduced one-half, taken with the oncograph. The upper line with 
large waves is the splenic curve ; each ascent corresponds to an increase, and each descent 
to a diminution in the volume of the spleen. The curve beneath is a blood-pressure 
tracing from the carotid artery. The lowest line indicates the time, the interruptions 
of the marker occupying every two seconds. The vertical lines a, and b, give the relative 
positions of the lever-point of the oncograph, and of the point of the recording style of 
the kymograph respectively (Roy). 
Fig. 140. 
greater or less degree of contraction of its muscular tissue. And it would 
appear that, like the small arteries, the muscular tissue of the spleen is in a 
state of tonic contraction. The size of the spleen may be influenced 
reflexly. Thus, Tarchanoff found that stimulation of the central end of the 
vagus, when the splanchnics were intact, caused contraction of the spleen, 
while stimulation of the central end of the sciatic also caused contraction, but 
to a less degree. It is quite certain that all the phenomena are not due to the 
action of vaso-motor nerves on the splenic blood-vessels. There is a certain 
amount of independent action of the muscular fibres of the organ, and it is 
not improbable that the innervation of the spleen is similar to the innervation 
of arteries, and that it has a motor centre in the cord capable of being in- 
fluenced reflexly by afferent nerves, while it also sends out efferent impulses.] 
[Stimulation of (T) the central end of a sensory nerve; (2) of the peripheral 
ends of both splanchnics; (3) of the peripheral ends of both vagi, causes con- Sec. 103.] 
STRUCTURE OF THE THYMUS GLAND. 
177 
traction of the spleen. But even after section of the splanchnics and vagi, 
stimulation of a sensory nerve still causes contraction, so that there must be 
some other channel as yet unknown {-Roy). Bochefontaine found that electrical 
stimulation of certain parts of the cortex cerebri produced contraction of the 
spleen.] Sensory nerves seem to occur only in the peritoneum covering the 
spleen. 
Pressure on the splenic vein causes enlargement of the spleen, hence increased pressure in 
this vein (congestion of the portal vein, cessation of hemorrhoidal and menstrual discharges) 
also causes its enlargement. With regard to the action of “ splenic reagents,” such as qui- 
nine, on the contraction of the spleen, Binz is of opinion that this drug retards the formation 
of the colorless blood-corpuscles, so that its chief function is interfered with, and the organ be- 
comes less vascular. It is not definitely decided, however, whether it is contraction or dilata- 
tion of the spleen that alters the proportion of red and white corpuscles in the blood. 
Splenic Tumors.—The increase in size of the spleen in various diseases early attracted the 
attention of physicians. The healthy spleen undergoes several variations in volume during 
the course of a day, corresponding with the varying activity of the digestive organs. In this 
respect the spleen resembles the arteries. In many fevers the spleen becomes greatly enlarged, 
probably due to paralysis of its nerves. It is greatly increased in intermittent fever or ague, 
and often during the course of typhus. When it becomes abnormally enlarged, and remains so 
after repeated attacks of ague, it is greatly hypertrophied, and constitutes “ ague cake.” In 
cases of splenic leukaemia it is greatly enlarged, and at the same time there is a great increase in 
the number of colorless corpuscles in the blood and also a decrease of the colored ones. (§ io). 
II. The Thymus.—During foetal life this gland is largely developed, and 
it increases during the first two or three years of life, remaining stationary 
until the tenth or fourteenth year, when it begins to atrophy and undergo fatty 
degeneration. [The degeneration begins at the outer part of each lobule and 
progresses inwards {His). Waldeyer finds that even in the oldest person the 
thymus is always represented by a mass of fat, at least as large as the thymus 
at birth, and always containing some adenoid tissue either in a diffuse or 
nodular form.] 
Structure.—“It consists of an aggregation of lymph-follicles (resembling the 
glands of Peyer) or masses of adenoid tissue held together by a framework of 
connective-tissue which contains blood-vessels, 
lymphatics, and a few nerves (fig. 141). The 
framework of connective-tissue gives off 
septa which divide the gland into lobes, these 
being further subdivided by finer septa into 
lobules, the lobules being separated by fine 
intra-lobular lamellae of connective-tissue into 
follicles (0.5-1.5 mm.). These follicles 
make up the gland-substance, and they are 
usually polygonal when seen in a section. Each 
follicle consists of a cortical and a medullary 
part, and the matrix or framework of both con- 
sists of a fine adenoid reticulum whose meshes 
are filled with lymph-corpuscles ” (fig. 142, 
a). ■ Many of these corpuscles exhibit various 
stages of disintegration. In the medulla are 
found the concentric corpuscles of Has- 
sall. [“ They consist of a central granular 
part, around which are disposed layers of 
flattened nucleated endothelial cells arranged 
concentrically. When seen in a section they 
resemble the ‘cell-nests’ of epithelioma (fig. 142, b), They have also been 
compared to similar bodies which occur in the prostate. They are most 
Section of the thymus gland of a cat, 
with one complete lobule with a cor- 
tical part, a, and a centre, b. a, 
lymphoid tissue ; c, blood-vessels in- 
jected; d, connective-tissue. 
Fig. 141. 178 
STRUCTURE OF THE THYROID GLAND. 
[Sec. 103. 
numerous when the gland undergoes its retrograde metamorphosis.” Sig. 
Mayer finds that the thymus of the frog contains 
structures, with transverse markings, identical with 
the stripes of striped muscular fibres. The structures 
are identical with those called “ sarcoplasts ” by 
Margo and Paneth, and “ sarcolytes ” by Sig. 
Mayer. They also occur in large numbers in the 
tail of the larvae of batrachians, when the tail is under- 
going a retrograde metamorphosis.] 
Simon, His, and others described a convoluted 
blind canal, the “central canal,” as occurring 
within the gland, and on it the follicles were said to 
be placed. Other observers, Jendrassik and Klein, 
either deny its existence or regard it merely as a 
lymphatic or an artificial product. Numerous fine 
lymphatics penetrate into the interior of the organ, 
and many are distributed over its surface, but their 
mode of origin is unknown. [They seem to be channels through which the 
lymph-corpuscles are conveyed away from the gland.] Numerous blood- 
vessels are also distributed to the septa and follicles (fig. 141, c). 
Chemical Composition.—Besides gelatin, albumin, soda-albumin, there are sugar and fat, 
leucin, xanthin, hypoxanthin, formic, acetic, butyric, and succinic acids. Potash and phosphoric 
acid are more abundant in the ash than soda, calcium, magnesium (? ammonium), chlorine, and 
sulphuric acid. 
Function of the Thymus.—As long as it exists, it seems to perform the functions of a true 
lymph-gland. This view is supported by the fact that in reptiles and amphibians, which do not 
possess lymph-glands, the thymus remains as a permanently active organ. [Extirpation gave 
few positive results, but chemical investigation shows that the parenchyma contains a large 
number of products indicating considerable metabolic activity (Friedleben).~\ 
[Development of the Thymus.—The thymus is the organ which earliest shows the struc- 
ture of adenoid tissue, both in the ontogeny of individual mammals and in the phylogeny of the 
vertebrates. In man His mantains that it is derived from the epithelium covering the fourth, 
third, and part of the second branchial cleft, which becomes compressed in the angle between 
the head and neck. (More recent observers—Kastochenko and others—have thrown some doubt 
on the correctness of His’s observations ; probably there are considerable differences in different 
classes of vertebrates, but all are now agreed that the original thymus is an epithelial organ 
mainly derived from the epithelium covering the gill-clefts.) The tube of epithelium—sinus 
praecervicalis—so formed grows inwards, branching dichotomously, and ramifying in the con- 
nective-tissue behind the sternum, just above the pericardium. The cells forming it grow 
inwards and fill up the lumen of the “ gland ” and at last of the duct also. By this epithelial 
ingrowth the same condensation of connective-tissue is brought about as in the tonsil, and in the 
same way blood-vessels appear in large numbers, and leucocytes begin to wander out of the 
vessels, are detained in the meshes of the connective-tissue, and invade the nearly functionless epithe- 
lial gland lobules. The cells of the latter proliferate, and the older cells of the lobule are pushed 
to the centre, become cornified, and present very much the appearance of the cell-nests of an 
epithelioma, forming the so called “ concentric corpuscles of Hassall.” While the leucocytes 
soon eat away the majority of the epithelial cells, and break the continuity of the epithelial tubes, 
these cornified structures long resist their attacks, and the thymus always retains the lobular 
character imparted to it by its epithelial precursor. The leucocytes divide rapidly by mitosis in 
the connective-tissue surrounding these epithelial remains, though no true “ germ-centres ” are 
ever formed. The complete removal of the “ concentric corpuscles ” by the leucocytes leads to 
the disappearance of the latter, and the appearance of fat in the position of the thymus; but 
Waldeyer has recently shown that the outward form of the thymus is always preserved in this 
fatty mass, and that it is always possible to demonstrate microscopically in some part of it a 
remaining leucocyte infiltration, and whenever this is at all well marked it will be found to 
surround a surviving “ concentric corpuscle ” (G. L. Gulland),\ 
III. The Thyroid.—Structure.—The gland consists of lobes and 
lobules held together by connective-tissue rich in cells. Each lobule is made 
up of numerous completely closed sacs (0.04 to 0.1 mm. in diameter), 
which in the embryo and the newly-born animal are composed of a membrana 
Elements of the thymus 
(x 300). a, lymph-corpus- 
cles ; b, concentric corpus- 
cles of Hassall. 
Fig. 142. Sec. 103.] 
EXCISION OF THE THYROID GLAND. 
179 
propria lined by a single layer of nucleated cubical cells (fig. 143). The sacs 
contain a transparent, viscid, albuminous fluid. [Not unfrequently the sacs 
contain many colored blood-corpuscles (Baber).~\ Each sac is surrounded by 
a plexus of capillaries which do not penetrate the membrana propria. There 
are also numerous lymphatics. At an early period the sacs dilate, their cellular 
lining atrophies, and their contents undergo colloid degeneration. When the 
gland-vesicles are greatly enlarged, “ goitre ” is produced. 
The chemical composition of this gland has not been much investigated. In addition to 
the ordinary constituents, leucin, xanthin, sarkin, lactic, succinic, and volatile fatty acids have 
been found. 
[Excision.—The effects differ according to the animal operated on. This gland has been 
excised in the human subject in cases of goitre. Reverdin pointed out that a peculiar condition 
results, called cachexia stumipriva, and practically the human being becomes a cretin. This 
operation therefore is highly questionable when performed on man. Rabbits endure the 
operation well, and so do the sheep, calf, and horse, none of the remarkable symptoms that 
occur in the dog and monkey being manifested by them. In pigeons no obvious disturbance is 
produced after bilateral excision of these glands, so that they do not appear to perform any import- 
ant function in these animals (/?. Ewald). Of dogs, cats, and foxes, only a very small number 
survive; nearly all die. It appears therefore that herbivora bear the operation and suffer fewer 
after-effects than carnivora (Sanquinco and Orecchia). The immediate effects are fibrillar 
contractions, which ultimately influence the gait of the animals, convulsions, anaesthesia, great 
diminution of sensibility, loss of flesh, redness of the ears, and intense heat of the skin (which 
disappear after several days), difficulty in seizing and eating food, kerato-conjunctivitis, and 
frequently disturbances of the rhythm of respiration with dyspnoea and spasms of the abdominal 
muscles (Schiff). The arterial blood contains about the same amount of O as venous blood. 
Certain parts of the peripheral nerves undergo a kind of degeneration similar to that found 
after nerve-stretching. There is albuminuria and fall of the blood-pressure. Death usually occurs 
between the third and fourth day, the animals being comatose (IVagner). Schiff found that if 
one-half of the gland was excised at once, and the other half a month afterwards, death did 
not occur; but Wagner denies this, for he asserts that the remaining half hypertrophies, and 
if it be excised, death occurs with the usual symptoms. In monkeys, five days after the 
operation, there are symptoms of nervous disturbance. The animals have lost their appetite, 
there are fibrillar contractions of the muscles of the face, hands, and feet, but the tremors 
disappear on voluntary effort. The appetite returns and is increased, but notwithstanding, the 
animal grows thin and pale; while the tremors increase and affect all the muscles of the body. 
These tremors are of central origin, because they disappear on dividing the nerve. Thus 
there is profound alteration of the motor powers: Amongst the outward symptoms are puffi- 
ness of the eyelids, swelling of the abdo- 
men, increased hebetude and dyspnoea, 
while afterwards there is a fall of the 
temperature and imbecility ; the tremors 
disappear, there is a pallor of the skin, and 
ultimately, after five to seven weeks, the 
animals die comatose. Thus there is slow 
onset of hebetude, terminating in imbe- 
cility. Very remarkable changes occur 
in the blood. There is a steady fall of the 
blood-pressure; a diminution of the red 
blood-corpuscles, or rather profound 
anaemia; leucocythaemia, the colorless 
corpuscles being increased to the ratio of 
four to fourteen; and lastly mucin is 
present in the blood, although normally it 
is not so. The salivary glands are hypertro- 
phied, owing to the presence of mucin, 
which is found even in the parotid, 
although this is normally a serous gland 
(§ 141.) The swelling of the abdomen 
is due to hypertrophy of the great omen- 
tum. Mucin is found in the peritoneal 
fluid, and the spleen is also enlarged. 
Thus these symptoms present many fea- 
tures in common with those of myxce- 
dema as described by Ord (v. Horsley).] 
Fig. 143 
Section of the thyroid gland, a, closed vesicles; 
b, distended by colloid masses and lined by low 
columnar epithelium; c, inter-vesicular connective 
tissue. 180 
[Sec. 103. 
THE SUPRARENAL CAPSULES. 
[Stages.—Horsley distinguishes three stages. In the first or neurotic stage, the animals 
exhibit constant tremors, 8 per second, and young animals do not appear to survive this stage. 
In the second or mucinoid stage, mucin is deposited in the tissues and blood; this change, 
however, is only seen to perfection in monkeys. If these animals be kept at a high artificial 
temperature, their life is considerably prolonged. In the third, atrophic or marasmic period, 
the animals die of marasmus, while they lose their excess of mucin. Age seems to exert an 
important influence in thyroidectomy; young dogs survive but a short time, while old dogs 
merely exhibit symptoms of indolence and incapacity; and, as a matter of fact, the activity of 
the gland seems to be greatest when tissue-metabolism is most active.] 
[The following table, after Horsley, indicates the symptoms that follow loss of the function 
of the thyroid gland. 
Stages. 
Duration. 
Symptoms. 
Remarks. 
I. Neurotic. 
I to 2 weeks in dogs; 
i to 3 weeks in 
monkeys. 
Tremors, rigidity, dysp- 
noea. 
Yonng dogs and monkeys 
alike die at this stage. 
II. Mucinoid. 
to i week in dogs; 
3 to 7 weeks in 
monkeys. 
Commencing hebetude 
and mucinoid degen- 
eration of the connec- 
tive-tissues. 
Dogs survive only to the 
beginning of this stage, 
monkeys die at the end, 
if not treated. 
III. Atrophic. 
5 to 8 weeks in mon- 
keys. 
Complete imbecility and 
atrophy of all tissues, 
especially muscles. 
Monkeys survive accord- 
ing to the temperature 
of the air-bath ] 
Functions.—The functions of the thyroid gland are very obscure. Perhaps it may be an 
apparatus for regulating the blood-supply to the head (?). It becomes enlarged in Basedow’s 
disease, in which there is great palpitation, as well as protrusion of the eyeballs or exophthalmos, 
which seem to depend upon a simultaneous stimulation of the accelerating nerve of the heart, 
and the sympathetic fibres of the smooth muscles in the orbital cavity and the eyelids, as well 
as of the inhibitory fibres of the vessels of the thyroid. In many localities it is common to find 
swelling of the thyroid constituting goitre, which is sometimes, but far from invariably, associ- 
ated with idiocy and cretinism. [Horsley finds that its removal is the essential cause of 
myxoedema and cretinism. He regards it (i) as a blood-forming gland, so that it has a haema- 
poietic function, but Gibson finds no grounds for supporting this view. During the anaemia 
resulting from its removal, the blood of the thyroid vein contains 7 per cent, more red blood- 
corpuscles than the corresponding artery (Horsley). (2) It seems to regulate the formation of 
mucin in the .body. After its removal the normal metabolism is no longer maintained, and 
there is a corresponding increasingly defective condition of nutrition.] 
According to Rogowitsch, the function of the thyroid is to neutralize a substance produced in 
the body, which, if it accumulated, would act as a poison on the central nervous system 
[Transplantation of the Thyroid.—Part of the thyroid of animals has been transplanted to 
the abdominal cavity and under the skin, but apparently, when so transplanted, fails to exercise 
any beneficial influence in cases of myxoedema.] 
In the Tunicata, this gland, represented by a groove, secretes a digestive fluid. In vertebrates 
it is an organ which has undergone a retrograde change (Gegenbaur). 
IV. The Suprarenal Capsules.—Structure.—These organs are invested 
by a thin capsule which sends processes into the substance of the organ. 
They consist of an outer (broad) or cortical layer and an inner (narrow) or 
medullary layer (fig. 144). The former is yellowish in color, firm and striated, 
while the latter is softer and deeper in tint. In- the outermost zone of the 
cortex (fig. 145), the trabeculae form polygonal meshes, which contain the 
cells of the gland-substance; in the broader middle zone the meshes are elong- 
ated, and the cells filling them are arranged in columns radiating outwards. 
Here the cells are transparent and nucleated, often containing oil-globules; in 
the innermost narrow zone the polygonal arrangement prevails, and the cells 
often contain yellowish-brown pigment. [Immediately under the capsule the 
cells are arranged in rounded groups—zona glomerulosa ; next to this the 
cells are arranged in columns, forming the widest zone or zona fasciculata, 
while next the medulla is the zona reticularis (fig. 145).] In the medulla 
the stroma forms a reticulum containing groups of cells of very irregular shape. Sec. 103.] 
THE SUPRARENAL CAPSULES. 
181 
Numerous blood-vessels occur in the gland, especially in the cortex. [The 
nerves are extremely numerous, and are derived from the renal and solar 
plexuses. Many of the fibres are medullated. After they enter the gland, 
numerous ganglionic cells occur in the plexuses which they form. Indeed, some 
observers regard the cells of the medulla as nervous. Undoubtedly, numerous 
multipolar nerve-cells exist within the gland.] 
Chemical Composition.—The suprarenals contain the constituents of connective- and nerve- 
tissue; also lucin, hypoxanthin, benzoic, hippuric, and taurocholic acids, taurin, inosit, fats, and 
a body which becomes pigmented by oxidation. Amongst inorganic substances potash and phos- 
phoric acid are most abundant. 
[Poisonous Extract.—Foa and Pellacani showed that a watery extract of the suprarenal 
capsule is poisonous to dogs, rabbits, and frogs. Marino-zuco has shown that the toxic base is 
neurin.] 
The function of the suprarenal bodies is very obscure. It is noticeable, however, that 
Capsule. 
Zona glomerulosa 
Z. fasciculate, 
Vortex. 
Z. reticularis. 
Strands of cells of 
the marrow. 
T. S. of a nerve, 
Ganglionic cells 
T. S. bundles of 
smooth muscle. 
Medulla. 
Cortex. 
Medulla. 
Vein. 
T. S. vein. 
Part of the suprarenal 
capsule of a child X 15. 
Fig. 144. 
Fig- 145- 
in Addison’s disease, or “bronzed skin,’’which is perhaps primarily a nervous affection, 
these glands have frequently, but not invariably, been found to be diseased. Owing to the 
injury to adjacent abdominal organs, extirpation of these organs is often, although not always, 
fatal; in dogs pigmented patches have been found in the skin near the mouth. [Tizzoni has 
found that many months after the excision of one or both suprarenals in dogs and rabbits, there 
is a profound alteration of the central nervous system. There is degeneration of the medullated 
nerve-fibres of certain parts of the cortex and white matter, and also of the gray and white 
matter of the cord. In the latter Goll’s column is specially affected, but the degenerated fibres 
are by no means confined to it.] Brown-Sequard thinks they may be concerned in preventing 
the over-production of pigment in the blood. 
[Spectrum.—MacMunn finds that the medulla of the suprarenal bodies (in man, cat, dog, 
guinea-pig, rat, etc.) gives the spectrum of htemochromogen ($ 18), while the cortex shows that 
of what he calls histohaematin, the latter being a group of respiratory pigments. He finds 
that haemochromogen is only found in excretory organs (the bile, the liver), hence he regards 
the medulla as excretory, so that part of the function of the adrenals may be “ to metamor- 
phose effete haemoglobin or haematin into haemochromogen,” and when they are diseased, the 
T. S., human suprarenal capsule X 50- 182 
[Sec. 103. 
HYPOPHYSIS CEREBRI. 
effete pigment is not removed, hence the pigmentation of the skin and mucous membranes. 
Taurocholic acid has been found in the medulla by Vulpian, and pyrocatechin by Krukenberg. 
MacMunn believes that “they have a large share in the downward metamorphosis of coloring 
matter.”] 
V. Hypophysis Cerebri—Coccygeal and Carotid Glands.—The hy- 
pophysis cerebri, or pituitary body, consists of an anterior lower or larger 
lobe, partly embracing the posterior lower or smaller lobe. These two lobes 
are distinct in their structure and development. The posterior lobe is a part 
of the brain, and belongs to the infundibulum. The nervous elements are 
displaced by the ingrowth of connective-tissue and blood-vessels. The atiterior 
portion represents an inflected and much altered portion of ectoderm, from 
which it is developed. It contains gland-like structures, with connective- 
tissue, lymphatics, and blood-vessels, the whole being surrounded by a capsule. 
According to Ecker and Mihalkowicz, it resembles the suprarenal capsule in 
its structure, while, according to other observers, in some animals it is more 
like the thyroid. Its functions are entirely unknown. 
[Excision.—Horsley has removed this gland twice successfully in dogs, which lived from 
five to six months. No nervous or other symptoms were noticed, but when the cortex of the 
brain was exposed and stimulated, a great increase in the excitability of the motor regions was 
induced, even slight stimulation being followed by violent tetanus and prolonged epilepsy.] 
Coccygeal and Carotid Glands.—The former, which lies on the tip of the coccyx, is com- 
posed to a large extent of plexuses of small, more or less cavernous arteries, supported and 
enclosed by septa and a capsule of connective-tissue (Luschka). Between these lie polyhedral 
granular cells arranged in networks. The carotid gland has a similar structure (p. 92). Their 
functions are quite unknown. Perhaps both organs maybe regarded as the remains of embryonal 
blood-vessels {Arnold). 
104. COMPARATIVE.—The heart in fishes (fig. 146, I), as well as in the larvae of 
amphibians with gills, is a simple venous heart, consisting of an auricle and a ventricle. The 
ventricle propels the blood to the gills, where it is oxygenated (arterialized); thence it passes 
into the aorta to be distributed to all parts of the body, and returns through the capillaries of 
the body and the veins to the heart. The amphibians (frogs) have two auricles and one 
ventricle (Frog, II). From the latter there proceeds one vessel which gives off the pulmonary 
arteries, and as the aorta supplies the rest of the body with blood, the veins of the systemic 
circulation carry their blood to the right auricle, those of the lung into the left auricle. In 
fishes and amphibians there is a dilatation at the commencement of the aorta, the bulbus arteriosus, 
which is partly provided with strong muscles. The reptiles (III) possess two separate auricles, 
and two imperfectly separated ventricles. The aorta and pulmonary artery arise separately from 
the latter two chambers. The venous blood of the systemic and pulmonary circulations flows 
separately into the right and left auricles, and the two streams are mixed in the ventricle. In 
some reptiles the opening in the ventricular septum seems capable of being closed. The com- 
plete separation of the ventricle into two is seen in fig. IV, in the tortoise. The lower vertebrates 
have valves at the orifices of the venae cavae, which are rudimentary in birds and some mammals. 
All birds and mammals have two completely separate auricles and two separate ventricles. 
In the halicore the apex of the ventricles is deeply cleft. Some animals have accessory hearts, 
e.g., the eel in its caudal vein. They are very probably lymph-hearts {Robin). The veins of 
the wing of the bat pulsate {Sckiff). The lowest vertebrate, amphioxus, has no heart, but 
only a rhythmically-pulsating vessel. 
Amongst blood-glands, the thymus and spleen occur throughout the vertebrata, the latter 
being absent only in amphioxus and a few fishes. 
Amongst invertebrata a closed vascular system, with pulsatile movement, occurs here and 
there, e.g., amongst echinodermata (star-fishes, sea-urchins, holothurians) and the higher 
worms. The insects have a pulsating “ dorsal vessel ” as the central organ of the circulation, 
which is a contractile tube provided with valves and dilated by muscular action; the blood being 
propelled rhythmically in one direction into the spaces which lie amongst the tissues and organs, 
so that these animals do not possess a closed vascular system. The mollusca have a heart with 
a lacunar vascular system. The cephalopods (cuttle-fish) have three hearts—a simple arterial 
heart, and two venous simple gill-hearts, each placed at the base of the gills. The vessels 
form a completely closed circuit. The lowest animals have either a pulsatile vesicle, which 
propels the colorless juice into the tissues (infusoria), or the vascular apparatus may be entirely 
absent. Sec. 105.] 
HISTORICAL RETROSPECT OF THE CIRCULATION. 
183 
105. HISTORICAL RETROSPECT.—The ancients held various theories regarding the 
movement of the blood, but they knew nothing of its circtilatiofi. According to Aristotle (384 
B.c.), the heart, the acropolis of the body, prepared in its cavities the blood, which streamed 
through the arteries as a nutrient fluid to all parts of the body, but never returned to the heart. 
With Herophilus and Erasistratus (300 B.C.), the celebrated physicians of the Alexandrian 
school, originated the erroneous view that the arteries contain air, which was supplied to them 
by the respiration (hence the name artery). They were led to adopt this view from the empty 
condition of the arteries after death. By experiments upon animals, Galen disproved this view 
(131-201 a.d.)—“Whenever I injured an artery,” he says, “blood always flowed from the 
wounded vessel. On tying part of an artery between two ligatures, the 
part of the artery so included is always filled with blood.” 
Still, the idea of a single centrifugal movement of the blood was retained, 
and it was assumed that the right and left sides of the heart communicated 
directly by means of openings in the septum of the heart, until Vesalius 
showed that there are no openings in the septum. Michael Servetus (a 
Spanish monk, burned at Geneva, at Calvin’s instigation, in 1553) discovered 
I. 
IV 
II. 
111. 
Fig. 146. 
Schemata of the circulation. I. Fish.—A, auricle; .S', sinus venosus; V, ventricle; B, bulbus 
aortae; c, branchial arteries; i, branchial vessels; Vv, branchial veins; F, circulus cephali- 
cusaortae; A) common aorta; G, caudal artery; If, duct of Cuvier; /, anterior, and AT) 
posterior cardinal veins; Z,caudal vein; M, M, kidneys. II. Frog.—I, sinus venosus; 
II, and III, right and left auricles; IV, ventricle; V, aorta with the bulb; 1, pulmonary 
arteries; 2, arch of the aorta; 3, carotid; 4, lingual; 5, carotid gland, and 6, axillary 
arteries; 7, common aorta; 8, coeliac artery; 9, cutaneous artery; Vv, pulmonary veins; 
p,p, lungs. III. Saurians.—I, right auricle, with the venae cavae; II, right ventricle; 
III, left auricle; IV, left ventricle; V, anterior common aorta; 1, pulmonary artery; 2, arch 
of the aorta; 3, carotid artery; 4, posterior common aorta; 5, coeliac, and 6, subclavian, 
arteries; 7, pulmonary veins; 8, lungs. IV. Tortoise.—I, right auricle with the venae 
cavae; II, right, and IV, left ventricles ; III, left auricle; 1 and 2, right and left aortas ; 3, 
posterior common aorta; 4, coeliac; 5, subclavian; 6, carotid, and 7, pulmonary arteries; 
8, pulmonary veins. 
the pulmonary circulation. Cesalpinus confirmed this observation, and named it “ Circulatio.” 
Fabricius ab Aquapendente (Padua, 1574) investigated the valves in the veins more carefully 
(although they were known in the 5th century to Theodoretus, Bishop in Syria), and he was ac- 
quainted with the centripetal movement of the blood in the veins. Up to this time it was imagined 
that the veins carried blood from the centre to the periphery, although Vesalius was acquainted 
with the centripetal direction of the blood-stream in the large venous trunks. At length William 
Harvey, who was a pupil of Fabricius (1604), demonstrated the complete circulation (1616— 184 
HISTORICAL RETROSPECT OF THE CIRCULATION. 
[Sec. 105. 
1619), and published his great discovery in 1628. [For the history of the discovery of the circu- 
lation of the blood, see the works of Willis on “ W. Harvey,” “ Servetus and Calvin,” those of 
Kirchner, and the various Harveian orations.] 
According to Hippocrates, the heart is the origin of all the vessels; he was acquainted with 
the large vessels arising from the heart, the valves, the chordae tendineae, the auricles, and the 
closure of the semi-lunar valves. Aristotle was the first to apply the terms aorta and venae cavae ; 
the school of Erasistratus used the term carotid, and indicated the functions of the venous 
valves. In Cicero a distinction is drawn between arteries and veins. Celsus mentions that if a 
vein be struck below the spot where a ligature has been applied to a limb, it bleeds, while 
Aretseus (50 a.d ) knew that arterial blood was bright, and venous blood dark. Pliny (f 79 
a.d.) described the pulsating fontanelle in the child. Galen (131-203 A.D.) was acquainted 
with the existence of a bone in the septum of the heart of large animals (ox, deer, elephant). He 
also surmised that the veins communicated with the arteries by fine tubes. The demonstration 
of the capillaries, however, was only possible by the use of the microscope, and employing 
this instrument, Malpighi (1661) was the first to demonstrate the capillary circulation. Leuwen- 
hoek (1674) described the capillary circulation more carefully, as it may be seen in the web of 
the frog’s foot and other transparent membranes. Blanchard (1676) proved the existence of 
capillary passages by means of injections. William Cooper (1697) proved that the same con- 
dition exists in warm-blooded animals, and Ruysch made similar injections. Stenson (bom 1638) 
established the muscular nature of the heart, although the Hippocratic and Alexandrian schools 
had already surmised the fact. Cole proved that the sectional area of the blood-stream became 
wider towards the capillaries (1681). Joh. Alfons Borelli (1608-1679) was the first to estimate 
the amount of work done by the heart. Physiology of Respiration. 
The object of respiration is twofold, viz., to supply the oxygen necessary 
for the oxidation processes that go on in the body, as well as to remove the 
carbon dioxide formed within the body. [Tissue-life implies the continuous 
and constant supply of oxygen, and hence in mammals and the higher verte- 
brates the lungs are relatively very large, and yield a free supply of oxygen.] 
The most important organs for this purpose are the lungs. There is an outer 
and an inner respiration—the former embraces the exchange of gases be- 
tween the external air and the blood-gases of the respiratory organs (lungs and 
skin)—the latter, the exchange of gases between the blood in the capillaries of 
the systemic circulation and the tissues of the body. 
[The pulmonary apparatus consists of (i) an immense number of small sacs— 
the air-vesicles—filled with air, and covered externally by a very dense 
plexus of capillaries ; (2) the air-passages—the nose, pharyx, larynx, trachea, 
and bronchi communicating with (1); (3) the thorax with its muscles, acting 
like a pair of bellows, and moving the air within the lungs.] 
106. STRUCTURE OF THE AIR-PASSAGES AND LUNGS. 
—The lungs are compound tubular glands, which separate C02 from the blood. 
Each lung is provided with an excretory duct (bronchus) which joins the com- 
mon respiratory passage of both lungs—the trachea. 
Trachea.—The trachea and extra-pulmonary bronchi are similar in struc- 
ture. The basis of the trachea consists of 16-20 C-shaped incomplete carti- 
laginous hoops placed over each other. These rings consist of hyaline cartilage, 
and are united to each other by means of tough fibrous tissue containing much 
elastic tissue, the latter being arranged chiefly in a longitudinal direction. 
The function of the cartilages is to keep the tube open under varying con- 
ditions of pressure. Pieces of cartilage having a similar function occur in the 
bronchi and their branches, but they are absent from the bronchioles, which 
are less than 1 mm. in diameter. In the smaller bronchi, the cartilages are 
fewer and scattered more irregularly. [In a transverse section of a large intra- 
pulmonary bronchus, two, three, or more pieces of cartilage, each invested 
by its perichondrium, may be found.] At the points where the bronchi sub- 
divide, the cartilages assume the form of irregular plates embedded in the 
bronchial wall. 
An external fibrous layer of connective tissue and elastic fibres covers the 
trachea and the extra-pulmonary bronchi externally. Towards the oesophagus, 
the elastic elements are more numerous, and there are also a few bundles of 
plain muscular fibres arranged longitudinally. Within this layer there are bundles 
of non-striped muscular fibres which pass transversely between the cartilages 
behind, and also in the intervals between the cartilages. [These pale reddish 
fibres constitute the trachealis muscle, and are attached to the inner sur- 
faces of the cartilages at a little distance from their free ends. The arrange- 
ment varies in different animals—thus, in the cat, dog, rabbit, and rat the mus- 
cular fibres are attached to the external surfaces of the cartilages, while in the 
pig, sheep, and ox they are attached to their internal surfaces (Stirling).'] Some 186 
STRUCTURE OF THE TRACHEA. 
[Sec. 106. 
muscular fibres are arranged longitudinally external to the transverse fibres. 
The function of these muscular fibres is to prevent too great distention when 
there is great pressure within the air-passages. 
The mucous membrane of the trachea consists of a basis of very fine 
connective-tissue, containing much adenoid tissue with numerous lymph-cor- 
puscles. Numerous elastic fibres 
are arranged chiefly in a longi- 
tudinal direction under the base- 
ment membrane. They are also 
abundant in the deep layers of the 
posterior part of the membrane 
opposite the intervals between the 
cartilages. A small quantity ot 
loose submucous connective 
tissue containing the large blood- 
vessels, glands, and lymphatics 
unites the mucous membrane to 
the perichondrium of the carti- 
lages. The epithelium consists 
of a layer of columnar ciliated 
cells with several layers of imma- 
ture cells under them. [The 
superficial layer of cells is colum- 
nar and ciliated (fig. 147, b), 
while those lying under them 
present a variety of forms, and 
below all is a layer of somewhat 
flattened squames, c, resting on 
the basement membrane, d. These 
squames constitute a layer quite 
distinct from the basement mem- 
brane, and they form the layer 
described as Debove’s mem- 
brane. They are active germin- 
ating cells, and play a most im- 
portant part in connection with 
the regeneration of the epithe- 
lium, after the superficial layers 
have been shed, in such condi- 
tions as bronchitis. Not unfre- 
quently a little viscid mucus (a) 
lies on the free ends of the cilia. In the intermediate layer, the cells are more 
or less pyriform or battledore-shaped, with their long tapering process inserted 
amongst the deeper layers of cells. According to Drasch, this long process is 
attached to one of these cells and is an outgrowth from it, the whole constituting 
a “ foot-cell.”] 
Under the epithelium is the homogeneous basement membrane, through 
which fine canals pass, connecting the cement of the epithelium with spaces 
in the mucosa. [This membrane is well marked in the human trachea, where 
it plays an important part in many pathological conditions, e. g., bronchitis. 
It is stained bright red with picrocarmine.] The cilia act so as to carry any 
secretion towards the larynx. Goblet cells exist between the ciliated columnar 
cells. Numerous small compound tubular mucous glands occur in the 
mucous membrane, chiefly between the cartilages. Their ducts open on the 
Fig. 147. 
Transverse section of part of a human bronchus (X 450). 
a, precipitated mucus; b, ciliated columnar epithe- 
lium ; c, deep germinal layer of cells (Debove’s mem- 
brane) ; d, elastic basement membrane; e, elastic 
fibres divided transversely (inner fibrous layer); f, 
bronchial muscle; g, outer fibrous layer with leuco- 
cytes and pigment granules (black) below a mass of 
adenoid tissue. Sec. 106.] 
STRUCTURE OF THE BRONCHI. 
187 
surface by means of a slightly funnel-shaped aperture, into which the ciliated 
epithelium is prolonged for a short distance. [The acini of some of these 
glands lie outside the trachealis muscle. The acini are lined by cubical or 
columnar secretory epithelium. In some animals (dog) these cells are clear, 
and present the usual characters of a mucus-secreting gland; in man, some of 
the cells may be clear, and others “ granular,” but the appearance of the cells 
depends upon the physiological state of activity.] These glands secrete the 
mucus, which entangles particles inspired with the air, and is carried towards 
the larynx by ciliary action. [Numerous lymphatics exist in the mucous and 
sub-mucous coat, and not unfrequently small aggregations of adenoid tissue 
occur (especially in the cat) in the mucous coat, usually around the ducts of the 
glands. They are comparable to the solitary follicles of the alimentary tract. 
The blood-vessels are not so numerous as in some other mucous membranes. 
[A plexus of nerves containing numerous ganglionic cells at the nodes exists 
on the posterior surface of the trachealis muscle. The fibres are derived from 
the vagus, recurrent laryngeal, and sympathetic (C. Frankenhauser, W. Stir- 
ling, Kandarazi').~\ 
[The mucous membrane of the trachea and extra-pulmonary 
bronchi, therefore, consists of the following layers from within outwards :— 
(1) Stratified columnar ciliated epithelium. 
(2) A layer of flattened cells (Debove’s membrane). 
(3) A clear homogeneous basement membrane. 
(4) A basis of areolar tissue, with adenoid tissue and blood-vessels, and 
outside this a layer of longitudinal elastic fibres. 
Outside this, again, is the sub-mucous coat, consisting of loose areolar 
tissue, with the larger vessels, lymphatics, nerves, and mucous glands.] 
[The Bronchi.—In structure the extra pulmonary bronchi resemble the 
trachea. As they pass into the lung they divide very frequently, and the 
branches do not anastomose. In the intra-pulmonary bronchi the sub- 
divisions become finer and finer, the finest branches being called terminal 
bronchi, or bronchioles, which open separately into clusters of air-vesicles.] 
[Eparterial and Hyparterial Bronchi.—As the bronchi proceed, one 
main trunk passes into the lung, running towards its base, and from it are given 
off branches dorsally and ventrally, and these branches again subdivide. In 
man one main branch comes off from the right bronchus and proceeds to the 
upper right lobe, above the place where the pulmonary artery crosses the 
bronchus. Such branches are called eparterial, and they are more numerous 
in birds. In man, all the branches, both on the right and left side, come off 
below the point where the pulmonary artery crosses the bronchus, and are called 
hyparterial bronchi ( C. Aeby).~\ 
[In the middle-sized intra-pulmonary bronchi the usual characters of the 
mucous membrane are retained, only it is thinner ; the cartilages assume the 
form of irregular plates situated in the outer wall of the bronchus; while the 
muscular fibres are disposed in a complete circle, constituting the bronchial 
muscle (fig. 147,/). When this muscle is contracted, or when the bronchus 
as a whole is contracted, the mucous membrane is thrown into longitudinal 
folds, and opposite these folds the elastic fibres form large elevations. This 
muscle is particularly well developed in the smaller microscopic bronchi. 
Numerous elastic fibres, e, disposed longitudinally, exist under the basement 
membrane, d. They are continuous with those of the trachea, and are pro- 
longed onwards into the lung. The mucous membrane of the larger intra- 
pulmonary bronchi consists of the following layers from within outwards: — 
(1) Stratified columnar ciliated epithelium (fig. 147, F). 
(2) Debove’s membrane (fig. 147, c). 188 
STRUCTURE OF THE BRONCHI. 
[Sec. 106. 
(3) Transparent homogeneous basement membrane (fig. 147, d). 
(4) Areolar tissue with longitudinal elastic fibres (fig. 147, e). 
(5) A continuous layer of non-striped muscular fibres disposed circularly 
{bronchial muscle, fig. 147,/"). 
Outside this is the sub-mucous coat, consisting of areolar tissue mixed with 
much adenoid tissue (fig. sometimes arranged in the form of cords, the 
lymph-follicular cords. It also contains the acini of the numerous 
mucous glands, blood-vessels, and lymphatics. The ducts of the glands 
perforate the muscular layer, and open on the free surface of the mucous mem- 
brane. The sub-mucous coat is connected by areolar tissue with the perichon- 
drium of the cartilages. Outside the cartilages are the nerves and nerve- 
ganglia accompanying the bronchial vessels. 
The branches of the pulmonary artery and 
of the pulmonary vein usually lie on op- 
posite sides of the bronchus, while there are 
several branches of the bronchial arteries 
and veins. Fat cells also occur in the 
peri-bronchial tissue.] 
In the small bronchi the cartilages and 
glands disappear, but the circular muscular 
fibres are well developed. They are lined 
by lower columnar ciliated epithelium, con- 
taining goblet-cells. 
[The bronchi when traced into the lung 
divide more or less dichotomously, and run 
between the lobules, constituting inter- 
lobular bronchi, and accompanied by 
branches of the pulmonary artery and vein. 
The branches become smaller and smaller 
until they end finally in terminal bronchi 
(.5 to 1 mm. in diameter). These terminal 
bronchi or lobular bronchi open into the 
apex of a lobule. As they pass into the 
lobule they give off, usually at nearly a right 
angle, several branches—the intralobular 
bronchi — or bronchioles, sometimes 
spoken of as alveolar passages. These 
alveolar passages are beset on all sides by air-cells. Each bronchiole opens into 
one or two wider passages, having the shape of an inverted cone, called an 
infundibulum (fig. 149, I), with delicate walls, and beset with air-vesicles, 
air-cells or alveoli (fig. 149). The cup-shaped air-vesicles open into the in- 
fundibulum, but do not communicate with each other. The infundibula are 
much wider than the bronchioles and also than the alveoli. Each terminal 
bronchiole with its infundibula and air-vesicles constitutes an acinus or 
lobulet, and all the lobulets connected with a terminal bronchus make up a 
single lobule. The lobules are arranged with their bases externally, and are 
separated from each other by connective tissue—inter-lobular septa (fig. 
149, IS)—so that in a partially pigmented lung, on examining its pleural sur- 
face with the naked eye, one can easily make out its lobules, consisting of a 
series of polygonal areas mapped out by black lines. In a young animal, e. g., 
calf, they are easily separated from each other after removal of the pleura. 
The inter-lobular septa are continuous on the one hand with the sub-pleural 
connective tissue and on the other with the peri-bronchial connective tissue.] 
[There is an alteration in the structure of the bronchi, as we proceed 
Termination of a bronchiole and of a pul- 
monary arteriole prepared by corrosion 
and magnified by a hand lens. A, bron- 
chiole ; B, branch of pulmonary artery. 
Fig. 148. Sec. 106.] 
STRUCTURE OF THE BRONCHI AND AIR-CELLS. 
189 
from the larger to the smaller tubes. The cartilages and glands are the first 
structures to disappear. The circular bronchial muscle is well developed in the 
smaller bronchi and bronchioles, and exists as a continuous thin layer over the 
alveolar passages, but it is not continued over and between the air-cells. 
Elastic fibres, continuous, on the one hand, with those in the smaller bronchi, 
and, on the other, with those in the walls of the air-cells, lie outside the mus- 
cular fibres in the bronchioles and infundibula. In the respiratory bronchioles, 
the ciliated epithelium is reduced to a single layer, and is mixed with the 
squamous form of epithelium, while where the alveolar passages open into the 
air-cells or alveoli, the epithelium is non-ciliated, low, and polyhedral.] 
Fig. 149. 
Scheme of a lung lobule. PA, and PV, pulmonary artery and vein; TB, terminal bronchus; 
Br., bronchiole; I, infundibulum; av, air-vesicles; IS, inter-lobular septum; PP, pleura; 
LB, lobular bronchus. 
Alveoli or Air-Cells.—The form of the air-cells, which are 25 ;j. inch) 
in diameter, may be more or less spherical, polygonal, or cup-shaped. They 
are disposed around and in communication with the alveolar passages. Their 
form is determined by the existence of a nearly structureless membrane, com- 
posed of slightly fibrillated connective-tissue containing a few corpuscles. 
This is surrounded by numerous fine elastic fibres, which give to the pulmonary 
parenchyma its well-marked elastic characters (fig. 153, e, e). These fibres 
often bifurcate, and are arranged with reference to the alveolar wall. They are 
very resistant, and in some cases of lung disease may be recognized in the 
sputum. A few non-striped muscular fibres exist in the delicate connective THE AIR-VESICLES OF THE LUNG. 
[Sec. 106. 
tissue between adjoining air-vesicles. These muscular fibres sometimes become 
greatly developed in certain diseases {Arnold, IV. Stirling). The air-cells are 
lined by two kinds of cells—(i) large, transparent, clear polygonal non- 
nucleated squames or placoids (22-45,a) lying operand between the capil- 
laries in the alveolar wall (fig. 151,0:); (2) small irregular “granular” 
nucleated cells (7-15 p) arranged 
singly or in groups (two or three) 
in the interstices between the capil- 
laries. They are well seen in a 
cat’s lung (fig. 151, d). When 
acted on with nitrate of silver the 
cement-substance bounding the 
clear cells is stained, but the small 
cells become of a uniform brown 
granular appearance, so that they 
are readily recognized. Small 
markings (? holes) or “ pseudo- 
stomata ” exist in the cement-sub- 
stance, and are most obvious in 
distended alveoli. They open into 
the lymph-canalicular system of the 
alveolar wall {Klein), and through 
them the lymph-corpuscles, which 
are always to be found on the sur- 
face of the air-vesicles, migrate, and 
carry with them into the lympha- 
tics particles of carbon derived from 
the air. In the alveolar walls is a 
very dense plexus of fine capil- 
laries (fig. 153, c), which lie more towards the cavity of the air-vesicle, being 
covered only by the epithelial lining of the air-cells. Between two adjacent 
alveoli there is only a single layer of capillaries (man), and on the boundary 
line between two air-cells the course of the capillaries is twisted, thus project- 
ing sometimes into the one aveolus, sometimes into the other (fig. 152). 
[In the lung of the newt, which is simply an oval sac with elastic and contractile walls, sup- 
plied by an artery and a vein, the capillary network lies immediately under the epithelium. 
The meshes themselves are narrow, although the capillaries corresponding to the large size of 
the blood-corpuscles are fairly wide. The epithelium consists of a single layer of thin cells 
peculiarly modified. The nucleated bodies of three or more cells have an appreciable thickness 
and lie in the extra-vascular meshes or islands, and from each cell there stretches an excessively 
thin wing-shaped expansion over the surface of the capillary, to meet a similar expansion from 
another cell lying in an adjacent mesh or island. Thus the blood in the capillary is separated 
from the air in the lung only by the thin capillary wall and the excessively thin wing-like 
expansions of the smaller “ respiratory epithelium.” The newt’s lung represents a very simple 
type of lung. In the frog the lung begins to be more complex. The infundibulum of the 
mammalian lung practically repeats the condition obtaining in the newt’s lung.] 
[The number of alveoli is stated to be about 725 millions, a result obtained 
by measuring the size of the air-vesicles and ascertaining the amount of air in 
the lung, after an ordinary inspiration, determining how much of this air is in 
the air-vesicles and bronchi respectively. The superficial area of the air- 
vesicles is about 90 square metres, or 100 times greater than the surface of the 
body (.8 to .9 sq. metre).] 
The Blood-vessels of the lung belong to two different systems:—(A) 
Pulmonary vessels (lesser circulation). The branches of the pulmonary 
artery accompany the bronchi and are closely applied to them. [As they 
proceed they branch, but the branches do not anastomose, and ultimately they 
Air-cell. 
Infundibulum. 
Infundibulum. 
Air-cell. 
Alveolar 
passage. 
Bronchiole. 
Scheme of a bronchiole terminating in alveolar 
passages, those leading into infundibula beset with 
air-vesicles. 
Fig. 150. Sec. I06.] 
THE BLOOD-VESSELS OF THE LUNGS. 
terminate in small arterioles, which supply several adjacent alveoli, each 
arteriole splitting up into capillaries for several air-cells (figs. 152, 153, v, c). 
An efferent vein usually arises at the opposite side of the air-cells, and carries 
away the purified blood from the capillaries. In their course these veins unite 
to form the pulmonary veins, which, again, are joined in their course by a 
few small bronchial veins. The veins usually anastomose in the earlier part of 
their course, whilst the corresponding arteries do not.] Although the capillary 
plexus is very fine and dense, its sectional area is less than the sectional area of 
the systemic capillaries, so that the blood-stream in the pulmonary capillaries 
must be more rapid than that in 
the capillaries of the body gen- 
erally. The pulmonary veins, 
unlike veins generally, are col- 
lectively narrower than the pul- 
monary artery (water is given off 
in the lungs), and they have no 
valves. 
[The pulmonary artery con- 
tains venous blood, and the pul- 
monary veins pure or arterial 
blood.] 
(B) The bronchial vessels 
represent the nutrient system of 
the lungs. The bronchial ar- 
teries (1-3) arise from the aorta 
(or intercostal arteries) and ac- 
company the bronchi without 
anastomosing with the branches 
of the pulmonary artery. In 
their course they give branches 
to the lymphatic glands at the 
hilum of the lung, to the walls 
of the large blood-vessels (vasa 
vasorum), the pulmonary pleura, 
the bronchial walls, and the in- 
terlobular septa. The blood which issues from their capillaries is returned— 
partly by the pulmonary veins—hence, any considerable interference with the 
pulmonary circulation causes congestion of the bronchial mucous membrane, 
resulting in a catarrhal condition of that membrane. The greater part of the 
blood is returned by the bronchial veins, which open into the vena azygos, in- 
tercostal vein, or superior vena cava. The veins of the smaller bronchi (fourth 
order onwards) opens into the pulmonary veins, and the anterior bronchial also 
communicate with the pulmonary vein (Zuckerkandl). 
[The Pleura.—Each pleural cavity is distinct, and is a large serous sac, which 
really belongs to the lymphatic system of the lung. The pleura consists of two 
layers, visceral and parietal. The visceral pleura covers the lung; the 
parietal portion lines the wall of the chest, and the two layers of the corre- 
sponding pleura are continuous with one another at the root of the lung. The 
parietal pleura is the thicker, and may readily be separated from the inner sur- 
face of the chest. Structurally, the pleura resembles a serous membrane, and 
consists of a thin layer of fibrous tissue covered by a layer of endothelium. 
Under this layer, or the pleura proper, is a deep or sub-serous layer of 
looser areolar tissue, containing many elastic fibres. The layer of the pleura 
pulmonalisof some animals, as the guinea-pig, contains a network of non-striped 
muscular fibres. Over the lung it is also continuous with the interlobular septa.] 
Air-vesicles injected with silver nitrate, a, outlines of 
squamous epithelium; b, alveolar wall; c, young epi- 
thelium cell; d, aggregation of young epithelial cells 
germinating x 35°- 
Fig. 151- THE BLOOD-VESSELS OF THE LUNGS. 
[Sec. 106. 
[The Interlobular Septa (fig. 154, e) consist of bands of fibrous tissue sepa- 
rating adjoining lobules, and they become continuous with the peri-bronchial con- 
nective tissue entering the lung at itshilum. Thus the fibrous framework of the 
lung is continuous throughout the lung, just as in other organs. The connec- 
tion of the sub-pleural fibrous tissue with the connective tissue within the sub- 
stance of the lung has most important pathological bearings. The interlobular 
septa contain lymphatics and blood-vessels. The endothelium covering the 
parietal layer is of the ordinary squamous type, but on the pleura pulmonalis 
the cells are less flattened, more polyhedral, and granular. They must neces- 
sarily vary in shape with changes in the volume of the lung, so that they are 
more flattened when the lung is distended, as during inspiration. The pleura 
contains many lymphatics, which communicate by means of stomata with 
the pleural cavity.] 
[The Lymphatics of the lung are numerous, and are arranged in several 
Fig. 152. 
Section of the vesicular tissue of a human lung injected from the pulmonary artery; a, a, free 
margins of the alveoli; b, small artery; c, c, vertical walls of alveoli divided transversely. 
systems. The various air-cells are connected with each other by very delicate 
connective tissue, and, according to J. Arnold, in some parts this interstitial 
tissue presents characters like those of adenoid tissue; so that the lung is tra- 
versed by a system of juice-canals or “ Saft-Canalchen.” In the deep layer 
of the pleura there is (a) sub-pleural plexus of lymphatics partly derived 
from the pleura, but chiefly from the lymph-canalicular system of the pleural 
alveoli. Some of these branches proceed to the bronchial glands, but others 
pass into the interlobular septa, where they join (b) the peri-vascular lym- 
phatics which arise in the lymph-canalicular system of the alveoli. These trunks, 
provided with valves, run alongside the pulmonary artery and vein, and in their 
course they form frequent anastomoses. Special vessels arise within the walls 
of the bronchi, and occur chiefly in the outer coat of the latter, constituting (V) 
the peri-bronchial lymphatics, which anastomose with b. The branches 
of these two sets run towards the bronchial glands. Not unfrequently (cat) Sec. 106.] 
THE LYMPHATICS OF THE LUNG. 
193 
masses of adenoid tissue are found in the course of these lymphatics.] The 
lymph-canalicular system and the lymphatics become injected, when fine colored 
particles are inspired, or are introduced into the air-cells artificially. The pig- 
ment particles pass through the semi-fluid cement-substance into the lymph- 
canalicular system and thence into the lymphatics; or, according to Klein, 
they pass through actual holes or pores in the cement (p. 190). [This pigmen- 
tation is well seen in coal-miner’s lung or anthracosis, where the particles 
of carbon pass into and are found in the lymphatics. Sikorski and Kuttner 
showed that pigment reached the lymphatics in this way during life. If pig- 
ment, China ink or indigo-carmine, be introduced into a frog’s lung, it is found 
in the lymphatic system of the lung. Ruppert, and also Schotielius, showed 
Fig. 153- 
Semi-diagrammatic representation of the air-vesicles of the lung. v. v, blood-vessels at the mar- 
gins of an alveolus; c, c, its blood-capillaries; E, relation of the squamous epithelium of an 
alveolus to the capillaries in its wall; f, alveolar epithelium shown alone; e, e, elastic 
tissue of the lung. 
that the same result occurred in dogs, after the inhalation of charcoal, cinna- 
bar, or precipitated Berlin blue, and von Ins after the inhalation of silica. 
Schestopal used China ink and cinnabar suspended in per cent, salt solution.] 
Excessively fine lymph-canals lie in the wall of the alveoli in the interspaces of 
the capillaries, and there are slight dilatations at the points of crossing. Ac- 
cording to Pierret and Renaut, every air-cell of the lung of the ox is surrounded 
by a large lymph-space, such as occurs in the salivary glands. When a large 
quantity of fluid is injected into the lung, it is absorbed with great rapidity; 
even blood-corpuscles rapidly pass into the lymphatics. 
The superficial lymphatics of the pulmonary pleura communicate with 
the pleural cavity by means of free openings or stomata, and the same is true 
of the lymphatics of the parietal pleura, but these stomata are confined to 194 
THE NERVES OF THE LUNG. 
[Sec. 106. 
limited areas over the diaphragmatic pleura. [The lymphatics in the costal 
pleura occur over the intercostal spaces and not over the ribs (Dybkowski).~\ 
The large arteries of the lung are provided with lymphatics which lie between 
the middle and outer coats. [The movements of the lung during respiration 
are most important factors in moving the lymph onwards in the pulmonary 
lymphatics. The reflux of the lymph is prevented by the presence of valves.]. 
[Absorption of particles in lungs and pleura.— If blood or China ink be injected into the 
lungs, the corpuscles are rapidly absorbed from the lungs, but not from the trachea or large 
bronchi. In the lungs the particles pass between the alveolar epithelium into the interstitial pul- 
monary tissue, and finally into the peri-bronchial and peri-arterial lymphatics, and from thence 
to the bronchial lymph-glands. Similar injections into the pleural cavity are absorbed (5-30 
minutes) by the costal and mediastinal pleura, but not by the pulmonary pleura.] 
[The nerves of the lung are derived from the anterior and posterior pul- 
monary plexuses and consist of branches from the vagus and sympathetic, 
and from certain dorsal nerves (p. 153). They enter the lungs and follow the 
distribution of the bronchi, several sections of nerve-trunks being usually found 
in a transverse section of a large bronchial tube. The nerves lie outside the 
cartilages, and are in close relation with the branches of the bronchial arteries. 
Medullated and non-medullated nerve-fibres occur in the nerves, which also 
contain numerous small ganglia (Remak, Klein, Stirling). In the lung of the 
calf the ganglia are large. The exact mode of termination of the nerve-fibres 
within the lung has yet to be ascertained in mammals, but some fibres pass to 
the bronchial muscle, others to the large blood-vessels of the lung, and it is 
highly probable that the mucous glands are also supplied with nerve filaments. 
In the comparatively simple lungs of the frog, nerves with numerous nerve-cells 
in their course are found (.Arnold, Stirling), and in the very simple lung of the 
newt, there are also numerous nerve cells disposed along the course of the 
intra-pulmonary nerves. Some of these fibres terminate in the uniform layer 
of non-striped muscle which forms part of the pulmonary wall in the frog and 
newt, and others end in the muscular coat of the pulmonary blood-vessel (Stir- 
ling). The functions of these ganglia are unknown, but they may be compared 
to the nerve-plexuses existing in the walls of the digestive tract.] 
The Function of the non-striped muscle of the entire bronchial system 
seems to be to offer a sufficient amount of resistance to increased pressure 
within the air-passages ; as in forced expiration, speaking, singing, blowing, etc. 
The vagus is the motor nerve for these fibres, and according to Longet, the 
“lung-tonus ” during increased tension depends upon these muscles. 
[Contraction of the Lungs and Bronchi—Effect of Nerves.—By connecting the in- 
terior of a small bronchus with an oncograph (§ 103) in curarized dogs (the thorax being 
opened), Brown and Roy found that section of one vagus causes a marked expansion of the 
bronchi of the corresponding lung, while stimulation of the peripheral end of a divided vagus 
causes a powerful contraction of the bronchi of both lungs. Stimulation of the central end of 
one vagus, the other being intact, also causes a contraction (feebler) under the same circum- 
stances. Especially in etherized dogs, expansion and not contraction results. If both vagi be 
divided, no effect is produced by stimulation of the central end of either vagus. It seems plain 
that the vagi contain centripetal or afferent fibres, which can cause both expansion and con- 
traction of the bronchi. Asphyxia causes contraction provided the vagi are intact, but none if 
they are divided, although in etherized dogs expansion frequently occurs, while stimulation of 
the central end of other sensory nerves has very rarely any, or, if any, but a slight, effect on the 
calibre of the bronchi, so that in the dog the only connection between the cerebro-spinal 
centres and the bronchi is through the vagi. Sandmann has confirmed the above observations 
for rabbits and cats, so that it seems certain that the vagus contains some fibres which dilate 
and others which cause contraction of the bronchi. Reflex contraction can be brought about 
by stimulation of the nose and larynx. Williams, Paul Bert, and others showed that the 
bronchi and lungs are contractile when they are stimulated with electricity. This contractility is 
very marked in reptilian lungs where there is a well-marked layer of smooth muscle.] 
Pathological.—Stimulation of the smooth muscles, whereby a spasmodic narrowing of the Sec. 106.] 
PHYSICAL PROPERTIES OF THE LUNGS. 
195 
smaller bronchi is produced, may excite asthmatic attacks. If the expiratory blast be inter- 
fered with, acute emphysema may take place (Biernier). 
Chemistry.—In addition to connective, elastic and muscular tissue, the lungs contain 
lecithin, inosit, uric acid (taurin and leucin in the ox), guanin, xanthin (?), hypoxanthin (dog) 
soda, potash, magnesium, oxide of iron, much phosphoric acid, also chlorine, sulphuric and 
silicic acids—in diabetes sugar occurs—in purulent infiltration glycogen and sugar—in renal 
degeneration urea, oxalic acid, and ammonia salts; and in diseases where decomposition takes 
place, leucin and tyrosin. 
[Physical Properties of the Lungs.—The lungs, in virtue of the large 
amount of elastic tissue which they contain, are highly elastic; and when the 
chest is opened they collapse. 
If a cannula with a small lat- 
eral opening be tied into the 
trachea of a rabbit’s or sheep’s 
lungs, the lungs may be in- 
flated with a pair of bellows, 
or elastic pump. After the 
artificial inflation, the lungs, 
owing to their elasticity, col- 
lapse and expel the greater 
part of the air. As much air 
remains within the light spon- 
gy tissue of the lungs, even 
after they are removed from 
the body, a healthy lung floats 
in water. If the air-cells are 
filled with pathological fluids 
or blood, as in certain dis- 
eased conditions of the lung 
(pneumonia), then the lungs 
or parts thereof may sink in 
water. The lungs of the 
foetus, before respiration has 
taken place, sink in water, 
but after respiration has been 
thoroughly established in the 
child, the lungs float. Hence 
this hydrostatic test is • 
largely used in medico-legal 
cases, as a test of the child’s 
having breathed. If a healthy 
lung be squeezed between the 
fingers, it emits a peculiar 
and characteristic fine crackling sound, owing to the air within the air-cells. 
A similar sound is heard on cutting the vesicular tissue of the lung. The 
color of the lungs varies much ; in a young child it is rose-pink, but after- 
wards it becomes darker, especially in persons living in towns or a smoky 
atmosphere, owing to the deposition of granules of carbon. In coal-miners 
the lungs may become quite black.] 
[Excision of the Lung.—Dogs recover after the excision of one entire lung, and they even 
survive the removal of portions of lung affected with tubercle Biondi).'] 
107. MECHANISM OF RESPIRATION.—The mechanism of re- 
spiration consists in an alternate dilatation and contraction of the chest. The 
dilatation, technically called “expansion,” is called inspiration, the con- 
traction expiration. As the whole external surfaces of both elastic lungs are 
Fig. 154. 
Human lung ( X 50 and reduced ]/z). a, small bronchus; 
b, b, pulmonary artery ; c, pulmonary vein; e, inter- 
lobular septa, continuous with the deep layer of the 
pleura, p. 196 
MECHANISM OF RESPIRATION. 
[Sec. 107. 
applied directly, and in an air-tight manner, by their smooth moist pleural in- 
vestment to the inner wall of the chest, which is covered by the parietal pleura, 
it is clear that the lungs must be distended with every dilatation of the chest, 
and diminished by every contraction thereof. The movements of the 
lungs, therefore, are entirely passive, and are dependent on the thoracic 
movements. 
On account of their complete elasticity and their great extensibility, the 
lungs are able to accommodate themselves to any variation in the size of the 
thoracic cavity, without the two layers of the pleura becoming separated from 
each other. As the capacity of the non-distended chest is greater than the 
volume of the collapsed lungs after their removal from the body, it is clear that 
the lungs, even in their natural position within the chest, are distended, i. e., 
they are in a certain state of elastic tension (§ 60). The tension is greater 
the more distended the thoracic cavity, and vice versd. As soon as the pleural 
cavity is opened by perforation from without, the lungs, in virtue of their elas- 
ticity, collapse, and a space filled with air is formed between the surface of the 
lungs and the inner surface of the thoracic wall (pneumo-thorax). The 
lungs so affected are rendered useless for respiration ; hence a double pneumo- 
thorax causes death. 
Pneumo-thorax.—It is also clear that if the pulmonary pleura be perforated from within 
the lung, air will pass from the respiratory passages into the pleural sac, and also give rise to 
pneumo-thorax. [Not unfrequently the surgeon is called on to open the chest, say by removing 
a portion of a rib to allow of the free exit of pus from the pleural cavity. If this be done with 
proper precautions, and if the external wound be allowed to heal, after a time the air in the 
pleural cavity becomes absorbed, the collapsed lung tends to regain its original form, and again 
becomes functionally active.] 
Estimation of Elastic Tension.—If a manometer be introduced through an intercostal 
space into the pleural cavity in a dead subject, we can measure, by means of a column of mer- 
cury, the amount of the elastic tension required to keep the lung in its position. This is equal 
to 6 mm. Hg. in the dead subject, as well as in the condition of expiration. If, however, the 
thorax be brought into the position of inspiration by the application of traction from without, 
the elastic tension may be increased to 30 mm. Hg. (Bonders). 
If the glottis be closed and a deep inspiration taken, the air within the 
lungs must become rarefied, because it has to fill a greater space. If the glottis 
be suddenly opened, the atmospheric air passes into the lungs until the air 
within the lungs has the same density as the atmosphere. Conversely, if the 
glottis be closed, and if an expiratory effort be made, the air within the chest 
must be compressed. If the glottis be suddenly opened, air passes out of the 
lungs until the pressure outside and inside the lung is equal. As the glottis 
remains open during ordinary respiration, the equilibration of the pressure 
within and without the lungs will take place gradually. During tranquil inspi- 
ration there is a slight negative pressure ; during expiration a slight positive 
pressure, in the lungs; the former = 1 mm., the latter 2-3 mm. Hg. in the 
human trachea (measured in cases of wounds of the trachea). According to 
J. R. Ewald, however, the values are only 0.1 and 0.13 mm. Hg. respectively. 
108. QUANTITY OF GASES RESPIRED. —As the lungs within 
the chest never give out all the air they contain, it follows that only a part of 
the air of the lungs is changed during inspiration and expiration. The volume 
of this air will depend upon the depth of the respirations. 
Hutchinson defined the following:— 
(1) Residual air is the volume of air which remains in the chest after the most complete 
expiration. It is = 1230-1640 c.c. [100-130 cubic inches], 
(2) Reserve or supplemental air is the volume of air which can be expelled from the 
chest after a normal quiet expiration. It is = 1240-1800 c.c. [100 cubic inches]. 
(3) Tidal air is the volume of air which is taken in and given out at each respiration. It 
is = 500 cubic centimetres [20 cubic inches. Sometimes it is stated to be 25-30 cubic inches.] Sec. 108.] 
ESTIMATION OF VITAL CAPACITY. 
(4) Complemental air is the volume of air that can be forcibly inspired over and above 
what is taken in at a normal respiration. It amounts to about 
1500 c.c. [100-130 cubic inches], 
(5) Vital Capacity is the term applied to the vol- 
ume of air which can be forcibly expelled from the 
chest after the deepest possible inspiration. It is equal 
to 3772 c.c. (or 230 cubic inches) for an Englishman 
(Hutchinson), and 3222 for a German (Haeser). 
Hence, after every quiet inspiration, both lungs con- 
tain (1 -j- 2 -j- 3) = 3000 to 3900 c.cm. [220 cubic 
inches] ; after a quiet expiration (1 —J— 2) = 2500 to 
3400 c.cm. [200 cubic inches]. So that about jf to \ 
of the air in the lungs is subject to renewal at each ordinary respiration. 
[It is important to remember that the lungs, even after the deepest expira- 
tion, always contain a large amount of air. In this way the diffusion of gases 
between the air in the lungs and the blood- 
gases can go on continuously, with increase of 
the process at every inspiration.] 
Donders calculated that the entire bronchial system 
and the trachea contain about 500 c.c. of air. 
Estimation of Vital Capacity.—This 
was formerly thought to be of great utility, 
but at the present time not much importance 
is attached to it, nor is it frequently measured 
in cases of disease. It is estimated by means 
of the spirometer of Hutchinson which con- 
sists of a graduated cylinder filled with water 
and inverted like a gasometer over water, and 
balanced by means of a counterpoise (fig. 155). 
Into the cylinder a tube projects, and this tube 
is connected with a mouthpiece. The person 
to be experimented upon takes the deepest 
possible inspiration, closes his nostrils, and 
breathes forcibly into the mouthpiece of the 
tube. After doing so the tube is closed. The 
cylinder is raised by the air forced into it, and 
after the water inside and outside the cylinder 
is equalized, the height to which the cylinder 
is raised indicates the amount of air expired, or the vital or respiratory capacity. 
In a man of average height, 5 feet 8 inches, it is equal to 230 cubic inches. 
The following circumstances affect the vital capacity: — 
(1) The Height.—Every inch added to the height of persons between 5 and 6 feet gives an 
increase of the vital capacity = 130 c.c. [8 cubic inches], 
(2) Body-weight.—When the body-weight exceeds the normal by 7 per cent, there is a 
diminution of 37 c.c. of the vital capacity for every kilo, of increase. 
(3) Age.—The vital capacity is at its maximum at 35; there is an annual decrease of 23.4 
c.c. from this age onwards to 65, and backwards to 15 years of age. 
(4) Sex.—It is less in women than men, and even where there is the same circumference of 
chest, and the same height in a man and a woman, the ratio is 10:7. 
(5) Position and Occupation.—More air is respired in the erect than in the recumbent 
position. In the following three categories the preceding group has a vital capacity greater by 
200 c.c. than the one following it: (a) soldiers and sailors; (<5) hand-workers, compositors; (r) 
paupers, officials, students (Arnold'). 
(6) Disease.—Abdominal and thoracic diseases diminish it. 
109. NUMBER OF RESPIRATIONS.—In the adult, the number 
of respirations varies from 16 to 24 per minute, so that about 4 pulse-beats 
RESPIRATORY CAPACITY 
230 cubic inches. 
COMPLEMENTAL 
AIR 
IIO 
TIDAL AIR 
20 
RESERVE AIR 
IOO 
RESIDUAL AIR 
IOO 
Scheme of Hutchinson’s spirometer. 
Fig- 155- 198 
CONDITIONS INFLUENCING RESPIRATION. 
[Sec. iog. 
occur during each respiration. The number of respirations is influenced by 
many conditions:— 
(1) The Position of the Body.—In the adult, in the horizontal position, Guy counted 13, 
while sitting 19, while standing 22, respirations per minute. 
(2) Age.—Quetelet found the mean number of respirations in 300 individuals to be :— 
Year. Respirations. 
O to X, 44 
5, 26 
15 to 20, 20 
Average 
Number per 
Minute. 
Year. Respirations. 
20 to 50, 187 
25 to 30, 16 
30 to 35, 181 
* 
Average 
Number per 
Minute. 
(3) The State of Activity.—Gorham counted in children of 2 to 4 years of age during 
standing 32, in sleep 24, respirations per minute. During bodily exertion the number of respi- 
rations increases before the heart-beats. [Very slight muscular exertion suffices to increase the 
frequency of the respirations.] 
[(4) The Temperature of the surrounding medium. — The respirations become more 
numerous the higher the surrounding temperature, but this result only occurs when the actual 
temperature of the blood is increased, as in fever. 
(5) Digestion.—There is a slight variation during the course of the day, the increase being 
most marked after mid-day dinner (Vierordt). 
(6) The Will can to a certain extent modify the number and also the depth of the respira- 
tions, but after a short time the impulse to respire overcomes the voluntary impulse. 
(7) The Gases of the Blood have a marked effect, and so has the heat of the blood in fever.] 
[(8) In Animals— 
Mammals. 
Per Min. 
Tiger, 6 
Lion, 10 
Jaguar, .... 11 
Panther, .... 18 
Cat, 24 
Dog, 15 
Dromedary, . . 11 
Giraffe, .... 8-10 
Ox, 15-18 
Squirrel, .... 70 
Per Min. 
Rabbit, .... 55 
Rat (waking), . 210 
Rat (asleep), . . 100 
Rhinoceros, . . 6-10 
Hippopotamus, . 1 
Horse, .... 10-12 
Ass, ..... 70 
Birds. 
Condor, .... 6 
Sparrow,.... 90 
Per Min. 
Pigeon, .... 30 
Siskin, IOO 
Canary, .... 18 
Reptiles. 
Snake, 5 
Tortoise,. ... 12 
Fish. 
Raja, 50 
Torpedo, ... 51 
Per Min. 
Perch,..... 30 
Mullet, . . .60 
Eel, 50 
Hippocampus, . 33 
Invertebrata. 
Crab, 12 
Mollusca, . . 14-16 
(/’. Bert.)-] 
A 
B 
Fig. 156. 
A, Brondgeest’s tambour for registering the respiratory movements, b, c, inner and outer 
caoutchouc membranes; a, the capsule; d, d, cords for fastening the instrument to the 
chest; S, tube to the recording tambour. B, normal respiratory curve obtained on a vibrat- 
ing plate [each vibration = 0.01613 sec.]. Sec. 109.] 
RELATIVE DURATION OF RESPIRATORY MOVEMENTS. 
[(9) In Disease.—The number may be greatly increased from many causes, e.g., in fever, 
pleurisy and pneumonia, some heart diseases, or in certain cases of alteration of the blood, as in 
anaemia ; and diminished where there is pressure on the respiratory centre in the medulla in 
coma. It is important to note the ratio of pulse-beats to respirations.] 
no. TIME OCCUPIED BY THE RESPIRATORY MOVE- 
MENTS.—The time occupied in the various phases of a respiration can only 
be accurately ascertained by obtaining a curve or pneumatogram of the 
respiratory movements by means of recording apparatus. 
Methods.—The graphic method can be employed in three directions :—(i) 
To record the movements of individual parts of the chest-wall. 
(1) Vierordt and C. Ludwig transferred the movements of a part of the chest-wall to a lever 
which inscribed its movements upon a revolving cylinder. Riegel (1873) constructed a 
“ double-stethograph ” on the same principle. This instrument is so arranged that one arm 
of the lever may be applied in connection with the healthy side of a person’s chest, and the 
other on the diseased side. In 
the case of animals placed on 
their backs, Snellon introduced 
a long needle vertically through 
the abdominal walls into the 
liver. Rosenthal opened the 
abdomen and applied a lever to 
the under surface of the dia- 
phragm, and thus registered its 
movements (Phrenograph). 
(2) An air-tambour, such as is 
used in Brondgeest’s pansphyg- 
mograph (fig. 156, A), may be 
employed. It consists of a brass 
vessel, a, shaped like a small 
saucer. The mouth of the brass 
vessel is covered with a double 
layer of caoutchouc membrane, 
b, c, and air is forced in between 
the two layers until the external 
membrane bulges outwards. 
This is placed on the chest, and 
the apparatus is fixed in position 
by means of the bands, d, d. The cavity of the tambour communicates by means of a caoutchouc 
tube, s, with a recording tambour, which inscribes its movements upon a revolving cylinder. 
Every dilatation of the chest compresses the membrane, and thus the air within the tambour is 
also compressed. [A somewhat similar apparatus is used by Burdon-Sanderson, and called a 
“ recording-stethograph.” By it movements of the corresponding points on opposite sides 
of the chest can be investigated.] A cannula or oesophageal sound may be introduced into 
that portion of the oesophagus which lies in the chest, and a connection established with Marey’s 
tambour (Rosenthal). [This method also enables one to measure the intrathoracicpressure 
(p. 214).] 
Marey’s Stethograph or Pneumograph.— [There are two forms of this instrument, one 
modified by P. Bert and the more modern form (fig. 157). A tambour (h) is fixed at right 
angles to a thin elastic plate of steel (/). The aluminium disc on the caoutchouc of the tambour 
is attached to an upright (b), whose end lies in contact with a horizontal screw (g). Two arms 
(d, <r) are attached to opposite sides of the steel plate, and to them the belt (<?) which fastens 
the instrument to the chest is attached. When the chest expands, these two arms are pulled 
asunder, the steel plate is bent, and the tambour is affected, and any movement of the tambour 
is transmitted to a registering tambour by the air in the tube (a).] 
Movements of the Diaphragm.—[The phases of respiration have been studied in animals 
by Kronecker and Marckwald by inserting the spoon-shaped end of a probe-like instrument 
through the abdominal wall, and between the liver and the diaphragm. From the pointed end 
of this instrument a thread passes over a pulley to be attached to a lever recording its movements 
on a drum.] 
(2) To record variation in volume of the thorax or of the respired 
gases. 
For this purpose E. Hering secures the animal, and places it in a tight box provided with two 
Marey’s stethograph. 
Fig- 157- 200 
THE DURATION AND TYPE OF RESPIRATION. 
[Sec. no. 
openings in its side; one hole contains a tube, which is connected to a cannula tied into the 
transversely divided trachea of the animal, so that respiration can go on undisturbed. In the 
other orifice is fixed a water-manometer provided with a swimmer arranged to write on a 
recording surface. Gad registers graphically the respired air by means of a special apparatus, 
the sero-plethysmograph; the expired air raises a very light and carefully equipoised box 
placed over water. As it is raised, it moves a writing style. During inspiration the box sinks. 
(3) To record the rate at which the respiratory gases are ex- 
changed. 
If the trachea of an animal, or the mouth of a man (the nostrils being closed), be connected 
with a tube like that of the dromograph (fig. 156), then during inspiration and expiration the 
pendulum will be moved to and fro by the air, and the movements of the pendulum can be 
registered. [Some years ago an instrument, called the “ Anapnograph,” was constructed on 
this principle.] 
The curve (fig. 156, B) was obtained by placing the tambour of a Brondgeest’s 
pansphygmograph upon the xiphoid process, and recording the movement upon 
a plate attached to a vibrating tuning-fork. The inspiration (ascending limb) 
begins with moderate rapidity, is accelerated in the middle, and towards the 
end again becomes slower. The expiration also begins with moderate rapidity, 
is then accelerated, and becomes much slower at the latter part, so that the 
curve falls very gradually. 
Inspiration is slightly shorter than Expiration.—According to Sib- 
son, the ratio for an adult is as 6 to 7 ; in women, children and old people, 6 
to 8 or 6 to 9. Vierordt found the ratio to be 10 to 14.1 (to 24.1); J. R. 
Ewald, 11 to 12. [For all practical purposes the following represents the 
ratio:— 
Inspiration : Expiration : : 5 : 6.] 
It is only occasionally that cases occur where inspiration and expiration are 
equally long, or where expiration is shorter than inspiration. When respiration 
proceeds quietly and regularly, there is usually no pause (complete rest of the 
chest-walls) between the inspiration and expiration. The very flat part of the 
expiratory curve has been wrongly regarded as due to a pause. Of course, we 
may make a voluntary pause between two respirations, or at any part of a respi- 
ratory act. 
Some observers, however, have described a pause as occurring between the end of expiration 
and the beginning of the next inspiration (expiration pause), and also another pause at the end 
of inspiration (inspiration pause). The latter is always of very short duration, and considerably 
shorter than the former. During very deep and slow respiration, there is usually an expiration 
pause, while it is almost invariably absent during rapid breathing. An inspiration pause is always 
absent under normal circumstances, but it may occur under pathological conditions. 
In certain parts of the respiratory curve slight irregularities may appear, which are sometimes 
due to vibrations communicated to the thoracic walls by vigorous heart-beats (fig. 158). 
The “type of respiration’’ may be ascertained by taking curves from 
various parts during the respiratory movements. Hutchinson showed that, in 
the female, the thorax is dilated chiefly by raising the sternum and the ribs 
(Respiratio costalis), while in man it is caused chiefly by a descent of the dia- 
phragm (Respiratio diaphragmatica or abdominalis). In the former there is 
the so-called “costal type,” in the latter the “diaphragmatic or abdom- 
inal type.” 
This difference in the type of respiration in the sexes occurs only during normal quiet respira- 
tion. During deep and forced respiration, in both sexes the dilatation of the chest is caused 
chiefly by raising the chest and the ribs. In man, the epigastrium may be pulled in sooner than 
it is protruded. During sleep, the type of respiration in both sexes is thoracic, while at the 
same time the inspiratory dilatation of the chest precedes the elevation of the abdominal wall 
(A/osso). It is not determined whether the costal type of respiration in the female depends upon 
the constriction of the chest by corsets or other causes (Sibson), or whether it is a natural adap- 
tation to the child-bearing function in women (Hutchinson). Some observers maintain that the 
difference of type is quite distinct, even in sleep, when all constrictions are removed; and that Sec. IIO.] 
RHYTHM OF RESPIRATION. 
similar differences are noticeable in young children. This is denied by others, while a third 
class of observers hold that the costal type occurs in children of both sexes, and they ascribe as 
a cause the greater flexibility of the ribs of children and women, which permits the muscles of 
the chest to act more efficiently upon the ribs. 
hi. PATHOLOGICAL.—[Examination of the Lungs.—The same methods that 
are applicable to the heart apply here also, viz. — 
I. Inspection (including Mensuration). 
II. Palpation (including vocal fremitus). 
III. Percussion (including sense of resistance); and 
IV. Auscultation (including vocal resonance).] 
[By inspection we may determine the presence of symmetrical or unilateral alterations in 
the shape of the chest, the presence of bulging or flattening at one part, and variations in the 
movement of the chest-walls. By palpation, the presence or absence, character, seat, and ex- 
tent of any movements are more carefully examined. But we may also study what is called 
vocal fremitus (§ 117), Percussion (g 114), Auscultation (§ 116).] 
Pneumatograms obtained by means of Riegel’s stethograph. I, normal curves; II, curve from 
a case of emphysema; a, ascending limb; b, apex ; c, descending limb of the curve. The 
small elevations are due to the cardiac impulse. 
Fig. 158. 
[In investigating the respiratory movements, we should observe (i), the frequency (§ 109); 
(2), the type ($ no); (3), the nature, character and extent of the movements, noting also 
whether they are accompanied by pain or not ($ Iio); (4), the rhythm.] 
I. Changes in the mode of Movement.—In persons suffering from disease of the respira- 
tory organs, the dilatation of the chest may be diminished (to the extent of 5 or 6 cm.) on both 
sides or only on one side. In affections of the apex of the lung (in phthisis), the sub-normal 
expansion of the upper part of the wall of the chest may be considerable. Retraction of the 
soft parts of the thoracic wall, the xiphoid process, and the parts where the lower ribs are in- 
serted. occurs in cases where air cannot freely enter the chest during inspiration, e.g., in narrow- 
ing of the larynx; when this retraction is confined to the upper part of the thoracic wall, it 
indicates that the portion of the lung lying under the part so affected is less extensile and diseased. 
Harrison’s Groove.—In persons suffering from chronic difficulty of breathing, and in whom, 
at the same time, the diaphragm acts energetically, there is a slight groove, which passes hori- 
zontally outwards from the xiphoid cartilage, caused by the pulling in of the soft parts and cor- 
responding to the insertion of the diaphragm. 202 
DYSPNCEA AND MODIFIED RESPIRATORY MOVEMENTS. 
[Sec. hi. 
The duration of inspiration is lengthenedi in persons suffering from narrowing of the 
trachea or larynx; expiration is lengthened in cases of dilatation of the lung, as in emphysema, 
where all the expiratory muscles must be brought into action (fig. 158. II). 
II. Variations in the Rhythm.—When the respiratory apparatus is much affected, there 
is either an increase or a deepening of the respirations, or both. When there is great difficulty 
of breathing, this is called dyspnoea. 
Causes of Dyspnoea.—(1) Limitation of the exchange of the respiratory gases in the blood 
due to—(a) diminution of the respiratory surface fas in some diseases of the lungs); (b) nar- 
rowing of the respiratory passages, [when a child sucks, it breathes exclusively through the 
nose, hence catarrhal conditions of the nasal mucous membrane are fraught with danger to the 
child; (0) diminution of the red blood-corpuscles; (d) disturbances of the respiratory mech- 
anism, (e. g., due to affections of the respiratory muscles or nerves, or painful affections of the 
chest-wall); (e) impeded circulation through the lungs due to various forms of heart disease. (2) 
Heat-dyspncea.—The frequency of the respirations is in febrile conditions. The 
warm blood acts as a direct irritant of the respiratory centre in the medulla oblongata, and 
raises the number of respirations to 30-60 per minute (“ Heat-dyspncea ”). If the carotids be 
placed in warm tubes, so as to heat the blood going to the medulla oblongata, the same 
phenomena are produced (§ 368).] 
[Orthopncea.—Sometimes the difficulty of breathing is so great that the person can only 
respire in the erect position, i. e., when he sits or is propped up in bed. This occurs frequently 
towards the close of some heart affections, notably in mitral lesions; dropsical conditions, espe- 
cially of the cavities, may be present.] 
Cheyne-Stokes’ Phenomenon.—This remarkable phenomenon occurs in certain diseases, 
where the normal supply of blood to the brain is altered, or where the quality of the blood itself 
is altered, e. g., in certain affections of the brain and heart, and in uraemic poisoning. Respira- 
Fig. 159. 
Tracing of Cheyne-Stokes’ breathing ( Gibson). 
tory pauses of one-half to three-quarters of a minute alternate with a short period min.) 
of increased respiratory activity, and during this time 20-30 respirations occur. The respira- 
tions constituting this “ series” are shallow at first; gradually they become deeper and deeper, 
and finally become shallow or superficial again. Then follows the pause, and thus there is an 
alternation of pauses and series (or groups) of modified respirations. 
[Fig. 159 shows a tracing of the respiratory movements. The increase from 
shallow to deeper respirations is sometimes called the “ ascending phase,” and 
the reverse the “descending phase.” As will be seen, the pause occupies 
somewhat less than the half of one period. Dixon Mann has recorded a case 
where this phenomenon lasted for more than a year.] During the pause, the 
pupils are contracted and inactive; and when the respirations begin, they dilate 
and become sensible to light; the eyeball is moved as a whole at the same time. 
[Mann found that the pupils did not contract during the pause, nor was there 
any change in their size on the return of breathing.] Hein observed that 
consciousness was abolished during the pause, and that it returned when respi- 
ration commenced. 
Causes.—Luciani and Rosenbach regard variations in the excitability of the respiratory 
centre as the cause of the phenomenon, which they compare with the periodic contraction of the 
heart (§ 58). The excitability of the respiratory centre is lowest during the pause. They ob- 
served this phenomenon after injury to the medulla oblongata above the respiratory centre, and 
after apnoea produced in animals deeply narcotized with opium, and in the last stages of asphyxia, 
during respiration in a closed space. During hibernation, this mode of respiration is normal 
in Myoxus, the hedgehog, and the caiman. Sec. III.] 
MUSCLES OF INSPIRATION. 
203 
Periodic Respiration.—If frogs be kept under water, or if the aorta be clamped, after 
several hours they become passive. If they be taken out of the water, or if the clamp be re- 
moved from the aorta, they gradually recover and always exhibit the Cheyne-Stokes’ phenome- 
non. In such frogs the blood-current may be arrested temporarily, while the phenomenon itself 
remains (Sokolow and Luchsinger). If the blood-current be arrested by ligature of the aorta, 
or if the frogs be bled, the respirations occur in groups. This is followed by a few single respi- 
rations, and then the respiration ceases completely. During the pause between the periods, 
mechanical stimulation of the skin causes the discharge of a group of respirations (Siebert and 
Langendorff). 
Action of Drugs.—Muscarin, digitalin, curare, chloral, sulphuretted hydrogen, and the poison 
of many infectious diseases (typhus, diphtheria, scarlet fever) may also cause periodic respiration 
[which is not due to the action of these drugs on the heart]. 
Periodic respiration without any variation in the size of the individual respirations—the so- 
called “ Biot’s respiration ”—occurs normally during sleep. While the nervous system as it 
were strives to rest, and thus forgets the respiration, the organism does not observe the short 
pauses (Mosso). [There is a periodic increase or decrease in the depth of the respiration, espe- 
cially in old people and children, even to the extent of the respiration becoming “ remittent,” or 
even “ intermittent,” for a period of 30 sec. during sleep. During periodic respiration the action 
of the several respiratory muscles does not coincide. As a rule, one respires more than is required 
by the organism. Mosso calls this “ luxus-respiration.”] Periodic irregularities in the respi- 
ration are often of reflex origin [Knoll). 
112. GENERAL VIEW OF THE RESPIRATORY MUSCLES. 
(A) Inspiration. 
I. During Ordinary Inspiration. 
1. The diaphragm (.Nervus phrenicus). 
2. The Mm. levatores costarum longi et breves (.Rami-posteriores Nn. dorsa- 
Hum). 
3. The Mm. intercostales externi et intercartilaginei (Nn. intercostales). 
[Ordinary inspiration, therefore, is both diaphragmatic and costal, i. e., it is 
essentially a muscular act brought about under the influence of the central ner- 
vous system, by a series of co-ordinated muscular movements. The diaphragm 
contracts, and the ribs are raised, at least all except the first. The ribs are raised 
by the levatores costarum, and the external and internal intercostal muscles (p. 
206).] 
II. During Forced Inspiration. 
(a) Muscles of the Trunk. 
1. The three Mm. scaleni (Rami musculares of the plexus cervicalis et bra- 
chialis). 
2. M. sternocleidomastoideus (Ram. externus N. accessorii). 
3. M. trapezius (R. externus N. accessorii et Ram. musculares plexus cervi- 
calis). 
4. M. pectoralis minor (Nn. thoracici anterior es). 
5. M. serratus posticus superior (N. dorsalis scapulce). 
6. Mm. rhomboidei (N. dorsalis scapulce). 
7. Mm. extensores columnae vertebralis (Ram. posteriores nervorum dorsa- 
liuni). 
[8. Mm. serratus anticus major (N. thoracicus longus).1L\ 
(b) Muscles of the Larynx. 
1. M. sternohyoideus (Ram. descendens hypoglossi). 
2. M. sternothyreoideus (Ram. descendens hypoglossi). 
3. M. crico-arytaenoideus posticus (N laryngeus inferior vagi). 
4. M. thyreo-arytaenoideus (N. laryngeus inferior vagi). 204 
CAUSES OF EXPIRATORY MOVEMENTS. 
[Sec. 112. 
{c) Muscles of the Face. 
1. M. dilatator narium anterior et posterior {N. facialis). 
2. M. levator alae nasi {N. facialis). 
3. The dilators of the mouth and nares, during forced respiration, [“ gasping 
for breath”] {N. facialis). 
(d) Muscles of the Pharynx. 
1. M. levator veli palatini {N. facialis). 
2. M. azygos uvulae {N. facialis). 
3. According to Garland, the pharynx is always narrowed. 
[Or, classified according to their action, the auxiliary muscles of forced 
inspiration are those that elevate the ribs directly or indirectly, or fix the 
lower jaw, so that muscles attached to the hyoid bone can act {Rutherford). 
Mylo-hyoid. 
Genio-hyoid. 
Stylo-hyoid. 
Digastric. 
The hyoid bone is raised by 
Stern o-mastoid. 
Sterno-hyoid. 
Sterno-thyroid. 
Thyro-hyoid. 
The sternum is raised by 
Scaleni: 
Cervicalis ascendens. 
Serratus posticus superior. 
The upper ribs are raised by 
Trapezius. 
Levator anguli scapulae. 
Rhomboideus major. 
“ minor. 
The shoulder girdle is raised and 
drawn backwards by 
Pectoralis major. 
“ minor. 
Subclavius. 
Serratus magnus.] 
The following muscles pull on the ribs 
and tend to approach them to the raised 
shoulder girdle:— 
(B) Expiration. 
I. During Ordinary Respiration. 
The thoracic cavity is diminished by the weight of the chest-wall, the elas- 
ticity of the lungs, costal cartilages, and abdominal wall and abdominal .contents. 
[Ordinary expiration, therefore, is non-muscular, and the act is a purely 
passive one.] 
II. During Forced Respiration. 
The A bdominal Muscles. 
1. The abdominal muscles [including the obliquus externus and interims, 
and transversalis abdominis] {Nn. abdominis internis anteriores e nervis inter- 
costalibus, 8-12). 
2. Mm. intercostales interni, so far as they lie between the osseous parts of 
the ribs, and the Mm. infracostales {Nn. intercostales). 
3. M. triangularis sterni {Nn. intercostales'). 
4. M. serratus posticus inferior {Ram. externi nerv. dorsalium). 
5. M. quadratus lumborum {Ram. muscular e plexu lumbali). 
6. Rectus abdominis {Nn. intercostales, 7-12). 
7. Levator ani {Nn. sacrales, 3-4). Sec. 112.] 
THE ACTION OF THE DIAPHRAGM. 
Obliquus externus. 
“ internus, 
Transversus abdominis. 
Levator ani. 
Rectus abdominis. 
205 
[ The abdominal contents are compressed 
and forced against the diaphragm by 
Rectus abdominis. 
Quadratus lumborum. 
Sarratus posticus inferior. 
Triangularis sterni.] 
The ribs are depressed by 
113- ACTION OF THE INDIVIDUAL RESPIRATORY MUSCLES. —(A) 
Inspiration.—(i) The Diaphragm arises from the cartilages and the adjoining osseous parts 
of the lower six ribs (costal portion), by two thick 
processes or crura, from the upper three or four 
lumbar vertebrae, and a sternal portion from the 
back of the ensiform process. It represents an 
arched double cupola or dome-shaped partition, 
directed towards the chest; in the larger concavity 
on the right side lies the liver, while the smaller 
arch on the left side is occupied by the spleen and 
stomach. During the passive condition, these viscera 
are pressed against the under surface of the dia- 
phragm by the elasticity of the abdominal walls, and 
by the intra-abdominal pressure, so that the arch of 
the diaphragm is pressed upwards into the chest. 
The elastic traction of the lungs also aids in pro- 
ducing this result. The greater part of the upper 
surface of the central tendon of the diaphragm is 
united to the pericardium. The part on which the 
heart rests, and which is perforated by the inferior 
vena cava (foramen quadrilaterum) is the deepest 
part of the middle portion of the diaphragm during 
the passive condition. 
Action of the Diaphragm.—When 
the diaphragm contracts, both arched por- 
tions become flatter, and the chest is thereby 
elongated from above downwards. In this 
act, the lateral muscular parts of the dia- 
phragm pass from an arched condition into 
a flatter form (fig. 160), and during a forced 
inspiration the lowest lateral portions, 
which during rest are in contact with the 
chest-wall, become separated from it. The 
middle of the central tendon where the 
heart rests (fixed by means of the pericardium and inferior vena cava), takes 
no share in this movement, especially in ordinary quiet breathing, but during 
the deepest inspiration it sinks somewhat. 
Undoubtedly, the diaphragm is the most powerful agent in increasing the cavity of the chest. 
Briicke believes that in addition to increasing the length of the thoracic cavity from above down- 
wards, it also increases the transverse diameter of the lower part of the chest. It presses upon 
the abdominal viscera from above, and strives to press these outwards, thus tending to push out 
the adjoining thoracic wall. If the contents of the abdomen are removed from a living animal, 
every time the diaphragm contracts the ribs are drawn inwards. This, of course, hinders the 
chest from becoming wider below, hence the presence of the abdominal viscera seems to be 
necessary for the normal activity of the diaphragm. Every contraction of the diaphragm, by 
increasing the intra-abdominal pressure, favors the venous blood-current in the abdomen towards 
the vena cava inferior. 
Phrenic Nerve.—The immense importance of the diaphragm as (he great inspiratory muscle 
is proved by the fact that, after both phrenic nerves (third and fourth cervical nerves) are 
divided, death occurs in some animals. [In animals where the intercostal muscles play a large 
Fig. 160. 
Sagittal section through the second rib on 
the right side. When the arched mus- 
cular part of the diaphragm contracts, a 
wedge-shaped space, with its apex down- 
wards, is formed around the circumfer- 
ence of the lower part of the chest. 206 
THE ACTION OF THE INTERCOSTAL MUSCLES. 
[Sec. 113. 
part in the act of inspiration, as in the dog, section of these nerves does not produce death 
rapidly.] The phrenic nerve contains some sensory fibres for the pleura, pericardium, and a 
portion of the diaphragm. [Ganglionic cells have been found in the course of the inter muscular 
fibres of the phrenics.] The contraction of the diaphragm is not to be regarded as a “ simple 
muscular contraction,” since it lasts 4 to 8 times longer than a simple contraction; it is rather a 
short tetanic contraction, which we may arrest in any stage of its activity, without bringing into 
action any antagonistic muscles (.Kronecker and Marckwald). 
(2) The Elevation of the Ribs.—The ribs at their vertebral ends (which lie much higher 
than their sternal ends) are united by means of joints by their heads and tubercles to the bodies 
and transverse processes of the vertebrae. A horizontal axis can be drawn through both joints, 
around which the ribs can rotate upwards and downwards. If the axis of rotation of each pair 
of ribs be prolonged on both sides until they meet ir\the middle line, the angles so formed are 
greatest above (125°), and smallest below (88°). Owing to the ribs being curved, we can imagine 
a plane which, in the passive (expiratory) condition of the chest, has a slope from behind and 
inwards to the front and outwards. If the ribs move on their axis of rotation, this plane becomes 
more horizontal, and the thoracic cavity is increased in its transverse diameter. As the axis of 
rotation of the upper ribs runs in a more frontal, and that of the lower ribs in a more sagittal 
direction, the elevation of the upper ribs causes a greater increase from before backwards, and 
the lower ribs from within outwards (as the movements of ribs which are directed downwards are 
vertical to the axis). The costal cartilages undergo a slight tension at the same time, which 
brings their elasticity into play. 
Changes in the Chest.—All inspiratory muscles which act directly 
upon the chest-wall do so Upraising the ribs :—(a) When the ribs are raised, 
the intercostal spaces are widened, (b) When the upper ribs are raised, all the 
lower ribs and the sternum must be elevated at the same time, because all the 
ribs are connected with each other by means of the soft parts of the intercostal 
spaces. (V) During inspiration, there is an elevation of the ribs and a dilatation 
of the intercostal spaces. (The lowest rib is an exception : during forced 
respiration, at least, it is drawn downwards.) (d) If, on a preparation of the 
chest, the ribs be raised as in inspiration, we may regard all those muscles as 
elevators of the ribs, whose origin and insertion become approximated. 
Every one is agreed that the scaleni and levatores costarum longi et breves, the 
serratusposticus superior, are inspiratory muscles. These are the most impor- 
tant inspiratory muscles which act upon the ribs. 
Intercostal Muscles.—With regard to the action of the intercostal muscles, 
there is a great difference of opinion. According to the above experiment, the 
external intercostals and the inter-cartilaginous parts of the internal intercostals 
act as inspiratory muscles, whilst the remaining portions of the internal inter- 
costals (as far as they are covered by the external) are elongated when the ribs 
are raised, while they shorten when the chest-wall descends. A muscle shortens 
only during its activity. The internal intercostals were regarded by Hamberger 
as depressors of the ribs or expiratory muscles. 
In fig. 161, I, when the rods, a and b (which represent the ribs), are raised, the intercostal 
space must be widened (e fyc d). On the opposite side of the figure, it is evident that when 
the rods are raised, the line g h, is shortened (f k<g h, direction of the external intercostals) l m is 
lengthened (/ w<o n, direction of internal intercostals).* Fig. 161, II, shows, that when the ribs are 
raised, the inter-cartilaginei, indicated by g k, and the external intercostals, indicated by l k, 
are shortened. When the ribs are raised, the position of the muscular fibres is indicated by the 
diagonal of the rhomb becoming shorter. 
The mode of action of the intercostal muscles is an old story, Galen (131-203 A. D.) regarding 
the externals as inspiratory, the internals as expiratory. Hamberger (1727) accepted this 
proposition, and considered the inter-cartilaginei also as inspiratory. Haller looked upon both 
the external and internal intercostals as inspiratory, while Vesalius (1540) regarded both as 
expiratory. Landerer, observing that the upper two or three intercostal spaces became narrower 
during inspiration, regarded both as active during inspiration and expiration. They keep 
one rib attached to the other, so that their action is to transmit any strain put upon them to the 
wall of the chest. On this view they will be in action, even when the distance between their 
points of attachment becomes greater. Landois regards the external intercostals and inter- 
cartilaginei as active only during inspiration, the internal intercostals only during expiration.. 
Martin and Hartwell exposed the internal intercostals, and observed whether they contracted. Sec. 113.] 
THE ACTION OF MUSCLES OF FORCED RESPIRATION. 
207 
along with the diaphragm, or whether the contractions of these two muscles alternate. As the 
result of their experiments, they conclude that “ the internal intercostal muscles are expiratory 
throughout their whole extent, at least in the dog and cat; and that in the former animal they 
are almost ‘ ordinary ’ muscles of respiration, while in the latter they are ‘ extraordinary ’ 
respiratory muscles ”] Landois is of 
opinion that the chief action of these 
muscles is not to raise or depress the 
ribs, but rather that the external inter- 
costals and the inter-cartilaginei offer 
resistance to the inspiratory dilatation 
of the intercostal spaces, and to the 
simultaneously increased elastic tension 
of the lungs. The internal intercostals 
act during powerful expiratory effotts 
(e. g., coughing), and oppose the dis- 
tention of the lungs and chest caused 
by this act. Unless muscles were 
present to resist the uninterrupted ten- 
sion and pressure, the intercostal sub- 
stance would become so distended that 
respiration would be impossible. [Ac- 
cording to Rutherford, the internal in- 
tercostals are probably muscles of in- 
spiration.] 
The Pectoralis minor and 
(? Serratus anticus major) 
can only act as elevators of the 
ribs when the shoulders are 
fixed, partly by the rhomboidei, 
and partly by fixing the shoulder- 
joint and supporting the arms, as 
is done instinctively by persons 
suffering from breathlessness. 
(3) Muscles acting on the 
Sternum, Clavicle, and Vertebral Column.—When the head is fixed by 
the muscles of the neck, the sternocleidomastoid raises the manubrium sterni 
and the sternal end of the clavicle, so that the thorax is raised and thereby 
dilated. The scaleni also aid in this act. The clavicular portion of the trape- 
zius may act in a similar although less energetic manner. When the vertebral 
column is straightened, it causes an elevation of the upper ribs, and a dilatation 
of the intercostal spaces which aid inspiration. During deep respiration, the 
straightening of the vertebral column takes place involuntarily. 
(4) Laryngeal Movements.—During labored respiration, with every 
inspiration, the larynx descends and the glottis is opened. At the same time 
the palate is raised, so as to permit a free passage to the air entering through 
the mouth. 
(5) Facial Movements.—During labored respiration, the facial muscles 
are involved; there is an inspiratory dilatation of the nostrils (well-marked in 
the horse and rabbit). When the need for respiration is very great, the mouth is 
gradually widened, and the person, as it were, gasps for breath. During expira- 
tion, the muscles that are active during (4) and (5) relax, so that a position of 
equilibrium is established without there being any active expiratory movement, 
to counteract the inspiratory movement. During inspiration the pharynx 
becomes narrow ( Garland). 
(B) Expiration.—Ordinary expiration occurs without the aid of 
muscles, owing to the weight of the chest-wall, which tends to fall into 
its normal position from the position to which it was raised during inspiration. 
This is aided by the elasticity of the various parts of the chest. When the 
Scheme of the action of the intercostal muscles. 
Fig. 161. 208 
RELATIVE DIMENSIONS OF CHEST. 
[Sec. 113. 
costal cartilages are raised, which is accompanied by a slight rotation of their 
lower margins from below forwards and upwards, their elasticity is called into 
play. As soon, therefore, as the inspiratory forces cease, the costal cartilages 
return to their normal position, i. e., the position of expiration, and tend to 
untwist themselves ; at the same time, the elasticity of the lungs draws 
upon the thoracic walls and the diaphragm. Lastly, the tense and elastic 
abdominal walls, which, in man chiefly, are stretched and pushed forward, 
tend to return to their non-distended passive condition when the abdominal 
viscera are relieved from the pressure of the contracted diaphragm. (When 
the position of the body is reversed, the action of the weight of the chest is 
removed, but in place of it there is the weight of the viscera, which press 
upon the diaphragm.) 
The abdominal muscles [obliquus internus and externus, rectus abdomi- 
nis, transversalis abdominis and levator ani] are always active during labored 
respiration. They act by diminishing the abdominal cavity, and they press 
the abdominal contents upwards against the diaphragm. When they act simul- 
taneously, the abdominal cavity is diminished throughout its whole extent. 
Cyrtometer curve. Left side of the chest re- 
tracted in a girl aged twelve. 
Fig. 162. 
Fig. 163. 
The triangularis sterni depresses the sternal ends of the united cartilages 
and bones, from the third to sixth ribs downwards; and the serratus pos- 
ticus inferior depresses the lowest four ribs, causing the others to follow. 
It is aided by the quadratus lumborum, which depresses the last rib. Ac- 
cording to Henle, the serratus posticus inferior fixes the lower ribs for the 
action of the slips of the diaphragm inserted into them, so that it acts during 
inspiration. According to Landerer, the downward movement of the ribs in 
the lower part of the thorax dilates the chest. 
In the erect position, when the vertebral column is fixed, deep inspiration and expiration 
naturally alter the position of the centre of gravity, so that during inspiration, owing to the 
protrusion of the thoracic and abdominal walls, the centre of gravity lies somewhat more to 
the front. Hence, with each respiration there is an involuntary balancing of the body. During 
very deep inspiration, the accompanying straightening of the vertebral column and the throwing 
backwards of the head compensate for the protrusion of the anterior walls of the trunk. 
114. RELATIVE DIMENSIONS OF THE CHEST.—The di- 
ameter of the chest is ascertained by means of callipers; the circumference 
with a flexible centimetre or other measure. 
Sibson’s thoracometer. Sec. 114.] 
ANATOMICAL RELATIONS OF THE LUNGS. 
209 
In strong men, the circumference of the upper part of the chest (immedi- 
ately under the arms) is 88 centimetres (34.3 inches), in females 82 centimetres 
(32 inches); at the level of the ensiform process 82 centimetres (32 inches) and 
78 centimetres (30.4 inches) respectively. [In health the chest expands from 
\y2 to 5 inches during forced inspiration.] When the arms are placed hori- 
zontally, during moderate expiration, the circumference immediately under the 
nipple and the angles of the scapulae is equal to half the length of the body; 
in man 82, and during deep inspiration 89 centimetres. The circumference 
at the level of the ensiform cartilage is 6 centimetres less. In old people, the 
circumference of the upper part of the chest is diminished, so that the lower 
part becomes the wider of the two. The right half of the chest is usually 
slightly larger than the left half, owing to the greater development of the 
muscles on that side. The long diameter of the chest—from the clavicle to 
the margin of the lowest rib—varies very much. 
The transverse diameter in man, above and below, is 25 to 26 centime- 
tres (9.7 to 10.1 inches), in females 23 to 24 centimetres (8.9 to 9.2 inches) ; 
above the nipple it is 1 centimetre more. The antero-posterior diameter 
(distance of anterior chest-wall from the tip of a spinous process) in the upper 
part of the chest is = 17 (6.6 inches), in the lower 19 centimetres (7.4 inches). 
Valentin found that in a man, during the deepest inspiration, the chest on a 
level with the groove in the heart was increased about y to while Sibson 
estimates the increase at the level of the nipple to be y1^. 
Thoracometer.—In order to obtain a knowledge of the degree of movement—rising or fall- 
ing—of the chest-wall during respiration, various instruments have been invented. The 
thoracometer (fig. 163) measures the elevation in different parts of the sternum. It consists of 
two metallic bars placed at right angles to each other; one of them, A, is placed on the verte- 
bral column. On B there is placed a movable transverse bar, C, which carries on its free end a 
toothed rod, Z, directed downwards. The lower end of this rod is provided with a pad which 
rests on the sternum, while its toothed edge drives a small wheel, which moves an index, whose 
excursions are indicated on a circle with a scale attached to it. 
The Cyrtometer of Woillez consists of a brass chain of movable links, to be applied in a 
definite direction to part of the chest-wall, e.g., transversely on a level with the nipple, or 
vertically upon the mammillary or axillary lines anteriorly. There are freely movable links at 
two parts, which permit the chain to be easily removed, so that as a whole it still retains its 
form. The chain is laid upon a sheet of paper, and a line drawn with a pencil around its inner 
margin gives the form of the thorax (fig. 162). [Two thin bands of lead united by a leather 
■hinge answers the same purpose.] 
Anatomical Relations and Limits of the Lungs.—The extent and 
boundaries of the lungs are ascertained in the living subject by means of per- 
cussion, which consists in lightly tapping the chest-wall by means of a per- 
cussion-hammer. A small ivory or bone plate or pleximeter, held in the 
left hand, is laid on the chest, and the hammer is made to strike this plate, 
whereby a sound is emitted, which sound varies with the condition of the sub- 
jacent lung-tissue. Whenever the lung-substance in contact with the chest-wall 
contains air, a clear resonant tone or sound—such as is obtained by striking a 
vessel containing air, a clear percussion-sound—is obtained. Where the lung 
does not contain air, a dull sound—like striking a limb—is obtained. If the 
parts containing air be very thin, or only partially filled with air, the sound is 
“ muffled. ” 
Fig. 164 indicates the relation of the lungs to the anterior surface of the 
chest. The apices of the lungs reach 3 to 7 centimetres (1.1 to 2.7 inches) above 
the clavicles anteriorly, while posteriorly they reach as high as the level of the 
seventh spinous process. The lower margin of the right lung in the passive 
position (moderate expiration) of the chest, commences at the right margin of 
the sternum at the insertion of the sixth rib, runs under the right nipple, nearly 
parallel to the upper border of the sixth rib, and descends a little in the axillary [Sec. 114. 
210 
TOPOGRAPHICAL RELATIONS OF THE LUNGS. 
line, to the upper margin of the seventh rib, or even to the eighth rib [and to 
the ninth rib in the scapular line]. On the left side (apart from the position 
of the heart), the lower limit reaches as far down anteriorly as the right. In 
fig. 164 the line a, t, b, shows the lowest limit of the passive lungs. Posteriorly 
both lungs reach as far down as the tenth rib. During the deepest inspiration, 
the lungs descend anteriorly as far as between the sixth and seventh ribs, and 
posteriorly to the eleventh rib—whereby the diaphragm is separated from the 
thoracic wall (fig. 164). During the deepest expiration, the lower margins of 
the lungs are elevated almost as much as they descend during inspiration. In 
fig. 164, m, n indicates the margin of the right lung during deep inspiration ; 
h, l, during deep expiration. [The part of the chest-wall covered by the 
Fig. 164. 
Topography of the lungs and heart, h, l, upward limit of margin of lung during deepest expira- 
tion ; m, n, lower limit during deepest inspiration, t, tf, t", triangular area where the heart 
is uncovered by lung, dull percussion-sound; d, d', d", muffled percussion-sound; i, i\ 
anterior margin of left lung reaches this line during deep inspiration, and during deep 
expiration it recedes as far as <?, e'. 
costal pleura is considerably larger than the circumference of the lung. This is 
specially marked at the lower margin of the lung, and where the left lung is 
incised over the heart. In these regions, during expiration, the surfaces of the 
visceral and parietal pleurae are in contact, but during inspiration they are 
separated, and allow the thin margins of the lung to be insinuated between 
them. This available space is called complemental space, or “ disposable” 
or reserve pleural space by Luschka (fig. 62).] 
It is important to observe the relation of the margin of the left lung to the 
heart. In fig. 164 a somewhat triangular space, reaching from the middle of 
the point of insertion of the fourth rib to the sixth rib on the left side of the 
sternum, is indicated. In the passive chest the anterior surface of the pericar- 
dium lies in contact with the inner surface of the thoracic wall in this triangular Sec. 114.] 
PATHOLOGICAL PERCUSSION-SOUNDS. 
211 
area (§ 56). This area is represented by the triangle t, t', t", and percussion 
over it gives a dull sound (superficial cardiac dulness, p. 89). 
In the area of the larger triangle, d, d', d", where the heart is separated from 
the chest-wall by the thin anterior margins of the lung, percussion gives a 
muffled sound, while further outwards a clear lung percussion-sound is obtained. 
During deep inspiration, the inner margin of the left lung reaches over the 
heart as far as the insertion of the mediastinum, whereby the dull sound is 
limited to the smallest triangle, t, i, i'. Conversely, during very complete 
expiration, the margin of the lung recedes so far that the cardiac dulness em- 
braces the space, t, e, e'. 
[The right lung consists of three lobes, and the left of two. The relations 
of these lobes to the chest-wall are important clinically, and may be tabulated 
as follows, according to Gibson and Russell:— 
Right Lung (3 lobes). 
Anteriorly 
(Mammary line). 
Laterally. 
Posteriorly. 
Upper lobe, 
From apex to 4th or 
To 4th rib. 
From apex to spine of 
5th rib. 
scapula. 
Middle lobe, 
From 4th or 5th rib to 
inferior margin of 
lung. 
From 4th to 6th rib. 
Nil. 
Lower lobe, 
Nil. 
From 6th to 8th rib. 
From spine of scapula to 
loth rib. 
Left Lung (2 lobes). 
Anteriorly 
(Mammary line). 
Laterally. 
Posteriorly. 
Upper lobe, 
From apex to 6th rib. 
To 4th rib. 
From apex to spine of 
scapula. 
Lower lobe, 
Nil. 
From 4th rib to base. 
From spine of scapula to 
base.] 
115- PATHOLOGICAL PERCUSSION-SOUNDS.—Abnormal Dulness.—'The 
normal clear resonant percussion-sound of the lungs becomes muffled when infiltration takes 
place into the lungs, so as to diminish the normal amount of air within them, or when the lungs 
are compressed from without, e. g., by effusion of fluid into the pleura. The percussion-sound 
becomes clearer when the chest-wall is very thin, as in spare individuals, during very deep in- 
spiration, and especially in emphysema, where the air-vesicles of certain parts of the lung (apices 
and margins) become greatly dilated. 
The pitch of the percussion-sound ought also to be noted. It depends upon the greater or 
less tension of the elastic pulmonary tissue, and on the elasticity of the thoracic wall. The 
tension of the elastic tissue is increased during inspiration and diminished during expiration, so 
that even under physiological conditions the pitch of the sound varies. 
The sound is said to be tympanitic when it has a musical quality resembling in its timbre 
the sound produced on drums, and when it has a slight variation in pitch, if a caoutchouc 
ball be placed near the ear, on tapping it gently, a well-marked tympanitic sound is heard, and 
the sound is of higher pitch the smaller the diameter of the ball. A tympanitic sound is 
always produced on tapping the trachea in the neck. A tympanitic sound produced over the 
chest is always indicative of a diseased condition. It occurs in cases of cavities or vomicae within 
the substance of the lung (the sound becomes deeper when the mouth, or better, the mouth 
and nose, are closed), when air is present in one pleural cavity, as well as in conditions where 
the tension of the pulmonary tissues is diminished. The tympanitic sound resembles the 
metallic tinkling which is heard in large pathological cavities in the lungs, or which occurs 
when the pleural cavity contains air, and when the conditions which permit a more uniform 
reflection of the sound-waves within the cavity are present. 
[When a cavity, freely communicating with a large bronchus, exists in the upper and 
anterior part of the lung, a peculiar “ cracked-pot sound” is heard on percussing over the 
part. Some notion of this sound may be obtained by clasping the two hands so as to bring the [Sec. 115. 
212 
THE NORMAL RESPIRATORY SOUNDS. 
palms nearly together, leaving an air-space between them, and then striking them on the knee. 
When percussion is made over a large cavity communicating with a bronchus, some of the air 
is expelled and the sound thereby emitted is blended with the fundamental note of the air in 
the cavity itself, the combination of these two sounds thus producing the “ cracked-pot” 
sound.] 
Resistance.—When percussing a chest, we may determine whether the substance lying under 
the portion of the chest under examination presents great or small resistance to the blow, either 
of the percussion-hammer or of the tips of the fingers, as the case may be, [e. g., in great 
pleuritic effusion exerting much pressure on, and so distending, the thoracic walls.] 
Phonometry.—If the stem of a vibrating tuning-fork be placed on the chest-wall over a part 
containing air, its sound is intensified; but if it be placed over a portion of the lung which 
contains little or no air, its sound is enfeebled (von Baas). 
116. THE NORMAL RESPIRATORY SOUNDS.—If the ear 
directly, or through the medium of a stethoscope, be placed in connection 
with the chest-wall, we hear over the entire area, where the lung is in contact 
with the chest, the so-called “ normal vesicular sound,” which is audible 
during inspiration, and its typical characters may be studied by listening in the 
infra-scapular region in an adult. It is a fine, soft, sighing or breezy sound, 
[which gradually increases in intensity until it reaches a maximum, and falls 
away before expiration begins]. It is said to be caused by the sudden dilatation 
of the air-vesicles (hence “ vesicular”) during inspiration, and it is also ascribed 
to the friction of the current of air entering the alveoli. The sound has, at one 
time, a soft, at another, a sharper character; the latter occurs constantly in 
children up to 12 years of age. In their case, the sound is sharper, because 
the air, in entering vesicles one-third narrower, is subjected to greater friction. 
This is followed by an expiratory sound, which may be absent during quiet 
breathing. It is a feeble sighing sound, of an indistinct soft character, caused 
by the air passing out of the air-vesicles, is three or four times shorter than the 
inspiratory, is loudest at first, and soon disappears, the latter part of the expi- 
ratory act giving rise to no audible sound. Its absence is not a sign of disease, 
but when it is prolonged and loud, suspicion is aroused. The relative duration 
of the respiratory sounds is :— 
Inspiratory sound : Expiratory sound : : 3 : 1. 
Bronchial Respiration.—Within the larger air-passages—larynx, trachea, 
bronchi—during inspiration and expiration, there are loud, rough, harsh sounds 
like a sharp h or ch—the “ bronchial”—the laryngeal, tracheal, or “ tubular ” 
sound, or breathing. [In normal bronchial breathing, as heard over the trachea, 
there is a pause between the inspiratory and expiratory sounds, which are of 
nearly equal duration and of about the same intensity throughout. These 
sounds are also heard between the scapulae, at the level of the fourth dorsal ver- 
tebra (bifurcation of trachea), and they occur also during expiration, being 
slightly louder on the right side, owing to the slightly greater calibre of the 
right bronchus. At all other parts of the chest, the vesicular sound obscures 
the tubular or bronchial sound. If the air-vesicles are deprived of their air, 
the tubular breathing becomes distinct.] 
Bronchial respiration is produced chiefly in the larynx, owing to the forma- 
tion of air-eddies in consequence of the narrowing of the respiratory part of the 
glottis. This “laryngeal stenosis sound” excites resonance of the tracheo- 
bronchial column of air, and communicates to it the specific character of 
bronchial breathing which is heard over the large tubes of the bronchial system 
(Dehio). 
[On listening with a stethoscope over the trachea, or better still, over the cervical vertebras, 
the sounds heard vary according as the mouth is open or closed. With the mouth open, the soft- 
blowing respiratory sounds are about of equal duration, are separated by a short pause, but the 
expiratory is louder than the inspiratory. If the mouth be closed, and respiration consequently Sec. 116.] 
PATHOLOGICAL RESPIRATORY SOUNDS 
213 
carried on through the nose, it is found that the sounds become harsher and louder. The char- 
acter of the sounds also vary with the rapidity of breathing.] 
It is asserted that, when lungs containing air are placed over the trachea, the tubular sound 
there produced becomes vesicular. In this case, we must suppose that the vesicular sound arises 
from the tubular breathing becoming weakened, and acoustically altered by being conducted 
through the lung alveoli. A sighing sound is often produced at the apertures of the nose and 
mouth during forced inspiration. 
117. PATHOLOGICAL RESPIRATORY SOUNDS.—[The breath-sounds heard in 
disease may be merely modifications of the normal vesicular or bronchial sounds, or new sounds, 
such as friction sounds, rales, or rhonchi.] 
[Puerile Breathing is merely an exaggerated vesicular sound, so called because it resembles 
the louder vesicular sound heard in children. It occurs when some part of the lung is unable 
to act, and there is, as it were, extra work of the other parts to compensate, and thus the sound 
is exaggerated.] 
(1) Bronchial or Tubular Breathing occurs over the entire area of the lung, either when 
the air-vesicles are devoid of air, which may be caused by the exudation of fluid or solid con- 
stituents. or when the lungs are compressed from without. In both cases vesicular sounds dis- 
appear, and the condensed or solidified lung-tissue conducts the tubular sound of the large bronchi 
to the surface of the chest. [The sound heard over a hepatized lobe of the lung in pneumonia is 
a typical example.] It also occurs in large cavities, with resistant walls near the surface of the 
lung, provided these cavities communicate with a large bronchus. [In this case it is termed 
cavernous breathing.] 
(2) The amphoric sound is compared to that produced by blowing over the mouth of an 
empty bottle. It occurs either when a cavity—at least the size of the fist—exists in the lung, 
which is so blown into during respiration that a peculiar amphoric-like sound, with a metallic 
timbre, called metallic tinkling, is produced; or when the lung still contains air, and is cap- 
able of expansion; as there is still air in the pleural cavity, it acts as a resonaior, and causes an 
amphoric sound, simultaneous with the change of air in the lungs. [The amphoric sound or 
echo and metallic tinkling are the only certain signs of the existence of a cavity in the lung.] 
(3) If obstruction occurs in the course of the air-passages of the lungs, various results may 
accrue, according to the nature of the resistance:—(a) owing to various causes, e.g., in the 
apices of the lungs, there may be partial swelling of the walls of the air-tubes, or infiltration into 
the air-cells which hinders the regular supply of the air. In these cases, parts of the lung are 
not supplied with air continuously; it only reaches them periodically, when a cogwheel sound 
occurs. A similar sound may be heard occasionally in a normal lung, when the muscles of the 
chest contract in a periodic spasmodic manner. (6) When the air entering large bronchi causes 
the formation of bubbles in the mucus which may have accumulated there, “ mucous ” are 
produced. They also occur in small spaces when the walls are separated from their fluid con- 
tents by the air entering during inspiration, or when the walls, being adherent to each other, are 
suddenly pulled asunder. The rales are distinguished as moist (when the contents are fluid), or 
as dry (when the contents are sticky) ; they may be inspiratory, expiratory, or continuous, or they 
may be coarse or fine; further, there is the very fine crepitation, or crackling sound, and, lastly, 
the metallic tinkling caused in large cavities through resonance. [Crepitation or vesicular 
riles are fine crepitating sounds like those produced by rubbing a lock of hair between the fin- 
gers near one’s ear, or the sounds produced when salt is thrown on a fire; they occur only during 
inspiration, and are a proof that some air is entering the air-vesicles. It is heard in its typical 
form during the first stage of pneumonia, and seems to be produced by the bursting of minute 
bubbles of air in fluid.] (c) When the mucous membrane of the bronchi is greatly swollen, or 
is so covered with viscid mucus that the air must force its way through, deep sonorous rhonchi 
(rhonchi sonori) may occur in the large air-passages, and clear, shrill, sibilant sounds (rhonchi 
sibilantes) in the smaller ones. [Rhonchi are whistling sonorous sounds, with a squeaking char- 
acter, and are usually due to catarrh or to affections of the bronchial mucous membrane or bron- 
chitis. When they are of low pitch, and produced in the large bronchial tubes, they are spoken 
of as sonorous rhonchi, but when they are of high pitch, and reproduced in the small bronchial 
tubes, they are sibilant rhonchi.] When there is extensive bronchial catarrh, not unfrequently 
we feel the chest-wall vibrating with the rale sounds (bronchial fremitus). 
(4) If fluid and air occur together in one pleural cavity in which the lung is collapsed, on 
shaking the person’s thorax vigorously we hear a sound such as is produced when air and water 
are shaken together in a bottle. This is the succussion sound of Hippocrates. Much more 
rarely this sound is heard under similar conditions in large pulmonary cavities. 
(5) Pleural Friction.—When the two opposed surfaces of the pleura are inflamed, have 
become soft, and are covered with exudation, they move over each other during respiration, and 
in doing so give rise to friction sounds, which can be felt (often by the patient himself), and 
can also be heard. The sound is comparable to the sound produced by bending new leather. 
(6) Pectoral Fremitus.—When we speak or sing in a loud tone, the walls of the chest 214 
RESPIRATORY AND INTRA-THORACIC PRESSURES. 
[Sec. 117. 
vibrate, because the vibration of the vocal cords is propagated throughout the entire bronchial 
ramifications. The vibration is, of course, greatest near the trachea and large bronchi. The ear 
cannot detect the sounds distinctly. If there be much exudation or air in the pleura, or great 
accumulation of mucus in the bronchi, the pectoral fremitus is diminished or altogether absent. 
[In health, when a person speaks, the vocal resonance over the trachea, although loud, may 
be inarticulate; and on listening over the sternum the sound is diminished and quite inarticu- 
late ; while over the chest-wall generally the sound, though distinct, is feeble.] 
All conditions which cause bronchial breathing increase the pectoral fremitus. Under normal 
circumstances, therefore, it is louder where bronchial breathing is heard normally. The ear 
hears an intensified sound, called bronchophony, [which is a sound like that heard normally 
over the trachea or bronchi, but audible over the vesicular lung-tissue. The conditions that 
cause it are the same as those on which bronchial breathing depends, so that it is heard in 
pneumonia and phthisis. If, through effusion into the pleura or inflammatory processes in the 
lung-tissue, the bronchi are pressed flat, a peculiar bleating sound (segophony) may be heard.] 
118. PRESSURE IN THE AIR-PASSAGES DURING RESPI- 
RATION.—Respiratory Pressure.—If a manometer be tied into the 
trachea of an animal, so that the respiration goes on completely undisturbed, 
i. <?., normal respiration, during every inspiration there is a negative pres- 
sure (-3 mm. Hg) and during expiration a positive pressure. Donders placed 
the U-shaped manometer tube in one nostril, closed his mouth, leaving the 
other nostril open, and respired quietly. * During every quiet inspiration the 
mercury showed a negative pressure of -1 mm., and during expiration a posi- 
tive pressure of 2-3 mm. (Hg). 
Forced Respiration.—As soon as the air was inspired or expired with 
greater force, the variations in pressure became very much greater, e. g., during 
speaking, singing, and coughing. The inspiratory pressure was = 57 mm. 
(36-74), the greatest expiratory pressure -f- 87 (82-100) mm. Hg. The pres- 
sure of forced expiration, therefore, is 30 mm. greater than the inspiratory 
pressure (.Donders\ 
Resistance to Inspiration.—Notwithstanding this, we must not conclude 
that the expiratory muscles act more powerfully than the inspiratory; for during 
inspiration a variety of resistances have to be overcome, so that after these have 
been met, there is only a residue of the force for the aspiration of the mercury. 
The resistances to be overcome by the inspiratory muscles are :—(1) The elastic 
tension of the lungs, which during the deepest expirations = 6 mm. ; during the 
deepest inspirations = 30 mm. Hg (§ 107). (2) The raising of the weight of 
the chest. (3) The elastic torsion of the costal cartilages. (4) The depression 
of the abdominal contents, and the elastic distention of the abdominal walls. 
All these not inconsiderable resistances, which the inspiratory muscles have to 
overcome, act during expiration, and aid the expiratory muscles. The forces 
concerned in inspiration are decidedly much greater than those of expiration. 
Intra-thoracic Pressure.—As the lungs within the chest, in virtue of 
their elasticity, continually strive to collapse, necessarily they must cause a neg- 
ative pressure within the chest. This amounts in dogs, during inspiration, to 
-7.1 to - 7.5 mm. Hg, and during expiration to - 4 mm. Hg. The corre- 
sponding values for man have been estimated at - 4.5 mm. Hg and - 3 mm. 
Hg, by Hutchinson. 
[We must distinguish between the respiratory pressure of the air within the respiratory 
passages, and the intra-thoracic pressure. The former is the same as the atmospheric pressure 
when the chest is passive, but less than it as the chest is being enlarged, and greater than it 
when it is being diminished in size. The intra-thoracic pressure is the pressure within the 
chest, but outside the lungs, i. e., in the pleura, mediastinum, etc. It is negative, i. e., less than 
the atmospheric pressure, and must vary with the degree of distention of the lungs.] 
[Methods of Estimating Intra-Thoracic Pressure.—A direct estimation was made 
by Adamkiewicz and Jacobson. A trocar with its stylette was forced into the fourth left inter- 
costal space near the sternum and pushed into the pericardium (sheep). The stylette was then 
withdrawn, and the trocar connected with a manometer, and the negative pressure of - 3 to - 5 Sec. 118.] 
NASAL BREATHING. 
215 
mm. Hg was obtained. During severe dyspnoea it was -9 mm. Hg. Rosenthal introduced an 
cesophageal sound with an elastic ampulla on its lower end into the oesophagus, so that the 
ampulla came to lie opposite the posterior mediastinum. The sound was connected with a regis- 
tering tambour or manometer. During inspiration the manometer fell, and during expiration 
it rose.] 
Even the greatest inspiratory or expiratory pressure is always much less than the blood-pressure 
in the large arteries ; but if the pressure be calculated upon the entire respiratory surface of the 
thorax, very considerable results are obtained. 
Pneumatometer.—This instrument of Waldenburg is merely a mercurial manometer fixed 
to a stand and connected to an elastic tube with a suitable mouthpiece, which is fitted over the 
mouth and nose, while the variations of the Hg can be read off on a scale. [In the male, the 
expiratory pressure is 90-120 mm. Hg, and the inspiratory 70-100. The relation of the pressures 
during expiration and inspiration is more important than the absolute pressure.] The inspira- 
tory pressure is diminished in nearly all diseases where the expansion of the lung is impaired 
[phthisis] ; or the expiratory pressure is diminished, as in emphysema and asthma. 
[The Lungs before birth are in an atelectatic condition, i. e., they 
contain no air. The alveoli are lined by cubical, nucleated granular cells, and 
their surfaces are in apposition, so that there are no alveolar cavities; similarly 
the walls of the bronchioles are in contact, while the cavity which exists in the 
larger bronchi and trachea contains fluid. At the first breath the air sucked in 
has to overcome the adhesion of the surfaces of the bronchi and alveolar epi- 
thelium, and as inspiration follows inspiration, gradually the respiratory pass- 
ages are opened up. It takes some time to establish a fully-distended condition 
of the lung. In a newly-born animal there is no negative pressure in the pleural 
cavity, for the lungs have not yet been distended, nor do the lungs collapse 
when the chest is opened. It is only when the elastic tension of the lungs is 
brought into play by the chest being distended, that the negative pressure ob- 
tains within the pleural cavity, and the lungs collapse when the chest is opened. 
The distention of the lungs takes place gradually, and seems to be brought 
about by the chest growing more rapidly than the lungs within it; so that even 
in the phase of expiration the lungs are kept distended.] 
Effects of the first Respiration on the Thorax.—Until birth the airless lungs are com- 
pletely collapsed (atelectatic) within the chest, and fill it, so that on opening the chest in a dead 
foetus, pneumo-thorax does not occur (Bernstein). Supposing, however, respiration to have been 
fully established after birth, and air to have freely entered the lungs, if a manometer be placed 
in connection with the trachea, and the chest be opened, the manometer will register a pressure 
of 6 mm. Hg, due to the collapse of the elastic lungs. Bernstein supposes that the thorax as- 
sumes a new permanent form, due to the first respiratory distention; it is as if, owing to the 
respiratory elevation of the ribs, the thorax had become permanently too large for the lungs, 
which are, therefore, kept permanently distended, but collapse as soon as air passes into the 
pleura. When a lung has once been filled with air, it cannot be emptied by pressure from with- 
out, as the small bronchi are compressed before the air can pass out of the alveoli. The expira- 
tory muscles cannot possibly expel all the air from the lungs, while the inspiratory muscular 
force is sufficient to distend the lungs beyond their elastic equilibrium. Inspiration distends 
the lungs, increasing their elastic tension, while expiration diminishes the tension without abol- 
ishing it. 
119. APPENDIX TO RESPIRATION.—Nasal Breathing.— 
During quiet respiration we usually breathe—or ought to breathe—through the 
nostrils, the mouth being closed. The current of air passes through the pha- 
ryngo-nasal cavity—so that, in its course during inspiration, it is (1) warmed 
and rendered moist, and thus irritation of the mucous membrane of the air- 
passages by the cold air is prevented; (2) small particles of soot, or other 
foreign substances in the air, adhere to and become embedded in the mucus 
covering the somewhat tortuous walls of the respiratory passages, and are car- 
ried outwards by the agency of the ciliated epithelium of the respiratory pass- 
ages; (3) disagreeable odors and certain impurities are detected by the sense 
of smell. 
If a lung be inflated, air constantly passes through the walls of the alveoli and trachea. This MODIFIED RESPIRATORY ACTS. 
[Sec. 119. 
also occurs during violent expiratory efforts (cutaneous emphysema in whooping-cough), so that 
pneumo-thorax may occur (J. R. Ewald and Koberl). 
Pulmonary (Edema, or the exudation of lymph into the pulmonary alveoli, occurs—(i) 
When there is very great resistance to the blood-stream in the aorta or its branches, e.g., by liga- 
turing all the arteries going to the head, or the arch of the aorta, so that only one carotid remains 
pervious. (2) When the pulmonary veins are occluded. (3) When the left ventricle, owing to 
mechanical injury, ceases to beat, while the right ventricle goes on contracting ($ 47). These 
conditions produce at the same time ansemia of the vaso-motor centre, which results in stimula- 
tion of that centre, and consequent contraction of all the small arteries. Thus the blood-stream 
through the veins to the right heart is favored, and this in its turn favors the production of oedema 
of the lungs. [The injection of muscarin rapidly causes pulmonary oedema, due to the increase 
of pressure and slowing of the blood-stream in the pulmonary capillaries. It is set aside by 
atropin (Weinzweig, Grossmann).~\ 
120. MODIFIED RESPIRATORY MOVEMENTS.—(1) Cough- 
ing consists in a sudden violent expiratory explosion after a previous deep in- 
spiration and closure of the glottis, whereby the glottis is forced open, and any 
substance, fluid, gaseous, or solid, in contact with the respiratory mucous mem- 
brane is violently ejected through the open 
mouth. It is produced voluntarily or reflexly; 
in the latter case it can be controlled by the 
will only to a limited extent. 
[Causes.—A cough may be discharged reflexly from 
a large number of surfaces (fig. 165) :—(1) A draught of 
cold air striking the skin, especially of the upper part of 
the body. This may cause congestion of blood in the 
air-passages, this in turn exciting the cough. (2) More 
frequently it is discharged from the respiratory mucous 
membrane, especially of the larynx, the sensory branches 
of the vagus and the superior laryngeal nerve being the 
afferent nerves. A cough cannot be discharged from 
every part of the larynx: thus there is none from the 
true vocal cords, but only from the glottis respiratoria. 
All other parts of the larynx are inactive, and so is the 
trachea as far as the bifurcation, where stimulation ex- 
cites a cough (Kohts). (3) Sometimes an offending 
body, such as a pea or inspissated cerumen in the exter- 
nal auditory meatus, gives rise to coughing, the afferent 
nerve being the auricular branch of the vagus. (4) 
There seems to be no doubt that there maybe a “gastric 
or stomach cough ” produced by stimulation of the gas- 
tric branches of the vagus, especially in cases of indi- 
gestion, accompanied by irritation of the larynx and 
trachea. (5) Irritation of the costal pleura and even of 
the oesophagus (Kohls'). (6) Irritation of some parts 
of the nose. (7) Sometimes also from irritation of the 
pharynx, as by an elongated uvula. (8) In some dis- 
eases of the liver, spleen, and generative organs, when 
pressure is exerted on these parts.] 
(2) Hawking, or clearing the throat.—An expiratory 
current is forced in a continuous stream through the nar- 
row space between the root of the tongue and the de- 
pressed soft palate, in order to assist in the removal of 
foreign bodies. When the act is carried out periodically, 
the closed glottis is suddenly forced open, and it is com- 
parable to a voluntary gentle cough. This act can only be produced voluntarily. 
(3) Sneezing consists in a sudden violent expiratory blast through the nose, for the removal 
of mucus or foreign bodies (the mouth being rarely open) after a simple or repeated spasm-like 
inspiration—the glottis remaining open. It is usually caused reflexly by stimulation of sensory 
nerve-fibres of the nose [nasal branch of the fifth nerve], or by sudden exposure to a bright 
light [the afferent nerve is the optic]. This reflex act may be interfered with to a certain extent, 
or even prevented, by stimulation of sensory nerves; or firmly compressing the nose where the 
nasal nerve issues. The continued use of sternutatories, as in persons who take snuff, dulls the 
sensory nerves, so tlSat they no longer act when stimulated reflexly. 
Scheme of the afferent nerves through 
which coughing may be excited 
reflexly. The efferent nerves are 
dotted. 
Fig. 165. Sec. 120.] 
ANALYSIS OF EXPIRED GASES. 
217 
[Sternutatories or Errhines, such as powdered ipecacuanha, snuff, and euphorbium, also 
increase the secretion from the nasal glands. The afferent impulses sent to the respiratory 
centre also affect the vaso-motor centre, so that, even when sneezing does not occur, the blood- 
pressure throughout the body is raised.] 
(4) Snoring occurs during respiration through the open mouth, whereby the inspiratory and 
expiratory stream of air throws the uvula and soft palate into vibration. It is involuntary, and 
usually occurs during sleep, but it may be produced voluntarily. 
(5) Gargling consists in the slow passage of the expiratory air-current in the form of bubbles 
through a fluid lying between the tongue and the soft palate, when the head is held backwards. 
It is a voluntary act. 
(6) Crying, caused by emotional conditions, consists in short, deep inspirations, long expira- 
tions with the glottis narrowed, relaxed facial and jaw muscles, secretion of tears, often combined 
with plaintive inarticulate expressions. When crying is long continued, sudden and spasmodic 
involuntary contractions of the diaphragm occur, which cause the inspiratory sounds in the 
pharynx and larynx known as sobbing. This is an involuntary act. 
(7) Sighing is a prolonged inspiration, usually combined with a plaintive sound, often caused 
involuntarily, owing to painful or unpleasant recollections. 
(8) Laughing is due to short rapid expiratory blasts through the rima glottidis, which cause 
a clear tone, and there are characteristic inarticulate sounds in the larynx, with vibrations of the 
soft palate. The mouth is usually open, and the countenance has a characteristic expression, 
owing to the action of the M. zygomaticus major. It is usually involuntary, and can only be 
suppressed, to a certain degree, by the will (by forcibly closing the mouth and stopping respiration). 
(9) Yawning is a prolonged deep inspiration occurring after successive attempts at numerous 
inspirations—the mouth, fauces, and glottis being wide open; expiration shorter—both acts often 
accompanied by prolonged characteristic sounds. It is quite involuntary, and is usually excited 
by drowsiness or ennui. 
[(10) Hiccough is due to a spasmodic involuntary contraction of the diaphragm, causing an 
inspiration, which is arrested by the sudden closure of the glottis, so that a characteristic sound 
is emitted. Not unfrequently it is due to irritation of the gastric mucous membrane, and some- 
times it is a very troublesome symptom in uraemic poisoning.] 
121. CHEMISTRY OF RESPIRATION—CARBON DIOXIDE, OXYGEN, and 
WATERY VAPOR GIVEN OFF.—I. Estimation of COr—1. The volume of C02. 
is estimated by means of the anthracometer (fig. 166, II). The volume of gas is collected in. 
a graduated tube, r, r, 
provided with a bulb at 
one end (previously 
filled with water and 
carefully calibrated, 
i. f.,the exact amount 
which each part of 
the tube contains is 
accurately measured), 
and the tube is closed. 
The lower end has a 
stop-cock, h, and to 
this is screwed a flask, 
n, completely filled 
with a solution of 
caustic potash; the 
stop-cock is then 
opened, the potash 
solution is allowed to 
ascend into the tube, 
which is moved about 
until all the C02 
unites with the potash 
to form potassium car- 
bonate. Hold the 
tube vertically and 
allow the potash to 
run back into the 
flask, close the stop- 
cock, and remove the 
bottle with the pot- 
ash. Place the stop cock under water, open it, and allow the water to ascend in the tube,. 
I 
IT 
Apparatus of Andral and Gavarret for collecting the expired air. C, 
large cylinder to collect the air expired; P, weight to balance cylin- 
der; a, b, two Muller’s valves; M, mouthpiece; II. Anthracometer 
of Vierordt. 
Fig. 166. 218 
ANALYSIS OF EXPIRED GASES. 
[Sec. 121. 
when the space in the tube occupied by the fluid indicates the volume of C02 which is com- 
bined with the potash. 
2. By Weight.—A large quantity of the mixture of gases which has to be investigated is 
made to pass through a Liebig’s bulb filled with caustic potash. The potash apparatus having 
been carefully weighed beforehand, the increase of weight indicates the amount of C02 which 
has been taken up by the potash from the air passed through it. 
3. By Titration.—A large volume of the air to be investigated is conducted through a known 
Scharling’s apparatus, d, bulb containing caustic potash to absorb C02 from ingoing air; A, 
box for animal experimented on; e and g, tubes containing sulphuric acid to absorb watery 
vapor; f potash bulb to absorb C02 given off; C, vessel filled with water to aspirate air; 
h, stop-cock. 
Fig. 167. 
Fig. 168. 
Scheme of the respiration apparatus of Regnault and Reiset. R, globe for animal; g, g, outer 
casing for R, provided with a thermometer, l; d and <?, exit tubes to movable potash bulbs 
KOIi and Koh; O, ingoing oxygen ; C02, vessel to absorb any carbonic acid; CaCl2, 
apparatus for estimating the amount of O supplied; f, manometer. 
volume of a solution of barium hydrate. The C02 unites with the barium and forms barium 
carbonate. The fluid is neutralized with a standard solution of oxalic acid, and the more 
barium that has united with the C02 the smaller will be the amount of oxalic acid used, and 
vice versa. 
II. Estimation of Oxygen.—According to volume—(a) By the union of the O with potas- 
sium pyrogallate. The same procedure is adopted as for the estimation of C02, only the flask, 
n, is filled with the pyrogallate solution instead of potash, (b) By explosion in an eudiometer 
{Bloodgases, \ 35). Sec. 121.] 
METHODS OF INVESTIGATION. 
219 
III. Estimation of Watery Vapor.—The air to be investigated is passed through a bulb 
containing concentrated sulphuric acid, or through a tube filled with pieces of calcium chloride. 
The amount of water is directly indicated by the increase of weight. 
122. METHODS OF INVESTIGATION.—Collecting the Expired Air.—(i) The 
air expired may be collected in the cylinder of the spirometer, which is suspended in concen- 
trated salt solution to avoid the absorption of C02 (§ 108). 
Andral and Gavarret’s Apparatus.—The operator breathed several times into a capacious 
cylinder (fig. 166). A mouthpiece (M) was placed air-tight over the mouth while the nostrils 
were closed. The direction of the respiratory current was regulated by two “ Muller’s Valves ” 
(mercurial), (a and h). With every inspiration the bottle or valve a (filled below with Hg, and 
hermetically closed above) permits the air inspired to pass to the lungs—during every expiration 
the expired air can pass only through b to the collecting-cylinder C. 
(2) If the gases given off by the skin are to be collected, a limb, or whatever part is to be 
investigated, is secured in a closed vessel, and the gases so obtained are analyzed. 
II. The most important apparatus for this purpose are those of—(a) Scharling, which consists 
of a closed box, A, of sufficient size to contain a man (fig. 167). It is provided with an 
inlet z and outlet b. The latter is connected with an aspirator, C, a large barrel filled with 
water. When the stop-cock, h, is opened and the water flows out of the barrel, fresh air will 
rush in continuously into the box, A, and the air mixed with the expired gases will be drawn 
towards C. A Liebig’s bulb, d, filled with caustic potash, is connected with the entrance tube, 
z, through which the ingoing air must pass, whereby it is completely deprived of C02, so that 
the person experimented on is supplied with air free from C02. The air passing out by the 
exit tube, b, has to pass first through e, where it gives up its watery vapor to sulphuric acid, 
whereby the amount of watery vapor is estimated by the increase of the weight of the apparatus, 
e. Afterwards the air passes through a bulb, f, containing caustic potash, which absorbs all the 
C02, while the tube,g, filled with sulphuric acid, absorbs any watery vapor that may come from 
f. The increase in weight of f and g indicates the amount of C02. The total volume of air 
used is known from the capacity of C. 
(b) Regnault and Reiset’s Apparatus is more complicated, and is used when it is neces- 
sary to keep animals for some time under observation in a bell-jar. It consists of a globe, R, in 
which is placed the dog to be experimented on (fig. 168). Around this is placed a cylinder, 
g. g (provided with a thermometer, t), which may be used for calorimetric experiments. A 
tube, c, leads into the globe, R ; through this tube passes a known quantity of pure oxygen 
(fig. 168, O). To absorb any trace of C02, a vessel containing potash (fig. 168, C02) is placed 
in the course of the tube. The vessel for measuring the O is emptied towards R, through a 
solution of calcium chloride from a large pan (CaCl2) provided with large flasks. Two tubes, 
d and e, lead from R, and are united by caoutchouc tubes with the potash bulbs (KOH, Koh), 
which can be raised or depressed alternately by means of the beam, W. In this way they 
aspirate alternately the air from R, and the caustic potash absorbs the C02. The increase in 
weight of these flasks after the experiment indicates the amount of C02 expired. The mano- 
meter,/', shows whether there is a difference of the pressure outside and inside the globe, R. 
(r) V. Pettenkofer’s is the most complete apparatus (fig. 169). It consists of a chamber, 
Z, with metallic walls, and provided with a door and a window. At a is an opening for the 
admission of air, while a large double suction-pump, PPj, continually renews the air within the 
chamber. The air passes into a vessel, b, filled with pumice-stone saturated with sulphuric 
acid, in which it is dried; it then passes through a large gas-meter, c, which measures the 
total amount of the air passing through it. After the air is measured, it is emptied outwards 
by means of the pump, PPr From the chief exit tube, x, of the chamber provided with a 
small manometer, q, a narrow laterally placed tube, n, passes and conducts a small secondary 
stream, which is chemically investigated. This current passes through the suction-apparatus, 
MMj (constructed on the principle of Muller’s mercurial valve, and driven by a steam-engine). 
Before reaching this apparatus, the air passes through the bulb, K, filled with sulphuric acid, 
whose increase in weight indicates the amount of watery vapor. After passing through MM1( 
it goes through the tube, R, filled with baryta solution, which takes up C02. The quantity of 
air which passes through the accessory current, n, is measured by the small gas-meter, u, from 
which it passes outwards. The second accessory stream, N, enables us to investigate the air 
before it enters the chamber, and it is arranged in exactly the same way as n. The increase of 
C02 and H20 in the accessory stream, n (i. e., more than in N), indicates the amount of C02 
given off by the person in the chamber, Z. 
123. COMPOSITION OF ATMOSPHERIC AIR.—1. Dry Air 
contains:— 
Gas. 
By Weight. 
By Volume. 
o, . . . 
• • • 23.015 
20.96 
N, . . . 
• • • 76-985 
79.02 
co„. . . 
0.03-0.034 220 
COMPOSITION OF ATMOSPHERIC AND EXPIRED AIR. 
[Sec. 123. 
2. Aqueous vapor is always present in the air, but it varies greatly in 
amount, and generally increases with the increase of the temperature of the 
air. We distinguish (a) the absolute moisture, i. e., the quantity of watery 
vapor which a volume of air contains in the form of vapor; and the 
relative moisture, i. e., the amount of watery vapor which a volume of air con- 
tains with respect to its temperature. 
Experience shows that people generally can breathe most comfortably in an atmosphere which 
is not completely saturated with aqueous vapor according to its temperature, but is only 
saturated to the extent of 70 per cent. If the air be too dry, it irritates the respiratory mucous 
membrane; if too moist, there is a disagreeable sensation; and if it be too warm, a feeling of 
closeness. Hence, it is important to see that the proper amount of watery vapor is present in 
the air of our sitting-rooms, bedrooms, and hospital wards. 
The absolute amount of moisture varies:—In towns during the day it increases with increase 
Respiration apparatus of v. Pettenkofer. Z, chamber for person experimented on ; x, exit 
tube with manometer, q\ b, vessel with sulphuric acid; C, gas-meter; PP,, pump; 
n, secondary current, with, k, bulb; MMj, suction apparatus; u, gas-meter; N, stream 
for investigating air before it enters Z. 
Fig. 169. 
of temperature, and diminishes when the temperature falls; it also varies with the direction of 
the wind, season of the year, and the height above sea-level. 
The relative amount of moisture is greatest at sunrise, least at midday; small on high 
mountains; greater in winter than in summer; larger with a south or a west wind than with a 
north or an east wind. 
The air in midsummer contains absolutely three times as much watery vapor as in mid-win- 
ter, nevertheless the air in summer is relatively drier than the air in winter. 
3. The air expands by heat. Rudberg found that 1000 volumes of air, 
at o°, expanded to 1365 when heated to ioo° C. 
4. The density of the air diminishes with increase of the height above the 
sea-level. 
124. COMPOSITION OF EXPIRED AIR.—1. The expired air con- 
tains more CO,—in normal respiration = 4.38 vols. per cent. (3.3 to 5.5 per 
cent.), so that it contains nearly 100 times more C02 than the atmospheric air. Sec. 124.] 
DAILY QUANTITY OF GASES EXCHANGED. 
221 
2. It contains less O (4.782 vols. per cent, less) than the atmospheric air, 
i. e., it contains only 16.033 v°ls- Per cent, of O. 
3. Respiratory Quotient.—Hence, during respiration, more O is taken 
into the body from the air than C02 is given off; so that the volume of the 
expired air is to smaller than the volume of the air inspired, both being 
calculated as dry, at the same temperature, and at the same barometric pres- 
sure. The relation of the O absorbed to the C02 given off is 4.38 : 4.782. 
This is expressed by the “ respiratory quotient ”— 
CO,/ 4.-38 V 0.916. 
O V, 4-782/ 
4. An excessively small quantity of N is added to the expired air (.Regnault 
andReisef). Segen found that all the N taken in with the food did not re- 
appear in the excreta (urine and faeces), and he assumed that a small part of it 
was given off by the lungs. 
5. During ordinary respiration the expired air is saturated with watery 
vapor. It is evident, therefore, that when the watery vapor in the air varies, 
the lungs give off different quantities of water from the body. The percentage 
of watery vapor falls during rapid respiration (.Moleschott). 
6. The expired air is warmer (36°.3C.). It is very near the temperature 
of the body, and although the temperature of the surrounding atmosphere be 
very variable, the temperature of the expired air still remains nearly the same. 
Fig. 170 shows the instrument used by Valentin and Brunner to determine the temperature 
of the expired air. It consists of a glass tube, A, A, with a mouth-piece, B, 
and in it is a fine thermometer, C. The operator breathes through the nose 
and expires slowly through the mouth-piece into the tube. 
Temperature of 
Temperature of the 
the Air. 
Expired Air. 
6-3° C„ 
+ 29.8° c. 
+17-190 c., 
+36.2-37° c. 
+ 44° C., 
*. +38.5°C. 
7- The diminution of the volume of the expired air 
mentioned under (3) is far more than compensated by the 
warming which the inspired air undergoes in the respiratory 
passages, so that the volume of the expired air is one-ninth 
greater than the air inspired. 
8. A very small quantity of ammonia is found in the ex- 
pired air = 0.0204 grams in 24 hours; it is probably derived 
from the blood. 
9. Small quantities of H and CH4 are expired, both being 
absorbed from the intestine. In herbivora, Reiset found that 
30 litres of CH4 were expired in 24 hours. 
[The toxicity of the exhalations from the lungs of animals described by 
Brown-Sequard has not been confirmed by other observers.] 
125. DAILY QUANTITY OF GASES EX- 
CHANGED.—As under normal circumstances more O is ab- 
sorbed than there is C02 given off (equal volumes of O and C02 
contain equal quantities of O), a part of the O must be used for 
other oxidation-processes in the body. According to the ex- 
tent of these latter processes, the ratio of the O taken in to 
the C02 given out—i. e., the respiratory quotient— 
/(Xb = 0.916 must vary. 
The amount of C02 given off may be less than, the “ mean ” 
above stated. The quantity of C03 alone is not a reliable in- 
Fig. 170. 222 
CONDITIONS INFLUENCING THE GASEOUS EXCHANGES. 
[Sec. 125. 
dication of the entire exchange of gases during respiration ; we must esti- 
mate simultaneously the amount of O absorbed and the C02 given off. 
126. DAILY GASEOUS INCOME AND EXPENDITURE. 
Income in 24 hours. 
Oxygen— 
744grms. = 516500 c.cmtr. [Vierordt). 
[Average, 700 grms.] 
(At o° C. and mean barometric pressure). 
Expenditure in 24 hours. 
Carbonic Acid— 
900 grms. = 455500 c.cmtr., . ( Vierordt). 
36 grms. per hour (Scharling). 
32.8 to 3.34 grms. “ (Liebermeister). 
34 grms. “ . . . (Panum). 
31.5 to 33 grms. “ . . . [Ranke). 
[Average, 850 grms. 8ozs. of carbon.] 
Water—640 grms. “ . . ( Valentin). 
330 “ “ . . (Vierordt). 
[Comparative.—The following table from Munk shows how the O inspired 
and the C02 expired varies in different animals :— 
Species of Animals. 
Body-weight in Kilograms. 
O Inspired in Grams. 
CO2 Expired in Grams. 
Ox, 
600. 
7950- 
IO9OO. 
Horse, 
45°- 
6100. 
9560. 
Man, 
75- 
750- 
900. 
Sheep, 
70. 
820. 
1140. 
Dog 
iS- 
425. 
44O. 
Cat, 
2-5 
60. 
64. 
Rabbit, 
2. 
45- 
57- 
Fowl, 
1. 
3i- 
39- 
Frog, 
0.03 
0.067 
0.05] 
[Nitrogen. The expired air contains a little more N than the air inspired, 
but the total is only about 7 grams daily, although herbivora eliminate more 
than carnivora.] 
[Aqueous Vapor is derived partly from the water (vapor) contained in the 
inspired air, and partly from the water of the blood circulating in the walls of 
the respiratory passages.] 
127. CONDITIONS INFLUENCING THE GASEOUS EX- 
CHANGES.—The formation of C02, in all probability, consists of two dis- 
tinct processes. First, compounds containing C02, which are oxidation pro- 
ducts of substances containing carbon, seem to be formed in the tissues. The 
second process consists in the separation of this C02, which, however, takes 
place without the absorption of O. Both processes do not always occur simul- 
taneously, and the one process may exceed the other in extent. The formation 
and elimination of C02 is affected by: — 
1. Age .—Until the body is fully developed, the C02 given off increases, 
but it diminishes as the bodily energies decay. Hence, in young persons the 
O absorbed is relatively greater than the C02 given off; at other periods both 
values are pretty constant. Example : — 
Age—Years. 
In 24 Hours. 
COg Gram. Excreted. = Carbon. 
O Absorbed in Grams. 
8 
443 grams. = 121 Carbon. 
375 grams. 
15 
766 “ = 209 “ 
652 “ 
l6 
950 “ = 259 “ 
809 “ 
18-20 
1003 “ = 274 “ 
854 “ 
20-24 
1074 “ = 293 “ 
914 “ 
40-60 
889 “ = 242 “ 
75 7 “ 
60-80 
810 “ = 221 “ 
689 “ Sec. 127.] 
QUANTITY OF CARBONIC ACID ELIMINATED. 
223 
The absolute amount of C02 given off is less in children than in adults; 
but if the C02 given off be calculated with reference to body-weight, then, 
weight for weight, a child gives off twice as much C02 as an adult. 
2. Sex.—Males, from the eighth year onward to old age, give off about 
one-third more C02 than females. This difference is more marked at puberty, 
when the difference may rise to one-half. After cessation of the menses, there 
is an increase, and in old age the amount of C02 given off diminishes. Preg- 
nancy increases the amount, owing to causes which are easily understood (An- 
dral and Gavarret). 
3. Constitution.—In general, muscular energetic persons use more O and 
excrete more C02 than less active persons of the same weight. 
4. Alternation of Day and Night.—The C02 given off is diminished 
about one-fourth during sleep, due to the constant heat of the surroundings 
(bed), darkness, absence of muscular activity, and the non-taking of food (see 
5, 6, 7, 9). O is not stored up during sleep (S. Lewiri). After awaking in 
the morning, the respirations are deeper and more rapid, while the amount of 
C02 given off is increased. It decreases during the forenoon, until dinner at 
mid-day causes another increase. It falls during the afternoon, and increases 
again after supper. 
During hibernation, when no food is taken, and when the respirations cease, or are greatly 
diminished, the respiratory exchange of gases is carried out by diffusion and the cardio-pneu- 
matic movements ($ 59). The C02 given off falls to A, the O taken in to dj> of what they are 
in the waking condition. Much less C02 is given off than O is taken in, so that the body-weight 
may increase through the excess of O. 
5. Temperature of the Surroundings.—Cold-blooded animals be- 
come warmer when the temperature of their environment is raised, and they 
give off more C02 in this condition than when they are cooler; e. g., a frog with 
the temperature of the surroundings at 390 C. excreted three times as much 
C02 as when the temperature was 6° C. Warm-blooded animals behave 
quite differently when the temperature of the surrounding medium is changed. 
When the temperature of the animal is lowered thereby, there is a considerable 
decrease in the amount of C02 given off, as in cold-blooded animals, but if the 
temperature of the animal be increased (and also in fever), the C02 is increased 
( C. Ludwig and Sanders-Ezn). Exactly the reverse obtains when the tempera- 
ture of the surroundings varies, and the bodily temperature remains constant. 
As the cold of the surrounding medium increases, the processes of oxidation 
within the body are increased through some as yet unknown reflex mechanism ; 
the number and depth of the respirations increase, whereby more O is taken in 
and more C02 is given out. A man in January uses 32.2 grams O per hour; 
in July only 31.7 grams. In animals, with the temperature of the surroundings 
at 8° C., the C02 given off was one-third greater than with a temperature of 38° 
C. When the temperature of the air increases—the body temperature remain- 
ing the same—the respiratory activity and the C02 given off diminish, while 
the pulse remains nearly constant. On passing suddenly from a cold to a warm 
medium, the amount of C02 is considerably diminished; and conversely, on 
passing from a warm to a cold medium, the amount is considerably increased 
(§ 2I4)- 
6. Muscular Exercise causes a considerable increase in the C02 given 
out, which may be three times greater during walking than during rest (Ed. 
Smith). Ludwig and Sczelkow estimated the O taken in and the C02 given off 
by a rabbit during rest, and when the muscles of the hind limbs were tetanized. 
During tetanus the O and C02 were increased considerably, but in tetanized 
animals more O was given off in the C02 expired than was taken up simulta- 
neously during respiration. The passive animal absorbed nearly twice as much 
O as the amount of C02 given off (§ 294). QUANTITY OF CARBONIC ACID ELIMINATED. 
[Sec. 127. 
7. Taking of Food causes a not inconsiderable increase in the C02 given 
off, which depends upon the quantity taken ; the increase generally occurs 
about an hour after the chief meal—dinner. The increased consumption of O 
following the taking of food into the stomach depends on the increased work of 
the intestinal tract (Zuntz and V. Mering). During inanition, the exchange 
of gases diminishes considerably until death occurs. At first the C02 given off 
diminishes more quickly than the O is taken up. The quality of the food 
influences the C02 given off to this extent, that substances rich in carbon (car- 
bohydrates and fats) cause a greater excretion of C02 than substances which 
contain less C (albumins). Regnault and Reiset found that a dog gave off 79 
per cent, of the O inspired after a flesh diet, and 91 per cent, after a diet of 
starch. If easily oxidizable substances (glycerin or lactate of soda) are injected 
into the blood, the O taken in, and the C02 given off, undergo a considerable 
increase (.Ludwig and Scheremetjewsky). Alcohols, tea, and ethereal oils 
diminish the C02 (Front, Vierordt). [Ed. Smith divided foods, with reference 
to the excretion of C02 into two classes. The respiratory excitants include 
nitrogenous foods, rum, beer, sugar, stout, etc. ; the non-exciters starch, fat, 
some alcoholic mixtures. The most powerful respiratory excitants, however, 
are tea, sugar, coffee, and rum, and the maximum effect is usually experienced 
within an hour. He also found that the effects produced by alcoholic drinks 
varied with the nature of the spirituous liquor. Thus brandy, whisky, and gin 
diminish the amount; while pure alcohol, rum, ale, and porter tend to 
increase it.] 
A healthy adult, weighing 50 kilos., respires while fasting 8 litres of air per kilo, per hour; 
he uses 0.4 gram O, and forms 0.5 gram C02. Taking of food increases these numbers to 9 
litres, 0.5 gram O, and 0.6 gram C02. The consumption of O is increased about 12 per cent, 
and the excretion of C02 about 27 per cent, after a diet of carbohydrates; it is less with a fatty 
diet, and least after one of proteids. 
8. The number and depth of the respirations have practically no influ- 
ence on the formation of C02 or the oxidation-processes within the body, these 
being regulated by the tissues themselves, by some mechanism as yet unknown 
(.Pflilger). They have a marked effect, however, upon the elimination of the 
already formed C02 from the body. An increase in the number of respirations 
(their depth remaining the same), as well as an increase of their depth (the 
number remaining the same), causes an absolute increase in the amount of C02 
given off, which, with reference to the total amount of gases exchanged, is 
relatively diminished. The following example from Vierordt illustrates this:— 
No. of Resps. 
per Minute. 
Volume of 
Air. 
Amount of = 
co2. 
per cent. 
C02. 
Depth of 
Resps. 
Amount of per cent. 
co2. ~ C02. 
12 
6000 
258 c. cmtr. 
= 4-3 % 
500 
21 c. cmtr. = 4.3 <fc 
24 
12000 
420 “ 
— 3-5 “ 
IOOO 
36 “ = 3.6 “ 
48 
24OOO 
744 “ 
= 1.3 “ 
1500 
5i “ =34“ 
96 
48000 
1392 “ 
— 2.9 “ 
2000 
64 “ = 3.2 “ 
3000 
72 “ = 1.4 “ 
g. Exposure to a bright light causes an increase in the C02 given off in 
frogs, in mammals and birds, even in frogs deprived of their lungs, or in those 
whose spinal cord has been divided high up. The consumption of O is 
increased at the same time. The same results occur in blind persons, although 
to a less degree. Rodents and birds show the maximum in red light, and 
turtles in violet light. According to Loch, the pupa of butterflies exposed to 
light do not produce more C02 than those kept in darkness, so that he attrib- 
utes the greater amount of C02 excreted to great muscular exertion produced 
by the light. Sec. 127.] 
EXCHANGE OF GASES IN THE LUNGS. 
225 
10. The experiments of Grehant, on dogs, seem to show that intense inflammation of the 
bronchial mucous membrane influences the C02 given off. 
11. Amongst poisons, thebaia increases the C02 given off, while morphia, codeia, narcein, 
narcotin, papaverin, diminish it (Filbini). 
128. DIFFUSION OF GASES WITHIN THE LUNGS.—The 
air within the air vesicles contains most C02 and least O, and as we pass from the 
small to the large bronchi and onwards to the trachea, the composition of the 
air gradually approaches more closely to that of the atmosphere. Hence, if 
the air expired be collected in two portions, the first half (i. e., the air from the 
larger air-passages) contains less C02 (3.7 vols. per cent.) than the second half 
(5.4 vols. per cent.). The difference in the percentage of gases gives rise to a 
diffusion of the gases within the air passages; the C02 must diffuse from the 
air-vesicles outwards, and the O from the atmosphere and nostrils inwards 
(§ 33)- This movement is aided by the cardio-pneumatic movement (§ 59). In 
hibernating animals and in persons apparently but not actually dead, the 
exchange of gases within the lungs can only occur in the above-mentioned 
ways. For ordinary purposes this mechanism is insufficient, and there are 
added the respiratory movements whereby atmospheric air is introduced into 
the larger air-passages, from which and into which the diffusion currents of O 
and C02 pass, on account of the difference of tension of the gases. 
129. EXCHANGE OF GASES IN THE AIR-VESICLES.— 
The exchange of gases between the gases of the blood and those in the air- 
vesicles occurs almost exclusively through the agency of chemical processes, 
and therefore independently of the diffusion of gases. 
Method.—It is important to ascertain the tension of the O and C02 in the venous blood of 
the pulmonary capillaries. Pfliiger and Wolfberg estimated the tension by “ catheterizing the 
lungs.” An elastic catheter was introduced through an opening in the trachea of a dog into 
the bronchus leading to the lowest lobe of the left lung. An elastic sac was placed round the 
catheter, and when the latter was introduced into the bronchus, the sac around the catheter 
was distended so as to plug the bronchus. No air could escape between the catheter and the 
wall of the bronchus. The outer end of the catheter was closed at first, and the dog was 
allowed to respire quietly. After four minutes the air in the air-vesicles was completely in 
equilibrium with the blood-gases. The air of the lung was sucked out of the catheter by means 
of an air-pump, and afterwards analyzed. 
Thus we may measure indirectly the tension of the O and C02 in the venous 
blood of the pulmonary capillaries. The direct estimation of the gases in dif- 
ferent kinds of blood is made by shaking up the blood with another gas. The 
gases so removed indicate directly the proportion of blood-gases. 
The following statement shows the tension and percentage of O and C02 in 
arterial and venous blood, in the atmosphere, and in the air of the alveoli : — 
I. 
O-Tension in arterial blood == 29.6 mm. Hg 
(corresponding to a mixture containing 3.9 
vol. per cent, of O). 
II. 
C02-Tension in arterial blood — 21 mm. Hg 
(corresponding to 2.8 vol. per cent.). 
III. 
O-Tension in venous blood = 22 mm. Hg 
(corresponding to 2.9 vol. per cent.). 
IV. 
Co2-Tension in venous blood = 41 mm. Hg 
(corresponding to 5.4 vol. per cent.). 
V. 
0-Tension in the air of the alveoli of the 
catheterized lung = 27.44 mm. Hg (cor- 
responding to 3.6 vol. per cent.). 
VI. 
C02-Tension in the air of the alveoli of the 
catheterized lung = 27 mm. Hg (corre- 
sponding to 3.56 vol. per cent.). 
VII. 
O-Tension in the atmosphere = 158 mm. Hg 
(corresponding to 20.8 vol. per cent.). 
VIII. 
C02-Tension in the atmosphere = 0.38 mm. 
Hg (corresponding to 0.03-0.05 vol. per 
cent.). [Sec. 129. 
226 
CHANGES IN THE AIR AND BLOOD IN THE LUNGS. 
When we compare the tension of the O in the air (VII = 158 mm. Hg) with 
the tension of the O in venous blood (III = 22 mm. Hg, or V = 27.44 mm. 
Hg), we might be inclined to assume that the passage of the O from the air of 
the air-vesicles into the blood was due solely to diffusion of the gases; and 
similarly, we might assume that the C02 of the venous blood (IV or VI) dif- 
fused into the air-vesicles, because the tension of the C02 in the air is much 
less (VIII). There are a number of facts, however, which prove that the 
exchange of the gases in the lungs is chiefly due to chemical forces. 
[Von Fleischl finds that fluids yield up their gases very much more easily when they receive a 
shock, and he regards the shock communicated to the blood, by the contraction of the heart, as 
an important factor in preparing the blood for the diffusion of C02 from the blood-plasma into 
the lungs. No facts support this theory as applied to the human body.] 
[Changes produced in the Blood by Respiration.—The blood of the 
pulmonary artery is changed from venous into arterial blood (§ 39), the most 
obvious alterations being (1) the change in color from dark crimson to bright 
scarlet. (2) It loses C02. (3) It gains O. (4) The reduced Hb of the ven- 
ous blood is converted into Hb02. (5) As to a supposed difference of tem- 
perature, see § 209, 3. (6) Pawlow finds that blood which passes several times 
through the lungs loses its power of coagulation. Are we to assume that the 
pulmonary tissues have the property of destroying the fibrin-ferment ?] 
1. Absorption of O.—Concerning the absorption of O from the air in 
the alveoli into the venous blood of the lung-capillaries, whereby the blood is 
arterialized, it is proved that this is a chemical process. The gas-free 
(reduced) haemoglobin takes up O to form oxyhaemoglobin (§ 15, 1). That 
this absorption has nothing to do directly with the diffusion of gases, but is 
due to a chemical combination of the atomic compounds, is shown by the fact 
that, when pure O is respired, the blood does not take up more O than when 
atmospheric air is respired ; further, that animals made to breathe in a limited 
closed space can absorb almost all the O—even to traces—into their blood 
before suffocation occurs. Of course, if the absorption of O were due to dif- 
fusion, in the former case more O would be absorbed, while in the latter case 
the absorption of O could not possibly occur to such an extent as it does. The 
law of diffusion comes into play in connection with the absorption of O to 
this extent, viz., that the O diffuses from the air-cells of the lung into the blood- 
plasma, where it reaches the blood-corpuscles floating in the plasma. The 
haemoglobin of the blood-corpuscles forms at once a chemical compound 
(oxyhaemoglobin) with the O. 
Even in very rarefied air, such as is met with in the upper regions of the atmosphere during 
a balloon ascent, the absorption of O still remains independent of the partial pressure. But a 
much longer time is required for this process at the ordinary temperature of the body, so that 
in rarefied air the absorption of O is greatly delayed, but it is not diminished. This is the cause 
of death in aeronauts who have ascended so high that the atmospheric pressure is diminished to 
one-third (,Setschenow). 
2. Elimination of C02.—With regard to the excretion of C02 from the 
blood, we must remember that the C02 in the blood exists in two conditions. 
Part of the C02 forms a loose or feeble chemical compound, while another por- 
tion is more firmly combined. The former is obtained by those means which 
remove gases from fluids containing them in a state of absorption, so that in 
removing the C02 from the blood it is difficult to determine whether the C02 
so removed obeyed the law of diffusion, or if it was expelled by chemical 
means. 
Although it is convenient to represent the excretion of C02 from the blood 
into the air-vesicles of the lung as due to equilibration of the tension of the 
C02 on opposite sides of the alveolar membrane, i. e., to diffusion—neverthe- Sec. 129.] 
DISSOCIATION OF GASES. 
227 
less, chemical processes play an important part in this act. The absorp- 
tion of O by the colored corpuscles acts, at the same time, in expelling C02. 
This is proved by the fact that the expulsion of C02 from the blood takes place 
more readily when O is simultaneously admitted. The free supply of O not 
only favors the removal of the C02 which is loosely combined, but it also favors 
the expulsion of that portion of the C02 which is more firmly combined, and 
which can only be expelled by the addition of acids to the blood. That the 
oxygenated blood-corpuscles (i. e., their oxyhaemoglobin) are concerned in the 
removal of C02 is proved by the fact that C02 is more easily removed from 
serum which contains oxygenated blood-corpuscles than from serum charged 
with O. 
[The following scheme may serve to illustrate the extent to which diffusion 
comes into play. The O must pass through the alveolar membrane, A B—in- 
cluding the alveolar epithelium and the wall of the capillaries—as well as the 
blood-plasma, to reach the haemoglobin of the blood-corpuscles. Similarly, 
the C02 must leave the salts of the plasma with which it is in combination, and 
diffuse in the opposite direction, through the wall of the capillaries, the alveolar 
membrane, and epithelium, to reach the air-vesicles. Let A B represent the 
alveolar membrane ; on the one side of it is represented the partial pressure of 
the C02 and O in the air-vesicles; and on the other, the partial pressure of the 
C02 and O in the venous blood entering the lung. The arrows indicate the 
direction of diffusion.] 
co2 o 
27 27.44 
Partial pressure of air in 
alveoli of lung. 
Tension of gases in venous 
blood of lung. 
A 1 T ¥ B 
41 22 
C02 . O 
Nature of the Process.—The exchange of gases between the blood and 
the air in the lungs has been represented by Donders as due to the process of 
dissociation. 
[Bohr used a modified rheometer of Ludwig’s, whereby living arterial blood was brought into 
direct contact with a volume of air containing a greater or less percentage of C02. Even when 
the amount of C02 in the air in direct contact with the blood was very small, it was found that 
very little C02 diffused from the blood into the air-space. Bohr therefore concludes that the 
separation of C02 from the venous blood in the lungs, and its passage into the air-vesicles, are 
not explicable on the hypothesis of diffusion, but we must rather regard the C02 as removed from 
the blood by the pulmonary tissue by means of a kind of secretory process, analogous to the 
excretion-processes in glands.] 
130. DISSOCIATION OF GASES.—Many gases form true chemical 
compounds with other bodies (i. e., they combine according to their equivalents), 
when the contact of these bodies is effected under conditions such that the 
partial pressure of the gases is high. The chemical compound formed under 
these conditions is broken up whenever the partial pressure is diminished, or 
when it reaches a certain minimum level, which varies with the nature of the 
bodies forming the compound. Thus, by increasing and diminishing the par- 
tial pressure alternately, a chemical compound of the gas may be formed and 
again broken up. This process is called dissociation of the gases. The 
minimal partial pressure is constant for each of the different substances and 
gases, but temperature, as in the case of the absorption of gases, has a great 
effect on the partial pressure; with increase of temperature the partial pressure, 
under which dissociation occurs, diminishes. 
As an example of the dissociation of a gas, take the case of calcium carbonate. When it is 
heated in the air to 440° C., C02 is given off from its state of chemical combination, but is taken 
up again, and a chemical compound formed, which is changed into chalk when it cools. [Sec. 130. 
228 
CUTANEOUS RESPIRATION. 
Dissociation in the Blood.—The chemical combinations containing C02 
and those containing O within the blood-stream, viz., the salts of the plasma, 
which are combined with C02, and the oxyhsemoglobin, behave in a similar 
manner. If these compounds of O and C02are placed under conditions where 
the partial pressure of these gases is very low—i. e., in a medium containing a 
very small amount of these gases, the compounds are dissociated, i. e., they 
give off C02 or O. If after being dissociated they are placed under conditions 
where, owing to the large amount of these gases, the partial pressure of O or 
of C02 is high, these gases are taken up again, and enter into a condition of 
chemical combination. 
The haemoglobin of the blood in the pulmonary capillaries finds plenty of 
O in the alveoli; hence, it unites with the O owing to the partial pressure of 
the O in the lung, and so forms the compound oxyhsemoglobin. On its 
course through the capillaries of the systemic circulation, the oxyhsemoglobin 
of the blood comes into relation with tissues poor in O ;' the oxyhsemoglobin 
is dissociated, the O is supplied to the tissues, and the blood freed from this O 
returns to the right heart, and passes to the lungs, where it takes up the new O. 
The blood whilst circulating meets with most C02 in the tissues; the high 
partial pressure of the C02 in the tissues causes C02 to unite with certain con- 
stituents in the blood so as to form chemical compounds, which carry the C02 
from the tissues to the lungs. In the air of the lungs, however, the partial 
pressure of the C02 is very low, dissociation of these chemical compounds 
occurs under the low partial pressure, and the C02 passes into the air-cells of 
the lung, from which it is expelled during expiration. It is evident that the 
giving up of O from the blood to the tissues, and the absorption of C02 from 
the tissues, go on side by side and take place simultaneously, while in the lungs 
the reverse processes occur almost simultaneously. 
131. CUTANEOUS RESPIRATION.—Methods.—If a man or an animal be placed in 
the chamber of the respiratory apparatus (§ 122), and if tubes be so arranged that the respiratory 
gases do not enter the chamber, of course we obtain only the “perspiration ” of the skin in the 
chamber. It is less satisfactory to leave the head of the person outside the chamber, while the 
neck is fixed air-tight in the wall of the chamber. The extent of the cutaneous respiration of 
a limb may be ascertained by enclosing it in an air tight vessel (Rohrig) similar to that used for 
the arm in the plethysmograph (§ 101). 
Loss by Skin.—A healthy man loses by the skin, in 24 hours, of his 
body-weight, which is greater than the loss by the lungs, in the ratio of 3:2. 
Only 10 grams—150 grains,—or it may be 3.9 grams—60 grains,—of the entire 
loss are due to the C02 given off by the skin. The remainder of the excretion 
from the skin is due to water lbs. daily] containing a few salts in solu- 
tion. When the surrounding temperature is raised, the C02 is increased, in 
fact it may be doubled ; violent muscular exercise has the same effect. 
O Absorbed.—The O taken up by the skin is either equal to, or slightly 
less than, the C02 given off. As the C02 excreted by the skin is only of 
that excreted by the lungs, while the O taken in = of that taken in by the 
lungs, it is evident that the respiratory activity of the skin is very slight. Animals 
whose skin has been covered by an impermeable varnish die, not from suffoca- 
tion, but from other causes (§ 225). 
In animals with a thin moist epidermis (frog) the exchange of gases is much greater, and in 
them the skin so far supports the lungs in their function, and may even partly replace them 
functionally. The skin of the frog eliminates °f ah the C02 excreted (Bidder), and even 
a larger proportion in winter frogs. Thus dipping a frog in oil kills it sooner than ligature of 
the lungs. In mammals with thick dry cutaneous appendages, the exchange of gases is, 
again, much less than in man. 
132. INTERNAL RESPIRATION.—Where C02 is formed.— 
By the term “internal respiration” is understood the exchange of gases Sec. 132.] 
INTERNAL RESPIRATION. 
229 
between the capillaries of the systemic circulation and the tissues of the organs 
of the body. As organic constituents of the tissues, during their activity, 
undergo gradual oxidation, and form, amongst other products, C02, we may 
assume—(1) that the chief focus for the absorption of O and the formation of 
C02 is to be sought for within the tissues themselves. That the O from the 
blood in the capillaries rapidly penetrates or diffuses into the tissues is shown 
by the fact that the blood in the capillaries rapidly loses O and gains C02, 
while blood containing O, and kept warm outside the body, changes very slowly 
and incompletely. If portions of fresh tissues 'be placed in defibrinated blood 
containing O, then the O rapidly disappears. Frogs deprived of their blood 
exhibit an exchange of gases almost as great as normal. This shows that the 
exchange of gases must take place in the tissues themselves. If the chief 
oxidations took place in the blood and not in the tissues, then during suffoca- 
tion, when O is excluded, the substances which use up O, i. e., those sub- 
stances which act as reducing agents, ought to accumulate in the blood. But this 
is not the case, for the blood of asphyxiated animals contains mere traces of 
reducing materials (.Pflilger). It is difficult to say how the O is absorbed by 
the tissues, and what becomes of it immediately it comes in contact with the 
living elements of the tissues. Perhaps it is temporarily stored up, or it may 
form certain intermediate less oxidized compounds. This may be followed by 
a period of rapid formation and excretion of C02. On this supposition, it is 
evident that the absorption of O and the excretion of C02 need not occur to 
the same extent, so that the amount of C02 given off at any period is not 
necessarily an index of the amount of O absorbed during the same period 
(§127). 
[Oxygen exists in excessively small quantities in the tissues, so that its tension 
may be considered as nearly zero : thus the O of the blood must diffuse towards 
the tissues. If two fingers touching each other be held in front of a bright 
light, then by means of a spectroscope placed opposite the interval between 
them, one can see the two bands of oxyhaemoglobin. If the bases of the 
fingers be constricted the single band of reduced haemoglobin appears in less 
than two minutes, so rapidly is the blood robbed of its oxygen. The C02 
formed in the tissues diffuses towards the blood. The following scheme after 
Beaunis represents the decrease in tension of the two gases:— 
O—Atmosphere>air in lungs>blood>tissues. 
C02—Tissues>blood>air in lungs>atmosphere.] 
[There are two views as to where the C02 is formed as the blood passes through 
the tissues. One view is that the seat of oxidation is in the blood itself, and 
the other is that it is formed in the tissues. If we knew the tension of the gases 
in the tissues, the problem would be easily solved, but we can only arrive at a 
knowledge of this subject indirectly in the following ways] :— 
CO,2 in Cavities.—That the C02 is formed in the tissues is supported by the fact that the 
amount of C0.2 in the fluids of the cavities of the body is greater than the C02 in the blood of 
the capillaries. The tension of C02 in— 
mm. 
Arterial blood, 21.28 Hg tension. 
Peritoneal cavity, .... 58.5 “ “ 
Acid urine, 68.0 1 “ “ 
Cavity of intestine, . . . 58.5 “ “ 
mm. 
Bile (gall bladder), .... 50.0 Hg tension. 
Hydrocele fluid, 46.5 *• “ 
Lymph (thoracic duct), . . 34.0 “ 
(.Pfluger and Strassburg.) 
The la.rge amount of C02 in these fluids can only arise from the C02 of the tissues passing 
into them. OXIDATION TAKES PLACE IN THE TISSUES. 
[Sec. 132. 
Gases of Lymph.—The following table shows the amount of gases in lymph:— 
O 
C02 
N 
Lymph from arm, 
0.00 
O.IO 
41.89 
47-13 
1.12 
I.58 
Lymph from intestine, 
O.IO 
37-55 
I.63 
In the lymph of the ductus thoracicus the tension of 0O2 = 33.4 to 37.2 mm. Hg, 
which is greater than in arterial blood, but considerably less than in venous blood (41.0 
mm. Hg). (Ludwig and Hammarsten, Tschirjew). This does not entitle us to conclude 
that in the tissues from which the lymph comes only a small quantity of C02 is formed, but 
rather that in the lymph there is less attraction for the C02 formed in the tissues than in the 
blood of the capillaries, where chemical forces are active in causing it to combine, or that in the 
course of the long lymph-current, the C02 is partly given back to the tissues, or that C02 is 
formed in the blood itself. Further, the muscles, which are by far the largest producers of C02, 
contain few lymphatics, nevertheless they supply much C02 to the blood. The amount of free 
“non-fixed” C02 contained in the juices and tissues indicates that the C02 passes from the 
tissues into the blood; still, Preyer believes that in venous blood C02“undergoes chemical com- 
bination. The exchange of O and C02 varies much in the different tissues. The muscles are 
the most important organs, for in their active condition they excrete a large amount of C02, and 
use up much O. The O is so rapidly used up by them that no free O can be pumped out of 
muscular tissue (Z. Hermann). The exchange of gases is more vigorous during the activity 
of the tissues. Nor are the salivary glands, kidneys, and pancreas any exception, for although, 
when these organs are actively secreting, the blood flows out of the dilated veins in a bright red 
stream, still the relative diminution of C02 is more than compensated by the increased volume 
of blood which passes through these organs. 
Reduction by the tissues.—The researches of Ehrlich have shown that in most tissues very 
energetic reductions take place. If coloring-matters, such as alizarin blue, indophenol blue, 
or methyl blue, be introduced into the blood stream, the tissues are colored by them. Those 
tissues or organs which have a particular affinity for O (e.g., liver, cortex of the kidney, and 
lungs), absorb O from these pigments, and render them colorless. The pancreas and sub- 
maxillary gland scarcely reduce them at all. 
(2) In the blood itself, as in all tissues, O is used up and C02 is formed. 
This is proved by the following facts: That blood withdrawn from the body 
becomes poorer in O and richer in C02; that in the blood of asphyxia, free 
from O and in the blood-corpuscles, there are slight traces of reducing agents, 
which become oxidized on the addition of O. Still, this process is compara- 
tively insignificant as against that which occurs in all other tissues. That the 
walls of the vessels—more especially the muscular fibres in the walls of the 
small arteries—use O and produce C02 is unquestionable, although the exchange 
is so slight that the blood in its whole arterial course undergoes no visible 
change. 
Ludwig and his pupils have proved that C02 is actually formed in the blood. If the easily 
oxidizable lactate of soda be mixed with blood, and this blood be caused to circulate in an excised 
but still living organ, such as a lung or kidney, more O is used up and more C02 is formed than 
in unmixed blood similarly transfused. 
(3) That the tissues of the living lungs use O and give off C02 is probable. 
When C. Ludwig and Muller passed arterial blood through the blood-vessels of 
a lung deprived of air, the O was diminished and the C02 increased. As the total 
amount of C02 and O found in the entire blood, at any one time, is only 4 grams, 
and as the daily excretion of C02 = 900 grams, and the O absorbed daily = 744 
grams, it is clear that exchange of gases must go on with great rapidity, that 
the O absorbed must be used quickly, and the C02 must be rapidly excreted. 
Still, it is a striking fact that oxidation-processes of such magnitude, as e.g., the union of C 
to form C02, occur at a relatively low temperature of the blood and the tissues. It has been 
surmised that the blood acts as an ozone-producer, and transfers this active form of O to the 
tissues. Liebig showed that the alkaline reaction of most of the juices and tissues favors the Sec. 132.] 
COMPARATIVE PHYSIOLOGY OF RESPIRATION. 
231 
processes of oxidation. Numerous organic substances, which are not altered by O alone, 
become rapidly oxidized in the presence of free alkalies, e.g., gallic acid, pyrogallic acid, and 
sugar; while many organic acids, which are unaffected by ozone alone, are changed into 
carbonates when in the form of alkaline salts {Gorup-Besanez); and in the same way, when 
they are introduced into the body in the form of acids, they are partly or wholly excreted in the 
urine, but when they are administered as alkaline compounds they are changed into carbonates. 
[Comparative Physiology of Respiration.—The most important re- 
searches in this department have been made by Regnault and Reiset and Paul 
Bert. The following table shows the quantity of O absorbed, C02 and N 
excreted by the respiratory organs per kilo.-weight of the animal during one 
hour:— 
0 Absorbed. 
C02 Excreted. 
N Excreted. 
grms. 
grms. 
grms. 
Rabbit, 
0.883 
1.109 
0.004 
Dog, 
1.183 
1195 
0.007 
Marmot, 
0.986 
1.016 
0.009 
Fowl,. . 
1-035 
1.368 
0.007 
Sparrow, ... .... 
9-595 
10.583 
0.008 
Lizard, . . ... 
0.191 
0.197 
0.004 
Frog, 
0.090 
0.091 
0.000 
Salamander, 
0.085 
0.113 
0.000 
Cockchafer, 
0.019 
I-I37 
t-^ 
00 
0 
d 
[It is evident that the respiration of birds is much more active than that of 
mammals, while in mammals and insects it is far more active than in reptiles 
and amphibians. The respiration of fishes is much less active than that of 
mammals.] 
[The respiratory quotient shows a marked difference in carnivora and 
herbivora; in herbivora = 0.9-1, in carnivora — o. 75-0.8, while the omnivora, 
e.g., man, stands midway between = 0.87, but it is increased by carbohydrate 
food, and diminished by animal food. In starving animals, however, the re- 
spiratory quotient is the same = 0.75, showing that the oxidation in starving 
animals takes place at the expense of the tissues of the body (Munk).~\ 
[The species of animal exercises a marked influence on the intensity of 
the respiratory process, as shown by the following table from Munk, giving 
the amount of O absorbed per unit weight (/. e., per kilogram) of the animal. 
It is at once apparent that the intensity of respiration is not parallel to the 
body-weight:— 
Species of Animal. 
O in Grams. Absorbed. 
Respiratory Quotient, Fy 2~ 
Cat, 
1.007 
O.77 
F>og, 
I.183 
0-75 
Rabbit, 
O.918 
O.92 
Fowl, 
1.30° 
o-93 
Small Singing-bird . 
II.360 
0.78 
Frog 
O.084 
0.63 
Man, 
O.417 
0.87 
Horse, 
0.563 
0.97 
Ox, 
0.552 
0.9 
Sheep, • 
O.49 
0.98] 
[Small animals, as a rule, have the greatest intensity of respiration ; birds 
have the most intense respiration, and this is greater the smaller the bird. Thus 
small singing-birds use nearly ten times as much oxygen as fowls. In cold- [Sec. 132. 
232 
RESPIRATION IN A LIMITED SPACE. 
blooded animals it is exceedingly small. A guinea-pig placed in a chamber 
containing little oxygen within a short time becomes convulsed and dies, while 
a frog will live for many hours in an atmosphere devoid of oxygen (Munk').~\ 
133. RESPIRATION IN A LIMITED SPACE.—Respiration in a 
limited space causes—(1) a gradual diminution of O ; (2) a simultaneous 
increase of C02; (3) a diminution in the volume of the gases. If the space be 
of moderate dimensions, the animal uses up almost all the O contained 
therein, and dies ultimately from spasms caused by the asphyxia. The O is 
absorbed, therefore—independently of the laws of absorption—by chemical 
means. The O in the blood is almost completely used up (§ 129). In a 
larger space, the C02 accumulates rapidly, before the diminution of O is 
such as to affect the life of the animal. As C02 can only be excreted from the 
blood when the tension of the C02 in the blood is greater than the tension 
of C02 in the air, as soon as the C02 in the surrounding air in the closed space 
becomes the same as in the blood, the C02 will be retained in the blood, and 
finally C02 may pass back into the body. This occurs in a large closed space, 
when the amount of O is still sufficient to support life, so that death occurs 
under these circumstances (in rabbits) through poisoning with C02 causing 
diminished excitability, loss of consciousness, and lowering of temperature, but 
no spasms ( Worm Muller). In pure O animals breathe in a normal way; the 
quantity of O absorbed and the C02 excreted is quite independent of the per- 
centage of O, so that the former occurs through chemical agency independent 
of pressure. In a limited space filled with O animals die by absorption of the 
C02 excreted. Worm Muller found that rabbits died after absorbing C02 equal 
to half the volume of their body, although the air still contained 50 per cent. 
O. Animals can breathe quite quietly a mixture of air containing 14.8 per 
cent. (20.9 per cent, normal) ; with 7 per cent, they breathe with difficulty ; 
with 4.5 per cent, there is marked dyspnoea; with 3 per cent. O there is toler- 
ably rapid asphyxia. The air expired by man normally contains 14 to 18 per 
cent. O. According to Hempner, mammals placed in a mixture of gases poor 
in O use slightly less O. 
Dyspnoea occurs when the respired air is deficient in O, as well as when it is overcharged with 
C02, but the dyspnoea in the former case is prolonged and severe; in the latter, the respiratory 
activity soon ceases. The want of O causes a greater and more prolonged increase of the blood- 
pressure than is caused by excess of C02. Lastly, the consumption of O in the body is less 
affected when the O in the air is diminished than when there is excess of C02. If air containing 
a diminished amount of O be respired, death is preceded by violent phenomena of excitement 
and spasms, which are absent in cases of death caused by breathing air over-charged with C02. 
In poisoning with C02, the excretion of C02 is greatly diminished, while with diminution of O it 
is almost unchanged. 
If animals be supplied with a mixture of gases similar to the atmosphere, in 
which N is replaced by H, they breathe quite normally (.Lavoisier and Seguin') ; 
the H undergoes no great change. 
Cl. Bernard found that, when an animal breathed in a limited space, it became partially 
accustomed to the condition. On placing a bird under a bell-jar, it lived several hours; but 
if several hours before its death, another bird fresh from the outer air were placed under the 
same bell-jar, the second bird died soon, with convulsions. 
Frogs, when placed for several hours in air devoid of O, give off just as much C02 as in air 
containing O, and they do this without any obvious disturbance. Hence, it appears that the 
formation of C02 is independent of the absorption of O, and the C02 must be formed from the 
decomposition of other compounds. Ultimately, however, complete motor paralysis occurs, 
whilst the circulation remains undisturbed (Aubert). 
[134. DYSPNCEA AND ASPHYXIA. —For the causes of dyspnoea see 
§ hi, and those of asphyxia see § 368. If from any cause an animal be not 
supplied with a due amount of air, normal respiration becomes greatly altered, Sec. 134.] 
DYSPNCEA AND ASPHYXIA. 
passing through the phases of hyperpncea, or increased respiration, dyspnoea, 
or difficulty of breathing, to the final condition of suffocation or asphyxia. 
The phenomena of asphyxia may be developed by closing the trachea of an 
animal with a clamp, or by any means which prevents the entrance of air or 
blood into the lungs. 
The phenomena of asphyxia are usually divided into several stages :—i. 
During the first stage there is hyperpncea, the respirations being deeper, more 
frequent, and labored. The extraordinary muscles of respiration—both those 
of inspiration and expiration (§ 118)—are called into action, dyspnoea is rapidly 
produced, and the struggle for air becomes more and more severe. At the same 
time the oxygen of blood is being used up, while the blood itself becomes 
more and more venous. The venous blood circulating in the medulla oblon- 
gata and spinal cord stimulates the respiratory centres, and causes the violent 
respirations. This stage usually lasts about a minute, and gradually gives place 
to— 
2. The second stage, when the inspiratory muscles become less active,, 
while those concerned in labored expiration contract energetically, and indeed 
almost every muscle in the body may contract; so that this stage of violent 
expiratory efforts ends in general convulsions. The convulsions are due to 
stimulation of the respiratory centres by the venous blood. The convulsive 
stage is short, and is usually reached in a little over one minute. This storm is 
succeeded by— 
3. The third stage, or stage of exhaustion, the transition being usually 
somewhat sudden. It is brought about by the venous blood acting on and 
paralyzing the respiratory centres. The pupils are widely dilated, consciousness 
is abolished, and the activity of the reflex centres is so depressed that it is im- 
possible to discharge a reflex act, even from the cornea. The animal lies almost 
motionless, with flaccid muscles, and to all appearance dead, but every now 
and again, at long intervals, it makes a few deep inspiratory efforts, showing 
that the respiratory centres are not quiet, but almost paralyzed. Gradually the 
pauses become longer and the inspirations feebler and of a gasping character. 
As the venous blood circulates in the spinal cord, it causes a large number of 
muscles to contract, so that the animal extends its trunk and limbs. It makes, 
one great inspiratory spasm, the mouth being widely opened and the nostrils 
dilated, and ceases to breathe. After this stage, which is the longest and most 
variable, the heart becomes paralyzed, partly from being over-distended with 
venous blood, and partly, perhaps, from the action of the venous blood on the 
cardiac tissues, so that the pulse can hardly be felt. To this pulseless condi- 
tion the term “ asphyxia” ought properly to be applied. In connection with 
the resuscitation of asphyxiated persons, it is important to note that the heart 
continues to beat for a few seconds after the respiratory movements have 
ceased. 
The whole series of phenomena occupies from 3 to 5 minutes, according to 
the animal operated on, and depending also upon the suddenness with which 
the trachea was closed. If the causes of suffocation act more slowly, the phe- 
nomena are the same, only they are developed more slowly. 
The Circulation.—The post-mortem appearances in man or in an 
animal are generally well marked. The right side of the heart, the pulmonary 
artery, the venae cavae, and the veins of the neck are engorged with dark ven- 
ous blood. The left side is comparatively empty. If the veins on the right 
side, or the right side of the heart, be pricked, the blood spurts out. Most ob- 
servers are agreed that the left side of the heart is comparatively empty, al- 
though they are not in accord as to its cause. Some observers ascribe it to the 
rigor mortis of the left side of the heart, and the elastic recoil of the systemic [Sec. 134. 
234 
BLOOD-PRESSURE IN ASPHYXIA. 
arteries, forcing the blood towards the systemic veins. G. Johnson ascribes 
the engorgement of the right side to spasm of the pulmonary arterioles. The 
blood itself is almost black, and is deprived of almost all its oxygen, its 
haemoglobin being nearly all in the condition of reduced haemoglobin, while 
ordinary venous blood contains a considerable amount of oxyhaemoglobin 
as well as reduced Hb. The blood of an asphyxiated animal practically con- 
tains none of the former and much of the latter. The spectrum of blood 
from an asphyxiated animal, where all oxygen has been used up, is that of 
reduced haemoglobin (p. 26). It is important to study the changes in the cir- 
culation in relation to phenomena exhibited by an animal during suffocation. 
We may measure the blood-pressure in any artery of an animal while it is 
being asphyxiated, or we may open its chest, maintain artificial respiration, and 
place a manometer in a systemic artery, e. g., the carotid, and another in a 
branch of the pulmonary artery. In the latter case, we can watch the order of 
events in the heart itself, when the artificial respiration is interrupted. It is 
well to study the events in both cases. 
If the blood-pressure be measured in a systemic artery, e. g., the caro- 
tid, it is found that the blood-pressure rises very rapidly, and to a great extent 
during the first and second stages; the pulse-beats at first are quicker, but soon 
become slower and more vigorous. During the third stage it falls rapidly to 
zero. The great rise of the blood-pressure, during the first and second stages, 
is chiefly due to the action of the venous blood on the general vaso-motor 
centre, causing constriction of the small systemic arteries. The peripheral 
resistance is thus greatly increased, and it tends to cause the heart to contract 
more vigorously, but the slower and more vigorous beats of the heart are also 
partly due to the action of the venous blood on the cardio-inhibitory centre in 
the medulla. 
If the second method be adopted, viz., to open the chest, keep up artificial 
respiration, and measure the blood-pressure in a branch of the pulmonary artery, 
as well as in a systemic artery,—e. g., the carotid,—we find that when the arti- 
ficial respiration is stopped, in addition to the rise of the blood-pressure indi- 
cated in the carotid manometer, the cavities of the heart and the large veins 
near it are engorged with venous blood. There is, however, but a slight com- 
parative rise in the blood-pressure in the pulmonary artery ; while the sys- 
temic pressure may be doubled, the pulmonary artery pressure may be only 
raised a few millimetres (p. 153). This may be accounted for, either by the 
pulmonary artery not being influenced to the same extent as other arteries by 
the vaso-motor centre, or by its greater distensibility (§ 88). But, as the heart 
itself is supplied through the coronary arteries with venous blood, its action 
soon becomes weakened, each beat becomes feebler, so that soon the left ven- 
tricle ceases to contract, and is unable to overcome the great peripheral resist- 
ance in the systemic arteries, although the right ventricle may still be con- 
tracting. As the blood becomes more venous, the vaso-motor centre becomes 
paralyzed, the small systemic arteries relax, and the blood flows from them into 
the veins, while the blood-pressure in the carotid manometer rapidly falls. The 
left ventricle, now relieved from the great internal pressure, may execute a few 
feeble beats, but they can only be feeble, as its tissues have been subjected to 
the action of the very impure blood. More and more blood accumulates in the 
right side from the causes already mentioned. The violent inspiratory efforts 
in the early stages aspirate blood from the veins towards the right side of the 
heart, but of course this factor is absent when the chest is opened.] 
[Convulsions during asphyxia occur only in warm-blooded animals, and 
not in frogs. If a drug when injected into a mammal excites convulsions, but 
does not do so in the frog, then it is usually concluded that the convulsions are Sec. 134.] 
ARTIFICIAL RESPIRATION. 
235 
due to its action on the circulation and respiration, and not to any direct 
stimulating effect upon the motor centres. But if the drug excites convulsions 
both in the mammal and frog, then it probably acts directly on the motor cen- 
tres (Brunton).~\ 
[Recovery from the condition of Asphyxia.—If the trachea of a dog be closed sud- 
denly and completely, the average duration of the respiratory movements is 4 minutes 5 seconds, 
while the heart continues to beat for about 7 minutes. Recovery may be obtained if proper 
means be adopted before the heart ceases to beat; but after this, never. If a dog be drowned, 
the result is different. After complete submersion for 1 minute, recovery did not take place. 
In drowning, air passes out of the chest, and water is inspired into and fills the air-vesicles. It 
is rare for recovery to take place in a person deprived of air for more than five minutes. If the 
statements of sponge-divers are to be trusted, a person may be accustomed to the deprival of air 
for a longer time than usual. In cases where recovery takes place after a much longer period of 
submersion, it has been suggested that, in these cases, syncope occurs, the heart beats but feebly 
or not at all, so that the oxygen in the blood is not used up with the same rapidity. It is a well- 
known fact that newly-born and young puppies can be submerged for a long time before they 
are suffocated. Young mammals in which the eyes remain closed for some time after birth survive 
submersion for a much longer time than the same class of animals a few days older, the reason 
being that in the former the foramen ovale and ductus arteriosus are still patent, while in the latter 
they are closed.] 
Artificial Respiration in Asphyxia.—Incases of suspended animation, artificial respiration 
must be performed. The first thing to be done is to remove any foreign substance from the 
respiratory passages (mucus or oedematous fluids) in the newly-born or asphyxiated. In doubt- 
ful cases, open the trachea and suck out any fluid by means of an elastic catheter (v. Hilter). 
Recourse must in all cases be had to artificial respiration. There are several methods of dilating 
and compressing the chest so as to cause an exchange of gases. One method is to compress the 
chest rhythmically with the hands. 
[Marshall Hall’s Method.—“ After clearing the mouth and throat, place the patient on the 
face, raising and supporting the chest well on a folded coat or other article of dress. Turn the 
body very gently on the side and a little beyond, and then briskly on the face, back again, 
repeating these measures cautiously, efficiently, and perseveringly, about fifteen times in the 
minute, or once every four or five seconds, occasionally varying the side. By placing the 
patient on the chest, the weight of the body forces the air out; when turned on the side this 
pressure is removed, and air enters the chest. On each occasion that the body is replaced on 
the face, make uniform but efficient pressure with brisk movement on the back between and 
below the shoulder-blades or bones on each side, removing the pressure immediately before 
turning the body on the side. During the whole of the operations let one person attend solely 
to the movements of the head and of the arm placed under it.”] 
[Sylvester’s Method.—“ Place the patient on the back on a flat surface, inclined a little 
upwards from the feet; raise and support the head and shoulders on a small firm cushion or 
folded articles of dress placed under the shoulder-blades. Draw forward the patient’s tongue, 
and keep it projecting beyond the lips; an elastic band over the tongue and under the chin 
will answer this purpose, or a piece of string or tape may be tied round them, or by raising the 
lower jaw the teeth may be made to retain the tongue in that position. Remove all tight 
clothing from about the neck and chest, especially the braces.” “ To Imitate the Movements of 
Breathing.—Standing at the patient’s head, grasp the arms just above the elbows, and draw the 
arms gently and steadily upwards above the head, and keep them stretched upwards for two 
seconds. By this means air is drawn into the lungs. Then turn down the patient’s arms, and 
press them gently and firmly for two seconds against the sides of the chest. By this means air 
is pressed out of the lungs. Repeat these measures alternately, deliberately, and perseveringly 
about fifteen times in a minute, until a spontaneous effort to respire is perceived, immediately 
upon which cease to imitate the movements of breathing, and proceed to induce circulation and 
warmth.”] 
Howard advises rhythmical compression of the chest and abdomen by sitting like a rider 
astride of the body, while Schiiller advises that the lower ribs be seized from above with both 
hands and raised, whereby the chest is dilated, especially when the thigh is pressed against the 
abdomen to compress the abdominal walls. The chest is compressed by laying the hands flat 
upon the hypochondria. Artificial respiration acts favorably by supplying O to, as well as 
removing C02 from, the blood; further, it aids the movement of the blood within the heart and 
in the large vessels of the thorax. If the action of the heart has ceased, recovery is impossible. 
In asphyxiated newly-born children, we must not cease too soon to perform artificial respiration. 
Even when the result appears hopeless, we ought to persevere. Pfliiger and Zuntz observed 
that the reflex excitability of the foetal heart continued for several hours after the death of the 
mother. 236 
RESPIRATION OF FOREIGN GASES. 
[Sec. 134. 
Resuscitation by compressing the heart.—Bohm found that in the case of cats poisoned with 
potash salts or chloroform, or asphyxiated, so as to arrest respiration and the action of the 
heart,—even for a period of forty minutes,—and even when the pressure within the carotid had 
fallen to zero, he could restore animation by rhythmical compression of the heart, combined with 
artificial respiration. The compression of the heart causes a slight movement of the blood, 
while it acts at the same time as a rhythmical cardiac stimulus. After recovery of the respira- 
tion, the reflex excitability and gradually also voluntary movements are restored. The animals 
are blind for several days, the brain acts slowly, and the urine contains sugar. These experiments 
show how important it is in cases of asphyxia to act at the same time upon the heart. 
For physiological purposes, artificial respiration is often made use of, especially after 
poisoning with curare. Air is forced into the lungs by means of an elastic bag or bellows, 
attached to a cannula tied in the trachea. The cannula has a small opening in the side of it to 
allow the expired air to escape. 
Pathological.—After the lungs have once been properly distended with air, it is impossible 
by any amount of direct compression of them to get rid of all the air. This is probably due to 
the pressure acting on the small bronchi, so as to squeeze them, before the air can be forced out 
of the air-vesicles. If, however, a lung be filled with C02, and be suspended in water, the C02 
is absorbed by the water, and the lungs become quite free from air and are atelectatic (Hermann 
and Keller). The atelectasis, which sometimes occurs in the lung, may thus be explained : If 
a bronchus is stopped with mucus or exudation, C02 accumulates in the air-vesicles belonging to 
this bronchus. If the C02 is absorbed by the blood or lymph, the corresponding area of the 
lung will become atelectatic. Sometimes there is spasm of the respiratory muscles, brought about 
by direct or reflex stimulation of the respiratory centre. 
135. RESPIRATION OF FOREIGN GASES.—No gas without a 
sufficient admixture of O can support life. Even with completely innocuous and 
indifferent gases, if no O be mixed with them, they cause suffocation in 2 to 3 
minutes. 
I. Completely indifferent Gases are N, H, CH4. The living blood of an animal breathing 
these gases yields no O to them (Pflilger). 
II. Poisonous Gases.—O-displacing Gases.—(«) Those that displace O, and form a 
stable compound with the haemoglobin—(1) CO (§§ 16 and 17). (2) CNH (hydrocyanic acid) 
displaces (?) O from haemoglobin, forming a more stable compound, and kills exceedingly rapidly. 
Blood-corpuscles charged with hydrocyanic acid lose the property of decomposing hydric peroxide 
into water and O (§ 17, 5). 
(£) Narcotic Gases.—(1) C02.—V. Pettenkofer characterizes atmospheric air containing .1 
per cent. C02 as “ bad air ” ; still, air in a room containing this amount of C02 produces a dis- 
agreeable feeling, rather from the impurities mixed with it than from the actual amount of C02 
itself. Air containing I per cent. C02 produces decided discomfort, and with 10 per cent, it 
endangers life, while larger amounts cause death, with symptoms of coma. (2) N20 (nitrous 
oxide), respired, mixed with i volume O, causes, after 1 to 2 minutes, a short temporary stage of 
excitement (“ Laughing gas ” of H. Davy), which is succeeded by unconsciousness, and after- 
wards by an increased excretion of C02. (3) Ozonized air causes similar effects (Binz). 
(c) Reducing Gases.—(1) H2S (sulphuretted hydrogen) rapidly robs blood-corpuscles of 
O—S and H20 being formed—and death occurs rapidly before the gas can decompose the 
haemoglobin to form a sulphur-methaemoglobin compound. (2) PH3 (phosphuretted hydrogen) 
is oxidized in the blood to form phosphoric acid and water, with decomposition of the haemo- 
globin. 
(3) AsH3 (arseniuretted hydrogen) and SbH3 (antimoniuretted hydrogen) act like PH3, but 
the haemoglobin passes out of the stroma and appears in the urine. 
(4) C2N2 (cyanogen) absorbs O, and decomposes the blood. 
III. Irrespirable Gases, i.e., gases which, on entering the larynx, cause reflex spasm of 
the glottis. When introduced into the trachea, they cause inflammation and death. Under this 
category come hydrochloric, hydrofluoric, sulphurous, nitrous, and nitric acids, ammonia, 
chlorine, fluorine, and ozone. 
136. ACCIDENTAL IMPURITIES OF THE AIR.—Amongst 
these are dust-particles, which occur in enormous amount suspended in the 
air, and thereby act injuriously upon the respiratory organs. The ciliated 
epithelium of the respiratory passages eliminates a large number of them. 
Some of them, however, reach the air-vesicles of the lung, where they pene- 
trate the epithelium, reach the interstitial lung-tissue and lymphatics, and so 
pass with the lymph-stream into the bronchial glands. Particles of coal or Sec. 136.] 
IMPURITIES OF THE AIR. 
237 
charcoal are found in the lungs of all elderly individuals, and blacken the 
alveoli. In moderate amount, these black particles do not seem to do any 
harm in the tissues, but when there are large accumulations they give rise to 
lung-affections, which lead to disintegration of these organs. [In coal-miners, 
for example, the lung-tissues along the track of the lymphatics and in the 
bronchial glands are quite black, constituting “coal-miners’ lung.”] The 
lymphatics of the mediastinal pleura can only take up such pigment as reaches 
them from the pleural cavities (Fleiner). In many trades various particles 
occur in the air; miners, grinders, stone-masons, file-makers, weavers, spin- 
ners, tobacco manufacturers, millers, and bakers suffer from lung affections 
caused by the introduction of particles of various kinds inhaled during the time 
they are at work. 
Germs and Micro-organisms.—There seems no doubt that the seeds of 
some contagious diseases may be inhaled. Diphtheritic bacteria (Bacillus 
diphtheriae) become localized in the pharynx and in the larynx—glanders in the 
nose—measles in the bronchi—whooping-cough in the bronchi—hay-monads 
in the nose—the Bacillus pneumoniae of pneumonia in the pulmonary alveoli. 
Tuberculosis, according to R. Koch, is due to the introduction and develop- 
ment of the Bacillus tuberculosis in the lungs, the bacillus being derived from the 
dust of tuberculous sputa. The same seems to be the case with the Bacillus of 
leprosy and with Bacillus malariae, which is the cause of malaria. The latter 
organism, Plasmodium malariae, is endowed with amoeboid movements, and thus 
passes from the respiratory organs into the blood, and changes the Hb within 
the red blood-corpuscles into melanin (§ io, 3), and causes them to break up 
(.Marchiafava and Celli). The Micrococcus vaccinae of smallpox gains access 
to the blood in the same way, also the Spirillum of remittent fever (fig. 32), 
the microbe of scarlet fever, etc. 
Seeds of disease passing into the mouth along with air, and also with the 
food, are swallowed, and undergo development in the intestinal tract, as is 
probably the case in cholera (Comma bacillus of R. Koch), dysentery, typhoid, 
and anthrax, the last of which is due to Bacterium anthracis. 
137. VENTILATION OF ROOMS.—Fresh air is as necessary for 
the healthy as for the sick. Every healthy person ought to have a cubic 
space of at the very least 800 cubic feet, and every sick person at the very 
least 1000 cubic feet of space. [The cubic space allowed per individual 
varies greatly, but 1000 cubic feet is a fair average. If the air in this space is 
to be kept sweet, so that the C02 does not exceed .06 per cent., 3000 cubic feet 
of air per hour must be supplied, i. e., the air in the space must be renewed three 
times per hour.] 
[Floor-Space.—It is equally important to secure sufficient floor-space, and this is especially 
the case in hospitals. If possible, 100-120 square feet of floor-space ought to be provided for 
each patient in a hospital-ward, and if it is obtainable a cubic space of 1500 cubic feet (Parkes). 
In all cases the minimum floor-space should not be less than of the cubic space.] 
Overcrowding.—When there is overcrowding in a room, the amount of C02 increases. V. 
Pettenkofer found the normal amount of C02 (.04 to .05 per 1000) increased in comfortable 
rooms to 0.54-0.7 per 1000; in badly ventilated sick-chambers = 2.4; in overcrowded audi- 
toriums, 3.2 ; in pits = 4.9 ; in schoolrooms, 7.2 per 1000. Although it is not the quantity of 
C02 which makes the air of an overcrowded room injurious, but the excretions from the outer 
and inner surfaces of the body, which give a distinct odor to the air, quite recognizable by the 
sense of smell, still the amount of C02 is taken as an index of the presence and amount of these 
other deleterious substances. Whether or not the ventilation of a room or ward occupied by 
persons is sufficient, is ascertained by estimating the amount of C02. A room which does not 
give a disagreeable, somewhat stuffy, odor has less than 0.7 per 1000 of C02, while the ventila- 
tion is certainly insufficient if the C02 = 1 per 1000. As the air contains only 0.0005 cubic 
metre C02 in 1 cubic metre of air, and as an adult produces hourly 0.0226 cubic metre C02, 
calculation shows that every person requires 113 cubic metres of fresh air per hour, if the C02 is 
not to exceed 0.7 per 1000 : for 0.7 : 1000 = (0.0226 -f- x X 0.0005) : x> *• e-ix — 1 13- 238 
[Sec. 137. 
FORMATION OF MUCUS, SPUTUM. 
[Vitiating Products.—In a state of repose, an adult man gives off from 12 to 16 cubic feet 
of C02 in twenty-four hours, or on an average .6 cubic feet per hour. To this must be added a 
certain quantity of organic matter, which is extremely deleterious to health. While the C02 
diffuses readily and is easily disposed of by opening the windows, this is not the case with the 
organic matter, which adheres to clothing, curtains, and furniture; hence to get rid of it, a 
room, and especially a sleeping apartment, requires to be well aired for a long time, together 
with the free admission of sunlight. We must also remember that an adult gives off from 25 
to 40 oz. of water by the skin and lungs. The nature of the organic matters is not precisely 
known, but some of it is particulate, consisting of epithelium, fatty matters, and organic 
vapors from the lungs and mouth. It blackens sulphuric acid, and decolorizes a weak solu- 
tion of potassic permanganate. As a test, if we expire through distilled water, and this water 
be set aside for some time in a warm place, it will soon become foetid. We must also take into 
consideration the products of combustion; thus 1 cubic foot of coal-gas, when burned, destroys 
all the O in 8 cubic feet of air (Parkes).~\ 
Methods.—In ordinary rooms, where every person is allowed the necessary cubic space (1000 
cubic feet), the air is sufficiently renewed by means of the pores in the walls of the room, by the 
opening and shutting of doors, and by the fireplace, provided the damper is kept open. It is 
most important to notice that the natural ventilation be not interfered with by dampness of the 
walls, for this influences the pores very greatly. At the same time, damp waLls are injurious to 
health by conducting away heat, and in them the germs of infectious diseases may develop. 
[Natural Ventilation.—By this term is meant the ventilation brought about by the ordinary 
forces acting in nature; such as diffusion of gases, the action of winds, and the movements 
excited owing to the different densities of air at unequal temperatures.] 
[Artificial Ventilation.—Various methods are in use for ventilating public buildings and 
dwelling-houses. Two principles are adopted for the former, viz., extraction and propulsion of 
air. In the former method, the air is sucked out of the rooms by a fan or other apparatus, 
while in the latter, air is forced into the rooms, the air being previously heated to the necessary 
temperature.] 
[Tobin’s Tubes, placed in the walls, furnish a very convenient method of introducing air 
into a room. The air enters through these tubes from the outside near the floor, and is carried up 
six or more feet, to an opening in the wall; the cool air thus descends slowly. For a sitting- 
room, a convenient plan of window ventilation is H. Bird’s Method:—Raise the lower sash 
and place under it, so as to fill up the opening, a piece of wood 3 or 4 inches high. Air will 
then pass in, in an upward direction, between the upper part of the lower sash-frame and the 
lower part of the upper one.] 
138. FORMATION OF MUCUS, SPUTUM.—The respiratory 
mucous membrane is covered normally with a thin layer of mucus (fig. 147, a). 
It so far inhibits the formation of new mucus by protecting the mucous glands 
from the action of cold or other irritative agents. New mucus is secreted as 
that already formed is removed. An increased secretion accompanies conges- 
tion of the respiratory mucous membrane [or any local irritation]. Division of 
the nerves on one side of the trachea (cat) causes redness of the tracheal mucous 
membrane and increased secretion (Rossbach), [but the two processes do not 
stand in the relation of cause and effect]. The secretion cannot be excited by 
stimulating the nerves going to the mucous membrane. [This merely causes 
anaemia of the mucous membrane, while the secretion continues.] 
Modifying Conditions.—If ice be placed on the belly of an animal so as to cause the animal 
“ to take a cold, ” the respiratory mucous membrane first becomes pale, and afterwards there is a 
copious mucous secretion, the membrane becoming deeply congested. The injection of sodium 
carbonate and ammonium chloride into the blood limits the secretion. The local application 
of alum, silver nitrate, or tannic acid, makes the mucous membrane turbid, and the epithelium 
is shed. The secretion is excited by apomorphin, emetin, pilocarpin, and ipecacuanha when 
given internally, while it is limited by atropin and morphia (Rossbach). 
[Expectorants favor the removal of the secretions from the air-passages. This they may do 
either by (a) altering the character and qualities of the secretion itself, or (3) by affecting the 
expulsive mechanism. Some of the drugs already mentioned are examples of the first class. 
The second class act chiefly by influencing the respiratory centre, e. g., ipecacuanha, strychnia, 
ammonia, senega; emetics also act energetically as expectorants, as in some cases of chronic 
bronchitis; warmth and moisture in the air are also powerful adjuncts.] 
Sputum.—Under normal circumstances, some mucus—mixed with a little 
saliva—may be coughed up from the back of the throat. In catarrhal con- Sec. 138.] 
CONSTITUENTS IN THE SPUTUM. 
239 
ditions of the respiratory mucous membrane, the sputum is greatly increased in 
amount, and is often mixed with other characteristic products. Microscopic- 
ally, sputum contains— 
1. Epithelial Cells, chiefly squames from the mouth and pharynx (fig. 
171), more rarely alveolar epithelium and ciliated epithelium (7) from the 
respiratory passages. They are often altered owing to maceration or other 
changes. Thus some cells may have lost their cilia (6). 
The epithelium of the alveoli (2) is squamous epithelium, the cells being two to four times 
the breadth of a colorless blood-corpuscle. These cells occur chiefly in the morning sputum 
in individuals over 30 years of age. In younger persons their presence indicates a pathological 
condition of the pulmonary parenchyma. 
They often undergo fatty degeneration, and they may contain pigment-granules (3); or they 
Fig. 171. 
Various objects found in sputum. 1, detritus and particles of dust; 2, alveolar epithelium 
with pigment; 3, fatty and pigmented alveolar epithelium; 4, alveolar epithelium with 
myelin-forms; 5, free myelin-forms; 6,7,ciliated epithelium,some without cilia; 8, squam- 
ous epithelium from the mouth; 9, leucocytes; 10, elastic fibres; It, fibrin-cast of a small 
bronchus; 12, leptothrix buccalis with cocci, bacteria, and spirochaetse; a, fatty acid crys- 
tals and free fatty granules ; b, hsematoidin; c, Charcot’s crystals; d, cholesterin. 
may present the appearance of what Buhl has called “ myelin degenerated cells," i. e., cells filled 
with clear refractive drops of various sizes, some colorless, others with colored particles, the 
latter having been absorbed (4). Mucin in the form of myelin drops (5) is always present in 
sputum. 
2. Lymphoid cells (9) are colorless blood-corpuscles which have wandered 
out of the blood-vessels ; they are most numerous in yellow sputum, and less 
numerous in the clear mucus-like excretion. The lymph-cells often present 
alterations in their characters ; they may be shrivelled up, fatty, or present a 
granular appearance. 
The fluid substance of the sputum contains much mucus, arising from 
the mucous glands and goblet cells, together with nuclein, and lecithin, and 
the constituents of saliva, according to the amount of the latter mixed with the 
secretion. Albumin occurs only during the inflammation of the respiratory [Sec. 138. 
240 
ACTION OF THE ATMOSPHERIC PRESSURE. 
passages, and its amount increases with the degree of inflammation. Urea has 
been found in cases of nephritis. 
In cases of catarrh, the sputum is at first usually sticky and clear (sputa cruda), but later it 
becomes more firm and yellow (sputa cocta). Under pathological conditions, there may be found 
in the sputum—(a) red blood-corpuscles from rupture of a blood-vessel. (£) Elastic fibres 
(io) from disintegration of the alveoli of the lung; usually the bundles are fine, curved, and the 
fibres branched. [In certain cases it is well to add a solution of caustic potash, which dissolves 
most of the other elements, leaving the elastic fibres untouched.] Their presence always indi- 
cates destruction of the lung tissue. (c) Colorless plugs of fibrin (n), casts of the smaller or 
larger bronchi occur in some cases of fibrinous exudation into the finer air-passages. (d) Crys- 
tals of various kinds—crystals offatty acids in bundles of fine needles (fig. 171, a). They indi- 
cate great decomposition of the stagnant secretion. Leucin and tyrosin crystals are rare ($ 269). 
Tyrosin occurs in considerable amount when an old abscess breaks into the lungs. Colorless, 
■sharp-pointed, octagonal or rhombic plates—Charcot’s crystals (c)—have been found in the 
expectoration in asthma, and exudative affections of the bronchi. Hsematoidin (£) and cho- 
lesterin crystals (d) occur much more rarely. 
Fungi and other lowly organisms are taken in during inspiration (§ 136b The threads of 
Leptothrix buccalis (12), detached from the teeth, are frequently found (§ 147). Mycelium and 
spores are found in thrush (Oidium albicans), especially in the mouths of sucking infants. In 
malodorous expectoration rod-shaped bacteria are present. In pulmonary gangrene are found 
imonads, and cercomonads; in pulmonary phthisis the tubercle bacillus; very rarely sarcina, 
which, however, is often found in gastric catarrh in the stomach and also in the urine ($ 270). 
Physical Characters.—Sputum, with reference to its physical characters, is described as 
mucous, muco-purulent, or purulent. 
Abnormal coloration of the sputum—red from blood ; when the blood remains-long in the 
lung it undergoes a regular series of changes, and tinges the sputum dark-red, bluish-brown, 
brownish-yellow, a prune-juice tint, deep yellow, yellowish-green, or grass-green. The sputum 
is sometimes yellow in jaundice. The sputum may be tinged by what is inspired [as in the case 
of the “black-spit” of miners]. 
The odor of the sputum is more or less unpleasant. It becomes very disagreeable when it 
has remained long in pathological lung-cavities, and it is stinking in gangrene of the lung. 
139. ACTION OF THE ATMOSPHERIC PRESSURE.—At the 
normal pressure of the atmosphere (height of the barometer, 760 millimetres 
Hg), pressure is exerted upon the entire surface of the body= 15,000 to 20,000 
kilos., according to the extent of the superficial area. This pressure acts equally 
on all sides upon the body, and also occurs in all internal cavities containing air, 
both those that are constantly filled with air (the respiratory passages and the 
spaces in the superior maxillary, frontal, and ethmoid bones), and those that 
are temporarily in direct communication with the outer air (the digestive tract 
and tympanum). As the fluids of the body (blood, lymph, secretions, paren- 
chymatous juices) are practically incompressible, their volume remains unchanged 
under the pressure; but they absorb gases from the air corresponding to the 
prevailing pressure (/'. e., the partial pressure of the individual gases), and ac- 
cording to their temperature (§ 33). The solids consist of elementary parts 
(cells and fibres), each of which presents only a microscopic surface to the 
pressure, so that for each cell the prevailing pressure of the air can only be cal- 
culated at a few millimetres—a pressure under which the most delicate histo- 
logical tissues undergo development. As an example of the action of the 
pressure of the atmospheric pressure upon large masses, take that brought about 
by the adhesion of the smooth, sticky, moist, articular surfaces of the shoulder 
and hip-joints; the arm and the leg are supported without the action of the 
muscles. The thigh-bone remains in its socket after section of all the muscles 
and its capsule. Even when the cotyloid cavity is perforated, the head of the 
femur does not fall out of its socket. The ordinary barometric variations affect 
the respiration—a rise of the barometric pressure excites, while a fall diminishes 
the respirations. The absolute amount of C02 remains the same (§ 127, 8). 
Great diminution of the atmospheric pressure, such as occurs in bal- 
looning (highest ascent, 8600 metres), or in ascending mountains, causes a Sec. 139.] 
INCREASE OF ATMOSPHERIC PRESSURE. 
241 
series of characteristic phenomena: (i) In consequence of the diminution of 
the pressure upon the parts directly in contact with the air, they become greatly 
congested, hence there is redness and swelling of the skin and free mucous 
membranes; there may be hemorrhage from the nose, lungs, gums; turgidity 
of the cutaneous veins; copious secretion of sweat; great secretion of mucus. 
(2) A feeling of weight in the limbs, a pressing outwards of the tympanic mem- 
brane (until the tension is equilibrated by opening the Eustachian tube), and 
as a consequence noises in the ears and difficulty of hearing. (3) In conse- 
quence of the diminished tension of O in the air (§ 129), there is difficulty of 
breathing, pain in the chest, whereby the respirations (and pulse) become more 
rapid, deeper, and irregular. When the atmospheric pressure is diminished y2- 
yi, the amount of O in the blood is diminished, the C02 is imperfectly removed 
from the blood, and in consequence there is diminished oxidation within the 
body. When the atmospheric pressure is diminished to one-half, the amount of 
C02 in arterial blood is lessened; and the amount of N diminishes proportion- 
ally with the decrease of the atmospheric pressure. The diminished tension of 
the air prevents the vibrations of the vocal cords from occurring so forcibly, 
and hence the voice is feeble. (5) In consequence of the amount of blood in 
the skin, the internal organs are relatively anaemic ; hence, there is diminished 
secretion of urine, muscular weakness, disturbances of digestion, dulness of the 
senses, and it may be unconsciousness, and all these phenomena are intensified 
by the conditions mentioned under (3). Some of these phenomena are modi- 
fied by usage. The highest limit at which a man may still retain his senses is 
placed by Tissandier at an elevation of 8000 metres (280 mm. Hg). In dogs 
the blood-pressure falls, and the pulse becomes small and diminished in fre- 
quency, when the atmospheric pressure falls to 200 mm. Hg. 
Those who live upon high mountains suffer from a disease, “ mal de montagne,” which con- 
sists essentially in the above symptoms, although it is sometimes complicated with anremia of the 
internal organs. Al. v. Humboldt found that in those who lived on the Andes the thorax was 
capacious. At 6000 to 8000 feet above sea-level, water contains only one-third of the absorbed 
gases, so that fishes cannot live in it. Animals may be subjected to a further diminution of the 
atmospheric pressure by being placed under the receiver of an air-pump. Birds die when the 
pressure is reduced to 120 mm. Hg; mammals at 40 mm. Hg; frogs endure repeated evacua- 
tions of the receiver, whereby they are much distended, owing to the escape of gases and water, 
but after the entrance of air they become greatly compressed. The cause of death in mammals 
is ascribed by Hoppe-Seyler to the evolution of bubbles of gas in the blood; these bubbles stop 
up the capillaries, and the circulation is arrested. Local diminution of the atmospheric pressure 
causes marked congestion and swelling of the part, as occurs when the cupping-glass is used. 
Great increase of the atmospheric pressure causes phenomena, for 
the most part, the reverse of the foregoing, as in pneumatic cabinets and in 
diving-bells, where men may work even under 4)4 atmospheres pressure. (1) 
Paleness and dryness of the external surfaces, collapse of the cutaneous veins, 
diminution of perspiration, and mucous secretions. (2) The tympanic mem- 
brane is pressed inwards (until the air escapes through the Eustachian tube, 
after causing a sharp sound), acute sounds are heard, pain in the ears, and 
difficulty of hearing. (3) A feeling of lightness and freshness during respira- 
tion, the respiration becomes slower (by 2-4 per minute), inspiration easier and 
shorter, expiration lengthened, the pause distinct. The capacity of the lungs 
increases, owing to the freer movement of the diaphragm, in consequence of 
the diminution of the intestinal gases. Owing to the more rapid oxidations in 
the body, muscular movement is easier and more active. The O absorbed and 
the C02 excreted are increased. The venous blood is reddened. (4) Difficulty 
of speaking, alteration of the tone of the voice, inability to whistle. (5) 
Increase of the urinary secretion, more muscular energy, more rapid meta- 
bolism, increased appetite, subjective feeling of warmth, pulse beats slower, and 242 
HISTORY OF RESPIRATION. 
[Sec. 139. 
pulse-curve is lower (compare § 74). In animals subjected to excessively high 
atmospheric pressure, P. Bert found that the arterial blood contained 30 vols. 
per cent. O (at 760 mm. Hg); when the amount rose to 35 vols. per cent., 
death occurred with convulsions. Compressed air has been used for therapeu- 
tical purposes, but in doing so a too rapid increase of the pressure is to be 
avoided. Waldenburg has constructed such an apparatus, which may be used 
for the respiration of air under a greater or less pressure. 
Frogs, when placed in compressed O (at 14 atmospheres) exhibit the same phenomena as if 
they were in a vacuum, or pure N. There is paralysis of the central nervous system, sometimes 
preceded by convulsions. The heart ceases to beat (not the lymph hearts), while the excita- 
bility of the motor nerves is lost at the same time, and lastly the direct muscular excitability 
disappears. An excised frog’s heart placed in O under a very high pressure (13 atmospheres) 
scarcely beats one fourth of the time during which it pulsates in air. If the heart be exposed 
to the air again it begins to beat so that compressed O renders the vitality of the heart latent 
before abolishing it. 
Phosphorus retains its luminosity under a high pressure in O, but this is not the case with the 
luminous organisms, e.g., Lampyris, and luminous bacteria. High atmospheric pressure is also 
injurious to plants. 
140. COMPARATIVE AND HISTORICAL.—Mammals have lungs similar to 
those of man. The lungs of birds are spongy, and united to the chest-wall, while there are 
openings on their surface communicating with thin-walled “ air-sacs,” which are placed 
amongst the viscera. The air-sacs communicate with cavities in the bones, which give the latter 
great lightness. The diaphragm is absent. In reptiles the lungs are divided into greater and 
smaller compartments; in snakes one lung is abortive, while the other has the elongated form of 
the body. The amphibians (frog) possess two simple lungs, each of which represents an 
enormous infundibulum with its alveoli. The frog pumps air into its lungs by the contraction of 
its throat, the nostrils being closed and the glottis opened. When young—until their metamorphosis 
—frogs breathe like fishes by means of gills. The perennibranchiate amphibians (Proteus) 
retain their gills throughout life. Amongst fishes which breathe by gills and use O absorbed by 
the water, the Dipnoi have in addition to gills a swim-bladder provided with afferent and efferent 
vessels, which is comparable to the lung. The Cobitis respires also with its intestine. Insects 
and centipedes respire by “ tracheae,” which are branched canals distributed throughout the 
body; they open on the surface of the body by openings (stigmata) which can be closed. 
Spiders respire by means of tracheae and tracheal sacs, crabs by gills. The molluscs and cepha- 
lopods have gills; some gasteropods have gills and others lungs. Amongst the lower inverte- 
brata some breathe by gills, others by.means of a special “ water-vascular system,” and others 
again by no special organs. 
Historical.—Aristotle (384 B. c.) regarded the object of respiration to be the cooling of the 
body, so as to moderate the internal warmth. He observed correctly that the warmest animals 
breathe most actively, but in interpreting the fact he reversed the cause and effect. Galen 
(131-203 A.d.) thought that the “soot” was removed from the body along with the expired 
water. The most important experiments on the mechanics of respiration date from Galen ; he 
observed that the lungs passively follow the movements of the chest; that the diaphragm is the 
most important muscle of inspiration; that the external intercostals are inspiratory; and the 
internal, expiratory. He divided the intercostal nerves and muscles, and observed that loss of 
voice occurred. On dividing the spinal cord higher and higher, he found that as he did so the 
muscles of the thorax lying higher up became paralyzed. Oribasius (360 a.d.) observed that 
in double pneumothorax both lungs collapsed. Vesalius (1540) first described artificial respira- 
tion as a means of restoring the beat of the heart. Malpighi (1661) described the structure of 
the lungs. J. A. Borelli (f 1679) gave the first fundamental description of the mechanism of 
the respiratory movements. The chemical processes of respiration could only be known after 
the discovery of the individual gases therein concerned. Van Helmont (f 1644) detected C02. 
[Joseph Black (1757) discovered that C02, or “fixed air,” is given out during expiration.] 
In 1774 Priestley discovered O. Lavoisier detected N (1775), and ascertained the composition 
of atmospheric air, and he regarded the formation of C02 and II20 of the breath as a result of a 
combustion within the lungs themselves. J. Ingen-Houss (1730-1799) discovered the respiration 
of plants. Vogel and others proved the existence of C02 in venous blood, and Hoffmann and 
others that of O in arterial blood. The more complete conception of the exchange of gases was, 
however, only possible after Magnus had extracted and analyzed the gases of arterial and venous 
blood (§ 36). Physiology of Digestion. 
[The substances which are used as food—the food-stuffs or alimentary 
principles belong to several different groups and may be conveniently classi- 
fied as— 
1. Proteids or albuminous bodies. 
2. Carbohydrates. 
3. Fats. 
4. Mineral or saline bodies, and water. 
Some of these bodies are insoluble in water, and others do not readily pass 
through animal membranes in their unaltered condition. As the food is carried 
along the alimentary canal it is subjected to the action of certain juices which 
are formed by the secretory activity of the cells lining the alimentary canal or 
by the glands which open into it. These juices (saliva, gastric juice, pancreatic 
juice, bile, and the secretions of the small and large intestine) are formed in 
glands (fig. 172), are poured out into the canal, and act on the food-stuffs by 
dissolving some of them, and rendering others more or less soluble and diffu- 
sible. The digested products pass into the blood, either directly into the 
rootlets of the portal vein or indirectly by the lacteals. The small undigested 
part of the food is discharged in the faeces. The digested products thus finally 
reach the blood, so that in this way new matter is brought within the reach of 
the tissues. Stated broadly, then, the process of digestion consists in rendering 
food-stuffs soluble and diffusible, so that they can pass into the blood.] 
141. THE MOUTH AND ITS GLANDS.—-The mucous mem- 
brane of the cavity of the mouth, which becomes continuous with the skin at 
the red margin of the lips, has a number of sebaceous glands in the region 
of the red part of the lip. The buccal mucous membrane consists of bundles 
of fine fibrous tissue mixed with elastic fibres, which traverse it in every direc- 
tion. Papillae—simple or compound—occur near the free surfaces. The 
sub-mucous tissue, which is directly continuous with the fibrous tissue of 
the mucous membrane itself, is thickest where the mucous membrane is thickest, 
and densest where it is firmly fixed to the periosteum of the bone and to the 
gum ; it is thinnest where the mucous membrane is most movable, and where 
there are most folds. The cavity of the mouth is lined by stratified squa- 
mous epithelium, which is thickest, as a rule, where the longest papillae occur. 
[The mouth is formed by an involution of the external skin, and its epithelium 
is of epiblastic origin.] 
All the glands of the mouth, including the salivary glands, may be 
divided into different classes according to the nature of their secretions. 
x. The serous or albuminous glands [true salivary], whose secretion 
contains a certain amount of albumin, e. g., the human parotid. [The parotid 
of the cat, dog, rabbit, sub-maxillary of the rabbit and guinea-pig.] 
2. The mucous glands, whose secretion, in addition to some albumin, con- 
tains the characteristic constituent mucin. [Sub-lingual of the rabbit, cat, 
dog, and sub-maxillary of the dog and cat.] 244 
THE SALIVARY GLANDS. 
[Sec. 141. 
3. The mixed [or muco-salivary] glands, some of the acini secreting an 
albuminous fluid and others 
mucin, e. g., the sub-maxil- 
lary and sub-lingual of man 
and ape. 
Numerous mucous 
glands (labial, buccal, pal- 
atine, lingual, molar) have 
the appearance of small ma- 
croscopic bodies lying in the 
sub -mucosa. They are 
branched tubular glands 
and the contents of their 
secretory cells consist partly 
of mucin, which is expelled 
from them during secretion. 
The excretory ducts of these 
glands, which are lined by 
cylindrical epithelium, are 
constricted where they enter 
the mouth. Not unfre- 
quently one duct receives 
the secretion of a neigh- 
boring gland. 
The glands of the 
tongue form two groups, 
which differ morphologi- 
cally and physiologically, 
(i) The mucous glands 
(Weber’s glands), oc- 
curring chiefly near the root 
of the tongue, are branched 
tubular glands lined with 
clear transparent secretory 
cells whose nuclei are placed 
near the attached end of the 
cells. The acini have a 
distinct membrana propria. (2) The serous glands (Ebner’s) are acinous 
glands occurring in the region of the circumvallate papillae (and in animals 
near the papillae foliatae). They are lined with turbid granular epithelium 
with a central nucleus, and secrete saliva. (3) The glands of Blandin and 
Nuhn are placed near the tip of the tongue, and consist of mucous and 
serous acini, so that they are mixed glands (Podwisotzky). 
The blood-vessels are moderately abundant, and the larger trunks lie in the sub-mucosa, 
whilst the finer twigs penetrate into the papillae, where they form either a capillary network or 
simple loops. 
The larger lymphatics lie in the sub-mucosa, whilst the finer branches form a fine network 
placed in the mucosa. The lymph-follicles also belong to the lymphatic system ($ 197). On 
the dorsum of the posterior part of the tongue they form an almost continuous layer. They are 
round or oval (r—1.5 mm. in diameter), lying in the sub-mucosa, and consist of adenoid tissue 
loaded with lymph-corpuscles. The outer part of the adenoid reticulum is compressed so as to 
form a kind of capsule for each follicle. Similar follicles occur in the intestine as solitary 
follicles; in the small intestine they are collected together into Peyer’s patches, and in the spleen 
they occur as Malpighian corpuscles. On the dorsum of the tongue several of these follicles 
form a slightly oval elevation, which is surrounded by connective-tissue. , In the centre of this 
elevation there is a depression, into which a mucous gland opens, which fills the small crater 
with mucus (%• 173)- 
' Xose 
\Salivary G/aud 
Salivary 
Glands - 
\Pharynx 
-Vein 
Windpipe- 
• Thoracic or 
Chyle Duct 
Gall 
Bladder 
Liver- 
Gullet 
Pylorus 
Stomach-. 
KSpleen 
Duodenum s 
Lac teals 
Large 
Intestine— 
Smafl I? i test if te 
Vermiform Appendix.. 
Fig. 172. 
General scheme of the digestive tract, with the chief glands 
opening into it; together with the lacteals arising from the 
intestine and joining the thoracic duct. Sec. 141.] 
TONSILS AND THEIR DEVELOPMENT. 
245 
The tonsils have fundamentally the same structure. On their surface are a 
number of depressions into which the ducts of small mucous glands open. 
These depressions are surrounded by 
groups (10-20) of lymph-follicles, 
and the whole is environed by a cap- 
sule of connective tissue (fig. 174). 
Large lymph-spaces, communicating 
with lymphatics, occur in the neigh- 
borhood of the tonsils, but as yet a 
direct connection between the spaces 
in the follicles and the lymph-vessels 
has not been proved to exist. Sim- 
ilar structures occur in the tubal and 
pharyngeal tonsils. [An enor- 
mous number of leucocytes wander 
out of the tonsils, solitary and Peyer’s 
glands, and the adenoid tissue of the 
bronchial mucous membrane (fig. 
174). The cells pass out between 
the epithelial cells, but do not pass 
into the interior of the latter (Stohr).~\ 
[Development of the Tonsil.—The development of the palatal tonsil is most easily 
studied in the rabbit, where the single primary crypt generally remains without branches through 
life, and there the tonsil first appears in embryos of an inch long (occipito-sacral measure- 
ment), or of about 12 days, 
as a shallow epithelial fold 
whose apex points directly 
backwards into the connec- 
tive-tissue concentrically con- 
densed round the pharynx. 
At this stage there is no in- 
filtration of the leucocytes in 
the connective-tissue round 
the crypt, and it is not until 
the embryos are about 21 
days old (lT inches long), 
that the leucocyte infiltra- 
tion becomes evident. The 
crypt has then become much 
deeper and broader, and by 
its ingrowth has produced a 
condensation of the connec- 
tive-tissues at right angles to 
the original peripharyngeal 
condensation as well as a 
great increase in the number 
of capillary blood - vessels. 
From this stage the elonga- 
tion of the crypt, the con- 
densation of the connective- 
tissue, the increase in the 
number of blood-vessels, and 
in the amount of leucocyte 
infiltration go on pari passu, 
until the adult condition is reached. As soon as the leucocytes appear in number in the submu- 
cous tissue they proceed to wander through the epithelium as Stohr has described. 
In the foetus of the pig the condensation of the connective tissue, especially at the apex of the 
tonsillar crypts, and the consequent massing of leucocytes, mainly at these points, is particularly 
well shown. 
In the human foetus the process is the same, though complicated by the early ramification of 
the original epithelial crypt, and the appearance of fresh ones. The crypts become so deep that 
Epithelium. 
Closed 
follicle. 
Depression, 
Closed 
Adenoid. 
tissue. 
.Mucous 
gland. 
Mucous 
gland. 
Section of a mucous follicle from the tongue. 
Fig. 173- 
Epithelium. 
(Tunica 
propria. 
Fig. 174. 
Vertical section of a human tonsil, X 20. 1, cavity; 2, epithe- 
lium infiltrated with leucocytes below and on the left, but free 
on the right; 3, adenoid tissue with sections fi,fvfv of masses 
of it; 4, fibrous sheath; 5, section of a gland-duct; d, blood- 
vessel. 246 
[Sec. 141. 
THE TYPES OF GLANDS. 
the cells from the surface layers of their epithelium cannot at once be thrown off into the mouth, 
and remain as a concentrically arranged mass of degenerated cornified cells filling up the lumen 
of the crypt; this mass is ultimately forced out by the vis a tergo of the leucocytes emigrating 
through the epithelium. (It will at once be seen how closely this resembles the formation of the 
concentric corpuscles of the thymus. The tonsils are preserved from the fate of the epithelial 
thymus by retaining their lumen.) 
The prime factor in the formation of the tonsils is the epithelial ingrowth, which partly me- 
chanically compresses the meshes of the connective-tissue, and partly causes proliferation of the 
connective cells and vessels by the slight irritation it produces, thereby making it easier for the 
leucocytes to escape from the thin-walled capillaries and veno-capillaries so formed, and, when 
they have escaped, causing them to be detained in the finely-meshed connective-tissue longer 
than in other situations. As the leucocytes are well supplied with nutriment, they divide by 
mitosis here in large numbers, as Flemming and his pupils first showed, and at a late stage in 
development (with great variations in individuals) “germ-centres” are formed, where a special 
arrangement of connective-tissue and vessels favors this process of division. 
The lingual and pharyngeal tonsils develop in the same way as the palatal. His shows that 
all the tonsils arise behind the membrana pharyngis, and consequently, all these epithelial in- 
Tubular glands. 
Alveolar glands. 
Simple tube. 
Simple saccule. 
Duct-system. 
Duct-system. 
Duct-system. 
Duct-system. 
End part. 
Alveoli. 
Simple glands. 
Compound gland. 
Fig- 175 
Simple glands. 
Compound gland. 
Scheme of different forms of gland; a, duct. 
growths pass into connective-tissue already condensed round the primitive alimentary canal (G. 
L. Gulland.)~\ 
Nerves.—Numerous medullated nerve-fibres occur in the sub-mucosa, pass into the mucosa, 
and terminate partly in the individual papillae in Krause’s end-bulbs, which are most abundant 
in the lips and soft palate, and not so numerous in the cheeks and floor of the mouth. The 
nerves administer not only to common sensation, but they are also the organs of transmission for 
tactile (heat and pressure) impressions. It is highly probable, however, that some nerve-fibres 
end in fine terminal fibrils, between the epithelial cells, as in the cornea and elsewhere. 
[Secretory glands may be simple or compound. In the latter case 
the duct is branched. In the course of development, a solid process of the 
epithelium sinks into the subjacent fibrous tissue, and, to form a simple gland, a 
cavity appears in this bud, but for a compound gland, other epithelial buds 
sprout from its blind end. Each bud acquires a central cavity ; these elongate 
and increase in number, thus forming a much-branched system, the terminal 
blind ends forming the acini, alveoli, or true secretory part. If the alveoli Sec. 141.] 
THE TYPES OF GLANDS. 
247 
are tubular in shape, the gland is called a compound tubular gland. Thus in 
the compound glands some parts are secretory, and others act as ducts, while in 
the simple glands all the parts may be secretory. All the glands opening on 
the surface of the body are of epiblastic origin. The secretory cells lining the 
acini rest on a basement membrane, and outside this are the lymph-spaces and 
capillary blood-vessels.] 
[Flemming has recently proposed a new classification of glands. Glands are developed from 
the epithelium of mucous membranes, and that of the skin. They are therefore hollow inflec- 
tions of the surface epithelium into the subjacent connective-tissue, and may be either cylin- 
drical tubes—tubuli—or with dilatations or sacculations, alveoli—so that two chief kinds are 
distinguished—tubular and alveolar glands (fig. 175). 
I. Tubular glands occur either singly, or arranged in groups, so that they are divided into— 
1. Simple tubular glands, which are either simple or branched tubes leading to a duct 
(fig. 175). The latter form has been called a “ duct-system.” 
2. Compound tubular glands, composed of a number of “ duct-systems ” (fig. 175). 
II. Alveolar glands are similarly classified. 
I. Simple alveolar glands, with either a simple or branched dilatation or saccule communi- 
cating with a duct; the latter is called an “ alveolar system.” 
A, duct and acini of the parotid gland of a dog; B, acini of the sub-maxillary gland of a dog; 
c, refractive mucous cells; d, granular half-moons of Gianuzzi; C, similar alveoli after 
prolonged secretion; D, basket-shaped tissue investment of an acinus; F, entrance of a 
non-medullated nerve-fibre into a secretory cell. 
Fig. 176. 
2. Compound alveolar glands, which consist of several alveolar systems. 
Unbratiched simple tubular glands are: Lieberktihn’s glands, sweat-glands, and the glands of 
the fundus of the stomach. 
Branched tubular simple glands are: the pyloric, Brunner’s, the smallest mucous and serous 
glands of the mouth, and the uterine glands. 
Compound tubular glands are : the larger mucous, and salivary and lachrymal glands. Also 
the kidneys, Cowper’s glands, prostatic glands, thyroid (at an early stage), liver, and testis. 
The branches of the latter two glands anastomose and form a network; hence the liver and 
testis have been called “reticular glands.” 
Unbranched simple alveolar glands are: the smallest sebaceous glands and the ovarian 
follicles. 
Branched alveolar simple glands are: the larger sebaceous glands and the Meibomian glands. 
Compound alveolar glands are : the mammary glands and the lungs (Flemming and Stohr).] 
142. THE SALIVARY GLANDS.—There are three pairs of saliv- 
ary glands, sub-maxillary, sub-lingual, and parotid. [The sub-maxil- 
lary gland lies under the horizontal ramus of the lower jaw, and its duct (50 
mm. long)—the duct of Wharton—opens in the floor of the mouth at the 248 
[Sec. 142. 
STRUCTURE OF THE SALIVARY GLANDS. 
side of the fraenum of the tongue. The parotid, the largest of the glands, lies 
close to the auricle, and its duct—the duct of Steno—passes over the 
masseter muscle, perforates the buccinator muscle obliquely, and opens into the 
mouth opposite the second upper molar tooth. The sub-lingual gland is the 
smallest of the three, lies beneath the tongue, and has a number of small ducts 
(10-20)—the ducts of Rivini—some of which open separately, but one 
larger one—the duct of Bartholin—unites with Wharton’s duct. All these 
glands are compound tubular glands.] [Each gland consists of a number 
of lobes, and each lobe in turn of a number of lobules, which, 
again, are composed of acini. All these are held together 
by a framework of connective-tissue. The larger branches 
of the duct lie between the lobules, and constitute the in- 
terlobular ducts, giving branches to each lobule which they 
enter, constituting the intralobular ducts, which branch 
and finally terminate in connection with the alveoli, by 
means of an intermediary or intercalary part or duc- 
tule. The larger interlobar and interlobular ducts consist 
of a membrana propria, strengthened outside with fibrous 
and elastic tissues and in some places also by non-striped 
muscle, while the ducts are lined by columnar epithelial 
cells. In the largest branches there is a second row of 
smaller cells, lying between the large cells and the membrana propria. The 
intralobular ducts are lined by a single layer of large cylindrical epithelium 
with the nucleus about the middle of the cell, while the outer half of the cell 
is finely striated longitudinally, or “rodded,” which is due to fibrillae (fig. 
Fig. 177. 
Rodded epithelium 
lining the duct of 
a salivary gland. 
Fig. 178. 
Section of the sub-maxillary gland of the dog stained with picro-carmine; D, duct. 
177); the inner half next the lumen is granular. The intermediary part 
is narrow, and is lined by a single layer of flattened cells, each with an elonga- 
ted oval nucleus. There is usually a narrow “ neck,” where the intralobular 
duct becomes continuous with the intermediary part, and here the cells are 
polyhedral.] 
The terminal acini, or alveoli, are the parts where the actual process of 
secretion takes place. Fig. 176, A, shows several ducts terminating in acini. 
The acini vary somewhat in shape—some are tubular, others branched, some 
are dilated and resemble a Florence flask, and several of them usually open into 
one intermediary part of a duct. Each alveolus is bounded by a basement 
membrane, with a reticulate structure made up of nucleated, branched, and Sec. 142.] 
STRUCTURE OF MUCOUS GLANDS. 
249 
anastomosing cells so as to resemble a basket (D). There is a homogeneous 
membrane bounding the alveoli in addition to this basket-shaped structure. 
Immediately outside this membrane is a lymph-space, and outside this again the 
network of capillaries is distributed. [The extent to which this lymph-space is 
filled with lymph determines the distance of the capillaries from the membrana 
propria. The interalveolar lymph-spaces communicate with large lymph-spaces 
between the lobules, which in turn communicate with perivascular lymphatics 
around the arteries and veins.] The lymphatics emerge from the gland at the 
hilum. 
The secretory cells vary in structure, according as the salivary gland is 
a mucous [sub-maxillary and sub-lingual of the dog and cat], a serous. 
E parotid of man and mammals, and sub-maxillary of rabbit], ora mixed gland 
human sub-maxillary and sub-lingual]. 
Mucous Acini.—The secretory cells of mucous glands, and the mucous 
acini of mixed glands (figs. 178, 179) are lined by a single layer of “ mucin 
cells” (fig. 176, B, c), which are large cells distended with mucin, or with a 
hypothetical substance, mucigen, which yields mucin. The mucin cells are 
Section of retro-lingual gland of dog—a mixed 
gland—stained with picro-carmine. M, mixed 
acinus ; S, serous acinus; D, duct. 
Fig. 179. 
Section of a human sub-maxillary gland. On 
the left is a group of serous alveoli, and on 
the right a group of mucous alveoli. 
Fig. 180. 
more or less spheroidal in shape, clear, shining, highly refractive, and 
nearly fill the acinus. The flattened nucleus is near the wall of the acinus. 
Each cell has a fine process which overlaps the fixed parts of the cells next to 
it. Owing to the body of each cell being infiltrated with mucin, these cells do 
not stain with carmine, although the nucleus and its immediately investing 
protoplasm do. Another kind of cell occurs in the sub-maxillary gland of the 
dog. It forms a half-moon-shaped structure lying in direct contact with the 
wall of the acinus Each “ demilune,” “ half-moon,” or “ cres- 
cent” consists of a number of small, closely packed, angular, highly albu- 
minous cells with small oval nuclei, which, however, are separated only 
with difficulty. Hence, Heidenhain has called them “ composite marginal 
cells” (B, d). They are granular, darker, devoid of mucin, and stain readily 
with pigments. [In the sub-maxillary gland of the cat, there is a complete layer 
of these “ marginal” carmine-staining cells lying between the mucous cells and 
the membrana propria.] 250 
CHANGES IN SALIVARV GLANDS DURING SECRETION. 
[Sec. 142. 
[Serous Acini.—In true serous glands (parotid of man and mammals) and 
in the serous acini of mixed glands, the acini are lined by a single layer of 
secretory columnar finely granular cells, which in the quiescent condition 
completely fill the acinus, so that scarcely any lumen is left (fig. 176, C). Just 
before secretion, or when these cells are quiescent, Langley has shown that they 
are large and filled with numerous granules, which obscure the presence of the 
nucleus. As secretion takes place, these granules seem to be used up or dis- 
charged into the lumen ; at least, the outer part of each cell gradually becomes 
clear and more transparent, and this condition spreads towards the inner part 
of the cell.] 
[In the mixed or muco-salivary glands (<?. g., human sub-maxillary) some 
of the alveoli are mucous and others serous in their characters, but the latter 
are always far more numerous, and the one kind of acinus is directly continuous 
with the other kind (fig. 180).]• 
143. HISTOLOGICAL CHANGES DURING THE ACTIVITY 
OF THE SALIVARY GLANDS.—[The condition of physiological 
activity of the gland-cells is accompanied by changes in the histological char- 
acters of the secretory cells. Changes in serous glands have been carefully 
studied in the parotid of the rabbit, but the appearances vary somewhat, accord- 
ing as the glands are examined in the fresh condition or after hardening in various 
reagents, such as absolute alcohol. When the gland is at rest, or in the 
“resting phase,” sometimes also called the “loaded” or “charged” con- 
dition, in a preparation hardened in alcohol, and stained with carmine, the 
cells consist of a pale, almost uncolored substance, with a few fine granules, 
and a small irregular, red-stained, shrivelled nucleus devoid of a nucleolus. 
The appearance of the nucleus suggests the idea of its being shrivelled by the 
action of the hardening reagent (fig. 181, A).] 
Fig. 181, A. 
Fig. 181, B. 
Sections of a “ serous” gland, stained with carmine. The parotid of a rabbit, fig. 181, A, at 
rest; fig. 181, B, after stimulation of the cervical sympathetic. 
[During activity, or in the “ active phase,” if the gland be caused to 
secrete by stimulating the sympathetic, all parts of the cells undergo a change 
(fig. 181, A, B). In preparations hardened in alcohol—(i) the cells dimin- 
ish somewhat in size ; (2) the nuclei are no longer irregular, but round, with a 
sharp contour and nucleoli; (3) the substance of the cell itself is turbid owing 
to the diminution of the clear substance, and the increase of the granules, 
especially near the nuclei; (4) at the same time, the whole cell stains more 
deeply with carmine (Heidenhain).'] 
[On studying the changes which occur in a living serous gland, Langley Sec. 143.] 
HISTOLOGICAL CHANGES IN GLANDS. 
251 
found that the substance of the cells of the parotid is pervaded by fine granules, 
which are so numerous as to obscure the nucleus, while the outlines of the cells 
are indistinct. No lumen is visible in the acini, during activity the granules 
disappear from the outer zone of the cells, the cells themselves becoming 
smaller and more distinct. After prolonged secretion, the granules largely 
disappear from the cell-substance except quite near the inner margin. The 
cells are smaller, their outlines more distinct, their spherical nuclei apparent, 
and the lumen of the acini is wide and distinct. Thus, it is evident that, during 
rest, granules are manufactured, which disappear during the activity of the 
cells, the disappearance taking place from without inwards. Similar changes 
occur in the cells of the pancreas (§ 168).] 
[More complex changes occur in the mucous glands, such as the sub-maxil- 
lary or orbital glands of the dog (Lavdovsky). The appearances vary accord- 
ing to the intensity and duration of the secretory activity. The mucous cells 
at rest are large, clear, and refractive, containing a flattened nucleus (fig. 176, 
C), surrounded with a small amount of protoplasm, and placed near the base- 
ment membrane. The clear substance does not stain with carmine, and con- 
sists of mucigen lying in the wide spaces of an intracellular plexus of fibrils. 
After prolonged secretion, produced, it may be, by strong and continued 
stimulation of the chorda, the mucous cells of the sub-maxillary gland of the 
dog undergo a great change. In such a condition the cells are spoken of as 
“unloaded” or “discharged.”] The distended, refractive,and “mucouscells,” 
which occur in the quiescent gland, and which do not stain with carmine, ap- 
pear quite different after the gland has been in a state of activity. They are 
represented by small dark protoplasmic cells devoid of mucin (fig. 176, C). 
These cells readily stain with carmine, whilst their nucleus is scarcely, if at all, 
colored by the dye. The researches of R. Heidenhain (1868) have shed 
much light on the secretory activity of these glands. 
[During rest, the protoplasm seems to manufacture mucigen, which is 
changed into and discharged as mucin in the secretion, when the gland is 
actively secreting. Thus, the cells become smaller, but the protoplasm of the 
cell seems to increase, new mucigen is manufactured during rest, and the cycle 
is repeated.] 
The change may be produced in two ways. Either it is due to the “ mucous cells” during 
secretion becoming broken up, so that they yield their mucin directly to the saliva; in saliva 
rich in mucin, small microscopic pieces of mucin are found, and sometimes mucous cells them- 
selves are present. Or. we must assume that the mucous cells simply eliminate the mucin from 
their bodies (Ewald, Siohr)-, while after a peiiod of rest, new mucin is formed. According to 
this view, the dark granular cells of the glands, after active secretion, are simply mucous cells, 
which have given out their mucin. If we assume, with Heidenhain, that the mucous cells 
break up, then these granular non-mucous cells must be regarded as new formations produced by 
the proliferation and growth of the composite marginal cells, i, e., the crescents, or half-moons 
of Gianuzzi. 
144. THE NERVES OF THE SALIVARY GLANDS. —The 
nerves are for the most part medullated, and enter at the hilum of the gland, 
where they form a rich plexus provided with ganglia between the lobules. 
[There are no ganglia in the parotid gland {Klein).'] 
All the salivary glands are supplied by branches from two different nerves— 
from the sympathetic and from a cranial nerve. 
1. The sympathetic nerve gives branches (a) to the sub-maxillary and 
the sub-lingual glands, derived from the plexus on the external maxillary artery; 
(b) to the parotid gland from the carotid plexus (fig. 182). [These nerve- 
fibres reach the gland along the arteries of the gland, and are for the most part 
non-medullated nerve-fibres. They can be traced to the superior cervical 
ganglion and from thence through the cervical sympathetic into the cord.] 252 
THE NERVES OF THE SALIVARY GLANDS. 
[Sec. 144. 
2. The facial nerve gives branches to the sub-maxillary and sub-lingual 
glands from the chorda tympani, which accompanies the lingual branch of 
the fifth nerve (fig. 182). [The chorda consists of fine medullated fibres, but 
as they enter the gland the fibres become non-medullated.] The branches to 
the parotid arise from the tympanic branch of the glosso-pharyngeal nerve 
(dog). The tympanic plexus sends fibres to the small superficial petrosal 
nerve, and with it these fibres run to the anterior surface of the pyramid in the 
temporal bone, emerging from the skull through a fissure between the petrous 
and great wing of the sphenoid, and then joining the otic ganglion. This 
ganglion sends branches to the auriculo-temporal nerve (itself derived from the 
third branch of the trigeminus), which, as it passes upwards to the temporal 
region under cover of the parotid, gives branches to this gland. 
The sub-maxillary ganglion, which gives branches to the sub-maxillary 
and sub-lingual glands, receives fibres from the tympanico-lingual nerve 
(chorda tympani) as well as sympathetic fibres from the plexus on the external 
maxillary artery. 
Scheme of the nerves of the salivary glands. P., pons; M.O., medulla oblongata ; J N., nerve 
of Jacobson; O., S.M., I.M., ophthalmic, superior, and inferior maxillary divisions of fifth 
nerve, V.; VII., seventh nerve; S.s.p., small superficial petrosal nerve; Vag., vagus; 
Sym., sympathetic; O.G., otic, and S.G., submaxillary ganglia; P., S., and S.L., parotid, 
sub-maxillary, and sub-lingual glands; T., tongue. 
Fig. 182. 
Termination of the Nerve-Fibres.—With regard to the ultimate distri- 
bution of these nerves we can distinguish (i) the vaso motor nerves, which 
give branches to the walls of the blood-vessels, and (2) the secretory nerves 
proper. 
Pfliiger states, with regard to the latter, that (<z) medullated nerve-fibres penetrate the acini; 
the sheath of Schwann unites with the membrana propria <jf the acinus; the medullated fibre— 
still medullated—passes between the secretory cells, where it divides and becomes non-medul- 
lated, and its axial cylinder terminates in connection with the nucleus of a secretory cell. [This, 
however, is not proved] (fig. 176, F). (£) According to Pfliiger, some of the nerve-fibres end in 
multipolar ganglion cells, which lie outside the wall of the acinus, and these cells send branches 
to the secretory cells of the acini. [These cells probably correspond to the branched cells 
of the basket-shaped structure.] (r) Again, he describes medullated fibres which enter the 
attached end of the cylindrical epithelium lining the excretory ducts of the glands (E). Pfliiger 
thinks that those fibres entering the acini directly are cerebral, while those with ganglia in their 
course are derived from the sympathetic system, [(z/) The direct termination of nerve-fibres has 
been observed in the salivary glands of the cockroach by Kupffer.] 
145. ACTION OF THE NERVOUS SYSTEM ON THE SE- 
CRETION OF SALIVA.—A. Sub maxillary Gland.—Stimulation Sec. 145.] 
EFFECTS OF STIMULATION OF THE CHORDA. 
253 
of the facial nerve at its origin causes a profuse secretion of a thin watery 
saliva, which contains a very small amount of specific constituents. Simul- 
taneously with the act of secretion, the blood-vessels of the glands dilate, and 
the capillaries are so distended that the pulsatile movement in the arteries is 
propagated into the veins. [Owing to the dilatation of the arterioles the 
pulse-wave is propagated through the capillaries into the veins, so that there is 
a venous pulse, the blood flowing from the veins in jets, p. 138.] Nearly four 
times as much blood flows out of the veins, the blood being of a bright red 
color, and containing one-third more O than the venous blood of the non- 
stimulated gland. Notwithstanding this relatively high percentage of O, the 
secreting gland uses more O than the passive gland (§ 132, 1). 
[I. Stimulation of Chorda Tympani.—If a cannula be placed in Whar- 
ton’s duct, e.g., in a dog, and the chorda tympani be divided, no secretion 
flows from the cannula. On stimulating the peripheral end of the chorda 
tympani with an interrupted current of electricity, the same results—copious 
secretion of saliva and vascular dilatation, with increased flow of blood through 
Fig. 183. 
Scheme of the secretory and vaso-constrictor nerves of the sympathetic nerve, and vaso-dilator 
and secretory nerves of the chorda passing to the sub-maxillary gland. 
the gland—occur as when the origin of the seventh nerve itself is stimulated.— 
The watery saliva is called chorda saliva. Thus two effects are produced 
simultaneously, viz., vascular dilatation and secretion of saliva. As a 
matter of fact, each is brought about by the independent action of special 
nerve-fibres, so that two functionally different kinds of nerve-fibres occur in the 
facial nerve and chorda—(i) vaso-dilator fibres (fig. 183), and (2) true 
secretory fibres. The methods by which the existence of these nerve-fibres 
is proved are described on p. 254]. 
II. Stimulation of the sympathetic nerve causes a scanty amount of a 
very thick, sticky, opaque mucous secretion, in which the specific salivary con- 
stituents, mucin, and the salivary corpuscles are very abundant. [It contains a 
large number of morphological elements, chiefly pale glutinous-looking masses, 
probably products of the transformation of gland-cells. The solids reach 15-28 
per 1000, but the total quantity of saliva secreted is always small.] The specific 
gravity of the saliva is raised from 1007 to 1010. Simultaneously the blood- 
vessels become contracted, so that the blood flows more slowly from the veins, 
and has a dark bluish color. ACTION OF ATROPIN. 
[Sec. 145. 
254 
The sympathetic also contains two kinds of nerve-fibres—(i) true secretory 
fibres, and (2) vaso-constrictor fibres (fig. 183). 
[Electrical Variations during Secretion.—That changes in the electromotive properties of 
glands occur during secretion was shown in the frog’s skin. Bayliss and Bradford find that the 
same is true of the sub-maxillary gland (dog). During secretion, the excitatory change on 
stimulating the chorda is a positive variation of the current of rest (the hilum of the gland 
becoming more positive), but it is frequently followed by a second phase of opposite sign. The 
latent period is always very short, about 0.37". Atropin abolishes the chorda variation. On 
stimulating the sympathetic, the excitatory change is of an opposite sign to that of the chorda, 
and the hilum becomes less positive, so that there is a negative variation. It requires a more 
powerful stimulus, is less in amount, and its latent period is longer (2//-4//), while atropin 
lessens but does not abolish it.] 
Relation to Stimulus.—On stimulating the cerebral nerves, at first with a weak and gradu- 
ally with a stronger stimulus, there is a gradual development of the secretion in which the solid 
constituents—occasionally the organic—are increased (Heidenhain). If a strong stimulus be 
applied for a long time, the secretion diminishes, becomes watery, and is poor in specific con- 
stituents, especially in the organic elements, which are more affected than the inorganic (C. 
Ludwig and Becher). After prolonged stimulation of the sympathetic, the secretion resembles 
the chorda saliva. It would seem, therefore, that the chorda and sympathetic saliva are not 
specifically distinct, but vary only in degree. On continuing the stimulation of the nerves up to 
a certain maximal limit, the rapidity of secretion becomes greater, and the percentage of salts 
also increases to a certain maximum, and this independently of the former condition of the 
glands. The percentage of organic constituents also depends on the strength of the nervous 
stimulation, but not on this alone, as it is essentially contingent upon the condition of the gland 
before the secretion took place, and it also depends upon the duration and intensity of the 
previous secretory activity. Very strong stimulation of the gland leaves an “ after effect,” 
which predisposes it to give off organic constituents into the secretion (Heidenhain). A latent 
period of 1.2 sec. to 24 sec. may elapse between the nerve-stimulation and the beginning of the 
secretion. 
[Langley has shown that in the cat the sympathetic saliva of the sub-maxillary gland is less 
viscid than the chorda saliva.] 
Relation of Secretion to Blood-Supply.— The secretion of saliva is not 
simply the result of the amount of blood in the glands; that there is a factor 
independent of the changes in the state of the vessels is shown by the following 
facts:— 
1. The secretory activity of the glands when their nerves are stimulated con- 
tinues for some time after the blood-vessels of the gland have been ligatured. 
[If the head of a rabbit be cut off, stimulation of the seventh nerve, above where the chorda 
leaves it, causes a flow of saliva, which cannot be accounted for on the supposition that the 
saliva already present in the salivary glands is forced out of them. Thus we may have secre- 
tion without a blood-stream. The saliva is really secreted from the lymph (fig. 183) present 
in the lymph-spaces of the gland (Ludwig).~\ 
2. Atropin and daturin abolish the activity of the secretory fibres in the 
chorda tympani, but do not affect the vaso-dilator fibres (.Heidenham). The 
same results occur after the injection of acids and alkalies into the excretory 
duct (Gianuzzi). 
[Action of Atropin.—The vascular dilatation and the increased flow of 
saliva due to the activity of the secretory cells, produced by stimulation of the 
chorda tympani, although they occur simultaneously, do not stand in the rela- 
tion of cause and effect. We may cause vascular dilatation without an increased 
flow of saliva, as already stated (2). If atropin be given to an animal, stimu- 
lation of the chorda produces dilatation of the blood-vessels, but no secretion 
of saliva. Atropin paralyzes the secretory fibres, but not the vaso-dilator fibres 
(fig. 184). The increased supply of blood, while not causing, yet favors the 
act of secretion, by placing a large amount of pabulum at the disposal of the 
secretory elements, the cells.] 
3. The pressure in the excretory duct of the salivary gland—measured by 
means of a manometer tied in it—may be nearly twice as great as the pressure Sec. 145.] 
PARALYTIC SECRETION OF SALIVA. 
255 
within the arteries of the glands, or even in the carotid itself {Ludwig). The 
pressure in Wharton’s duct may reach 200 mm. Hg [while the pressure within 
the carotid, i. e., the blood-pressure, may be only 120 mm. Hg.] 
[Secretory Pressure.—The experiment described under (3) proves, in a 
definite manner, that the passage of the water from the blood-vessels, or at least 
from the lymph into the acini of the gland, cannot be due to the blood-pressure ; 
that, in fact, it is not a mere process of filtration, such as perhaps occurs in the 
glomeruli of the kidney. In the case of the salivary gland, where the pressure 
within the gland may be nearly double that of the arterial pressure, the water 
actually moves from the lymph-spaces against very great resistance. We can 
only account for this result by ascribing it to the secretory activity of the 
gland-cells themselves. Whether the activities of the gland-cells, as suggested 
by Heidenhain, are governed directly by two distinct kinds of nerve-fibres, a 
set of solid-secreting fibres, and a set of water-secreting fibres, remains to be 
proved.] 
All these facts lead us to conclude that the nerves exercise a direct 
effect upon the secretory cells, apart from their action on the blood- 
vessels. 
4. Just as in the case of muscles and nerves, the salivary glands become fatigued or ex- 
hausted after prolonged action. This result may also be brought about by injecting acids or 
alkalies into the duct, which shows that the secretory activity of the gland is independent of 
the circulation (Giamtzzi). 
Extirpation of Salivary Glands.—When the chorda tympani is extirpated on one side in 
young dogs, the sub-maxillary gland on that side does not develop so much—its weight is 50- 
per cent, less—while the mucous cells and the “ crescents ” are smaller than on the sound side- 
(.Bufalini). 
During secretion, the temperature of the gland rises 1.50 C. {Ludwig), 
and the blood flowing from the veins is often warmer than the arterial blood. 
[The electro-motive changes are referred to at p. 254.] 
[Results of Stimulation of glandular nerves.—The results following 
electrical or other stimulation of the peripheral end of a glandular nerve may 
be stated as follows :— 
(1) Vaso-motor changes, causing alterations in the blood-supply and 
blood-flow. 
(2) Chemical and histological changes in the gland-cells connected 
with the elaboration of the organic and possibly of the inorganic constituents 
of the saliva. 
(3) Changes by which water is secreted, i. e., passes through the base- 
ment membrane and gland-cells, and the consequent movement of the fluid 
through the cells and ducts. 
(4) Electrical changes (p. 254), which do not seem to be associated with 
the vaso-motor changes, for the electrical variations are readily abolished by 
atropin, which does not affect the vaso-motor changes.] 
“ Paralytic Secretion ” of Saliva.—By this term is meant the continued 
secretion of a thin watery saliva from the sub-maxillary gland, which occurs 
twenty-four hours after the section of the cerebral nerves (chorda of the seventh), 
i. e., those branches of them that go to this gland, whether the sympathetic be 
divided or not {Cl. Bernard). It increases until the eighth day, after which 
it gradually diminishes, while the gland-tissue degenerates. The injection 
of a small quantity of curare into the artery of the gland also causes it. 
[Heidenhain showed that section of one chorda is followed by a continuous secretion of saliva 
from both sub-maxillary glands. The term “ paralytic secretion ” is applied to that which 
takes place on the side on which the nerve is cut, and Langley proposes to call the secretion on 
the opposite side the antilytic. Apnoea (§ 368) stops both the paralytic and antilytic 
secretion, while dyspnoea increases the flow in both cases; and as section of the sympathetic 256 
REFLEX SECRETION OF SALIVA. 
[Sec. 145. 
fibres to the gland (where the chorda is cut) arrests the paralytic secretion excited by dyspnoea, 
it is evident that both the paralytic secretion and the secretion following dyspnoea are caused 
by stimuli travelling down the sympathetic fibres. In the later stages of the paralytic secretion 
the cause is in the gland itself, for it goes on even if all the nerves passing to the gland be 
divided, and is probably due to a local nerve-centre. In this stage the secretion is arrested by 
a large dose of chloroform. The paralytic secretion, in the first stage, may be owing to a venous 
condition of the blood acting on a central secretory centre whose excitability is increased; and 
in the latter stages probably on local nerve-centres within the gland. The fibres of the chorda 
in the cat are only partially degenerated thirteen days after section (Langley).] 
[Histological Changes.—In the gland during paralytic secretion, the gland-cells of the 
alveoli (serous, mucous, and demilunes) diminish in size, and show the typical “ resting ” 
appearance, even to a greater extent than the normal resting gland (Langley). 
B. Sub-Lingual Gland.—Very probably the same general relations obtain 
as in the sub-maxillary gland. 
C. Parotid Gland.—In the dog, stimulation of the sympathetic alone 
causes no secretion ; it occurs when the glosso-pharyngeal branch to the parotid 
is simultaneously excited. This branch may be reached within the tympanum 
in the tympanic plexus. A thick secretion containing much organic matter is 
thereby obtained. Stimulation of the cerebral branch alone yields a clear thin 
watery secretion, containing a very small amount of organic substances, but a 
considerable amount of the salts of the saliva. 
[Stimulation of Jacobson’s Nerve (Parotid of Dog)— 
Total Solids. 
Salts. 
Organic Matter. 
Without sympathetic, 
0.55% 
O.3I 
O.24 
With sympathetic, 
2.42% 
O.36 
2.06] 
The following table shows the nerves of the parotid gland :— 
Vaso-motor nerves 
Cerebral. Vaso dilators = glosso-pharyngeal. 
Sympathetic. Vaso-constrictors = sympathetic. 
Secretory nerves 
Cerebral 
Facial (?) 
Glosso-pharyn geal 
= small superficial petrosal. 
The parotid atrophies after destruction of the tympanic plexus {Bradford). 
Sympathetic = sympathetic.} 
Reflex Secretion of Saliva.— 
[If a cannula be placed in Wharton’s 
duct, e.g., in a dog, during fasting, 
little or no saliva will flow out, but on 
applying a sapid substance to the 
mucous membrane of the mouth or 
the tongue, there is a copious flow of 
saliva. If the sympathetic nerve be 
divided, secretion still takes place 
when the mouth is stimulated, but if 
the chorda tympani be cut, secretion 
no longer takes place. Hence, the 
secretion is due to a reflex act; in 
this case, the lingual is the afferent, 
and the chorda the efferent nerve car- 
rying impulses from a centre situated 
in the medulla oblongata (fig. 184).] 
In the intact body, the secretion of 
saliva occurs through a reflex stimulation of the nerves concerned, whereby, 
under normal circumstances, the secretion is always watery (chorda or facial 
saliva). The centripetal or afferent nerve fibres concerned are:—(1) 
The nerves of taste. (2) The sensory branches of the trigeminus of the entire 
■cavity of the mouth and the glosso-pharyngeal (which appear to be capable of 
Mucous Membrane 
Afferent 
Nerve./ 
Duct of Gland 
[Secretory I 
Nerve 
Centre, 
1 Secreting 
* cells. 
Vase-dilator 
Nerve. 
of Gland. 
Fig. 184. 
Diagram of a salivary gland. Sec. 145.] 
CONDITIONS AFFECTING SALIVARY SECRETION. 
257 
being stimulated by mechanical stimuli, pressure, tension, displacement). The 
movements of mastication also cause a secretion of saliva. Pfliiger found that 
one-third more saliva was secreted on the side where mastication took place; 
and Cl. Bernard observed that the secretion ceased in horses during the act 
of drinking. (3) The nerves of smell, excited by certain odors. (4) The 
gastric branches of the vagus. A rush of saliva into the mouth usually precedes 
the act of vomiting (§ 158). 
(5) The stimulation of distant sensory nerves, e. g,, the central end of the sciatic— 
certainly through a complicated reflex mechanism—causes a secretion of saliva (Owsjannihow 
and Tschierjew). Stimulation of the conjunctiva, e. g., by applying an irritating fluid to the 
eye of carnivorous animals, causes a reflex secretion of saliva (Aschenbrandt). Perhaps the 
secretion of saliva which sometimes occurs during pregnancy is caused in a similar reflex manner. 
(6) The movements of mastication excite secretion, but although, during the act of rumi- 
nation, this is the case in ruminants, in whom the process of mastication is very thorough, there 
is no secretion from the sub-maxillary gland, although the parotid secretes [Colin, Ellenberger 
and Hofmeister). 
The reflex centre for the secretion of saliva lies in the medulla oblongata, 
at the origin of the seventh and ninth cranial nerves. The centre for the sym- 
pathetic fibres is also placed here. This region is connected by nerve-fibres 
with the cerebrum ; hence the thought of a savory morsel, sometimes, when 
one is hungry, causes a rapid secretion of a thin watery fluid—[or, as we say, 
“ makes the mouth water ”]. If the centre be stimulated directly by a mechan- 
ical stimulus (puncture), salivation occurs, while asphyxia has the same effect. 
The reflex secretion of saliva may be inhibited by stimulation of certain sen- 
sory nerves, e. g., by pulling out a loop of the intestine. Stimulation of the 
cortex cerebri of a dog, near the sulcus cruciatus, is often followed by secre- 
tion of saliva. Disease of the brain in man sometimes causes a secretion of 
saliva, owing to the effects produced on the intracranial centre. 
So long as there is no stimulation of the nerves, there is no secretion of 
saliva, as in sleep. Immediately after the section of all nerves, secretion stops, 
for a time at least. 
Pathological Conditions and Poisons.—Certain affections, as inflammation of the mouth, 
neuralgia; ulcers of the mucous membrane; and affections of the gums, due to teething or the 
prolonged administration of mercury, often produce a copious secretion of saliva orptyalism. 
Certain poisons cause the same effect by direct stimulation of the nerves, as Calabar bean (phy- 
sostigmin), digitalin, and especially pilocarpin. Many poisons, especially the narcotics—above 
all atropin—paralyze the secretory nerves, so that there is a cessation of the secretion and the 
mouth becomes dry; while the administration of muscarin in this condition causes secretion. 
Pilocarpin acts on the chorda tympani, causing a profuse secretion, and if atropin be given, the 
secretion is again arrested. Conversely, if the secretion be arrested by atropin, it may be 
restored by the action of pilocarpin or physostigmin. Nicotin, in small doses, excites the secre- 
tory nerves, but in large doses paralyzes them. Daturin, cicutin, and iodide of sethylstrychnin, 
paralyze the chorda. The saliva is diminished in amount in man, in cases of paralysis of the 
facial or sympathetic nerves, as is observed in unilateral paralysis of these nerves. 
[Sialogogues are those drugs which increase the secretion of saliva. Some are topical, and 
take effect when applied to the mouth. They excite secretion reflexly by acting on the sensory 
nerves of the mouth. They include acids, and various pungent bodies, such as mustard, ginger, 
pyrethrum, tobacco, ether, and chloroform; but they do not all produce the same effect on the 
amount or quality of the saliva; others, the general sialogogues, cause salivation when intro- 
duced into the blood : physostigmin, nicotin, pilocarpin, muscarin. The drugs named act after 
all the nerves going to the gland are divided, so that they stimulate the peripheral ends of the 
nerves in the glands. The first two also excite the central ends of the secretory nerves.] 
[Anti-sialics are those substances which diminish the secretion of saliva, and they may take 
effect upon any part of the reflex arc, i. e., on the mouth, the afferent nerves, the nerve-centre 
and afferent nerves, or upon the blood-stream through the glands, or in the glands themselves. 
Opium and morphia affect the centre, large doses of physostigmin affect the blood-supply, 
but atropin is the most powerful of all, as it paralyzes the terminations of the secretory nerves in 
the glands, e. g., the chorda tympani, and event he sympathetic in the cat (but not in the dog).] 
[Excretion by the Saliva.—Some drugs are excreted by the saliva. Iodide of potassium 
is rapidly eliminated by the kidneys, and by the salivary glands, and so also is iodide of iron.] [Sec. 145. 
258 
THE SALIVA OF THE INDIVIDUAL GLANDS. 
Theory of Salivary Secretion.—Heidenhain has recently formulated the following theory 
regarding the secretion of saliva :—“ During the passive or quiescent condition of the gland, 
the organic materials of the secretion are formed Irom and by the activity of the protoplasm of 
the secretory cells. A quiescent cell, which has been inactive for some time, therefore contains 
little protoplasm, and a large amount of these secretory substances. In an actively secreting 
gland, there are two processes occurring together, but independent of each other, and regulated 
by two different classes of nerve-fibres; secretory fibres cause the act of secretion, while trophic 
fibres cause chemical processes within the cells, partly resulting in the formation of the soluble 
constituents of the secretion, and partly in the growth of the protoplasm. According to the 
number of both kinds of fibres present in a nerve passing to a gland, such nerve being stimu- 
lated, the secretion takes place more rapidly (cerebral nerve) or more slowly (sympathetic), 
while the secretion contains less or more solid constituents. The cerebral nerves contain many 
secretory fibres and few trophic fibres, while the sympathetic contain more trophic but few 
secretory fibres. The rapidity and chemical composition of the secretion vary according to the 
strength of the stimulus. During continued secretion, the supply of secretory materials in the 
gland-cells is used up more rapidly than it is replaced by the activity of the protoplasm; hence, 
the amount of organic constituents diminishes, and the microscopic characters of the cells are 
altered. The microscopic characters of the cells are altered also by the increase of the proto- 
plasm, which takes place in an active gland. The mucous cells disappear, and seem to be 
dissolved after prolonged secretion, and their place is taken by other cells derived from the pro- 
liferation of the marginal cells (?). The energy which causes the current of fluid depends upon 
the protoplasm of the gland-cells.” 
146. THE SALIVA OF THE INDIVIDUAL GLANDS.—(a) 
Parotid saliva (Steno’s duct) ; it has an alkaline reaction, but during fast- 
ing, the first few drops may be neutral, or even acid, on account of free C02; its 
specific gravity is 1003 to 1004. [It does not contain any morphological con- 
stituents.] After standing it becomes turbid, and deposits, in addition to 
albuminous matter, calcium carbonate, which is present in the fresh saliva in 
the form of bicarbonate. It contains small quantities (more abundant in the 
horse) of a globulin-like body, and never seems to be without CNKS, i. e., 
sulphocyanide of potassium (or sodium),—which, however, is absent in the 
sheep and dog. 
[The sulphocyanide gives a dark red color (ferric sulphocyanide) with ferric chloride, and 
the color is discharged by mercuric chloride, but this is not the case with meconic acid, which 
gives a similar color reaction.] It also reduces iodic acid when added to saliva, causing a 
yellow color from the liberation of iodine, which may be detected at once by starch {Solera). 
Amongst the organic substances the most important are ptyalin, a small 
amount of urea, and traces of a volatile acid. Mucin is absent, hence the 
parotid saliva is not sticky, and can readily be poured from one vessel into 
another. It contains 1.5 to 1.6 per cent, of solids in man, of which 0.3 to 
1.0 per cent, is inorganic. [It does not contain any morphological elements. 
Its diastatic action is more powerful in man than that of the sub-maxillary gland, 
or of mixed saliva. Parotid saliva is powerfully diastatic in the rodents (guinea- 
pig, rat, mouse, rabbit) ; it is less active in ruminants, and it is said to be 
inactive in the sheep. It is almost inactive in the dog and cat.] 
Of the inorganic constituents—the most abundant are potassium and sodium chlorides; then 
potassium, sodium, and calcium carbonates, some phosphates, and a trace of an alkaline 
sulphate. 
Salivary calculi are formed in the ducts of the salivary glands owing to the deposition of 
lime-salts, and they contain only traces of the other salivary constituents ; in the same way is 
formed the tartar of the teeth, which contains many threads of leptothrix, and the remains of 
low organisms which live in decomposing saliva in carious cavities and between the teeth. 
Method of obtaining Saliva.—In order to obtain the saliva from the individual glands, a 
thin metallic tube or cannula is introduced into the corresponding duct. On making masticatory 
movements, or on stimulating the tongue with sapid substances, there is a reflex secretion of 
saliva which flows out by the tube. 
{U) Sub-maxillary saliva is obtained by placing a cannula in Wharton’s 
duct; it is alkaline, and may be strongly so. After standing for a time, fine 
crystals of calcium carbonate are deposited, as also an amorphous albuminous Sec. 146.] 
MIXED SALIVA. 
259 
body. It always contains mucin (which is precipitated by acetic acid); 
hence, it is usually somewhat stringy and viscid. It contains ptyalin, but in 
less amount than in parotid saliva ; and, according to Oehl, only 0.0036 per 
cent, of potassium sulphocyanide. 
Chemical Composition.—Sub-maxillary saliva (dog) : 
Water, . . . 991.45 per 1000. 
Organic Matter, 2.89 “ 
4.50 NaCl and CaCl2. 
1.16 CaC03, Calcium and Magnesium phosphates. 
Inorganic Matter, 5.66 
Mixed Saliva 
Parotid 
Sub-maxillary 
(Human) 
(Human) 
(Dog) 
(Jacubowitsch). 
(Hoppe-Seyler). 
(Herter). 
[Water, .... 
99-Si 
99-32 
99-44 
Solids, .... 
o.6S 
0.56 
Soluble organic bodies (ptyalin), 0.13 
Epithelium, mucin, 0.16 
0.34 
o.o66 
0.17 
Inorganic salts, 0.102 0.34 0.43 
Potassic sulphocyanide, .... 0.006 0.03 
Potassic and sodic chlorides, . . 0.084 ] 
Gases.—Pfliiger found that ioo cubic centimetres of the saliva contained 0.6 O; 64.7 C02 
(part could be pumped out, and part required the addition of phosphoric acid) ; 0.8 N; or, in 
100 vol. gas, 0.91 O; 97.88 C02; 1.21 N. [It therefore contains much more C02 than venous 
blood. Kiilz obtained from 100 c.c. of human saliva 7 c.c. of gas—O = 1 c.c., N = 2.5 c.c. 
and C02 — 3.5 c.c. Besides this there is 40—60 c.c. of fixed COa in the form of carbonates.] 
(V) Sub-lingual saliva is obtained by placing a very fine cannula in the 
ductus Rivinianus ; it is strongly alkaline in reaction, very sticky and viscid, 
contains much mucin, numerous salivary corpuscles, and some potassium 
sulphocyanide. 
147. THE MIXED SALIVA IN THE MOUTH.—The mixed 
saliva in the mouth is a mixture of the 
secretions from the salivary, mucous 
and other glands of the mouth. 
fi) Physical Characters.—It is 
an opalescent, tasteless, odorless, 
slightly glairy fluid, with a specific 
gravity of 1004 to 1009, and an alka- 
line reaction [due to alkaline bicar- 
bonates and phosphates]. The amount 
secreted in twenty-four hours = 200 to 
1500 grams (7 to 50 oz.)j according 
to Bidder and Schmidt, however, = 
1000 to 2000 grams. The solid con- 
stituents= 5.8 per 1000. 
Composition.—The solids are :—Epithe- 
lium and mucus, 2.2; ptyalin and albumin, 
1.4; salts, 2.2; potassium sulphocyanide, 0.04 
per 1000. The ash contains chiefly potash, 
phosphoric acid, and chlorine (Hammerbacher). 
Decomposition-products of epithelium, salivary corpuscles, or the remains of food, may render 
it acid temporarily, as after long fasting, and after much speaking; the reaction is acid in some 
cases of dyspepsia and in fever, owing to the stagnation and insufficient secretion. 
(2) Microscopic Constituents.—(a) The salivary corpuscles are 
slightly larger than the white blood-corpuscles (8 to 11 //), and are nucleated pro- 
toplasmic globular cells without an envelope (fig. 185). While the corpuscles are 
living, the particles in their interior exhibit molecular or Brownian move- 
Fig. 185. 
Microscopic characters of mixed saliva and the 
buccal secretion, a, epithelial cells ; b, sali- 
vary corpuscles; c, fat droplets; d, leuco- 
cytes ; e, spirochseta buccalis; f, comma bacil- 
lus of the mouth ; g, Leptothrix buccalis; h, 
i, k, different forms of fungi. [Sec. 147. 
260 
FUNCTIONS OF SALIVA. 
ment. The dark granules lying in the protoplasm are thrown into a trembling 
movement, from the motion of the fluid in which they are suspended. This 
dancing motion stops when the cell dies. 
[The Brownian movements of these suspended granules are purely physical, and are ex- 
hibited by all fine microscopic particles suspended in a limpid fluid, e. g., gamboge rubbed up in 
water, particles of carmine, charcoal, etc.] 
(£) Pavement epithelial cells from the mucous membrane of the mouth and tongue; they 
are very abundant in catarrh of the mouth (fig. 185). 
(r) Living organisms, which live and thrive in the cavities of the teeth, nourished by the 
remains of food. Amongst these are Leptothrix buccalis (figs. 171,185) and small bacteria-like 
organisms. The threads of the leptothrix penetrate into the canals of the dentine, and produce 
dental caries. [Miller has found twenty-five varieties of micro-organisms, including cocci (Iodo- 
coccus vaginatus), bacteria (Bacillus buccalis maximus), vibrios, spirilla (Spirillum sputigenum), 
and spirochsetre (Spirochseta dentium), eight of them present in the stomach and twelve in the 
intestines. The Zooglea form of Leptothrix forms the yellow scum on the teeth.] 
(3) Chemical Properties.—(a) Organic Constituents.—Serum-albu- 
min is precipitated by heat and by the addition of alcohol. In saliva, mixed 
with much water and shaken up with C02, a globulin-like body is precipitated ; 
mucin occurs in small amount. Amongst the extractives, the most important is 
ptyalin; fats and urea occur only in traces. In twenty-four hours 130 
milligrams of potassium or sodium sulphocyanide are secreted. 
[Mucin makes saliva viscid. It is precipitated by acetic acid, but if much NaCl be added an 
excess of acid will not precipitate it. It is a very complex body, but it can be split up into a 
proteid-like body and a carbohydrate (§ 250, 1).] 
(b) Inorganic Constituents.—Sodium and potassium chlorides, potassium 
sulphate, alkaline and earthy phosphates, ferric phosphate. 
According to Schonbein, the saliva contains traces of nitrites (detected by adding dilute sul- 
phuric acid and diamido-benzol to dilute saliva), which give a yellow color (Gries). There are 
also traces of ammonia (Briicke). 
Abnormal Constituents.—In diabetes mellitus, lactic acid, derived from a further decom- 
position of grape-sugar, is found. It dissolves the lime in the teeth, giving rise to diabetic dental 
caries. Frerichs found leucin, and Vulpian increase of albumin in albuminuria. Of foreign sub- 
stances taken into the body, the following appear in the saliva: Mercury, potassium, iodine, and 
bromine. 
Saliva of New-Born Children.—In new-born children, the parotid alone 
contains ptyalin. The diastatic ferment seems to be developed in the sub- 
maxillary gland and pancreas, at the earliest, after two months. Hence, it is 
not advisable to give starchy food to infants. No ptyalin has been found in the 
saliva of infants suffering from thrush (Oidium albicans—Zweifel). The dias- 
tatic action of saliva is not absolutely necessary for the suckling, feeding as it 
does upon milk. The mouth during the first two months is not moist, but at 
a later period saliva is copiously secreted (.Korowin); after the first six months 
the salivary glands increase considerably. The eruption of the teeth—owing 
to the irritation of the mucous membrane—produces a copious secretion of 
saliva. 
148. PHYSIOLOGICAL ACTIONS OF SALIVA.—I. Diastatic 
Action.—The most important chemical action exerted by saliva in digestion 
is its diastatic or amylolytic action (Leuchs, 1831), i. e., the transformation of 
starch into dextrin and some form of sugar. This is due to the ptyalin—a 
hydrolytic ferment or enzyme—which, even when it is present in very 
minute quantity, causes starch to take up water and become soluble, the fer- 
ment itself undergoing no essential change in the process. [Ptyalin belongs to 
the group of unorganized ferments (§ 250, 9). Like all other ferments, it acts 
only within a certain range of temperature, being most active about 40° C. 
Its energy is permanently destroyed by boiling. It acts best in a slightly alka- 
line or neutral medium.] Sec. 148.] 
261 
ACTION OF SALIVA ON STARCH. 
II. Saliva dissolves those substances which are soluble in water; its alkaline 
reaction enables it to dissolve some substances which are not soluble in water 
alone, but require the presence of an alkali. 
III. Saliva moistens dry food and aids mastication and the formation of the 
“bolus,” while by its mucin it helps the act of swallowing, the mucin being 
given off unchanged in the faeces. The ultimate fate of ptyalin is unknown. 
[IV. Saliva also aids articulation, and according to Liebig it carries down into 
the stomach small quantities of O.] 
[V. It is necessary to the sense of taste to dissolve sapid substances, and bring 
them into relation with the end-organs of the nerves of taste.] 
Saliva has no action on proteids or on fats. 
The presence of a peptone-forming ferment has recently been detected in saliva (Hufner, 
Munk, Kiihne). [Perfectly healthy human saliva has no poisonous properties.] 
[Action of Saliva on Starch.—Starch-grains consist of granulose or 
starch enclosed by coats of cellulose. Starch-grains, e.g., of the potato, con- 
sist of oval microscopic granules with concentric markings arranged in a lob- 
sided manner around an eccentrically placed spot, the hilum (fig. 186). Cellu- 
lose does not appear to be affected by saliva, so that saliva acts but slowly on 
raw unboiled starch. If the starch be boiled so as to swell up the starch- 
grains, and rupture the cellulose envelopes, the amylolytic action takes place 
rapidly. If starch-paste or starch-mucilage, made by boiling starch in water, 
be acted upon by saliva, especially at the temperature of the body, the first 
physical change observable is the liquefaction of the paste, the mixture be- 
coming more fluid and transparent. The change takes place in a few minutes. 
When the action is continued, important chemical changes occur.] “ 
According to O’Sullivan, Musculus, and v. Mering, the diastatic ferment of 
saliva (and of the pancreas), by acting upon starch or glycogen, forms dextrin 
and maltose (both soluble in water). Several closely allied varieties of dex- 
trin, distinguishable by their color-reactions, seem to be produced (Briicke). 
Erythrodextrin is formed first, it gives a red color with iodine; then a 
reducing dextrin—achroodextrin, which gives no color-reaction with iodine. 
The sugar formed by the action of ptyalin upon starch is maltose (C12H22On- 
H20), which is dis- 
tinguished from grape- 
sugar (C12H24012) by con- 
taining one molecule less 
of water, which, how- 
ever, it holds as a mole- 
cule of water of hydra- 
tion. [Maltose also dif- 
fers from grape-sugar in 
its greater rotatory power 
on polarized light, the 
former = -)- 150°, the 
latter -(- 56°, and in its 
smaller power of reduc- 
ing cupric oxide, the ratio begin 100 : 61. Thus, between the original starch 
and the final product, maltose, several intermediate bodies are formed. The 
starch gives a blue with iodine, but after it has been acted on for a time it gives 
a red or violet color, indicating the presence of erythrodextrin, there being a 
simultaneous production of sugar; but ultimately no color is obtained on add- 
ing iodine—achroodextrin, which gives no color with iodine,—and maltose 
being formed. The presence of the maltose is easily determined by testing 
with Fehling’s solution.] 
Fig. 186. 
Grains of potato-starch X 300. 262 
[Sec. 148. 
CONDITIONS AFFECTING THE ACTION OF SALIVA. 
[Brown and Heron suggest that the final result of the transformation may be 
represented by the equation— 
i°(Cj2H20Ojo) + 8H20 = 8(C]2H22Ou) -f- 2(C12tf20O10) 
Soluble starch. Water. Maltose. Achroodextrin. 
The ferment slowly changes maltose into grape-sugar or dextrose. This 
result may be brought about much more rapidly by boiling maltose with dilute 
sulphuric or hydrochloric acid.] Achroodextrin ultimately passes into maltose, 
and this again into dextrose; the other form of dextrin does not seem to 
undergo this change (Seegen’s Dystropodextrin). For the further changes 
that maltose undergoes in the intestine, see § 183, II. 2. 
[Action of Acid on Starch.—Starch may be converted into dextrin and 
sugar by boiling it with a dilute acid, e. g., HC1, but there is a difference 
between this hydration producing an acid and that produced by a ferment like 
ptyalin. In the former case the sugar produced is wholly dextrose, no maltose 
being formed.] 
[The formula of starch is usually expressed as C6H]0O5, but the researches already mentioned, 
and those of Brown and Heron, make it probable that it is more complex, which we may pro- 
visionally represent by »C12H20O]0. According to Musculus and Meyer, erythrodextrin is a 
mixture of dextrin and soluble starch.] 
Preparation of Ptyalin.—(1) Like all other hydrolytic ferments, it is carried down with any 
copious precipitate that is produced in the fluid which contains it, and it can be isolated from 
the precipitate. The saliva is acidulated with phosphoric acid, lime-water is added until the 
reaction becomes alkaline, when a precipitate of the basic calcium phosphate occurs, which 
carries the pytalin along with it. This precipitate is collected on a filter, washed with water, 
which dissolves the ptyalin, and from its watery solution it is precipitated by alcohol as a white 
powder. It is redissolved in water and reprecipitated and is obtained pure (Cohnheim). 
(2) Glycerin or v. Wittich’s Method.—The salivary glands [rat] are chopped up, placed 
in absolute alcohol for twenty-four hours, taken out and dried, and afterwards placed in glycerin 
for several days, which extracts the ptyalin. It is precipitated by alcohol from the glycerin 
extract. 
(3) William Roberts recommends the following solutions for extracting ferments from organs 
which contain them:—(1) A 3 to 4 per cent, solution of a mixture of 2 parts of boracic acid 
and 1 part borax. (2) Water, with 12 to 15 per cent, of alcohol. (3) 1 part chloroform to 200 
of water. 
Conditions affecting the Diastatic Action of Saliva.—(«) The diastatic or sugar-form- 
ing action is known by—(1) The disappearance of the starch. When a small quantity of 
starch is boiled with several hundred times its volume of water, starch mucilage is obtained, 
which strikes a blue color with iodine. If to a small quantity of this starch a sufficient amount 
of saliva be added, and the mixture kept for some time at the temperature of the body, the blue 
color disappears. (2) The presence of sugar is proved directly by using the tests for sugar 
(3 149)- 
[b) The action takes place more slowly in the cold than at the temperature of the body—its 
action is enfeebled at 55° C., and destroyed at 750 C. [Paschutin). The most favorable temper- 
ature is 350 to 390 C. 
(r) The ptyalin itself does not seem to be changed during its action, but ptyalin which has 
been used for one experiment is less active when used the second time (Paschutin). 
Ptyalin differs from diastase—the ferment in germinating grains—in so far that the latter first 
begins to act at -j- 66° C. Ptyalin decomposes salicin into saligenin and grape-sugar [Prericks 
and Stdd/er). 
(1d) Saliva acts best in an exactly neutral medium, but it also acts in an alkaline and even in 
a slightly acid fluid; strong acidity prevents its action. The ptyalin is only active in the stomach 
when the acidity is due to organic acids (lactic or butyric), and not when free hydrochloric acid 
is present (van de Velde). In both cases, however, dextrin is formed. Ptyalin is destroyed by 
hydrochloric acid or digestion by pepsin (Chittenden and Griswold, Langley). Even butyric 
and lactic acids formed from grape-sugar in the stomach may prevent its action; but if the acidity 
be neutralized, the action is resumed [Cl. Bernard). 
[e) The addition of common salt, ammonium chloride, or sodium sulphate (4 per cent, solu- 
tion), increases the activity of the ptyalin, and C02, acetate of quinine, strychnia, morphia, 
curare, 0.025 per cent, sulphuric acid, have the same effect. 
(f) Much alcohol and caustic potash destroy the ptyalin : long exposure to the air weakens its 
action, sodium carbonate and magnesium sulphate delay the action [Pfeiffer). Salicylic acid 
and much atropin arrest the formation of sugar. Sec. 148.] 
TESTS FOR SUGAR. 
263 
(g) I’tyalin acts very feebly and very gradually upon raw starch, only after 2 to 3 hours 
(,Schiff); while upon boiled starch it acts rapidly. [Hence the necessity for boiling thoroughly 
all starchy foods.] 
(h) The various kinds of starch are changed more or less rapidly according to the amount of 
cellulose which they contain; raw potato starch after 2 to 3 hours, raw maize starch after 2 to 3 
minutes (Hammarsten); wheat starch more quickly than that of rice. When the starches are 
powdered and boiled, they are changed with equal rapidity. 
(i) A mixture of the saliva from all the glands is more active than the saliva from any single 
gland (Jakubowitsch), while mucin is inactive. 
[(j) The action of ptyalin, like all such ferments, is hindered by the products of its own action. 
As the sugar accumulates, the action of the ptyalin is slowed or arrested. If the sugar formed 
be removed the ptyalin again acts on the remainder of the starch.] 
[Effect of Tea.—Tea has an intensely inhibitory effect on salivary digestion, which is due to 
the large quantity of tannin contained in the tea-leaf. Coffee and cocoa have only a slight 
effect on salivary digestion. The only way to mitigate the inhibitory effect of tea on salivary 
digestion is “ not to sip the beverage with the meal, but to eat first and drink afterwards ” 
(Iioberts').~\ 
149. TESTS FOR SUGAR.—1. Trommer’s test depends upon the 
fact that, in alkaline solutions, sugar acts as a reducing agent ; in this 
case a metallic oxide is changed into a suboxide. To the fluid to be investi- 
gated, add Y?, of its volume of a solution of caustic potash (soda), specific 
gravity 1.25, and a few drops of a weak solution of cupric sulphate, which 
causes at first a bluish precipitate, consisting of hydrated cupric oxide, but it is 
redissolved, giving a clear blue fluid, if sugar be present. Heat the upper 
stratum of the fluid, and a yellow or red ring of cuprous oxide is obtained, 
which indicates the presence of sugar ; 2CuO — O == Cu20. 
The solution of hydrated cupric oxide is caused by other organic substances; but the final 
stage, or the production of cuprous oxide, is obtained only with certain sugars—grape-, fruit- 
and milk- (but not cane-) sugar. Fluids which are turbid must be previously filtered, and if 
they are highly colored, they must be treated with basic lead acetate; the lead acetate is after- 
wards removed by the addition of sodium phosphate and subsequent filtration. If very small 
quantities of sugar are present along with compounds of ammonia, a yellow color instead of a 
yellow precipitate may be obtained. In doing the test, care must be taken not to add too much 
cupric sulphate. 
[2. Fehling’s Solution is an alkaline solution of potassio-tartrate of 
copper. Boil a small quantity of the deep-blue-colored Fehling’s solution in 
a test-tube, and add to the boiling test a few drops of the fluid supposed to con- 
tain the sugar. If sugar be present, the copper solution is reduced, giving a 
yellow or reddish precipitate. The reason for boiling the test itself is, that the 
solution is apt to decompose when kept for some time, when it is precipitated 
by heat alone. This is one of the best and most reliable tests for the presence 
of sugar. In Pavy’s modification of this test, ammonia is used instead of a 
caustic alkali (§ 267).] 
(3) Bottger’s Test.—Alkaline bismuth oxide solution is best prepared, according to Ny- 
lander, as follows:—2 grms. bismuth subnitrate, 4 grms. potassic and sodic tartrate, 100 grms. 
caustic soda of 8 per cent. Add 1 c.c. to every 10 c.c. of the fluid to be investigated. When 
boiled for several minutes, the sugar causes the reduction and deposits a black precipitate of 
metallic bismuth. [According to Salkowski the urine of a person taking rhubarb gives the same 
reaction with this test.] 
(4) Moore and Heller’s Test.—Caustic potash or soda is added until the mixture is 
strongly alkaline; it is afterwards boiled. If sugar be present, a yellow, brown, or brownish- 
black coloration is obtained. If nitric acid be added, the odor of burned sugar (caramel) and 
formic acid is obtained. 
(5) Mulder and Neubauer’s Test.—A solution of indigo-carmine, rendered alkaline with 
sodic carbonate, is added to the sugar solution until a slight bluish color is obtained. When the 
mixture is heated, the color passes into purple, red, and yellow. When shaken with atmospheric 
air, the fluid again becomes blue. 
Molisch’s Test.—To 5 c.cm. of the fluid add 2 drops of a 17 per cent, alcoholic solution 
of a-naphthol, or a solution of thymol. Add I to 2 c.cm. of concentrated sulphuric acid, and 
shake the mixture. The presence of sugar colors the a-naphthol mixture deep violet, the 264 
QUANTITATIVE ESTIMATION OF SUGAR. 
[Sec. 149. 
thymol deep red. The subsequent addition of water causes a precipitate of similar color, which 
is insoluble in concentrated hydrochloric acid. Albumin, casein, and peptone give the same re- 
action (Seegen), but the deposit on the addition of water is soluble in concentrated hydro- 
chloric acid. 
Other tests, including the Phenyl-hydrazin test, are described in \ 267. 
In all cases where albumin is present it must be removed—in urine by acidulating with acetic 
acid and boiling ; in blood, by adding four times its volume of alcohol and afterwards filtering, 
while the alcohol is expelled by heat. [If peptone be present the cuprous oxide may not be 
precipitated on boiling. The mixture must be evaporated down, the sugar dissolved out by al- 
cohol, and the test for sugar applied to a watery solution of the alcoholic extract.] 
150. QUANTITATIVE ESTIMATION OF SUGAR.—I. By Fermentation.— 
In the glass vessel (fig. 187, a) a measured quantity (20 c.cm.) of the fluid (sugar) is placed 
along with some yeast, while b contains concentrated sul- 
phuric acid. The whole apparatus is then weighed. When 
exposed to a sufficient temperature (xo° to 40° C.), the sugar 
splits into 2 molecules of alcohol and 2 of carbon dioxide, 
C6H1206 = 2(C2H60) + 2(C02), 
Grape-sugar = 2 alcohol + 2 carbon dioxide; 
and in addition there are formed traces of glycerin and suc- 
cinic acid. The C02 escapes from b, and as it passes through 
the H2S04, the C02 yields to the latter its water. The appa- 
ratus is weighed after two days, when the reaction is ended, 
and the amount of sugar is calculated from the loss of weight 
in the 20 c.cm. of fluid. 100 parts of water-free sugar = 
48.89 parts C02, or 100 parts C02 correspond to 204.54 parts 
of sugar. 
II. Titration.—By means of Fehling’s solution, which is made of such a strength that all 
the copper in 10 cubic centimetres of the solution is reduced by 0.05 gram of grape-sugar 
(2 267). ... 
III. Circumpolarization.—The saccharimeter of Soleil-Ventzke may be used to deter- 
mine the amount of sugar present. It may also be used for the quantitative estimation of 
albumin. Sugar rotates the ray of polarized light to the right and albumin to the left. The 
amount of rotation, or “ specific rotatory power,” is directly proportional to the amount of the 
rotating substance present in the solution, so that the amount of rotation of the ray indicates 
the amount of the substance present. By the term “ specific rotatory power ” is meant the 
degree of rotation which is produced by 1 grm. of the substance dissolved in 1 c.cm. of water, 
when examined in a layer 1 decimetre thick. For yellow light the specific rotation of grape- 
sugar is -f- 56°. 
In fig. 188 the light from the lamp falls upon a crystal of calc-spar. Two Nicol’s prisms are 
placed at v and s, v is movable round the axis of vision, while .y is fixed. In m Soleil’s double 
plate of quartz is placed, so that one-half of it rotates the ray of polarized light as much to the 
right as the other rotates it to the left. In n the field of vision is covered by a plate of left- 
rotatory quartz. At b c is the compensator, composed of two right-rotatory prisms of quartz, 
which can be displaced laterally by the milled head, g, so that the polarized light passing 
through the apparatus can be made to pass through a thicker or thinner layer of quartz. When 
these right-rotatory prisms are placed in a certain position, the rotation of the left-rotatory 
quartz at n is exactly neutralized. In this position the scale on the compensator has its nonius 
exactly at o, and both halves of the double plate at m appear to have the same color to the 
observer, who from v looks through the telescope placed at e. Rotate the Nicol’s prism at v 
until a bright rose-colored field is obtained. In this position the telescope must be so adjusted 
that the vertical line bounding the two halves shall be distinctly visible. The apparatus is now 
ready for use. 
Fill a tube, 1 decimetre in length, with urine containing sugar or albumin, the urine being 
perfectly clear. The tube is placed between m and n. By rotating the Nicol’s prisms, v, the 
rose-color is again obtained. The compensator then rotated until both halves of the 
field of vision have exactly the same color. When this is obtained, read off on the scale the 
number of degrees the nonius is displaced to the right (sugar) or to the left (albumin) from zero. 
The number of degrees indicates directly the number of grams of the rotating substance 
present in 100 c.c. of the fluid. If the fluid is very dark colored, it must be decolorized by 
filtering it through animal charcoal (Seegen), [or the coloring matter may be precipitated by the 
addition of lead acetate.] If the sugary urine contains albumin, the latter must be removed by 
boiling and filtration. A turbidity not removed by filtration may be got rid of by adding a drop 
of acetic acid or several drops of sodic carbonate or milk of lime, and afterwards filtering. [One 
may also employ the apparatus of Mitscherlich, or the “ half-shadow apparatus ” of Laurent.] 
Fig. 187. 
Apparatus for the quantitative 
estimation of sugar by fer- 
mentation. Sec. 151.] 
INTRODUCTION OF THE FOOD. 
151. MECHANISM OF THE DIGESTIVE APPARATUS.— 
This embraces the following acts :— 
1. The introduction and mastication of the food; the movements of the 
tongue ; insalivation ; formation of the bolus of food. 
2. Deglutition. 
3. The movements of the stomach, small and large intestine. 
4. The excretion of faecal matters. 
Soleil-Ventzke’s polarization apparatus. 
Fig. 188. 
152. INTRODUCTION OF THE FOOD.—Fluids are taken into 
the mouth in three ways :—(i) By suction, the lips are applied air-tight to 
the vessel containing the fluid, while the tongue is retracted (the lower jaw 
being often depressed) and acts like the piston in a suction-pump, thus causing 
the fluid to enter the mouth. Herz found that the negative pressure caused by 
an infant while sucking = 3 to 10 mm. Hg. (2) The fluid is lapped when it 
is brought into direct contact with the lips, and is raised by aspiration and 
mixed with air so as to produce a characteristic sound in the mouth. (3) 
Fluid may be poured into the mouth, and as a general rule, the lips are applied 
closely to the vessel containing the fluid. [Sec. 152. 
266 
MASTICATION. 
Solids, when they consist of small particles, are licked up with the lips, 
aided by the movements of the tongue. In the case of large masses, a part is 
bitten off with the incisor teeth, and is afterwards brought under the action of 
the molar teeth by means of the lips, cheeks, and tongue. 
153. MASTICATION .—The process of mastication is a complicated 
co-ordinate muscular act carried out under the direction of the central nervous 
system, with the aid of guiding sensations originating in the structures of the 
mouth. 
The articulation of the jaw is provided with an interarticular cartilage—the meniscus—which 
prevents direct pressure being made upon the articular surface when the jaws are energetically 
closed, and which also divides the joint into two cavities, one lying over the other. The capsule 
is so lax that, in addition to the raising and depressing of the lower jaw, it permits of the lower 
jaw being displaced forwards, whereby the meniscus moves with it, and covers the articular 
surface. 
The process of mastication embraces:—(a) The elevation of the 
jaw, accomplished by the combined action of the Temporal, Masseter, and 
Internal Pterygoid Muscles. If the lower jaw was previously so far depressed 
that its articular surface rested upon the tubercle, it now passes backwards upon 
the articular surface. 
(b) The depression of the lower jaw is caused by its own weight, aided 
by the action of the anterior bellies of the Digastrics, the Mylo- and Genio- 
hyoid and Platysma. The muscles act especially during forcible opening of 
the mouth. The necessary fixation of the hyoid bone is obtained through the 
action of the Omo- and Sterno-hyoid, and by the Sterno-thyroid and Thyro- 
hyoid. 
When the articular surface of the lower jaw passes forwards on to the tubercle, the External 
Pterygoids actively aid in producing this (Berard). 
(c) Displacement of the Articular Surfaces.—During rest, when the 
mouth is closed, the incisor teeth of the lower jaw are within the arch of the 
upper incisors. When in this position. the jaw is protruded by the External 
Pterygoids, whereby the articular surface passes on to the tubercle (and, there- 
fore, downwards), while the lateral teeth are thereby separated from each other. 
The jaw is retracted by the Internal Pterygoids without any aid from the pos- 
terior fibres of the Temporals. When one articular surface is carried forwards, 
the jaw is protruded and retracted by the External and Internal Pterygoid of 
the same side. At the same time, there is a transverse movement, whereby the 
back teeth of the protruded side are separated from each other. 
During mastication, the individual movements of the lower jaw are variously 
combined, and especially with lateral grinding movements, while the food to 
be masticated is kept from passing outwards by the action of the muscles of 
the lips (Orbicularis oris) and the Buccinators, while the tongue continually 
pushes the particles between the molar teeth. The energy of the muscles of 
mastication is regulated by the sensibility of the teeth, and the muscular 
sensibility of the muscles of mastication, as well as by the general sensibility of 
the mucous membrane of the mouth and lips. At the same time, the mass is 
mixed with saliva, the divided particles cohere, and are formed into a mass or 
bolus, of a long, oval shape, by the muscles of the tongue. The bolus then 
rests on the back of the tongue, ready to be swallowed. 
Nerves of Mastication.—The muscles of mastication receive their motor nerves from the 
third branch of the trigeminus, the mylo-hyoid and the anterior belly of the digastric being sup- 
plied from the same source. The genio-, omo-, and sterno hyoid, sterno-thyroid, and thyro- 
hyoid are supplied by the hypoglossal, while the facial supplies the posterior belly of the digastric, 
the stylo-hyoid, the platysma, the buccinator, and the muscles of the lips. The general centre 
for the muscles of mastication lies in the medulla oblongata (§ 367). 
When the mouth is closed, the jaws are kept in contact by the pressure of the air, as the Sec. 153.] 
267 
STRUCTURE OF THE TEETH. 
cavity of the mouth is rendered free from air, and the entrance of air is prevented anteriorly 
by the lips and posteriorly by the soft palate. The pressure exerted by the air is from 2 to 4 
mm. Hg. (Metzger and Donders). 
[Effect on the Circulation.—Marey found that mastication trebled the velocity of the blood- 
current in the carotid (horse), while Frangois-Frank observed that the circulation of the brain 
(in man) is increased; hence it is evident that mastication implies an increased supply of blood 
to the nerve-centres.] 
154. STRUCTURE AND DEVELOPMENT OF THE TEETH. 
—[Each tooth consists of a portion above the gum and termed the crown, a 
part imbedded in the gum, the fang, and a narrow neck connecting these two.] 
A tooth is just a papilla of the mucous membrane of the gum, which has under- 
gone a characteristic development. In its simplest form, as in the teeth of the 
Enamel. 
Dentine. 
Pulp 
Cavity. 
Cement. 
Fig. 191. 
Fig. 189. 
Fig. 190. 
Fig. 189.—Longitudinal section of an incisor tooth. Fig. 190.—Transverse section of dentine. 
The light rings are the walls of the dentinal tubules; the dark centres with the light points 
are the fibres of Tomes lying in the tubules. Fig. 191.—Interglobular spaces in dentine. 
lamprey, the connective-tissue basis of the papilla is covered with many layers 
of corneous epithelium. In human teeth, part of the papilla is transformed 
into a layer of calcified dentine, while the epithelium of the papilla produces 
the enamel, the fang of the tooth being covered by a thin accessory layer of 
bone, the crusta petrosa or cement. 
The dentine or ivory which surrounds the pulp-cavity and the canal of the 
fang (fig. 189) is very firm, elastic, and brittle. Dentine, like the matrix of 
bone, when treated in a certain way, presents a fibrillar structure. It is per- 
meated by innumerable long, tortuous, wavy tubes—the dentinal tubules— 
each of which communicates with the pulp-cavity by means of a fine opening 
and passes more or less horizontally outwards as far as the outer layers of the 
dentine. The tubules are bounded by an extremely resistant, thin, cuticular 
membrane, which strongly resists the action of chemical reagents. These [Sec. 154. 
268 
STRUCTURE OF THE TEETH. 
tubules are filled completely by soft fibres, the “ fibres of Tomes,” which 
are merely greatly elongated and branched processes of the odontoblasts of 
the pulp. 
The dentinal tubes, as well as the fibres of Tomes, anastomose throughout 
their entire extent by means of fine processes. As the fibres approach the 
enamel, which they do not penetrate, some of them bend on themselves, and 
form a loop (fig. 192, z), whilst others pass into the “ interglobular spaces ” 
(fig. 191), which are so abundant in the outer part of the dentine. The inter- 
globular spaces are small spaces bounded by curved surfaces. Certain curved 
lines, “ Schreger’s lines,” maybe detected with the naked eye in the dentine 
(<?. g., of the elephant’s tusk) running parallel with the contour of the tooth. 
They are caused by the fact that at these parts all the chief curves in the 
dentinal tubules follow a similar course. 
The enamel, the hardest substance in the body (resembling apatite), covers 
the crown of the teeth. It consists of hexagonal flattened prisms arranged 
side by side like a palisade (fig. 192, i?andC). They are 3 to 5 ,u inch) 
Fig. 192. 
Fig. 193- 
Fig. 192.—Section of a tooth between the dentine and enamel, a, enamel; c, dentinal tubules; 
B, enamel prisms highly magnified; C, transverse sections of enamel prisms. Fig. 193.— 
Transverse sections of the fang, a, cement with bone corpuscles; b, dentine with tubules; 
c, boundary between both. 
broad, not quite uniform in thickness, curved slightly in different directions, 
and, owing to inequalities of thickness, they exhibit transverse markings. 
They are elongated calcified, cylindrical, epithelial cells. Retzius de- 
scribed dark-brown lines running parallel with the outer boundary of the 
enamel, due to the presence of pigment (fig. 189). The fully-formed enamel 
is negatively doubly refractive and uniaxial, while the developing enamel is 
positively doubly refractive (Hoppe-Seyler). 
The cuticula or Nasmyth’s membrane covers the free surface of the 
enamel as a completely structureless membrane 1 to 2 \x thick, but in quite 
young teeth it exhibits an epithelial structure, and is derived from the outer 
epithelial layer of the enamel organ. 
The cement or crusta petrosa is a thin layer of bone covering the fang 
(fig. 193, a). The bone lacunae communicate directly with the dental tubules 
of the fang. Haversian canals and lamellae are only found where the layer of 
cement is thick, and the former may communicate with the pulp-cavity. Very 
thin layers of cement may be devoid of bone-corpuscles. Sharpey’s fibres occur Sec. 154.] 
STRUCTURE OF THE TEETH. 
269 
in the cement of the dog’s tooth ; while in the horse’s tooth single bone-cor- 
puscles are surrounded by a capsule. In the periodontal membrane, which 
is just the periosteum of the alveolus, coils of blood-vessels similar to the renal 
glomeruli occur. They anastomose with each other, and are surrounded by a 
delicate capsule of connective tissue. 
The pulp in a fully-grown tooth represents the remainder of the dental 
papilla around which the dentine was deposited. It consists of a very vascular 
indistinctly fibrillar connective tissue, laden with cells. The layers of cells, 
resembling epithelium, which lie in direct contact with the dentine, are called 
odontoblasts, i. e., those cells which build up the dentine. These cells 
send off long branched processes into the dentinal tubules, whilst their 
nucleated bodies lie on the surface of the pulp, and form connections by 
processes with other cells of the pulp and with neighboring odontoblasts. 
Numerous non-medullated nerve-fibres (sensory from the trigeminus), whose 
mode of termination is unknown, occur in the pulp. 
The periosteum or periodontal membrane of the fang is, at the same 
Epithelium. 
ithelium. 
Tunica 
propria. 
Tunica 
propria. 
Bone of jaw. 
A.—Vertical section of the jaw of a sheep embryo x 4°- *5 dental furrow; 2, dental ridge; 
3, enamel germ. B.—Transverse section of the lower jaw of a four months’ human foetus 
X 40. 1, dental ridge; 2, stalk of the enamel organ ; 3, enamel organ; a, peripheral cells ; 
b, germ pulp; c, cylindrical cells of enamel; 4, papilla. C.—a, dental ridge; b, enamel 
organ with (1) outer epithelium, (2) middle stellate layer, (3) enamel prism-cell layer; c, 
dentine germ with blood-vessels, and the long osteoblasts on the surface; d, tooth-sac; e, 
secondary enamel germ. 
Fig. 194. 
time, the alveolar periosteum, and consists of connective tissue with elastic 
fibres and many nerves. 
Chemistry of a Tooth.—The teeth consist of a gelatine-yielding matrix infiltrated with 
calcium phosphate and carbonate (like bone), (i) The dentine contains—organic matter, 
27.70; calcium phosphate and carbonate, 72-06; magnesium phosphate, 0.75 ; with traces of 
iron, fluorine, and sulphuric acid. 
(2) The enamel contains an organic proteid matrix allied to the substance of epithelium. It 
consists of 3.60 organic matter and 96.00 of calcium phosphate and carbonate, 1.05 magnesium 
phosphate, with traces of calcium fluoride and an insoluble chlorine compound. 
(3) The cement is identical with bone. 
The gums are devoid of mucous glands, very vascular, and often provided with long vascular 
papillae, which are sometimes compound. 
Development of a Tooth.—It begins at the end of the second month of foetal life. Along 
the whole length of the foetal gum is a thick projecting ridge composed of many layers of 
epithelium (fig. 194 A). A depression, the dental groove, also filled with epithelium, occurs 
in the gum, and runs along under the ridge. The dental groove becomes deeper throughout its 
entire length, and on transverse section presents the appearance of a dilated flask, while at the 
same time it is filled with elongated epithelial cells, which form the “ enamel organ,” or 
“common enamel germ.” A conical papilla, the “ dentine germ,” grows up from the [Sec. 154. 
DEVELOPMENT OF A TOOTH. 
mucous tissue, of which the gum consists, towards the enamel organ (figs. 194 B, 194 C), so 
that the apex of the papilla comes to have the enamel organ resting upon it like a double cap. 
Afterwards, owing to the development of connective tissue, the parts of the enamel organ lying 
between and uniting the individual dentine germs, disappear, and gradually the connective- 
tissue forms a tooth sac enclosing the papilla and its enamel organ (fig. 194 A, 3). 
Those epithelial cells (figs. 194, B, 3, 194 C) of the enamel organ, which lie next the top of 
the papilla, are cylindrical, and become calcified to form enamel prisms. The layer of cells of 
the double cap, which is directed towards the tooth-sac, becomes flattened, fuses, undergoes a 
horny transformation, and becomes the cuticula, whilst the cells which lie between both layers 
undergo an intermediate metamorphosis, so that they come to resemble the branched stellate 
cells of the mucous tissue, and gradually disappear altogether. 
The dentine is formed in the most superficial layer of the projecting connective tissue of the 
dental papilla, owing to the calcification of the continuous layer of odontoblasts which occur 
there (figs. 194 C, 195). During the process, fibres or branches of these cells are left unaffected, 
and remain as the fibres of Tomes. Exactly the same process occurs as in the formation of bone, 
the odontoblasts forming around themselves a calcified matrix. The cement is formed from the 
soft connective-tissue of the dental alveolus. 
Peripheral flat 
cells. 
Dental Sac. - 
Outer layer. 
Inner layer. 
Enamel pulp. 
Enamel cells. J 
Enamel. 
Enamel 
organ. 
Dentine. 
Papilla. 
Odontoblasts 
Spherical elements 
with blood-vessels. 
Bone of the lower jaw, 
Fig- 195- 
Transverse section of the lower jaw of a new-born dog x 4°- The dental sac is shown only on 
the left side. The tissues originating from connective tissue are shown on the left, and 
those of epithelial origin on the right. 
Dentition.—During the development of the first, temporary or milk- 
teeth, a special enamel organ (fig. 194, c) is formed near these, but it does not 
undergo development until the milk-teeth are shed; even the papilla is wanting 
at first. When the permanent tooth begins to develop, it opens into the 
alveolar wall of the milk-teeth from below. The tissue of this dental sac causes 
erosion, or eating away of the fang and even of the body of the milk-teeth, 
without its blood-vessels undergoing atrophy. The chief agents in the absorp- 
tion are the amoeboid cells of the granulation tissue. [Multinuclear giant-cells 
also erode the fangs of the teeth. The little cavities in which the large osteo- 
clasts lie are known as Howship’s lacunae or foveae.] 
Eruption of the Milk-Teeth.—The following is the order in which the 
twenty milk-teeth cut the gum, i. e., from the seventh month to the second 
year:—Lower central incisors, upper central incisors, upper lateral incisors, 
lower lateral incisors, first molar, canine, the second molars. Sec. 154.] 
ERUPTION OF THE TEETH. 
271 
[The figures indicate in months the period of eruption of each tooth.] 
Molars. 
Canines. 
Incisors. 
Canines. 
Molars. 
24 12 
18 
9 7 7 9 
18 
12 24 
[The permanent teeth succeed the milk-teeth, the process beginning about 
the seventh year. Ten teeth in each jaw take the place of the milk-teeth, while 
six teeth appear further back in each jaw. Thus the total number of permanent 
teeth is thirty-two. As the sacs from which the permanent teeth are devel- 
oped are formed before birth, they merely undergo the same process of develop- 
ment as the temporary teeth, only at a much later period. The last of the 
permanent molars—the wisdom-tooth—may not cut the jaw until the seventee7ith 
to the twenty-fifth year. At the sixth year the jaw contains the largest number 
of teeth, as all the temporary teeth are present, and, in addition, the crowns of 
all the permanent teeth, except the wisdom-teeth, making forty-eight in all 
(fig. x96). ] 
[Eruption of Permanent Teeth.—The age at which each tooth cuts the 
gum is given in years in the following table : — 
Molars. 
Bicuspid. 
Canines. 
Incisors. 
Canines. 
Bicuspid. 
Molars. 
17 12 
to to 6 
25 >3 
IO 9 
II to 12 
8 7 7 8 
II to 12 
9 IO 
12 17 
6 to to 
13 25 
[Action of Drugs on the Teeth.—All the conditions for putrefaction are present in the 
mouth; and when putrefac- 
tion occurs, the products 
(often acid) attack the den- 
tine and hasten its decay. 
Hence, the necessity for 
thorough daily cleansing of 
the teeth and mouth. The 
teeth may be cleaned by 
means of a soft tooth-brush 
and water, with or without 
the use of any of the numer- 
ous dentrifices, such as pow- 
dered chalk or charcoal. 
Astringents such as catechu 
and areca-nut are sometimes 
used. Mineral acids attack 
the teeth, and ought when 
taken to be sucked through 
a tube.] 
Lower jaw of a child, five years of age, with the surface removed 
to show the uncut permanent tooth-germs. 
Fig. 196. 
155. MOVEMENTS OF THE TONGUE.—The tongue, being a 
muscular organ, and extremely mobile, plays an important part in the process 
of mastication : (1) It keeps the food from passing from between the molar 
teeth. (2) It forms into a bolus the finely-divided food after it is mixed with 
saliva. (3) When the tongue is raised, the bolus lying on its dorsum is pushed 
backwards into the pharynx and oesophagus. 
The course of the fibres is threefold—longitudinally, from base to tip ; 
transversely, the fibres for the most part proceeding outwards from the verti- 
cally-placed septum linguae; vertically, from below upwards. Some of the 
muscles are confined to the tongue (intrinsic), while others (extrinsic) are 
attached beyond it to the hyoid bone, lower jaw, the styloid process, and the 
' palate. [Sec. 155. 
272 
MOVEMENTS OF THE TONGUE. 
[The Extrinsic Muscles of the Tongue.—The tongue is divided vertically by a fibrous 
septum, and on each side there are four extrinsic muscles. The hyo-glossus passes from the 
hyoid bone upwards into the tongue between the lingualis and stylo-glossus. When both muscles 
contract the tongue is drawn backwards. The genio hyo-glossus arises from the inner aspect of 
the anterior part of the ramus of the lower jaw, its fibres spread out in a fan-shaped manner, 
■some going to the hyoid bone, a few to the pharynx, but most enter the entire length of the 
tongue near the fibrous septum. Both muscles acting together protrude the tongue. The palato- 
glossus, in the anterior pillar of the fauces, enters the upper surface of the tongue, and is con- 
cerned in deglutition. The stylo-glossus passes from the styloid process down to the side of the 
tongue. These muscles pull back the tongue and raise its margins.] 
[The Intrinsic Muscles.—The superior or superficial lingual runs from the tip of the 
tongue towards the hyoid bone just under the mucous membrane. The transverse muscle, whose 
fibres run transversely from the septum to the sides of the tongue. The vertical fibres run in 
an arched direction downwards and outwards towards the dorsum of the tongue. The inferior 
or deep lingual muscle consists of a thick bundle of longitudinal fibres running along the under 
surface between the genio-hyo-glossus and the hyo-glossus. They shorten the tongue and turn 
its tip downwards.] 
Microscopically, the fibres are transversely striated, with a delicate sarcolemma, and very 
■often they are branched where they are inserted into the mucous membrane. The muscular 
bundles cross each other in various directions, and in the interspaces fat-cells and glands occur. 
Changes in form and position of the tongue: — 
(1) Shortening and broadening by the longitudinal muscle, aided by the hyo- 
glossus. 
(2) Elongation and narrowing, by the transversus linguae. 
(3) The dorsum is rendered concave by the transversus and the simultaneous 
action of the median vertical fibres. 
(4) Arching of the dorsum:—(a) Transversely, by the lowest transverse bun- 
dles; (b) longitudinally, by the lowest longitudinal muscles. 
(5) Protrusion, by the genio-glossus, 
while at the same time the tongue usually 
becomes narrower and longer (2). 
(6) Retraction, by the hyo-glossus and 
stylo-glossus, and (1) usually occurring 
at the same time. 
(7) Depression into the floor of the 
mouth, by the hyo-glossus. The floor 
of the mouth may be made deeper by 
depressing the hyoid bone. 
(8) Elevation of the tongue towards 
the palate :—(a) At the tip by the an- 
terior part of the longitudinal fibres; 
(h) in the middle by elevating the entire 
hyoid bone by the mylo-hyoid (iV. tri- 
geminus') ; (c) at the root by the stylo- 
glossus and palato-glossus, as well as 
indirectly by the stylo-hyoid (N. facia- 
lis). 
(9) Lateral movements, the tip of the 
tongue passing to the right or left; these 
are caused by the longitudinal fibres of one side. 
The motor nerve of the tongue is the hypoglossal (fig. 197). When this nerve is divided 
or paralyzed on one side, the tip of the tongue lying in the floor of the mouth is directed towards 
the sound side, because the tonus of the non-paralyzed longitudinal fibres shortens the sound 
side slightly. If the tongue be protruded, however, the tip passes towards the paralyzed side. 
This arises from the direction of the genio-glossus (from the middle downwards and outwards), 
and the tongue follows the direction of its action. The tongues of animals which have been 
killed exhibit fibrillar contractions of the muscles, sometimes lasting for a whole day. [Stirling 
has frequently found nerve-ganglia in the nerves of the tongue.] 
Fig. 197. 
The three nerves of the tongue, showing their 
curved course and their terminations. 1, 
Mandible; 2, hyoid bone; 3, internal caro- 
tid ; 4, lingual artery; 5, genio-glossus; 6, 
hyo-glossus ; 7, stylo-glossus ; 8, hypoglossal 
nerve; 9, lingual branch of fifth nerve; 10, 
glosso-pharyngeal ; II, facial nerve; 12, 
chorda tympani. Sec. 155.] 
DEGLUTITION. 
273 
[The sensory nerves are the lingual or gustatory branch of the fifth, which confers sensi- 
bility on the mucous membrane of the anterior two-thirds of the tongue. The lingual branch 
of the glosso-pharyngeal, which confers ordinary sensibility and the sense of taste on the posterior 
third of the tongue. The chorda tympani, which is the special nerve of taste for the anterior 
two-thirds of the tongue. There are also sympathetic fibres on the blood-vessels (fig. 197).] 
156. DEGLUTITION.—[By a complicated series of co-ordinated mus- 
cular acts the bolus of food is carried from the mouth successively through the 
pharynx and oesophagus into the stomach.] 
[The pharynx (112 mm. in length) extends from the base of the skull to the lower border of 
the cricoid cartilage, where it becomes continuous with the oesophagus. Above, it communicates 
with the nose, mouth and larynx (fig. 198). It is lined by a mucous membrane, and strengthened 
and made contractile externally by a layer of striped muscular fibres running, for the most part, 
somewhat transversely, and 
made up of the three con- 
strictor muscles,—superior, 
middle and inferior. Running 
more longitudinally and inter- 
nally are th zpalato-pharyngeus 
and stylopharyngeus muscles. 
Outside the muscular layer of 
the pharynx is a fibrous or con- 
nective- tissue layer. The upper 
part of the mucous membrane 
of the pharynx is lined by 
columnar ciliated epithelium, 
while that portion opposite and 
below the fauces is lined by 
stratified squamous epithelium. 
Much adenoid tissue also exists 
in the mucous membrane.] 
[Seven openings communi- 
cate with the pharynx, viz., the 
two posterior nares, the isthmus 
of the fauces, the opening into 
the larynx, the oesophagus, 
and the two Eustachian tubes, 
so that during deglutition all 
these apertures have to be 
guarded in some way or other.] 
[Anatomically the other im- 
portant parts are the soft palate 
with the uvula, the isthmus of 
the fauces opening from the 
mouth into the pharynx, and 
bounded laterally by the an- 
terior and posterior pillars of 
the fauces, the former containing thepalato-glossus muscle, and the latter the palato-pharyngeus 
muscle. On each side between the pdlars lies a tonsil.] 
The onward movements of the contents of the digestive canal are effected 
by a special kind of action whereby the tube or canal contracts upon its con- 
tents, and as this contraction proceeds along the tube, the contents are thereby 
carried along. This is the “ peristaltic movement,” or peristalsis. 
[The act of swallowing a solid mass has been variously described,—firstly, as 
consisting of a voluntary and an involuntary stage. In the voluntary 
stage the food remains in the mouth, but when it reaches the posterior third of 
the tongue, or rather at the isthmus of the fauces, the involuntary stage 
commences, which includes its passage through the pharynx and oesophagus 
into the stomach. Others, again, divide it into three stages— 
(1) While the food traverses the isthmus of the fauces. 
(2) While the food traverses the pharynx. This includes the movements 
of the pharynx, the shutting off of the posterior nares, the occlusion 
Eustachian tube. 
Soft palate. 
Isthmus of the 
fauces. 
Epiglottis. 
Entrance to 
larynx. 
Hyoid bone. ■ 
Cricoid 
cartilage. 
Trachea. 
Vertical or sagittal median section through the mouth and 
pharynx. 
Fig. 198. [Sec. 156. 
274 
STAGES OF DEGLUTITION. 
of the entrance to the glottis, and the shutting of the pillars of the 
fauces. 
(3) While it traverses the oesophagus. In this stage gravity has no effect, 
as the food is carried downwards by peristaltic action of the oesopha- 
gus, so that a person can swallow when standing on his head.] 
In the act of deglutition, we distinguish in order the following individual 
movements:— 
I. Voluntary Stage.—(1) The aperture of the mouth is closed by the 
orbicularis oris (IVfacialis). 
(2) The jaws are pressed against each other by the muscles of mastication 
(TV. trigeminus'), while at the same time the lower jaw affords a fixed point for 
the action of the muscles attached to it and the hyoid bone. 
(3) The tip, middle, and root of the tongue, one after the other, are pressed 
against the hard palate, whereby the contents of the mouth are propelled 
towards the pharynx [the floor of the mouth being raised by the contraction of 
the mylo-hyoid muscles]. 
II. Involuntary Stage.—(4) The food is prevented from passing into the 
mouth. When the bolus has passed the anterior palatine arch (the mucus of 
the tonsillar glands making it slippery again), it is prevented from returning to 
the mouth by the palato-glossi muscles which lie in the anterior pillars of the 
fauces, coming together like two side-screens or curtains, meeting the raised dor- 
sum of the tongue (stylo-glossus). 
(5) The food is prevented from passing into the posterior nares. The morsel 
is now behind the anterior palatine arch and the root of the tongue, and has 
reached the pharynx, where it is subjected to the successive action of the three 
pharyngeal constrictor muscles which propel it onwards. The action of the 
superior constrictor of the pharynx is always combined with a horizontal eleva- 
tion (Levator veli palatini; N. facialis) and tension (Tensor veli palatini; 
N. trigetninus, otic ganglion) of the soft palate. The upper constrictor presses 
(through the pterygo-pharyngeus) the posterior and lateral walls of the pharynx 
tightly against the posterior margin of the horizontal, tense, soft palate, whereby 
the margins of the posterior palatine arches (palato-pharyngeus) are approxi- 
mated. The pharyngo-nasal cavity is thus completely shut off, so that the bolus 
cannot be pressed backwards into the nasal cavity (fig. 199 B). 
In persons with congenital or acquired defects of the soft palate, or cleft-palate, during 
swallowing, food passes into the nose. 
(6) The food is prevented from passing into the larynx. The bolus is pro- 
pelled onwards by the successive contraction of the upper, middle, and lower 
constrictors of the pharynx until it passes into the oesophagus. At the same 
time the entrance to the glottis is closed, else the morsel would pass into the 
larynx, or, as is generally said, would “ pass the wrong way.” 
Sounds during Deglutition.—If the region of the stomach be auscultated during the act of 
swallowing, two sounds may be heard; the first one is produced when the bolus is projected into 
the stomach; the second occurs when the peristalsis, which takes place at the end of swallow- 
ing, squeezes the contents of the oesophagus through the cardia (Meltzer, Zenker, Eivald). [The 
latter occurs a short time afterwards. In man, when water alone is swallowed, there is no sound, 
but when it is mixed with air there is, and it is generally heard because air is usually swallowed 
with the food or drink (Quincke).] 
The closure of the glottis is effected in the following manner:—(a) The 
whole larynx—the lower jaw being fixed—is raised upwards and forwards, 
while at the same time the root of the tongue hangs over it. The hyoid bone 
is raised forwards and upwards by the genio-hyoid, anterior belly of the digas- 
tric, and mylo-hyoid ; the larynx is approximated close to the hyoid bone by 
the thyro-hyoid. (b) When the larynx is raised, so that it comes to lie below Sec. 156.] 
kronecker’s experiments on deglutition. 
275 
the overhanging root of the tongue, the epiglottis is pressed downwards over 
the entrance to the glottis, and the bolus passes over it. The epiglottis is also 
pulled down by the special muscular fibres of the reflector epiglottidis and ary- 
epiglotticus. (V) The closure of the glottis by the constrictors of the larynx 
also prevents the entrance of substances into the larynx (§ 313, II, 2). 
In order that the descending bolus may be prevented from carrying the 
pharynx with it, the stylo-pharyngeus, salpingo-pharyngeus, and baseo-pharyn- 
geus contract upwards when the constrictors act. 
Injury to the Epiglottis.—Intentional injury of the epiglottis in animals, or its destruction 
in man, may cause fluids to “go the wrong way,” i. e., into the glottis, whilst solid food can be 
swallowed without disturbance. In dogs, colored fluids placed on the root of the tongue have 
been observed to pass directly into the pharynx without coming into contact with it, so as 
to tinge the upper surface of the epiglottis (Magendie). [The basis of the epiglottis is yellow 
elastic cartilage, so that it shows no tendency to ossify, and always retains its elasticity ($ 313).] 
[Experiments of Kronecker, Falk, and Meltzer. Method.—Meltzer placed in his oeso- 
phagus an oesophageal sound with a thin india-rubber bag tied to its lower end, and its upper 
Scheme of deglutition.—A shows the passages and openings marked with arrows indicating the 
air- and food-channels. B, the act of deglutition. 
Fig. 199. 
end in connection with a Marey’s tambour. The sound was graduated into centimetres, so that 
by fixing it with the teeth, the depth to which the bag reached in the oesophagus could be ascer- 
tained at once. The elastic bag was inflated from a lateral tube so as to fill the oesophagus. 
The experiment was so arranged as to indicate the moment the act of swallowing commenced, 
a second bag being placed in the pharynx, and of course as the bolus—usually water—passed 
along the pharynx and oesophagus it compressed first the one and then the other bag, and a 
tracing was obtained of the relative time of passage.] 
[In all experiments on deglutition it is important to remember that the size and 
consistence of the bolus cause different mechanisms to come into play. In 
swallowing water, for example, less than second suffices to transport it from 
the mouth along the oesophagus. It is “projected,” “ shot-down ” the oeso- 
phagus by the contractions chiefly of the muscles of the floor of the mouth— 
the mylo-hyoids—the oesophagus remaining open ; and the oesophagus first 
contracts after the bolus is already in the stomach. If a large mass of con- 
siderable consistence is swallowed, this seems to require the help of the con- 
strictors of the pharynx and the oesophageal walls.] [Sec. 156. 
276 
kronecker’s experiments on deglutition. 
[From the tracing (fig. 200) it will be seen that the bolus—e. g., water—is 
projected right into the stomach long before the oesophagus begins to contract. 
What Kronecker in- 
sists on is that in 
swallowing, say wa- 
ter or semi-fluid 
food, the food is not 
carried into the stom- 
ach by a complica- 
ted peristaltic act as 
described above; but 
that the act of deglu- 
tition is one act, due 
chiefly to the con- 
traction of the mylo- 
hyoid muscles, which 
project the food right 
through the relaxed 
oesophagus into the 
stomach with con- 
siderable rapidity 
(ytjj sec.) and under 
a relatively high pres- 
sure. Of course at 
the same time the various side-openings to the posterior nares and entrance to 
the glottis have to be guarded and closed.] 
[The mylo-hyoids form a hammock-like diaphragm, on which rests the tongue. There are also 
concerned the longitudinal and hyoglossi muscles; the latter pull the root of the tongue back- 
wards and downwards.] 
[When, however, the bolus is large and solid, then deglutition takes place much more 
slowly, and the bolus seems to meet with more resistance at certain parts in its passage, 
and to require the peristaltic action of the pharyngeal and oesophageal muscles to press it 
onwards.] 
[Kronecker divides the digestive tube as far as the cardia into five muscular rings—1. Those 
for the first act, chiefly the mylo-hyoids. 2. The constrictors of the pharynx. 3. The first 
section of the oesophagus (cervical segment provided with striped muscle). 4. The upper 
dorsal segment of the oesophagus (partly striped and partly smooth muscle). 5. To the 
cardiac (smooth muscle). In this connection we may recall the observation of Virchow in cases 
of poisoning by sulphuric acid, where he noticed that little effect was produced on the mouth 
or pharynx, the most marked effects of the action of the acid being at the entrance to the 
oesophagus where it crosses the left bronchus, and just before the cardia where it perforates the 
diaphragm.] 
[Time Relations.—As to the time relations of the contraction of the successive muscular rings 
we have the following :— 
Tracing of the act of deglutition. I, A indicates the compression of 
the elastic bag caused by the bolus projected by the contraction of 
the mylo-hyoid muscles; B, contraction of the pharynx; 2, Line 
marking seconds; 3, Tracing of the bag in the oesophagus 12 
centimetres from the teeth ; C, compression of the bag by the bolus 
corresponding to A; D, compression by the residues of the bolus 
carried on by the contraction of the pharynx, B; E, contraction of 
the oesophagus. 
Fig. 200. 
Contraction of mylo-hyoids and constrictor 
°-3 X 1 
Secs. 
= o-3 
“ first part of oesophagus 
0-3 X (i + 2) 
- °-9 
“ second “ 
o-3 X (i + 2 + 3) 
= 1.8 
“ third “ 
o.3Xli + 2+3+4) 
= 3-o 
6.0 
i. e., if each part had to contract successively it would require at least 6 seconds before a bolus 
of food could be carried to the stomach, yet it is within the experience of all of us that the act 
occurs much more quickly. It will be seen that the above gives an arithmetical series of the 
second order with difference 1 and a constant factor 0.3.] 
[It is necessary to distinguish a single, isolated act of deglutition from 
a series, or succession of these acts. If we make a series of acts of swal- 
lowing, as when we drink a glass of water, the oesophagus does not contract 
until after the last act of deglutition, and it contracts at the same interval of Sec. 156.] 
NERVOUS MECHANISM OF DEGLUTITION. 
277 
time after the beginning of the last act of deglutition as if only a single act 
had been carried out. It is obvious, therefore, that every act of swallowing 
not only excites an oesophageal contraction, but at the same time it inhibits the 
already excited but not yet manifested oesophageal contraction. Thus in swal- 
lowing a glass of water each successive act of deglutition inhibits the oesopha- 
geal contraction, so that the oesophagus remains open, and only contracts after 
the last drop of water is already in the stomach.] 
Nervous Mechanism.—Deglutition is voluntary only during the time 
the bolus is in the mouth. When the food passes through the palatine arch 
into the gullet the act becomes involun- 
tary, and is, in fact, a well-regulated re- 
flex action. When there is no bolus to be 
swallowed, voluntary movements of de- 
glutition can be accomplished only within 
the mouth ; the pharynx only takes up the 
movement, provided a bolus (food or 
saliva) mechanically excites the reflex act. 
The afferent nerves, which, when me- 
chanically stimulated, excite the involun- 
tary act of deglutition, are the palatine 
branches of the trigeminus (from the 
spheno-palatine ganglion and the pharyn- 
geal branches of the vagus (fig. 201). [It 
can also be excited by stimulation of the 
central end of the superior laryngeal 
nerve.] The centre for the nerves con- 
cerned (for the striped muscles) lies in the 
superior olives of the medulla oblongata. 
Swallowing can be carried out when a per- 
son is unconscious, or after destruction 
of the cerebrum, cerebellum, and pons 
(§ 367, 6). [Even in the deep coma of 
alcoholism, the tube of a stomach-pump is 
carried into the stomach reflexly, provided 
the surgeon passes it back into the pharynx]. 
The nerves of the pharynx are derived 
from the pharyngeal plexus, which re- 
ceives branches from the vagus, glosso-pharyngeal, and sympathetic (§ 352, 4). 
Stimulation of the glosso-pharyngeal nerve inhibits reflex deglutition (Kro- 
necker and Wassilieff). 
[The efferent or motor nerves are those supplying the muscles concerned, (1) the inferior 
maxillary division of the fifth cranial nerve supplies the masse ter, temporal, pterygoid, mylo- 
hyoid, and anterior belly of the digastric muscles; (2) the facial supplies the orbicularis oris, 
buccinator, stylo-hyoid, and posterior belly of the digastric ; (3) the hypoglossal or ninth cranial 
nerve supplies the intrinsic muscles of the tongue, genio-hyoid, thyro-hyoid, genio-hyoglossus, 
hyoglossus, and stylo-glossus; (4) branches of the pharyngeal plexus (vagus, glosso-pharyngeal, 
and sympathetic) supply the constrictors of the pharynx, palato-glossus, and palato-pharyngeus; 
(5) a branch from the glosso pharyngeal (?) supplies the stylo-pharyngeus; (6) the facial 
(petrosal) branch of the Vidian supplies the levator palati and azygos uvulae; (7) a branch from 
the otic ganglion of the fifth supplies the tensor palati; (8) the inferior laryngeal branch of the 
vagus supplies the muscles that close the glottis. ] 
[We have seen that the contraction of the oesophagus is inhibited during a 
succession of acts of deglutition. We know that the vagus conducts impulses 
which excite the oesophagus, and is therefore motor. Through the trigeminus 
reflex acts of deglutition can be excited. As to the glosso-pharyngeal, we know 
Scheme ot the afferent and efferent nerves 
concerned in deglutition (Stirling). 
Fig. 201. 278 
NERVOUS MECHANISM OF DEGLUTITION. 
[Sec. 156. 
that its section does not set aside deglutition, nor does its stimulation excite the 
act of swallowing. The glosso-pharyngeal inhibits the occurrence of a reflex act 
of deglutition. If the glosso-pharyngeal be stimulated, the strongest stimuli to 
deglutition (<?. g., filling the pharynx with fluid, or stimulation of the superior 
laryngeal nerves) fail to discharge the act of deglutition ; neither the first part 
of the act nor contraction of the oesophagus takes place. Stimulation of the 
lingual branch of the glosso-pharyngeal inhibits the first act of deglutition ; 
whde the pharyngeal branches seem to inhibit the oesophageal contractions, so 
that the glosso-pharyngeal is the inhibitory nerve of deglutition.] 
[With each stimulus to the movement of the first act of deglutition (especially 
the mylo-hyoid group) there is an inhibition of the deeper sections through the 
stimulation of the glosso-pharyngeal nerve. This inhibition takes place in the 
nerve-centre in the medulla oblongata, for Mosso showed that the peristaltic 
movements of the oesophagus are propagated from above downwards, even after 
section of the oesophagus.] 
[Action on other Centres.—The act of swallowing affects many other 
centres, e. g., the cardio-motor in the medulla, it reduces the tonus of the heart 
vagus, so that the heart beats quicker (§ 369), it also affects the respiratory 
centre and diminishes the need for respiration, constituting “ Deglutition- 
apnoea.” It also affects the vaso-motor and some other centres (Kronecker).~\ 
[Where the Deglutition Reflex is discharged.—It is very difficult to determine from what 
parts of the mouth deglutition is excited. In the rabbit, by touching the anterior central part 
of the soft palate, a complete act of deglutition is discharged. This may be set aside by 
section of the trigeminus, or painting the part with cocaine. Parts of the larynx supplied by 
the superior laryngeal also excite it. In man the reflex is discharged when the bolus passes 
behind the velum in the region of the tonsils. Stimulation of the glosso-pharyngeal inhibits 
deglutition, but how it is caused is unknown. Stimulation of the pharynx, even muscular pressure, 
will inhibit it (Wassilief).) 
Within the oesophagus, whose stratified squamous epithelium is moistened 
with the mucus derived from the mucous glands in its walls, the downward 
movement is involuntary, and depends upon a complicated reflex movement 
discharged from the centre for deglutition. There is a peristaltic movement of 
the outer longitudinal and inner circular non-striped muscular fibres. 
In the upper part of the oesophagus, which contains striped muscular fibres, the peristalsis 
takes place more quickly than the lower part. The movements of the oesophagus never 
occur independently, but are always the continuation of a foregoing act of deglutition. If food 
be introduced into the oesophagus through a hole in its wall, there it lies; and it is only carried 
downwards when a movement to swallow is made. The peristalsis extends along the whole 
length of the oesophagus, even when it is ligatured or when a part of it is removed (Mosso). If 
a dog be allowed to swallow a piece of flesh tied to a string, so that the flesh goes half-way 
down the oesophagus, and if the flesh be withdrawn, the peristalsis still passes downwards 
(C. Ludwig and Wild.) 
The motor nerve of the cesophagus is the vagus (not the accessory fibres) [oesophageal, 
whose branches have numerous small ganglia in their course]. After it is divided, the food 
lodges in the lower part of the cesophagus. Very large and very small masses are swallowed 
with more difficulty than those of moderate size. Dogs can swallow an olive-shaped body 
weighted with a counterpoise of 450 grams (Mosso). When the thorax is greatly distended, as in 
Muller’s experiment, or greatly diminished, as in Valsalva’s experiment (g 60), deglutition is 
rendered more difficult. 
Goltz’s Experiments.—The oesophagus and stomach of the frog become more excitable, 
i. e., the excitability of the ganglionic plexuses in their walls is increased, when the brain and 
spinal cord or both vagi are destroyed. These organs contract energetically after slight 
stimulation, while frogs, whose central nervous system is intact, swallow fluids simply by 
peristalsis. Females, and sometimes men also, suffering from hysteria, not unfrequently have 
similar spasmodic contractions of the oesophageal region (globus hystericus). After section of 
both vagi in the dog, Schiff observed spasmodic contraction of the oesophagus. [After section 
of the glosso-pharyngeal nerve the oesophagus may pass into a state of tonic spasm lasting about 
a day]. 
Effect on Circulation.—Every time one swallows, the heart’s action is accelerated, the Sec. 156.] 
STRUCTURE OF THE (ESOPHAGUS. 
279 
blood-pressure falls, the necessity for respiration diminishes, while many movements (labor 
pains, erection) tend to be inhibited. These effects are brought about reflexly (Kronecker and 
Meltzer, $ 369). 
[Structure of the (Esophagus.—The oesophagus in the dog and rabbit 
is almost entirely composed of striped muscle. In the cat and man, its upper 
part acts like a striped muscle, and its lower part is composed of smooth muscle. 
The oesophagus is almost 25 cm. long, and its walls are composed of four 
coats—mucous, sub-mucous, muscular, and fibrous (fig. 202). 
(1) The mucous coat is firm, and is thrown into longitudinal folds, which 
disappear when the tube is distended-. It is lined by several layers of stratified 
squamous epithelium. The membrane itself is composed, especially at its 
inner part, of dense fibrous tissue, which projects, in the form of papillae, into 
the stratified epithelium. The papillae are present in the child, but are largest 
in old people. At its outer part is a continuous longitudinal layer of non-striped 
muscle, the muscularis mucosae. The layer consists of small bundles of 
non-striped muscle separate from each other. 
Excretory duct. 
Stratified 
epithelium.- 
Injected 
,capillaries. 
Connective- 
tissue with 
papillae.' 
Mucous mem- 
■brane with 
muscularis 
mucosae. 
Mucous 
gland. 
Muscular Coat. 
-Sub-mucosa. 
Circular mus- 
cular fibres 
Longitudinal 
musculaH 
fibres 
Fig. 202. 
(2) The sub-mucous coat is thicker than the foregoing, and consists of 
loose connective-tissue, with the acini of small mucous glands imbedded in it. 
The ducts pierce the muscularis mucosae to open on the inner surface of the 
tube. Some animals have a considerable number of large mucous glands in the 
oesophagus (dog) and others have very few. 
(3) The muscular coat consists of an inner, thicker, circular, and an 
outer, thinner, longitudinal layer of non-striped muscle, commencing on a 
level with the cricoid cartilage. In man, the upper third of the gullet consists 
of striped muscular fibres. 
(4) Outside the muscular coat is a layer of fibrous tissue,—the adventitia 
—with elastic fibres. The structure of the muscular coat of the oesophagus 
varies much in different animals. In the rabbit, in the first quarter of its 
length, it has two layers, but below this there are three layers, i. e., a circular 
between an outer and an inner longitudinal layer, while the non-striped fibres 
are confined to the lowest quarter of the tube.] 
[Nerve-Plexuses.—As in the intestine, there are two plexuses of nerves 
with ganglia ; one in the sub-mucous coat {Meissner’s) and the other between 
Transverse section of part of the oesophagus. 280 
MOVEMENTS OF THE STOMACH. 
[Sec. 156. 
the two muscular coats [Auerbach's'), which are continuous with those in the 
stomach and intestine. Blood-vessels and numerous lymphatics lie in the 
mucous and sub-mucous coats.] 
157. MOVEMENTS OF THE STOMACH.—Position.—When the 
stomach is empty, the great curvature is directed downwards and the lesser 
upwards; but when the organ is full, it rotates on an axis running horizontally 
through the pylorus and cardia, so that the great curvature appears to be 
directed to the front and the lesser backwards. 
Arrangement of the Muscular Fibres.—The non-striped muscular fibres of the stomach 
are arranged in three directions or layers. There is an outer longitudinal layer, whose fibres 
are continuous with those of the oesophagus and is best developed along the curvatures, especi- 
ally the lesser. At the pylorus the fibres form a thick layer, and become continuous with the 
longitudinal fibres of the duodenum. The circular fibres form a complete layer; at the pylorus 
they are more numerous, and constitute the sphincter-muscle or pyloric valve ; whilst at the 
cardia (inlet), such a muscular ring is absent. The innermost oblique or diagonal layer is 
incomplete. 
The Movements of the Stomach are of two kinds: The rotatory or 
churningmovements, whereby the parts of the wall of thestomach in contact with 
the contents glide to and fro with a slow rubbing movement. Such movements 
seem to occur periodically, every period lasting several minutes (.Beaumont). 
By these movements the contents are moistened with the gastric juice, while the 
masses of food are broken down. The formation of hair-balls in the stomach 
of dogs and oxen indicates that such rotatory movements of the contents of the 
stomach take place. (2) The other kind of movement consists in a periodically 
occurring peristalsis, whereby, as with a push, the first dissolved portions of 
the contents of the stomach are forced into the duodenum. They begin after 
a quarter of an hour, and recur until about five hours after a meal. This peri- 
stalsis is most pronounced towards the pyloric end, and the muscles of the 
pyloric sphincter relax to allow the contents to pass into the duodenum. 
According to Riidinger, the longitudinal muscular fibres, when they contract, 
especially when the pyloric end is filled, may act so as to dilate the pylorus. 
The following experiment is designed to determine the time at which the ingesta pass into the 
intestine. Salol splits up in an alkaline medium (in intestine) into phenol and salicylic acid, 
and the presence of the latter in the urine can be ascertained by ferric chloride (violet color). 
In health the reaction begins in A~i hour, and disappears after 24 hours; in motor insufficiency 
of the stomach 3-24 hours later [Huber). 
Gizzard.—The strongly muscular walls of the stomach of grain-eating birds effect a tritura- 
tion of the food. The older physiologists found that glass balls and lead tubes, which could 
be compressed only by a weight of 40 kilos., were broken or compressed in the stomach of 
a turkey. 
[The Nerves of the Stomach.—It is supplied by nerve-fibres from the 
two vagi and the solar plexus. After forming the oesophageal plexus, the left 
vagus descends rather anterior to, and the right posterior to, the oesophagus, 
and they continue along it to the stomach. The left supplies chiefly the lesser 
curvature and the anterior surface of the organ, together with branches to the 
liver, and, perhaps the duodenum, while the right gives branches to the 
posterior surface of the stomach, about two-thirds of its fibres passing to the 
solar plexus. The gastric branches of the vagus contain for the most part non- 
medullated fibres.] 
[From the solar or cceliac plexus branches—chiefly composed of non- 
medullated fibres—proceed, constituting the gastric plexus of the splanchnic 
nerves along the gastric artery to the stomach, where they intermingle with the 
branches from the vagi under the peritoneal covering. Small ganglia exist in 
the course of these nerves. Branches penetrate the coats of the stomach along 
with the arteries, and, between the longitudinal and circular muscular coats, 
form Auerbach’s plexus, and Meissner’s plexus in the sub-mucous coat.] Sec. 157. 
VOMITING. 
281 
[Branches from Meissner’s plexus pass to the mucous membrane, some to 
supply the muscularis mucosae, and it may be to the glands, as well, but this latter 
point has not been proved histologically.] 
Influence of Nerves on the Stomach.—Auerbach’s ganglionic 
plexus of nerve-fibres and nerve-cells, which lies between the muscular coats 
of the stomach, must be regarded as its proper motor centre, and to it motor 
impulses are conducted by the vagi. Section of both vagi does not abolish, 
but it diminishes the movements of the stomach. The muscular fibres of the 
cardia may be excited to action, or their action inhibited by fibres which run 
in the vagus (Nn. constrictores, et dilatator cardise). [If the vagi be divided 
in the neck, there is a short temporary spasmodic contraction of the cardiac 
aperture. On stimulating the peripheral end of the vagus with electricity, after 
a latent period of a few seconds, the cardiac end contracts, more especially if 
the stomach be distended, but the movements are slight if the stomach be 
empty. In curarized dogs, the pylorus contracts with varying intensity, and 
irregularly, whether the vagi and splanchnics be intact or divided. Stimula- 
tion of the vagi in the neck causes contraction of the pylorus, when the latent, 
period may be seven seconds. Stimulation of the splanchnics in the thorax 
arrests the spontaneous pyloric contractions, the left splanchnic being more 
active than the right ( Oser).] 
In the cardia are automatic ganglionic cells (analogous to the cardiac ganglia), which are 
connected with the vagus and sympathetic. [They lie in groups (n in the rabbit) and are not 
to be confounded with Auerbach’s plexus.] A centre for the contraction of the cardia lies in 
the posterior pair of the corpora quadrigemina ; the efferent channels for the impulses seem to 
be through the vagi and partly through the splanchnics. The centre for the opening of the 
cardia, [*. e., the origin of the dilator cardise] lies in the anterior inferior end of the corpus- 
striatum, and the conducting paths in the vagi. The cardia may be opened reflexly by stimula- 
tion of the sensory abdominal nerves [e.g., of the kidney, uterus, intestine]. 
The body of the stomach also possesses a few automatic ganglia in connection with the 
vagi and sympathetic. A centre for its contraction lies in the corpora quadrigemina, and the 
efferent paths lie in the vagi but chiefly in the cord, and from the latter into the sympathetic- 
inhibitory centres lie in the upper part of the cord, and the efferent paths are in the sympathetic 
and splanchnics. 
The pylorus also contains automatic centres. The centre for opening the cardia inhibits- 
the movement of the pylorus, the path being through the cord and splanchnics. Inhibitory 
pyloric centres lie in the corpora quadrigemina and olives, the paths are in the cord. The centres 
in the cortex [sulcus cruciatus] for opening the cardia at the same time contract the pylorus.. 
The contraction-centres for the pylorus lie in the corpora quadrigemina (Openchowski). [These 
results refer to the dog and rabbit.] 
Local electrical stimulation of the surface of the stomach causes circular constrictions of 
the organ, which disappear very gradually, while the movement is often propagated to other 
parts of the gastric wall. When heated to 250 C., the excised empty stomach exhibits move- 
ments. Injury to the pedunculi cerebri, optic thalamus, medulla oblongata, and even to the 
cervical part of the spinal cord, according to Schiff, causes paralysis of the vessels of certain areas 
of the stomach, resulting in congestion and subsequent hemorrhage into the mucous membrane. 
[It is no uncommon occurrence to find hemorrhage into the gastric mucous membrane of rabbits,, 
after they have been killed by a violent blow on the head.] 
[Action of Drugs.—The automatic centres are excited by emetin, apomorphin, tartar 
emetic, while muscarin causes general contraction of the stomach. The activity of the auto- 
matic centres is diminished by chloral, urethan, morphin, and nicotin, while atropin causes 
paralysis of the nerve-endings (E. Schiltz).] 
158. VOMITING.—Mechanism.—Vomiting is caused by contraction 
of the walls of the stomach, the pyloric sphincter being closed. It occurs most 
readily when the stomach is distended—(dogs usually greatly distend the 
stomach by swallowing air before they vomit); it readily occurs in infants, in 
whom the cul-de-sac at the cardia is not developed. It is quite certain that 
in children vomiting occurs through contraction of the walls of the stomach, 
without the spasmodic action of the abdominal walls. When vomiting is- 
violent, the abdominal muscles act energetically. [The act of vomiting is- 282 
VOMITING. 
[Sec. 158. 
generally preceded by a feeling of nausea, and usually there is a rush of saliva 
into the mouth, caused by a reflex stimulation of afferent fibres in the gastric 
branches of the vagus, the efferent nerve for the secretion of saliva being the 
chorda tympani. After this a deep inspiration is taken, and the glottis closed, 
so that the diaphragm is firmly pressed downwards against the abdominal con- 
tents, and it is kept contracted; the lower ribs are pulled in. The diaphragm 
being kept contracted and the glottis closed, a violent expiratory effort is made, 
so that the contraction of the abdominal muscles acts upon the abdominal con- 
tents, the stomach being forcibly compressed. The cardiac orifice is opened 
at the same time, and the contents of the stomach are ejected. The chief 
agent seems to be the abdominal compression, but the walls of the stomach 
also help, though only to a slight extent.] 
The contraction of the walls of the stomach, which causes a general diminution of the gastric 
cavity, is not a true anti-peristalsis, as can be seen in the stomach when it is exposed. The 
cardia is opened by the longitudinal muscular fibres, which pull towards the lower orifice of the 
oesophagus, so that when the stomach is full they must act as dilators. The act of vomiting is 
preceded by a ructus-like dilating movement of the intra-thoracic part of the oesophagus, which 
is caused thus: The glottis is closed, inspiration occurs suddenly and violently, whereby the 
oesophagus is distended by gases proceeding from the stomach. The larynx and hyoid bone, 
by the combined action of the genio-hyoid, sterno-hyoid, sterno-thyroid, and thyro-hyoid muscles, 
are forcibly pulled forwards, so that the air passes from the pharynx downwards into the upper 
section of the oesophagus. If the abdominal walls contract suddenly, and if this sudden impulse 
be aided by the movements of the stomach itself, the contents of the stomach are forced outwards. 
During continued vomiting, antiperistalsis of the duodenum may occur, whereby bile passes into 
the stomach, and becomes mixed with its contents. 
Children, in whom the fundus is absent, vomit more easily than adults. [In them also the 
nervous system is more excitable.] 
Influence of Nerves.—The centre for the movements concerned in vom- 
iting lies in the medulla oblongata, and is in relation with the respiratory centre, 
as is shown by the fact that nausea may be overcome by rapid and deep respira- 
tions. In animals, vomiting may be inhibited by vigorous artificial respiration. 
On the other hand, the administration of certain emetics prevents the occur- 
rence of apnoea. 
In vomiting, the afferent impulses may be discharged from (i) the mucous 
membrane of the soft palate, pharynx, root of the tongue (glosso-pharyngeal 
nerve), as in tickling the fauces with the finger ; (2) the nerves of the stomach 
(vagus and sympathetic) ; (3) stimulation of the uterine nerves (pregnancy) ; 
(4) the mesenteric nerves (inflammation of the abdomen and hernia); (5) 
nerves of the urinary apparatus (passing a renal calculus) ; (6) nerves to the liver 
and gall-duct {vagus) ; (7) nerves to the lungs in phthisis (vagus). Vomiting 
is also produced by direct stimulation of the vomiting centre. [The efferent 
impulses are carried by the phrenics (diaphragm), vagus (oesophagus and 
stomach), and intercostals (abdominal muscles).] 
Vomiting, produced by the thought of something disagreeable, appears to be caused by the con- 
duction of the excitement from the cerebrum to the vomiting centre. [It may also be excited 
through the brain by a disagreeable smell, shocking sight, or by other impressions on the nerves 
of special sense.] Vomiting is very common in diseases of the brain [tubercle, inflammation, 
hemorrhage]. Section of both vagi generally, but not always, prevents vomiting. 
Emetics act (1) partly by mechanically or chemically stimulating the ends of the centripetal 
(afferent) nerves of the mucous membrane. [These are local emetics.] Tickling the fauces, 
touching the surface of the exposed stomach (dog); and many chemical emetics, e.g., mustard, 
cupric and zinc sulphate, and other metallic salts, act in this way. (2) Other substances cause 
vomiting when they are introduced into the blood (without being first introduced into the stomach), 
and act directly upon the vomiting centre, e.g., apomorphin. [These are general emetics.] (3) 
Lastly, there are some substances which act in both ways, e.g., tartar emetic. Emetics may 
also remove mucus from the lungs, and in this case it is probable that the emetic acts upon the 
respiratory centre, and so favors the respirations. The general emetics usually create consider- 
able depression, while the vomiting lasts longer than with local emetic®. The former increase 
the salivary, gastric, and respiratory secretions. Sec. 158.] 
MOVEMENTS OF THE INTESTINE. 
283 
[Uses of Emetics.—Emetics are useful not only for removing from the stomach any offend- 
ing body, be it a poison or the products of imperfect or perverted gastric digestion, or bile which 
has passed back into the stomach, but foreign bodies impacted in the oesophagus may be got rid 
of on exciting vomiting by the subcutaneous injection of apomorphin. As the diaphragm con- 
tracts vigorously during vomiting, it compresses the liver, and thus bile is expelled into the 
duodenum, or the passage of a small calculus along the bile-duct may be aided. They also are 
useful in removing mucus or false membranes from the respiratory passages.] 
[Anti-Emetics.—Vomiting may be allayed by local anti-emetics such as ice, and many 
chemical substances such as bismuth, hydrocyanic acid, opium, and morphia, as well as by general 
remedies which act on the vomiting centre. Some of the foregoing drugs perhaps act both 
locally and generally.] 
Vomiting is analogous to the process of rumination in animals that chew the cud (§ 187). 
Some persons can empty their stomachs in this way. 
159. Movements of the Intestine.—[The intestines consist of the 
small and large intestine; the small intestine commences at the pylorus and 
ends at the junction of the ileum with the large intestine (i. e., at the caecum), 
and its length is about metres (about 20 feet) (fig. 172).] 
[The first part of the small intestine is the duodenum, about 22 cm. long and 5 cm. in 
diameter; of the remainder the upper third is called the jejunum (2.2 metres long) and the 
lower two-thirds the ileum (about 4 metres long), but there is no line of demarcation between 
these parts, the one shading into the other. The large intestine is about 1.4-1.8 metres 
long (about 5 feet), wider than the small and extends from the termination of the ileum to the 
anus. It is divided anatomically into the ccecum with the vermiform appendix, the colon, and 
the rectum. 
[Comparative Length and Capacity of the Intestines.—There is a marked difference 
between the intestinal canal of herbivora and carnivora. Vegetable food requires a much larger 
number of mechanical and chemical aids for its digestion than animal food. The intestinal canal 
is shortest in carnivora (cat, lion, dog), longer in omnivora (man, apes), and longest, sometimes 
very long, and with enormous dilatations, in the pure herbivora. In the tiger and lion the whole 
digestive tract is 3 times as long as the body {i. e., from the nose to the anus); in the dog, 5; 
chimpanzee, 6; man, 9 times. In herbivora it is 11-26 times as long as the body; horse, 12 
times; pig, 16 ; ox, 20; and goat, 26 times. The intestinal canal of the horse is comparatively 
short, but its capacity is very great. The capacity of the intestinal tract (excluding the stomach) 
is in the ox, 80 litres; horse, 200; pig, 27 ; and dog 8. The capacity of the stomach in the ox 
is 200, and in the horse only 10-18 litres. The superficial area of the intestinal mucous mem- 
brane is in the ox, 15; horse, 15-51; pig, 3, and dog, 0-5 square metres (Munk)l\ 
Peristalsis.—The best example of peristaltic movements is afforded by the 
small intestine; the progressive narrowing of the tube proceeds from above 
downwards, thus propelling the contents before it. Frequently after death, or 
when air acts freely upon the gut, the peristalsis develops at various parts of the 
intestine simultaneously, whereby the loops of intestine present the appearance 
of a heap of worms creeping amongst each other. The advance of new intes- 
tinal contents again increases the movement. In the large intestine the move- 
ments are more sluggish and less extensive. The peristaltic movements may be 
seen and felt when the abdominal walls are very thin, and also in hernial sacs. 
They are more lively in vegetable feeders than in carnivora. The peristalsis is 
perhaps conducted directly through the muscular substance itself, as in the 
heart and ureter. The movements of the stomach and intestine cease during 
sleep (Busch). 
[Rate of Motion.—In a Thiry-Velly fistula (£ 183, II) Fubini estimated the rate of motion 
of a smooth sphere of sealing-wax along the intestine. It took 55 sec. to travel 1 cm. [£ in.]; 
an induction-current greatly increases the motion, to 1 cm. in 10 seconds; NaCl does not affect 
it, but excites secretion; laudanum paralyzes it.] 
Method of Observation.—Open the abdomen of an animal under a .6 per cent, saline so- 
lution to prevent the exposure of the gut to air (Saunders and Braam-Houckgeest). 
The ileo-colic valve, as a rule, prevents the contents of the large intestine 
from passing backwards into the small intestine. 
When fluid is slowly introduced into the rectum through a tube, it passes upwards into the 284 
EXCRETION OF FyECAL MATTER. 
[Sec. 159. 
intestine, and even goes through the ileo-colic valve into the small intestine. Muscarin excites 
very lively peristalsis of the intestines, which may be set aside by atropin (Schmiedeberg and 
Koppe). 
Pathological.—When any condition excites an acute inflammation of the intestinal mucous 
membrane, catarrh is rapidly produced, and very strong c mlractions of the inflamed parts filled 
with food take place. When these parts of the gut become empty, the movements are not 
stronger than normal. If new material passes into the inflamed part, the peristalsis recurs, be- 
comes more lively than normal, and the result is diarrhoea (Nothnagel). Sometimes a greatly 
contracted part of the small intestine is pushed into the piece of gut directly continuous with it, 
giving rise to invagination, or intussusception. 
Anti-peristalsis, i. e., a movement which travels in an upward direction 
towards the stomach, does not occur normally. This has been inferred from 
the fact, that in cases where the intestine is occluded, called ileus, faecal matter 
is vomited. Nothnagel’s experiments throw doubts upon this view, as he failed 
to observe anti-peristalsis in cases Avhere the intestine was occluded artificially. 
The faecal odor of the ejecta may result from the prolonged retention of the 
material within the small intestine. 
160. EXCRETION OF MATTER.—The contents of the 
small intestine remain in it about three hours, and about twelve hours in the 
large intestine, where they become less watery, and they assume the characters 
of faeces, become “formed” in the lower part of the great intestine. The 
faeces are gradually carried along by the peristaltic movement, until they reach 
a point a little above that part of the rectum which is surrounded by both 
sphincters, the internal sphincter consisting of non-striped, and the external of 
striped muscle. 
Immediately after the expulsion of the faeces the external sphincter (fig. 203, 
S, and fig. 204) usually contracts vigorously, and remains so for some time. 
Afterwards it relaxes, when the elasticity of the parts surrounding the anal 
opening, particularly of the two sphincters, suffices to keep the anus closed. 
In the interval between two evacuations there does not seem to be a continued 
tonic contraction of the sphincters. As long as the faeces lie above the rectum, 
they do not excite any conscious sensations, but the sensation of requiring to 
go to stool occurs when the faeces pass into the rectum. At the same time, the 
stimulation of the sensory nerves of the rectum causes a reflex excitement of 
the sphincters. The centre for these movements (Budge’s centrum anospinale) 
lies in the lumbar region of the spinal cord (§ 362); in the rabbit between the 
sixth and seventh, and in the dog at the fifth lumbar vertebra (Masius). 
In animals whose spinal cord is divided above the centre, a slight touch in the region of the 
anus causes this orifice to contract, but after this lively reflex contraction the sphincters relax 
again, and the anus may remain open for a time. This occurs because the voluntary impulses 
which proceed from the brain to cause the contraction of the external sphincter are absent. 
Landois observed that in dogs with the posterior roots of their lower lumbar and sacral nerves 
divided, the anus remained open, and not unfrequently a mass of fieces remained half ejected. 
As the sensibility of the rectum and anus was abolished in these animals, the sphincters could 
not contract reflexly, nor could there be any voluntary contraction of the sphincters, the result of 
sensory impulses from the rectum. 
The external sphincter can be contracted voluntarily, like any voluntary 
muscle, but the closure of the anus can only be effected up to a certain degree. 
When the pressure from above is very great, the energetic peristalsis at last 
overcomes the strongest voluntary impulses. Stimulation of the peduncles of 
the cerebrum and of the spinal cord below this point causes contraction of the 
external sphincter. 
Defaecation.—The evacuation of the faeces, which in man usually occurs at 
certain times, begins with a lively peristalsis of the large intestine, which passes 
downwards to the rectum. In order that the mass of faeces may not excite re- 
flexly the sphincter-muscles, in consequence of mechanical stimulation of the Sec. 160.] 
DEFECATION. 
285 
sensory nerves of the rectum, there seems to be a centre which inhibits the 
reflex action of the sphincters, which is called into play, owing, as it appears, 
to voluntary impulses. Its seat is in the brain, perhaps in the optic thalami. 
When this inhibitory apparatus is in action, the fecal mass passes through the 
anus, without causing it to close reflexly. The strong peristalsis which pre- 
cedes defecation can be aided, and to a certain degree excited by rapid volun- 
tary movements of the external sphincter and levator ani, whereby the plexus 
myentericus of the large intestine is stimulated mechanically, thus causing 
lively peristaltic movements in the large intestine. The expulsion of the feces 
is also aided by the pressure of the abdominal muscles, and most efficiently 
The perinseum and its muscles, i, anus; 2, coccyx; 3, tuberosity; 4, sciatic ligament; 5, 
cotyloid cavity; B, bulbo-cavernosus muscle; Ts, superficial transverse perineal muscle; 
F, fascia of the deep transverse perineal muscle; J, ischio-cavernosus muscle; M, obturator 
internus; S, external anal sphincter; L, levator ani; P, pyriformis. 
Fig. 203. 
when a deep respiration is taken, so as to fix the diaphragm, whereby the ab- 
dominal cavity is diminished to the greatest extent. The soft parts of the floor 
of the pelvis, during a strong effort at stool, are driven downwards in the form 
of a cone, causing the mucous membrane of the anus, which contains much 
venous blood, to be everted. The function of the levator ani (figs. 203, 204) 
is to raise voluntarily the soft parts of the floor of the pelvis, and to pull the 
anus to a certain extent upwards over the descending fecal mass. At the same 
time, it prevents the distention of the pelvic fascia. As the fibres of both leva- 
tores converge below, and become united with the fibres of the external 
sphincter, they aid the latter during energetic contraction of the sphincter ; or, 286 
DEFALCATION. 
[Sec. 160. 
as Hyrtl put it, the levatores are related to the anus, like the two cords of a 
tobacco pouch. During the periods between the evacuation of the gut, the 
faeces appear only to reach the lower end of the sigmoid flexure. As a rule, 
Levator ani and sphincter ani externus. 
Fig. 204. 
from thence downwards, the rectum is normally devoid of faeces. It seems 
that the strong circular fibres of the muscular coat, which Nelaton has called 
sphincter ani tertius, when they are well developed, contract, and prevent the 
entrance of the faeces. When the tendency to the evacuation of the rectum 
Fig. 205. 
Auerbach’s plexus shown in section (human), a, ganglionic cells; b, nerve-fibres ; 
c, section of the circular muscular fibres; d, longitudinal muscular fibres. 
is very pressing, the anus may be closed more firmly from without, by ener- 
getically rotating the thigh outwards, and contracting the muscles of the gluteal 
region. Sec. 161.] 
MO YEMENIS OF THE INTESTINE. 
287 
161. CONDITIONS INFLUENCING THE INTESTINAL 
MOVEMENTS.—The intestinal canal contains automatic motor cen- 
tres within its walls,—the plexus myentericus of Auerbach—which lies 
between the longitudinal and circular muscular fibres of the gut. It is this 
plexus which enables the intestine, when cut out of the body, to execute, 
apparently spontaneously, movements for some time. 
[Structure.—Auerbach’s Plexus consists of non-medullated nerve-fibres which form a 
fairly dense network, groups of ganglion cells occurring at the nodes (fig. 206), and when seen 
in vertical sections between the muscular coats it is like fig. 205. A similar plexus extends 
throughout the whole intestine between the longitudinal and circular muscular coats from the 
oesophagus to the rectum. Branches are given off to the muscular bundles. A similar, but 
not so rich a plexus, lies in the sub-mucous coat—Meissner’s plexus—which gives branches to 
supply the muscularis mucosse, the smooth muscular fibres of the villi, and the glands of the 
intestine (fig. 207).] 
Fig. 206. 
Plexus of Auerbach, prepared from the small intestine of a dog, by the action of gold chloride. 
The nerve cells are shown at the nodes, while the fibrils proceeding from the ganglia, and 
the anastomosing fibres, lie between the muscular bundles. 
1. If this centre is not affected by any stimulus, the movements of the in- 
testine cease—comparable to the condition of the medulla oblongata in apnoea. 
The same is true—just as in the case of the respiration—during intra-uterine 
life, in consequence of the foetal blood being well supplied with O. This con- 
dition may be termed aperistalsis. It also occurs during sleep, perhaps on 
account of the greater amount of O in the blood during that state. 
2. When blood containing the normal amount of blood-gases passes through 
the intestinal blood-vessels, the quiet peristaltic movements of health occur 
(euperistalsis) provided no other stimulus be applied to the intestine. 
3. All stimuli applied to the plexus myentericus increase the peristalsis, which 
may become so very violent as to cause evacuation of the contents of the large 
gut, and may even produce spasmodic contraction of the musculature of the 
intestine. This condition may be termed dysperistalsis, corresponding to 
dyspnoea. The condition of the blood flowing through the intestinal vessels 
affects the peristalsis. MOVEMENTS OF THE INTESTINE. 
[Sec. 161. 
Condition of the Blood.—Dysperistalsis may be produced by (a) interrupting the circu- 
lation of the blood in the intestines, no matter whether anaemia (as after compressing the aorta— 
Schiff) or venous hyperaemia be produced. The stimulating condition is the want of O, i. e., 
the increase of C02. Very slight disturb- 
ance in the intestinal blood-vessels, e. g., 
venous congestion after copious transfusion 
into the veins, whereby the abdominal and 
portal veins become congested, causes in- 
creased peristalsis. The intestines become 
nodulated at one part and narrow at an- 
other, and involuntary evacuation of the 
fasces takes place when there is conges- 
tion, owing to the plugging of the intesti- 
nal blood-vessels when blood from another 
species of animal is used for transfusion 
(£ 102). The marked peristalsis which 
occurs on the approach of death is un- 
doubtedly due to the derangements of the 
circulation, and the consequent alteration 
of the amount of gases in the blood of the 
intestine. The same is true of the in- 
creased movements of the intestines, which 
occur as a result of psychical excitement, 
e. g., grief. The stimulus, in this case, 
passes from the cerebrum through the 
medulla oblongata (vaso-motor centre) to 
the intestinal nerves, and causes anaemia 
of the intestine (corresponding to the pal- 
lor occurring elsewhere). When the nor- 
mal condition of the circulation is restored, 
the peristalsis diminishes. (£) Direct 
stimulation of the intestine, conducted to 
the plexus myentericus, causes dysperistal- 
sis ; direct exposure of the intestines to 
the air (stronger when C02 or Cl is pres- 
ent)—introduction of various irritating sub- 
stances into the intestine—increased filling 
of the intestine when there is any difficulty 
in emptying the gut (often in man)—di- 
rect stimulation of various kinds (also in- 
flammation),—all act upon the intestine, 
either from without or from within. Induction-shocks applied to a loop of intestine in a hernial 
sac cause lively peristalsis in the hernia. With increasing heat, at first there is diminished move- 
ment or cessation of movement (stimulation of the splanchnics); on heating to 430 the move- 
ments recommence. 
4. The continued application of strong stimuli causes the dysperistalsis to 
give place to rest, owing to over-stimulation, which may be called “ intestinal 
paresis,” or exhaustion. 
This condition is absolutely different from the passive condition of the intestine in aperistalsis. 
Continued congestion of the intestinal blood-vessels ultimately causes intestinal paralysis, e. g., 
when transfusion of foreign blood causes coagulation within these vessels. Filling the blood- 
vessels with “indifferent” fluids, after the peristalsis has been previously brought about by 
compressing the aorta, also causes cessation of the movements (O. Nasse). The movements 
cease when the intestines are cooled to 190 C. (Horwatk), while severe inflammation of the 
intestine has a similar effect. Under favorable circumstances, the intestine may recover from 
this condition. Arterial blood admitted into the vessels of the exhausted intestine causes 
peristalsis, which at first is more vigorous than normal. 
5. The continued application of strong stimuli causes complete paralysis 
of the intestine, such as occurs after violent peritonitis, or inflammation of the 
musculature or mucous coat in man. In this condition the intestine is greatly 
distended, as the paralyzed musculature does not offer sufficient resistance to 
the intestinal gases which are expanded by the heat. This constitutes the con- 
dition of meteorism. 
Plexus of Meissner, a, ganglia; b, anastomosing 
fibres ; c, artery; d, vaso-motor nerve-fibres accom- 
panying c. 
Fig. 207. Sec. 161.] 
289 
INFLUENCE OF NERVES ON THE INTESTINE. 
Influence of Nerves.—With regard to the nerves of the intestine, stimula- 
tion of the vagus increases the movements (of the small intestine), either by- 
conducting impressions to the plexus myentericus, or by causing contraction of 
the stomach, which stimulates the intestine in a purely mechanical manner 
(.Braam-Houckgeest). The splanchnic is (i) the inhibitory nerve of the 
small intestine (Pfluger), but only as long as the circulation in the intestinal 
blood-vessels is undisturbed, and the blood in the capillaries does not become 
venous; when the latter condition occurs, stimulation of the splanchnic 
increases the peristalsis. If arterial blood be freely supplied, the inhibitory 
action continues for some time. Stimulation of the origin of the splanchnics, 
of the spinal cord in the dorsal region (under the same conditions), and even 
when general tetanus has been produced by the administration of strychnia, 
causes an inhibitory effect. It is inferred that the splanchnic contains besides 
inhibitory fibres—which are easily exhausted by a venous condition of the 
blood, also (2) motor fibres, which remain excitable for a longer time, 
because after death stimulation of the splanchnics always causes peristalsis, just 
like stimulation of the vagus. (3) It is the vaso-motor nerve of the intes- 
tinal blood-vessels, so that it governs the largest vascular area in the body. 
When it is stimulated, all the vessels of the intestine which contain muscular 
fibres in their walls contract; when it is divided, they dilate. In the latter 
case, a large amount of blood accumulates within the blood-vessels of the 
abdomen, so that there is anaemia of the other parts of the body, which may 
be so great as to cause death—owing to the deficient supply of blood to the 
medulla oblongata. (4) It is the sensory nerve of the intestine, and, under 
certain circumstances, it may give rise to very painful sensations. 
As stimulation of the splanchnic contracts the blood-vessels, von Basch has raised the ques- 
tion whether the intestine does not come to rest, owing to the want of the blood, which acts as 
a stimulus. But, when a weak stimulus is applied to the splanchnic, the intestine ceases to 
move before the blood-vessels contract (van Braam-Houckgeest'); it would therefore seem that 
the stimulation diminishes the excitability of the plexus myentericus. According to Engel- 
mann and v. Brakel, the peristaltic movement is chiefly propagated by direct muscular conduc- 
tion, as in the heart and ureter, without the intervention of any nerve-fibres. 
[Effect of Nerves on the Rectum.—The nervi erigentes, when stimulated, causes the 
longitudinal muscular fibres of the rectum to contract, while the circular muscular fibres are sup- 
plied by the hypogastric nerves. Stimulation of the latter nerves also exerts an inhibitory effect 
on the longitudinal muscles. Stimulation of the nervi erigentes inhibits not only the spontaneous 
movements of the circular fibres of the rectum, but also those movements excited by stimulation 
of the hypogastric nerves (Fellner).] 
[Artificial Circulation in the Intestine.—Ludwig and Salvioli excised a loop of intestine 
from an animal, tied a cannula into an artery and another into a vein, and kept it in a warm, moist 
atmosphere. The arterial cannula was connected with a vessel containing defibrinated blood, 
to which different drugs could be added. A lever rested on the intestine and registered its 
movements on a recording surface. As long as arterial blood was transfused, the intestine was 
nearly quiescent, but when it was arrested, so that the blood became venous, a series of con- 
tractions occurred. Nicotin diminished the flow of blood and quickened the intestinal move- 
ments, while at the same time the circular muscular fibres remained contracted or tetanic. 
Tincture of opium, in the proportion of .01 to .04 in the blood, causes at first contraction of the 
vessels, and lessens the amount of blood circulating in the intestine ; but it very rapidly increases 
—even to six times—the amount of blood which transfuses, while at the same time the move- 
ments of the intestine cease, the walls of the intestine being contracted. Peptone caused first 
strong and then irregular contractions.] 
Effect of Drugs.—Amongst the reagents which act upon the intestinal movements are:— 
(1) Such as diminish the excitability of the plexus myentericus, i. e., which lessen or even 
abolish intestinal peristalsis, e. g., belladonna. (2) Such as stimulate the inhibitory fibres of the 
splanchnic, and in large doses paralyze them—opium, morphia; 1 and 2 produce constipation. 
(3) Other agents excite the motor apparatus—nicotin (even causing spasm of the intestine), 
muscarin, caffein, and many laxatives, which act as purgatives. The movements produced by 
muscarin are abolished by atropin. These substances accelerate the evacuation of the intestine, 
and, owing to the rapid movement of the intestinal contents, only a small amount of water is 
absorbed; so that the evacuations are frequently fluid. (4) Amongst purgatives, colocynth and INFLUENCE OF DRUGS ON THE INTESTINE. 
[Sec. 161. 
croton oil act as direct irritants. With regard to drugs of this sort, they seem to cause a watery 
transudation into the intestine, just as croton oil causes vesicles when applied to the skin. (5) 
Calomel is said to limit the absorptive activity of the intestinal wall, and to control the decom- 
positions in the intestine. The stools are thin and greenish, from the admixture of biliverdin. 
(6) Certain saline purgatives—sodium sulphate, magnesium sulphate—cause fluid evacuations 
by retaining the water in the intestine; and it is said that if they be injected into the blood- 
vessels of animals, they cause constipation. [When a crystal of a potash salt is applied to the 
peritoneal surface of the intestine of an animal, it causes merely a local constriction of the mus- 
cular fibres of the gut, while a sodium salt excites a 
contraction which passes upwards towards the stomachj 
and never towards the rectum. In any case it may serve 
as a useful guide to the surgeon, in determining which is 
the upper end of a piece of intestine during an operation 
on the intestines (Nothnagel).] 
Mucous coat. 
E. 
Gl. 
Mm. 
Sub-mucous 
coat. 
Muscular 
coat. 
Fig. 209. 
Serosa. 
Fig. 208. 
Fig. 210. 
Fig. 208.—Vertical section of the wall of the human stomach X 15. E., epithelium; Gl., 
glands; Mm., muscularis mucosae. Fig. 209.—Goblet-cells of the stomach. Fig. 210.— 
Surface section of the dog’s gastric mucous membrane, showing pits, i, i; a, the elevations 
round i, i. 
I. Transverse section of a duct of a fundus-gland—a, membrana propria; b, mucus-secreting 
goblet-cells; c, adenoid interstitial substance. II. Transverse section of a fundus-gland— 
a, chief, h, parietal cells; r, adenoid tissue ; c, capillaries. 
Fig. 211. Sec. 161.] 
STRUCTURE OF THE STOMACH. 
[Saline Cathartics.—A salt exerts a genuine excito-secretory action on the glands of the 
intestines, whilst at the same time, in virtue of its low diffusibility, it impedes absorption. 
Thus, between stimulated secretion and impeded absorption there is an accumulation of fluid 
within the canal, which reaches the rectum and results in purgation. Purgation does not ensue 
when water is withheld from the diet for one or two days previous to the administration of the 
salt in a concentrated form. When a concentrated solution of a salt is administered to an 
animal whose alimentary canal is empty, but whose blood is in a natural state of dilution, the 
blood becomes rapidly very concentrated, and reaches the maximum of its concentration in from 
half an hour to an hour and a half; within four hours the blood has gradually returned to its 
normal state of concentration, without having reabsorbed fluid from the intestine. It apparently 
recoups itself from the tissue-fluids. The salt—sulphate of magnesia or sulphate of soda—be- 
comes split up in the small intestine, and the acid is more rapidly absorbed than the base. A 
portion of the absorbed acid shortly afterwards returns to the intestines, evidently through the 
intestinal glands. The salt does not purge when injected into the blood, and excites no intestinal 
secretion; nor does it purge when injected subcutaneously, unless on account of its causing 
local irritation of the abdominal subcutaneous tissue, which acts reflexly on the intestines, dilating 
their blood-vessels, and perhaps stimulating their muscular movements (M. Hay).] 
162. STRUCTURE OF THE STOMACH.—[The stomach receives 
the bolus, and secretes a juice which acts on certain 
constituents of the food, while by its muscular walls it 
moves the latter within its own cavity, and after a time 
expels the partially digested products or chyme— 
towards the duodenum. In the adult when moderately 
distended its length is about 28 cm. and its greatest 
width 10 cm.] 
[Structure.—The walls of the stomach consist of 
four coats, which are from without inwards (fig. 208). 
(T) The serous layer, from the peritoneum. 
(2) The muscular layer, composed of three layers 
of non-striped muscular fibres—(a) longitudi- 
nal, (<£) circular, (r) oblique. 
(3) The sub-mucous layer of loose connective- 
tissue, with the larger blood-vessels, lymphatics, 
and nerves. 
(4) The mucous layer, containing the secretory 
glands.] 
The well-developed mucous membrane of the 
stomach is thrown into a series of folds or rugae, in a 
contracted condition of the organ. With the aid of a 
hand-lens, it is seen to be beset with small irregular 
depressions or pits (fig. 210). Throughout its entire 
extent it is covered by a single layer of moderately tall, 
narrow, cylindrical epithelium, which seems to 
consist of mucus-secreting goblet-cells (fig. 209). 
The epithelium is sharply defined at the cardia from 
the stratified epithelium of the oesophagus, and also at 
the pylorus, from the true cylindrical epithelium with 
the striated disc in the duodenum. [The cells contain 
a plexus of fibrils, and in the passive condition seem 
to consist of two zones, an inner clear part, next the lumen of the organ, con- 
sisting of a substance (mucigen) which yields mucus, the attached end of the 
cell being granular.] The oval nucleus lies about the centre of the cells. 
Spindle-shaped, nucleated cells, probably for replacing the others, are said by 
Ebstein to occur at their bases. All the cells are open at their free ends, so 
that the mucus is readily discharged, leaving the cells empty. Numerous tubu- 
lar glands of two distinct kinds are placed vertically, like rows of test-tubes, 
in the mucous membrane. 
Fig. 212. 
Isolated pyloric gland. 292 
STRUCTURE OF THE FUNDUS-GLANDS. 
[Sec. 162. 
The cardiac portion of the gastric mucous membrane consists of a number 
of microscopic tubular glands [5 mm. to 2 mm. in length and 50-80/2 in width], 
placed side by side in a vertical position,—the fundus-glands of Heidenhain, 
otherwise called peptic, or cardiac. Several gland-tubes, which are wider 
below, usually open into the duct (fig. 213). Each gland consists of a struc- 
tureless membrana propria with anastomosing branched cells in relation with it. 
[Each gland has a “ mouth,” by which it opens into the stomach; the mouth 
and duct together form about one-third of the gland. The deeper part of the 
Vertical section of the gastric mucous membrane, g, g, pits on the surface ; p, neck of a fundus- 
gland opening into a duct, g; x, parietal, andp, chief cells; a, v, c, artery, vein, capilla- 
ries; d, d, lymphatics, emptying into a large trunk, e. 
Fig. 213. 
gland, called the “body ” or “ secretory part,” the largest part of the gland, 
is joined to the duct by a “ neck.”] The duct is short, about one-fifth to one- 
third of the whole tube, and is lined by a layer of cells like those lining the 
stomach, while the secretory part of the tubes is lined throughout by a layer 
of faintly granular, short, small, polyhedral, or columnar nucleated cells. These 
cells border the very narrow tortuous lumen, and are called principal, chief, 
central (fig. 211, II, a), or adelomorphous cells (AdyAos, hidden). At 
various places, between these cells and the membrana propria, are large, oval, Sec. 162.] 
STRUCTURE OF THE PYLORIC GLANDS. 
293 
or angular, well-defined, coarsely granular, densely reticulated, nucleated cells, 
the parietal cells of Heidenhain, the delomorphous cells of Rollett, the 
oxyntic (6~wsiv, to sharpen, acidulate), or acid-forming cells of Langley (fig. 
211, II,//), or ovoid cells. They are most numerous in the neck of the glands, 
and less so and larger in the deep blind end or fundus of the tubes. These cells 
do not form a continuous layer, and are stained deeply by osmic acid and ani- 
line blue (fig. 217), so that they are readily distinguished from the other cells. 
They bulge out the membrana propria of the gland opposite where they are 
placed. The parietal cells in man are said to reach to the lumen of the gland-tubes 
{Stohr). Isolated cells are sometimes found under the epithelium of the sur- 
face of the stomach, and occasionally in individual pyloric glands. The fundus- 
glands are most numerous (about five millions), and are of considerable size in 
the fundus. At the cardia there is a circular layer of gland-tubes without parietal 
cells which secrete a diastatic ferment (Edelmann). 
2. The pyloric glands occur only in the region of the pylorus, where the 
mucous membrane is more yellowish-white in color (fig. 212). These glands 
are generally branched at their lower ends, so that several tubes open into a 
single duct [which, in contra-distinction to the duct of the cardiac glands, is 
wide and long, extending often to half the depth of the mucous membrane. 
They are not so closely packed as the fundus glands. The mouth and duct 
are lined by epithelium like that lining the stomach, while the secretory part 
is lined by a single layer of short, finely granular, columnar cells, whose secre- 
tion is quite different from that of the cells lining the duct. The lumen is well 
defined. Nussbaum has occasionally found other cells, which stain deeply with 
osmic acid, between the bases of these. The appearance of the cells differs 
according to their state of physiological activity (figs. 215, 216). When they 
are exhausted they are smaller and more granular, owing to the denser reticu- 
lation of their net-work ; at any rate they are granular in preparations hardened 
in alcohol (fig. 216). There are no parietal cells.] [Mahl by tryptic digestion 
has shown that the basement membranes of the gastric and other intestinal 
glands can be resolved into fibrils.] 
3. The glands are supported by very delicate connective-tissue mixed with 
adenoid tissue (fig. 211). Below this are two layers, circular and longitudinal, 
of non-striped muscle, the muscularis mucosse (fig. 208, Mm.'), and from it 
fine processes of smooth muscular fibres pass up between groups of the glands 
towards the free epithelial surface of the mucous membrane. Perhaps these 
processes are concerned in emptying the glands. [In the gastric mucous mem- 
brane of the cat, there is a clear homogeneous layer, which is stained red by 
picro-carmine, and placed immediately internal to the muscularis mucosse. It 
is pierced by the processes passing from the muscularis mucosse.] 
Masses of adenoid tissue occur in the mucous membrane, especially near 
the pylorus, constituting lymph-follicles, which are comparable to the soli- 
tary glands of the small intestine. The lymphatics are numerous, and begin 
close under the epithelium by dilated extremities or loops (fig. 213, d) ; they 
run vertically between the gland-tubes and anastomose in the mucosa between 
the gland-tubes, which they envelop in sinus-like spaces. They join large 
trunks in the mucosa ; another plexus of large vessels exists in the sub-mucosa 
{Loveii). 
[The Nerves.—A plexus of non-medullated nerve-fibres and a few ganglion 
cells exist in the muscular coat [Auerbach’s], and another [Meissner’s] in 
the sub-mucosa.] 
The blood-vessels are very numerous (fig. 214). Small arterial branches, 
a, run in the sub-mucosa, and ascend between the glands to form a longitudinal 
capillary network, c, c, under the epithelium, and between its meshes the gland- [Sec. 162. 
TRANSITION FROM STOMACH TO DUODENUM. 
ducts open, g. The veins gradually collect from this horizontal capillary net- 
work, and run towards the large veins of the sub-mucosa, v. 
[Transition from Stomach to Duodenum.—If a section be made through 
the junction of the stomach with the duodenum, it shows the appearances pre- 
sented in fig. 214. The glands of Brunner in the duodenum are seen to be 
homologous with the pyloric glands, but in the duodenum the acini of the 
glands of Brunner lie in the sub-mucous coat, while in the mucous coat itself 
the glands of Lieberkiihn appear, and with them the villi so characteristic of 
the small intestine.] 
163. THE GASTRIC JUICE.—Properties. —The gastric juice is a 
tolerably clear colorless fluid, with a strong acid reaction, sour taste, and 
peculiar characteristic odor; it rotates the plane of polarized light to the left. 
Villi. 
Mucous mem- 
brane of 
stomach. 
Mucous mem 
brane of duo- 
denum. 
Lieberkiihn’s 
glands. 
Sub-mucous 
coat, on the left 
with Brunner’s 
glands. 
Muscular coat. 
Vertical section of the junction between the stomach and duodenum. The blood-vessels injected. 
V, villi; MM, muscularis mucosae ; arteries red, veins blue. 
Tig. 214. 
It is not rendered turbid by boiling, and resists putrefaction for a long time. 
Its specific gravity = 1002.5 (dog, 1005), and it contains only per cent, of 
solid constituents. The quantity secreted in 24 hours was estimated by 
Beaumont, from observations upon Alexis St. Martin, who had a gastric fistula 
(1834)—at only 180 grms. daily (!); by Grunewald (1853), in a similar case, 
as equal to 26.4 per cent, of the body-weight; while Bidder and Schmidt 
(from corresponding observations on dogs) estimated it as equal to kilos, 
daily, corresponding to of the body-weight. It contains :— 
(1) Pepsin, the characteristic hydrolytic ferment or enzyme, which in an 
acid medium dissolves proteids. E. Schiitz obtained 0.41 to 1.17 per cent, 
from a fasting person by means of the oesophageal sound. Sec. 163.] 
COMPOSITION OF GASTRIC JUICE. 
295 
(2) Free hydrochloric acid (.Pront, 1824), 0.2 to 0.3 (.Richet, 0.8 to 2.1) 
per cent.; (in the dog, 0.52 per cent.). The acid occurs as free hydrochloric 
acid, as from the gastric juice there can always be obtained more free chlorine 
than bases to which the latter can be united (C. Schmidt). Lactic acid is 
usually met with, but it arises from the fermentation of the carbohydrates of 
the food. 
Tests.—Free hydrochloric acid is detected by the following reactions: 0.025 per cent, 
solution of methyl-violet becomes blue, especially after tannic acid has been added to the fluid ; 
or alkaline solution of oo-tropseolin becomes lilac; or, red Bordeaux wdne, treated with amylic 
alcohol until its color almost disappears, becomes rose-colored. An amylic alcohol extract of 
Fig. 215. 
Pyloric glands, showing changes of the 
cells during digestion. 
Fig. 216. 
Section of the pyloric mucous membrane. 
ripe bilberries is made red by dilute HC1. [Giinzburg recommends an alcoholic solution of 
phloroglucin-vanillin. 2 grams of phloroglucin are mixed with 1 gram of vanillin in 30 grams 
of absolute alcohol, which gives a yellowish-red solution. Concentrated and even very weak 
mineral acids cause, with this solution, a bright red color with the formation of bright red 
crystals, while concentrated organic acids do not affect it. For gastric juice, mix equal quantities 
of the filtered gastric juice and the above solution in a watch-glass, and evaporate carefully, not 
allowing it to boil; a red pellicle with red crystals indicates the presence of minute traces of 
hydrochloric acid. Congo-red, either in solution or as congo-red papers, becomes blue, but the 
reaction is interfered with by the presence of ammonia, or ammoniacal salts.] 
Lactic Acid.—The freshly-prepared blue solution of 10 c. c. of a 4 per cent, solution of 
carbolic acid, with 20 c. c. of distilled water, and 1 drop of liquor ferri perchloride, is changed to 296 
COMPOSITION OF GASTRIC JUICE. 
[Sec. 163. 
yellow by lactic acid (Uffelmann). Allow the fluid to drop into the test; at the point of contact 
there is a citron-yellow color. 
(3) The large amount of mucus covering the surface of the mucous mem- 
brane is secreted by the goblet-cells of the mucous membrane (§ 162). 
(4) Mineral salts (2 per 1000). 
They are chiefly sodium and potassium chlorides, less calcic chloride (ammonium chloride, also 
in animals), and the compounds of phosphoric acid with lime, magnesium, and iron. 
(5) A milk-curdling ferment (rennet or rennin). 
Amongst foreign substances, which may be introduced into the body, the following appear in 
the gastric juice—HI, after the use of potassium iodide—potassium sulphocyanide, ferric lactate, 
and sugar; and ammonium carbonate in uraemia. 
[Composition of Gastric Juice (.Hoppe-Seyler after C. Schmidt). 
Constituents. 
I. 
Human. 
H. 1 hi. 
Dog. 
IV. 
Sheep. 
Water, 
994.404 
With saliva. 
97I.I7I 
No saliva. 
973.062 
986.143 
Organic matter, .... 
3-195 
I7-336 
I7.I27 
4.055 
Free HC1, 
0.200 
2-337 
3-050 
I.234 
CaCl2, 
NaCl, 
0.061 
1.661 
O.624 
0.II4 
1.465 
3-H7 
2.507 
4.369 
KC1, 
o.55o 
1-073 
I.I25 
I.518 
NH4C1, 
0-537 
O.468 
0-473 
(Ja32( P04), 
) f 
2.294 
I.729 
1.182 
Mg32(P04), 
0.323 
0.226 
0-577 
FeP04, 
i i 
0.121 
0.082 
0.331 
Good human saliva is not so dilute or so poor in HC1 as No. X. Szabo has found even 3 of 
HC1 per 1000 in Than.] 
[Comparative.—The above table shows that the gastric juice of mammals has approximately 
the same composition as that of man, but there is more acid in the case of the carnivora than in 
herbivora and man. The acidity is very considerable in fishes. It is said that in certain inver- 
tebrates (crustaceans), the gastric juice is alkaline.] 
[The pepsin in frogs seems to be different from that in mammals, at least it is active at o° C. 
at which temperature mammalian pepsin is inactive.] 
[The gastric juice of new-born dogs and rabbits does not contain pepsin, but it appears a few 
days after birth. In the dog, according to Hammarsten, pepsin is formed until the third week 
after birth ; while pepsin is present in the human foetal mucous membrane just before birth, the 
acid appears much sooner.] 
164. SECRETION OF GASTRIC JUICE.—After the discovery of 
the two kinds of glands in the stomach and the two kinds of cells in the fundus- 
glands, the question arose as to whether the different constituents of gastric 
juice were formed by different histological elements. 
Changes of the Cells during Digestion.—During the course of digestion, the cells of the 
fundus (and pyloric glands, dog) undergo important changes (.Heidenhain). During hunger, 
the chief cells are clear and large, the parietal investing cells are small, the pyloric cells clear 
and of moderate size. During the first six hours of digestion, the chief cells become enlarged 
and moderately turbid or granular, the parietal cells also enlarge, while the pyloric cells remain 
unchanged (fig. 217). The chief cells become diminished and more turbid or granular until the 
ninth hour, the parietal cells are still swollen, and the pyloric cells enlarge (fig. 217, D). During 
the last hours of digestion, the chief cells again become larger and clearer, the parietal cells 
diminish, the pyloric cells decrease in size and become turbid (figs. 215, 216). 
[Langley gives a different description of the appearances presented by these cells. The 
results may be reconciled by remembering that the gland-cells were examined under different 
conditions. The secretory cells consist of a cell-substance composed of (a) a framework of living 
protoplasm, either in the form of an intracellular fibrillar network, or in flattened bands. The 
meshes of this framework enclose at least two chemical substances, viz., (b) a hyaline substance 
in contact with the framework, and (c) spherical granules which are imbedded in the hyaline 
substance. During active secretion, the granules decrease in number and size, the hyaline sub- Sec. 164.] 
CHANGES OF THE GASTRIC CELLS DURING SECRETION. 
297 
stance increases in amount, the network grows. This is the reverse of what is stated above as 
the observation of Fleidenhain, but the granular appearance described by Fleidenhain after secre- 
tion is very probably due to the action of the hardening agent, alcohol. Langley found that in 
the living condition, or after the use of osmic acid, in some animals at least, the chief cells are 
granular during rest, but during a state of activity two zones are differentiated—an outer one, 
which is clear, owing to the disappearance of the granules, and an inner more or less granular 
one. Granules reappear in the outer part after rest. During digestion, the parietal cells increase 
in size, but do not become granular. In all cells containing much pepsinogen distinct granules 
are present, and the quantity of pepsinogen varies directly with the number and size of the 
granules. In the glands of some animals there is little difference between the resting and active 
phases. Compare Serous Glands, § 143, and Pancreas, \ 168.] 
Fig. 217. 
Fundus glands of dog stained with aniline blue. A and A/, when animal was starved ; B, first 
stage of digestion, enlargement of the chief cells; C and D, second stage of digestion, 
progressive diminution and increased turbidity of the chief cells (Heidenhain). 
Pepsin is formed in the chief cells of the fundus-glands. When these 
are large, they contain much pepsin ; when they are turbid, the amount is 
small. The pyloric glands are also said to secrete pepsin, but only to a small 
extent. Pepsin accumulates during the first stage of hunger, and it is eliminated 
during digestion, and also during prolonged hunger. Pepsin, as such, is not 
present within the cells, but only as a “ mother-substance,” a pepsinogen- 
substance (zymogen), or propepsin, which occurs in the granules of the 
chief cells. This zymogen, or mother-substance, by itself, has no effect upon 
proteids; but if it be treated with hydrochloric acid or sodium chloride, it is 298 
THE FORMATION OF PEPSIN AND ACID. 
[Sec. 164. 
changed into pepsin. Pepsin and pepsinogen may be extracted from the gas- 
tric mucous membrane by means of water free from acids. 
[The chief reasons adduced for the view that the chief cells secrete pepsin are as follows:—(i) 
The principal cells disappear by auto-digestion when the mucous membrane is placed in I per 
cent, hydrochloric acid, while the parietal cells swell up and do not disappear; (2) There is a 
relation between the volume of these cells and the quantity of pepsin obtainable from the mucous 
membrane ; (3) The pyloric region, which contains no parietal cells, also secretes pepsin; (4) In 
frogs the pepsin is formed in the oesophageal glands, which contain only cells analogous to the 
principal cells, while the stomach contains glands with parietal cells, but it secretes acid, and no 
pepsin; (5) In the bat during hibernation the principal cells disappear almost entirely while 
digestive activity is suspended.] 
[Pepsinogen and Pepsin.—Glycerin extracts very little pepsin from the perfectly fresh 
gastric mucous membrane, but a large amount is afterwards obtained by extracting it with dilute 
hydrochloric acid, or with this acid and glycerin. The relative amount of pepsinogen and pepsin 
in a fluid may be determined approximately by the method of Langley and Edkins. A 1 per 
cent, solution of sodic carbonate exerts a greater destructive action on pepsin than on pepsinogen, 
while a current of C02 destroys pepsinogen to a greater extent than pepsin. Both substances are 
unaffected by CO, but are destroyed at 540 to 570 C.] 
[That pepsinogen exists in the mucous membrane is proved as follows :—Extract the mucous 
membrane with water, or glycerin free from acid, until no more pepsin is obtainable from the 
membrane. Then treat the latter with dilute hydrochloric acid or sodic chloride, when a fresh 
quantity of pepsin is at once obtainable. More pepsin is formed or set free by the action of 
these re-agents upon some other body, which has been called propepsin and pepsinogen.] 
The pyloric glands also secrete pepsin but no acid. Klemensiewicz 
excised in a living dog the pyloric portion of the stomach, and afterwards 
stitched together the duodenum and the remain- 
ing part of the stomach. The excised pyloric 
part, with its vessels intact, he stitched to the 
abdominal wall, after sewing up its lower end. 
The animals experimented on died, at the latest, 
after six days. The secretion of this part was thin, 
alkaline, and contained 2 per cent, of solids, in- 
cluding pepsin. 
[Pyloric Fistula.—In fig. 218, P represents the excised 
pyloric portion, C the cardiac. The parts a, a, and a' ar 
were then stitched together, and the continuity of the organ 
established. The lower end (<-/) of P was closed by sutures, 
while the edges of P at o were stitched to the abdominal 
walls, thus making a pyloric fistula.] 
In the frog the alkaline glands of the oesophagus contain only chief cells 
which produce pepsin ; while the stomach has glands which secrete acid (and 
perhaps some pepsin), and are lined by parietal cells. 
Amongst fishes the carps have no fundus-glands in the stomach (Luchaii). [The secreting 
portions of glands of the cardiac sac (crop) of the herring are lined by a single layer of polygonal 
cells [W. Stirling).] 
The hydrochloric acid is formed, according to Heidenhain, by the 
parietal cells. It occurs on the free surface of the gastric mucous mem- 
brane as well as in the ducts of the fundus-glands. The deep parts of the glands 
are usually alkaline. Free HC1 is detected in human gastric juice, within 45 
minutes to 1 or 2 hours after a moderate meal, but in 10 to 15 minutes in a 
fasting condition after drinking water; the amount gradually increases during 
the process of digestion. Lactic acid, perhaps derived from the food, is found 
in the stomach immediately after taking food, after half an hour, along with 
HC1, while after an hour only HC1 is found (Bwald and Boas). 
Cl. Bernard injected lactate of iron, and some time afterwards potassium ferrocyanide, into the 
veins of a dog. After death, blue coloration occurred only in the upper acid layers of the 
mucous membrane. Nevertheless, we must assume that the hydrochloric acid is secreted in the 
Diagram of Klemensiewicz’s 
experiment (Stirling) 
Fig. 218. Sec. 164.] 
THE SECRETION OF GASTRIC JUICE. 
parietal cells of the fundus of the glands, and that it is rapidly carried to the surface along with 
the pepsin. Briicke neutralized the surface of the gastric mucous membrane with magnesia usta, 
chopped up the mucous membrane with water, and left it for some time, when the fluid had 
again an acid reaction. 
As to the formation of a free acid, the following statements may be 
noted: The parietal cells form the hydrochloric acid from the chlorides 
which the mucous membrane takes up from the blood. According to Voit, 
the formation of acid ceases, if chlorides be withheld from the food. Maly 
suggests that the active agent is lactic acid, which splits up sodium chloride 
and forms free HC1. The base set free is excreted by the urine, rendering it 
at the same time less acid. The formation of acid is arrested during hunger. 
According to H. Schultz, watery solutions of alkaline and earthy chlorides are 
decomposed, even at a low temperature, by C02, free hydrochloric acid being 
formed. 
[If thin sections of the fresh mucous membrane be placed for a day in lactate of iron, and 
then treated with potassic ferrocyanide, Sehrwald finds that the parietal cells become dark blue, 
while the chief cells remain colorless, so that the chief cells appear to be alkaline and the 
parietal cells acid.] 
[The source of the HC1 is undoubtedly the sodic chloride in the blood and lymph, but 
what other acid displaces the HCl is a matter of conjecture. In this connection, it is important 
to remember that Jul. Thomsen has shown that every acid can displace a part of another acid 
from its combination with its base, and the weaker acid may even combine with the greater part 
of the base. Thomsen calls this “avidity.” Even strong mineral acids may be displaced by 
weak organic ones. Thus the free C02 in the alkaline blood may set free a small quantity of 
HC1 from the sodic chloride. What is still more remarkable is, that the free HC1 should be 
transferred by the cells towards the gland-duct while the sodic carbonate diffuses towards the 
blood and lymph.] 
[The milk-curdling ferment or rennin exists in the mucous membrane in 
the state of a zymogen, from which it is formed under the action of acids. 
According to Langley it exists in the principal cells.] 
Secretion.—[The secretion of gastric juice is intermittent except in the 
case of those animals like the rabbit, whose stomachs always contain food.] 
When the stomach is empty, there is usually no secretion of gastric juice; 
this takes place only after appropriate (mechanical, thermal, or chemical) 
stimulation. In the normal condition, it takes place immediately on the intro- 
duction of food, but also of indigestible substances, such as pebbles. The 
mucous membrane becomes red, and the circulation more active, so that the 
venous blood becomes brighter. [That the vagi are concerned in this vascular 
dilatation is proved by the fact that if both nerves be divided during digestion, 
the gastric mucous membrane becomes pale (.Rutherford).] The secretion is 
probably caused reflexly, and the centre perhaps lies in the wall of the stomach 
itself (Meissner’s plexus in the sub-mucous coat). It is asserted that the idea 
of food, especially during hunger, excites secretion. As yet we do not know 
the effect produced upon the secretion by stimulation or destruction of other 
nerves, e.g., vagus, sympathetic. [There is no nerve passing to the stomach, 
whose stimulation causes a secretion of gastric juice, as the chorda tympani 
does in the sub-maxillary gland. If the vagi be divided sufficiently low down 
not to interfere with respiration, the introduction of food still causes a secre- 
tion of gastric juice; even if the sympathetic branches be divided at the same 
time, secretion still goes on (.Heidenhain). Division of the vagi in the neck is 
not a satisfactory experiment in relation to the secretion of gastric juice, for 
this experiment produces so many other effects. If the vagi be divided below 
the origin of the pulmonary and cardiac branches, gastric juice containing 
pepsin and capable of digestion is said by some observers to be still secreted 
(see under). This experiment points to the existence of local secretory centres 
in the stomach. But there is evidence to show that there is some connection, 
299 300 
METHODS OF OBTAINING GASTRIC JUICE. 
[Sec. 164. 
perhaps indirect, between the central nervous system and the gastric glands. 
Richet observed a case of complete occlusion of the oesophagus in a woman, 
produced by swallowing a caustic alkali. A gastric fistula was made, through 
which the person could be nourished. On placing sugar or lemon juice in the 
person’s mouth, Richet observed a secretion of gastric juice. In this case no 
saliva could be swallowed to excite secretion, so that it must have taken place 
through some nervous channels. Even the sight or smell of food caused 
secretion. Emotional states also are known to interfere with gastric diges- 
tion.] 
[In dogs Pawlow made a gastric fistula, divided the oesophagus, and stitched the two cut ends 
of the latter into the wound in the neck. After recovery of the animals he found that flesh, 
when eaten, excited a copious reflex secretion of gastric juice (20 c.c. in 5 minutes) in an empty 
stomach. Of course the food in this case escaped by the divided oesophagus and did not enter 
the stomach. This effect was not altered by section of the splanchnic nerves. Division of the 
vagi, however, completely abolished the reflex. After section of the vagi, for several days only 
strongly acid mucus flowed from the stomach, but it had scarcely any action on proteids. Stim- 
ulation of the peripheral end of the divided left vagus caused a clear watery fluid to flow from 
the fistula, which, although less acid than normal juice, was capable of digesting proteids.] 
Effect of Absorption of Peptic Products.—Heidenhain isolated a part 
of the mucous membrane of the fundus so as to form a blind sac of it, and he 
found that mechanical stimulation caused merely a scanty local secretion at the 
spots irritated. If, however, at the same time, absorption of digested matter 
also occurred, secretion took place over larger surfaces. [He distinguishes a 
primary and merely local secretion excited by the mechanical stimulus of the 
ingesta, and a secondary depending on absorption, and extending to the whole 
of the mucous membrane.] 
The statement of Schiff, that active gastric juice is secreted only after absorption of the so- 
called peptogenic substances (especially dextrin) is contradicted by other observers. 
The acid contents of the stomach called chyme, which pass into the 
duodenum after gastric digestion is completed, are neutralized by the alkali of 
the intestinal mucous membrane and the pancreatic juice, [at the same time a 
precipitate is formed and deposited on the walls of the duodenum, and it car- 
ries the pepsin down with it]. Part of the pepsin is reabsorbed as such, and is 
found in traces in the urine and muscle juice (Brticke). If the gastric juice be 
completely discharged externally through a gastric fistula, the alkalinity of the 
intestine is so strong that the urine becomes alkaline {Maly). 
The acid gastric juice of the new-born child is already fairly active; casein is most easily 
digested by it, then fibrin and the other proteids (Zweifel). When the amount of acid is too 
great in the stomach of sucklings, large, firm, indigestible masses of casein are apt to be formed, 
especially after the use of cow’s milk (§ 230). 
[Action of Drugs on Gastric Secretion.—Dilute alkalies, if given before food; saliva; 
some substances called peptogens by Schiff, such as dextrin and peptones, alcohol and ether, 
all excite secretion, the last being very powerful. When the secretion is excessively acid, ant- 
acids are given, some diminishing the acidity in the stomach, as the carbonates and bicarbonates 
of the alkalies, liquor potassae, and the carbonate of magnesia; while the citrates and tartrates 
of the alkalies, becoming converted into carbonates in their passage through the organism, di- 
minish the acidity of the urine.] Small doses of alcohol, introduced into the stomach, increase 
the secretion of gastric juice; large doses arrest it, Artificial digestion is affected by 10 per cent, 
of alcohol, is retarded by 20 per cent., and is arrested by stronger doses. Beer and wine hinder 
digestion, and in an undiluted form interfere with artificial digestion. 
165. METHODS OF OBTAINING GASTRIC JUICE.—Historical.—Spallan- 
zani caused starving animals to swallow small pieces of sponge enclosed in perforated lead cap- 
sules, and after a time, when the sponges had become saturated with gastric juice, he removed 
them from the stomach. To avoid the admixture of saliva, the sponges are best introduced 
through an opening in the oesophagus. Dr. Beaumont (1825), an American physician, was the 
first to obtain human gastric juice, from a Canadian named Alexis St. Martin, who was injured 
by a gun-shot wound, whereby a permanent gastric fistula was established. Various substances Sec. 165.] 
PREPARATION OF PEPSIN. 
301 
were introduced through the external opening, which was partially covered with a fold of skin, 
and the time required for their solution was noted. Bassow (1842), Blondlot (1843), and Bar- 
deleben (1849) were thereby led to make artificial gastric fistulae. 
Gastric Fistula.—The anterior abdominal wall is opened by a median incision just below 
the ensifornr cartilage, the stomach is exposed, and its anterior wall opened and afterwards 
stitched to the margins of the abdominal walls. A strong cannula is placed in the fistula thus 
formed. The tube is kept corked. If the ducts of the salivary glands be tied, a perfectly un- 
complicated object for investigation is obtained. 
According to Leube, dilute human gastric juice may be obtained by means of a siphon-like 
tube introduced into the stomach. Water is introduced first, and after a time it is withdrawn. 
An important advance was made when Eberle (1834) prepared artificial gastric juice, by 
extracting the pepsin from the gastric mucous membrane with dilute hydrochloric acid. Four 
litres of solution of hydrochloric acid, containing 4 to 8 c. c. HC1 per 1000, are sufficient to 
extract the chopped-up mucous membrane of a pig’s stomach. Half a litre is infused with the 
stomach and renewed every six hours. The collected fluid is afterwards filtered. The substance 
to be digested is placed in this fluid, and the whole is kept at the temperature of the body, but 
it is necessary to add a little HC1 from time to time (Schwann). The HC1 may be replaced by 
ten times its volume of lactic acid and also by nitric acid; while oxalic, sulphuric, phosphoric, 
acetic, formic, succinic, tartaric, and citric acids are much less active; butyric and salicylic acids 
are inactive. 
Von Wittich’s Method.—(a) Glycerin extracts pepsin in a very pure form. The mucous 
membrane is rubbed up with powdered glass until it forms a pulp, mixed with glycerin, and 
allowed to stand for eight days. The fluid is pressed through cloth, and the filtrate mixed with 
alcohol, thus precipitating the pepsin, which is washed with alcohol and afterwards dissolved in 
the dilute HC1, to form an artificial digestive fluid. (b) Or the mucous membrane may be placed 
for twenty-four hours in alcohol, and afterwards dried and extracted for eight days with glycerin. 
(<r) Wm. Roberts has used other agents for extracting enzymes ($ 148). 
Preparation of Pure Pepsin.—Briicke pours on the pounded mucous membrane of the 
pig’s stomach a 5 per cent, solution of phosphoric acid, and afterwards adds lime-water until the 
acid reaction is scarcely distinguishable. A copious precipitate, which carries the pepsin with 
it, is produced. This precipitate is collected on cloth, fepeatedly washed with water, and after- 
wards dissolved in very dilute HC1. A copious precipitation is caused in this fluid by gradually 
adding to it a mixture of cholesterin in four parts of alcohol and one of ether. The cholesterin 
pulp is collected on a filter, washed with water containing acetic acid, and afterwards with pure 
water. The cholesterin pulp is placed in ether to dissolve the cholesterin, and the ether is then 
removed. The small watery deposit contains the pepsin in solution. 
Pepsin so prepared is a colloid substance; it does not react like albumin 
with the following tests, viz. :—It does not give the xanthroprotein reaction 
(§ 248), is not precipitated by acetic acid and potassium ferrocyanide, nor by 
tannic acid, mercuric chloride, silver nitrate, or iodine. In other respects it 
belongs to the group of albuminoids. It is rendered inactive in an acid fluid 
by heating it to 550 to 6o° C. 
166. PROCESS OF GASTRIC DIGESTION.—[In the process of 
gastric digestion we have to consider— 
1. The secretion of gastric juice and its action on food. 
2. The absorption of the products of this digestion. 
3. The movements of the stomach itself.] 
Chyme.—The finely divided mixture of food and gastric juice is called 
chyme. The gastric juice acts upon certain constituents of chyme. 
I. Action on Proteids.—Pepsin and the dilute hydrochloric acid, at the 
temperature of the body, transform proteids into a soluble and diffusible form, 
to which Lehmann (1850) gave the name of “peptone” (§ 249, III). 
Fibrin (or coagulated proteids) first becomes clear and swollen up. [There 
seems to be a close relation between the acid and the ferment, so much so that 
some have spoken of it as “pepsin-acid,” and others as “pepto-hydrochloric 
acid.”] 
[It is commonly stated that the first product formed during the gastric diges- 
tion of proteids is syntonin or para-peptone, then hemi-albumose or 
pro-peptone, and finally peptone. The products vary, however, with the 302 
THE PRODUCTS OF GASTRIC DIGESTION. 
[Sec. 166. 
proteid digested. Kiihne has shown that the proteid molecule is split up, and 
yields two groups, which he calls hemi-peptone and anti-peptone (p. 303). 
A mixture of the two he calls ampho-peptone. Hemi-peptone can be 
split up into leucin and tyrosin by trypsin, while the anti-peptone does not 
undergo this change. The intermediate body, or pro-peptone, is really a mix- 
ture of several bodies. Kuhne called it hemi-albumose. These intermediate 
bodies from albumin are called albumoses, from globulins globuloses, from 
casein caseoses. Halliburton calls all these intermediate bodies “proteoses.”] 
Properties of Hemi-albumose.—Although a composite body, hemi-albu- 
mose gives the following reactions : It is highly soluble in water; when heated 
to 50° to 6o° it becomes somewhat turbid, but when boiled it becomes clear, 
and gets turbid again on cooling. This effect is most marked when it is treated 
with acetic acid and sodic chloride, or the latter alone. It is precipitated by 
acetic acid and potassic ferrocyanide, but the precipitate disappears on heating 
and reappears on cooling. It gives the biuret rosy tint reaction like peptones. 
It is precipitated by nitric acid, and the precipitate adheres to the glass, but is 
soluble in the acid with the aid of heat, -yielding a yellow fluid, but is precipita- 
ted on cooling. It is precipitated by boiling with acetic acid and a strong solu- 
tion of sodic sulphate, metaphosphoric acid, and pyrogallic acid (Kiihne). It 
is said to be present in .all animal tissues except muscle and nerve (§ 293). 
[Albumoses are the first products of the splitting up of proteids by 
enzymes, and from them peptones are ultimately formed. They may be made 
from Witte’s peptone, or by the peptic digestion of fibrin. Such a mixture, on 
being neutralized with sodic carbonate, gives a copious precipitate of para- 
peptones, which can be filtered off, leaving a clear solution of albumoses. 
Para-peptones are said to be closely related to acid-albumin or syntonin. On 
saturating the clear fluid with NaCl, a dense white precipitate, consisting of 
three albumoses, called protodys-, and hetero-albumose is obtained ; a 
fourth, deutero-albumose, remains in solution, but can be precipitated by 
adding acetic acid. If the albumose precipitate be treated with 10 per cent. 
NaCl solution, proto- and hetero-albumose are dissolved, leaving dys-albumose 
undissolved. Dialysis of the saline solution precipitates hetero-albumose, 
leaving proto-albumose in solution. It is probable however, that hetero- and 
dys-albumose are identical, or that the former is merely an insoluble form of 
the latter. The albumoses are bodies intermediate between albumins and pep- 
tones, and of the three, deutero-albumose is nearest to peptones. An import- 
ant character is that they do not dialyze or diffuse readily. The albumoses also 
are produced by the activity of many micro-organisms and doubtless play an 
important part in many pathological processes (§ 249).] 
[Properties of the Albumoses.—Proto-albumose is soluble in distilled water, is not 
changed by heat, but is precipitated by saturation of the solution with sodic chloride, by HNOs, 
acetic acid and potassic ferrocyanide, copper sulphate, mercuric chloride. Deutero-albumose 
is very like the foregoing, but it is not precipitated by HN03 or on adding sodic chloride to 
saturation, but precipitation occurs when 20 to 30 per cent, of acetic acid is added. Hetero- 
albumose resembles a globulin in its properties; it is insoluble in distilled water, but is solu- 
ble in saline solutions (io to 15 per cent.), and is partly precipitated from its solution by satura- 
tion with NaCl or by dialysis, it is coagulated by heat. All give the rosy-pink color with the 
biuret-reaction, and they are all precipitated by saturation with neutral ammonia sulphate, which 
peptones are not (Kiihne and Chittenden).] See also $ 249. 
[Globuloses from the globulin of ox-serum are obtained in the same way, although the fer- 
ment has much less action on globulin than on albumin. Speaking generally, they resemble the 
albumoses.] 
By the continued action of the gastric juice, the pro-peptone passes into a 
true soluble peptone. The unchanged albumin behaves like an anhydride 
with respect to the peptone. The formation of peptone is due to the taking 
up of a molecule of water, under the influence of the hydrolytic ferment Sec. 166.] 
THE PRODUCTS OF GASTRIC DIGESTION. 
303 
pepsin, and the action takes place most readily at the temperature of the body. 
Gelatin is changed into a gelatinpeptone. 
[Method of separating the products of gastric digestion.—If fibrin 
or white of egg be digested for some time with gastric juice, these proteids will 
ultimately be dissolved. Neutralize the digest with sodic carbonate and a 
greater or less precipitate of para-peptones will be obtained. Filter. The 
filtrate contains other digested proteids. Saturate it with crystals of neutral 
ammonium sulphate, which will precipitate the albumoses ; filter these off, 
and the solution still contains peptone, which can be precipitated by much 
alcohol. Ammonium sulphate precipitates all soluble proteids except peptones.] 
According to Kiihne, the proteid molecule contains two preformed substances in its composi- 
tion : anti-albumin and hemi-albumin. Gastric juice at first converts them into anti-albu- 
mose and hemi-albumose, and ultimately the former is converted into anti-peptone and the 
latter into hemi-peptone 170, II.). Only the latter is capable of being split up by trypsin 
into leucin and tyrosin by the action of the pancreatic juice (f 249). 
[The following scheme represents the results :— 
Action of Enzymes (ferments). 
Action of pepsin. 
Albumin. 
Action of trypsin. 
Anti-albumose. 
Hemi-albumose. 
Anti-peptone. 
Anti-peptone. 
i 
Hemi-peptone. 
Hemi-peptone. 
I . .1 
Leucin, Tyrosin, etc. 
Leucin, 
I 
Tyrosin, etc.] 
The greater the amount of pepsin (within certain limits), the more rapidly 
does the solution take place. The pepsin suffers scarcely any change, and if 
care be taken to renew the hydrochloric acid, so as to keep it at a uniform 
amount, the pepsin can dissolve new quantities of albumin. Still, it seems 
that some pepsin is used up in the process of digestion (Grutzner). Proteids 
are introduced into the stomach either in a solid (coagulated) or fluid con- 
dition. Casein alone of the fluid forms is precipitated or coagulated, and after- 
wards dissolved. The non-coagulated proteids are transformed into syntonin, 
without being previously coagulated, and are then changed into pro-peptone 
and directly peptonized, i. <?., actually dissolved. 
When albumin is digested by pepsin at the temperature of the body, a not inconsiderable 
amount of heat disappears, as can be proved by calorimetric experiment (Maly). Hence, the 
temperature of the chyme in the stomach falls o°.2 to o°.6 C. in two to three hours (v. Vintschgau 
and Dietl). 
Coagulated albumin may be regarded as the anhydride of the fluid form, and 
the latter again as the anhydride of peptone. The peptones, therefore, represent 
the highest degree of hydration of the .proteids. 
Hence, peptones may be formed from proteids by those reagents which usually cause hydra- 
tion, viz., treatment with strong acids (from fibrin, with 0.2 HC1), caustic alkalies, putrefactive 
and various other ferments, and ozone. 
The anhydride proteid has been prepared from the hydrated form. Henni- 
ger and Hofmeister, by boiling pure peptone with dehydrating substances 
(anhydrous acetic acid at 8o° C.), have succeeded in decomposing it into a 
body resembling syntonin. 
Peptones.—(x) They are completely soluble in water. (2) They diffuse 
very easily through animal membranes. (3) They filter quite easily through 
the pores of animal membranes. (4) They are not precipitated by boiling, nitric THE PROPERTIES OF PEPTONES. 
[Sec. 166. 
acid, acetic acid and potassium ferrocyanide, acetic acid and saturation with com- 
mon salt. (5) They are precipitated from neutral or feebly acid solutions by 
mercuric chloride, tannic acid, bile acids, and phospho-molybdic acid. (6) 
With Millon’s reagent they react like proteids, and give a red color, and with 
nitric acid give the yellow xantho-protein reaction. (7) With caustic potash 
or soda and a small quantity of cupric sulphate [or Fehling’s solution], they 
give a beautiful rosy-red color, the biuret-reaction. (8) They rotate the plane 
of polarized light to the left. 
[Kiihne and Chittenden, making use of the fact that ammonium sulphate to 
saturation precipitates all proteids from solution except peptone, have reinvesti- 
gated the subject, and they find that many of the peptones of commerce con- 
tain albumoses. Pure peptone has remarkable properties. When dissolved in 
water, it hisses and froths like phosphoric anhydride, heat is evolved, and a 
brown solution is formed. It is difficult to preserve it. It is not precipitated 
by NaCl, or NaCl and acetic acid, but is completely precipitated by phospho- 
tungstic and phospho-molybdic acids, tannin, iodo-mercuric iodide, picric acid. 
Peptones have a cheesy taste, while albumin and albumoses are tasteless.] 
The biuret-reaction is obtained with hemi-albumose, as well as with a form of albumin, which 
is formed during artificial digestion and is soluble in alcohol. It is called “ alkophyr ” by 
Briicke. [Darby’s fluid-meat gives all the above reactions, and is very useful for studying the 
tests for peptones.] 
The rapidity of solution of fibrin is tested by placing fibrin, which is swollen up by the 
action of 0.2 per cent. HC1 in a glass funnel, and adding the digestive fluid, observing the 
rapidity with which the fluid, the altered fibrin, drops from the funnel, and the fibrin disappears 
{Grilnhagen). Or the fibrin may be colored with carmine, swollen up in o.l per cent. HC1, and 
placed in the digestive fluid. The more rapidly the fluid is colored red, the more energetic is the 
digestion. 
Preparation.—Pure peptones are prepared by taking fluid which contains them and 
neutralizing it with barium carbonate, evaporating upon a water-bath, and filtering. The 
barium is removed from the filtrate by the careful addition of sulphuric acid, and subsequent 
filtration. 
Ptomaines.—Brieger extracted from gastric peptones by amylic alcohol a peptone-free 
poison, with actions like those of curare. It belongs to the group of ptomaines, i. <?., alkaloids 
obtained from dead bodies or decomposing proteids. [Ptomaines are identical with the alka- 
loids in plants, and many have been isolated. The term leucomaine has been applied by 
Gautier to alkaloids formed by the decomposition of albuminous bodies during the normal 
metabolic processes taking place in the tissues. They are not formed by the activity of micro- 
organisms. Some seem to be formed in muscle, and are closely allied to creatin and xanthin 
(S 250, IV).] 
Peptones are undoubtedly those modifications of albumin or proteids which, 
after their absorption from the intestinal canal into the blood, are destined to 
make good the proteids used up in the human organism. [It is important to 
note, however, that peptones are not found in the blood. They seem to be 
reconverted into some other proteid as they pass through the mucous mem- 
brane of the intestine towards the blood (§ 192).] By giving peptones (instead 
of albumin) as food, life can not only be maintained, but there may even be an 
increase of the body-weight (Plosz and Maly, Adamkiewicz). Very probably, 
before being actually absorbed into the blood-stream, peptones are retrans- 
formed into serum-albumin or some closely allied body (§ 192). 
Conditions affecting Gastric Digestion.—The presence of peptones already formed 
interferes with the action of the gastric juice, in so far as the greater concentration of the fluid 
interferes with and limits the mobility of the fluid particles. Boiling, concentrated acids, alum, 
and tannic acid, alkalinity of the gastric juice (e. g., by the admixture of much saliva), abolish 
the action; also sulphurous and arsenious acids and potassic iodide. The salts of the heavy 
metals, which cause precipitates with pepsin, peptone, and mucin, interfere with gastric digestion, 
and so do concentrated solutions of alkaline salts, common salt, magnesium and sodium sul- 
phates. A small quantity of NaCl increases the secretion (Griitzner) and favors the action of 
pepsin. Alkalies rapidly destroy pepsin, but less rapidly pro-pepsin (Langley). Alcohol pre- Sec. 166.] 
ARTIFICIAL AND NATURAL DIGESTION. 
305 
cipitates the pepsin, but by the subsequent addition of water it is redissolved, so that digestion 
goes on as before. Any means that prevent the proteid bodies from swelling up, as by binding 
them firmly, impede digestion. Slightly over half a pint of cold-water does not seem to disturb 
healthy digestion, but it does so in cases of disease of the stomach. Copious draughts of water, 
and violent muscular exercise, disturb digestion; while warm clothing, especially over the pit of 
the stomach, aids it. Menstruation retards gastric digestion. [Oddi finds that the presence 
of large quantities of ox bile, or even of its own bile in the stomach of a dog, does not affect 
the activity of the gastric juice, does not precipitate peptones, and does not excite vomiting 
(2186).] 
[Artificial Digestion.—The action of gastric juice on proteids may be 
observed outside the body, and we can prove, as is shown in the following 
table, after Rutherford, that pepsin and an acid—e. g., hydrochloric, along with 
water—are essential to the formation of gastric peptones : — 
Beaker A. 
Beaker B. 
Beaker C. 
Water. 
Water. 
Water. 
Pepsin, 0.3 per cent. 
Fibrin. 
HC1, 0.2 per cent. 
Fibrin. 
Pepsin, 0.3 per cent. 
HC1, 0.2 
Fibrin. 
Keep all in'water-bath at 38° C. 
Unchanged. 
Fibrin swells up, becomes clear, and is 
changed into acid-albumin or syntonin. 
Fibrin ultimately changed 
into peptone.] 
[In all animals, gastric digestion is essentially an acid digestion, and 
between the native proteid—fibrin, albumin, or any other form of proteid— 
and the end-product peptone there are numerous intermediate substances— 
proteoses—the properties and characters of many of which have still to be 
investigated.] 
[Natural versus Artificial Digestion.—It is to be remembered that there is a very great 
difference between natural and artificial digestion. In the former, the gastric juice is secreted 
all the time the food is present in the stomach, so that there is a favorable proportion of acid and 
ferment. Moreover, the movements of the stomach thoroughly mix the food with the digestive 
juice. The peptones are absorbed as they are formed or pass into the duodenum, so that they 
do not accumulate in the mixture and retard the process of digestion, as is the case in artificial 
digestion. It is obvious that as ordinarily conducted artificial digestion differs from normal 
digestion, e.g., in the stomach, in the want of the following factors—the absence of (i) constant 
movements of the contents; (2) constant removal of the digestive products; and (3) continuous 
addition of fresh supply of digestive juice.] 
[Kronecker and his pupils, Brink and Popoff, state that the gastric and intestinal mucous 
membrane can change gastric peptones into serum-albumin. The frog’s heart can do the same, 
but much more slowly. The test applied for the conversion of peptone into serum-albumin was 
perfusion through the excised amphibian heart, which Kronecker regards as a very sensitive test 
for serum-albumin. A solution of peptone—which acts injuriously on the heart—when intro- 
duced into the stomach, or better, the intestine, of a dog, and then perfused through the heart, 
restores the latter after it has been exhausted by perfusion of normal saline.] 
[Exclusion of the Stomach.—Ogata finds that if the stomach be divided at the pyloric end 
so as to exclude the stomach from the digestive apparatus, a dog can be nourished for a long time 
by introducing food through the pylorus into the duodenum. A dog has lived several years after 
excision of its stomach (Czerny). Raw flesh so introduced is digested more rapidly in the 
small intestine than in the stomach. The stomach not only digests, but it acts on the connective 
tissue of flesh so as to prepare the latter for intestinal digestion.] 
II. Action on other Constituents of Food.—Milk coagulates or 
curdles when it enters the stomach, owing to the precipitation of the casein, 
and in doing so it entangles some of the milk-globules. [The curd is after- 
wards dissolved and digested by the gastric juice.] During the process of coagu- 
lation, heat is given off. The free hydrochloric acid of the gastric juice is 
itself sufficient to precipitate it; the acid removes from the alkali-albuminate 306 
DIGESTION OF MILK AND ALBUMINOIDS. 
[Sec. 166. 
or casein the alkali which keeps it in solution. Hammarsten separated a special 
ferment from the gastric juice—quite distinct from pepsin—the milk-curdling 
ferment, which, quite independently of the acid, precipitates the casein either 
in neutral or alkaline solutions. It is this ferment, or rennet, or rennin, 
which is used to coagulate casein in the making of cheese. [Rennin can 
curdle milk in a neutral solution, and neutralized gastric juice can do so also. 
The action of rennin is most active about 40° C., and its curdling action is 
destroyed by boiling.] Rennet is formed from a mother-substance in the chief 
cells of the gastric glands (p. 299). [Rennet is an infusion of the fourth 
stomach of the calf in brine (§ 231). The ferment which coagulates milk is 
quite distinct from pepsin. If magnesic carbonate be added to an infusion of 
calf’s stomach, a precipitate is obtained. The clear fluid has strongly coagu- 
lating properties, while the precipitate is strongly peptic.] 
The action of the milk-curdling ferment is perhaps, like the action of all ferments, a hydration 
of casein; it is greater in the presence of 0.2 HC1. 
One part of the rennet-ferment can precipitate 800,000 parts of casein. When casein coagu- 
lates, two new proteidsseem to be formed—the coagulated proteid which constitutes cheese, and 
a body resembling peptone dissolved in the whey—whey-proteid. The addition of calcium chlo- 
ride accelerates, while water retards the coagulation 231) (Hammarsten). [A ferment similar 
to rennet is contained in the seeds of Withania coagulans (S. Lea).] 
Casein is first precipitated in the stomach, then a body like syntonin is formed, and finally pep- 
tone. During the process, a substance containing phosphorus and resembling nuclein appears 
(Lubavin). 
[Action of Acids versus Rennin on Milk.—If a dilute acid be added to 
milk the casein is precipitated as such and not as a curd. It may even be re- 
dissolved and curdled with rennin. Casein may also be precipitated unchanged 
by neutral salts (NaCl, MgS04). The precipitate when washed can be redis- 
solved in water in the presence of calcic phosphate, and this solution is coagu- 
lated by rennin. When casein is curdled by rennin, however, the casein is 
split up into two proteids—an insoluble one forming the curd, and a soluble 
one allied to albumin. The curdling of milk therefore seems to be due to the 
splitting up of a complex proteid by a ferment; one of the proteids is soluble, and 
closely allied to albumin—whey-proteid—the other is insoluble, and forms the 
curd ; but this reaction will not take place—at least an insoluble curd will not 
be formed—if calcic phosphate be entirely absent. We are reminded of the 
analogous case of the coagulation of blood produced by the splitting up of 
fibrinogen in the presence of neutral salts.] 
[Much confusion has existed regarding the terminology of the proteids in milk ($ 231). The 
chief proteid in milk, by some called casein, exists in milk partly dissolved and partly in suspen- 
sion. The curd precipitated by rennin is quite insoluble in the whey. Some apply the term 
casein to the proteid which is present in milk, and curd to the insoluble casein produced by the 
ferment action of rennet. Halliburton proposes to call the proteid in milk caseinogen, and that 
which composes the curd casein. Foster calls the latter tyrein.] 
There is a “ lactic acid ferment ” also present in gastric juice, which changes 
milk-sugar into lactic acid (.Hammarsten). Part of the milk-sugar is changed in 
the stomach and intestine into grape-sugar. 
Action on Carbohydrates.—Gastric juice does not act as a solvent of 
starch, inulin, or gums. Cane-sugar is slowly changed into grape-sugar. Ac- 
cording to Uffelmann, the gastric mucus, and according to Leube, the gastric 
acid, are the chief agents in this process. 
Action on Albuminoids and Fats.—During the digestion of true car- 
tilage, there is formed a chondrin-peptone, and a body which gives the sugar- 
reaction with Trommer’s test. Perfectly pure elastin yields an elastin-peptone, 
similar to albumin-peptone, and hemi-elastin similar to hemi-albumose. A 
very minute quantity of fat is broken up into glycerin and fatty acids. [On Sec. 166.] 
WHY THE STOMACH DOES NOT DIGEST ITSELF. 
307 
neutral olive-oil being injected into the stomach of a dog, after several hours— 
the pylorus being plugged with an elastic bag—it partly splits up and yields 
oleic acid (Cash and Ogata).'] 
[We still require further observations on the gastric digestion of fats. Richet observed in his 
case of fistula, that fatty matters remained a long time in the stomach, and Ludwig found the 
same result in the dog. In some dyspeptics, rancid eructations often take place towards the end 
of gastric digestion.] 
III. Action on the various Tissues.—(i) The gelatin-yielding substance (collagen) of 
all the connective-tissues (connective-tissue, white fibro-cartilage, and the matrix of bone), as 
well as glutin, is dissolved and peptonized by the gastric juice. [Gelatin, when acted on by 
gastric juice, no longer solidifies in the cold, but a gelatin peptone is formed, which is soluble 
and diffusible, although it differs from true peptone. In the dog, connective tissues are specially 
acted on in the stomach, while the other parts of organs used as food are prepared for digestion 
in the small intestine, where the cellular and nuclear elements are digested by the pancreatic 
juice (Bikfalvi).] (2) The structureless membranes (membranae propriae) of glands, sarco- 
lemma, Schwann’s sheath of nerve-fibres, capsule of the lens, the elastic laminae of the cornea, 
the membranes of fat-cells are dissolved, but the true elastic (fenestrated) membranes and fibres 
are not affected. (3) Striped muscle, after solution of the sarcolemma, breaks up transversely 
into discs, and, like non-striped muscle, is dissolved, and forms a true soluble peptone, but parts 
of the muscle always pass into the intestine. (4) The albuminous constituents of the soft cellular 
elements of glands, stratified epithelium, endothelium, and lymph-cells, form peptones, but the 
nuclein of the nuclei does not seem to be dissolved. (5) The horny parts of the epidermis, 
nails, hair, as well as chitin, silk, conchiolin, and spongin of the lower animals, are indigestible, 
and so are amyloid-substance and wax. (6) The red blood-corpuscles are dissolved, the 
haemoglobin decomposed into haematin and a globulin-like substance; the latter is peptonized, 
while the former remains unchanged, and is partly absorbed and transformed into-biie-pigment. 
Fibrin is easily dissolved to form hemi- and anti-peptone. (7) Mucin, which is also secreted 
by the goblet-cells of the stomach, passes through the intestines unchanged. (8) Vegetable 
fats are not affected by the gastric juice. Vegetable cells yield their protoplasmic contents to 
form peptones, while the cellulose of the cell-wall, in the case of man at least, remains undi- 
gested (\ 184). [(9) On gluten-casein, the chief proteid obtainable from wheaten flour or 
bread, artificial gastric juice yields soluble products or proteoses, or gluten-caseoses—which bear 
the same relation to the mother-substance as the albumosesof fibrin or albumin do to the mother- 
proteid. There is no essential difference in the general character of the proteids in this case 
between the animal and vegetable proteid. (Chittenden and Smith).] 
Why the Stomach does not digest itself.—That the stomach can digest living things is 
shown by the following facts: Bernard introduced the leg of a living frog through a 
gastric fistula in the stomach of a dog. Pavy did the same with the ear of a rabbit, and in 
both cases the objects introduced were digested. [Frenzel has modified this experiment, and 
shown that the legs of a living frog are digested by artificial gastric juice, the tissues being first 
killed and then digested. His experiments go to show that the alkalinity of the blood is not 
the protective medium.] The margins of a gastric ulcer and of gastric fistulas in man are 
attacked by the gastric juice. John Hunter (1772) discussed the question why the stomach 
does not digest itself. Not unfrequently after death the posterior wall of the stomach is found 
digested, [more especially if the person die after a full meal and the body be kept in a warm 
place, whereby the contents of the stomach may escape into the peritoneum. Cl. Bernard showed 
that if a rabbit be killed and placed in an oven at the temperature of the body, the walls of the 
stomach are attacked by its own gastric juice. Fishes also are frequently found with their stom- 
ach partially digested after death]. It would seem therefore, that, so long as the circulation 
continues, the tissues are protected from the action of the acid by the alkaline blood; this action 
cannot take place if the reaction be alkaline (Pavy). [This, however, does not explain why the 
pancreatic juice does not digest the pancreas.] Ligature of the arteries of the stomach causes 
digestive softening of the gastric mucous membrane. The thick layer of mucus may also aid in 
protecting the stomach from the action of its own gastric juice (Cl. Bernard). [Viola and Gas- 
pardi find that if the spleen, with its circulation still intact, be introduced through a gastric fistula 
into the stomach of a dog, it is not digested even after 40 hours, but if the circulation was 
stopped it was reduced to a pulp in 8 hours. Here there is no question of the existence of col- 
umnar epithelium and a coating of mucus.] 
[Comparative.—The process of gastric digestion seems to be essentially the same in all classes 
of vertebrates, with this exception, that while the gastric juice of mammals and birds is not active 
at o° C., that of cold-blooded animals is, although the optimum of the latter is 20° C. In the 
human fcetus pepsin is formed shortly before birth, and apcording to Hammarsten, in the rabbit it 
is formed in the last week of intra-uterine life, and in the dog in the third week after birth. The 
formation of acid takes place much sooner.] 308 
STRUCTURE OF THE PANCREAS. 
[Sec. 167. 
167. GASES IN THE STOMACH.—T he stomach always contains 
a certain quantity of gas, derived partly from the gases swallowed with the 
saliva, partly from gases which pass backwards from the duodenum. 
The air in the stomach is constantly undergoing changes, whereby its O is 
absorbed by the blood, and for 1 vol. of O absorbed 2 vols. of C02 are returned 
to the stomach from the blood. Hence, the amount of O in the stomach is 
very small, the C02 very considerable (Planer). 
Gases in the Stomach.—Vol. per cent. (Planer.) 
Human Subject after Vegetable Diet. 
Dog. 
I. 
11. 
I. 
After Animal Diet. 
II. 
After Legumes. 
co2, 
20.79 
33-83 
25.2 
32.9 
H, . 
.... 6.71 
27-58 
N, . 
72.50 
38.22 
68.7 
66.3 
0, . 
0-37 
6.1 
0.8 
By the acid of the stomach a part of the C02 is set free from the saliva, which 
contains much C02 (§ 146). The N acts as an indifferent substance. 
Abnormal development of gases in persons suffering from gastric catarrh occurs when the 
gastric contents are neutral in reaction; during the butyric acid fermentation H and C02 are 
formed; the acetic acid and lactic acid fermentations do not cause the formation of gases. 
Marsh-gas (CH4) has been found, but it comes from the intestine, as it can only be formed when 
no O is present (§ 184). 
168. Structure of the Pancreas.—[The pancreas is a long, narrow, com- 
pound tubular gland of a cream color and soft texture, which lies across the 
posterior wall of the abdomen behind the stomach and opposite the first lum- 
bar vertebra (fig. 219). It is about 18 cm. long, 4 cm. broad, and 1.5 cm. 
thick, and weighs about 75 grams. The broader end or head lies in, and is- 
embraced by, the curvature of the duodenum, and the narrow end or tail is in 
Pancreas and duodenum removed from the body, and seen from behind. The gland is cut 
to show the ducts. 
Fig. 219. 
contact with the spleen. The duct—duct of Wirsung—is about 2-3 mm. 
in diameter, runs along the whole length of the gland, and in its course it 
receives nearly at right angles contributory small ducts from the different 
lobules of the gland. It opens, along with the common bile-duct, into the 
duodenum, piercing the coats of the latter obliquely about 8 to 10 cm. below 
the pylorus. In man there is a small accessory duct—the duct of Santorini 
—opening independently into the duodenum. The gland has a thin con- Sec. 168.] 
STRUCTURE OF THE PANCREAS. 
nective-tissue capsule which sends a fine process and septa between its lobules, 
and these septa carry into it the blood-vessels and nerves. The duct consists 
of connective-tissue, and is lined by a single layer of non-striated columnar or 
cylindrical cells. When traced backwards the ducts open into intermediate or 
intercalary parts lined by flattened epithelium, while the intercalary parts open 
into the acini.] 
The pancreas is a compound tubular gland, and in its general arrange- 
ment into lobes, lobules, and system of ducts and acini, it corresponds 
exactly to the true salivary glands (§ 142). The single layer of cylindrical 
epithelial cells lining the ducts is not at all, or only faintly, striated. The 
acini are tubular, or flask-shaped, and often convoluted. They consist of a 
membrana propria, resembling that of the salivary glands, lined by a single 
layer of somewhat cylindrical cells, with a more or less conical apex, directed 
towards the very narrow lumen of the acini. [As in the salivary glands, there 
is a narrow intermediary part of the ducts opening into the acini, and lined 
by flattened epithelium. The acini are larger and more tubular than those of 
the salivary gland, and moreover, the acini are more numerous, so that in a 
section far fewer ducts are seen.] 
The cells lining the acini consist of two zones (fig. 220): (1) The smaller 
outer or parietal zone in each cell is transparent, homogeneous, sometimes 
Section of the acini of fresh pancreas, show- 
ing the small lumen of the acini and the 
granular inner zone in the cells lining the 
acini. 
Fig. 220. 
Section of a pancreas stained with picro-carmine. 
D, duct; C, capsule; A, acinus (Stirling). 
Fig. 221. 
faintly striated, and readily stained with carmine and logwood ; and (2) the 
inner zone (Bernard’s granular layer) is granular, and stains but slightly with 
carmine (figs. 221, 222). [This inner zone contains a large number of more 
or less refractive granules depending on the state of physiological activity of 
the gland (fig. 222).] It undoubtedly contributes to the secretion by giving 
off material, the granules being dissolved, while the zone itself becomes smaller. 
The spherical nucleus lies between the two zones. [The lumen of the acini is 
very small, and spindle-shaped or branched cells (centro-acinar cells) lie in 
it, and send their processes between the secretory cells, thus acting as support- 
ing cells for the elements of the wall of the acini. During secretion there is a 
continuous change in the appearance of the cell-substance; the granules of the 
inner zone dissolve to .form part of the secretion ; new granules are formed in 
the homogeneous substance of the outer zone, and pass towards the inner zone 
(.Heidenhain, Kiihne, and Lea).] 
[Changes in the Cells during Digestion.—When the cells are examined in the fresh con- 
dition, during the resting phase, or when the cells are “ loaded,” they contain throughout their 
substance a large number of refractive “ granules” or spherules, which may obscure the nucleus. 310 
STRUCTURE OF THE PANCREAS. 
[Sec. 168. 
In the active phase, or in a “ discharged ” cell, the granules are far less numerous, they have 
disappeared from the outer zone of the cell, and are confined to its inner zone, and the relative 
width of the clear more or less homogeneous outer zone and that of the inner granular zone 
depends upon the activity of the cells, and the greater the activity the fewer the granules in the 
inner zone. There is a close resemblance between the condition of the pancreatic cells and 
those of the serous salivary glands.] According to Heidenhain, during the first stage (6 to io 
hours) the granular inner zone diminishes in size, the granules disappear, while the striated 
outer zone increases in size (fig. 222, 2). In the second stage (10 to 20 hours) the inner zone is 
greatly enlarged and granular, while the outer zone is small (fig. 222, 3). During hunger the 
outer zone again enlarges (fig. 222, 1). In a gland where paralytic secretion takes place, 
the gland is much diminished in size, the cells are shrivelled (fig. 222, 4) and greatly changed. 
According to Ogata, some cells actually disappear during secretion (Langley). 
The axially-placed excretory duct consists of an inner thick and an outer 
loose wall of connective and elastic tissues, lined by a single layer of columnar 
epithelium. Small mucous glands lie in the largest trunks. Non-medullated 
nerves with ganglia in 
their course, pass to the 
acini, but their mode of 
termination is unknown. 
[The nerves come from 
the semilunar ganglion 
along the splenic, gastro- 
duodenal and superior 
mesenteric arteries.] 
The blood-vessels 
form a rich capillary 
plexus round some acini, while round others there are very few. [It receives 
blood from several arteries (splenic, pancreatico-duodenal, and superior 
mesenteric), and its blood is returned to the portal system by the splenic and 
superior mesenteric veins.] Kiihne and Lea found peculiar small cells in 
groups between the alveoli, and supplied with convoluted capillaries like glo- 
meruli. Their significance is entirely unknown. 
[They are probably lymphatic in their nature.] 
The lymphatics resemble those of the salivary 
glands. [They begin as peri-vascular and peri- 
acinar spaces, and open into two lymphatic glands 
lying on the superior mesenteric artery. When a 
colored injection is forced into the ducts under a 
high pressure, fine intercellular passages between 
the secreting cells are formed {SaviottVs canals), but 
they are artificial products.] 
[Number of Ducts.—In making experiments upon the 
pancreatic secretion, it is important to remember that the num- 
ber of pancreatic ducts varies in different animals. In man 
there is one duct opening along with the common bile-duct at 
Vater’s ampulla, at the junction of the middle and lowest third 
of the duodenum. The rabbit has two ducts, the larger open- 
ing separately about 14 inches (30 to 35 cm.) below the en- 
trance of the bile-duct (fig. 223). The dog and cat have each 
two ducts opening separately.] 
Chemistry.—The fresh pancreas contains water, proteids, 
ferments, fats, and salts. In a gland which has been exposed 
for some time, much leucin, isoleucin, butalin, tyrosin, often 
xanthin and guanin, are found; lactic and fatty acids seem to 
be formed from chemical decompositions taking place. 
169. THE PANCREATIC JUICE.—Method.—Regner de Graaf 
(1664) tied a cannula in the pancreatic duct of a dog, and collected the juice in 
Changes of the pancreatic cells in various stages of activity, 
i, During hunger; 2, in the first stage of digestion; 3, in the 
second stage ; 4, during paralytic secretion. 
Fig. 222. 
Fig. 223. 
Pancreas of the rabbit P; pd, 
pancreatic duct; d, d, duo- 
denum ; Py, pylorus; S, 
stomach; GB, gall-bladder; 
BD, bile-duct. Sec. 169.] 
COMPOSITION OF THE PANCREATIC JUICE. 
311 
a small bag. Other experimenters made a temporary fistula. To make a 
permanent fistula, the abdomen is opened (dog), the pancreatic duct pulled 
forward, and stitched to the abdominal wall, with which it unites. Heidenhain 
cuts out the part of the duodenum where the duct opens into it, from its con- 
tinuity with the intestine, and fixes it outside the abdominal wound. 
The secretion obtained from a permanent fistula is a copious, slightly 
active, watery secretion, containing much sodium carbonate. The thick fluid 
obtained from the fistula before inflammation sets in, or that from a temporary 
fistula, acts far more energetically. This thick secretion, which is small in 
amount, is the normal secretion. The copious watery secretion is, perhaps, 
caused by the increased transudation from the dilated blood-vessels (possibly in 
consequence of the paralysis of the vaso-motor nerves). It is, therefore, in a 
certain sense, a “paralytic secretion” (§ 145). The quantity varies much, 
according as the fluid is thick or thin. During digestion, a large dog secretes 
1 to 1.5 gram, of a thick secretion (C/. Bernard). Bidder and Schmidt 
obtained in twenty-four hours 35 to 117 grams of a watery secretion per kilo, 
of a dog. When the gland is not secreting, and is at rest, it is soft, and of a 
pale yellowish-red color, but during secretion it is red and turgid with blood, 
owing to the dilatation of the blood-vessels. [It is to be remembered that most 
of the experiments have been made in the pancreatic juice of the dog.] 
Physical and Chemical Characters of the Secretion.—The normal 
secretion is thick, transparent, colorless, odorless, saltish to the taste, and has 
a strong alkaline reaction, owing to the presence of sodium carbonate, so that 
when an acid is added, C02 is given off. It contains several groups of sub- 
stances—(1) serum-albumin and alkali-albuminate; it is sticky, somewhat 
viscid, flows with difficulty, and is coagulated by heat into a white mass. In 
the cold, there separates a jelly-like albuminous coagulum. Nitric, hydro- 
chloric, and sulphuric acids cause a precipitate ; while the precipitate caused 
by alcohol is redissolved by water. (2) Several ferments (p. 312) ; (3) Nitro- 
genous bodies, e. g., leucin, guanin, etc., in small amount; (4) Traces of soaps; 
(5) Salts, less than 1 per cent. Cl. Bernard found in the normal pancreatic 
juice of a dog 8.2 per cent, of organic substances, and 0.8 per cent, of ash. 
The juice (dog) analyzed by Carl Schmidt contained in 1000 parts :— 
Collected on first opening 
Water, 
the duct. 
900.8 
Permanent Fistula. 
979.0 
Solids, 
99-2 
20.0 
Solids j 
Organic Matter, 
90.4 
12.4 
Inorganic “ 
, 8.8 
7.6 
The ash from 1000 parts of juice yielded— 
Soda, 
3-32 
Sodic chloride, 
2.50 
Potassic chloride, 
, 0.02 
0-93 
Phosphates of alkaline earths and iron, 
0-53 
0-08 
Sodic phosphate, 
0.01 
Lime and magnesia, 
0.01 
The more rapid and more profuse the secretion, the poorer it is in organic substances, while 
theTnorganic remain almost the same; nevertheless, the total quantity of solids is greater than 
when the quantity secreted is small (Bernstein). Traces of leucin and soaps are present in 
the fresh juice. [It usually contains few or no structural elements. Any structural elements 
present in the fresh juice, as well as its proteids, are digested by the peptone-forming ferment of 
the juice, especially if the latter be kept for some time. If the fresh juice is allowed to stand 
for some time, and then mixed with chlorine water, a red color is obtained.] 
Concretions are rarely formed in the pancreatic ducts; they usually consist of calcic carbonate. 
Dextrose has been found in the juice in diabetes, and urea in jaundice. Schiff’s statement that [Sec. 169. 
312 
ACTIONS OF THE PANCREATIC JUICE. 
the pancreas secretes only after the absorption of dextrin has not been confirmed. The secretory 
activity of the pancreas is not dependent on the presence of the spleen. 
[Comparative.—The pancreatic juice of the dog contains about io per 
cent, of solids; of these 9 is organic, 1 mineral. In other animals, however, 
the percentage of solids is much less; in the sheep 2.15, and rabbit 1.76. 
Herter found over 20 per cent, of solids in the fluid accumulated in a human 
dilated pancreatic duct. In many fishes the pancreatic juice is acid, and does 
not contain any diastatic ferment. In molluscs and arthropoda there is a fer- 
ment analogous to trypsin. The secretion is intermittent in carnivora and 
continuous in herbivora.] 
170. ACTIONS OF THE PANCREATIC JUICE.—The presence 
of four enzymes, or hydrolytic ferments, makes the pancreatic juice one 
of the most important digestive fluids in the body. 
I. Its diastatic action is due to the diastatic ferment amylopsin, a sub- 
stance which seems to be identical with the saliva ferment; but it acts much 
more energetically than the ptyalin of saliva on raw starch as well as upon 
boiled starch ; at the temperature of the body the change is effected almost at 
once, while it takes place more slowly at a low temperature, maltose being 
formed. Glycogen is changed into dextrin and grape sugar ; and achroodextrin 
into sugar. Even cellulose is said to be dissolved, and gum changed into sugar 
by it, but inulin remains unchanged. 
[If digestion of starch by pancreatic juice or saliva be carried on under con- 
ditions approximating as nearly as possible to those existing in the intestine, 
nearly the whole of the starch may be converted into maltose, there being but 
little dextrin left at the end of a prolonged digestion. The presence of the 
maltose seems to prevent the further conversion of the small remainder of 
dextrin into sugar (Sheridan Lea'). Sugar seems to be the final form in which 
the products of digestion of carbohydrates leave the intestine and pass into the 
blood.] 
According to v. Mering and Musculus, the starch (as in the case of the saliva, § 148) is 
changed into maltose, and a reducing-dextrin; so also is glycogen. Amylopsin changes 
achroodextrin into maltose; at 40° C. maltose is slowly changed into dextrose, but cane-sugar 
is not changed into invert-sugar. The ferment is precipitated by alcohol, while it is extracted by 
glycerin without undergoing any essential change. All conditions which destroy the diastatic 
action of saliva ($ 148) similarly affect its action, but the admixture with acid gastric juice (its 
acid being neutralized) or bile does not seem to have any injurious influence. This ferment is 
absent from the pancreas of new-born children (Korowin). 
Preparation of the Ferment.—It is isolated by the same methods as obtain for ptyalin 
(£ 148), but the tryptic ferment is precipitated at the same time. The addition of neutral salts 
(4 per cent, solution), e. g., potassium nitrate, common salt, ammonium chloride, increases the 
diastatic action. 
II. Its tryptic or proteolytic action, or its action on' proteids, depends upon 
the presence of a hydrolytic ferment which is now termed trypsin (Kiihne). 
Trypsin acts upon proteids at the temperature of the body, when the reaction is 
alkaline, and changes them first into a globulin-like substance, then into pro- 
peptone or albumose, and lastly into a true peptone, sometimes called tryptone. 
The albumoses are not so abundant or so easily separated as in gastric digestion 
(see also p. 302) ; [as in gastric digestion the peptones formed are hemi-pep- 
tone and anti-peptone, but the former alone undergoes further change when 
it is acted on by the pancreatic juice]. The proteids do not swell up before 
they are changed into peptone, [but they are eroded or eaten away by the action 
of the juice]. When the proteid has been previously swollen up by the action 
of an acid, or when the reaction of the medium is acid, the transformation is 
interfered with, although the changes go on slowly in a neutral medium. 
Substances yielding gelatin, nuclein (?), and Hb, resist trypsin ; glutin and swollen-up gelatin- Sec. 170.] 
TRYPSIN AND TRYPTIC DIGESTION. 
313 
yielding substances are changed into gelatin-peptone, but the latter undergoes no further change. 
Hb-02 is split up into albumin and hsemochromogen. In other respects, trypsin acts on tissues 
containing albumins just like pepsin (§ 166, III). 
Trypsin is never absent from the pancreas of new-born children (Zweifel), and it may be 
extracted by water, which, however, also dissolves the albumin. Kiihne has carefully separated 
the albumin and obtained the ferment in a pure state. It is soluble in water, insoluble in 
alcohol. Pepsin and hydrochloric acid together act upon trypsin and destroy it; hence it is 
not advisible to administer trypsin by the mouth, as it would be destroyed in the stomach. 
When dried it may be heated to i6o° without injury. 
Trypsin is formed within the pancreas by a “ mother-substance,” or 
zymogen, taking up oxygen. The zymogen is found in small amount, 6 to 
io hours after a meal, in the inner zone of the secretory cells, but after 16 
hours it is very abundant in the inner zone of the cells. It is soluble in water 
and glycerin. Trypsin is formed in the watery solution from the zymogen, 
and the same result occurs when the pancreas is chopped up and treated with 
strong alcohol (.Kiihne). The addition of sodium chloride, carbonate, and 
glycocholate, favors the activity of the tryptic ferment (Heidenhain). [The 
following facts show that zymogen (JZoiirj, ferment), or, as it has been called, 
trypsinogen, is the precursor of trypsin, that it exists in the gland-cells, and 
requires to be acted upon before trypsin is formed. If a glycerin extract be 
made of a pancreas taken from an animal just killed, and if another extract be 
made from a similar pancreas which has been kept for 24 hours, it will be found 
that an alkaline solution of the former has practically no effect on fibrin, while 
the latter is powerfully proteolytic. If a fresh, and still warm, pancreas be 
rubbed up with an equal volume of a 1 percent, solution of acetic acid, and then 
extracted with glycerin, a powerfully proteolytic extract is at once obtained. 
Trypsin is formed from zymogen by the action of acetic acid. There is reason 
to believe that trypsin is formed from zymogen by oxidation, and that the 
former loses its proteolytic power after removal of its oxygen. The amount of 
zymogen present in the gland-cells seems to depend upon the number and size 
of the granules present in the inner granular zone of the secretory cells.] 
Further Effects on Proteids.—When trypsin is allowed to act upon 
the hemi-peptone formed by its own action, the latter is partly changed into 
the amido-acid, leucin, or amido-caproic acid (C6H13N02), and tyrosin 
(C9HnN03). Tyrosin belongs to the aromatic series (§ 252, IV, 3). Hypo- 
xanthin, xanthin, and aspartic or amido-succinic acid (C4H9N04) are also formed 
during the digestion of fibrin and gluten, and so are glutamic (C5H9N04) and 
amido-valerianic acid (C5HuN02). Gelatin is first changed into gelatin-pep- 
tone, and afterwards is decomposed into glycin and ammonia. 
Putrefactive Phenomena.—If the action of the pancreatic juice be still 
further prolonged, especially if the reaction be alkaline, a body with a strong, 
stinking, disagreeable fsecal odor is formed together with indol (C8H7N), 
skatol (C9H9N), and phenol (C6H60), and a substance—protein-chromo- 
gen—which becomes red on the addition of chlorine-water (.Bernard), [or it 
gives with bromine-water first a pale red and then a violet tint (.Kiihne')], 
volatile fatty acids are formed, while, at the same time, H, C02, H2S, CH4, 
and N are given off. The formation of indol and the other substances just 
mentioned depends upon putrefaction (§ 184, III). Their formation is pre- 
vented by the addition of salicylic acid, or thymol, which kills the organisms 
upon which putrefaction depends (.Kiihne). 
[Peptones are formed from proteids by the action of the pancreatic ferment without the aid of 
micro-organisms (if the digestive fluid contains 1 per cent, carbolic acid it is quite antiseptic). 
The production of indol is always associated with the appearance of micro-organisms in the 
medium, and Harris and Tooth incline to the view that there are special indol-forming 
organisms, in the absence of which this body does not appear.] 314 
PANCREATIC DIGESTION OF PROTEIDS. 
[Sec. 170. 
[Artificial Digestion and Pancreatic vs. Gastric Digestion.—From 
fibrin placed in pancreatic juice, or in a 1 per cent, solution of sodium carbonate 
containing the ferment trypsin, peptones are rapidly formed at 40° C. When 
we compare gastric with pancreatic digestion, we find that the fibrin in 
pancreatic digestion is eroded, or eaten away, and never swells up. The 
process takes place in an alkaline medium, and never in an acid one. In fact, 
a 1 per cent, solution of sodic carbonate seems to play the same part in assist- 
ing trypsin that a .2 per cent, solution of HC1 does for pepsin, in gastric 
digestion. In gastric digestion acid-albumin or syntonin is formed in addition 
to the true peptones. In pancreatic digestion a body resembling alkali-albumin, 
which passes into a globulin-like body, and ultimately into a peptone, is 
formed. Of the peptones so produced, one is called anti-peptone, and it is 
not further changed, but part of the proteid is changed into hemi-peptone. 
This body, when acted upon, yields leucin and tyrosin. When putrefaction 
takes place, the bodies above-mentioned are also formed. We might represent 
the action of trypsin thus : Proteid -f- trypsin -f- 1 per cent, sodium carbonate, 
kept at 38° C. = formation of a globulin-like body, and then anti-peptone and 
hemi-peptone are formed. 
Anti-peptone 
yields 
Hemi-peptone. 
yields 
Normal Digestive Products. 
Putrefactive Products. 
undergoes no 
Leucin, 
Indol, 
Volatile Fatty Acids, 
further change. 
Tyrosin, 
Hypoxanthin, 
Aspartic Acid. 
Skatol, 
H, C02, H2S, 
Phenol. 
ch4, n. 
It seems that trypsin in pure water can act slowly upon fibrin to produce 
peptone. Pepsin cannot do this without the aid of an acid.] 
[In artificial tryptic digestion of fibrin Kiihne obtained 9.1 per cent, of leucin 
and 3.86 of tyrosin. S. Lea more recently obtained 8-10 per cent, of the 
former, and 2-3 per cent, of the latter—i. e., in the ratio of 3 : 1. Lea 
confirms Kiihne’s view, and has further shown from the examination of the 
contents of the duodenum in a dog after digestion of a meal of flesh, that 
both leucin and tyrosin are formed in the intestine in not inconsiderable 
quantities during natural tryptic digestion.] 
[The following scheme by Kiihne indicates the action of ferments (and cer- 
tain acids) on proteids. The latter are split up into an anti-group and a hemi- 
group. 
Action of pepsin in an 
acid medium. 
Action of Enzymes (ferments). 
Albumin. 
Action of trypsin in an 
alkaline medium. 
Anti-albumose. 
Hemi-albumose. 
Anti-peptone. 
Anti-peptone. 
Hemi-peptone. 
Hemi-peptone. 
Leucin, 
Tyrosin, etc. 
Leucin, 
Tyrosin, etc. 
The anti-group is not further split up, but the hemi-group although not split 
up by gastric digestion, is split up by tryptic digestion into leucin, tyrosin, and 
other products.] 
[Kiihne’s Pancreas Powder.—This is prepared by the prolonged extraction of fresh pan- 
creas of ox with alcohol and then with ether. If the dry powder be extracted for several hours Sec. 170.] 
ACTION OF THE PANCREATIC JUICE ON FATS. 
315 
with a 1 per cent, solution of salicylic acid, and filtered, a fluid with powerful proteolytic, but 
no diastatic, properties is obtained. Several hours afterwards much tyrosin may separate out, 
which, of course, must be removed by filtration. The clear fluid, when mixed with fibrin and a 
1 per cent, solution of sodic carbonate, rapidly digests fibrin. If it be desired to obtain a true 
pancreatic digestion, with none of the products of putrefaction, the mixture must be strongly 
“thymolized” with a 25 per cent, alcoholic solution of thymol (Kiihne).) 
[Setschenow finds that egg-albumin, boiled in a vacuum at 35°-4O0 C., is more rapidly digested 
than fibrin by a specially prepared trypsin.] When proteids are boiled for a long time with 
dilute H2S04, we obtain peptone, then leucin and tyrosin ; gelatin yields glycin. Hypoxanthin 
and xanthin are obtained in the same way by similarly boiling fibrin, and the former may even 
be obtained by boiling fibrin with water (Chittenden). 
It is very remarkable that the juice of the green fruit of the papaya tree, or Carica papaya, 
possesses digestive properties {Roy, Wittmack), and that the action is due to a peptonizing fer- 
ment, closely related to trypsin, and called caricin or papain. [It forms a true peptone, an 
intermediate body, and leucin and tyrosin. It also contains a milk-coagulating ferment (Martin).] 
The milky juice of the fig-tree has a similar action. Sprouting malt, vetch, hop, hemp during 
sprouting, and the receptacle of the artichoke contain a peptonizing ferment. Leucin, tyrosin, 
glutamic and aspartic acids, and xanthin are formed in the seeds of some plants; hence we may 
assume that the processes of decomposition in some seeds are closely allied to the fermentative 
actions that occur in the intestine. 
III. Its action on neutral fats is twofold: (1) It acts upon fats so as 
to form a fine permanent emulsion. (2) It causes neutral fats to take up 
a molecule of water and split into glycerin and their corresponding fatty 
acids :— 
(C„H,„0,) + 3( H,o) = (C,H,0S) + aCC^o,). 
Tristearin. Water. Glycerin. Stearic Acid. 
The latter result is due to the action of an easily-decomposable fat-splitting 
ferment (C7. Bernard), also called steapsin. Lecithin is decomposed by it 
into glycerin-phosphoric acid, neurin, and fatty acids. The fatty acids thus 
liberated are partly saponified by the alkali of the pancreatic and intestinal 
juices, and partly emulsionized by the alkaline intestinal juice. Both the soaps 
and emulsions are capable of being absorbed (§ 191). 
Emulsification.—The most important change effected on fats in the small intestine is the 
production of an emulsion, or their subdivision into exceedingly minute particles (£ 191). This 
is necessary in order that the fats may be taken up by the lacteals. If the fat to be emulsified 
contain a free fatty acid, i.e., if it be slightly rancid, and if the fluid with which it is mixed be 
alkaline, emulsification takes place extremely rapidly (Briicke). A drop of cod-liver oil, which 
in its unpurified condition always contains fatty acids, on being placed in a drop of 0.3 per cent, 
solution of soda, instantly gives rise to an emulsion (Gad). The excessively minute oil-globules 
that compose the emulsion are first covered with a layer of soap, which soon dissolves, and in 
the process small globules are detached from the original oil-globules. The fresh surface is 
again covered by a soap film, and the process is repeated over and over again until an exces- 
sively fine emulsion is obtained. If the fat contain much fatty acid, and the solution of soda be 
more concentrated, “ myelin forms’1'’ are obtained similar to those which are formed when fresh 
nerve-fibres are teased in water. Animal oils emulsionize more readily than vegetable oils; 
castor oil does not emulsionize (GW). [It is extremely difficult to obtain a perfectly neutral 
oil, as most oils contain a trace of a fatty acid. In fact, if on adding a weak solution of sodic 
carbonate to oil or fatty matters, fluid at the temperature of the body, an emulsion is obtained,, 
one may be sure that the oil contained a fatty acid, so that Bernard’s view about an “ emulsive 
ferment” being necessary is not endorsed. The fatty acid set free by the fat-splitting ferment 
enables the alkaline pancreatic juice at once to produce an emulsion.] 
Fat-Splitting Ferment.—This is a very unstable body, and must be prepared from the per- 
fectly fresh gland by rubbing it up with powdered glass, glycerin, and a 1 per cent solution of 
sodic carbonate, and allowing it to stand for a day or two (Grutzner). [This ferment is said to 
cause an emulsion of oil and mucilage tinged blue with litmus at 40° C. to become red (Gamgee). 
In performing this experiment notice that the mucilage is perfectly neutral, as gum-arabic is 
frequently acid.] 
[Pancreatic Extracts.—The action of the pancreas may be tested by making a watery ex- 
tract of a perfectly fresh gland. Such an extract always acts upon starch and generally upon 
fats, but this extract and also the glycerin extract vary in their action upon proteids at different 
times. If the extract—watery or glycerin—be made from the pancreas of a fasting animal, the 316 
SECRETION OF PANCREATIC JUICE. 
[Sec. 170. 
tryptic action is slight or absent, but is active if it be prepared from a gland 4 to 10 hours after 
a meal. The pancreatic preparations of Benger of Manchester, Savory and Moore, or Burroughs 
and Wellcome, all possess active diastatic and proteolytic properties.] 
[Pancreas Ferments.—Finely divided calf’s pancreas is extracted with less than twice its 
volume of water and kept for five hours at 38° C. The fluid is decanted, shaken with ether, and 
precipitated with alcohol. The precipitate is spread on filter paper and dried at 40° C. A small 
piece of this paper extracted with 3-4 cc. of water yields a fluid with diastatic, tryptic, and it is 
said, fat-splitting activities (Setschenow).~\ 
[Pancreas Salt.—Prosser James proposes to employ common salt mixed with pepsin, which 
he calls peptic salt; and he advocates the use of another preparation composed of the pancreatic 
ferments and common salt, pancreatic salt.] 
The pancreas of new-born children contains trypsin and the fat-decom- 
posing ferment, but not the diastatic one (.Zweifel). A slight diastatic action 
is obtained after two months, but the full effect is not obtained until after the 
first year (Korowin). 
IV. The pancreas contains a milk-curdling ferment, which may be ex- 
tracted by means of a concentrated solution of common salt. 
171. THE SECRETION OF THE PANCREATIC JUICE.— 
Rest and Activity.—As in other glands, we distinguish a quiescent state, 
during which the gland is soft and pale, and a state of secretory activity, dur- 
ing which the organ swells up and appears pale red. The latter condition only 
occurs after a meal, and is caused probably reflexly owing to stimulation of the 
nerves of the stomach and duodenum. Kiihne and Lea found that all the 
lobules of the gland were not active at the same time. The pancreas of the 
herbivora secretes uninterruptedly [but in the dog secretion is not constant]. 
Time of Secretion.—According to Bernstein and Heidenhain the secre- 
tion begins to flow when food is introduced into the stomach, and reaches its 
maximum 2 to 3 hours thereafter. The amount falls towards the 5th or 7th 
hour, and rises again (owing to the entrance of the chyme into the duodenum) 
towards the 9th and nth hour, gradually falling towards the 17th to 24th 
hour until it ceases completely. When more food is taken, the same process is 
repeated. As a general rule, a rapidly formed secretion contains less solids 
than one formed slowly. 
Condition of Blood-Vessels.—During secretion, the blood-vessels behave 
like the blood-vessels of the salivary glands after stimulation of the chorda— 
they dilate, and the venous blood is bright red—thus, it is probable that a similar 
nervous mechanism exists [but as yet no such mechanism has been discovered]. 
The secretion is excreted at a pressure of more than 17 mm. Hg. (rabbit). 
Effect of Nerves.—The nerves arise from the hepatic, splenic, and superior 
mesenteric plexuses, together with branches from the vagus and sympathetic. 
The secretion is excited by stimulation of the medulla oblongata, as well as 
by direct stimulation of the gland itself by induction-shocks. [It is not arrested 
by secretion of the cervical spinal cord.] The secretion is suppressed by 
atropin [in the dog, but not the rabbit], by producing vomiting, by stimula- 
tion of the central end of the vagus, as well as by stimulation of other sensory 
nerves, e. g., the crural and sciatic. Extirpation of the nerves accompanying 
the blood-vessels prevents the above-named stimuli from acting. Under these 
circumstances, a thin “ paralytic secretion,” with feeble digestive powers, is 
formed, but its amount is not influenced by the taking of food. [Secretion is 
excited by the injection of ether into the stomach.] 
Excision of the Pancreas.—The duct may be ligatured in animals, without causing any 
very great change in their nutrition; the absorption of fat from the intestine does not cease. 
After the duct is ligatured it may be again restored. Ligature of the duct may cause the forma- 
tion of cysts in the duct and atrophy of the gland-substance. Pigeons soon die after this opera- 
tion. [After excision of the pancreas, dogs become permanently diabetic (p. 331). There may 
be as much as 5-10 per cent, of sugar in the urine during fasting. In the later stages before 
death acetonuria occurs (Minkowski and v. Mering).'] Sec. 172.] 
PEPTONIZED FOOD. 
317 
[172. PREPARATION OF PEPTONIZED FOOD.—Peptonized 
food may be given to patients whose digestion is feeble {Roberts). Food may 
be peptonized either by peptic or tryptic digestion, but the former is not so 
suitable as the latter, because in peptic digestion the grateful odor and taste of 
the food are destroyed, while bitter bye-products are formed, so that pancreatic 
Portal vein and its branches of origin. A, liver; B, gall-bladder; C, spleen; D, stomach; E, 
part of the small intestine; I, trunk of the portal vein; 2, superior and 3, inferior mesen- 
teric veins; 4, superior, 5, middle and inferior hsemorrhoidal veins; 6, right, and 7, 
left, gastro-epiploic veins; 8, splenic vein; 9, gastric coronary vein; 10, pyloric vein; II, 
cystic vein. 
Fig. 224. 318 
STRUCTURE OF THE LIVER. 
[Sec. 172. 
digestion yields a more palatable and agreeable product. As trypsin is destroyed 
by gastric digestion, obviously it is useless to give extract of the pancreas to a 
patient along with his food.] 
[Peptonized Milk.—“A pint of milk is diluted with a quarter of a pint of water and heated 
to 6o° C. Two or three teaspoonfuls of Benger’s liquor pancreaticus, together with io or 20 
grains of bicarbonate of soda, are then mixed therewith.” Keep the mixture at 38° C. for about 
two hours, and then boil it for two or three minutes, which arrests the ferment action.] 
[Peptonized Gruel, prepared from oatmeal, or any farinaceous food, is more agreeable than 
peptonized milk, as the bitter flavor does not appear to be developed in the pancreatic digestion 
of vegetable proteids.] 
[Peptonized Milk-Gruel yielded Roberts the most satisfactory results, as a complete and 
highly nutritious food for weak digestions. Make a thick gruel from any farinaceous food, e.g., 
oatmeal, and while still hot add to it an equal volume of cold milk, when the mixture will have 
a temperature of 520 C. (1250 F.). To each pint of this mixture add two or three teaspoonfuls 
of liquor pancreaticus and 20 grains of bicarbonate of soda. It is kept warm for two hours 
under a “ cosey.” It is then boiled for a few minutes and strained. The bitterness of the 
digested milk is almost completely covered by the sugar produced during the process.] 
[Peptonized soups and beef-tea have also been made and used with success, and have been 
administered both by the mouth and rectum.] 
[Peptonizing powders containing the proper proportions of ferment and sodic bicarbonate 
are prepared by Benger, and Burroughs and Wellcome.] 
[173. Structure of the Liver.—The liver is the heaviest organ in the 
body, weighing in the adult, when devoid of blood, about 1850 grams. It 
formsof the weight of the male body, and is about 28 cm. in length, 18 cm. 
in breadth at its thickest part. The bile is carried out of the liver by the two 
hepatic ducts, which emerge from the right and left hepatic substance at the 
transverse fissure. They unite and are joined by the cystic duct, which is a 
continuation of the tapering extremity of the gall-bladder. By the union of 
the hepatic duct with the cystic duct the common bile duct (75 mm. long) 
is formed. It pierces the coats of the duodenum very obliquely, and opens, 
along with the pancreatic duct, into the duodenum. The gall-bladder is a 
pear-shaped sac, capable of containing 20-25 c.c. of bile. In some animals 
the gall-bladder is wanting, as in the donkey, elephant, and mouse.] 
[Blood-Vessels of the Liver.—The liver is supplied with blood by 
(1) The portal vein. (2) The hepatic artery. 
The portal vein is formed by the confluence of the splenic, inferior, and 
superior mesenteric veins, where- 
by the short, wide vena portae 
is formed (fig. 224, 1). It 
enters the liver at the transverse 
fissure, accompanied by the 
bile-duct and hepatic artery, 
and is distributed between the 
liver lobules. The portal vein 
returns the blood from the 
stomach, pancreas, intestines, 
and spleen; hence it carries 
some of the products of diges- 
tion directly to the liver, wrhere 
some of them are materially 
changed by the hepatic cells 
as they pass slowly through 
the hepatic blood-vessels. The 
hepatic artery supplies a small 
quantity of arterial blood to the 
liver. The blood, after circula- 
Fig. 225. 
Blood-vessels of a rabbit’s liver injected; portal vein, 
blue; hepatic vein, red (Stirling). Sec. 173.] 
BLOOD-VESSELS OF THE LIVER. 
319 
ting through the liver, is returned by the hepatic veins to the inferior vena 
cava.] 
The liver consists of innumerable small lobules or acini, i to 2 millimetres 
in diameter. These lobules are visible to the naked eye. All the lobules have 
the same structure. 
1. The Capsule.—The liver is covered by a thin, fibrous, firmly adherent 
capsule, which has on its free surface a layer of endothelium derived from the 
peritoneum. The capsule 
sends fine septa into the 
organ between the lobules, 
but it is also continued 
into the interior at the 
transverse fissure, where it 
surrounds the portal vein, 
hepatic artery, and bile- 
duct, and accompanies 
these structures as the 
capsule of Glisson, or 
interlobular connective tis- 
sue. The spaces in which 
these three structures lie 
are known as portal 
canals. In some animals 
(pig, camel, polar bear) 
the lobules are separated 
from each other by the 
somewhat lamellated con- 
nective tissue of Glisson’s 
capsule, but in man this is 
but slightly developed, so 
that adjoining lobules are more or less fused. Very delicate connective tissue, 
but small in amount, is also found within the lobules. Leucocytes are some- 
times found in the tissue of Glisson’s capsule. 
2. Blood-Vessels—(a) Branches of the Venous System.—The portal 
vein, after its entrance into the liver at the portal fissure, gives off numerous 
branches lying between the lobules, and ultimately forming small trunks 
which reach the periphery of the lobules, where they form a rich plexus. The 
branches of the portal vein lying between the lobules are called interlobular 
veins (figs. 225, 226, 227, V. /.), which are always provided with thick mus- 
cular walls. From these veins numerous capillaries (e, e) are given off to the 
entire periphery of the lobule. The capillaries converge towards the centre of 
the lobule. As they proceed inwards, they form elongated meshes, and between 
the capillaries lie rows or columns of liver-cells (d, d). The capillaries are 
relatively wide, and are so disposed as to lie between the edges of the columns 
of cells, and never between the surfaces of two neighboring cells. The capil- 
laries converge towards the centre of each lobule, where they join to form one 
large vein, the intralobular, hepatic, or central vein (V c), which tra- 
verses each lobule, reaches its surface at one point, passes out, and joins similar 
veins from other lobules to form the sublobular veins (fig. 227, V. s'). The 
branches of the hepatic veins have very thin walls. These in turn unite to 
form wide veins, the origins of the hepatic vein, which opens into the vena 
cava inferior. \ 
(b) The branches of the hepatic artery accompany the branches of the 
portal vein and bile-duct in the portal canals between the lobules, and in their 
Sublobular Vein. 
Intralobular Vein. 
Bile- 
Ducts. 
Inter- 
lobular 
Vein. 
Fig. 226. 
Section of human liver, X 20, showing the liver-lobules and 
the radiate arrangement of their cells from the central or 
intralobular vein. 320 
THE LIVER CELLS. 
[Sec. 173. 
course give off capillaries to supply the walls of the portal vein and larger bile- 
ducts. The branches of the hepatic artery anastomose frequently where they 
lie between the lobules. On reaching the periphery of the lobules, a certain 
number of capillaries are given off, which penetrate the lobule, and terminate 
in the capillaries of the portal vein (J, /). These capillaries, however, which 
supply the walls of the portal vein and large bile-ducts (r, r), terminate in 
veins which end in the portal vein (V. v). Several branches—capsular—pass 
to the surface of the liver, where they form a wide-meshed plexus under the 
peritoneum. The blood is returned by veins, which open into branches of the 
portal vein. 
I, Scheme of a liver-lobule— V. i, V. i, interlobular vein (portal); V. c, central or intralobular 
vein (hepatic); c, c, capillaries between both; V. s, sublobular vein; V.v, vena vascularis; 
A, A, hepatic artery, giving branches, r, r, to Glisson’s capsule and the larger vessels, and 
ultimately forming the venae vasculares at i, i, opening into the intralobular capillaries ; g, 
bile-ducts; x, x, intralobular biliary channels between the liver-cells ; d, d, position of the 
liver-cells between the meshes of the blood-capillaries. II. Isolated liver-cells—c, a blood- 
capillary; a, fine bile-capillary channel. 
Fig. 227. 
[Hepatic Zones.—Pathologists draw a sharp distinction between different zones within a 
hepatic lobule. Thus the central area, capillaries, and cells from the hepatic vein zone, which 
is especially liable to cyanotic changes; the area next the periphery of the lobule is the portal 
vein zone, whose cells, under certain circumstances, are particularly apt to undergo fatty 
degeneration; while there is an area lying midway between the two foregoing—the hepatic 
artery zone—which is specially liable to amyloid or waxy degeneration.] 
3. The liver cells (fig. 227, II, a) are irregular polygonal cells of about 
Tinny °f an inch (34 to 45 /*) in diameter (fig. 229). The arrangement of the 
capillaries within a lobule determines the arrangement of the liver-cells. The 
liver-cells form anastomosing columns which radiate from the centre to the Sec. 173.] 
CHANGES IN THE LIVER CELLS. 
321 
periphery of each lobule (figs. 228, 230). [The liver-cells are usually stated to 
be devoid of an envelope, although Haycraft states that they possess one. They 
usually contain a single nucleus, with one or more nucleoli, but sometimes two 
nuclei occur. The protoplasm and nucleus of each cell contain a plexus of 
fibrils just like other epithelial cells. In some animals, globules of oil and pig- 
ment-granules are found in the cell-protoplasm (fig. 229). Each cell is in 
relation with the wide-meshed blood-capillaries (fig. 227, d, d~), and also with 
the much narrower meshwork of bile-ducts (I, „r).] 
Changes in Liver-Cells.—The appearance of the cells varies with the 
period of digestion. During hunger, the liver-cells are finely granular and 
very cloudy (fig. 230), [and contain little glycogen, but many pigment-gran- 
ules, and the nucleus is more frequently absent. Often free nucleoli and pale 
nuclei are found (Ellenberger and Bailin'). During activity, i. e., after a full 
meal, especially of starchy food, the cells are larger and more distinct, stain 
more deeply with eosin, and contain fewer granules.] The protoplasm con- 
tains coarse, glancing hyaline masses of glycogen (fig. 233, 2), and near the 
surface of the cell it is 
condensed, and a fine 
network stretches to- 
ward the centre of the 
cell, and in it is suspen- 
ded the nucleus. All 
the hepatic cells are not 
in the same phase of 
activity at the same 
time. [Afanassiew finds 
that if the formation of 
bile in the liver be in- 
creased (e. g., by sec- 
tion of the hepatic 
nerves, or feeding with 
proteids), the cells are 
moderately enlarged in 
size, and contain nu- 
merous granules, which 
are proteid in their na- 
ture ; such cells resist 
the action of caustic pot- 
ash. When there is a 
great formation of gly- 
cogen (as after feeding 
Fig. 228. 
A liver lobule stained with picro-carmine (Stirling). BD., 
bile-duct; PV. and HV.,portal and hepatic veins; HA., 
hepatic artery. 
Human liver-cells containing oil-globules, b ; 
d, has two nuclei. 
Fig. 229. 
Liver-cells after withholding food for 
36 hours. 
Fig. 230. 
with potatoes and sugar), all the cells are very large and sharply defined, and 322 
CHANGES IN THE LIVER CELLS. 
[Sec. 173. 
contain many granules of glycogen, the cells being so large as to compress the 
capillaries.] 
[A. In frogs the appearance of the liver-cells varies with the season of the year. During 
the period from December to May—best studied in April—the cells are small, the nuclei large; 
and the cells contain very little or no glycogen. In the period from June to November—best 
studied in November—the cells are large, and contain many granules which are stained by eosin 
and nigrosin. They contain much glycogen (most in December), and their nuclei are small.] 
[The cells of a winter frog’s liver contain in their protoplasm (i) hyaline granules of glycogen, 
usually arranged towards the outer part of the cell near the blood-vessel; (2) scattered through- 
out the protoplasm of the cell there may be fine granules of fat or oil; and, (3) small granules 
of a proteid nature, at the inner part of the cell next the bile capillary. The last-named gran- 
ules diminish during digestion, and new ones appear to be formed in the intervals of digestion, so 
that there is an analogy between the liver-cells in this respect and other glands, e. g., pancreas. 
All these substances may be recognized either directly or by reagents; the glycogen gives a port- 
wine color with iodine, and the fat is blackened by osmic acid, while the proteid granules are 
not affected by osmic acid, but disappear in caustic potash. If the glycogen be dissolved out by 
water the outer part of the cell-protoplasm appears vacuolated. If a frog be fed on carbo- 
hydrates the cells enlarge, and there is a great accumulation of glycogen in the cell, especially at 
its outer part, so as to compress the protoplasm. The port-wine reaction is very marked. In a 
summer frog, or a starved one, the cells are very small and devoid of glycogen. In one fed on 
proteids there is little or no glycogen, and the cells are smaller and very granular.] 
[B. Mammals.—Much the same changes occur; but in one fed on carbo-hydrates the 
glycogen accumulates in the protoplasm around the nucleus, and spreads out towards the 
periphery, leaving a compressed crust of protoplasm outside it. If the glycogen be dissolved 
out, wide vacuoles bounded 
by threads of protoplasm 
are seen in the cells. In 
the starved mammal the 
cells generally are like 
those of the frog under 
similar conditions.] 
[Action of Drugs on 
the Liver-Cells.—Some 
substances excite the cells 
to activity, and cause them 
to present the appearance 
of cells in activity, e. g., 
pilocarpin, muscarin, aloes; 
less so salicylate and ben- 
zoate of soda and rhubarb, 
while atropin and lead 
acetate inhibit the signs of 
activity. These results were 
obtained in the horse by El- 
lenberger and Baum. [Stol- 
nikow, by using the quad- 
ruple staining method of 
Gaule, finds that the hepatic 
cells of the frog undergo re- 
markable changes in pois- 
oning by phosphorus. It 
Finest bile-capillary. 
Finest bile-capillary divided. 
Blood- 
vessel. 
Nucleus of a 
liver-cell. 
Finest 
bile-capillary. 
Blood-capillaries; finest bile-capillaries or canaliculi in their 
relative position in a rabbit’s liver. 
Fig. 231. 
Liver-cells of frogs, a, early, and b, late stage in poisoning by phosphorus; c, liver-cell of 
frog getting water only; d, getting sugar; and e, peptone (Stirling after Stolnikow). 
Fig. 232. Sec. 173.] 
STRUCTURE OF THE BILE-DUCTS. 
323 
is well known that this drug produces fatty degeneration of the liver-cells, but a deeper study 
shows that the changes are both histological and chemical. Besides producing remarkable 
changes in the protoplasm of the cell, the protoplasm of the nucleus, in the form of small 
masses called plasmosoma, passes out into the cell-body, perhaps to renew the latter. The cells 
are increased in size, both after poisoning with phosphorus and after excision of the fat bodies 
in the frog (fig. 232). The fat present in the liver in phosphorus-poisoning is not present as 
droplets of oil, but probably in a loose combination, e. g.s lecithin, and as a matter of fact the 
amount of liver-lecithin is extraordinarily increased. There is also an increase of the nuclein; 
while glycogen is absent (A. Leonard'). Antipyrin also produces profound changes, especially 
in the nuclei.] 
4. The Bile-Ducts.—The finest bile-capillaries, channels, or canaliculi 
arise at the centre of the lobule, and indeed throughout the whole lobule they 
form a regular anastomosing network of very fine tubes or channels. Each 
cell is surrounded by a polygonal—usually hexagonal—mesh (figs. 233, 3, 234). 
The bile-capillaries always lie in the middle of the 
surface between two adjoining cells (fig. 227 II, a), 
where they form actual intercellular passages, 
(fig. 231). [According to some observers, they are 
merely excessively narrow channels (1 to 2 wide) in 
the cement substance between the cells, while accord- 
ing to others they have a distinct delicate wall. The 
bile-capillary network is much closer than the blood- 
capillary network. Thus, there are three networks 
within each lobule— 
(1) A network of blood-capillaries; 
(2) “ liver-cells; 
(3) “ bile-capillaries; (fig. 231.)] 
[The intralobular bile-capillaries in man lie between two cells, but in the frog the channels 
lie at the junction of several hepatic cells, a fact best seen where the bile-capillary is cut 
transversely.] 
Fig- 233. 
I, Liver-cell, during fasting;- 
2, containing masses of gly- 
cogen ; 3, a liver-cell sur- 
rounded with bile channels, 
from which fine twigs pro- 
ceed into the cell-substance 
to end in vacuoles. 
Blood-vessels of rabbits liver injected with carmine (red). The bile-ducts and intralobular 
bile-capillaries are blue, being filled with a natural injection of sulph-indigotate of soda. 
Fig. 234. 
Excessively minute intracellular passages are said to pass from the bile- 
capillaries into the interior of the liver-cells, where they communicate with THE LYMPHATICS AND NERVES OF THE LIVER. 
[Sec. 173. 
certain small cavities or vacuoles (Asp, Kupffer) (fig. 233, 3). As the blood- 
capillaries run along the edge of the liver-cells, and the bile-capillaries between 
the opposed surfaces of adjacent cells, the two systems of canals within the 
lobule are kept separate. Some-bile capillaries run along the edges of the 
liver-cells in the human liver, especially during embryonic life. Towards the 
peripheral part of the lobule, the bile-capillaries are larger, while adjoining 
channels anastomose, and leave the lobule, where they become interlobular 
ducts (fig. 227 g), which join with other similar ducts to form larger inter- 
lobular bile-ducts. These accompany the hepatic artery and portal vein, and 
leave the liver at the transverse fissure. The finer interlobular ducts, unlike 
ducts generally, frequently anastomose in Glisson’s capsule, possess a structure- 
less basement membrane, and are lined by a single layer of low polyhedral 
epithelial cells. The larger interlobular ducts 
have a distinct wall, consisting of connective and 
elastic tissue, mixed with circularly-disposed 
smooth muscular fibres (fig. 235). Capillaries are 
supplied to the wall, which is lined by a single 
layer of columnar epithelium. A sub-mucosa 
occurs only in the largest bile-ducts and in the 
gall-bladder. Smooth muscular fibres, arranged 
in single bundles, occur in the largest ducts, and 
as longitudinal and circular layers in the gall- 
bladder, whose mucous membrane is provided 
with numerous folds and depressions. The mu- 
cous membrane of the gall-bladder is pitted and 
the mucous membrane lining it. The epithelium 
lining it is cylindrical, with a distinct clear disc, and between these cells are 
goblet-cells. Small branched tubular mucous glands occur in the larger 
bile-ducts and in the gall-bladder. 
Vasa aberrantia are isolated bile-ducts which occur on the surface of the liver, but have no 
relation to any system of liver-lobules. They occur at the sharp margin of the liver, in the 
region of the inferior vena cava, of the gall-bladder, and of the parts near the portal fissure. 
It seems that the liver-lobules to which they originally belonged have atrophied and disappeared 
[ Zuckerkandl and Toldt). 
5. The lymphatics begin as peri-capillary tubes around the capillaries 
within the lobules, emerge from the lobule, and run within the wall of the 
branches of the hepatic and portal veins, and afterwards surround the venous 
trunks, thus forming the interlobular lymphatics. These unite to form larger 
trunks, which leave the liver partly at the portal fissure, partly along with the 
hepatic veins, and partly at different points on the surface of the organ. There 
is a narrow superficial meshwork of lymphatics under the peritoneum—sub- 
peritoneal—which communicate with the thoracic lymphatics through the tri- 
angular ligament and suspensorium, while on the under surface they communi- 
cate with the lymphatics of the interlobular connective tissue. 
6. The nerves consist partly of medullated but chiefly of non-medullated 
fibres from branches of the sympathetic, the terminal branches of the right 
vagus, and some branches of the left vagus to the hepatic plexus, the hepatic 
plexus being that part of the solar plexus which embraces the portal vein, bile- 
duct, and hepatic artery, as these pass into the liver at the portal fissure. They 
accompany the branches of the hepatic artery, and ganglia occur on their 
branches within the liver. Some of the nerve-fibres are vaso-motor in function, 
and, according to Pfliiger, other nerve-fibres terminate directly in connection 
with liver-cells. [MacCallum describes an interlobular plexus of non- 
medullated fibres in man and Menobranchus, from which a perivascular and 
Circular 
fibres. 
Cylindrical 
epithelium. 
Fig- 235. 
Interlobular bile-duct (human). Sec. 173.] 
GLYCOGEN IN THE LIVER. 
325 
intercellular plexus proceeds. From the latter, fibrils pass to terminate within 
the cells near the nucleus.] 
Pathological.—The connective tissue between the lobules may undergo great increase in 
amount, especially in alcohol and gin drinkers, and thus the substance of the lobules may 
be greatly compressed, owing to the cicatricial contraction of the newly-formed connective 
tissue (cirrhosis of the liver). In such interlobular connective-tissue, newly-formed bile-ducts 
are found. 
Ligature of the ductus choledochus [causes enlargement of the spleen (rabbit), and a 
diminution in the number of the blood-corpuscles], and, after a time, interstitial inflammation of 
the liver. In rabbits and guinea-pigs the liver parenchyma disappears, and its place is taken by 
newly-formed connective tissue and bile-ducts (Charcot and Gombault). In all these cases of 
interstitial inflammation, there is proliferation of the epithelium of the bile-ducts. 
[Regeneration of the Liver.—Tizzoni finds that there may be partial regeneration and new 
formation of liver-lobules in the dog, the process being the same as that which occurs in the 
embryonic development of the organ, i.e., the growth of solid cylinders of liver-cells, formed by 
the pre-existing liver-cells, which penetrate into the connective tissue uniting the edges of the 
wound. These cells ultimately differentiate into hepatic cells and bile-ducts. Other observers 
attribute the new formation to outgrowths of the epithelial cells of the bile-cells.] 
[Excision of Part of Liver.—Nearly three-fourths of a rabbit’s liver may be excised, and 
still the animal may live in apparent health for months or even a year. This is due to the enor- 
mous regeneration of liver-tissue which takes place. Nearly the whole bulk of the organ removed 
may be reproduced, even if three-quarters of the liver be removed (Ponjick).] 
174. CHEMICAL COMPOSITION OF THE LIVER-CELLS.— 
(1) Proteids.—The fresh, soft, parenchyma of the liver is alkaline in reaction ; 
after death, coagulation occurs, the cell-contents appear turbid, the tissue be- 
comes friable, and gradually an acid reaction is developed. This process closely 
resembles what occurs in muscle, and is due to the coagulation of a myosin-like 
body, which is soluble during life, but after death undergoes spontaneous 
coagulation (.Plosz). The liver contains other proteids; globulins coagulating 
at 450, 56°, and at 70° C., and mere traces of a cell-albumin coagulating at 
7°0-73° C. Nucleo-albumins appear to be absent (.Halliburton). The nuclei 
contain nuclein. The connective-tissue yields gelatin. 
(2) Glycogen or Animal Starch.—1.2 to 2.6 per cent.—is a true carbo- 
hydrate most closely related to inulin, apparently soluble in cold water, but 
perhaps only swelling up in water yielding an opalescent solution, which 
diffuses with difficulty. It has the formula 6(C6H10O5) -f- H20 [and may be 
regarded as a colloid-carbohydrate.] It is stored up in the liver-cells in 
amorphous granules around the nuclei (fig. 233, 2), and is uniformly distributed 
in all parts of the liver. Like inulin, it gives a deep red or port-wine color 
with solution of iodine in iodide of potassium. It is changed into dextrin and 
sugar by diastatic ferments, and when boiled with dilute mineral acids it yields 
grape sugar (§ 148, I; § 170, I; §-252, III). [It appears to play the same 
part in animal metabolism that starch does in the metabolism of plants. It 
represents a store of the excess of carbohydrates stored up in the organism for 
future use.] 
Preparation of Glycogen.—[Feed a rabbit on carrots or boiled rice, and kill it three or four 
hours thereafter. Remove the liver immediately after death, cut it into fine pieces, and place 
these in boiling water, and boil it for some time in order to obtain a watery extract of the liver. 
The boiling water destroys the ferment supposed to be present in the liver, which would trans- 
form the glycogen into grape-sugar. To the cold filtrate are added alternately dilute hydro- 
chloric acid and potassic-mercuric iodide, which precipitate the proteids. Filter, when a clear 
opalescent fluid, containing the glycogen in solution, is obtained. The glycogen is precipitated 
from the filtrate, as a white amorphous powder, on adding an excess of 70 to 80 per cent, alcohol. 
The precipitate is washed with 60 per cent, and afterwards with 95 per cent, alcohol, then with 
ether, and lastly, with absolute alcohol; it is dried over sulphuric acid and weighed (Brucke). 
Kiilz modifies the method somewhat. After boiling the liver for half an hour, it is rubbed up 
with liquor potassse (100 grm. liver, 4 grm. KHO). Evaporate on a water-bath until all is dis- 
solved, which occurs in about 3 hours. After cooling, neutralize with HC1 and precipitate the 
proteids as above. The glycogen is precipitated with 96 per cent, alcohol, i. e., until the solution Sec. 174.] 
326 
GLYCOGEN IN THE LIVER. 
contains 60 per cent, of alcohol. F. Eves asserts that the post-mortem conversion of sugar in 
the liver is not attributable to a ferment action, and the rapid appearance of sugar in the liver 
after death is due to the specific metabolic activity of the dying cells (p. 327).] 
Sources.—These have been variously stated by different observers to be the 
carbohydrates of the food (.Pavy); glycerin, taurin, and glycin (the latter split- 
ting into glycogen and urea), the proteids (CY. Bernard) \ and gelatin (Salo- 
mon). If glycogen is derived from the albumins, it must be formed from a 
non-nitrogenous derivative thereof. 
Rohmann found that the use of ammonia carbonate and asparagin or glycin, along with a 
carbohydrate diet, in rabbits considerably increased the formation of glycogen. The acid formed 
in excessive amount, observed by Stadelmann in diabetes, unites with the ammonia and dimin- 
ishes considerably the formation of glycogen. 
Effects of Food.—Rabbits, whose livers have been rendered free from 
glycogen by starvation, yield new glycogen from their livers when they are fed 
with cane-sugar, grape-sugar, maltose, or starch. Active muscular movements 
soon make the liver of dogs free from glycogen ; exposure to cold diminishes 
its amount. Dextrin and grape-sugar occur in the dead liver, but, in addition, 
some glycogen is found for a considerable time after death in the liver and in 
the muscles. 
[Pfliiger regards the formation of glycogen from proteids as a synthetic process. The molecular 
group (CH2), present both in albumin and the fatty acids, must be changed into CH.OH by 
oxidation. The cells which cause this formation can also make use of these groups CH.OH, 
where they find them already present, as in sugar and glycerin. In this way the formation of 
glycogen from molecules derived from various sources is analogous to the formation of fat from 
carbohydrates or from proteids ($ 241).] 
If glycogen is injected into the blood, achroodextrin appears in the urine, and also haemo- 
globin, as glycogen dissolves red blood-corpuscles. Ligature of the bile-duct causes decrease of 
the glycogen in the liver. 
Other Situations.—Glycogen is not' confined to the liver-cells; it occurs during foetal life in 
all the tissues of the body of the embryo [including the embryonic skeleton], in young animals 
(Alikne), the placenta [in the epithelial cells between the foetal and maternal tissues] (.Bernard). 
[It occurs in large amount in the liver during intra-uterine life.] In the adult it occurs in the 
testicle, in the muscles (MacDonnel, O. Nasse), in numerous pathological products, in inflamed 
lungs (ATuhne), and also in the corresponding tissues of the lower animals. [It also occurs in 
the chorionic villi, in colorless blood-corpuscles, in fresh pus cells which still exhibit amoeboid 
movements, and in fact in all developing animal cells, with amoeboid movement; the outer root- 
sheath of a hair-follicle (Neisser); it is a never-failing constituent in cartilage, and in the 
muscles and liver of invertebrata, such as the oyster. There is none in the fresh brain of the 
dog or rabbit, but it is found in the brain in diabetic coma (Abeles).'] 
Modifying Conditions.—If to a diet of proteids there be added large 
quantities of starch, milk-, fruit-, or cane-sugar, or glycerin, the amount of gly- 
cogen in the liver is very greatly increased (to 12 per cent, in the fowl), with a 
purely albuminous diet there, is less glycogen, while a purely fatty diet dimin- 
ishes it enormously. During hunger it may disappear entirely. The injection 
of sugar or glycerin into a mesenteric vein of a starving rabbit causes the liver, 
previously free from glycogen, to contain glycogen (Naunyn). [It rapidly 
disappears from the liver of a rabbit by the action of cold, e.g., cold baths 
and cold air. It would seem, therefore, to be a source of heat. Glycerin 
increases it, and also prevents the post-mortem change of glycogen into grape- 
sugar.] 
[Effect of Drugs on Glycogen.—Arsenic, phosphorus, and antimony destroy the glycogenic 
function of the liver, no glycogen being present in the liver in animals poisoned with these 
drugs, so that puncture of the floor of the fourth ventricle no longer causes glycosuria in them. 
In animals poisoned by strychnia or curare, it is greatly diminished, both in the liver and in 
the muscles. Sugar is always present in the urine in the latter case but not in the former.] 
During life, in the intervals of digestion under normal conditions, the 
glycogen is slowly and gradually transformed into grape-sugar, and the latter Sec. 174.] 
GLYCOGENIC FUNCTION OF THE LIVER. 
327 
passes into the hepatic vein. The normal amount of sugar in blood is 0.5 to 1 
per 1000, although the blood of the hepatic vein contains somewhat more [.2-. 28 
per cent.]. A considerable amount is transformed into sugar only when there is a 
decided derangement of the hepatic circulation, and in these circumstances the 
blood of the hepatic vein contains more sugar. The glycogen undergoes this 
change very rapidly after death, so that a liver which has been dead for some 
time always contains more sugar and less glycogen, the grape-sugar formed 
corresponding to the glycogen which disappears. 
[Glycogeny or Glycogenic Function of the Liver.—The formation of 
glycogen in the liver is intimately related to the general metabolic phe- 
nomena in the body. In 1848 Bernard found that a considerable quantity of 
a reducing sugar was obtainable from the liver after death. In 1857, however, 
he found that if a liver be taken out of the body of a well-fed animal immedi- 
ately after death and analyzed, it did not contain sugar, but from it he obtained 
the body glycogen, the explanation of his first observation being that the 
glycogen normally existing in the cells of the living liver was rapidly converted 
into sugar after death. Pavy also showed that if the liver be examined as 
quickly as possible after death it contained only glycogen, with occasionally 
traces of sugar. 
An extract of a liver rapidly removed from a “ well-fed ” animal after death 
always presents an opalescent appearance, due to glycogen, and it gives all the 
reactions of glycogen. If, however, an extract be made of a liver that has been 
removed several hours previously, and especially if the liver has been kept in a 
warm place, a decoction of such a liver is always clear and contains no glycogen, 
but much sugar. The glycogen has after death, by some action or other, been 
converted into sugar; the agency, whatever it is, is destroyed by the tempera- 
ture of boiling water. It was suggested that the conversion was due to the action 
of a diastatic ferment, but this is highly doubtful. Diastatic ferments, e.g., 
ptyalin, when they act on glycogen, convert it into maltose. Now, the sugar 
which is formed in the liver post-mortem is glucose. More probably it is due to 
the action of the living protoplasm of the hepatic cell, a view confirmed by 
Dastre (p. 329).] 
[The quantity of glycogen in the liver varies in different species of animals, even under the 
same conditions of feeding, etc. MacDonnell gives the following :— 
Dog, 
Ratio of weight of body 
to weight of liver. 
30.1 
Percentage of 
glycogen. 
4-5 
Cat, 
19-1 
i-5 
Rabbit, 
35-i 
3-7 
Guinea-pig, 
1.4 
Rat, 
2-5 
Pigeon, 
44-1 
2-5] 
[That the amount of glycogen present in the liver is very variable, and is 
especially dependent on the nature and amount of the food, has already 
been stated. Prolonged fasting causes it to disappear from the liver entirely 
in dogs in fifteen or sixteen days, and in rabbits in five days. Feeding with 
carbohydrates causes the greatest accumulation of glycogen in the liver, or 
rather a mixed diet containing some proteids, but with a large excess of carbo- 
hydrates. If a dog or fox be starved until all glycogen disappears from its 
liver, and then be fed on flesh, i. e., proteids, glycogen accumulates in the 
liver; but not to such an extent as occurs after feeding with carbohydrates. 
The glycogen in the liver cannot be accounted for by the small quantities of 
glycogen that are present in the flesh, for small quantities of glycogen are formed 
in the liver even on a diet of fibrin, or gelatin. It seems, therefore, that some 
glycogen may be formed from proteids, and we know that when proteids are 328 
GLYCOGENIC FUNCTION OF THE LIVER. 
[Sec. 174. 
split up under certain conditions they yield a nitrogenous body and a carbon- 
containing non-nitrogenous residue ; the latter may probably be the source of 
the glycogen in this case. Fats are in no way concerned in the storing up of 
glycogen in the liver.] 
[The storing up of glycogen is also influenced by the season of the year apart from the 
taking of food. This is the case in the frog. There is a considerable storage of glycogen in the 
liver of the frog in winter, even though no food has been taken for some months; while in 
summer the liver contains very little (p. 322). The storage and disappearance of glycogen in 
the frog’s liver are ultimately dependent on temperature. If a winter frog be kept warm for 
some days, its hepatic glycogen rapidly disappears. From the above it would seem that glycogen 
may be formed independently of matters obtained from the alimentary canal. The material 
for its formation must have been furnished from some part of the frog other than the intestinal 
tract.] 
[It is obvious that the liver in some way or other manufactures glycogen 
either from the carbohydrates or proteids, or from both supplied to it. One 
theory suggests that the sugar carried by the portal vein to the liver is dehy- 
drated or loses water and is converted into glycogen, which is stored up in the 
hepatic cells. This view receives a certain amount of confirmation from 
Bernard’s experiment of injecting grape-sugar into the jugular vein, when the 
sugar was excreted in the urine. If, however, the sugar was slowly injected into 
a rectal vein, a tributary of the portal vein—i. <?., the sugar had to traverse the 
liver before it reached the general circulation—none of the sugar appeared in 
the urine ; at the same time there was an increase of glycogen in the liver. If 
this be the true view, then the liver-cells form a great storehouse for the 
carbohydrates during digestion, while the liver regulates the amount of sugar 
in the blood. It is known that if the sugar in the blood rises above a certain 
percentage (more than 0.3 per cent., normal amount 0.05-0.15), it is 
excreted by the urine. Considering, then, the rapid absorption of sugar from 
the intestine during digestion, it seems necessary that so much sugar should not 
be thrown continuously into the general circulation. The liver, on this theory, 
catches and secures the sugar, and stores it up as glycogen. The blood of the 
portal vein during digestion contains more sugar than the hepatic vein, but the 
hepatic vein in the intervals of digestion contains more sugar—about twice as 
much—than the portal vein. This has been ascertained for the hepatic vein 
by catheterization of the hepatic vein. A long flexible catheter is introduced 
through the jugular vein into the superior vena cava, and thence into the inferior 
vena cava ; and it is so arranged that the inferior cava can be occluded below 
the hepatic vein, and from the latter blood can be drawn off and analyzed.] 
[This increase of the sugar in the hepatic vein is interpreted to mean that in 
the intervals of digestion the liver slowly and steadily re-converts the glycogen 
into sugar, and discharges the latter into the hepatic vein, in this way supplying 
the needs of the economy for this substance, yet preventing the percentage of 
sugar in the blood rising so high that it would be excreted by the urine.] 
[It has been suggested that the glycogen in the liver is a preliminary phase 
in the constructive metabolism of fat. There are no good grounds of support 
for this view.] 
[Muscle-glycogen.—Next to the liver it occurs in largest amount in the 
muscles, and it disappears from some muscles, at least during starvation. Even 
admitting that it is diminished during the working of a muscle, a muscle re- 
mains contractile without glycogen (§ 294).] 
The diastatic ferment in the liver is small in amount, and can be ob- 
tained from the extract of the liver-cells by the same means as are applicable 
for obtaining other similar ferments, such as ptyalin ; it does not seem to be 
formed within the liver-cells, but only passes very rapidly from the blood into 
them. The ferment seems to be rapidly formed when the blood-stream under- Sec. 174.] 
FAT, FERMENT, AND SALTS OF THE LIVER. 
goes considerable derangement. A similar ferment is formed when red blood- 
corpuscles are dissolved (Tiege/), and, as red blood-corpuscles are continually 
destroyed within the liver, there is one source from which the ferment may be 
formed, whereby minute quantities of sugar would be continually formed in the 
liver. 
[Dastre, like Eves, was unable to find a diastatic ferment in the liver capable of converting 
glycogen into grape-sugar, nevertheless, he admits that glycogen is converted into glucose in the 
liver. This, he says, is due to the activity of the protoplasm of the living hepatic cells. He 
has found an invert ferment in the liver.] 
According to Seegen, the blood of the hepatic vein contains twice as much sugar (0.23 
per cent.) as that in the portal vein (0.119 per cent.); observations on dogs showed that the 
blood flowing through the liver gives up over 400 grms. sugar in 24 hrs. Hence, in carnivora, 
the greatest part of the C of the animal food must pass into sugar, so that the formation of sugar 
in the liver, and its decomposition in the blood, or in the organs traversed by the blood, must be 
a very important function of the metabolism. Seegen is also of opinion that the liver-glycogen 
takes no part in the formation of sugar in the liver. 
[Blood when perfused through a freshly excised liver (or through the kidneys, lungs, or mus- 
cles,) gains lactic acid (Gaglio). Lactic acid seems to be a normal constituent of the liver; at 
least when arterial blood or serum is perfused through the liver, the outflowing fluid contains 
lactic acid (Gaglio).] 
(3) Fats, in the form of highly refractive granules, occur in the liver-cells, 
as well as free in the bile-ducts; sometimes, when the food contains much fat 
(more abundant in drunkards and the phthisical), olein, palmitin, stearin, vola- 
tile fatty acids, and sarcolactic acid are found. 
There are also found traces of cholesterin, minute quantities of urea, uric acid, and the little- 
known body jecorin, C 105Hlg6N5SP3O46, discovered by Drechsel, contains S and P, and reduces 
alkaline solutions of copper like grape-sugar. Its function is unknown, but its reducing action 
must be borne in mind in connection with reducing substances in the liver. It is also found in 
the spleen, muscles, and blood (Baldi). The liver of birds contains a relatively large amount of 
uric acid, even 6 to 14 times as much as the blood (v. Schrceder). Leucin (? guanin), sarkin, 
xanthin, cystin and tyrosin occur pathologically in certain diseases where marked chemical de- 
compositions occur. 
[Fatty Degeneration and Infiltration.—Fatty granules are of common occurrence within 
the cells of the liver, constituting fatty infiltration, and when not too numerous do not seem to 
interfere greatly with the functions of the liver-cells. Fatty particles occur if too much fatty 
food be taken, and they are commonly found in the livers of stall-fed animals; the well-known 
pate-de-foie gras is largely composed of the livers of geese, which have been fed on large 
amounts of farinaceous food, and which have been subjected to other unfavorable hygienic con- 
ditions. Fatty granules are recognized by their highly refractive appearance, by their solubility 
in ether, and by being blackened by osmic acid. Even in health fatty granules are frequently 
present in the hepatic cells, especially those near the portal vein. During lactation also the liver 
contains much fat. In fishes the liver always contains much oil, and there seems to be some 
relation between the activity of the respiratory organs and the size of the liver; at any rate in 
fishes, where the respiration is less active—and the same is the case in embryos—the liver is 
always large, while birds with very active respiration have small livers. If a dog be fed on oil 
its hepatic cells readily become fatty.] 
(4) The inorganic substances in the human liver are—potassium, so- 
dium, calcium, magnesium, iron, manganese, chlorine, and phosphoric, sul- 
phuric, carbonic, and silicic acids; while copper, zinc, lead, mercury, and 
arsenic may be accidentally deposited in the hepatic tissue. 
[Tizzoni’s Reaction for Iron.—If a section of a liver (especially of a young animal) hard- 
ened in alcohol be treated with a solution of potassic ferrocyanide, and then with dilute hydro- 
chloric acid, as a general rule the preparation becomes blue, even to the naked eye ; but failing 
that, one can usually see with the microscope granules of Prussian blue in the protoplasm of the 
cells, indicating the presence of free iron oxide.] [If, as is very probable, the bile pigments are 
derived from a derivative of haemoglobin, what becomes of the iron? There are numerous 
combinations of iron in the liver, some simple, e.g., oxide and phosphate, and some more stable 
organic combinations, e.g., combined with nuclein, as an iron-nuclein called hepatin ($ 247, V.).] 
329 330 
TEMPORARY GLYCOSURIA. 
[Sec. 175. 
175- DIABETES MELLITUS AND GLYCOSURIA.—[Glyco- 
suria is characterized by the presence of grape-sugar in the urine. Ac- 
cording to Briicke a trace of sugar exists normally in urine, and when this 
amount is increased we have glycosuria. When the normal amount of grape- 
sugar in the blood is increased, grape-sugar appears in the urine. The blood 
normally contains 0.05-0.15 per cent, of sugar, that of diabetics 0.22-0.44 
per cent. When the percentage of sugar is artificially increased to 0.3 per 
cent., sugar passes into the urine. In diabetes mellitus, grape-sugar also 
appears in the urine, but this is really a serious disease, involving the alteration 
of many tissues, and distinguished by profound disturbance of the whole meta- 
bolic activity, which leads to numerous pathological changes and often to death. 
The appearance of grape-sugar in urine does not necessarily mean that a person 
is suffering from this disease. The abnormal increase of sugar in the blood is 
the cause of the appearance of sugar in the urine. The increase of sugar in 
the blood in diabetics seems to be due to the diminution in the amount of sugar 
decomposed.] 
Temporary Glycosuria.—The formation of large quantities of grape- 
sugar by the liver, and its passage into the blood, and from the blood into the 
urine, constitute glycosuria. Extirpation of the liver in frogs, or destruction 
of the hepatic cells, as by fatty degeneration from poisoning with phosphorus 
or arsenic, does not cause this condition. It occurs after the injury of a cer- 
tain part—the centre for the hepatic vaso-motor nerves, “diabetic centre”—of 
the floor of the lower part of the fourth ventricle at the level of the origin of 
the vagi (C/. Bernard's “piqure”). [The animal must be well fed previously, 
and the urine in a few hours will not only be increased in quantity, but contain 
sugar. The amount of sugar reaches a maximum and then declines; the urine 
becomes non-saccharine in a day or two, so that the glycosuria is only tempo- 
rary. In a starved animal the urine will contain little or no grape-sugar. Gly- 
cosuria also occurs after section of the vagi, so that the vagi are not the chan- 
nels through which the influences are conveyed to the liver to excite glycosuria. 
The piqure is effective even after section of the vagi.] It also occurs after sec- 
tion of the vaso-motor channels in the spinal cord, from above down, as far as 
the exit of the nerves for the liver, viz., to the lumbar region, and in the frog 
to the fourth vertebra (Schijf). When the vaso-motor nerves, which proceed 
from this centre to the liver, are cut or paralyzed in any part of their course, 
mellituria or glycosuria is produced. All the nerve-channels do not run through 
the spinal cord alone. A number of vaso-motor nerves leave the spinal cord 
higher up, pass into the sympathetic, and thus reach the liver; so that destruc- 
tion of the superior (Pavy), as well as of the inferior cervical sympathetic 
ganglion, and the first thoracic ganglion (Eckhard), the abdominal ganglia, 
and often of the splanchnic itself, produces it. The paralysis of the blood- 
vessels causes the liver to contain much blood, and the mtra-hepatic blood- 
stream is slowed. The disturbance of the circulation causes a great accumu- 
lation of sugar in the liver, as the blood-ferment has time to act upon the 
glycogen and transform it into sugar. By stimulation of the sympathetic at the 
lowest cervical and first thoracic ganglion, the hepatic vessels at the periphery 
of the liver-lobules become contracted and pale (Cyon). It is remarkable that 
glycosuria when present may be set aside by section of the splanchnic nerves. 
This is explained by supposing that the enormous dilatation and congestion, or 
the hyperaemia of the abdominal blood-vessels thereby produced, renders the 
liver anaemic. The vascularity of the liver produced by the injury to the 
fourth ventricle may be due, not to paralysis of vaso-constrictor nerves, but to 
stimulation of vaso-dilator fibres. This, however, has not been proved. 
[As to the path of the nervous impulses from the medulla oblongata to Sec. 175.J 
CAUSES OF GLYCOSURIA 
331 
the liver there is great uncertainty. As already stated, they do not pass 
through the vagi. They certainly pass down the cervical spinal cord, then 
leave the cord to pass into the sympathetic. Cyon stated that they enter the 
lowest cervical ganglion, and pass through the annulus of Vieussens to the first 
dorsal ganglion and then through the sympathetic to the cceliac plexus, and by 
the hepatic plexus to the liver. As we have seen, section of certain of these 
nerves produces diabetes, but section of the splanchnic nerve does not always 
do so, although it gives rise to vaso-motor paralysis of the hepatic vessels. It 
is to be remembered, however, that section of the splanchnics paralyzes the 
abdominal blood-vessels, and it may be that the great amount of vaso-motor 
paralysis thereby produced interferes with the velocity of the blood-stream 
through the liver. It is also to be remembered that the vaso-motor theory of 
glycosuria is by no means proved. The supposition that the nerves act directly 
on the hepatic cell protoplasm is by no means excluded.] 
[Reflex Production of Glycosuria.—Continued stimulation of peripheral nerves may act 
rejiexly upon the centre for the vaso-motor nerves of the liver. Diabetes has been observed to 
occur after stimulation of the central end of the vagus (C7. Bernard), and also after stimulation 
of the central end of the depressor nerve (Filehne). [Neuritis of the vagus, produced by injec- 
tion of lycopodium or croton oil into the nerve trunk or by the action of a ligature, is followed 
by glycosuria, which may last with intermissions for a month (.Arthaud and Butte').~\ Even 
section and subsequent stimulation of the central end of the sciatic nerve causes diabetes. This 
may explain the occurrence of diabetes in people who suffer from sciatica. [It may occur also 
after perverted nervous activity, as psychical excitement, neuralgias (sciatica, trigeminal or occi 
pital), concussion of the brain, as well as after certain injuries to the skull and vertebral column 
and some cerebral diseases.] 
Other Causes of Glycosuria.—According to Schiff, the stagnation of blood in other vascu- 
lar regions of the body may cause the ferment to accumulate in the blood to such an extent that 
diabetes occurs. The glycosuria that occurs after compression of the aorta or portal vein may 
perhaps be ascribed to this cause, but perhaps the pressure caused by these procedures may para- 
lyze certain nerves. According to Eckhard, injury to the vermiform process of the cerebellum 
of the rabbit causes diabetes [and so does injury to the cerebral peduncles and pons Varolii], In 
man, affections of the above-named nervous regions cause diabetes. [Complete extirpation of 
the pancreas in dogs causes glycosuria (v. Mering).~\ 
[In most individuals the use of a large quantity of sugar in the food is not followed by the 
appearance of sugar in the urine; but in some exceptional cases it is often present, e.g., in 
persons suffering from gastric catarrh, especially if they are gouty.] 
A number of poisons which paralyze the hepatic vaso-motor nerves produce diabetes; curare, 
CO, amyl nitrite, ortho-nitro-propionic acid, and methyl-delphinin [phloridzin (v. Mering)\ • 
less certainly morphia, chloral hydrate, HCN, and some other drugs; and some infectious dis- 
eases. But congestion of the liver produced in other ways appears to cause diabetes, e.g., after 
mechanical stimulation of the liver. To this class belongs the injection of dilute saline solutions 
into the blood (Bock Hoffmann), whereby either change in form or the solution of the colored 
blood-corpuscles causes the congestion. The circumstance that repeated blood-letting makes 
the blood richer in sugar may perhaps be explained by the slowing of the circulation. 
[Curare-poisoning causes glycosuria. This is not due to the artificial respiration necessary to 
keep curarized animals alive. It also occurs in frogs, and in these animals aeration of the blood 
can take place without the respiratory movements. Phloridzin is a glucoside, and it might be 
argued that the sugar formed under its influence was derived from the phloridzin itself, but the 
same effect is produced by phloretin, which is not a glucoside.] 
[Phloridzin-glycosuria.—Most of the means which produce glycosuria in other animals 
fail to do so in birds; even the piqure rarely produces it. This Thiel and Minkowski attribute 
to the intensely active oxidation-processes in birds. Phloridzin, a glucoside found in the root 
cortex of apple and cherry trees, causes glycosuria,“even after extirpation of the liver, which 
shows that in these cases there are other causes at work than obtain in the other forms of glyco- 
suria. Phloridzin makes animals, which are free from carbohydrates, diabetic. In this case the 
sugar must be derived from proteids (v. Mering). Phloridzin makes dogs diabetic within a few 
hours, but after two or three days the glycosuria disappears, but then the liver and muscles are 
free from glycogen. The administration of more phloridzin causes still more sugar to be excreted. 
This must proceed from proteid.] 
Theoretical.—In order to explain the more immediate cause of these phenomena several 
hypotheses have been advanced :— 
(«) The liver-glycogen may be transformed unhindered into sugar, as the blood in its passage THE FUNCTIONS OF THE LIVER. 
[Sec. 175. 
through the liver deposits or gives up the ferment to the liver-cells. So that the normal func- 
tion of the vaso-motor system of the liver, and its centre in the floor of the fourth ventricle, may 
be regarded as, in a certain sense, an “ inhibitory system ” for the formation of sugar. 
(6) If we assume that normally there is continually a small quantity of sugar passing from 
the liver into the hepatic vein, we might explain the diabetes as due to the disappearance of 
those decompositions—diminished burning-up of the sugar in the blood, which are constantly 
removing the sugar from the blood. In fact, diabetic persons have been found to consume less 
O and to have an increased formation of urea. 
Persons suffering from diabetes require a large amount of food ; they suffer greatly from 
thirst, and drink much fluid. They exhibit signs of marked emaciation, when the loss of the 
body is greater than the supply. [In advanced diabetes the glycogenic function of the liver is 
almost abolished, as was proved by removing with a trocar a small part of the liver from man, 
when almost no glycogen was found {Ehrlich'). The absorbed sugar in the portal vein passes 
directly into the general circulation without being submitted to the action of the liver (v. Fre- 
richs).] In severe cases, towards death, not unfrequently a peculiar comatose condition— 
diabetic coma—occurs, when the breath often has the odor of aceton, which is also found in 
the urine. But neither aceton nor its precursor, aceto-acetic acid, nor sethyl-diacetic acid, nor 
the unknown substance, in diabetic urine, which gives the red color with ferric chloride (v. 
Jaksch), is the cause of the coma (Frerichs and Brieger). 
[Injection of Grape-Sugar into the Blood.—When grape-sugar is injected into the jugular 
vein of a dog, only 33 per cent, at most is given off in the urine; within 2 to 5 hours the urine 
is free from sugar. Even within a few minutes after the injection, only a certain proportion 
(/4~X) °f the sugar is found in the blood; part of the sugar has been detected in the muscles, 
liver, and kidneys, but the fate of the remainder is not known. Immediately after the injection, 
the amount of haemoglobin and also of serum-albumin is diminished (50 per cent.), which is due 
to increase of the quantity of water within the vessels ; but within two hours the normal state is 
restored (.Brasol). In a curarized dog the injection of grape-sugar into a vein increases the 
blood-pressure, but this effect is not observed after the injection of morphia and chloral.] 
176. THE FUNCTIONS OF THE LIVER.—[To understand the 
functions of the liver, we must remember its unique relation to the vascu- 
lar and digestive systems, whereby many of the products of gastric and 
intestinal digestion have to traverse it before they reach the blood, and some 
of them as they traverse the liver are altered. We have still much to learn 
regarding the liver. It has several distinct functions—some obvious, others 
not. (1) The liver secretes bile, which is formed by the hepatic cells, and 
leaves the organ by the bile-ducts, to pass into the duodenum. (2) The liver- 
cells also form glycogen, which does not pass into the ducts, but in some 
altered and diffusible form passes into the blood-stream, and leaves the liver by 
the hepatic veins. Hence, the study of the liver materially influences our con- 
ception of a secreting organ. In this case, we have the products of its secre- 
tory activity leaving it by two different channels—the one by the ducts, and 
the other by the blood-stream. The liver, therefore, is a great storehouse of 
carbohydrates, and it serves them out to the economy as they are required. It 
prevents the blood from being overwhelmed with sugar, and on the other hand 
it prevents a deficiency of this important body in the blood (Btcnge). All this 
points to the liver as being an organ intimately related to the general meta- 
bolism of the body. (3) In a certain period of development it is concerned 
in the formation of blood-corpuscles (§ 7). (4) It has some relation to the 
breaking up of blood-corpuscles and the formation of urea and other meta- 
bolic products (§ 20, § 177, 3). (5) Some importance is attributed to the liver 
in connection with the arrest of certain substances absorbed from the alimen- 
tary canal, whereby they are either destroyed, stored up in the liver, or, it may 
be, prevented from entering the general circulation in too large amount. It is 
possible that ptomaines may be arrested in this way (§ 166). [It converts the 
poisonous aromatic products of putrefaction, e.g., phenol, derived from pro- 
teids in the intestine, into harmless compounds by conjugation with sulphates 
(§ 262).] 
[The liver has no special action on certain mineral substances which traverse it in the blood, 
e.g., potassic chloride, but it retains the vegetable alkaloids, provided they are not present in Sec. 176.] 
CHEMICAL COMPOSITION OF BILE. 
333 
too large an amount in the blood. The ptomaines are similarly retained in the liver. The liver 
is said to possess this property only as long as it contains glycogen (H. Rogers').] 
[Heger, in his experiments on the artificial circulation of blood through an excised liver, found 
that blood to which an alkaloid (nicotin) was added, after being perfused through the liver lost 
some of its nicotin. Again, a dose of nicotin or hyoscyamine that proves fatal when injected 
subcutaneously, does not do so when it is injected into a branch of the portal vein (Schiff and 
Latitenbach).) 
177. CONSTITUENTS OF THE BILE.—[The bile, although it is 
secreted continuously, and passes along the hepatic duct in most animals, is 
only poured into the intestine at certain times. In the intervals it is carried 
along the cystic duct and stored up in the gall-bladder. At certain times it is 
poured out by the common bile-duct into the duodenum.] 
Bile is a yellowish-brown or dark-green colored transparent fluid, with a 
sweetish, strongly bitter taste, feeble musk-like odor, and neutral reaction. The 
specific gravity of human bile from the gall-bladder = 1026 to 1032, while that 
from a fistula = 1020 to 1011. It contains no proteids. 
The following table gives its composition in different animals— 
ioo parts Bile of— 
Man. 
Ox. 
Pig. 
Dog. 
Gall-bladder. 
Fresh 
Secreted. 
Water, 
86.3 
90.4 
88.8 
85.2 
95-3 
Solids, 
137 
9.6 
11.2 
I4.8 
47 
Bile, salts, lecithin, 'J 
8.2 I 
f 7-3 
12.6 
3-4 
cholesterin, fats, V 
8.0 
soaps, J 
2.5 j 
(. 2.2 
D3 
o-5 
Mucus and pigment,. 
2.2 
o-3 
0.6 
o-3 
0.2 
Inorganic salts, . . 
0.8 
*•3 
1.1 
0.6 
0.6 
It contains— 
(1) Mucus, which gives bile its sticky character, and not unfrequently makes 
it alkaline; it is the product of the mucous glands and the goblet-cells of the 
mucous membrane of the larger bile-ducts. When bile is exposed to the air, 
the mucus causes it to putrefy rapidly. It is precipitated by acetic acid, or 
alcohol. 
[The bile formed in the ultimate bile-ducts does not seem to contain mucin or mucus, but bile 
from the gall-bladder always does, the difference in composition of bile from the gall-bladder and 
bile from the liver-duct being shown in the above table. The bile in the gall-bladder is more 
concentrated, so that absorption of water occurs in the gall-bladder. The mucus is partly formed 
by the mucous glands in the larger bile-ducts, and partly by the cells lining the gall-bladder 
(| 173). It is not a true mucin, but rather a nucleo-albumin.] 
(2) The Bile-Acids.—Glycocholic and taurocholic acids, so-called 
conjugate-acids, are united with soda (in traces with potash) to form glyco- 
cholate and taurocholate of soda, which have a bitter taste, and rotate the plane 
of polarized light to the right. In human bile (as well as in that of birds, 
many mammals, and amphibians) taurocholic acid is most abundant; in other 
animals (pig, ox) glycocholic acid is most abundant but is absent in sucklings. 
(■a) Glycocholic acid, C23H43N06, when boiled with caustic potash, or baryta 
water, or with dilute mineral acids, takes up H20 and splits into— 
Glycin (= Glycocoll = Gelatin Sugar = Amido acetic acid) = C2H5N02. 
-j- Cholalic acid (also called Cholic acid) = C24H40O5. 
= Glycocholic acid -(- Water = C26H43NQ6 -f- H20. 
(b) Taurocholic acid, C26H45NS07, when similarly treated, takes up water 
and splits into— 
Taurin (= Amidosethyl-Sulphuric acid) . . = C2H7NS03. 
-f- Cholalic acid = C24H40O5. 
== Taurocholic acid -)- Water = C24H45NS07 -f- H20 (Strecber). 334 
BILE SALTS AND THEIR TESTS. 
[Sec. 177. 
[Solutions of taurocholic acid are antiseptic, and if sufficiently strong interfere with the de- 
velopment of bacteria, and prevent the alcoholic and lactic fermentations, as well as the tryptic 
and diastatic action of the pancreas (Emich)i\ 
Preparation of the Bile-Acids.—Evaporate bile to % of its volume, rub it up into a paste 
with excess of animal charcoal, and dry at ioo° C. Extract the black mass with absolute alco- 
hol, and filter. After a part of the alcohol has been removed by distillation, the bile-salts are 
precipitated in a resinous form, and on the addition of excess of ether, there is formed immediately 
a crystalline mass of glancing needles (Plattner’s “ crystallized bile ”). The alkaline salts 
of the bile-acids are freely soluble in water or alcohol, and insoluble in ether. Neutral lead 
acetate precipitates the glycocholic acid—as lead glycocholate—from the solution of both salts; 
the precipitate is collected on a filter, dissolved in hot alcohol, and the lead is precipitated as 
lead sulphide by H2S; after removal of the lead sulphide, the addition of water precipitates the 
isolated glycocholic acid. If, after precipitating the lead glycocholate, the filtrate be treated 
with basic lead acetate, a precipitate of lead taurocholate is formed, from which the acid may be 
obtained in the same way as described above (Strecker). 
With regard to the decomposition products of the bile-acids, glycin, as 
such, does not occur in the body, but only in the bile in combination with 
cholic acid, in urine in combination with benzoic acid, as hippuric acid, and 
lastly, in gelatin in complex combination. [The constitution of glycin is 
known. It is the same as amido-acetic acid CH2(NH2)COOH. In the body it 
originates from proteid (Bunge).] 
Cholalic acid rotates the ray of polarized light to the right, and its chemical 
constitution is unknown. It is insoluble in water, soluble in alcohol, but soluble 
with difficulty in ether, from which it separates in prisms. Its crystalline alka- 
line salts are readily soluble in water. It is colored blue by iodine, and occurs 
free only in the intestine. 
Cholalic acid is replaced in the bile of many animals by a nearly related acid, e.g., in pig’s 
bile, by hyo-cholalic acid (Strecker); in the bile of the goose, cheno-cholalic acid is present 
(Marsson, Otto). [Cholalic acid obtained from the bile acids of various animals differs in its 
composition. The formula of cholalic acid from human bile is C18H2804, while that from ox 
bile is C24II40O5]. 
When cholalic acid is boiled with concentrated HC1, or heated dry at 200° 
C., it becomes an anhydride, thus : — 
Cholalic acid . . . 
. . — C24H40O5, produces 
Choloidinic acid 
. . — C24H3804 -f H,0, and this again yields 
Dyslysin .... 
• • — + H20. 
Choloidinic acid is, however, not improbably a mixture of cholalic acid and dyslysin; dyslysin, 
when fused with caustic potash, is changed into cholalate of potash. By oxidation cholalic 
acid yields a tribasic acid, as yet uninvestigated, and a fair amount of oxalic acid, but no fatty 
acids (Clive). 
[Taurin is derived from proteids, as shown by its composition and by the sulphur it contains.] 
Pettenkofer’s Test.—The bile-acids, cholic acid, and their anhydrides, 
when dissolved in water, yield on the addition of 2/z concentrated sulphuric 
acid (added in drops so as not to heat the fluid above 70° C.), and several 
drops of a 10 per cent, solution of cane-sugar, a reddish-purple transparent fluid, 
which shows two absorption-bands at E and F (Schenk). [Avery good method 
is to mix a few drops of the cane-sugar solution with the bile, and to shake the 
mixture until a copious froth is obtained. Pour the sulphuric acid down the side 
of the test-tube, and then the characteristic color is seen in the froth. Any 
albumin present must be removed before applying the test.] 
According to Drechsel, it is better to add phosphoric acid, instead of sulphuric acid, until the 
fluid is syrupy, then add the cane-sugar, and afterwards place the whole in boiling water. 
When investigating the amount of bile-acids in a liquid, the albumin must be removed before- 
hand, as it gives a reaction similar to the bile-acids, but in that case the red fluid has only one 
absorption-band. If only small quantities of bile-acids are present, the fluid must in the first 
place be concentrated by evaporation. Pettenkofer’s test depends on the formation of furfural 
from the sugar and H2S04, furfurol giving a red with the bile-acids (MyIt us). In place of sugar 
a X per cent, watery solution of furfurol may be used. [Sec. 177. 
THE BILE-PIGMENTS. 
335 
[Hay’s Test.—The bile-acids or their soluble salts Imver the surface-tension of fluids in which 
they are dissolved. Throw a small quantity of sulphur (sublimed or precipitated) on the surface 
of the fluid containing bile-acids, and if the bile-acids be present, the sulphur will at once begin 
to sink, and will be wholly precipitated within a few minutes. (Privately communicated.)'] 
The bile-acids are formed in the liver. After its extirpation, there is no 
accumulation of biliary matters in the blood. 
How the formation of the nitrogenous bile-acids is effected is quite unknown. They must be 
obtained from the decomposition of albuminous materials, and it is important to note that the 
amount of bile-acids is increased by albuminous food. Taurin contains part of the sulphur of 
albumin; bile-salts contain 4 to 4.6 per cent., which may perhaps be derived from dissolved red 
blood-corpuscles. 
(3) The Bile-Pigments.—The freshly secreted bile of man and many 
animals has a yellowish-brown color, due to the presence of bilirubin. [In 
cases of human biliary fistula, Robson found that in fresh human bile the pig- 
ment is biliverdin.] When it remains for a considerable time in the gall- 
bladder, or when alkaline bile is exposed to the air, the bilirubin absorbs O, 
and becomes changed into a green pigment, biliverdin. This substance is 
present naturally, and is the chief pigment in the bile of herbivora and cold- 
blooded animals. [Both pigments behave like acids; they form soluble com- 
pounds with the potassium group, and insoluble ones with the calcium group 
(Bunge). The actual amount of coloring matter in bile is always very small.] 
Anthen finds that living hepatic cells when brought into contact with a solu- 
tion of hsemoglobin outside the body take up haemoglobin, and (glycogen 
being present in them) convert it into a pigment closely related to the bile- 
pigment. 
The bile-pigments are :— 
(1a) Bilirubin (C32H36N406) is perhaps united with an alkali; it crystallizes 
in transparent fox-red clinorhombic prisms. It is insoluble in water, soluble in 
chloroform, by which substance it may be separated from biliverdin, which is 
insoluble in chloroform. It unites as a monobasic acid with alkalies, and as 
such is soluble. It is identical with Virchow’s haematoidin (§ 20). 
Preparation.—It is most easily prepared from the red (bilirubin-chalk) gall-stones of man or 
the ox. The stones are pounded, and their chalk dissolved by hydrochloric acid; the pigment 
is then extracted with chloroform. That bilirubin is derived from haemoglobin is very probable, 
considering its identity with haematoidin. Very probably red blood-corpuscles are dissolved in 
the liver, and their haemoglobin changed into bilirubin. 
(b) Biliverdin (B32H36N408) is an oxidized derivative of the former, from 
which it can be obtained by various oxidation-processes. It is readily soluble 
in alcohol, very slightly so in ether, and not at all soluble in chloroform. It 
occurs in the placenta of the bitch. As yet it has not been retransformed by 
reducing agents into bilirubin. 
Tests for Bile-Pigments.—Bilirubin and biliverdin may occur in other 
fluids, e.g., the urine, and are detected by the Gmelin-Heintz’ reaction. 
When nitric acid containing some nitrous acid is added to a liquid containing 
these pigments, a play of colors is obtained, beginning with green (biliverdin), 
blue—violet—red, ending with yellow. [This reaction is best done by placing 
a drop of the liquid on a white porcelain plate, and adding a drop of the 
impure nitric acid.] 
(c) If, when the blue color is reached, the oxidation process is arrested, bilicyanin (.Heynsius, 
Campbell), in acid solution blue (in alkaline violet), is obtained, which shows two ill-defined 
absorption-bands near D {Jaffa)- 
(d) Bilifuscin occurs in small amount in decomposing bile and in gall-stones = bilirubin 
+ HA . 
(1?) Biliprasin (Stadler) also occurs = bilirubin -f- H2 + O. 
(f) The yellow pigment, which ultimately results from the prolonged action of the oxidizing 
reagent, is the choletelin (C16H18N206) of Maly; it is amorphous, and soluble in water, alcohol, 
acids, and alkalies. 336 
CHOLESTERIN IN BILE. 
[Sec. 177. 
[ Spectrum of Bile.—The bile of carnivorous animals is generally free from absorption- 
bands, except when acids are added to it, in which case the band of bilirubin is revealed. Bili- 
rubin and biliverdin yield characteristic spectra only when they are treated with nitric acid. The 
bile of some animals yields bands, but when this is the case they are due to the presence of a 
derivative of hsematin, and MacMunn calls this body cholohaematin, which gives a three- or 
four-banded spectrum (ox, sheep).] 
(g) Bilirubin absorbs H + H20 (by putrefaction, or by the treatment of 
alkaline watery solutions with the powerfully reducing sodium amalgam), and 
becomes converted into Maly’s hydrobilirubin (C32H40N4O7), which is slightly 
soluble in water, and more easily soluble in solutions of salts, or alkalies, alco- 
hol, ether, chloroform, and shows an absorption-band at b, F. This substance, 
which, according to Hammarsten, occurs in normal bile, is a constant coloring- 
matter of faeces, and was called stercobilin by Vaulair and Masius, but is 
identical with hydrobilirubin (Maly). It is, however, probably identical with 
the urinary pigment urobilin of Jaffe (Stokvis, § 20). 
[According to MacMunn, hydro-bilirubin differs from urobilin. There is a close resemblance 
between pathological bilirubin and stercobilin. The bile of invertebrates contains none of the 
bile-pigments present in vertebrates, although haemochromogen is found in the cray-fish and 
pulmonate molluscs. In some organs, and in bile, a pigment-like vegetable chlorophyll—entero- 
chlorophyll—is found, but whether it is derived from without, or formed within the organism, 
is not certain (MacMunn).] 
[Electrolysis of Bile.—When ox-bile is electrolyzed in a U-tube, oxidation of the pig- 
ment takes place at the positive electrode, bilirubin being changed into biliverdin, and with a 
strong or long-continued current the biliverdin may in its turn give place to higher oxidation 
products. Reversal of the current will now cause the process to retrace its steps, and the bile- 
pigment will pass through bilirubin to a more reduced stage where the color is yellow (Haycraft 
and Scofield). The spectrum of the bile, however, remains practically unchanged amidst the 
play of oxidation and reduction. The substance which causes the absorption bands does not 
therefore belong to the bilirubin series. The changes produced in the pigment by electrolysis 
are not due to the direct action of the current, but to the action of the products set free at the 
electrodes. The bile-salts, on the other hand, are electrolytes (£. N. Stewart).'] 
(4) Cholesterin C26H440 + H20, is a monatomic alcohol which rotates the 
ray of polarized light to the left; it occurs also in blood, yelk, nervous matter 
[and gall-stones]. It forms transparent rhombic 
plates, which usually have a small oblong piece cut 
out of the corner (fig. 236). It is insoluble in water, 
soluble in hot alcohol, ether, or chloroform. It is 
kept in solution in the bile by the bile-salts. [The 
quantity is considerable. It may reach 2 per cent.] 
Preparation.—It is most easily prepared from so-called white 
gall-stones, which not unfrequently consist entirely of choles- 
terin, by extracting them with hot alcohol after they are pulver- 
ized. Crystals are excreted after evaporation of the alcohol. 
Tests.—They give a red color with sulphuric acid (5 vol. to I. 
vol. H20), while they give a blue—as cellulose does—with sulphuric acid and iodine. When 
dissolved in chloroform, one drop of concentrated sulphuric acid causes a deep red color (H. 
Schijf). Moistened with an alcoholic solution of alcohol, on adding H2S04, the crystals exhibit 
a green, blue, and red coloration. Dissolved in glacial acetic acid, H2S04 = red, and then a blue 
color (Liebermann). 
(5) Amongst the other organic constituents:—Lecithin (§ 23), or its 
decomposition-product, neurin (cholin), and glycero-phosphoric acid (into 
which lecithin may be artificially transformed by boiling with baryta) ; palmi- 
tin, stearin, olein, as well as their soda soaps ; diastatic ferment; traces 
of urea; (in ox-bile, acetic acid and propionic acid, united with glycerin, 
and metals, Dogiel). 
(5) Inorganic constituents of bile (0.6 to 1 per cent.) :— 
They are—sodic and potassic chloride, calcic and magnesic phosphate, and much iron, which 
in fresh bile gives the ordinary reactions for iron, so that iron must occur in one of its oxidized 
Fig. 236. 
Crystals of cholesterin. Sec. 177.] 
THE SECRETION OF BILE. 
337 
compounds in bile; manganese and silica. Gases.—Freshly-secreted bile contains in the dog 
more than 50 vol., and in the rabbit 109 vol. per cent. CO,2, partly united to alkalies, partly 
absorbed, the latter, however, being almost completely absorbed within the gall-bladder. 
The mean composition of human bile is:— 
Water, . . . . . 82 to 90 per cent. 
Bile salts 6 to 11 “ 
Fats and soaps, . . 2 “ 
Cholesterin, .... 0.4 “ 
Lecithin, 0.5 per cent. 
Mucin and pigments, . 1 to 3 “ 
Ash, 0.61 “ 
Further, unchanged fat probably always passes into the bile, but it is again absorbed there- 
from ( Virchow'). The amount of S in dry dog’s bile = 2.8 to 3.1 per cent., the N — 7 to 10 per 
cent. (Spiro); the sulphur of the bile is not oxidized into sulphuric acid, but it appears as a 
sulphur-compound in the urine (Kunkel, v. Voit). In birds deprived of their liver there is no 
formation of bile. 
[Comparative.—Dog’s bile is bright yellow and contains taurocholate only; cat’s bile has 
the same composition whatever the nature of the food. The bile of the fox and wolf contains 
traces of glycocholate. In herbivora the bile is generally green in color and contains both 
glycocholate and taurocholate of soda, but that of the sheep contains only traces of the 
former. Pig’s bile is turbid, reddish-brown, filters easily, and contains two special biliary 
acids—hyoglycocholate and hyotaurocholic. In the guinea-pig it is like amber in color and 
becomes green on exposure to the air. Bird’s bile is generally green, and so is that of the 
frog; the latter contains taurocholic acid. In fishes the bile contains chiefly taurocholic acid. 
Amphioxus has no bile. The so-called biliary secretion of the invertebrates does not seem to 
be true bile (Beaunis).] 
178. SECRETION OF BILE.—(1) The secretion of bile is not a 
mere filtration of substances already existing in the blood of the liver, but it is 
a chemical production of the characteristic biliary constituents, accompanied 
by oxidation, within the hepatic cells, to which the blood of the gland only 
supplies the raw material. The liver-cells themselves undergo histological 
changes during the process of digestion. It is secreted continually ; but part 
is stored up in the gall-bladder, and is poured out copiously during digestion. 
The higher temperature of the blood of the hepatic vein, as well as the large 
amount of C02 in the bile, indicates that oxidation occurs within the liver. 
The water of the bile is not merely filtered through the blood-capillaries, as the 
pressure within the bile-ducts [15-17 mm. Hg.] may exceed that in the portal 
vein [7 mm. Hg.] 
[Liver cells while still alive can produce bile salts from a mixture of haemoglobin and 
glycogen, a process which is favored by the addition of soda or serum [Kalimeyer and Alex. 
Sch?nidt).~\ 
(2) The quantity of. bile was estimated by v. Wittich, from a biliary 
fistula, at 533 cubic centimetres in twenty-four hours (some bile passed into the 
intestine) ; by Westphalen, at 453 to 566 grms. [by Murchison, at 40 oz.] ; by 
Joh. Ranke, on a biliary-pulmonary fistula, at 652 cubic centimetres ; Copeman 
and Winston, 700-800 c.c. The observation by Ranke gives 14 grms. (with 0.44 
grms. solids) per kilo, of man in twenty-four hours. The mean is 1290 c.c. per 
day in a man weighing 70 kilos. [Mayo Robson found in cases of biliary 
fistula an average of 30 oz. More is secreted during the day than at night.] 
Analogous values for animals are—1 kilo, dog, 32 grms. (1.2 solids); 1 kilo, rabbit, 137 
grms. (2.5 solids) ; I kilo, guinea-pig, 176 grms. (5.2 solids). 
(3) The excretion of bile into the intestine shows two maxima during one 
period of digestion; the first from 3 to 5 hours, and the second from 13 
to 15 hours, after food. This seems to be due to simultaneous reflex excite- 
ment of the hepatic blood-vessels, which become greatly dilated. 
(4) The influence of food is very marked. The largest amount is secreted 
after a flesh diet, with some fat added, less after vegetable food ; a Very small 
amount with a pure fat diet; it stops during hunger. [Mayo Robson did not 
find it to be materially influenced by diet.] Draughts of water increase the 338 
INFLUENCE OF BLOOD-SUPPLY ON BILE. 
[Sec. 178. 
amount, with a corresponding relative diminution of the solid constituents. 
[The biliary solids are increased by food, reaching their maximum about one 
hour after feeding.] 
(5) The influence of blood supply is variable:— 
(a) Secretion is greatly favored by a copious and rapid blood-supply. The blood-pressure 
is not the prime factor, as ligature of the cava above the diaphragm, whereby the greatest 
blood-pressure occurs in the liver, arrests the secretion. [It would seem, as in the case of the 
kidney, that the velocity of the blood has far more to do with it than the blood-pressure.] 
(£) Simultaneous ligature of the hepatic artery (diameter mm.) and the portal vein 
(diameter, 16 mm.) abolishes the secretion (Rohrig). These two vessels supply the raw material 
for the secretion of bile. 
(t) If the hepatic artery be ligatured, the portal vein alone sustains the secretion. Ligature 
of the artery or of one of its branches ultimately causes necrosis of the parts supplied by that 
branch, and eventually of the entire liver, as this artery is the nutrient vessel of the liver. 
(</) If the branch of the portal vein to one lobe be ligatured, there is only a slight secretion 
in that lobe, so that the bile must be formed from the arterial blood. Complete ligature of 
the portal vein rapidly causes death (§ 87). Neither ligature of the hepatic artery by itself, 
nor gradual obliteration of the portal vein by itself, causes cessation of the secretion, but it 
is diminished. That sudden ligature of the portal vein causes cessation is due to the fact that, 
in addition to diminution of the secretion, the enormous stagnation of blood in the rootlets of 
the portal vein in the abdominal organs makes the liver very anaemic, and thus prevents it from 
secreting. 
(<?) If the blood of the hepatic artery is allowed to pass into the portal vein (which has been 
ligatured on the peripheral side), secretion continues (Schiff). 
(/) Profuse loss of blood arrests the secretion of bile, before the muscular and nervous 
apparatus become paralyzed. A more copious supply of blood to other organs—e.g., to the 
muscles of the trunk—during vigorous exercise, diminishes the secretion, while the transfusion 
of large quantities of blood increases it, but if too high a pressure is caused in the portal vein, 
by introducing blood from the carotid of another animal, it is diminished. 
(g) Influence of Nerves.—All conditions which cause contraction of the abdominal blood- 
vessels, e. g., stimulation of the ansa Vieussenii, of the inferior cervical ganglion, of the hepatic 
nerves, of the splanchnics, of the spinal cord (either directly by strychnia, or reflexly through 
stimulation of sensory nerves), affect the secretion; and so do all conditions which cause stagna- 
tion or congestion of the blood in the hepatic vessels (section of the splanchnic nerves, diabetic 
puncture, § 175), section of the cervical spinal cord. Paralysis (ligature) of the hepatic nerves 
causes at first an increase of the biliary section. [Stimulation of the nerves around the hepatic 
artery causes at first an acceleration, and afterwards slowing of the secretion. Section of these 
nerves causes a decided acceleration. Doubtless these results are due to variations in the calibre 
of the vessels and bile-ducts.] 
(k) Portal and Hepatic Veins.—With regard to the raw material supplied to the liver by 
its blood-vessels, it is important to note the difference in the composition of the blood of the 
hepatic and portal veins. The blood of the hepatic vein contains more sugar, lecithin, cholesterin 
(?), (DrosdofiF), and blood-corpuscles, but less albumin, fibrin, haemoglobin, fat, water and salts.] 
[(f) Uffelmann observed that the flow of bile from a person with a biliary fistula was arrested 
during fever.] 
(6) The formation of bile is largely dependent upon the decomposition 
of red blood-corpuscles, as they supply the material for the formation of 
some of its constituents. 
Hence, all conditions which cause solution of the colored blood-corpuscles are accompanied 
by an increased formation of bile (§ 180). 
[The Specific Constituents of Bile.—The bile-acids and pigments are 
formed in the liver, (x) These substances do not exist in the general 
blood-stream. (2) In frogs, after removal of the liver, these substances are 
not found in the blood. (3) After ligature of the bile-ducts, and all the vessels 
passing to the liver in pigeons, the biliary secretion is arrested, but even after 
twenty-four hours none of the specific biliary constituents were found in the 
tissues or blood. No bile pigments were found in the blood-serum {Stem). 
Had the bile constituents been formed outside the liver, they would have 
accumulated in the blood and tissues. After ligature of the bile-ducts only in 
pigeons, biliary pigment is found in the blood and urine. The same is true 
of biliary acids as proved by Fleischl (p. 340).] Sec. 178.] 
BILIARY FISTULAS. 
339 
[As to the sources of the specific biliary constituents, the glycocol and taurin 
of the bile-acids, containing as they do nitrogen, must be derived from a 
proteid molecule, but cholalic acid—an acid free from N—does not necessarily 
arise from proteids.] 
[That the bile pigments are formed from haemoglobin resulting from the 
breaking up of haemoglobin is believed from the following considerations :— 
(1) In old apoplectic clots—haematoidin—a body nearly identical with 
bilirubin is found (§ 20). There is a genetic relation between bile-pigments 
and haematin:— 
Haematin, C32H32N404Fe. 
Bilirubin, C32H36N406. 
Biliverdin, C32H36N408. 
(2) Substances which cause solution of the blood-corpuscles within the vascular 
system increase the quantity of bile-pigments, e. g., the intra-venous injection 
of water, bile-salts, haemoglobin. (3) Moreover, the bile contains iron in the 
form of a phosphate, and the iron is perhaps obtained from the iron of the 
decomposed Hb. (4) Bile-pigments are only found in the vertebrata,—that 
is, in those animals whose blood contains haemoglobin. They do not occur in 
invertebrata. Amphioxus, which has no red blood-corpuscles, forms no bile- 
pigments.] 
(7) Of course a normal condition of the hepatic cells is required for a normal 
secretion of bile. 
[(8) Age.—The age of the individual does not appear to influence greatly its composition 
nor does sex influence it.] 
Biliary Fistulae.—The mechanism of the biliary secretion is studied in animals by means of 
biliary fistulae. Schwann made a permanent biliary fistula. He opened the belly by a vertical 
incision a little to the right of the ensiform 
process, cut into the fundus of the gall-bladder, 
and sewed its margins to the edges of the 
wound in the abdomen, and afterwards intro- 
duced a cannula into the wound (fig. 237). 
To secure that all the bile is discharged exter- 
nally, tie the common bile-duct in two places 
and divide it between the two ligatures. 
After a fistula is freshly made the secretion 
falls. This depends upon the removal of the 
bile from the body. If bile be supplied, the 
secretion is increased. Regeneration of the 
divided bile-duct may occur in dogs. V. 
Wittich observed a biliary fistula in man. [A 
temporary biliary fistula may also be made. 
The abdomen is opened in the same way as 
described above. A long bent glass cannula 
is introduced and tied into the common bile- 
duct, and the cystic duct is ligatured or 
clamped (fig. 237). The tube is brought out 
through the wound in the abdomen.] 
[Influence of the Liver on Metabolism.—If the liver be excluded from the circulation, 
important changes must necessarily occur in the metabolism. In birds (goose) there is an 
anastomosis between the portal system of the liver and that of the kidneys, so that, when the 
portal circulation is interrupted in these animals, there is never any great congestion in the 
abdominal organs. The goose dies generally eight to ten hours after the operation. The uric 
acid in the urine rapidly falls to a minimum to of normal); the chief constituent of the 
urine is then sarcolactic acid, while in normal urine there is none; the ammonia is increased 
(.Minkoivski). The experiment goes to indicate that uric acid is formed in the liver. Dog.— 
If the liver be excluded from the portal circulation, by connecting the portal vein with the 
inferior vena cava, and ligaturing the hepatic artery, a dog will live in the former case three to 
six days, and in the latter one to two. The liver does not undergo necrosis, nor does bile cease 
to be secreted. The liver is nourished by the blood in the hepatic vein, the reflux in this vein 
being probably caused by the respiratory movements (Slolnikow). Noel Paton finds that in dogs, 
Fig. 237. 
Schwann’s permanent fistula, and a temporary 
fistula. Abd, abdominal wall; G. B., gall- 
bladder; INT., intestine; T., tube in tem- 
porary fistula {Stirling). 340 
EXCRETION OF BILE. 
[Sec. 178. 
in a condition of nitrogenous equilibrium, some drugs which increase the flow of bile (e. g., 
salicylate and benzoate of soda, colchicum, perchloride of mercury, and euonymin) also increase 
the production of urea; hence, he concludes that the formation of urea in the liver bears a very 
direct relationship to the secretion of bile (§ 256).] 
179. EXCRETION OF BILE.—[In this connection we must keep in 
view two distinct mechanisms, (x) The bile-secreting mechanism depend- 
ent upon the liver-cells, which are always in a greater or less degree of activity; 
(2) the bile-expelling mechanism, which is specially active at certain 
periods of digestion (§ 178).] 
Excretion of bile is due to (1) the continual pressure of the newly-formed 
bile within the interlobular bile-ducts forcing onward the bile in the excretory 
ducts. 
(2) The interrupted periodic compression of the liver from above, by 
the diaphragm, at every inspiration. Further, every inspiration assists the flow 
of blood in the hepatic veins, and every respiratory increase of pressure within 
the abdomen favors the current in the portal vein. 
It is probable that the diminution of the secretion of bile, which occurs after bilateral division 
of the vagi, is to be explained in this way; still it is to be remembered, that the vagus sends 
branches to the hepatic plexus. It is not decided whether the biliary excretion is diminished 
after section of the phrenic nerves and paralysis of the abdominal muscles. 
(3) The contraction of the smooth muscles of the larger bile-ducts and the 
gall-bladder. Stimulation of the spinal cord, from which the motor nerves for 
these structures pass, causes acceleration of the outflow, which is afterwards 
followed by a diminished outflow. Under normal conditions, this stimulation 
seems to occur reflexly, and is caused by the passage of the ingesta into the 
duodenum, which, at the same time, excite movement of this part of the 
intestine. 
(4) Direct stimulation of the liver, and reflex stimulation of the spinal cord, 
diminish the excretion ; while extirpation of the hepatic plexus and injury to 
the floor of the fourth ventricle do not exert any disturbing influence. 
(5) A relatively small amount of resistance causes bile to stagnate in the 
bile-ducts. 
Secretion Pressure.—A manometer, tied into the gall-bladder of a guinea pig, supports a 
column of 200 millimetres of water or 15 mm. Hg; and secretion can take place under this 
pressure. If this pressure be increased, or too long sustained, the watery bile passes from the 
liver into the blood, even to the amount of four times the weight of the liver, thus causing 
solution of the red blood-corpuscles by the absorbed bile; and very soon thereafter haemoglobin 
appears in the urine. [This fact is of practical importance, as duodenitis may give rise to 
symptoms of jaundice, the resistance of the inflamed mucous membrane being sufficient to arrest 
the outflow ot bile.] 
Passage of Substances into the Bile.—Some substances which enter the blood pass into 
the bile; especially the metals, copper, arsenic, iron, etc.; potassium iodide, bromide and 
sulphocyanide, and turpentine [the latter gives it an odor of violets] ; to a less degree, cane- 
sugar and grape sugar; sodium salicylate, and carbolic acid. If a large amount of water be 
injected into the blood, the bile becomes albuminous; mercuric and mercurous chlorides cause 
an increase of the water of the bile. Sugar has been found in the bile in diabetes ; leucin and 
tyrosin in typhus, lactic acid and albumin in other pathological conditions of this fluid. 
180. REABSORPTION OF BILE; JAUNDICE.—I. Absorption-Jaundice.— 
When resistance is offered to the outflow of bile into the intestine, e. g., by a plug of mucus, 
or a gall-stone which occludes the bile-duct, or where a tumor or pressure from without makes 
it impervious—the bile-ducts become filled with bile and cause an enlargement of the liver [and 
may give rise to obstructive, mechanical, or hepatogenous jaundice.] The pressure within the 
bile-ducts is increased. As soon as the pressure has reached a certain amount, which it soon 
does when the bile-duct is occluded (in the dog 275 mm. of a column of bile), reabsorption of 
bile from the distended larger bile-ducts takes place into the lymphatics (not the blood-vessels) 
of the liver, the bile-acids pass into the lymphatics of the liver. [The lymphatics can be seen 
at the portal fissure filled with yellow-colored lymph.] The lymph passes into the thoracic 
duct, and so into the blood (Fleischl). Even when the pressure is very low within the portal Sec. 180.] 
JAUNDICE AND INFLUENCE OF DRUGS ON BILE. 
341 
vein, bile may pass into the blood without any obstruction to the bile-duct being present. This 
is the case in Icterus neonatorum, as after ligature of the umbilical cord no more blood passes 
through the umbilical vein ; further, in the icterus of hunger, “ hunger-jaundice,” as the portal 
vein is relatively empty, owing to the feeble absorption from the intestinal canal (Cl. Bernard). 
[Jaundice is readily produced by inhalation of arseniuretted hydrogen or the administration of 
toluylendiamin.] 
II. Cholaemia may also occur, owing to the excessive production of bile (hypercholia), the 
bile not being all excreted into the intestine, so that part of it is reabsorbed. This takes place 
when there is solution of a great number of blood-corpuscles ($ 178, 6), which yield material for 
the formation of bile. Thick inspissated bile accumulates in the bile-ducts, so that stagnation, 
with subsequent reabsorption of the bile, takes place. The transfusion of heterogeneous blood 
obtained by dissolving colored blood-corpuscles acts in this direction. Icterus is a common 
phenomenon after too copious transfusion of the same blood. The blood-corpuscles are dissolved 
by the injection into the blood of heterogeneous blood-serum, by the injection of bile-acids into 
the vessels, and by other salts, by phosphoric acid, water, chloral, inhalation of chloroform and 
ether; the injection of dissolved haemoglobin into the arteries or into a loop of the small intestine 
acts in the same way. 
Icterus Neonatorum.—When, owing to compression of the placenta within the uterus, too 
much blood is forced into the blood-vessels of the newly-born infant, a part of the surplus blood 
during the first few days becomes dissolved, and part of the haemoglobin is converted into bili- 
rubin, thus causing jaundice ( Virchow, Violet). 
Absorption-Jaundice.—When the jaundice is caused by the absorption of 
bile already formed in the liver, it is called hepatogenic or absorption-jaundice. 
The following are the symptoms :— 
(1) Bile-pigments and bile-acids pass into the tissues of the body; hence, the most pro- 
nounced external symptom is the yellowish tint or jaundice. The skin and the sclerotic become 
deeply colored yellow. In pregnancy the foetus is also tinged. 
(2) Bile-pigments and bile-acids pass into the urine (not into the saliva, tears, or mucus), 
(3 177)- When there is much bile-pigment, the urine is colored a deep yellowish-brown, and 
its froth is citron-yellow; while strips of gelatin or paper dipped into it also become colored. 
Occasionally bilirubin (= haematoidin) crystals occur in the urine (§ 266). 
(3) The faeces are ‘•‘•clay colored" (because the hydrobilirubin of the bile is absent from the 
fecal matter)—very hard (because the fluid of the bile does not pass into the intestine); contain 
much fat (in globules and crystals), because the fat is not sufficiently digested in the intestine 
without bile, so that 78 per cent, of the fat taken with the food reappears in the faeces (v. Voit); 
they have a very disagreeable odor, perhaps because the bile normally limits the putrefaction in 
the intestine. [V. Voit finds that putrefaction does not take place if fats be withheld from the 
food (p. 343).] The evacuation of the fceces occurs slozvly, partly owing to the hardness of the 
faeces, partly because of the absence of the peristaltic movements of the intestine, owing to the 
want of the stimulating action of the bile. 
(4) The heart-beats are greatly diminished, e.g., to 40 per minute. This is due to the action 
of the bile-salts, which at first stimulate the cardiac ganglia, and then weaken them. Bile-salts 
injected into the heart produce at first a temporary acceleration of the pulse, and afterwards 
slowing (Rohrig). The same occurs when they are injected into the blood, but in this case the 
stage of excitement is very short. The phenomenon is not affected by section of the vagi. It 
is probable, that when the action of the bile-salts is long continued, they act upon the heart- 
muscle. In addition to the action on the heart, there is slowing of the respiration and dimi- 
nution of temperature. 
(5) That the nervous system, and perhaps also the muscles, are affected, either by the bile- 
salts or by the accumulation of cholesterin in the blood, is shown by the very general relaxa- 
tion, sensation of fatigue, weakness, drowsiness, and lastly deep coma—sometimes there is sleep- 
lessness, itching of the skin, even mania, and spasms. Lowit, after injecting bile into animals, 
observed phenomena referable to stimulation of the respiratory, cardio-inhibitory, and vaso-motor 
nerve-centres. 
(6) In very pronounced jaundice there may be “yellow vision," owing to the impregnation of 
the retina and macula lutea with the bile-pigment. 
(7) The bile-acids in the blood dissolve the red blood-corpuscles. The haemoglobin is 
changed into new bile-pigment, and the globulin-like body of the haemoglobin may form 
urinary cylinders or cast§ in the urinary tubules, which are ultimately washed out of the tubules 
by the urine. 
[Influence of Drugs on the Secretion of Bile.—On animals one may make either a 
permanent or a temporary fistula (p. 339). The latter is the more satisfactory method, and the 
experiments are usually made on fasting curarized dogs. A suitable cannula is introduced into 
the common bile-duct (fig. 237), the animal is curarized, artificial respiration being kept up, while [Sec. 180. 
342 
FUNCTIONS OF THE BILE. 
the drug is injected into the stomach or intestine. Rohrig used this method, which was 
improved by Rutherford and Vignal. Rohrig found that some purgatives—croton oil, colocynth, 
jalap, aloes, rhubarb, senna, and other substances—increased the secretion of bile. Rutherford 
and Vignal investigated the action of a large number of drugs on the bile-secreting mechan- 
ism. They found that croton oil is a feeble hepatic stimulant, while podophyllin, aloes, col- 
chicum, euonymin, iridin, sanguinarin, ipecacuan, colocynth, sodium phosphate, phytolaccin, 
sodium benzoate, sodium salicylate, dilute nitro-hydrochloric acid, ammonium phosphate, mer- 
curic chloride (corrosive sublimate), are all powerful, or very considerable, hepatic stimulants. 
Some substances stimulate the intestinal glands, but not the liver, e.g., magnesium sulphate, 
castor oil, gamboge, ammonium chloride, manganese sulphate, calomel. Other substances stim- 
ulate the liver as well as the intestinal glands, although not to the same extent, e.g., scammony 
(powerful intestinal, feeble hepatic stimulant); colocynth excites both powerfully; jalap, 
sodium sulphate, and baptisin, act with considerable power both on the liver and the intestinal 
glands. Calabar bean stimulates the liver, and the increased secretion caused thereby may be 
reduced by sulphate of atropin, although the latter drug, when given alone, does not notably 
affect the secretion of bile. The injection of water or bile slightly increases the secretion. In 
all cases where purgation was produced by purely intestinal stimulants, such as magnesium 
sulphate, gamboge, and castor oil, the secretion of bile was diminished. In all such experi- 
ments it is most important that the temperature of the animal be kept up, else the secretion of 
bile diminishes. Paschkis’s results on dogs differ considerably from those of Rutherford. He 
asserts that only the bile-acids (salts) of all the substances he investigated excite a prompt and 
distinct cholagogue action. Baldi also asserts that he has not observed a decided increase of the 
secretion following the use of some of the so-called cholagogues.] 
[Biliary fistulse sometimes occur in man. The bile-duct may be completely blocked by gall- 
stones. Sometimes the gall-bladder is opened to remove the gall-stones, and occasionally a 
biliary fistula persists, the bile being wholly discharged through an opening, none reaching the 
intestine owing to occlusion of the common bile-duct. In a case observed by Mayo Robson, he 
found that many so-called cholagogues, e.g., euonymin, rhubarb, podophyllin, carbonate of soda, 
turpentine, benzoate of soda, seem rather to diminish than increase the amount of bile excreted; 
iridin appears to increase the flow temporarily without augmenting the total quantity in 24 
hours.] 
[As yet we cannot say definitely whether or not such substances as stimulate the secretion of 
bile do so by exciting the mucous membrane of the small intestine and thereby inducing reflex 
excitement of the liver. Their action does not seem to be due to increase of the blood-stream 
through the liver. More probably, as Rutherford suggests, these drugs act directly on the 
hepatic-cells or their nerves. Acetate of lead directly depresses the biliary secretion, while some 
substances affect it indirectly.] 
[Cholesteraemia.—Flint ascribes great importance to the excretion of cholesterin by the bile, 
with reference to the metabolism of the nervous system. Cholesterin, which is a normal in- 
gredient of nervous tissue, is excreted by the bile, and if it be retained in the blood “ choles- 
teraemia,” with grave nervous symptoms, is said to occur. This, however, is problematical, 
and the phenomena described are probably referable to the retention of the bile-acids in the 
blood.] 
181. FUNCTIONS OF THE BILE.—[(1) Bile is concerned in the 
digestion of certain food-stuff's. 
(2) Part is absorbed, a fact opposed to the view that bile is entirely an ex- 
cretion. 
(3) Part is excreted. Perhaps the bile is largely excrementitious ; at least, 
observations in cases of biliary fistula in man have shown that increase in body- 
weight and good health are quite consistent with the entire absence of bile 
from the intestines (M. Robs on). 
(A) Bile plays a part in the absorption of fats.—[The presence of bile 
in the intestine is not absolutely necessary for the digestion of such an amount 
of fat as is capable of supporting life and keeping up nutrition.] 
(1) It emulsionizes neutral fats, whereby the fatty granules pass more 
readily through or between the cylindrical epithelium of the small intestine 
into the lacteals. It does not decompose neutral fats into glycerin and a fatty 
acid, as the pancreas does (§ 170, III). 
When, however, fatty acids are dissolved in the bile, the bile-salts are decomposed, the bile- 
acids being set free, while the soda of the decomposed bile-salts readily forms a soluble soap 
with the fatty acids. These soaps are soluble in the bile, and increase considerably the emul- Sec. 181.] 
FUNCTIONS OF THE BILE. 
343 
sifying power of this fluid. Bile can dissolve fatty acids to form an acid fluid, which has high 
emulsionizing properties (Steiner). Emulsification is influenced by a I per cent, solution of 
NaCl, or Na^SO^. 
(2) As fluid fat flows more easily through capillary tubes moistened with bile, 
it is concluded that, when the pores of the wall of the small intestine are 
moistened with bile, the fatty particles pass more easily through them. 
(3) Filtration of fat takes place through a membrane moistened with bile or 
bile-salts under less pressure than when it is moistened with water or salt solu- 
tions (v. Wistinghausen). [Groper has repeated v. Wistinghausen’s experiment, 
but with negative results.] 
(4) As bile, like a solution of soap, has a certain relation to watery solutions, 
as well as to fats, it permits diffusion to take place between these two fluids, as 
the membrane is moistened by both fluids. 
Bile is of importance in the absorption of fats. This is strikingly illustrated by experiments 
on animals, in which the bile is entirely discharged externally through a fistula. Dogs under 
these conditions absorbed at most 40 per cent, of the fat taken with the food [60 per cent, being 
given off by the faeces, while a normal dog absorbs 99 per cent, of the fat]. The chyle of such 
animals is very poor in fat, is not white but transparent ;• the faeces, however, contain much fat, 
and are oily; the animals have a ravenous appetite; the tissues of the body contain little fat, 
even when the nutrition of the animals has not been much interfered with. Persons suffering 
from disturbances of the biliary secretion, or from liver affections, ought, therefore, to abstain 
from fatty food. [The digestion of flesh and gelatin is not interfered with in dogs by the removal 
of the bile (v. Voi(). Dogs with biliary fistula can digest albumin and carbohydrates as com- 
pletely as normal dogs. The putrefactive smell of the faeces in dogs with intestinal fistula is due 
to the unabsorbed fat enclosing the proteids, which become decomposed by the putrefactive 
organisms of the intestine (Bunge).~\ 
(B) Fresh bile contains a diastatic ferment, which transforms starch into 
sugar, and also glycogen into sugar. [This is a very feeble diastatic action, 
and is apparently not greater than that possessed by some other non-digestive 
juices in the body. Bile has no action on albumin.] 
(C) Bile excites contractions of the muscular coats of the intestine, 
and contributes thereby to absorption. [In cases of biliary fistula in man 
regular action of the bowels may occur without the presence of bile in the 
intestine.] 
(1) The bile-acids act as a stimulus to the muscles of the villi, which contract from time to 
time, so that the contents of the origins of the lacteals are emptied towards the larger lymphatics, 
and the villi are thus in a position to absorb more. [The villi act like numerous small pumps, 
and expel their contents, which are prevented from returning by the presence of valves in the 
larger lymphatics.] 
(2) The musculature of the intestine itself seems to be excited, perhaps through the 
agency of the plexus myentericus. In animals with a biliary fistula, and in which the bile-duct 
is obstructed, the intestinal peristalsis is greatly diminished, while the salts of the bile-acids ad- 
ministered by the mouth cause diarrhoea and vomiting. As contraction of the intestine aids 
absorption, bile is also necessary in this way for the absorption of the dissolved food-stuffs. 
(D) The presence of bile seems to be necessary to the vital activity of the 
intestinal epithelium in its supposed function of being concerned in the absorp- 
tion of fatty particles (§ 190). 
(E) Bile moistens the wall of the intestines, and gives to the faeces their 
normal amount of water, so that they can be readily evacuated. Animals with 
a biliary fistula, and some individuals with obstruction of the bile-ducts, are 
very costive. The mucus aids the forward movement of the ingesta through 
the intestinal canal. Thus, in a certain sense, bile is a natitralpurgative. 
(F) The bile diminishes putrefactive decomposition of the intestinal con- 
tents, especially with a fatty diet, § 190. [Thus, it is an antiseptic, although 
this is doubted by v. Voit. Its so-called antiseptic action is quite unimportant. 
Bile itself rapidly decomposes outside the body.] 
(G) When the strongly acid contents of the stomach pass into the duode- 344 
FATE OF THE BILIARY CONSTITUENTS 
[Sec. 181. 
num, the glycocholic acid is precipitated by the gastric acid, and carries the 
pepsin with it (Burkart). Some of the albumin, which has been simply dis- 
solved (but not peptone or propeptone), is also precipitated by the taurocholic 
acid (Maly and Emicli). The bile-salts are decomposed by the acid of the 
gastric juice. When the mixture is rendered alkaline by the pancreatic juice 
and the alkali derived from the decomposition of the bile-salts, the pancreatic 
juice acts energetically in this alkaline medium (Moleschott). 
[Taurocholic acid and its soda salts precipitate albumin, but not peptone ; glycocholic acid 
does not precipitate albumin, so that in the intestine the peptone is separated from the albumin 
(and syntonin), and may therefore be more readily absorbed, while the precipitate adhering to 
the intestinal wall can be further digested (Maly and Emich). Taurocholic acid behaves in 
the same way towards gelatin peptone.] 
Bilious Vomit.—When the bile passes into the stomach, as in vomiting, the acid of the 
gastric juice unites with the bases of the bile-salts; sodium chloride and free bile-acids are formed, 
and the acid-reaction is thereby somewhat diminished. The bile-acids cannot carry on gastric 
digestion; the neutralization also causes a precipitation of the pepsin and mucin. As soon, how- 
ever, as the walls of the stomach secrete more acid, the pepsin is redissolved. The bile which 
passes into the stomach deranges gastric digestion, by shrivelling the proteids, which can only be 
peptonized when they are swollen up (p. 305). 
182. FATE OF THE BILE.—Some of the biliary constituents are 
completely evacuated with the feces, while others are reabsorbed by the intes- 
tinal walls. [A considerable proportion of the bile is excreted.] 
(1) Mucin passes unchanged into the feces. 
(2) The bile-pigments are reduced, and are partly excreted with the feces 
as hydrobilirubin, and partly as the identical end-product urobilin by the 
urine (§ 177, 3^). 
From meconium hydrobilirubin is absent, while crystalline bilirubin and biliverdin, and an 
unknown red oxidation-product of them, are present [bile-acids, even taurocholic, and small 
traces of fatty acids] (Zweifel), so that it gives Gmelin’s reaction. Hence, no reduction—but 
rather oxidation —processes occur in the foetal intestine. [Composition of meconium.—Dary 
gives 72.7 per cent, water, 23.6 mucus and epithelium, 1 per cent, fat and cholesterin, and 3 
per cent, bile-pigments. Zweifel gives 79.78 percent, water, and solids 20.22 per cent. It does 
not contain lecithin, but so much bilirubin that Hoppe-Seyler uses it as a good source whence to 
obtain this pigment. It gives a spectrum of a body related to urobilin.] 
(3) Cholesterin is given off with the feces. 
(4) The bile salts are for the most part reabsorbed by the walls of the 
jejunum and ileum, to be re-employed in the animal’s economy. Tappeiner 
found them in the chyle of the thoracic duct—minute quantities pass normally 
from the blood into the urine. Only a very small amount of glycocholic acid 
appears unchanged in the feces. The taurocholic acid, as far as it is not ab- 
sorbed, is easily decomposed in the intestine, by the putrefactive processes, into 
cholalic acid and taurin; the former of these is found in the feces, but the 
taurin at least seems not to be constantly present. Part of the cholalic acid 
is absorbed, and may unite in the liver either with glycin or taurin ( Weiss). 
(5) The feces contain mere traces of lecithin. 
Impaired Nutrition.—The greatest part of the most important biliary constituents, the bile- 
acids, re-enter the blood, and thus is explained why animals with a biliary fistula, where all the 
bile is removed (without the animal being allowed to lick the bile), rapidly lose weight. This 
depends partly upon the digestion of the fats being interfered with, and also upon the direct loss 
of the bile-salts. If such dogs are to maintain their weight, they must eat twice as much food. 
In such cases, carbohydrates most beneficially replace the fats. If the digestive apparatus is 
otherwise intact, the animals, on account of their voracity, may even increase in weight, but the 
flesh and not the fat is increased. 
Bile partly an Excretion.—The fact that bile is secreted during the foetal 
period, whilst none of the other digestive fluids is, proves that it is an excretion. 
The cholalic acid which is reabsorbed by the intestinal walls passes into the body, and seems 
ultimately to be burned to form C02 and H20. The glycin (with hippuric acid) forms urea, as 
the urea is increased after the injection of glycin. The fate of taurin is unknown. When large Sec. 182.] 
brunner’s and lieberkuhn’s glands. 
345 
quantities are introduced into the human stomach, it reappears in the urine as tauro-carbamic 
acid, along with a small quantity of unchanged taurin. When injected subcutaneously into a 
rabbit, nearly all of it reappears in the urine. 
[Practical.—In practice it is important to remember that bile, once in the intestine, is liable 
to be absorbed unless it be carried down the intestine; hence, it is one thing to give a drug 
which will excite the secretion of the bile, i. e., a hepatic stimulant, and another to have the bile 
so secreted expelled. It is wise, therefore, to give a drug which will do both, or at least to com- 
bine a hepatic stimulant with one which will stimulate the musculature of the intestine as well. 
Active exercise, whereby the diaphragm is vigorously called into action -to compress the liver, 
wdll aid in the expulsion of the bile from the liver (Brunton).~\ 
183. THE INTESTINAL JUICE.—Length of Intestine.—The human intestine is 
ten times longer than the length of the body, as measured from the vertex to the anus. It is 
longer comparatively than that of the omnivora. Its minimum length is 507, its maximum 1194 
centimetres [17 to 35 feet] ; its capacity is relatively greater in children (Beneke) (§ 159). 
The succus entericus is the digestive fluid secreted by the numerous glands 
of the intestinal mucous membrane. The largest amount is produced by 
Lieberkiihn’s glands, while in the duodenum there is added the scanty secretion 
of Brunner’s glands. 
Brunner’s glands are small, branched, tubular glands, lying in the sub-mucosa of the duo- 
denum. Their fine ducts run inwards, pierce the mucous membrane, and open at the bases 
of the villi (figs. 214, 238). The acini are lined by cylindrical cells, like those lining the 
pyloric glands. In fact, Brunner’s glands are 
structurally and anatomically identical with the 
pyloric glands of the stomach. During hunger, 
the cells are turbid and small, while during di- 
gestion they are large and clear. The glands 
receive nerve-fibres from Meissner’s plexus 
(Drasch). 
I. The Secretion of Brunner’s 
Glands.—The granular contents of 
the secretory cells of these glands, 
which occur singly in man, but form 
a continuous layer in the duodenum 
of the sheep, besides proteids, consist 
of mucin and a ferment-substance of 
unknown constitution. The watery ex- 
tract of the glands causes—(1) Solution 
of proteids at the temperature of the 
body (.Krolow). (2) It also has a 
diastatic action. It converts maltose 
into glucose {Brown and Heroti). It 
does not appear to act upon fats. 
On account of the smallness of these objects, 
such experiments are only made with great 
difficulty, and, therefore, there is a considerable 
uncertainty with regard to the action of the 
secretion. 
Lieberkiihn’s glands are simple 
tubular glands resembling the fin- 
ger of a glove [or a test-tube], which lie closely packed, vertically, near each 
other, in the mucous membrane (fig. 239); they are most numerous in the 
large intestine, owing to the absence of villi in this region. They consist of a 
structureless membrana propria lined by a single layer of low cylindrical epi- 
thelium, between which numerous goblet-cells occur, the goblet-cells being fewer 
in the small intestine and much more numerous in the large (fig. 239). The 
glands of the small intestine yield a thin secretion, while those of the large 
intestine yield a large amount of sticky mucus from their goblet-cells (Klose 
E 
Mucous 
coat. 
Muscula ris 
mucosae. 
Sub- 
mucous 
coat. 
Muscular 
coat. 
Fig. 238. 
Serous coat. 
Vertical section of duodenum (cat) X 30. E, 
epithelium ; c and /, circular and longitudinal 
muscular fibres; L.g, Lieberkuhn’s glands ; 
B.g, Brunner’s glands; g, ganglion cells; 
v, villi. 346 
INTESTINAL FISTULA. 
[Sec. 183. 
and Heidenhain). [In a vertical section of the small intestine they lie at the 
base of the villi (figs. 238, 249). In transverse section they are shown in 
fig. 240.] 
II. The Secretion of Lieberkiihn’s Glands, from the duodenum on- 
wards, is the chief source of the intestinal juice. 
Intestinal Fistula.—The intestinal juice is obtained by making a Thiry’s Fistula (1864). 
A loop of the intestine of a dog is pulled forward (fig. 241), and a piece about 4 inches in 
length is cut out, so that the continuity of the intestinal tube is broken, but the mesentery 
and its blood-vessels are not divided. One end of this tube is closed, and the other end is 
left open and stitched to the abdominal wall (fig. 241, 3). The two ends of the intestine, 
from which this piece was taken, are brought together with sutures, so as to establish the 
continuity of the intestinal canal (fig. 241, 2). The excised pieces of intestine yield a secretion 
Crypt. 
Cavity 
of the 
gland. 
Glandular 
epithelium. 
Blood-vessel. 
Fig. 240. 
Transverse section of Lieberkiihn’s 
follicles. 
Fig. 239. 
Fig. 241. 
Lieberkiihn’s gland from 
the large intestine 
(dog). 
Scheme of Thiry’s fistula. I, 2, 3, 4, Vella’s 
fistula. A A.' are stitched together; Abd, 
Abdominal wall (Stirling). 
which is uncontaminated with any other digestive secretion. [Thiry’s method is very unsatis- 
factory, as judged from the action of the separated loop in relation to medicaments, 
probably owing to its mucous membrane becoming atrophied from disuse, or injured by inflam- 
mation.] 
[Meade Smith makes a small opening in the intestine, through which he introduces two 
small collapsed india-rubber balls, one above and the other below the opening, which are then 
distended by inflation until they completely block a certain length of the intestine. The loop 
thus blocked off, having been previously well washed out, is allowed to become filled with 
succus, which is secreted on the application of various stimuli. By means of Bernard’s gastric 
cannula (§ 165) inserted into the fistula in the loop, the secretion can be removed when desired.] 
[Vella’s Fistula.—Open the belly of adog.and pull out a loop (30 to 50 ctm.) [1 to feet] 
of small intestine, and ligature it; divide it above and below, and re-establish the continuity of Sec. 183.] 
ACTIONS OF INTESTINAL JUICE. 
347 
the rest of the intestine. Stitch both ends of the loop of intestine into the wound in the linea 
alba (fig. 241,4), so that there is a loop of intestine supplied by its blood-vessels and nerves, 
isolated, and with an upper and lower aperture.] 
The intestinal juice of such fistulae flows spontaneously in very small 
amount, and is increased during digestion; it is increased—especially its mucus 
—by mechanical, chemical, and electrical stimuli; at the same time, the mucous 
membrane becomes red, so that 100 centimetres yield 13 to 18 grams of this 
juice in an hour (Thiry). The juice is light yellow, opalescent, thin, strongly 
alkaline; specific gravity ion ; evolves C02 when an acid is added ; it contains 
albumin, ferments, and mucin—especially the juice of the large intestine. Its 
composition is—water, 97.59 ; proteids, 0.80 ; other organic substances = 0.73; 
salts, 0.88 per cent. ; amongst these—sodium carbonate, 0.32 to 0.34 per cent. 
[The intestinal juice obtained by Meade Smith’s method contained only 0.39 per cent, of 
organic matter, and in this respect agreed closely with the juice which A. Moreau procured by 
dividing the mesenteric nerves of a ligatured loop of intestine. The secretion of the large 
intestine is much more viscid than that of the small intestine.] 
[Very discordant results as to the quantity and actions of the intestinal juice have been ob- 
tained by different observers. Rohmann, however, working with a Vella’s fistula finds that the 
quantity of secretion obtained depends on the position of the loop of intestine isolated, more 
fluid being obtained from the lower than from the upper portion of the gut. The fluid of the 
upper portions yields much diastatic ferment, that of the lower only traces. Invertin is found in 
the upper but not in the lower portions. Demant collected some human intestinal juice, but he 
found that it had no action on fibrin, and only a slight action on boiled starch.] 
Actions of Succus Entericus.—It is most active in the dog, and in other 
animals it is more or less inactive. 
(1) It is less diastatic than the saliva and the pancreatic juice, but it does 
not form maltose; while the juice of the large intestine does not possess this 
property (.Eichhorst). 
(2) It converts maltose into grape-sugar. It seems, therefore, to continue the 
diastatic action of saliva (§ 148) and pancreatic juice (§ 170), which usually 
form only maltose. 
According to Bourquelot this action is due to the intestinal schizomycetes and not to the intes- 
tinal juice as such, the saliva, gastric juice, or invertin. The greater part of the maltose appears, 
however, to be absorbed unchanged. 
(3) Fibrin is slowly (by the trypsin and pepsin—Kiihne) peptonized (Thiry, 
Leube) ; less easily albumin (Masloff), fresh casein, flesh raw or cooked, vege- 
table albumin : probably gelatin also is changed by a special ferment into a 
solution which does not gelatinize (.Eichhorst). 
(4) Fats are only partly emulsionized (Schiff), and afterwards decomposed 
( Vella). 
(5) According to Cl. Bernard invertin occurs in intestinal juice (this fer- 
ment can also be extracted from yeast). It causes cane-sugar (C12H22Hn) to 
take up water (-j- H20), and converts it into invert-sugar, which is a mixture 
of left rotating sugar (lsevulose, C6H1206) and of grape-sugar (dextrose, 
C6H1206) (p. 351). Heat seems to be absorbed during the process. 
[Hoppe-Seyler has suggested that this ferment is not a natural product of the body, but is in- 
troduced from without with the food. Matthew Hay, however, finds it to be invariably present 
in the small intestine of the foetus]. 
[Bunge suggests that as it is doubtful if it has any digestive action on food, its chief im- 
portance lies in the sodic carbonate which it contains. This substance neutralizes the acids of 
the intestinal contents, and helps to emulsify the fats.] 
[Effect of Drugs on the Succus Entericus.—The subcutaneous injection of pilocarpin 
causes the mucous membrane of a Vella’s fistula to be congested, when a strongly alkaline, 
opalescent, watery, and slightly albuminous secretion is obtained. This secretion produces a 348 
FERMENTATION IN THE INTESTINE. 
[Sec. 183. 
reducing sugar, converts cane-sugar into invert-sugar, emulsifies neutral fats, ultimately splitting 
them up, peptonizes proteids, and coagulates milk, even although the milk be alkaline. The 
juice attacks the sarcous substance of muscle before the connective- 
tissues—the reverse of the gastric juice. The mucous membrane in 
a Vella’s fistula does not atrophy. K. B. Lehmann finds that the 
succus entericus obtained from the intestine of a goat by a Vella 
fistula has no digestive action.] 
The Action of Nerves on the secretion of the intestinal 
juice is not well determined. Section or stimulation of the vagi 
has no apparent effect; while extirpation of the large sympathetic 
abdominal ganglia causes the intestinal canal to be filled with a 
watery fluid, and gives rise to diarrhoea. This may be explained by 
the paralysis of the vaso-motor nerves, and also by the section of 
large lymphatic vessels during the operation, whereby absorption 
is interfered with and transudation is favored. Moreau’s Ex- 
periment—Moreau placed four ligatures on a loop of intestine at 
equal distances from each [other (fig. 242). The ligatures were 
tied so that three loops of intestine were shut off. The nerves (N) to the middle loop were 
divided, and the intestine was replaced in the abdominal cavity. After a time a very small 
amount of secretion, or none at all, was found in two of the ligatured compartments of the gut, 
i. e., in those with the nerves and blood-vessels intact (1, 3), but the compartment (2) whose 
nerves had been divided contained a watery secretion. Perhaps the secretion which occurs after 
section of the mesenteric nerves is a paralytic secretion. The secretion of the intestinal and 
gastric juices is diminished in man in certain nervous affections (hysteria, hypochondriasis, and 
various cerebral diseases); while in other conditions these secretions are increased. 
Excretion of Drugs.—If an isolated intestinal fistula be made, and various drugs adminis- 
tered, the mucous membrane excretes iodine, bromine, lithium, sulphocyanides, but not potassium 
ferrocyanide, arsenious or boracic acid, or iron salts. 
In sucklings, not unfrequently a large amount of acid is formed, when the fungi in the in- 
testine split up milk-sugar or grape-sugar into lactic acid (Leube). Starch changed into grape- 
sugar may undergo the same abnormal process; hence, infants ought not to be fed with starchy 
food. 
[Fate of the digestive Ferments.—Langley is of opinion that the digestive ferments are 
destroyed in the intestinal canal; the diastatic ferment of the saliva is destroyed by the free HC1 
of the gastric juice; pepsin and rennet are acted upon by the alkaline salts of the pancreatic 
and intestinal juices, and by trypsin ; while the diastatic and peptic ferments of the pancreas dis- 
appear under the influence of the acid fermentation in the large intestine. (See Urine, \ 262.)] 
184. FERMENTATION IN THE INTESTINE.—Those pro- 
cesses, which are to be regarded as fermentations or putrefactive processes, are 
quite different from those caused by the digestive enzymes or ferments just 
considered. [Lea proposes the term zymolysis for the changes brought about 
by unorganized ferments, in contradistinction to the results produced by 
organized ferments, such as yeast, or various bacteria.] The putrefactive 
changes are connected with the presence of lower organisms, so-called fer- 
mentation- or putrefaction-producers; and they may develop in suitable media 
outside the body. The lowly organisms which cause the intestinal fermen- 
tation are swallowed with the food and drink, and also with the saliva. 
When they are introduced, fermentation and putrefaction begin, and gases are 
evolved. 
Intestinal Gases.—During the whole of the foetal period, until birth, fer- 
mentation cannot occur; hence gases are never present in the intestine of the 
newly-born. The first air-bubbles pass into the intestine with the saliva which 
is swallowed, even before food has been taken. The germs of organisms are 
thus introduced into the intestine, and give rise to the formation of gases. 
The evolution of intestinal gases goes hand in hand with the fermentations. 
Air is also swallowed, and an exchange of gases takes place in the intestine, 
so that the composition of the intestinal gases depends upon various conditions. 
Kolbe and Ruge collected the gases from the anus of a man, and found in 100 
vols. :— 
Fig. 242. 
Scheme of Moreau’s experi- 
ment {Stirling). Sec. 184.] 
FUNGI IN THE INTESTINE. 
Food. 
co2. 
H. 
ch4. 
N. 
h2s. 
Milk, . . . 
Flesh, .... 
Peas, .... 
16.8 
12.4 
21.0 
43-3 
2.1 
4.0 
0.9 
27-5 
55-9 
38.3 
57-8 
18.9 
Quantity not 
estimated. 
1. Air-bubbles are swallowed with the food. The O is rapidly absorbed in 
the intestinal tract, so that in the lower part of the large intestine, even traces 
of O are absent. In exchange, the blood-vessels in the intestinal wall give off 
C02 into the intestine, so that part of the C02 in the intestine is derived by 
diffusion from the blood. 
2. H, C02, NH3, and CH4 are also formed from the intestinal contents by 
fermentation, which takes place even in the small intestine. 
Fungi.—The chief agents in the production of fermentations, putrefaction, and other similar 
decompositions are undoubtedly the group of fungi called fission fungi or schizomycetes. 
They are small unicellular organisms of various forms—globular, micrococcus ; short rods, 
bacterium; long rods, bacillus ; or spiral threads, vibrio, spirillum, spirochaeta (fig. 32). 
The mode of reproduction is by division, and they may either remain single or unite to form 
colonies. Each organism is usually capable of some degree of motion. They produce pro- 
found chemical changes in the fluids or media in which they grow and multiply, and these 
changes depend upon the vital activity of their protoplasm. These minute microscopic organisms 
take certain constituents from the “ nutrient fluids ” in which they live, and use them partly for 
building up their own tissues and partly for their own metabolism. In these processes, some 
of the substances so absorbed and assimilated undergo chemical changes, some ferments seem 
thereby to be produced, which in their turn may act upon material present in the nutritive 
fluid. 
These fungi consist of a capsule enclosing protoplasmic contents. Many of them are provided 
with excessively delicate cilia, by means of which they move about. The new organisms, 
produced by the division of pre-existing ones, sometimes form large colonies visible to the naked 
eye, the individual fungi being united by a jelly-like mass, the whole constituting zoogloea. 
In some fungi, reproduction takes place by spores ; more especially when the nutrient fluids are 
poor in nutritive materials. The bacteria form longer rods or threads, which are jointed, and 
in each joint or segment small (1-2 f) highly refractive globules or spores are developed (fig. 
243, 7). In some cases, as in the butyric acid fermentation, the rods become fusiform before 
spores are formed. When the 
envelope of the mother-cell is 
ruptured or destroyed, the spores 
are liberated,and if they fall upon 
or into a suitable medium, they 
germinate and reproduce organ- 
isms similar to those from which 
they sprang. The process ol 
spore-production is illustrated 
in fig. 243 B, 7, 8, 9, and in I, 
2, 3, 4 is shown the process oi 
germination in the butyric acid 
fungus. The spores are very 
tenacious of life; they may be 
dried, when they resist death for 
a very long time ; some of them 
are killed by being boiled. Some 
fungi exhibit their vital activities 
only in the presence of O 
(aerobes), while others require 
the exclusion of O (anaerobes, 
Pasteur). According to the 
products of their action, they 
are classified as follows:—Those 
that produce fermentations 
(zymogenic schizomycetes); 
those that produce pigments 
A, Bacterium aceti in the form of—cocci (i); diplococci (2); 
short rods (3); and jointed threads (4, 5). B, Bacillus 
butyricus—(1) isolated spore; (2,3,4) germinating condi- 
tion of the spores; (5, 6) short and long rods ; (7, 8, 9). 
formation of spores within a cellular fungus. 
Fig. 243. DIGESTION OF CELLULOSE. 
[Sec. 184. 
(chromogenic); those that produce disagreeable odors, as during putrefaction (bromogenic); 
and those that, when introduced into the living tissues of other organisms, produce pathological 
conditions, and even death (pathogenic). All these different kinds occur in the human body. 
When we consider that numerous fungi are introduced into the intestinal canal with the 
food and drink—that the temperature and other conditions within this tube are specially 
favorable for their development; that there also they meet with sufficient pabulum for their 
development and reproduction—we cannot wonder that a rich crop of these organisms is met 
with in the intestine, and that they produce there numerous fermentations. 
I. Fermentation of Carbohydrates.—(1) Bacillus acidi lactici 
consists of biscuit-shaped cells, 1.5-3 m in length, arranged ingroups or isolated. 
They split up grape-sugar into lactic acid : — 
1 grape-sugar = C6H1206 = 2(C3H603) = 2 lactic acid. 
Milk-sugar (C12H22Ou) can be split up by the same ferment, causing it to take 
up H20, and forming 2 molecules of grape-sugar, 2(C6Hj206), which are again 
split into 4 molecules of lactic acid 4(C3H603). 
This fungus and its spores occur everywhere in the atmosphere, and are the cause of the 
•spontaneous acidification and subsequent coagulation of milk ($ 230). There are other lactic 
acid-forming fungi. 
(2) Bacillus Butyricus, which in the presence of starch is often colored 
blue by iodine, changes lactic acid into butyric acid, together with C02 and H 
(Prazmowski). 
(C3H603) lactic acid = 
C4H802 = 1 butyric acid. 
2(C02) = 2 carbon dioxide. 
4H = 4 hydrogen. 
This fungus (fig. 243, B) is a true anaerobe, and grows only in the absence of O. The lactic 
acid fungus uses O very largely, and is, therefore, its natural precursor. The butyric acid 
fermentation is the last change undergone by many carbohydrates, especially by starch and 
inulin. It takes place constantly in the faeces. Some other fungi have a similar action. 
(3) Certain micrococci cause alcohol to be formed from carbohydrates. 
The presence of yeast may cause the formation of alcohol in the intestine, and 
in both cases also from milk-sugar, which first becomes changed into dextrose. 
(4) Bacterium aceti (fig. 243, A) converts alcohol into acetic acid outside the body. Alcohol 
(C2HgO) 4- O = C2H40 (Aldehyd) -f- H20. Acetic acid (C2H402) is formed from aldehyd 
by oxidation. According to Nageli, the same fungus causes the formation of a small amount of 
C02 and H20. - As the acetic fermentation is arrested at 35°C.,this fermentation cannot occur 
in the intestine, and the acetic acid, which is constantly found in the faeces, must be derived from 
another source. During putrefaction of the proteids, with exclusion of air, acetic acid is pro- 
duced (Nencki). 
(5) Starch and cellulose are partly dissolved by the schizomycetes (Bac. 
butyricus and Vibrio rugula) of the intestine. If cellulose be mixed with 
cloacal-mucus, or with the contents of the intestine, it passes into a saccharine 
carbohydrate which decomposes into equal volumes of C02 and CH4 (.Hoppe- 
Seyler). 
When the cellulose envelopes are softened and dissolved the digestive juices 
can act upon the enclosed digestible parts of the grains (Tappeiner). 
[Digestion of Cellulose.—In herbivora 40-60 per cent, of the cellulose 
taken in the food disappears in the intestine. None of the digestive juices can 
digest cellulose so long as putrefaction does not take place in the digestive 
mixture. The maceration of the cellulose with saliva begins in the paunch, 
but the chief change takes place in the caecum. It seems that first a sugar-like 
body is formed, and afterwards this may be split up into C02 and CH4. The 
putrefaction of cellulose yields large quantities of C02 and CH4.] 
[Weiske found that he could digest a considerable quantity of the-wood-fibres or cellulose of 
carrots, cabbage, and celery, but it can scarcely be regarded as a food for man. It, however, 
acts as a mechanical stimulus to promote peristalsis of the intestine. Hence it is absolutely Sec. 184.] 
FERMENTATION OF FATS AND PROTEIDS. 
351 
essential for animals with along intestine, e. g., rabbits. A rabbit fed on food free from cellulose 
rapidly dies, because the onward movement of the intestinal contents ceases. If horn-parings 
be added to the food—which are quite indigestible—nutrition is normal in rabbits; they act in 
a purely mechanical manner in place of the cellulose {Knieriem')J\ 
(6) Fungi, whose nature is unknown, can partly transform starch (? and cel- 
lulose) into sugar. 
(7) Others produce the ferment invertin. Invertin can change cane-sugar, 
milk-sugar, and maltose into glucoses (dextrose, laevulose, galactose) (§ 183, 
II, 5). Yeast has a similar action (§ 183, II, 5). 
CUH»CU + h2o = c6h12o6 + c6h12o6 
Cane-sugar. Water. Dextrose. Lsevulose. 
II. Fermentation of Fats (§ 251).—During putrefaction, organisms of 
an unknown nature cause neutral fats to take up water and split into glycerin 
and their corresponding fatty acid (§ 170). Glycerin is capable of under- 
going several fermentations, according to the fungus which acts upon it 
(§ 251). With a neutral reaction, in addition to succinic acid, a number of 
fatty acids, H and C02 are formed. 
Fitz found that the hay-bacillus (Bacillus subtilis, fig. 244) formed alcohol, and caproic, 
butyric, and acetic acids ; in other cases, especially butylic alcohol, van de Velde found butyric, 
lactic, and traces of succinic acid with C02, H20, N. 
The fatty acids, especially as chalk soaps, form an excellent material for 
fermentation. Calcium formiate mixed with cloacal-mucus ferments and yields 
calcium carbonate, C02 and H ; calcium acetate, under the same conditions, 
produces calcium carbonate C02 and CH4. Amongst the oxy-acids, we are 
acquainted with the fermentations of lactic, glycerinic, malic, tartaric, and 
citric acids. 
According to Fitz, lactic acid (in combination with chalk) produces propionic and acetic acids, 
C02,H20. Other ferments cause the formation of valerianic acid. Glycerinic acid, in addition 
to alcohol and succinic acid, yields chiefly acetic acid; malic acid forms succinic and acetic 
acids. The other acids above enumerated yield somewhat similar products. 
III. Fermentation of Proteids (§ 249).—The undigested proteids and 
their derivatives appear to be acted upon by fungi. Many fission fungi (Bac. 
subtilis and the 
spirillum of 
cheese), however, 
can produce a 
peptonizing fer- 
ment, so that a 
small amount of 
the peptonizing 
done in the in- 
testine may be 
due to microbes. 
This however has 
not been proved, 
although it has 
been rendered 
probable by the 
experiments ofVignal. 
We have already seen that pancreatic digestion acts upon the proteids, form- 
ing, among other products, amido-acids, leucin, tyrosin, and other bodies 
(§ 170, II). Under normal conditions, this is the greatest decomposition 
produced by the pancreatic juice. The putrefactive fermentation of the 
large intestine causes further and more profound decompositions. Leucin 
Bacillus subtilis. I, spore; 2, 3, 4, its germination; 5, 6, short rods; 7, 
jointed thread, with the formation of spores in each segment; 8, short 
rods, some of them containing spores ; 9, spores in single short rods ; 10, 
fungus with a cilium. 
Fig. 244. 352 
DECOMPOSITION PRODUCTS OF PROTEIDS. 
[Sec. 184. 
(C6H13N02) takes up two molecules of water and yields valerianic acid 
(C6H10O2), ammonia, C02 and H4; glycin behaves in a similar manner. 
Tyrosin (C9HnN03) is decomposed into indol (C8H7N), which is constantly 
present in the intestine along with carbon dioxide, water, and H. If O be pres- 
ent, other decompositions take place. These putrefactive products are absent 
from the intestinal canal of the foetus and the newly-born. During the putre- 
factive decomposition of proteids, C02, H2S, H, and CH+, are formed; the 
same result is obtained by boiling them with alkalies. Gelatin, under the 
same conditions, yields much leucin and ammonia, C02, acetic, butyric, and 
valerianic acids, and glycin. Mucin and nuclein undergo no change. Arti- 
ficial pancreatic digestion-mixtures rapidly tend to undergo putrefaction. 
The substance which causes the peculiar faecal odor is produced by putrefaction, but its 
nature is not known. It clings so firmly to indol and skatol that these substances were formerly 
regarded as the odorous bodies, but when they are prepared pure they are odorless [Bayer). 
Amongst the solid substances in the large intestine formed only by putre- 
faction is indol (C8H7N), a substance which is also formed when proteids 
are heated with alkalies, or by superheating them with water to 200° C. It is 
the stage preceding the indican in the urine. If the products of the digestion 
of the proteids—the peptones—are rapidly absorbed, there is only a slight 
formation of indol; but when absorption is slight, and putrefaction of the pro- 
ducts of pancreatic digestion occurs, much indol is formed, and indican appears 
in the urine. 
Jaffe found much indican in the urine in strangulated hernia, and when the small intestine 
was obstructed (§ 262, 1). 
Reactions for Indol.—Acidulate strongly with HC1, and shake vigorously after adding a few 
drops of turpentine. If there be an intense red color, the pigment is removed by ether. The 
substance—protein-chromogen—which is formed after the digestion of fibrin by trypsin, and 
which gives a violet color with bromine water (§ 170, II), can be removed by chloroform. In 
addition to the last pigment, there is a second one, which passes over during distillation, and 
which can be extracted from the distillate by ether. Both substances seem to belong to the 
indigo group (Krukenberg). 
A. Bayer prepared indigo-blue artificially from ortho-phenyl-propionic acid, by boiling with 
dilute caustic soda, after the addition of a little grape-sugar. He obtained indol and skatol from 
indigo-blue. Hoppe-Seyler found that on feeding rabbits with ortho-nitrophenyl-propionic acid, 
much indican was present in the urine. 
Phenol (C6H60) is formed during putrefaction in the intestine, and it is 
also formed when fibrin and pancreatic juice putrefy outside the body, while 
Brieger found it constantly in the faeces. It seems to be increased by the same 
circumstances that increase indol, as an excess of indican in the urine is accom- 
panied by an increase of phenylsulphuric acid in that fluid (§ 262). 
From putrefying flesh and fibrin, amido-phenylpropionic acid is obtained, as a decomposition- 
product of tyrosin. A part of this is transformed by putrefactive ferments into hydrocinnamic 
acid (phenylpropionic acid). The latter is completely oxidized in the body into benzoic acid, 
and appears as hippuric acid in the urine. Thus is explained the formation of hippuric acid 
from a purely albuminous diet. 
Skatol (C9H9N = methylindol) is a constant human faecal substance, and 
has been prepared artificially by Nencki and Secretan from egg-albumin, by 
allowing it to putrefy for a long time under water. It also appears in the urine 
as a sulphur compound. The excretin of human faeces, described by Marcet, 
is related to cholesterin, but its history and constitution are unknown. 
According to Salkowski, skatol and indol are both formed from a common substance which 
exists preformed in albumin, and which, when it is decomposed, at one time yields more indol, 
at another skatol, according as the hypothetical (‘indol fungus,” or “skatol fungus,” is the more 
abundant. 
It is of the utmost importance, in connection with the processes of putrefac- 
tion, to determine whether they take place when oxygen is excluded, or not. Sec. 184.] 
PROCESSES IN THE LARGE INTESTINE. 
353 
When O is absent, reductions take place; oxy-acids are reduced to fatty 
acids, and hydrogen, marsh-gas, and H2S are formed ; while the H may pro- 
duce further reductions. If O be present, the nascent H separates the mole- 
cule of free ordinary oxygen (= 02) into two atoms of active oxygen (= O). 
Water is formed on the one hand, while the second atom of O is a powerful 
oxidizing agent (.Hoppe-Seyler). 
It is remarkable that the putrefactive processes, after the development of phenol, indol, skatol, 
cresol, phenylpropionic and phenylacetic acids are subsequently limited, and after a certain con- 
centration of the fluid with these bodies is reached, the putrefactive processes cease altogether. 
The putrefactive process produces antiseptic substances which kill the micro-organisms, so we 
itiay assume that these substances limit to a certain extent the putrefactive processes in the 
intestine. 
The reaction of the small intestine immediately below the stomach is 
acid, but the pancreatic and intestinal juices cause a neutral and afterwards an 
alkaline reaction, which obtains along the whole small intestine. In the large 
intestine, the reaction of its wall is alkaline, but the contents are generally 
acid, on account of the acid fermentation and the decomposition of the ingesta 
and the faeces. 
[Role of micro-organisms in the intestine.—It is to be remembered 
that micro-organisms exist throughout the entire intestinal tract. Numerous 
microbes have been found in the saliva (p. 260), stomach (p. 358), and small 
intestine (p. 349). From the normal intestinal mucus Babes has isolated five 
species of bacteria, while an enormous number of micro-organisms exist in the 
large intestine and faeces (p. 356). Vignal calculates their number at 20 
millions per decigram of faeces. All these organisms resist the action of the 
digestive juices, save a few which are dissolved by the gastric juice. 
The researches of Duclaux, Vignal, and others have shown that certain of 
these micro-organisms secrete soluble ferments identical in their action with 
the ferments of the digestive juices. Vignal states that certain of these organ- 
isms contribute to the dissolution of food in the intestine. It is certain that 
they contribute to many processes of fermentation and decomposition which go 
on in the intestine. During foetal life these organisms are wanting, but they 
are numerous a few days after birth (Beaunis). In this connection one cannot 
fail to remember that bacteria by their action can produce in albuminous fluids 
albumoses and peptones, and that the former bodies are now regarded by bac- 
teriologists as substances which play an important role in many pathological 
processes.] 
185. PROCESSES IN THE LARGE INTESTINE.—Within the 
large intestine, the fermentative and putrefactive processes are certainly more 
prominent than the digestive processes proper, as only a very small amount 
of the intestinal juice is found in it. The absorptive function of the large 
intestine is greater than its secretory function, for at the beginning of the colon 
its contents are thin and watery, but in the further course of the intestine they 
become more solid. Water and the products of digestion in solution are not 
the only substances absorbed, but under certain circumstances, unchanged fluid 
egg-albumin, milk and its proteids, flesh juice, solution of gelatin, myosin with 
common salt, may also be absorbed. Experiments with acid-albumin, syntonin, 
or blood-serum gave no result. Toxic substances are certainly absorbed more 
rapidly than from the stomach. [In the dog the secretion of the large intestine 
has no digestive properties, but fats are absorbed in it. Klug and Koreck 
regard its Lieberkiihnian glands not as secreting- but as absorbing-structures.] 
The fecal matters are formed or rather shaped in the lower part of the gut. 354 
THE COMPOSITION OF F/ECES. 
[Sec. 185. 
The caecum of many animals, e.g., rabbit, is of considerable size, and in it 
fermentation seems to occur with considerable energy, giving rise to an acid- 
reaction. In man, the chief function of the caecum is absorption, as is shown 
by the great number of lymphatics in its walls. From the lower part of the 
small intestine and the caecum onwards, the ingesta assume the faecal odor. 
[Heidenhain found that in an excised loop of intestine, as in a Vella’s fistula, but where the 
two ends of the loop were stitched together and returned to the abdomen, after several weeks 
the closed loop of gut was found to contain a faecal-like mass. It is evident, therefore, that the 
secretion of the large intestine must contribute matters to the faeces.] 
The amount of faeces is about [5 oz. or] 170 grms. (60 to 250 grins.*) 
in twenty-four hours; but if much indigestible food be taken, it may be as 
much as 500 grms. The amount is less, and the absolute amount of solids 
is less, after a diet of flesh and albumin, than after a vegetable diet. The 
faeces are rendered lighter by the evolution of gases, and hence they float in 
water. 
The consistence depends on the amount of water present—usually about 
75 per cent. The amount of water depends partly on the food—pure flesh diet 
causes relatively dry faeces, while substances rich in sugar yield faeces with a 
relatively large amount of water. The quantity of water taken has no effect 
upon the amount of water in the faeces. But the energy of the peristalsis has. 
The more energetic the peristalsis is, the more watery the faeces are, because 
sufficient time is not allowed for absorption of the fluid from the ingesta. 
Paralysis of the blood- and lymph-vessels, or section of the nerves, leads to a 
watery condition of the faeces (§ 183). 
The reaction is often acid, in consequence of lactic acid being developed 
from the carbohydrates of the food. Numerous other acids produced by putre- 
faction are also present (§ 184). If much ammonia be formed in the lower 
part of the intestine, a neutral or even alkaline reaction may obtain. A copious 
secretion of mucus favors the occurrence of a neutral reaction. 
The odor, which is stronger after a flesh diet than after a vegetable diet, is 
caused by some faecal products of putrefaction, which have not yet been 
isolated; also by volatile fatty acids and by sulphuretted hydrogen, when they 
are present. 
The color of the faeces depends upon the amount of altered bile-pigments 
mixed with them, whereby a bright yellow to a dark brown color is obtained. 
The color of the food is also of importance. If much blood be present in the food, the faeces 
are almost brownish-black from haematin; green vegetables = brownish-green from chlorophyll; 
bones {dog) — white from the amount of lime; preparations of iron = black from the forma- 
tion of sulphide of iron. 
The faeces contain— 
(1) The unchanged residues of animal or vegetable tissues used as food; 
hairs, horny and elastic tissues ; most of the cellulose, woody fibres, spiral 
vessels of vegetable cells, gums. 
(2) Portions of digestible substances, especially when these have been 
taken in too large amount, or when they have not been sufficiently broken up 
by chewing. Portions of muscular fibres, ham, tendon, cartilage, particles of 
fat, coagulated albumin—vegetable cells from potatoes and other vegetables, 
raw starch, etc. (fig. 245). 
All food yields a certain amount of residue—white bread, 3.7 per cent.; rice, 4.1 per cent; 
flesh, 4.7 per cent.; potatoes, 9.4 per cent.; cabbage, 14.9 per cent.; black bread, 15 per cent.; 
yellow turnip, 20.7 per cent. (Rubner). Sec. 185.] 
MICRO-ORGANISMS OF THE FA5CES. 
355 
(3) The decomposition-products of the bile-pigments, which do not now 
give Gmelin’s 
reaction; as 
well as the al- 
tered bile-acids 
(§177,2). This 
reaction, how- 
ever, may be ob- 
tained in patho- 
logical stools, 
especially in 
those of a green 
color; unaltered 
bilirubin, bili- 
verdin, glyco- 
cholic and tau- 
rocholic acids 
occur in meco- 
nium (§ 182). 
[MacMunn found 
no unchanged bile- 
pigments in the 
faeces. A substance called stercobilin is obtained from the faeces, and it closely resembles what 
has been called “ febrile” urobilin, but it is certainly different from normal urobilin.] 
(4) Unchanged mucin and nuclein—the latter occasionally after a diet 
of bread, together with partially disintegrated cylindrical epithelium from the 
intestinal canal, and occasionally drops of oil. Cholesterin is very rare. [Ten 
grains of a substance, stercorin, said to be a modification of cholesterin, occur 
in the faeces (Flint).] The less the mucus is mixed with the faeces, the lower 
the part of the intestine from which it is derived (Nothnagel). 
(5) After a milk diet, and also after a fatty diet, crystalline needles of lime 
combined with fatty acids and chalk soaps constantly occur, even in sucklings 
( Wegscheider). Even unchanged masses of casein and fat occur during the 
milk cure. Compounds of ammonia, with the acids mentioned as the result of 
putrefaction (§ 184, III), belong to the faecal matters (Brieger). 
(6) Amongst inorganic residues, soluble salts rarely occur in the faeces 
because they diffuse readily, e. g., common salt, and the other alkaline chlo- 
rides, the compounds of phosphoric acid, and some of those of sulphuric acid. 
The insoluble compounds—of which ammoniaco-magnesic or triple phos- 
phate (fig. 245, k), neutral calcic phosphate, yellow-colored lime salts, calcium 
carbonate, and magnesium phosphate are the chief—form 70 per cent, of the 
ash. Some of these insoluble substances are derived from the food, as lime 
from bones, and in part they are excreted after the food has been digested, as 
ashes are eliminated from food which has been burned. 
Concretions.—The excretion of inorganic substances is sometimes so great that they form 
incrustations around other faecal matters. Usually ammoniaco-magnesic phosphate occurs in 
large crystals by itself, or it may be mixed with magnesium phosphate. 
(7) Micro-organisms.—A considerable portion of normal faecal matter 
consists of micrococci and microbacteria ; yeast is seldom absent (Frerichs, 
Nothnagel'). 
To isolate the individual fungi, Escherich has made pure cultivations from the intestinal 
contents of sucklings, and Bienstock from adults. In the intestine of sucklings which have 
been nourished entirely on their mother’s milk, the Bacterium lactis aerogenes (fig. 246, 2) 
Faeces, a, muscular fibres ; b, tendon ; c, epithelium; d, leucocytes; e-i, 
different forms of vegetable cells and between the whole numerous bac- 
teria, /. Between h and b, yeast; k, triple phosphate. 
Fig. 245. 356 
PATHOLOGY OF THE DIGESTIVE PROCESSES. 
[Sec. 185. 
causes the lactic acid fermentation and the evolution of C02 and H, in the upper part of 
the canal where some milk-sugar is still unabsorbed. In the evacuations is the characteristic 
1, Bacterium coli commune; 2, bacterium lactis aerogenes; 3 and 4, the large bacilli of 
Bienstock, with partial endogenous spore-formation; 5, the various stages in the develop- 
ment of the bacillus which causes the fermentation of albumin. 
Fig. 246. 
slender Bacterium coli commune (fig. 246, 1). In addition, occasionally there are other 
bacilli, cocci, spores of yeast, and a mould. 
MOUTH & (ESOPHAGUS 
ALKALINE 
STOMACH 
ACID 
SMALL INTESTINE 
ALKALINE 
LARGE INTESTINE 
ALKALINE 
In the fasces of an adult, Bienstock detected two 
large forms of bacilli (fig. 246, 3, 4), closely 
resembling Bacillus subtilis in form and size, but 
distinguished from it only by the form of its pure 
cultivation, by the mode of growth of its spores, 
and by the absence of movements. These two forms 
can be distinguished microscopically by the mode of 
their cultivation, which is either in the form of a 
grape or a flat membrane. These two do not excite 
a fermentative action. A third micrococcus-like, 
small, very slowly-developing bacillus occurs in three-fourths of all stools. A fourth kind 
(absent in sucklings) is the specific bacillus (§ 184, III), causing the decomposition of albumin, 
resulting in the products of putrefaction and a fecal odor. This is the only bacillus that 
excites these processes in the intestine; but it does not decompose casein and alkali-albumin. 
In fig. 246, 5, a-g, the stages in the development of this bacillus are represented, but the 
stages from c to g are absent in the feces, and are found only in artificial cultivations. 
If the feces are simply investigated microscopically and without special precautions, there 
are other fungi, some of which may be introduced through the anus. In stools that contain 
much starch, the bacillus butyricus, which is tinged blue with iodine, occurs ($ 184), and other 
small globular or rod-like fungi, which give a similar reaction (Nothnagel, Uffelmann). 
The changes of the intestinal contents have been studied on persons with an accidental 
intestinal fistula, or an artificial anus. 
[The preceding scheme (fig. 247), from Krukenberg shows graphically the reaction of the 
contents of the various parts of the alimentary canal, and also the distribution of the fer- 
ments.] , 
186. PATHOLOGICAL VARIATIONS.—A. The taking of food may be interfered 
with by spasm of the muscles of mastication (usually accompanied by general spasms), stricture 
of the oesophagus, by cicatrices after swallowing caustic fluids (e. g., caustic potash, mineral 
acids), or by the presence of a tumor, such as cancer. Inflammation of all kinds in the mouth 
or pharynx interferes with the taking of food. Inability to swallow occurs as part of the general 
phenomena in disease of the medulla oblongata, in consequence of paralysis of the motor centre 
(superior olives) for the facial, vagus, and hypoglossal nerves, and also for the afferent or 
sensory fibres of the glosso-pharyngeal, vagus, and trigeminus. Stimulation or abnormal 
excitation of these parts causes spasmodic swallowing, and the disagreeable feeling of a con- 
striction in the gullet (globus hystericus). 
Amylolytic ferment 
Milk coagulating ferment 
Pepsin 
Trypsin 
Bacteria 
Fig. 247. 
Reaction of the contents of the 
intestinal tract. Sec. 186.] 
PATHOLOGY OF GASTRIC DIGESTION. 
357 
B. The secretion of saliva is diminished during inflammation of the salivary glands ; 
occlusion of their ducts by concretions (salivary calculi); also by the use of atropin, daturin, 
and during fever, whereby the secretory (not the vaso-motor) fibres of the chorda appear to be 
paralyzed (§ 145). When the fever is very high, no saliva is secreted. The saliva secreted 
during moderate fever is turbid and thick and usually acid. As the fever increases, the diastatic 
action of the saliva diminishes. The secretion is increased by stimulation of the buccal 
nerves (inflammation, ulceration, trigeminal neuralgia), so that the saliva is secreted in great 
quantity. Mercury and jaborandi cause secretion of saliva, the former causing stomatitis, which 
excites the secretion of saliva reflexly. Even diseases of the stomach accompanied by vomit- 
ing cause secretion of saliva. A very thick tenacious sympathetic saliva occurs when there is 
violent stimulation of the vascular system during sexual excitement, and also during certain 
psychical conditions. The reactior* of the saliva is acid in catarrh of the mouth ; in fever, in 
consequence of decomposition of the buccal epithelium ; and in diabetes mellitus, in consequence 
of acid fermentation of the saliva which contains sugar. Hence, diabetic persons often suffer 
from carious teeth. Unless the mouth of an infant be kept scrupulously clean, the saliva is apt 
to become acid. 
C. Disturbances in the activity of the musculature of the stomach may be due to paralysis 
of the muscular layers, whereby the stomach becomes distended, and the ingesta remain a long 
time in it. A special form of paralysis of the stomach is due to non-closure of the pylorus 
(.Ebstein). This may be due to disturbances of innervation of a central or peripheral nature, 
or there may be actual paralysis of the pyloric sphincter, or anaesthesia of the pyloric mucous 
membrane, which acts reflexly upon the sphincter muscle; and lastly, it may be due to the 
reflex impulse not being transferred to the efferent fibre within the nerve-centre. Abnormal 
activity of the gastric musculature hastens the passage of the ingesta into the intestine; vomit- 
ing often occurs. 
D. Gastric digestion is delayed by violent bodily or mental exercise, and sometimes it is 
arrested altogether. Sudden mental excitement may have the same effect. These efforts are 
very probably caused through the vaso-motor nerves of the stomach. Feeble and imperfect 
digestion may be of a purely nervous nature (Dyspepsia nervosa—Leube ; Neurasthenia gastrica 
—Bur kart). An excessive formation of acid may be due to nervous disturbance, and is called 
“ nervous gastroxynsis,” by P.ossbach. 
[Action of Alcohol, Tea, etc., in Digestion.—According to J. W. Fraser, all infused 
beverages, tea, coffee, cocoa, retard the peptic digestion of proteids, with few exceptions. The 
retarding action is less with coffee than with tea. The tannic acid and volatile oil seem to 
be the retarding ingredients in teas. Distilled spirits—brandy, whisky, gin—have but a 
trifling retarding effect on the digestive processes; and when one considers their action on the 
secretory glands, it follows that in moderate dietetic doses they promote digestion. Wines are 
highly inimical to salivary digestion, but this is due to their acidity; and this effect can be 
removed by the addition of an alkali. Wines retard peptic digestion, the sparkling less than the 
still wines. Tea has an intensely inhibitory action on salivary digestion; in fact, a small 
quantity paralyzes the action of saliva, while coffee has only a slight effect. This action of tea 
is due to the tannin. Tea, coffee, and cocoa all retard peptic digestion, when they form 20 per 
cent, of the digestive mixture (W. Roberts).'] 
[Action of Bile on Gastric Digestion.—The passage of bile into the stomach in cases of 
gastric fistula in man, or the introduction of large quantities of bile into the stomach of dogs, 
contrary to what is usually stated, does not interfere with the gastric digestion of proteids 
(.Herzen, Dastre, Oddi). Bile, however, added to artificial digests retards the process (p. 305).] 
Inflammatory or catarrhal affections of the stomach, as well as ulceration and new forma- 
tions, interfere with digestion, and the same result is caused by eating too much food which is 
difficult of digestion, or taking too much highly spiced sauce or alcohol. In the case of a dog 
suffering from chronic gastric catarrh, Griitzner observed that the secretion took place continuously, 
and that the gastric-juice contained little pepsin, was turbid, sticky, feebly acid, and even alka- 
line. The introduction of food did not alter the secretion, so that in this condition the stomach 
really obtains no rest. The chief cells of the gastric-glands were turbid. Hence, in gastric 
catarrh, we ought to eat frequently, but take little at a time, while at the same time dilute hydro- 
chloric acid ought to be administered (0.4 per cent.). Small doses of common salt seem to aid 
digestion. 
[Absence of HC1.—HC1 is almost always absent in carcinoma of the stomach (van de 
Velde), amyloid degeneration of the gastric mucous membrane (Edinger), and sometimes in 
fever. In all these cases the acid-reaction is due to lactic or butyric acid.] The absence of HC1 
in cancer of the stomach is an important diagnostic and prognostic symptom. It is not absent in 
simple dilatation of the stomach. Test the contents of the stomach for free HC1 with tropseolin 
(red color), methyl-violet (blue), and with ferric chloride and carbolic acid (Uffelmann). 
per cent, of free HC1 causes the amethyst-blue of the last to become steel-grey, while somewhat 
more discharges the color altogether. [In testing for the presence of free lactic acid in the 
gastric contents use Uffelmann’s reaction ($ 163). The lactic acid is easily extracted by ether 358 
PATHOLOGY OF GASTRIC DIGESTION. 
[Sec. 186. 
from the gastric contents, and the reaction can then be performed with the residue obtained after 
evaporating the ether. A solution of I drop of the liquor perchloride in 50 c.c. of water is made 
yellow by lactic acid.] 
Feeble digestion may be caused either by imperfect formation of acid or pepsin, so that both 
substances may be administered in such a condition. [It may also be due to deficient muscular 
power in the wall of the stomach.] In other cases, lactic, butyric, and acetic acids are formed, 
owing to the presence of lowly organisms. In such cases, small doses of salicylic acid, together 
with some hydrochloric acid, are useful. Pepsin need not be given often, as it is rarely absent, 
even from the diseased gastric mucous membrane. Albumin has been found in the gastric-juice 
in cases of gastric catarrh and cholera. 
E. Digestion during Fever and Anaemia.—Beaumont found that in the case of Alexis St. 
Martin, when fever occurred, a small amount of gastric-juice was secreted; the mucous 
membrane was dry, red, and irritable. Dogs suffering from septicaemic fever, or rendered 
anaemic by great loss of blood, secrete gastric-juice of feeble digestive power and containing 
little acid (Manasseln). [In acute diseases accompanied by fever, the inner cells of the fundus- 
glands of the human stomach may disappear (C. Kupffer).~\ Hoppe-Seyler investigated the 
gastric-juice of a typhus patient, in which van de Velde found no free acid. Usually no free 
hydrochloric acid is found in cancer of the stomach. The gastric-juice of the typhus patient 
did not digest artificially, even after the addition of hydrochloric acid. The diminution of acid, 
under these circumstances, favors the occurrence of a neutral reaction, so that, on the one hand, 
digestion cannot proceed, and on the other, fermentative processes (lactic and butyric acid 
fermentations with the evolution of gases) occur. These results are associated with the presence 
of micro-organisms and Sarcina ventriculi (Goodsir). Uffelmann found that the secretion of 
a peptone-forming gastric juice cea«ed in fever, when the fever is severe at the outset, when a 
feeble condition occurs, or when the temperature is very high. The amount of juice secreted is 
certainly diminished during fever. The excitability of the mucous membrane is increased so 
that vomiting readily occurs. The increased excitability of the vaso-motor nerves during fever 
is disadvantageous for the secretion of the digestive fluids (Heidenhain). Beaumont observed 
that fluids are rapidly absorbed from the stomach during fever, but the absorption of peptones is 
diminished on account of the accompanying catarrhal condition of the stomach, and the altered 
functional activity of the muscularis mucosae (Leube). 
Many salts, when given in large amount, disturb gastric digestion, e.g., the sulphates. While 
the alkaloids, morphia, strychnia, digitalin, narcotin, veratria have a similar action, quinine 
favors it ( Wolberg). In some nervous individuals “ peristaltic unrest of the stomach,” conjoined 
with a dyspeptic condition, occurs (Kussman). [Prosser James directs attention to the value of 
peptic and pancreatic salts, which are preparations of common salt mixed with pepsin and the 
ferments of the pancreas respectively.] 
[Artificial Digestion is affected by various salts, according to their nature and dilution. The 
digestion of fibrin by pepsin goes on best without the addition of salts, being diminished by 
magnetic sulphate, sodic carbonate, and sulphate. The digestion of fibrin by pancreatic extract 
is accelerated by sodic carbonate (Heidenhain), and retarded by MgS04 and Na2S04. The 
diastatic action of the saliva and pancreas on starch is greatly accelerated by NaCl (2 per cent.), 
while Na2C03,Na2S04, and MgS04, hinder it (Pfeiffer).] According to Schiitz, artificial gastric 
digestion is retarded by a 2 per cent, solution of alcohol, and also by a solution of salicylic acid 
(.06 to .1 per cent.). Buchner, however, finds that 10 per cent, of alcohol does not affect artificial 
gastric digestion, while above 20 per cent, arrests it. Beer hinders digestion. 
F. In acute diseases, the secretion of bile is affected ; it becomes less in amount and more 
watery, i. e., it contains fewer specific constituents. If the liver undergoes great structural 
change, the secretion may be arrested. 
G. Gall-Stones.—When decomposition of the bile occurs, gall-stones are formed in the gall- 
bladder or in the bile-duds. Some are white, and consist almost entirely of stratified layers of 
crystals of cholesterin. The brown forms consist of bilrubin-lime, and calcium carbonate, often 
mixed with iron, copper, and manganese. The gall-stones in the gall-bladder become facetted 
by rubbing against each other. The nucleus of the white stones often consists of chalk and bile- 
coloring matters, together with nitrogenous residues, derived from shed epithelium, mucin, bile- 
salts, and fats. Gall-stones may occlude the bile-duct and cause cholsemia. When a small stone 
becomes impacted in a duct, it gives rise to excessive pain, constituting hepatic colic, and may 
even cause rupture of the bile-duct with its sharp edges. 
H. Nothing certain has been determined regarding the pancreatic secretion in disease, but 
in fever it appears to be diminished in amount and digestive activity. The suppression of the 
pancreatic secretion, as by a cancerous tumor of the head of the pancreas, is often accompanied 
by the appearance of fat, in the form of globules or groups of crystals in the faeces. 
I. Constipation is a most important derangement of the digestive tract. It may be caused 
by—(1) Conditions which obstruct the normal channel, e.g., constriction of the gut from stricture 
—in the large gut after dysentery, tumors, rotation on its axis of a loop of intestine (volvulus), 
or invagination, occlusion of a coil of gut in a hernial sac, or by the pressure of tumors or Sec. 186.] 
PATHOLOGY OF DIARRHOEA. 
359 
exudations from without, or congenital absence of the anus. (2) Too great dryness of the con- 
tents, caused by too little water in the articles of diet, diminution of the amount of the digestive 
secretions, e.g., of bile in icterus; or in consequence of much fluid being given off by other 
organs as after copious secretion of saliva, milk, or in fever. (3) Variations in the functional 
activity of the muscles and motor-nervous apparatus of the gut may cause constipation, owing to 
imperfect peristalsis. This condition occurs in inflammations, degenerations, chronic catarrh, and 
diaphragmatic inflammation. Affections of the spinal cord, and sometimes also of the brain, 
are usually accompanied by slow evacuation of the intestine. Whether diminished mental 
activity and hypochondriasis are the cause of, or are caused by, constipation is not proved. 
Spasmodic contraction of a part of the intestine may cause temporary retention of the intestinal 
contents, and, at the same time, give rise to great pain or colic; the same is true of spasm of 
the anal sphincter, which may be excited reflexly from the lower part of the gut. The faecal 
masses in constipation are usually hard and dry, owing to the water being absorbed; hence they 
form large masses or scybala within the large intestine, and these again give rise to new resist- 
ance. Amongst the reagents which prevent evacuation of the bowels, some paralyze the motor 
apparatus temporarily, e.g., opium, morphia; some diminish the secretion of the intestinal mucous 
membrane, and cause constriction of the blood-vessels, as tannic acid, vegetables containing 
tannin, alum, chalk, lead acetate, silver nitrate, bismuth nitrate. 
J. Increased evacuation of the intestinal contents is usually accompanied by a watery condition 
of the faeces, constituting diarrhoea. The causes are:— 
1. A too rapid movement of the contents through the intestine, chiefly through the large 
intestine, so that there is not time for the normal amount of absorption to take place. The 
increased peristalsis depends upon stimulation of the motor-nervous apparatus of the intestine, 
usually of a reflex nature. Rapid transit of the contents through the intestine causes the evacu- 
ation of certain substances, which cannot be digested in so short a time. 
2. The stools become thinner from the presence of much water, mucus, and the admixture 
with fat, and by eating fruit and vegetables. In rare cases, when the evacuations contain much 
mucin, Charcot’s crystals occur (fig. 171, f). In ulceration of the intestine, leucocytes (pus) are 
present (Notknagel). 
3. Diarrhoea may occur as a consequence of disturbance of the diffusion-processes through the 
intestinal walls, as in affections of the epithelium, when it becomes swollen in inflammatory or 
catarrhal conditions of the intestinal mucous membrane. [Irritation over the abdomen, as from 
the subcutaneous injection of small quantities of saline solutions, causes diarrhoea.] 
4. It may also be due to increased secretion into the intestine, as in capillary diffusion, when 
magnesium sulphate in the intestine attracts water from the blood. 
The same occurs in cholera, when the stools are copious and of a rice-water character, and are 
loaded with epithelial cells from the villi. The transudation into the intestine is so great that 
the blood in the arteries becomes very thick, and may even on this account cease to circulate. 
Transudation into the intestine also takes place as a consequence of paralysis of the vaso- 
motor nerves of the intestine. This is perhaps the case in diarrhoea following upon a cold. 
Certain substances seem directly to excite the secretory organs of the intestines or their nerves, 
such as the drastic purgatives (| 180). Pilocarpin injected into the blood causes great secretion 
fMasloff). 
During febrile conditions, the secretion of the intestinal glands seems to be altered quanti- 
tatively and qualitatively, with simultaneous alteration of the functional activity of the muscu- 
lature and the organs of absorption, while the excitability of the mucous membrane is increased 
(Uffelmann'). It is important to note that in many acute febrile diseases the amount of common 
salt in the urine diminishes, and increases again as the fever subsides. 
187. COMPARATIVE.—Salivary Glands.—Amongst mammals, the herbivora have 
larger salivary glands than the carnivora; while midway between both are the omnivora. The 
whale has no salivary glands. The pinnipedia have a small parotid, which is absent in echidna. 
The dog and many carnivora have a special gland lying in the orbit, the orbital or zygomatic 
gland. In birds the salivary glands open at the angle of the mouth, but the parotid is absent. 
Amongst reptiles the parotid of some species is so changed as to form poison-glands; the 
tortoise has sublingual glands; reptiles have labial glands. The amphibia and fishes have 
merely small glands scattered over the mouth. The salivary glands are large in insects ; some 
of them secrete formic acid. The salivary glands are well developed in molluscs, and the saliva 
of Dolium galea contains more than 3 per cent, of free sulphuric acid (?). The cephalopods 
have a double set of glands. 
A crop is not present in any mammal; the stomach is either simple, as in man, or, as in 
many rodents, it is divided into two halves, into a cardiac and a pyloric portion. The intestine 
is short in flesh-eating animals and long in herbivora. The stomach of ruminants is compound, 
and consists of four cavities. The first and largest is the paunch or rumen, then the reticulum. 
In these two cavities, especially the former, the ingesta are softened and undergo fermentation, 
they are then returned to the mouth by the action of the voluntary muscular fibres, which reach [Sec. 187. 
360 
COMPARATIVE PHYSIOLOGY OF DIGESTION. 
to the stomach. This is the process of rumination. The ingesta are chewed again in the 
mouth, and are again swallowed, but this time they enter the third cavity or psalterium— 
(which is absent in the camel)—and thence into the fourth stomach or abomasum, in which 
the fermentative digestion takes place. The caecum is a very large and important digestive 
organ in herbivora and in most rodents; it is small in man, and absent in carnivora. The oeso- 
phagus in grain-eating birds not unfrequently has a blind diverticulum or crop for softening the 
food. In the crop of pigeons during the breeding season, there is formed a peculiar secretion— 
“ pigeon’s milk,” which is used to feed the young (J. Hunter). The stomach consists of a 
glandular proventricuius and a strong muscular stomach, which is covered with horny epithe- 
lium and triturates the food. There are usually two fluid diverticula on the small intestine near 
where it joins the large gut. In fishes the intestinal canal is generally simple; the stomach is 
merely a dilatation of the tube; and at the pylorus there may be one, but usually many, blind 
glandular appendages (the appendices pyloricae). They are generally longitudinal folds in the 
intestinal mucous membrane, but in some fishes, e.g., the shark, there is a spiral valve. [The 
inversive cane-sugar ferment is wanting in the herbivora, as the cow, horse, and sheep, but is 
present in the dog and cat. It is also met with in birds and reptiles, and in many of the inver- 
tebrates, as the ordinary earth-worm (M. Hay). 
In amphibia and reptiles the stomach is a simple dilatation ; the gut is larger in vegetable 
feeders than in flesh feeders. The liver is never absent in vertebrates, although the gall-bladder 
frequently is. [It is absent in the donkey, horse, elephant, and deer.] The pancreas is absent 
in some fishes. 
Digestion in Plants.—The observations on the albumin-digesting power of some plants are 
extremely interesting (Canby, 1869; Ch. Darwin, 1875). The sundew or drosera has a series 
of tentacles on the surface of its leaves, and the tentacles are provided with glands. When an 
insect alights upon a leaf, it is suddenly seized by the tentacles ; the glands pour out an acid 
juice over the prey, which is gradually digested, all except the chitinous structures. The secre- 
tion, as well as the subsequent absorption of the products of digestion, are accomplished by the 
activity of the protoplasm of the cells of the leaves. The digestive juice contains a pepsin-like 
ferment and formic acid. Similar phenomena are manifested by the Venus flytrap (Dionaea), 
by pinguicula, as well as by the cavity of the altered leaves of Nepenthes. About fifteen species 
of these “insectivorous” or carnivorous plants are known. Papain, and other ferments analo- 
gous in their action to trypsin, are referred to in § 170. 
188. HISTORICAL.—Digestion in the Mouth.—The older observers regarded the 
saliva as a solvent, and in addition, many bad qualities, especially in starving animals, were 
ascribed to it. This arose from the knowledge of the saliva of mad animals, and the parotid 
saliva of poisonous snakes. The salivary glands have been known for a long time. Galen 
(131-203 A.D.) was acquainted with Wharton’s duct and Aetius (270 A.D.) with the sub-maxil- 
lary and sub-lingual glands. Hapel de la Chenaye (1780) obtained large quantities of saliva 
from a horse, in which he was the first to make a salivary fistula. Spallanzani (1786) asserted 
that food mixed with saliva was more easily digested than food moistened with water. Ham- 
berger and Siebold investigated the reaction, consistence, and specific gravity of saliva, and 
found in it mucus, albumin, common salt, calcium and sodium phosphates. Berzelius gave the 
name ptyalin to the characteristic organic constituent of saliva, but Leuchs (1831) was the first 
to detect its diastatic action. 
Gastric Digestion.—Digestion was formerly compared to “ coction,” whereby solution was 
effected. According to Galen, only substances that have been dissolved passed through the 
pylorus into the intestine. He described the movements of the stomach and the peristalsis of the 
intestines. Aelian gave names to the four stomachs of the ruminants. Vidius (f 1567) noticed 
the numerous small apertures of the gastric glands. Van Helmont (f 1644) expressly notices 
the acidity of the stomach. Reaumur (1752) knew that a juice was secreted by the stomach, 
which effected solution, and with which he and Spallanzani performed experiments on digestion 
outside the body. Carminati (1785) found that the stomachs of carnivora during digestion 
secreted a very acid juice. Prout (1824) discovered the hydrochloric acid of the gastric-juice. 
Sprott and Boyd (1836) the glands of the gastric mucous membrane, while Wassmann and 
Bischoff noted the two kinds of gastric-glands. After Beaumont (1834) had made his obser- 
vations upon Alexis St. Martin, who had a gastric fistula caused by a gunshot wound, Bassow 
(1842) and Blondlot (1843) made the first artificial gastric-fistulae upon animals. Eberle (1830) 
prepared artificial gastric juice. Miallie called albumin, when altered by gastric digestion, 
albuminose ; Lehmann, who investigated this substance more carefully, gave it the name peptone. 
Schwann isolated pepsin (1836), and established the fact of its activity in the presence of hydro- 
chloric acid. 
Pancreas, Bile, Intestinal Digestion.—The pancreas was known to the Hippocratic 
School ; Maur. Hoffmann demonstrated its duct (fowl), and Wirsung described it in 
man. Regner de Graaf (1664) collected the pancreatic juice from a fistula, and Tiedemann and 
Gmelin found it to be alkaline, while Lauret and Lassaigne found that it resembled saliva. Sec. 188.] 
HISTORICAL ACCOUNT OF DIGESTION. 
361 
Valentin discovered its diastatic action, Eberle its emulsionizing power, and Cl. Bernard (1846) 
its tryptic and fat-splitting properties. The last-mentioned function was referred to by Purkinje 
and Pappenheim (1836). Aristotle characterized the bile as a useless secretion; according to 
Erasistratus (304 B. c.), fine invisible channels conduct the bile from the liver into the gall- 
bladder. Aretaeus ascribed icterus to obstruction of the bile-duct. Benedetti (1493) described 
gall-stones. According to Jasolinus (1573), the gall-bladder is emptied by its own contractions. 
Sylvius noticed the lymphatics of the liver (1640); Walaeus, the connective tissue of the so- 
called capsule of Glisson (1641). Halle rindicated the uses of bile in the digestion of fats. The 
liver-cells were described by Henle, Purkinje, and Dutrochet (1838). Heynsius discovered the 
urea and Cl. Bernard (1853) the sugar in the liver, and he and Hensen (1857) found glycogen 
in the liver. Kiernan gave a more exact description of the hepatic blood-vessels (1834). Beale 
injected the lymphatics, and Gerlach the finest bile-ducts. Schwann (1844) made the first 
biliary fistula; Demarcay particularly referred to the combination of the bile-acids with soda 
(1838); Strecker discovered the soda compounds of both acids, and isolated them. Celsus 
mentions nutrient enemata (3-5 A.D.). Fallopius (1561) described the valvulse conniventes and 
villi of the intestinal mucous membrane, and the nervous plexus of the mesentery. The 
agminated glands or patches of Peyer were known to Severinus (1645). Physiology of Absorption. 
i8g. THE ORGANS OF ABSORPTION.—[As most substances in 
the state in which they are used for food are either insoluble, or diffuse but im- 
perfectly through membranes, the whole drift of the complicated digestive pro- 
cesses is to render these substances soluble and diffusible, and thus fit them 
for absorption ; most of the neutral fats, however, are emulsionized.] 
The mucous membrane of the whole intestinal tract, as far as it is covered 
by a single layer of columnar epithelium, i. e., from the cardiac orifice of the 
stomach to the anus—is adapted for absorption. The mouth and oesophagus, 
lined as they are by stratified squamous epithelium, are much less adapted for 
this purpose. Still, poisoning is caused by placing potassium cyanide in the 
mouth. The channels of absorption in the intestinal tract are—(i) the capil- 
laries [direct], and (2) the lacteals [indirect] of the mucous membrane (fig. 
248). Almost the whole of the substances 
absorbed by the former pass into the rootlets 
of the portal vein, and traverse the liver, before 
they reach the general circulation, while those 
that enter the lacteals really pass into lym- 
phatics, so that the chyle passes through the 
thoracic duct and is poured by it into the 
blood, where the thoracic duct joins the sub- 
clavian vein (fig. 172). 
Watery solutions of salts, grape-sugar, pep- 
tone, poisons, and in a still higher degree 
alcoholic solutions of poisons, are absorbed in 
the stomach. The empty stomach absorbs 
more rapidly than one filled with food ; gastric 
catarrh delays absorption. After a copious 
diet of milk, fatty granules have been found 
in the protoplasm of the goblet-cells; so that, 
according to this view, the goblet-cells have a double function, to secrete mucus 
and to absorb nutriments. 
The greatest area of absorption is undoubtedly the small intestine, espe- 
cially its upper half, owing to the presence of the valvulae conniventes and 
the villi. 
[Absorption takes place all along the intestine—but in the case of the fats 
this is strictly confined to the small intestine, where indeed all absorption is 
most active. We might classify the various sections of the intestinal canal, as 
far as regards their activity of absorption, as follows:—small intestine, large in- 
testine, stomach, mouth, pharynx, oesophagus (Beaunis).] 
190. STRUCTURE OF THE SMALL AND LARGE INTES- 
TINES.—[The wall of the small intestine consists of four coats ; which, 
from without inward, are named serous, muscular, sub-mucous, and 
mucous (fig. 249).], 
Fig. 248. 
Scheme of intestinal absorption. LAC., 
lacteals; T.D., thoracic duct; P.V., 
and H.V., portal and hepatic veins; 
INT., intestine. Sec. 190.] 
363 
(1) The serous coat has the same structure as the peritoneum, i. <?., a thin 
basis of fibrous tissue covered on its outer surface by endothelium. 
(2) The muscular coat consists of a thin outer longitudinal and an 
inner thicker circular layer of non-striped muscular fibres (fig. 249). 
(3) The sub-mucous coat consists of loose connective tissue containing 
large blood-vessels, lymphatics, and nerves, and it connects the muscular with 
the mucous coat. 
(4) The mucous coat is the most internal coat, and its absorbing surface is 
largely increased by the presence of 
the valvulae conniventes and villi. 
[The valvulae conniventes are 
permanent folds of the mucous mem- 
brane of the small intestine, arranged 
across the long axis of the gut. They 
pass round a half or more of the inner 
surface of the gut. They begin a 
little below the commencement of 
the duodenum, and are large and well 
marked in the duodenum, and re- 
main so as far as the upper half of 
the jejunum, where they begin to 
become smaller, and finally disap- 
pear about the lower part of the 
ileum.] The villi are characteristic 
of the small intestine, and are con- 
fined to it; they occur everywhere 
as closely-set cylindrical projections 
over and between the valvulae con- 
niventes (fig. 249). When the inner 
surface of the mucous membrane is 
examined in water, it has a velvety 
appearance owing to their presence. 
[They vary in length from to 
of an inch, and are largest and most 
numerous in the upper part of the 
intestine, duodenum, and jejunum, 
where absorption is most active, but 
they are less abundant in the ileum. 
Their total number has been calcu- 
lated at four millions by Krause, and 
there are 10-18 on a square mm.] 
Each villus is a projection of the en- 
tire mucous membrane, so that it 
contains within itself representatives 
of all the tissue-elements of the mucosa. The orifices of the glands of Lieber- 
kiihn open between the bases of villi (fig. 249). 
Structure of a Villus.—Each villus, be it cylindrical or conical in shape, 
is covered by a single layer of columnar epithelium, whose protoplasm is 
reticulated and contains a well-defined nucleus with an intranuclear plexus of 
fibrils. The ends of the epithelial cells directed towards the gut are polygonal, 
and present the appearance of a mosaic (fig. 250, D). When looked at from 
the side, their free surface is seen to be covered with a clear,* highly refractive 
disc or “ cuticula,” which is marked with vertical striae. These striae were 
supposed by Kolliker to represent pores for the absorption of fatty particles, 
STRUCTURE OF THE SMALL INTESTINE. 
Villi 
with 
epithe- 
lium. 
Lieber- 
kiihn’s 
glands. 
Muscu- 
laris 
mucosse. 
Sub mucous coat. 
Peyer’s 
patch. 
Circular 
muscle. 
Longi- 
tudinal 
muscle. 
Fig. 249. 
Longitudinal section through a Peyer’s patch 
of the small intestine of a dog. 364 
[Sec. 190. 
STRUCTURE OF A VILLUS. 
but this has not been confirmed, while Brettauer and Steinach regarded them 
as produced by prisms placed side by side. 
[According to Heidenhain, the epithelial cells are devoid of a cell wall, and 
their shape varies with the degree of contraction of the villus. The disc con- 
sists of rods with an intermediate substance, but they appear to be continuous 
with the protoplasm of the cell. Sometimes no disc is to be seen, and in this case 
the rods are retracted. The rods forming the disc may vary much in length. 
Although Heidenhain admits changes in the length of these “rods,” he does 
not ascribe to them an active part in the absorption of fat.] 
According to v. Thanhoffer, however, this clear disc is comparable to the thickened flange 
around the bottom of a vessel, such as is used for collecting gases. On this supposition, the 
upper end of each cell is open, and from it there project pseudopodia-like bundles of protoplas- 
mic processes (fig. 250, B). These processes are supposed to be extended beyond the margin of 
the cell, and again rapidly retracted, and in so acting they are said to carry the fatty particles into 
A, scheme of a transverse section ot part of a villus; a, columnar epithelium with; b, clear 
disc ; c, goblet-cell; i, i, adenoid reticulum; d, d, spaces containing leucocytes, e, e,; f 
section of the central lacteal. B, scheme of a cell with processes projected from its interior. 
C, columnar epithelium after the absorption of fatty granules. D, columnar epithelium of a 
villus seen from above with a goblet-cell in the centre. 
Fig. 250. 
the interior of the cells, much as the pseudopodia of an amoeba entangle its food. [This view 
has not been confirmed by a sufficient number of observers.] Between the epithelial cells are 
the so-called goblet-cells (fig. 250, C). [Each goblet-cell is more or less like a chalice, nar- 
rower above and below, and broad in the middle, with a tapering fixed extremity. The outer 
part of these cells is filled with a clear substance or mucigen, which, on the addition of water, 
yields mucus. The mucigen lies in the intervals of a fine network of fibrils, which pervades the 
cell-protoplasm, while the protoplasm, containing a globular or triangular nucleus, is pushed into 
the lower part of the cell. These goblet-cells are simply altered columnar epithelial cells which 
secrete mucus in their interior. They are more numerous under certain conditions. Not unfre- 
quently in a section of the mucous membrane of the gut, after it is stained with logwood, we may 
see a deep blue plug of mucus partly exuded from these cells. When looked at from above Sec. 190.] 
STRUCTURE OF A VILLUS. 
365 
they give the appearance seen in fig. 250, D.] The epithelium of the villi is replaced by other 
cells derived from the epithelium of Lieberkiihn’s glands, gradually rising upwards to take the 
place of the shed cells. The epithelial cells are shed in enormous numbers in cholera, and in 
poisoning with arsenic and muscarin [Bohm). 
[The epithelial cells covering the villus are placed upon a layer of squamous 
epithelium (basement membrane)—the sub-epithelial membrane of Debove. 
This basement membrane is said to be connected by processes with the so-called 
branched cells of the adenoid tissue of the villus, while it also sends up pro- 
cesses between the epithelial covering.] 
The stroma or body of the villus itself consists of a basis of adenoid 
tissue, containing in its centre one or more lacteals, closely invested with 
several bundles of longitudinal smooth muscular fibres, derived from the mus- 
cularis mucosae, and a plexus of blood-vessels. The adenoid tissue of the 
villus consists of a reticulum of fibrils with endothelial plates at its nodes. 
The spaces of the adenoid tissue form a spongy network of inter-communica- 
ting channels containing stroma-cells or leucocytes (fig. 250, A, e, e). These 
leucocytes or lymph-corpuscles have been seen to contain fatty granules. 
[The stroma is relatively larger in amount in relation to the epithelium in 
the dog (fig. 259) and cat than in the rabbit and guinea-pig. In the stroma 
are spaces which contain leucocytes of various kinds and phagocytes. Color- 
ation with Biondi’s fluid (p. 389) enables one to single out the varieties of these 
cells, some of which wander out into and between the epithelial cells. The 
spaces also contain a coagulable fluid. The capillaries are arranged close under 
the epithelium (fig. 259, c).] 
The lymphatic or lac- 
teal lies in the axis of the 
villus (fig. 252, d). Some 
regard the lacteal merely as 
a space in the centre of the 
villus, but more probably it 
has a distinct wall composed 
of endothelial cells, with 
apertures or stomata here 
and there between the cell- 
plates. These stomata place 
the interior of the lacteal in 
direct communication with 
the spaces of the adenoid 
tissue. Perhaps white blood- 
corpuscles wander out of the 
blood-vessels of the villi into 
the spaces of the adenoid 
tissue, where they become 
loaded with fatty granules, 
and pass into the central lac- 
teal. Zuwarykin and Wied- 
ersheim suppose that the leu- 
cocytes pass from the paren- 
chyma of the villus towards 
the epithelial layer, and even between the epithelial cells, from which they 
return towards the axis of the villus, laden with substances which they have 
taken into their interior (§ 192, II). [This however is highly doubtful.] 
A small artery placed eccentrically passes into each villus (fig. 251). In 
man it begins to divide about the middle of the villus, but in animals it usually 
runs to the apex before it divides. The capillaries resulting from the division 
of the arterv form a fine dense network Dlaced superficially, immediately under 
Cylindri- 
cal epi- 
thelium. 
Disc on 
the epi- 
thelium. 
Capillary. 
Vein.. 
Artery. 
Injected blood-vessels of a villus. 
Fig- 251. 366 
VILLI AND LIEBERKUHN’S GLANDS. 
[Sec. 190. 
the epithelium of the surface. The blood is carried out. of a villus by one or 
two veins (figs. 251, 252). 
Non-striped muscular 
fibres are present in villi. They 
are arranged longitudinally in 
several bundles from base to apex 
immediately outside the central 
lacteal. [Each bundle is sur- 
rounded by a connective-tissue 
sheath.] When they contract they 
tend to empty the lacteal. A 
few muscular fibres are placed 
more superficially and run in a 
more transverse direction. [The 
longitudinal bundles of non- 
striped muscle in the villi are 
connected together by oblique 
strands; while the longitudinal 
bundles shorten the villus, the 
oblique fibres keep the lacteal 
open ; thus the parenchyma of 
the villus is also compressed 
transversely, whereby the pro- 
ducts of absorption are forced 
into the lacteal. The muscles 
are fixed by cement to the sub- 
epithelial basal membrane. The 
muscular fibres of the villi are 
direct prolongations of the mus- 
cularis mucosae.] 
Nerves pass into the villi 
from Meissner’s plex- 
us lying in the sub- 
mucous coat. The 
nerves to the villi 
are said to have small 
granular ganglionic 
cells in their course, 
and they terminate 
partly in the muscular 
fibres and partly in 
the arteries of the 
villi. 
On making a ver- 
tical section of the 
mucous mem- 
brane of the small 
intestine one sees the 
villi, and under them 
a network of adenoid 
tissue loaded with 
leucocytes. This tis- 
sue forms its basis, 
and in it are placed 
vertically side by side, 
Fig. 252. 
Mucous membrane of the small intestine of the dog; 
the lacteals are black, and the blood-vessels lighter. 
a, artery; b, lymphatic ; c, plexus of capillaries in the 
villi; d, lacteal; e, Lieberkiihn’s glands. 
Villi with blood-vessels injected. Solitary follicle. 
Mucous 
membrane 
with villi. 
Blood 
vessels. 
Muscular 
coat. 
Transverse sectiofi of duodenum of a rabbit injected, x 50. 
F>'g- 253- Sec. 190.] 
lieberkuhn’s and brunner’s glands. 
367 
like test-tubes in a stand, immense numbers of simple tubular glands—the 
crypts or glands of Lie- 
berkiihn (fig. 249).] [Kult- 
schitzki finds that the con- 
nective-tissue framework of 
the mucous membrane of the 
small intestine is not true 
adenoid tissue, but a transi- 
tion form between the latter 
and loose fibrous tissue.] 
Lieberkiihn’s glands open 
above at the bases of the villi, 
while their closed lower ex- 
tremity reaches almost to the 
muscularis mucosae. Each tube 
consists of a basement mem- 
brane lined by a single layer 
of columnar epithelium, leav- 
ing a wide lumen, the cells 
lining them being continuous 
with those that cover the 
mucous membrane. Many of 
the cells exhibit mitotic fig- 
ures, i. e., they are about to 
divide. Some goblet-cells are 
often found between the col- 
umnar epithelium. Immedi- 
ately below the bases of the follicles of Lieberkiihn is the muscularis mucosae, 
consisting of two or 
three narrow layers 
of non-striped mus- 
cular fibres arranged 
circularly and longi- 
tudinally. [Itiscon- 
t i n u o u s with the 
muscularis mucosae 
of the stomach, and 
extends throughout 
the whole intestine, 
not as a continuous 
layer, but as a close 
network of bundles 
of smooth muscle. 
It sends fibres up- 
wards into the villi 
(fig. 254 e).] 
[Brunner’s 
glands are com- 
pound tubular glands 
lying in and con- 
fined to the 
mucous coat of the duodenum (figs. 214, 238). Their ducts perforate the 
muscularis mucosae to open on the surface. They seem to be the homologues 
of the pyloric glands of the stomach (fig. 214).] 
[Solitary Follicles are small round or oval white masses of adenoid tissue 
Fig. 254. 
Section of a solitary follicle of the small intestine (human). 
a, lymph-follicle covered with epithelium (b) ; but the 
villi, c, are denuded of epithelium; d, Lieberkiihn’s 
follicle; e, muscularis mucosae; f, sub-mucous tissue. 
Fig. 255.—Diagram of a vertical section of the mucous membrane of 
the small intestine of a dog, showing, the closed follicles, a a, 
part of a Peyer’s patch; b, muscularis mucosae. 368 
SOLITARY FOLLICLES. 
[Sec. 190. 
(.5-2 mm. in diameter), with their deeper parts embedded in the submucosa, 
and their apices projecting into the mucosa of the intestine. They begin at 
the pyloric end of the stomach, and are found throughout the whole intestine 
—small and large. They consist of small masses of adenoid tissue loaded with 
leucocytes (fig. 254). The small, round, or oval masses at first lie in the 
mucous coat, their apex covered by the epithelium, with few goblet-cells, while 
their outer part rests on the muscularis mucosae. As they develop, they grow 
outwards through the muscularis mucosae, and penetrate into the sub-mucous 
coat, so that they become pear-shaped, the narrow end of the pear being 
Fig. 256.—Scheme of the blood-vessels of the small intestine. Arteries red, veins blue. The 
various coats are shown schematically, s, villi. 
V 
directed towards and covered by the epithelium of the gut. At the same time 
Lieberkiihn’s glands are pressed aside and no villi lie over the follicles. In 
the centre of each is a germ-centre, where the leucocytes often exhibit mitosis. 
Many of the leucocytes wander out between the epithelial cells just as in the 
tonsil. They are well supplied with blood-vessels (§ 197), although no 
lymphatic vessels enter them. They are surrounded by lymphatics, and, in 
fact, they may be said to hang into a lymph-stream. The distribution of 
solitary follicles is fairly uniform in the small intestine; their number generally 
increases from the stomach to the large intestine ; although there are consider- Sec. 190.] 
BLOOD-VESSELS OF THE SMALL INTESTINE. 
369 
able variations in different individuals, there seems to be the same number of 
solitary follicles and Peyer’s patches in the infant as in the adult.] 
[Peyer’s patches, or agminated glands, consist of groups (10-80 or 
more) of lymph-follicles, lying side by side like the foregoing (figs. 249, 255). 
The masses are often more or less fused together, their bases lie in the sub- 
mucosa, while their summits project into the mucosa, where they are covered 
merely by the columnar epithelium of the intestine. The lymph-corpuscles 
often pass between the epithelial cells. The patches so formed have their long 
axis in the axis of the intestine, and they are always placed opposite the attach- 
ment of the mesentery. Like the solitary glands, they are well supplied with 
blood-vessels, while around them is a dense plexus of lymphatics or lacteals. 
They are most abundant in the lower part of the ileum. These glands are 
specially affected in typhoid fever.] 
Epithelium. 
Lieber- 
kiihn’s 
glands. 
Mucous 
membrane. 
Capillary. 
Muscu- 
laris 
mucosae. 
Solitary 
follicle. 
Sub- 
mucous 
coat. 
Circular 
fibres. 
Muscular 
coat. 
Longitudi- 
nal fibres. 
Longitudinal section of the large intestine. 
Fig. 257. 
[Blood-vessels of the Small Intestine (fig. 256).—Branches of the 
mesenteric arteries from between the two layers of the peritoneum reach the 
intestine, and ramify under the serous coat. At intervals they penetrate the 
longitudinal and circular muscular coats, giving off branches of supply to these 
as they pass. Fairly large branches enter the sub-mucous coat and ramify in it, 
and from these fine branches arise, which run vertically, and form a rich plexus 
around Lieberkiihn’s glands, while another branch ascends in each villus as 
already described. The blood is returned by corresponding veins. Mall has 
shown that small capillary venous plexuses exist in the sub-mucous coat. The 
mucous coat is far more vascular than the muscular.] 
[Nerves of the Intestine.—The nerves of the small intestine come 
from the superior mesenteric plexus, and pass along the branches of the superior 370 
STRUCTURE OF THE LARGE INTESTINE. 
[Sec. 190. 
mesenteric artery. The large intestine is supplied by branches from the 
inferior mesenteric and hypogastric plexuses. The, for the most part, non- 
medullated nerve-fibres pass from the vessels to the intestine, where they form 
a plexus under the peritoneal coat of the gut and from this branches penetrate 
the muscular coat to form Auerbach’s plexus. This plexus exists through- 
out the whole intestinal tract, lying between the longitudinal and circular mus- 
cular coats (figs. 205, 206). This plexus, with angular or polygonal meshes, 
consists of non-medullated nerves with groups of multipolar ganglionic cells at 
the nodes. Fibres are given off by it to the muscular coats. Connected by 
branches with the foregoing, and lying in the sub-mucosa, is the plexus of 
Meissner, which is much finer, the meshes being wider, the nodes smaller, 
but also provided with ganglionic cells. It supplies the muscular fibres and 
arteries of the mucosa, including those of the villi. It also sends branches to 
Lieberkuhn’s glands (fig. 207).] 
[Structure of the Large Intestine.—It has four coats, like those of 
the small intestine. The serous coat has the same structure as that of the 
small intestine. The muscular coat has external longitudinal fibres occur- 
ring all round the gut, but they form three flat ribbon-like longitudinal bands 
in the caecum and colon (fig. 257). Inside this coat are the circular fibres. 
The sub-mucosa is practically the same as that of the small intestine. The 
mucosa is distinguished by negative characters. It has no villi and no Peyer’s 
patches, but otherwise it resembles structurally the small intestine, consisting of 
a basis of adenoid tissue with the simple tubular glands of Lieberkiihn (fig. 
239). These glands are very numerous and somewhat longer than those of the 
small intestine, and they always contain far more goblet-cells—about ten times 
as many. The cells lining them are devoid of a clear disc. Solitary glands 
occur throughout the entire length of the large intestine. At the bases of 
Lieberkuhn’s glands is the muscularis mucosae. The blood-vessels and 
nerves have a similar arrangement to those in the stomach.] 
[Blood-Vessels.—On looking down on an opaque injection of the mucous 
membrane of the stomach, one sees a dense meshwork of polygonal areas of 
unequal size, with depressions here and there. The orifices are the orifices of 
the gastric glands, each surrounded by a capillary. A somewhat similar appear- 
ance is seen in an opaque injection of the mucous membrane of the large intes- 
tine, but in the latter the meshwork is uniform, all the orifices (of Lieberkuhn’s 
glands) being of the same size.] 
191. ABSORPTION OF THE DIGESTED FOOD.—The phy- 
sical forces concerned are:—endosmosis, diffusion, and filtration. 
All the constituents of the food, with the exception of the fats, which in part are changed 
into a fine emulsion, are brought into a state of solution by the digestive processes. These 
substances pass through the walls of the intestinal tract, either into the blood-vessels of the 
mucous membrane or into the beginning of the lymphatics. In this passage of the fluids two 
physical processes come into play—endosmosis and diffusion as well as filtration. 
I. Endosmosis and diffusion occur between two fluids which are capable of forming an 
intimate mixture with each other, e.g., hydrochloric acid and water, but never between two fluids 
which do not form a perfect mixture, such as oil and water. If two fluids capable of mixing 
with each other, but of different compositions, be separated from each other by means of a sep- 
tum with physical pores (which occur even in a homogeneous membrane), an exchange of the 
constituents in the fluids occurs until both fluids have the same composition. This exchange of 
fluids is termed endosmosis or diosmosis. 
Diffusion.— If the two miscible fluids are placed in a vessel, the one fluid over the other, 
but without being separated by a porous septum, an exchange of the particles of the fluids also 
occurs, until the whole mixture is of uniform composition. This process is called liquid diffusion. 
Conditions influencing Diffusion.—Graham’s investigations showed that the rapidity of 
diffusion is influenced by—(1) The nature of the fluids themselves; acids diffuse most rapidly; 
the alkaline salts more slowly; and most slowly, fluid albumin, gelatin, gum, dextrin. These 
last do not crystallize, and perhaps do not form true solutions. (2) The more concentrated the Sec. 191.] 
CRYSTALLOIDS, COLLOIDS, AND OSMOSIS. 
371 
solutions, the greater the diffusion. (3) Heat accelerates, while cold retards, the process. (4) 
If a solution of a body which diffuses with difficulty be mixed with an easily diffusible one, the 
former diffuses with still greater difficulty. (5) Dilute solutions of several substances diffuse 
into each other without any difficulty, but if concentrated solutions are employed, the process is 
retarded. (6) Double salts, one constituent of which diffuses more readily than the other,1 may 
be chemically separated by diffusion. 
Endosmometer—The exchange of the fluid particles takes place independently of the 
hydrostatic pressure. An endosmometer (fig. 258) consists of a glass cylinder filled with 
distilled water, and into this is placed a flask, J, without a bottom, instead of which a mem- 
brane, m, is tied on. A glass tube, R, is fixed firmly by means of a cork into the neck of the 
flask. The flask is filled up to the lower end of the tube with a concentrated salt solution, and 
is then placed in the cylindrical vessel until both fluids are on the same level, x. The fluid in 
the tube, R, soon begins to rise, because water passes through the membrane into the concen- 
trated solution in the flask, and this independently of the hydrostatic pressure. Particles of 
the concentrated salt solution pass into the cylinder and mix with the water, F. These outgoing 
and ingoing currents continue until the fluids without and within J are of uniform composition, 
whereby the fluid in R always stands higher (e.g., aty), while it is lowered in the cylinder. 
The circumstance of the level of the fluid within the tube being so high, and remaining so, is 
due to the fact that the pores in the membrane are too fine to allow the hydrostatic pressure to 
act through them. 
Endosmotic Equivalent.—Experiment has shown that equal weights of different soluble 
substances attract different amounts of distilled water through the membrane, i. e., a known 
weight of a soluble substance (in the flask) can be exchanged by endos- 
mosis for a definite weight of water. The term “endosmotic equivalent” 
indicates the weight of distilled water that passes into the flask of the 
endosmometer, in exchange for a known weight of the soluble substance 
{Jolly'). For 1 grm. alcohol 4.2 grins, water were exchanged; while for 
1 grm. NaCl, 4.3 grms. water passed into the endosmometer. The follow- 
ing numbers give the endosmotic equivalent of— 
Acid potassium sulphate, = 2.3 
Common Salt, ... -= 4.3 
Sugar, =7-1 
Sodium sulphate, . . = 11.6 
Magnesium sulphate, = 11.7 
Potassium sulphate, = 12.0 
Sulphuric acid, . . = 0.39 
Potassium hydrate, . =215.0 
The amount of the substance which passes through the membrane into 
the water of the cylinder is proportional to the concentration of the 
solution. If the water in the cylinder, therefore, be repeatedly renewed, 
the endosmosis takes place more rapidly and the process of equilibration 
is accelerated. The larger the pores of the membrane, and the smaller the 
molecules of the substance in solution, the more rapid is the endosmosis. 
Hence, the rapidity of endosmosis of different substances varies, e.g., the 
rapidity of sugar, sodium sulphate, common salt, and urea is in the ratio 
of I : I.I : 5 : 9.5. 
The endosmotic equivalent is not constant for each substance. It is 
influenced by—(1) The temperature, which, as it increases, generally 
increases the endosmotic equivalent. (2) It also varies with the degree 
of concentration of the osmotic solutions, being greater for dilute solutions 
of the substances. 
If a substance other than water be placed in the cylinder, an endosmotic 
current occurs on both sides until complete equality is obtained. In this 
case, the currents in opposite directions disturb each other. If two sub- 
stances be dissolved in the water in the flask at the same time, they diffuse 
into water without affecting each other. (3) It also varies with membranes 
of varying porosity. Common salt, which gives an endosmotic equivalent 
with a pig’s bladder = 4.3 gives 6.4 when an ox bladder is used; 2.9 with 
a swimming bladder; and 20.2 with a collodion membrane. 
Colloids.—There are many fluid-substances which, on account of the great size of their 
molecules, do not pass, or pass only with difficulty, through the pores of a mem brane impreg- 
nated with gelatinous bodies, which diffuse slowly. These substances are not actually in a 
true state of solution, but exist in a very dilute condition of imbibition. Such substances are 
the fluid proteids, starches, dextrin, gum, and gelatin. These diffuse when no septum is present, 
but diffuse with difficulty or not at all through a porous septum. Graham called these sub- 
stances colloids, because, when concentrated, they present a glue-like or gelatinous appear- 
ance ; further they do not crystallize, while those substances which diffuse readily are crystalline, 
and are called crystalloids. Crystallizable substances may be separated from non-crystallizable 
by this process, which Graham called dialysis. Mineral salts favor the passage of colloids 
through membranes. 
Fig. 258. 
Endosmometer. ABSORPTION OF WATER AND SALTS. 
[Sec. 191. 
372 
That endosmosis and diffusion take place in the intestinal tract, through 
the mucous membrane and the delicate membranes of the blood- and lymph- 
capillaries, cannot be denied. On the one side of the membrane, within the 
intestine, are relatively concentrated solutions of highly diffusible salts, pep- 
tones, sugar, and soaps, and within the blood-vessels are the colloids, which 
are scarcely diffusible, e. g., the proteids of blood and lymph. 
II. Filtration is the passage of fluids through the coarse intermolecular pores of a membrane 
owing to pressure. The greater the pressure, and the larger and more numerous the pores, 
the more rapidly does the fluid pass through the membrane; increase of temperature also 
accelerates it. Those substances which are imbibed by the membrane filter most rapidly, so 
that the same substance filters through different membranes with varying rapidity. The filtration 
is usually slower, the greater the concentration of the fluid. The filter has the property of retain- 
ing some of the substances from the solution passing through it, e.g., colloid substances—or water 
(in dilute solutions of nitre). In the former case, the filtrate is more dilute, in the latter more 
concentrated, than before filtration. Other substances filter without undergoing any change of 
concentration. Many membranes behave differently, according to which surface is placed next 
the fluid; thus the shell-membrane of an egg permits filtration only from without inwards ; [and 
the same is true to a much less extent with filter-paper; the smooth side of the filter-paper ought 
always to be placed next the fluid to be filtered. The intact skin of the grape prevents the 
entrance of fungi into the fruit.] There is a similar difference with the gastric and intestinal 
mucous membrane. 
[By using numerous layers of filter-paper, many colloids and crystalloids are retained in the 
filter, e.g., haemoglobin, albumin, and many coloring matters, especially aniline colors, the last 
being arrested by glass-wool (JTrysinski),] 
[Filtration of Albumin.—Runeberg finds that the amount of albumin in pathological transu- 
dations varies with (i) the capillary area, being least in oedema of the subcutaneous tissue. 
(2) The presence or absence of inflammatory processes in the vascular wall, non-inflammatory 
pleuritic effusion containing 2 per cent., and inflammatory 6 per cent., of albumin. (3) The 
condition and amount of albumin in the blood. The amount of albumin in the transudate never 
reaches, although it sometimes approaches, that in blood. In ascites in general dropsy the 
amount is .03 to .04 per cent. (4) The duration of the transudation. (5) Perhaps the blood- 
pressure and the condition of the circulation.] 
Filtration of the soluble substance may take place from the canal of the 
digestive tract when : (1) The intestine contracts and thus exerts pressure upon 
its contents. This is possible when the tube is narrowed at two points, and the 
musculature between these two points contracts upon the fluid-contents. (2) 
Filtration, under negative pressure, may be caused by the villi (Briicke). 
When the villi contract energetically, they empty their contents towards the 
blood- and lymph-vessels. The lacteal remains empty, as the chyle is pre- 
vented from passing backwards into the origin of the lacteal within the villi, 
owing to the presence of numerous valves in the lymphatics. When the villi 
relax, they are refilled with fluids from the intestine. 
192. ABSORPTION BY THE INTESTINAL WALL.—I. True 
solutions undoubtedly pass by endosmosis into the blood-vessels and lymph- 
atics of the intestinal walls, but numerous facts indicate that the protoplasm of 
the cells takes an active part in the process of absorption. The forces concerned 
have not as yet been proved to be purely physical and chemical in their nature. 
(1) Inorganic Substances.—Water and soluble salts necessary for 
nutrition are easily absorbed, the latter especially by the blood- and lymph- 
vessels. When saline solutions pass by endosmosis into the vessels, water 
must pass from the intestinal vessels into the intestine. The amount of water, 
however, is small, owing to the small endosmotic equivalent of the salts to be 
absorbed. More salts are absorbed from concentrated than from dilute solutions. 
If large quantities of salt, with a high endosmotic equivalent, e. g., magnesium 
or sodium sulphate, are introduced into the intestine, these salts retain the 
water necessary for their solution, and may thus cause diarrhoea. Conversely, 
when these substances are injected into the blood, a large quantity of water Sec. 192.] 
ABSORPTION OF WATER AND SALTS. 
373 
passes from the intestine into the blood, so that constipation occurs, owing to 
dryness of the intestinal contents (Aubert). 
[M. Hay concludes from his experiments (§ 161) that salts, when placed in the intestines, 
do not abstract water from the blood, or are themselves absorbed, in virtue of an endosmotic 
relation being established between the blood and the saline solution in the intestines. Absorp- 
tion is probably due to the filtration and diffusion, or processes of imbibition other than endos- 
mosis, as yet little understood. The result obtained by Aubert, which is not constant, is mostly 
caused by the great diuresis which the injected salt excites.] The absorption of fluids takes 
place best at a medium pressure of 80 to 140 cm. of water within the intestine ; higher pressure 
compresses the blood-vessels and diminishes the absorption. During digestion, owing to the 
dilatation of the vessels, absorption is more rapid. The fact that 0.5 per cent, solution of NaCl 
is absorbed better than water, and soda solution than potash solution, seems to show that physical 
forces are not the only factors concerned. 
Fig. 259. 
Transverse section of an intestinal villus (dog). /, lacteal; c, capillaries; m, muscular fibres. 
Numerous inorganic substances, which do not occur in the body, are absorbed by endosmosis 
from the intestine, e.g., dilute sulphuric acid, potassium iodide, chlorate, and bromide, and 
many other salts. 
[That the water passes chiefly into the blood-capillaries, and only a small 
amount by the lacteals, appears to be due to the superficial position of these 
capillaries immediately under the epithelium of the villus (fig. 259, c.). If 
water be injected into a loop of intestine in the dog, and a fistula made on the 
thoracic duct so as to collect the chyle, the chyle-stream is but slightly increased 
during the absorption of the water from the intestine, so that perhaps a large 
part of the fluid of the chyle is derived from the’lymph formed by the capillaries 
of the villi. The water appears to pass between the cells, as well as through, 
the cell protoplasm. 
Physical forces, e.g., diffusion, do not seem to yield a satisfactory explanation 374 
ABSORPTION OF CARBOHYDRATES AND PEPTONES. 
[Sec. 192. 
of the absorption of water from the intestine. If a solution of grape-sugar and 
sodic sulphate be injected into a loop of intestine, the whole of the former is 
absorbed, but there always remains a considerable amount of the latter in the 
gut, although sodic sulphate has a higher rate of diffusion than grape-sugar. 
Indeed, for many soluble substances (e. g., pigments) the epithelium is quite 
impervious. 
As a general rule, soluble substances pass in the same way as the water, i. e., 
into the blood-vessels.] 
(2) The soluble carbohydrates, such as the sugars, of which the chief 
representatives are maltose and dextrose, with a relatively high endosmotic 
equivalent. Cane-sugar is changed by a special ferment into invert-sugar 
(§ 183, 5)- Absorption appears to take place somewhat slowly, as only very 
small quantities of grape-sugar are found in the chyle vessels, or the portal vein, 
at any time. According to v. Mering, the sugar passes from the intestine into 
the rootlets of the portal vein ; dextrin is also said to occur in the portal 
vein. [This latter statement is highly doubtful.] When the blood of the 
portal vein is boiled with dilute sulphuric acid the amount of sugar is increased. 
[There is no proof that the carbohydrates are absorbed in any other form than 
sugar.] The amount of sugar absorbed depends upon the concentration of its 
solution in the intestine; hence the amount of sugar in the blood is increased 
after a diet containing much of this substance, so that it may appear in the 
urine ; in which case the blood must contain at least 0.6 per cent, of sugar. A 
small amount of cane-sugar has also been found in the blood (CY. Bernard). 
If a large quantity of sugar be present in the intestine a part passes into the 
lymphatics or lacteal (Ginsberg). The sugar is used up in the bodily meta- 
bolism ; some of it is perhaps oxidized in the muscles (§ 176). 
[Injection of Sugar into Blood.—Lactose when injected into a vein is excreted unchanged 
in the urine, but galactose is almost completely assimilated, only a trace appearing in the urine. 
Lactose, therefore, requires to be changed in the intestinal canal before it can be assimilated. 
(Dastre). Cane-sugar is excreted in the urine as a foreign body. Grape-sugar (p. 332).] 
(3) The peptones have a small endosmotic equivalent, a 2 to 9 per cent, solu- 
lion = 7 to 10 [while albumin has 100]. Owing to their great diffusibility 
they are readily absorbed, and they are the chief representatives of the pro- 
teids which are absorbed. The amount absorbed depends upon the concentra- 
tion of their solution in the intestine. [According to Plosz and Gydrgyai, 
Drosdoff and Schmidt-Mulheim, peptones occur only in traces in the blood of 
the portal vein. Neumeister, however, using the best methods, finds that 
although peptones are abundant in the intestine, not a trace of peptone 
or of the albumoses is found either in the blood or lymph. This coincides 
with Hofmeister’s researches. As no peptones or albumoses have been 
found in the blood, and as they can compensate for the total metabolism of the 
proteids within the body, we must assume that they are rapidly converted into 
true albuminous bodies, somewhere between the cavity of the intestine and 
the blood-stream, i.e., in the wall of the intestine itself.] Hofmeister supposes 
that the leucocytes absorb the peptones and act as their carriers, much as the 
red corpuscles are oxygen carriers. They carry the peptones into the mucous 
membrane of the stomach and small intestine, which are very rich in peptone 
at the fourth hour of digestion. [The number of leucocytes is greatly 
increased in the mucous membrane, especially in the stomach and upper part 
of the duodenum, during digestion, and diminished during fasting in dogs and 
cats. The same is the case w'ith the lymph-follicles, the cells of which are 
formed by the division of the pre-existing cells.] [Thus the mucous membrane 
possesses the property of changing peptone into albumin (Salvioli). Heidenhain 
regards the epithelium of the villi as the seat of these changes. He supposes Sec. 192.] 
ABSORPTION OF PROTEIDS. 
375 
that the epithelium covering the villi reconvert the peptone into albumin, and 
give it up to the blood-capillaries lying immediately below the epithelial cells. 
At all events, some structures in the mucous membrane are capable of effecting 
the reconversion of peptones into albumin.] When animals are fed on pep- 
tones (with the necessary fat or sugar), these serve to maintain the body-weight. 
[It was formerly stated that the liver possessed the power of converting peptones into albumin 
Neumeister completely disproved this view by perfusing blood containing peptones through an 
excised but still living liver, and finding that no such change was effected. Also by injecting pep- 
tones and albumoses into a mesenteric vein, almost all the peptone was excreted by the urine, 
only a minute quantity being found in the small intestine.] 
[If a loop of mesentery be excised, and blood perfused through its arteries, i.e., an artificial 
circulation kept up, the loop will live for some time. If peptone be placed in the cavity of the 
loop, it will gradually disappear from the intestine, nor can it be recovered from the blood. 
It is absorbed, but apparently not as peptone. It is not changed by the blood, for peptone added 
to blood before it is perfused can be recovered from the blood after its perfusion. This experi- 
ment also points to the peptone being changed in its passage through the wall of the intestine 
(.Ludwig and Salvioli).] 
[Injection of Peptone into Blood.—When peptone is slowly injected into the blood of an 
animal, within a short time thereafter no trace of the peptone is to be found in the blood, liver, 
spleen, or small intestine, and only traces in the kidney. It is rapidly excreted, by the kidneys, 
so that the urine is like a solution of peptone. If a large quantity be rapidly injected the rab- 
bit dies, and much peptone is found in the small intestine. It would seem as if the kidneys 
could not excrete it quick enough, with the result that it passed into the intestine. Peptones, or 
rather albumoses, so injected prevent the blood of the dog (not of the rabbit, cat, or pig) from 
coagulating (p. 37). In large quantity they are fatal. Five c.c. of a 20 per cent, solution in 0.6 
per cent. NaCl solution is fatal to a dog weighing about 8 kilos. (17 lbs.). The peptones used 
in these experiments were really a mixture of peptones and albumoses. Neumeister finds that 
in the dog, when albumoses are injected into the blood they reappear in the urine, but some- 
where in the body they undergo hydration in the sense in which peptic digestion causes hydra- 
tion. The two primary albumoses reappear almost completely as deutero-albumose, and deutero- 
albumose, when introduced, reappears as peptone. Peptone, however, reappears unchanged. 
In rabbits, albumose reappears unchanged in the urine.] 
(4) Unchanged true proteids filter with great difficulty, and much albu- 
min remains upon the filter. On account of their high endosmotic equivalent 
they pass with extreme slowness, and only in traces, through membranes. 
Nevertheless, it has been conclusively proved that unchanged proteids can be 
absorbed (Briicke), e.g., casein, soluble myosin, alkali-albuminate, albumin 
mixed with common salt, gelatin ( Voit, Bauer, Eichhorst'). They are absorbed 
even from the large intestine (Czerny and Latschenberger), although the human 
large intestine cannot absorb more than 6 grms. daily. But the amount of 
unchanged proteids absorbed is always very much less than the amount of pep- 
tone. 
Other Proteids.—Egg-albumin without common salt, syntonin, serum-albumin, and fibrin are 
not absorbed from the intestine (Eichhorst). Landois observed, in the case of a young man 
who took the whites of 14 to 20 eggs along with NaCl, that albumin was given off by the urine 
for 4 to 10 hours thereafter. The amount of albumin given off rose until the third day, and 
ceased on the fifth day. The more albumin taken, the sooner the albuminuria appeared, and 
the longer it lasted. The unchanged egg-albumin reappeared in the urine. If unboiled egg- 
albumin be injected into the blood, part of it reappears in the urine, [so that it is not assimila- 
ted by the tissues. Before this can occur it must be altered in the digestive tract. If it be 
changed into syntonin or into alkali albumin, however, and then injected into a vein (dog), 
not a trace of these appears in the urine, so that they seem to be assimilated in the blood-stream. 
Casein similarly injected causes albuminuria, so that the changes casein undergoes during diges- 
tion prevents it from being excreted from the blood by the kidneys (Neumeister) ($ 41,2), 
(Stokvis, Lehmann).~\ 
(5) The soluble fat-soaps represent only a fraction of the fats of the food 
which are absorbed ; the greater part of the neutral fats being absorbed in the 
form of very fine particles—as an emulsion (§ 192, II). The absorbed soaps 
have been found in the chyle, and as the blood of the portal vein contains more 376 
ABSORPTION OF FATS. 
[Sec. 192. 
soaps during digestion than during hunger, it has been assumed that the soaps 
pass into the intestinal blood-capillaries. Still only a very small amount passes 
into the blood (J. Munk). 
The investigations of Lenz, Bidder, and Schmidt render it probable that the organism can 
absorb only a limited amount of fat within a given period; the amount, perhaps, bears a relation 
to the amount of bile and pancreatic juice. The maximum per kilo, (cat) was 0.6 grm. of fat 
per hour. 
[Injection of Soaps into the Blood.—If a certain amount of pure oleate of soda (soap) 
per kilogram weight be injected into a vein in a dog or rabbit, the blood-pressure falls and death 
may take place. If, however, the soap solution be injected into the rootlets of the portal vein it 
requires much more soap, so that the liver appears to retain a large part of it, or change it 
chemically. If volatile fatty acids (butyrate of soda) be injected instead, about ten times the 
amount can be injected. Injection of soaps into the blood retards the coagulation of the blood. 
In some respects, therefore, soap-injection is like peptone-injection, but the poisonous action of 
the peptone is not diminished by the liver as is the case with the soaps.] 
The greatest amount of the fats in the intestine are conveyed to the chyle as 
neutral fats. It would appear that the soaps reunite with glycerin in the paren- 
chyma of the villi, to form neutral fats, as Perewoznikoff and Will found neu- 
tral fats, after injecting these two ingredients into the intestinal canal, while 
Ewald found that fat was formed when soaps and glycerin were brought into 
contact with the living fresh intestinal mucous membrane. No fatty acids 
are found in blood (§ 32, II) or chyle (§ 198). 
Absorption of other Substances.—Of soluble substances which are introduced into the 
intestinal canal, some are absorbed and others are not. The following are absorbed: alcohol, 
part of which appears in the urine (not in the expired air), viz., that part which is not changed 
into CO,2 and H20, within the body; tartaric, citric, malic, and lactic acids; glycerin, inulin; 
gum and vegetable mucin, which give rise to the formation of glycogen in the liver. 
Amongst coloring matters, alizarin (from madder), alkanat, indigo-sulphuric acid, and its 
soda-salt are absorbed; haematin is partly absorbed, while chlorophyll is not. Metallic salts 
seem to be kept in solution by proteids, are perhaps absorbed along with them, and are partly 
carried by the blood of the portal vein to the liver (ferric sulphate has been found in chyle). 
Numerous poisons are very rapidly absorbed, e.g., hydrocyanic acid after a few seconds; potas- 
sium cyanide has been found in the chyle. [If salts (KI, sulphocyanide of ammonium) be 
injected into a ligatured loop of intestine (dog, cat, rabbit), these substances are absorbed both 
by the blood- and lymph-vessels, and in both nearly simultaneously.] 
Even for the absorption of completely fluid substances, endosmosis and filtration seem to be 
scarcely sufficient. An active participation of the protoplasm of the cells seems here also—in 
part at least—to be necessary, else it is difficult to explain how very slight disturbances in the 
activity of these cells, e.g., from intestinal catarrh, cause sudden variations of absorption, and 
even the passage of fluids into the intestine. 
If absorption were due to effusion alone, when alcohol is injected into the intestine, water 
ought to pass into the intestine, but this does not occur. Brieger found that the injection of a 
0.5 to 1 per cent, solution of salts into a ligatured loop of intestine did not cause water to pass 
into the intestine; but it appeared when a 20 per cent, solution was injected. 
II. Absorption of the Smallest Particles.—The largest amount of the 
neutral fats and also the fatty acids are simultaneously absorbed in the form 
of a milk-like emulsion, formed by the action of the bile and the pancreatic 
juice, and consisting of excessively small granules of uniform size (§ 170, III; 
§ 181). The fats themselves are not chemically changed, but remain as unde- 
composed neutral fats. The particles seem to be surrounded by a delicate 
albuminous envelope, or haptogen membrane, partly derived from the pan- 
creatic juice [probably from its alkali-albuminate]. The process of the ab- 
sorption of fat by the villi is one of the most obscure in physiology. The villi 
of the small intestine are the chief organs concerned in the absorption of the 
fatty emulsion, but the epithelium of the stomach and that of the large intestine 
also take a part. The fatty granules are recognized in the villi—(1) Within 
the delicate canals? (§ 190), in the clear band of the epithelium (.Kolliker). 
[It is highly doubtful if the vertical lines seen in the clear disc of the epithe- 
lium of the intestine are due to pores.] (2) The protoplasm of the epithelial Sec. 192.] 
ABSORPTION OF FATS. 
377 
>cells is loaded with fatty granules of various sizes during the time of absorption, 
while the nuclei of the cells remain free, although, from the amount of fat 
within the cells, it is often difficult to distinguish them (fig. 260). (3) The 
granules pass into the spaces of the parenchyma of the villi; these spaces com- 
municate freely with each other. (4) The origin of the central lymphatic 
or lacteal in the axis of the villus is found to be filled with fatty granules. 
The amount of fat in the chyle of a dog, after a fatty meal, is 8 to ro per 
cent., while the fat disappears from the blood within thirty hours. 
[Absorption of Fat.—1. Within the epithelial cells.—As to the ab- 
sorption of fats, the balance of evidence goes to show that it passes through the 
body of the epithelial cells, but what forces are concerned in this process 
is not certain. The bile at least seems to aid the process within the epithelial 
cells; the fat appears in droplets of variable size (fig. 260). The fat enters in 
small droplets, which in the protoplasm of the cell may run together to form 
larger ones. The fatty contents seem to be driven out of the body of the cells 
by the contraction of the protoplasm of the cells. 
Vertical section of the epithelium of a villus, showing 
the absorption of fat; the fatty particles are blackened 
by osmic acid. 
Fig. 260. 
Pancreas and duodenum of rabbit 
during digestion of fat. S, 
Stomach ; mg, mesenteric gland; 
t, lacteals; d, duodenum; pdr 
entrance of pancreatic duct. 
Fig. 261. 
2. In the spaces of the stroma of the villi.—The fatty granules 
then pass into the pericellular spaces of the stroma of the villi. The fatty par- 
ticles are carried through these spaces towards the lacteal by the lymph-stream, 
which flows from the superficially placed capillaries towards the central lacteal. 
This current carries the suspended fatty particles floating in an alkaline stream. 
3. In the lacteal.—The so-called “molecular basis” of the chyle is first 
seen and appears to be formed as the suspended fatty granules pass into the 
lacteal. No such fine fatty emulsion as occurs in the lacteals is found in the 
small intestine, nor even in the villus itself. 
There is no good reason for believing that fat passes directly into the blood- 
vessels.] 
[Some recent observers, e.g., Krehl, doubt whether fat is absorbed in a par- 
ticulate form from the intestine, and they regard it as most probable that the 
fat is absorbed by the epithelium in a soluble form.] 
[C. Bernard noticed in rabbits, in whom the chief pancreatic duct opens 378 
[Sec. 192. 
ABSORPTION OF FATTY PARTICLES. 
separate from the bile-duct, and low down in the intestine, that the lacteals first 
became white below the entrance of the pancreatic duct (fig. 261). This 
observation led him to attach great importance to the emulsionizing properties 
of the pancreatic juice.] 
Fate of the Fats.—The excessively fine fatty particles are used up by the 
tissues, but all tissues do not do so equally. They are taken up in large amount 
by the liver, and least of all by muscle. The tissues are said to split up the 
fats into glycerin and fatty acids, and these are ultimately oxidized to yield 
heat chiefly. 
With regard to the forces concerned in the absorption of fats, v. 
Wistinghausen stated that when a porous membrane is moistened with bile, the 
passage of fatty particles through it is thereby facilitated (p. 343), but this fact 
alone does not explain the copious and rapid absorption of fats. It is possible 
that the protoplasm of the epithelial cells is actively concerned in the process, 
and that it takes the particles into its interior. Perhaps a fine protoplasmic 
process is thrown out by these cells, just as pseudopodia are thrown out and 
retracted by lower organisms. [This, however, has not been corroborated by 
a sufficient number of observers.] Perhaps the protoplasm of the epithelial cells, 
in virtue of its contractility, forces the fatty granules out of the cells into the 
spaces of the villi, whence they are carried by the lymph-stream (p. 377), and 
so through the stomata (?), between the endothelial cells into the central lac- 
teal of the villus. According to this view, the absorption of fatty particles, and 
perhaps also the absorption of true proteids, is in part due to an active vital 
process, as indicated by the observations of Briicke and v. Tbanhoffer. This 
view is supported by the observation of Griinhagen, that the absorption of fatty 
particles in the frog is most active at the temperature at which the motor phe- 
nomena of protoplasm are most lively. That it is due to simple filtration alone 
is not a satisfactory explanation, for the amount of fatty particles in the chyle 
is independent of the amount of water in it. If absorption were chiefly due to 
filtration, we would expect that there would most probably be a direct relation 
between the amount of water and fat (Ludwig and Zawilsky). [The observa- 
tions of Watney have led him to suppose that the fatty particles do not pass 
through the cell protoplasm to reach the lacteal, but that they pass through the 
cement substance between the epithelial cells covering a villus. If this view be 
correct, and it is highly doubtful if it is, the absorbing surface is thereby greatly 
diminished. Zuwarykin and Schafer suggest that the leucocytes, which have 
been observed between the columnar cells of the villi of the small intestine, 
are carriers of at least part of the fat from the lumen of the gut to the lacteal; 
they also, perhaps, alter it for further use in the economy. [So far these state- 
ments relative to the leucocytes have not been universally accepted; indeed, 
they are denied by the most recent observers.] 
[One of the most remarkable experiments in relation to the absorption of 
fatty matter is that of I. Munk, and confirmed by Walther, viz., that if a dog 
be fed on fatty acids instead of neutral fats, then neutral fats appear in the 
chyle collected from the thoracic duct. Where does the glycerin come from, 
and where and how is the synthesis effected? So far there is no satisfactory 
answer to these questions, but it is suggested that the synthesis takes place in 
the villi, or even in the lumen of the gut.] 
[A most remarkable case of a lymph fistula in a man was experimented on by Munk. A lad 
suffering from elephantiasis had a fistula in the leg, through which during digestion much chyle 
was discharged. When erucic acid—an acid not found normally in the body—was administered 
to the lad, the chyle discharged from the fistula did not contain more than traces of free erucic 
acid, but on the contrary, it contained a large quantity of the corresponding neutral fat erucin. 
The erucic acid must have somewhere obtained glycerin to combine with, to form the neutral 
fat. This confirms Munk’s experiments on animals, that fatty acids do not reach the blood as Sec. 192.] 
NUTRIENT ENEMATA. 
379 
such, but that, perhaps, in the very act of absorption in the intestinal mucous membrane, they 
are by synthesis converted into neutral fats. 'The case has also been used to prove that sugars 
when given by the mouth, are all, except an excessively small amount, absorbed by the blood- 
stream, and do not reach the blood through the lymph- and chyle-stream.] 
[Methods.—A. Histological.—The absorption of fat has usually been studied by feeding 
an animal on fatty food and examining its villi either in a fresh condition, or more usually after 
they have been submitted to the action of osmic acid, which blackens fatty matter. In this 
connection it is important to remember two facts, viz., that turpentine may discharge the 
black color of fat acted on by osmic acid, such sections in histological processes being often 
treated with turpentine; and secondly, an observation of Heidenhain’s that osmic acid blackens 
also granules in some of the leucocytes of the villi which are certainly not fatty, for they are not 
soluble in ether.] 
[B. Experimental.—If in a dog a cannula be introduced into the thoracic duct where it 
joins the subclavian vein, the amount of chyle that flows out in a given time can be estimated. 
The amount flowing out is not greater during digestion than in a fasting animal. In a fasting 
animal the fluid is transparent and like lymph, and it becomes white and opaque during 
digestion from the presence of fatty particles. During the digestion of sugar the chyle does 
not contain more sugar—o. 1-0.2 per cent.—than is present in the lymph or serum of a fasting 
animal. These and other similar experiments make it clear that the fats alone pass via the 
chyle-stream to reach the blood, all the other products of digestion pass directly into the 
rootlets of the portal vein.] 
The activity of the cells of the intestine with pseudopodial processes may be studied in the 
intestinal canal of Distomum hepaticum. Sommer has figured these pseudopodial processes 
actively engaged in the absorption of particles from the intestine. 
193. INFLUENCE OF THE NERVOUS SYSTEM ON AB- 
SORPTION.—With regard to the influence of the nervous system upon in- 
testinal absorption, we know very little. After extirpation of the semi-lunar 
ganglion, as well as after section of the mesenteric nerves (.Moreau), the intes- 
tinal contents become more fluid, and are increased in amount (§ 183). This 
may be partly due to diminished absorption. V. Thanhofler states that he 
observed the protrusion of threads from the epithelial cells of the small intes- 
tine only after the spinal cord, or the dorsal nerves, had been divided for some 
time. 
194. “ NUTRIENT ENEMATA.”—In cases where food cannot be taken by the mouth, 
e.g., in stricture of the oesophagus, continued vomiting, etc., food is given per rectum. As the 
digestive activity of the large intestine is very slight, fluid food ought to be given in a condition 
ready to be absorbed, and this is best done by introducing it into the rectum through a tube with 
a funnel attached, and allowing the food to pass in slowly by its own weight. The patient must 
endeavor to retain the enema as long as possible. When the fluid is slowly and gradually intro- 
duced, it may pass above the ileo-ctecal valve. 
Solutions of grape-sugar, and perhaps a small amount of soap solution, are useful; and 
amongst nitrogenous substances the commercial flesh-, bread-, or milk-peptones of Sanders-Ezn, 
and Adamkiewicz, in Germany, and Darby’s fluid meat, and Carnrick’s beef-peptonoids in this 
country, are to be recommended. The amount of peptone required is 1.11 grm. per kilo, of 
body-weight (Catillon); less useful are buttermilk, egg-albumin with common salt. Leube 
uses a mixture of 150 grms. flesh, with 50 grms. pancreas, 100 grms. water, which he slowly 
injects into the rectum, where the proteids are peptonized and absorbed. [Peptonized food 
prepared after the method of Roberts is very useful ($ 172).] The method of nutrient enemata 
only permits imperfect nutrition, and at most only of the proteids necessary for maintaining 
the metabolism of the body is absorbed (v. Voit, Bauer). 
195. CHYLE-VESSELS AND LYMPHATICS.—Lymphatics. 
—Within the tissues of the body generally, and even in those tissues which do 
not contain blood-vessels, e. g., the cornea, or in those which contain few blood- 
vessels, there exists a system of vessels or channels which contain the juices of 
the tissues, and within these vessels the fluid always moves in a centripetal 
direction. These canals arise within the tissues in a variety of ways, and unite 
in their course to form delicate and afterwards thicker tubes, which ultimately 
terminate in two large trunks which open at the junction of the jugular and 
subclavian veins; that on the left side is the thoracic duct, and that on the 
right, the right lymphatic trunk. [Sec. 195. 
380 
STRUCTURE OF THE LYMPHATIC SYSTEM, 
[Through the thin-walled blood-capillaries 
there transudes into the spaces of the sur- 
rounding tissues part of the blood-plasma. 
This fluid is the lymph. It permeates every 
tissue of the body, bathing their constituent 
form-elements, supplying the latter with nutri- 
ment, and enabling them to get rid of the 
waste products resulting from their metabolism. 
The lymph is collected and returned to the 
blood in special tubes, the lymphatics. 
Whatever the mode of origin of the lymphatics 
(p. 385), at first they form thin-walled micro- 
scopic lymphatic vessels, which communicate 
freely with each other in a plexiform manner, 
and by their confluence they form the lym- 
phatic vessels (.1-1 mm.), which usually run 
along with the superficial and deep blood- 
vessels (fig. 262). The larger lymphatics are 
provided with valves, like some veins. The 
valves open towards the heart, and on the 
cardiac side of the valve there is a dilatation, 
so that the lymphatic trunks, especially when 
injected, often present a beaded or varicose 
appearance. The walls often are so thin and 
translucent that one can see the clear lymph 
which they contain. A moderate-sized lym- 
phatic trunk has three coats like a vein, 
only the coats are thinner. The inner coat, 
or tunica intima, consists of a layer of endo- 
thelial cells, often with a sinuous outline, 
resting on a delicate network composed of fine 
elastic fibres. The middle coat, or tunica 
media, is composed of smooth muscular 
fibres arranged transversely or obliquely. The 
tunica adventitia consists of connective- 
tissue, which in some situations contains smooth 
muscular fibres. The fine lymphatic capillaries 
have dilatations and constrictions on them, 
and are composed of a single layer of endo- 
thelium, the edges of which are usually sinuous, 
a fact best demonstrated by the use of silver 
nitrate (fig. 263).] 
The lymph fulfils different functions in 
different organs. (1) In many tissues, the 
lymphatics represent the nutrient channels, 
by which the fluid that transudes through the 
neighboring vessels is distributed, as in the 
cornea and in many connective-tissues. (2) 
In many tissues, as in glands, e. g., the sali- 
vary glands and the testis, the lymph-spaces 
are the chief reservoirs for fluid, from 
which the cells during the act of secretion 
derive the fluid necessary for that process. 
(3) The lymphatics have the general function 
of collecting the fluid which saturates the tis- 
Anterior view of the lymphatics of 
the arm. A, basilic, B, cephalic, 
and C, axillary veins; I, lymphatic 
plexus of the palm; 2, external 
collateral trunk of the thumb; 3,3, 
superficial lymphatics of the fore- 
arm, and 5, of the upper arm; 4, 
supra-trochlear; 6, axillary ganglia; 
7, lymphatics of the shoulder; 8, 
vein accompanying the cephalic 
vein; 9, ganglia of the neck. 
Fig. 262. Sec. 195.] 
STRUCTURE OF THE LYMPHATIC SYSTEM. 
sues, and carrying it back again to the blood. The capillary blood system 
may be regarded as an irrigation system, which supplies the tissues with 
nutrient fluids, while the lymphatic 
system may be regarded as a 
drainage apparatus, which con- 
ducts away the fluids that have trans- 
uded through the capillary. walls. 
Some of the decomposition-products 
of the tissues, proofs of their retro- 
gressive metabolism, become mixed 
with the lymph-stream, so that the 
lymphatics are at the same time 
absorbing vessels. Substances 
introduced into the parenchyma of 
the tissues in other ways, e.g., by 
subcutaneous injection, are partly 
absorbed by the lymphatics. A 
study of these conditions shows that 
the lymphatic system represents an 
appendix to the blood vascular 
system, and further that there can 
be no lymph system when the blood- 
stream is completely arrested; it 
acts only as a part of the whole, and with the whole. 
Lacteals.—When we speak of the lymphatics proper as against the chyle- 
vessels or lacteals, we do sc 
from anatomical reasons, because 
the important and considerable 
lymphatic channels coming from 
the whole of the intestinal tract 
are, in a certain sense, a fairly 
independent province of the lym- 
phatic vascular area, and are en- 
dowed with a high absorptive ac- 
tivity,, which from ancient times 
has attracted the notice of ob- 
servers. The contents of the chyle- 
vessels or lacteals are mixed with 
a large amount of fatty granules, 
giving the chyle a white appear- 
ance, which distinguishes them at 
once from the true lymphatics with 
their clear watery contents. From 
a physiological point of view, how- 
ever, the lacteals must be classified 
with the lymphatics, for, as regards 
their structure and function, they 
are true lymphatics, and their con- 
tents consist of true lymph mixed 
with a large amount of absorbed 
substances, chiefly fatty granules. 
[The contents of the lacteals are white only during digestion, at other times, 
i. e., when an animal has fasted for some time, they are clear like lymph.] 
Fig. 263. 
Lymphatic of the pericardium ; epithelium stained 
with silver, and showing the bulging and con- 
strictions in the vessel. 
Origin of lymphatics from the central tendon of the 
diaphragm stained with nitrate of silver, s, the 
juice-canals, communicating at x with the lym- 
phatics ; a, origin of the lymphatics by the conflu- 
ence of several juice-canals. 
Fig. 264. 382 
ORIGIN OF THE LYMPHATICS. 
[Sec. 196. 
196. ORIGIN OF THE LYMPH ATICS—Connective-tissue.— 
(i) Origin in Spaces.—Within the connective-tissues (connective-tissue 
proper, bone) are numerous stellate, irregular, or branched spaces, which com- 
municate with each other by numerous tubular processes (fig. 264, s) ; in these 
communicating spaces or lymph-spaces lie the cellular elements of these 
tissues. These spaces, however, are not completely filled by the cells, but an 
interval exists between the body of the cell and the wall of the space, which is 
greater or less according to the condition of movement of the protoplasmic 
cell. These spaces are the so-called “juice canals ” or “ Saft canalchen,” 
and they represent the origin of the lymphatic vessels (v. Recklinghausen). As 
they communicate with neighboring spaces, the movement of the lymph is 
provided for. The cells which lie in the spaces exhibit amoeboid move- 
ments. Some of these cells remain permanently each in its own space, 
within which, however, it may change its form—these are the so-called “ fixed 
connective-tissue corpuscles,” and bone corpuscles—while others merely 
wander or pass into these spaces, and are called “wandering cells ,” or 
“leucocytes;” but the latter are merely lymph-corpuscles, or colorless 
blood-corpuscles which have passed out of the blood-vessels into the origin 
of the lymphatics (fig. 266). These cells exhibit amoeboid movements. These 
spaces communicate with the small tubular lymphatics—the so-called lymph- 
capillaries (L). The spaces lie close together, where they pass into a lymph- 
capillary (a). The lymph-capillary, which is usually of greater diameter than 
the blood-capillary, generally lies in the middle of the space within the 
capillary arch (B). The finest lymphatics are lined by a layer of delicate, 
nucleated, endothelial cells 
(<?, e), with characteristic 
sinuous margins, whose 
characters are easily re- 
vealed by the action of 
silver nitrate (fig. 265, L). 
This substance blackens the 
cement-substance which 
holds the endothelial cells 
together. Between the 
endothelial cells are small 
holes, or stomata, by 
means of which the lymph- 
capillaries communicate (at 
x) with the juice-canals. 
From the researches of 
Arnold, Thoma, and others 
it is assumed that the 
blood-vessels communicate 
with the juice-canals, and 
that fluid passes out of 
the thin-walled capillaries 
through their stomata into 
these spaces (§ 65). This 
fluid nourishes the tissues, 
the tissues take up the sub- 
stances appropriate to each, 
while the effete materials pass back into the spaces, and from these reach the 
lymphatics, which ultimately discharge them into the venous blood. 
Pleural surface of the central tendon of the diaphragm of 
the rabbit stained with silver nitrate. L, lymphatic with 
its sinuous endothelium; c, cells of the connective-tissue 
brought into view by the silver nitrate. 
Fig. 265. Sec. 196.] 
CONNECTIVE-TISSUE. 
383 
Whether the cells within these spaces are actively concerned in the pouring 
out of the blood-plasma, or take part in its movement, is matter of con- 
jecture. We can imagine that by contracting their body, after it has been 
impregnated with fluid, this fluid may be propelled from space to space towards 
the lymphatics. The leucocytes wander through these spaces until they pass into 
the lymphatics. Fine particles which are contained in these spaces—e.g., after 
tattooing the skin, and even fatty particles after inunction—are absorbed by 
the leucocytes, and carried by them to other parts of the body. [The pigment 
particles used to tattoo the finger are usually found within the first lymphatic 
gland at the elbow.] 
The migration of cellular elements from the blood-vessels into the origin of 
the lymphatics is to be considered as a normal process. Granular coloring- 
matter passes from the blood into the protoplasmic body of the cells within the 
Fig. 266. 
Subcutaneous connective tissue of a sheep, a a, fixed connective-tissue corpuscles with processes; 
b b, anastomosing processes; cc, broken-off processes; d, isolated parts of the cells; e, lymph - 
cell or leucocyte. X 800. 
lymph-spaces; and only when the granular pigment is in large amount does it 
appear as a granular injection in the branches of the juice-spaces. 
[Connective-tissue is widely distributed in the body, entering into the 
construction of most organs, and, as its name denotes, it connects and binds 
structures together. It assumes many forms, being either of a more or less 
open texture, when it is called areolar tissue, or its fibres may be so arranged 
as to form dense membranes, such as fasciae, or stout cords and bands, like 
ligaments. It performs certain purely mechanical and certain physiological 
functions in the economy. It is developed from the cells of the mesoblast, and 
consists of— 
1. Cells or corpuscles. 
2. An inter-cellular matrix. 
The corpuscles—of which there are several varieties—are in the adult far less 
numerous than the matrix or inter-cellular matter, which consists of fibres, the 384 
STRUCTURE OF CONNECTIVE-TISSUE. 
[Sec. 196. 
fibres being of two kinds—the white fibres and the yellow or elastic fibres. 
Its mechanical functions depend far more on the fibres than the cells. In the 
form which occurs under the skin, and surrounds lymphatics and blood-vessels 
in their course, and is spoken of as loose connective-tissue or areolar 
tissue, the fibres are arranged in bundles which cross each other in various 
directions and leave larger or smaller spaces, or areolae, between them. These 
spaces contain lymph, and from them the lymphatics arise, hence the name “ areo- 
lar.” The fixed connective-tissue corpuscles lie on the bundles of white fibres 
(fig. 266). If a piece of areolar tissue be teased out and examined microscopically, 
it is seen to consist of bundles of wavy fibres, and these fibres readily split up 
under the action of reagents, e.g., 10 per cent, common salt or picric acid, 
into fine unbranched excessively narrow fibrils or fibrillae, 1 ;j. or less in 
diameter. The fibrillae are held together by a globulin-like, or perhaps mucin- 
like, cement, and according to the number of fibrillae so is the size of the fibres. 
The outline of the fibre is always somewhat indistinct, but they refract the light 
pretty strongly and appear whitish under the microscope, hence their name of 
white fibres. These fibres when boiled yield gelatin, and hence they have 
been called gelatiniferous fibres. The bundles are held together by a cement- 
substance which is blackened by silver nitrate, and on the fibres lie the fixed 
connective-tissue corpuscles (fig. 267) embedded in the cement. These 
nucleated cells may be fusiform, but they are more frequently irregular in form 
and branched. They resemble flattened, winged, or stellate plates. As they 
are sometimes in relation with more than one fibre, they may present a winged 
appearance. They are most abundant and most readily seen in young tissue, 
and are not so readily seen in a preparation from 
an adult animal, partly because of the number 
of fibres, and partly because their refractive 
index is not such as to make them readily visi- 
ble. If they be stained, however, e.g., with 
eosin (fig. 266), or if the tissue be acted on by 
a dilute acid—e.g., acetic acid—the white 
fibres swell up and become clear and homo- 
geneous, so that the nuclei of the connective- 
tissue corpuscles come distinctly into view. 
The corpuscles become somewhat shrunken and 
more granular under the action of the acid. 
These are called “fixed” connective-tissue 
corpuscles because they do not change their 
place, nor do they in the adult exhibit amoe- 
boid movement. In the spaces of areolar tissue 
there are always found some cells much smaller 
than the foregoing, spherical in form, and 
presenting all the characters of leucocytes, 
which indeed they are (fig. 266, e). They 
exhibit amoeboid movements and have wandered 
out of the blood-vessels or lymphatics into the 
areolar spaces. A third form of corpuscle is 
frequently found, more especially along the 
course of the smaller blood-vessels in certain 
situations. The last variety of cells always 
contains numerous large granules. These cells were called “ plasma cells ” 
by Waldeyer.] 
[In the connective-tissue of the mesentery of the newt, and in the peri- 
oesophageal membrane around the oesophagus of the frog, and in the connective- 
Showing relation of a connective- 
tissue corpuscle to a fibre, lying on 
and clasping the latter. A, nucleus 
of the fixed cell; B, protoplasm 
body; C, processes ; D, white fibre 
on which the cell rests; E, elastic 
fibre. X 1000. 
Fig. 267. Sec. 196.] 
CLASMATOCYTES. 
385 
tissue membranes of vertebrates generally, Ranvier has described some 
enormously large connective-tissue corpuscles—nearly 1 mm. in size—which 
stain deeply with methyl-violet. He has called them “ clasmatocytes ” 
(xkd<rt±a, aToq, fragment, xbroq, cell), because they tend to break up into small 
particles or granules. What their relation is to other forms of connective-tissue 
corpuscles has not been determined.] 
[Clasmatocytes occur in the thin connective-tissue membranes of vertebrata, and are most 
readily found in the perioesophageal membrane of the frog. They are first fixed with osmic acid 
and then stained with methyl-violet, 5 B. In the triton they are about I mm. in length, and are 
therefore colossal cells. When stained they are colored violet with a tinge of red, the nucleus 
being slightly blue. They have numerous processes, simple or branched, but the processes do 
not form a reticulum. The body and processes have a granular appearance and are irregular in 
their shape. Parts of them tend to separate in fragments, hence the name of the cells. This is 
the peculiarity of these cells, that their processes tend to break up and form islands of granules 
under certain conditions, and this process Ranvier calls clasmacytosis. They do not exhibit 
amoeboid movements, although they are developed by the evolution of leucocytes, which have 
passed out of the vessels into the connective-tissue. Ranvier has traced the stages from the sim- 
ple leucocytes up to these complex and marvellous cells. The clasmatocyte is at least one hundred 
times larger than the leucocyte. Certain leucocytes, after reaching the meshes of the connective- 
tissue, appear to grow, enlarge, and undergo a particular evolution which makes them clasma- 
tocytes, which give off part of their substance in fragments, which are probably used in the 
economy (Ranvier).] 
[It is difficult to say what is the relation—if any—of these cells to the plasma-cells of 
Waldeyer, i. e., certain granular cells situated along the course of the blood-vessels, the inter- 
stitial cells of the testes, and the cells of the supra-renal capsules (p. 180). Ehrlich, by staining 
the plasma-cells with aniline dyes, showed that they were not all alike. Only some of them 
were colored by the basic aniline dyes; these are the anilinophile cells or “ Matszellen ” of 
Ehrlich. They are derived from the fixed connective-tissue corpuscles.] 
[There are also yellow or elastic-fibres present in areolar tissue. They 
can be seen in a fresh preparation of the tissue, but are best seen after the 
action of acetic acid, which makes the white fibres transparent, but does not 
affect the yellow fibres. The yellow fibres are not so numerous as the white; 
they have a sharper outline, and faint yellow tinge ; they branch and anasto- 
mose, and when broken tend to curl up at their ends. By their anastomoses 
they form networks which render the tissues in which they occur more or less 
elastic. They vary in size, but they cannot be split up further into fibres. In 
some situations the elastic fibres become greatly increased both in number and 
size, as in the ligamentum nuchse, which consists almost entirely of elastic 
fibres—some of them as broad as a red blood-corpuscle (fig. 269). There is 
every gradation between the fine networks of elastic fibres that occur in the 
meso-colon and skin (fig. 268) to the thick fibres of the ligamentum nuchse, 
up to fenestrated sheets of elastic tissue occurring in the aorta, and the complete 
sheet of elastic membrane, forming the chief part of the elastic lamina of the 
arteries. The elastic fibres consist of elastin (§ 250).] 
(2) Origin within villi—i.e., of the chyle vessel or lacteal—has been 
described (§ 190). 
(3) Origin in perivascular spaces (fig. 270).—The smallest blood-vessels 
of bone, the central nervous system, retina, and the liver, are completely sur- 
rounded by wide lymphatic tubes, so that the blood-vessels are completely 
bathed by a lymph-stream. In the brain these lymphatics are partly composed 
of delicate connective-tissue fibres, which traverse the lymph-space and become 
attached to the wall of the included blood-vessel. Fig. 270, B, represents a 
transverse section of a small blood-vessel, B, from the brain ; p is the divided 
perivascular space. This space is called the perivascular space of His, but 
in addition to it the blood-vessels of the brain have a lymph-space within the 
adventitia of the blood-vessels ( Virchow-Robin's space). It is partly lined by 
well-defined endothelium. Where the blood-vessels begin to increase consid- 386 
STOMATA AND SEROUS CAVITIES. 
[Sec. 196. 
erably in diameter, they pass through the wall of the lymphatics, and the two 
vessels afterwards take separate courses. In all cases, where there is a perivas- 
cular space, the passage of lymph- and blood-corpuscles into the lymphatics is 
greatly facilitated. In the tortoise the large blood-vessels are often surrounded 
with perivascular lymphatics. Fig. 270, A, gives a representation of the aorta 
of the tortoise surrounded by a perivascular space which is visible to the un- 
aided eye. In mammals the perivascular spaces are microscopic. 
(4) Origin in the form of interstitial slits within organs.—Within 
the testis the lymphatics begin simply in the form of numerous slits, which 
occur between the coils and twists of the seminal tubules. They take the form 
of elongated spaces bounded by the curved cylindrical surfaces of the tubules. 
The surfaces, however, are covered with endothelium. The lymphatics of the 
testis get independent walls after they leave the parenchyma of the organ. In 
many other glands the gland-substance is similarly surrounded by a lymph- 
space. The blood-vessels pour the lymph into 
these spaces, and from them the secreting cell 
obtain the materials necessary for the forma 
tion of their secretion. 
Fig. 268. 
Fig. 269. 
Network of yellow or fine elastic fibres from the 
omentum. Some corpuscles are also visible. X 350. 
Thick elastic fibres of the human liga- 
mentum nuchse. X 459. 
(5) Origin by means of free stomata on the walls of the larger serous 
cavities, which (fig. 271, a) communicate freely with the lymphatics. The 
investigation of the serous surfaces is most easily accomplished on the septum of 
the great abdominal lymph-sac of the frog. Silver nitrate reveals the presence 
of relatively large free openings or stomata lying between the endothelium. 
Each stoma is bounded by several germinating cells, which have a granular 
appearance, and undergo a change of shape, so that the size of the stoma de- 
pends upon the degree of contraction of these cells ; thus the stoma may be 
open (a), half-open (b), or completely closed (<r). These stomata are the origin 
of the lymphatics. The serous cavities belong therefore to the lymphatic sys- 
tem, and fluids placed in the serous cavities readily pass into the lymphatics. 
The cavities of the peritoneum, pleura, pericardium, tunica vaginalis testis, 
arachnoid space (?), aqueous chambers of the eye, and the labyrinth of the ear, 
are true lymph-cavities, and the fluid they contain is to be regarded as lymph. 
[Hoffmann has found that a nerve-fibre surrounds the stomata in the frog and 
sends branches between the germinal epithelium.] 
(6) Free open pores have been observed on some mucous membranes, Sec. 196.] 
SIMPLE LYMPH-FOLLICLES 
387 
which are regarded as the origin of lymphatics, e. g., in the bronchi, nasal mu- 
cous membrane, trachea, and larynx. 
Structure of Lymphatics.—The larger lymphatics resemble in structure 
the veins of corresponding size. The valves are particularly numerous in the 
lymphatics, so that a distended lymphatic resembles a chain of pearls (p. 380). 
[Lymphatics have dilations here and there in their course (fig. 265).] 
197. THE LYMPH-GLANDS.—The lymphatic glands belong to 
the lymph apparatus. They are incorrectly termed glands, as they are merely 
Fig. 270. 
Fig. 271. 
Perivascular lymphatics. A, aorta of tor- 
toise ; B, artery from the brain. 
Stomata in the great lymph-sac (frog). 
a, open; b, half-closed; £, closed. 
much-branched lacunar labyrinthine spaces composed of adenoid tissue, and 
Intercalated in the course of the lymphatic vessels. There are simple and 
compound lymph-glands. 
(i) The simple lymph glands, or, more correctly, lymph-follicles, are 
small rounded bodies, about the size of a pin-head. They consist of a mass of 
adenoid tissue (fig. 272, A), i. e., of a very delicate network of fine reticular 
fibres with nuclei at their points of intersection, and in the spaces of the mesh- 
work lie the lymph and the lymph-corpuscles. Near the surface the tissue is 
somewhat denser, where it forms a capsule, which is not however a true cap- 
sule, as it is permeated with numerous small sponge-like spaces. Small lym- 
phatics come directly into 
contact with these lymph- 
follicles, and often cover 
their surface in the form of 
a close network. The sur- 
face of the lymph-follicles 
is not unfrequently placed 
in the wall of a lymph- 
vessel, so that it is di- 
rectly bathed by the lymph- 
stream. Although no di- 
rect canal-like opening 
leads from the follicle 
into the lymphatic stream 
in relation with it, a com- 
munication must exist, and 
this is obtained by the 
Two lymph-follicles. A, a small follicle highly magnified, 
showing the adenoid reticulum; B, a follicle less highly 
magnified, showing injected blood-vessels. 
Fig. 272. 388 
STRUCTURE OF LYMPHATIC GLANDS. 
[Sec. 197. 
numerous spaces in the follicle itself, so that a lymph-follicle is a true lymphatic 
apparatus whose juices and lymph-corpuscles can pass into the nearest lymphatic. 
The follicles are surrounded by a network of blood-vessels which sends loops of 
capillaries into their interior (fig. 272, B). [In the centre of each is a germ- 
centre where mitosis goes on rapidly.] We may assume that lymph-corpuscles 
pass from these capillaries into the follicle. 
[The follicles arise by aggregation of round cells or leucocytes in the mucosa or sub-mucosa, 
where they rapidly reproduce themselves by mitosis. The gradually enlarging mass compresses 
the surrounding tissue which forms a kind of tunica propria for each follicle (p. 245). In the 
intestine the cupola is covered by columnar epithelium with a few goblet-cells.] 
In connection with these follicles, including those of the back of the tongue, 
the solitary glands of the intestine, and the adenoid tissue in the bronchial 
tract, the tonsils, and Peyer’s patches, it is important to remember that enor- 
mous numbers of leucocytes pass out continually between the epithelial cells 
covering these follicles. In this process many epithelial cells are destroyed. 
Thus there is a kind of physiological solution of continuity of the surface, 
through which, under certain conditions, micro-organisms or other poisonous 
bodies may enter the organism. The extruded leucocytes undergo disintegration 
subsequently. 
(2) The compound lymph-glands—the lymphatic glands—represent a 
collection of lymph-follicles, whose form is somewhat altered. [They are small 
oval or kidney-shaped bodies varying much in size, and intercalated in the 
course of lymphatics. Usually at one side there is a hilum from which the effer- 
ent lymphatic issues.] Every lymph-gland is covered externally with a connec- 
tive-tissue capsule (fig. 273, c), which contains numerous non-striped muscular 
fibres. From its inner surface numerous septa and trabeculae (/r.) pass into 
the interior, so that the gland-substance is divided into a large number of com- 
partments. These compartments in the cortical portion of the gland have 
a somewhat rounded form, 
and are nearly filled with 
aggregations of lymph-cor- 
puscles, sometimes called 
secondary nodules— 
which constitutethealveoli, 
while in the medullary por- 
tion they have a more elon- 
gated and irregular form. 
[In many of the nodules 
there is a lighter centre— 
germ-centre, where mito- 
sis or division of leucocytes 
goes on rapidly (fig. 275). 
On making a section of a 
lymph-gland we can readily 
distinguish the cortical 
from the medullary por- 
tion of the gland.] All the 
compartments are of equal 
dignity, and they all com- 
municate with each other 
by means of openings, so 
that the septa bound a rich 
network of spaces within 
the gland, which communicate on all sides with each other. 
Fig. 273. 
Diagrammatic section of a lymphatic gland, a.l., afferent, 
e.l., efferent, lymphatics; C, cortical substance; M, reticular 
cords of medulla; l.s., lymph-sinus; c, capsule, with tra- 
beculae, tr. Sec. 197.] 
389 
THE LEUCOCYTES OF LYMPHATIC GLANDS. 
These spaces are traversed by the follicular threads (fig. 27These 
represent the contents of the spaces, but are smaller than the spaces in which 
they lie, and do not come into contact anywhere with the walls of the spaces. 
If we imagine the spaces to be injected with a mass, which ultimately shrinks 
to one-half of its original volume, we obtain a conception of the relation of 
these follicular threads to the spaces of the gland. 
[The blood-vessels of the gland (A) lie within these follicular threads. 
They are surrounded by a tolerably thick crust of adenoid tissue, with very fine 
meshes (jr, x) filled with lymph-corpuscles, and with its surface (0, 0) covered 
by the cells of the adenoid reticulum, in such a way as to leave free communi- 
cation through the narrow meshes. The blood-vessels may enter at the hilum 
or at points on the surface of the gland. The large branches run in the 
Fig. 274. 
Network of adenoid tissue. The leucocytes have been pencilled out of 
the meshes {Stirling). X 350. 
trabeculae and septa, and from these finer branches traverse the lymph-paths 
and split up into a capillary plexus in the masses or strands of adenoid tissue. 
The vein passes out by the hilum. Nerves, medullated and non-medullated, 
enter the gland, but their terminations are un- 
known. Perhaps they go to the blood-vessels 
and the smooth muscular fibres of the septa.] 
[The fine network of adenoid tissue which 
traverses the lymph-paths, and in which the 
leucocytes lie, consists of fine bundles of fibrous 
tissue with cells—endothelial cells—at the nodes. 
This system is continuous with the fibrous tissue 
of the capsule and septa (fig. 274).] 
[The cellular elements, lymph-cells, or 
leucocytes are not all of one kind, as can be 
shown by differential staining, such as Ehrlich- 
Biondi’s fluid, which is a mixture of orange-G., 
methyl-green, and acid fuchsin. The most 
abundant leucocytes are (1) cells with a very 
small amount of colorless protoplasm surround- 
ing a faint violet-stained nucleus. (2) A second 
form has a large nucleus surrounded with bright 
rose-colored protoplasm. (3) There are “ granu- 
lar ” cells most abundant in the mesenteric 
glands. (4) A fourth form shows cells under- 
going degeneration. (5) Phagocytes are also 
Fig. 275. 
Section of a lymph-knot, or germ 
centre of a mesenteric lymph-gland. 
a, large, b, small leucocytes; c, mi- 
tosis; d, direct division of nucleus; 
e, cells which, besides a nucleus, 
contain large easily-stained bodies 
and some yellow granules. X 400. [Sec. 197. 
390 
THE LEUCOCYTES OF LYMPHATIC GLANDS. 
present, but they are usually found in the lymph-paths and medullary cords 
(Hoyer).'] 
Lymph-glands not only form leucocytes, but in them also cells break down, 
and the products of their disintegration are taken up by leucocytes and further 
changed by them. 
Between the surface of the follicular threads and the inner wall of all the 
spaces of the gland, lies the lymph-channel or lymph-path (B, B), which 
is traversed by a reticulum of adenoid tissue, containing relatively few lymph- 
corpuscles. It is very probable that these lymph-paths are lined by endo- 
thelium. 
Part of a lymphatic gland. A, vas afferens; B, B, lymph-paths; a, a, trabeculae seen on edge ; 
f f, follicular strand from the medulla; x, x, its adenoid reticulum; b, its blood-vessels; 
o, 0, narrow-meshed part limiting the follicular strands from the lymph-path. 
Fig. 276. 
The vasa afferentia (fig. 273, a.l.') of which there are usually several, 
expand upon the surface of the gland, perforate the outer capsule, and pour 
their contents into the lymph-paths of the gland (C). The vasa efferentia, 
which are less numerous than the afferentia, and come out at the hilum, form 
large, wide, almost cavernous dilatations, and they anastomose near the gland 
(<?./.). Through them the lymph passes out at the opposite surface of the gland. 
The lymph percolates through the gland, and passes along the lymph-paths, 
which represent a kind of rete mirabile interposed between the afferent and 
efferent lymph-vessels. 
During its passage through this complicated branched system of spaces, the Sec. 197.] 
PROPERTIES OF CHYLE AND LYMPH. 
391 
movement of the lymph through the gland is retarded, and, owing to the 
numerous resistances which occur in its path, it has very little propulsive 
energy. The lymph-corpuscles which lie in the meshes of the adenoid reticulum 
are washed out of the gland by the lymph-stream. The lymph-corpuscles lying 
within the follicular threads pass through the narrow meshes (0) into the lymph- 
paths. The formation of lymph-corpuscles either occurs locally, from division 
of the pre-existing cells, or new leucocytes wander out into the follicular 
threads. The movement of the lymph through the gland is favored by the 
muscular action of the capsule. When the capsule contracts energetically, it 
must compress the gland like a sponge, and the direction in which the fluid 
moves is regulated by the position and arrangement of the valves. 
[Formation of Leucocytes in Lymph-glands.—This takes place chiefly 
in the cortical alveoli. In the centre of each is a germ-centre, in the form 
of a spherical group of leucocytes, which stain more deeply with staining re- 
agents than the surrounding leucocytes. These cells divide by mitosis, and 
the chromatin filaments can be stained with saffranin or other chromatin dye 
(fig. 275). Mitosis takes place to a much less extent in the medullary cords 
and the cells of the lymph-stream itself.] 
Chemistry of Lymph-glands.— In addition to the constituents of lymph and leucocytes 
(| 24), the following chemical substances have been found in lymphatic glands—leucin and 
xanthin. 
198. PROPERTIES OF LYMPH AND CHYLE.—Lymph is 
an albuminous, colorless, clear alkaline fluid, containing lymph-corpuscles, 
which are identical with the colorless blood-corpuscles (§ 9). [Its specific grav- 
ity is 1012-1022.] In some places, e.g., in the thoracic duct, a few colored 
blood-corpuscles have been found. The lymph-corpuscles are supplied to the 
lymph and chyle from the lymphatic glands and the adenoid tissue. As to their 
source see § 200, 2. They also pass out of the blood-vessels and wander into 
the lymphatics. As red blood-corpuscles have also been seen to pass out of 
the blood-vessels, this explains the occasional presence of these corpuscles in 
some lymphatics; but when the pressure within the veins is high, near the cen- 
tral orifice of the thoracic duct, red blood-corpuscles may pass into the tho- 
racic duct. But we are not entitled to conclude from their pressure that 
lymph-cells form red blood-corpuscles. In addition, the chyle contains 
numerous fatty granules, each surrounded with an albuminous envelope. 
[Thus the chyle, in addition to the constituents of the lymph, contains, espe- 
cially during digestion, a very large amount of fat, in the form of the finely- 
emulsionized fat of the food, which gives it its characteristic white or milky 
appearance. During hunger, the fluid in the lacteals resembles ordinary lymph. 
The fine fat-granules constitute the so-called “molecular basis” of the 
chyle.] 
Composition of Lymph.—The lymph consists of lymph-plasma with 
lymph-corpuscles suspended in it. The corpuscles or leucocytes are de- 
scribed in § 24. The lymph-plasma contains the three so-called fibrin- 
factors, deiived very probably from the breaking up of lymph-corpuscles (§ 29). 
When lymph is withdrawn from the body, these substances cause it to coagu- 
late. Coagulation occurs slowly, owing to the formation of a soft, jelly-like, 
small “lymph-clot,” which contains most of the lymph-corpuscles. The 
exuded fluid or lymph-serum contains alkali-albuminate (precipitated by 
acids), serum-albumin (coagulated by heat), and paraglobulin—the latter two 
occurring in less amount but in the same proportion as in the blood-serum ; 37 
per cent, ofr the coagulable proteids is paraglobulin. 
[After rapid injection of peptone into the blood the lymph does not clot (Fano). Peptone 
injection profoundly alters the endothelial cells of the blood-capillaries.] [Sec. 198. 
392 
COMPOSITION OF CHYLE. 
[The same organic constituents occur in lymph as in blood-plasma, although 
in different proportions, but C02 and urea are more abundant in lymph than 
blood. The inorganic constituents are approximately the same in amount and 
in the same proportion in the two fluids:— 
Human Blood-plasma. 
Water, 
. 902.90 
Human Lymph. 
986.34 
Solids, 
• 97-10 
13.66 
Fibrin, 
Other proteids, 
4.05 
I.07 
. 78.84 
2.30 
Extractives, 
5.66 
I.51 
Inorganic salts, 
• 78.55 
8.78.] 
(1) Chyle is the name given to the fluid which occurs within the lacteals of 
the intestinal tract during the digestion of fatty food. It can only be obtained 
in very small amount before it is mixed with lymph, and hence the difficulty of 
investigating it. A few lymph-corpuscles occur even in the origin oP lac- 
teals within the villi, but their number increases in the vessels beyond the 
intestine, more especially after the chyle has passed through the mesenteric 
glands. The amount of solids, which undergoes a great increase during di- 
gestion, on the contrary, diminishes when chyle mixes with lymph. After a 
diet rich in fatty matters the chyle contains innumerable fatty granules (2-4 
Ij. in size). [This is the so-called “molecular basis” of the chyle.] The 
amount of fibrin factors increases with the increase of lymph-corpuscles as they 
are formed from the breaking up of the lymph-corpuscles; a diastatic ferment 
absorbed from the intestine; occasionally sugar; after much starchy food lac- 
tates; peptone in the leucocytes (§ 192, I, 3), and traces of urea and leucin. 
[The chyle contains a greater percentage of solids, as compared with lymph, 
while the fats are specially abundant in chyle.] 
The Chyle of a person who was executed contained 90.5 per cent, of water. 
Fibrin, . . trace 
Albumin, 7.1 
Fats, 0.9 
Extractives, 1.0 
Salts, 0.5 
Solids, 9.5 
Schmidt found the following inorganic substances in 1000 parts of chyle of ahorse:— 
Sodic chloride, . . 5.84 
Soda, 1.17 
Potash, 0.13 
Sulphuric acid, . . . 0.05 
Phosphoric acid, . . 0.05 
Calcic phosphate, . . 0.20 
Magnesic phosphate, . 0.05 
Iron, trace 
[The following table shows the composition of chyle in some animals:— 
ioo Parts Chyle contain 
Man. 
Dog. 
Horse. 
Water, 
90.5 
91.2 
92.8 
Solids, 
9-5 
8.8 
7.2 
Fibrin, 
O.I 
O.I 
O.I 
Proteids, 
7.0 
• 2.7 
4.0 
Fat, etc., 
1.0 
4-9 
i-5 
Extractives, 
Salts, 
} '•< { 
o-3 
0.8 
0.8 
0.8 
(Munk).] 
[Extravasations of Chyle and Chylous Ascites.—After ligature of the thoracic duct 
in dogs, the receptaculum chvli bursts and the chyle is discharged into the peritoneal cavity. 
Sometimes there is rupture of the lacteal paths in man, when the chyle passes into the perito- 
neum, causing chylous dropsy.] 
(2) The lymph obtained from the beginning of the lymphatic system also 
contains very few lymph-corpuscles; it is clear, transparent, and colorless, and Sec. 198.] 
COMPOSITION OF LYMPH AND CHYLE. 
393 
closely resembles the fluids of serous cavities. That the lymph coming from 
different tissues varies somewhat is highly probable, but this has not been 
proved. After lymph has passed through lymphatic glands, it contains more 
corpuscles, and also more solids, especially albumin and fat. Ritter counted 
8200 lymph-corpuscles in 1 cubic centimetre of the lymph of a dog. 
Lymph obtained from a lymphatic fistula in the leg of a man has an alkaline 
reaction and a saline taste, and the following composition : — 
Lymph 
(Hensen Dahnhardt). 
Cerebro-spinal Fluid 
(Iloppe-Seyler). 
Pericardial Fluid 
(v. Gorufi-Besanez). 
Water, 
98.74 
95-51 
Solids, 
I.25 
4.48 
Fibrin, 
O.08 
Albumin, 
0.14 
O.16 
2.46 
Alkali-albuminate, . . 0.09 
Extractives, 1 „ 
Urea, Leucin, ( ' ' * 
Salts, 0.88 
70vol.%of absorbed C02, 50% could 
be pumped out, and 20 % liberated 
by the addition of an acid. 
The cerebro-spinal fluid and ab- 
dominal lymph contain a kind of 
sugar (?) (without the property of 
rotating polarized light—Hoppe- 
Seyler). 
1.26 
[The following table from Munk shows the composition of lymph in man and some animals:— 
ioo Parts of Lymph contain 
Man, 
Horse. 
Ox. 
Water 
95-o 
95.8 
964 
Solids, 
5-o 
4.2 
3-6 
Fibrin, 
O.I 
O.I 
0.1 
Proteids, 
4-1 
2.9 
2.8 
Fats, etc., 
traces 
traces 
traces 
Extractives, 
0-3 
0.1 
0.1 
Salts, .... 
o-5 
1.1 
0.6] 
100 parts of the ash of lymph contained the following substances:— 
Sodium chloride, . . 74.48 
Soda, 10.36 
Potash, 3.26 
Lime, 0.98 
Magnesia, 0.27 
Phosphoric acid, . . . 1.09 
Sulphuric acid, .... 1.28 
Carbonic acid. .... 8.21 
Iron oxide, 0.06 
Just as in blood, potash and phosphoric acid are most abundant in the 
corpuscles ; while soda (chiefly sodium chloride) is most abundant in the 
lymph-serum. The potash and phosphoric acid compounds are most 
abundant in cerebro-spinal fluid, according to C. Schmidt. The amount of 
water in the lymph rises and falls with that of the blood. 
Gases of Lymph.—Dog’s lymph contains much C0.2—more than 40 vols. 
per cent., of which 17 per cent, can be pumped out, and 23 per cent, expelled 
by acids, while there are only traces of O and 1.2 vols. per cent. N. (.Ludwig. 
Hammarsten). See also p. 230. 
[The cerebro-spinal fluid contains a substance which reduces an alkaline solution of cupric- 
hydrate. It is not sugar but pyrocatechin. The potassic are in excess of the soda salts, while 
the fluid of meningoceles and chronic hydrocephalus contains proto-albumose, some serum- 
globulin, no serum-albumin, but the last is present in acute hydrocephalus fluid. No albumose 
is found in pericardial or pleuritic fluids (Halliburton). The fluid is not a simple exudation 
from the blood. It presents rather the characters of a secretion.] 
[Serosity or Lymph of Serous Cavities.—Ranvier has made the re- 
markable discovery that the fluid in normal serous cavities, e. g., the peritoneum, [Sec. 198. 
394 
QUANTITY OF LYMPH AND CHYLE. 
is usually not clear like water, but somewhat turbid or even opalescent. This 
fluid always contains red blood-corpuscles and several varieties of spherical 
colorless corpuscles varying in structure and reactions according to'the animal 
examined. In the fluid from the rabbit’s peritoneal cavity, nearly all the color- 
less cells have the same structure, although their diameter varies from 6 to 20 ;j.. 
The largest variety often contains many vacuoles. There are no cells so large 
either in the lymph or blood. Most of the cells exhibit amoeboid movements. 
If they are lymphatic cells, they have become greatly altered after leaving the 
vessels and passing into the peritoneal cavity. In the rat also there are color- 
less cells, some of which are amoeboid and others not. The last variety— 
non-amoeboid—is granular and very large, 20-25 in diameter, and are readily 
colored by fuchsin or methyl-violet. No corresponding cells exist in the rat or 
rabbit. In the pleuro-peritoneal cavity of reptiles similar large granular cells 
are found, comparable to those of the rat, but no large granular cells occur in 
the frog. Ranvier is of opinion that there is a close relationship between true 
clasmatocytes (p. 385) and the non-amceboid cells of the serosity of the pleuro- 
peritoneal cavity.] 
199. QUANTITY OF LYMPH AND CHYLE.—When it is stated 
that the total amount of the lymph and chyle passing through the large vessels 
in twenty-four hours is equal to the amount of the blood, it must be remem- 
bered that this is merely a conjecture. Of this amount one-half may be lymph 
and the other half chyle. The formation of lymph in the tissues takes place 
continually, and without interruption. Nearly 6 kilos, of lymph were collected 
in twenty four hours from a lymphatic fistula in the arm of a woman, by Gubler 
and Quevenne; 70 to 100 grms. were collected in 1 y2 to 2 hours from the 
large lymph-trunk in the neck of a young horse. The following conditions 
affect the amount of chyle and lymph :— 
(1) The amount of chyle undergoes very considerable increase during 
digestion, more especially after a full meal, so that the lacteals of the mesen- 
tery and intestine are distended with white or milky chyle. During hunger 
the lymph-vessels are collapsed, so that it is difficult to see the large trunks. 
(2) The amount of lymph increases especially with the activity of the 
organ from which it proceeds. Active or passive muscular movements 
greatly increase its amount. Lesser obtained in this way 300 cubic centimetres 
of lymph from a fasting dog, whereby its blood became so inspissated as to 
cause death. 
(3) All conditions which increase the pressure upon the juices of the 
tissues increase the amount of lymph, and vice versa. These conditions are :— 
(а) An increase of the blood-pressure, not only in the whole vascular system, but also 
in the vessels of the corresponding organ, augments the amount of lymph, and vice versa (Ludwig, 
Tomsa). This, however, is doubtful, as has been shown by Paschutin and Emminghaus. [In 
order to increase the amount of lymph depending upon pressure within the vessels, what 
must happen is increased pressure within the capillaries and veins.] 
(б) Ligature or obstruction of the efferent veins greatly increases the amount of lymph 
which flows from the corresponding parts (Bidder, Emminghaus). It may be doubled in 
amount. Tight bandages cause a swelling of the parts on the peripheral side of the bandage, 
owing to a copious effusion of lymph into the tissue (congestive oedema). 
(<r) An increased supply of arterial blood acts in the same way, but to a less degree. 
Paralysis of the vaso-motor nerves, or stimulation of vaso-dilator fibres, by increasing the supply 
of blood increases the amount of lymph; While diminution of the blood-supply, owing to 
stimulation of vaso-motor fibres or other causes, diminishes the amount. Even after ligature 
of both carotids, as the head is still supplied with blood by the vertebrals, the lymph-stream in 
the large cervical lymphatic does not cease. 
(4) When the total amount of the blood is increased, by the injection of blood or serum 
into the arteries, much fluid passes into the tissues and increases the formation of lymph. 
(5) The formation of lymph still goes on for a short time after death, and after complete 
essation of the action of the heart, but only to a slight extent. If fresh blood be caused to Sec. 199.] 
ORIGIN OF LYMPH. 
395 
circulate in the body of an animal, while it is still warm, more lymph flows from the lym- 
phatics. It appears as if the tissues obtained plasma from the blood for a time after the 
stoppage of the circulation. This perhaps explains the circumstance that some tissues, e. g., 
connective-tissues, contain more fluid after death than during life, while the blood-vessels have 
given out a considerable amount of their plasma after death. 
(6) The amount of lymph is increased under the influence of curare, and so is the amount 
of solids in the lymph (Lesser). A large amount of lymph collects in the lymph-sacs [especially 
the sub-lingual] of frogs poisoned with curare, which is partly explained by the fact that the 
lymph-hearts are paralyzed by curare. 
(7) The amount of lymph is also increased in inflamed parts. 
[(8) Injection of peptone into the blood causes a large increase in the rate of flow of lymph. 
In the thoracic duct it may be increased tenfold, notwithstanding the fall of blood-pressure due 
to the peptone injected. The amount of solids also increase (Heidenhain).] 
200. ORIGIN OF LYMPH.—(1) Source of the Lymph-Plasma.— 
The lymph-plasma may be partly regarded as fluid which has been pressed 
through the walls of the blood-vessels by the blood-pressure, i.e., by filtration 
into the tissues. The salts which pass most readily through membranes go 
through nearly in the same proportion as they exist in blood-plasma—the fibrin- 
factors to about two-thirds, and albumin to about one-half of that in the blood 
(p. 44). As in the case of other filtration-processes, the amount of lymph 
must increase with increasing pressure. 
Ludwig and Tomsa found that when they passed blood-serum under varying pressures through 
the blood vessels of an excised testis, the amount of transuded fluid which flowed from the 
lymphatics varied with the pressure. This “ artificial-lymph ” had a composition similar to 
that of the natural lymph. Even the amount of albumin increased with increasing pressure. 
The lymph-plasma is mixed in the different tissues with the decomposition products, the results 
of the metabolism of the tissues. 
[There are reasons for thinking that the formation of lymph is not entirely, 
or chiefly due to filtration, i.e., it is not merely a transudation from the blood- 
vessels. By some it is regarded as a secretory product of the cells of the 
capillary wall (Heidenhain).] 
[When sugar, egg-albumin, peptone, urea, or NaCl are injected into the blood they pass in a 
concentrated form into the increased lymph-stream. If peptone be injected the blood-pressure 
falls enormously, still these bodies pass into the lymph, so that their passage cannot be due 
entirely to blood-pressure. The increase of the lymph under (8) led Heidenhain to regard the 
formation of lymph not as a transudation, but as a true secretion from the blood-vessels. With 
the increase of the lymph-stream, the secretion of urine also increases. One may regard the 
lymph-system as a reservoir which temporarily takes up substances from the blood until they 
can be excreted by the urine (Heidenhain). Peptone when injected slowly into the blood is 
excreted in the urine, but if the renal vessels are tied it passes from the blood into the lymph. 
If it be rapidly injected it is chiefly thrown out into the lymph, and after a time it passes from 
the lymph in the tissues of the body into the thoracic duct and then enters the blood again.] 
[If peptone be injected into the lymphatic system it can be recovered un- 
changed. Thus the lymphatic glands have not the power to assimilate peptone 
and convert it into serum-albumin, as has been suggested by some observers 
(Shore).~\ 
When the muscles act, not only is the lymph poured out more rapidly, but 
more lymph is formed. The tendons and fasciae of the muscles of the skeleton, 
which are provided with numerous small stomata, absorb the lymph from the 
muscles. By the alternate contraction and relaxation of these fibrous structures, 
they act like suction-pumps, whereby the lymphatics are alternately filled and 
emptied, while the lymph is propelled onwards. Even passive movements 
act in the same way. If solutions be injected under the fascia lata, they may 
be propelled onwards to the thoracic duct by passive movements of the limb 
(Ludwig, Schweigger-Seidel). 
(2) The source of the lymph-corpuscles varies.—(1) A very consid- 
erable number of lymph-corpuscles are derived from the lymphatic glands 
(p. 391); they are washed out of these glands into the vas efferens by the 
lymph-stream; hence, the lymph always contains more corpuscles after it has 396 
[Sec. 200. 
ORIGIN AND DECAY OF LYMPH-CORPUSCLES. 
passed through a lymph-gland. Small isolated lymph-follicles permit corpus- 
cles to pass through their limiting layer into the lymph-stream. (2) Those 
organs whose basis consists of adenoid tissue and in whose meshes numerous 
lymph-corpuscles occur, e.g., the mucous membrane of the entire intestinal 
tract, red marrow of bone, and the spleen (§ 103). The cells reach the origin 
of the lymph-stream by their own amoeboid movements. (3) As lymph-cor- 
puscles are returned to the blood-stream, where they appear as colorless blood- 
corpuscles, so they again pass out of the blood-capillaries into the tissues, 
partly owing to their amoeboid movements, and they are partly expelled by the 
blood-pressure. In rare cases lymph-corpuscles wander from lymphatic spaces 
back again into the blood-vessels. 
Fine particles of cinnabar or milk-globules introduced into the blood soon pass into the lym- 
phatics. The extrusion of particles is greater during venous congestion than when the circula- 
tion is undisturbed, just as with diapedesis (§ 95); inflammatory affections of the vascular wall 
also favor their passage. The vessels of the portal system are especially pervious. 
(3) By mitotic division of the lymph-corpuscles (p. 391), and also 
by proliferation of the fixed connective-tissue corpuscles. This pro- 
cess certainly occurs during inflammation of many organs. This has been 
proved for the excised cornea kept in a moist chamber; the nuclei of the 
cornea-corpuscles also proliferate. 
That the connective-tissue corpuscles proliferate is shown by the enormous production of 
lymph-corpuscles in acute inflammations (with the formation of pus), e.g., in extensive erysipelas, 
and inflammatory purulent effusions into serous cavities, where the number of corpuscles is too 
great to be explained by the wandering of blood-corpuscles out of the blood-vessels. 
Decay of Lymph-Corpuscles.—The lymph-corpuscles disappear partly 
where the lymphatics arise, and also in the lymphatic glands. The presence 
of the fibrin-factors in the lymph—formed as they are from the breaking-up of 
lymph-corpuscles—seem to indicate this. In inflammation of connective-tissue, 
in addition to the formation of numerous new lymph-corpuscles, a considerable 
number seems to be dissolved ; hence the lymph, and also the blood, in this 
case contains more fibrin. Lymph-corpuscles are also dissolved within the 
blood-stream, and help to form the fibrin-factors, [or rather the precursor of 
fibrin.] 
201. MOVEMENT OF CHYLE AND LYMPH.—The ultimate 
cause of the movement of the chyle and lymph depends upon the difference 
of the pressure at the origin of the lymphatics, and the pressure where the 
thoracic duct opens into the venous system. 
(1) The forces which are active at the origin of the lymphatics are con- 
cerned in moving the lymph, but these must vary according to the place of 
origin—(a) The lacteals receive the first impulse towards the movements of 
their contents—the chyle—from the contraction of the muscular fibres of 
the villi (pp. 366, 372). When these contract and shorten, the axial lacteal 
is compressed, and its contents are forced in a centripetal direction towards 
the large lymphatic trunks. When the villi relax, the numerous valves prevent 
the return of the chyle into the villi, (b) Within those lymphatics which 
take the form of perivascular spaces, every time the contained blood-vessel is 
dilated the surrounding lymph will be pressed onwards. (c) In case of the 
pleural lymphatics with open mouths, every inspiratory movement acts like 
a suction-pump upon the lymph, and the same is the case with the openings or 
stomata of the lymphatics on the abdominal side of the diaphragm. (d) In 
the case of those vessels which begin by means of fine juice-canals, the move- 
ment of the lymph must largely depend upon the tension of the juices of 
the parenchyma, and this again must depend upon the tension or pressure 
in the blood-capillaries, so that the blood-pressure acts like a vis a tergo in the 
rootlets of the lymphatics. Sec. 201.] 
MOVEMENT OF CHYLE AND LYMPH. 
397 
[In some organs peculiar pumping arrangements are brought into action. The abdominal 
surface of the central tendon of the diaphragm is provided with stomata, or open communica- 
tions between the peritoneal cavity and the lymphatics in the substance of the tendon. Von 
Recklinghausen found that milk put upon the peritoneal surface of the central tendon showed 
little eddies, caused by the milk-globules passing through the stomata and entering the lym- 
phatics. The central tendon consists of two layers of fibrous tissue arranged in different 
directions (fig. 277, b, c). When the diaphragm moves during respiration, these layers are 
alternately pressed together and pulled apart. Thus the spaces are alternately dilated and con- 
tracted, lymph being drawn into the lymphatics through the stomata (fig. 277, h). The same 
kind of pumping mechanism exists over the costal pleura. The fascia covering the muscles is 
another similar mechanism. The fascia consists of two layers of fibrous tissue, with intervening 
lymphatics (fig. 278). When a muscle contracts, lymph is forced out from between the layers 
of the fascia, while, when it relaxes, the lymph from the muscle, carrying with it some of the 
waste products of muscular action, passes out of the muscle into the fascia, between the now 
partially separated layers.] 
[Ludwig’s Experiment.—Tie a respiration cannula in the trachea of a dead rabbit; cut 
across the body of the animal immediately below the diaphragm; remove the viscera, and ligature 
the vessels passing between the thorax and abdomen; tie the thorax to an iron ring, and hang it up 
with the head downwards; pour a solution of Berlin blue upon the peritoneal surface of the dia- 
phragm ; connect the respiration cannula either with a pair of bellows or an apparatus for 
artificial respiration, and imitate the respiratory movements. After a few minutes the lymphatics 
are filled with a blue injection showing a beautiful plexus.] 
(2) Within the 
lymph-trunks them- 
selves, the indepen- 
dent contraction 
of their muscular 
fibres partly aids the 
lymph stream. Heller 
observed in the mes- 
entery of the guinea- 
pig that the peri- 
staltic movement of the lymphatic wall passed m a centripetal direction. T he 
numerous valves prevent any reflux. The contraction of the surrounding 
muscles, and pressure upon the vessels and the tissues, aid the current. If the 
outflow of blood from the veins is interfered with, lymph flows copiously from the 
corresponding tissues. [If a cannula be tied in a lymphatic of a dog, a few 
drops of lymph flow out at long intervals. But if even passive movements of the 
limb be made, e. g., simply flexing and extending the limb, the outflow becomes 
very considerable and continuous.] 
(3) The lymph-glands, which occur in the course of the lymphatics, offer 
very considerable resistance to the lymph-stream, which must pass through the 
lymph-paths, whose spaces are traversed by adenoid tissue, and contain a few 
lymph-corpuscles. But this is, to a certain extent, compensated for by the 
non-striped mus- 
cle which exists 
in the capsule 
and trabeculae of 
the glands. 
When they con- 
tract they force 
on the lymph, 
while the valves 
prevent its reflux. 
Enlarged lym- 
phatic glands 
have been seen 
to contract when 
Fig. 277. 
Section of central tendon of diaphragm. The injected lymph-spaces, 
h and h, are black. At /"the walls of the space have collapsed. 
Injected lymph-spaces (black) from the fascia lata of the dog. 
Fig. 278. 398 
MOVEMENT OF THE LYMPH. 
[Sec. 201. 
stimulated electrically. [Botkin has stimulated enlarged lymphatic glands with 
electricity in cases of leukaemia, and found that they contracted somewhat.] 
(4) The lymph-vessels gradually join to form larger vessels, and finally end 
in one trunk. Thus the sectional area diminishes, so that the velocity of the 
current and the pressure are increased. Nevertheless, the velocity is always 
small; it varies from 230 to 300 millimetres per minute in the large lymphatic 
in the neck of a horse, a fact which, enables us to conclude that the movement 
must be very slow in small vessels. The lateral pressure at the same place 
was 10 to 20 mm., and in the dog 5 to 10 mm. of a weak solution of soda, 
although it was =12 mm. Hg in the thoracic duct of a horse. 
(5) The respiratory movements exercise a considerable influence upon 
the lymph-stream in the thoracic duct, and in the right lymphatic duct; every 
inspiration favors the passage of the venous blood, and also of the lymph 
towards the heart; indeed, the pressure in the thoracic duct may even become 
negative. [The diastolic suction of the heart, by diminishing the pressure in 
the subclavian vein, also favors the inflow of lymph into the thorax.] 
(6) Lymph-hearts exist in certain cold-blooded animals. The frog has two axillary 
hearts (above the shoulder near the vertebral column), and two Sacral hearts, one on each 
side of the coccyx near the anus (fig. 279, L). They beat, but not synchronously, about sixty 
times per minute, and contain 10 cubic millimetres of lymph. They have transversely-striped 
muscular fibres in their walls, and are also provided with nerve-ganglia. The posterior pair 
pump the lymph into the branch of the vena iliaca communicans, and the anterior pair into the 
vena sub-scapularis. Their pulsation depends partly, but not exclusively, upon the spinal cord, 
for if the cord be rapidly destroyed, they may cease to pulsate, but not unfrequently they con- 
tinue to pulsate after removal of the cord. [If the cord, however, be destroyed gradually, they 
continue to beat (Kabrhel).~\ A second source of their pulsatile movements is to be sought for 
in Waldeyer’s ganglia. Stimulation of the skin, intestine, or blood-heart influences them reflexly 
—partly accelerating and partly retarding them, [most frequently arresting them in diastole, so 
that there seems to be an inhibitory mechanism in the cord, but it is not affected by atropine 
{Kabrhel)l\ If the coccygeal nerve, which connects the sacral hearts to the spinal cord, be 
divided, these effects do not occur. Strychnia accelerates their movements, and so does heating 
of the spinal cord; but if the cord be cooled, they are retarded. A lymph-heart arrested by 
being exposed, or after the action of muscarin, can be caused to beat by filling it under pressure, but 
this is not the case when the arrest is caused by destruction of its nerves. Antiarin paralyzes 
the lymph-heart and the blood-heart at the same time, while curare paralyzes the former alone. 
In other amphibians there are two lymph-hearts ; in the ostrich and cassowary and some swim- 
ming birds, and in the embryo chick 1 or 2. They occur in some fishes, e.g., near the caudal 
vein of the eel. 
(7) The nervous system has a direct effect upon the lymph-stream, on 
account of its connection with the muscles of the lymphatics and lymph-glands, 
and with the lymph-hearts where these exist. Kiihne observed that the cornea 
corpuscles contracted when the cor- 
neal nerves were stimulated, [and Hoff- 
man has described the termination of 
nerves in connective-tissue corpuscles.] 
Goltz also observed that when a dilute 
solution of common salt was injected 
under the skin of a frog, it was rapidly 
absorbed, but if the central nervous 
system had been destroyed, it was not 
absorbed. 
If Inflammation be produced in the hind 
legs of a dog, and if the sciatic nerve be 
divided on one side, oedema and a simultane 
ous increase of the lymph stream occur on that 
side. [A combination of congestion and in- 
flammation greatly increases the lymph-stream, 
and this is still more the case when the nerves 
are divided at the same time.] 
_ Ligature the leg of a frog, except the nerves 
Fig. 279. 
Posterior pair of lymph-hearts (L) of the frog. Sec. 2oi.] 
ABSORPTION AND PRODUCTION OF EFFUSIONS. 
399 
so as to arrest the circulation, and place the leg in water; it swells up very rapidly, but a dead 
limb does not swell up. So that absorption is independent of the continuance of the circulation. 
Section of the sciatic nerve, or destruction of the spinal cord (but not section of the brain), 
arrests absorption. 
202. ABSORPTION OF PARENCHYMATOUS EFFUSIONS. 
—Fluids which pass from the blood-vessels into the spaces in the tissues, or those 
injected subcutaneously, are absorbed chiefly by the blood-vessels but also by 
the lymphatics. Small particles, as after tattooing with cinnabar or China ink, 
may pass from the tissue-spaces into the lymphatics—and so do blood-corpuscles 
from extravasations of blood, and fat-granules from the marrow of a broken 
bone. If all the lymphatics of a part are ligatured, absorption takes place 
quite as rapidly as before ; hence, absorbed fluid must pass through the thin 
membranes of the blood-vessels. The corresponding experiment of ligaturing 
all the blood-vessels, when no absorption of the parenchymatous juices take 
place, does not prove that the lymphatics are not concerned in absorption, for, 
after ligaturing the blood-vessels of a part, of course the formation of lymph, 
and also the lymph-stream, must cease. When fluids are injected under the 
skin, absorption takes place very rapidly—more rapidly than when the substance 
is given by the mouth. The subcutaneous injection of drugs is extensively 
used, but of course the substances used must not corrode, irritate, or coagulate 
the tissues. 
Some substances do not act when given by the mouth, as snake poison, poisons from dead 
bodies, or putrid things, although they act rapidly when introduced subcutaneously. If 
emulsin be given by the mouth, and amygdalin be injected into the veins of an animal, 
hydrocyanic acid is not formed, as the emulsin seems to be destroyed in the alimentary canal. 
If the emulsin, however, be injected into the blood, and the amygdalin be given by the mouth, 
the animal is rapidly poisoned, owing to the formation of hydrocyanic acid, as the amygdalin is 
rapidly absorbed from the intestinal canal. The amygdalin, a glucoside (C20H27N0U), is 
acted upon by fresh emulsin like a ferment ; it takes up 2(H20) and yields hydrocyanic acid 
(CHN), + oil of bitter almonds (C7II60), -f- sugar 2(C6H1206). Serum injected subcu- 
taneously is rapidly absorbed; it is decomposed within the blood-stream, and increases the 
amount of urea. Albuminous solutions, oil, peptones, and sugars are also absorbed. 
203. CEDEMA, DROPSY, AND SEROUS EFFUSIONS.—[Dropsy.—As aptly 
illustrated by Lauder Brunton, the lymph spaces may be represented by cisterns, each of which 
is provided with supply pipes—the arteries and capillaries; while there are two exit pipes— 
the veins and lymphatics. In health, the balance between the inflow and outflow is such that 
the spaces are merely moistened with fluid. When a cannula is placed in a lymphatic vessel in 
a dog, only a few drops of lymph flow out at long intervals, but if the veins of the limb be 
ligatured, the lymph flows much more quickly. This is in part due to the increased transuda- 
tion of fluid from the small blood-vessels, but it may also be due to fluid passing away by 
the lymphatics when it can no longer be carried away by the veins. We cannot say what is 
the relative share of the veins and the lymphatics, nor in the above experiment do we know 
how much is due to increased transudation or diminished absorption. When there is an undue 
accumulation of fluid more or less like serum in the lymph-spaces, we have the condition 
termed dropsy. When there is general dropsy it is called anasarca.] 
CEdema.—If the efferent veins and lymphatics of an organ be ligatured, or if resistance be 
offered to the outflow of their contents, congestion and a copious transudation of lymph into the 
tissue take place. These are most marked in the skin and subcutaneous cellular tissue. The 
soft parts swell up, without pain or redness, and a doughy swelling, which pits on pressure 
with the finger, results. These are the signs of lymph-congestion, which is called oedema when 
the fluid is watery and localized. 
Under similar circumstances lymph is effused into the serous cavities. [In the peritoneum 
it is ascites—thorax, hydro-thorax—pericardium, hydro-pericardium—cranium, hydro- 
cephalus-tunica vaginalis, hydrocele—joints, hydrarthrosis, etc.] If, at the same time, a 
large number of colorless blood-corpuscles pass out of the blood-vessels into the cavity, the 
fluid becomes more and more like pus. In order that these corpuscles may proliferate, a con- 
siderable percentage of albumin is necessary. When the pressure within the serous cavity rises 
above that in the small blood-vessels, water may pass into the blood. These sero-purulent 
effusions not unfrequently undergo changes, and yield decomposition-products, such as leucin, 
tyrosin, xanthin , kreatin, kreatinin (?), uric acid (?), urea. Endothelium from the serous 400 
PHYSIOLOGY OF TRANSUDATIONS. 
[Sec. 203. 
cavity, sugar in pleuritic effusions and in oedemas with little albumin, cholesterin frequently in 
hydrocele fluid, and succinic acid in the fluid of echinococci have all been found in these 
effusions. The effusion of lymph may arise not only from pressure upon the lymphatics, but 
also from inflammation and thrombosis of the lymphatics themselves, in which cases not unfre- 
quently new lymphatics are formed, so that the communication is re-established. Sometimes 
the ductus thoracicus bursts and lymph is poured directly into the abdomen or thorax. [Liga- 
ture of the thoracic duct results in rupture of the receptaculum chyli and escape of chyle and 
lymph into the large serous cavities (Ludwig).\ 
When dropsy or effusion of fluids occurs into serous cavities, there is always a greater transu- 
dation of fluid through the blood-vessels. The abdominal blood-vessels, and those which yield 
a watery effusion under normal circumstances, are those most liable to be affected. 
Transudation is favored by—(i) Venous congestion, so as to raise the blood-pressure, 
in which case the effusion usually contains little albumin and few lymph corpuscles, while the 
colored corpuscles, on the contrary, are more numerous the greater the venous obstruction. 
Ranvier produced oedema artificially by ligaturing the vena cava in a dog, and at the same time 
dividing the sciatic nerve. The paralytic dilatation of the blood-vessels thereby produced 
caused an increased amount of blood to pass to the limb, while the blood-pressure was raised, 
and both factors favored the transudation of fluid. [Ranvier’s experiment proves that mere liga- 
ture of the venous trunk of a limb by itself is not sufficient to cause oedema. The oedema is 
due to the concomitant paralysis of the vaso-motor nerves. If the motor roots of the sciatic 
nerve alone be divided along with ligature of the vena cava, no oedema occurs, but if the vaso- 
motor fibres are divided at the same time, the limb rapidly becomes oedematous. There is such 
an increased transudation through the vascular walls that the veins and lymphatics cannot 
remove it with sufficient rapidity, and oedema occurs. If there be weakness of the vaso-motor 
nerves, slight obstruction is sufficient to produce oedema.] When the leg-veins are occluded 
with an injection of gypsum, oedema occurs. (2) Some unknown physical changes occur in 
the protoplasm of the endothelium of the capillaries and blood-vessels, which favor the transu- 
dation of albumin, haemoglobin, and even blood-corpuscles. This occurs when abnormal sub- 
stances accumulate in the blood—e. g., dissolved haemoglobin—and when the blood contains 
little O or albumin. The same has been observed after exposure to too high temperatures and 
the swelling of soft parts in the neighborhood of an inflammatory focus seems due to the transuda- 
tion of fluid through the altered vascular wall. It is probable that a nervous influence may affect 
particular areas through its action on the blood-vessels of the part (it may be upon the protoplasm 
of the blood-capillaries). The transudations of this nature usually contain much albumin and 
many lymph-corpuscles. (3) When the blood contains a very large amount of water, the 
tendency to transudation of fluid is increased. After a time it may produce the changes indica- 
ted in (2), and when long continued may increase the permeability of the vascular wall. 
Watery lymphatic effusions from watery blood—“ cachectic oedema”—occur in feeble and 
badly-nourished individuals. [One of the commonest forms of dropsy is the slight oedema of 
the legs in anaemic persons, in whom the heart and lungs are healthy. Many factors are in- 
volved—the blood-pressure, watery condition of the blood, the condition of nutrition of the 
capillaries, and probably a tendency to vaso-motor paresis (Brunlon).] 
[The fluid poured out varies according to the rapidity with which this occurs. In acute 
inflammations effusion or exudation takes place rapidly, and the fluid contains the precursor of 
fibrin, so that it tends to coagulate spontaneously. There is every gradation between the non- 
coagulable hydrocele fluid and the coagulable exudation in inflammation. The fluids in different 
dropsies vary in composition, and some have more cells in them, depending on local causes, as 
in some situations absorption is more active than in others. The pleural fluid contains most 
solids, then ascitic, cerebro spinal, and, lastly, that in the subcutaneous tissue. Transudation 
corresponds to the process of filtration through animal membranes; i. e., the transudation contains 
only those substances already present in the blood-plasma. The filtrate may even contain 
more salts than the original fluid, as is often the case with fluids containing crystalloid and 
colloid bodies. Senator finds, in cases of oedema of the leg, that increase of the venous pressure 
increases the proteids in the transudation, but causes no essential change in the amount of the 
salts.] 
[(4) Ostroumoff found that stimulation of the lingual nerve not only causes the blood-vessels 
of the tongue to dilate, but that the corresponding side of the tongue becomes oedematous. If 
a solution of dilute hydrochloric acid or quinine ($ 145) be injected into the duct of the sub- 
maxillary gland, and the chorda tympani stimulated, there is no secretion of saliva, but the 
gland becomes oedematous. In an animal poisoned with atropin, stimulation of the chorda causes 
dilatation of the blood-vessels, although there is no secretion of saliva, nevertheless the gland 
does not become oedematous (Heidenhain). As Brunton suggests, this experiment points to 
some action of atropin on the blood-vessels which has hitherto been entirely overlooked.] 
204. COMPARATIVE PHYSIOLOGY.—In the frog large lymph-sacs, lined with 
endothelium, exist under the skin, while large lymph sacs lie in relation with the vertebral column Sec. 204.] 
COMPARATIVE AND HISTORICAL. 
401 
—one on each side—separated from the abdominal cavity by a thin membrane, perforated with 
stomata. This is the cysterna lymphatica magna of Panizza. Some amphibians and many 
reptiles have under the skin large lymph-spaces, which occupy the whole of the dorsal region 
of the body. All reptiles and the tailed amphibians have large elongated reservoirs for lymph 
along the course of the aorta. The lymph-apparatus of the tortoise (fig. 270) is very extensive. 
The osseous fishes have in the lateral parts of their backs an elongated lymph-trunk, which 
reaches from the tail to the anterior fins, and is connected with the dilated lymphatic rootlets 
in the base of the tail and in the fins. The largest internal lymph-sinus is in the region of the 
oesophagus. Many birds possess a sinus-like dilatation or lymph-space in the region of the 
tail. The lymph-spaces communicate with the venous system—with valves properly arranged 
—usually in connection with the upper vena cava. Lymph-hearts have already been referred to 
(§ 201, 6). In carnivora the lymph-glands of the mesentery are united into one large compact 
mass, the so-called “ pancreas Asellii.” 
205. HISTORICAL.—Although the Hippocratic School was acquainted with the lymph- 
glands from their becoming swollen from time to time, and although Herophilus and 
Erasistratus had seen the mesenteric glands, yet Aselli (1662) was the first who accurately 
described the lacteals of the mesentery with their valves. Pecquet (1648) discovered the 
receptaculum chyli; Rudbeck and Thom. Bartholinus the lymphatic vessels (1650-52); 
Eustachius (1563) was acquainted with the thoracic duct, which Gassendus (1654) maintained 
that he was the first to see; Lister noticed that the chyle became blue when indigo was injected 
into the intestine (1671); Sommering observed the separation of fibrin when lymph coagulated ; 
Reuss and Emmert discovered the lymph-corpuscles. The chemical investigations date from 
the first quarter of this century; they were carried out by Lassaigne, Tiedemann, Gmelin, and 
others. The two last-named observers noticed that the white color of chyle was due to the 
presence of fatty granules. Physiology of Animal Heat. 
206. SOURCES OF HEAT.—The heat of the body is an uninterrupted 
evolution of kinetic energy, which we must represent to ourselves as due to 
vibrations of the corporeal atoms. The ultimate source of the heat is con- 
tained in the potential energy taken into the body with the food, and with the 
O of the air absorbed during respiration. The amount of heat formed de- 
pends upon the amount of energy liberated. 
The energy of the food-stuffs may be called “latent heat,” if we assume 
that when they are used up in the 
body, chiefly by a process of com- 
bustion, kinetic energy is liberated 
only in the form of heat. As a 
matter of fact, however, mechanical 
energy and electrical energy are de- 
veloped from the potential energy. 
In order to obtain a unit-measure 
for the energy liberated, it is ad- 
visable to express all the potential 
energy as heat units. 
Calorimeter.—This instrument 
enables us to transform the potential 
energy of the food into heat, and, 
at the same time, to measure the 
number of heat-units produced. 
Favre and Silbermann used a water- 
calorimeter (fig. 280). The substance to 
be burned is placed in a large cylindrical 
combustion-chamber (K), suspended in a 
large cylindrical vessel (L) filled with water 
(70), so that the combustion-chamber is 
completely surrounded by the water. Three 
tubes open into the upper part of the cham- 
ber; one of them (O) supplies the air which 
is necessary for combustion, it reaches 
almost to the bottom of the chamber; the 
second (a) is fixed in the middle of the lid, 
and is closed above with a thick glass plate, 
and on this is placed, at an angle, a small 
mirror (j), which enables an observer to 
look into the chamber, and observe the pro- 
cess of combustion at c. The third tube (d) is used only when combustible gases are to be 
burned in the chamber. It can be closed by means of a stop-cock. A lead tube (e, e), with 
many twists, passes from the upper part of the chamber through the water, and finally opens at 
g. The gaseous products of combustion pass out through this tube, and in doing so help to heat 
the water. The cylindrical vessel with the water is closed with a lid which transmits the four 
tubes. The water-cylinder stands on four feet within a large cylinder (M), which is filled with 
some good non-conductor of heat, and this again is placed in a large vessel filled with water 
(W). This is to prevent any heat reaching the inner cylinder from without. A weighed quantity 
Fig. 280. 
Water-calorimeter of Favre and Silbermann Sec. 206.] 
SOURCES OF HEAT AND CALORIMETERS. 
403 
of the substance (c) to be investigated is placed in the combustion-chamber. When combustion 
is ended, during which the inner water must be repeatedly stirred, the temperature of the water 
is ascertained by means of a delicate thermometer. If the increase of the temperature and the 
amount of water are known, then it is easy to calculate the number of heat-units produced by 
the combustion of a known weight of the substance (see Introduction). 
The ice-calorimeter may also be used. The inner cylinder is filled with ice and not with 
water, and ice is also placed in the outer cylinder to prevent any heat from without from acting 
upon the inner ice. The heat given 
off from the combustion - chamber 
causes a certain amount of the ice to 
melt, and the water thereby produced 
is collected and measured. It re- 
quires 79 heat-units to melt I grm. of 
ice to i grm. of water at o° C. 
[The amount of heat produced by a 
living animal is similarly measured. 
The animal (fig. 281), in a cage, is 
placed in a large vessel, which is 
placed within another vessel, and the 
interspace filled with water. The 
whole should be enclosed in a large box 
packed with fur, shavings, feathers, 
or other bad conductor of heat. A 
tube, D, opens into the inner space, 
and from it there is an exit tube, D', 
which winds many times in the water- 
space beneath. Air passes in through 
D and out by D/. The temperature 
of the water is ascertained by ther- 
mometers T and T/, while the water 
is moved by a stirrer (S) placed between the two. In Rosenthal’s calorimeter, one cylinder, 
surrounded by an air-jacket, is placed inside another, and the animal is placed in the inner cyl- 
inder.] 
Just as in a calorimeter, although much more slowly, the food-stuff's within 
our body are burned up, oxygen being supplied, and thus potential energy is 
transformed into kinetic energy, which, in the case of a person at rest, almost 
completely appears in the form of heat. 
Heat-Units.—Favre, Silbermann, Frankland, Rechenberg, B. Danilewsky, and others have 
made calorimetric experiments on the heat produced by food. According to Danilewsky, 1 
gram of the following dry substances yields heat-units :— 
Water-calorimeter of Dulong. 
Fig. 281. 
Casein, . . . 5855 
Fibrin, . . . 5772 
Peptone, . . 4876 
Glutin, . . . 5493 
Ox-blood, . . 5900 
Ox-flesh, . 5724 
Vegetable 
fibrin, . . 6231 
Glutin, . . .6141 
Legumin, . .5573 
Palmitin, . . 8883 
Olein, . . . 8958 
Stearin, . . . 9036 
Ox-fat . . . 9686 
Glycerin, . . 4179 
Starch, . . . 4479 
Dextrose, . . 3939 
Maltose, . .4163 
Milk-sugar, . 4162 
Cane-sugar, .4173 
Cow’s milk, . 5733 
Woman’s 
milk, . . . 4837 
Egg-yelk, . . 4479 
Potatoes, . . 4234 
Rye-bread, .4471 
Wheat-bread, 4351 
Rice, .... 4806 
Peas, .... 4889 
Buckwheat, . 4288 
Maize, . . .5188 
Alcohol, . . 6980 
Urea, .... 2537 
Muscle 
Extractives 
(Liebig’s) 
4400 
Flesh extract, 3216 
Acetic acid, .3318 
Butyric acid, . 5647 
Palmitic acid, 9316 
As albumin is only oxidized to the stage of urea, we must deduct the heat-units obtainable 
from urea from those of albumin, and as 1 part of albumin yields in round numbers about of 
urea, we obtain about 5100 calories (= 2170 kilogram metres) for x grm. of albumin. 
Isodynamic foods, i.e., those that produce an equal amount of heat; 100 grms. animal 
albumin (after deducting the heat-units of urea) = 52 fat =114 starch = 129 dextrose; 100 
grms. fat are isodynamic with 243 dry flesh or 225 of dry syntonin (Rubner); 100 grms. of 
vegetable albumin = 55 fat = 121 starch = 137 dextrose (Danilewsky). Rubner calculated 
that in man, with a mixed diet, the available heat-units for 1 grm. of albumin = 4100; 1 grm. 
fat = 9300; and for 1 grm. carbohydrate = 4100 calories. 
When we know the weight of any of the above-named substances consumed 
by a man in twenty-four hours, a simple calculation enables us to determine SOURCES OF HEAT-PRODUCTION. 
[Sec. 206. 
how many heat-units are formed in the body by oxidation, i. e., provided the 
substance is completely oxidized. 
[Several sources of heat-production or thermogenesis are to be 
found in all tissues wherever oxidation is going on. The metabolism of proto- 
plasm is always associated with the evolution of heat.] 
(1) In the transformation of the chemical constituent of the food, endowed with 
a large amount of potential energy into such substances as have little or no energy. 
The organic substances used as food consist of C, H, O, N, so that there takes 
place—(a) Combustion of C into C02, of H into H20, whereby heat is pro- 
duced; 1 grm. C burned to produce C02 yields 8080 heat-units, while 1 grm. 
H oxidized to H20 yields 34,460 heat-units. The O necessary for these pur- 
poses is absorbed during respiration, so that, to a certain extent, at least, the 
amount of heat produced may be estimated from the amount of O consumed. 
The same consumption of O gives rise to the same amount of heat whether it is 
used to oxidize H or C (Pfluger). There is a relation, amounting to cause and 
effect, between the amount of heat produced in the body and the O consumed. 
The cold-blooded animals, which consume little O, have a low temperature; 
amongst warm-blooded animals, 1 kilo, of a living rabbit takes up within an 
hour 0.914 grm. O, and its body is heated to a mean of 38° C. 1 kilo, of a 
living fowl uses 1.186 grms. O, and gives a mean temperature of 43.90 C. The 
amount of heat produced is the same whether the combustion occurs slowly or 
quickly; the rapidity of the metabolism, therefore, affects the rapidity, but not 
the absolute amount of heat-production. The combustion of inorganic sub- 
stances in the body, e.g., of the sulphur into sulphuric acid, the phosphorus 
into phosphoric acid, is another, although very small, source of heat. 
[The muscles form about the half of the whole mass of the body and the 
bones nearly the other half. In the latter, oxidation does not go on actively, 
so that the muscles must be the great seats of heat-production or thermogenesis 
in the body. This view is supported by the fact that the blood leaving a 
muscle at rest contains more C02 than the blood in the right ventricle. Mus- 
cular exercise greatly increases the metabolism and the C02 excreted (§ 126), 
but at the same time, there is a great increase in heat-production. The muscles, 
therefore, are the great thermogenic tissues, and they yield -|ths of the heat in 
health. The several secreting glands, especially the liver and the alimentary 
canal, during digestion, are also foci of heat-formation.] 
(,b) In addition to the processes of combustion or oxidation, all those chemi- 
cal processes in our body, by which the amount of the available potential 
energy which is present is diminished, in consequence of a greater satisfaction 
of atomic affinities, lead to the production of heat. In all cases where the 
atoms assume more stable positions with their affinities satisfied, chemical 
energy passes into kinetic thermal energy, as in the alcoholic fermentation of 
grape-sugar, and other similar processes. 
Heat is also developed during the following chemical processes: — 
(a) During the union of bases with acids. The nature of the base determines the amount of 
heat produced, while the nature of the acid is without effect. Only in those cases where the acid, 
e g., C02, is unable to neutralize the alkaline reaction, the amount of heat produced is less. 
The formation of compounds of chlorine (e.g., in the stomach) produces heat. 
(/3) When a neutral salt is changed into a basic one. In the blood the sulphuric and phos- 
phoric acids derived from the combustion of S and P are united with the alkalies of the blood 
to form basic salts. The decomposition of the carbonates of the blood by lactic and phosphoric 
acids form a double source of heat, on the one hand, by the formation of a new salt, and, on the 
other, by the liberation of C02, which is partly absorbed by the blood. 
(y) The combination of haemoglobin with O (§ 36). 
During those chemical processes, whereby the heat of the body is produced, 
heat-absorbing intermediate compounds are not unfrequently formed. Thus, in Sec. 206.] 
SOURCES OF HEAT-PRODUCTION. 
405 
order that the final stage of more complete saturation of the affinities be reached, 
intermediary atomic groups are formed, whereby heat is absorbed. Heat is also 
absorbed when the solid aggregate condition is changed during retrogressive 
processes. But these intermediary processes, whereby heat is lost, are very 
small compared with the amount of heat liberated when the end-products are 
formed. 
(2) Certain physical processes are also a source of heat.—(a) The trans- 
formation of the kinetic mechanical energy of internal organs, when the 
work done is not transferred outside the body, produces heat. Thus the whole 
of the kinetic energy of the heart is changed into heat, owing to the resistance 
opposed to the blood-stream (§ 93). The same is true of the mechanical energy 
evolved by many muscular viscera. The torsion of the costal cartilages, the 
friction of the current of air in the respiratory organs, and the ingesta in the 
digestive tract, all yield heat. 
An excessively minute amount of the mechanical energy of the heart is transferred to sur- 
rounding bodies by the cardiac impulse and the superficial pulse-beats, but this is infinitesimally 
small. During respiration, when the respiratory gases and other substances are expired, a very 
small amount of energy disappears externally, which does not become changed into heat. If 
we assume that the daily work of the circulation exceeds 86,000 kilogram-metres, the heat 
evolved is equal to 204,000 calories in twenty-four hours ($ 93), which is sufficient to raise the 
temperature of a person of medium size 2° C. 
('b) When, owing to muscular activity, the body produces work which is 
transferred to external objects, e. g., when a man ascends a tower or mountain, 
or throws a heavy weight, a portion of the kinetic energy passes into heat, 
owing to friction of the muscles, tendons, and the articular surfaces, as well as 
to the shock and pressure of the ends of the bones against each other. 
(V) The electrical currents which occur in muscles, nerves, and glands very 
probably are changed into heat. The chemical processes which produce heat 
evolve electricity, which is also changed into heat. This source of heat, how- 
ever, is very small. 
(d) Other processes are the formation of heat from the absorption of C02, by the concentration 
of water as it passes through membranes, in imbibition, and the formation of the solids, e. g., of 
chalk in the bones. After death, and in some pathological processes during life, the coagulation 
of blood and the production of rigor mortis are sources of heat. 
207. HOMOIOTHERMAL AND POIKILOTHERMAL ANI- 
MALS.—In place of the old classification of animals into “ cold-blooded ” 
and “warm-blooded,” another basis of classification seems desirable, viz., 
the relation of the temperature of the body to the temperature of the surround- 
ing medium. Bergmann introduced the word homoiothermal for the warm- 
blooded animals (mammals and birds), because these animals can maintain a 
very uniform temperature, even although the surrounding temperature be subject 
to considerable variations. The so-called cold-blooded animals are called 
poikilothermal, because the temperature of their bodies rises or falls, within 
wide limits, with the heat of the surrounding medium. 
When homoiothermal animals are kept for a long time in a cold medium, 
their heat-production is increased, and when they are kept for a long time in a 
warm medium it is diminished. 
Fordyce gave a proof of the nearly uniform temperature in man. A man remained ten 
minutes in an oven containing very dry hot air (§ 218), and yet the temperature of the palm 
of his hand, mouth, and urine was increased only a few tenths of a degree. Becquerel and 
Brechet investigated the temperature of the human biceps (by means of thermo-electric 
needles), when the arm has been one hour in iced water, and yet the temperature of the 
muscular tissue was cooled only 0.20 C. The same muscle did not undergo any increase in 
temperature, or at most 0.20 C., when the man’s arm was placed for a quarter of an hour in 
water at 420 C. 406 
HOMOIOTHERMAL AND POIKILOTHERMAL ANIMALS. [Sec. 207. 
If heat be rapidly abstracted (§ 225) or rapidly supplied (§ 221) to the body, 
so as to produce rapid variation of the temperature, life is endangered. 
Poikilothermal animals behave very differently; the temperature of their 
bodies generally follows, although with considerable variations, the temperature 
of the surroundings. When the temperature of the surroundings is increased, 
the amount of heat produced is increased, and when the surrounding tempera- 
ture falls, the amount of heat evolved within the body also falls. 
The following table shows very clearly the characters of poikilothermal animals, e.g., frogs 
which were placed in air and water of varying temperatures. They were immersed up to the 
mouth. The temperature was measured by means of a thermometer introduced through the 
mouth into the stomach. 
In Water. 
In Air. 
Temperature of the 
Water. 
Temperature of Frog’s 
Stomach. 
Temperature of the 
Air. 
Temperature of Frog's 
Stomach. 
4i.o° C. 
38.0° c. 
40.40 C. 
31.70 c. 
3°.° 
29.6 
27.4 
19.7 
20.6 
20.7 
16.4 
14.6 
5-9 
8.0 
6.2 
7.6 
2.8 
5-3 
5-9 
8.6 
[Temperature of Different Animals. 
Birds. 
Temp. 
Temp. 
Temp. 
Swallow, 
.... 44.03 
Panther, . . 
.... 38.90 
Thalassidroma, . . 
• 40.30 
Gull, . . . 
.... 37-8 
Mouse, . . 
.... 41.1 
Procellaria, . . . 
. 40.80 
Mammals. 
Dolphin, . . 
• • • • 35-5 
Goose, 
. 41-70 
Tiger, . . . 
.... 37.20 
f 37-30-40.00 
Sparrow, .... 
r 39.08 
Horse, . . . 
. 36.80-37.50 
Sheep, . . 
-j 39-50-40.00 
\ 42.10 
Rat, . . . 
.... 38.80 
[ 40.00-40.50 
Pigeon, . . . 41.80-42.50 
Hare, . . . 
.... 37.80 
Ape, . . . 
.... 35-5° 
Turkey, 
. 42.70 
Cat, .... 
• 38-30-38-90 
Guinea-pig, 
. 35.76-38.00 
Guinea-fowl, . . . 
- 43-9° 
Guinea-pig, 
.... 38.80 
Rabbit, 
• 37-5o-38.oo 
Duck, 
f 43-90 
Dog, . . . 
( 37-40 
Ox, . . . . 
.... 37.50 
142.50 
• • • S 39-oo 
Ass, . . . . 
.... 36.95 
Crow, 
• 41-17 
( 39-6o 
(Gavarret dr5 Rosenthal). ] 
Reptiles—Snakes, io°-I2°, but higher when incubating. Amphibians and fishes—o.5°-3° 
above the temperature of the surroundings. Arthropoda—o.i0~5.8° above the surroundings. 
Bees in a hive, 3o0-32°, and when swarming, 40°. The following animals have a temperature 
higher than the surrounding temperature:—Cephalopods, 0.570; molluscs, 0.46°; echinoderms, 
0.40°; medusae, 0.270; polyps, o.2i° C. 
208. ESTIMATION OF TEMPERATURE.—By using thermometric apparatus, we 
are enabled to obtain information regarding the degree of heat of the body to be investigated. 
For this purpose the following methods are employed :— 
A. The Thermometer.—Celsius (1701-1744) divided his thermometer into 100 parts, and 
each part was again divided into 10 parts, so that C. could be easily read off. All thermo- 
meters which have been used for a long time give too high readings, hence they should be com- 
pared, from time to time, with a normal thermometer. When taking the temperature, the bulb 
ought to be surrounded for fifteen minutes, and during the last five minutes the mercury column 
ought not to vary. A very sensitive thermometer will indicate the temperature after seven 
seconds if the urine stream be directed upon its bulb. Minimal and maximal thermometers 
are often of use to the physician. 
[Clinically, one of the thermometers shown in fig. 282 may be used. They are self-registering 
maximum thermometers, i. e., a portion of the mercury is separated from the mercurial column, 
to form the index, the top of which indicates the temperature. Before being used, the index 
must be well below the normal temperature. Various forms of surface thermometers have been 
used.] 
Walferdin’s metastatic thermometer (fig. 283) is specially useful for comparative observation. 
The tube is very narrow in comparison with the bulb, and in order that the stem be not too 
long, it is constructed so that the amount of mercury can be varied. A quantity of mercury is Sec. 208.J 
ESTIMATION OF TEMPERATURE. 
407 
taken, so that with the temperature expected the thread of mercury will stand about the middle 
of the stem. A small 
bulb at the upper part 
of the stem receives 
the excess of Hg. 
Suppose a tempera- 
Fig. 282. J 
A, Casella’s “ infallible,” B, “ Ferris’ perfect,” and C, Evans’ and Wormull’s 
“standard” clinical thermometers. 
ture between 37°-40° C. is to be measured, the bulb is first heated a little over 40° 
C., it is then suddenly cooled, and shaken at the same time, so that the thread of 
Fig. 283. 
Walferdin’s 
metastatic 
thermo- 
meter. 
Fig. 284. 
Scheme of thermo-electric arrangements for estimating the temperature. 408 
THERMO-ELECTRIC MEASUREMENTS. 
[Sec. 208. 
mercury is thereby suddenly broken above 40°. The tube is so narrow that i° C. is equal to 
about 10 centimetres of the length of the tube, so that C. is still 1 millimetre in length. 
The scale is divided empirically, but the value of the divisions must be compared with a normal 
thermometer. 
Kronecker and Meyer used very small maximal “ outflow thermometers,” and caused them 
to pass through the intestinal canal, or through large blood-vessels. The mercury flows out of 
the short open tube, and of course more flows out the higher the temperature. After these small 
bulbs have passed through the animal, a comparison is instituted with a normal thermometer, to 
determine at what temperature the mercury reaches the free margin of the tube. 
B. Thermo-electric Method.—This method enables us to determine the temperature accur- 
ately and rapidly (fig. 284, I). The thermo-electric galvanometer of Meissner and Meyer- 
stein consists of a circular magnet (m), suspended by a thread of silk (r), to which a small mir- 
ror (S) is attached. A large stationary bar magnet (M) is placed near the magnet (m), so that 
the north poles (n and N) of both magnets point in the same direction, and it is so arranged 
that the suspended magnet is caused to point to the north by a minimal action of M. A thick 
copper wire [b, b) is coiled several times round m (although in the fig. it is represented as a 
single coil), and the ends of the wire are soldered to two thermo-elements, each composed of 
two different metals—iron and German silver, the two similar free elements being united by a wire 
so that the two thermo-elements form part of a closed circuit. A horizontal scale (K, K) 
is placed at a distance of 3 metres from the mirror, so that the divisions of the scale are seen in 
the mirror. The scale itself rests upon a telescope (F) directed towards the mirror. The 
observer (B), who looks through the telescope, can see the divisions of the scale in the mirror. 
When the magnet, and with it the mirror, swing out of the magnetic meridian, the observer 
notices other divisions of the scale in the mirror. When one of the thermo-elements is heated, 
an electrical current is produced, which passes from the iron to the German silver in the heated 
couple, and causes a deviation of the suspended magnet. Suppose a person were swimming in 
the direction of the current in the conducting wire, then the north pole of the magnet moves to 
the north (Ampbre). The tangent of the angle <f>, through which the freely movable magnet is 
diverted by a galvanic current, from its position of rest or zero, in the magnetic meridian, is the 
Q 
same as the galvanic stream; G is proportional to the magnetic energy D, i.e., tang. <p * 
If G is to remain the same, and the tang. <j> to be as large as possible, the magnetic energy must 
be diminished as much as possible. If the magnetism of the suspended magnet be indicated by 
m, and that of the earth by T, the magnetic directing energy D — Tvi, so that D can be dis- 
tinguished in two ways: (1) by diminishing the magnetic moment of the suspended magnet, as 
may be done by using a pair of astatic needles, such as are used in Nobili’s galvanometer; (2) 
and also by weakening the magnetism of the earth, by placing an accessory stationary magnet 
(Hauy’s rod) in the same direction, and near the suspended magnet. An important arrange- 
ment for rapidly getting the magnet to zero is the dead-beat arrangement of Gauss (not figured 
in the scheme). It consists of a thick copper cylinder, on which the wire of the coil is wound. 
This mass of copper may be regarded as a closed multiplicator with a very large transverse sec- 
tion. The vibrating magnet induces in this closed circuit a current of electricity, whose inten- 
sity is greatest when the velocity of the excursion of the magnet is greatest, and which takes 
the opposite direction as soon as the magnet returns towards zero. These induced currents 
cause a diminution of the vibrations of the magnet in this way, that the arc of vibration of the 
magnet diminishes very rapidly, almost in a geometrical progression. The induced damping- 
current is stronger, the less the resistance in the closed circuit, and in the damper or dead-beat 
arrangement itself, the greater the section of the copper ring. This damping arrangement limits 
the oscillations of the magnet, and it comes to rest rapidly and promptly after 3 or 4 small 
vibrations, so that much time is saved. The angle of deviation is so small that the angle itself 
may be taken instead of the tangent. 
The thermo-electric needles of Dutrochet (fig. 284, II) may be placed in the circuit. They 
consist of iron and German silver soldered at their points; or the needles of Becquerel (HI) 
may be used. They consist of the same metals soldered in a straight line, one behind the other. 
The needles must always be covered by a varnish, which will prevent the parenchymatous juices 
from acting upon them, and so causing a current. Before the experiment we must determine 
what extent of excursion on the scale is obtained with a certain temperature. In order to 
determine this, a delicate thermometer is fixed to each of the thermo-couples, and both are 
placed in oil baths, which differ in temperature—say by 1° C.—as can be determined by the 
thermometer. When the current is closed, the excursion on the scale will indicate i° C. Sup- 
pose that the excursion was 150 mm., then each mm. of the scale would be equal to C. 
When this is determined, the two thermo-needles may be placed in the different tissues or 
organs of animals, and, of course, we obtain the difference of temperature in these places. Or 
one thermo-couple may be placed in a bath of constant temperature (nearly that of the body), 
in which is placed a delicate thermometer, while the other needle is introduced into the organ 
to be investigated. In this case we obtain the difference of temperature between the tissue and Sec. 408.] 
TEMPERATURE TOPOGRAPHY. 
the source of the constant heat. The electric current passes in the warmer needle from the iron 
to the German silver, and thus through the wires of the apparatus. For small differences of 
temperature, such as occur in the body, the thermo-electric energy is always proportional to the 
difference of temperature of the two needles or couples. In place of a single pair of needles 
several may be used, whereby the sensitiveness of the apparatus is greatly increased. Helmholtz 
found that by using sixteen antimony-bismuth couples, he could detect an increase of 0 C. 
Schiffer prepared a simple thermopile (IV) by soldering together alternately four pairs of wires 
of iron (f) and German silver (a). These are placed in the two organs (A and B) which are to be 
investigated, whereby a very high degree of exactness is obtained. 
209. TEMPERATURE TOPOGRAPHY.—Although the blood, in 
virtue of its continual motion (completing, as it does, the circulation in twenty- 
three seconds), must exercise a very considerable influence on the equilibration 
of the temperature in different organs, nevertheless, a completely uniform tem- 
perature does not exist, and the temperature varies in different parts : — 
1. Skin (/. Davy). 
Middle of the sole ofthe foot, 32.26° C. 
Near tendo-Achillis, . . . 33.85 
Anterior surface of leg, . . 33.05 
Middle of calf, 33-85 
Bend of knee, 35-°° 
Middle of upper arm, .... 35.40° C. 
Inguinal fold, 35.80 
Near cardiac impulse, .... 34.40 
Face, 31.00 
Nose and tip of ear, 22.24 
In the closed axilla, 36.49 (mean, of 505 individuals);—36.5 to 37.25 ( Wunderlich);—36.89° 
C. (Liebermeister). The skin over muscles is warmer than that over bone (Kunkel). 
The temperature of the skin of the head is higher in the forehead and parietal region than in 
the occipital region ; the skin on the left side of the head is warmer than on the right. Dyspnoea 
increases the temperature of the skin. 
Method.—Liebermeister determines the temperature of free cutaneous surfaces thus : The 
bulb of the thermometer is heated slightly above the temperature expected; after the mercury 
begins to fall, the bulb is placed on the skin, and if the bulb has the same temperature as the 
skin, the mercury remains stationary. This experiment must be repeated several times. 
2. Cavities. 
Mouth under the tongue, . . 37.19° C. 
Rectum, 38.01 
Vagina, 38.30° G. 
Urine, 37-03 
Uterine cavity somewhat warmer; cervical canal of the uterus somewhat cooler. 
The temperature falls in the stomach during digestion (§ 166, 1). Cold in- 
jections (ix° C.) into the rectum rapidly lower the temperature in the stomach 
i° C. ( Winternitz). 
3. The temperature of the blood is, as a mean, 390 C. The venous 
blood in internal viscera is warmer than the arterial, but it is cooler in pe- 
ripheral parts: — 
Blood of the right heart, 38.8° 
“ left heart, 38.6 
“ aorta, 38.7 
“ hepatic vein, 39.7 
Blood of the superior vena cava, . 36.78° 
“ inferior vena cava, . 38.x 1 
“ crural vein, .... 37.20 
( Cl. Bernard and v. Liebig.) 
The lower temperature of the blood in the left heart may be explained by the blood becom- 
ing cooled in its passage through the lungs during respiration. According to Heidenhain and 
Korner, the right heart is slightly warmer because it lies in relation with the warm liver, whilst 
the left heart is surrounded by the lung, which contains air. This observation is disputed by 
others, who say that the left heart is slightly warmer because the combustion-processes are more 
active in arterial blood, and heat is evolved during the formation of oxyhaemoglobin. The blood 
in the veins is usually cooler than in the corresponding arteries, owing to the superficial position 
of the former, whereby they give off heat during their long course ; thus the blood of the jugular 
vein is to 2° C. lower than the blood in the carotid; the crural vein to 1° cooler than in 
the crural artery. Superficial veins, more especially those of the skin, give off much heat, 
and their blood is, therefore, somewhat cooler. The warmest blood is that of the hepatic vein 
39.7° C., partly owing to the great chemical changes which occur within the liver, from its secre- 
tory activity (§ 210, a), and partly to its protected situation. 
4. The individual tissues are warmer: (1) the greater the transformation of 
kinetic energy into heat, i. e., the greater the tissue-metabolism; (2) the more CONDITIONS AFFECTING THE TEMPERATURE. 
[Sec. 
blood they contain ; (3) and the more protected their situation. According 
to Heidenhain and Korner, the cerebrum is the warmest organ of the body. 
Subcutaneous tissue (sheep), . 37.35° C. 
Brain, 40.25 
Liver, 4I-25 
Lungs, 41.40 
Rectum, 40.67° C. 
Right heart, 41.60 
Left heart, 40.90 
[Berger.) 
Becquerel and Brechet found the temperature of the human subcutaneous tissue to be 2.10 C. 
lower than that of the neighboring muscles. The horny tissues do not produce heat, and their 
low temperature is due to the conduction of heat from the parts on which they grow. The tem- 
perature of the cornea partly depends on that of the iris, and the more contracted the pupil is, 
the more heat it receives from the blood-vessels of the iris. 
210. CONDITIONS AFFECTING THE TEMPERATURE OF 
ORGANS.—The temperature of the individual organs is by no means con- 
stant ; it is influenced by many conditions ; amongst these are the following : — 
(1) The more heat produced independently within a part, the higher is its 
temperahire. As the amount of heat produced within a part depends upon its 
metabolism, therefore when the metabolism is increased, the amount of heat 
produced is similarly increased. 
(a) Glands produce more heat during the act of secretion, as is proved by 
the higher temperature of their secretion, or by the higher temperature of the 
venous blood flowing out of their veins. 
Ludwig found that when he stimulated the chorda tympani, the saliva of the submaxillary 
gland was 1.50 C. warmer than the blood in the carotid, which supplied the gland with blood 
(p. 255). The blood in the renal vein in a kidney which is secreting is warmer than the blood 
in the renal artery. The secreting liver produces much heat (§ 178). Cl. Bernard investigated 
the temperature of the blood of the portal and hepatic veins during hunger, at the beginning 
of digestion, and when digestion was most active, and he found :— 
Temperature of portal vein, . . 37.8° C. 
“ hepatic vein, . . 38.4 
After 4 days' 
starvation. 
Blood of right heart. 
38.8° 
(Hunger period.) 
Beginning of 
digestion. 
Temperature of portal vein, . . 39.9 
“ hepatic vein, . . 39.5 
Temperature of portal vein, . . 39.7 
“ hepatic vein, . . 41.3 
Digestion most 
active. 
Blood of right heart, 
during digestion, 39.2°. 
In the dog a moderate diet, chemical or mechanical stimulation of the gastric mucous mem- 
brane, or even the sight of food, raises the temperature in the stomach and intestine. 
(h) When the muscles contract, they evolve heat. Davy found that an 
active muscle became 0.70 C. warmer; while Becquerel, by means of a thermo- 
galvanometer, found that human muscles, when kept contracted for five min- 
utes, became i° C. warmer (§ 302). 
This is one of the reasons why the temperature may rise above 40° during rapid running. A 
temperature obtained by energetic muscular action usually does not fall to the normal until after 
resting for \)4 hour. The low temperature of paralyzed limbs depends partly upon the absence 
of the muscular contractions. 
(c) With regard to the effect of sensory nerves upon the temperature, 
some of the chief points to ascertain are—whether the circulation is accelerated 
or retarded by their stimulation, or whether the respiration is increased or di- 
minished (§ 214, II, 3), and whether the muscles of the skeleton are relaxed or 
contracted reflexly (§ 214, I, 3). In the former case the temperature of the 
interior of the body and rectum is increased ; in the latter diminished. 
(d) The temperature of the body rises during mental exertion. Davy 
observed an increase of 0.30 C. after vigorous mental exertion. 
(e) The parenchymatous fluids, serous fluids, and lymph produce little heat, 
owing to their feeble metabolism, hence they have the same temperature as their Sec. 210.] 
ESTIMATION OF HEAT AND CALORIMETRY. 
411 
surroundings ; the epidermal and horny tissues do not produce heat, they merely 
conduct it from subjacent structures. 
(2) The temperature depends, to a large extent, upon the amount of blood 
in an organ, and also upon the rapidity with which the blood is renewed by the 
circulation. This is best observed in the difference of the temperature between 
a cold, pale, bloodless hand, and a warm, red congested one. 
Becquerel and Brechet found that the temperature of the human biceps fell several tenths of a 
degree when the axillary artery was compressed. Ligature of the crural artery and vein in a dbg 
causes a fall of several degrees. If the extremities be kept suspended in the air, they become 
bloodless and cold. 
Liebermeister has pointed out a difference with regard to the external and internal parts of the 
body. The external parts give off more heat than they produce, so that they become cooler the 
more slowly new blood flows into them, and warmer the greater the rapidity of the blood-stream 
through them. Acceleration of the blood-stream, therefore, causes the temperature of peripheral 
parts to approximate more and more to the temperature of internal organs, while retardation of 
the blood-stream causes them to approach the temperature of the surrounding medium. Exactly 
the reverse is the case with internal parts, where a large amount of heat is produced, and heat 
is given up almost alone to the blood which flows through them. Their temperature must fall 
when the blood-stream through them is accelerated, and it is raised when the blood-stream is 
retarded. Hence it follows that the greater the difference of the temperature between peripheral 
and internal parts, the slower must be the velocity of the circulation. 
(3) If the position or other condition of an organ be such as to cause it to 
give off heat by conduction or radiation, then its temperature falls. 
A good example of this is the skin, which varies greatly in temperature according to the 
temperature of the surrounding medium, whether it is covered or uncovered, whether it is dry 
or moist with sweat (which abstracts heat when it evaporates). When much cold food or drink 
is taken, the stomach is cooled, and when ice-cold air is breathed, the respiratory passages 
as far as the bronchi are cooled. 
211. ESTIMATION OF HEAT.—Calorimetry is the method of 
determining the amount of heat possessed by any body, or what amount of heat 
it is capable of producing. The unit of measurement is the “ heat-unit,” 
or “ calorie,” i. e., the amount of heat (or potential energy) required to raise 
the temperature of 1 gram of water i° C. (see Introduction'). This is some- 
times called the small caloric. 
Experiment has shown that equal quantities of different substances require very unequal 
amounts of heat to raise them to the same temperature, e. g., 1 kilo, water requires nine times as 
much heat as 1 kilo, iron to raise it to the same temperature. In the human body, therefore, 
which is composed of very different substances, unequal amounts of heat will be required to 
raise them all to the same temperature. The same amount of heat transferred to two different 
substances will raise them to different temperatures. Hence, bodies of different temperatures 
may contain equal amounts of heat. The amount of heat required to raise a definite quantity 
(e. g., 1 grm.) of a substance to a certain higher degree [e. g., i° C.) is called “ specific heat.” 
The specific heat of water (which of all bodies has the highest specific heat) is taken as = 1. 
By “ heat-capacity” is meant that property of bodies in virtue of which they must absorb a 
given amount of heat in order to have a certain temperature. 
Calorimetry is employed :—1. To determine the specific heat of the different 
organs of the body.—Only a few observations have been made. The mean 
specific heat of the following animal parts (water = 1) is :— 
Human blood = 1.02 (?) 
Arterial blood = 1.031 (?) 
Venous blood = 0.892 (?) 
Cow’s milk = 0.992 
Human muscle = 0.741 
Ox muscle = 0.787 
Compact bone == 0.3 
Spongy bone = 0.71 
Fat tissue == 0.712 
Striped muscle = 0.825 
Defibrinated blood = 0.927 
(J. Rosenthal.') 
The specific heat of the human body, as a whole, is about that of an equal 
volume of water. 
Kopp’s Method.—The solid to be investigated is broken in pieces about the size of a pea, and 
placed in a test-tube A, with thin walls, which is closed above with a cork, from which a copper 412 
CALORIMETRY 
[Sec. 211. 
wire with a hook on it projects (fig. 285). The test-tube contains a certain quantity of fluid 
which does not dissolve the substance, 
but which lies between its pieces and 
covers it. It is weighed three times 
to ascertain the weight (1) of the empty 
glass, (2) after it is filled with the solid 
substance, (3) after the fluid is added, so 
that we obtain the weight of the solid 
substance, m, and that of the fluid, f. 
The test-tube and its contents are placed 
in a mercury bath, BB, and this again in 
an oil bath, CC, and the whole is raised 
to a high temperature. Into BB there is 
introduced a fine thermometer, T. When 
the tube, A, has reached the necessary 
temperature (say 40°) it is rapidly placed 
in the water of the accompanying calori- 
meter-box, DD. The water in this box, 
which also contains a thermometer, D, 
is kept in motion until it has completely 
absorbed all the heat given off by A. 
Let T represent the temperature to which 
A and its contents were raised in the 
mercury bath, and T the temperature to 
which it fell in the calorimeter; let s be the specific heat, and m the weight of the solid 
substance in the test-tube, while a and fi represent the specific heat and the weight of the 
interstitial fluid in the test-tube; and lastly, let w equal the amount of water in contact with A, 
which absorbs and gives off heat; then W represents the amount of heat which the test-tube 
and its contents give off during cooling. 
Fig. 285. 
Kopp’s apparatus for estimating specific heat. 
W = (j. m q. w + a p) (T—Tr) 
The amount of heat, W1; absorbed by the calorimeter is 
Wj = M - t), 
where M represents the amount of water in the calorimeter, t the original temperature of the 
water in the calorimeter, and t1 the temperature to which it is raised by placing A in it. If 
W and Wj are equal, then 
the specific heat, s = ~0 ~ g -^)(T ~ Ti), 
W(T - Tj) 
If a fluid substance is placed in the test tube, and its weight = m, and its specific heat = s, 
the formula for the specific heat of the fluid to be investigated is 
f M(/t — t) — w (T— Tx) 
m (T —1\) 
II. Calorimetry is more important for determining the amount of heat 
produced in a given time by the body as a whole, or by its individual parts. 
Lavoisier and Laplace made the first calorimetric observations on animals in 1783, by means 
of an ice-calorimeter; a guinea-pig melted 13 oz. of ice in ten hours. Crawford, and afterwards 
Dulong and Despretz, used Rumford’s water-calorimeter, which is similar to Favre and 
Silbermann’s. Small animals are placed in the inner thin-walled copper chamber (K), which 
is placed in a water-bath surrounded on all sides by some non-conducting material. We 
require to know the amount of water, and its original temperature. The number of calories 
is obtained from the increase of the temperature at the end of the experiment, which lasts 
several hours. The air is supplied to the animal through a special apparatus, resembling a 
gasometer. The amount of C02 in the gases evolved is estimated. 
According to Despretz, a bitch formed 16,410 heat-units per hour—i. e., 
393,000 in twenty-four hours. Other things being equal, a man seven times 
heavier than this would produce in twenty-four hours about 2,750,000 calories. 
Senator found that a dog weighing 6330 grms. produced 15,370 calories per 
hour, and excreted at the same time 367 grms. C02. The first calorimetric 
experiments on man were made by Scharling (1849). Liebermeister estimated Sec. 211.] 
VARIATIONS OF THE MEAN TEMPERATURE. 
413 
the amount of heat given off by a man placed in a cold bath, which was sur- 
rounded with a woollen covering. Leyden placed a lower limb in the calori- 
meter, whereby 6000 grms. water were raised i° C. in an hour. If we assume 
that the total superficial area of the body is fifteen times greater than that of 
the leg, the human body would produce 2,376,000 calories in twenty-four 
hours. 
212. THERMAL CONDUCTIVITY OF TISSUES.—The thermal conductivity of 
animal tissues is of special interest in connection with the skin and subcutaneous fatty tissue. 
The fatty layer under the skin, more especially in the whale, walrus, and seal, forms a protective 
covering, whereby the conduction of heat from internal organs is rendered almost impossible. 
Investigations upon this subject, however, are few. Griess attempted to estimate the thermal 
conductivity by heating one part of the tissue, and determining when and in what direction 
.pieces of wax placed on the tissue to be investigated began to melt. He investigated the 
stomach of the sheep, the bladder, skin, hoof, horn, and bones of an ox, deer’s horn, ivory, 
mother-of-pearl, shell of haliotis. He found that fibrous tissues conducted heat more r.eadily 
in the direction of their fibres than at right angles to the course of the fibres. Hence, the 
figures obtained from the melted wax were usually elliptical. Landois has made similar 
observations, and he finds that tissues conduct better in the direction of their fibres. After 
bones, blood-clot was the best conductor, then followed spleen, liver, cartilage, tendon, muscle, 
elastic tissue, nail and hair, bloodless skin, gastric mucous membrane, washed fibrin. It is 
specially interesting to note how much better skin containing blood in its blood-vessels 
conducts than does bloodless skin. Hence little heat is given off from a bloodless skin, while 
congested skin conducts and gives off much more heat. 
Like all other substances, the human body is enlarged by heat. A man weighing 60 kilos., 
and whose temperature is raised from 370 C. to 40° C., is enlarged about 62 cubic centimetres. 
Connective-tissue (tendon) is extended by heat, while elastic tissue and the skin, like caoutchouc 
are contracted. 
213. VARIATIONS OF THE MEAN TEMPERATURE.—(1) 
General Climatic and Somatic Influences.—In the tropics the mean 
temperature of the body is about C. higher than in temperate climates, 
where again it is several tenths of a degree warmer than in cold climates ; 
but this has recently been denied. The difference is comparatively trivial, 
when we remember that a man is subjected to a variation of over 40° C. in 
passing from the equator to the poles. Observations on more than 4000 per- 
sons show that when a person goes from a warm to a cold climate, his tempera- 
ture is but slightly diminished, but when he goes from a cold to a warm climate 
his temperature rises relatively considerably more. In the temperate zone, the 
temperature of the body during a cold winter is usually o. i° to 0.30 C. lower 
than it is on a warm summer day. The height of a place above sea-level 
has no obvious effect on the temperature of the body. There seems to be no 
difference in different races, nor in the sexes, other conditions being the 
same. Persons of powerful physique and constitution are said to have gen- 
erally a slightly higher temperature than feeble, weak, anaemic persons. 
(2) Influence of the General Metabolism.—As the formation of heat 
depends upon the transformation of chemical compounds, whose chief final 
products, in addition to H20, are C02 and urea, the amount of heat formed 
must go pari passu with the amount of these excreta. The more rapid meta- 
bolism which sets in after a full meal causes a rise of temperature to several 
tenths of a degree (“ Digestion-fever ”). As the metabolism is much dimin- 
ished during hunger, this explains why the mean temperature in a fasting man 
is 36.6°, while it is 37.170 on ordinary days (§ 237). 
Jtirgensen also found that the temperature fell on the first day of inanition (although there 
was a temporary rise on the second day). In experiments made upon starving animals, the 
temperature at first fell rapidly, then remained constant for a considerable time, while during 
the last days it fell considerably. Schmidt starved a cat—on the 15th day the temperature was 
38.6°; on the 16th, 38.3°; 17th, 37 64°; i8th,35.8°; 19th (death) — 33.00. Chossat found 
that starving mammals and birds had a temperature 160 C. below normal on the day of their 
death. [Sec. 213. 
DAILY VARIATIONS OF TEMPERATURE. 
(3) Age has a decided effect upon the temperature of the body. The ex- 
tent of the general metabolism is in part an index of the heat of the body at 
different ages, but it is possible that other, as yet unknown, influences are also 
active. 
Age. 
Mean Temperature at the 
Ordinary Temperature. 
Normal Limits. 
Where Measured. 
Newly-born, 
37-45° c- 
37-35-37-55°C. 
Rectum. 
5 9 year, 
37-72 
36.87-37.62 
Mouth and Rectum. 
15-20 “ 
37-37 
36.12-38.1 
Axilla. 
21-30 “ 
37.22 
(< 
25-30 “ 
36.91 
(( 
31-40 “ 
37-i 
36.25-37.5 
a 
41-50 “ 
36.87 
t< 
51-60 “ 
36.83 
u 
80 “ 
37-46 
Mouth. 
Newly-born animals exhibit peculiarities owing to the sudden change in 
their conditions of existence. Immediately after birth, the infant is 0.30 
warmer than the vagina of the mother, viz., 37.86°. A short time after birth 
the temperature falls 0.9°, while twelve to twenty-four hours afterwards it has 
risen to the normal temperature of an infant, which is 37.45°. Several irregu- 
lar variations occur during the first weeks of life. During sleep the temperature 
of an infant falls 0.34° to 0.56°, while continued crying may raise it several 
tenths of a degree. Old people, on account of their feeble metabolism, pro- 
duce little heat; they become cold sooner, and hence ought to wear warm 
clothing to keep up their temperature. 
Variations of the daily temperature in health during twenty-four hours. L , after 
Liebermeister; J , after Jiirgensen. 
Fig. 286. 
(4) Periodical Daily Variations.—In the course of twenty-four hours 
there are regular periodic variations in the mean temperature, and these occur 
at all ages. As a general rule, the temperature continues to rise during the day 
(maximum at 5 to 8 p. m.), while it continues to fall during the flight (minimum 
2 to 6 a. m.). The mean temperature occurs at the third hour after breakfast 
(fig. 286). 
The mean height of all the temperatures taken during a day in a patient is 
called the “daily mean,” and according to Jaeger it is 37.310 in the rectum Sec. 213.] 
CAUSES OF DAILY TEMPERATURE VARIATIONS. 
415 
in health. A daily mean of more than 37.8° is a “fever temperature,” while 
a mean under 37.o° C. is regarded as a “collapse temperature.” 
Time. 
Barensprung. 
J. Davy. 
Hallmann. 
Gierse. 
Jiirgensen. 
Jager. 
Morning, 5 
367 
36.6 
36.9 
6 
36.68 
36.7 
36.4 
37-1 
7 
36.94* 
36.63 
36.98 
36.7* 
36.5* 
37-5* 
8 
37.16* 
36.80* 
37.08* 
36.8 
36.7 
37-4 
9 
36.89 
36.9 
36.8 
37-5 
10 
37.26 
= 37-36 
37-23 
37-o 
37-o 
37-5 
11 
36.89 
37-2 
37-2 
37-3 
Mid-day, 12 
36.87 
37-3* 
37-3* 
37-5* 
1 
36.83 
37-21 
37-13 
37-3 
37-3 
37-4 
2 
37-05 
37-5o* 
37-4 
37-4 
37-5 
3 
37-15* 
37-43 
37-4* 
37-3* 
37-5 
4 
37-17 
37-4 
37-3 
37-5* 
5 
3748 
37-05* 
52 = 37-31 
37-43 
37-5 
37-5 
37-5 
6 
6j = 36.83 
37-29 
37-5 
37-6 
37-4 1 
7 
37-43 
= 36.50* 
37-31 * 
37-5* 
37.6* 
37-3 ; 
8 
37-4 
37-7 
37-i* 
9 
37.02* 
37-4 
37-5 
36.9 
10 
37-29 
37-3 
37-4 
36.8 
11 
36.85 
36.72 
36.70 
36.81 
37-2 
37-i 
36.8 
Night, 12 
. . 
37-i 
36.9 
36.9 
1 
36.65 
36-44 
37-o 
36.9 
36.9 
2 
36.9 
36.7 
36.8 
3 
. . 
36.8 
367 
36 7 
4 
36.31 
• • 
36.7 
36.7 
36.7 
As the variations occur when a person is starved for a day—although those that occur at the 
periods at which food ought to have been taken are less—it is obvious that the variations are not 
due entirely to the taking of food. [The * indicates taking of food.] 
The daily variation in the frequency of the pulse often coincides with variation of the 
temperature. Barensprung found that the mid-day temperature maximum slightly preceded the 
pulse maximum ($ 70, 3, C). 
If one sleeps during the day, and does all one’s daily duties during the night, 
the above described typical course of the temperature is reversed. With regard 
to the effect of activity or rest, it appears that the activity of the muscles during 
the day tends to increase the mean temperature slightly, while at night the 
mean temperature is less than in the case of a person at rest. 
The peripheral parts of the body exhibit more or less regular variations of their temperature. 
In the palm of the hand, the progress of events is the following: after a relatively high night 
temperature there is a rapid fall at 6 a.m., which reaches its minimum at 9 to 10 a.m. This is 
followed by a slow rise, which reaches a high maximum after dinner; it falls between 1 to 3 
r.M., and after two or three hours reaches a minimum. It rises from 6 to 8 P.M., and falls again 
towards morning. A rapid fall of the temperature in a peripheral part corresponds to a rise of 
temperature in internal parts. 
(5) Many operations upon the body affect the temperature. After hemor- 
rhage the temperature falls at first, but it rises again several tenths of a degree, 
and is usually accompanied by a shiver or slight rigor; several days thereafter 
it falls to normal, and may even fall somewhat below it. The sudden loss of a 
large amount of blood causes a fall of the temperature of y2 to 20 C. Very 
long-continued hemorrhage (dog) causes it to fall to 310 or 290 C. 
This is obviously due to the diminution of the processes of oxidation in the anaemic body, 
and to the enfeebled circulation. Similar conditions causing diminished metabolism effect the 
same result. Continued stimulation of the peripheral end of the vagus, so that the heart’s 
action is enormously slowed, diminishes the temperature several degrees in rabbits (Landois and 
Ammon). [Sec. 213. 
416 
REGULATION OF TEMPERATURE. 
The transfusion of a considerable quantity of blood raises the temperature 
about half an hour after the operation. This gradually passes into a febrile 
attack, which disappears within several hours. When blood is transfused from 
an artery to a vein of the same animal, a similar result occurs (§ 102). 
(6) Many poisons diminish the temperature, e. g., chloroform and the 
anaesthetics, alcohol (§ 235), digitalis, quinine, aconitin, muscarin. These 
appear to act partly by rendering the tissues less liable to undergo molecular 
transformations for the production of heat. In the case of the anaesthetics, 
this effect perhaps occurs, and is due possibly to a semi-coagulation of the 
nervous substance (?). They may also act partly by influencing the giving 
off of heat (§ 214, II.). Other poisons increase the temperature for opposite 
reasons. 
The temperature is increased by strychnin, nicotin, picrotoxin, veratrin, laudanin. 
(7) Various diseases diminish the temperature, which may be due either to lessened pro- 
duction of heat (diminution of the metabolism), or to increased expenditure of heat. Loewen- 
hardt found that in paralytics and in insane persons, several weeks before their death, the rectal 
temperature was 30° to 310 C., in diabetes 30° C. or less; the lowest temperature observed and 
life retained in a drunk person was 240 C. 
The temperature is increased in fever, and the highest point reached just before death, and 
recorded by Wunderlich, was 44.65° C. (compare \ 220). 
214. REGULATION OF THE TEMPERATURE.—As the bodily 
temperature of man and similar animals is nearly constant, notwithstanding 
great variations in the temperature of their surroundings, it is clear that some 
mechanism must exist in the body, whereby the heat economy is constantly 
regulated. This maybe brought about in two ways ; either by controlling 
the transformation of potential energy into heat, or by affecting the amount of 
heat given off according to the amount produced, or to the action of external 
agencies. 
[The constancy or thermostatic condition of the temperature is brought about 
by three co-operant factors, the thermogenic or heat-producing, the thermo- 
lytic or heat-discharging, and the thermotaxic or mechanism by which heat- 
production and heat-loss are balanced, and it is obvious that the last must be 
in relation with the other two. The thermotaxic mechanism is developed last, 
is least pronounced in the lower vertebrata, and is most easily liable to fail 
under injury or disease (Mac A lister).] 
I. Regulatory Arrangements governing the Production of Heat.— 
Liebermeister estimated the amount of heat produced by a healthy man at 1.8 
calories, i. e., the kilo unit, per minute. It is highly probable that, within the 
body, there exist mechanisms which determine the molecular transformations, 
upon which the evolution of heat depends. This is accomplished chiefly in a 
reflex manner. The peripheral ends of cutaneous nerves (by thermal stimu- 
lation), or the nerves of the intestine and the digestive glands (by mechanical 
or chemical stimulation during digestion or inanition), may be irritated, 
whereby impressions are conveyed to the heat-centre, which sends out 
impulses through efferent fibres to the depots of potential energy, either to 
increase or diminish the extent of the transformations occurring in them. The 
nerve-channels herein concerned are entirely unknown. Many considerations, 
however, go to support such an hypothesis (§ 377). 
[Thermotaxic Mechanism, Thermal Nerves and Centres.—Just as the respiration and 
the state of the blood-vessels are regulated from a central focus, so the question arises, Does the 
same obtain with regard to temperatures? Studying this question, however, it must be borne in 
mind that thermometric observations alone are not sufficient; the true test must be calorimetric. 
Sir Benjamin Brodie observed that in a case of injury of the spinal cord in the neck the tem- 
perature in the thigh rose very high. In some cases the temperature falls. Wood has shown 
that section of the cord above the origin of the splanchnics leads to decided increase in the Sec. 214.] 
REGULATION OF TEMPERATURE. 
417 
amount of heat dissipated, but to a decided diminution of heat-production. The vaso-motor 
paralysis has much to do in these cases with the loss of heat. In warm-blooded animals, exposed 
to a high temperature, the heat-production is diminished, but when they are exposed to a low 
temperature it is increased. If a warm-blooded animal’s medulla oblongata be divided, there is 
a fall of temperature, chiefly due to vaso-motor paralysis, and such an animal behaves, as regards 
the effect of heat and cold, exactly like a poikilothermal animal, i. e., its metabolism and heat- 
production are increased by cold and diminished by heat. If, however, the incision be made 
above the pons, so as to leave the vaso-motor centre intact in the dog, there is a rise of the 
temperature and increased heat-production for 24 hours afterwards. This suggests the idea 
that this region is traversed by inhibitory nerves, so that when they are cut off from their centres 
situate above, the augmentor nerves can act more vigorously. This suggests the existence of 
thermo-inhibitory centres situate higher up in the brain. If an animal be curarized, not only is 
there paralysis of voluntary motor acts, but on stimulating an ordinary motor nerve, not only 
is there no muscular contraction, but there is no rise of temperature of the muscles supplied by 
that nerve. In such an animal the temperature rises and falls with the temperature of the 
surrounding medium. Even although the respirations be kept constant and the vaso-motor 
nerves intact, the thermogenic activity of muscles, therefore, seems to be dependent on their 
innervation.] 
[Cerebral Centres.—Apart from the cortical heat centres ($ 377), Ott, Aronsohn, Sachs, 
Richet, and others have shown that if a needle be thrust through the skull and brain, so as to 
injure certain deeper-seated parts, there is a rise of temperature and increased heat-production 
for several hours. The experiment may be repeated several times in the same rabbit. Ott gives 
three areas which, when so injured, cause these effects—(1) a part of the brain in the median 
side of the corpus striatum, and near the nodus cursorius; (2) a part between the corpus striatum 
and the optic thalamus; and (3) the anterior end of the optic thalamus itself. From the effect of 
atropin, Ott suggests the existence of spinal centres as well.] 
Regulatory Mechanisms.—The following phenomena indicate the exist- 
ence of mechanisms regulating the production of heat:— 
(1) The temporary application of moderate cold raises the bodily 
temperature, while heat, similarly applied to the external surface, lowers it 
(§§ 222 and 224). 
(2) Cooling of the surroundings increases the amount of C02 excreted, 
by increasing the production of heat, while the O consumed is also increased 
simultaneously; heating the surrounding medium diminishes the C02 (§ 126, 5). 
D. Tinkler found, from experiments upon guinea-pigs, that the production of heat was more 
than doubled when the surrounding temperature was diminished 240 C. The metabolism of the 
guinea-pig is increased in winter 23 per cent as compared with summer, so that the same rela- 
tion obtains as in the case of the diminution of the surrounding temperature of short duration. 
C. Ludwig and Sanders-Ezn found that in a rabbit there was a rapid increase in the amount of 
C02 given off, when the surroundings were cooled from 38° to 6° or 70 C.; while the excretion 
was diminished when the surrounding temperature was raised from 4°-9° to 35°-37°, so that the 
thermal stimulation, due to the temperature of the surrounding medium, acted upon the com- 
bustion within the body. Pfliiger found that a rabbit which was dipped in cold water used more 
0 and excreted more C02. 
If the cooling action was so great as to reduce the bodily temperature to 30°, the exchange of 
gases diminished, and where the temperature fell to 20°, the exchange of gases was diminished 
one-half. It is to be remembered, however, that the excretion of C02 does not go hand in 
hand with the formation of C02. If mammals be placed in a warm bath, which is 2° to 30 
higher than their own temperature, the excretion of C02 and the consumption of O are increased 
owing to the stimulation of their metabolism, while the excretion of urea is also increased in 
animals and in man ($ 126, 5). 
(3) Cold acting upon the skin causes involuntary muscular move- 
ments (shivering, rigors), and also voluntary movements, both of which 
produce heat. 
The cold excites the action of the muscles, which is connected with processes of oxidation 
{Pfliiger). After poisoning with curare, which paralyzes voluntary motion, this regulation of 
the heat falls to a minimum (Rbhrig andZuntz), [so that the bodily temperature rises and falls 
with a rise or fall in the temperature of the surrounding medium], 
(4) Variations in the temperature of the surroundings affect the 
appetite for food ; in winter, and in cold regions, the sensation of hunger 418 
REGULATION OF TEMPERATURE. 
[Sec. 214. 
and the appetite for the fats, or such substances as yield much heat when they 
are oxidized, are increased ; in summer, and in hot climates, they are di- 
minished. Thus the mean temperature of the surroundings, to a certain extent, 
determines the amount of the heat-producing substances to be taken in the food. 
II. Regulatory Mechanisms governing the Excretion of Heat or 
Thermolysis.—The mean amount of heat given off by the human skin in 
twenty-four hours, by a man weighing 82 kilos, is 2092 to 2952 calories, i. e., 
1.36 to 1.60 per minute. 
[Radiation from the Skin.—The real radiiting surface in man under ordinary conditions 
is the surface of the clothes, and only to a comparatively small extent the skin. In warm- 
blooded animals it is not the naked epidermis but the surface of the hair or feathers. The 
amount of radiation from this surface depends (1) on the difference between its temperature 
and that of the surroundings, and (2) on its co-efficient of emission. G. N. Stewart has compared 
the influence of these two factors for the human skin by measuring simultaneously the temper- 
ature of the skin and the amount of heat radiated from it. Both measurements were made by 
the electrical method with lead paper gratings. The co-efficient of emission was not found to 
vary much under the conditions of the experiments, the chief factor in determining the amount 
of radiation being the temperature difference. Masje, however, has stated that when a large 
part of the body is stripped in a cold atmosphere the radiation from the skin is increased, 
although its temperature is lowered. The effect of replacing the normal radiating surface by 
one of higher temperature is well seen when the hair is extensively removed from a rabbit or a 
guinea-pig, and the animal is prevented from covering itself. Even in warm summer weather 
the animal may die in as short a time as twenty hours (G. N. Stewart).~\ 
(1) Heat causes dilatation of the cutaneous vessels ; the skin 
becomes red, congested, and soft; it contains more fluids, and becomes a 
better conductor of heat; the epithelium is moistened, and sweat appears 
upon the surface. Thus increased excretion of heat is provided for, while the 
evaporation of the sweat also abstracts heat. 
The amount of heat necessary to convert into vapor 1. grm. of water at ioo° C. is equal to 
that required to heat 10 grms. from o° to 53.67° C. The sweat as secreted is at the temperature 
of the body; if it were completely changed into vapor, it would require the heat necessary to 
raise it to the boiling point, and also that necessary to convert it into vapor. 
Cold causes contraction of the cutaneous vessels ; the skin becomes 
pale, less soft, poorer in juices, and collapsed ; the epithelium becomes dry, 
and does not permit fluids to pass through it to be evaporated, so that the 
excretion of heat is diminished. The excretion of heat from the periphery, and 
the transverse thermal conduction through the skin, are diminished by the con- 
traction of the vessels and muscles of the skin, and by the expulsion of the well- 
conducting blood from the cutaneous and subcutaneous vessels. The cooling 
of the body is very much affected, owing to the diminution of the cutaneous 
blood-stream, just as occurs when the current through a coil or worm of a distil- 
lation apparatus is greatly diminished. If the blood-vessels dilate, the tempera- 
ture of the surface of the body rises, the difference of temperature between it 
and the surrounding cooler medium is increased, and thus the excretion of 
heat is increased. Tomsa has shown that the fibres of the skin are so arranged 
anatomically, that the tension of the fibres produced by the erector pili muscles 
causes a diminution in the thickness of the skin, this result being brought about 
at the expense of the easily expelled blood. 
By the systematic application of stimuli, e.g., cold baths, and washing with cold water, the 
muscles of the skin and its blood-vessels may be caused to contract, and become so vigorous and 
excitable that when cold is suddenly applied to the body, or to a part of it, the excretion of heat is 
energetically prevented, so that cold baths and washing with cold water are, to a certain extent, 
“ gymnastics of the cutaneous muscles,” which, under the above circumstances, protect the body 
from cold. 
(2) Increased temperature causes increased heart-beats, while 
diminished temperature diminishes the number of contractions of the Sec. 214.] 
REGULATION OF TEMPERATURE. 
419 
heart (§ 58, II, a). The relatively warm blood is pumped by the action of the 
heart from the internal organs of the body to the surface of the skin, where it 
readily gives off heat. The more frequently the same volume of blood passes 
through the skin—twenty-seven heart-beats being necessary for the complete 
circuit of the blood—the greater will be the amount of heat given off, and 
conversely. Hence, the frequency of the heart-beat is in direct relation to the 
rapidity of cooling. In very hot air (over ioo° C.) the pulse rises to over 160 
per minute. The same is true in fever (§ 70, 3, c). Liebermeister gives the 
following numbers in an adult: — 
Pulse-beats, per min., 78.6 91.2 99.8 108.5 110 137-5 
Temperature in C., 370 38° 390 40° 410 420 
(3) Increased Temperature increases the Number of Respirations. 
—Under ordinary circumstances, a much larger volume of air passes through 
the lungs when it is warmed almost to the temperature of the body. Further, 
a certain amount of watery vapor is given off with each expiration, which must 
be evaporated, thus abstracting heat. Energetic respiration aids the circulation, 
so that respiration acts indirectly in the same way as (2). According to other 
observers, the increased consumption of O favors the combustion in the body, 
whereby the increased respiration must act in producing an amount of heat 
greater than normal (§ 126, 8). This excess is more than compensated for by 
the cooling factors above mentioned. Forced respiration produces cooling, 
even when the air breathed is heated to 540 C., and saturated with watery 
vapor. 
(4) Covering of the body.— Animals become clothed in winter with a 
winter fur or covering, while in summer their covering is lighter, so that the 
excretion of heat in surroundings of different temperatures is thereby rendered 
more constant. 
Many animals which live in very cold air or water (whale) are protected from 
too rapid excretion of heat by a thick layer of fat under the skin. Man pro- 
vides for a similar result by adopting summer and winter clothing. 
(5) The position of the body is also important; pulling the parts of the 
body together, approximation of the head and limbs, keep in the heat; spread- 
ing out the limbs, erection of the hairs, pluming the feathers, allow more heat 
to be evolved. If a rabbit be kept exposed to the air with its legs extended for 
three hours, the rectal temperature will fall from 390 C. to 370 C. Man may influ- 
ence his temperature by remaining in a warm or a cold room—by taking hot or 
cold drinks, hot or cold baths—remaining in air at rest or air in motion, e.g., 
hy using a fan. 
CLOTHING.—Warm Clothing is the Equivalent of Food.— As clothes are intended 
to keep in the heat of the body, and heat is produced by the combustion and oxidation of the 
food, we may say the body takes in heat directly in the food, while clothing prevents it from 
giving off too much heat. Summer clothes weigh 3 to 4 kilos., and winter ones 6 to 7 kilos. 
In connection with clothes, the following considerations are of importance :— 
(1) Their capacity for conduction.—Those substances which conduct heat badly keep us 
warmest. Hare-skin, down, beaver-skin, raw silk, taffeta, sheep’s wool, cotton wool, flax, spun- 
silk, are given in order, from the worst to the best conductors. (2) The capacity for radiation. 
—Coarse materials radiate more heat than smooth, but color has no effect. (3) Relation to the 
sun's rays.—Dark materials absorb more heat than light-colored ones. (4) Their hygroscopic 
properties are important, whether they can absorb much moisture from the skin and gradually 
give it off by evaporation, or the reverse. The same weight of wool takes up twice as much 
as linen; hence the latter gives it off in evaporation more rapidly. Flannel next the skin is not 
so easily moistened, nor does it so rapidly become cold by evaporation; hence it protects against 
the action of cold. (5) The permeability for air is of importance, but does not stand in relation 
with the heat-conducting capacity. The following substances are arranged in order from the 
most to the least permeable—flannel, buckskin, linen, silk, leather, wax-cloth. 420 
HEAT-BALANCE. 
[Sec. 215. 
215. HEAT-BALANCE .—As the temperature of the body is maintained 
within narrow limits, the amount of heat taken in must balance the heat given 
off, i. e., exactly the same amount of potential energy must be transformed in 
a given time into heat, as heat is given off from the body. An adult produces 
as much heat in half an hour as will raise the temperature of his body i° C. 
If no heat were given off, the body would become very hot in a short time; 
it would reach the boiling point in thirty-six hours, supposing the production 
of heat continued uninterruptedly. The following are the most important 
calculations on the subject:— 
A. Helmholtz was the first to estimate numerically the amount of heat produced by a 
man :— 
(1) Heat-income.—(a) A healthy adult, weighing 82 kilos., expires in 
twenty-four hours 878.4 grams. C02 (Scharling). The combus- 
tion of the C therein into C02 produces 1,730,760 cal. 
(b) But he takes in more O than reappears in the C02; the excess is used 
in oxidation-processes, e.g., for the formation of H20, by union with 
H, so that 13.615 grms. H will be oxidized by the excess of O,which 
gives 318,600 “ 
2,049,360 cal. 
(c) About 25,per cent, of the heat must be referred to sources other than 
combustion (Dulong), so that the total = 2,732,000 “ 
2,732,000 calories are actually sufficient to raise the temperature of an adult, weighing 80 
to 90 kilos., from io° to 38° or 390 C., i. e., to a normal temperature. 
(2) Heat-expenditure.—(a) Heating the food and drink, which 
have a mean temperature of 120 C 70,157 cal.= 2.6 per cent. 
(h) Heating the air respired = 16,400 grms. with an initial tem- 
perature of 200 C 70,032 “ = 2.6 “ 
( When the temperature of the air is o°, 140,064 cal. — 5.2 per cent.) 
(c) Evaporation of 656 grms. water by the lungs, 397,536 “ = 14.7 “ 
(d) The remainder given off by radiation and evaporation of 
water by the skin, (77-5 Per cent, to) = 80.1 
B. Dulong.—(1) Heat-income.—Dulong and others sought to estimate the amount of heat 
from the C and H contained in the food. As we know that the combustion of 1 grm. 0 = 8040 
heat-units, and I grm. H = 34.460 heat-units, it would be easy to determine the amount of heat 
were the C simply converted into C02 and the H into H20. But Dulong omitted the H in the 
carbohydrates (e. g., grape-sugar = C6H1206) as producing heat, because the H is already com- 
bined with O, or at least is present in the proportion in which it exists in water. This assumption 
is hypothetical, for the atoms of C in a carbohydrate may be so firmly united to the other atoms, 
that before oxidation can take place their relations must be altered, so that potential energy is 
used up, i. e., heat must be rendered latent; so that these considerations rendered the following 
example of Dulong’s method given by Vierordt very problematical:— 
An adult eats in twenty-four hours 120 grms. proteids, 90 grms. fat, and 340 grms. starch 
(carbohydrates). These contain:— 
Proteids, 120 grms. contain 64.18 C. and 8.60 H. 
Fat 90 “ “ 70 20 “ 10.26 
Starch 340 “ “ 146.82 
281.20 and 18.86 
The urine and faeces contain, still unconsumed, .... 29.8 “ 6.3 
Remainder to be burned 251.4 and 12.56 
As 1 grm. C — 8040 heat-units and 1 grm. H = 34,460 heat-units, we have the following 
calculation:— 
251.4 X 8,040 = 2,031,312 (from combustion of C). 
12.56 X 34,460= 432,818 ( “ “ H). 
2,464,130 heat-units. Sec. 215.] 
RELATION OF HEAT TO WORK. 
421 
(2) Heat-expenditure :— 
Heat-units. 
Per cent, of 
the excreta. 
I. 
1900 grins, are excreted daily by the urine and faeces, and they are 
250 warmer than the food, 47,500 
i-9 
2. 
13,000 grms. air heated (from 120 to 370 C.) (heat-capacity of 
3-38 
the air = 0.26), 84,500 
3- 
330 grms. water are evaporated by the respiration (1 grm. = 582 
heat-units), 192,060 
7.68 
4- 
660 grms. water are evaporated from the skin, 384,120 
iS-37 
Total, . 708,180 
Remainder radiated and conducted from the skin, . . . ... 1,791,820 
71.67 
Total amount of heat-units given off, 2,500,000 
100.00 
C. Heat-income.—Frankland burned the food directly in a calorimeter, and found that 1 
grm. of the following substances yielded :— 
Albumin, i grm., ....... 
Grape-sugar, i grm 
Ox fat, I grm., 
The albumin, however, is only oxidized to the stage of urea, hence the heat-units of urea 
must be deducted from 4998, which gives 4263 heat units obtainable from 1 grm. albumin. 
When we know the number of grams consumed, a simple multiplication gives the nun ber of 
heat-units. 
The heat-units will vary, of course, with the nature of the food. J. Ranke gives the fol- 
lowing : — 
With animal diet, ........ 
“ food free from N, 
2,059,506 
“ mixed diet, 
2,200,000 “ 
“ during hunger, 
216. VARIATIONS IN HEAT-PRODUCTION—(1) Influence of Bodily Surface. 
—Rubner found that the production of heat depended more upon the size of the body and its super- 
ficial area than upon the body-weight. Small or young animals have a relatively larger surface 
than large or older ones, and as the removal of heat takes place chiefly from the external sur- 
face, animals with a larger surface must produce more heat. Small animals use relatively more 
O. Rubner’s investigations on dogs of different size gave a heat-production of 1,143,000 
calories for every square metre of cutaneous surface. On comparing the body-weight with the 
cutaneous surface in different animals, he found that for every 1 kilo, of body-weight there was 
in the rat 1650, rabbit 946, man 287 square centimetres of surface. 
(2) Age and Sex.—The heat-production is less in infancy and in old age, and it is less in 
proportion in the female than in the male. 
(3) Daily Variation.—The heat-production shows variations in twenty-four hours corre- 
sponding with the temperature of the body ($ 213, 4). 
(4) The heat-production is greater in the waking condition, during physical and mental 
exertion, and during digestion, than in the opposite conditions. 
217. RELATION OF HEAT-PRODUCTION TO WORK.— 
The potential energy supplied to the body may be transformed into heat and 
various other forms of kinetic energy (see Introduction). In the resting con- 
dition, almost all the potential energy is changed into heat; the workman, 
however, transforms potential energy into work—mechanical work—in addi- 
tion to heat. These two may be compared by using an equivalent measure- 
ment, thus, 1 heat-unit (energy required to raise 1 gram of water i° C.) = 
425.5 grammetres. 
Relation of Heat to Work.—The following example may serve to illustrate the relation 
between heat-production and the production of work: Suppose a small steam-engine to be 
placed within a capacious calorimeter, and a certain quantity of coal to be burned, then as long 
as the engine does not perform any mechanical work, heat alone is produced by the burning of 
the coal. Let this amount of heat be estimated, and a second experiment made by burning the 
same amount of coal, but allow the engine to do a certain amount of work—say, raise a weight 
—by a suitable arrangement. This work must, of course, be accomplished by the potential [Sec. 217. 
422 
ACCOMMODATION FOR VARYING TEMPERATURES. 
energy of the heating material. At the end of this experiment, the temperature of the water 
will be much less than in the first experiment, i. e., fewer heat-units have been transferred to the 
calorimeter when the engine was heated than when it did no work. Comparative experiments 
of this nature have shown that in the second experiment the useful work is very nearly pro- 
portional to the decrease of the heat (Him). 
Compare this with what happens within the body; A man in a passive 
condition forms from the potential energy of the food between to 
million calories. The work done by a workman is reckoned at 30,000 kilo- 
grammetres (§ 300). 
If the organism were precisely similar to a machine, a smaller amount of heat, 
corresponding to the work done, would be formed in the body. As a matter 
of fact, the organism produces less heat from the same amount of potential 
energy when mechanical work is done. There is one point of difference be- 
tween a workman and a working machine. The workman consumes much 
more potential energy in the same time than a passive person ; much more is 
transformed in his body ; and hence the increased consumption is not only cov- 
ered, but even over-compensated. Hence, the workman is warmer than the 
passive person, owing to the increased muscular activity (§ 210, 1, b). Take 
an example : Hirn remained passive, and absorbed 30 grms. O per hour in a 
calorimeter, and produced 155 calories. When in the calorimeter he did work 
equal to 27,450 kilogrammetres, which was transferred beyond it; he absorbed 
132 grms. O, and produced only 251 calories. 
In estimating the work done, we must include only the heat-equivalent of the work transferred 
beyond the body; lifting weights, pushing anything, throwing a weight, and lifting the body, 
are examples. In ordinary walking we must take into account that we overcome the resistance 
of the air and activity of the muscles. 
The organism is superior to a machine in as far as it can, from the same 
amount of potential energy, produce more work in proportion to heat. Whilst 
the very best steam-engine gives of the potential energy in the form of 
work, and 1/% as heat, the body produces as work and as heat. Chemical 
energy can never do work alone, in a living or dead motor, without heat being 
formed at the same time. 
218. ACCOMMODATION FOR VARYINGTEMPERATURES. 
—All substances which possess high conductivity for heat, when brought into 
contact with the skin, appear to be very much colder or hotter than bad con- 
ductors of heat. The reason of this is that these bodies abstract far more heat, 
or conduct more heat than other bodies. Thus the water of a cool bath, being 
a better conductor of heat, is always thought to be colder than air at the same 
temperature. In our climate it appears to us that— 
Air, at 18° C. is moderately warm; 
“ at 25°-28° C., hot; 
“ above 28°, very hot. 
Water, at i8° C. is cold; 
“ from i8°-29° C., cool; 
“ “ 29°-35° C., warm ; 
“ “ 37-5° and above, hot. 
Warm Media.—As long as the temperature of the body is higher than that 
of the surrounding medium, heat is given off, and that the more rapidly the 
better the conducting power of the surrounding medium. As soon as the tem- 
perature of the surrounding medium rises higher than the temperature of the 
body, the latter absorbs heat, and it does so the more rapidly the better the 
conducting power of the medium. Hence hot water appears to be warmer than 
air at the same temperature. A person may remain eight minutes in a bath at 
45.50 C. (dangerous to life !); the hands may be plunged into water at 50.50 
C, but not at 51.65°, while at 6o° violent pain is produced. 
A person may remain for eight minutes in hot air at 127° C., and a tempera- 
ture of 1320 C. has been borne for ten minutes, and yet the body temperature Sec. 218.] 
FEVER. 
423 
rises only to 38.6° or 38.9°. This depends upon the air being a bad conductor, 
and thus it gives less heat to the body than water would do. Further, and 
what is more important, the skin becomes covered with sweat, which evapo- 
rates and abstracts heat, while the lungs also give off more watery vapor. The 
enormously increased heart-beats—over 160—and the dilated blood-vessels, 
enable the skin to obtain an ample supply of blood for the formation and evapo- 
ration of sweat. In proportion as the secretion of sweat diminishes, the body 
becomes unable to endure a hot atmosphere; hence it is that in air containing 
much watery vapor a person cannot endure nearly so high a temperature as in 
dry air, so that the heat must accumulate in the body. In a Turkish vapor- 
bath of 530 to 6o° C., the rectal temperature rises to 40.70 or 41.6° C. A 
person may work continuously in air at 310 C. which is almost saturated with 
moisture. 
If a person be placed in water at the temperature of the body, the normal 
temperature rises i° C. in one hour, and in ifo, hour about 20 C. A gradual 
increase of the temperature from 38.6° to 40.20 C. causes the axillary tempera- 
ture to rise to 39.o° within fifteen minutes. 
219. STORAGE OF HEAT.—As the uniform temperature of the body, 
under normal circumstances, is due to the reciprocal relation between the 
amount of heat produced and the amount given off, it is clear that heat must 
be stored up in the body when the evolution of heat is diminished. The skin 
is the chief organ regulating the evolution of heat; when it and its 
blood-vessels contract, the heat evolved is diminished ; when they dilate, it is 
increased. Heat may be stored up when— 
(a) The skin is extensively stimulated, whereby the cutaneous vessels are temporarily con- 
tracted. (b) Any other circumstances preventing heat from being given off by the skin. (<r) 
When the vaso-motor centre is excited, causing all the blood vessels of the body—those of the 
skin included—to contract. This seems to be the cause of the rise of temperature after trans- 
fusion of blood, and the rise of temperature after the sudden removal of water from the body 
seems to admit of a similar explanation, as the inspissated blood occupies less space, and the 
contracted vessels of the skin admit less blood. (d) When the circulation in the cutaneous 
vessels of a large area is mechanically slowed, or when the smaller vessels are plugged by the 
injection of some sticky substance, or by the transfusion of foreign blood, the temperature rises 
(I I02)- 
It is also obvious that when a normal amount of heat is given off, an increased 
production of heat must raise the temperature. The rise of the temperature 
after muscular or mental exertion, and during digestion, seems to be caused in 
this way. The rise which occurs several hours after a cold bath is probably due 
to the reflex excitement of the skin causing an increased production (_Jiirgensen). 
When the temperature of the body, as a whole, is raised 6° C., death takes 
place, as in sunstroke. It seems as if there was a molecular decomposition of 
the tissues at this temperature; while, if a slightly lower temperature be kept 
up continuously, fatty degeneration of many tissues occurs (Litten). If animals, 
which have been exposed artificially to a temperature of over 420 to 440 C., be 
transferred to a cooler atmosphere, their temperature becomes sub-normal 
(36° C.), and may remain so for several days. 
220. FEVER.—Fever consists in a “ disorder of the body heat,” and at the same time there 
is greatly increased tissue metabolism (especially in the muscles). Of course the mechanism 
regulating the balance of formation and expenditure of heat is disturbed. During fever the 
body is greatly incapacitated for performing mechanical work. It is evident, therefore, that 
the large amount of potential energy transformed is almost all converted into heat, so that the 
non transformation of the energy into mechanical work is another important factor. We may 
take intermittent fever or ague as a type of fever, in which violent attacks of fever of several 
hours’ duration alternate with periods free from fever. This enables us to analyze the symp- 
toms. The symptoms of fever are: — 
(1) The increased bodily temperature (38° to 390 C., slight; from 390 to 410 C. and 424 
FEVER. 
[Sec. 220. 
upwards, severe).—The high temperature occurs not only in cases where the skin is red, and has 
a hot burning feeling (calor mordax), but even during the rigor or the shivering stage, the tem- 
perature is raised. The congested red skin is a good conductor of heat, while the pale bloodless 
skin conducts badly; hence, the former feels hot to the touch (§ 212). 
[The following table in 0 C. and 0 F. indicates generally the degree of fever :— 
35° C. = 95° F Collapse. 
36 = 96.8 .... Low. 
36.5 = 97.7 .... Sub-normal. 
37 = 98.6 .... Normal. 
390 C. = 102.20 F. 
39.5 == 103.1 
Moderate Fever. 
40 = 104 
40.5 = 104.9 
41 — 105.8 Hyperpyretic. 
Finlays on. ] 
High fever. 
37.5 = 99.4' 
38 = 100.4 
38.5 =101.3. 
Sub-febrile. 
(2) The increased production of heat is proved by calorimetric observations. This is, in 
small part, due to the increased activity of the circulation being changed into heat ($ 206, 2, a), 
but for the most part it is due to increased combustion within the body. 
(3) The increased metabolism gives rise to the “ consuming ” or “ wasting ” character of 
fever, which was known to Hippocrates and Galen. In 1852 v. Barensprung asserted that “ all 
the so-called febrile symptoms show that the metabolism is increased.” The increase of the 
metabolism is shown in the increased excretion of C02 = 70 to 80 per cent., while more O is 
consumed, although the respiratory quotient remains the same. According to D. Finkler, the 
CC)2 excreted shows greater variations than the O consumed. The excretion of urea is increased 
Y to Yz- 1° dogs suffering from septic fever, Naunyn observed that the urea began to increase 
before the temperature rose, “prefebrile rise." Part of the urea, however, is sometimes retained 
during the fever, and appears after the fever is over, “ epicritical excretion of urea." The uric 
acid is also increased; the urine pigment ($ 19), derived from the haemoglobin, may be increased 
twenty times, while the excretion of potash may be seven-fold. It is important to observe that 
the oxidation or combustion processes within the body of the fever-patient are greatly increased 
when he is placed in a warmer atmosphere. The oxidation processes in fever, however, are 
also increased under the influence of cooler surroundings (§ 213, I, 2), but the increase of the 
oxidation in a warm medium is very much greater than in the cold ( D. Finkler). The amount 
of COa in the blood is diminished, but not at once after the onset even of a very severe fever 
(Geppert). 
(4) The diminished excretion of heat varies in different stages of a fever. We distinguish 
several stages in a fever—(a) The cold stage, when the loss of heat is greatly diminished 
owing to the pale bloodless skin, but at the same time the heat-production is increased 1 y2 to 2 yz 
times. The sudden and considerable rise of the temperature during this stage shows that the 
diminished excretion of heat is not the only cause of the rise of the temperature, (b) During 
the hot stage the heat given off from the congested red skin is greatly increased, but at the 
same time more heat is produced. Liebermeister assumes that a rise of 1,2, 3, 40 C. corresponds 
to an increased production of heat of 6, 12, 18, 24 per cent, (r-) In the sweating stage the 
excretion of heat through the red moist skin and evaporation are greatest, more than two or 
three times the normal. The heat-production is either increased, normal, or sub-normal, so that 
under these conditions the temperature may also be sub-normal (36° C.). 
(5) The heat-regulating mechanism is injured.—A warm temperature of the surround- 
ings raises the temperature of the fever-patient more than it does that of a non-febrile person. 
The depression of the heat-production, which enables normal animals to maintain their normal 
temperature in a warm medium (§ 214), is much less in fever (Z>. Finkler). 
The accessory phenomena of fever are very important: Increase in the intensity and 
number of the heart-beats (§ 214, II., 2) and respirations (in adults 40, and children 60 per 
min.) both being compensatory phenomena of the increased temperature; further, diminished 
digestive activity and intestinal movements ($ 186, D); disturbances of the cerebral activities; 
of secretion; of muscular activity; slower excretion, e.g., of potassium iodide through the 
urine. In severe fever, molecular degenerations of the tissues are very common. For the con- 
dition of the blood-corpuscles in fever, see $ 10, the vascular tension § 69, the saliva, § 146, 
digestion, \ 186. 
Quinine, the most important febrifuge, causes a decrease of the temperature by limiting the 
production of heat ($ 213, 6). Toxic doses of the metallic salts act in the same way, while there 
is at the same time diminished formation of C02 [Antipyretics or Febrifuges.—All methods 
which diminish abnormal temperature belong to this group. As the constant temperature of the 
body depends on (1) the amount of heat-production, and (2) the loss of heat, we may lower 
the temperature either in the one way or the other. When cold water is applied to the body, it 
abstracts heat, i. e., it affects the results of fever, so that Liebermeister calls such methods 
antithermic. But those remedies which diminish the actual heat-production are true anti- 
pyretics. In practice, however, both methods are usually employed, and spoken of collectively 
as antipyretic.] Sec. 220.] 
EMPLOYMENT OF HEAT. 
425 
[Amongst the methods which are used to abstract heat from the body are the application of 
colder fluids, such as the cold bath, diffusion, douche, spray, ice, or cold mixtures, etc. A person 
suffering from high fever requires to be repeatedly placed in a cold bath to produce any per- 
manent reduction of the temperature. Some remedies act by favoring the radiation of heat, by 
dilating the cutaneous vessels (alcohol), while others excite the sweat-glands—i. e., are sudorifics 
—so that the water by its evaporation removes some heat. Amongst the drugs which influence 
tissue changes and oxidation, and thereby lessen heat-production, are quinine, salicylic acid, 
some of the salicylates, digitalis, and veratrin. Blood-letting was formerly used to diminish 
abnormal temperature. Amongst the newer antipyretic remedies are hydrochlorate of kairin 
and antipyrin, both of which belong to the aromatic group (derivatives of benzol), which in- 
cludes also many of our best antiseptics.] 
221. ARTIFICIAL INCREASE OF THE BODILY TEM- 
PERATURE.—If mammals are kept constantly in air at 40° C., the ex- 
cretion of heat from the body ceases, so that the heat produced is stored up. 
At first the temperature falls somewhat for a very short time, but soon a decided 
increase occurs. The respirations and pulse are increased, while the latter 
becomes irregular and weaker. The O absorbed and C02 given off are dimin- 
ished after six to eight hours, and death occurs after great fatigue, feebleness, 
spasms, secretion of saliva, and loss of consciousness, when the bodily tem- 
perature has been increased 40 or at most 6° C. Death does not take place 
owing to rigidity of the muscles, for the coagulation of the myosin of mammals’ 
muscles occurs at 490 to 50° C., in birds at 530 C., and in frogs at 40° C. If 
mammals are suddenly placed in air at ioo° C., death occurs (in 15 to 20 min.) 
very rapidly, and with the same phenomena, while the bodily temperature rises 
4° to 50 C. In rabbits the body-weight diminishes 1 grm. per min. Birds 
bear a high temperature somewhat longer ; they die when their blood reaches 
48° to 50° C. 
Even man may remain for some time in air at 100-110-132° C., but in ten 
to fifteen minutes there is danger to life. The skin is burning to the touch, and 
red ; a copious secretion of sweat bursts forth, and the cutaneous veins are fuller 
and redder. The pulse and respirations are greatly accelerated. Violent head- 
ache, vertigo, feebleness, and stupefaction, indicate great danger to life. The 
rectal temperature is only i° to 20 C. higher. The high temperature of fever 
may even be dangerous to human life. If the temperature remains for any 
length of time at 42.50 C., death is almost certain to occur. Coagulation of 
the blood in the arteries is said to occur at 42.6° C. If the artificial heating 
does not produce death, fatty infiltration and degeneration of the liver, heart, 
kidneys, and muscles begin after thirty-six to forty-eight hours. 
Cold-blooded animals, if placed in hot air or warm water, soon have their temperature 
raised 6 to io° C. The highest temperature compatible with life in a frog must be below 40° C., 
as the frog’s heart and muscles begin to coagulate at this temperature. Death is preceded by a 
stage resembling death, during which life may be saved. 
Most of the juicy plants die in half an hour in air at 520 C., or in hot water at 46° C. (Sachs). 
Dried seeds of corn may still germinate after long exposure to air at 120° C. Lowly organized 
plants, such as algae, may live in water at 6o° C. (Hoppe-Seyler). Several bacteria withstand a 
boiling temperature (Tyndall). 
222. EMPLOYMENT OF HEAT.—Action of Heat.—The short, but not intense, 
action of heat on the surface causes, in the first place, a transient slight decrease of the bodily 
temperature, partly because it retards reflexly the production of heat, and partly because, owing 
to the dilatation of the cutaneous vessels and the stretching of the skin, more heat is given off. 
A warm bath above the temperature of the blood at once increases the bodily temperature. 
Therapeutic Uses.—The application of heat to the entire body is used where the bodily 
temperature has fallen, or is likely to fall, very low, as in the algid stage of cholera, and in 
infants born prematurely. Thz. general application of heat is obtained by use of warm baths, 
packing, vapor baths, and the copious use of hot drinks. The local application of heat is 
obtained by the use of warm wrappings, partial baths, plunging the parts in warm earth or sand, 
or placing wounded parts in chambers filled with heated air. After removal of the heating 426 
ACTION OF COLD ON THE BODY 
[Sec. 222. 
agent, care must be taken to prevent a great escape of heat due to the dilatation of the 
blood-vessels. 
223. INCREASE OF TEMPERATURE POST-MORTEM.—Phenomena.—Hei- 
denhain found that in a dead dog, before the body cooled, there was a constant temporary rise of 
the temperature, which slightly exceeded the normal. The same observation had been occa- 
sionally made on human bodies immediately after death, especially when death was preceded by 
muscular spasms [also in yellow fever]. Thus Wunderlich measured the temperature fifty-seven 
minutes after death in a case of tetanus, and found it to be 45.3750 C. 
Causes.—(1) A temporary increased production of heat after death, due chiefly to the change 
of the semi-solid myosin of the muscles into a solid form (rigor mortis). As the muscle coagu- 
lates, heat is produced. All conditions which cause rapid and intense coagulation of the 
muscles—e.g., spasms—favor a post-mortem rise of temperature (see \ 295); a rapid coagulation 
of the blood has a similar result (§ 28, 5). 
(2) Immediately after death a series of chemical processes occur within the body, whereby heat 
is produced. Valentin placed a dead rabbit in a chamber, so that no heat could be given off 
from the body, and he found that the internal temperature of the animal’s body was increased. 
The processes which cause a rise of temperature post-mortem are more active during the first 
than the second hour; and the higher the temperature at the moment of death, the greater is 
the amount of heat evolved after death. 
(3) Another cause is the diminished excretion of heat post-mortem. After the circulation is 
abolished, within a few minutes little heat is given off from the surface of the body, as rapid 
excretion implies that the cutaneous vessels must be continually filled with warm blood. 
224. ACTION OF COLD ON THE BODY.—Phenomena.—A 
short temporary slight cooling of the skin (removing one’s clothes in a cool 
room, a cool bath for a short time, or a cool douche) causes either no change 
or a slight rise in the bodily temperature. The slight rise when it occurs is 
due to the stimulation of the skin, causing reflexly a more rapid molecular 
transformation, and therefore a greater production of heat, while the amount 
of heat given off is diminished owing to contraction of the small cutaneous ves- 
sels and the skin itself (.Liebermeister). The continuous and intense applica- 
tion of cold causes a decrease of the temperature, chiefly by conduction, notwith- 
standing that at the same time there is a greater production of heat. After a 
cold bath the temperature may be 340, 320, and even 30°. 
As an after-effect of the great abstraction of heat, the temperature of the 
body after a time remains lower than it was before (“primary after-effect”— 
Liebermeister) ; thus after an hour it was 0.220 C. less in the rectum. There is 
a 11 secondary after-effect ” which occurs after the first after-effect is over, when 
the temperature rises (Jiirgensen). This effect begins five to eight hours after 
a cold bath, and is equal to + o. 20 C. in the rectum. Hoppe-Seyler found that 
some time after the application of heat there was a corresponding lowering of 
the temperature. 
Taking Cold.—If a rabbit be taken from a surrounding temperature of 350 C., and suddenly 
cooled, it shivers, and there may be diarrhoea. After two days the temperature rises 1.50 C., 
and albuminuria occurs. There are microscopic traces of interstitial inflammation in the 
kidneys, liver, lungs, heart, and nerve-sheaths, the dilated arteries of the liver and lung con- 
tain thrombi, and in the neighborhood of the veins are accumulations of leucocytes. In preg- 
nant animals, the foetus shows the same conditions. Perhaps the greatly cooled blood acts as 
an irritant causing inflammation. 
Action of Frost.—The continued application of a high degree of cold causes at first contrac- 
tion of the blood-vessels of the skin and its muscles, so that it becomes pale. If continued, 
paralysis of the cutaneous vessels occurs, the skin becomes red owing to congestion of its 
vessels. As the passage of fluids through the capillaries is rendered more difficult by the cold, 
the blood stagnates, and the skin assumes a livid appearance, as the O is almost completely 
used up. Thus the peripheral circulation is slowed. If the action of the cold be still more 
intense, the peripheral circulation stops completely, especially in the thinnest and most exposed 
organs—ears, nose, toes, and fingers. The sensory nerves are paralyzed, so that there is numb- 
ness with loss of sensibility, and the parts may even be frozen through and through. As the 
slowing of the circulation in the superficial vessels gradually affects other areas of the circula- 
tion, the pulmonary circulation is enfeebled, and diminished oxidation of the blood occurs, Sec. 224.] 
ARTIFICIAL LOWERING OF THE TEMPERATURE. 
427 
notwithstanding the greater amount of O in the cold air, so that the nerve centres are affected. 
Hence arise great dislike to making movements or any muscular effort, a painful sensation of 
fatigue, a peculiar and almost irresistible desire to sleep, cerebral inactivity, blunting of the 
sense-organs, and lastly, coma. The blood freezes at —3.90 C., while the juices of the super- 
ficial parts freeze sooner. Too rapid movements of the frost-bitten parts ought to be avoided. 
Rubbing with snow, and the very gradual application of heat, produce the best results. Partial 
death of a part is not unfrequently produced by the prolonged action of cold. 
225. ARTIFICIAL LOWERINGOFTHETEMPERATURE.— 
Phenomena.—Theartificial cooling of warm-blooded animals, by placing 
them in cold air or in a freezing mixture, gives rise to a series of characteristic 
phenomena. If the animals (rabbits) are cooled so that the temperature 
(rectum) falls to 180, they suffer great depression, without, however, the volun- 
tary or reflex movements being abolished. The pulse falls from 100 or 150 to 
20 beats per minute, and the blood-pressure falls to several millimetres of Hg. 
The respirations are few and shallow. Suffocation does not cause spasms, the 
secretion of urine stops, and the liver is congested. The animal may remain 
for twelve hours in this condition, and when the muscles and nerves show signs 
of paralysis, coagulation of the blood occurs after numerous blood-corpuscles 
have been destroyed. The retina becomes pale, and death occurs with spasms 
and the signs of asphyxia. If the bodily temperature be reduced to 170 and 
under, the voluntary movements cease before the reflex acts. An animal cooled 
to 18° C., and left to itself, at the same temperature as the surroundings, does 
not recover of itself, but if artificial respiration be employed, the temperature 
rises io° C. If this be combined with the application of external warmth, the 
animals may recover completely, even when they have been apparently dead 
for forty minutes. Walther cooled adult animals to g° C., and recovered them 
by artificial respiration and external warmth ; while Horvath cooled young 
animals to 50 C. Mammals, which are born blind, and birds which come out 
of the egg devoid of feathers, cool more rapidly than others. Morphia, and 
more so, alcohol, accelerate the cooling of mammals, at the same time the 
exchange of gases falls considerably ; hence, drunk men are more liable to die 
when exposed to cold. 
Artificial Cold-blooded Condition.—Cl. Bernard made the important 
observation that the muscles of animals that had been cooled remained irri- 
table for a long time to direct stimuli as well as to stimuli applied to their nerves ; 
and the same is the case when the animals are asphyxiated for want of O. An 
“ artificial cold-blooded condition,''1 i. e., a condition in which warm-blooded 
animals have a lower temperature, and retain muscular and nervous excitability, 
may also be caused in warm-blooded animals, by dividing the cervical spinal 
cord and keeping up artificial respiration ; further, by moistening the peri- 
toneum with a cool solution of common salt. 
Hibernation presents a series of similar phenomena. Valentin found that hibernating 
animals become half awake when their bodily temperature is 28° C.; at 180 C. they are in a 
somnolent condition, at 6° they are in a gentle sleep, and at i.6° C. in a deep sleep. The heart- 
beats and the blood pressure fall, the former to 8 to 10 per minute. The respiratory, urinary, 
and intestinal movements cease completely, and the cardio-pneumatic movement alone sustains 
the slight exchange of gases in the lungs ($ 59). They cannot endure cooling to o° C., and 
awake before the temperature falls so low. Hibernating animals may be cooled to a greater 
degree than other mammals ; they give off heat rapidly, and they become warm again rapidly, 
and even spontaneously. New-born mammals resemble hibernating animals more closely in 
this respect than do adults. 
Cold-blooded animals maybe cooled to o°. Even when the blood has been frozen and ice 
formed in the lymph of the peritoneal cavity, frogs may recover. In this condition they appear 
to be dead, but when placed in a warm medium they soon recover. A frog’s muscle so cooled 
will contract again. The germs and ova of lower animals, e.g., insects’ eggs, survive continued 
frost; and if the cold be moderate, it merely retards development. Bacteria, e.g., Bacillus 
anthracis, survive a temperature of — 130° C.; yeast, even — ioo° C. [Sec. 225. 
428 
EMPLOYMENT OF COLD. 
Varnishing the skin causes a series of similar phenomena. The varnished skin gives off a 
large amount of heat by radiation, and sometimes the cutaneous vessels are greatly dilated. 
Hence the animals cool rapidly and die, although the consumption of O is not diminished. If 
cooling be prevented by warming them and keeping them in warm wool, the animals live for a 
longer time. The blood post-mortem does not contain any poisonous substances, nor even are 
any materials retained in the blood which can cause death, for if the blood be injected into other 
animals, these remain healthy. 
226. EMPLOYMENT OF COLD.—Cold may be applied to the whole or part of the 
surface of the body in the following conditions :— 
(«) By placing the body for a time in a cold bath to abstract as much heat as possible, when 
the bodily temperature in fever rises so high as to be dangerous to life. This result is best 
accomplished and lasts longest when the bath is gradually cooled from a moderate temperature. 
If the body be placed at once in cold water, the cutaneous vessels contract, the skin becomes 
bloodless, and thus obstacles are placed in the way of the excretion of heat. A bath gradually 
cooled in this way is borne longer. The addition of stimulating substances, e. g., salts, which 
cause dilation of the cutaneous vessels, facilitates the excretion of heat; even salt water 
conducts heat better. If alcohol be given internally at the same time it lowers the 
temperature. 
Cold may be applied locally by means of ice in a bag, which causes contraction of the 
cutaneous vessels and contraction of the tissues (as in inflammation), while at the same time 
heat is abstracted locally. 
(c) Heat may be abstracted locally by the rapid evaporation of volatile substances (ether, 
carbon disulphide), which causes numbness of the sensory nerves. The introduction of media 
of low temperature into the body, respiring cool air, taking cold drinks, and the injection of 
cold fluids into the intestine act locally, and also produce a more general action. In applying 
cold it is important to notice that the initial contraction of the vessels and the contraction of 
the tissues are followed by a greater dilatation and turgescence, i. e., by a healthy reaction. 
227. HEAT OF INFLAMED PARTS.—“ Calor,” or heat, is reckoned one of the 
fundamental phenomena of inflammation, in addition to rubor (redness), tumor (swelling), 
and dolor (pain). But the apparent increase in the heat of the inflamed parts is not above the 
temperature of the blood. Simon, in i860, asserted that the arterial blood flowing to an in- 
flamed part was cooler than the part itself, but this has been contradicted. The outer parts of 
the skin in an inflamed part are warmer than usual, owing to the dilatation of the vessels (rubor) 
and the consequent acceleration of the blood-stream in the inflamed part, and, owing to the 
swelling (tumor), from the presence of good heat-conducting fluids; but the heat is not greater 
than the heat of the blood. It is not proved that an increased amount of heat is produced 
owing to increased molecular decompositions within an inflamed part. 
228. HISTORICAL AND COMPARATIVE.—According to Aristotle, the heart pre- 
pares the heat within itself, and sends it along with the blood to all parts of the body. This 
doctrine prevailed in the time of Hippocrates and Galen, and occurs even in Cartesius and 
Bartholinus (1667, “ flammula cordis”). The iatro-mechanical school (Boerhave, van 
Swieten) ascribed the heat to the friction of the blood on the walls of the vessels. The iatro- 
chemical school, on the other hand, sought the source of heat in the fermentations that arose 
from the passage of the absorbed substances into the blood (van Helmont, Sylvius, Ettmuller). 
Lavoisier (1777) was the first to ascribe the heat to the combustion of carbon in the lungs. 
After the construction of the thermometer by Galileo, Sanctorius (1626) made the first ther- 
mometric observations on sick persons, while the first calorimetric observations were made by 
Lavoisier and Laplace. Comparative observations are given at § 207, and also under Hiber- 
nation ($ 225). Physiology of the Metabolic Phenomena, etc. 
By the term metabolism vve mean those phenomena, whereby all—even 
the most lowly—living organisms are capable of incorporating the substances 
obtained from their food into their tissues, and making them an integral part 
of their own bodies. This part of the process is known as assimilation. 
Further, the organism in virtue of its metabolism forms a store of potential 
energy, which it can transform into kinetic energy, and which, in the higher 
animals at least, appears most obvious in the form of muscular work and heat. 
The changes of the constituents of the tissues, by which these trans- 
formations of the potential energy are accompanied, result in the formation of 
excretory products, which is another part of the process of metabolism. 
The normal metabolism requires the supply of food quantitatively and qualita- 
tively of the proper kind, the laying up of this food within the body, a regular 
chemical transformation of the tissues, and the formation of the effete products 
which have to be given out through the excretory organs. [Synthetic or con- 
structive metabolism is spoken of as anabolic, and destructive or analytical 
metabolism as katabolic, metabolism.] 
[The human organism is continually giving off daily, i. e., daily losses : — 
By the lungs : carbon dioxide and watery vapor. 
By the kidneys : water, urea, uric acid, etc., and salts. 
By the skin : water, and a small quantity of C02 and fatty matter. 
By the bowel: water, insoluble salts and residues of food, etc. 
From the surfaces of the body are given off a small quantity of epithelium 
and mucus, and, under certain conditions, the products of the secretion of the 
mammary glands and testes. 
The organism takes in daily a certain amount of matter, i. e., daily gains. 
By the lungs : oxygen. 
By the digestive tract, i. e., food : water, salts, proteids, carbohy- 
drates and fats. 
When the income exactly equals the expenditure, i. <?., quantitatively, the 
animal is said to be in equilibrium.] 
[We have discussed the daily income and expenditure of the body from the 
quantitative side, but when we compare these qualitatively we find that there 
is a great difference between what we take in as food and give off as excretions. 
Setting aside the water and salts taken in with the food—for they are excreted 
nearly unchanged—our food consists of highly complex organic, and but 
slightly oxidized bodies—proteids, fats, and carbohydrates ; while the 
excreta, on the other hand, are such simple bodies as carbon dioxide (C02), 
water, and urea, the last of which readily splits up into carbon dioxide and 
ammonia. We have seen that a supply of oxygen is absolutely necessary for 
life, and that it is taken in by the respiratory processes, and carried to the tis- 
sues by the haemoglobin of the red blood-corpuscles. In the capillaries these 
give up their oxygen to the tissues, and we have seen good reasons for believing 
that the oxygen is used up in the tissues themselves—oxidation-processes— 430 
METABOLIC PROCESSES. 
and that there also carbon dioxide is formed (§ 131), constituting the so- 
called “ inner respiration.” In the tissues and organs the nutrient organic 
substances are more and more oxidized, until the final products, water, carbon 
dioxide, and urea are reached. All this takes place through and by the activity 
of the living cellular elements of the tissues. The cellular elements of each 
organ or tissue select from the lymph the materials they require, but it is evi- 
dent that the process of oxidation in the tissues is not determined solely by 
their affinity for oxygen, for the fats which are oxidized with difficulty are 
completely decomposed in the body into C02 and H20. Again, such easily 
oxidizable substances as uric acid occur in the body, while some substances 
which are greedy of oxygen, e.g., pyrocatechin, pass into the urine unchanged.] 
[But we have every reason to believe that reduction-processes also take 
place in the organism, although they are far less than the oxidation-processes. 
When we group the various chemical processes taking place in the body, they 
are by no means all simple processes of oxidation ; we have dissociation, or 
the separation of a complex body into its components, taking place, as in the 
separation of Hb02 into Hb and O. The decomposition may be either of a 
simple nature, i. e., without the addition of any new element,—i. e., simple 
decomposition,—or a molecule of water may be taken up, constituting 
hydrolytic decomposition, or oxygen maybe combined with it, constituting 
what we know as oxidation. In addition, various synthetic and reduction- 
processes may take place; so that it is plain that decomposition and oxidation- 
processes go on together in the organism.] 
[When we compare the complex proteid with what represents it chiefly in the 
excreta—viz., urea—one is not to assume that urea is formed directly from 
the proteid. There is reason to believe that in the process of katabolism there 
are a large number of intermediate less highly oxidized bodies formed before the 
final stage of urea is reached. We are but imperfectly acquainted with these. 
The following represents some of these bodies, as far as their ratio of C and N 
are concerned, but one is not to assume that they are all precursors of urea. 
Albumin contains i atom N to 4 C 
Glutin (( 1 <( 3/4 lt 
Glycin „ 1 ,< 2 „ 
Kreatin and Kreatinin u 1 u 1A u 
Uric acid l( 1 u 1A u 
Allantoin „ 1 u 1 
Urea „ 1 ,, yi u 
In proportion as the members of this group become poorer in C, they become 
richer in N, and also in O.] 
[Of the numerous intermediate bodies—the products of the retrogressive 
metabolism of the tissues—we know much too little to be able to state definitely 
what are the immediate precursors of urea. Perhaps leucin, glycocoll or glycin, 
asparagin and ammonia salts are precursors of urea ; at least when given to an 
animal they reappear as urea. These bodies, as we have seen, are formed in 
the small intestine, and it is supposed that they are changed into urea in the 
liver (§ 256).] 
[As albumin contains 1 atom N to 4 C and urea 1 N to *4 C, it is evident 
that in the decomposition of a proteid a non-nitrogenous residue must be set 
free, and doubtless it also forms a series of intermediate bodies, each of which 
step by step gains more O, and contains less C, until it is finally excreted as 
C02 and H20. If, however, the amount of this non-nitrogenous residue be 
greater than can be decomposed in the body, there is reason to believe that it 
may be stored up in the form of fat (§ 241).] 
[The changes undergone by the carbohydrates are much simpler. First 
the starches are changed into sugar in the mouth and intestine, and sugar formed Sec. 229.] 
OXIDATION AND REDUCTION PROCESSES. 
431 
in the intestine enters the blood for the most part as such. In the liver it is 
dehydrated and glycogen is formed, but this again slowly enters the blood- 
stream as sugar. It is then comparatively rapidly oxidized into C02 and H20. 
What the intermediate products are is uncertain. If the sugar be in excess of 
the needs of the economy it is supposed that it may be stored up as fat (§ 241).] 
[The fats, although they are decomposed with difficulty by oxidizing agents, 
are yet rapidly and completely split up in the organism into C02 and H20. 
The oxidation does not seem to be a direct process, but a number of interme- 
diate bodies seem to be formed. We have in the body examples of the series 
of fatty acids with the formula CnH2n02 (formic, acetic, propionic acid, etc.) 
so that they are probably intermediate bodies. When fat is taken in excess it 
is not necessarily stored up in the body; in fact, there is reason to believe that 
fat in the body is chiefly formed from proteids (§ 241).] 
[Amongst the oxidation processes may be classified the formation of sul- 
phuric acid. The sulphur contained in the proteid molecule is oxidized, and 
appears either as a sulphate, or, in small amount, in the aromatic compounds of 
the urine (§ 262) (After Munk).~\ 
[“ The chemical processes of the animal organism, therefore, may be repre- 
sented as a series of oxidation and reduction processes,—chiefly, however, 
analytical processes—in virtue of which the highly complex and slightly oxi- 
dized constituents*of the body, i. e., those taken into the body as food—are 
decomposed into the simple and highly oxidized compounds—urea, carbon 
dioxide, sulphuric acid, and water, and removed from the body as such by the 
various organs of excretion” (Munk')I\ 
[Alongside of these oxidation processes there are certain synthetic and re- 
duction processes which take place in the body, e. g., the formation of 
haemoglobin. Benzoic acid unites with glycocoll, and appears in the urine as 
hippuric acid (§ 260) ; phenol unites with sulphuric acid, and appears as phenol- 
sulphuric acid. Fatty acids taken into the alimentary canal unite somewhere 
with glycerin and form the corresponding neutral fat (§ 192, 3), and this with- 
out glycerin being administered at the same time with the fatty acid. But, in 
any case, the synthetic processes are far less in evidence, and are far fewer in 
number, than the oxidation and analytic chemical processes, which are so 
characteristic of animal metabolism generally, in contrast to what occurs in 
vegetable metabolism (see Introduction).] 
229. THE MOST IMPORTANT SUBSTANCES USED AS 
FOOD.—Water.—When we remember that 58.5-64 per cent, of the body 
consists of water, that water is being continually given off by the urine and 
faeces, as well as through the skin and lungs, that the processes of digestion and 
absorption require water for the solution of most of the substances used as 
food, and that numerous substances excreted from the body require water for 
their solution, especially in the urine, the great importance of water and its 
continual renewal within the organism are at once apparent. As put by 
Hoppe-Seyler, all organisms live in water, and even in running water, a remark 
which ranks with the old saying—“ Corpora non agunt nisi fluida.” 
[According to Volkmann, 100 parts of a human being consist of 64 parts water, 16 proteid 
(and gelatin), 14 fat, and 5 parts ash. As the muscles make up 42-43 parts of the entire body, 
and contain 21 per cent, of proteid and 75 per cent, of water, it is evident that in round 
numbers the muscles contain about half the proteids and more than the half of the total water of 
the body.] , 
Water—as far as it is not a constituent of all fluid foods—occurs in different forms as drink: 
(1) Rain water, which most closely resembles distilled or chemically pure water, always 
contains minute quantities of C02, NH3, nitrous and nitric acids. (2) Spring water usually 
contains much mineral substance. It is formed from the deposition of watery vapor or rain 
from the air, which permeates the soil, containing much C02 ; the C02 is dissolved by the 432 
WATER AS A FOOD. 
[Sec. 229. 
water, and aids in dissolving the alkalies, alkaline earths, and metals, which appear in solution 
as bicarbonates, e.g., of lime or iron oxide. The water is removed from the spring by proper 
mechanical appliances, or it bubbles up on the surface in the form of a “ spring.” (3) River 
water usually contains much less mineral matter than spring water. Spring water floating on 
the surface rapidly gives off its C02 whereby many substances—e.g., lime—are thrown out of 
solution, and deposited as insoluble precipitates. 
Gases in Water.—Spring water contains little O, but much C02, the latter giving to it its 
fresh taste. Hence, vegetable organisms flourish in spring water, while animals requiring, as 
they do, much O, are but poorly represented in such water. Water flowing freely gives up C02, 
and absorbs O from the air, and thus affords the necessary conditions for the existence of fishes 
and other marine animals. River water contains to fa of its volume of absorbed gases, which 
may be expelled by boiling or freezing. 
Drinking water is chiefly obtained from springs. River water, if used for this purpose, must 
be filtered to get rid of mechanically suspended impurities. For household purposes a charcoal 
filter may be used, as the charcoal acts as a disinfectant. Alum has a remarkable action. When 
added to give a dilution containing 0.0001 per cent., it makes turbid water clear. 
Investigation of Drinking Water.—Drinking water, even in a thick 
layer, ought to be completely colorless, not turbid, and without odor. Any odor 
is best recognized by heating it to 50° C., and adding a little caustic soda. It 
ought not to be too hard, i. e., it ought not to contain too much lime (and mag- 
nesia) salts. 
By the term “ degree of hardness ” of a water is meant the unit amQunt of lime (and mag- 
nesia) in 100,000 parts of water; a water of 20 degrees of hardness contains 20 parts of lime 
(calcium oxide) combined with C02, sulphuric, or hydrochloric acids (the small amount of mag- 
nesia may be neglected). A good drinking water ought not to exceed 20 degrees of hardness. 
The hardness is determined by titrating the water with a standard soap solution, the result being 
the formation of a scum of lime-soap on the surface. The hardness of unboiled water is called 
its total hardness, while that of boiled water is called permanent hardness. Boiling drives off 
the C02, and precipitates the calcium carbonate, so that the water at the same time becomes softer. 
The presence of sulphuric acid, or sulphates, is determined by the water becoming turbid on 
adding a solution of barium chloride and hydrochloric acid. 
Chlorine occurs in small amount in pure spring water, but when it occurs there in large 
amount—apart from its being derived from saline springs, near the sea or manufactories—we may 
conclude that the water is contaminated from water-closets or dunghills, so that the estimation of 
chlorine is of importance. For this purpose use a solution, A, of 17 grms. of crystallized silver 
nitrate in 1 litre of distilled water; I cubic centimetre of this solution precipitates 3.55 milligrams of 
chlorine as silver chloride. Use also B, a cold saturated solution of neutral potassium chromate. 
Take 50 cubic centimetres of the water to be investigated, and place it in a beaker, add to it 2 to 3 
drops of B,and allow the fluid A to run into it from a burette until the white precipitate first formed 
remains red, even after the fluid has been stivred. Multiply the number of cubic centimetres of 
A used by 7.1, and this will give the amount of chlorine in 100,000 parts of the water. Example 
—50 c.cmtr. requires 2.9 c.cmtr. of the silver solution, so that 100,000 parts of the water contain 
2.9 X 7.1 = 20.59 parts chlorine (Kubel Tiemann). Good water ought not to contain more than 
15 milligrams of chlorine per litre. 
The presence of lime may be ascertained by acidulating 50 cubic centimetres of the water 
with HC1, adding ammonia in excess, and afterwards adding ammonia oxalate; the white pre- 
cipitate is lime oxalate. According to the degree of turbidity, we judge whether the water is 
“ soft ” (poor in lime), or “ hard ” (rich in lime). 
Magnesia is determined by taking the clear fluid of the above operation, after removing the 
precipitate of lime, and adding to it a solution of sodium phosphate and some ammonia; the 
crystalline precipitate which occurs is magnesia. 
The more feeble all these reactions which indicate the presence of sulphuric acid, chlorine, 
lime, and magnesia are, the better is the water. In addition, good water ought not to contain 
more than traces of nitrates, nitrites, or compounds of ammonia, as their presence indicates the 
decomposition of nitrogenous organic substances. 
For nitric acid, take 100 cubic centimetres of water acidulated with two or three drops of 
concentrated sulphuric acid, add several pieces of zinc together with a solution of potassium 
iodide, and starch solution—a blue color indicates nitric acid. The following tests are very deli- 
cate : (1) Brucine test.—Add to half a drop of water in a capsule two drops of a watery solu- 
tion of Brucinum sulphuricum, and afterwards several drops of concentrated sulphuric acid ; a 
rose-red coloration indicates the presence of nitric acid. (2) [Diphenylamine test.—Pour a 
thin layer of a 2 per cent, solution of diphenylamine in strong sulphuric acid on a white plate. 
A drop of water containing nitrates or nitrites gives a blue color.] Sec. 229.] 
EXAMINATION OF WATER. 
433 
The presence of nitrous acid is ascertained by the blue coloration which results from the addi- 
tion of a solution of potassium iodide, and solution of starch, after the water has been acidulated 
with sulphuric acid. 
Compounds of ammonia are detected by Nessler’s reagent, which gives a yellow or reddish 
coloration when a trace of ammonia is present in water; while a large amount of these com- 
pounds gives a brown precipitate of the iodide of mercury and ammonia. 
The contamination of water by decomposing animal substance is determined by the amount 
of N it contains. In most cases it is sufficient to determine the amount of nitric acid present. 
For this purpose we require (A) a solution of 1.871 grms. potassium nitrate in one litre distilled 
water—I cubic centimetre contains 1 milligram nitric acid; (B) a dilute solution of indigo, which 
is prepared by rubbing together one part of pulverized indigotin with six parts H2S04, and allow- 
ing the deposit to subside, when the blue fluid is poured into forty times its volume of distilled 
water and filtered. This fluid is diluted with distilled water until a layer, 12 to 15 mm. in 
thickness, begins to be transparent. 
To test the activity of B, place 1 cubic centimetre of A in 24 cubic centimetres water, add some 
common salt and 50 cubic centimetres concentrated sulphuric acid, and allow B to flow from a 
burette into this mixture until a faint green color is obtained. The number of cubic centimetres 
of B used correspond to 1 milligram of nitric acid. 
Twenty-five cubic centimetres of the water to be investigated are mixed with 50 cubic centi- 
metres of concentrated H2S04, and titrated with B until a green color is obtained. This pro- 
cess must be repeated, and on the second occasion the solution B must be allowed to flow in at 
once, when usually somewhat more indigo solution is required to obtain the green solution. The 
number of cubic centimetres of B (corresponding to the strength of B as determined above) indi- 
cates the amount of nitric acid present in 25 c.cmtr. of the water investigated. As much as xo 
milligrams nitric acid have been found in spring water (Marx, Trommsdorff). 
Sulphuretted Hydrogen is recognized by its odor; also by a piece of blotting-paper moist- 
ened with alkaline solution of lead becoming brown, when it is held over the boiling water. If 
it occurs as a compound in the water, sodium nitro-prusside gives a reddish-violet color. 
It is of the greatest importance that drinking water should be free from the presence of organic 
matter in a state of decomposition. Organic matter in a state of decomposition, and the organ- 
isms therewith associated, when introduced into the body, may give rise to fatal maladies, e. g 
cholera and typhoid fever. This is the case when the water-supply has been contaminated from 
water which has percolated from water-closets, privies, and dung-pits. The presence of organic 
matter may be detected thus—(1) A considerable amount of the water is evaporated to dryness in 
a porcelain vessel; if the residue be heated again a brown or black color indicates the presence 
of a considerable amount of organic matter; and if it contain N, there is an odor of ammonia. 
Good water treated in this way gives only a light brown stain. The presence of micro-organ- 
isms may be determined microscopically after evaporating a small quantity of the water on a 
glass slide. (2) The addition ofpotassio-gold chloride to the water gives a black frothy precipi- 
tate after long standing. (3) A solution of potassium permanganate, added to the water in a 
covered jar, gradually becomes decolorized, and a brownish precipitate is formed. 
Water containing much organic matter should never be used as drinking water, and this is 
especially the case when there is an epidemic of typhoid fever, cholera, or diarrhoea. In all such 
circumstances, the water ought to be boiled fora long time, whereby the organic germs are killed. 
The insipid taste of the water after boiling may be corrected by adding a little sugar or lime 
juice. 
230. THE MAMMARY GLANDS AND MILK.—Milk-Duct.— 
About 20 galactoferous ducts open singly upon the surface of the nipple. Each 
of these, just before it opens on the surface, is provided with an oval dilatation 
—the sinus lacteus. When traced into the gland, the galactoferous ducts 
divide like the branches of a tree, and a large branch of the duct passes to each 
lobe of the gland, all the lobes being held together by loose connective-tissue. 
Only during lactation do all the fine terminations of the ducts communicate 
with the globular glandular acini. Every gland acinus consists of a membrana 
propria, surrounded externally with a network of branched connective-tissue 
corpuscles, and lined internally with a somewhat flattened polyhedral layer of 
nucleated secretory cells (fig. 287). The size of the lumen of the acini de- 
pends upon the secretory activity of the glands; when it is large, it is filled 
with milk containing numerous refractive fatty granules. The walls of the milk- 
ducts consist of fibrillar connective-tissue. Some fibres are arranged longitu- 
dinally, but the chief mass are disposed circularly, and are permeated externally 
with elastic fibres, while in the finer ducts there is a membrana propria con- STRUCTURE OF THE MAMMA. 
[Sec. 230. 
tinuous with that of the gland acini. The ducts are lined by cylindrical epi- 
thelium. 
During the first few days after delivery, the breasts secrete a small amount of 
milk of greater consistence, and of a yellow color—the colostrum—in which 
large cells filled with fatty granules occur—the colostrum-corpuscles (fig. 289). 
Sometimes a nucleus is observable within them, and rarely they exhibit amoe- 
boid movements (fig. 288, c, d, e). The regular secretion of milk begins after 
three to four days. It was formerly supposed that 
the cells of the acini underwent a fatty degeneration, 
and thus produced the fatty granules of the milk. 
It is more probable, from recent observations, that 
the cells of the acini manufacture the fatty granules, 
and their protoplasm eliminates them, at the same 
time forming the clear fluid part of the milk. 
Changes in the gland cells during Secre- 
tion.—Pratsch and Heidenhain found that the secre- 
tory cells in the non-secreting gland (fig. 288, I), 
were flat, polyhedral, and uni-nucleated, whilst the 
secreting cells (fig. 288, II) often contained sev- 
eral nuclei, were more albuminous, higher, and cylin- 
drical in form. The edge of the cell directed 
towards the lumen of the acinus undergoes character- 
istic changes during secretion. Fatty granules are formed in this part of the 
cell, and are afterwards extruded. The decomposed portion of the cell is dis- 
solved in the milk, and the fatty granules become free as milk-globules (fig. 
Acini of the mammary gland 
of a sheep during lactation. 
a, membrana propria; b, 
secretory epithelium. 
Fig. 287. 
F ig. 288. 
I. Inactive acinus of the mamma. II. During the secretion of milk—a, b, milk-globules; 
c, d, e, colostrum corpuscles; f, pale cells (bitch). 
288, II, a). If nuclei are present in that part of the cell which is broken up, 
they also pass into the milk and give rise to the presence of nuclein in the 
secretion. 
Besides the milk-globules and colostrum corpuscles, Rauber has found leucocytes undergoing 
fatty degeneration, and single pale cells (/). Occasionally milk-globules are found with traces 
of the cell-substance adhering to their surface (b). 
Formation of Milk.—Concerning the formation of the individual constituents of milk, 
H. Thierfelder, who digested fresh mammary glands directly after death, found that during the 
digestion of the glands, at the temperature of the body, a reducing substance, probably lactose, 
was formed by a process of fermentation. The mother substance (saccharogen) is soluble in 
water, but not in alcohol or ether, is not destroyed by boiling, and is not identical with glycogen. 
The ferment which forms the lactose is connected with the gland-cells—it does not pass into the 
milk, nor into a watery extract of the gland. During the digestion of the mammary glands at 
the temperature of the body, casein is formed, probably from serum-albumin, by a process of 
fermentation. This ferment occurs in the milk. 
The nipple and its areola are characterized by the presence of pigment—more abundant 
during pregnancy—in the rete Malpighii of the skin, and by large papillae in the cutis vera. Sec. 230.] 
STRUCTURE OF MAMMARY GLANDS. 
Some of the papillse contain touch-corpuscles. Numerous non-striped muscular fibres surround 
the milk-ducts in the deep layers of the skin and in the subcutaneous tissue, which contains no 
fat. These muscular fibres can be traced, following a longitudinal course, to the termination of 
the ducts on the surface. The small glands of Montgomery, which occur on the areola dur- 
ing lactation, are just small milk-glands, each with a special duct opening on the surface of the 
elevation. 
Arteries proceed from several sources to supply the mamma, but their branches do not 
accompany the milk-ducts; each gland acinus is surrounded by a network of capillaries, which 
communicate with those of adjoining acini by small arteries and veins. The veins of the areola 
are arranged in a circle (circulus Halleri). The nerves are derived from the supraclavicular, 
and the II-IV-VI intercostals; they proceed to the skin over the gland, to the very sensitive 
nipple, to the blood-vessels and non-striped muscle of the nipple, and to the gland acini, where 
their mode of termination is still unknown. Lymphatics surround the alveoli, and they are 
often full. The milk appears to be prepared from the lymph contained in the lymphatics 
surrounding the acini. 
Comparative Anatomy of the Mamma.—The rodents, insectivora, and carnivora have io 
to 12 teats, while some of them have only 4. The pachydermata and ruminantia have 2 to 4 
abdominal teats, the whale has 2 near the vulva. The apes, bats, vegetable-feeding whales, 
elephants, and sloths, have 2, like man. In the marsupials the tubes are arranged in groups, 
which open on a patch of skin devoid of hair without any nipple. The young animals remain 
within the mother’s pouch, and the milk is expelled into their mouths by the action of a muscle 
—the compressor mammae. 
The development of the human mamma begins in both sexes during the third month ; 
at the fourth and fifth months a few simple tubular gland-ducts are arranged radially around the 
position of the future nipple, which is devoid of hair. In the new-born child the ducts are 
branched twice or thrice, and are provided with dilated extremities, the future acini. Up to the 
twelfth year, in both sexes, the ducts continue to divide dendritically ; but without any proper 
acini being formed. In the girl at puberty, the ducts branch rapidly; but the acini are formed 
only at the periphery of the gland ; during pregnancy, acini are also formed in the centre of 
the gland, while the connective-tissue at the same time becomes somewhat more opened out. At 
the climacteric period, or menopause, all the acini and numerous fine milk-ducts degenerate. 
In the adult male, the gland remains in the non-developed infantile condition. Accessory or 
supernumerary glands upon the breast and abdomen are not uncommon, sometimes the mamma 
occurs in the axilla, on the back, over the acromion process, or on the leg. A slight secretion of 
milk in a newly-born infant is normal. 
During the evacuation of the milk (500-1500 cubic centimetres daily), there is not only the 
mechanical action of sucking, but also the activity of the gland itself (| 152). This consists 
in the erection of the nipple, whereby its non-striped muscular fibres compress the sinuses on 
the milk-ducts, and empty them, so that the milk may flow out in streams. The gland acini are 
also excited to secretion reflexly by the stimulation of the sensory nerves of the nipple. The 
vessels of the gland are dilated, and there is a copious transudation into the gland—the trans- 
uded fluid being manufactured into milk under the influence of the secretory protoplasm. 
The amount of secretion has a relation to the blood-pressure (Rohrig). During sucking, not 
only is the milk in the gland extracted, but new milk is formed, owing to the accelerated secre- 
tion. Emotional disturbances—anger, fear, etc.—arrest the secretion. Laffont found that stimu- 
lation of the mammary nerve (bitch) caused erection of the teat, dilatation of the vessels, and 
secretion of milk. After section of the cerebro-spinal nerves going to the mamma, Eckhard 
observed that erection of the teat ceased, although the secretion of milk in a goat was not inter- 
rupted. The rarely observed galactorrhcea is perhaps to be regarded as a paralytic secretion 
analogous to the paralytic secretion of saliva. Heidenhain and Pratsch found that the secretion 
(bitch) was increased by injecting strychnine or curare after section of the nerves of the gland. 
The “ milk-fever,” which accompanies the first secretion of milk, probably depends on stimu- 
lation of the vaso-motor nerves, but this condition must be studied in relation with the other 
changes which occur within the pelvic cavity after birth. [Some substances, such as atropin, 
arrest the secretion of milk.] 
231. MILK AND ITS PREPARATIONS.—Milk represents a 
complete or typical food in which are present all the constituents necessary 
for maintaining the life and growth of the body of an infant (§ 236). [It 
contains 82-90 per cent, of water, and 10-18 per cent, of solids varying with 
the animal’s milk investigated. In round numbers, the water = 87.5, pro- 
teid = 3.5, fats = 4, sugar = 5, and ash = 0.6. The solids of milk consist 
of proteids (chiefly casein or caseinogen), fats, carbohydrates (lactose), and 
inorganic salts.] [If an adult were to live on milk alone, to get the 23 oz. of 436 
[Sec. 231. 
THE COMPOSITION OF MILK. 
dry solids necessary, he would have to take 9 pints of milk daily, which would 
give far too much water, fat, and proteids.] To every 10 parts of proteids 
there are 10 parts fat and 20 parts sugar. Relatively more of the fat than the 
proteid of the milk is absorbed (Rubtier). 
Characters.—Milk is an opaque, bluish-white fluid, with a sweetish taste 
and a characteristic odor, probably due to the peculiar volatile substances 
derived from the cutaneous secretions of the glands, and it has a specific gravity 
of 1026 to 1035. When it stands for a time, numerous milk globules, butter 
globules or cream, collect on its surface, under which there is a bluish watery 
fluid. Human milk is always alkaline, cow’s milk may be alkaline, acid, or 
amphoteric ; while the milk of carnivora is always slightly acid. 
[Quantity secreted.—A woman secretes 800 cc. to 1 litre, and a cow 6-7 
litres per day.] 
j, Milk-Globules.—When milk is examined microscopically, it is seen to con- 
tain numerous small highly refractive oil-globules [0.0015-0.005 millimetre 
in diameter], floating in a clear fluid—the milk-plasma (figs. 288, a b, 289) ; 
while colostrum corpuscles and epithelium 
from the milk-ducts are not so numerous. 
The white color and opacity of the milk 
are due to the presence of the milk- 
globules, which reflect the light; the 
globules consist of a fat, or butter, and 
are said by some to be surrounded with a 
very thin envelope of casein or haptogen 
membrane [so that milk is a perfect emul- 
sion.] 
If acetic acid or liquor potassae be added to a 
microscopic preparation of milk, the iatty granules 
run together to form irregular masses. If cow’s 
milk be shaken with caustic potash, the casein 
envelopes are dissolved, and if ether be added, the 
milk becomes clear and transparent, as the ether 
dissolves out all the fatty particles in the solution. 
Ether cannot extract the fat from cow’s milk until 
acetic acid or caustic potash is added to liberate the 
fats from their envelopes; but shaking with ether 
is sufficient to extract the fats from human milk. 
Some observers deny that an envelope of casein exists, and, according to them, milk is a simple 
emulsion, kept emulsionized owing to the colloid swollen up casein in the milk-plasma. The 
treatment of milk with potash and ether makes the casein unable any longer to preserve the 
emulsion (Soxhlet). 
The fats of the milk-globules are the triglycerides of stearic, palmitic, 
oleic acids; very little myristic, arachic (butinic), capric, caprylic, caproic, 
and butyric acids, with traces of acetic and formic acids and cholesterin. 
[The fats of milk exist in an emulsified condition, but even the finest milk- 
globules are much larger than the so-called molecular granules of chyle. The 
fats of milk are all animal fats, a mixture of olein, stearin, and palmitin, small 
quantities of capronin, and butyrin (tri-glycerides of caproic acid C6H1206 and 
butyric acid C4H802). Their melting point is between 31 and 33°C. Accord- 
ing to Lebedeff, human milk contains twice as much olein as palmitin and 
stearin, while in cow’s milk they are about equal. Butyrin and capronin make 
up about yj of the fats of milk (Munk).] 
Butter.—When milk is beaten or stirred for a long time [i. e., churned), the fat of the milk- 
globules is ultimately obtained in the form of butter, owing to the rupture of the envelopes of 
casein. Butter is soluble in alcohol and ether, and it is clarified by heat (6o° C.), or by washing 
in water at 40° C. When allowed to stand exposed to the air, it first becomes sour, ow'ing to 
Microscopic appearance of milk, (M) upper 
half, and colostrum (C) lower half. 
Fig. 289. Sec. 231.] 
THE COMPOSITION OF MILK. 
437 
the formation of lactic acid, and afterwards rancid, owing to the glycerin of the neutral fats 
being decomposed by fungi into acrolein and formic acid, while the volatile fatty acids give it its 
rancid odor. 
The milk-plasma is a clear, slightly opalescent fluid, and contains casein 
(§ 249, III, 3)—the chief proteid of milk—some lact albumin—(§ 32), small 
quantity of nuclein, and a trace of diastatic ferment (in human milk). 
The presence of other peculiar chemical bodies, e. g., lactoprotein, globulin, albumose, galactin, 
etc., is disputed by some chemists. Sebelien distinguishes besides the above proteids lacto- 
globulin. 
[Proteids of Milk.—There are two proteids in milk, one usually called 
casein, but which Halliburton proposes to call caseinogen (p. 306); this is 
the chief proteid and coagulates on the addition of rennet. The other is present 
in small amount and resembles serum-albumin in some characters, and is called 
lact-albumin.] 
[Caseinogen may be precipitated by the addition of acids, or by saturating 
the milk with neutral salts, or, better still, by a combination of both methods. 
It is immediately clotted at 40° by rennet, but if it be washed to free it of all 
calcic phosphate, clotting does not then take place. Caseinogen is usually 
stated to resemble alkali-albumin, but the latter does not clot with rennin. In 
its behavior towards neutral salts caseinogen behaves like a globulin.] 
[Casein.—This name is restricted by Halliburton to the proteid formed by 
the action of rennin on caseinogen. It is insoluble in the whey, and is the 
chief constituent of cheese. Foster calls the coagulated casein tyrein.] 
[Lact-albumin remains in solution after precipitation of caseinogen by 
MgS04. It coagulates at 70°-8o° C., and is not separable by fractional heat- 
coagulation into several albumins.] 
[Lacto-globulin is absent in normal milk although it is present in colostrum.] 
[Proteoses and peptones are absent (Halliburton).] 
When milk is boiled the albumin coagulates, while the surface also becomes 
covered with a thin scum or layer of casein, which has become insoluble [the 
rest of the milk remaining fluid. The scum is in part, perhaps, lact-albumin 
with altered caseinogen and some fat.] 
Casein.—When milk is filtered through fresh animal membranes or through a clay filter \i. e., 
through a porous clay cell under pressure], the casein does not pass through. [This shows that 
the casein is not in a state of true solution in the milk-plasma.] Precipitation.—It is precipi- 
tated by adding crystals of MgS04 to saturation. [If to milk twice its volume of a saturated 
solution of NaCl and crystals of NaCl be added, and the whole shaken thoroughly, casein is 
precipitated, and carries down with it fat, so that the clear filtrate contains the lactose, salts, 
and coagulable proteids.] 
The plasma contains milk-sugar (§ 252) [which differs from dextrose chiefly 
in its much less solubility in water and alcohol, and its much less tendency to 
crystallize. Nor does it undergo the alcoholic fermentation directly] ; a carbo- 
hydrate resembling dextrin (? lactic acid), lecithin, urea, extractives, kreatin, 
sarkin, (potassic sulphocyanide in cow’s milk), sodic and potassic chlorides, 
alkaline phosphates, calcium and magnesium sulphates, alkaline carbonates, 
traces of iron, fluorine, and silica; C02, N, and O. 
The coagulation of milk depends upon the coagulation of its casein, or, as it is called, case- 
inogen. In milk, caseinogen is combined with calcium phosphate, which keeps it in solution > 
acids which act on the calcium phosphate cause coagulation of the caseinogen (acetic and tartaric 
acids in excess redissolve it). All acids do not coagulate human milk. It is coagulated by 
two or more drops of hydrochloric acid (0.1 per cent.) or acetic acid (0.2 per cent.). The 
spontaneous coagulation of milk after it has stood for a time, especially in a warm place, is 
due to the production of lactic acid, which is formed from the milk-sugar in the milk by the 
action of bacillus acidi lactici [which is introduced from without] (§ 184, I). It changes the 
neutral alkaline phosphate into the acid phosphate, takes the casein from the calcium phos- 
phate, and precipitates the casein. The sugar is decomposed into lactic acid and C02. [Sec. 231. 
438 
THE COMPOSITION OF MILK. 
Souring of Milk.—When milk is exposed to the air for a time—varying with the temperature 
—it first becomes neutral, and then gradually acid; but for a time it remains fluid, even although 
acid. The acidity steadily increases, and after a certain degree of acidity the milk thickens, and 
finally a jelly-like mass is formed. This clot gradually shrinks—not unlike a blood clot—and 
squeezes out a small quantity of fluid, the milk-serum. 
Rennet or rennin (§ 250,9, d, \ 166, II) coagulates milk with an alkaline reaction (sweet 
whey). This ferment decomposes the caseinogen into the precipitated cheese (casein) and 
also into the slightly soluble whey-albumin, so that the coagulation by rennet is a process quite 
distinct from the coagulation of milk by the gastric and pancreatic juices, [and also from the 
precipitation produced by acids. The presence of calcium phosphate seems to be necessary for 
the complete action of the rennet (.Hammarsten).] 
Experiments with rennet and milk.—Warm a little milk to 40° C., and add a few drops of 
commercial rennet, setting aside the mixture in a warm place; a solid coagulum is soon formed, 
and by and by the whey separates from it. If the milk be previously diluted with water, no 
coagulum is formed ; and if the rennet be boiled before, it, like other ferments, is destroyed. A 
solution of rennet may be prepared by extracting the fourth stomach of the calf with glycerin. 
[When the milk is coagulated we obtain the curd, consisting of casein with some milk-globules 
entangled in it; the whey contains some soluble albumin and fat, and the great proportion of 
the salts and milk-sugar, together with lactic acid.] 
[Under the influence of weak specimens of rennet ferment the casein of milk may not undergo 
a complete change to the more insoluble form of tyrein (p. 306). The change may merely con- 
sist in certain chemical qualities of the casein being altered, the milk itself, as far as clotting or 
naked eye characteristics are concerned, being apparently unacted upon by the rennet ferment. 
The changes which the casein undergoes in these circumstances are that it becomes precipitated 
by a lower percentage of neutral salts or of free acid; whereas, under ordinary circumstances, 
there is no separation of casein by adding an equal bulk of saturated solution of sodium chloride 
to milk (there being required almost total saturation with the salt), yet under the above condi- 
tions an abundant separation of this changed casein occurs. With hydrochloric acid, just half 
the strength necessary to precipitate the casein in milk will form a curd when the milk has been 
subjected to such weak rennet ferment. One more point is of interest, and that is that the casein 
thus changed will coagulate on boiling, but for certain reasons this is not so satisfactory a test of 
the change as the action of neutral salt or free acid. 
Pancreatic juice was long ago described as possessing a rennet ferment. Very strong specimens 
do not show this action, probably because the proteolytic action masks it, but less strong will give 
the above-mentioned characteristics, though there may be no clotting of the milk as a whole. This 
power of the milk of becoming coagulated on boiling after treatment with pancreatic extracts was 
described first by Roberts as the metacaseine reaction (J. S. Edkins).'] 
[A milk-coagulating ferment is found in certain plants (artichokes, figs, Carica papaya), 
and causes milk to coagulate in neutral or alkaline solutions. It is also found in the small intes- 
tine of the calf, while a 5 per cent. NaCl solution of the seeds of Withania coagulans coagulates 
milk in an alkaline medium.] 
Boiling [by killing all the lower organisms), sodium bicarbonate ammonia, salicylic 
acid glycerin, and ethereal oil of mustard prevent the spontaneous coagulation. Fresh 
milk makes tincture of guaiacum blue, but boiled milk does not do so. When milk is exposed 
to the air for a long time, it gives off C02 and absorbs O; the fats are increased (? owing to the 
development of fungi in the milk), and so are the alcoholic and ethereal extracts from the de- 
composition of the casein. According to Schmidt-Mulheim, some of the casein becomes con- 
verted into peptone, but this occurs only in unboiled milk. 
Composition.—100 parts of milk contain :— 
Human. 
Cow. 
Goat. 
Ass. 
Water, 
Solids, 
. . 87.24 to 90.58 
86.23 
86.85 
89.OI 
. . 9.42 “ 12.39 
13-77 
I3-52 
IO.99 
Casein, . . . 
Albumin, 
. . 2.9I “ 3.92 1 . , 
0 y | 1.90 to 2.36 
i 3-23 
I0.50 
2-53 \ 
1.26 / 
3-57 
Butter, .... 
. . 2.67 “ 4.30 
4 50 
4-34 
1.85 
Milk-sugar, . . 
. . 3.15 “ 6.09 
4-93 
378 \ 
5-°5 
Salts, .... 
. . 0.X4 “ 0.28 
0.61 
0.65/ 
[Cow’s v. Human Milk.—The milk of the ass most closely resembles human milk, only the 
former contains much less fat. Cow’s milk is richer in proteids, but poorer in sugar. By 
adding vol. of water and sugar, cow’s milk can be made to resemble human milk. Human 
milk contains a very small amount of inorganic salts, its milk globules are smaller, and there are 
qualitative differences in its coagulated casein as compared with cow’s milk. Cow’s milk yields 
a dense curd, while the curd of human milk falls in a more flocculent condition; moreover, 
human milk is more easily digested, both by normal and artificial gastric juice, than cow’s milk.] Sec. 231.] 
THE COMPOSITION OF MILK. 
439 
[The following table shows the difference in composition between colostrum, (1-5 days after 
delivery) and milk (from the 7th day onwards). 
In 100 parts. 
Water. 
Proteids. 
Fats. 
Sugar. 
Salts. 
Colostrum, 
86.4 
5-3 
3-4 
4-5 
0.4 
Milk, 
87.8 
2-5 
3-9 
5-5 
o-3 
Colostrum, therefore, is richer in solids, and the latter consist chiefly of albumin, and but little 
casein. The casein gradually increases at the expense of the albumin, and on the 7th day there 
is chiefly casein and little albumin. Colostrum contains less sugar.] 
Gases.—Pfluger and Setschenow found in 100 vols. of milk 5.01 to 7.60 C02; 0.09 to 0.32 O; 
0.70 to 1.41 N, according to volume. Only part of the C02 is expelled by phosphoric acid. 
Salts.—The potash salts (as in blood-corpuscles and muscle) are more abundant than the soda 
compounds, while there is a considerable amount of calcium phosphate, which is necessary for 
forming the bones of the infant. Wildenstein found in 100 parts of the ash of human milk— 
sodium chloride, 10.73 ; potassium chloride, 26.33; potash, 21.44 ; lime, 18.78; magnesia, 0.87 ; 
phosphoric acid, 19; ferric phosphate, 0.21; sulphuric acid, 2.64; silica, traces. The amount 
of salts present is affected by the salts of the food. 
[Bunge gives the following table of the composition of the salts of milk : — 
In 1000 parts. 
Potash. 
Soda. 
Calcium. 
Magnesia. 
Iron 
Oxide. 
Phospho- 
ric Acid. 
Chlorine. 
Woman’s milk, 
O.7 
°-3 
0-3 
O.I 
0.006 
o-5 
0.4 
Cow’s milk, 
1.8 
1.1 
1.6 
0.2 
O.OO4 
2.0 
1 *7] 
Conditions Influencing the Composition of Milk.—The oftener the breasts are emptied, 
the richer the milk becomes in casein. The last milk obtained at any time [“ strippings ”] is 
always richer in butter, as it comes from the most distant part of the gland—viz., the acini. Some 
substances are diminished and others increased in amount, according to the time after delivery. 
The following are increased: Until the second month after delivery, casein and fat; until the 
5th month, the salts (which diminish progressively from this time onwards); from the 8th to the 
10th month, the sugar. The following are diminished : from loth to 24th month, casein ; from 
5th to 6th and 10th to nth month, fat; during 1st month, the sugar; from the 5th month, the 
salts. 
The greater amount of milk that is secreted (woman), the more casein and sugar, and the less 
butter it contains. The milk of a primapara is less watery. Rich feeding, especially proteids 
(small amount of vegetable food), increases the amount of milk and the casein, sugar, and fat in 
it; a large amount of carbohydrates (not fats) increases the amount of sugar. 
Modifying Conditions.—That cow’s milk is influenced by the pasture and food is well 
known. Turnip as food gives a peculiar odor, taste, and flavor to milk, and so do the fragrant 
grasses. The mental state of the nurse influences the quantity and quality of the milk. Jaborandi 
is the nearest approach to a galactagogue, but its action is temporary. Atropin is a true anti- 
galactagogue. The composition of the milk may be affected by using fatty food, by the use of 
salts, and above all by the diet [Dolan). 
[Milk may be a vehicle for communicating disease—by direct contamination from the 
water used for adulterating it or cleansing the vessels in which it is kept; by the milk absorbing 
deleterious gases ; by the secretion being altered in diseased animals.] Milk ought not to be 
kept in zinc vessels, owing to the formation of zinc lactate. 
Substitutes for Milk.—If other than human milk has to be used, ass’s milk most closely 
resembles human milk. Cow’s milk is best when it contains plenty of fatty matters—it must be 
diluted with its own volume of water at first and a little milk-sugar added. The casein of cow’s 
milk differs qualitatively from that of human milk; its coagulated flocculi or curd are much 
coarser than the fine curd of human milk, and they are only dissolved by the digestive juices, 
while human milk is completely dissolved. Cow’s milk when boiled is less digestible than un- 
boiled milk. 
Tests for Milk.—The amount of cream is estimated by placing the milk for twenty-four 
hours in a tall cylindrical glass graduated into a hundred parts, or creamometer; the cream 
collects on the surface, and ought to form from 10 to 24 vols. per cent. [The cream is generally [Sec. 231. 
440 
FORMATION OF THE MILK CONSTITUENTS. 
about T The specific gravity (fresh cow’s milk 1029 to 1034; when creamed, 1032 to 1040) 
—is estimated with the lactometer at 150 C. The sugar is estimated by titration with Fehling’s 
solution (g 150, II), but in this case 1 cubic centimetre of the solution corresponds to 0.067 grm- 
of milk-sugar; or its amount may be estimated by means of the saccharimeter ($ 150). Proteids 
are precipitated and the fats extracted with ether. The fats in fresh milk form about 3 per cent., 
and in skimmed milk \]/2 per cent. The amount of water in relation to the milk globules is 
estimated by the lactoscope or the diaphanometer of Donne (modified by Vogel and Hoppe- 
Seyler), which consists of a glass vessel with plane parallel sides placed 1 centimetre apart. A 
measured quantity of milk is taken, and water is added to it from a burette until the outline of a 
candle flame placed at a distance of 1 metre can be distinctly seen through the .diluted milk. This 
is done in a dark room. For 1 cubic centimetre of good cow’s milk, 70 to 85 centimetres water 
are required. [Other forms of lactoscope are used, all depending on the same principle of an 
optical test, viz., that the opacity of milk varies with and is proportional to the amount of butter- 
fats present, i.e., the oil globules. Bond uses a shallow cylindrical vessel with the bottom covered 
by black lines on a white surface. A measured quantity of water is placed in this vessel, and 
milk is added drop by drop, until the parallel lines on the pattern at the bottom of the dish cease 
to be visible. On counting the number of drops a table accompanying the appliance gives the per- 
centage of fats. This method gives approximate results. In all cases it is well to use fresh milk]. 
Various substances pass into the milk when they are administered to the mother—many 
odoriferous vegetable bodies, e.g., anise, vermuth, garlic, etc.; chloral, rhubarb, opium, indigo, 
salicylic acid, iodine, iron, zinc, mercury, lead, bismuth, antimony. In osteomalacia the amount 
of lime in the milk is increased (Gusserow). Potassium iodide diminishes the secretion of milk 
by affecting the secretory function. Amongst abnormal constituents are—hxmoglobin, bile- 
pigments, mucin, blood-corpuscles, pus, fibrin. Numerous fungi and other low organisms develop 
in evacuated milk, and the rare blue milk is due to the development of bacillus cyanogeneum. 
The milk-serum is blue, not the fungus. Blue milk is unhealthy, and causes diarrhoea. There 
are fungi which make milk bluish-black or green. Red and yellow milk are produced by a 
similar action of chromogenic fungi 184). The former is produced by Micrococcus prodigio- 
sus, which is colorless. The color seems to be due to fuchsin. The yellow color is produced 
by bacillus synxanthus. Some of the pigments seem to be related to the aniline-, and others to 
the phenol-coloring matters (Huppe). 
The rennet-like action of bacteria is a widely diffused property of these organisms; they 
coagulate and peptonize casein, and may ultimately produce further decompositions. The buty- 
ric acid bacillus ($ 184) first'coagulates casein, then peptonizes it, and finally splits it up, with 
the evolution of ammonia (Huppe). 
Milk becomes stringy owing to the action of cocci which form a stringy substance [— dextran, 
C12H10O10 (Scheibler)], just as beer or wine undergoes a similar or ropy change. [The milk of 
diseased animals may contain or transmit directly infectious matter.] 
Preparations of Milk.—(1) Condensed Milk.—80 grms. cane-sugar are added to 1 litre 
of milk ; the whole is evaporated to i; and while hot sealed up in tin cans. For children one 
teaspoonful is dissolved in a pint of cold water, and then boiled. 
(2) Koumiss is prepared by the Tartars from mare’s milk. After the addition of koumiss 
and sour milk, the whole is violently stirred, and it undergoes the alcoholic fermentation, 
whereby the milk-sugar is first changed into galactose, and then into alcohol; so that koumiss 
contains 2 to 3 per cent, of alcohol; while the casein is at first precipitated, but is afterwards 
partly redissolved and changed into acid-albumin and peptone. Tartar koumiss seems to be pro- 
duced by the action of a special bacterium (Diaspora caucasia). 
[How is Milk formed ?—It is obvious from its chemical composition that 
milk is not a simple transudation from the blood, for casein and lactose occur 
in it in large amount, and neither of these is present in the blood ; moreover, 
there is much fat, which occurs only in small amount in the blood. Lastly, the 
ash of milk is quantitatively different from the ash of blood-plasma. Milk, 
therefore, is a chemical product, due to the secretory activity of the cells of the 
mammary glands, which find only the raw material in the blood, and from this, 
by their own subtle chemistry, manufacture the specific products of the milk.] 
[Source of the Fats.—A plentiful supply of proteid food increases the 
amount of milk and its specific constituents, but most of all it increases its 
richness in fats. It seems clear that the fats of milk are not derived from the 
fats taken with the food, but are obtained from the splitting up of proteid mole- 
cules, and we know that albumin does split up under certain conditions into a 
nitrogenous and a non-nitrogenous molecule. Further, in a bitch fed on pure 
flesh diet, the milk contains a very large amount of fat.] Sec. 231.] 
CHEESE AND EGGS. 
441 
[The addition of fat to the food rather diminishes than increases the fats of the 
milk, if there be not simultaneously sufficient proteids in the food.] 
[Source of the Sugar.—The carbohydrates of the food have no effect on 
the amount of sugar in the milk, and even in herbivora there is no special 
effect to be noted. The greatest part of the sugar is also derived from the pro- 
teids, for bitches fed on an exclusively animal diet (flesh) yield a considerable 
amount of sugar.] 
[Source of Casein.—This seems to be derived from the proteids of the 
blood and lymph.] 
[To increase the quantity of milk, therefore, proteid food must be given.] 
[Margarine or Artificial Butter.—The best form is beef fat freed from its stearin and mixed 
with milk or genuine butter-coloring and flavoring ingredients. If prepared from wholesome 
pure animal fats, it has a nutritive value little inferior to butter, but it seems to be less assimilable 
than butter.] 
(3) Cheese is prepared by coagulating milk with rennet, allowing the whey 
to separate, and adding salt to the curd. When kept for a long time cheese 
“ripens,” the casein again becomes soluble in water, probably from the for- 
mation of soda albuminate; in many cases it becomes semi-fluid, when it takes 
the characters of peptones. When further decomposition occurs, leucin and 
tyrosin are formed. [The word tyrosin is derived from Tupo?, cheese.] The 
fats increase at the expense of the casein, and they again undergo further 
change, the volatile fatty acids giving the characteristic odor. 
The formation of peptone, leucin, tyrosin, and the decomposition of fat recall the digestive pro- 
cesses. [Cheese is coagulated casein, entangling more or less fat, so that the richness of the 
cheese will depend upon the kind of milk from which it is made. There are, in this sense, 
three kinds of cheese, whole milk, skim milk, and cream cheese, the last being represented by 
Stilton, Roquefort, Cheshire, etc. The composition is shown in the following table after Bauer:— 
Water. 
Nitrogenous. 
Matter. 
Fat. 
Extractives. 
1 
Ash. 
Cream cheese, . . 
35-75 
7.16 
3°-43 
2-53 | 
4-13 
Whole milk, . . . 
46.82 
27.62 
20.54 
2.97 
3-05 
Skim milk, . . . 
48.02 
32.65 
8.41 
6.80 
4.12 
Cream cheese, especially if it be made from the goat’s milk, acquires a very high odor and 
strong flavor when it is kept and “ ripens ”; the casein is partly decomposed to yield ammonia 
and ammonium sulphide, while the fats yield butyric, caproic, and other acids.] 
232. EGGS must be regarded as a complete food, as the organism of the 
young chick is developed from them. The yolk contains a characteristic pro- 
teid body—vitellin (§ 249), and an jxlbuminate in the envelopes of the yellow 
yolk spheres—nuclein, from the white yolk ; fats in the yellow yolk (palmitin, 
olein), cholesterin, much- lecithin, and as its decomposition-product, glycerin- 
phosphoric acid; grape-sugar, pigments (lutein), and a body containing iron 
and related to haemoglobin ; lastly, salts qualitatively the same as in blood— 
quantitatively as in the blood-corpuscles—and gases. The chief constituent of 
the white of egg is egg-albumin (§ 249), together with a small amount of pal- 
mitin and olein partly saponified with soda; grape-sugar, extractives; lastly 
salts, qualitatively resembling those of blood, but quantitatively like those of 
serum, and a trace of fluorine. Relatively more of the nitrogenous constituents 
than of the fatty constituents of eggs are absorbed {Rubier). [Considered as 
a food, eggs are obviously deficient in carbohydrates.] 
[The shell is composed chiefly of mineral matter (91 per cent, of calcic carbonate, 6 per cent, 
of calcic phosphate, and 3 per cent, of organic matter). A hen’s egg weighs about x| oz., of 
which the shell forms about Note the amount of fats in the yolk.] 
Composition:— 
White of Egg. Yolk. 
Water, 84.8 51.5 
Proteids, 12.0 15.0 
Fats, etc., 2.0 30.0 
White of Egg. Yolk. 
Mineral matter, ... 1.2 1.4 
Pigment Extractives, ... 2.1 [Sec. 233. 
442 
FLESH AND ITS COMPOSITION. 
233- FLESH AND ITS PREPARATIONS.—Flesh, in the form in 
which it is eaten, contains, in addition to the muscle-substance proper, more or 
less of the elements of fat, connective- and elastic-tissue mixed with it (§ 293). 
The following results refer to flesh freed as much as possible from those con- 
stituents. The chief proteid constituent of the contractile muscular substance 
is myosin ; serum-albumin occurs in the fluid of the fibres, in the lymph and 
blood of muscle. The fats are for the most part derived from the interfascicu- 
lar fat-cells, while lecithin and cholesterin come from the nerves of the muscles; 
the gelatin is derived from the connective-tissue of the perimysium, perineurium, 
and the walls of blood-vessels and tendons. The red color of the flesh is due to 
the haemoglobin present in the sarcous substance, but in some muscles, e. g., the 
heart, there is a special pigment, myohaematin (MacMunn), [although the 
latter statement is denied by Hoppe-Seyler.] Elastin occurs in thesarcolemma, 
neurilemma, and in the elastic fibres of the perimysium and walls of the vessels; 
the small amount of keratin is derived from the endothelium of the vessels. 
The chief muscular substance, the result of the retrogressive metabolism of the 
sarcous substance, is kreatin (-0.05 per cent.); kreatinin, sometimes inosinic 
acid, then lactic, or rather sarcolactic acid (§ 293). Further, taurin, sarkin, 
xanthin, uric acid, carnin, inosit (most abundant in the muscles of drunkards), 
urea (0.1 per cent, [but in the dog-fish 1.95 per cent.]), dextrin (in horse and 
rabbit, not constant) ; grape-sugar, but this is very probably derived post-mor- 
tem from glycogen (0.43 per cent.), which occurs in considerable amount in 
foetal muscles; lastly, volatile fatty acids. Amongst the salts, potash and 
phosphoric acid compounds are most abundant; magnesium phosphate exceeds 
calcium phosphate in amount. [The composition varies somewhat even in dif- 
ferent muscles of the same animal.] 
In 100 parts Flesh there are, according to Schlossberger and v. Bibra— 
Ox. 
Calf. 
Deer. 
Pig- 
Man. 
Fowl. 
Carp. 
Frog. 
Water, 
77-50 
78.20 
74-63 
78.30 
74-45 
77-3° 
79.78 
8043 
Solids, 
22.50 
21.80 
25-37 
21.70 
25-55 
22.7 
20.22 
19-57 
Soluble albumin, 
Coloring matter, . . 
| 2.20 
2.60 
I.94 
2.40 
i-93 
3°{ 
2-35 
1.86 
Glutin 
1.30 
1.60 
0.50 
0.80 
2.07 
1.2 
I.98 
2.48 
Alcoholic extract, . 
1.50 
I.40 
4-75 
I.70 
3-7i 
i-4 
3-47 
3-46 
Fats, 
1.30 
2.30 
1.11 
0.10 
Insoluble albumin, 
Blood-vessels, etc., 
i7-5o 
16.2 
16.81 
l6.8l 
15-54 
16.5 
11 -31 
11.67 
In 100 parts Ash there are— 
Horse. 
Ox. 
Calf. 
Pig- 
Potash, ... 
39-40 
35 94 
34-40 
37-79 
Soda 
4.86 
2-35 
4.02 
Magnesia, 
3.88 
3-3i 
1-45 
4.81 
Chalk, 
1.80 
1 -73 
I.99 
7-54 
Potassium, 
Sodium, 
} M7 { 
5-36 
} 10-59 { 
0.40 
Chlorine, 
4.86 
0.62 
Iron oxide, 
1.0 
0.98 
0.27 
o-35 
Phosphoric Acid, 
46.74 
34-36 
48.13 
44-47 
Sulphuric “ ...... 
0.30 
3-37 
Silicic .... 
2.07 
0.81 
Carbonic . . . . 
8.02 
Ammonia, 
0.15 Sec. 233.] 
COOKING OF FLESH AND SOUPS. 
443 
The amount of fat in flesh varies very much according to the condition of the animal. After 
removal of the visible fat, human flesh contains 7.15 ; ox, 11.12; calf, 10.4; sheep, 3.9; wild 
goose, 8.8; fowl, 2.5 per cent. 
The amount of extractives is most abundant in those animals which exhibit energetic muscu- 
lar action ; hence it is largest in wild animals. The extract is increased after vigorous muscular 
action, whereby sarcolactic acid is developed, and the flesh becomes more tender and is more 
palatable. Some of the extractives excite the nervous system, e.g., kreatin and kreatinin; and 
others give to flesh its characteristic agreeable flavor [“ o-masome,”] but this is also partly due to 
the different fats of the flesh, and is best developed when the flesh is cooked. The extractives 
in 100 parts of flesh are in man and pigeon, 3; deer and duck, 4; swallow, 7 per cent. 
[Flesh is characterized by its large percentage of proteids containing four times as much as 
milk. The flesh of birds contains most proteids, then follows that of mammals, and then fishes.] 
[Munk gives the following table of its composition : — 
In ioo Parts flesh. 
Ox. 
Calf. 
Pig. 
Horse. 
Fowl. 
Pike. 
Water, 
76.7 
75-6 
72.6 
74-3 
70.8 
79-3 
Solids, 
23-3 
24.4 
27.4 
25-7 
29.2 
20.7 
Myosin, albumin, and | 
gelatin, / 
20.0 
194 
I9.9 
21.7 
22.7 
18.3 
Fat, 
i-5 
2.9 
6.2 
2-5 
4.I 
0.7 
Carbohydrates, .... 
0.6 
0.8 
0.6 
0.6 
i-3 
0.9 
Salts, 
1.2 
i-3 
1.1 
1.0 
1.1 
0.8] 
Cooking of Flesh.—As a general rule, the flesh of young animals, owing to the sarcolemma, 
connective-tissue, and elastic constituents being less tough, is more tender and more easily 
digested than the flesh of old animals; after flesh has been kept for a time it is more friable 
and tender, as the inosit becomes changed into sarcolactic acid and the glycogen into sugar, and 
this again into lactic acid, whereby the elements of the flesh undergo a kind of maceration. 
Finely divided flesh is more digestible than when it is eaten in large pieces. In cooking meat, 
the heat ought not to be too intense, and ought not to be continued too long, as the muscular 
fibres thereby become hard and shrink very much. Those parts are most digestible which are 
obtained from the centre of a roast where they have been heated to 6o° to 70° C., as this tem- 
perature is sufficient, with the aid of the acids of the flesh, to change the connective-tissue into 
gelatin, whereby the fibres are loosened, so that the gastric juice readily attacks them. In roasting 
beef, apply heat suddenly at first, to coagulate a layer on the surface, which prevents the escape 
of the juice. 
Meat Soup is best prepared by cutting the flesh into pieces and placing them for several 
hours in cold water, and afterwards boiling. Liebig found that 6 parts per 100 of ox flesh were 
dissolved by cold water. When this cold extract was boiled, 2.95 parts were precipitated as 
coagulated albumin, which is chiefly removed by “ skimming,” so that only 3.05 parts remain in 
solution. From 100 parts of flesh of fowl, 8 parts were extracted, and of these 4.7 was coagu- 
lated and 3.3 remained dissolved in the soup. By boiling for a very long time, part of the 
albumin may be redissolved. The dissolved substances are: (1) Inorganic salts of the meat, 
of which 82.27 per cent, pass into the soup; the earthy phosphates chiefly remain in the 
cooked meat. (2) Kreatin, kreatinin, the inosinates and lactates which give to broth or beef-tea 
their stimulating qualities, and a small amount of aromatic extractives. (3) Gelatin, more abun- 
dantly extracted from the flesh of young animals. According to these facts, therefore, flesh 
broth or beef-tea is a powerful stimulant, supplying muscle with restoratives, but is not a food in 
the ordinary sense of the term, as kreatin in general leaves the body unchanged [y. Voit). The 
flesh, especially if it be cooked in a large mass, after the extraction of the broth, is still available 
as a food. 
Liebig’s Extract of Meat is an extract of flesh evaporated to a thick syrupy consistence. It 
contains no fat or gelatin or proteid, and is chiefly a solution of the extractives and salts of flesh. 
[It contains about 22 per cent, of water and 78 of solids. Of the latter—which contain no pro- 
teids—61 per cent, is organic, and 17 inorganic salts. Crystals of kreatin are found in large 
numbers in the extract.] 
[Extract of Fish.—A similar extract is now prepared from fish ; and such extract has no 
fishy flavor, but presents much the same appearance, odor, and properties as extract of flesh.] 
[Beef-Tea made by putting the meat, cut up into small pieces, in cold water and then gradu- 
ally heating it, is really a watery extract of certain of the constituents of meat. It has slight 
nutritive and stimulating properties, and may be regarded as a watery solution of the extractives, 
and salts of meat together with gelatin, minute quantities of soluble albumin, and, perhaps, some 
fat floating on the surface of the fluid.] 444 
VEGETABLE FOODS. 
[Sec. 233. 
[Preservation of Meat.—Much “preserved” meat in tins is now used. The Indians dry 
strips of meat in the sun’s rays to form pemmican. “ Pickling” or salting meat is much prac- 
ticed. Voit found that where meat is placed in brine its nutritive value is not greatly impaired. 
In salted meat, besides an increase of salt, he found a loss of 10.4 per cent, of water and of 
organic matters 2.1, albumin 1.1, extractives 13.5, and phosphoric acid 8.5 per cent. When 
meat is “ smoked ” the surface becomes harder, and the meat is acted on by creasote and other 
antiseptics present in the smoke of the wood used in the process.] 
234. VEGETABLE FOODS .—The nitrogenous constituents of plants 
are not so easily absorbed as animal food (Rubner). Still if they contain the 
same amount of N they may completely replace animal proteids {Rutgers), [and, 
according to Hoppe-Seyler, the vegetable proteids do not seem to differ essen- 
tially from animal proteids.] Carbohydrates, starch, and sugar are very com- 
pletely absorbed, and even a not inconsiderable proportion of cellulose may be 
digested (§ 184, I). The more fats that are contained in the vegetable food, 
the less are the carbohydrates digested and absorbed. 
[Vegetable foods are characterized by the very large amount of non-nitroge- 
nous substance they contain, and by the fact that this is usually contained in cel- 
lulose capsules, which are 
either not or with difficulty 
dissolved by the digestive 
juices, and they always yield 
a considerable amount of in- 
digestible residue, so that 
the herbivorous animals al- 
ways pass a larger quantity 
of faeces than carnivorous. 
Moreover, vegetable food is 
not so fully utilized in the 
digestive tract as animal food 
(p. 446). Further, the pot- 
ash and magnesia, especially 
the phosphatic salts, are 
more abundant than soda 
and lime, while there is little 
chlorine {Munk).~\ 
1. The cereals are most 
important vegetable foods; 
they contain proteids,starch, 
salts, and about 14 per cent, 
of water. The nitrogenous body glutin is most abundant under the husk 
(fig. 290, Kl). The use of whole meal containing the outer layers of the 
grain is highly nutritive, but bread containing much bran is somewhat indi- 
gestible {Rubner). Their composition is the following:— 
Fig. 290. 
Section of part of a grain of wheat; ep, epidermis with 
cuticle c; m, middle layer; qu, transverse, and sch, tubu- 
lar cells; br and n, coats of the seed; Kl, glutin cells; 
si, starch-grains within cells. 
ioo Parts of the Dry Meal contain 
100 Parts of Ash contain 
Of 
Albumin. 
Starch. 
Red Wheat. 
White Wheat. 
Wheat, 
16.52% 
56.25% 
27.87 
Potash, .... 
33-84 
Rye, 
II.92 
60.91 
15-75 
Soda 
. . 
Barley, 
17.70 
38.31 
i-93 
Lime, 
3-°9 
Maize, 
13-65 
77-74 
9.60 
Magnesia, .... 
13-54 
Rice, ...... 
7.40 
86.21 
1.36 
Iron oxide, . . . 
0.31 
Buckwheat, . . . 
6.8-10.5 
65.05 
49-36 
Phosphoric Acid, 
59-21 
0.15 
Silica, 
It is curious to observe that soda is absent from white wheat, its place being taken by other Sec. 234.] 
COMPOSITION OF VEGETABLE FOODS. 
445 
alkalies. Rye contains more cellulose and dextrin than wheat, but less sugar; rye-bread is 
usually less porous. 
The following table by Konig gives their composition, although they vary much with climate, 
soil, cultivation, etc.:— 
In 100 Parts. 
Wheat. 
Rye. 
Barley. 
Oats. 
Rice. 
Maize. 
Water, 
13.6 
11.1 
13-8 
I2.4 
131 
I3-1 
Proteid, 
12.4 
II.5 
11.1 
IO.4 
7-9 
9.9 
Fat, 
1.8 
1.8 
2.2 
5-2 
0.9 
4.6 
Carbohydrates and 
N-free extractives, 
67.9 
67.8 
64.9 
57-8 
76.5 
68.4 
Cellulose, .... 
2-5 
2.0 
5-3 
11.2 
0.6 
2-5 
Ash, 
1.8 
1.8 
2.7 
3-° 
1.0 
I-5 
The cereals have an outer envelope composed of cellulose : to facilitate di- 
gestion of the contents the cellulose envelopes are crushed or removed by the 
process of “ milling;” the finely ground contents constitute flour or meal. 
[Oatmeal contains more nitrogenous substances (gliadin and glutin-casein) 
than wheaten flour, but owing to the want of adhesive properties it cannot be 
made into bread. The amount of fat and salts is large (p. 447).] 
In the preparation of bread the meal is kneaded with water until dough is formed, and to 
it is added salt and yeast (Saccharomyces cerevisiae). When placed in a warm oven, the pro- 
teids of the meal begin to decompose and act as a ferment upon the swollen-up starch, which 
becomes in part changed into sugar. The sugar is further decomposed into C02 and alcohol, 
the C02 forms bubbles, which cause the bread to “rise,” and thus become spongy and porous. 
The alcohol is driven off by the baking (200°j, while much soluble dextrin is formed in the 
crust of the bread. [But C02 may beset free within the dough by chemical means without 
yeast or leaven, thus forming unfermented bread. This is done by mixing with the dough an 
alkaline carbonate, and then adding an acid. Baking powders consist of carbonate of soda and 
tartaric acid. In Dauglish’s process for aerated bread, the C02 is forced into water, and a 
dough is made with this water under pressure, and when the dough is heated, the C02 expands 
and forms the spongy bread. Bread as an article of food is deficient in N, while it is poor in 
fats and some salts. Hence the necessity for using some form of fat with it (butter or bacon).] 
2. The leguminous seeds or pulses contain much proteid, especially 
legumin ; together with starch, lecithin, cholesterin, and 9 to 19 per cent, 
water. Owing to the absence of glutin, they do not form dough, and bread 
cannot be prepared from them. On account of the large amount of proteids 
which they contain, and on account of their cheapness, they are admirably 
adapted as food for the poorer classes; excellent soup can be made with them. 
[The following table from Munk shows their composition contrasted with that of potatoes:— 
In ioo Parts. 
Lentils. 
Peas. 
Beans. 
Potatoes. 
Water, ... 
12-5 
14-3 
14.8 
76.O 
Proteids, 
24.8 
22.6 
23-7 
2.0 
Fat, 
1.9 
i-7 
1.6 
0.2 
Carbohydrates, 
54-8 
53-2 
49-3 
20.6 
Cellulose, 
3-6 
5-5 
7-5 
0.7 
Ash, 
2.4 
2.7 
3-i 
1.0 
[3. The whole group of farinaceous substances used as “pudding 
stuffs,” such as corn-flour, arrow-root, rice, hominy, are really very largely 
composed of starchy substances.] 
4. Potatoes contain 70 to 81 per cent, water, and of the solids about 20 
per cent, consists of starch. In the fresh juicy cellular tissue, which has an 
acid reaction, from the presence of phosphoric, malic, and hydrochloric acids, 446 
[Sec. 234. 
COMPOSITION OF VEGETABLES. 
there is 16 to 23 per cent, of starch, 2.5 soluble albumin, globulin, and a trace 
of asparagin. The envelopes of the cells swell up by boiling, and are changed 
into sugar and gums by dilute acids. The cells contain a large number of 
starch granules (fig. 291). The poisonous solanin occurs in the sprouts. In 
100 parts of potato ash, May found 49.96 potash, 2.41 sodium chloride, 8.11 
potassium chloride, 6.50 sulphuric acid derived from burned proteids, 7.17 silica. 
5. In fruits the chief nutrient ingredients are sugar and salts; the organic acids 
give them their characteristic taste, the gelatinizing substance is the soluble 
so-called pectin (C32H48032), 
which can be prepared arti- 
ficially by boiling the very 
insoluble pectose of unripe 
fruits and mulberries. 
6. Green Vegetables are 
especially rich in salts which 
resemble the salts of the blood; 
thus, dry salad contains 23 per 
cent, of salts which closely 
resemble the salts of the blood. 
Of much less importance are 
the starch, cell-substance, 
dextrin, sugar, and the small 
amount ofalbumin which they 
contain. 
[Vegetables are chiefly useful for 
the salts they contain, while many 
of them are antiscorbutic. Their 
value is attested by the serious de- 
fects of nutrition, such as scurvy, 
which result when they are not sup- 
plied in the food. In Arctic expe- 
ditions and the navy, lime juice is 
served out as an antiscorbutic.] 
[Salts of Vegetable Food.— 
Much interest attaches to the large 
amount of potash salts in vegetable 
food. They contain 2-8 times as 
much potash as soda, so that herbivora take 5-10 times as much potash as soda in their food. Bunge 
has shown that this large consumption of potash salts by certain of these animals is the cause of 
the great amount of common salt required by them ( 
[Preserved Vegetables.—The dried and compressed vegetables of Messrs. Chollet & Com- 
pany are an excellent substitute for fresh vegetables, and are used largely in naval and military 
expeditions.] 
[Utilization of Food.—As regards what percentage of the food swallowed 
is actually absorbed, we know that, stated broadly, vegetable food is assimilated 
to a much less extent than animal food in man. Fr. Hofmann gives the following 
table as showing this :— 
Fig. 291. 
Section of part of a potato. K, capsule; pi, plasma, con- 
taining cells with small starch-grains; r, protein crystals; 
s, starch. 
Weight of Food. 
Vegetable. 
Animal. 
Digested. 
Undigested. 
Digested. 
Undigested. 
Of ioo parts of solids, 
75-5 
24-5 
89.9 
II.I 
Of ioo “ albumin, . . 
46.6 
53-4 
8l.2 
18.8 
Of ioo “ fats or carbohydrates, 
90-3 
9-7 
96.9 
3-i] Sec. 234.] 
COMPOSITION OF FOODS AND DRINKS. 
447 
[The following table, abridged from Parkes, shows the composition of the chief articles of 
diet, and is also used for calculating diet tables:— 
Articles. 
Water. 
Proteids. 
Fats. 
Carbo- 
hydrates. 
Salts. 
Beef Steak, 
74-4 
20.5 
3-5 
1.6 
Fat pork, 
39-o 
9.8 
48.9 
2-3 
Smoked ham, 
27.8 
24.O 
36.5 
10.1 
White fish, 
78.0 
I8.I 
2.9 
1.0 
Poultry, 
74.0 
21.0 
3-8 
1.2 
White wheaten bread 
40.0 
8.0 
i.5 
49.2 
i-3 
Wheat flour, 
15.0 
11.0 
2.0 
70.3 
i-7 
Biscuit, ... 
8.0 
15-6 
i-3 
73-4 
i-7 
Rice, 
10.0 
5-o 
0.8 
83.2 
0.5 
Oatmeal, 
15.0 
12.6 
5-6 
63.0 
3° 
Maize, 
I3-S 
10.0 
6.7 
64-5 
1.4 
Macaroni, 
131 
9.0 
o-3 
76.8 
0.8 
Arrow-root 
15-4 
0.8 
83-3 
0.27 
Peas (dry), 
15.0 
22.0 
2.0 
53-o 
2.4 
Potatoes, 
74.0 
2.0 
0.16 
21.0 
1.0 
Carrots, 
85.0 
1.6 
0.25 
8.4 
1.0 
Cabbage, 
91.0 
1.8 
5-o 
5-8 
0.7 
Butter, 
6.0 
o-3 
91.0 
2.7 
Egg (tV for shell), 
73-5 
13-5 
11,6 
1.0 
Cheese, 
36.8 
33-5 
24-3 
5-4 
Milk (S. G. 1032), 
86.8 
4.0 
3-7 
4.8 
0.7 
Cream, 
66.0 
2.7 
26.7 
2.8 
1.8 
Skimmed milk, 
88.0 
4.0 
1.8 
5-4 
0.8 
Sugar, 
30 
96.5 
0-5] 
235-—CONDIMENTS, COFFEE, TEA, ALCOHOL.—Same substances are used 
along with food, not so much on account of their nutritive properties as on account of their 
stimulating effects and agreeable qualities, which are exerted partly upon the organ of taste and 
partly upon the nervous system. These are called condiments. 
Coffee, Tea, and Chocolate are prepared as infusions of certain vegetables [the first of the 
roasted berry, the second of the leaves, and the third of the seeds]. Their chief active ingredients 
are respectively caffein, thein (CgH10N4O2 -f- H20 trimethylxanthin), and theobromin 
(C7HgN402 dimethylxanthin), which are regarded as alkaloids of the vegetable bases, and which 
have recently been prepared artificially from xanthin (E. Fischer). [Guarana, or Brazilian 
cocoa, is made of the seeds ground into a paste in the form of a sausage. Mate or Paraguay tea 
(the leaves of a species of holly) is used in South America, and so also is the coca of the Andes 
(Erythroxylon Coca). These “ alkaloids ” occur as such in the plants containing them ; they 
behave like ammonia; they have an alkaline reaction, and form crystalline salts with acids. All 
these vegetable bases act upon the nervous system; some more feebly (as the above), others more 
powerfully (quinine); some stimulate powerfully, or completely paralyze (morphia, atropin, 
strychnin, curarin, nicotin). 
Effects of Tea and Coffee.—All these substances act on the nervous sys- 
tem ; they quicken thought, accelerate movement, and stir one to greater activity. 
In these respects they resemble the stimulating extractives of beef-tea. Coffee 
contains about per cent, of caffein, part of which only is liberated by the 
act of roasting. Tea has 6 per cent, of thein ; whilst green tea contains i per 
cent, ethereal oil, and black tea y per cent.; in green tea there is 18 per 
cent., in black 15 per cent, tannin ; green tea yields about 46 per cent., and 
the black scarcely 30 per cent, of extract. The inorganic salts present are 
also of importance ; tea contains 3.03 per cent, of salts, and amongst these are 
soluble compounds of iron, manganese, and soda-salts. In coffee, which yields 
3.41 per cent, of ash, potash salts are most abundant; in all three substances 
the other salts which occur in the blood are also present. 
Alcoholic drinks owe their action chiefly to the alcohol which they con- 
tain. Alcohol, when taken into the body, undergoes certain changes and pro- 448 
ALCOHOLIC DRINKS. 
[Sec. 235. 
duces certain effects—(i) About 95 per cent, of it is oxidized chiefly into C02 
and H20, so that it is so far a source of heat. As it undergoes this change very 
readily, when taken to a certain extent, it may act as a substitute for the con- 
sumption of the tissues of the body, especially when the amount of food is in- 
sufficient. [Hammond found that when he lived on an insufficient amount of 
food, alcohol, if given in a certain quantity, supplied the place of the deficiency 
of food, and he even gained in weight. If, however, sufficient food was taken, 
alcohol was unnecessary. As it interferes with oxidation, and where there is a 
sufficient amount of other food, in health it is unnecessary for dietetic pur- 
poses.] Small doses diminish the decomposition of the proteids to the extent 
of 6 to 7 per cent. Only a very small part of the alcohol is excreted in the 
urine ; the odor of the breath is not due to alcohol, but to other volatile sub- 
stances mixed with it, e.g., fusel oil, etc. (2) In small doses it excites, while 
in large doses it paralyzes the nervous system. By its stimulating qualities it 
excites to greater action, which, however, is followed by depression. (3) It 
diminishes the sensation of hunger. (4) It excites the vascular system, accel- 
erates the circulation, so that the muscles and nerves are more active, owing to 
the greater supply of blood. It also gives rise to a subjective feeling of warmth. 
In large doses, however, it paralyzes the vessels, so that they dilate, and thus 
much heat is given off (§ 213, 7 ; § 227) and the temperature is lowered. The 
action of the heart also becomes affected, the pulse becomes smaller, feebler, 
and more rapid. In high altitudes the action of alcohol is greatly lessened, 
owing to the diminished atmospheric pressure, whereby it is rapidly given off 
from the blood. 
Alcohol in small doses is of great use in conditions of temporary want, 
and where the food is insufficient in quantity. When alcohol is taken regu- 
larly, more especially in large doses, it affects the nervous system, and under- 
mines the psychical and corporeal faculties, partly from the action of the im- 
purities which it may contain, such as fusel oil, which has a poisonous effect 
upon the nervous system, partly by the direct effects, such as catarrh and in- 
flammation of the digestive organs, which it produces, and lastly, by its effect 
upon the normal metabolism. 
[The action of alcohol in lowering the temperature, even in moderate doses, is most impor- 
tant. By dilating the cutaneous vessels, it thus permits of the radiating of much heat from the 
blood. When the action of alcohol is pushed too far, and especially when this is combined with 
the action of great cold, its use is to be condemned. Brunton has pointed out that, as regards 
its action on the nervous system, it seems to induce progressive paralysis, affecting the nervous 
tissues “ in the inverse order of their development, the highest centres being affected first and the 
lowest last.” The judgment is affected first, although the imagination and “ emotions may be 
more than usually active.” The motor centres and speech are affected, then the cerebellum is 
influenced, and afterwards the cord, while by and by the centres essential to life are paralyzed, 
provided the dose is sufficiently large.] 
Preparation.—Alcoholic drinks are prepared by the fermentation of various carbohydrates, 
such as sugar derived from starch. The alcoholic fermentation, such as occurs in the manu- 
facture of beer, is caused 
by the development of the 
yeast plant, Saccharo- 
myces cerevisise ; while 
in the fermentation of the 
grape (wine), S. ellipsoid- 
eus is the species present 
(fig. 292). The yeast takes 
the substances necessary 
for the maintenance of its 
organic processes directly 
from the mixture of the 
sugar, viz., carbohydrates, 
proteids, and salts, especially calcium and potassium phosphates and magnesium sulphate. These 
substances undergo decomposition within the cells of the yeast plant, which multiply during the 
Fig. 292. 
i, Isolated yeast cells; 2, 3, yeast cells budding ; 4, 5, so-called en- 
dogenous formation of cells; 6, sprouting and formation of buds. Sec. 235.] 
EQUILIBRIUM OF THE METABOLISM. 
449 
process, and there are produced alcohol and C02 (£ 150), together with glycerin (3.2 to 3.6 per 
cent.) and succinic acid (0.6 to 0.7 per cent.). Yeast is either added intentionally or it reaches 
the mixture from the air, which always contains its spores. When yeast is completely excluded, 
or if it be killed by boiling [or if its action be prevented by the presence of some germicide], the 
fermentation does not occur. The alcoholic fermentation is due to the vital activity of a low 
organism. 
In the preparation of brandy, the starch of the grain or potatoes is first changed into sugar by 
the action of diastase or maltin. Yeast is added, and fermentation thereby produced ; the mix- 
ture is distilled at 78.3° C. The fusel oil is prevented from mixing with the alcohol by passing 
the vapor through heated charcoal. The distillate contains 50 to 55 per cent, of alcohol. 
In the preparation of wine, the saccharine juice of the grape—the must—after being ex- 
pressed from the grapes, is exposed to the air at io° to 150 C., and the yeast cells, which are 
floating about, drop into it and excite fermentation, which lasts 10 to 14 days, when the yeast 
sinks to the bottom. The clear wine is drawn off into casks, where it becomes turbid by under- 
going an after-fermentation, until the sugar is converted into alcohol and CO,2, which is accom- 
panied by the deposition of some yeast and tartar. If all the sugar is not decomposed—which 
occurs when there is not sufficient nitrogenous matter present to nourish the yeast—a sweet wine 
is obtained. Wine contains 89 to 90 per cent, water, 7 to 8 per cent, alcohol, consisting of ethy- 
lic, propylic, and butylic alcohols. The red color of some wines is due to the coloring matter 
of the skin of the grapes, but if the skins be removed before fermentation, red grapes yield 
white wine. When wine is stored, it develops a fine flavor or bouquet. The characteristic vinous 
odor is due to cenanthic ether. The salts of wine closely resemble the salts of the blood. 
In the preparation of beer the grain is moistened, and allowed to germinate, when the tem- 
perature rises, and the starch (68 per cent, in barley) is changed into sugar. Thus “ malt ” is 
formed, which is dried, and afterwards pulverized, and extracted with water at 70° to 750, the 
watery extract being the “ wort.” Hops are added to wort, and the whole is evaporated, when 
the proteids are coagulated. Hops give beer its bitter taste, and make it keep, while their tan- 
nic acid precipitates any starch that may be present, and clarifies the wort. After being boiled, 
it is cooled rapidly (12° C.); yeast is added, and fermentation goes on rapidly and with con- 
siderable effervescence at io° to 140. Beer contains 75 to 95 per cent, water; alcohol, 2 to 5 
per cent, (porter and ale, to 8 per cent.); C02, 0.1 to 0.8 per cent.; sugar, 2 to 8 per cent.; 
gum, dextrin, 2 to 10 per cent.; the hops yield traces of protein, fat, lactic acid, ammonia com- 
pounds, the salts of the grain and of the hops. In the ash there is a great preponderance of 
phosphoric acid and potash, both of which are of great importance for the formation of blood. 
In 100 parts of ash there are 40.8 potash, 20.0 phosphorus, magnesium phosphate 20, calcium 
phosphate 2.6, silica 16.6 per cent. The formation of blood, muscle, and other tissues from the 
consumption of beer is due to the phosphoric acid and potash, while if too much be taken, the 
potash produces fatigue. 
Condiments are taken with food, partly on account of their taste, and 
partly because they excite secretion. Common salt, in a certain sense, is a 
condiment. We may also include as such many substances of unknown consti- 
tution which act upon the gustatory organs, e. g., dextrin, and substances in the 
crust of bread and in meat which has been roasted. 
236. EQUILIBRIUM OF THE METABOLISM.—By this term is 
meant that, under normal physiological conditions, just as much material is 
absorbed and assimilated from the food as is removed from the body by the ex- 
cretory organs in the form of effete or end-products, the result of the retro- 
gressive tissue-changes. The income must always balance the expenditure; 
wherever a tissue is used up, it must be replaced by the formation of new tissue. 
During the period of growth, the increase of the body corresponds to an in- 
creased formative activity whereby the metabolism of the growing parts of the 
body is 2.5 to 6.3 times greater than that of the parts already formed. Con- 
versely, during senile decay, there is an excess of expenditure from the body. 
Methods.—The normal equilibrium of the metabolism of the body is investigated—(1) By 
determining chemically that the sum of all the substances passing into the body is equal to the 
sum of all the substances given off from it. Thus the C, N, H, O, salts and water of the food, 
and the O inspired, must be equal to the C, N, H, O, salts and water given off in the excreta 
(urine, faeces, air expired, water excreted). (2) The physiological equilibrium is determined 
empirically by observing that the body retains its normal weight with a given diet; so that, by 
simply weighing a person, a physician is enabled to determine exactly the state of convalescence 
of his patient. The tedious process of making an elementary analysis of the metabolic sub- 450 
EQUILIBRIUM OF THE METABOLISM 
[Sec. 236. 
stances was first undertaken in the Munich School by v. Bischoff, v. Voit, v. Pettenkofer, and 
others. 
Circulation of C.—In the circulation of materials the total amount of C 
taken in the food, if the metabolism be in a condition of physiological equi- 
librium, must be equalled by the C in the C02 given off by the lungs and skin 
(90 per cent.), together with the relatively small amount of C in the organic 
excreta of the urine and faeces (10 per cent.) 
Circulation of N.—Nearly all the N taken in with the food is excreted 
within twenty-four hours in the form of urea. A very small amount of nitro- 
genous matter is excreted in the faeces, while the other nitrogenous urinary con- 
stituents (uric acid, kreatinin, etc.) represent about 2 per cent, of N. A trace 
of the N is given off by the breath (§ 124), and a minute proportion in combina- 
tion, in the epidermal scales (50 milligrams daily in the hair and nails), and in 
the sweat. 
Deficit of N.—That nearly all the N taken in the food reappears in the 
urine and faeces, as was stated by v. Voit to be the case in the carnivora and in 
the herbivora, and by v. Ranke in man, is contradicted partly by old and partly 
by new observations, which go to show that the whole of the N cannot be re- 
covered from these excretions, but that on the contrary there is a deficit. 
According to Leo, only 0.55 per cent, of the albumin transformed within the body (assuming 
15 per cent. N in albumin) gives off its N in the form of gaseous N (according to Seegen and 
Nowak 12 times more). In every exact analysis of the metabolism of N this gaseous excretion 
of N must be taken into account. 
The excretion of N after food does not take place regularly from hour to hour, but it in- 
creases at once and distinctly, reaches its maximum in five to six hours, and then gradually falls. 
The same is true of the excretion of S and P ; but in these cases the maximum of excretion is 
reached at the fourth hour. When fat is added to a diet of flesh, the excretion of N and S is 
uniformly distributed over the individual hours of the day (v. Voit and Feder'). 
The nitrogenous constituents in the body during metabolism become poorer in C, and richer 
in N and O. Thus in albumin to 1 atom of N there are 4 atoms C; in gelatin, C; in 
glycocoll, 2 C; in kreatin, C; in uric acid, ifi C; in allantoin, 1 C; in urea, only f2 
atom of C (p. 430). 
Circulation of H and O and Salts.—The H leaves the body chiefly in 
the form of water—a part, however, is in combination in other excrfeta; the 
O is chiefly excreted as C02 and water; a little is given off in combination in 
other excreta; water is given off by evaporation from the lungs and skin, and 
also in the urine and faeces. As H is oxidized to H20, more water is excreted 
than is taken in. Most of the readily soluble salts are given off by the urine ; 
the less soluble salts, especially those of potash, and the insoluble salts, in the 
faeces ; while others are given off in the sweat. Of the sulphur of albumin, 
about one-half is excreted in the sulphur compounds in the urine, and the other 
half in the faeces (taurin) and in the epidermal tissues. 
Every organism has a minimum and a maximum limit of metabolism, 
according to the amount of work done by the body and its weight. If less food 
be given than is necessary to maintain the former, the body loses weight; 
while, if more be given after the maximum limit is reached, the food so given 
is not absorbed, but remains as a floating balance, and is given off with the 
faeces. When food is liberally supplied, and the weight increases, of course the 
minimum limit rises; hence, during the process of “ feeding ” or “ fattening” 
the amount of food necessary is very much greater than in poorly fed animals, 
for the same increase of the body-weight. By continuing the process a condi- 
tion is at last reached in which the digestive organs are just sufficient to main- 
tain the existing condition, but cannot act so as to admit of new additions being 
made to the body-weight (v. Bischoff, v. Voit, v. Pettenkofer'). 
By the term “ luxus consumption ” is meant the direct combustion or Sec. 236.] 
ADEQUATE DIETARY. 
451 
oxidation of the superfluous food-stuff's absorbed by the blood. This, however, 
does not exist. On the contrary, the material in the juices is always being used 
for building up the tissues. The albumin found in the fluids, which everywhere 
permeate the tissues, has been called “ circulating albumin,” and according 
to v. Voit it undergoes decomposition sooner than the organized or “ organic 
albumin ” which forms an integral part of the tissue. According to v. Voit, 
in 24 hours 1 per cent, of the organic and 70 per cent, of the circulating albu- 
min is used up. 
[Liebig taught that the nitrogenous metabolism of the body depended on a corresponding de- 
composition of the proteids of the organs, so that the proteids in the food supplied the place of 
the proteids of the organs thus used up. He called the proteids “ plastic foods ”or“ tissue- 
formers,” while he regarded the fats and carbohydrates as “ respiratory foods,” as he sup- 
posed that they alone were concerned in the evolution of heat. As a matter of fact, experiment 
proved that the N metabolism is to a large extent independent of the proteids of the food. The 
luxus-consumption theory was invented to explain this. It simply means, that proteids taken 
with the food not only replace the amount of proteids which have been decomposed during the 
activity of organs and tissues, but that any excess is immediately consumed without being con- 
verted into tissue, and thus this surplus amount giving rise to heat by being oxidized, to a certain 
extent replaces the fats and carbohydrates. Voit tried to show that nitrogenous metabolism is 
not influenced by the activity of the organism, and that in ordinary conditions only a small 
amount of the organic albumin, i. e., that composing tissues and organs, undergoes decomposition, 
while, owing to the action of the cellular elements of the tissue, a large amount of the circulating 
albumin is split up, so that, under ordinary conditions, the organic albumin is comparatively 
stable. This view, he thought, gained support from a comparison of the urea excreted, for the 
urea may be taken as an index of the N metabolism in well-fed, fasting, and starving animals.] 
[It is highly doubtful, however, whether we can draw a sharp distinction between “ tissue 
proteids ” and “ circulating proteids ” as fulfilling two different functions. Formerly the blood 
was supposed to be the seat of oxidation, but we have seen reason to believe that these processes 
occur in the tissues. This being so, it seems evident that the food does not undergo decomposi- 
tion or katabolic changes until it has been assimilated, or become part and parcel of the living 
tissues, so that the metabolic products are not, as a rule, derived from the food direct, but from 
the activity of the living tissues. If an increased quantity of food betaken, the excretion of waste 
products is’also increased. On Voit’s doctrine of “ tissue proteids” and “circulating proteids,” 
part of the proteid was supposed to pass into the blood, and not to be built up into tissues at all, but 
was oxidized directly in the blood to yield heat only. The theory of “ luxus-consumption ” was 
invented by Voit to account for this supposed process, because it seemed a wasteful expenditure 
of proteids. This theory, however, has found but little favor, as so many facts are against it; 
for the formation of metabolites seems to be essentially a function of living material, viz., the 
living tissues and organs of the body.] 
Quality and Quantity of the Diet for a healthy adult.—As far as his 
organization is concerned, man belongs to the omnivorous animals, i. e., 
those that can live upon a mixed diet. For an adequate diet man requires 
for his existence and to maintain health a mixture of the following four chief 
groups of food-stufls, along with the necessary relishes; none of them must be 
absent from the food for any length of time. They are :— 
1. Water—for an adult in his food and drink, 2700 to 2800 grms. (70 to 
90 oz. daily (§ 229 and § 247, 1). 
[Thirst.—The needs of the economy for water are expressed by the sensation of thirst. The 
sensation of heat and dryness may be confined to the tongue, mouth, and fauces, and indeed 
may be excited by inhaling dry air. This local thirst may be allayed by swallowing water or 
by eating substances which excite the secretion of saliva. More frequently, however, the sensa- 
tion is the expression of a general condition indicating the diminution of water in the tissues; or 
it may be due to excess of saline matters in the blood. In some diseases this sensation is very 
intense, e.g., diabetes. If water be injected into the blood-vessels, or stomach, both the general 
and local thirst are abolished, even although no water enters the mouth.] 
2. Inorganic substances or Salts are an integral part of all tissues, and 
without them the tissues cannot be formed. They occur in ordinary food. 
The addition of too much salt increases the consumption of water, and this in 
turn increases the transformation of N in the body. If an animal be deprived 452 
AVERAGE DIETARIES. 
[Sec. 236. 
of salts, nutrition is interfered with ; food deprived of its lime affects the forma- 
tion of the bones ; deprival of common salt causes albuminuria (247, A, III). 
The alkaline salts serve to neutralize the sulphuric acid formed by the oxidation 
of the sulphur of the proteids. Iron, which is so essential for the formation of 
blood, exists in animals and plants in combination with complex organic bodies. 
Only in times of famine is man driven to eat large quantities of inorganic substances, to extract 
the organic matter mixed therewith. A. v. Humboldt states, in regard to the inhabitants of the 
Orinoco, that they eat a kind of earth which contains innumerable infusoria. 
3. At least one animal or vegetable albuminous body or proteid (§§ 248, 
250). The proteids are required to replace the used-up nitrogenous tissues, 
e. g., for muscles. They contain 15-18 per cent. N. 
The proteids in blood = 20.56 per cent.; muscles, 19.9 per cent.; liver, 11.74 per cent.; 
brain, 8.63 per cent.; blood-plasma, 7.5 per cent.; milk, 3.94 per cent.; lymph, 2.46 per cent. 
According to Pfliiger and Bohland, a youth of full stature, and 62 kilos. [136 lbs.] weight, de- 
composes 89.9 grms. of albumin daily. 
Asparagin, in combination with gelatin, can replace albumin in the food (IVeiske), while 
asparagin alone limits the decomposition of albumin in herbivora but not in carnivora {J. Munk). 
Ammoniacal salts, glycocoll, sarkosin, and benzamid increase with the amount of albumin in the 
body. 
4. At least one fat (§ 251), or a digestible carbohydrate (§ 252). These 
chiefly serve to replace the transformed fats and non-nitrogenous constituents. 
Owing to the large amount of C which they contain, when they undergo oxida- 
tion, they form the chief source of the heat of the body (§ 206). Fats and 
carbohydrates may replace each other in the food, and in inverse proportion 
too, corresponding to the amount of C which each contains. As far as the mere 
evolution of heat is concerned, 100 parts of fat = 256 of grape-sugar = 234 of 
cane-sugar = 221 of dry starch (Rubner). A man consumes 210 grms. fat daily. 
[5. Every proper diet ought to have a certain degree of sapidity or flavor. The substances 
which give this are not useful in the evolution of energy or building up the tissues, but they 
stimulate the nervous system and excite secretion. They are called “ Genussmittel ” (means of 
enjoying food) by the Germans, but we have no exact equivalent for this word in English, 
though the articles themselves are included under our expression “ condiments.” These sub- 
stances are the aromatic matter in roast meat (osmasome), tea, vinegar, salt, mustard, pepper, 
etc.] 
[Condition of Diet for Health.—In an adequate diet, not only (1) should 
the total quantity of food be sufficient and not more than sufficient, but (2) the 
constituents should exist in proper proportions, (3) be digestible, and (4) the 
whole should be in good condition, wholesome, and not adulterated with any 
substance prejudicial to health.] 
With regard to the relative proportions of the various kinds of food which 
ought to be taken, experience has shown that the diet best suited for the body 
must contain 1 part of nitrogenous foods to f/2 or, at most, 4 y2 of the non-nitro- 
genous. Looking at.ordinary foods from this point of view, we see how far they 
correspond to this requirement, and how several substances may be combined 
to produce a satisfactory diet. 
I. 
Veal, .... 
Nit. Non-Nit. 
. IP I 
2. 
Hare’s flesh, . 
. io 
2 
3- 
Beef, .... 
. IO 
17 
4- 
Lentils, . . . 
. IO 
21 
5- 
Beans, . . . 
. io 
22 
6. 
Peas, .... 
. IO 
23 
7- 
Mutton, . . . 
. IO 
27 
Nit. Non-Nit, 
8. 
Pork, . . . io 
30 
9- 
Cow’s milk, io 
30 
IO. 
Human milk, io 
37 
11. 
Wheaten 
flour, . . io 
46 
12. 
Oat-meal, . io 
5o 
13- 
Rye-meal, . io 
57 
Nit. Non-Nit. 
I4. 
Barlev-meal, 
IO 
57 
I5- 
White 
potatoes, 
. IO 
86 
16. 
Blue “ 
. IO 
115 
17- 
Rice, . . 
. IO 
123 
18. 
Buckwheat- 
meal, 
. IO 
130 
An examination of this table shows that, in addition to human milk, wheat-flour has the right 
proportion of nitrogenous to non-nitrogenous substances. A man who tries to nourish himself 
on beef alone commits as great a mistake as the one who would feed himself on potatoes alone. Sec. 236.] 
COMPOSITION OF FOODS. 
453 
Experience has taught people that man may live upon milk and eggs, but that in addition to 
flesh we must eat bread or potatoes, while pulses require fat or bacon. 
The diet varies with the climate and with the season of the year. As 
the organism must produce more heat in cold latitudes, the inhabitants of 
northern climates must eat more non-nitrogenous foods, such as fats and sugars 
or starches, which, on account of the large amount of C they contain, are 
admirably adapted for producing heat (§ 214, I, 4). 
Animal Foods. 
Water. 
Proteids. 
Albuminoids. 
N-free org. bodies. 
Salts. 
Beef. 
Pork. 
Fowl. 
Fish. 
Egg. 
Cow’s 
milk. 
Human 
milk. 
Vegetable Foods. 
Water. 
Proteids. 
Digestible. 
N-free organic bodies. 
Non-digestible. 
Salts. 
Wheaten- 
bread. 
Peas. 
Rice. 
Potatoes. 
White' 
Turnip.' 
Cauli-r 
flower.[ 
Beer.' 
Fig. 293. 
The graphic representation of the composition of foods (fig. 293) shows the 
relative proportions of the most important food-stuffs, and how they vary from 
the standard of 1 nitrogenous to 3y2 or 4non-nitrogenous. 
The absolute amount of food-stuffs required by an adult in twenty-four 
hours depends upon a variety of conditions. As the food represents thechemi- AMOUNT OF FOOD REQUIRED DAILY. 
[Sec. 236. 
cal reservoir of potential energy, from which the kinetic energy (in its various 
forms) and the heat of the body are obtained, the absolute amount of food must 
be increased when the body loses more heat, as in winter, and when more mus- 
cular activity (work) is accomplished. Asa general rule, an adult requires daily 
130 grams proteids, 84 grams fats, 404 grams carbohydrates, and 30 
grams salts. 
A Healthy Adult requires in 24 Hours of water-free solids :— 
Food in Grams. 
At Rest 
{Playfair). 
Moderate 
Work 
(Mole schott). 
Laborious Work. 
{Playfair). 
(w. Pettenkofer 
and v. Voit). 
Proteids, 
70.87 
130 
I55-92 
137 
Fats, 
28.35 
84 
70.87 
117 
Carbohydrates (Sugar, Starch, etc.), 
310.20 
404 
597-50 
352 
Salts, 
I4.OO 
30 
40.00 
40 
[When we record these numbers in ounces we get the following results as 
water-free solids required by an average man (Parkes) :— 
At Rest. 
Ordinary Work. 
Laborious Work. 
Proteids, 
2-5 
4.6 
6 to 7 
Fats, 
1.0 
3-0 
3.5 to 4.5 
Carbohydrates, 
12.0 
14.4 
16 to 18 
Salts, 
o-5 
1.0 
1.2 tO 1-5 
Total water-free food, 
16.o 
23.0 
26.7 to 31.0 
During ordinary work the proportion is about:— 
Proteids 1 : fats 0.6 : carbohydrates 3.0, 
i. e., 1 nitrogenous to 3.6 non-nitrogenous.] 
[In a diet for ordinary work (23 oz. of dry solids) a man takes about part 
of his own weight daily; ordinary food, however, as it is consumed, contains 
between 50 and 60 per cent, of water ; if we add this proportion of water to the 
actually dry food, we get 48 to 60 oz. of ordinary food (exclusive of liquids). 
But we consume 50 to 80 oz. of water in some liquid form, making the total 
amount of water 70 to 90 oz (.Parkes).] 
The following tables show the elementary composition of the income and 
expenditure: — 
An Adult doing a Moderate Amount of Work takes in:— 
C. 
H. 
N. 
0. 
120 grams albumin, containing 
90 “ fats, “ ...... 
330 “ starch, “ 
64.18 
70.20 
146.82 
8.60 
IO.26 
20.33 
18.88 
28.34 
9-54 
162.85 
281.20 
39-19 
18.88 
200.73 
Add. 744.11 grm. O from the air by respiration. 
“ 2818 “ h2o. 
“ 32 “ Inorganic compounds (salts). 
The whole is equal to kilos. [7 lbs.], i. e., about of the body-weight; 
so that about 6 per cent, of the water, about 6 per cent, of the fat, about 1 per 
cent, albumin, and about 0.4 per cent, of the salts of the body, are daily trans- 
formed within the organism. Sec. 236.] 
INFLUENCE OF WORK ON METABOLISM. 
455 
Water. 
C. 
H. 
N. 
0. 
By respiration, 
33° 
248.8 
? 
65115 
Perspiration, 
660 
2.6 
7.2 
Urine, . 
X700 
9.8 
3-3 
15-8 
11.1 
Fseces, 
128 
20.0 
3-0 
3-o 
12.0 
2818 
28l.2 
6-3 
18.8 
681.45 
An Adult doing a Moderate Amount of Work gives off in grams:— 
Add to this (besides 2818 grams water as drink) 296 grams water formed in the body by the 
oxidation of H. These 296 grams of water contain 34.89 grms. H, and 263.41 grms. O; 26 
grms. of salts are given off in the urine, and 6 by the faeces. 96.5 grms. of proteid (= 1.46 grm. 
per kilo.) are used up by a resting adult in twenty four hours ; but while working 107.6 grms. 
are used. Nominally 2.3 times as much fat as albumin are used up. 
The investigations of the Munich School have shown that the following numbers represent 
the minimum amount of food necessary for different ages :— 
Age. 
Nitrogenous. 
Fat. 
Carbohydrates. 
Child until year, 
20—36 grms. 
30-45 grms. 
60-90 grms. 
“ from 6 to 15 years, 
70-80 “ 
37-50 *• 
250-4OO “ 
Man (moderate work), 
118 “ 
56 “ 
500 “ 
Woman “ 
92 “ 
44 “ 
400 “ 
Old man, 
100 “ 
68 “ 
350 “ 
Old woman 
80 “ 
50 “ 
260 “ 
Small animals have a more lively metabolism than large ones. In small animals the decom- 
position of albumin per unit weight of body is greater than in large animals (v. Voit). Small 
animals as a rule consume more proteid than larger ones, because they generally have less bodily 
fat [Rubtier). 
[Influence of Work on the Metabolism.—When muscular work is 
done in the body, there is a much greater decomposition of non-nitrogenous 
substances in the body, the carbohydrates of muscle and the fats of the body 
are used up, and after they are largely decomposed the muscular tissue itself is 
used up. Pettenkofer and Voit found in an individual weighing 70 kilos (147 
lbs.) that his diet (mixed diet) at rest was— 
Proteids, 137 grams 
Fats, X17 “ 
Carbohydrates, 352 “ 
Containing 19.5 grams N. 
and 315.5 “ C. 
and he excreted— 
Water, 2262 “ 
Grams N. 
Grams C. 
Grams Water. 
By the urine, 
17.4 
12.6 
II94 
“ faeces, 
2.1 
14-5 
94 
“ respiration, 
3°9.2 
1412 
Total, 
19-5 
336.3 
2700 c c. 
So that his body was in N — equilibrium and he gave off also 438 grams of 
water and 20.8 grams of C = 28 grams of fat. When, however, he did a 
large amount of work he took the same amount of proteids and carbohydrates, 
but nearly double as much fat (§ 294).] 
Relation of N to C in Foods and Dietaries.—In most of the ordinary 
articles of diet, nitrogenous and non-nitrogenous substances are present, but in 
very varying proportion, in the different foods. Man requires that these shall 
be in the proportion of 1 : to 1 : 4/4- If food be taken in which this 456 
HUNGER AND STARVATION. 
[Sec. 236. 
proportion is not observed, in order to obtain the necessary amount of that 
substance which is contained in too small proportion in his food, he must con- 
sume far too much food. In order to obtain the 130 grams of proteids 
necessary a person must use— 
Cheese, ; . . . 388 grms. 
Lentils, .... 491 “ 
Peas, 582 “ 
Beef, 614 grms. 
Eggs 968 “ 
Wheat-bread, . 1444 “ 
Rice, 2562 grms. 
Rye-bread, . . 2875 “ 
Potatoes, . . 10,000 “ 
provided he were to take only one of these substances as food ; so that if a work- 
man were to live on potatoes alone, in order to get the necessary amount of N 
he would have to consume an altogether excessive amount of this kind of food. 
To obtain the 448 grams of carbohydrates, or the equivalent amount of 
fat necessary to support him, a man must eat— 
Rice, 572 grms. 
Wheat-bread, . 625 “ 
Lentils, .... 806 “ 
Peas, 819 grms. 
Eggs, 902 “ 
Rye-bread, . . 930 “ 
Cheese 2011 grms. 
Potatoes, . . . 2039 “ 
Beef, 2261 “ 
so that if he were to live upon cheese or flesh alone, he would require to eat an 
enormous amount of these substances. 
In the case of herbivora, the proportion of nitrogenous to non-nitrogenous food necessary is 
i of the former to 8 or 9 parts of the latter. 
Lastly, all the nutrient material is not necessarily digested and absorbed in 
the intestinal tract; on the contrary, there always remains an undigested or un- 
used residue which is evacuated with the faeces. The yield of dry substance, 
with rice as a food, is 4.1 per cent.; white bread, 4.5; flesh, 5.2; egg, 5.2; 
milk, 9; potatoes, 9.4; peas, 11.8; beans, 18.3; and black bread, 15 
([Prausnitz) (§ 180, 2). 
237. HUNGER AND STARVATION. —If a warm-blooded animal 
be deprived of all food, it must, in order to maintain the temperature of its 
body and to produce the necessary amount of mechanical work, transform and 
utilize the potential energy of the constituents of its own body. The result is that 
its body-weight diminishes from day to day, until death occurs from starvation. 
The following table, from Bidder and Schmidt, shows the amount in grams of the different 
excreta in the case of a starved cat:— 
Day. 
Body- 
weight. 
Water 
taken. 
Urine. 
Urea. | 
Inorganic 
Substances 
in Urine. 
Dry 
Faeces. 
Expired C. 
Water in 
Urine 
and Faeces. 
I. 
2464 
98 
7-9 
*•3 
1.2 
13-9 
9I.4 
2. 
2297 
ir-5 
54 
5-3 
0.8 
1.2 
I2.9 
5°-5 
3- 
2210 
45 
4.2 
0.7 
I.I 
13 
42.9 
4- 
2172 
68.2 
45 
3-8 
0.7 
I.I 
I2.3 
43 
5- 
2129 
55 
4-7 
0.7 
1-7 
11-9 
54-i 
6. 
2024 
44 
4-3 
0.6 
0.6 
11.6 
41.1 
7- 
1946 
. . 
40 
3-8 
o-5 
0.7 
11 
37-5 
8- 
i873 
42 
3-9 
0.6 
1.1 
10.6 
40 
9- 
1782 
15-2 
42 
4 
0-5 
i-7 
10.6 
41.4 
IO. 
1717 
35 
3-3 
0.4 
i-3 
io-5 
34 
ii. 
1695 
4 
32 
2.9 
0-5 
1.1 
10.2 
3°-9 
12. 
1634 
22.5 
3° 
2.7 
0.4 
1.1 
10.3 
29.6 
J3- 
1570 
7-i 
40 
3-4 
o-5 
0.4 
10.1 
36.6 
14. 
ISI8 
41 
3-4 
o-5 
o-3 
97 
38 
15- 
H34 
41 
2.9 
0.4 
0.3 
9.4 
384 
16. 
1389 
48 
3 
0.4 
0.2 
8.8 
45-5 
i7- 
1335 
28 
i .6 
0.2 
o-3 
7.8 
26.6 
18. 
1267 
13 
0.7 : 
0.1 
o-3 
6.1 
12.9 
! -”97 
13*5 
773 
65 8 , 
9.8 
157 
199.7 
7344 Sec. 237.] 
LOSSES DURING STARVATION. 
457 
The cat lost 1197 grms. in weight before it died, and this amount is appor- 
tioned in the following way: 204.43 grms. (— 17.01 percent.) loss of albu- 
min ; 132.75 grms. (= 11.05 Per cent.) loss of fat; 863.82 grms. loss of water 
(= 71-91 per cent, of the total body-weight lost). 
Methods.—In order to investigate the condition of inanition it is necessary—(1) to weigh 
the animal daily; (2) to estimate daily all the C and N given off from the body in the faeces, 
urine, and expired air. The N and C, of course, can only be obtained from the decomposition 
of tissues containing them. 
Amongst the general phenomena of inanition, it is found that strong well-nourished dogs 
die after 4 weeks, man after 21 to 24 days—(6 melancholics who took water died after 41 days); 
small mammals and birds 9 days,' and frogs 9 months. Vigorous adults die when they lose 
of their body-weight, but young individuals die much sooner than adults. The symptoms are 
obvious : The mouth is dry, the walls of the alimentary canal become thin, and the digestive 
secretions cease to be formed; pulse-beats and respirations are fewer; urine very acid from the 
presence of an increased amount of sulphuric and phosphoric acids, whilst the chlorine com- 
pounds rapidly diminish and almost disappear. The blood contains less water and the plasma 
less albumin, the gall-bladder is distended, which indicates a continuous decomposition of blood- 
corpuscles within the liver. The liver is small and very dark-colored, the muscles are very 
brittle and dry, so that there is a great muscular weakness, and death occurs with the signs of 
great depression and coma. 
Metabolism during Inanition.—The relations of the metabolism are 
given in the foregoing table; the diminution in the excretion of urea is much 
greater than that of C02, which is due to a larger amount of fats than proteids 
being decomposed. According to the calculation, there is daily a tolerably 
constant amount of fat used up, while, as starvation continues, the proteids are 
decomposed in much smaller amounts from day to day, although the drinking 
of water accelerates their decomposition. 
[Excretion of Urea during Inanition.—The above data shows that the urea excreted falls 
decidedly during the first few days, then it falls to a minimum, and for several days it remains 
pretty constant, and then it quickly falls, when the symptoms of approaching death supervene. 
Sometimes a rise in the quantity excreted takes place when all the fats are used up.] 
Loss of Weight of Organs.—It is of importance to determine to what 
extent the individual organs and tissues lose weight; some undergo simple loss 
of weight, e. g., the bones; the fat undergoes very considerable and rapid 
decomposition, while other organs, as the heart, undergo little change, because 
they seem to be able to nourish themselves from the transformation products of 
other tissues. 
Per cent. 
Per cent, of 
originally 
the total loss of 
present. 
body-weight. 
I. 
Fat, .... 
• 97 
26.2 
2. 
Spleen, . . 
66.7 
0.6 
3- 
Liver, . . . 
• 53-7 
4.8 
4- 
Testicles, 
40.6 
0.1 
5- 
Muscles, . . 
- 30.5 
42.2 
6. 
Blood, . . . 
• 37-o 
3-7 
7- 
Kidneys, . . 
• 25.9 
0.6 
8. 
Skin, . . . 
20 6 
8.8 
9- 
Intestine, 
18.0 
2.0 
A starving cat, according to v. Voit, lost— 
Per cent. 
Per cent, of 
originally 
the total loss of 
present. 
body-weight. 
IO. 
Lungs, .... 
177 
o-3 
II. 
Pancreas, . . . 
17.O 
0.1 
12. 
Bones, .... 
I3-9 
5-4 
13- 
Central Nervous 
system, . . . 
3-8 
0.1 
14. 
Heart, .... 
2.6 
0.02 
15- 
Total loss of the 
— 
— 
rest of the 
body,.... 
36.8 
5° 
There is a very important difference according as the animals before inani- 
tion have been fed freely on flesh and fat [/. e., if they have a surplus store of 
food within themselves], or as they have merely had a subsistence diet. Well- 
fed animals lose weight much more rapidly during the first few days than on 
the later days. V. Voit thinks that the albumin derived from the excess of 
food occurs in a state of loose combination in a body as “ circulating ” or 
“ storage-albumin," so that during hunger it must decompose more rapidly and 458 
[Sec. 237. 
METABOLISM ON A FLESH DIET. 
to a greater extent than the “organic albumin,” which forms an integral 
part of the tissues (§ 236). Further, in fat individuals, the decomposition of 
fat is much greater than in slender persons. 
[Comparative.—Cold-blooded animals live much longer without food than mammals or 
birds. Snakes may live half a year and frogs nearly a year without food. Dogs may survive for 
4 weeks, cats and horses for 3 weeks without food or drink, especially if they are quiet, and not 
called upon to make any exertion. It is remarkable that small mammals, guinea-pigs and rats 
survive only for a few days (3—9) : rabbits even 19 days. If water be given, however, the animals 
survive longer, dogs for 4 weeks, man 4 or 5 weeks, and the dog even 9 weeks. Quite young 
animals die quicker than adults yMunk). As to a human being many factors have to be taken 
into account,—age (old persons withstand withdrawal of food best), amount of muscular work 
done, the condition of the atmosphere, whether it is moist and saturated with watery vapor or 
otherwise; temperature of the surroundings, etc. As a rule, complete abstinence from food and 
drink cannot be supported for more than 8-10 days, although there are exceptional cases on 
record where life has been sustained for forty days without food, water, however, being taken. 
Total deprivation of food in man usually causes death in the third week.] 
Zuntz and Lehmann, experimenting on the fasting man Cetti, found that the consumption of O 
and the production of C02 with reference to the unit of body-weight very rapidly reached a mini- 
mum, under which it did not fall, although the person continued to starve. As a mean the O 
consumed on the 3d to 6th day of starvation = 4.65 c.c. per minute per kilo. The respiratory 
metabolism diminished very slowly, but not in proportion to the loss of body-weight. At the 
beginning of starvation theC02 fell more rapidly than the O consumed. The respiratory quotient 
was 0.67. The urea diminished from 1-10 hunger days from 29 to 20 grams. 
238. METABOLISM ON A PURELY FLESH DIET .—A man is 
not able to maintain his metabolism in equilibrium on a purely flesh diet; if he 
were compelled to live on such a diet, he would succumb. The reason is obvi- 
ous. In beef the proportion of nitrogenous to non-nitrogenous elementary con- 
stituents of food is 1 : 1.7 (p. 452). A healthy person excretes 380 grams [8 
to 9 oz.] of carbon in the form of C02, in the expired air, and in the urine and 
faeces. If a man is to obtain 280 grams C from a flesh diet he must consume— 
digest and assimilate—more than 2 kilos. [4.4 lbs.] of beef in twenty-four hours. 
But our digestive organs are unequal to this task for any length of time. The 
person is soon obliged to take less beef, which would necessitate the using of 
his own tissues, at first the fatty parts, and afterwards the proteid substances. 
A carnivorous animal (dog), whose digestive apparatus, being specially adapted for the 
digestion of flesh—a short intestine and powerfully active digestive fluids—can only maintain its 
metabolism in a state of equilibrium when fed on a flesh diet free from fat, provided its body 
is already well supplied with fat, and is muscular. It consumes to part of the weight of its 
body in flesh, so that the excretion of urea increases enormously. If it eats a larger amount, it 
may “put on flesh, when of course it requires more to maintain itself in this condition, until the 
limit of its digestive activity is reached. If a well-nourished dog is fed on less than to of 
its body-weight of flesh, it uses part of its own fat and muscle, gradually diminishes in weight, 
and ultimately succumbs. Poorly fed, non-muscular dogs are unable from the very beginning to 
maintain their metabolism in equilibrium for any length of time on a purely flesh diet, as they 
must eat so large a quantity of flesh that their digestive organs cannot digest it. The herbivora 
cannot live upon flesh food, as their digestive apparatus is adapted solely for the digestion of 
vegetable food. 
[The proteid metabolism depends (i)on the amount of proteids ingested, 
for the great mass of these becomes changed into circulating albumin ; (2) upon 
the previous condition of nutrition of the organism, for we know that a certain 
amount of proteid may produce very different results in the same individual 
when he is in good health, and when he has suffered from some exhausting dis- 
ease. (3) The use of other foods, e. g., fats and carbohydrates. If a certain 
amount of fat be added to a diet of flesh, much less flesh is required, so that the 
N metabolism is reduced by fat. This is spoken of as the “ albumin-sparing 
action of fats.”] 
Exactly the same result occurs with other forms of proteids, as with flesh. 
It has been proved that gelatin may to a certain extent replace proteids in the Sec. 238.] 
DIET OF FATS OR CARBOHYDRATES. 
459 
food, in the proportion of 2 of gelatin to 1 of albumin. The carnivora, which 
can maintain their metabolism in equilibrium by eating a large amount of flesh, 
can do so with less flesh when gelatin is added to their food. A diet of gelatin 
alone, which produces much urea, is not sufficient for this purpose, and animals 
soon lose their appetite for this kind of food. 
[Gelatin.—Voit has shown that gelatin readily undergoes metabolism in the body and forms 
urea, and if a small quantity be taken, it is completely and rapidly metabolized. When admin- 
istered it acts just like fats and carbohydrates as an “ albumin-sparing ” substance. It seems 
that gelatin is not available directly for the growth and repair of tissues.] Owing to the great 
solubility of gelatin, its value as a food used to be greatly discussed. The addition of gelatin in 
the form of calf’s-foot jelly is recommended to invalids. [When a large amount of gelatin is 
given as food, owing to the large and rapid excretion of urea, the latter excites diuresis.] When 
chondrin is given along with flesh for a time, grape-sugar is found in the urine. 
[The Metabolism of Peptones.—Most of the proteids absorbed into the 
blood are previously converted into peptones by the digestive juices. It has 
been asserted, more especially by Briicke, that some albumin is absorbed un- 
changed (§ 192, 4), and that only this is capable of forming organic albumin, 
while the peptones, after undergoing a reconversion into albumin as they pass 
through the intestinal wall, undergo decomposition as such.] 
239. A DIET OF FAT or OF CARBOHYDRATES.—If fat alone 
be given as a food, the animal lives but a short time. The animal so fed ex- 
cretes even less urea than when it is starving; so that the consumption of fat 
limits the decomposition of the animal’s own proteids. As fat is easily oxidized 
in the body, it yields heat chiefly, and becomes sooner oxidized than the nitro- 
genous proteids which are oxidized with more difficulty. If the amount of fat 
taken be very large, all the C of the fat does not reappear, e.g., in the C02 of 
the expired air; so that the body must acquire fat, whilst at the same time it 
decomposes proteids. The animal thus becomes poorer in proteids and richer 
in fats at the same time. 
[The metabolism of fats is not dependent on the amount of fats taken with 
the food. 1. It is largely influenced by work, i. e., by the activity of the 
tissues, and in fact with muscular work C02 is excreted in greatly increased 
amount (§ 126, 6). 2. By the temperature of the surroundings, as more C02 
is produced in the cold (§ 214, 2), and far more fatty foods are required in high 
latitudes. In their action on the organism, proteids and fats so far oppose each 
other, as the former increase the waste, and therefore oxidation, while the latter 
diminish it, probably by affecting the metabolic activity of the cells themselves 
(Bauer). Asa matter of fact, fat animals or persons bear starvation better than 
spare individuals. In the latter, the small store of fat is soon used up, afid then 
the albumin is rapidly decomposed. For the same reason corpulent persons are 
very apt to become still more so, even on a very moderate diet.] 
When carbohydrates alone are given, they must first be converted by di- 
gestion into sugar. The result of such feeding coincides pretty nearly with feed- 
ing with fat alone. But the sugar is more easily burned or oxidized within the 
body than the fat, and 17 parts of carbohydrate are equal to 10 parts of fat. 
Thus the diet of carbohydrates limits the excretion of urea more readily than a 
purely fat diet. The animals lose flesh, and appear even to use up part of their 
own fat. 
[The metabolism of carbohydrates also serves to diminish the proteid 
metabolism, as they are rapidly burned up, and thus “spare ” or “ economize ” 
the circulating albumin. But Pettenkofer and Voit assert that they are rapidly 
destroyed in the body, even when given in large amount, so that they differ 
from fats in this respect. They are more easily oxidized than fats, so that they 
are always consumed first in a diet of carbohydrates and fat. By being con- 
sumed they protect the proteids and fats from consumption.] 460 
[Sec. 239. 
STRUCTURE OF ADIPOSE TISSUE. 
The direct introduction of grape- and cane-sugar into the blood does not increase the amount 
of O used, but the amount of C02 is increased. [The doctrine of Liebig, that the oxygen taken 
in is a measure of the metabolic processes, is refuted by these and other experiments. It would 
seem that fat is not directly oxidized by O, but that it is split up into other simpler compounds 
which are slowly and gradually oxidized; in fact, fat may lessen the.amount of O taken in, as it 
diminishes waste.] 
240. FLESH AND FAT, or FLESH AND CARBOHY- 
DRATES.—An amount of flesh equal to to -j- of the weight of the body 
is required to nourish a dog, which is fed on a purely flesh diet; if the necessary 
amount of fat or carbohydrates be added to the diet, a smaller quantity of flesh 
is required ( v. Voit). For 100 parts of fat added to the flesh diet, 245 parts of 
dry flesh or 227 of syntonin can be dispensed with. If instead of fats carbo- 
hydrates are added, then 100 parts of fat = 230 to 250 of the latter (Rubner). 
When the amount of flesh is insufficient, the addition of fat or carbohydrates to 
the food always limits the decomposition of the animal’s own substance. Lastly, 
when too much flesh is given along with these substances, the weight of the 
body increases more with them than without them. Under these circumstances, 
the animal’s body puts on more fat than flesh. The consumption of O in the 
body is regulated by the mixture of flesh and non-nitrogenous substances, rising 
and falling with the amount of flesh consumed. It is remarkable that more O 
is consumed when a given amount of flesh is taken, than when the same amount 
of fle-h is taken with the addition of fat. 
It seems that, instead of fat, the corresponding amount of fatty acids has the same effect on 
the metabolism. [If a dog be fed with fatty acids and a sufficient amount of proteid, no fatty 
acids are found in the chyle, while fat is formed synthetically, the glycerin for the latter probably 
being produced in the body (§ 192).] They are absorbed as an emulsion just like the fats. 
When so absorbed, they seem to be reconverted into fats in their passage from the intestine to the 
thoracic duct, perhaps by the action of the epithelium of the villi. [Glycerin in small doses has 
no effect on the metabolism of proteid, but in large doses it increases it. It is consumed in the 
body, as shown by experiments on the respiratory products, and it prevents a certain amount of 
fat from being used up. About 20 per cent, is excreted in the urine (Arnschink). The admin- 
istration of glycerin to rabbits leads to accumulation of sugar in the liver (p. 326), but, according 
to Ransom, it inhibits the formation of sugar in the liver, and thus leads to the accumulation of 
sugar in the liver. The glycosuria that follows injury to the floor of the fourth ventricle is pre- 
vented by glycerin, and so is the post-?nortem change of glycogen into sugar.] 
241. STRUCTURE OF ADIPOSE TISSUE AND ORIGIN OF 
FAT IN THE BODY.—[This tissue is widely distributed in the body ; it 
occurs in subcutaneous tissue as the “ panniculus adiposus,” around many or- 
gans, such as the kidney, and especially in stall-fed animals around the pericar- 
dium, in the omentum, under the epicardium, in the yellow marrow of bones, 
orbital cavities, etc. None is found within the cranium, or in the subcutaneous 
tissue of the eyelids. 
It is a great storehouse of reserve material, and its bulk fluctuates greatly. It 
is readily formed, and it may be very quickly absorbed again should the needs 
of the economy require it. 
Adipose tissue, when examined microscopically, consists of little bladders or 
vesicles filled with fat. The vesicles may be spherical or polyhedral from mutual 
pressure. Each cell is 40-70 /a in diameter and consists of a thin transparent 
cell-wall or envelope, enclosing a large globule of fat, which almost completely 
fills the cell (fig. 294). At the side, between the cell-wall and the oil-globule, 
lies the nucleus, surrounded by a small quantity of protoplasm. From the 
nucleus occupying this eccentric position, and when the whole cell is seen from 
the side, it presents an appearance somewhat like a signet-ring. A thin shell of 
protoplasm extends round the cell between the envelope and the globule of oil. 
A fat-cell, therefore, may be regarded as an altered connective-tissue corpuscle, 
which has become vacuolated, and in the single large vacuole fat is formed. The Sec. 241.] 
EFFECT OF REAGENTS ON FAT-CELLS. 
461 
fat-cells are arranged in lobules, and the cells in each lobule are kept together 
by a small quantity of connective-tissue. The lobules form larger polygonal 
lobes. At least one artery and two veins are connected with a lobule, and 
around the fat-cells is a plexus of capillaries, so that in its general arrangement 
it assumes a glandular type.] 
[Effect of Reagents on Fat-cells.—The envelopes are readily brought 
into evidence by dissolving out the fat by means of hot ether or alcohol. The 
nucleus is stained by carmine or logwood, while the fat itself is blackened by 
osmic acid. Sometimes after fat-cells are acted on by glycerin, or alcohol, or 
merely after they are removed from the body, they exhibit a radiate arrange- 
ment of crystals of margarine (fig. 295).] 
[Development of Fat-cells.—Apparently they are derived from modified 
connective-tissue corpuscles. The corpuscles at first are somewhat spherical, 
and in their protoplasm small droplets of oil are formed. Gradually these drop- 
lets become larger and more numerous, the cell at the same time enlarging, and 
by and by the droplets run together to form one large globule of oil, so that the 
Fig. 294. 
Fig. 295. 
Fat-cells from rabbit. X 340. 
Fat-cells with margarine crystals. 
remains of the protoplasm and the nucleus are pushed to one side immediately 
under the cell-wall.] 
[Effect of Starvation.—Starvation rapidly reduces the amount of fat in the 
body. The fat-cells gradually and rapidly yield up their fat, and their envel- 
opes remain, diminished, however, in size. The protoplasm may grow some- 
what, and in it appear vacuoles filled with a fluid, hence these now altered cells 
are called “serous fat-cells.”] 
I. Part of the fat of the body is derived directly from the fat of the food, 
i. e., it is absorbed and deposited in the tissues. This is shown by the fact 
that, with a diet containing a small amount of albumin, the addition of more fat 
causes the deposition of a larger amount of fat in the body (v. Voit, Hofmann). 
[Hofmann starved a fat dog for 30 days until all its fat was used up. He fed it on lard and 
a little albumin for five days and then killed it. In 5 days it absorbed 1854 grms. of fat and 254 
grms. of albumin. It added to its body 1353 grms. of fat; but this amount could not be formed 
from the proteids of the food, and therefore the fat must have come from the fat of the food. 
Pettenkofer and Voit arrived at the same result in another way. They fed dogs on flesh and 
much fat, and by their respiration-apparatus estimated the gaseous income and expenditure 
(§ 122). All the N taken in reappeared in the excreta, but not all the C. The amount of C 
retained was very large, therefore a non-nitrogenous residue must have been laid up in the body, 462 
[Sec. 241. 
FORMATION OF FAT. 
and it could only be fat, as this was the only substance found in large amount in the body. They 
estimated the possible amount of fat that could be formed from the proteids, and found that the 
amount stored up was far greater than this; so that the fat of the food must have been stored up 
in the tissues.] 
Lebedeff found that dogs, which were starved for a month, so as to get rid of all their own 
fat, on being fed with linseed oil, or mutton suet and flesh, had these fats restored to their tissues. 
These fats, therefore, must have been absorbed and deposited. J. Munk found the same on 
feeding animals with rape-seed oil. Fatty acids may also contribute to the formation of fats, as 
glycerin when formed in the body must be stored up during metabolism (J. Munk). 
Fatty acids may contribute to the formation of fats by union with the glycerin of the body 
during the metabolism (p. 378). 
II. A second source is the new formation of fats from albuminous 
bodies. In the case of the formation of fat from proteids, which may yield 
11 per cent, of fat (according to Henneberg 100 parts of dry albumin can form 
51.5 of fats, together with 33.45 urea, and 27.4 C02), these proteids split up 
into a non-nitrogenous and a nitrogenous atomic compound. The former, 
provided in a diet containing much albumin, it is not completely oxidized into 
C02 and H20, is the'substance from which the fat is formed—the latter leaves 
the body oxidized chiefly to the stage of urea. 
Examples.—That fats are formed from proteids is shown by the following: 1. A cow 
which produces 1 lb. of butter daily does not take nearly this amount of fatty matter in its food, 
so that the fat would appear to be formed from vegetable proteids. 2. Carnivora giving suck, 
when fed on plenty of flesh and so??ie fat, yield milk rich in fat. 3. Dogs fed with plenty of 
flesh and some fat, add more fat to their bodies than the fat contained in the food. 4. Fatty 
degeneration, e. g., of nerve and muscle, is due to a decomposition of proteids. 5. The transfor- 
mation of entire bodies, e. g., such as have lain for a long time surrounded with water, into a 
mass consisting almost entirely of palmitic acid or adipocere is also a proof of the transforma- 
tion of part of the proteids into fats. 6. Fungi are also able to form fat from albumin during 
their growth. [7. In starving dogs, Bauer estimated the N and C02 given off, and O taken in, 
and then slowly poisoned them with phosphorus, and he found that the excretion of N was in- 
creased twofold, while the excretion of C02 and the absorption of O were diminished one-half. 
Therefore from a large amount of nitrogenous tissue, a nitrogenous body and a small amount of 
a carbonaceous compound were excreted, while a large amount of a non-nitrogenous residue was 
retained unconsumed. There was fatty degeneration of all the organs, the fat being derived from 
the non-nitrogenous part of the proteid. The same obtains with arsenic and antimony.] 
Fats not merely absorbed.—Experiments which go to show that the fat of animals, during 
the fattening process, is not absorbed as such, from the food, are : 1. Fattening occurs with flesh 
and soaps; it is most improbable that the soaps are transformed into neutral fats by taking up 
glycerin and giving up alkali. 2. If a lean dog be fed with flesh and palmitin- and stearin- 
soda-soap, the fat of its body contains, in addition to palmitin and stearin, olein fat, so that the 
last must be formed by the organism from the proteids of the flesh. Further, Ssubotin found 
that when a lean dog was fed on lean meat and spermaceti-fat, a very small amount of the latter 
was found in the fat of the animal. Although these experiments show that the fat of the body 
must be formed from the decomposition of proteids, they do not prove that all the fat arises in 
and that none of it is absorbed and redeposited ($ 241,1). 
III. From experiments upon fattening warm-blooded animals (pig, goose, 
dog) however, Lawes and Gilbert, Lehmann, Heiden, v. Wolff, and others, 
think they are entitled to conclude that the carbohydrates absorbed are 
directly concerned in the formation of fats, a view which is supported by Hen- 
neberg, B. Schulze, and Soxhlet. Pigs were fed by Lawes and Gilbert on a 
large excess of carbohydrates, with very little fat and albumin. In the forma- 
tion of fat, the converse process takes place, as compared with the formation 
of glycogen from proteid (§ 174). The molecular group CH.HO, is by reduc- 
tion changed into CH2 (Pfliiger). Suppose the carbohydrate (like albumin) 
to be decomposed into fat, C02 and H20, then 100 grms. starch ( =111.1 grms. 
sugar) at most will yield 41.4 grms. fat, 47.5 grms. C02 and 11.4 grms. H20 
(Meisel). According to Pasteur, glycerin (the basis of neutral fats) may be 
formed from carbohydrates. 
[Tscherwinsky fed two similar pigs from the same litter ; No. I. weighed 7300 grms.; No. II. Sec. 241.] 
CORPULENCE. 
463 
7290 grms. No. I was killed, and its fat and proteids estimated. No. II was fed for four 
months on grain and then killed, the grain and excreta and the undigested fat and proteids 
were analyzed, so that the amount of fat and proteid absorbed in four months was estimated. 
The pig then weighed 24 kilos., it was killed and its fat and proteids estimated. 
No. II. contained 
2.50 
kilos, albumin and 9.25 kilos, fat. 
No. I. 
0.96 
“ “ 0.69 “ 
Assimilated, . . . 
1.56 
8.56 “ “ 
Taken in in food, . 
7-49 
4. 4. 0.66 “ 
Difference, . . . — 
■5-93 
4 4 4. + 7_9o .4 ,< 
There were therefore 7.90 kilos, of fat in the body which could not be accounted for in the fat 
of the food. The 5.93 kilos, of albumin of the food which were not assimilated as albumin 
could yield only a small part of the 7.90 kilos, of fat, so that at least 5 kilos, of fat must have 
been formed from carbohydrates. Lawes and Gilbert calculated that 40 per cent, of the fat in 
pigs was derived from carbohydrates. How the carbohydrates are changed into fat in the body 
is entirely unknown.] 
Formerly it was believed that bees could prepare wax from honey alone ; this is a mistake— 
an equivalent of albumin is required in addition—the necessary amount is found in the raw 
honey itself. 
242. CORPULENCE.—The addition of too much fat to the body is a pathological pheno- 
menon which is attended with disagreeable consequences. With regard to the causes of obesity, 
without doubt there is an inherited tendency (in 33 to 56 per cent, of the cases) in many 
families—and in some breeds of cattle,—to lay up fat in the body, while other families may be 
richly supplied with fat, and yet remain lean. The chief cause, however, is taking too much 
food, i. e., more than the amount required for the normal metabolism; corpulent people, in 
order to maintain their bodies, must eat absolutely and relatively more than persons of spare 
habit, under analogous conditions of nutrition (§ 236). 
Conditions favoring Corpulence.—(1) A diet rich in proteids, with a corresponding addi- 
tion of fat or carbohydrates. As flesh or muscle is formed from proteids, and part of the fat of 
the body is also formed from albumin, the assumption that fats and carbohydrates fatten, or, 
when taken alone, act as fattening agents, is completely without foundation. (2) Diminished 
disintegration of materials within the body, e. g., (a) diminished muscular activity (much sleep 
and little exercise); (b) abrogation of the sexual functions (as is shown by the rapid fattening of 
castrated animals, as well as by the fact that some women, after cessation of the menses, readily 
become corpulent); (c) diminished mental activity (the obesity of dementia), phlegmatic tem- 
perament. On the contrary, vigorous mental work, excitable temperament, care and sorrow, 
counteract the deposition of fat; (d) diminished extent of the respiratory activity, as occurs 
when there is a great deposition of fat in the abdomen, limiting the action of the diaphragm 
(breathlessness of corpulent people), whereby the combustion of the fatty matters which become 
deposited in the body, is limited ; (e) a corpulent person requires to use relatively less heat-giving 
substances in his body, partly because he gives off relatively less heat from his compact body 
than is done by a slender long-bodied individual, and partly because the thick layer of fat re- 
tards the conduction of heat (§ 214, 4). Thus, corresponding to the relatively diminished pro- 
duction of heat, more fat may be stored up; (f) a diminution of the red blood-corpuscles, which 
are the great exciters of oxidation in the body, is generally followed by an increase of fat—fat 
people, as a rule, are fat because they have relatively less blood (§ 41)—women with fewer red 
blood-corpuscles are usually fatter than men; (g) the consumption of alcohol favors the conser- 
vation of fat in the body, the alcohol is easily oxidized, and thus prevents the fat from being 
burned up (g 235). 
Disadvantages of Corpulence.—Besides the inconvenience of the great size and weight of 
the body, corpulent people suffer from breathlessness—they are easily fatigued, are liable to in- 
tertrigo between the folds of the skin, the heart becomes loaded with fat, and they not unfre- 
quently are subject to apoplexy. 
In order to counteract corpulence we ought to — (1) Reduce uniformly all articles of diet. 
The diet and body ought to be weighed from week to week, and as long as there is no diminu- 
tion in the body-weight the amount of food ought to be gradually and uniformly reduced (not- 
withstanding the appetite). This must be done very gradually and not suddenly. A moderate 
reduction of fat and carbohydrates in a normal diet at the same time leads to a diminution of 
the fat of the body itself. Let a person who is capable of muscular exertion take 156 grms. 
proteid, 43 grms. fat, and 114 grms. carbohydrates; but those in whom congestions, hydrsemia, 
breathlessness have taken place, should take 170 grms. proteid, 25 grms. fat, and 70 grms. carbo- 
hydrates (Oertel). It is not advisable to limit the amount of fat and carbohydrates alone, as is 
done in the Banting-cure or Bantingism. Apart altogether from the fact that fat is formed 464 
METABOLISM OF THE TISSUES 
[Sec. 242. 
from proteids, if too little non-nitrogenous food be taken, severe disturbance of the bodily meta- 
bolism is apt to occur. (2) It is advisable during the chief meal to limit the consumption of 
fluids of all sorts (even until three-quarters of an hour thereafter), and thus render the absorption 
and digestive activity of the intestine less active (Oertel). (3) The muscular activity ought to 
be greatly developed by doing plenty of muscular work, or taking plenty of exercise, both physi- 
cal and mental. (4) Favor the evolution of heat by taking cold baths of considerable duration, 
and afterwards rubbing the skin strongly so as to cause it to become red; further, dress lightly, 
and at night use light bed clothing; tea and coffee are useful, as they excite the circulation. (5) 
Use gentle laxatives: acid fruits, cider; alkaline carbonates (of Marienbad, Carlsbad, Vichy, 
Neuenahr, Ems, etc.) act by increasing the intestinal evacuations and diminishing absorption. 
(6) If from accumulation of fat there is danger of failure of the heart’s action, Oertel recom- 
mends hill-climbing, whereby the cardiac muscle is exercised and strengthened. At the same 
time the circulation becomes more lively and the metabolism is increased. 
[Oertel’s Method goes on the idea of strengthening the cardiac musculature, which is sought 
to be accomplished by (1) limiting the amount of fluids consumed, and (2) carefully regulated 
muscular exertion. The amount of food is first reduced one-half, and the water to a still lower 
amount, while the nitrogenous elements in food are increased, the non-nitrogenous are decreased. 
The person is then instructed to take exercise under certain medical precautions, first, on level 
ground, and then on gradually increasing gradients.] 
Fatty Degeneration.—The process of fattening consists in the deposition of drops of fat 
within the fat-cells of the panniculus and around the viscera, as well as in the marrow of bone 
(but they are never deposited in the subcutaneous tissue of the eyelids, of the penis, of the red 
part of the lips, in the ears and nose). This is quite different from the fatty atrophy or fatty 
degeneration which occurs in the form of fatty globules or granules in albuminous tissues, e.g., 
in muscular fibres (heart), gland-cells (liver, kidney), cartilage-cells, lymph- and pus-corpuscles, 
as well as in nerve fibres separated from their nerve-centres. The fat in these cases is derived 
from albumin, much in the same way as fat is formed in the gland-cells of the mammary and 
sebaceous glands. Marked fatty degeneration not unfrequently occurs after severe fevers, and 
after artificial heating of the tissues; when a too small amount of O is supplied to the tissues, 
as occurs in cases of phosphorus poisoning [Bauer); in drunkards; after poisoning with arsenic 
and other substances, and after some disturbances of the circulation and innervation. Some 
organs are especially prone to undergo fatty degeneration during the course of certain diseases. 
243. METABOLISM OF THE TISSUES.—The blood stream 
is the chief medium whereby new material is supplied to the tissues and the 
effete products removed from them. The lymph which passes through the 
thin capillaries comes into actual contact with the tissue elements. Those 
tissues which are devoid of blood-vessels in their own substance, such as the 
cornea and cartilage, receive nutrient fluid or lymph from the adjacent capil- 
laries, by means of their cellular elements, which act as juice-conducting media. 
Hence, when the normal circulation is interfered with, by atheroma or calcifi- 
cation of the walls of the blood-vessels, these tissues are secondarily affected 
[this, for example, is the case in arcus senilis of the cornea, due to a fatty de- 
generation of the corneal tissue, owing to some affection of the blood-vessels 
on which the cornea depends for its nutrition]. Total compression or ligature 
of all the blood-vessels results in necrosis of the parts supplied by the ligatured 
blood-vessels. 
Atrophies caused by diminution of the normal supply of blood, gradually, in the course of 
time become less and less [Samuel'). 
Hence there must be a double current of the tissue juices; the afferent or 
supply current, which supplies the new material, and the efferent stream 
which removes the effete products. The former brings to the tissues the pro- 
teids, fats, carbohydrates, and salts from which the tissues are formed. It is 
evident that any interruption of the arterial supply to the tissues will diminish 
this supply. 
That such a current exists is proved by injecting an indifferent, easily recognizable substance 
into the blood, e.g., potassium ferrocyanide, when its presence may be detected in the tissues, to 
which it has been carried by the outgoing current. 
The efferent stream carries away the decomposition products from the Sec. 243.] 
465 
METABOLISM OF THE TISSUES. 
various tissues, more especially urea, C02, H20, and salts, and these are trans- 
ferred as quickly as possible to the organs through which they are excreted. 
That such a current exists is proved by injecting such a substance as potassium ferrocyanide 
into the tissues, e. g., subcutaneously, when its presence may be detected in the urine within two 
to five minutes. 
If the current from the tissues to the blood is so active that the excretory 
organs cannot eliminate all the effete products from the blood, then these 
products are found in the tissues. When certain poisons are injected subcu- 
taneously, they pass rapidly into the blood and are carried in great quantity to 
other tissues, e.g., to the nervous system, on which they act with fatal effect, 
before they are eliminated to any great extent from the blood by the action of 
the excretory organs. The effete materials are carried away from the tissues by 
two channels, viz., by the veins and by the lymphatics, so that if these be 
interfered with, the metabolism of the tissues must also suffer. When a limb 
is ligatured so as to compress the veins and the lymphatics, the efferent stream 
stagnates to such an extent that considerable swelling of the tissues or oedema 
may occur (§ 203). The action of the muscles and fasciae are very important in 
removing these effete matters. 
H. Nasse found that the blood of the jugular vein is 0.225 Per 1000 specifically heavier than 
the blood of the carotid, and contains 0.9 part per 1000 more solids; 1000 cubic centimetres 
of blood circulating through the head yield about 5 cubic centimetres of transudation into the 
tissues. 
The extent and intensity of the metabolism of the tissues depend 
upon a variety of factors. 
I. Their activity.—The increased activity of an organ is indicated by the 
increased amount of blood going to it, and by the more active circulation 
through it (§ 100). When an organ is completely inactive, such as a paralyzed 
muscle, or the peripheral end of a divided nerve, the amount of blood and the 
nutritive exchange of fluids diminish within these parts. The parts thus 
thrown out of activity become pale, relaxed, and ultimately undergo fatty de- 
generation. The increased metabolism of an organ during its activity has 
been proved experimentally in the case of muscle, and (§ 294) also in the 
brain (Speck). Langley and Sewell have recently observed directly the meta- 
bolic changes within sufficiently thin lobules of glands during life. The cells 
of serous glands (§ 143), and those of mucous and pepsin-forming glands (§ 164), 
during quiescence, become filled with coarse granules, which are dark in trans- 
mitted light and white in reflected light, which granules are consumed or dis- 
appear during granular activity. During sleep, when most organs are at rest, 
the metabolism is limited ; darkness also diminishes it; while light excites it, 
obviously owing to nervous influences. The variations in the total metabolism 
of the body are reflected in the excretion of C02 (§ 126, 9) and urea (§ 257), 
which may be expressed graphically in the form of a curve corresponding with 
the activity of the organism ; this curve corresponds very closely with the daily 
variations in the respirations, pulse, and temperature (§ 213, 4). 
2. The composition of the blood has a marked effect upon the current 
on which the metabolism of the tissues depends. Very concentrated blood, 
which contains a small amount of water, as after profuse sweating, severe 
diarrhoea, cholera, makes the tissues dry, while if much water be absorbed into 
the blood, the tissues become more succulent and even oedema may occur. 
When much common salt is present in the blood, and when the red blood- 
corpuscles contain a diminished amount of O, and especially if the latter con- 
dition be accompanied by muscular exertion causing dyspnoea, a large amount 466 
REGENERATION OF TISSUES AND ORGANS. 
[Sec. 243. 
of albumin is decomposed, and there is a great formation of urea. Hence, 
exposure to a rarefied atmosphere is accompanied by increased excretion of 
urea. Certain abnormal conditions of the blood produce remarkable results; 
blood charged with carbonic oxide cannot absorb O from the air, and does not 
remove C02 from the tissues (§ 16). The presence of hydrocyanic acid in the blood 
(§ 16) is said to interrupt at once the chemical oxidation processes in the blood, 
so that rapid asphyxia, owing to cessation of the internal respiration, occurs. 
Fermentation is interrupted by the same substance in a similar way. A diminution 
of the total amount of the blood causes more fluid to pass from the tissues into 
the blood, but the absorption of substances—such as poisons or pathological 
effusions—from the tissues or intestines is delayed. If the substances which 
pass from the tissues into the blood be rapidly eliminated from it, absorption 
takes place more rapidly. 
3. The blood-pressure, when it is greatly increased, causes the tissues to 
contain more fluid, while the blood itself becomes more concentrated, to the 
extent of 3 to 5 per 1000. We may convince ourselves that blood-plasma 
easily passes through the capillary wall, by pressing upon the efferent vessel 
coming from the chorium deprived of its epidermis, e. g., by a burn ora blister, 
when the surface of the wound becomes rapidly suffused with plasma. Diminu- 
tion of the blood-pressure produces the opposite result. The oxidation pro- 
cesses in the body are diminished after the use of P, Cu, ether, chloroform, and 
chloral. 
4. Increased temperature of the tissues (several hours daily) does 
not increase the breaking up of albumin and fats. (See §§ 220, 221, 225.) 
5. The influence of the nervous system on the metabolism is twofold. 
On the one hand, it acts indirectly through its effect upon the blood-vessels, by 
causing them to contract or dilate through the agency of vaso-motor nerves, 
whereby it influences the amount of blood supplied, and also affects the blood- 
pressure. But quite independently of the blood-vessels, it is probable that certain 
special nerves—the so-called trophic nerves—influence the metabolism or 
nutrition of the tissues (§ 342, c). That nerves do influence directly the trans- 
formation of matter within the tissues is shown by the secretion of saliva result- 
ing from the stimulation of certain nerves, after cessation of the circulation 
(§ 145), and by the metabolism during the contraction of bloodless muscles. 
Increased respiration and apncea are not followed by increased oxidation 
(yPfliiger) (§ 126, 8). 
[Gaskell has raised the question as to the existence of katabolic and anabolic nerves con- 
trolling respectively the analytic and synthetic metabolism of the tissues.] 
244. REGENERATION OF TISSUES AND ORGANS. —The extent to which lost 
parts are replaced varies greatly in different organs. Amongst the lower animals, the parts of 
organs are replaced to a far greater extent than amongst warm-blooded animals. When a hydra 
is divided into two parts, each part forms a new individual—nay, if the body of the animal be 
divided into several parts in a particular way, then each part gives rise to a new individual 
{Spallanzani). The Planarians also show a great capability of reproducing lost parts (Duges). 
Spiders and crabs can reproduce lost feelers, limbs, and claws; snails, part of the head, feelers, 
and eyes, provided the central nervous system is not injured. Many fishes reproduce fins, even 
the tail fin. Salamanders and lizards can produce an entire tail, including bones, muscles, and 
even the posterior part of the spinal cord; while the triton reproduces an amputated limb, the 
lower jaw, and the eye. This reproduction necessitates that a small stump be left, while total 
extirpation of the parts prevents reproduction. 
In amphibians and reptiles the regeneration of organs and tissues, as a 
whole, takes place after the type of the embryonic development, and the same 
is true as regards the histological processes which occur in the regenerated tail Sec. 244.] 
REGENERATION OF TISSUES. 
and other parts of the body of the earth-worm. In amphibians and reptiles 
the same kind of tissue is formed as the tissue which has been injured. The 
spinal cord is regenerated from the epithelium of the spinal canal. The leu- 
cocytes, in the process of new formation, are merely concerned in the nutrition 
of the parts, and do not enter into their construction (Fraisse). [One of the 
most remarkable cases is the regeneration of the retina in tritons after section 
of the optic nerve (Griffini).~\ 
The extent to which regeneration can take place in mammals and in man 
is very slight, and even in these cases it is more marked in young individuals. 
A true regeneration occurs in— 
1. The blood, including the plasma, the colorless and colored corpuscles 
(§ 7 and § 40- 
2. The epidermal appendages (§ 283) and the epithelium of the mucous 
membranes are reproduced by a proliferation of the cells of the deeper layers 
of the epithelium, with simultaneous division of their nuclei. Epithelial cells 
are reproduced as long as the matrix on which they rest and the lowest layer of 
cells are intact. When these are destroyed cell-regeneration from below ceases, 
and the cells at the margins are concerned in filling up the deficiency. Re- 
generation, therefore, either takes place from below or from the margins of the 
wound in the epithelial covering; leucocytes also wander into the part, while 
the deepest layer of cells forms large multi-nucleated cells, which reproduce by 
division polygonal flat nucleated cells. [In the process of division of the cells, 
the nucleus plays an important part, and in so doing it shows the usual mitotic 
figures (§ 431).] The nails grow from the root forwards; those of the fingers 
in four to five months, and that of the great toe in about twelve months, 
although growth is slower in the case of fracture of the bones. The matrix is 
co-extensive with the lunule, and if it be destroyed the nail is not reproduced 
(§ 284). The eyelashes are changed in 100 to 150 days, the other hairs of 
the body somewhat more slowly. If the papilla of the hair-fo'llicle be destroyed, 
the hair is not reproduced. Cutting the hair favors its growth, but hair which 
has been cut does not grow longer than uncut hair. After hair has grown to a 
certain length, it falls out. The hair never grows at its apex. The epithelial 
cells of mucous membranes and secretory glands seem to undergo a regular 
series of changes and renewal. The presence of secretory cells in the milk 
(§ 231) and in the sebaceous secretion (§ 285) proves this; the spermatozoa are 
replaced by the action of spermatoblasts. In catarrhal conditions of mucous 
membranes, there is a great increase in the formation and excretion of new 
epithelium, while many cells are but indifferently formed and constitute mucous 
corpuscles. The crystalline lens, which is just modified epithelium, is 
reorganized like epithelium; its matrix is the anterior wall of its capsule, with 
the single layer of cells covering it. If the lens be removed, and this layer of 
cells retained, these cells proliferate and elongate to form lens fibres, so that the 
whole cavity of the empty lens capsule is refilled. If much water be withdrawn 
from the body, the lens fibres become turbid. [A turbid or opaque condition 
of the lens may occur in diabetes, or after the transfusion of strong common 
salt or sugar solution into a frog.] 
3. The blood-vessels undergo extensive regeneration, and they are re- 
generated in the same way as they are formed (§ 7, B). Capillaries are always 
the first stage, and around them the characteristic coats are added to form an 
artery or a vein. When an artery is injured and permanently occluded, as a 
general rule the part of the vessel up to the nearest collateral branch becomes 
obliterated, whereby the derivatives of the endothelial lining, the connective- 
tissue corpuscles of the wall, and the leucocytes change into spindle-shaped 468 
REGENERATION OF TISSUES. 
[Sec. 244. 
cells, and forma kind of cicatricial tissue. Blind and solid outshoots are always 
found on the blood-vessels of young and adult animals, and are a sign of the 
continual degeneration and regeneration of these vessels. Lymphatics behave 
in the same way as blood-vessels; after removal of a lymphatic gland, a new 
lymphatic formation may be produced {Bayer). 
4. The contractile substance of muscle may undergo regeneration after 
it has become partially degenerated. This takes place after amyloid or'wax- 
like degeneration, such as occurs not unfrequently after typhus and other severe 
fevers. This is chiefly accomplished by an increase of the muscle corpuscles. 
After being compressed, the muscular nuclei disappear, and at the same time 
the contractile contents degenerate. After several days, the sarcolemma con- 
tains numerous nuclei which reproduce new muscular nuclei and the contractile 
substance. In fibres injured by a subcutaneous wound, Neumann found that, 
after five to seven days, there was a bud-like elongation of the cut ends of the 
fibres, at first without transverse striation, but with striation ultimately. If a 
large extent of a muscle be removed, it is replaced by cicatricial connective- 
tissue. Non-striped muscular fibres are also reproduced; the nuclei of the 
injured fibres divided after becoming enlarged, and exhibit a well-marked intra- 
nuclear plexus of fibrils. The nuclei divide into two, and from each of these 
a new fibre is formed, probably by the differentiation of the peri-nuclear proto- 
plasm. 
5. After a nerve is divided, the two ends do not join at once so as to 
permit the function of the nerve to be established. On the contrary, marked 
changes occur. If a piece be cut out of a nerve-trunk, the peripheral end of 
the divided nerve degenerates, the axial cylinders and the white substance of 
Schwann disappear. The interval is filled up at first with juicy cellular tissue. 
The subsequent changes are fully described in § 325, 4. There seems to be in 
peripheral nerves a continual disappearance of fibres by fatty degeneration, 
accompanied by a consecutive formation of new fibres {Sigtn. Mayer). The 
regeneration of peripheral ganglionic cells is unknown. V. Voit, however, 
observed that a pigeon, part of whose brain was removed, had within five 
months reproduced a nervous mass within the skull, consisting of medullated 
nerve-fibres and nerve-cells. Eichhorst and Naunyn found that in young dogs, 
whose spinal cords were divided between the dorsal and lumbar regions, there 
was an anatomical and physiological regeneration, to such an extent that volun- 
tary movements could be executed (§ 338, 3). Vaulair, in the case of frogs, 
and Masius in dogs, found that mobility or motion was first restored, and after- 
wards sensibility. Regeneration of the spinal ganglia did not occur. [The 
taste-bulbs undergo regeneration after they have undergone degenerative 
changes following section of the glosso-pharyngeal nerve {Griffini).~\ 
6. In many glands, the regeneration of their cells during normal activity is 
very active—sebaceous, mucous, Lieberkiihnian, uterine, mammary glands 
during pregnancy—in others less. If a large portion of a secretory gland be 
removed, as a general rule, it is not reproduced. A gland, if injured, and if 
suppuration follows, is not regenerated. But the bile-ducts (§ 173) and the 
pancreatic duct may be reproduced (§ 171). According to Phillippeaux and 
Griffini, if part of the spleen be removed it is reproduced (§ 103). Tizzoni 
and Collucci observed the formation of new liver-cells and bile-ducts after 
injury to the liver, and in fact enormous masses of liver may be reproduced 
{Griffini, Ponfick) (§ 173), and Pisenti makes the same statement as regards the 
kidney. After mechanical injury to the secretory cells of glands (liver, 
kidney, salivary, Meibomian), neighboring cells undergo proliferation, and 
aid in the restoration of the cells. Sec. 244.] 
TRANSPLANTATION OF TISSUES. 
469 
7* Amongst connective-tissues, cartilage, provided its perichondrium be not 
injured, reproduces itself by division of its cartilage cells; but usually when a 
part of a cartilage is removed, it is replaced by connective-tissue. 
8. When a tendon is divided, proliferation of the tendon cells occurs, and 
the cut ends are united by connective-tissue. 
9. The reproduction of bone takes place to a great extent under certain 
conditions. If the articular end be removed by excision, it may be repro- 
duced, although there is a considerable degree of shortening. Pieces of bone 
which have been broken off or sawn off heal again, and become united with the 
original bone. A tooth may be removed, replanted in the alveolus, and be- 
come fixed there. If a piece of periosteum be transplanted to another region 
of the body, it eventually gives rise to the formation of new bone in that 
locality. If part of a bone be removed, provided the periosteum be left, new 
bone is rapidly reproduced ; hence, the surgeon takes great care to preserve the 
periosteum intact in all operations where he wishes new bone to be reproduced. 
Even the marrow of bone, when it is transplanted, gives rise to the forma- 
tion of bone. This is due to the osteoblasts adhering to the osseous tissue. 
In fracture of a long bone, the periosteum deposits on the surface of the ends of the broken 
bones a ring of substance which forms a temporary support, the external callus. At first this 
callus is jelly-like, soft, and contains many corpuscles, but afterwards it becomes more solid 
and somewhat like cartilage. A similar condition occurs within the bone, where an internal 
callus is formed. The formation of this temporary callus is due to an inflammatory prolifera- 
tion of the connective-tissue corpuscles, and partly to the osteoblasts of the periosteum and 
marrow. According to Rigal and Vignal, the internal callus is always osseous, and is derived 
from the marrow of the bone. The outer and inner callus become calcified and ultimately 
ossified, whereby the broken ends are reunited. Towards the fortieth day, a thin layer of bone 
is formed (intermediary callus) between the ends of the bone. Where this begins to be 
definitely ossified, the outer and inner callus begin to be absorbed, and ultimately the inter- 
mediary callus has the same structure as the rest of the bone. 
There are many interesting observations connected with the growth and metabolism of 
bones. 1. The addition of a very small amount of phosphorus or arseniotis acid to the food 
causes considerable thickening of the bones. This seems to be due to the non-absorption of those 
parts of the bones which are usually absorbed, while new growth is continually taking place. 2. 
When food devoid of lime-sails is given to an animal, the growth of the bones is not arrested, but 
the bones become thinner, whereby all parts, even the organic basis of the bone, undergo a uni- 
form diminution. 3. Feeding with madder makes the bones red, as the coloring matter is de- 
posited with the bone-salts in the bone, especially in the growing and last-formed parts. In 
birds the shell of the egg becomes colored. 4. The continued use of lactic acid dissolves the 
bones. The ash of bone is thereby diminished. If lime-salts be withheld at the same time, the 
effect is greatly increased, so that the bones come to resemble rachitic bones. (Development of 
bone, $ 447-) 
When a lost tissue is not replaced by the same kind of tissue, its place is 
always taken by cicatricial connective-tissue. 
When this is the case, the part becomes inflamed and swollen, owing to an exudation of 
plasma. The blood-vessels become dilated and congested, and, notwithstanding the slower 
circulation, the amount of blood is greater. The blood vessels are increased, owing to the 
formation of new ones. Colorless blood-corpuscles pass out of the vessels and reproduce them- 
selves, and many of them undergo fatty degeneration, whilst others take up nutriment and 
become converted into large uninucleated protoplasma cells, from which giant cells are developed. 
The newly formed blood-vessels supply all these elements with blood. 
245. TRANSPLANTATION OF TISSUES. —The nose, ear, and 
even a finger, after having been severed from the body by a clean cut, have, 
under certain circumstances, become united to the part from which each was 
removed. The skin is frequently transplanted by surgeons, as, for example, 
to form a new nose. The piece of skin is cut from the forehead or arm, to 
which it is left attached by a bridge of skin, is then stitched to the part which 470 
INCREASE IN SIZE AND WEIGHT. 
[Sec. 245. 
it is desired to cover in, and when it has become attached in its new situation, 
the bridge of skin is severed. Reverdin cut a piece of skin into pieces about 
the size of a pea and fixed them on an ulcerated surface, where they, as it were, 
took root, grew, and sent off from their margins epithelial outgrowths, so that 
ultimately the whole surface was covered with epithelium. [White skin trans- 
planted to a negro ultimately becomes pigmented, and black skin transplanted 
to a white person becomes white.] The excised spur of a cock was transplanted 
and fixed in the comb of the same animal, where it grew {John Hunter). P. 
Bert cut off the tail and legs of rats and transplanted them under the skin of 
the back of other rats, where they united with the adjoining parts. Ollier found 
that, when periosteum was transplanted, it grew and reproduced bone in its 
new situation. Even blood and lymph may be transfused (Transfusion, § 102). 
[Small portions (1.5 mm.) of epiphyses, costal cartilage, of a rabbit or kitten, 
when transplanted quite fresh into the anterior chamber of the eye, testis, sub- 
maxillary gland, kidney, and under the skin of a rabbit, attach themselves and 
grow, and the growth is more rapid the more vascular the site on which the 
tissue is transplanted. Even rabbit’s bone has been transplanted to the human 
subject and grown in its new site. The cartilage is not essentially different 
from hyaline cartilage, but the cells are fewer in the centre, while the matrix 
tends to become fibrous. Small pieces of epiphysial cartilage introduced into 
the jugular vein were found as cartilaginous foci in the lungs. Tissues trans- 
planted from embryonic structures grow far better than adult tissues. If a por- 
tion of the cornea of a rabbit be transplanted to a human eye, provided Desce- 
met’s membrane be clear, it will grow and remain clear (v. Hippell). A 
rabbit’s nerve has been transplanted to the human subject, but without 
success.] 
Many of these results seem only to be possible between individuals of the 
same species,although Helferich has recently found that a piece of dog’s muscle, 
when substituted for human muscle, united to the adjoining muscle, and be- 
came functionally active. [Magnus, however, finds that a piece of rabbit’s 
muscle transplanted to another rabbit’s muscle serves merely as a temporary 
structure, and does not unite to the end of the original muscular fibres, but the 
latter grow and use the transplanted muscle as a scaffolding, which is ultimately 
absorbed and disappears.] [J. R. Wolfe has transplanted the conjunctiva of 
the rabbit to the human eye.] Most tissues, however, do not admit of trans- 
plantation, e. g., glands and the sense-organs. They may be removed to other 
parts of the body, or into the peritoneal cavity, without exciting any inflam- 
matory reaction ; they, in fact, behave like inert foreign matter. 
246. INCREASE IN SIZE AND WEIGHT.—The length of the 
body, which at birth is usually of the adult body, undergoes the greatest 
elongation at an early period: in the first year, 20; in the second, 10 ; in the 
third, about 7 centimetres; whilst from five to sixteen years the annual increase 
is about centimetres. In the twentieth year the increase is very slight. 
From fifty onwards the size of the body diminishes, owing to the intervertebral 
discs becoming thinner, and the loss may be 6 to 7 centimetres about the 
eightieth year. 
The weight of the body (Jy of an adult) sinks during the first five 
to seven days, owing to the evacuation of the meconium and the small 
amount of food which is taken at first. Only on the tenth day is the 
weight the same as at birth. 
The increase of weight is greater in the same time than the increase in 
length. Within the first year a child trebles its weight. The greatest weight 
is usually reached about forty, while towards sixty a decrease begins, which at Sec. 246.] 
INORGANIC CONSTITUENTS OF THE BODY. 
471 
eighty may amount even to 6 kilos. The results of measurements, chiefly by 
Quetelet, are given in the following table :— 
Age. 
Length (Cmtr.). 
Weight (Kilo.). 
Man. 
Woman. 
Man. 
Woman. 
O 
49.6 
48.3 
3-20 
2.9I 
I 
69.6 
69.O 
10.00 
9-3° 
2 
79.6 
78.O 
12.00 
11.40 
3 
86.0 
85.O 
13 21 
12.45 
4 
93-2 
91.0 
I5-07 
14.18 
5 
990 
97.0 
16.70 
I5.50 
6 
104.6 
IO3.2 
18.04 
10-74 
7 
111.2 
IO9.6 
20.16 
18.45 
8 
117.0 
"3-9 
22.26 
19.82 
9 
122.7 
120.0 
24.O9 
22.44 
IO 
128.2 
124.8 
26.12 
24.24 
ii 
132.7 
127.5 
27.85 
26.25 
12 
135-9 
132-7 
31.08 
3°-54 
13 
140.3 
138.6 
35-32 
34.65 
14 
148.7 
144.7 
4O.5O 
38.IO 
Age. 
Length (Cmtr.). 
Weight (Kilo.). 
Man. 
Woman. 
Man. 
Woman. 
15 
155-9 
147-5 
46.41 
4I.30 
16 
161.0 
150.0 
53-39 
44.44 
17 
167.0 
154-4 
57-40 
49.08 
18 
170.0 
156.2 
61.26 
53-io 
19 
1706 
63-32 
20 
171.1 
i57o 
65.00 
54-46 
25 
172.2 
157-7 
68 29 
55.08 
3° 
172.2 
157-9 
68.90 
55-H 
40 
171-3 
155-5 
68.81 
56.65 
5o 
167.4 
153-6 
67-45 
58.45 
60 
163.9 
151.6 
65.50 
56.73 
70 
162.3 
151 -4 
63-03 
53-72 
80 
161.3 
150.6 
61.22 
5i-52 
90 
57-83 
49-34 
(Chiefly from Quetelet.) 
Between the 12th and 15th years the weight and size of the girl are greater than of the boy. 
Growth is most active in the last months of foetal life, and afterwards from the 6th to the 9th 
year until the 13th to 'the 16th. The full stature is reached about 30 but not the greatest 
weight. 
General View of the Chemical Constituents of the 
Organism. 
247. (A) INORGANIC CONSTITUENTS.—I. Water forms over 
60 per cent, of the whole body, but it occurs in different quantity in the 
different tissues. The kidneys, brain, and vitreous humor contain the most 
water; bones, 22 percent.; teeth, 10 per cent.; while enamel contains the 
least, 0.2 per cent. (§ 229). According to some observers, peroxide of hydrogen 
(H202) is also present in the body. 
[Approximately, water forms about two-thirds of the weight of the body, 
so that a body weighing 75 kilos. (165 lbs.) contains 50 kilos, (no lbs.) of 
water. The following table, modified from Beaunis, shows the percentage of 
water in several tissues and organs:— 
Solids. 
Tissue or Organ. Water. 
Solids. 
Tissue or Organ. 
Water. 
Solids. 
Spinal cord, 
• 697 
3°-3 
Thymus, . . . 
77.O 
23.O 
White matter of 
brain, . . . 
} 7°-° 
30.0 
Connective- 1 
tissue, . . . j 
79-6 
2O.4 
Skin, .... 
. 72.0 
28.0 
Kidney, . . , . 
82.7 
17-3 
Brain, .... 
Muscles, . . „ 
• 75-o 
- 75-7 
25.0 
24-3 
Gray matter' 
of brain, . . 
>85.8 
I4.2 
Spleen, . . . 
• 75-8 
24.2 
Vitreous humor, 
98.7 
i-3 
Tissue or Organ. Water. 
Solids. 
Enamel, . . . 
.2 
99.8 
Dentine, . 
10.0 
90.0 
Bone, 
48.6 
51-4 
Fat, . ; . 
29.9 
70.1 
Elastic tissue, . . 
49.6 
50-4 
Cartilage, 
S5.0 
45-o 
Liver, . . . 
69-3 
30.7 
Blood, . 
79.1 
20.9 
Bile, . . . 
86.4 
13.6 
Milk, . 
89.1 
10.9 
Liquor sanguinis, 
90.1 
9-9 
Chyle, 
92.8 
7.2 
Liquids. 
Lymph, . . . . 95.8 
4.2 j 
Aqueous humor, . 
. 98.6 
14 
Serum, 95.9 
4.1 I 
Cerebro-spinal 
[98.8 
Gastric juice, . . 97.3 
2.7 
fluid, . . . 
Intestinal juice, . 97.5 
2-5 
Saliva, .... 
• 995 
05 
Tears, 98.2 
1.8 
1 Sweat, .... 
■ 99-5 
o-5 
II. Gases.—O,— ozone (§ 37) — H, — N, — C02 (§ 38). Marsh gas CH4 (g 124), NH3 
(S 30, $ 124, $ 184), H2S (g 184). 472 
INORGANIC CONSTITUENTS OF THE BODY. 
[Sec. 247. 
III. Salts.—Sodium Chloride [is one of the most important inor- 
ganic substances present in the body. It occurs in all the tissues and fluids of 
the body, and plays a most prominent part in connection with the diffusion of 
fluids through membranes, and its presence is necessary for the solution of the 
globulins (p. 476). Sometimes it exists in a state of combination with proteid 
bodies, as in the blood-plasma. Common salt is absolutely necessary for one’s 
existence, as it facilitates absorption by promoting endosmotic processes, and it 
also increases tissue metabolism; if it be withdrawn entirely, life soon comes 
to an end. The body contains about 200 grams. About 15 grams are given 
off in twenty-four hours, chiefly by the urine. Boussingault showed that the 
addition of common salt to the food of cattle greatly improved their condition.] 
[Calcium phosphate (Ca3P208) is the most abundant salt in the body, as it forms more 
than one-half of our bones, but it also occurs in dentine, enamel, and to a much less extent in 
the other solids and fluids of the body. Amongst secretions, milk contains relatively the largest 
amount. In milk it is necessary for forming the calcareous matter of the bones of the infant. 
It gives bones their hardness and rigidity. It is chiefly derived from the food, and, as only 
a small quantity is given off in the excretions, it seems not to undergo rapid removal from the 
body.] 
[Sodium phosphate (Na3P04), acid sodium phosphate (N a2H P04), acid potassium phosphate 
(K2HP04). The sodium phosphate and the corresponding potash salt give most of the fluids of 
the body their alkaline reaction. The alkaline reaction of the blood-plasma is partly due to 
alkaline phosphates, which are chiefly derived from the food. The acid sodium phosphate is 
the chief cause of the acid reaction of the urine. A small quantity of phosphoric acid is formed 
in the body owing to the oxidation of lecithin, which contains phosphorus.] 
[Sodium carbonate (Na2C03) and sodium bicarbonate (NaIIC03) exist in small quan- 
tities in the food, and are formed in the body from the decomposition of the salts of the vege- 
table acids. They occur in the blood-plasma, where they play an important part in carrying 
the CO,2 from the tissues to the lungs.] 
[Sodium and potassium sulphates (Na2S04 and K2S04) exist in very small quantity in 
the body, and are introduced with the food, but part is formed in the body from the oxidation of 
organic bodies containing sulphur.] 
[Potassium chloride (KC1) is pretty widely distributed, and occurs specially in muscle, 
colored blood-corpuscles, and milk. Calcium floride (CaFl2) occurs in small quantity in bones 
and teeth. Calcium carbonate (CaC03) is associated with calcium phosphate in bone, teeth, 
and in some fluids, but it occurs in relatively much smaller amount. It is kept in solution by 
alkaline chlorides, or by the presence of free carbonic acid. Ammonium chloride (NH4C1). 
—Minute traces occur in the gastric juice and the urine. Magnesium phosphate (Mg3P04) 
occurs along with calcium phosphate, but in very much smaller quantity.] 
Table by Beaunis of the relative proportions of Salts. The figures give the percentage 
quantities of mineral matters in the ash. 
Heintz. 
Staffel. 
Breed. 
Oidtmann. 
C. Schmidt. 
Oidtmann. 
Bone. 
Muscle of 
calf. 
Brain. 
Liver. 
Lungs. 
Spleen. 
Sodic chloride, .... 
io-59 
4-74 
I3.0 
Potassic chloride, . . . 
Soda, 
2-35 
10 69 
I4-5I 
19-5 
44-33 
Potash, 
34-40 
34-42 
25-23 
i-3 
9.60 
Lime, 
37-58 
1.99 
0-77 
3.61 
i-9 
7.48 
Magnesia, 
1.22 
i-45 
1.23 
0.20 
1.9 
0.49 
Ferric oxide, 
2-74 
3-2 
7.28 
Chlorine, 
2.58 
0-54 
Fluorine, 
1.66 
Phosphoric acid (free), . 
9-15 
Phosphoric acid (comb.), 
53-31 
48.13 
39.02 
50.18 
48.5 
27.10 
Sulphuric acid, .... 
0-75 
O.92 
1.4 
2-54 
Carbon dioxide, .... 
5-47 
Silicic acid, 
0.81 
0.12 
O.27 
0.17 
Ferric phosphate, . . . 
1.23 Sec. 247.] 
ORGANIC COMPOUNDS. 
473 
Table by Beaunis of the Mineral Matter in Animal Fluids, i.e., the percentage in the ash 
Verdeil. 
Weber. 
Weber. 
Dahn- 
hardt. 
Porter. 
Wilder- 
stein. 
Rose. 
Porter. 
Blood. 
Blood- 
serum. 
Blood- 
clot. 
Lymph. 
Urine. 
Milk. 
Bile. 
Faeces. 
Sodic chloride, 
58.81 
72.88 
I7.36 
74.48 
67.28 
io-73 
27.70 
4-33 
Potassic chloride 
29.87 
26.33 
Soda, .... 
415 
12.93 
3-55 
>o-35 
I-33 
. . 
36.73 
5 07 
Potash, . . . 
11.97 
2.95 
22.36 
3-25 
13-64 
21.44 
4.80 
6.10 
Lime, .... 
I.76 
2.28 
2.58 
0.97 
18.78 
1-43 
26.40 
Magnesia, . . 
1.12 
0.27 
0-53 
0.26 
i-34 
0.87 
0-53 
10.54 
Ferric oxide, . 
8-37 
0.26 
10.48 
0.50 
0.10 
0-33 
• 2.50 
Phosphoric acid, 
IO.23 
i-73 
10.64 
1.09 
11.21 
19.00 
10 45 
36.03 
Sulphuric acid, 
I.67 
2.10 
0.09 
2.64 
6.39 
Carbon dioxide, 
1.19 
4.40 
2.17 
8.20 
11.26 
Silicic acid, . . 
0.20 
0.42 
1.27 
4.06 
0.36 
3-13 
IV. Free Acids.—Hydrochloric acid (HC1) [occurs free in the gastric juice, but in com- 
bination with the alkalies it is widely distributed as chlorides.] Sulphuric acid (H2S04) [is 
said to occur free in the saliva of certain gasteropods, as Dolium galea. In the body it forms 
sulphates, chiefly in combination with soda and potash. The caterpillar of the Puss Moth 
secretes for defensive purposes a highly acid fluid composed of formic acid and water. The 
proportion may be 40 per cent, of acid and one-twentieth of a gram may be ejected at once from 
a mature larva (Poulton).] 
V. Bases. — Silicon as silicic acid (Si02); manganese; iron, the last forms an integral 
constituent of haemoglobin [the total quantity in the blood being about 3 grams]. [Iron is 
readily detected in organs in which it occurs on hardening small parts of the organ in alcohol 
and then in alcohol containing ammonium sulphide, which makes the iron granules a green 
color] ; copper (?), (g 174). 
248. (B) ORGANIC COMPOUNDS.—The Albuminous or Pro- 
teid Substances.—(1) True Proteids and their Allies are composed of 
C, H, O, N, and S, and are derived from plants (see Introduction). [The 
formation of albumin from the elements is accomplished only by plants. What 
the chemical processes are is quite unknown. We only know that the N is in 
the first instance obtained from the nitric acid or ammonia of the soil. The 
former is probably not used directly as such, but serves, perhaps, for the forma- 
tion of amides or amido-acids, from which, by the action of non-nitrogenous 
bodies, proteids are formed.] 
[The exact formula of the proteids is unknown, as they have never been obtained sufficiently 
pure and in such quantity as to admit of an elementary analysis being made. From such 
analyses as have been made Bunge gives the following formulae :— 
Egg albumin, 
N„ 
®66 
S, 
Proteid in haemoglobin from horse, 
*• C680 
-^1098 
■^210 
oM1 
s? 
Globulin from pumpkin seeds, . . 
• 
H481 
n90 
®83 
«2 
According to Hoppe-Seyler their general percentage composition is— 
0 
H 
N 
C 
S 
From . 
. . 20.9 
6.9 
15.2 
5i-5 
°-3 
To . . , 
• • 23-5 
7-3 
17.0 
54-5 
2.0] 
They exist in almost all animal fluids and tissues, partly in the fluid form, although Briicke 
maintains that the molecule of albumin exists in a condition midway between a state of imbibi- 
tion and a true solution—and partly in a more concentrated condition. Besides forming the 
chief part of muscle, nerve, and gland, they occur in nearly all the fluids of the body, including 
the blood, lymph, and serous fluids, but in health mere traces occur in the sweat, while they 
are absent from the bile and the urine. Unboiled white of egg is the type. In the ali- 
mentary canal they are changed into peptones. The chief products derived from their oxida- 
tion within the body are C02, H20, and especially urea, which contains nearly all the N of the 
proteid'. 474 
CHARACTERS OF PROTEIDS. 
[Sec. 248. 
[The term proteid (7t/iuteiov, pre-eminence) was given by Mulder, and is now used as synony- 
mous with the term “ albuminous body.”] 
Constitution of Proteids.—Their chemical constitution is quite unknown. The N seems to 
exist in two distinct conditions, partly loosely combined, so as to yield ammonia readily when 
they are decomposed, and partly in a more fixed condition. According to Pfliiger, part of the 
N in living proteid bodies exists in the form of cyanogen. [Loew supports PfUiger’s view that 
the molecule of living (active) albumin differs from that of dead albumin, as he finds that the 
living protoplasm of certain algae can reduce silver in very dilute alkaline solutions, which dead 
protoplasm cannot do ] The proteid molecule is very large, and is a very complex one; a small 
part of the molecule is composed of substances from the group of aromatic bodies (which become 
conspicuous during putrefaction), the larger part of the molecule belongs to the fatty bodies; 
during the oxidation of albumin fatty acids especially are developed. Carbohydrates may also 
appear as decomposition-products. For the decompositions during digestion, see \ 170, and 
during putrefaction, \ 184. The proteids form a large group of closely related substances, all of 
which are perhaps modifications of the same body. When we remember that the infant 
manufactures most of the proteids of its ever-growing body from the casein in milk, this last 
view seems not improbable. 
Characters of Proteids.—Proteids, the anhydrides of peptones (§ 166), 
are colloids (§ 191), and therefore do not diffuse easily through animal mem- 
branes ; they are amorphous and [for the most part] do not crystallize, and 
hence are isolated with difficulty; some are soluble, others are insoluble in 
water; insoluble in alcohol and in ether; rotate the ray of polarized light to 
the left; when burned they give the odor of burned horn. Various metallic 
salts and alcohol precipitate them from their solutions; they are coagulated 
by heat, mineral acids, and the prolonged action of alcohol. Caustic alkalies 
dissolve them (yellow), and from this solution they are precipitated by acids. 
By powerful oxidizing agents they yield carbamic acid, guanidin, and volatile 
fatty acids. 
Decomposition of Proteids.—[The number and varieties of these products are exceedingly 
great, so that it is not easy to separate the several products. In the first place, there is great 
difficulty in getting in sufficient quantity a perfectly pure proteid, wherewith to institute the 
necessary experiments. The decomposition-products of albumin when acted on by barium 
hydrate have been most fully investigated. The action of concentrated HC1, potassic perman- 
ganate, and bromine have also been studied. The action of the animal or vegetable digestive 
ferments is very important (£ 170), and specially that of bacteria causing putrefaction ($ 184).] 
When acted upon in a suitable manner by acids and alkalies, they give rise to the decomposition- 
products—leucin (10 to 18 per cent.), tyrosin (0.25 to 2 per cent.), aspartic acid, glutamic acid, 
and also volatile fatty acids, benzoic and hydrocyanic acids, and aldehydes of benzoic and fatty 
acids; also indol (Hlasiwetz, Heberinann). Similar products are formed during pancreatic 
digestion (§ 170) and during putrefaction (§ 184). [Although it is assumed that the proteids 
have the closest relation to urea, no one, so far, has succeeded in preparing urea by the direct 
decomposition of albumin. Both by the action of acids and barium hydrate, the splitting up 
into simpler compounds does not take place at once, but by successive stages, one to the forma- 
tion of different bodies. Proteids, when fully decomposed, either by acids or alkalies, yield as 
the final products ammonia and amido-acids; by alkalies also carbonic, acetic, and oxalic acids. 
The amido-acids contain several series, including leucin, tyrosin, and glutamic acid. But all 
proteids do not yield these three bodies, for tyrosin may be absent, while leucin, so far, has 
been always found. It has therefore been attempted to classify proteids into those that yield 
tyrosin (*. e., aromatic compounds) and those that do not. Classes I.-VIII., p. 476, yield when 
decomposed aromatic bodies (tyrosin, indol, phenol), while gelatin-yielding bodies and spongin 
yield no aromatic bodies.] 
[Electrolysis of Animal Tissues including Proteids.—A current in passing through a 
tissue or a proteid solution is conducted almost entirely by the inorganic constituents. The chemi- 
cal effects produced on the proteid constituents are due to secondary actions of the products of 
electrolysis of the salts. At the positive pole coagulable proteids are partly coagulated and 
partly changed into acid-albumin ; at the negative pole alkali-albumin is formed. When blood 
or a pure haemoglobin solution is electrolyzed, methaemoglobin and then acid haematin are formed 
at the anode, but not if a reducing agent be present; alkali-haematin is formed at the cathode 
(G. N. Stewart). 
General Reactions of Proteids.—(1) Xanthoproteic Reaction.— 
Heated with strong nitric acid they give a yellow, the addition of excess of Sec. 248.] 
GENERAL REACTIONS OF PROTEIDS. 
475 
ammonia gives a deep orange color. [The deepening of the color from yellow 
to orange is the most important part of the reaction and is one of the best tests 
for the presence of proteids.] 
(2) With Millon’s reagent they give a white precipitate, and when heated 
with this reagent above 6o° C. they give a brick-red color, probably owing to 
the formation of tyrosin. [This does not occur in the presence of sodic chlor- 
ide. If the proteids are present in large amount, a red precipitate occurs, but 
if mere traces are present only the fluid becomes red.] 
(3) Biuret-reaction.—The addition of a few drops of a dilute solution of 
cupric sulphate, and the subsequent addition of excess of caustic potash 
or soda, give a violet color, which deepens on boiling. The biuret-reaction is 
so called because the reddish-violet color is like that given by the substance 
biuret, a derivative of urea. This is sometimes called Piotrowski’s reaction. 
[The same color is obtained by adding a few drops of Fehling’s solution]. 
(4) They are precipitated after strong acidulation by acetic acid and potas- 
sium ferrocyanide. 
(5) Liebermann’s reaction.—When proteids are washed with alcohol 
and ether and then boiled with concentrated hydrochloric acid, they give a 
violet-red color. 
(6) Sulphuric acid containing molybdic acid gives a blue color (Frohde). 
(7) Adamkiewicz’ reaction.—Their solution in glacial acetic acid is 
colored violet with concentrated sulphuric acid, and shows the absorption-band 
of hydrobilirubin. r 
(8) Iodine is a good microscopic reagent, which strikes a brownish-yellow, 
while sulphuric acid and cane-sugar give a purplish-white (F. Schultz). 
[(9) When rendered strongly acid with acetic acid and boiled with an equal 
volume of a concentrated solution of sodic sulphate, they 'are precipitated. 
This method is used for removing proteids from other liquids, as it does not 
interfere with the presence of other substances. Saturation with sodio-mag- 
nesic sulphate precipitates the proteids, but not peptones, and the same is the 
case with saturation with neutral ammonia sulphate (§ 249).] 
[(10) The precipitation of albumin by acids is more delicate when the acid is 
dissolved in alcohol containing 10 per cent, of ether; the precipitate is not 
dissolved by an excess of the reagent.] 
[(11) Most of them are precipitated by strong mineral acids, and meta- 
phosphoric acid, tannic acid (in an acid solution), phospho-tungstic and phos- 
pho-molybdic acids (in acid solution); potassio-mercuric iodide (in acid solu- 
tions) ; many metallic salts, e. g., of Cu, Pb, Ag, Hg ; chloral, phenol, trichlor- 
acetic acid, picric acid, alcohol. Taurocholic acid precipitates albumin and 
syntonin, but not peptone or hemi-albumose (§ 181).] 
[(12) On adding 2-3 drops of a weak solution of benzaldehyd with a fair 
amount of sulphuric acid, (1 : 1 water) and 1 drop of ferric sulphate, albumin, 
on being heated, or after standing, gives a deep blue color (.Reiche)S\ 
[Precipitants of Proteids.—All the proteids cannot be precipitated with 
equal ease, the albumoses and peptones being exceptions. As a group they are 
precipitated by (1) strong mineral acids, e. g., nitric, phosphotungstic and meta- 
phosphoric acids; (2) Salts of the heavy metals, forming an albuminate of the 
metal; (3) acetic acid and ferro-cyanide of potassium ; (4) acetic acid and ex- 
cess of certain neutral salts (NaCl, Na2S04, MgS04) ; (5) saturation with am- 
monium sulphate, etc. ; (6) picric acid, or tannic acid, or alcohol.] 
Proteids maybe removed from a fluid containing them by means of (1) Briicke’s method, i. e., 
precipitation with hydrochloric acid and potassio-mercuric iodide (p. 325). (2) By boiling a 
faintly acid fluid containing them. (3) Wenz’s method, viz., saturating the liquid with ammo- 
nium sulphate which precipitates all proteids except peptones. 476 
NATIVE ALBUMINS AND GLOBULINS. 
[Sec. 248. 
[Coagulation of Proteids by Heat.—When a soluble proteid passes into 
an insoluble one by heat, this is called heat-coagulation. The proteids coagu- 
lated by heat are egg-albumin, serum-albumin, and globulins, but the tempera- 
ture at which this remarkable change takes place has been shown to vary with 
the nature of the proteids present in the solution (Fractional heat-coagulation, 
p. 45) with the concentration of the solution, and also with the quantity and 
nature of the salts present. The following table after Halliburton shows the 
temperatures of coagulation of some of the principal proteids:— 
Albumins. 
Egg-albumin, 
• • 73° C. 
Serum-albumin a, 
• • 75° 
“ “ P, 
• • 77° 
<< U y^ 
. . 84° 
Cell albumin, 
■ • 73° 
Muscle albumin, ....... 
- • 73° 
Lact-albumin, 
• • 77° 
Globulins. 
Fibrinogen, . . . 
. 56° C. 
Serum-globulin, ....... 
- 75° 
Cell-globulin, \ 
• 75° 
Myosinogen, 
- 56° 
Myo-globulin, 
- 63° 
Vitellin, 
Crystallin, 
- 75° 
• 73°] 
249. THE ANIMAL PROTEIDS AND THEIR CHARAC- 
TERS.—Class I.—Native Albumins occur in a natural condition in ani- 
mal solids and fluids. They are soluble in water [in dilute saline solutions 
and in saturated solutions of sodic chloride and magnesium sulphate], and are 
not precipitated by alkaline carbonates, NaCl, or by very dilute acids. [They 
are precipitated by saturating their solutions with ammonium sulphate.] Their 
solutions are coagulated by heating at 65° to 730 C. Dried at 40° C., they 
yield a clear, yellow, amber-colored, friable mass, “ soluble albumin,” which 
is soluble in water. 
(1) Serum-albumin (g 32 and \ 41).—Its specific rotatory power is - 56°. Almost all its 
salts may be removed from it by dialysis, when it is no longer coagulated by heat. It is coagu- 
lated by strong alcohol; and not very readily precipitated by hydrochloric acid, while the pre- 
cipitate so formed is easily dissolved on adding more acid. When precipitated, it is readily 
soluble in strong nitric acid. It is not precipitated when shaken up with ether. The addition 
of w'ater to the hydrochloric solution precipitates acid-albumin. For its presence abnormally in 
urine, § 264. 
(2) Egg-albumin.—When injected into the blood-vessels or under the skin, or even when 
introduced in large quantity into the intestine, part of it appears unchanged in the urine (§ 192, 
4, and \ 264). When shaken with ether it is precipitated. These two reactions serve to dis- 
tinguish it from (1). The specific rotation is-35.5, i. <?., for yellow light. Amount of S, 1.6 
per cent. 
(3) Muscle-albumin, i. e., the proteid extracted from muscle by water (§ 293). 
(4) Cell-albumin ($ 24). 
(5) Lact-albumin (§ 231). 
Class II.—Globulins are native proteids, insoluble in distilled water, 
but soluble in dilute neutral saline solutions, i. e., neutral solutions of 
the alkalies and alkaline earths, e. g., NaCl, KC1, NH4C1, Na2S04, (but not 
Na2C03, Na2P04), sodium chloride of i per cent., and in magnesium sulphate. 
[They are insoluble in concentrated solutions of NaCl, MgS04, (NH4)2 S04.] 
These solutions are coagulated by heat, and are precipitated by the addition of 
a large quantity of water. Most of them are precipitated from their sodium 
chloride solution by the addition of crystals of sodium chloride, and also by 
saturating their neutral solution at 30° with crystals of magnesium sulphate or 
ammonium sulphate. When acted upon by dilute acids they yield acid-albumin, 
and by dilute alkalies, alkali-albumin. 
(1) Globulin (Ciystallin) is obtained by passing a stream of C02 through a watery extract of 
the crystalline lens. 
(2) Vitellin is the chief proteid in the yolk of egg. It is also said to occur in the chyle (?) 
and in the amniotic fluid (IVeyl). Both the foregoing are not precipitated from their neutral 
solutions by saturation with sodium chloride. Sec. 249.] 
DERIVED ALBUMINS AND PROTEOSES. 
477 
(3) Para-globulin or Serum-globulin in blood-plasma ($ 29), and abnormally in urine 
(2 264)- 
(4) Fibrinogen (§ 29).—In the clear jelly-like secretion of the vesiculae seminales of the 
guinea-pig, there is a globulin-like body closely resembling fibrinogen. It contains 29 per cent, 
of albumin, with scarcely any ash. If it be touched with a trace of blood-serum, without 
mixing them, it gradually and completely forms a solid mass quite like fibrin. 
(5) Myosinogen, from which is formed myosin, is the chief proteid in dead muscle. Its 
coagulation in muscle post-mortem constitutes rigor mortis. If muscle be repeatedly washed, 
and afterward treated with a 10 per cent, solution of sodium or ammonium chloride, it yields 
a viscid fluid which, when dropped into a large quantity of distilled water, gives a white 
flocculent precipitate of myosin. It is also precipitated from its NaCl solution by crystals of 
NaCl. For Kuhne’s and other methods, see $ 293. 
(6) Globin (Preyer), the proteid constituent of haemoglobin ($ 18). 
Class III.—Derived Albumins (Albuminates).—[They are obtained 
by the action of acids or alkalies on albumins, globulins or other proteids ; are 
insoluble in pure water, but are soluble in acid or alkaline solutions, or in weak 
saline solutions. Like globulins, they are precipitated by saturation with neutral 
salts (NaCl, MgS04, (NH4)2 S04). Their solutions are not coagulated by 
heat.] 
(1) Acid-albumin or Syntonin.—When proteids are dissolved in the stronger acids, e.g., 
hydrochloric, they become changed into acid-albumins. They are precipitated from solution by 
the addition of many salts, sodic chloride, acetate or phosphate, or by neutralization with an 
alkali, e.g., sodic carbonate, but they are not precipitated by heat. The concentrated solution 
gelatinizes in the cold, and is redissolved by heat. Syntonin, which is obtained by the pro- 
longed action of dilute hydrochloric acid (2 per 1000) upon minced muscle, is also an acid 
albumin. It is formed also in the stomach during digestion ($ 166, I). According to Soyka, 
the alkali- and acid-albumins differ from each other only in so far as the proteid in the one case 
is united with the base (metal) and in the other with the acid. 
(2) Alkali-albumin.—If egg- or serum-albumin be acted upon for some time by dilute 
alkalies, a solution of alkali-albumin is obtained. Strong caustic potash acts upon white of 
egg, and yields a thick jelly, Lieberkiihn’s jelly. The solution is not precipitated by heat, but 
it is precipitated by the addition of an acid. [Although alkali-albumin is precipitated 
on neutralization, this is not the case in the presence of alkaline phosphates, e.g., sodic 
phosphate.] 
(3) Casein is the chief proteid in milk ($231). It is precipitated by acids and by rennet at 
40° C. In its characters it is closely related to alkali-albuminate, but it contains more N. It 
contains a large amount of phosphorus (0.83 per cent.). It may be precipitated from milk by 
diluting it with several times its volume of water and adding dilute acetic acid, or by adding 
magnesium sulphate crystals to milk and shaking vigorously. Owing to the large amount of 
phosphorus which it contains, it is sometimes referred to the nucleo-albumins. When it is 
digested with dilute IICl (0.1 percent.) and pepsin at the temperature of the body, it gradually 
yields nuclein. 
[Caseinogen and Casein.—Halliburton has recently suggested that the term caseinogen 
should be applied to the chief proteid as it exists in milk, reserving the term casein for the pre- 
cipitate obtained in milk by the action of rennet in the presence of calcium salts. Caseinogen is 
precipitated from milk by saturating the milk with neutral salts (MgS04, NaCl) or by adding a 
very small amount of acid (acetic). This terminology brings the milk-proteid in line with some 
other proteids, e.g., myosin from myosinogen; fibrin from fibrinogen, etc. Casein, therefore, 
would be classed “ with fibrin, myosin, glutin, as proteids, more or less insoluble, which are pro- 
duced by ferment action from other proteids of more soluble nature.” It is more difficult to 
classify caseinogen, for in some respects it resembles alkali-albumin and in others the globulins, 
but it differs from both, and Halliburton suggests that it should be put into a class intermediate 
between the albuminates and the globulins.] 
[Class IV.—Proteoses.—This name is given to a number of products 
formed during the hydration of proteids. They are formed by the action of 
gastric or pancreatic juice on proteids, the final product being peptone. They 
may also be formed by heating proteids with water, steam, or dilute mineral 
acids. They are only slightly diffusible. Suppose we start with albumin, 
before the stage of peptone is reached, an intermediate body, albumose, is 478 
PROTEOSES. 
[Sec. 249. 
formed ; this body is a proteose. The particular proteose formed depends on 
the nature of the original proteid ; thus albumin yields albumoses; globulin 
globuloses; myosin myosinoses, casein caseoses, etc., (§ 166). 
They are not coagulated by heat; they are precipitated, but not coagulated 
by alcohol; with the biuret test they give a rosy pink color. They are pre- 
cipitated by nitric acid, but the precipitate is soluble on heating and reappears 
on cooling. 
There are two varieties; suppose we take albumin as the original proteid, 
then we obtain hemi-albumose, which can be changed into hemi pep- 
tone ; and anti-albumose, which is changed during digestion into anti- 
peptone.] 
[They are classified according to their solubilities into :— 
(a) Proto-albumose, which is soluble in cold and hot water and saline solutions, but it is 
precipitated like globulins by saturation with NaCl or MgS04. 
(b) Hetero-albumose is soluble in water, soluble in 0.5-15 per cent. NaCl solutions in 
the cold. It is precipitated by dialyzing out the salt from its solutions. It is precipitated by 
saturation with salts. 
(c) Deutero-albumose is soluble in cold and hot water, not precipitated by saturation with 
NaCl or MgS04, but by ammonium sulphate. 
Proto- and hetero-albumose are sometimes called the primary albumoses, while deutero- 
albumose is a stage much nearer to peptone. 
The following table from Halliburton shows the chief properties of these bodies and also of 
peptone:— 
Variety of Proteid. 
Hot and 
Cold Water. 
Hot and 
Cold Saline 
Solutions, 
e.g., 10 per 
cent. NaCl. 
Saturation 
with NaCl 
or M gS04. 
Saturation 
with Amj 
SO4. 
Nitric Acid. 
Copper 
Sulphate. 
Biuret Test, 
i. e.. Copper 
Sulphate 
and Caustic 
Potash. 
Proto- 
Albumose 
. 
’ 
Soluble. 
Soluble. 
Precipi- 
tated. 
Precipi- 
tated. 
Precipitated 
in cold : 
precipitate 
dissolves 
with heat 
and re- 
appears on 
cooling. 
Precipi- 
tated. 
Rose-red 
color. 
Hetero- 
Albumose 
■ 
. 
Insoluble, 
i. e., pre- 
cipitated 
by dialysis 
from saline 
solutions. 
Soluble; 
partly pre- 
cipitated 
but not 
coagulated 
on heating 
to 65° C. 
Precipi- 
tated. 
Precipi- 
tated. 
Do. 
Precipi- 
tated. 
Do. 
Deutero- 
Albumose 
I 
• 
Soluble. 
Soluble. 
Not precipi- 
tated. 
Precipi- 
tated. 
Thisreaction 
only occurs 
in presence 
of excess 
of salts. 
Not precipi- 
tated. 
Do. 
Peptone 
{ 
Soluble. 
Soluble. 
Not Precipi- 
tated. 
Not precipi- 
tated. 
Not precipi- 
tated . 
Not precipi- 
tated. 
Do.] 
Class V.—Peptones.—There are two classes, Hemipeptone and Anti- 
peptone. The former can be split up by pancreatic juice into simple products, 
eg., leucin and tyrosin (§ 170, II.) ; the latter not. Nor does the latter give 
Millon’s reaction. Both diffuse readily. 
Class VI.—Fibrin.—(§ 72) and for the precursors of fibrin (§ 29). 
Class VII.—Coagulated Proteids.—When any native albumins or globulins are coagulated, 
e.g., at 70° C., they yield bodies with altered characters, insoluble in water and saline solutions, Sec. 249.] 
VEGETABLE PROTEIDS. 
479 
but soluble in boiling strong acids and alkalies, when they are apt to split up. They are dis- 
solved during gastric and pancreatic digestion to produce peptones. 
[Halliburton divides coagulated proteids—(i), those coagulated by heat, and (2), those 
coagulated by the action of ferments. In the latter class is included fibrin, myosin, casein, and 
anti-albumin.] 
Class VIII. — Lardacein and other Bodies.—There fall to be mentioned the “yelk- 
plates,” which occur in the yelk: Ichthin (cartilaginous fishes, frog); Ichthidin (osseous 
fishes); Ichthulin (salmon); Emydin (tortoise); also the indigestible amyloid substance or 
lardacein, which occurs chiefly as a pathological infiltration into various organs, as the liver, 
spleen, kidneys and blood-vessels. It gives a blue with iodine and sulphuric acid (like cellulose), 
and a mahogany-brown with iodine. It is difficult to change it into an albuminate by the action 
of acids and alkalies. 
Appendix: Vegetable Proteid Bodies.—Plants, like animals, contain proteid bodies, 
although in less amount. They occur either in solution in the juices of living plants or in the 
solid form. In composition and reaction they resemble animal proteids. 
[The characters of vegetable proteids have a great resemblance to animal proteids. They 
have frequently been obtained in a crystalline form, e.g., from the seeds of the gourd and various 
oleaginous seeds. They occur in greatest bulk in the seeds of plants, aleurone grains being 
for the most part composed of them. In seeds, globulins and “vegetable peptone” form the 
greater proportion of the proteid constituents.] 
[Albumin.—The existence of a body corresponding to egg- or serum-albumin in the vegeta- 
ble kingdom is doubtful (Ritthausen). Such a body has been described in papaw juice 
(Mar/in).] 
[Globulins.—Three varieties have been described as occurring in the seeds of plants:— 
vegetable myosin, vitellin, and paraglobulin (Martin). They have practically the same 
properties as those found animal kingdom : vegetable vitellin has, however, not been suffi- 
ciently studied. Paraglobulin has been found in papaw juice (Martin). Myosin occurs in the 
seeds of leguminosse, in flour, and in the potato ] [Globulins aie by far the most abundant pro- 
teids in plants.] 
[Vegetable Peptone : Albumoses.—A true peptone has not yet been recognized in plants; 
what has been described as such is hemi-albumose ( Fines). Albumoses has been found in the 
seeds of leguminosse, in flour, and in papaw juice. In the last, two forms occur, called respec- 
tively a- and /J-phytalbumose. The former, a-phytalbumose, agrees with the hemi-albumose 
described by Vines, being soluble in cold and boiling water; giving also a biuret-reaction, and 
a precipitate by saturation with sodium chloride only in an acid solution. The latter, /3-phytal- 
bumose, is soluble in cold, but not in boiling, distilled water; hence it is precipitated by heat. 
It is also readily thrown down by saturation with sodium chloride, and gives a faint biuret 
reaction (Martin).') 
[Vegetable Casein is said to occur in the seeds of leguminosse; and it is slightly soluble in 
water, but readily so in weak alkalies and in solutions of basic calcic phosphate. A solution of 
this body is precipitated by acids and rennet. Two varieties have been described,—(a) legumin, 
in peas, beans, lentils ; acid in reaction, soluble in weak alkalies and very dilute HC1 or acetic 
acid;(/?) conglutin, a very similar body occurring in hops and almonds. The existence of 
vegetable casein is denied. Vines states that both legumin and conglutin are artificial products, 
being formed from the globulins present by the dilute alkali used in extraction of the proteids. 
This is denied by Ritthausen.] 
[Gluten.—Gluten is readily prepared from flour by washing and kneading it in a muslin bag 
under a stream of water. It is probably formed by the fermentation from the proteids pre- 
existing in flour. So prepared, it is yellowish-brown in color, very sticky, and capable of 
being drawn out into long shreds. Is is insoluble in water, soluble (but not completely) 
by prolonged action in dilute acids and alkalies (.2 per cent. KHO and HC1). The pro- 
longed action of alcohol (80 to 85 per cent.) dissolves part of the substance of gluten, leaving 
a residue, called by Liebig plant-fibrin and by Ritthausen gluten-casein. The alcohol contains 
gliadin (glutin), gluten-fibrin, and mucedin. Gluten-casein is readily soluble in dilute alka- 
lies, almost insoluble in dilute acetic acid, and quite insoluble in cold and boiling water; the pro- 
ducts of its decomposition, by heating with H2S04 are leucin, tyrosin, glutamic, and aspara- 
ginic acids. The three bodies dissolved from gluten by alcohol differ chiefly in their solubility 
in alcohol and water. Gluten-fibrin, the least soluble, is coagulated by the action of absolute 
alcohol; it is readily soluble in dilute acids and alkalies, being precipitated by neutralization. 
Gliadin (glutin, plant-gelatin) may be prepared by boiling gluten with water: it deposits on 
cooling the solution. Though soluble in water at ioo° C. at first, it becomes insoluble by the 
prolonged action of water at that temperature. It is, like gluten-fibrin, soluble in dilute acids 
and alkalies. Mucedin differs from gliadin in being less soluble in strong alcohol. The water 
used in washing the flour in the preparation of gluten contains hemi albumose (Vines) and a 480 
ALBUMINOIDS AND FERMENTS. 
[Sec. 249. 
globulin (Weyl). Rye-flour, as well as wheaten, yields gluten under similar treatment with 
water.] 
[Nitrogenous Crystalline Principles.—Leucin, tyrosin, asparagin, and glutamic acid have 
been found in the seeds of plants.] 
Poisonous Proteids.—Many of the proteids are poisonous, and some of 
them are the products of the metabolic activity of micro-organisms, which 
seem to play an important part in the causation of disease. Amongst poison- 
ous animal-proteids are those of snake-poison, e.g., of the cobra and viper 
which contain [-tox-albumins, -globulins, and -albumoses; the proteids in the 
serum of the conger eel and other fishes (p. 46), and the albumoses and pep- 
tones produced during digestion. Some of the products obtained by cultivat- 
ing specific bacilli in a culture fluid containing proteid, when injected into an 
animal, may render that animal immune against an attack of certain diseases. 
Hankin has shown that an albumose is capable of protecting animals against 
splenic fever. These bodies are called “ protective proteids.”] 
250. (2) THE ALBUMINOIDS AND FERMENTS.—These sub- 
stances closely resemble true proteids in their composition and origin, and are 
amorphous non-crystalline colloids; some of them do not contain S, but the 
most of them have not been prepared free from ash. Their reactions and de- 
composition-products closely resemble those of the proteids; some of them pro- 
duce, in addition to leucin and tyrosin, glycin and alanin (amido-propionic 
acid). They occur as organized constituents of the tissues and also in fluid 
form. It is unknown whether they are formed by oxidation from proteid 
bodies or by synthesis. 
1. Mucin is the characteristic substance present in mucus. That obtained from the sub- 
maxillary gland contains—C 52.31, H 7.22, N 11.84, O 28.63. According to Hammarsten, it 
contains S 1.79 and N 13.5 per cent. It dissolves in water, making it sticky or slimy, and can 
be filtered. It is precipitated by acetic acid and alcohol; and the alcohol precipitate is again 
soluble in water. It is not precipitated by acetic acid and ferrocyanide of potassium, but HN03 
and other mineral acids precipitate it. It gives the xanthoproteic reaction, and becomes 
red with Millon’s reagent. Occurrence.—It occurs in saliva (§ 146), in bile, in mucous glands, 
secretions of mucous membranes, in mucous tissue, in synovia, and in tendons. [The mucin- 
like body occurring in synovia, which renders synovia viscous, is said by Hammarsten not to 
be true mucin, but a nucleo-albumin containing 5 per cent, of phosphorus.] Pathologically 
it occurs not unfrequently in cysts; in the animal kingdom, especially in snails and in the 
skin of holothurians. It yields leucin and 7 per cent, of tyrosin when it is decomposed by 
prolonged boiling with sulphuric acid. Mucin behaves like a glucoside; under the action 
of dilute mineral acids at a high temperature, it splits up into an albuminous body and a 
carbohydrate (Lcebisch). [The precipitate called mucin has not always the same characters, 
and, in fact, it differs according to the animal from which it is obtained (Landwehr). The so- 
called mucin of bile is probably a nucleo-albumin (§ 177).] 
2. Nuclein (§ 24).—Miescher gives the formula C29H49N9P3022—contains phosphoric acid, 
which cannot be separated from it in the cold by dilute neutral acids. It is slightly soluble in 
water, easily in ammonia, alkaline carbonates strong HN03. It occurs in the nuclei of pus 
and blood-corpuscles (§ 22), in spermatozoids, yelk-spheres, liver, brain, and milk, yeast, fungi, 
and many seeds. It has resemblances to mucin, and is perhaps an intermediate product between 
albumin and lecithin (Hoppe-Seyler). It is prepared by the artificial digestion of pus, when it 
remains as an indigestible residue; acids precipitate it from an alkaline solution. It gives a 
feeble xanthoproteic reaction; after the prolonged action of alkalies and acid, substances 
similar to albumin and syntonin are formed. Hypoxanthin and guanin have been obtained as 
decomposition products from it (Kossel). [A product intermediate between nuclein and hypo- 
xanthin is adenin.] 
3. Keratin occurs in all horny and epidermic tissues (epidermic scales, hairs, nails, feathers) 
—C 50.3-52.5, H 6.4-7, N 16.2-17, O 20.8-25, S 0.7-5 Per cent.—is soluble in boiling caustic 
alkalies, but swells up in cold concentrated acetic acid. When decomposed by H2S04 it yields 
10 per cent, leucin and 3.6 per cent, tyrosin. Neuro-keratin (§ 321). 
4. Fibroin is soluble in strong alkalies and mineral acids, in ammonio-sulphate of copper; 
when boiled with H2S04 it yields 5 per cent, tyrosin, leucin, and glycin. It is the chief con- 
stituent of the cocoons of insects and threads of spiders. Sec. 250.J 
481 
GELATIN AND CHONDRIN. 
5. Spongin, allied to fibroin, occurs in the bath-sponge, and yields, as decomposition-pro- 
ducts, leucin and glycin (Stadeler). 
6. Elastin, the fundamental substance in elastic tissue, is soluble only when boiled in con- 
centrated caustic potash—C 55-55-6, H 7.1-7.7, N 16.1-17.7, O 19.2-21.1 per cent. It yields 
36 to 45 per cent, of leucin and l/2 per cent, of tyrosin. [When elastin is digested, elastoses 
are formed ] 
7. Gelatin (Glutin), obtained from connective-tissues by prolonged boiling with water; 
it gelatinizes in the cold—C 52.2-50.7, H 6.6-7.2, N 17.9-18.8, S -f- O 23.5-25 (S 0.7 per 
cent.). [Some authors state that it contains no sulphur.] [The ordinary connective-tissues are 
supposed to contain the hypothetical anhydride collagen, while the organic basis of bone is 
called ossein.] It rotates the ray of polarized light strongly to the left = — 130°- By pro- 
longed boiling and digestion, it is converted into a peptone-like body (gelatin-peptone), which 
does not gelatinize (§ 161, I). [It swells up, but does not dissolve in cold water; when dis- 
solved in warm water, and tinged with Berlin blue or carmine, it forms the usual colored mass 
which is employed by histologists for making fine transparent injections of blood-vessels.] A 
body resembling gelatin is found in leuksemic blood and in the juice of the spleen ($ 103, I). 
When decomposed with sulphuric acid it yields glycin, ammonia, leucin, but no tyrosin. [It is 
precipitated from its solution by alcohol, mercuric chloride, metaphosphoric acid, phospho- 
tungstic acid, taurocholic acid, tannic acid, but the precipitate with the last does not occur when 
salts are absent. It is readily soluble in dilute acids, even in acetic acid. When boiled with 
Millon’s reagent, it is not colored red. With cupric sulphate and caustic soda it gives a violet 
color, which, on boiling, becomes light red. It gives no color with concentrated H2S04 and 
acetic acid.] 
[Gelatin, when treated with superheated steam or digested, yields intermediate bodies, analo- 
gous to the proteoses, and finally a gelatin-peptone is formed (§ 166, III), which, however, 
differs from proteid-peptone as follows (Salkowski):— 
Proteid Peptone. 
Gelatin. 
Gelatin-Peptone. 
Adamkiewicz’ reaction, 
Addition of an equal 1 
Violet. 
Yellowish. 
Yellowish. 
volume of concentrated > 
Dark brown. 
Yellow. 
Yellow. 
H2so4, J 
Millon’s reaction, .... 
Reddish precipi- 
tate. 
Colorless. 
Colorless. 
Xanthoproteic reaction, 
Deep yellow. 
Lemon-yellow. 
Lemon-yellow.] 
[According to the analysis of Hofmeister, the percentage composition of the gelatinous sub- 
stances varies within the following limits :— 
Gelatin from bone. 
Chondrin. 
Albumin. 
Carbon, 
49-3 - 5°-8 
47.7-5°.2 
50.O-55.O 
Hydrogen, 
6.5- 6.6 
6.6- 6.8 
6.6- 7.3 
Nitrogen, 
17.5-18.4 
13.9-X4.1 
15.0-19.0 
Sulphur, 
0.56? 
0.4 - 0.6 ? 
0.3- 2.4 
Oxygen, 
24.9 - 26.0 
29.0-51.0 
19.0-24.0] 
8. Chondrin occurs in the matrix of hyaline cartilage and between the fibres in fibro-car- 
tilage. It is obtained from hyaline cartilage and the cornfea by boiling. [Its solutions gelati- 
nize on cooling.] It occurs also in the mantle of molluscs—C 49.5-50.6, H 6.6-7.1, N 14.4- 
14.9, S -f- O 27.2-29 (S 0.4 per cent.). When boiled with sulphuric acid it yields leucin; 
with hydrochloric acid, and when digested, chondro glucose (Meissner); it belongs to the 
glucosides which contain N. When acted upon by oxidizing reagents it is converted into gelatin 
(.Brame). The substance which yields chondrin is called chondrigen, which is perhaps an 
anhydride of chondrin. The following properties of gelatin and chondrin are to be noted:— 
Gelatin is precipitated by tannic acid, mercuric chloride, chlorine water, platinic chloride, 
and alcohol, but not by acids, alum, or salts of silver, iron, copper, or lead; its specific rotation 
is = — 130°. [Compare these precipitants with those of albumin.] Chondrin is precipitated 
by acetic acid and dilute sulphuric and hydrochloric acids, by alum, and by salts of silver, iron, 
and lead; its specific rotation — — 213°. 482 
[Sec. 250. 
HYDROLYTIC FERMENTS. 
[The following table after Halliburton shows the chief reactions of chondrin 
compared with those of mucin and of gelatin : — 
Chondrin. 
Gelatin. 
Mucin. 
Solubilities. 
Insoluble in cold water, 
alcohol, or ether. 
Soluble in hot water; 
such solutions set 
into a jelly when 
cold. 
Insoluble in cold 
water, alcohol, or 
ether. 
Soluble in hot water; 
such solutions set 
into a jelly when 
cold. 
Insoluble in cold 
water, alcohol, or 
ether. 
Insoluble in hot 
water. 
Acetic acid. 
Gives a precipitate in- 
soluble in excess. 
Gives no precipitate. 
Gives a precipitate 
insoluble in excess. 
Mineral acids. 
Give a precipitate solu- 
ble in excess. 
Give no precipitate. 
Give a precipitate 
soluble in excess. 
Tannic acid. 
Gives a precipitate. 
Gives a precipitate. 
Gives no precipitate. 
Mercuric chloride. 
Gives a precipitate. 
Gives a precipitate. 
Gives no precipitate. 
Lead acetate. 
Gives a precipitate. 
Gives no precipitate. 
Gives a precipitate. 
Alum. 
Gives a precipitate. 
Gives no precipitate. 
Gives a precipitate. 
When decomposed by 
A reducing sugar is 
No reducing sugar is 
A reducing sugar is 
boiling with dilute 
mineral acids. 
formed. 
formed. 
formed. 
so that chondrin possesses the reactions of gelatin and also those of mucin.] 
[9. Nucleo-albumins are compounds of proteids (usually globulins) and 
nuclein, and occur in cell-protoplasm. The mucin-like substance in bile is a 
nucleo-albumin (§ 177).] 
10. The hydrolitic ferments have recently been called enzymes by W. 
Kiihne, in order to distinguish them from organized ferments, such as yeast. 
The enzymes, hydrolytic or organic ferments, act only in the presence of water. 
They act upon certain bodies, causing them to take up a molecule of water. 
They all decompose hydric peroxide into water and O. They are most active 
between 30° to 350 C., and are destroyed by boiling, but when dry they may 
be subjected to a temperature of ioo° without being destroyed. Their solu- 
tions, if kept for a long time, gradually lose their properties, and undergo 
more or less decomposition. [It has been proposed to apply the term zymo- 
lysis to the action of this group of ferments (S. Lea).'] 
(a) Sugar-forming, amylolytic, or diastatic-ferment occurs in saliva 
(§ 148), pancreatic juice (§ 170), intestinal juice (§ 183), bile (§ 180), blood 
(§ 22), chyle (§ 108), liver (§ 174), and human milk (§ 231). Invertin in 
intestinal juice (§ 183). Almost all dead tissues, organic fluids, and even pro- 
teids, although only to a slight degree, may act diastatically. Diastatic fer- 
ments are very generally distributed in the vegetable kingdom, the best example 
being diastase. 
(.b) Proteolytic, or ferments which act upon proteids.—Pepsin in 
gastric juice and in muscles'(§ 166), in vetches, myxomycetes (.Krukenberg), 
trypsin in the pancreatic juice (§170), a similar ferment in the intestinal juice 
(§ 183), and urine (§ 264). 
(e) Fat-decomposing in pancreating juice (§170), in the stomach (§ 166). 
(d) Milk-coagulating rennet, or rennin, in the stomach (§ 170), and 
perhaps also in the intestinal juice (?)—( W’. Roberts). 
[(<?) There are, however, other ferments, e.g., coagulative ferments, e.g., 
fibrin ferment, myosin ferment, and a ferment from Withania coagulans.] 
[The importance of fermentative processes has already been referred to 
in detail under “Digestion.” Ferments are bodies which excite chemical Sec. 250.] 
UNORGANIZED FERMENTS. 
483 
changes in other matter with which they are brought into contact, without 
apparently undergoing any change themselves, or at least they do not enter into 
the composition of the final product. They are divided into two classes :— 
(1) Unorganized; soluble or non-living. 
(2) Organized, or living.] 
[(1) The Unorganized Ferments are those mentioned in the following 
table. They seem to be nitrogenous bodies, although their exact composition 
is unknown, and it is doubtful if they have ever been obtained perfectly pure. 
They are present in many secretions, and are produced within the body by the 
vital activity of the protoplasm of cells. They are termed soluble because they 
are soluble in water, glycerin, and some other substances (§ 148), while they 
can be precipitated by alcohol and some other reagents. They do not multi- 
ply during their activity, nor is their activity prevented by a certain proportion 
of salicylic acid. They are not affected by oxygen subjected to the compres- 
sion of many atmospheres (P. Bert). They are non-living. Their other prop- 
erties are referred to above.] 
[The unorganized ferments present in the body, and their actions ( W. 
Roberts): — 
Fluid or Tissues. 
Ferment. 
Actions. 
Saliva, .... 
I. Ptyalin (■$ 148), .... 
Converts starch chiefly into maltose. 
f 
1 
Gastric juice, -j 
1 
L 
1. Pepsin, | 
2. Milk curdling, .... 
| 3. Lactic acid ferment, . . 
4. Fat-splitting (?), . . . . 
Converts proteids into peptones in an acid 
medium, certain bye-products being 
formed ($ 166). 
Curdles casein of milk. 
Splits up milk-sugar into lactic acid. 
Splits up fats into glycerin and fatty acids. 
r 
Pancreatic 
juice, 
l 
X. Diastatic or amylopsin, . 
2. Trypsin, j 
3. Emulsive (?), 
4. Fat-splitting or steapsin, 
5. Milk-curdling, .... 
Converts starch chiefly into maltose. 
Changes proteids into peptones in an alka- 
line medium, certain bye-products being 
formed (§ 170). 
Emulsifies fats. 
Splits fats into glycerin and fatty acids. 
Curdles casein of milk. 
Intestinal 
juice, 
1. Diastatic, | 
! 2. Proteolytic, 
3. Invertin, 
4. Milk-curdling, .... 
Does not form maltose, but maltose is 
changed into glucose (§ 183). 
Changes fibrin into peptone (?). 
Changes cane- into grape-sugar. 
(? in small intestine). 
Blood, . . . 
Chyle, . . . 
Liver (?), . . 
Milk, . . . . 
Most tissues, . 
- 
' 
■ Diastatic ferments. 
Muscle, . . . 
Urine, . . . 
- Pepsin and other ferments. 
Blood,.... 
Fibrin ferment. 
[(2) The Organized or living ferments are represented by yeast (§ 235). 
Other living ferments belonging to the schizomycetes, occurring in the intes- 
tinal canal, are referred to in § 184. Yeast causes fermentation by splitting up 
sugar into C02 and alcohol (§ 150), but this result only occurs so long as the 
yeast is living. Hence, its activity is coupled with the vitality of the cells of 484 
[Sec. 250. 
COLORING MATTERS. 
the yeast. If yeast be boiled, or if it be mixed with carbolic or salicylic acid, 
or chloroform, all of which destroy its activity, it cannot produce the alco- 
holic fermentation. As yet no one has succeeded in extracting from yeast a 
substance which will excite the alcoholic fermentation. All the organized fer- 
ments grow and multiply during their activity at the expense of the substances 
in which they occur. Thus the alcoholic fermentation depends upon the 
“life” of the yeast. They are said to be killed by oxygen subjected to the 
compression of many atmospheres (P. Bert). But it is important to note that 
Hoppe-Seyler has extracted from dead yeast (killed by ether) an unorganized 
ferment—invertin—which can change cane-sugar into grape-sugar.] 
n. Haemoglobin, the coloring-matter of blood, which, in addition to C, 
H, O, N, and S, contains iron, may be taken with the albuminoids or with the 
pigments (§ n). [Haemocyanin (§ 32).] 
(3) Glucosides containing Nitrogen. 
In addition to chondrin, the following glucosides containing nitrogen, 
when subjected to hydrolytic processes, may combine with water, and form 
sugar and other substances :—- 
Cerebrin ($ 322) = C57H1]0N2O25 (Geoghegan). [Parcus has shown that cerebrin as origin- 
ally prepared by W. Miiller is a mixture of three bodies, viz., cerebrin, homocerebrin, and 
encephalin.] 
Protagon—C 66.29, H 10.69, N 2.39, P 1.068 per cent, [empirical formula, C160H308N5PO35] 
—occurs in nerves, and contains phosphorus ($ 322). 
Chitin, 2(Cj5H26N2O10), is a glucoside containing nitrogen, and occurs in the cutaneous 
coverings of arthropoda, and also in their intestine and tracheae; it is soluble in concentrated 
acids, e.g., hydrochloric or nitric acid, but insoluble in other reagents. According to Sandwick, 
chitin is an amin-derivative of a carbohydrate with the general formula n(C12H20O10). The 
hyalin of worms is closely related to chitin. (Solanin, amygdalin (§ 202), and salicin, etc., are 
glucosides of the vegetable kingdom.) 
(4) Coloring Matters containing Nitrogen. 
Their constitution is unknown, and they occur only in animals. They are 
in all probability derivatives of haemoglobin. They are—(1) Haemoglobin 
with its derivatives: haematin (§ 18, A), myohaematin (§ 233, § 292), 
histo-haematin (§ 103, IV.), and haematoidin (§ 20). (2) Bile-pigments 
(§ 177, 3)- (3) Urine-pigments (except Indican). (4) Melanin—C44.2, 
H3, N9.9, 042.6—or the black pigment which occurs partly in epithelium 
(choroid, retina, iris, and in the deep layers of epidermis in colored races) and 
partly in connective-tissue corpuscles (Lamina fusca of the choroid). [It is 
probable that there are several melanins.] [Turacin occurs in the red feathers 
of Corythaix Buffoni, Cape lory, or Plantain-Eater. Its ash contains nearly 6 
per cent, of copper (Church). The reddish spots or parts of feathers burn with 
a green flame.] 
(5) Coloring Matters containing no Nitrogen. 
[The lipochromes are fatty pigments, and are very numerous. They are 
soluble in ether, and alcohol-like fats, they give certain absorption bands in the 
spectrum and yield color-reactions with iodine or sulphuric acid, or with both 
these reagents together (§ 384). Amongst them are lutein, the yellow pig- 
ment of the corpus luteum, tetronerythrin, the red pigment in the shell of 
crustaceans (§ 32), the chromophanes of the retinal cones (§ 384), and 
visual purple (§ 384).] 
II. Organic Acids free from Nitrogen. 
(1) The fatty acids, with the formula CnH2n_10(0H), occur in the body 
partly free and partly in combination. Free volatile fatty acids occur in de- Sec, 250.] 
NEUTRAL FATS. 
485 
composing cutaneous secretions (sweat). In combination, acetic acid and 
caproic acid occur as amido-compounds in glycin (= amido-acetic acid) and 
leucin (= amido-caproic acid). More especially do they occur united with 
glycerin to form neutral fats, from which the fatty acid is again set free by 
pancreatic digestion (§ 170, III). 
(2) The acids of the acrylic acid series, with the formula CnH2n-30(HO), are represented 
in the body by one acid, oleic acid—C18H3402—which in combination with glycerin yields the 
neutral fat olein. 
♦ 
251. Fats.—(1) Neutral fats occur very abundantly in animals, but they 
also occur in all plants; in the latter more especially in the seeds (nuts, 
almonds, cocoanut, poppy), more rarely in the pericarp (olive) or in the root. 
[The chief neutral fats found in the body are tripalmitin, C3H5(0.C]6H310)3, 
tristearin C3H5(0.C18H350)3 are solid fats and are held in solution at the 
temperature of the body by triolein, C3H5(0.C18H330)3. Tributyrin, 
C3H5(0.C4H70)3 is found in butter.] They are obtained by pressure, melting, 
or by extracting them with ether or boiling alcohol. They contain much less 
O than the carbohydrates, such as sugar and starch; they give a greasy spot on 
paper, and when shaken with colloid substances, such as albumin, they yield 
an erpulsion. When treated with superheated steam or with certain ferments 
(p. 307, III), they take up water and yield glycerin and fatty acids, and 
if the latter be volatile they have a rancid odor. Treated with caustic alkalies 
they also take up water,‘and are decomposed into glycerin and fatty acids; the 
fatty acid unites with the alkali and forms a soap, while glycerin is set free. 
The soap-solution dissolves fats. 
[The following table from Halliburton indicates some of the differences 
between the neutral fats of the body :— 
Stearin. 
Palmitin. 
Olein. 
C18H350)3. 
Melting-point.—53°-66° C. 
Solubilities.—Nearly insoluble 
in cold alcohol and ether. 
Soluble in both when hot. 
Remarks.—The chief consti- 
tuent of the more solid fats 
(like mutton suet). 
It crystallizes from alcohol in 
brilliant quadrangular plates. 
C3H5(0.C16H310)3. 
45° C. 
More soluble than stearin in 
both hot and cold alcohol 
and ether. 
More abundant in the adi- 
pose tissue of man than 
stearin. 
It crystallizes in fine 
needles. 
C.3H5(0. C18H330)3. 
o° C. 
Easily soluble in both hot 
and cold alcohol and 
ether. 
Dissolves all the solid fats, 
especially at 30° C, or 
above; it is thus this fat 
which holds the other two 
in solution at the tempera- 
ture of the body. 
Glycerin is a tri-atomic alcohol, C3H5(OH)3, and unites with (i) the following monobasic 
fatty acids (those occurring in the body are printed in italics):— 
I. 
Acids. 
Formic, . 
. ch2o2 
2. 
Acetic, .... 
3- 
Propionic, 
• Qm6o2 
4- 
Butyric, . . . 
■ C4Hg02 
[Isobutyric, 
• c4h8o2] 
5- 
Valerianic, . 
• c5n10o2 
6. 
Caproic, . . . 
• 
7- 
Acids. 
(Enanthylic, . 
• 
8. 
Caprylic, . . 
• c8h16o2 
9- 
Pelargonic, . 
■ c9H18o2 
IO. 
Capric, . . . 
• 
ii. 
Laurostearic, 
• C12H24°2 
I 2. 
Myristic, . . 
• 
13- 
Palmitic, . . 
Acids. 
[Margaric, . . 
CnH3402, 
is a mixture 
of 13 and 14.] 
14- 
Stearic, .... 
*5- 
Arachinic, . .. 
c20h40o2 
i6. 
Hyanic, . . . 
17- 
Cerotinic, . . . 
The acids form a homologous series with the formula CnH2n_10(0H). With every CH2 
added their boiling-point rises 190. Those containing most carbon are solid, and non-volatile ; 
those containing less C (up to and including 10) are fluid like oil, have a burning acid taste, 
and a rancid odor. The earlier members of the series may be obtained by oxidation from the 
later, by CH2 being removed, while C02 and H20 are formed; thus, propionic acid is obtained 
from butyric acid. Nos. 13 and 14 are found in human and animal fat, less abundant and more 486 
THE FATTY AND OTHER ACIDS. 
[Sec. 251. 
inconstant are 12, n, 6, 8, io, 4. Some occur in sweat (§ 287) and in milk (f 231). Many of 
them are developed during the decomposition of albumin and gelatin. Most of the above 
(except 15 and 17) occur in the contents of the large intestine (§ 185). 
(2) Glycerin also unites with the monobasic oleic acid, which also forms a series, whose 
general formula is CnH2n_30(0H); and they all contain 2H less than the corresponding 
members of the fatty acid series. The corresponding fatty acids can be obtained from the oleic 
acid series and vice versa. Oleic acid (olein-elainic acid), C18H3402, is the only one found in 
the organism; united with glycerin, it forms the fluid fat, olein. The fat of new-born children 
contains more glyceride of palmi'ic and stearic acid than that of adults, which contains more 
glyceride of oleic acid. Oleic acid also occurs united with alkalies (in soaps) and (like some 
fatty acids) in the lecithins ($ 23). If lecithin be acted on with barium hydrate, we obtain 
insoluble stearic, or oleic, or palmitic acids and barium oleate, together with dissolved neurin 
($ 322, b) and baric glycero phosphate. Lecithin is regarded as glycero-phosphate of neurin, in 
which in the radical of glycero-phosphoric acid 2 atoms H are replaced by 2 of stearic, 
palmitic, or oleic acids. It appears as if there were several lecithins, of which the most abun- 
dant are the one with stearic acid and that with palmitin -(- oleic acid radical (Diakonow). 
Lecithin occurs in the blood-corpuscles (§ 23), semen, and nerves. Neurin is constantly present 
in fungi. 
The neutral fats [palmitin, stearin (both solid), and olein (fluid)], the glycerides of fatty 
acids, and of oleic acid, are triple ethers of the triatomic alcohol glycerin. With the neutral fats 
may be associated glycero-phosphoric acid, an acid glycerin ether, formed by the union of 
glycerin and phosphoric acid, with the giving off of a molecule of water (C3H9P06); it is a 
decomposition-product of lecithin ($ 23). 
(3) The glycolic acids (acids of the lactic acid series) have the formula CnH2n_.20(0H)2. 
They are formed by oxidation from the fatty acid series by substituting OH (hydroxyl) for one 
atom of H of the fatty acids. Conversely, fatty acids may be obtained from the glycolic acids. 
The following acids of this series occur in the body:— 
(«) Carbonic Acid (oxy-formic acid), CO(OH)2; in this form, however, it forms salts only. 
Free carbonic acid or carbon dioxide is an anhydride of the same = C02. 
(b) Glycolic Acid (oxy-acetic acid), C2H20(0H)2 does not occur free in the body. One of 
its compounds, glycin (glycocoll, amido acetic acid, or gelatin-sugar),occurs as a conjugate acid, 
viz., as glycocholic acid in the bile (§ 177,2), and as hippuric acid in the urine (§ 260). Glycin 
exists in complex combination in gelatin. 
(r) Lactic Acid (oxy-propionic acid), C3H40(0H)2, occurs in the body in two isomeric forms 
— 1. The ethylidene lactic acid, which occurs in two modifications—as the right rotatory 
sarcolactic acid (paralactic), a metabolic product of muscle; and as the ordinary optically 
inactive product of “ lactic fermentation,” which occurs in gastric juice, in sour milk (sauerkraut, 
acid cucumber), and can be obtained by fermentation from sugar (§ 184). 2. The isomer, 
ethylene-lactic acid, occurs in the watery extract of muscles ($ 293). 
(d) Leucic Acid (oxy-caproic acid), C6H1203, does not occur as such, but only in the form of 
one of its derivatives, leucin (amido-caproic acid), as a product of the metabolism in many 
tissues, and is formed during pancreatic digestion (§ 170, II). Leucic acid may be prepared 
from leucin, and glycolic acid from glycin, by the action of nitrous acid. 
(4) Acids of the Oxalic Acid or Succinic Acid Series, having the formula CnH2a_ 
402(0II)2, are bi-basic acids, which are formed as completely oxidized products by the oxidation 
of fatty acids and glycolic acid, water being removed. It is important to note their origin from 
substances rich in carbon, e. g., fats, carbohydrates, and proteids. 
(а) Oxalic Acid, C202(OH)2, arises from the oxidation of glycol, glycin, cellulose, sugar, 
starch, glycerin, and many vegetable acids—it occurs in the urine as calcium oxalate 
(2 260). 
(б) Succinic Acid, C4H402(0Ii)2, has been found in small amount in animal solids and fluids, 
spleen, liver, thymus, thyroid; in the fluids of echinococcus, hydrocephalus, and hydrocele, and 
more abundantly in dog’s urine after fatty and flesh food; in rabbit’s urine after feeding with 
yellow turnips. It is also formed in small amount during alcoholic fermentation (§ 150). 
(5) Cholalic Acid in the bile (§ 177) and in the intestine ($ 182). 
(6) Aromatic Acids contain the radical of benzol. [Benzene or benzol, with the formula 
06H6, is the origin of the aromatic group, so called because many of the derivatives of this 
body have aromatic properties. One or more of the atoms of hydrogen can be replaced by 
more or less complicated radicals.] Benzoic Acid (= phenyl-formic acid) occurs in urine 
united with glycin, as hippuric acid (£ 266). Sec. 251.] 
CARBOHYDRATES. 
487 
III. Alcohols. 
Alcohols are bodies which originate from carbohydrates, in which the radi- 
cal hydroxyl (HO) is substituted for one or more atoms of H. They may be 
H 1 
also regarded as water, M [• O, in which the half of the H is replaced by a 
. C H ) 
CH compound. Thus, C2H6 (ethyl-hydride) passes into 2W5 > O (ethylic 
alcohol). 4 
C H 
(a) Cholesterin, 26pj43 > O, is a true monatomic alcohol, and occurs in blood, yolk, brain, 
bile (§ 177, 4), and generally in vegetable cells; it is the only solid monatomic alcohol in the 
body. f OH 
(b) Glycerin, C3H5-j OH, is a triatomic alcohol. It occurs in neutral fats united with fatty 
(OH 
acids and oleic acid; it is formed by the splitting up of neutral fats during pancreatic digestion 
(j$ 170, III), and during the alcoholic fermentation ($ 150). 
(f) Phenol ( = phenylic acid, carbolic acid, oxy-benzol) ($ 184, III). 
(d) Pyrokatechin (— dioxybenzol) (§ 252). 
The Sugars are closely related to the alcohols, and they may be regarded as polyatomic 
alcohols. Their constitution is unknown. Together with a series of closely-related bodies they 
form the great group of the carbohydrates, some of which occur in the animal body, while 
others are widely distributed in the vegetable kingdom. 
252. THE CARBOHYDRATES.—Occur in plants and animals, and 
receive their name, because in addition to C (at least 6 atoms), they contain 
H and O, in the proportion in which these occur in water. They are all solid, 
chemically indifferent, and without odor. They have either a sweet taste 
(sugars), or can be readily changed into sugars by the action of dilute acids ; 
they rotate the ray of polarized light either to the right or left; as far as their 
constitution is concerned, they may be regarded as fatty bodies, or as hexa- 
tomic alcohols, in which 2H are wanting. 
Small quantities of carbohydrates occur in nearly all animal tissues. Under certain conditions 
of nutrition, there is reason to believe that complex organic constituents of our tissues, e. g., pro- 
teids, split up into a nitrogenous body from which urea is readily formed, and a non-nitrogenous 
carbon-containing residue, and from the latter fat or carbohydrates may be formed (§ 241). Car- 
bohydrates are formed from fats in the germination of oleaginous seeds, oxygen being absorbed 
in the process. 
They are divided into the following groups :— 
I. Division.—Glucoses (C6II1206).—(1) Grape-sugar (glucose, dextrose, or diabetic sugar) 
occurs in minute quantities in the blood, chyle, muscle, liver (?), urine, and in large amount in 
the urine in diabetes mellitus (§ 175). It is formed by the action of diastatic ferments upon 
other carbohydrates, during digestion. In the vegetable kingdom it is extensively distributed 
in the sweet juices of many fruits and flowers (and thus it gets into honey). It is formed from 
cane-sugar, maltose, dextrin, glycogen, and starch, by boiling with dilute acids. It crystallizes 
in warty masses with one molecule of water of crystallization; unites with bases, salts, acids, 
and alcohols, but is easily decomposed by bases; it reduces many metallic oxides (§ 149). 
Fresh solutions have a rotatory power of -f- 1060. By fermentation with yeast it splits up into 
alcohol and C02 ($ 150); with decomposing proteids it splits up into 2 molecules of lactic acid 
(| 184, I); the lactic acid splits up under the same conditions in alkaline solutions, into butyric 
acid, C02 and H. For the qualitative and quantitative estimation of glucose, see \ 149 and 
\ 150. In alcoholic solution, it forms very insoluble compounds with chalk, barium, and potas- 
sium, and it also forms a crystalline compound with common salt (Estimation, \ 150). 
(2) Galactose, obtained by boiling milk-sugar (lactose) with dilute mineral acids; it 
crystallizes readily, is very fermentable, and gives all the reactions of glucose. When oxidized 
with nitric acid it becomes transformed into mucic acid. Its specific rotatory power = 
+ 88.08°. 
(3) Laevulose (left- fruit-, invert-, or mucin-sugar) occurs as a colorless syrup in the acid 
juices of some fruits and in honey; is non-crystallizable, and insoluble in alcohol; specific rota- 
tory power = — 1060. It is formed normally in the intestine ($ 183), and occurs rarely as a 
pathological product in urine. 
II. Division.—This contains carbohydrates with the formula C12H22On, and its members may 
be regarded as anhydrides of the first division—1. Milk-sugar or lactose occurs only in milk, 488 
GLYCOGEN AND ALLIED BODIES. 
[Sec. 252. 
crystallizes in cakes (with I molecule of water) from the syrupy concentrated whey; It rotates 
polarized light to the right = -f- 59.3, and is much less soluble in water and alcohol than grape- 
sugar. When boiled with dilute mineral acids it passes into galactose, and can be directly 
transformed into lactic acid only by fermentation ; the galactose, however, is capable of under- 
going the alcoholic fermentation with yeast (Koumiss preparation, $ 231). For its quantitative 
estimation (g 231). Rare in urine (§ 267). 
2. Maltose (C12H22On) H20 {O'Sullivan) has 1 molecule of water less than grape-sugar 
(C12H240i2), is formed during the action of a diastatic ferment, such as saliva upon starch 
(§ 148); is soluble in alcohol, right-rotatory power = + 150°; it is crystalline, while its reduc- 
ing power is only two-thirds that of dextrose. [The ratio of the reducing power of maltose to 
that of glucose is 100 to 66.] 
3. Saccharose (cane-sugar) occurs in sugarcane and some plants; it does not reduce a 
solution of copper, is insoluble in alcohol, is right-rotatory and not capable of fermentation. 
When boiled with dilute acids, it becomes changed into a mixture of easily fermentable glucose 
(right-rotatory) and lsevulose (invert sugar, \ 183, 5, and \ 184, I, 7), which ferments with diffi- 
culty and is left-rotatory ($ 183). When oxidized with nitric acid, it passes into glucic acid and 
oxalic acid.) 
III. Division.—This contains carbohydrates, with the formula (C6H10O5)s, which may be 
regarded as anhydrides of the second division. 
1. Glycogen, with a dextro-rotatory power of 211°, does not reduce cupric oxide. It occurs 
in the liver ($ 174), muscles, many embryonic tissues, the embryonic area of the chick (Kiilz) in 
normal and pathological epithelium; in diabetic persons it is widely distributed; brain, pancreas, 
and cartilage; and in the spleen, pancreas, kidney, ovum, brain, and blood, together with a 
small amount of glucose (Pavy). It also occurs in the oyster and some of the molluscs (Bizio), 
and indeed in all tissues and classes of the animal kingdom. 
2. Dextrin was discovered by Limpricht in the muscles of the horse. It is right-rotatory = 
-j- 138°, soluble in water, and forms a very sticky solution, from which it is precipitated by alco- 
hol or acetic acid; it is tinged red brown with iodine. It is formed in roasted starch, (hence it 
occurs in large quantity in the crust of bread—see Bread, $ 234), from starch by dilute acids, 
and in the body by the action of ferments (§ 148). It is formed from cellulose by the action of 
dilute or sulphuric acid. It occurs in beer, and is found in the juices of most plants. 
(3. Amylum or Starch occurs in the “ meally ” parts of many plants, is formed within 
vegetable cells, and consists of concentric layers with an eccentric nucleus (fig. 186). The 
diameter and characters of starch-grains vary greatly with the plant from which they are derived. 
At 720 C. it swells up in water and forms a mucilage; in the cold, iodine colors it blue. Starch- 
grains always contain more or less cellulose and a substance, erythrogranulose, which is 
colored red with iodine ($ 148). It and glycogen are transformed into dextrose by certain 
digestive ferments in the saliva, pancreatic, and intestinal juices, and artificially by boiling with 
dilute sulphuric acid.) 
(4. Gum, C10H20O10 occurs in vegetable juices (especially in acacias and mimosse), also in the 
salivary glands, mucous tissue, lungs, and urine ; is partly soluble in water (arabin), partly swells 
up like mucin (bassorin). Alcohol precipitates it. It is fermentable, and when boiled with 
dilute acid yields a reducing sugar.) 
(5. Inulin, a crystalline powder occurring in the root of chicory, dandelion, and specially in 
the bulbs of the dahlia; it is not colored blue by iodine.) 
(6. Lichenin occurs in the intercellular substance of Iceland moss (Cetraria islandica) and 
algae; is transformed into glucose by dilute sulphuric acid.) 
(7. Paramylum occurs in the form of granules resembling starch, in the infusorian, Euglena 
viridis.) 
(8. Cellulose occurs in the cell-walls of all plants (in the exo-skeleton of arthropoda, and 
the skin of snakes); soluble only in ammonio cupric oxide; rendered blue by sulphuric acid 
and iodine. Boiled with dilute sulphuric acid, it yields dextrin and glucose. Concentrated 
nitric acid mixed with sulphuric acid changes it (cotton) into nitro-cellulose (gun-cotton) 
C6H,(N02)305, which dissolves in a mixture of ether and alcohol and forms collodion. 
(9. Tunicin is a substance resembling cellulose, and occurs in the integument of the Tunicata 
or Ascidians.) 
IV. Division.—This contains the carbohydrates which do not ferment. 
1. Inosit—C6H1206—(phaseo-mannit, muscle-sugar) occurs in muscle [Scherer), lung, liver, 
spleen, kidney,brain of ox, human kidney; pathologically in urine and the fluid of echinococcus. 
In the vegetable kingdom, in beans (leguminosse), and the juice of the grape. It is an isomer of 
grape sugar; optically it is inactive, crystallizes in warts with 2 molecules of water, in long mono- 
clinic crystals; it has a sweet taste, is insoluble in water, does not give Trommer’s reaction, is 
capable of undergoing only the sarcolactic acid fermentation. (Nearly allied are Sorbin, from 
sorbic acid—Scyllit, from the intestines of the hag-fish and skate—and Eucalin, arising from 
the fermentation of melitose.) [Some authors however include these with the glucoses.] Sec. 252.] 
DERIVATIVES OF AMMONIA. 
489 
[Glycuronic acid, C6H10O7, seems to be related to the carbohydrates. It occurs in the urine 
as a potassium salt (C6H907K), and is found in large quantity in the urine after the administra- 
tion of chloral, chloroform, butyl-chloral, etc. It reduces alkaline solutions of copper, e. g., 
Fehling’s solution, and is apt, therefore, to be mistaken for dextrose ($ 262). It, however, does 
not undergo the alcoholic fermentation as dextrose does.] 
IV. Derivatives of Ammonia and their Compounds. 
The ammonia derivatives are obtained from the proteids, and are decomposition-products of 
their metabolism. 
(1) Amines, i. e. compound ammonias which can be obtained from ammonia (NH)3 or from 
ammonium-hydroxide (NH4—OH), by replacing one or all the atoms of H by groups of carbo- 
hydrates (alcohol radicals). The amine derived from one molecule of ammonia is called mona- 
mine. We are only acquainted with— 
II 
H 
CH3 
CH ' 
CH3 
ch3. 
Methylamine 
N 
and Tri-Methylamine 
N, 
as decomposition-products of cholin (neurin) and of kreatin. Neurin occurs in lecithin in a very 
complex combination (see Lecithin, p. 486, and also § 23). 
(2) Amides, i. e., derivatives of acids which have exchanged the hydroxyl (HO) of the acids 
for NH2 (Amidogen). Urea, CO(NH2)2, the biamid of C02, is the chief end-product of the 
metabolism of the nitrogenous constituents of our bodies (see Urine, $ 256). Carbon dioxide 
containing water = CO(OH)2, where both OH are replaced by NH2—thus we get CO(NH2)2, 
urea. 
(3) Amido-acids, i.e., nitrogenous compounds, which show partly the character of an acid 
and partly that of a weak base, jn which the atoms of H of the acid-radical are replaced by NH2, 
or by the substituted ammonia groups. 
(«) Glycin (or amido-acetic acid, glycocoll, gelatin-sugar, \ 177, 2) is formed by boiling 
gelatin with dilute sulphuric acid. It has a sweet taste (gelatin-sugar), behaves as a weak acid, 
but also unites with acids as an amine-base. It occurs as glycin -j- benzoic acid = hippuric acid, 
in urine ($ 260 and also as glycin -j- cholalic acid = glycocholic acid in bile ($ 177). Leucin 
—(| 170) = amido-caproic acid, (c) Serin—(== ? amido-lactic acid) obtained from silk-gelatin. 
(1d) Aspartic acid—(amido-succinic acid); and (<?) Glutamic acid, obtained by the splitting 
up of proteids (§ 170). Other amido-acids are—(/) Cystin = amido-lactic acid, in which Ois 
replaced by S (§ 268). Taurin—($ 177), amido-ethyl-sulphuric acid occurs (except in 
certain glands) chiefly in combination with cholalic acid, as taurocholic acid in bile. T.yrosin 
(parahydro-oxyphenyl-amido-propionic acid), an amido-acid of unknown constitution, occurs 
along with leucin during pancreatic digestion (§ 170), is a decomposition-product of proteids, and 
occurs plentifully in the urine in acute yellow atrophy of the liver (§ 269). 
To the amido-acids are related—(a) Kreatin in muscle, brain, blood, urine, regarded as 
methyl-uramido-acetic acid (C4H9N302). It has been prepared artificially. When boiled with 
baryta-water, it takes up H20, and splits into urea—and (b) Sarkosin (C3H7N02), methyl- 
amido-acetic acid. When boiled with water, or heated with strong acids, in the presence of 
putrefying substances, kreatin gives off water, and is changed into kreatinin (C4H7N30). This 
strong base can be rechanged by alkalies into kreatin. 
(4) Ammonia Derivatives of Unknown Constitution.—Uric acid (§ 258); allantoin 
(§ 260), is formed by the oxidation of uric acid by means of potassium permanganate ; cyanuric 
acid in dog’s urine; inosinic acid in muscle; guanin in traces in the liver and pancreas, in 
guano, the excrements of spiders, in the skin of amphibia and reptiles, in the silver sheen of many 
fishes [A. Ewald and Krukenberg); by oxidation it yields urea (p. 450); hypoxanthin or 
sarkin occurs along with xanthin in many organs and in urine. Kossel prepared hypoxanthin 
from nuclein by prolonged boiling of the latter. It may be obtained from fibrin by putrefaction, 
by gastric and pancreatic digestion, and by dilute acids [Salomon, H. Krause, Chittenden); 
xanthin is prepared by oxidation from hypoxanthin. It occurs very rarely in the form of a 
urinary calculus. Paraxanthin in urine, and a similar body carnin in flesh (§ 233). [Adenin 
(C5H5N5), discovered by Kossel in the pancreas, yeast, and tea-leaves, has also been isolated from 
the spleen, lymphatic glands, and kidney; it appears to be present in all highly cellular animal 
and vegetable tissues. Like the allied bases, xanthin and guanin, it is a derivative of the nuclein 
of the nuclei.] 
Aromatic Substances. 
1. Monatomic phenols—(a) Phenol (hydroxyl of benzol) in the intestine ($ 180). Phe- 
nylsulphuric acid in urine ($ 262). (£) Kresol, in the form of orthokresol and parakresol, 
united with sulphuric acid, occur in urine ($ 262). 2. Diatomic phenols—(a) pyrokatechin 
united with sulphuric acid in urine (§ 262). 3. Aromatic oxyacids—(«) Hydroparacu- 
maric acid; (b) Paraoxyphenylacetic acid in urine ($ 262). 4. Indol and skatol in the 490 
HISTORICAL AND COMPARATIVE. 
[Sec. 252. 
intestine (§ 184), conjoined with sulphuric acid in urine (§ 262). Skatol has been formed arti- 
ficially by distilling strychnia with lime (Stoehr). 
253. HISTORICAL.—According to Aristotle, the organism requires food for three purposes 
—for growth, for the production of heat, and to compensate for the loss of the bodily excreta. 
The formation of heat takes place in the heart by a process of concoction, the heat so formed 
being distributed to all parts of the body by means of the blood, while the respiration is regarded 
as an act whereby the body is cooled. Galen accepted this view in a somewhat modified form ; 
according to him, the metabolic processes may be compared to the processes going on in a lamp; 
the blood represents the oil; the heart, the wick; the lungs, the fanning apparatus. According 
to the view of the iatrochemical school (van Helmont), the metabolic processes of the body are 
fermentations, whereby the food is mixed with the juices of the body. Since the middle of the 
seventeenth century {Boyle), the knowledge of the metabolic processes has followed the develop- 
ment of chemistry. A. v. Haller regarded heat as due to chemical processes—the food con- 
tinually supplying the waste which is excreted from the body. After the discovery of oxygen 
(1774, by Priestley and Scheele), Lavoisier formulated the theory of combustion in the lungs, 
whereby carbonic acid and water are formed. Mitscherlich compared the decomposition-pro- 
cesses in the living body with putrefactive processes. Magendie was the first to emphasize the 
difference between nitrogenous and non-nitrogenous foods, and he showed that the latter alone 
were not able to support life. Even gelatin alone is not sufficient for this purpose. The greatest 
advance in the theory of nutrition was made by J. v. Liebig, who laid the foundation of our present 
knowledge of this subject. According to Liebig, foods may be divided into two classes, viz., the 
“ plastic,” suitable for the construction of the organism, and the “ respiratory ” for the main- 
tenance of the temperature ; to the former class he referred the albuminates or proteids ; to the 
latter, the non-nitrogenous carbohydrates and fats (p. 451). Amongst recent observers, the Mu- 
nich School, as represented by v. Bischoff, v. Pettenkofer, and v. Voit, has done most to give us 
an exact knowledge of this department of physiology. The Secretion of Urine. 
[Elimination of Waste Products.—We have seen that the tissues are 
nourished by the lymph, which contains the chemical compounds—proteids, 
carbohydrates, fats, salts, and gases—necessary for nourishing the tissues. As 
a result of the activity of the tissues, certain waste-products are formed which 
are removed from the tissues either by passing directly into the lymph-stream, 
by which they ultimately enter the blood,—or certain of these waste-products 
pass into the venous blood. In any case, the blood contains these waste- 
products and they must be got rid of, for if they accumulate to any great 
extent in the blood they injure the tissues. These matters are eliminated from 
the blood by various organs—called excretory organs—while the substances 
so excreted are called excretions.] 
[A complete acquaintance with all the facts of the case would enable us to 
trace step by step the various changes which the neutral substances undergo 
before they become effete products, but our acquaintance with what goes on in 
the economy does not enable us to do so completely. Speaking broadly, how- 
ever, the chief waste-products are urea, and certain closely allied nitrogenous 
bodies, carbon dioxide, salts, and water. These substances leave the body by 
one or other of three main channels. Much of the water, urea, and allied bodies, 
and the greater portion of the salts, are eliminated in the urine by the kidneys. 
These organs are of special importance, as nearly all the waste bodies contain- 
ing nitrogen are eliminated in the urine. Through the skin—in the sweat—is 
eliminated a large but variable quantity of water, a very small amount of salts, 
and a little carbon dioxide. The lungs serve as the chief channel for the elimi- 
nation of carbon dioxide and a considerable quantity of water in the form of 
aqueous vapor. 
[Besides these main channels the liver excretes substances in the bile, some 
of which are ultimately discharged, perhaps in a somewhat altered form, in 
the faeces. As we have seen, some of the undigested food is excreted by the 
bowel and along with it certain residues derived from the secretions poured into 
the intestinal canal. 
254. STRUCTURE OF THE KIDNEY.—[Capsule.—The kidney 
is a compound tubular gland, and is invested by a thin, tough, fibrous 
capsule, easily stripped off from the substance of the organ, to which it is 
attached by fine processes of connective-tissue and blood-vessels.] 
[Naked Eye Appearances.—On dividing the kidney longitudinally from 
the hilum to its outer border, and examining the cut surface with the naked 
eye, we observe the parenchyma of the kidney, consisting of an outer 
cortical and an inner medullary, or pyramidal portion, the latter composed 
of about twelve conical papillae, or pyramids of Malpighi, with their apices 
directed towards and embraced by the calices of the pelvis of the kidney (fig. 
296). The medullary portion is further subdivided into the boundary layer 
of Ludwig and the papillary portion. According to Klein, the relative pro- 
portions of these three parts are—cortex, 3.5 ; boundary layer, 2.5, and papil- STRUCTURE OF THE KIDNEY. 
[Sec. 254. 
lary portion, 4. The cortex has a light brown color, and when torn presents 
a slightly granular aspect, with radiating lines running at regular distances. 
The granules are due to the presence of the Malpighian corpuscles, and the 
striae to the medullary rays. The boundary zone is darker, and often purplish 
in color. It is striated with clear and red lines alternating with opaque ones, 
the former being blood-vessels and the latter uriniferous tubules. The papillary 
zone is nearly white and uniformly striated, the striae converging to the apex 
of the pyramid. The medulla is much denser and less friable than the cortex, 
owing to the presence of a large amount of connective-tissue between the 
tubules. The bundles of straight tubes of the medulla may be traced at regular 
Boundary layer 
of Medulla. 
i" Labyrinth. 
Papillary por- 
tion of me- 
dulla. 
U" 
2' 
%' Medullary rays. 
Transverse section) 
of tubules in 
boundary layer. J 
•3 
MEDULLA. 
Fat of renal sinus, 
CORTEX. 
Renal calyx. 
Ureter. 
Tranversely 
coursing medullary 
rays. 
f Branch of 
t Renal artery. 
Artery. 5. 
Artery. 5. 
Fig. 296. 
Longitudinal section through the kidney (Tyson, after Henle) 
intervals running outwards into the cortex, constituting medullary rays, 
which become smaller as they pass outwards in the cortical zone, so that they 
are conical and form the pyramids of Ferrein (fig. 298, PF). The portion 
of the cortex lying between the medullary rays is known as the labyrinth, 
from the complicated arrangement of its tubules.] 
[Size, Weight of Kidney.—The adult kidney is about 11 centimetres (4.4 inches) in length, 
5 centimetres (2 inches) wide, and 3 centimetres (1 inch) in thickness. It weighs in the male 
H3.5 to 170 grms. (4 to 6 oz.), in the female 113.5 t0 156 grms. (4 to 5oz). The width of 
the cortex is usually 5 to 6 millimetres to \ inch).] 
I. The uriniferous tubules all arise within the labyrinth of the cortex by Sec. 254.] 
STRUCTURE OF THE URINARY TUBULES. 
493 
means of a globular enlargement, 200 to 300 fi [yjt-g- to inch] in diameter, 
called Bowman’s capsule (figs. 298, 299). After pursuing a complicated 
course, altering their direction, diameter, and structure, and being joined by 
other tubules, they ultimately form large collecting tubes, which terminate by 
minute apertures, visible with the aid of a hand-lens, on the apices of the 
papillae projecting into the calices of 
the kidney. Each urinary tubule is 
composed of a homogeneous mem- 
brana propria, lined by a single 
layer of epithelial cells, so as to leave 
a lumen for the passage of the urine 
from the Malpighian corpuscles to the 
pelvis of the kidney. The diameter 
and direction of the tubules vary, and 
the epithelium differs in its characters 
at different parts of the tube, while 
the lumen also undergoes alterations 
in its diameter. 
Course and Structure of the 
Tubules.—In the labyrinth of the 
cortex, tubules arise in the spherical 
enlargement known as Bowman’s 
capsule (fig. 298, 1), which invests 
(in the manner presently to be de- 
scribed) the tuft of capillary blood- 
vessels called a glomerulus or Mal- 
pighian corpuscle. By means of 
a short and narrow neck (2) the cap- 
sule becomes continuous with a con- 
voluted tubule, X in fig. 299. This 
tubule is of considerable length, form- 
ing many windings in the cortex (fig. 
298, 3); the first part of it is 45 fi 
wide, constituting the proximal or 
first convoluted tubule. It be- 
comes continuous with a spiral tub- 
ule of Schachowa (4), which lies in 
a medullary ray where it pursues a 
slightly wavy or spiral course. On the boundary line between the cortical and 
boundary zone, the spiral tubule suddenly becomes smaller and passes into the 
descending portion of Henle’s loop (5), which is 14 /z in breadth, and is 
continued downwards through the boundary zone into the medulla, where it 
forms the narrow loop of Henle (6) which runs backwards in the medullary 
part to the boundary zone. Here it becomes wider (20-26 /z), and as it con- 
tinues its undulating course, it enters a medullary ray, where it constitutes the 
ascending looped tube (7), which becomes narrower in the cortex. Leav- 
ing the medullary ray again, it passes into the labyrinth, where it forms a tube 
with irregular angular outlines—the irregular tubule (10), which is continu- 
ous with (fig. 299, n, ri) the second or distal convoluted tubule (11), which 
resembles the proximal tubule of the same name. Its diameter is 40 /z. A short, 
narrow, wavy junctional or curved collecting tubule (12) connects the latter 
with one of the straight collecting tubes (13) of a medullary ray. As the 
collecting tubule proceeds through the boundary zone, it receives numerous 
Cortex. 
Boundary 
or mar- 
ginal 
zone. 
Papillary 
zone. 
Fig. 297. 
Longitudinal section of a Malpighian pyramid. 
PF, pyramids of Ferrein; RA, branch of renal 
artery; RV, lumen of a renal vein receiving an 
interlobular vein; VR, vasa recta; PA, apex 
of a renal papilla; b, b, embrace the bases of the 
renal lobules. 494 
THE URINARY TUBULES. 
[Sec. 254. 
junctional tubes, and when it reaches the boundary zone, it forms one of the 
collecting tubes (fig. 299, O), which unite with one another at acute angles 
to form the larger straight excretory tubes or ducts of Bellini (15), which 
open on the summit of the Malpighian pyramids into a calyx of the pelvis of 
the kidney. In the cortex the collecting tubules are 45 jj. in diameter, but 
where they have formed an excretory tube (O), their diameter is 200 to 300 ; 
Sub-capsular layer without Mal- 
pighian corpuscles. 
12. First part of collecting tube. 
11. Distal convoluted tubule. 
A. CORTEX. 
10. Irregular tubule. 
3. Proximal convoluted tubule. 
13. Straight part of collect- 
ing tube. 
4. Spiral tube. 
9. Wavy part of ascending limb. 
2. Constriction or neck. 
9. Wavy part of ascending 
limb of Henle’s loop. 
4. Spiral tubule. 
Inner stratum of cortex 
without Malpighian 
corpuscles. 
1. Malpighian tuft surrounded 
by Bowman’s capsule. 
8. Spiral part of ascending limb 
of Henle’s loop. 
B. BOUNDARY ZONE. 
7 & 8. Ascending limb of 
Henle’s loop-tube. 
5. Descending limb of Henle’s 
loop-tube. 
6. Henle’s loop. 
C. PAPILLARY ZONE. 
Diagram of the course of two uriniferous tubules (Klein and Noble-Smith). 
Fig. 298. 
24 to 80 of these tubes open on the apex of each of the 12 to 15 Malpighian 
pyramids. In the lowest and broadest part, the membrana propria is 
strengthened by the presence of a thick supporting framework of connective- 
tissue. 
Structure of the Tubules.—[Below the neck, the tubules are lined every- 
where by a single layer of nucleated epithelium.] Bowman’s capsule, Sec. 254.] 
STRUCTURE OF THE URINARY TUBULES, 
495 
which is about inch in diameter (fig. 300, II), consists of a homogeneous 
basement membrane lined 
internally by a single con- 
tinuous layer of flattened 
cells (£). According to 
Roth, the basement mem- 
brane itself is composed of 
endothelial cells. [In the 
foetus the lining cells are 
more polyhedral.] Within 
the capsule lies the glo- 
merulus or tuft of blood- 
vessels. The cells lining 
the capsule are reflected 
over and between the lo- 
bules of which the glo- 
merulus consists. The glo- 
merulus may not com- 
pletely fill the capsule, so 
that, according to the ac- 
tivity of the kidney, there 
may be a larger or smaller 
space between the glo- 
merulus and the capsule 
into which the filtered 
urine passes. The neck 
is lined by cubical cells. 
These cells, in some ani- 
mals, e.g., the rabbit, 
sheep, mouse, and frog, 
are ciliated. 
[The proximal con- 
voluted tubule is lined 
by characteristic epithe- 
lium. The cells, which are 
short or polyhedral, con- 
tain a turbid or cloudy 
protoplasm (fig. 300, III, 
1 and 2), which not un- 
frequently contains oil- 
globules, and they form 
a single layer. Each cell 
consists of two parts ; the 
inner, containing the 
spherical nucleus, is next 
the lumen, and granular 
(III, 2, g), while the outer 
part, next the membrana 
propria, appears fibril- 
ia ted, or “ rodded,” 
from the presence of rods 
Or fibrils placed vertically 
to the basement-membrane (fig. 301). These appear like the hairs of a brush 
pressed upon a plate of glass (III, 2). The cells are not easily separated from 
Blood-vessels and uriniferous tubules of the kidney (semi-dia- 
grammatic) ; A, capillaries of the cortex, B, of the medulla; 
a, interlobular artery; I, vas afferens; 2, vas efferens; r, e, 
vasa recta; c, venae rectae; v, v, interlobular vein; S, origin 
of a vena stellata; i, i, Bowman’s capsule and glomerulus; 
X, X, convoluted tubules; t, t, Henle’s loop; n, n, junctional 
piece ; 0, o, collecting tubes; O, excretory tube. 
Fig. 299. 496 
STRUCTURE OF THE URINARY TUBULES. 
[Sec. 254. 
each other, as neighboring cells interlock by means of the branched ridges on 
their surfaces (III, i)—(.Heidenhain, Schachowa). The lumen is well defined, 
but its size seems to depend upon the state of imbibition of the cells bounding it. 
The spiral tubule has similar epithelium and a corresponding lumen, 
although the epithelium becomes lower and somewhat altered in its characters 
at the lower part of the tube. 
The descending limb of Henle’s loop, and the loop itself with a rela- 
tively wide lumen, are bounded by clear, flattened, epithelial cells, with a bulg- 
ing nucleus (IV, S) ; the cells lying on one side of the tube being so placed 
that the bulging part of the bodies of the cells is opposite the thin part of the 
cells on the opposite side of the tube. [These tubes might be mistaken for 
blood-capillaries, but in addition to their squamous lining, they have a basement- 
membrane, which capil- 
laries have not.] In the 
ascending limb, the 
lumen is relatively wide, 
while its epithelium 
agrees generally with that 
in the convoluted tubule, 
excepting that the 
“ rods” are shorter. 
Sometimes the cells are 
arranged in an “ imbri- 
cate ” manner. 
In the irregular tub- 
ule, which has a very 
small lumen, the polyhe- 
dral cells lining it con- 
tain oval nuclei, and are 
shorter than those of the 
convoluted tubules. The 
cells, again, are very ir- 
regular in size, while 
their “ rodded ” charac- 
ter is much coarser and 
more defined (fig. 303). 
The distal convoluted tubule closely resembles in its structures the proxi- 
mal convoluted tubule, and is lined by similar cells. The curved collecting, or 
junctional tubule, although narrow, has a relatively wide lumen, as it is 
lined by clear, somewhat flattened cells. 
The collecting tubes have a distinct lumen and are lined by clear, some- 
what irregular, cubical cells (fig. 300, V), which in the larger excretory tubes 
are distinctly columnar (VI). The basement-membrane is said to be absent in 
the larger tubes. [Klein describes a thin,.delicate, nucleated centro-tubular 
membrane lining the surface of the epithelium next the lumen.] 
II. The Blood-Vessels.—[Considering the size of the kidney it is most 
abundantly supplied with blood.]—The renal artery (fig. 306) divides into 
four or five branches, which pass into the kidney at the hilum. These branches, 
surrounded by connective-tissue continuous with that of the capsule, continue 
to divide, and pass between the papillse, to reach the bases of the pyramids on 
the limits between the cortical and boundary zones where they form incomplete 
arches. From these horizontal trunks, the interlobular or radiate arteries 
(fig. 299, a) run vertically and singly into the cortex, between each two medul- 
lary rays, and in their course they give off on all sides the short undivided 
Fig. 300. 
II, Bowman’s capsule and glomerulus, a, vas afferens; e, vas 
efferens; c, capillary network of the cortex; k, endothelium 
of the capsule; h, origin of a convoluted tubule. Ill, 
“ rodded ” cells from a convoluted tubule—2, seen from the 
side, with g, inner granular zone; I, from the surface. IV, 
cells lining Henle’s looped tubule. V, cells of a collecting 
tube. VI, section of an excretory tube. Sec. 254.] 
THE BLOOD-VESSELS OF THE KIDNEY. 
497 
vasa afferentia (1), each of which enters a Malpighian capsule at the oppo- 
site pole from which the urinary tubule is given off. Within the capsule each 
afferent artery breaks up into capillaries arranged in lobules and supported 
by connective-tissue, the whole forming a tuft of capillary blood-vessels, or 
a glomerulus. Each glomerulus is covered on its surface, directed towards 
the wall of the capsule by a layer of flat, nucleated, epithelial cells (fig. 300, 
II), which also dip down between the capillaries. A vein, the vas efferens (2), 
which is always smaller than the afferent arteriole, proceeds from the centre of 
the glomerulus, and leaves the capsule close to the point at which the afferent 
vessel enters it (fig. 300, II). In their structure and distribution all the efferent 
vessels resemble arteries, as they divide into branches to form a dense, narrow- 
meshed, capillary network (fig. 299, A, and fig. 300, II, c), which ramifies 
over and between the convoluted tubules. The meshes are elongated around 
the tubules of the medullary rays, and more polygonal around the convoluted 
tubules (fig. 299). Some of the lowest efferent vessels split up into vasa 
recta, which run towards the medulla. The interlobular arteries become 
smaller as they pass towards the surface of the kidney, and some of their 
terminal capillaries communicate with the capillaries of the external capsule 
itself. Venous trunks proceed from the capillary network, to terminate in the 
interlobular veins (V), which begin close under the capsule by venous 
radicles arranged in a stellate manner (constituting the stellulae Verheynii, or 
Convoluted tubule (after ammonium chromate) 
showing “ rodded ” epithelium. 
Fig. 301. 
Epithelium of an irregular tubule of 
the kidney of a dog. 
Fig. 302. 
venae stellatae), and accompanying the corresponding artery to the limit 
between the cortex and boundary zone, where they communicate with the large 
venous trunks in that situation. [The subcapsular layer of the cortex, and a 
thin layer next the boundary zone (fig. 298, a, a), are devoid of Malpighian 
corpuscles]. 
The blood-vessels of the medulla arise from the vasa recta (fig. 299, r), 
which begin on the limit of the cortex and medulla, either as single, direct, 
muscular branches (r) of the large arterial trunks, or from those efferent ves- 
sels (<?) which lie next to the medulla. The latter are said to be devoid of 
muscle. According to Huschke, a few vasa recta are formed by the union of 
the capillaries of the medullary rays. All the vasa recta enter the boundary 
layer, where they split up into a leash or pencil of small arterioles, which pass 
between the straight tubules towards the pelvis, and form in their course a 
capillary network with elongated meshes. From these capillaries there arise 
venous radicles, which, as they proceed towards the limit between the cortex 
and medulla, form the venae rectae (4), and open into the concave side of the 
venous trunks in this region. At the apex of the papillae, the capillaries of the 
medulla form connections with the rosette-like capillaries surrounding the 
excretory ducts (at I). 
[The circulation through the vasa recta is most important. The cortical 
system of blood-vessels communicates with the medullary, but as most of the 
vasa recta are derived from the same vessel as the interlobular arteries, it is 498 
[Sec. 254. 
LYMPHATICS AND NERVES OF THE KIDNEY. 
evident that they may form a side stream through which much of the blood 
may pass without traversing the vessels of the cortex. Very probably the 
“ short-cut ” is useful in congestions of the kidney. The amount of distention 
of these vessels also will influence the size of the tubules lying between them. 
There are two other channels by which blood can pass through the renal arteries 
without traversing the glomeruli—(i) The anastomoses between the terminal 
twigs of the renal artery and the subcapsular venous plexus; (2) small branches 
given off-, either by the interlobular arteries or by the afferent vessels before 
entering the glomeruli (Bruntori).] 
The blood-vessels of the external capsule are derived partly from the 
terminal twigs of the interlobular arteries, partly from branches of the supra- 
renal, phrenic, and lumbar arteries, which anastomose with each other. The 
capillary network has simple meshes. The venous radicles pass partly into the 
venae stellatse, and partly into the veins of the same name as the arteries. The 
connection of the area of the renal artery with the other arteries of the capsule 
explains why, after ligature of the renal artery within the kidney, the blood 
still circulates in the external capsule (C. Ludwig, M. Herrman) ; in fact, these 
blood-vessels still supply the kidney with a small amount of blood, which may 
suffice to permit a slight secretion of urine to take place (.Litten, Pautynski). 
III. The lymphatics form a wide-meshed plexus in the capsule of the 
kidney, while under it they form large spaces (Heidenhain). In the parenchyma 
of the kidney, the lymphatics are said to be represented by large slits devoid 
of a wall in the tissues, and are more numerous around the convoluted than the 
straight tubules. The slits pass to the surface of the kidney, and expand 
under the capsule. When the lymphatics are greatly distended, they tend to 
compress the uriniferous tubules and the blood vessels (C. Ludwig and Zawary- 
kiri). According to Ryn- 
dowsky, the uriniferous 
tubules are surrounded by 
true lymphatics with an 
endothelial lining, and 
they even penetrate into 
the capsule of Bowman 
along with the vas affer- 
ens. [The large blood- 
vessels are also surrounded 
by lymphatics.] Large 
lymphatics, provided with 
valves, pass out of the kid- 
neys at the hilum, while 
others emerge through the 
capsule; both sets are con- 
nected with the lymph- 
spaces of the capsule of 
the kidney {A. Budge). 
IV. The nerves form 
small trunks provided with 
ganglia, and accompany 
the blood-vessels. [They 
are derived from the renal 
plexus and the lesser splanchnic nerve.] The nerves forming the renal plexus 
are derived chiefly from the solar plexus. As the right vagus and great and 
lesser splanchnics join the solar plexus, it is probable that branches of these 
nerves enter the kidney by way of the renal plexus. The splanchnics, how- 
Fig- 3°3- 
Transverse section of apex of Malpighian pyramid, a, large 
collecting tubes; b, c, d, tubules of Henle; e, f, blood- 
capillaries. Sec. 254.] 
PHYSICAL CHARACTERS OF URINE. 
499 
ever, send branches direct to the renal plexus, and the left vagus sends some 
fibres to the left kidney. In the dog the nth, 12th, and 13th dorsal spinal 
nerves, and perhaps some of the upper lumbar nerves, send branches into the 
kidney via the renal plexus (§ 276). They contain medullated and non-medul- 
lated fibres, and the latter have been traced by W. Krause as far as the apices 
of the papillae. Their mode of termination is unknown. Physiologically, we 
are certain that they contain both vaso-constrictor, vaso-dilator, and sensory 
fibres; perhaps there may be also secretory fibres [although we have no evidence 
of the termination of nerve-fibres in the epithelium of the tubules]. 
V. The connective-tissue, or interlobular stroma, forms in the papillae, 
especially at their apices, fibrous, concentric layers of considerable thickness 
between the excretory tubules (fig. 303). Further outwards, the fibrillar char- 
acter becomes less distinct, while at the same time branched connective-tissue 
corpuscles occur in greater numbers. In the cortex, the interstitial stroma 
consists almost entirely of branched corpuscles, which anastomose with each 
other. [There is also a small quantity 
of delicate fibrous tissue around Bow- 
man’s capsule, and along the course 
of the arteries. The connective-tissue 
often plays an important role in patho- 
logical conditions of the kidftey, as in- 
terstitial nephritis.] The outer layers 
of the capsule of the kidney are com- 
posed of dense bundles of fibrous tissue, 
while the deeper layers are more loose, 
and send processes into the cortical 
layers. The capsule is easily stripped 
off. None of the secretory substance 
is removed with it. The fat surround- 
ing the kidney is united to the latter 
partly by blood-vessels and partly by 
bands of connective-tissue. 
VI. Smooth Muscle is present (1) as a 
sphincter-like layer round the apex of each 
papilla i^Henle); (2) as a wide-meshed thin 
plexus on the surface of the kidney, just under 
the capsule; (3) as fine fibres derived from the 
pelvis of the kidney and which pass along with 
the blood-vessels into the pyramids (Jardet). 
(4) Kostjurin found in the dog in the boundary 
zone between the cortex and medulla a layer of 
muscle which sends prolongations into both zones. 
[Development of a Malpighian Capsule. 
—The upper end of the urinary tubule is dilated 
and closed, and into it there grows a tuft of 
blood-vessels (a) pushing one layer of the tube 
[6) before it, hence the capillaries become in- 
vested by it, just as an organ is surrounded by a 
serous sac, so that one layer—the reflected one 
(,b)—of the tubule is closely applied to the blood- 
vessels, while the other (c) lies loosely over it 
with a space between the two (fig. 304).] 
255. THE URINE.—Physical 
Characters.—A knowledge of the com- 
position of this secretion is of the great- 
est value to the physician and surgeon. 
1. The quantity of urine passed by an adult man in twenty-four hours is 
between 1000 and 1500 cubic centimetres, or about 50 oz., and in the female 
Fig. 304. 
Fig. 304.—Development of a glomerulus and 
Malpighian capsule, a, capillary; b, vis- 
ceral, c, parietal layer of capsule. 
Fig. 305.—Graduated cylinder and flask for 
measuring the amount of urine. 
Fig. 306.—Urinometer. 
Fig- 3°5- 
Fig. 306. 500 
PHYSICAL CHARACTERS OF URINE. 
[Sec. 255. 
900 to 1200 c.c. The minimum is secreted between 2 to 4 a.m., and the maxi- 
mum between 2 to 4 p.m. ( Weigelin). 
The amount is diminished by profuse sweating, diarrhoea, thirst, non-nitrogenous food, 
diminution of the general blood-pressure, after severe hemorrhage, and in some diseases of the 
kidneys. The minimum, which may be normal, is 400 to 500 c.c. It is increased by increase 
of the general blood-pressure, or of the pressure within the area of the renal artery, by copious 
drinking, contraction of the cutaneous vessels through the action of cold, the passage of a large 
amount of soluble substances (urea, salts, and sugar) into the urine, a large amount of nitro- 
genous food, as well as by various drugs, such as digitalis, alcohol, squills. After taking fluids 
charged with C02, the amount of urine is increased during the following hours (Quincke). 
The secretion is influenced directly by the nervous system, as in the sudden polyuria fol- 
lowing nervous excitement, such as hysteria [when the person usually passes a large amount of 
very pale-colored urine] ; after an epileptic attack, and also after pleasurable excitement (Beneke). 
We may have polyuria unaccompanied by the presence of sugar in the urine, which follows 
injury to a certain part of the floor of the fourth ventricle (C,1. Bernard). The urine is measured 
in tall graduated cylindrical vessels (fig. 305). [In estimating the quantity of urine passed, the 
patient must, of course, be directed always to empty his bladder at a particular hour, and collect 
the urine passed during the next twenty-four hours.] 
[Comparative.—In man 60 per cent, of the water eliminated from the body is given off by 
the kidneys and 40 by the lungs and skin. In herbivora 30 per cent, of the water is eliminated 
by the kidneys and 70 by the lungs and skin, while in carnivora the proportions are 70 by the 
urine and 30 by the lungs and skin (Afunb).] 
2. The specific gravity varies, as a mean, between 1015 and 1025 ; the 
minimum, after copious draughts of water, may be 1002 ; while the maximum, 
after profuse perspiration and great thirst, may be 1040. The mean specific 
gravity is about 1020. In newly-born children, the specific gravity falls very 
considerably during the first three days, which is due to the amount of food 
taken (Martin and Ruge). [The specific gravity of the urine in infants is 
about 1003 to 1006.] A healthy adult excretes about 70 grms. [2y2 oz.] daily 
of solids by the urine, or about 1 grm. of solids per 1 kilo, of body weight. 
The specific gravity is estimated by means of a urinometer (fig. 306), the urine being at 
the temperature of 160 C. [The urinometer, when placed in distilled water, ought to float at 
the mark o° or zero, which is conventionally spoken of as 1000. Place the urine to be tested in 
a tall cylindrical glass, of such width that the urinometer, when placed in it, may float freely 
and not touch the sides. Take care that no air-bubbles adhere to the instrument. When read- 
ing off the mark on the stem, raise the vessel to the eye and bring the eye on a level with the 
surface of the water, noting the number which corresponds to this. This rule is adopted, because 
the water rises on the stem in virtue of capillarity. It is essential that a sample of the mixed 
urine of the twenty-four hours be used for ascertaining the mean specific gravity.] 
Christison’s Formula.—To estimate the amount of solids in the urine. This maybe done 
approximately by means of the formula of Trapp or Haeser, or, as it is called in this country, 
“Christison’s Formula,” viz., “ Multiply the two last figures of a specific gravity expressed in 
four figures by 2.33 ” (Christison and Haeser), or by 2 ( Trapp), or 2.2 (Loebisck). This gives 
the amount of solids in every 1000 parts. [Suppose a person passes 1200 c.c. urine in twenty- 
four hours, and the specific gravity is 1022, then— 
To ascertain the amount in 1200 c.c.— 
22 x 2.33 = 5 grins, in 1000 c.c. 
, 51.26 x 1200 , n 
1000 : 1200 : : 51.26 : x = -— = 61.51 grins.1 
1000 3 s J 
Direct Estimation of Solids.—Place 15 c.c. of urine in a capsule of known weight, and 
evaporate it to dryness over a water-bath; afterwards completely dry the residue in an air-bath 
at ioo° C., and then cool it over concentrated sulphuric acid. During the process, a small 
amount of urea is decomposed, so that the value obtained is slightly too small. Of course the 
specific gravity varies with the amount of water in the urine. The most concentrated (highest 
specific gravity) urine is the morning urine (Urina noctis), especially after being retained in the 
bladder, e.g., in prolonged sleep a certain amount of water is absorbed, so that the urine becomes 
more concenttated. The most dilute urine is secreted after copious drinking (Urina potus). 
Under pathological conditions, as in diabetes mellitus ($ 175), the urine is, at the same time, 
very copious (as much as 10,000 c.c.), and very concentrated, so that the specific gravity varies 
from 103010 iobo [due to the presence of a large amount of grape-sugar] In fever the urine 
is concent!ated and small in amount. In polyuria, due to certain nervous conditions, the urine 
is very dilute and copious, while the specific gravity may be as low as 1001. Sec. 255.] 
THE SOLIDS OF URINE. 
501 
3. The color of the urine depends on the coloring-matters present in it, and 
varies greatly, but the differences in color are due chiefly to variations in the 
amount of water. Normally it has a pale straw color, but if it contains more 
water than usual it has a very pale tint, and in certain cases (as in the sudden 
polyuria occurring after an attack of hysteria) it may be as clear as water. Con- 
centrated urine, as after meals, or the first urine passed in the morning, has a 
darker color; it is a dark yellow or brownish-red; while it is usually dark 
colored in fever. 
Foetal urine, and also the urine first passed after birth, are as clear and colorless as water. 
The admixture of various substances with the urine alters its color. When mixed with blood 
according to the degree of decomposition of the haemoglobin, the urine is red or dark brownish 
red [more frequently it is smoky"], especially if the blood comes from the kidneys and the urine 
is acid. When mixed with bile pigments, it is of a deep yellowish-brown, with an intense 
yellow froth; senna taken internally makes it intensely red, rhubarb brownish-yellow, and car- 
bolic acid black. Urine undergoing the ammoniacal fermentation may present a dirty bluish 
appearance owing to the formation of indigo. The color of urine is estimated by Neubauer and 
Vogel by means of an empirical “ color-scale.” 
Urine, but especially ammoniacal urine, exhibits fluorescence, which disappears on the 
addition of an acid, and reappears after the addition of an alkali. 
Normal urine, after standing for several hours, deposits a fine cloud of vesical mucus [like 
delicate cotton wool]. The froth of normal urine is white, and disappears pretty rapidly, while 
that on an albuminous urine persists much longer. The urine not unfrequently contains some 
epithelial cells from the bladder ajid urethra. 
[Of the total solids (= 65 grams) urea = about 32 grams, chlorides = 15 
grams, phosphoric acid = 2.5 grams = 49.5 grams; the remainder consists of 
other substances, so that are organic and yi inorganic.] 
[The following table gives approximately the average quantities in grams of 
the chief substances excreted in the urine by a healthy adult in 24 hours. 
Total Amount 
Percentage 
in Grams. 
in Grams. 
Water, 
I440- 1500 
96 
Solids, 
57-68 
4 
f Urea, . . 
28-32 
2-5-3 
I Uric acid, 
•7 
•05 
Organic -J Hippuric 
1 acid, 
•3-2 
.015 - .1 
[ Kreatinin, 
1.7 - 2.1 
• i 1 
Total Amount 
Percentage 
in 
Grams. 
in Grams. 
' Sodic chloride, 
15 - 20 
I - 1.25 
Phosphoric acid, 
2-5-3 
.16 
Sulphuric acid, 
2 - 2.5 
•15 
Inorganic - 
Sodium, . . . 
5-7 
•4 
Magnesium, . 
•4 
•03 
Potassium, . . 3 
- 4 
•25 
Calcium, . . 
•3 
.02] 
[Amounts of the Several Urinary 
Constituents (Loebisch). 
Man, 28 years of age, 
Mean of 
weight. 
72 kilos., 
observa- 
analyses in 
tions over 8 days (Kerner). 
different 
Constituents. 
individuals 
In 24 hours. 
(Vogel). 
Min. 
Max. 
Mean. 
In 24 houis. 
c.c. 
C.C. 
C.C. 
c c. 
Quantity, 
1099 
2150 
M91 
1500 
Specific gravity, . . 
1015 
102 7 
1021 
1020 
Water, 
1440 
Solids, 
60 
U rea, 
32.00 
43-4 
38.1 
35 
Uric acid, 
0.69 
i-37 
0.94 
°-75 
Sodium chloride, . . 
15.00 
19.20 
16.5 
16.5 
Phosphoric acid, . . 
3.00 
4.07 
3-42 
3-5 
Sulphuric acid, . . 
Phosphorus, Cal- 
2.26 
2.84 
2.48 
0.38 
2.0 
cium, 
0.25 
0.51 
Magnesium ph’sph’te 
0.67 
1.29 
0.97 
lotal quantity of) 
earthy phosphates ) 
0.92 
i.80 
I-35 
1.2 
Ammonia, 
0.74 
1.01 
0.83 
0.65 
Free acid, 
i-74 
2.20 
i-95 
3 ] 
[Amounts of the Several Urinary 
Constituents Passed in 24 Hours (Parkes). 
Constituents. 
By an aver- 
age man of 
66 kilos. 
Per 1 
kilo, of 
body- 
weight. 
Water, 
grms. 
1500.000 
grms. 
23.000 
Total solids, .... 
72.oco 
1.100 
Urea, 
33-i8° 
0.500 
Uric acid, ... 
o-555 
0.0084 
Hippuric acid, . . . 
O.4OO 
0.0060 
Kreatinin, 
O.9IO 
0.0140 
Pigment and other 
substances, . . . 
IO.3OO 
0.1510 
Sulphuric acid, . . 
2.012 
0.0305 
Phosphoric acid, . . 
3-i64 
0.0486 
Chlorine, 
7.000 (8.12) 
0.1260 
Ammonia, .... 
O.77O 
Potassium, .... 
2.500 
Sodium, 
II.O9O 
Calcium, . . 
0.260 
Magnesium, .... 
0.207 
• ■] 502 
THE REACTION OF URINE. 
[Sec. 255. 
4. Consistence.—Normal urine, like water, is a freely mobile fluid. [The 
temperature is about 390 C.] 
Large quantities of sugar, albumin, or mucus make it less mobile; while the so-called chylous 
urine of warm climates may be like a white jelly. 
5. The taste is a saline bitter, the odor is characteristic and aromatic. 
Ammoniacal urine has the odor of ammonia. Turpentine taken internally gives rise to the 
odor of violets, copaiba and cubebs a strongly aromatic, and asparagus an unpleasant odor. 
Valerian, assafoetida, and castoreum [but not camphor] also produce a characteristic odor. 
[The odor of diabetic urine is described as “sweet.”] 
6. The reaction of normal urine is acid, owing to the presence of acid 
salts, chiefly acid sodic phosphate, [NaH2P04] which seems to be derived 
from basic sodic phosphate, owing to the uric acid, hippuric acid, sulphuric 
acid, and C02 taking to themselves part of the soda, so that the phosphoric 
acid forms an acid salt. After a diet of flesh, acid potassic phosphate is the 
cause of the acidity. That the urine contains no free acid is proved by the 
fact that it gives no precipitate with sodic hyposulphite (v. Foil, Hupperf). 
[The uric acid exists as urates, the hippuric acid also is not free, but exists as 
an alkaline hippurate. Briicke has proved this by congo-red, which gives a 
violet or inky color with one part of free hippuric acid in 55,000 of water, but 
urine gives no change of color.] 
The acid reaction is increased after the use of acids, e.g., hydrochloric and phosphoric, also 
by ammoniacal salts, which are changed within the body into nitric acid; lastly, after prolonged 
muscular exertion. The morning urine is strongly acid. [Sometimes under pathological condi- 
tions free fatty acids appear in the urine (lipaciduria).] 
The urine becomes less acid or alkaline—(1) By the use of caustic alkalies, alkaline car- 
bonates, or alkaline salts of the vegetable acids, the last being oxidized within the body into 
carbonates. (2) By the presence of calcic or magnesia carbonate. (3) By admixture with 
alkaline blood, or pus. (4) By removing the gastric juice through a gastric fistula (p. 301— 
Maly); further, from one to three hours after a meal. [The reaction of urine passed during 
digestion may be neutral, or even alkaline. This is due either to the formation of acid in the 
stomach (Bence Jones'), or to a fixed alkali derived from the basic alkaline phosphates taken 
with the food (W. Roberts).] (5) The urine is rarely alkaline in anaemia, owing to a deficiency 
of phosphoric and sulphuric acids. [(6) The nature of the food—vegetable food makes it 
alkaline. (7) By profuse sweating. (8) By absorption of alkaline transudations (blood, 
serum).] 
[Method.—The reaction of urine is tested by means of litmus paper. Normal urine turns 
blue litmus paper red, and does not affect red litmus. An alkaline urine makes red litmus paper 
blue, while a neutral urine does not alter either blue or red litmus paper.] Sometimes violet lit- 
mus paper is used, which becomes red in acid, and blue in alkaline urine. 
[Estimation of the Acidity.—This is done by determining the amount of caustic soda neces- 
sary to produce a neutral reaction in 100 c.c. of urine. A soda solution, containing 0.0031 grm. of 
soda in each c.c., is used ; 1 c.c. of this solution exactly neutralizes 0.0063 grm- oxalic acid. 
To the 100 c.c. of urine in a beaker, soda solution is added, drop by drop, from a graduated 
burette (fig. 307), until violet litmus paper becomes neither red nor blue. The number of c.c. 
of soda solution is now read off on the burette, and as each c.c. corresponds to 0.0063 grm- 
oxalic acid, we can easily calculate the amount of oxalic acid which is equivalent to the degree 
of acidity in 100 c.c. of urine. So that the degree of acidity of the urine is expressed by the 
equivalent amount of oxalic acid, which is completely neutralized by the same amount of caustic 
soda.] 
[Urine of Mammals.—The urine of carnivora is pale, passing into a golden-yellow; its 
specific gravity is high, and its reaction strongly acid. The urine of herbivora is alkaline; it 
shows a precipitate of earthy carbonates (hence, it effervesces on the addition of an acid), and 
of basic earthy phosphates. During hunger, the urine presents the character of that of car- 
nivora, as the animal in this case practically lives upon its own flesh and tissues.] 
256. I. THE ORGANIC CONSTITUENTS OF URINE.—Urea, 
CO(NH2)2, the diamid of C02, or carbamid, is the chief end-product of the 
oxidation of the nitrogenous constituents of the body (p. 430). Its composi- 
tion is comparatively simple: 1 carbonic acid ■-(- 2 ammonia — 1 water. It Sec. 256.] 
UREA AND ITS QUANTITATIVE ESTIMATION. 
503 
crystallizes in silky four-sided prisms with oblique ends (rhombic system), 
without water of crystallization (fig. 308, 1); if it crystallizes rapidly it forms 
delicate white needles. It has no action on litmus, is odorless, and has a weak, 
bitter, cooling taste, like saltpetre; is readily soluble in water and alcohol, but 
insoluble in ether. It is an isomer of ammonium cyanate, from which it may 
be prepared by evaporation, whereby the atoms rearrange themselves ( Wohler, 
1828). It can be prepared artificially in many other ways. 
Decomposition of Urea.—When heated above 120°, it gives off ammonia vapor, while a 
glassy mass of biuret and cyanic acid is left. When urine undergoes the alkaline fermentation 
(£ 263), or when urea is treated with strong mineral acids, or boiled with the hydrates of the 
alkalies, or superheated with water (240° C.), it takes up two molecules of water and produces 
ammonium carbonate, thus— 
When brought into relation with nitrous acid, it splits up into water, C02, and N. The last 
two decompositions are made the bases of methods for the quantitative estimation of urea ($ 257). 
[Biuret.—When urea is heated to 1500- 
170° C. it melts, gives off ammonia, and the 
substance which remains is biuret 
CO(NH2)2 + 2H20 = (NH4)2C03. 
2CON,H4 - NH3 = c2o2n3h5 
Urea. Biuret. 
Biuret with caustic potash and CuS04 gives a 
characteristic rosy solution.] 
Quantity.—In normal urine, urea 
occurs to the extent of 2.5 to 3.2 per 
cent. An adult man excretes daily 
from 30 to 40 grms. [500 grains, or 
a little over 1 oz.] ; women less, chil- 
dren relatively more [at 3-6 years, 1 
gram; 8-11, .8 gram; and 13-16, 
.4-6 gram per kilo, of body-weight] ; 
owing to the relatively greater meta- 
bolism in children, the unit weight of 
body produces more urea than the 
unit weight of an adult, in the propor- 
tion of 1.7 : 1. If the metabolism of 
the body is in a condition of equilib- 
rium (§ 236), the urea excreted con- 
tains almost as much N as is taken 
in with the nitrogenous constituents 
of the food (p. 450). 
Variations in the Quantity.— 
The amount of urea increases when 
the amount of proteids in the food is 
increased ; and also when there is a 
more rapid breaking up of the nitro- 
genous tissues of the body itself. As 
this breaking up is increased by di- 
minution of O, and by loss of blood, 
so these conditions also increase the 
urea (§ 4i)- It is also increased by 
drinking large draughts of water, by 
various salts, by frequent urination, 
and by exposure to compressed air. 
In diabetic persons, who eat very large quantities of food, it may exceed no 
Fig. 307. 
Graduated burette. 504 
FORMATION OF UREA. 
[Sec. 256. 
grms. [over 3 oz.] per day; during hunger it sinks to 6.1 grms. [90 grains] per 
day. During inanition, the maximum amount is excreted towards mid-day, 
and the minimum in the morning. The daily amount of urea varies with the 
quantity of urine ; three to four hours after a meal, the formation of urea is at 
a maximum, when it sinks and reaches its minimum during the night. Mus- 
cular exercise, as a rule, does not increase it (v. Voit, Fick and Wislicenus), 
although Pfluger states that greatly increased muscular activity increases the 
urea, and in the same proportion the total N excreted by the urine (§ 295). 
Pathological.—In acute febrile inflammations, and in fevers generally ($ 220, 3), the 
urea increases until the crisis is reached, and afterwards it diminishes. After the fever has 
passed off, the amount excreted is often under the normal. In some cases of high fever, al- 
though the amount of urea formed is increased, it may not be excreted; there is a retention of 
the urea, which, later on, may lead to an increased excretion (Naunyn). In chronic diseases, 
the amount depends largely upon the state of the nutrition, the metabolism, and also upon the 
degree of fever present. Degenerative changes in the liver, e. g., due to poisoning with phos- 
phorus, may be accompanied by diminished excretion of urea and increased excretion of am- 
monia (Stadelmann). It is increased in man by morphia, narcotin, narcein, papaverin, codein, 
thebain (.Fubini), arsenic (Gathgens), compounds of antimony, and small doses of phosphorus 
(Bauer), which favor the decomposition of proteids, and by substances which increase the bile 
formation in the liver (N. Patton). Quinine, which “ spares ” the proteids, diminishes it. 
1, 2, Prisms of pure urea; 3, rhomboidal plates; 4, hexagonal tablets; 5,6, irregular scales 
and plates of urea nitrate. 
Fig. 308. 
Occurrence.—Urea occurs in the blood (i : 10,000) lymph, chyle, (2 : 1000), liver, lymph- 
glands, spleen, lungs, brain, eye, bile, saliva, amniotic fluid, and pathologically in sweat, e. g., in 
cholera, in the vomit and sweat of uraemic patients, and in dropsical fluids. 
Formation of Urea.—It is certain that it is the chief end-product of the 
metabolism of the proteids. Less oxidized products are uric acid, guanin, 
xanthin, hypoxanthin, alloxan, allantoin [but it does not follow that these are 
precursors of urea]. Uric acid administered internally appears in the urine 
as urea; alloxan and hypoxanthin can be directly changed into urea. The 
urea excretion is increased by the administration of leucin, glycin, aspartic 
acid, or ammonia salts (Schulzen, Nencki'). As yet it has not been definitely 
determined where urea is formed, but the liver, and, perhaps, the lymph- 
glands, are organs where it is produced (§ 178). 
In birds the liver forms uric acid from ammonia. The liver can be readily excluded from the 
circulation in birds, and Minkowski found that afier this operation the uric acid was diminished 
and the ammoniacal salts were increased ($ 178). Sec. 256.] 
COMPOUNDS OF UREA. 
505 
Antecedents of Urea.—During digestion, part of the proteids is con- 
verted into leucin, tyrosin, glycin, and aspartic acid. If the amido-acids, 
glycin, leucin, or aspartic acid, or ammoniacal salts be given to an animal, 
the amount of urea excreted is increased. As the molecule of the amido-acids 
contains only one atom of N, and the molecule of urea contains two of N, it is 
probable that urea may be formed synthetically from these acids. It is possible 
that the amido-acids meet with nitrogenous residues in the juices of the body, 
e.g.y carbamic acid or cyanic acid. The union of these may produce urea. 
According to Salkowski, feeding with these substances causes the breaking up 
of the proper proteids of the body so as to provide the necessary components. 
Schmiedeberg is of opinion that urea is formed in the body from ammonium 
carbonate by the removal of water ; and v. Schroder found that when he 
passed blood containing ammonia carbonate through a “surviving” liver the 
urea in the blood was greatly increased. Drechsel succeeded in producing urea 
at ordinary temperatures by the rapid alternating oxidation and reduction of 
a watery solution of ammonium carbonate. [We know that the greater part of 
the urea exists in the blood, and that the renal epithelium removes it from the 
blood. Although it is surmised that some of the nitrogenous bodies named 
above, more especially leucin, and perhaps also kreatin, are the precursors of 
urea, yet we cannot say definitely how or where the transformation takes place. 
Perhaps this is effected in the liver, and, it may be, also in the spleen (§ 193).] 
Preparation of Urea.—Urea may be prepared from dog’s urine (especially after a diet of 
flesh) by evaporating it to a syrupy consistence, extracting it with alcohol, and again evaporating 
the filtrate to a syrupy consistence. The crystals which separate are washed with water to re- 
move any extractives that may be mixed with them, and dissolved in absolute alcohol. It is then 
filtered and allowed to crystallize slowly. 
Or, human urine may be evaporated to one-sixth of its volume and cooled to o°, and excess 
of strong pure nitric acid added, which precipitates urea nitrate mixed with coloring matter. 
This precipitate is pressed in blotting-paper, then dissolved in boiling water containing animal 
charcoal, and filtered while hot. When it cools, colorless crystals of urea nitrate separate (fig. 
308). These crystals are redissolved in warm water, and barium carbonate added until efferves- 
cence ceases; urea and barium carbonate are formed. Evaporate to dryness, extract with abso- 
lute alcohol, filter, and allow evaporation to take place, when urea separates. 
Compounds of Urea.—Urea combines with acids—nitric, oxalic, phos- 
phoric—bases, and salts (NaCl, nitrate of mercury). The following are the 
most important combinations :— 
1. Urea nitrate (CH4N20, HN03) is easily soluble in water, and not so soluble in water con- 
taining nitric acid. It forms characteristic rhombic crystals (fig. 308, 3, 4, 5, 6). Sometimes 
the formation of these crystals is used to determine micro- 
scopically the presence of urea in a fluid. If a fluid is 
suspected to contain minute traces of urea, it is concen- 
trated and a drop of the fluid is put on a microscopic slide. 
A thread is placed in the fluid, and the whole is covered 
with a cover-glass. A drop of concentrated nitric acid is 
allowed to flow under the cover-glass, and after a time 
crystals of urea nitrate adhering to the thread may be 
detected with the microscope. 
2. Urea oxalate (CH4N20)2, C2H204 + H20, is made 
by mixing a concentrated solution of urea with oxalic acid. 
The crystals form groups of rhombic tables, often of irregu- 
lar shape. It is only slightly soluble in cold water, and 
still less so in alcohol (fig. 309). 
3. Urea phosphate (CH4N20, H3P04), forms large, 
glancing, rhombic crystals, very easily soluble in water. It 
is obtained by evaporating the urine of pigs fed on dough. 
4. Sodic chloride -)- urea (CH4N20, NaCl -j- H20) forms rhombic, shining prisms, which are 
sometimes deposited in evaporated human urine. 
5. Urea mercuric nitrate is obtained as a white cheesy precipitate, when mercuric nitrate 
is added to a solution of urea. Liebig’s titration method for urea depends on this reaction 
(2 257, ii). 
Perfect crystals of oxalate of urea. 
Fig. 309. 506 
UREAMETER. 
[Sec. 257. 
257- QUALITATIVE AND QUANTITATIVE ESTIMATION 
OF UREA.—I. The qualitative Estimation of Urea.—(i) It may be 
isolated as such. If albumin be present, add to the fluid three or four times its 
volume of alcohol, and, after several hours, filter. Evaporate the filtrate over 
a water-bath, and dissolve the residue in a few drops of water. 
(2) The crystals of urea nitrate may be detected microscopically (fig. 308). 
II. Quantitative Estimation.—(1) Sodic hypobromite decomposes 
urea into C02, H20, and N. On this reaction depends the Knop-Hiifner 
method of quantitative estimation. The N rises in the form of small bubbles 
in the mixed fluid, while the C02 is absorbed by the caustic soda. [The reac- 
tion is the following :— 
N2H4CO + 3NaBrO = 3NaBr + C02 + 2H20 + Nr 
The nitrogen is collected and estimated in a graduated tube, and the amount 
of urea calculated from the volume of nitrogen. The uric acid is also decom- 
posed, but that can be estimated separately and a correction made. We may 
use the apparatus of Russell and West, or Dupre, or that of Charteris (fig. 310).] 
[Ureameter.—Make a solution of hypobromite of soda by mixing 100 grams 
NaHO in 250 c.c. of water, and adding 25 c.c. of bromine. It is better to be 
made fresh, as it decomposes by keeping. The graduated tube is placed in a 
cylindrical vessel, filled with water, and depressed until the zero on the tube 
coincides with the level of the water. In- 
troduce 15 c.c. of the hypobromite solu- 
tion into the pyramidal-shaped bottle,while 
into a short test-tube are placed 5 c.c. of 
urine. The test-tube with the urine is in- 
troduced into the bottle by means of a pair 
of forceps in such a way that it does not 
spill. Close the bottle tightly with the 
caoutchouc stopper, through which passes 
a glass tube to connect it with the graduated 
burette. Incline the bottle so as to allow 
the urine to mix with the hypobromite 
solution when the gases are given off, and 
pass into the collecting tube, which is 
gradually raised until the surfaces of the 
liquids, outside and in, coincide. Time 
should be allowed to permit the whole ap- 
paratus to have the same temperature. 
Read off the amount of gas N evolved, for 
the C02 is absorbed by the caustic soda. 
The collecting tube is usually graduated 
beforehand, so that each division of the 
tube is = 0.1 per cent, of urea, or 0.44 gr. per fluid oz. Thus, suppose that 50 
oz. of urine are passed in twenty-four hours, and that 5 c.c. of urine evolve 18 
measures of N, then 0.44 x 18 x 50 = 396 grs. of urea. If, however, the tube 
be graduated into c.c., then 30.3 c.c. of N = o. 1 grm. of urea at the ordinary 
temperature and pressure.] 
III. Volumetric Method [Liebig).—By means of a graduated pipette (fig. 311), 40 cubic 
centimetres of the urine are placed in a beaker; add 20 cubic centimetres of barium mixture 
to precipitate the sulphuric and phosphoric acids. The barium mixture consists of 1 vol. of a 
cold saturated solution of barium nitrate and 2 vols. of a cold saturated solution of barium hy- 
drate. Filter through a dry filter, and take 15 cubic centimetres of the filtrate, which corre- 
spond to 10 c.c. of urine, and place in a beaker. Allow a titrated standard solution of mer- 
curic nitrate to drop from a burette into the urine until a precipitate no longer occurs. The 
mercuric nitrate is made of such a strength that 1 cubic centimetre of it will combine with xo 
Ureameter of Charteris. 
Fig. 310. Sec. 257.] 
URIC ACID. 
507 
milligrams of urea. Test a drop of the mixture from time to time with a solution of sodic car- 
bonate, which is called the indicator, and placed in a watch-glass or piece of glass blackened 
on its under surface. Whenever the slightest excess of mercuric nitrate is added, the mixture 
strikes a yellow color with the soda. The standard solution must be added drop by drop until 
this result is obtained. Read off the number of cubic centimetres of the standard solution used; 
as each centimetre corresponds to io milligrams of urea, multiply by ten, and the amount of urea 
in io cubic centimetres of urine is obtained. 
This method does not give quite accurate results even in normal urine. To urine containing 
much phosphates is added an equal volume of the barium mixture. Very acid urines may require 
several volumes to be added. Urine containing albumin or blood must be boiled, after the addi- 
tion of a few drops of acetic acid, to remove the albumin. The sodic chloride in the urine also 
interferes with the accuracy of the process, as, on adding mercuric nitrate to urine, mercuric 
chloride and sodic nitrate are formed, so that the urea does not combine until the sodic chloride 
is decomposed. When the urine contains, as is usually the case, I to per cent. NaCl, deduct 
2 c.c. from the number of c.c. of the S S. added to io c.c. of urine. 
Estimation of the total N in Urine (Kjeldahl’s Method).—Pfliiger and Bohland recom- 
mend the following modification of the method of Kjeldahl. Five c.c. of a urine 
of medium concentration are allowed to flow from a burette into Erlenmeyer’s flask, 
capable of containing about 300 c.c., and to it are added 20 c.c. of concentrated sul- 
phuric acid. The whole is boiled until all the water and gases are driven off. The fluid 
at first becomes black from the action of the sulphuric acid, but when it has become of 
brownish tone lessen the heat of the Bunsen burner. About half an hour suffices to 
heat it, when the fluid at last becomes bright yellow. Allow it to cool, dilute it 
with water to 200 c.c., and place the whole in a flask, add 80 c.c. of caustic soda (S. 
G. 1.3), cork the flask as quickly as possible, and distil its contents. The distillate 
must pass over into sulphuric acid, which must be titrated beforehand. The quan- 
tity of sulphuric acid not combined with ammonia must be estimated by titration 
with caustic soda. 
The N in the Urine may be estimated approximately thus. To 10 c.c. of the 
urine add from a burette Liebig’s mercuric nitrate solution, and test the mixture on 
a black glass plate with dry sodic bicarbonate until a yellow speck remains. Multi- 
ply the number of c.c. of the burette fluid used by 0.04 (Pfliiger and Bohland). 
258. URIC ACID = C5H4N,03 is the nitrogenous substance 
which, next to urea, carries off most of the N from the body; in 
twenty-four hours 0.5 grm. (7 to 10 grains); during hunger, 0.24 
grm. (4 grains) ; after a strongly animal diet, 2.11 grm. (30 to 35 
grains) are excreted ; [on a purely vegetable diet it amounts to 0.2 
to 0.7 gram.] The proportion of urea to uric acid is 45 : 1. 
If a mammal be fed with uric acid, part of it becomes more highly 
oxidized into urea, while the oxalic acid in the urine is also increased 
(§ 260) ; in fowls, feeding with leucin, glycin, or aspartic acid (v. 
Knieriem), or ammonium carbonate (Schroeder), increases the 
amount of uric acid. When urea is administered to fowls, it is 
reduced chiefly to uric acid. The fresh splenic pulp containing so 
many decomposition products of leucocytes (nuclein, xanthin-bodies, 
p. 173) (§ 169) when treated with warm blood yields it (Horbac- 
zewski'). It is the chief nitrogenous product in the urine of birds, 
reptiles, and insects. It is sometimes, but not always, absent from 
herbivorous urine. 
Properties.—It is dibasic, colorless, and crystallizes in various 
forms (figs. 312 and 313), belonging to the rhombic system (1). 
When the angles are rounded, the whetstone form (2) is produced, and if the 
long surfaces be flattened, six-sided tables occur. Not unfrequently diabetic 
urine deposits spontaneously large, yellow, transparent rosettes (6, 8). If 
20 c.c. of HC1, or acetic acid, be added to 1 litre of urine, crystals (9) are de- 
posited, like cayenne pepper, on the surface and sides of the glass, after several 
hours. [The HC1 decomposes the urates, and liberates the acid, which does 
not crystallize at once, owing to the presence of the phosphates in the urine. 
Crystals of uric acid are usually yellowish in color from the pigment of the 
urine (fig. 312), and they are soluble in caustic potash.] 
Fig. 311 
Graduated 
Pipette. 508 
URIC ACID. 
[Sec. 258. 
Solubility.—It is tasteless and odorless; reddens litmus; is soluble in 15,000 parts of cold 
and in 1900 of boiling water, and insoluble in alcohol and ether. Horbaczewski prepared it 
synthetically by melting together glycin, or, as it is also called, glycocin, and urea. 
[C2H5N02 + 3CON2H4 = ch4n4o, + 3NH3 + 2II2o.] 
Glycocin. Urea. Uric acid. 
It is freely soluble in alkaline carbonates, borates, phosphates, lactates, and acetates, these salts 
at the same time removing a part of the base; thus there are formed acid urates and acid salts 
from the neutral salts. It is soluble in concentrated sulphuric acid, from which it may be pre- 
cipitated by the addition of water. [The phosphates play an important part in keeping it in solu- 
tion in the urine.] 
Decomposition.—During dry distillation it decomposes into urea, cyanuric acid, hydrocyanic 
acid, and ammonium carbonate. Superoxide of lead converts it into urea, allantoin, oxalic acid, 
and C02; while ozone forms the same substances, with the addition of alloxan. When it is re- 
duced by H in statu nascendi, as by sodium amalgam, it forms xanthin and sarkin. It is a less 
oxidized metabolic product than urea, but it is by no means proved that uric acid is a precursor 
of urea. 
Forms of uric acid. 1. Rhombic plates; 2, whetstone forms; 3, quadrate forms; 4, 5, pro- 
longed into points; 6, 8, rosettes; 7, pointed bundles; 9, barrel forms precipitated by 
adding hydrochloric acid to urine. 
Fig. 312. 
Occurrence.—Uric acid occurs dissolved in the urine in the form of acid 
urates of soda and potash. These salts occur also in urinary calculi, 
gravel, and in gouty deposits. Ammonium urate occurs in very small quantity 
in a deposit of “urates,” but is formed in considerable amount when urine 
becomes ammoniacal from decomposition (fig. 317). Free uric acid occurs in 
normal urine only in the very smallest amount. It is sometimes deposited 
after a tvtie (fig. 316). It frequently forms urinary calculi and gravel. 
The urine of newly-born children contains much uric acid. Uric acid and its salts are 
increased after severe muscular exertion, accompanied by perspiration, in catarrhal and rheu- 
matic fevers, and such conditions as are accompanied by disturbance of the respiration; in 
leukaemia and tumors of the spleen, cirrhotic liver, and generally in cases of catarrh of the 
stomach and intestinal tract, following the excessive use of alcohol. [It is certainly increased in 
leukaemia; as much as 4 grams have been eliminated in 24 hours. It is also increased during 
ague and fevers, and perhaps this has some relation to the congestion of the spleen which accom- 
panies these conditions.] It is diminished after copious draughts of water, after large doses of 
quinine, caffein, potassic iodide, common salt, sodic and lithic carbonates, sodic sulphate, inha- 
lation of O, slight muscular exertion. In gout, the amount excreted in the urine is small. In Sec. 258.] 
URIC ACID AND URATES. 
509 
chronic tumors of the spleen, anaemia, and chlorosis, when the respiration is not at the same 
time embarrassed, it is also diminished. 
[The quantity of uric acid excreted is greatest during the “ alkaline tide.” By the use of 
acids the uric acid is relatively diminished. Suppose the normal ratio of uric acid to urea to be 
1 : 35, then after the use of acids (4 grams of citric acid three times daily), the proportion will 
be about 1 : 41. If alkalies be taken (3 grams citrate of potash three times daily), the reverse 
is the case, the ratio becomes about 1 : 28 [Haig).'] 
Urates.—Uric acid forms salts—chiefly acid urates—with several bases, 
which dissolve with difficulty in cold water, but are easily soluble in warm 
water. Neutral urates are changed by C02 into acid salts. [The urates are 
insoluble substances and are readily precipitated, but this occurs more readily 
during the acid formation of urine, because the acid urate of sodium is then 
formed, and it is more insoluble than the normal urate— 
2-C5H2Na2N403 4- H20 -f- C02 = 2C5H3NaN403 + Na2C03 
Normal sodium urate. Acid sodium urate. Sodium carbonate. 
Hydrochloric and acetic acids break up the compounds, and crystals of uric 
acid separate. [According to W. Roberts uric acid is perhaps a vestigial rem- 
nant in mammalian descent. Besides the acid and normal urates Roberts de- 
scribes what he calls quadrurates, and he regards them as the exclusive combi- 
nation in which uric acid exists in solution in normal urine. The appearance 
of a deposit of urates in urine when it cools does not necessarily mean that there 
is an increased formation of urates, for urates may be deposited in concentrated 
urine when it cools.] 
[One of the atoms of H is easily replaced by metals. If uric acid be dissolved in sodic car- 
bonate we obtain C5H3NaN403 which is an acid urate. If, however, it be dissolved in an 
alkali, e.g., caustic soda, we get C5H2Na2N403 whereby a second atom of H is replaced by an 
alkaline metal, producing “ neutral or normal urate.” It is not known if the latter action 
occurs in the body.] 
(1) Acid sodic urate usually appears as a brick-red deposit in urine; more rarely gray or 
white (lateritious deposit), tinged with uroerythrin, in catarrhal conditions of the digestive 
organs, and in rheumatic and febrile affections. Microscopically, it is completely amorphous, 
consisting of granules, sometimes disposed in groups (fig. 316, b)—sometimes the granules have 
spines on them. The corresponding potash salt occurs not unfrequently under the same condi- 
tions, and presents the same characters. 
(2) Acid ammonium urate (fig. 317, a) always occurs as a sediment in ammoniacal urine, 
either with (1), or mixed with free uric acid, accompanied by triple phosphate. Microscopically, 
it is the same as (1). (1) and (2) are distinguished by the sediment dissolving zvhen the urine is 
heated. If a drop of hydrochloric acid be added to a microscopic preparation of the sediment, 
crystals of uric acid separate. 
(3) Acid calcic urate occurs sometimes in calculi, and is a white, amorphous powder slightly 
soluble in water. When heated on platinum it leaves an ash of calcium carbonate. Magnesium 
urate rarely occurs in urinary calculi. 
[A deposit of urates is of common occurrence in urine, e.g., after excessive muscular exercise, 
deranged digestion, etc. They exist in urine chiefly as normal sodium urate, but they are 
deposited chiefly as acid urates when the urine cools. The deposit is often pink-colored and 
is chiefly amorphous, but it may contain a few crystals. It redissolves when the urine is heated. 
The following table gives the chief facts relative to the urates (Ralfe) : — 
Urates. 
Formulae. 
Solubility 
in water. 
Deposited as 
Acid ammonium urate, . . 
C5H3N403.(NH4) 
1 in 1600 
Amorphous or spiked globular 
masses. 
Normal sodium “ 
C5H2N403.Na2 
1 in 77 
Nodular masses. 
Acid “ “ . . 
C6H3N403.Na 
I in 1200 
Amorphous, rarely crystalline. 
Normal potassium “ . . 
Acid “ “ . . 
c5h2n4o3.k2 
1 in 44 
Amorphous, or in fine needles. 
c5h3n4o3.k 
1 in 800 
Normal calcium “ . . 
C5H2N403.Ca 
1 in 1500 
Fine granules. 
Acid “ “ . . 
(C5H3N403)2.Ca 
1 in 600 
Amorphous, or in fine needles. 
Acid lithium “ . . 
C5H3N.O3.Li 
1 in 60 
4t << tl ESTIMATION OF URIC ACID. 
[Sec. 258. 
The greater solubility of lithium and potassium urates has led to the administration of potash 
or lithia water in cases of uric acid diathesis.] 
[Formation of Uric Acid.—It exists in the blood, and does not seem to 
be formed in the kidneys. In gout, when there is a diminished excretion of 
uric acid it accumulates in the blood and tissues. After extirpation of the kid- 
neys in birds and snakes, it accumulates in the blood and organs. The seat of 
its formation in mammals has not been ascertained experimentally. In birds, 
however, it seems to be formed in the liver. Birds have a vascular system in 
their kidneys similar to the portal vein. A vena advehens carries the blood 
from the caudal and iliac veins and veins coming from the pelvic viscera to the 
kidneys, and the vena advehens communicates with the portal vein by means 
of Jacobson’s vein. Minkowski tied the portal vein in geese, thus excluding 
the liver, but the blood from the abdominal organs still passed through the 
kidneys to the inferior vena cava. The animals lived from 6-20 hours. He 
found that the total nitrogen eliminated in the urine is not greatly diminished 
(reduced about one-half or less), but the proportion of uric acid to the total 
nitrogen was greatly diminished. Normally, in geese 60-70 per cent, of the 
total nitrogen in the urine is eliminated as uric acid, but after exclusion of the 
liver it amounts only to 3-6 per cent., while the ammonia is enormously in- 
creased. The normal 9-18 per cent, of ammonia is increased to 50-60 per cent. 
It would seem as if ammonia is a normal antecedent of uric acid, and that 
the synthesis perhaps takes place in the liver. Another noteworthy fact 
observed was the simultaneous great increase of lactic acid in the urine 
(P- 5°4)-] 
259. ESTIMATION OF URIC ACID.—I. Qualitative.—1. Micro- 
scopic Characters.—The appearances presented by uric acid and its salts 
under the microscope are shown in fig. 313. It is deposited from urine after 
several hours, on adding acetic or hydrochloric acid. 
2. Murexide Test.—Gently heat a urate or uric acid in a porcelain vessel 
along with nitric acid. Decomposition takes place and the color changes to 
yellow. N and C02 are given off; urea and alloxan (C4H2N204) remain. 
[C5H4N403 -f o + h.2o = C4H2N204 + CON2H4.] 
Uric Acid. Alloxan. Urea. 
Evaporate slowly and allow the yellowish-red stain to cool; on adding a drop 
of dilute ammonia a purplish-red color of murexide (which contains furfurate of 
ammonia, alloxantin-amid) is obtained, it becomes blue on the addition of 
caustic potash. If potash or soda be added instead of ammonia, a violet color 
is obtained, which disappears on heating. 
3. Schiff’s Test.—Dissolve uric acid or a urate in a solution of an alkaline carbonate, and 
drop it upon blotting-paper saturated with a solution of silver nitrate; reduction of the silver 
takes place at once, and a black spot is formed. 
4. On boiling a solution of uric acid or a urate in an alkali, with Fehling’s solution ($ 149, 
2), at first white urate of the suboxide of copper is deposited, while later, red copper suboxide 
is formed. 
II. Quantitative Estimation.—Add 5 cubic centimetres of concentrated HC1 to 100 c.c. of 
urine, and allow it to stand for forty-eight hours in the dark, when the uric acid is precipitated 
like fine cayenne pepper crystals. All the uric acid is not precipitated by the HC1, even after 
standing for a time. [E. A. Cook uses sulphate of zinc to precipitate the uric acid as urate of 
zinc. Caustic soda is added to precipitate the phosphates, and then to the clear fluid zinc sul- 
phate solution, which precipitates urate of zinc as a white gelatinous deposit.] 
Fokker-Salkowski Method.—Make 200 c.c. of urine strongly alkaline with sodic carbon- 
ate, and after an hour add 200 c.c. of a concentrated solution of ammonium chloride, whereby 
acid urate of ammonium is precipitated. After forty-eight hours filter through a small weighed 
filter, and wash it several times. Fill the filter with dilute HC1 and collect the filtrate. Do 
this until all the acid urate is dissolved. From the total filtrate after a time all the uric acid 
separates. It is collected on the same filter, washed with water and alcohol until the acid Sec. 259.] 
KREATIN AND XANTHIN. 
511 
reaction disappears, dried at ioo° C, and weighed. To the weight in excess of the filter add 
0.03° grm. 
[Haycraft’s method depends on the fact, that uric acid forms a compound with silver—urate 
of silver—which is very insoluble in water. The solutions required are: I. Centinormal 
ammonic sulphocyanate, made by dissolving 8 grams of crystals in I litre of water, and adjust 
to decinormal silver solution. Dilute with 9 vols. of water, 1 c.c. = 0.00168 uric acid. 2. 
Saturated solution of iron-alum (the indicator). 3. Pure HNOa (20 to 30 per cent.). 4. 
Strong ammonia. Ammoniacal silver solution made by dissolving 5 grms. AgNOs in 100 c.c. 
water, and add NH4HO until the solution becomes clear. Process.—Place 25 c.c. of urine in 
a beaker, and add 1 grm. sodic bicarbonate; then add 2 to 3 c.c. of ammonia to precipitate 
ammonio-magnesic phosphate. Add X to 2 c.c. of ammoniacal silver solution, which precipi- 
tates silver urate in a white gelatinous form. The precipitate is then thoroughly washed on an 
asbestos filter, and then dissolved from this by nitric acid, after which the silver is estimated 
(Volhard’s method). In doing so, add a few drops of the indicator, and drop in the centinormal 
solution of ammonic sulphocyanate. A white precipitate with a transient reddish coloration 
will be formed; as soon as the red color is permanent the process is at an end. The uric 
acid present is ascertained by multiplying the number of cubic centimetres of the sulphocyanate 
used by 0.00168. 
260. KREATININ AND OTHER SUBSTANCES.—Kreatinin 
c4h7n3o, is derived from the kreatin of muscle by the removal of a mole- 
cule of water, and partly from flesh food. The quantity excreted daily is 0.6 
to 1.3 gram (8 to 18 grains). 
[Source.—It is generally considered that it is formed from the kreatin of muscle. If kreatin 
be given to animals by the mouth it 
reappears in the urine as kreatinin, 
but if it be injected into the blood 
stream it reappears as kreatin, so that 
the kidneys cannot effect the change. 
Perhaps the change is effected in the 
muscles.] 
It is diminished in progressive 
muscular atrophy, tetanus, anaemia, 
marasmus, chlorosis, consumption, 
paralysis; and is increased in typhus, 
inflammation of the lung; it is absent 
from the urine of sucklings. 
Properties.—Kreatinin is alkaline, 
easily soluble in water and hot alcohol. 
It forms colorless oblique rhombic 
columns ; unites with acids and salts, 
silver nitrate, mercuric chloride, and 
especially with zinc chloride. 
Tests.—Kreatinin-zinc chloride 
(fig. 313) is used to detect its pres- 
ence. Weyl’s Test.—Add to urine 
a few drops of a slightly brownish 
solution of nitro-prusside of soda, and 
then weak caustic soda solution, pro- 
ducing a Burgundy-red color, which 
soon disappears. When heated with glacial acetic acid, the color changes to green, which 
after a time changes to blue (Salkowski). Aceton gives a similar reaction, but in this case the 
red color is darker, and more of a purple shade. Aceton can be expelled by boiling the urine; 
so that it is better to boil the urine beforehand, if aceton be suspected. [The blue color— 
Berlin blue—is due to the formation of an iron-salt, ferrocyanide of sodium, from the decomposi- 
tion of the nitro-prusside. The reaction also succeeds with formic acid—instead of glacial acetic 
acid—if some time be allowed to elapse after Weyl’s reaction.] 
Zanthin = C5H4N402 occurs only to the amount of 1 gram in 300 kilos, of urine. It is a sub- 
stance intermediate between sarkin and uric acid. Guanin and hypoxanthin may be changed 
into xanthin ; in contact with water and ferments it passes into uric acid. When evaporated 
with nitric acid, it gives a yellow stain, which becomes yellowish-red on adding potash, and 
violet-red on applying more heat. It is an amorphous, yellowish-white powder, fairly soluble in 
boiling water. It has also been found in traces in muscles, brain, liver, spleen, pancreas, and 
thymus. The crystalline body paraxanthin (dimethylxanthin) and the amorphous heteroxan- 
thin (methylxanthin) occur in traces in the urine (Salomon). 
Fig. 313. 
Kreatinin-zinc chloride, a, balls with radiating marks; 
b, crystallized from water; c, from alcohol. OXALIC AND HIPPURIC ACID. 
[Sec. 260. 
Sarkin or Hypoxanthin, C5H4N40.—As yet this substance has been found only in the urine 
of leuksemic patients (Jakubasch), and it has been prepared in the form of needles or flattened 
scales from muscle, spleen, thymus, brain, bone, liver, and kidney. In normal urine a body 
nearly related to, and possibly identical with, hypoxanthin occurs (E. SalkoUski). Hypoxan- 
thin closely resembles xanthin, and can be changed into it by oxidation. Nascent hydrogen, on 
the other hand, reduces uric acid to xanthin and hypoxanthin. When evaporated with nitric 
acid it gives a light yellow stain, which becomes deeper, but not reddish-yellow, on adding 
caustic soda. It is more easily soluble in water than xanthin, and by this means the two sub- 
stances can be separated from each other. Guanin is insoluble in water. 
[Notice the close relation of the three bodies—uric acid, xanthin, and hypoxanthin. The 
difference is in the proportion of oxygen:— 
Uric acid, . 
. . c5h4n4os 
Xanthin, 
• • c5H4N4o2 
Hypoxanthin, 
. . c5h4n40. 
Closely related to these, and belonging to the xanthin group, but which do not occur in urine,are 
guanin, and adenin (C5H5N5), the latter a polymer of hydrocyanic acid. Perhaps 
all these four bodies belong to the antecedents of urea or uric acid (jBunge).'] 
Oxaluric acid (C3H4N204) is an oxidation product of uric acid, and occurs in very small 
quantity combined with ammonia in urine. Physiologically, it is interesting on account of its 
relation to uric acid. It is a white powder slightly soluble in water. Ammonium oxalurate can 
be prepared from uric acid. 
Oxalic Acid (C2H204) occurs, but not constantly, to the amount of 20 
milligrams daily, [but never as free oxalic acid]. It is united with calcium and 
held in solution by the acid phosphate of soda. Sometimes it forms a deposit 
of oxalate of lime, which is known by the “ envelope ” shape of the crystals 
(fig. 314) ; insoluble in acetic acid, and forming 
transparent octahedra. More rarely it assumes a bis- 
cuit or sand-glass form. The genetic relation of 
oxalic acid to uric acid is shown by the fact, that dogs 
fed with uric acid excrete much oxalate of lime. Oxalic 
acid may also be produced by the oxidation of pro- 
ducts derived from the fatty acid series (p. 486). 
Oxaluria.—The eating of substances containing oxalate of lime 
(rhubarb) increases the excretion. Increased excretion is called 
oxaluria; it is regarded as a sign of retarded metabolism (Beneke), 
and it may give rise to the formation of a calculus. In oxaluria 
the uric acid is also often increased in amount. Perhaps, in the 
first instance, there is an increased formation of uric acid from 
which oxalic acid, urea, and C02 may be formed. The amount 
of oxalic acid is increased after the use of wine and sodic bicarbonate. 
Hippuric Acid = C9H(,N03(Benzoylamidoacetic acid, p. 490) occurs in 
large amount in the urine of herbivora, and in them is the chief end-product of 
the metabolism of certain nitrogenous substances; in human urine the daily 
quantity is small, 0.3 to 3.8 grms (5 to 50 grains). It is an odorless mono- 
basic acid with a bitter taste, crystallizing in colorless four-sided prisms (fig. 
315). [It exists in urine as hippurates of the alkalies.] Readily soluble in 
alcohol, and soluble in 600 parts of water. Its presence in urine is a matter of 
diet. 
[Crystals of hippuric acid when heated in a test-tube are decomposed, and a sublimate of 
benzoic acid and ammonic benzoate condenses on the upper cool part of the tube, while there is 
an odor of new hay, and oily drops remain in the tube.] 
It is a conjugated acid, and is formed in the body from benzoic acid, or some 
nearly related chemical body, such as the cuticular substance of plants, or from 
oil of bitter almonds, cinnamic or quinic acid, which easily pass by reduction 
(quinic acid) or by oxidation (cinnamic acid) into benzoic acid. It may be 
formed by the union with hydration of benzoic acid with glycin :— 
Oxalate of lime, a, b, octa- 
hedra; c, compound forms; 
d, dumb-bells. 
Fig. 314- 
C7H602 + C2H5N02 = C9H9N03 + H20 
Benzoic acid + Glycin = Hippuric acid + Water. Sec. 260.] 
FORMATION OF HIPPURIC ACID. 
513 
[If hippuric acid be boiled with alkalies or strong mineral acid, it splits up 
with hydration into benzoic acid and glycocoll or glycin. 
C6H5 CO N\CH2— COOH + H2° — 
C„HS- COOH + H-N(cHHi_ cooh 
Hippuric acid. 
Benzoic acid. 
Glycocoll.] 
[Formation of Hippuric Acid.—When benzoic acid is introduced into 
the alimentary canal of an animal (rabbit or dog), it appears in the urine as 
hippuric acid, so that somewhere in the body benzoic acid meets with and 
combines with glycin. Nitro-benzoic acid appears as nitro-hippuric acid. As 
the benzoic acid passes through the body, it becomes conjugated with glycin or 
glycocoll, chiefly in the kidneys. The hippuric acid in the urine of herbi- 
vora is chiefly derived from some substance with a benzoic acid residue—the 
aromatic combinations—present in the cuticular coverings of the food. That 
hippuric acid, in part at least, is formed in the kidneys, /.<?., by the cells of 
the renal tubules, is shown by the following considerations: If arterialized 
blood, containing benzoic acid and glycin, or even benzoic acid alone, be 
passed through the blood-vessels of a fresh, living, excised kidney, a so-called 
“ surviving kidney,” hippuric acid is found in the blood after it is perfused. 
Even after forty-eight hours, if the kidney be kept cool, the synthesis takes 
place. The kidney in this case also must 
not be dead, but a “surviving” one. If 
the kidney be kept too long, the conjuga- 
tion does not take place. If the fresh sur- 
viving kidney be chopped up, and kept at 
the temperature of the body with benzoic 
acid and glycocoll, hippuric acid is formed. 
Oxygen seems to be necessary for the pro- 
cess, for, if blood or serum containing car- 
bonic oxide be used, there is no formation 
of hippuric acid.] 
[If the liver be excised in frogs, and 
benzoic acid, or better, benzoic acid and 
glycocoll, be injected into the dorsal lymph-sac, hippuric acid is found in the 
tissues and secretions. Thus the liver is not the locality, or exclusive locality, 
in the frog, where the synthesis occurs. But in the frog, it may be formed 
after extirpation of the kidneys. It is only in the dog that its exclusive forma- 
tion in the kidney has been proved (Bunge and Schmiedeberg).~\ 
[There is one difficulty about the matter, viz., that glycin, as such, has not 
been found in the tissues. It is probable, however, that it is formed in various 
metabolic processes, and is as rapidly combined with some other body. It 
may be formed in this way in the kidney, and immediately combine with ben- 
zoic acid to form hippuric acid.] 
According to this view, it is derived chiefly from the food of herbivorous animals, and 
hence it is absent from the urine of sucking calyes, as well as after feeding with grain devoid 
of husk. But it is also formed in the body from the proteids. In the dog, the formation of 
hippuric acid occurs in the kidney (Schmiedeberg and Bunge), and in the frog also outside the 
kidney. Kiihne and Hallwachs thought it was formed in the liver, and Jaarsveld and Stockvis 
in the kidney, liver and intestine. The observation of Salomon that, after excision of the kid- 
neys in rabbits, and injection of benzoic acid into the blood, hippuric acid was found in the 
muscles, blood, and liver, goes to show that it must be formed in other organs beside the kidneys. 
The power of changing benzoic acid introduced into the human body into hippuric acid may 
even be abolished in disease of the kidney. Under certain circumstances it seems that hippu- 
ric acid, already formed, may be again decomposed in the tissues. 
F'g- 3I5- 
Hippuric Acid. COLORING MATTERS OF THE URINE. 
[Sec. 260. 
It is greatly increased after eating pears, plums, and cranberries; in icterus, some liver affec- 
tions, and in diabetes. 
Preparation.—Add milk of lime to the fresh urine of horses or cows to form calcic hippu- 
rate. Filter, evaporate the filtrate to a small bulk, and precipitate the hippuric acid with excess 
of hydrochloric acid. To purify the hippuric acid, crystallize it several times from a hot watery 
solution. 
Cynuric Acid C20HuN2O6 -(- H20 occurs in the urine of dogs (J. v. Liebig). 
Allantoin, which occurs in the amniotic fluid of the cow, is 
found in minute traces in normal urine after flesh food, and is more abundant 
during the first weeks of life and during pregnancy. [It, to a large extent, 
replaces urea in the urine of the foetus.] 
After large doses of tannic acid the amount is increased (Schottin), while, in dogs, feeding 
with uric acid also increases it (Salkowski). 
Properties.—It forms shining, prismatic crystals; from the urine of sucking calves it crystal- 
lizes in transparent prisms. It is decomposed by ferments into urea, ammonium oxalate, and 
carbonate, and another as yet unknown body. Preparation—(a) the urine is precipitated 
with basic lead acetate, the lead in the filtrate is removed by sulphuretted hydrogen, and the 
filtrate itself is then evaporated to a syrup, from which the crystals separate, after standing for 
several days. They are then washed with water, and recrystallized from the water (Salkowski). 
261. COLORING-MATTERS OF THE URINE.—1. Uro- 
bilin is most abundant in the highly-colored urine of fevers, but it also occurs 
in normal urine (Jaffe). It is identical with the hydrobilirubin of Maly 
(§ T77> 3> g)- is a derivative of haematin, which also yields the bile-pigments 
(§ 177). It gives a red, or reddish-yellow, color to urine, which becomes yel- 
low on the addition of ammonia. [What is called normal bilirubin seems 
to be the principal coloring-matter in urine.] 
[MacMunn, chiefly from spectroscopic observations, finds that two entirely different sub- 
stances have been included under the name of “ urobilin,” viz., that of normal and that of 
pathological urine, and that hydrobilirubin is not identical with either. The pathological urobi- 
lin seems to be closely connected with stercobilin ($ 185).] 
Preparation.—Prepare a chloroform extract of urine containing urobilin—add iodine to the 
extract, and remove the iodine by shaking the mixture with dilute caustic potash, which forms 
potassic iodide. This potash solution becomes yellow or brownish-yellow, and exhibits beauti- 
ful green fluorescence (Gerhardt). 
Urobilin may be extracted from many urines by ether [Salkomski). When subjected to the 
action of reducing agents, e. g., sodium amalgam, a colorless product is obtained, which on 
exposure to the air absorbs O, and becomes retransformed into urobilin. This colorless body is 
identical with the chromogen which Jaffe found in urine. 
If urine is treated with soda or potash, the characteristic absorption-band lying between b and 
F. passes nearer to b, becomes darker and more sharply defined. According to Hoppe-Seyler, 
urobilin is formed in urine after it is voided, from another urobilin-forming body (Jaffa’s chro- 
mogen) absorbing oxygen. If urine containing urobilin be made alkaline with ammonia, and 
zinc chloride be added, it exhibits marked fluorescence ; it has a green shimmer by reflected 
light. When urobilin is isolated, it fluoresces without the addition of zinc chloride. In cases 
of jaundice ($ 180), where Gmelin’s test sometimes fails to reveal the presence of bile-pigments, 
urobilin occurs. This “urobilin-icterus” (Gerhardt) occurs chiefly after the absorption of 
large extravasations of blood. According to Cazeneuve, the urobilin is increased in all diseases 
where there is increased disintegration of colored blood-corpuscles. 
2. Urochrome was regarded (Thudichum) as the chief coloring-matter of urine. It may be 
isolated in the form of yellow scales, soluble in water, and in dilute acids and alkalies. [It is 
possibly impure urobilin.] The watery solution oxidizes, and when exposed to air becomes red, 
owing to the formation of uroerythrin. When acted on by acids, new decomposition-products 
are formed, e. g., uromelanin. Uroerythrin gives the red color to deposits of urates (g 258). 
3. A brown pigment containing iron is carried down with uric acid, which is precipitated on 
the addition of hydrochloric acid (§ 258). By repeatedly adding sodic urate to the urine, 
and precipitating the uric acid by hydrochloric acid, a considerable amount may be obtained 
(.Kunkel). 
4. Urine boiled with HC1 yields a garnet-red crystalline pigment, urorubin, to ether. 
In cases of melanotic tumors, there has been occasionally observed urine, which becomes 
dark, owing to melanin ($ 250, 4), or to a coloring-matter containing iron (.Kunkel). Sec. 262.] 
PHENOL AND ETHEREAL SULPHATES. 
515 
262. INDIGO, PHENOL, KRESOL, PYROKATECHIN, AND 
SKATOL-FORMING SUBSTANCES.—1. Indican. [C8H7NS04], 
or indigo-forming substance (Schunck), is derived from indol, CSH7N, the basis 
of indigo, which is formed in the intestine by the pancreatic digestion of pro- 
teids (§ 170, II), but it also arises as a putrefactive product (§ 184, III). 
Indol, when united with the radical of sulphuric acid, HS03, and combined 
with potassium, forms the so-called indigogen or indican of urine (.Brieger, 
Baumann). This substance (C8H6NS04K = potassium indoxyl-suiphate) forms 
white glancing tablets and plates ; readily soluble in water and less so in alcohol. 
By oxidation it forms indigo-blue ; 2 indican -f- 02 = C16H10N2O2 (indigo-blue) 
-j- 2HKS04 (acid potassic sulphate). It is more abundant in the urine in the 
tropics, and it is absent from the urine of the newly-born (Senator). [The 
indigo in the animal body is derived from indol, the basis of the indigo group. 
Indol is formed in the intestine by the bacterial putrefaction of proteids, and 
when absorbed it is oxidized into indoxyl— 
C8H7N + O = C8H6(OH) n 
Indol Indoxyl 
Tests.—(1) Add to 40 drops of urine, 3 to 4 c.c. of strong fuming hydrochloric acid, and 2 
to 3 drops of nitric acid. Boil, a violet-red color with the deposition of true crystalline indigo- 
blue (rhombic) and indigo-red attests its presence. Putrefaction causes a similar decomposition 
in indican; hence, we not unfrequently observe a bluish-red pellicle of microscopic crystals 
of indigo-blue, or even a precipitate of the same. (2) Mix in a beaker equal quantities of urine 
and hydrochloric acid, and add two drops of solution of chloride of lime; the mixture at first 
becomes clear, then blue [Jaffe). Add chloroform, and shake the mixture vigorously for some 
time; the chloroform dissolves the blue coloring-matter, which is obtained as a deposit, when 
the chloroform evaporates [Senator, Salkowski). [What happens in this case is that the indigo 
exists in urine as a colorless combination—indoxyl-suiphate of potash, the conjugated sulphuric 
acid is split up, and the indoxyl is oxidized into indigo— 
2CgH6NKS04 + 02 = C16H10N2O2 -f 2HKS04] 
(3) Heat to 70° one part of urine with two parts of nitric acid, and shake up with chloroform; 
the chloroform dissolves the indigo which is formed, assumes a violet color, and gives an absorp- 
tion band between C and D, slightly nearer D (Hoppe-Seyler). 
Quantity.—Jaffe found in 1500 c.c. of normal human urine, 4.5 to 19.5 milligrams of indigo; 
horse’s urine contains 23 times as much. The subcutaneous injection of indol increases the 
indican in the urine (Jaffe). E. Ludwig obtained indican by heating hsematin or urobilin with 
a caustic alkali and zinc dust. It has also been found in the sweat ($ 286) (Bizio). 
Pathological.—The indican in the urine is increased when much indol is formed in the 
intestine ($ 170,11), e. g., in typhus, lead colic, trichinosis, catarrh and hemorrhage of the 
stomach, cholera, carcinoma of the liver and stomach; obstruction of the bowels or ileus, 
peritonitis, and diseases of the small intestine. [It is a fact of some practical importance that 
a large quantity of the indoxyl compound, indican, is found in the urine in intestinal obstruction. 
It is increased after ligature of the small, but not the large, intestine in dogs. This is due to the 
putrefaction of the albumin in the intestine yielding indol. In man it is increased in obstruction 
of the small, but not of the large, gut.] 
2. Phenol, C6HsO (carbolic acid, § 252, IV), was discovered by Stadeler 
in human urine (more abundant in horse’s urine). It does not occur as 
carbolic acid, but in combination with a substance from which it is separated 
by distillation with dilute mineral acids. The “ phenol-forming substance ” is, 
according to Baumann, “ phenolsulphuric acid” (C6H50, S03H), which 
in urine is united with potash [i.e., as phenol-sulphate of potassium, 
c6h5o . S03K.] 
Phenol is derived from the decomposition of proteids by pancreatic digestion ($ 170, II), and 
also from putrefaction ($ 184, III), the mother-substance being tyrosin. Hence, the formation of 
phenolsulphuric acid is analogous to the formation of indican. 
If in the employment of carbolic acid it be absorbed, the phenolsulphuric acid becomes greatly 
increased in amount, so that sulphuric acid must be united with it; hence, alkaline sulphates are 
decomposed in the body, so that the latter may be absent from the urine (Baumann). Living 
Indoxyl sulphate of potash. Indigo blue. [Sec. 262. 
516 
SULPHURIC ACID AND ETHEREAL SULPHATES. 
muscle or liver, when digested in a stream of air for several hours with blood to which phenol 
and sodic sulphate are added, yields phenolsulphuric acid; while, under the same circumstances, 
pyrokatechin forms ethersulphuric acid. 
Carboluria.—When carbolic acid is used externally or internally, and it is absorbed, it causes 
a deep dark-colored urine due to the oxidation of phenol into pyrocatechin and hydroquinon 
(orthobioxybenzol = C6H602), which for the first part appears in the urine as ethersulphuric acid 
(Baumann and others). [These substances in an alkaline urine become brown on exposure to 
air, and produce the dark color of the urine in so-called carboluria.] 
3. Parakresol (C7H80), (hydroxyltoluol, with its isomers ortho- and 
meta-kresol (the latter in traces), is more abundant in urine (.Baumann, 
Preusse). It also occurs in conjugation with sulphuric acid. [It occurs as 
kresol sulphate of potassium, C7H70 . SOsK.] 
Test for phenol.—(and also kresol):—Distil 150 c.c. urine with dilute sulphuric acid. The 
distillate gives a brown crystalline deposit of tribromophenol with bromine water, as well as a 
red color with Millon’s reagent. 
Hydroxybenzol (pyrokatechin, hydroquinon) is obtained from urine when it is heated for a 
long time with hydrochloric acid. 
Resorcin, which is an isomer of hydroquinon, when administered internally, also appears in 
the urine as ethersulphuric acid. Toluol and naphthalin behave similarly. Benzol is oxidized 
to phenol. 
4. Pyrokatechin or Katechol, C6H602 (metadihydroxylbenzol), is formed 
along with hydroquinon from phenol, and is an isomer of the former. It be- 
haves like indol and phenol, for when united with sulphuric acid, it yields the 
pyrokatechin-forming substance. Small quantities sometimes occur in human 
urine; it is more abundant in the urine of children ; it becomes darker when 
the urine putrefies. 
5. Skatol [C8H6(CH3)N (methyl-indol)], which is crystalline, and is formed 
during putrefaction in the intestine, also appears in the urine as a compound of 
sulphuric acid (§ 252), [/.<?., as skatoxyl-sulphate of potassium, C9H8NO . - 
S03K]. On feeding a dog with skatol, Brieger found much potassic skatol- 
oxy-sulphate. 
Test.—Skatol compounds are recognized by adding dilute nitric acid, which causes a violet 
color, or fuming nitric acid, which precipitates red flakes (Nencki). Its quantity is regulated 
by the same conditions as indican. 
[It is important to notice that the aromatic combinations present in the urine 
occur as conjugated sulphuric acid compounds, /.<?., as ethereal sul- 
phates. Indol, phenol, and skatol, derived from the putrefactive decomposi- 
tion of proteids in the intestine, must somewhere after absorption unite with 
sulphuric acid—probably in the liver—to form these compounds, i.e., that in 
the liver poisonous compounds are converted into innocuous ones (p. 332). 
Baumann has shown that if the intestine be disinfected, the conjugated sulphuric 
acid disappears from the urine.] 
The aromatic oxyacids, hydroparacumaric acid, and paraoxyphenylacetic acid (the 
former a putrefactive product of flesh, the latter obtained by E. and H. Salkowski from putrid 
albumin) occur in the urine (Baumann, \ 252). Test.—Shake the urine treated with a 
mineral acid with ether, evaporate the latter, and dissolve the residue in water. If aromatic 
oxyacids are present, they give a red color with Millon’s reagent. 
Baumann gives the following series of bodies, which are formed from tyrosin by decomposi- 
tion and oxidation; most of the substances are formed both during the decomposition of albumin, 
and also in the intestine, whence they pass into the urine:—Tyrosin, C9HuN03 -j- H2 = 
C9H10O3 (hydroparacumaric acid) -j- NH3. C9H10O3 = C8H]0O (paraethylphenol, not yet proved) 
-f- C(J2. CgH10O + 03 = C8H803 (paraoxyphenylacetic acid) -f- H20. C8H803= C7HgO (para- 
kresol) C02. C7H80 + (J3 = C7H603 (paroxybenzoic acid, not yet proved) H20. C7H603 = 
C6H60 (phenol -(- C02. 
Potassium sulphocyanide, or thio-cyanate, derived from the saliva, 
also occurs in urine. [It passes into the intestine, is absorbed into the blood, Sec. 262.] 
SODIC CHLORIDE IN URINE. 
and is excreted in the urine.] After acidulation with hydrochloric acid, its 
presence may be detected by the ferric chloride test (§ 146—Gscheidlen and J. 
Munk). One litre of human urine contains 0.02 to 0.08 gram combined with 
an alkali. 
Succinic acid (C4H604) occurs chiefly after a diet of flesh and fat, and almost disappears 
after a vegetable diet. It is a decomposition-product of asparagin, and occurs in considerable 
amount in the urine after eating asparagus. It is also a product of the alcoholic fermentation 
(| 150), and as it passes out of the body unchanged, it occurs in the urine of those who imbibe 
spirituous liquors. It passes unchanged into the urine (Neubauer). 
Lactic acid (C3H603) is a constant constituent of urine. Some observers have found fer- 
mentable lactic acid in diabetic urine ; sarcolactic acid alter poisoning with phosphorus and in 
trichinosis. Occasionally traces of volatile fatty acids are present. Some animal gum occurs 
in urine (p. 488), and Bechamp’s “ nephrozymose ” consists for the most part of gum (Land- 
wehr). This substance is precipitated from urine by adding to it three times its volume of 90 
per cent, alcohol. It is not a simple body, but at 6o° to 70° C. it transforms starch into sugar 
(v. Vintschgau). 
Ferments.—Traces of diastatic, peptic, and rennet ferment have 
been found, especially in urine of high specific gravity. [Fibrin placed in 
urine absorbs the ferments.] Trypsin is said not to occur normally (Lea.) 
Traces of sugar (i. e., dextrose] (Brilcke, Bence Jones), to the amount of 0.05 to 0.01 per 
cent., occur in normal urine. [Bunge doubts the occurrence of sugar and lactic acid in normal 
urine.] After the ingestion of milk-, cane-, or grape-sugar (50 grms.) these varieties of sugar 
appear in small quantity in the urine ( Worm-Muller—§ 267, 7). 
Kryptophanic acid (C3H9N05), according to Thudichum, occurs as a free acid in urine, but 
Landwehr regards it as an animal gum. 
Reducing substances.—Substances which give Trommer’s test always 
occur in the urine. Normal human urine reduces cupric salts, like a 0.15-0.25 
solution of grape-sugar (more in fever.) About of these substances seem to 
be compounds of glycuronic acid (§ 275), and is due to uric acid and 
kreatinin (Flilckiger). 
Aceton (C3HbO) is formed when normal urine is oxidized with potassic bichromate and sul- 
phuric acid, and it is formed from a reducing substance present in normal urine (apparently 
derived from the grape-sugar of the blood). Aceton occurs in traces as a normal urinary con- 
stituent, which is increased during increased metabolism of the tissues, e.g., carcinoma, inanition. 
It has also been found in the blood in fever (v. Jaksch). Lieben’s Test.—Acidulate half a 
litre of urine with HC1 and distil; when treated with tincture of iodine and ammonia there is a 
turbidity due to iodoform (p. 530). 
II. THE INORGANIC CONSTITUENTS OF THE URINE. 
—The inorganic constituents are either taken into the body as such with the 
food and pass off unchanged in the urine, or they are formed in the body, 
owing to the sulphur and phosphorus of the food being oxidized and the pro- 
ducts uniting with bases to form salts. The quantity of salts excreted daily 
in the urine is 9 to 25 grams to oz.]. 
Sodic chloride—to the amount of 12 (10 to 13) grams [180 grains]—is 
excreted daily. It is increased, after a meal, by muscular exercise, drinking 
of water, and generally when the quantity of urine is increased, by the free use 
of large quantities of common salt, and by potash salts also; it is diminished 
under the opposite conditions. 
In disease it is greatly diminished ; in pneumonia and other inflammations accompanied by 
effusions, in continued diarrhoea and profuse sweating, constantly in albuminuria and in dropsies. 
[In cases of pneumonia, sodic chloride may at a certain stage almost disappear from the urine :— 
e. g., to 1 or 2 grams—at the crisis 8 grams, and the day after 16 grams—and it is a good sign 
when the chlorides begin to reappear.] In other chronic diseases, the amount of NaCl excreted 
runs nearly parallel with the amount of urine passed. In conditions of excitement the amount of 
sodic chloride is diminished, and potassic chloride increased; in conditions of depression the 
reverse is the case (Zeulzer). 
Tests for Chlorides.—Add to the urine nitric acid and then nitrate of silver solution, which 518 
PHOSPHORIC ACID. 
[Sec. 262 
gives a white curdy precipitate of chloride of silver. In albuminous urine the albumin must 
first be removed. Microscopically look for the step-like forms of common salt, and also for the 
crystals of sodic chloride and urea ($ 256, 4). 
[Estimation of Chlorides (Volhard’s method).—(1) A S.S. (/.<?., a 
standard solution) of silver nitrate is prepared so that 1 c.c. = .010 grm. NaCl 
or .006 of Cl. It is placed in a burette. (2) A 10 per cent, solution of neu- 
tral chromate of potash is used as the indicator. 
Place 2 c.c. of urine in a glass, add a few drops of (2), and drop in (1) from a burette = a 
red precipitate of chromate of silver, which disappears on shaking, giving place to a white pre- 
cipitate of silver chloride. Add S.S. until the fluid in daylight retains a red color (not orange), 
i. e., until all the chlorine has been precipitated, which is indicated by the persistence of the red 
color of the chromate of silver. Read off the number of c.c. of the S.S. used. Multiply the 
number of c.c. of urine passed by the number of c.c. of S.S. used and divide by 200. Suppose 
a person passed 2000 c.c. of urine in 24 hours and 2 c.c. of the S.S. were required to obtain the 
2000 x 2 
reaction, then = 20 grams of NaCl. 
200 & 
Mohr’s Method.—This simple method gives approximate results. Dilute 10 c.c. of urine 
with water to 100 c.c.; neutralize with carbonate of soda, add 3 drops of a concentrated solution 
of potassic chromate. Drop in from a burette a S.S. of silver nitrate (14.53 gnus. to 500 c.c. 
water), until on stirring a red color persists. Every c.c. of the S.S. = 10 milligrams of NaCl 
or .00607 gram of chlorine. 
2. Phosphoric acid occurs in urine [in the form of two classes of phos- 
phates,—(1) Alkaline phosphates] as acid sodic phosphate, acid po- 
tassic phosphate, and (2) Earthy phosphates,—acid calcic and mag- 
nesic phosphates to the amount of about 2 grams daily [30 grains] ; it is 
more abundant after an animal than after a vegetable diet. The amount 
increases after a mid-day meal until evening, and falls during the night until 
next day at noon. It is partly derived from the alkaline and earthy phosphates 
of the food, and partly as a decomposition-product of lecithin and nuclein. 
As phosphorus is an important constituent of the nervous system, the relative 
increase of phosphoric acid is due to increased metabolism of the nervous sub- 
stance. 
Pathological.—In fevers, the increased excretion of potassic phosphate is due to a consump- 
tion of blood and muscle ($ 220, 3). It is also increased in inflammation of the brain, soften- 
ing of the bones, diabetes, and oxaluria; after the administration of lactic acid, morphia, chloral, 
or chloroform. It is diminished during pregnancy, owing to the formation of the foetal bones; 
also after the use of ether and alcohol, and in inflammation of the kidney. 
[Tests.—To urine add nitric acid and solution of ammonium molybdate and boil, a canary- 
yellow precipitate of ammonium phosphomolybdate indicates the presence of phosphoric acid. 
Or, add half its volume of caustic potash to urine, and boil. The earthy phosphates are precipi- 
tated, but not the alkaline phosphates.] 
Earthy phosphates are precipitated by heat in some pathological urines. 
This precipitate is distinguished from albumin, which is also precipitated by 
heat, by being soluble in nitric acid, which precipitated albumin is not. [The 
earthy phosphates are not precipitated until near the boiling point.] 
[Quantitative Estimation of Phosphoric Acid.—The amount of phosphoric acid is esti- 
mated by titration with a standard solution of uranium acetate ; ferrocyanide of potassium 
being the indicator. The indicator gives a brownish-red color when there is an excess of free 
uranium acetate. 
Place 50 c.c. of filtered urine in a beaker, add to it 5 c.c. of a solution of sodic acetate (con- 
taining 100 grams of sodic acetate and 100 c.c. of acetic acid in 1 litre of water). In a burette 
place a S.S. of uranium acetate which is previously titrated to such a strength that 1 c.c. = 
.005 grm. phosphoric acid. Drop in the standard solution, until a drop of the mixture gives a 
faint brown color with a drop of the indicator (ferrocyanide of potassium). This is done on a 
porcelain slab. Boil and test again. If necessary, add a few more drops of the S.S. until the 
brown color reappears. Read off the c.c. of the S.S. used. Suppose 17 c.c. of the S.S. are 
used, then .005 x 17 = .085 grm. phosphoric acid in 50 c.c. urine. Suppose a patient passes 
1250 c.c. urine in 24 hours, then 50 : 1250 : : .085 : x) — 
1250 X .085 
50 =2.12 grams of phosphoric acid passed in 24 hours.] Sec. 262.] 
SULPHURIC ACID. 
519 
In addition to phosphoric acid, phosphorus occurs in an incompletely oxidized form in the 
urine, e.g., glycero-phosphoric acid [C3H9P06] (£ 251, 2), which occurs to the amount of 
15 milligrams in a litre of urine; it is increased in nervous diseases and after chloroform 
narcosis. 
3. Sulphuric acid occurs in the urine, the greater part in combination 
with the alkalies [/. e., as pre-formed or combined sulphuric acid], and 
the remainder united with indol, skatol, and pyrokatechin, in the form of aro- 
matic ether-sulphuric compounds, i. e., as conjugated sulphuric acid 
(p. 515), [forming the ethereal sulphates], the ratio being 1 : 0.1045. All 
conditions which favor the formation of indol, skatol, or pyrokatechin increase 
the amount of combined or conjugated sulphuric acid. The total daily 
amount of sulphuric acid is 2.5 to 3.5 grams [37 to 52 grains]. It is increased 
by the administration of sulphur (Krause). The sulphuric acid is chiefly de- 
rived from the decomposition of proteids, and hence its amount runs parallel 
with the amount of urea excreted. The amount of alkaline sulphates in the 
food is, as a rule, very small. 
Test for Sulphuric Acid.—Barium chloride gives a copious white heavy precipitate of 
barium sulphate, insoluble in nitric acid. 
An increased excretion of sulphuric acid in fevers indicates an increased metabolism of the 
tissues of the body. In renal inflammation it has been observed to be diminished, and in eczema 
it is greatly increased. Feeding with taurin (which contains sulphur), in the case of rabbits (but 
not in carnivora or man), increases the sulphuric acid in the urine (Salkowski). According to 
Ziilzer, a copious secretion of bile lessens the relative amount of sulphuric acid in the urine. 
In addition to sulphuric acid, sulphur Q) occurs in an incompletely oxidized form in the urine 
(potassium sulphocyanide, cystin, and sulphur-bearing compounds derived from the bile) (Kunkel, 
v. Voit—\ 177, 6). Hyposulphurous acid, as an alkaline salt, is an abnormal constituent in 
typhus; and so is sulphuretted hydrogen, which is recognized by the blackening of a piece of 
paper moistened with lead acetate and ammonia, held over the urine. 
Quantitative Estimation of Sulphuric Acid.—Acidulate strongly with acetic acid 50 c.c. 
of urine and add to it an equal volume of water and barium chloride. After being heated for 
an hour or so in the water-bath, the precipitate falls and is then collected on a filter, and washed 
with water, then with dilute HC1, and again with water. The baric sulphate purified in this way 
is then burned and weighed. It contains all the sulphuric acid which formed salts, i. e., all the 
combined sulphuric acid. 
The filtrate and the washings obtained after the above process contain the sulphuric acid com- 
bined with organic bodies. The filtrate and washing are mixed, to them is added of its 
volume of HC1, and the whole is heated for some time. Barium sulphate and a resinous sub- 
stance separate out. Filter, dissolve and wash the resinous substance off the filter with hot alco- 
hol, then wash with hot water, dry, and burn the deposit; 1 part barium sulphate corresponds to 
°-3433 H2S04. 
[It is important to notice that sulphur occurs in several combinations in 
urine, as the ordinary bibasic salts and the monobasic conjugated sulphuric 
acid. The latter forms about one-tenth of the average amount of ordinary sul- 
phuric acid. The ordinary sulphates are precipitated, after acidulation, by a 
soluble barium salt (see above). The filtrate still contains conjugated sulphuric 
acid. Add hydrochloric acid to the filtrate and boil; the conjugated sul- 
phuric acids are broken up and may also be precipitated as a salt of barium. 
The filtrate from this still contains some sulphur organically combined. Under 
certain circumstances cystin and sulphocyanides both containing sulphur occur 
in the urine.] 
4. Excessively minute traces of silicic acid and nitric acid derived from 
drinking water have been found in urine. Organic acids, e.g., citric and tar- 
taric, when taken internally, increase the amount of carbonates in the urine. 
The urine may effervesce on the addition of an acid. 
The sodium in the urine is chiefly combined with chlorine, but a small part 
of it is united with phosphoric and uric acids; potassium (which is about ]/$ 
of the sodium) is chiefly combined with chlorine. In fevers, more potash is 
excreted than soda, and during convalescence the reverse is the case; calcium 520 
FERMENTATION OF URINE. 
[Sec. 262. 
and magnesium exist in normal acid urine as chlorides or acid phosphates. 
If the urine is neutral, neutral calcium phosphate and magnesium phosphate 
are precipitated. Ebstein found the latter in alkaline urine, as large, clear four- 
sided prisms, in diseases of the stomach. If the urine is alkaline, calcium 
carbonate (fig. 338) and tribasic calcic phosphate are deposited as such, while 
the magnesium is precipitated in the form of ammonio-magnesium phosphate 
or triple phosphate. The calcium is derived from the food, and depends upon 
the amount of lime salts absorbed from the intestine. Free ammonia is said 
to occur (0.72 gram or 7 grains daily) in perfectly fresh urine (.Neubauer 
Briicke'), and the amount is greater with an animal than with a vegetable diet 
( Coranda). The amount of fixed ammonia is increased by the administration 
of mineral acids ( Walter, Schmiedeberg, Gathgens). Iron (1 to 11 milligrams 
per litre) is never absent. There is a trace of hydric peroxide (Schonbeiri), 
which is detected by its decolorizing indigo-solution on the addition of iron 
sulphate. 
Gases.—24.4 c.c. of gas was obtained from one litre of urine—100 volumes 
of the gases pumped out consisted 
of 65.40 vol. C02, 2.74 O, 13.86 
N. After severe muscular action, 
the amount of C02 may be doubled; 
digestion also increases it, copious 
drinking diminishes it. 
263. FERMENTATIONS 
OF URINE.—Acid Fermen- 
tation.— When perfectly fresh 
urine is set aside, it gradually be- 
comes more acid from day to day. 
This is called the “ acid fermen- 
tation.” It seems to be due to 
the development of special fungi 
(fig. 316, a), and the process is 
accompanied by the deposition of 
uric acid (c), acid sodium urate, 
in amorphous grains (b), and cal- 
cium oxalate (d). According to 
Scherer, the fungus and the mucus 
from the bladder decompose part 
of the urinary pigment into lactic and acetic acids. The latter sets free uric 
acid from neutral sodium urate, so that free uric acid and sodium urate must be 
formed. Butyric and formic acids have been found as abnormal decomposition- 
products of other urinary constituents. When the acid fermentation begins, 
the urine absorbs oxygen (.Pasteur). According to Briicke, it is the lactic acid, 
formed from the minute traces of sugar present in urine, which causes the 
acidity. According to Rohmann, who recognizes the acid fermentation as an 
exceptional phenomenon, the acids are formed from the decomposition of 
sugar, and from alcohol which may be present accidentally. While the urine 
is still acid, it becomes turbid and contains nitrous acid, whose source is entirely 
unknown. According to v. Voit and Hofmann, phosphoric acid and a basic 
salt are formed from acid sodium phosphate, whereby part of the uric acid is 
displaced from sodium urate, thus causing the formation of an acid urate. 
Alkaline Fermentation.—When urine is exposed for a still longer time, 
more especially in a warm place, it becomes neutral and ultimately ammoniacal, 
i. <?., it undergoes the alkaline fermentation (fig. 317). 
This condition is accompanied by the formation of the microccocus ureae 
Deposit in “ acid fermentation ” of urine, a, fungus ; 
b, amorphous sodium urate ; c, uric acid ; d, calcium 
oxalate. 
Fig. 316. Sec. 263.] 
ALBUMINURIA. 
521 
(fig. 317) (Pasteur, Cohn), and Bacterium ureae (figs. 317, 318), which 
causes the urea to take up water, and decompose into C02 and ammonia. 
[CON2H4 + 2H20 = (NH4),COs]. 
Urea. Ammonium carbonate. 
The property of decomposing urea belongs to many kinds of bacteria, including even the sar- 
cina of the lungs—whose germs seem to be universally diffused in the air. These organisms pro- 
duce a soluble ferment (Musculus), which, 
however, only passes from the body of the 
cells into the fluid after the cell or organism 
has been killed by alcohol (Lea). 
The presence of ammonia causes the 
urine to become turbid, and those 
substances which are insoluble in an 
alkaline urine are precipitated— 
earthy phosphates, consisting of 
the amorphous calcic phosphate, 
Fig. 317. 
Fig. 318. 
Deposit in ammoniacal urine (alkaline fermenta- 
tion). a, acid ammonium urate; b, ammonio- 
magnesium phosphate; c, bacterium ureae. 
Micrococcus ureae. 
acid ammonium urate (fig. 316, a), in the form of small dark granules cov- 
ered with spines; and, lastly, the large clear knife-rest or “coffin-lid ” form 
of ammonio-magnesic phosphate, or triple phosphate (fig. 339). [The 
last substance does not exist as such in normal urine, but it is formed when am- 
monia is set free by the decomposition of urea, the ammonia uniting with the 
magnesium phosphate. Its presence therefore always indicates ammoniacal 
fermentation of the urine.] In cases of catarrh or inflammation of the 
bladder, this decomposition may take place within the bladder, when the 
urine always contains pus-cells (fig. 323) and detached epithelium. When 
much pus is present, the urine contains albumin. Ammoniacal urine forms 
white fumes of ammonium chloride, when a glass rod dipped in hydrochloric 
acid is brought near it. [When ammonia is added to normal urine, triple 
phosphate is precipitated in a feathery form (fig. 341).] 
[Significance of Triple Phosphate.—If urine be alkaline when it is passed, and the alka- 
linity be due to a volatile alkali, i. e., to NH3, then decomposition of the urine has taken 
place, and this kind of urine is a sure sign that there is disease of the genito-urinary mucous 
membrane.] 
264. ALBUMIN IN URINE OR ALBUMINURIA.—Serum- 
albumin is the most important abnormal constituent in urine which engages 
the attention of the physician. It occurs in blood (§ 32), and its characters 
are described in § 249. [In some cases, perhaps in most cases, serum-globulin 
is present along with serum-albumin.] 
Causes of Albuminuria.—1. Serum-albumin may appear in urine without any apparent 
anatomical or structural change of the renal tissues. This condition has been called by v. 
Bamberger “ Hcematogenous albuminuria,” and by Leube “ physiological albuminuria,” although 
the latter term is not a good one. It occurs but rarely, however, and sometimes in healthy 
individuals when there is an excess of albumin in the blood plasma (e. g., after suppression of 522 
TESTS FOR ALBUMIN IN URINE. 
[Sec. 264. 
the secretion of milk), and after too free use of albuminous food. 2. As a result of increased 
blood-pressure in the renal vessels, e. g., after copious drinking. It may be temporary or it may 
be persistent, as in cases of congestion following heart disease, emphysema, chronic pleuritic 
effusions, infiltrations of the lungs, and after compression of the chest, causing congestion in the 
pulmonary circuit, which extends even into the renal veins, etc. 3. After section or paralysis 
of the vaso-motor nerves of the kidneys, which causes great congestion of these organs. The 
albuminuria, which accompanies intense and long-continued abdominal pain, is brought about 
owing to a reflex paralysis of the renal vessels. 4. After violent muscular exercise. [Senator 
found that forced marches in young recruits were very frequently followed by the appearance of 
albumin in the urine, which persisted for several days.] Convulsive disorders, e. g., epilepsy, 
the spasms of dyspnoea after strychnin poisoning, in shock of the brain, apoplexy, spinal 
paralysis, and violent emotions; the excessive use of morphia, which perhaps acts on the vaso- 
motor centres. 5. It may accompany many acute febrile diseases, e. g., the •exanthemata (scarlet 
fever), typhus, pneumonia, and pyaemia. In these cases it may be due to the increase of 
temperature paralyzing the vessels, but more probably the secretory apparatus of the kidney is 
so changed (e. g., cloudy swelling of the renal epithelium) that the albumin can pass through 
the renal membrane. 6. Certain degenerations and inflammations of the kidneys at several of 
their stages. 7. Inflammation or suppuration in the ureter or urinary passages. 8. Certain 
chemical substances which irritate the renal parenchyma, e. g., cantharides, carbolic acid. 9. 
The complete withdrawal of common salt from the food. The albumin disappears when the 
common salt is given again. 10. The epithelium may be in such a condition that it cannot 
retain the albumin within the vessels, due to imperfect nourishment and functional weakness of 
the excretory elements. This includes the albuminuria of ischaemia, and that after hemorrhage, 
in anaemia, scorbutus, icterus, diabetes. [Grainger Stewart finds that albuminuria is more com- 
mon among presumably healthy people than was formerly supposed.] [11. Besides the experi- 
mental conditions mentioned above, what is called experimental albuminuria may be produced by 
pressure on the renal vein, or by closing the renal artery for a short time and then removing the 
obstruction and allowing the blood to circulate.] 
[Besides being derived from the secreting parenchyma of the kidney, albumin may be present 
owing to admixture with the secretions from any part of the urinary tract, including the vagina 
and uterus in the female. In some cases the transudation of albumin is favored by changes in 
the capillary walls, the albumin being forced through by the intravascular pressure. Sometimes 
albuminuria occurs during the course of severe typhoid fever, and in acute fevers generally, 
where the temperature is persistently above 40° C. (104° F.). The high temperature alters the 
filtering membrane and permits the filtration of albumin.] 
[So-called Physiological Albuminuria.—This term has been applied to that condition of 
the urine where traces of albumin are found in individuals apparently in perfect health. John- 
son and Pavy cite such cases, while Posner asserts that all urine—even healthy urine—contains 
traces of proteids, whose presence is ascertained after concentrating the urine. It is safe to 
assume that normal urine should give no reaction with the usual tests for albumin. Posner pre- 
cipitated the urine with alcohol, washed the precipitate, dissolved it in acetic acid, and tested it, 
with the ferrocyanide test for albumin. He finds that minute traces of proteid are detected by 
the following modification of the biuret test: Make the urine alkaline, and by the “ contact 
method ” bring a layer of very dilute cupric sulphate over it; when the two fluids touch, a 
reddish-violet ring is obtained.] 
The tests for albumin in urine depend upon the facts that it is coagu- 
lated by heat in neutral or acid solutions, and it is precipitated by various 
reagents. 
[(1) Heller’s Test.—Place 10 c.c. of the urine in a test-glass, and pour in pure colorless 
HN03 so as t0 run down the side of the glass, forming a layer beneath the urine. A white zone 
of coagulated albumin indicates the presence of albumin. In this test it is important to wait a 
certain time for the development of the reaction. In urines of high specific gravity, a haziness due 
to acid urates may be formed above where the two fluids meet, but its upper edge is not circum- 
scribed. The acid decomposes the neutral urates and forms a more insoluble acid salt. This 
cloud of acid urates is readily dissolved by heat, while the albumin is not; the latter is always a 
sharply defined zone between the two fluids. In very concentrated urine (rare), nitric acid may 
gradually precipitate crystalline urea nitrate. In patients taking copaiba, nitric acid, by acting 
on the resin, causes a slight milkiness.] 
[(2) Boiling and Nitric Acid.—Place 10 c.c. of urine in a test-tube and boil. If albumin 
be present in small quantity, a faint haziness, which may be detected in a proper light, will be 
produced. Add 10 to 12 drops of HN03. If the turbidity disappears it is due to phosphates, 
while if any remains it is due to albumin. If albumin be present in large quantity, a copious 
whitish coagulum is obtained. Precautions.—(«) In all cases, if the urine be turbid, filter it Sec. 264-] 
TESTS FOR ALBUMIN IN URINE. 
523 
before applying any test. (b) How to boil.—Boil the upper strata of the liquid, and take care, 
if any coagulum be formed, that it does not adhere to the side of the tube, else the tube is liable 
to break, (c) In performing this test with a neutral solution, note when the precipitate falls, for 
albumin is precipitated about 70° C., phosphates not till about the boiling point. (d) Amount of 
Acid.—If too little (2 or 3 drops) HNOs be added, or too much (30 or 40 drops), we may fail 
to detect albumin, although it is present.] 
(3) Ferrocyanide Test.—By the addition of acetic acid and potassium ferrocyanide. [If 
albumin be present, a white flocculent precipitate separates in the cold. Dr. Pavy has intro- 
duced pellets, consisting of a mixture of citric acid and sodic ferrocyanide. All that is required 
is to add a pellet to the suspected urine. Oliver’s Papers.—Dr. Oliver uses papers, one satu- 
rated with citric acid and another with ferrocyanide of potassium. The two papers are added to 
the clear filtered urine. Other precipitants of albumin, such as small pieces of paper impreg- 
nated with potassio-mercuric iodide, are used by Oliver.] 
(4) Boiling Acid Urine.—If the urine be alkaline, although albumin may be present, it is 
not precipitated by heat alone. We require to add acetic acid until a slightly acid reaction is 
obtained. Boiling may give a precipitate of earthy phosphates in an alkaline urine, owing 
perhaps to the C02 being driven off. This precipitate might be mistaken for albumin, but 
on adding acetic acid or nitric acid, the earthy precipitate is dissolved, while the precipitate of 
albumin is not dissolved. In testing for albumin, always use clear urine. If it is turbid, 
filter it. 
[(5) Metaphosphoric acid is dissolved in water just before it is to be used and added to 
clear urine (Hindenlang). Graham pointed out that metaphosphoric acid precipitated albumin. 
A 20 per cent, solution of the ordinary glacial phosphoric acid is a good test for albumin, but it 
also precipitates peptones. It, however, changes into ordinary phosphoric acid by keeping, and 
then it no longer precipitates albumin.] 
[(6) Sodic Sulphate and Acetic Acid.—Acidulate 10 c.c. of urine with acetic acid, and 
add )4 °f its volume of a concentrated solution of sulphate of soda or magnesia. On heating, 
if albumin be present, a distinct cloudiness is obtained.] 
[(7) In picric acid, according to Dr. Johnson, we have a more delicate test for minute traces 
of albumin than either heat or nitric acid, or than both these tests combined. It is used either 
in the form of crystals or powder, or as a saturated aqueous solution. Take a four-inch column 
of urine in a test-tube, hold the tube in a slanting direction, and pour an inch of the picric acid 
solution on the surface of the urine, where, in consequence of its low specific gravity (1005), it 
mixes only with the upper layer of the urine. It coagulates any albumin present. The precipi- 
tate occurs at once, and is increased by heat, while the urate of soda, which is sometimes precipi- 
tated, is soluble on heating. Peptones and albumoses are also precipitated by this reagent, but 
the precipitate redissolves on heating.] 
[(8) Potassio-mercuric iodide, or Tanret’s reagent, gives a white precipitate. This is a 
very delicate test, but it also precipitates peptones and albumoses (but these precipitates are dis- 
solved by heat), alkaloids, and bile-salts. The reagent consists of mercuric chloride, 1.35 grams; 
potassium iodide, 3.32 grams; acetic acid, 20 c.c.; and water, 64 c.c.] 
[Dr. Roberts regards any test for albumin which requires strong acidulation with an organic 
acid, citric, acetic, or lactic, as unsatisfactory, since it precipitates mucin. For this reason he 
rejects the tungstate, mercuric iodide, and potassic ferrocyanide tests. Dr. Roberts regards the 
heat test, with the addition of a small definite quantity of acetic acid, as the best test for the 
detection of small quantities of albumin.] 
1. Quantitative Estimation of albumin.—100 c.c. of urine are boiled in a capsule, some 
acetic acid being ultimately added, whereby the albumin is precipitated in flakes. The pre- 
cipitate is collected on a weighed, dried (no°), ash-free filter, and repeatedly washed with hot 
water, then with alcohol, and dried in an air-bath at 1 io°. The weight of the filter is deducted, 
and finally the dried filter with the albumin is burned in a weighed platinum capsule, and the 
weight of the ash also deducted. [This method is not available for the busy practitioner on 
account of the time it takes. Practically, it is sufficient to compare from day to day the propor- 
tion that the precipitated albumin bears to the bulk of the urine tested. A graduated tube may 
be used, so that after the precipitate has subsided, the physician may see what proportion of the 
whole the precipitate occupies.] 
Esbach’s Albuminimeter (fig 319).—A glass cylinder is filled with the urine up to the 
mark U, and to R with the precipitant (20 citric acid, 10 picric acid, 970 water). The vessel is 
corked and turned upside down several times to secure the mixture of the fluids. After twenty- 
four hours the coagulated albumin subsides, when the graduation on the tube indicates the 
number of grams of albumin per 1000 c.c. of urine. Very albuminous urine must be previously 
diluted. [Suppose the amount of deposit to reach to 3, and the patient passed 1800 c.c. of 
urine in 24 hours, the amount of albumin is 1.8 X 3 = 5.4 grams in 24 hours. That is, 3 grams 
1800 X 3 
in 1000 c.c., therefore = s.4.] 
’ 1000 j t j BLOOD AND BLOOD-PIGMENT IN URINE. 
[Sec. 264. 
2. Serum-globulin occurs only in albuminous urine, and is frequently present. Its 
presence is ascertained by [neutralizing and] adding powdered magnesium 
sulphate in excess to the urine; when it is present it is precipitated ($ 32). The 
more globulin there is in the presence of albumin, the more difficult it is to pre- 
cipitate it. Sometimes, when an albuminous urine is dropped into a large cylinder 
of water, each drop as it sinks is followed by a milky train, and when a sufficient 
number of drops have been added, the water becomes opalescent, the opalescence 
disappearing on adding an acid. The globulin is kept in solution by common salt 
and other neutral salts, but when these are largely diluted, the globulin is precipi- 
tated [Roberts). 
3. Peptone occurs in some specimens of albuminous urine, but also in non- 
albuminous urine. Maixner found it constantly in the urine in all cases where 
suppuration is present, and even in phthisis, constituting pyogenic peptonuria. 
Peptone occurs in pus, and the peptonuria in these cases is a sign of the breaking 
up of the pus-cells [Hofmeister). Also when many leucocytes are broken up in 
the blood (haematogenic). It occurs in cases where there is great disintegration 
of albuminous tissues, e.g., in cancer, [suppurative diseases, empyema, croupous 
pneumonia, phosphorus-poisoning, etc.]. It is frequently found after child-birth. 
Ammonium sulphate precipitates all proteids except peptones (p. 475). 
[The only satisfactory test for peptone is to precipitate all the other proteids with 
ammonium sulphate, and any proteid remaining in solution in the filtrate must 
then be peptone. Many of the so-called cases of peptonuria (Martin) (in sup- 
purative diseases) are really due to the presence of deutero-proteose. This last 
substance gives all the reactions for peptone except the following two. It is 
precipitated by ammonium sulphate, while peptone is not. It gives no precipitate 
with nitric acid unless a considerable amount of salt is added, and this precipitate 
disappears on heating and reappears on cooling, while peptone gives no precipitate 
with nitric acid.] 
[When peptone is injected into the blood it is excreted in the urine as peptone 
(p. 37). Deutero-albumose similarly injected appears as peptone.] 
Test.—Separate the albumin by boiling and the addition of acetic acid. Treat 
the filtrate with three volumes of alcohol; this precipitates the peptone, which, 
when dissolved in water, gives the characteristic reactions for peptone (§ 166, 1). 
4. Proteoses, i.e., Hemialbumose or propeptone occur very rarely, e.g., in 
osteomalacia and intestinal tuberculosis [Bence Jones). The urine is heated to 
saturation with NaCl and a large quantity of acetic acid added, and filtered while 
hot, to separate the albumin and globulin. In the cold filtrate hemialbumose forms a 
turbidity, which is redissolved by heat. The precipitate thrown down by HC1 and HNOs is soluble 
by heat [Kuhne). The precipitate is isolated by filtration, and dissolved in a little warm water, 
when it gives with HN03 a yellow reaction; like peptone the solution gives the biuret-reaction 
(p. 478). [Another proteose occurring in the urine is the deutero-proteose, which has been 
mistaken for peptone (see above).] 
5. Egg-albumin appears in the urine when much egg-albumin is taken in the food, and also 
when it is injected into the blood-vessels (§ 192, 4). According to Semmola, the albumin 
present in the urine in Bright’s disease has undergone a molecular change (similar to egg- 
albumin), and hence it is excreted. 
6. Mucus is present in large amount, especially in catarrh of the bladder. It contains 
numerous mucous corpuscles, which are scarcely distinguishable from pus corpuscles. They con- 
tain albumin, so that urine containing much mucus is albuminous; mucin is not precipitated 
by heat, but acetic acid gives a flocculent precipitate in clear urine. [Minute traces of mucin 
occur normally in urine. If clear normal urine be set aside for a short time, a flocculent hazi- 
ness. like a cloud of cotton wool, is seen floating in the urine. This is mucus entangling a few 
epithelial cells from the genito-urinary tract. Mucin Reaction.—According to W. Roberts, 
the addition of a concentrated solution of citric acid to urine, as in Heller’s test (§ 264, a), 
where the two fluids meet, causes an opalescent zone gradually to be formed above the layer of 
acid.] 
265. BLOOD (HEMATURIA) AND BLOOD-PIGMENT 
(HEMOGLOBINURIA) IN THE URINE.—I. Source of the 
Blood.—(1) In haematuria, the blood may come from any part of the 
urinary apparatus. 
1. In hemorrhage from the kidney, the amount of blood is usually small and well mixed 
with the urine. The presence of “ blood-cylinders,” long microscopic blood coagula, casts of 
the uriniferous tubules, washed out of them by the urine, is characteristic when they are found 
Fig- 319- 
Esbach’s 
albumini- 
meter. Sec. 265.] 
BLOOD AND BLOOD-PIGMENT IN URINE. 
525 
in the urine (fig. 332). The urine usually has a smoky appearance. [The urine slowly dissolves 
out the coloring matter, the stroma of the corpuscles after a time being deposited as a brownish 
sediment. The smoky hue occurs only in acid urine; if the urine becomes alkaline, the hue 
becomes brighter red.] The blood-corpuscles show peculiar changes of form, [they become 
crenated] (fig. 320), and exhibit evidence of division, due to the action of urea on them (§ 5). 
Large coagula are never found in urine mixed with blood derived from the kidney. 2. In 
hemorrhage from the ureter, we occasionally find worm-like masses of clotted blood, casts of 
the canal of the ureter. 3. The relatively largest coagula occur in hemorrhage from the 
bladder. In all cases where blood is present, we must examine microscopically for the blood- 
corpuscles, and it may be for coagula of fibrin. In acid urine, blood-corpuscles, but never 
arranged in rouleaux, may be found after two or three days. The blood-corpuscles settle as a 
red sediment at the bottom. If the hemorrhage is copious, many retain their original shape, 
but if the urine is very concentrated, they may become crenated. 
When there is a small and slow hemorrhage from ruptured small capillaries, the red blood- 
corpuscles are of unequal size, many ]/% to the size of normal, while the pigment has 
become brownish-yellow (fig. 321). 
If a hemorrhage of this kind be accompanied by catarrhal inflammation of the bladder, 
there is found between the red, numerous shrivelled leucocytes (fig. 321), which in freshly passed 
urine often exhibit lively amoeboid movements. If the urine be alkaline, as it usually is, crystals 
of triple phosphate also occur. 
If the remains of the red blood-corpuscles become very pale, their presence may be frequently 
ascertained by adding iodine in a solution of KI (fig. 321). Blood is constantly present in the 
urine during menstruation. 
Fig. 320.—Crenated red blood-corpuscles in urine, x 35°- Fig- 321-—Peculiar changes of the 
red blood-corpuscles in renal haematuria. Fig. 322.—Colored and (a) colorless blood 
corpuscles of various forms. Fig. 323.—Shrivelled blood-corpuscles in urine (catarrh of 
the bladder), with numerous lymph-corpuscles, and crystals of triple phosphate, x 350. 
Fig. 320. 
Fig. 321. 
Fig. 322. 
Fig. 323- 
II. Haemoglobinuria is quite distinct from hgematuria. It depends upon 
the excretion of haemoglobin as such through the kidneys, and it is pro- 
duced when haemoglobin occurs free within the blood-vessels, as in cases where 
the colored blood-corpuscles have been dissolved inside the blood-vessels 
(hsemocytolysis). 
It occurs when foreign blood is transfused, e.g., when lamb’s blood is transfused into man. 
The foreign blood-corpuscles are dissolved in the blood of the recipient, and the haemoglobin 
appears in the urine 102). In addition, microscopic “ cylinders,” or “ casts,” consisting of 
a globulin like body, tinged yellow with haemoglobin, may likewise be found in the urine. It 
also occurs in cases of severe burns (§ 10, 3); after decomposition of the blood in pyaemia, 
scorbutus, purpura, severe typhus, after respiring arseniuretted hydrogen, and after the passage 
of azobenzol, naphthol, pyrogallic acid, potassic chlorate, chloral, phosphorus, or carbolic 
acid into the circulation. [The injection of laky blood, water, ether, glycerin (Adams), or 
toluylendiamin (Affanassiew), also causes it, and in such cases Affanassiew asserts that the 
Hb passes out through the glomeruli, while brown degeneration-products of the red blood- 
corpuscles, which are dissolved by these agents, were found in the convoluted tubules.] These 
substances dissolve the red blood-corpuscles. Sometimes it occurs periodically from causes 
and conditions as yet but little understood, e.g.. the application of cold to the skin. [In 
paroxysmal haemoglobinuria, which occurs during periodic febrile attacks, haemoglobin may 
be present in the urine, but generally there is also methaemoglobin, which does not seem to be 
due to the action of the urine on the pigment, but the methaemoglobin seems to be secreted as 
such in the kidney.] 526 
BILE IN URINE. 
[Sec. 265. 
Tests for Blood in Urine.—1. The color of bloody urine shows every tint, from a faint red 
to a dark blackish-brown, according to the amount of blood present. The urine is often turbid. 
2. Urine containing blood or blood-pigment contains albumin. 
3. Heller’s Blood Test.—Add to urine half its volume of solution of caustic potash, and 
heat gently. The earthy phosphates are precipitated, and they carry the hsematin with them, 
falling as garnet red flocculi. [This is not a reliable test.] 
4. Haemin Test.—The colored earthy phosphates may be collected on a filter, and from 
them haemin may be prepared as directed in § 19. 
5. Almen’s Test.—Add to urine, freshly prepared tincture of guaiacum and ozonized ether; 
a blue color indicates the presence of blood ($ 37). 
6. Spectroscope (see \ 14). Fig. 324 shows the arrangement of the apparatus. The urine 
is placed in a glass vessel, D, with parallel sides, 1 centimetre apart (haematinometer). Light 
from a lamp, E, passes through the fluid. The lamp, F, illuminates the scale, which is seen by 
the observer through the telescope, A. (a) Fresh urine containing blood gives the spectrum 
of oxyhaemoglobin (fig. 23). (b) When bloody urine is exposed for some time, especially in 
a warm place, it becomes more acid, and assumes a dark brownish-black color. The haemo- 
globin becomes changed into methaemoglobin (§ 15). It is precipitated by lead acetate, which 
Fig. 324. 
Spectroscope for investigating the presence of haemoglobin in urine. 
does not precipitate oxyhsemoglobin ; the spectrum of methaemoglobin resembles that of haematin 
in an acid solution ($ 15, fig. 23). The spectra may be combined, (c) The microscopic in- 
vestigation must never be omitted. The shape of the corpuscles may vary considerably (figs. 
320-322). 
266. BILE IN URINE (CHOLURIA).—The physiological condi- 
tions which cause the bile constituents to appear in the urine are mentioned in 
part at § 180. 
Haematogenic or Anhepatogenic Icterus [Quincke), occurs when bilirubin (§ 20) is formed 
from extravasated blood by the action of the connective-tissue corpuscles, so that bile pigments, 
in addition to coloring the tissues, pass into the urine. 
I. Bile Pigments.—Their presence is ascertained by Gmelin-Heintz’s test. Green 
(Biliverdin) is the characteristic hue in the play of colors obtained with this test, which is fully 
described in \ 177. 
Modifications of the Test.—I. If icteric urine be filtered through filtering or blotting paper, 
a drop of nitric acid containing nitrous acid, when applied to the inner surface of the spread-out 
filter, gives a yellowish-colored ring [Rosenbach). 2. In order that the reaction may not take Sec. 266.] 
SUGAR IN URINE. 
527 
place too rapidly, add a concentrated solution of sodic nitrate, and then slowly pour in sulphuric 
acid (Fleischl). 3. On shaking 50 c.c. of icteric urine with 10 c.c. of chloroform, the bilirubin is 
dissolved by the latter. On adding bromide water, a beautiful ring of colors is obtained (Maly). 
If the chloroform extract be treated with ozonized turpentine and dilute caustic potash, a green 
color, due to biliverdin, occurs in the watery fluid (Gerhardt). 
[Marechal’s Test.—Pour tincture of iodine (B.P.) on the surface of the urine in a test-tube. 
A green color appears if bile pigments are present.] 
In slight degrees of jaundice, urobilin alone may be found (§ 261, 1) (Quincke). 
In persistent high fever, the urine contains especially biliprasin (Huppert). If it contains 
choletelin alone, add to the urine some hydrochloric acid, and examine it with the spectroscope, 
which gives a pale absorption-band between b and F ($ 177, 3,f). 
Haematoidin.—Sometimes crystals of hcematoidin (§ 20, fig. 27) appear in the urine, especi- 
ally when blood-corpuscles are dissolved within the blood-stream; occasionally in scarlet fever 
and typhus, and sometimes in cases of periodic haemoglobinuria. The breaking up of old blood- 
clots in the urinary passages, as in pyonephrosis (Ebstein), or the dissolution of necrotic areas 
(Hofmann and Ultzmann) produces them, and similar crystals occur in analogous cases in the 
sputum (| 138). In jaundice due to congestion ($ 180), the identical crystalline substance, 
bilirubin, is found. 
II. Bile acids occur in largest amount in absorption jaundice, but they are never present to 
any extent. The test is described at § 177, 2, the cane-sugar solution consisting of 0.5 grm. to 
1 litre of water. If the urine be dilute, it is advisable to concentrate it on a water-bath. [It is 
rare to get a satisfactory result with Pettenkofer’s test in ordinary icteric urine.] V. Pettenkofer’s 
test may be used with the alcoholic extract of the nearly dry residue, but no albumin must be 
present. Dragendorff found 0.8 grm. in 100 litres of normal urine. 
Strassburg’s Modification.—Dip filter paper into the urine, to which a little cane-sugar has 
been added; dry the paper and apply to it a drop of sulphuric acid. A violet-red color is ob- 
tained after a short time. [Hay’s Reaction 177). Icteric urine precipitates the albumin 
in a solution of acid-albumin (§ 181 G.).] 
267. SUGAR IN URINE (GLYCOSURIA).—Diabetes Mellitus. 
—The excessively minute trace of grape-sugar or dextrose, which is con- 
stantly present in normal urine, sometimes becomes greatly increased and con- 
stitutes the conditions of diabetes mellitus and glycosuria. The physio- 
logical conditions which determine this result are given at § 175. In this 
condition, the quantity of urine is greatly increased; it may reach 10 or 
more litres. Many pints may be passed daily. [The usual abnormal amount 
of sugar is from 1 to 8 per cent., although 15 per cent, has been found, i.e., 
from 5 to 50 grs. per fluid oz., or 300 to 3000 grs. in twenty-four hours.] The 
specific gravity is also increased (1030 to 1040). [In a case where a large 
amount of urine is passed of a pale color and a specific gravity above 1030, 
always suspect sugar.] A diabetic person gives off relatively more water by 
the kidneys and less by the skin (and lungs?) than a healthy person. The 
color is very pale yellow, although the amount of pigment is by no means 
diminished—it is only diluted [the depth of the color being inversely as the 
quantity passed]. The amount of the nitrogenous urinary excreta is increased. 
The sugar is increased by a diet of carbohydrates and diminished by an albu- 
minous diet. The uric acid and oxalate of lime are often increased at the 
commencement of the disease, while yeast cells are constantly present after the 
urine has been exposed to the air for some time. 
[In diabetes insipidus there is a very copious secretion of watery urine 
without the presence of sugar. It may be produced experimentally by injury 
to a certain part of the floor of the fourth ventricle, and it occurs as a diseased 
condition. It seems to depend on some derangement of the central vaso-motor 
apparatus of the kidney.] 
Sugar has been found occasionally [z. e., transitory glycosuria] after poisoning with or after 
the use of morphia, CO, chloral, chloroform, curare (?) (p. 529); after the injection of ether and 
amyl-nitrite into the blood; and in gout, intermittent fever, cholera, cerebro-spinal meningitis, 
hepatic cirrhosis, and cardiac and pulmonary affections. 
[There is no doubt that normal healthy human urine contains one or more reducing agents, 
which reduce cupric oxide to the same extent as if the urine on an average contained 6 grains TESTS FOR SUGAR. 
[Sec. 267. 
of glucose in every io fluid ounces of urine, or 1.34 grms. per litre. As this substance does 
not cause alcoholic fermentation in its solutions, its identity with glucose appears to be 
doubtful. The most active reducing agent is probably kreatinin (G. S. Johnson). But Feh- 
ling’s solution is also reduced by uric acid, hippuric acid, pyrocatechin, and glycuronic acid 
(p. 529). The only way to distinguish these from dextrose is the fermentation-test. None of them 
ferment with yeast to yield alcohol and C02.] 
Tests for Sugar.—Any of the tests described at \ 149 may be used, but the urine must be 
free from albumin. The quantitative estimation by fermentation and the titration methods are 
described in \ 149. [The tests for grape-sugar described in § 149 are (1) Trommer’s; (2) Feh- 
ling’s; (3) Moore & Heller’s; (4) Bottger’s; (5) Mulder & Neubauer’s; (6) Fermentation 
test; (7) Molisch’s test.] 
8. Worm-Muller recommends the following modification of Fehling’s test: Use a 2.5 per 
cent, solution of cupric sulphate solution, and another of 10 parts of sodio-potassic tartrate in 
100 parts of 4 per cent, solution of soda. Boil 5 c.cm of urine in a test-tube, while in a second 
test-tube is boiled I to 3 c.cm. of the copper solution and 2.5 c cm of the potassic-tartrate solu- 
tion. The boiling of both fluids is stopped simultaneously, and after 20 to 25 seconds the con- 
tents of one test-tube are added to those of the other, but without shaking the mixture, the 
reduction taking place spontaneously. 
9. Nylander’s modification of Bottger’s test is also good (f 149). 
[10. Picric Acid and Potash Test.—Braun showed that grape-sugar, when boiled with 
picric acid and potash, reduces the yellow picric acid to the deep red picramic acid, the depth of 
the color depending on the amount of sugar present. 
Dr. Johnson uses this test for detecting the presence 
of sugar in urine, and also for estimating the amount 
of sugar present, the depth of the red color obtained 
on boiling being compared with a standard dilution 
of ferric acetate. In doing the test, use 1 drachm 
of urine, a drachm of liquor potassse, and 10 min- 
ims of picric acid solution; make up to 2 drachms 
with distilled water, and boil the mixture for one 
minute. This test indicates the presence of 0.6 
grain of sugar per fluid ounce of normal urine. 
Dr. Johnson claims for this test that it possesses all 
the advantages of the other tests, while it is not af- 
fected by uric acid or any other normal ingredient 
of urine; neither does the presence of albumin 
interfere with the action of the test as it does with 
all the forms of copper testing.] 
[11. Indigo-carmine Test.—A blue solution of 
this substance, when boiled with diabetic urine con- 
taining sodic carbonate, changes from a blue to 
a violet, purple, red, yellow, and finally, straw- 
yellow color. After cooling and exposure to the 
air, the various colors are obtained in the re- 
verse order until the mixture becomes blue again. 
Dr. Oliver uses this test in the form of test-papers. One bibulous paper is impregnated with 
the indigo-carmine and the other with sodic carbonate. Drop one of the test-papers and a sodic 
carbonate paper into a test-tube containing 1 inch of water, heat gently, when a blue solution 
is obtained. Add the urine slowly, one drop at a time, and boil the mixture, observing any 
change of color by holding the tube against a white surface below the level of the eye. Uric 
acid and urates, which reduce Fehling’s solution, do not affect the carmine test, nor does krea- 
tinin, although it reacts with the picric acid test.] 
[12. Phenyl-hydrazin Test.—It depends on the fact that glucose forms with phenyl-hydrazin 
a characteristic body, phenyl-glucosazon, which takes the form of yellow needles, and is but 
little soluble in water. Two parts of phenyl-hydrazin chloride and three of sodic acetate are 
placed together in a test-tube containing 6-8 c.c. urine, and the test-tube is placed for 20-30 
minutes in boiling water. After this the tube is put into a vessel containing cold water. If sugar 
be formed, a yellow deposit separates, which, when examined with the microscope, is seen to 
consist of crystals of phenyl-glucosazon, either detached or arranged in clusters (fig. 325). The 
substance melts at 205° C. Albumin, if present, should be got rid of previously.] 
[Quantitative Estimation of Sugar.—(a) Fermentation Test (§ 150). Take 4 oz. 
(120 c.c.) of the urine; add a lump of German yeast, about the size of a walnut, lightly cork 
the bottle, and place it aside for twenty four hours in a moderately warm place, e.g., on the 
mantelpiece. Take the specific gravity before and after the fermentation. Thus, if the specific 
gravity be 1038 before and 1013 afterwards, the difference or “ density lost” is 25, which gives 
Fig- 325- 
Phenyl-glucosazon crystals from urine con- 
taining sugar. Sec. 267.] 
ESTIMATION OF SUGAR. 
529 
25 grs. of sugar per fluid oz. (Roberts). If it be desired to get the percentage, multiply the 
density lost by 0.23, thus 25 x 0.23 = 5-69 in 100 parts.] 
[(£) Volumetric Analysis of Sugar.—10 c.c. of Fehling’s solution = .05 gram of sugar. 
1. Ascertain the quantity of urine passed in twenty-four hours. 2. Filter the urine, and 
remove any albumin present by boiling and filtration. 3. Dilute 10 c.c. of Fehling’s solution 
with about twenty times its volume of distilled water, and place it in a white porcelain capsule 
on a wire gauze support under a burette. (It is diluted because any change of color is more 
easily observed.) 4. Take 5 c.c. of the urine, and 95 c.c. of distilled water, and place the 
diluted urine in a burette. 5. Gradually boil the diluted Fehling’s solu- 
tion, and whilst it is boiling gradually add the diluted urine from the 
burette, until all the cuprous oxide is precipitated as a reddish powder, and 
the supernatant fluid has a straw-yellow color, not a trace of blue remain- 
ing. Read off the number of c.c. of dilute urine employed. Say 36 c.c. 
were used—that, of course, represents 1.8 c.c. of the original urine. Sup- 
pose the patient passes 1550 c.c.; as 1.8 c.c. of urine reduced all the 
cupric oxide in the 10 c.c. of Fehling’s solution, it must contain .05 gram 
sugar, hence, 
1.8: 1550 :: .05 : X -°5 __ 237.5 grams of sugar passed in 24 hours.] 
1.8 
[Preparation of Fehling’s Solution.—34.64 grams of pure crystal- 
line cupric sulphate are powdered and dissolved in 200 c.c. of distilled 
water; in another vessel dissolve 173 grams of Rochelle salts in 480 c.c. 
of pure caustic soda, specific gravity 1.14. Mix the two solutions, and 
dilute the deep-colored fluid which results to 1 litre. N. B.—Fehling’s 
solution ought not to be kept too long; it is apt to decompose, and should 
therefore be preserved from the light, or protected with opaque paper 
pasted on the bottle. Some other substances in urine, e.g., urates and uric 
acid, reduce cupric oxide.] 
(z) According to Worm-MUller, the polarization method is almost value- 
less for diabetic urine. 
[Picro-Saccharimeter.—G. Johnson uses a stoppered bottle 12 inches 
long and inch wide, graduated in and (fig. 326). To it is 
fixed a shorter bottle containing the standard iron solution for comparison, 
a standard solution, composed of liquor ferri perchloride gj, liq. ammon. 
acetatis 3 iv, glacial acetic acid giv, liq. ammonise gj, and water to make 
up giv. All B.P. preparations give a color identical with a solution 
containing 1 gr. of grape-sugar per oz., reduced by picric acid and after- 
wards diluted four times, so that this tint = gr. of sugar per oz. After 
reducing the sugar with the picric acid, pour into the tall tube the dark 
saccharine liquid produced by boiling to occupy ten divisions of the tube, 
and add distilled water cautiously until the color approaches that of the 
standard; read off the level of the fluid. The amount of sugar present is 
determined from the amount of water added. In making the test, the 
picric acid must be added in proportion to the amount of sugar present.] 
If large quantities of dextrose are taken in the food, a part of it (and more in diabetic per- 
sons) appears in the urine. Lsevulose, when taken internally, does not increase the amount of 
sugar in diabetes. The free use of starch does not cause glycosuria in health, but in diabetes it 
increases the amount of sugar. A large consumption of cane- or milk-sugar causes the passage 
of small quantities of both of these sugars into the urine in health, while in diabetes the amount 
of dextrose is increased (Worm-Muller). According to Kiilz, in diabetic persons cane-sugar 
splits up into grape- and fruit-sugar, the latter being used up in the body, and the former partly 
excreted ; and the same is the case with milk-sugar. 
In severe cases of diabetes mellitus, Kiilz found the left-rotatory /3-oxybutyric acid (the 
next highest analogue of lactic acid) in the urine, from which acetic acid is formed by oxidation 
($ I75)> which in its turn readily yields C02 and aceton. a-crotonic acid is formed in urine by 
the removal of water from oxybutyric acid in the urine in diabetes (Stadelmann). The adminis- 
tration of aceton causes albuminuria, and this may in part explain in some cases the complica- 
tion of albuminuria in diabetes [Albertoni and Pisenti). 
[Glycuronic acid (C6H10O7) occurs in such excessively small quantities in normal urine that 
it may be regarded as absent. It is the substance which above all others is most liable to be 
mistaken for sugar (p. 528). The other substances mentioned on p. 528 which reduce Fehling’s 
solution, do so only to a small extent, but glycuronic acid does so like dextrose. It occurs in 
the urine in large amount after the administration of chloroform, chloral, butyl-chloral, curare, 
Picro-saccharimeter 
of G. Johnson. 
Fig. 326. ACETONURIA AND CYSTINURIA. 
[Sec. 267. 
and morphia. It, however, does not undergo the alcoholic fermentation. Ashdown has re- 
corded a case in which it appeared in the urine without any drugs being administered.] 
Aceton [C3HeO] or Aceton-yielding substance, probably aceto-acetic acid, is sometimes found 
in diabetic urine. It has a peculiar vinous odor, and it has been detected in the urine during 
fever. Gerhardt described a peculiar substance in diabetic urine, which gave a deep red color 
with perchloride of iron. This substance is probably ethyl-diacetic ether [C6H10O3], and he 
considered it to be the source of aceton; but it is more probably derived from aceto-acetic acid. 
[This substance has been confounded with aceton, but the iron test distinguishes them.] Tests 
for Aceton.—(i) Perchloride of iron = Burgundy-red color; but this is not reliable. (2) 
Lieben suggested an iodoform test. Dissolve 20 grains of KI in a fluid drachm of liq. potassas, 
and boil the fluid. Pour the suspected urine on the surface, when a ring of phosphates is 
deposited from the urine by the hot alkaline solution. If aceton be present after a time the 
deposit becomes yellow, and yellow granules of iodoform appear and sink to the bottom of the 
test-tube. The only other substance which may be met with in the urine giving this reaction is 
lactic acid. 
Milk-sugar is sometimes found in the urine of women who are nursing; when the secretion 
of milk is arrested, absorption taking place from the breasts {Kirsten, Spiegelberg). Laevulose 
is sometimes found in diabetic urine (§ 252). 
Dextrin has also been found in diabetic urine. Inosit, or muscle-sugar (§ 252) is some- 
times found in diabetes, in polyuria, and albuminuria. 
It is found in traces even in normal urine. Occa- 
sionally, after the piqure in animals ($ 175), inosit, 
instead of grape-sugar, appears in the urine (fig. 327). 
In testing for inosit, remove the grape-sugar by fer- 
mentation, and the albumin by heat after the addi- 
tion of a few drops of acetic acid and sodic sulphate. 
Some of the filtrate is evaporated nearly to dryness 
on a capsule. To the residue add two drops of mer- 
curic nitrate (Liebig’s titration fluid for urea), which 
gives a yellow precipitate. When this colored 
residue is spread out and carefully heated, a dark 
red color, which disappears on cooling is obtained 
(Gallois, Kiilz). [Inosit gives a green when boiled 
with Fehling’s solution.] 
[Diazo-reaction or Ehrlich’s reaction.—This 
reaction is never given by normal urine, but it is 
given by the urine in typhoid fever (Rutimeyer), 
acute tuberculosis, etc. Its exact clinical signifi- 
cance is unknown. Two solutions are required—(1) 
a concentrated solution of sulphanilic acid, and (2) 
a solution of sodium nitrate (1 in 200). 200 c.c. of 
(1) are mixed with 10 c.c. of pure HC1 and 6 c.c. 
of (2). Mix equal quantities of this mixture and 
urine rendered strongly alkaline with ammonia; a bright carmine-red constitutes the reaction. 
After standing 24-36 hours a deposit, green or black, on its upper surface occurs.] 
268. CYSTIN = C6H12N2S,04.—This left-rotatory body occurs very sel- 
dom in large amount in urine, although it seems to be a constituent of normal 
urine. It may be in solution or in the form of hexagonal crystals (fig. 328, A) 
[the latter only in acid urine]. It is insoluble in water, alcohol, and ether, 
but easily soluble in ammonia, from which solution it may be crystallized. Ac- 
cording to Baumann and Preusse, there are intermediate products of the meta- 
bolism, from which are furnished the materials necessary for the formation of 
cystin. During normal metabolism these materials undergo further changes, 
and the sulphur appears oxidized in the urine as sulphuric acid. In rare cases 
these oxidations do not take place, and then the sulphur appears in the cystin 
of the urine (Stadthagen). ’Cystin is increased in phosphorus-poisoning 
{Baumann). 
269. LEUCIN = CfiH13N02. TYROSIN = C9H„N03.—Both bodies 
occur in the urine in acute yellow atrophy of the liver, and in poisoning 
by phosphorus. (Their formation during pancreatic digestion has been 
referred to in § 170, II.) As the urea excreted is usually diminished at the 
Inosit crystallized partly from alcohol and 
partly from water. 
Fig. 327. Sec. 269.] 
DEPOSITS IN URINE. 
531 
same time, it is assumed that, in these diseases, the further oxidation of the 
derivatives of the proteids is interfered with. Leucin, which is either precipi- 
tated spontaneously or obtained after evaporating an alcoholic extract of the 
concentrated urine, occurs in the form of yellowish-brown balls (fig. 329, 
a, a), often with concentric markings, or with fine spines on their surface. 
When heated it sublimes without fusing. 
Tyrosin forms silky colorless sheaves of needles (fig. 329, b, b). 
When boiled with mercuric nitrate and nitric acid it gives a red color, and after- 
wards a brownish-red precipitate. Piria’s Test.—When slightly heated with 
a few drops of concentrated sulphuric acid, it dissolves with a temporary deep 
red color. On diluting with water, adding barium carbonate until it is neutral- 
ized, boiling, filtering, and adding dilute ferric chloride, a violet color is ob- 
tained {Piria St adder). 
Fig. 328. 
Fig. 329. 
A, crystals of cystin ; B, oxalate of lime; 
c, hour-glass forms of B. 
a, a, leucin balls; b, b, tyrosin sheaves; 
c, double balls of ammonium urate. 
270. DEPOSITS IN URINE.—Deposits may occur in normal and in 
pathological urine, and they may be either “organized” or “unorgan- 
ized.” 
I. Organized Deposits. 
A. Blood : red and white blood-corpuscles and sometimes fibrin (figs. 320-322). 
B. Pus, in greater or less amount in catarrh or inflammation of the urinary passages. Pus 
cells exactly resemble colorless blood corpuscles (figs. 14, 323). Donne’s Test.—Pour off the 
supernatant fluid and add a piece of caustic potash to the deposit; if it be pus it becomes 
gelatinous, ropy, and more viscid (alkali-albuminate). Mucus, when so acted on, becomes 
more fluid and mixed with flocculi. 
C. Epithelium of various forms occurs, but it is not always possible to say whence it is 
derived. 
D. Spermatozoa may be present. 
E. Lower organisms occur in the urinary passages very seldom, but they may be present, 
e.g., in the bladder, when germs are introduced from without by means of a dirty catheter. 
[Before introducing a catheter into the bladder one ought always to make sure that the instru- 
ment is perfectly aseptic.] Micrococci are found in the urine in certain diseases, e.g., diphtheria. 
The following forms are distinguished:— 
1. Schizomycetes (| 184). Normal human urine contains neither schizomycetes nor their 
spores. In pathological conditions, however, fungi may pass from the blood into the urinary 
tubules and thus reach the urine (Leube). During the alkaline fermentation of urine, micro- 532 
DEPOSITS IN URINE. 
[Sec. 270. 
cocci, rod-shaped bacteria or bacilli (fig. 330) appear. Sarcinae belong to the group 
(S 186). 
2. Saccharomycetes (fermentation fungi): (a) The fungus of the acid urine fermentation (S. 
urinse) consists of small bladder-like cells arranged 
either in chains or in groups (figs. 316, a; 330, 
/). (t>) Yeast (S. fermentum) occurs in diabetic 
urine, as oval cells with a dotted eccentrically- 
placed nucleus (fig. 292). 
3. Phytomycetes (moulds) occur in putrid 
urine (fig. 330, <?). They are without clinical sig- 
nificance. 
F. Tube casts.—The occurrence of tube casts, 
i.e., casts of the uriniferous tubules (Henle, 1837), 
is of great importance in the diagnosis of renal 
diseases. If these structures are relatively thick 
and straight, they probably come from the collect- 
ing tubules, but if they are smaller and twisted, 
they probably come from the convoluted tubules. 
There are various forms of tube casts: 1. Epithelial casts, consisting of the actual cells of 
the uriniferous tubules. They indicate that there is no very great change going on, but only 
that, as in catarrhal inflammation of any mucous membrane, the epithelium is in process of des- 
quamation. 2. Hyaline casts (fig. 337) are quite clear and homogeneous, usually long and 
small; sometimes they are “ finely granular,” from the presence of fat or other particles. They 
are best seen after the addition of a solution of iodine. They are probably formed from albumin, 
which passes into the uriniferous tubules. They are dissolved in alkaline urine, 
while acid urine favors their formation. They usually occur in the late stages of 
renal disease, after the tubular epithelium has been shed. 3. Coarsely granu- 
lar casts (fig. 336) are brownish-yellow, opaque, and granular, usually broader than 
2. There are various forms. Not unfrequently there are fatty gran- 
ules, and, it may be, epithelial cells in them. 4. Amyloid casts 
occur in amyloid degeneration of the kidneys (fig. 337). They are 
Fungi in urine, e, mould; /, yeast; d, g, 
|s micrococci and bacilli; a, b, c, uric acid. 
Fig. 330- 
Fig. 331- 
Fig- 332. 
Fig- 333- 
Fig. 334- 
Fig. 335- 
Fig. 331.—Epithelial casts. Fig. 332.—Blood cast. Fig. 333.—Leucocyte cast. Fig. 334.— 
Acid sodic urate in cylinders. Fig. 335.—Finely granular cast. 
refractive and completely homogeneous, and give a blue color (amyloid reaction) with sulphuric 
acid and iodine. 5. Blood casts occur in capillary hemorrhage of the kidney, and consist of 
coagulated blood entangling blood-corpuscles (fig. 332). When tube casts are present, the urine 
is always albuminous. 
Leucocyte casts occur in suppurating conditions of the urinary tubules (fig. 337). The urates 
in the form of casts (fig. 334) are without significance. 
II. Unorganized Deposits. 
Some of these are crystalline and others are amorphous, and they have been referred to in 
treating of the urinary constituents. 
271. SCHEME FOR DETECTING URINARY DEPOSITS.— 
I. In acid urine there may occur— 
1. An amorphous granular deposit: 
(a) Which is dissolved by heat and reappears in the cold; the deposit is often reddish in 
colour = urates (fig. 316). Sec. 271.] 
EXAMINATION OF URINARY DEPOSITS. 
533 
(b) Which is not dissolved by heat but is dissolved by acetic acid, but without efferves- 
cence = probably tribasic calcic phosphate. 
(r) Small, bright refractive granules, soluble in ether = fat or oil granules ($ 41), (Lipaemia). 
Fat occurs in the urine, especially when the round worm, Filaria sanguinis hominis, 
is present in the blood; sometimes, along with sugar, in phthisis, poisoning with 
phosphorus, yellow fever, pyaemia, after long-continued suppuration, and lastly, after 
the injection of fat or milk into the blood (g 102). It occurs also in fatty degenera- 
tion of the urinary apparatus, admixture with pus from old abscesses, and after severe 
injuries to bones. In these cases attention ought to be directed to the presence of 
cholesterin and lecithin. Very rarely is the fat present in such amount in the urine 
as to form a cream on the surface (chyluria). 
Fig. 336.—Coarsely granular casts. Fig. 337.—Hyaline casts, a; b, with leucocytes; c, with 
renal epithelium. Fig. 338.—a, Granules of calcic carbonate of lime; b, c, crystalline neutral 
calcic phosphate. Fig. 339.—Ammonio-magnesic phosphate or triple phosphate. Fig. 
340.—Imperfect and feathery forms of the same. 
Fig- 337- 
F'g- 339- 
Fig. 340. 
2. A crystalline deposit may be— 
(a) Uric acid (fig. 312). 
(b) Calcium oxalate (fig. 314)—octahedra insoluble in acetic acid. 
\c) Cystin (fig. 328). 
(d) Leucin and tyrosin—very rare (fig. 329). 
II. In alkaline urine there may occur— 
1. A completely amorphous granular deposit, soluble in acids without effervescence — 
tribasic calcium phosphate. 
2. Sediment crystalline, or with a characteristic form. 
(ia) Triple phosphate (figs. 339, 340), soluble at once in acids. 
(b) Acid ammonium urate—dark yellowish small balls, often beset with spines, also 
amorphous (fig. 341). 
(r) Calcium carbonate—small whitish balls or biscuit-shaped bodies. Acids dissolve 
them with effervescence (fig. 338). [Sec. 271. 
534 
URINARY CALCULI. 
(d) Leucin and tyrosin (fig. 329)—very rare. 
(f) Neutral calcic phosphate and long plates of tribasic magnesic phosphate (fig. 342). 
Organized deposits may occur both in alkaline and in acid urine; pus-cells are more 
abundant in alkaline urine, and so are the lower vegetable organisms. 
272. URINARY CALCULI.—Urinary concretions may occur in gran- 
ules the size of sand, or in masses as large as the fist. According to their size 
they are spoken of as sand, gravel, stone or calculi. They occur in the 
pelvis of the kidney, ureters, bladder, and sinus prostaticus. 
We may classify them as follows (Ultzmann) :— 
1. Calculi, whose nucleus consists of the sedimentary deposits that occur in acid urine 
(primary formation of calculi). They are all formed in the kidney, and pass into the bladder, 
where they enlarge by the deposition of matter on their surface. 
2. Calculi, which are either sedimentary forms from alkaline urine, or whose nucleus con- 
sists of a foreign body (secondary formation of calculi). They are formed in the bladder. 
The primary formation of calculi begins with free uric acid in the 
form of sheaves (fig. 312), which form a nucleus, with concentric layers 
of oxalate of lime. The secondary formation occurs in neutral urine 
by the deposition of calcic carbonate and crystalline calcic phosphate; 
in alkaline urine, by the deposition of acid ammonium urate, triple 
phosphate, and amorphous calcic phosphate. 
Chemical Investigation.—Scrape the calculus, burn the scrapings 
on platinum foil to ascertain if they are burned or not. 
I. Combustible concretions can consist only of organic substances. 
(a) Apply the murexide test ($ 259, 2), and, if it succeeds, uric acid 
is present. Uric acid calculi are very common, often of considerable 
size, smooth, fairly hard, and yellow to reddish-brown in color. 
(b) If another portion, on being boiled with caustic potash, gives 
the odor of ammonia (or when the vapor makes damp turmeric paper 
brown, or if a glass rod dipped in HC1 and held over it gives white 
fumes of ammonium chloride), the concretion contains ammonium 
urate. If b gives no result, pure uric acid is present. Calculi of 
ammonium urate are rare, usually small, of an earthy consistence, i. e., 
soft and pale yellow or whitish in color. 
(c) If the xanthin reaction succeeds (§ 260), this substance is present (rare). Indigo has 
been found on one occasion in a calculus (Ord). 
(d) If, after solution in ammonia, hexagonal plates (fig. 328, A) are found, cystin is present. 
(e) Concretions of coagulated blood or fibrin, without any crystals, are rare. When burned 
they give the odor of singed hair. They are insoluble in 
water, alcohol, and ether; but are soluble in caustic potash, 
and are precipitated therefrom by acids. 
(f) Urostealith is applied to a caoutchouc-like soft elastic 
substance, and is very rare. When dry it is brittle and hard, 
brown or black. When warm it softens, and if more heat be 
applied it melts. It is soluble in ether, and the residue after 
evaporation becomes violet on being heated. It is soluble in 
warm caustic potash, with the formation of a soap. 
II. If the concretions are only partly combustible, thus 
leaving a residue, they contain organic and inorganic con- 
stituents. 
(«) Pulverize a part of the stone, boil it in water, and filter while hot. The urates are dis- 
solved. To test if the uric acid is united with soda, potash, lime, or magnesia, the filtrate is 
evaporated and burned. The ash is investigated with the spectroscope (§ 14), when the char- 
acteristic bands of sodium or potash are observed. Magnesic urate and calcic urate are changed 
into carbonate by burning. To separate them, dissolve the ash in dilute hydrochloric acid, and 
filter. The filtrate is neutralized with ammonia, and again redissolved by a few drops of acetic 
acid. The addition of ammonium oxalate precipitates calcic oxalate. Filter, and add to the 
filtrate sodic phosphate and ammonia, when the magnesia is precipitated as ammonio-magnesic 
phosphate. 
(£) Calcic oxalate (especially in children, either as small smooth pale stones, or in dark, 
warty, hard “ mulberry calculi”) is not affected by acetic acid, is dissolved by mineral acids 
without effervescence, and again precipitated by ammonia. Heated on platinum foils it chars 
and blackens, then it becomes white, owing to the formation of calcic carbonate, which effer- 
vesces on the addition of an acid. 
Fig- 341- 
Acid ammonium urate. 
Fig. 342. 
Basic magnesic phosphate. Sec. 272.] 
THE FUNCTIONS OF THE KIDNEY. 
535 
(c) Calcic carbonate (chiefly in whitish-gray, earthy, chalk-like calculi, somewhat rare, 
dissolves with effervescence in hydrochloric acid. When burned it first becomes black, owing 
to admixture with mucus, and then white. 
(4) Ammonio-magnesic phosphate and basic calcic phosphate usually occur together 
in soft, white, earthy stones, which occasionally are very large. These stones show that the urine 
has been ammoniacal for a very long time. The first substance when heated gives the odor of 
ammonia, which is more distinct when heated with caustic potash; is soluble in acetic. acid 
without effervescence, and is again precipitated in a crystalline form from this solution on the 
addition of ammonia. When heated it fuses into a white enamel-like mass; [hence, it is called 
“ fusible calculus ”]. Basic calcic phosphate does not effervesce with acids. The solution 
in hydrochloric acid is precipitated by ammonia. When ammonium oxalate is added to the acetic 
acid solution, it yields calcic oxalate. 
(<?) Neutral calcic phosphate is rare in calculi, while it is frequent in the form of gravel. 
Physically and chemically, these concretions resemble the earthy phosphates, only they do not 
contain magnesia. 
273. THE SECRETION OF URINE—[The functions of the 
kidney are— 
1. To excrete waste products, chiefly nitrogenous bodies and salts; 
2. To excrete water; 
3. And perhaps also to reabsorb water from the uriniferous tubules, after 
it has washed out the waste products from the renal epithelium. 
The chief parts of the organs concerned in 1, are the epithelial cells of the 
convoluted tubules; the glomeruli permit water and some solids to pass through 
them, while the constrictions of the tubules may prevent the too rapid outflow 
of water, and thus enable part of it to be reabsorbed.] 
Theories.—The two chief older theories regarding the secretion of urine 
are the following: 1. According to Bowman (1842), through the glomeruli 
are filtered only the water and some of the highly diffusible and soluble salts 
present in the blood, while the specific urinary constituents are secreted by the 
activity of the epithelium of the urinary tubules, and are extracted or removed 
from the epithelium by the water flowing along the tubules. This has been 
called the “vital” theory. 2. C. Ludwig (1844) assumes that very dilute 
urine is secreted or filtered through the glomerulus. As it passes along the 
•urinary tubules it becomes more concentrated, owing to endosmosis. It gives 
back some of its water to the blood and lymph of the kidney, thus becoming 
more concentrated, and assuming its normal character. [This is commonly 
known as the “ mechanical theory.”] 
The secretion of urine in the kidneys does not solely depend upon definite 
physical forces. A great number of facts force us to conclude that the vital 
activity of certain secretory cells plays a foremost part in the process of secre- 
tion (R. Heidenhain). 
The secretion of urine embraces—(1) The water, and (2) the urinary 
constituents therein dissolved; both together form the urinary secretion. 
The amount of urine depends chiefly upon the amount of water which is 
filtered through or secreted by the glomeruli; the amount of solids dissolved 
in the urine determines its concentration. 
(A) The amount of urine, which is secreted chiefly within the Malpighian 
capsules, depends primarily upon the blood-pressure in the area of the renal artery, 
and follows, therefore, the laws of filtration (§ 191, II) (.Ludwig and Goll). 
[In this respect the secretion of urine differs markedly from that of saliva, 
gastric juice, or bile. We may state it more accurately thus, that the amount 
of urine depends very closely upon the differences of pressure between the blood 
in the glomeruli and the pressure within the renal tubules. If the ureter be 
ligatured, the secretion of urine is ultimately arrested, even although the blood- 536 
[Sec. 273. 
THE SECRETION OF URINE. 
pressure be high. The secretion may also be arrested by ligature of the renal 
vein ; and in some cases of cardiac pulmonary disease the venous congestion 
thereby produced may bring about the same result.] 
Glomerular Epithelium.—The amount of urine secreted does not depend 
upon the hydrostatic pressure alone, but it seems that the epithelial cells cover- 
ing the glomerulus also participate actively in the process of secretion. Besides 
the water, a certain amount of the salts present in the urine are excreted through 
the glomeruli. The serum-albumin of the blood, however, is prevented fro?n 
passing through. With regard to the secretory activity of these cells, the quan- 
tity of water must also depend upon the amount of the urinary constituents and 
water present in the blood (PI. Heidenhain). 
Only when the vitality of the secretory cells is intact is there independent activity of these 
secretory cells (Heidenhain). When the renal artery is closed temporarily, their activity is par- 
alyzed, so that the kidneys ceasd to secrete, and even after the compression is removed and the 
circulation is re-established, secretion does not take place for some time (Overbeck). 
That the secretion depends in part upon the blood-pressure is proved 
by the following considerations :— 
1. Increase of the total contents of the vascular system so as to increase the 
blood-pressure, increases the amount of water which filters through the glome- 
ruli. The injection of water into the blood-vessels, or drinking copious 
draughts of water, acts partly in this way. If the blood-pressure rises above a 
certain height, albumin may pass into the urine. The active participation 
of the cells of the glomeruli is rendered probable by the fact that, after 
very copious drinking, the blood-pressure is not always raised (Pawlow') ; 
further, after copious transfusion, the quantity of urine is not increased. Con- 
versely, the loss of water owing to profuse sweating or diarrhoea, copious hem- 
orrhage, or prolonged thirst, diminishes the secretion of urine. 
2. Diminution of the capacity of the vascular system, provided the pressure 
within the renal area be thereby increased, acts in a similar manner. This may 
be produced by contraction of the cutaneous vessels, owing to the action of 
cold, stimulation of the vaso-motor centre, or large vaso-motor nerves, ligature,_ 
or compression of large arteries (§ 85, e), or enveloping the extremities in tight 
bandages. All these conditions cause an increase in the amount of urine, and 
of course the opposite conditions bring about a diminution of urine, e.g., the 
action of heat on the skin causing redness and dilatation of the cutaneous ves- 
sels, weakening of the vaso-motor centre, or paralysis of a large number of vaso- 
motor nerves. 
3. Increased action of the heart, whereby the tension and rapidity of the blood 
in the arteries are increased (§ 85, c), augments the amount of urine ; conversely, 
feeble action of the heart (paralysis of motor cardiac nerves, disease of the car- 
diac musculature, certain valvular lesions) diminishes the amount. Artificial 
stimulation of the vagi in animals, so as to slow the action of the heart, and 
thus diminish the mean blood-pressure from 130 to 100 mm. Hg, causes a dimi- 
nution in the amount of urine to the extent of one-fifth (Goll, Cl. Bernard') \ 
when the pressure in the aorta falls to 40 mm. the secretion of urine ceases. [If 
the medulla oblongata be divided (dog), there is an immediate fall of the gen- 
eral blood-pressure, and although, as a general rule, the secretion of urine is 
arrested when the pressure falls to 40 to 50 mm. Hg, yet secretion has been 
observed to take place with a lower pressure than this.] 
4. The amount of urine secreted rises or falls according to the degree of ful- 
ness of the renal artery (Ludwig, Max Hermann); even when this artery is Sec. 273.] 
THE SECRETION OF URINE. 
537 
moderately constricted in animals, there is a decided diminution in the amount 
of urine. 
Pathological.—In fever the renal vessels are less full and there is consecutive diminution of 
urine (Mendelsohn). It is most important, in connection with certain renal diseases, to note 
that ligature of the renal artery, even when it is obliterated for only two hours, causes necrosis 
of the epithelium of the uriniferous tubules. When the arterial ansemia is kept up for a long 
time, the whole renal tissue dies (Lilten). After long-continued ligation of the renal artery, 
the epithelium of the glomeruli becomes greatly changed (Kibbert). 
•5. Most diuretics act in one or other of the above-mentioned ways. 
[Some diuretics act by increasing th& general blood-pressure (digitalis and the action of cold 
on the skin), others may increase the blood-pressure locally within the kidney, and this they may 
do in several ways. The nitrites are said to paralyze the muscular fibres in the vasa afferentia, 
and thus raise the blood-pressure within the glomeruli. But some also act on the secretory epi- 
thelium, such as urea and caffein. Brunton recommends the combination of diuretics in appro- 
priate cases, and the diuretics must be chosen according to the end in view—as we wish to re- 
move excess of fluids from the tissues and serous cavities, or as we wish to remove injurious waste 
products, or merely to dilute the urine.] 
[6. The amount of urine also depends upon the composition of the blood. 
Drinking a large quantity of water, whereby the blood becomes more watery, in- 
creases the amount of urine, but this is true only within certain limits. It is 
not merely the increase of volume of the blood acting mechanically which causes 
this increase, as we know that large quantities of fluid may be transfused with- 
out the general blood-pressure being materially raised thereby.] 
[Heidenhain argues that it is not so much the pressure in the glomeruli as 
the velocity of the blood, which determines the process of the secretion of 
water in the kidney. He contends that, while increase of the pressure in the 
renal artery causes an increased flow of urine, ligature of the renal vein, 
whereby the pressure in the glomeruli is also increased, arrests the secretion 
altogether. In both cases the pressure is increased within the glomeruli, and 
the two cases differ essentially in the velocity of the blood-current through 
the glomeruli.] 
Pressure in the Vas Afferens.—The pressure in each vas afferens must 
be relatively great, because (1) the double set of capillaries in the kidney offers 
considerable resistance, and (2) the lumen of the vas efferens is narrower than 
that of the vas afferens. Hence, owing to the high blood-pressure in the capil- 
laries of the renal glomeruli, filtration must take place from the blood into the 
Malpighian capsules. When the vasa afferentia are dilated, the filtration-pres- 
sure is increased, while, when they are contracted, the secretion is lessened. 
When the pressure becomes so diminished as to retard greatly the blood-stream 
in the renal vein, the secretion of urine begins to be arrested. Occlusion of 
the renal vein completely suppresses the secretion (.H'. Meyer, v. Frerichs). 
Ludwig concluded from this observation that the filtration or excretion of fluid 
could not take place through the renal capillaries proper, as, owing to occlusion 
of the renal vein, the blood-pressure in these capillaries must rise, which ought 
to lead to increased filtration. Such an experiment points to the conclusion 
that the filtration must take place through the capillaries of the glomeruli. The 
venous stasis distends the vas efferens, which springs from the centre of the 
glomerulus, and compresses the capillary loops against the wall of the Mal- 
pighian capsule, so that filtration cannot take place through them. It is 
not decided whether any fluid is given off through the convoluted urinary 
tubules. 
Venous congestion in the kidneys diminishes the quantity of urine and the urea. The NaCl 
remains constant, but pathological albumin is increased (Senator and Alunk). 538 
[Sec. 273. 
EXPERIMENTS WITH SULPHINDIGOTATE OF SODA. 
Pressure in Ureter.—As the blood-pressure in the renal artery is about 
120 to 140 mm. Hg, and the urine in the ureter is moved along by a very slight 
propelling force, so that a counter-pressure of from 10 (.Lobell) to 40 mm. of 
Hg is sufficient to arrest its flow, it is clear that the blood-pressure can also act 
as a vis a tergo to propel the urine through the ureter. The pressure in the 
ureter is measured by dividing the ureter transversely and inserting the mano- 
meter in it. 
(B) Secretory Activity of the Renal Epithelium.—The degree of 
concentration of the urine also depends upon the quantity of the dissolved 
constituents which has passed from the blood into the urine. The secretory 
cells of the convoluted tubules, by their own proper vital activity, seem to be 
able to take up, or secrete, some at least of these substances from the blood 
(.Bowman, Heidenhain). The watery part of the urine, containing only easily 
diffusible salts, as it flows along the tubules from the glomeruli, extracts or 
washes out these substances from the secretory epithelium of the convoluted 
tubules. 
Experiments with sulphindigotate of soda.—1. Sulphindigotate of 
soda and sodium urate, when injected into the blood, pass into the urine, and 
Fig. 343- 
Fig. 344- 
Fig. 345- 
Fig. 343.—Section of a rabbit’s kidney after the injection of a large quantity of sulphindigotate 
of soda into the blood. Fig. 344.—Section of a rabbit’s kidney. Section of the spinal 
cord and subsequent injection of sulphindigotate of soda. Note that the pigment is con- 
fined to the cortex. Fig. 345.—Section of a rabbit’s kidney. The surface between c 
and h and d was cauterized. There is the normal appearance in the areas fc,gh, db, but 
arrest of the secretion of water in eg and hd. 
are found within the protoplasma of the cells of the convoluted tubules [only in 
those parts lined by “ rodded ” epithelium], but not in the Malpighian cap- 
sules (Heidenhain). A little later these substances are found in the lumen of 
the urinary tubules, from which they are washed out by the watery part of the 
urine coming from the glomeruli. If, however, two days before the injection 
of these substances into the blood, the cortical part of the kidney containing 
the Malpighian capsules be cauterized [e. g., by nitrate of silver], or sliced off, 
the blue pigment remains within the convoluted tubules. It cannot be carried 
onward, as the water which should carry it along has ceased to be secreted, 
owing to the destruction of the glomeruli. This experiment also goes to show 
that through the glomeruli the watery part of the urine is chiefly excreted, while 
through the convoluted tubules the specific urinary constituents are excreted. 
[When a large quantity of the pure sulphindigotate is injected into the blood, 
within less than half an hour the cortex and pyramids become deep blue; the 
boundary zone, as a rule, is lighter in tint (fig. 343). The blue pigment is found 
in the epithelium of the convoluted tubules, or in their lumen, but never in the 
epithelium of the straight tubules, although a large amount is found in the 
lumina, especially of the collecting-tubes.] 
[If, however, the spinal cord be divided so as to lower the arterial blood- Sec. 273.] 
nussbaum’s experiments. 
539 
pressure, and thus arrest the secretion of water, and a small quantity of the 
sulphindigotate be injected into the blood, the 
blue pigment is secreted from the lymph, itself 
nearly colorless, by the convoluted tubules and 
the looped tubules of Henle. Owing to the 
arrest of the watery part of the secretion, the 
pigment remains in the cortex and the kidney 
presents the appearance shown in fig. 344.] 
[Fig. 345 shows the effect of cauterizing the 
surface of the kidney with silver nitrate. In 
the cauterized area the secretion of water within 
the capsules ceases, while the secretion of the 
pigment by the convoluted tubules is not ar- 
rested, so that in the normal areas one has the 
appearances shown in fig. 343 and in the cau- 
terized area that of fig. 345]. 
Uric acid salts, injected into the blood, 
were observed by Heidenhain to be excreted 
by the convoluted tubules. Von Wittich had 
previously observed that in birds, crystals of 
uric acid were excreted by the epithelium of 
the convoluted tubules. [The presence of crys- 
tals of uric acid in the renal epithelium was 
observed by Bowman, and used as an argument 
to support his theory.] Nussbaum, in 1878, 
stated that urea is secreted by the urinary 
tubules and not by the glomeruli. 
The same is true for the bile-pigments, for the iron salts 
of the vegetable acids when injected subcutaneously, and 
for haemoglobin. After injection of milk into the blood- 
vessels, numerous fatty granules occur within the epithe- 
lium of the urinary tubules (§ 102). 
Excretion of Pigments.—Only during very copi- 
ous excretion does the glomeruli participate. After 
the introduction of a large amount of sodic sulphindigo- 
tate, and when the experiment has lasted for a long time, 
the epithelium of the glomerulus becomes blue. In 
albuminuria, the abnormal excretion of urine takes 
place first in the urinary tubules, and afterwards in the 
Malpighian capsules; Hb is partly found in the capsules. 
According to Nussbaum, egg-albumin passes out through 
the Malpighian capsules. 
[Nussbaum’s Experiments.—In the frog 
and newt, the kidney is supplied with blood 
in a manner different from that obtaining in 
mammals. The glomeruli are supplied by 
branches of the renal artery. The tubules are 
supplied by the renal-portal vein (fig. 346). The vein coming from the poste- 
rior extremities divides at the upper end of the thigh into two branches, one of 
which enters the kidney, and breaks up to form a capillary plexus, which sur- 
rounds the uriniferous tubules, but this plexus is also joined by the efferent 
vessels of the glomeruli. These two systems are partly independent of each 
other. After ligaturing the renal arteries, Nussbaum asserted that the circula- 
tion in the glomeruli was cut off, while ligature of the renal-portal vein excluded 
the functional activity of the tubules. By injecting a substance into the blood, 
after ligaturing either the arteries or renal-portal vein, and observing whether 
Veins of the frog, semi-diagrammatic. 
S. V., sinus venosus; HA, LA, right, 
left auricles; V, ventricle; pr-c, pre- 
caval; ex ju., external jugular; i. 
ju., internal jugular ; s-sc., subscap- 
ular; in, innominate ; s-cl, subcla- 
vian ; br, brachial; m-ct, musculo- 
cutaneous ; pc, post-caval; sc, sci- 
atic; p.v., pelvic; rp, renal-portal; 
d.-L, dorso-lumbar; o, veins from 
oviduct; r.v, renal; a, ab, anterior 
abdominal; bl, vesical; p, portal, 
and h, hepatic veins; k, kidneys; 
i, alimentary canal with its capil- 
laries ; /, capillaries of liver; pi, 
pulmonary veins. 
Fig. 346. [Sec. 273. 
540 
LIGATURE OF THE URETER. 
it occurs, in the urine, he infers that it is given off either by the glomeruli or 
the tubules. Sugar, peptones, and egg-albumin rapidly pass through an intact 
kidney, but if the renal arteries be tied they are not excreted. Urea when 
injected into the circulation is excreted after the arteries are tied, so that it is 
excreted through the tubules, but at the same time it takes with it a consider- 
able quantity of water. Thus, water is excreted in two ways from the kidney, 
by the glomeruli and also from the venous plexus around the tubules along with 
the urea. Indigo-carmine merely passes into the tubular epithelium of the 
convoluted tubules, but it does not cause a secretion of urine. Albumin passes 
through the glomeruli, but only after their membranes have been altered in 
some way, as by clamping the renal artery for a time.] 
[Adami’s Experiments on the kidney of the frog tend to show that Nussbaum’s conclusions 
are not justified, for Adami found that if the renal arteries in the frog be ligatured, within a 
few hours a collateral circulation is established and a certain amount of blood flows through 
the kidney. He proved this by injecting into the blood carmine or painter’s vermillion, in a 
state of fine suspension, and after ligature of the renal arteries he found it in many of the 
glomeruli, while laky blood similarly injected revealed its presence as menisci of II b in the 
Malpighian corpuscles. Even secretion of some urine may go on after ligature of the renal 
arteries. It is evident, then, that Nussbaum’s method is not a reliable one for locating the parts 
of the kidney through which certain substances are excreted. Adami’s experiments also give 
some support to Heidenhain’s view that the glomerular epithelium “ possesses powers of a selec- 
tive secretory nature,” for he finds that in frogs, after ligature of the renal arteries, where, of 
course, the pressure in the glomeruli is just nearly that in the veins, and in the dog after section 
of the spinal cord, so that the blood-pressure has fallen below 40 mm. Hg, whereby the secretion 
of urine is arrested, the injection of laky blood causes Hb to appear in the capsules, although 
there is no simultaneous excretion of water.] 
2. Even when the secretion of the watery part of the urine is completely 
arrested, either by ligature of the ureter, or after a very great fall of the blood - 
pressure in the renal artery [as after section of the cervical spinal cord], the 
before-mentioned substances, when injected into the blood, are found in the 
cells of the convoluted tubules. The injection of urea under these circum- 
stances causes renewed secretion. These facts show that, independently of the 
filtration-pressure, the secretory activity of these cells is still maintained. 
The independent vital activity of the secretory cells of the urinary tubules, which as yet 
we are unable to explain on purely physical grounds, renders it probable that the tubules are not 
to be compared to an apparatus provided with physical membranes. This is proved by the 
following experiment: Abeles caused arterial blood to circulate through freshly excised living 
kidneys. A pale urine-like fluid dropped from the ureter. On adding some urea or sugar to the 
blood, the secretion became more concentrated. Thus, the excised “surviving ” kidney also 
excretes substances in a more concentrated form than those supplied to it in the diluted blood 
streaming through it. J. Munk obtained similar results in excised kidneys, with common salt, 
nitre, caffein, grape sugar, glycerin, with increase in the amount of urine secreted. The addition 
of caffein or theobromin to the perfused blood increases the secretion, exciting the secretory cells 
to greater activity (v. Schroeder). 
Salts and Gases.—The vital activity explains why the serum albumin of the blood does not 
pass into the urine, while egg-albumin and dissolved haemoglobin readily do so. Among the salts 
which occur in the blood and blood-corpuscles, of course only those in solution can pass into the 
urine. Those which are united with proteid bodies, or are fixed in the cellular elements, cannot 
pass out, or at least only after they have been split up. Thus, we may explain the difference 
between the salts of the urine and those of the blood. Similarly, the urine can only contain the 
absorbed and not the chemically-united gases. 
Ligature of the Ureter.—If the secretion be arrested by compression or by ligature of the 
ureter, the lymph-spaces of the kidney become filled with fluid, which may pass into the blood, 
so that the organ becomes cedematous, owing to the passage of fluid into its lymph-spaces. The 
secretion undergoes a change, as first water passes back into the blood, then the sodic chloride, 
sulphuric, and phosphoric acids diminish, and lastly the urea (C. Ludzvig, Max Herrman). 
Kreatinin is still present in considerable amount. There is no longer secretion of proper urine 
obeli). 
Non-Symmetrical Renal Activity.—It is remarkable that both kidneys do not secrete 
symmetrically—there is an alternate condition of hypermmia and secretory activity on opposite Sec. 273.] 
FORMATION OF UREA. 
541 
sides (| ioo). One kidney secretes a more watery urine, which at the same time contains more 
NaCl and urea. Von Wittich observed that the secretion of uric acid was not uniform in all the 
urinary tubules of the same bird. Extirpation of one kidney, or disease of one kidney in man, 
does not seem to diminish the secretion (Rosenstein). The remaining kidney becomes more 
active, and larger. 
Reabsorption in the Kidney.—In discussing the secretion of the kidney, we must' attach 
considerable importance to the variations in the calibre of the renal tubules in their course. 
Perhaps in the narrowing of the descending part of the looped tubule of Henle there may be 
either a reabsorption of water, so that the urine becomes more concentrated, or there may be 
absorption even of albumin, which may perhaps pass through the glomeruli in small amount. 
[That reabsorption of fluid takes place within the kidney was part of Ludwig’s theory, which 
is practically a process of filtration and reabsorption. Hiifner pointed out that the structure of 
the kidneys of various classes of vertebrates corresponded closely with the requirements for 
reabsorption of water. The experiments of Ribbert show that the urine actually secreted in 
the cortex of the kidney is more watery than that secreted normally by the entire organ. He 
extirpated the medullary portion in rabbits, leaving the cortical part intact, and in this way 
collected the dilute urine from the Malpighian corpuscles before it passed through Henle’s 
loops.] 
274. FORMATION OF THE URINARY CONSTITUENTS.— 
The question has often been discussed, whether all the urinary constituents 
are merely excreted through the kidneys, i. e., that they exist preformed in the 
blood ; or whether some of them do not exist preformed in the blood, but are 
formed within the kidneys, as a result of the activity of the renal epithelium. 
Urea is formed outside the Kidney.—Urea exists preformed in the 
blood, from which it is separated by the activity of the kidney. This is 
proved by the following considerations: — 
1. The blood contains one part of urea in 3000 to 5000 parts, but the renal vein contains 
less urea than the blood of the corresponding artery. 
2. After extirpation of the kidneys, or nephrectomy, or after ligature of the renal vessels, 
the amount of urea accumulates in the blood, and increases with the duration of the experiment 
to to At the same time there is vomiting and diarrhoea, and the fluids so voided con- 
tain urea [Cl. Bernard). Animals die in from one to three days after the operation. 
3. After ligature of the ureters, the secretion of urine is soon arrested. Urea accumulates in 
the blood, but not to a greater extent than after nephrectomy. It is possible, however, that the 
kidneys, like other organs, may form a small amount of urea, due to the metabolism of their own 
tissues. 
[Although the percentage of urea in the blood is small, yet when we consider the enormous 
amount of blood circulating through the very vascular kidneys, we obtain data which prove that 
the kidneys withdraw the urea from the blood. A dog weighing 30 kilos. (66.6 lbs.) has 2.31 
kilos, of blood, i. e., Tkth part of its body-weight. The entire course of the circulation is com- 
pleted in 15 secs., so that in 24 hours 2.31 X 4 X 60 X 24 = 13305.6 kilos, of blood will pass 
through the body. Taking the kidneys as part of the weight of the body, about 66.53 
kilos, of the blood will pass through the kidneys in 24 hours. Suppose the blood contained 
only .5 gram urea in 1000 c.c., 66.53 kilos, could yield 33.3 grams of urea. A large dog fed on 
flesh excretes 30-35 grams of urea in 24 hours [Ahmk).^ 
[Urea exists in the blood; whence does the blood derive it? It can 
only obtain it from one or more of several organs—(1) muscle, (2) nervous 
system, and (3) glands, of which the liver is the most prominent. This is best 
stated by the method of exclusion.] 
[1. That urea is not formed in muscle is shown, among other considerations, 
by the fact that only a trace of urea occurs in muscle (§ 293), and that the 
amount is not increased by exercise. Blood which has been transfused through 
a must le, or the blood after circulating in a muscle during violent- exercise, 
does not contain an increase of urea, nor does the addition of ammonium car- 
bonate to blood circulating through muscle show any increase of urea. Again, 
muscular exertion dors not (as a rule) increase the amount of urea in the 
urine, as shown by the experiments of Fick and Wislicenus (§ 294), Parkes, 
and oih-rs. The excretion chiefly increased by muscular exertion is the pulmo- 
nary CO* (§ 127).] 542 
FORMATION OF UREA. 
[Sec. 274. 
[ 2. From what we know of the nervous system, it is not formed there. We 
are therefore forced to consider the evidence as to the liver, as the organ, or, 
at least, the chief organ, in which it is formed. This evidence is in some 
respects contradictory, but it is partly experimental and partly clinical.] 
[Experimental Evidence.—Although Hoppe-Seyler denies the existence 
of urea in the liver, (i) its existence there was proved by Gscheidlen ; (2) and 
Cyon, on passing blood through an excised liver by the “ perfusion” method 
of Ludwig, found that blood, after being passed several times through the 
organ, contained an increased amount of urea. The objection to these 
experiments is that Cyon’s method of estimating the urea was unreliable. 
(3) But von Schroeder, using a similar method, finds that if the blood taken 
from a dog in full digestio?i be perfused through the liver, there is a slight in- 
crease in the amount of urea, while there is no urea formed when the blood of 
a fasting dog is similarly perfused. (4) If ammonium carbonate be added to 
the blood, there is a very much greater amount of urea in the blood of the 
hepatic vein. This last fact is confirmed by Salomon. But if blood mixed 
with ammonium carbonate be perfused through an excised surviving kidney, 
or through the muscles of the lower limbs, there is no increase of urea. 
These experiments seem to point to ammonium carbonate as being one of the 
antecedents of urea, which is further strengthened by the fact that the adminis- 
tration of ammonium salts increases the amount of urea in the urine. (5) The 
experiments of Minkowski on the liver of the goose (§ 386) show that, when the 
liver is excluded from the circulation, lactic acid takes the place of uric acid 
in this bird. (6) Brouardel further states, that if the region of the liver be so 
beaten as to cause congestion of that organ, there is an increase of the urea in 
the urine. (7) Noel-Paton finds that some drugs which increase the quantity of 
bile in dogs in a state of N-equilibrium (§ 178), e. g., sodic salicylate and ben- 
zoate, colchicum, mercuric chloride, and euonymin, also increase the urea in 
the urine ; he therefore concludes “ that the formation of urea in the liver bears 
a very direct relationship to the secretion of bile by that organ.” But the de- 
struction of red blood-corpuscles, e.g., by the injection of pyrogallic acid or 
toluylendiamin into the blood by setting free haemoglobin, not only causes an 
increase of bile, but it also increases the elimination of urea by the kidneys, 
and the time of maximum destruction of the red blood-corpuscles, as measured 
by the haemocytometer, coincides with the maximum excretion of urea.] 
[The clinical evidence points strongly to the formation of urea in the 
liver. Parkes pointed out that in hepatic abscess, during the early conges- 
tive stage, the urea in the urine is increased, while it is diminished in the sup- 
purative stage, when the hepatic parenchyma is destroyed. The urea is also 
diminished in cancer of the liver, phthisis, and some forms of hepatic cirrhosis, 
while it is increased during hepatic congestion, and specially so in some cases 
of diabetes mellitus. The most striking fact of all is that, in acute yellow 
atrophy of the liver, the urea is enormously diminished in the urine, and may 
even disappear from it while its place is taken by the intermediate products, 
leucin and tyrosin (v. Frerichs'). In poisoning by phosphorus, coincident with 
the atrophy of the liver, there is a fall in the urea-excretion. In diabetes 
mellitus depending on disease of the liver, not only is the sugar passed in the 
urine greatly increased, but the urea is also increased. In hepatic cirrhosis, 
where there is great diminution in the parenchyma of the liver, the urea in the 
urine is greatly diminished and the ammonia greatly increased.] 
As to the antecedents of urea there is the greatest doubt (§ 256). 
[These and the following experiments indicate that urea, and perhaps most 
of the organic urinary constituents, are “secreted” or separated by the kid- 
neys from the blood passing through them, and that they are not formed in Sec. 274.] 
FORMATION OF HIPPURIC ACID. 
543 
the kidneys themselves. The urea is derived from proteids, and the liver 
seems to be the organ in which it is formed.] 
Uric Acid is formed outside the Kidneys.—i. Bird’s blood normally 
contains uric acid (.Meissner). [The liver of the pigeon contains 6 to 14 times 
as much uric acid as the blood.] Ligature of the ureters or renal blood-vessels 
(.Pawlinoff), or gradual destruction of the renal secretory parenchyma by the 
subcutaneous injection of neutral potassium chromate (Ebstein), is followed by 
the deposition of uric acid in the joints and tissues, and it may even form a 
white incrustation on the serous membranes. The brain remains free (.Zalesky, 
Oppler). Acid urates of ammonia, soda, and magnesia are also similarly de- 
posited. Extirpation of a snake’s kidneys gives the same result, but to a less 
degree. 
[Minkowski found that, after excluding the liver from the circulation, lactic acid took the 
place of uric acid in the urine (p. 510). Some uric acid still appears in the urine, which cannot 
be derived from the small amount in the blood, so that, according to v. Schroeder, there are per- 
haps other foci of formation of uric acid.] 
[The latter experiment points to the formation of uric acid in the liver in 
birds, and this is supposed to be strengthened by the appearance of the deposi- 
tion of urates in the urine in certain disorders of digestion.] Von Schroeder 
and Colasanti, however, as the result of their experiments upon snakes, come 
to the conclusion that there is no special organ concerned in the formation of 
uric acid. 
Hippuric acid is partly formed in the kidney, for the blood of herbivora 
does not contain a trace of it (.Meissner and Shepard). In rabbits, however, it 
is formed synthetically in other tissues as well as in the kidney. If blood con- 
taining sodic benzoate and glycin be passed through the blood-vessels of a fresh 
kidney, hippuric acid is formed (§ 260) (Bunge, Schmiedeberg, Kochs). [The 
other evidence is given in § 260.] 
Kreatinin has intimate relations to kreatin of muscle, but where it is formed is not known. 
If phenol and pyrokatechin are digested along with fresh renal substance, a compound of 
sulphuric acid similar to that occurring in urine is formed (§ 262). The latter substance, how- 
ever, is also formed by similarly digesting liver, pancreas, and muscle. It is concluded from 
these experiments that these substances are formed in the body within the kidneys and the other 
organs mentioned (Kochs). 
[Urobilin, nearly related to bilirubin, is ultimately formed from haemoglobin (£ 261), per- 
haps in the liver, and is re-absorbed from the intestinal canal to be excreted in the urine. The 
other urinary pigments all arise directly or indirectly from haemoglobin, some of them perhaps 
form the bile pigments, and it may be that they assume their final form in the epithelium of the 
renal tubules.] 
Chemistry of the Kidney.—The kidneys contain a very large amount of water. Besides 
serum-albumin, globulin, albumin soluble in sodium carbonate (Gottwalt), gelatin-yielding sub- 
stances, fat in the epithelium, elastic substance derived from the membrana propria of the tubules, 
the kidneys contain leucin, xanthin, hypoxanthin, kreatin, taurin, inosit, cystin (the last in no 
other tissue), but only in very small amount. The occurrence of these substances points to a 
lively metabolism in the kidneys, which is also proved by the liberal supply of blood they 
receive. 
Blood-vessels of the Kidney.—The kidneys receive a very large supply 
of blood, and during secretion the blood of the-renal vein is bright red. 
[In the dog the diameter of the renal artery may be diminished to .5 mm. with- 
out the amount of blood flowing through the kidney being thereby greatly 
interfered with. Hence, within wide limits, the amount of blood is indepen- 
dent of the size of the arterial lumen, and is therefore dependent on the blood- 
pressure in the aorta, and the resistance to the blood-current within and beyond 
the kidney (Heidenhaiti).~\ 
The reaction of the kidneys is acid, even in those animals whose urine is alkaline. Perhaps 
this fact is connected with the retention of the albumin in the vessels. 544 
INFLUENCE OF NERVES ON THE KIDNEY. 
[Sec. 275. 
275. PASSAGE OF VARIOUS SUBSTANCES INTO THE URINE —I. The 
following substances pass unchanged into the urine ; Sulphate, borate, silicate, nitrate, and 
carbonate of the alkalies; alkaline chlorides, bromides, iodides; potassium sulphocyanide and 
ferrocyanide; bile salts, urea, kreatinin; cumaric, oxalic, camphoric, pyrogallic and carbolic 
acids. Many alkaloids, e. g., morphia, strychnia, curare, quinine, caffein; pigments, sulphindigo- 
tate of soda, carmine, madder, logwood, coloring matter of cranberries, cherries, rhubarb; san- 
tonin; lastly, salts of gold, silver, mercury, antimony, arsenic, bismuth, iron (but not lead), 
although the greatest part of these is excreted by the bile and the faeces. 
2. Inorganic acids reappear in man and carnivora as neutral salts of ammonia; in herbivora, 
as neutral salts of the alkalies. 
3. Certain substances which, when injected in small amount, seem to be decomposed in the 
blood, pass in part into the urine, when they occur in such large amount in the blood that they 
cannot be completely decomposed—sugar, haemoglobin, egg-albumin, alkaline salts of the vege- 
table acids, alcohol, chloroform. 
4. Many substances appear in an oxidized form in the urine—moderate quantities of organic 
alkaline salts, as alkaline carbonates (Wohler), uric acid in part as allantoin (Salkowski), sul- 
phides and sulphites of soda, in part as sodium sulphate, potassium sulphide as potassium sulphate, 
some oxyduls as oxides, benzol as phenol (Naunyn and Schulzen). 
5. Those bodies which are completely decomposed, as glycerin, resins, give rise to no special 
derivatives in the urine. 
6. Many substances combine and appear as conjugated compounds in the urine, e.g., the 
origin of the hippuric acid by conjugation ($ 260), the conjugation of sulphuric acid ($ 262), and 
the formation of urea by synthesis from carbamic acid and ammonia (Drechsel) ($ 256). After 
the use of camphor, chloral, or butylchloral, a conjugated compound with glycuronic acid (an 
acid nearly related to sugar) appears in the urine (p. 529). [Chloral appears as urochloralic 
acid, and chloroform partly as urochloralic acid; gallic and pyrogallic acids partly as such, and 
partly as pyrogallol, pyrokatechin, and other substances which turn brown when alkaline urine 
is exposed to the air.] Taurin and sarcosin unite with sulphaminic acid. When bromophenol 
is given, it unites with mercapturic acid, a body nearly related to cystin (§ 268). 
7. Tannic acid, C14H10O9, takes up H20, and is decomposed into two molecules of gallic acid 
— 2(C?H606). 
8. The iodates of potash and soda are reduced to iodides; malic acid (C4H605) partly to 
succinic acid (C4H604); indigo-blue (ClgH10N2O2) takes up hydrogen and becomes indigo-white 
(C16H12NA). 
9. Some substances do not pass into the urine at all, e. g., oils, insoluble metallic salts 
and metals. 
276. INFLUENCE OF NERVES AND OTHER CONDI- 
TIONS.—At present we are acquainted merely with the influence of the 
vaso-motor nerves on the circulation through the renal vessels. Each 
kidney seems to be supplied with vaso-motor nerves, which spring from both 
halves of the spinal cord (Nicolaides). As a general rule, dilatation of the 
branches of the renal artery, chiefly the vasa afferentia, must raise the pressure 
within the glomeruli, and thus increase the amount of water filtered through 
them. The more the dilatation is confined to the area of the renal artery 
alone, the greater is the amount of the urine. In the dog, the lower dorsal 
nerves contain the most vaso-motor nerves—both vaso-constrictor and vaso- 
dilator (p. 548)—for the kidney (.Bradford). [As yet we know the nervous 
system influences the secretion of urine only in so far as it modifies the pressure 
and velocity of the blood-current in the kidney. We have no satisfactory 
evidence of the existence of direct secretory nerves in the kidney.] 
1. Renal Plexus and its Centre.—Section of the nerves of the renal 
plexus—the nerves around the renal artery—generally causes a considerable 
increase in the secretion of urine, hydruria or polyuria; sometimes, on 
account of the great rise of the pressure within the glumeruli, albumin passes 
into the urine, and there may be rupture of the vessels of the glomeruli, leading 
to the passage of blood into the urine. The nerve centre for the renal 
nerves lies in the floor of the fourth ventricle, in front of the origin of the 
vagus. Injury to this part of the floor of the fourth vemricle, e.g., by puncture 
(piqtire), may increase the amount of urine (diabetes insipidus), which is 
sometimes accompanied by the simultaneous appearance of albumin and blood Sec. 276.] 
INFLUENCES AFFECTING THE KIDNEY. 
545 
in the urine (CY. Bernard). Section of the parts which lie directly in the 
course of these fibres, as they pass from their centre to the kidney, produces 
the same effects. Close to this centre in the medulla lies the centre for the 
vaso-motor nerves of the liver, whose injury causes diabetes mellitus (§ 175). 
Eckhard found that stimulation of the vermiform process of the cerebellum 
produced hydruria. In man, stimulation of these parts by tumors or inflamma- 
tion, etc., produces similar results. 
2. Paralysis of Limited Vascular Areas.—If, simultaneously with the 
paralysis of the nerves of the renal artery, the nerves of a neighboring large 
vascular area be paralyzed, necessarily the blood-pressure in the renal artery 
area will not be so high, as more blood flows into the other paralyzed province. 
Under these circumstances, there may be only a temporary, or, indeed, no 
increase of urine, provided the paralyzed area be sufficiently large. There is a 
moderate increase of urine for several hours after section of the splanchnic 
nerve. This nerve contains the renal vaso-motor nerves (which, in part at 
least, leave the spinal cord at the first dorsal nerve and pass into the sympathetic 
nerve), but it also contains the vaso-motor nerves for the large area of the 
intestinal and abdominal viscera. Stimulation of this nerve has the opposite 
effect (Cl. Bernard, Eckhard). [The polyuria thus produced is not so great 
as after section of the renal nerves, because the splanchnic supplies such a large 
vascular area, that much blood accumulates in that area, and also because all 
the renal nerves do not run in the splanchnics.] 
3. Paralysis of Large Areas.—If, simultaneously with paralysis of the 
renal nerves, the great majority of the vaso-motor nerves of the body be 
paralyzed [as by section of the medulla oblongata], then, owing to the. great 
dilatation of all these vessels, the blood-pressure falls at once throughout the 
arterial system. The result of this may be, provided the pressure is sufficiently 
low, that there is a great decrease, or, it may be, entire cessation of the secre- 
tion of urine. The secretion is arrested when the cervical cord is completely 
divided, down even as far as the seventh cervical vertebra (Eckhard). The 
polyuria caused by 
injury to the floor of 
the fourth ventricle 
at once disappears 
when the spinal cord 
(even down to the 
twelfth dorsal nerve) 
is divided. 
[4. Other Condi- 
tions.—As already 
stated, section of the 
renal nerves is fol- 
lowed by polyuria, 
owing to the in- 
creased pressure in 
the glomeruli, but 
this polyuria may be 
increased by stimu- 
lating the spinal cord 
below the medulla oblongata, because the contraction of the blood-vessels 
throughout the body still further raises the blood-pressure within the glomeruli. 
If, however, the spinal cord be divided below the medulla oblongata—the renal 
nerve being also divided—the polyuria ceases, because of the fall of the general 
blood-pressure thereby produced. Division of the spinal cord in the dorsal 
F’g- 347- 
View of renal oncometer; the small one is shown open. 546 
ONCOMETER. 
[Sec. 276. 
region also diminishes or arrests the secretion of urine, owing to the fall of the 
blood-pressure; but animals recover from this operation, the general blood- 
pressure rises, and with it the secretion of urine. Stimulation of the cord 
below the medulla arrests the secretion, as it causes contraction of the renal 
arteries along with the other arteries of the body.] 
[Volume of the Kidney—Oncometer.—By means of the plethysmograph 
(§ 101), we can measure the variations in the size of a limb, while by the onco- 
graph (Syxoq, volume) similar variations in the volume of the spleen are 
measured (§ 103). Roy and Cohnheim have measured the variations in the 
volume of the kidney by means of an instrument which consists of two parts, 
one termed the oncometer or renal plethysmometer, in which the organ 
is enclosed, while the other part is the registering portion or oncograph. 
The kidney is enclosed in a kidney-shaped metallic capsule (figs. 347, 348), 
composed of two halves which move on the hinge, h, to introduce the organ. 
The renal vessels pass out at a, v. The kidney is surrounded with a thin 
membrane, and between this membrane and the inner surface of the capsule is 
a space filled with warm oil through the tube, I, which is closed by means of a 
Fig. 348. 
Fig. 349- 
Fig. 348.—Oncometer. K, kidney; the thick line is the metallic capsule; h, hinge; I, tube 
for filling apparatus; T, tube to connect with Tj; a,v,u, artery, vein, ureter [Stirling, 
after Roy). Fig. 349.—Oncograph. O', chamber filled with oil, communicating by 
with T; p, piston; /, writing-lever (Stirling, after Roy). 
stop-cock after the space is filled with oil. The tube T can be made to com- 
municate with another tube, T1} leading into a metallic chamber, C, of the 
oncograph (fig. 349), which is provided with a movable piston, p, attached by 
a thread to the writing-lever, /. Any increase in the size of the organ expels 
oil from the chamber, O, into C', and thus the piston is raised, while a diminu- 
tion in the size of the kidney diminishes the fluid in C', and the lever falls. 
The actual volume of the living kidney depends upon the state of distention of 
its structural elements, upon the amount of lymph in its lymph-spaces, but 
chiefly upon the amount of blood in its blood-vessels, and this again must 
depend upon the condition of the non-striped muscles in the renal arteries. 
When the vessels dilate, the kidney increases in size, and when they contract 
it contracts, so that we can register on the same revolving cylinder the varia- 
tions of the volume at the same time that we record the general arterial blood- 
pressure.] 
[In the normal circulation through the kidney, the kidney-curve, i. e., the 
curve of the volume of the kidney, runs parallel with the blood-pressure curve, 
and shows the large respiratory undulations, as well as the smaller elevations 
due to the systole of the heart (fig. 350). In this respect it differs sharply from Sec. 276.] 
VASO-MOTOR NERVES OF THE KIDNEY. 
547 
a spleen-curve (fig. 140). Usually, when the blood-pressure falls, the kidney- 
curve sinks, and when the blood-pressure rises the volume of the kidney in- 
creases. When the blood-pressure curve is complicated by Traube-Hering 
waves (§ 85) the opposite effect is produced on the kidney-curve; the highest 
blood-pressure corresponds to the smallest size of the kidney, and conversely. 
This is due to the fact that, when these curves occur, all the small arterioles, 
including those in the kidney, are contracted. A kidney placed in an oncome- 
ter secretes urine like a kidney under natural conditions.] 
[Arrest of the respiration in a curarized animal produces a rapid and 
great diminution of the volume of the kidney, caused by the venous blood 
stimulating the vaso-motor centres, and thus contracting the small arterioles, 
including those of the kidney. This result occurs whether one or both 
splanchnics are divided, proving that all the vaso-motor nerves of the kidney 
do not reach it through the splanchnics. When all the renal nerves at the 
hilum are divided, arrest of the respiration causes dilatation of the organ, which 
condition runs parallel with the rise of the blood-pressure. Stimulation of a 
sensory nerve, e.g., the central end of the sciatic nerve, while causing an 
increase of the blood-pressure, makes the kidney shrink.] 
[In poisoning with strychnin, the kidney shrinks while the blood-pressure 
rises. Stimulation of the central or peripheral end of the splanchnics, 
B. P., Blood-pressure curve ; K., curve of the volume of the kidney; T, time curve: intervals 
indicate a quarter of a minute; A, abscissa (Stirling, after Roy). 
Fig- 35°- 
divided at the diaphragm, causes contraction of the renal-vessels of both sides; 
the former is a reflex, the latter a direct effect. Stimulation of the peripheral 
end of one splanchnic sometimes affects both kidneys. Stimulation of the peri- 
pheral end of the renal nerves always causes a diminution in the volume of the 
kidney, so that Cohnheim and Roy inferred that, although there was evi- 
dence of the existence of vaso-motor and sensory nerves to the kidney, 
they found none of vaso-dilators. Each kidney acts independently of the 
other. Sudden compression of one renal artery has not the slightest effect upon 
the blood-current of the other kidney. If a kidney be exposed in an animal, 
by making an incision in the lumbar region, on stimulating the medulla ob- 
longata directly with electricity, we may observe the kidney itself becoming 
paler, the pallor appearing in a great many small spots on the surface of the 
organ, corresponding to the distribution of the interlobular arteries.] 
[Cohnheim showed that the chemical composition of the blood has a 
remarkable effect on the renal circulation, the kidney being very sensitive to 
such changes in the composition of the blood. Some substances (water and 
urea), when injected into the blood, cause the kidney first to shrink and then 
to expand, while sodic acetate dilates the kidney, even after all the renal 
nerves are divided—an operation which is very difficult indeed. Provided all 
the renal nerves be divided, these effects would indicate the existence of some 
local intra-rqnal vaso-motor mechanism governing the renal blood-vessels. The 548 
URAEMIA. 
[Sec. 276. 
general blood-pressure is not thereby modified ; nor need we wonder at this, 
as ligature of one renal artery does not increase the pressure in the aorta.] 
[Vaso-constrictor and vaso-dilator nerves to kidney.—Rose and 
Bradford, by enclosing the kidney of a dog in an oncometer-tube confirmed 
the view, that not only are the kidneys well supplied with vaso-constrictor 
fibres, but that they also receive vaso-dilator fibres. The vaso-constrictor 
fibres leave the spinal cord (dog) by the anterior roots of the spinal nerves as 
high as the 6th dorsal, and as low as the 2d lumbar (or even 4th); but by 
stimulating the peripheral end of each nerve-root singly, and observing the 
effect on the volume of the kidney, it has been shown that the largest number 
pass out by the nth, 12th, and 13th dorsal nerves. From the anterior roots 
they enter the corresponding ganglia of the sympathetic, they enter the solar 
plexus, and pass via the renal plexus into the kidney. Some apparently do not 
enter the splanchnic nerve. Vaso constrictor nerves are best excited by rapid 
electrical stimulation.] 
[Vaso-dilator fibres.—It is a peculiarity of vaso-dilator fibres that they 
are best excited by slow rhythmical stimulation (§ 372) (2-5 shocks per sec.), 
and if the peripheral end of the anterior roots of certain of these nerves be 
stimulated the kidney dilates, showing that these nerves contain vaso-dilator as 
well as vaso-constrictor fibres and the vaso-dilators seem to take the same 
course as the constrictors, being most abundant in the nth, 12th, and 13th 
dorsal nerves.] 
[The reciprocal relation between the skin and the kidneys is known to 
every one. On a cold day, when the skin is pallid, owing to contraction of 
the cutaneous vessels, the amount of urine secreted is great, and conversely, in 
summer less urine is passed than in winter. Washing the skin of a dog for two 
minutes with ice-cold water causes a great contraction of the kidney.] 
The perfusion of blood through a living excised kidney, i. <?., a 
“surviving kidney,” is materially influenced by the substances mixed with 
the blood perfused. This effect may in part be due to the action of these 
chemical ingredients upon the nuclei of the endothelial lining of the blood- 
vessels, especially the capillaries, or the effects upon the muscular fibres of the 
blood-vessels. 
[Strychnin seems to cause contraction of the renal vessels, independently of its action on the 
general vaso-motor centre. Brunton and Power found that digitalis caused an increase of the 
blood-pressure (dog), but the secretion of urine was either at the same time diminished, or it 
ceased altogether. The latter result was due to contraction of the renal blood-vessels, but when 
the aortic blood-pressure began to fall, the amount of urine secreted rose much above normal, 
i. e., when the arteries had begun to relax.] 
During fever, the renal vessels are probably contracted in consequence of the stimulation of 
the renal centre by the abnormally warm blood (Mendelsohn). 
The repeated respiration of CO is said to produce polyuria, perhaps in consequence of 
paralysis of the renal vaso-motor centre. 
Action of the Vagus.—According to Cl. Bernard, stimulation of the vagus at the cardia in- 
creases the urinary secretion, while at the same time the blood of the renal vein becomes red. 
This nerve may contain vaso dilator nerve-fibres corresponding to the fibres in the facial nerve 
for the salivary glands (§ 145). 
According to Arthaud and Butte, stimulation of the peripheral end of the vagus diminishes 
the blood stream in the kidney and the secretion of urine. Atropin, however, prevents this 
from taking place. The vagus, therefore, would appear to contain some vaso-motor fibres for 
the kidney. Stimulation of the cervical sympathetic also diminishes the secretion. This seems 
to be due to a reflex effect through the spinal cord affecting the splanchnics (Masius). 
277. URAEMIA—AMMONI-^EMIA.—Symptoms of Uraemia.—After excision of the 
kidneys, nephrectomy, or ligature of the ureter; in man also, as a result of certain diseased 
conditions of the kidney, leading to the suppression of the secretion of urine, there is developed 
a series of characteristic symptoms which are followed by death. The condition is called 
uraemic intoxication, or urtzmia. There are marked cerebral phenomena, drowsiness, and deep Sec. 277.] 
STRUCTURE OF THE URETER. 
549 
coma, and occasionally local or more general spasms. Sometimes there is delirium ; Cheyne- 
Stokes’ phenomenon is often observed (§ ill, II), and there may be vomiting and diarrhoea, 
while in the fluids voided, as well as in the expired air, ammonia may sometimes be detected. 
The cause of these phenomena has been ascribed to the retention in the blood of those sub- 
stances which normally are excreted by the urine, but as yet it has not been definitely ascer- 
tained which of these substances causes the phenomena:— 
1. The first thought is to ascribe them to the retention of the urea. V. Voit found that 
dogs exhibited uraemic symptoms if they were fed for a long time on food containing urea and 
little water. Meissner found that in nephrectomized animals the uraemic symptoms were 
hastened by the injection of urea into the blood. The injection of a moderate amount of urea 
in perfectly healthy animals is not followed by uraemic symptoms, probably because the urea 
is rapidly excreted by the kidneys; i to 2 grams [15 to 30 grains] so injected produce 
comatose symptoms in rabbits. Dogs died in convulsions after the subcutaneous injection of 
urea equal to 1 per cent, of their body-weight. Although animals die with convulsions after the in- 
jection of urea, this is not to be confounded with the intermittent convulsions of uraemic poisoning. 
2. The injection of ammonium carbonate produces symptoms resembling those of uraemia, 
so that v. Frerichs thought that the urea was decomposed in the blood, yielding ammonium 
carbonate—ammoniaemia. Demjankow observed uraemic phenomena after nephrectomy, if at 
the time he injected urea-ferment into the blood (§ 263). Neither after nephrectomy alone, nor 
with simultaneous injection of urea into the blood, has any ammonia been found in the blood. 
It seems, therefore, that the spontaneous formation of urea cannot take place in the blood, and 
it cannot be the cause of uraemic convulsions. Feltz and Ritter obtained uraemic symptoms in 
dogs by injecting salts of ammonia into the blood. 
3. As ligature of the ureters produces a comatose condition in those animals which excrete 
chiefly uric acid in the urine—e.g., birds and snakes (Zalesky)—it is possible that other sub- 
stances may produce the poisonous symptoms. The injection of kreatinin causes feebleness 
and contraction of the muscles in dogs (Meissner). Bernard, Traube, and more recently Feltz 
and Ritter, ascribe the symptoms to an accumulation of the neutral potassium salts in the blood 
(| 54). The injection of kreatin, succinic acid (Meissner), uric acid, and sodic urate (Ranke), 
is without effect. Schottin and Oppler ascribe the results to an accumulation of normal or ab- 
normal extractives. It is possible that several substances and their decomposition-products con- 
tribute to produce the result, so that there is a combined action of several factors, but perhaps 
the retention of th& potash salts plays the most important part. 
The direct application of some urinary substances (kreatinin, kreatin, acid potassic phosphate, 
urates) to the surface of the cerebrum causes all the symptoms of uraemia. Urea is inactive, 
and slightly active are ammonium and sodic carbonate, leucin, NaCl, KC1 (Landois). 
[Alkaloids in Urine.—Human urine, and especially febrile urine, when injected under the 
skin of frogs or rabbits, acts as a poison, and even causes death, by arresting the respiration. 
The alkaloids, i. <?., ptomaines and leucomaines, seem to be formed by the action of vegetable 
organisms in the intestine, whence they are absorbed into the blood, and pass into the urine 
(§ 116). This, however, is denied by some observers, who state that normal urine is free from 
such bodies. Urine rendered colorless by charcoal loses half its toxic power, and the poisonous 
substance is not volatile, and even resists boiling. These alkaloids are increased in the urine 
in typhoid fever, pneumonia, but not in diabetes.] 
Uric Acid Diathesis.—When too much nitrogenous food, too much of any alcoholic fluid 
is persistently used, and little muscular exercise taken, especially if the respiratory organs are in- 
terfered with, uric acid may not unfrequently accumulate in the blood (Garrod). It may be 
deposited in the joints and their ligaments, especially in the foot and hand, giving rise to pain- 
ful inflammation, and forming gout-stones or chalk-stones [which are acid-urates]. The heart, 
liver, and kidneys are rarely affected. The tissues near these deposits undergo necrosis. 
278. STRUCTURE AND FUNCTIONS OF THE URETER. 
—Mucous Membrane.—The pelvis of the kidney and the ureter are lined 
by a mucous membrane, consisting of connective-tissue, and covered with 
several layers of stratified “transitional” epithelium (fig. 352). The cells 
are of various shapes, those of the lowest layer being usually more or less 
spherical and small, while many of the cells in the upper layers are irregular in 
shape, often with long processes passing into the deeper layers. 
Sub-mucosa.—Under the epithelium there is a layer of adenoid tissue 
(.Hamburger, Chiari), which may contain small lymph-follicles [embedded in 
loose connective-tissue]. In the pelvis of the kidney and ureter there are a 
few small mucous glands lined by a single layer of columnar epithelium 
( Unruh, Egli ). 550 
MOVEMENT OF THE URINE. 
[Sec. 278. 
The muscular coat consists of an inner somewhat stronger layer of longi- 
tudinal non-striped fibres, and an outer circular layer (fig. 351). In the lowest 
third of the ureter there are in addition a number of scattered muscular fibres. 
All these layers are surrounded and supported by connective-tissue. The outer 
layers of the connective-tissue form an outer coat or adventitia, which con- 
tains the large vessels and nerves. The various coats of the ureter can be 
followed up to the pelvis of the kidney, and to its calices. The papillae are 
covered only by the mucous membrane, while the muscular layer ceases at the 
apex of the pyramids, where they are disposed circularly, to form a kind of 
sphincter muscle for each papilla (Henie). 
The blood-vessels supply the various coats, and form a capillary plexus under the epithelium. 
The nerves are not very numerous, but they contain medullated (few) and non-medullated 
fibres, with numerous ganglia scattered in their course. They are partly motor and supply the 
muscular layers, and some pass towards the epithelium, and are sensory and excito-reflex in func- 
tion. These nerves are excited when a calculus passes along the ureter, and thus give rise to 
Adventitia. 
Cylindrical 
cells. 
Leucocyte. 
Tunica 
propria. 
Fig. 351- 
Fig- 352. 
Transverse section of the lower part of human ureter, 
X 15. e, epithelium; /.tunica propria; j, sub- 
mucosa ; / and r, longitudinal and circular fibres. 
Vertical section of the mucous membrane of 
a human bladder. 
severe pain. The ureter perforates the wall of the bladder obliquely. The inner opening is a 
narrow slip in the mucous membrane, directed downwards and inwards, and provided with a 
pointed valve-like process (fig. 354). 
Movement of the Urine.—The urine is propelled along the ureter thus: 
—(x) The secretion, which is continually being formed under a high pressure 
in the kidney, propels the urine onwards in front of it, as the urine is under a 
low pressure in the ureter. (2) Gravity aids the passage of the urine when the 
person is in the erect posture. (3) The muscles of the ureter contract rhyth- 
mically and peristaltically, and so propel it towards the bladder. This move- 
ment is reflex, and is due to the presence of the urine in the ureter. Every 
three-quarters of a minute several drops of urine pass into the bladder. But 
the fibres may also be excited directly. The contraction passes along the tube 
at the rate of twenty to thirty mm. per second, always from above downwards. 
The greater the tension of the ureter due to the urine, the more rapid is the 
peristaltic movement. Sec. 278.] 
URINARY BLADDER AND URETHRA. 
551 
Local Stimulation.—On applying a stimulus to the ureter directly, the contraction passes 
both upwards and downwards. Engelmann observed that the movements occur in parts of the 
ureter where neither nerve nor ganglia were to be found, and he concluded that the movement 
was propagated by “muscular conduction.” If this be so, then an impulse may be pro 
pagated from one non-striped muscular cell to another without the intervention of nerves (see 
Heart, \ 58, I, 3). 
Prevention of Reflux.—The urine is prevented from exerting a backward 
pressure towardst he kidneys: (1) The urine which collects in the pelvis of 
the kidney is under a high pressure, and thus tends uniformly to compress the 
pyramids so that the urine cannot pass into the minute orifices of the urinary 
tubules. (2) When there is a considerable accumulation of urine in a ureter, 
e.g., from the presence of an impacted calculus or other cause, there is also 
more energetic peristalsis, and, at the same time, the circular muscular fibres 
round the apices of pyramids compress the pyramids and prevent the reflux of 
urine through the collecting tubules. The urine is prevented from passing back 
Fig- 353- 
Isolated transitional epithe- 
lium from the bladder of a 
guinea pig. Some of the 
large cells lie upon the 
summit of the columnar 
and caudate cells, and de- 
pressions are seen on their 
under surface, a, a super- 
ficial cell seen from the 
side, and a' from below ; b, 
and c, cells from the deeper 
layers, x 3°° (Stirling). 
Fig- 354- 
Lower part of the human bladder laid open, showing clear part, 
or trigone, the slit like openings of the ureters, the divided 
ureters, and vesiculse seminales; the sinus prostaticus, and on 
each side of it the openings of the ejaculatory ducts, and 
below both numerous small apertures of the prostatic ducts. 
from the bladder into the ureter, the wall of the bladder itself, and the part of 
the ureter which passes through it, are compressed, so that the edges of the 
slit-like opening of the ureter are rendered more tense, and are thus approx- 
imated towards each other (fig. 354). 
279. URINARY BLADDER AND URETHRA.—Structure.— 
The mucous membrane of the bladder resembles that of the ureter ; the 
upper layers of the stratified transitional epithelium are somewhat flattened (fig. 
354). It is obvious that the form of the cells must vary with the state of dis- 
tention or contraction in the bladder. [The mucous membrane and muscular 
coats are thicker than in the ureter. There are mucous glands in the mucous 
membrane, especially near the neck of the bladder.] 
Sub-mucous Coat.—There is a layer of delicate fibrillar connective-tissue 
mixed with elastic fibres between the mucous and muscular layers. 
[The serous coat is continuous with, and has the same structure as the 
peritoneum and it covers only the posterior and upper half of the organ.] [Sec. 279. 
552 
URINARY BLADDER AND URETHRA. 
Musculature.—Non-striped muscular fibres are arranged in bundles in 
several layers, an external longitudinal layer, best developed on the anterior and 
posterior surfaces, and an imier circular layer. [Between these two is an 
oblique layer.] There are other bundles of muscular fibres arranged in different 
directions. Physiologically, the musculature of the bladder represents a 
single or common hollow muscle, whose function when it contracts is to dimin- 
ish uniformly the size of the bladder, and thus to expel its contents (§ 306). 
The blood-vessels resemble those of the ureter. The nerves form a plexus, and are placed 
partly in the mucous membrane and partly in the muscular coat, and, like all the extra-renal 
parts of the urinary apparatus, are provided with ganglia, lying in the mucosa, sub-mucosa, 
and connected to each other by fibres (Maier). Ganglia occur in the course of the motor nerve- 
fibres in the bladder ( W. IVolff). Their functions are motor, sensory, excito-motor, and 
vaso-motor. [Sympathetic nerve-ganglia also exist underneath the serous coat (F\ Dar- 
win).] 
A too minute dissection of the several layers and bundles of the musculature of the bladder 
has given rise to erroneous inferences. Thus, we speak of a detrusor urinae, which, however, 
consists chiefly of fibres running on the anterior and posterior surfaces, from the vertex to the 
fundus. There does not seem to be a special sphincter vesicae internus ; it is merely a thicker 
circular (6 to 12 mm.) layer of non-striped muscle which surrounds the beginning of the 
urethra, and which, from its shape, helps to form the funnel-like exit of the bladder. Numerous 
muscular bundles, connected partly with the longitudinal and partly with the circular fibres of 
the bladder, exist, especially in the trigone, between the orifice of the ureters. 
In the female, the urethra serves merely for the passage of urine. The mucous membrane 
consists of connective-tissue with many elastic fibres, and provided with papillae. It is covered 
by stratified epithelium and contains several mucous glands (Liltre). Outside this is a layer of 
longitudinal, smooth, muscular fibres, and outside this again a layer of circular fibres. Many 
elastic fibres exist in all the layers, which are traversed by numerous wide venous channels. 
The proper sphincter urethrae is a transversely striped muscle subject to 
the will, and consists of completely circular fibres which extend downwards as 
far as the middle of the urethra, and partly of longitudinal fibres, which extend 
only on the posterior surface towards the base of the bladder, where they be- 
come lost between the fibres of the circular layer. 
In the male urethra, the epithelium of the prostatic part is the same as that in the bladder; 
in the membranous portion it is stratified, and in the cavernous part the simple cylindrical form. 
The mucous membrane, under the epithelium itself, is beset with papilla, chiefly in the posterior 
part of the urethra, and contains the mucous glands of Littre. 
Non-striped muscle occurs in the prostatic part arranged longitudinally, chiefly at the 
colliculus seminalis; in the membranous portion the direction of the fibres is chiefly circular, 
with a few longitudinal fibres intercalated; the cavernous part has a few circular fibres 
posteriorly, but anteriorly the muscular fibres are single and placed obliquely and longitudi- 
nally. 
Closure of the Bladder.—The so-called internal vesical sphincter of the 
anatomists, which consists of non-striped muscle, is in reality an integral part 
of the muscular coat of the bladder, and surrounds the orifice of the urethra as 
far down as the prostatic portion, just above the colliculus seminalis. It is, 
however, not the sphincter muscle. The proper sphincter urethrae (sph. 
vesicse externus) lies below the latter. It is a completely circular muscle dis- 
posed around the urethra, close above the entrance of the urethra into the sep- 
tum urogenitale at the apex of the prostate, where it exchanges fibres with the 
deep transverse muscle of the peringeum which lies under it. 
Some longitudinal fibres, which run along the upper margin of the prostate from the bladder, 
belong to this sphincter muscle. Single transverse bundles passing forward from the surface of 
the neck of the bladder, the transverse bands which lie within the prostate, the apex of the 
colliculus seminalis, and a strong transverse bundle passing in front of the origin of the urethra 
into the substance of the prostate—all belong to the sphincter muscle (Henle). In the male 
urethra, the blood-vessels form a rich capillary plexus under the epithelium, below which is a 
wide-meshed lymphatic plexus. 
[Tonus of Sphincter Urethrae.—Open the abdomen of a rabbit, ligature one ureter, tie a Sec. 279.] 
MICTURITION. 
553 
cannula in the other, and pour water into the bladder until it runs out through the urethra, 
which usually occurs under a pressure of 16 to 20 inches. If the spinal cord be divided between 
the fifth and seventh lumbar vertebrae, a column of 6 inches is sufficient to overcome the 
resistance of the sphincter, while section at the fourth lumbar vertebra has no effect on the 
height of the pressure. In such an animal the bladder becomes distended, but in one with 
its cord divided between the fifth and seventh lumbar vertebrae, there is incontinence of urine— 
in the former case because the excito-motor impulses are cut off from the centre (5 to 7 vert.), 
and in the latter because the tonus of the sphincter is destroyed (Kupressow). This tonus is 
denied by Landois and others.] 
280. ACCUMULATION OF URINE—MICTURITION.—After 
emptying the bladder, the urine slowly collects again, the bladder being there- 
by gradually distended. [A healthy bladder may be said to be full when it 
contains 20 oz.] As long as there is a moderate amount of urine in the 
bladder, the elasticity of the elastic fibres surrounding the urethra, and that of 
the sphincter of the urethra (and in the male of the prostate), suffice to retain 
the urine in the bladder. This is shown by the fact that the urine does not escape 
from the bladder after death. If the bladder be greatly distended (1.5 to 1.8 
litre), so that its apex projects above the pubes, the sensory nerves in its walls 
are stimulated and cause a feeling of a full bladder, while at the same time the 
urethral opening is dilated, so that a few drops of urine pass into the beginning 
of the urethra. Besides the subjective feeling of a full bladder, this tension of 
the walls of the bladder causes a reflex effect, so that the urinary bladder con- 
tracts periodically upon its fluid contents, and so do the sphincter of the urethra 
and the muscular fibres of the urethra, and thus the urethra is closed against the 
passage of these drops of urine. As long as the pressure within the bladder is 
not very high, the reflex activity of the transversely striped sphincter over- 
comes the other (as during sleep); but as the pressure rises and the distention 
increases, the contraction of the walls of the bladder overcomes the closure 
produced by the sphincter, and the bladder is emptied, as occurs normally in 
young children. 
As age advances, the sphincter urethrae comes under the control of the will, 
so that it can be contracted voluntarily, as occurs in man when he forcibly 
contracts the bulbo-cavernosus muscle to retain urine in the bladder. The 
sphincter ani usually contracts at the same time. The reflex activity of the 
sphincter may also be inhibited voluntarily, so that it may be completely re- 
laxed. This is the condition when the bladder is emptied voluntarily. 
Slight movements, confined to the bladder, occur during psychical or emotional disturbances 
(e. g., anger, fear), [the bladder may be emptied involuntarily during a fright], after stimulation 
of sensory nerves, auditory impressions, restraining respiration, and by arrest of the heart’s 
action. There are slight periodic variations coincident with variations in the blood-pressure. 
The contractions of the bladder cease after deep inspiration, and also during apnoea (Mosso and 
Pellacani). The excised bladder of the frog, and even portions free from ganglia, exhibit 
rhythmical contractions, which are increased by heat (Pfalz). [Ashdown found in dogs that 
the bladder exhibits regular rhythmical contractions,, which were influenced by the degree of 
distention of the bladder, being most marked with moderate dilatation and least when the 
bladder was feebly or over-distended. The contractions could be registered by means of a 
water-manometer communicating with the interior of the bladder.] 
Nerves of Micturition.—The nerves concerned in the retention and 
evacuation of the urine are : 1. The motor nerves of the sphincter urethrae, 
which lie in the pudendal nerve (anterior roots of the third and fourth sacral 
nerves). When these nerves are divided, as soon as the bladder becomes so 
distended as to dilate the urethral opening, the urine begins to trickle away 
(incontinence of urine). 2. The sensory nerves of the urethra, which excite 
these reflexes, leave the spinal cord by the posterior roots of the third, fourth 
and fifth sacral nerves. Section of these nerves causes incontinence of urine. 
The centre for the reflex in dogs lies opposite the fifth, and in rabbits opposite 554 
MECHANISM OF MICTURITION. 
[Sec. 280. 
the seventh lumbar vertebra (Budge). 3. Fibres pass from the cerebrum— 
those that convey voluntary impulses through the peduncles, and the anterior 
columns of the spinal cord (according to Mosso and Pellacani, through the 
posterior columns and the posterior part of the lateral columns), to the motor 
fibres of the sphincter urethrae. 4. The inhibitory fibres concerned in the 
reflex-inhibition of the sphincter urethrae take the same course (perhaps from 
the optic thalamus?) downwards through the cord to where the third, fourth 
and fifth sacral nerves leave it. 5. Sensory nerves proceed from the urethra 
and bladder to the brain, but their course is not known. Some of the motor 
and sensory fibres lie for a part of their course in the sympathetic. 
[Just as the rectum is supplied by two sets of nerve-fibres, so the bladder 
receives nerve-fibres, viz., from the sacral nerves. Stimulation of these nerves 
not only causes contraction of the longitudinal fibres of the rectum, but also 
contraction of the bladder, in which act the longitudinal muscular fibres of the 
bladder take the most active part. Stimulation of the hypogastric nerves coming 
from the upper lumbar and dorsal region cause chiefly contraction of the circular 
fibres of the bladder, as well as contraction of the circular fibres of the rectum.] 
Transverse section of the spinal cord above where the nerves leave it, 
is always followed in the first instance by retention of urine, so that the bladder 
becomes distended. This occurs because—(1) the section of the spinal cord 
increases the reflex activity of the urethral sphincter; and (2) because the 
inhibition of this reflex can no longer take place. As soon, however, as the 
bladder becomes so distended, as in a purely mechanical manner to cause dilata- 
tion of the urethral orifice, then the urine trickles away, but the amount of 
urine which trickles out in drops is small. Thus the bladder becomes more and 
more distended, as the continuously distended walls of the organ yield to the 
increased tension, so that the bladder may become distended to an enormous 
extent. The urine very frequently becomes ammoniacal, accompanied by 
catarrh and inflammation of the bladder (§ 263). 
[In dogs, with their cord divided at the last dorsal vertebra,—whereby the 
lumbar part of the cord is completely cut off from all volitional impulses,—after 
a time, i. e., when the cord has recovered, micturition takes place reflexly when 
the bladder is full. The reflex act may be excited by gentle stimulation of the 
skin round the anus or slight pressure on the abdomen (Goltz).~\ 
Voluntary Micturition.—Observers are not agreed as to the mechanism 
concerned in emptying the bladder when it is only partially full. It is stated by 
some that a voluntary impulse passes from the brain along a cerebral peduncle, 
and the cord, to the anterior roots of the third and fourth sacral nerves, 
and partly through motor fibres from the second to the fifth lumbar nerves 
(especially the third), to act directly upon the smooth muscular fibres of the 
bladder. This is assumed, because electrical stimulation of any part of this 
nervous channel causes contraction of the bladder. This view, however, does 
not seem to be the true one. It is to be remembered that Budge showed that 
the sensory nerves of the wall of the bladder are contained in the first, second, 
third, and fourth sacral nerves, and also in part in the course of the hypogastric 
plexus, whence they ultimately pass by the rami communicantes into the spinal 
cord. 
According to Landois, the smooth musculature of the bladder cannot be ex- 
cited directly by a voluntary impulse, but it is alw’ays caused to contract reflexly. 
If we wish to micturate when the urinary bladder contains a small quantity of 
urine, we first excite the sensory nerves of the opening of the urethra, either by 
causing contraction or relaxation of the sphincter urethrae, or by means of 
slight abdominal pressure, and thus force a little urine into the urethral orifice. 
This sensory stimulation causes a reflex contraction of the walls of the urinary Sec. 280.J 
MECHANISM OF MICTURITION. 
555 
bladder. At the same time, this condition is maintained voluntarily, by the 
action of the intracranial reflex-inhibitory centre of the sphincter urethrae. The 
centre for the reflex stimulation of the movements of the walls of the urinary 
bladder is placed somewhat higher in the spinal cord than that for the sphincter 
urethrae. In dogs, it is opposite the fourth lumbar vertebra ( Gianuzzi, Budge). 
[Two centres are assumed to exist in the cord, fig. 355, one the automatic (A.C.) at the seg- 
ment corresponding to the second, third, and fourth sacral nerves, which maintains the tonic 
action of the sphincter; the other, a reflex centre (R.C.), is situated 
higher, and through it the detrusor urinae is excited to contraction. 
Both centres are connected with and governed or controlled by a 
cerebral centre (C). The automatic centre is connected with the 
sphincter, and the other with the urine-expelling fibres. They are 
also connected with afferent fibres from the bladder and elsewhere. 
The afferent or sensory fibres are also connected with the brain. The 
automatic centre maintains the closure of the bladder, but if the 
latter be distended, different impulses proceeding from it reach the 
spinal centre, and it may be the cerebrum. The impulses reaching 
the automatic centre inhibit its action and those to the reflex centre 
excite it, so that the detrusor urinse contracts. If the afferent im- 
pulses be powerful, a desire to urinate is excited, and voluntary 
impulses are excited which act upon the spinal centres as the affer- 
ent impulses do, and thus the act of urination is more easily accom- 
plished.] 
We may conceive a voluntary impulse to pass down special fibres 
to an inhibitory centre, which may either act directly on the motor 
centre,or possibly may send branches directly to the sphincter muscles. 
Painful stimulation of sensory nerves causes reflex contraction of 
the bladder and evacuation of the urine (in children during teeth- 
ing). Reflex contraction of the bladder can be brought about in 
cats by stimulation of the inferior mesenteric ganglion. After sec- 
tion of all the nerves going to the bladder, hemorrhage and asphyxia 
cause contraction by a direct effect upon the structures in the wall 
of the bladder. As yet no one has succeeded in exciting artificially 
the inhibitory centre in the brain for the sphincter muscle (Sokowin 
and Kowalesky). 
It seems probable that, as in the case of the anal sphincter (§ 
160), there is not a continuous tonic reflex stimulation of the sphinc- 
ter urethrae ; the reflex is excited each time by the contents. The 
sphincter vesicas of the anatomists, which consists of smooth muscu- 
lar tissue, does not seem to take part in closing the bladder. Budge 
and Landois found that, after removal of the transversely striped 
sphincter urethrae, stimulation of the smooth sphincter did not cause 
occlusion of the bladder, nor could L. Rosenthal or v. Wittich convince themselves of the pres- 
ence of tonus in this muscle. Indeed, its very existence is questioned by Henle. 
Changes of the Urine in the Bladder.—When the urine is retained in the bladder for a 
considerable time, according to Kaupp, there is an increase in the sodium chloride and a decrease 
in the urea and water. Urine which remains for a long time in the bladder is prone to undergo 
ammoniacal decomposition. 
Absorption.—Many observers have shown that the mucous membrane of the bladder is 
capable of absorbing substances—potassium iodide and other soluble salts. [Ashdown has shown 
that poisons, such as watery solutions of strychnin, curare, eserin, emulsions of chloroform and 
ether, are absorbed when injected into the bladder of rabbits. In rabbits, KI injected into the 
bladder through a catheter was found in the urine obtained from the divided ureters. Water and 
urea are also absorbed—the latter in larger proportion than the former.] 
As the ureters enter near the base of the bladder, the last-secreted urine is always lowest. If a 
person remain perfectly quiet, strata of urine are thus formed, and the urine may be voided so 
as to prove this (Edlefsen). 
The pressure within the bladder, when in the supine position — 13 to 15 centimetres of 
water. Increase of the intra-abdominal pressure (by inspiration, forced expiration, coughing, 
bearing down) increases the pressure within the bladder. The erect posture also increases it, 
owing to the pressure of the viscera from above (Schatz, Dubois). [James obtained 4 to 4.5 
inches Hg as the highest expulsive power of the bladder, including the abdominal pressure, vol- 
untary and involuntary. In paraplegia, where there is merely the expulsive power of the bladder, 
he found 20 to 30 inches of water.] 
Fig- 355- 
Scheme of micturition :— 
A.C., R.C., C., automatic, 
reflex, and cerebral cen- 
tres; B., bladder; S., sen- 
sory centre acted on by 
afferent impulses. 556 
RETENTION OF URINE. 
[Sec. 280. 
[Hydronephrosis occurs when the ureters and pelvis of the kidney become dilated, owing 
to partial and gradual obstruction of the outflow of urine from the ureters: if the obstruction 
become complete, there is cessation of the urinary secretion. James has shown that the bladder 
remains contracted for several seconds after it is emptied, and this is specially the case in irritable 
bladder; so that this condition may also give rise to hydronephrosis by damming up the urine 
in the ureters.] 
Rapidity of Micturition.—The amount of urine voided at first is small, but it increases with 
the time, and towards the end of the act it again diminishes. In men, the last drops of urine 
are ejected from the urethra by voluntary contractions of the bulbo-cavernosus muscle. Adult 
dogs increase the stream rhythmically by the action of this muscle. 
281. RETENTION AND INCONTINENCE OF URINE.—Retention of urine or 
ischuria occurs: 1. When there is obstruction of the urethra, from foreign bodies, concretions, 
stricture, swelling of the prostate. 2. Paralysis or exhaustion of the musculature of the bladder; 
the latter sometimes occurs after delivery, in consequence of the pressure of the child against the 
bladder. 3. After section of the spinal cord (p. 554). 4. Where the voluntary impulses are 
unable to act upon the inhibitory apparatus of the sphincter urethrae reflex, as well as when the 
sphincter urethrae reflex is increased. 
Incontinence of urine (stillicidium urinae) occurs in consequence of: 1. Paralysis of the 
sphincter urethrae. 2. Loss of sensibility of the urethra, which of course abolishes the reflex of 
the sphincter. 3. Trickling of the urine is a secondary consequence of section of the spinal cord, 
or of its degeneration. 
Strangury is an excessive reflex contraction of the walls of the bladder and sphincter, due to 
stimulation of the bladder and urethra; it is observed in inflammation, neuralgia [and after the 
use of some poisons, e.g., cantharides]. 
Enuresis nocturna, or involuntary emptying of the bladder at night, may be due to an in- 
creased reflex excitability of the wall of the bladder, or weakness of the sphincter. 
282. COMPARATIVE AND HISTORICAL.—Amongst vertebrates, the urinary and 
genital organs are frequently combined, except in the osseous fishes. The Wolffian bodies, 
which act as organs of excretion during the embryonic period, remain throughout life in fishes 
and amphibians, and continue to act as such. Fishes.—The myxinoids (cyclostomata) have the 
simplest kidneys; on each side is a long ureter with a series of short-stalked glomeruli with cap- 
sules arranged along it. Both ureters open at the genital pore. In the other fishes, the kidneys 
lie often as elongated compact masses along both sides of the vertebral column. The two ureters 
unite to form a urethra, which always opens behind the anus, either united with the opening of 
the genital organs, or behind this. In the sturgeon and hag-fish, the anus and orifice of the 
urethra together form a cloaca. Bladder-like formations, which, however, are morphologically 
homologous with the urinary bladder of mammals, occur in fishes, either on each ureter (ray, 
hag-fish), or where both join. In amphibians, the vasa efferentia of the testicles are united 
with the urinary tubules; the duct in the frog unites with the one on the other side, and both 
conjoined open into the cloaca, whilst the capacious urinary bladder opens through the anterior 
wall of the cloaca. From reptiles upwards, the kidney is no longer a persistent Wolffian body, 
but a new organ. In reptiles, it is usually flattened and elongated ; the ureters open singly into 
the cloaca. Saurians and tortoises have a urinary bladder. In birds, the isolated ureters open 
into the urogenital sinus, which opens into the cloaca, internal to the excretory ducts of the geni- 
tal apparatus. The urinary bladder is always absent. In mammals, the kidneys often consist 
of many lobules, e.g., dolphin, ox. 
Amongst invertebrates, the mollusca have excretory organs in the form of canals, which 
are provided with an outer and inner opening. Inthemussel this canal is provided with a sponge- 
like organ, often with a central cavity, and consisting of ciliated secretory cells, placed at the 
base of the gills (organ of Bojanus). In gasteropods, with analogous organs, uric acid has been 
found. Insects, spiders, and centipedes have the so-called Malpighian vessels, which are 
excretory organs, partly for uric acid and partly for so-called bile. These vessels are long tubes, 
which open into the first part of the large intestine. In crabs, blind tubes connected with the 
intestinal tube perhaps have the same functions. The vermes also have renal organs. 
Historical.—Aristotle directed attention to the relatively large size of the human bladder— 
he named the ureters. Massa (1552) found lymphatics in the kidney. Eustachius (f 1580) 
ligatured the ureters and found the bladder empty. Cusanus (1565) investigated the color and 
weight of the urine. Rousset (1581) described the muscular nature of the walls of the bladder. 
Vesling described the trigone (1753)- The first important chemical investigations on the urine 
date from the time of van Helmont (1644). He isolated the solids of the urine, and found 
among them common salt; he ascertained the higher specific gravity of fever-urine, and ascribed 
the origin of urinary calculi to the solids of the urine. Scheele (1766) discovered uric acid and 
calcium phosphate; Arand and Kunckel, phosphorus; Rouelle (1773), urea; and it got its name 
from Fourcroy and Vauquelin (1799). Berzelius found lactic acid; Seguin, albumin in patho- 
logical urine; Liebig, hippuric acid; Heintz and v. Pettenkofer, kreatin and kreatinin; Wollas- 
ton (1810), cystin. Marcet found xanthin; and Lindbergson, magnesic carbonate. Sec. 283.] 
STRUCTURE OF THE SKIN. 
557 
Functions of the Skin. 
283. STRUCTURE OF THE SKIN, HAIR, AND NAILS.— 
The skin (3.3 to 2.7 mm. thick; specific gravity, 1057) consists of— 
[1. The epidermis ; 
2. The corium, or cutis vera, with the papillse (fig. 356).] 
The epidermis (0.08 to 0.12 mm. thick) consists of many layers of stratified 
epithelial cells united to each other by cement substance (figs. 356, 357, 358). 
The superficial layers—stratum corneum—consist of several or many layers 
of dry, horny non-nucleated squames, which swell up in solution of caustic soda 
Epidermis. 
Epidermis. 
Eleidin 
layer. 
Stratum 
Malpighii. 
Papilla. 
Cutis vera. 
Sweat-duct. 
Panniculus adiposus. 
Coil of 
sweat-gland. 
Fat-cells. 
Fig. 356. 
Vertical section of the human skin. 
(fig. 358, E). [It is always thickest where intermittent pressure is applied, as 
on the sole of the foot and palm of the hand.] The next layer is the 
stratum lucidum, which is clear and transparent in a section of skin, hence 
the name, and consists of a few compact layers of clear cells with vestiges of 
nuclei. [The cells are two or three deep, are without granules, and do not 
stain readily.] Under this is the rete mucosum or rete Malpighii (.fig. 358, 
f/), consisting of many layers of nucleated protoplasmic epithelial cells which 
contain pigment in the dark races, and in the skin of the scrotum, and around 
the anus. [The superficial cells are more fusiform—at least they appear fusi- 
form in section—and contain granules which stain deeply with carmine and 
osmic acid, and they are devoid of prickles. They constitute, 3, the stratum 558 
STRUCTURE OF THE SKIN. 
[Sec. 283. 
granulosum. In these cells the formation of keratin is about to begin, and 
they contain two sets of granules—the intra-cellular, hyaline, albuminoid 
granules of Waldeyer, which stain with logwood, and the eleidin granules of 
Ranvier, which seem to be allied to fatty bodies, and are readily stained by 
alkanet. All corneous structures contain 
similar granules in the area where the 
cells are becoming corneous. Then fol- 
low several layers of more or less polyhe- 
dral cells, constituting the stratum 
Malpighii, softer and more plastic in 
their nature, and exhibiting the charac- 
ters of so-called “prickle cells” (fig. 
358, R). [The spaces between the fibrils 
connecting adjacent cells are lymph- 
spaces.] The deepest layers of cells are 
more or less columnar, and the cells are 
placed vertically upon the papillae and 
are provided with spherical nuclei. 
Granular leucocytes or wandering cells 
are sometimes found between these cells. 
The rete Malpighii dips down between 
adjacent papillae and forms inter-papillary 
processes. According to Klein, a deli- 
cate basement membrane separates 
the epidermis from the true skin.] The 
superficial layers of the epidermis are 
continually being thrown off, while new 
cells are continually being formed in the 
deeper layers of the skin by proliferation 
of the cells of the rete Malpighii, so that 
many of the cells may exhibit mitosis. 
There is a gradual change in the micro- 
scopic and chemical characters of the 
cells from the deepest to the superficial 
layers of the epidermis. [In a vertical 
section of the skin stained with picro-carmine, the S. granulosum is deeply 
stained red, and is thus readily distinguished amongst the other layers of the 
epidermis.] 
Stratum 
"corneum. 
Stratum 
lucidum. 
Stratum 
-granu- 
losum. 
Stratum 
Malpighii. 
Fig- 357- 
Vertical section of the human epidermis; 
the nerve-fibrils, n, b, stained with gold 
chloride. 
(1) Stratum corneum, 
(2) Stratum lucidum, 
Cuticle. 
Epidermis 
(%• 
357), 
(3) Stratum granulosum, 
(4) Stratum Malpighii, 
Rete 
Mucosum. 
No pigment is formed within the epidermis itself [but in the colored races 
pigment-granules of melanin exist in the cells of the deepest layers of the 
stratum Malpighii] ; when it is present, it is carried by leucocytes from the 
subcutaneous tissue (KiehlEhrmann, Aeby). This explains how it is that a 
piece of white skin, transplanted to a negro, becomes black (Kary). 
[Herxheimer has described some peculiar “ spirals ” in the epidermis. They seem to be due 
to coagulation of a proteid.] 
The corium (fig. 358, I, C) is beset over its entire surface by numerous 
(0.5 to 0.1 mm. high) papillae (figs. 356, 358), the largest being upon the volar 
surface of the hand and foot, on the nipple and glans penis. Most of the 
papillse contain a looped capillary (g)f while in certain regions some of them Sec. 283.] 
STRUCTURE OF THE SKIN. 
559 
contain a touch-corpuscle (fig. 359, a). The papillae are disposed in 
groups, whose arrangement varies in different parts of the body. In the palm 
of the hand and sole of the foot they occur in rows, which are marked out 
I, Vertical section of the skin, with a hair and sebaceous gland, T. Epidermis and corium 
shortened—1, outer; 2, inner fibrous layer of the hair follicle; 3, its hyaline layer; 4, 
outer root-sheath; 5, Huxley’s layer of the inner root-sheath; 6, Henle’s layer of the 
same; p, root of the hair, with its papilla; A, arrector pili muscle; C, corium; a, sub- 
cutaneous fatty tissue; b, epidermis (horny layer); d, rete Malpighii; g, blood-vessels of 
papillse; v, lymphatics of the same; h, horny or corneous substance; i, medulla or pith; 
k, epidermis or cuticle of hair; K, coil of sweat gland, E, epidermal scales (seen from 
above and en face] from the stratum corneum; R, prickle cells from the rete Malpighii; 
n, superficial, and m, deep cells from the nail; H, hair magnified; e, cuticle; c, medulla, 
with cells; f,f, fusiform fibrous cells of the substance of the hair; x, cells of Huxley’s 
layer; /, those of Henle’s layer; S, transverse section of a sweat-gland from the axilla; 
a, smooth muscular fibres surrounding it; t, cells from a sebaceous gland, some of them 
containing granules of oil. 
Fig. 358. 
by the existence of delicate furrows on the surface visible to the naked eye. 
The corium consists of a dense network of bundles of white fibrous tissue 
mixed with a network of elastic fibres, which are more delicate in the pa- 
pillae. In silversmiths the elastic fibres are blackened by the partial deposition [Sec. 283. 
560 
STRUCTURE OF THE CUTIS VERA. 
of reduced silver, and the same obtains in those who take silver nitrate in such 
quantity as to produce argyria. The connective-tissue contains many connec- 
tive-tissue corpuscles and numerous leucocytes. The deeper connective-tissue 
layers of the corium gradually pass into the subcutaneous tissue, where 
they form a trabecular arrangement of bundles, leaving between them elongated 
rhomboidal spaces filled for the most part with groups of fat-cells (figs. 356, 
358, a, a). [In microscopic sec- 
tions, after the action of alcohol, the 
fat-cells not unfrequently contain 
crystals of margarin (fig. 295).] 
The long axis of the rhomb corre- 
sponds to the greater tension of the 
skin at that part (C. Longer). In 
some situations the subcutaneous 
tissue is devoid of fat [penis, eye- 
lids]. In many situations, the skin 
is fixed by solid fibrous bands to 
subjacent structures, as fasciae, liga- 
ments or bones (tenacula cutis); 
in other parts, as over bony promi- 
nences, bursse partially lined with endothelium and filled with synovia-like 
fluid, occur. 
Smooth muscular fibres occur in the corium in certain situations on 
extensor surfaces (Neumann); nipple, areola mammae, prepuce, perinaeum, and 
in special abundance in the tunica dartos of the scrotum. 
[Guanin in the Skin.—The skin of many amphibians and reptiles contain brown or black 
pigment-granules, and other granules of a white, silvery, or chalky appearance. Ewald and 
Krukenberg have shown that the latter consist of guanin, and that this substance is very widely 
diffused in the skin of fishes, amphibians, and reptiles. Test: Select a piece of skin from the 
belly of a frog; place it in a porcelain capsule as for the murexide test; add concentrated nitric 
acid, and heat to dryness, when a yellow residue is obtained; on adding a drop of caustic soda 
a red color is struck. The yellow residue gives no reaction with ammonia. If to the fluid more 
water be added, and it be then heated, distributed over the surface of the capsule, and cooled by 
blowing upon it, various shades of purple and violet are obtained.] 
The nails (specific gravity 1.19) consist of numerous layers of solid, horny, 
homogeneous, epidermal, or nail-cells, which may be isolated with a solution of 
caustic alkali, when they swell up and exhibit the remains of an elongated 
nucleus (fig. 358, n, m). The whole under-surface of the nail rests upon the 
nail-bed ; the lateral and posterior edges lie in a deep grove, the nail-groove 
(fig. 360, e). The corium under the nail is covered throughout its entire 
extent by longitudinal rows of ridges (fig. 360, d). Above this there lies, as 
in the skin, many layers of prickle cells like those in the rete Malpighii (fig. 
358, d), and above this again is the substance of the nail (fig. 360, a). [The 
stratum granulosum is rudimentary in the nail-bed. The substance of the nail 
represents the stratum lucidum, there being no stratum corneum (Klein).] The 
posterior part of the nail-groove and the half moon, brighter part or lunule, 
form the root of the nail. They are, at the same time, the matrix from which 
growth of the nail takes place. The lunule is present in an isolated nail, and is 
due to diminished transparency of the posterior part of the nail, owing to the 
special thickness and uniform distribution of the cells of the rete Malpighii 
(Toldt). 
Growth of the Nail.—According to Unna, the matrix extends to the front part of the 
lunule. The nail grows continually from behind forwards, and is formed by layers secreted or 
formed by the matrix. These layers run parallel to the surface of the matrix. They run 
obliquely from above and behind, downwards and forwards, through the thickness of the sub- 
Fig. 359- 
Papillae of the skin, epidermis removed, blood- 
vessels injected; some contain a Wagner’s touch- 
corpuscle, a, the others a capillary loop. Sec. 283.] 
NAILS AND HAIR. 
stance of the nail. The nail is of the same thickness from the anterior margin of the lunule 
forwards to its free margin. Thus the nail does not grow in thickness in this region. In the 
course of a year the fingers produce about 2 grms. of nail substance, and relatively more in 
summer than in winter. 
Development.—1. From the second to the eighth month of foetal life, the position of the 
nail is indicated by a partial but marked horny condition of the epidermis on the back of the 
first phalanx, the “ eponychium.” The remainder of this substance is represented during 
life by the normally formed epidermal layer, which separates the future nail from the surface of 
the furrow. 2. The future nail is formed under the eponychium, with its first nail-cells still in 
front of the nail-groove; then the nail grows and pushes forward towards the groove. At the 
seventh month, the nail (itself covered by the eponychium) covers the whole extent of the nail- 
bed. 3. When, at a later period, the eponychium splits off, the nail is uncovered. After birth 
the ridges are formed on the bed of the nail, while simultaneously the matrix passes backwards 
to the most posterior part of the groove ( Unna). 
Absence of Hairs.—The whole of the skin, with the exception of the palmar surface of 
the hand, sole of the foot, dorsal surface of the third phalanx of the fingers and toes, outer 
surface of the eyelids, glans penis, inner surface of the prepuce, and part of the labia, is covered 
with hairs, which may be strong or fine (lanugo). 
A Hair (specific gravity 1.26) is fixed by its lower extremity (root) in a 
depression of the skin or a hair-follicle (fig. 358, I,/) which passes obliquely 
through the thickness of tht 
skin, sometimes as far as th< 
subcutaneous tissue. Tin 
structure of a hair-follicle i: 
the following: — 1. Tht 
outer fibrous layer (figs 
358, 1, 357)? composed o 
interwoven bundles of con 
nective-tissue, arranged fo: 
the most part longitudinally 
and provided with numerou: 
blood-vessels and nerves. [I 
is just the connective-tissut 
of the surrounding corium] 
2. The inner fibrous layei 
(figs. 358, 2, 361) consist: 
of a layer of fusiform cell; 
(? smooth muscular fibres) 
arranged circularly. [It doe: 
not extend throughout tin 
whole length of the follicle], 
3. Inside this layer is a transparent, hyaline, glass-like basement membrane 
(fig. 358, 3, 361), which ends at the neck of the hair-follicle; while above it 
is continued as the basement membrane which exists between the epidermis 
and corium (?). In addition to these coverings, a hair-follicle has epithelial 
coverings which must be regarded in relation to the layers of the epidermis. 
Immediately within the glass-like membrane is the outer root-sheath (figs. 
358, 4, 361, 362), which consists of so many layers of epithelial cells that it 
forms a conspicuous covering. It is, in fact, a direct continuation of the 
stratum Malpighii, and consists of many layers of soft cells, the cells of the 
outer layer being cylindrical. Towards the base of the hair-follicle it becomes 
narrower, and is united to, and continuous with, the cells of the root of the hair 
itself, at least in fully developed hairs. The horny layer of the epidermis con- 
tinues to retain its properties as far down as the orifice of the sebaceous follicle ; 
below this point, however, it is continued as the inner root-sheath. This 
consists of (1) a single layer of elongated, flat, homogeneous, non-nucleated 
cells (figs. 358, 6, 361, f—Henle's layer) placed next and within the outer 
Fig. 360. 
Transverse section of one-half of a nail, a, nail-substance; 
b, more open layer of cells of the nail-bed; c, stratum 
Malpighii of the nail-bed ; d, transversely divided ridges; 
e, nail-groove; f, horny layer of e projecting over the 
nail; g, papilla; of the skin on the back of the finger. HAIR-FOLLICLES. 
[Sec. 283. 
root-sheath. Within this lies (2) Huxley's layer (figs. 358, 5, 361, g), con- 
sisting of nucleated elongated polygonal cells (fig. 358, x, and 3), while the 
cuticle of the hair-follicle is composed of cells analogous to those of the sur- 
face of the hair itself. Towards the bulb of the hair these three layers become 
fused together. 
[Coverings of a hair-follicle arranged from without inwards— 
(a) Longitudinally arranged fibrous tissue. 
(b) Circularly arranged spindle cells. 
i. Fibrous layers, 
2. Glass-like [hyaline) membrane. 
3. Epithelial layers. 
(a) Outer root-sheath. 
(b) Inner root-sheath. 
(c) Cuticle of the hair. 
Henle’s layer. 
Huxley’s layer. 
4. The hair itself.] 
The arrector pili muscle (fig. 358, A) is a fan-like arrangement of a layer 
of smooth muscular fibres, attached below to the side of a hair-follicle and 
extending towards the surface of the corium ; as 
it stretches obliquely upwards, it subtends the 
obtuse angle formed by the hair-follicle and the 
surface of the skin, [or, in other words, it forms 
an acute angle with the hair-follicle, and between 
it and the follicle lies the sebaceous gland]. 
When these muscles contract, they raise and erect 
the hair-follicles, producing the condition of 
cutis anserina or gooseskin. As the sebaceous 
gland lies in the angle between the muscle and the 
hair-follicle, contraction of the muscle compresses 
the gland and favors the evacuation of the seba- 
ceous secretion. It also compresses the blood- 
vessels of the papilla (Unna). 
The hair with its large bulbous extremity— 
hair-bulb—sits upon, or rather embraces, the 
papilla. It consists of (i) the marrow or 
medulla (fig. 358, i), which is absent in woolly 
hair and in the hairs formed during the first year 
of life. It is composed of two or three rows of 
cubical cells (H, c). (2) Outside this lies the 
thicker cortex which consists of elongated, 
rigid, horny, fibrous cells (H, f, f'), while in and 
between these cells lie the pigment granules of the 
hair. (3) The surface of the hair is covered with 
a cuticle (k), which consists of imbricated layers 
of non-nucleated squames. 
[Nerves.—Numerous nerve-fibres are distributed in the 
hair-follicles (g 424.] 
Gray Hair.—When the hair becomes gray, as in old age, this is due to defective formation of 
pigment in the cortical part. The silvery appearance of white hair is increased when small 
air-cavities are developed, especially in the medulla, and to a less extent in the cortex, where 
they reflect the light. Landois records a case of the hair becoming suddenly gray, in a man 
whose hair became gray during a single night, in the course of an attack of delirium tremens. 
Numerous air-spaces were found throughout the entire marrow of the (blond) hairs, while the 
hair-pigment still remained. 
[Blood-Pigment in Hairs.—The feelers of albino rabbits contain blood-pigment in some 
part of their substance (Sig. Mayer).~\ 
Development of Hair.—According to Kdlliker, from the 12th to 13th week of intra uterine 
life, solid finger-like processes of the epidermis are pushed down into the corium. The process 
becomes flask-shaped, while the central cells of the cylinder become elongated, and form a 
Transverse section of a hair and its 
follicle, a, outer fibrous coat, 
with b, blood-vessels; c, inner 
circularly disposed layer; d, 
glass-like layer; e, outer, f, g, 
inner, root-sheath; f, outer layer 
of the same (Henle’s sheath); 
g, inner layer of the same (Hux- 
ley’s sheath); h, cuticle; /, hair. 
Fig. 361. Sec. 283.] 
DEVELOPMENT OF HAIR. 
563 
conical body, arising as it were from the depth of the recess. It soon differentiates into an inner 
darker part, which becomes the hair, and a thinner, clearer layer covering the former, the inner 
root-sheath. The outer cells, i. e., those lying next the wall of the sac, form the outer root- 
sheath. Outside this again the fibrous tissue of the corium forms a rudimentary hair-follicle, 
while one of the papilke grows up against it, indents it, and becomes embraced by the bulb of 
the hair. This is the hair papilla, which contains a loop of blood-vessels. The cells of the 
bulb of the hair proliferate rapidly, and thus the hair 
grows in length. The point of the hair is thereby gradu- 
ally pushed upwards, pierces the inner root-sheath, and 
passes obliquely through the epidermis. The hairs appear 
upon the forehead at the 19th week; at the 23d to 25th 
week the lanugo hairs appear free, and they have a 
characteristic arrangement on different parts of the body. 
Physical Properties.—Hair has very considerable 
elasticity (stretching to 0.33 of its length), considerable 
cohesion (carrying 3 to 5 lbs.), resists putrefaction for 
a long time, and is highly hygroscopic. The last property 
is also possessed by epidermal scales, as is proved by the 
pains that occur in old wounds and scars during damp 
weather. 
Growth of a hair occurs by proliferation of the cells 
Section of a hair-follicle while a hair 
is being shed, a, outer and middle 
sheaths of hair-follicle ; b, hyaline 
membrane ; c, papilla, with a capil- 
lary ; d, outer, <?, inner root-sheath ; 
f, cuticle of the latter; cuticle of 
the hair; h, young non-medullated 
hair; i, tip of new hair; /, hair- 
knob of the shed hair, with k, the 
remainder of the cast-off outer root- 
sheath. 
Fig. 362. 
Fig. 363- 
Sebaceous gland, with a lanugo hair. 
a, granular epithelium; b, rete Mal- 
pighii continuous with a; c, fatty 
cells and free fat; d, acini; e, hair- 
follicle, with a small hair,f 
on the surface of the hair papilla, these cells representing the matrix of the hair. Layer after 
layer is formed, and gradually the hair is raised higher within its follicle. 
Change of the Hair.—According to one view, when the hair has reached its full length, the 
process of formation on the surface of the hair papilla is interrupted; the root of the hair is 
raised from the papilla, becomes horny, remains almost devoid of pigment, and is gradually 
more and more lifted upwards from the surface of the papilla, while its lower bulbous end 564 
THE GLANDS OF THE SKIN. 
[Sec. 283. 
becomes split up like a brush. The lower empty part of the hair-follicle becomes smaller, while 
on the old papilla a new formation of a hair begins, the old hair at the same time falling out 
(Unna). According to Stieda, the old papilla disappears, while a new one is formed in the 
hair-follicle, and from it the new hair is developed. According to Kolliker, again, both pro- 
cesses obtain. 
[Erectile Hairs.—The vibrissse or feelers in the snout of some animals are really organs of 
touch, and in each hair-follicle is a large blood-sinus.] 
[Chemistry.—In the horny epithelium the protoplasm is replaced by keratin, which belongs 
to the group of the albuminoids (§ 250, 3) and contains sulphur, which is but loosely combined, 
for on boiling hairs with alkalies the sulphur is liberated. It is also the chief constituent of 
hairs, hoof, and feathers, while a similar body, neuro-keratin, is found in nervous structures. 
The quantity of sulphur in keratin is about 3-5 per cent. Hairs on being burned yield 5-70 per 
1000 of ash, composed of 250 alkaline sulphates, 140 calcium sulphate, 100 iron oxide, and 400 
parts of silicic acid. As a rule, dark hairs yield more iron than blond hairs.] 
[The color of the skin in the colored races, and the black or brown color of hair in general, is 
due to melanin (p. 484). There seem to be several varieties of this pigment, but that of 
human hair contains rather less nitrogen and more sulphur than some of the others. It does not 
contain iron.] 
284. THE GLANDS OF THE SKIN.—The sebaceous glands (fig. 
358, x, T) are simple acinous glands, which open by a duct into the hair- 
follicles of large hairs near their upper part; in the case of small hairs, the 
latter may project from the duct of the gland (fig. 363). In some situations 
the ducts of the glands open free upon the surface, e.g., the glands of labia 
minora, glans, prepuce (Tyson’s glands), and the red margins of the lips. The 
largest glands occur in the nose and in the labia; they are absent only 
from the vola manus and planta pedis. The oblong alveoli of the gland 
consist of a basement membrane lined with small polyhedral nucleated granular 
secretory cells (fig. 358, /). Within this are other polyhedral cells, whose 
substance contains numerous oil-globules; the cells become more fatty towards 
the centre of the alveolus. The cells lining the duct are continuous with 
those of the outer root-sheath. The detritus formed by the fatty metamorphosis 
of the cells constitutes the sebum or sebaceous secretion. 
[If the “oil or coccygeal gland” of a duck be removed, it is found that, when the animal is 
submerged, it takes up between its feathers about the same amount of water as an intact duct; 
but it retains 2 to times as much water in its feathers (Max Joseph).] 
The sweat-glands (figs. 356, 358, I, k), sometimes called sudoriparous 
glands, consist of a long blind tube, whose lower end is arranged in the form 
of a coil placed in the areolar tissue under the skin, while the somewhat 
smaller upper end or excretory portion winds in a vertical, slightly wave- 
like manner, through the corium, and in a cork-screw or spiral manner 
through the epidermis, where it opens with a free, somewhat trumpet-shaped, 
mouth (fig. 356). The glands are very numerous and large in the palm of 
the hand, sole of the foot, axilla, forehead, and around the nipple; few on the 
back of the trunk; and are absent on the glans, prepuce, and margin of 
the lips. The circumanal glands and the ceruminous glands of the 
external auditory meatus, and Moll’s glands, which open into the hair-follicles 
of the eyelashes, are modifications of ihe sweat-glands. 
Each gland-tube consists of a basement membrane lined by cells; the 
excretory part or sweat-canal of the tube is lined by several layers of 
cubical cells, whose surface is covered by a delicate cuticular layer, a small 
central lumen being left. Within the coil the structure is different. The first 
part of the coil resembles the above, but as the coil is the true secretory part 
of the gland, its structure differs from the sweat-canal. This, the so-called 
distal portion of the tube, is lined by a single layer of moderately tall, clear, 
nucleated cylindrical epithelium (fig. 358, S), often containing oil-globules. 
Smooth muscular fibres are arranged longitudinally along the tube in the large 
glands (fig. 358, S, a). There is a distinct lumen present in the tube. As the Sec. 284.] 
THE FUNCTIONS OF THE SKIN. 
565 
duct passes through the epidermis, it winds its way between the epidermal cells 
without any independent membrane lining it (.Heynold). A network of capil- 
laries surrounds the coil. Before the arteries split up into capillaries, they 
form a true rete mirabile around the coil (Briicke). This is comparable to the 
glomerulus of the kidney, which may also be regarded as a rete mirabile. 
Numerous nerves pass to form a plexus, and terminate in the glands (Tomsa). 
The total number of sweat-glands is estimated by Krause at 2]/2 millions, which gives a 
secretory surface of nearly 1000 square metres. These glands secrete sweat. Nevertheless, 
an oily or fatty substance is often mixed with the sweat. In some animals (glands in the sole of 
the foot of the dog, and in birds) this oily secretion is very marked. 
Numerous lymphatics occur in the cutis; some arise by a blind end, and others from loops 
within the papilla on a plane lower than the vascular capillary. [These open into more or less 
horizontal networks of tubular lymphatics in the cutis, and these again into the wide lymphatics 
of the subcutaneous tissue, which are well provided with valves.] Special lymphatic spaces 
are disposed in relation with the hair-follicles and their glands (Neumann), [and also with 
the fat (Klein). The lymphatics of the skin are readily injected with Berlin blue by the puncture 
method], 
[The blood-vessels of the skin are arranged in several systems. There is a superficial 
system, from which proceed the capillaries for the papillae. There is a deeper system of vessels 
which supplies special blood-vessels to (a) the fatty tissue; the hair-follicles, each of which 
has a special vascular arrangement of its own, and in connection with this each sebaceous gland 
receives a special artery; (c) an artery goes also to each coil of a sweat-gland, where it forms a 
dense plexus of capillaries (Tomsa).'] 
285. THE SKIN AS A PROTECTIVE COVERING.—The sub- 
cutaneous fatty tissue fills up the depressions between adjoining parts of 
the body and covers projecting parts, so that a more rounded appearance of 
the body is thereby obtained. It also acts as a soft elastic pad and protects 
delicate parts from external pressure (sole of the foot, palm of the hand), and 
it often surrounds and protects blood-vessels, nerves, etc. It is a bad conduc- 
tor of heat, and thus acts as one of the factors regulating the radiation of heat 
(§ 2x4, II, 4), and, therefore, the temperature of the body. The epidermis 
and cutis vera also act in the same manner (§ 212). Klug found that the heat- 
conduction is less through the skin and subcutaneous fatty tissue than through 
the skin alone ; the epidermis conducts heat less easily than the fat and the 
corium. 
The solid, elastic, easily movable cutis affords a good protection against 
external, mechanical injuries; while the dry, impermeable, horny epidermis, 
devoid of nerves and blood-vessels, affords a further protection against the 
absorption of poisons, and at the same time it is capable of resisting, to a cer- 
tain degree, thermal and even chemical actions. A thin layer of fatty matter 
protects the free surface of the epidermis from the macerating action of fluids, 
and from the disintegrating action of the air. The epidermis is important in 
connection with the fluids of the body. It exerts pressure upon the cutaneous 
capillaries, and to a limited extent, prevents too great diffusion of fluid from 
the cutaneous vessels. Parts of the skin devoid of epidermis are red and 
always moist. When dry, the epidermis and the epidermal appendages are bad 
conductors of electricity (§ 326). Lastly, the existence of uninjured epidermis 
prevents adjoining parts from growing together. 
As the epidermis is but slightly extensile it is stretched over the folds and papillae of the cutis 
vera, which becomes level when the skin is stretched, and the papillae may even disappear with 
strong tension (Lewinski). 
286. CUTANEOUS RESPIRATION: SEBUM—SWEAT.— 
The skin, with a surface of more than i*4 square metre, has the following 
secretory functions: — 
1. The respiratory excretion ; 
2. The secretion of sebaceous matter; and 
3. The secretion of sweat. 566 
THE SEBACEOUS SECRETION. 
[Sec. 286. 
[Besides this the skin is protective, contains sense-organs, is largely 
concerned in regulating the temperature, and may be concerned in 
absorption.] 
1. Respiration by the skin has been referred to (§ 130). The organs concerned are the 
tubes of the sweat-glands, moistened as they are with fluids, and surrounded by a rich network 
of capillaries. It is uncertain whether or not the skin gives off a small amount of N or ammonia. 
Rohrig made experiments upon an arm placed in an air-tight metal box. According to him, 
the amount of C02 and H20 excreted is subject to certain daily variations; it is increased by 
digestion, increased temperature of the surroundings, the application of cutaneous stimuli, and 
by impeding the pulmonary respiration. The exchange of gases also depends upon the vascu- 
larity of certain parts of the skin, while the cutaneous absorption of O also depends upon the 
number of colored corpuscles in the blood. 
In frogs and other amphibians, with a thin, always moist epidermis, the cutaneous respira- 
tion is more considerable than in warm-blooded animals. In winter, in frogs, the skin alone 
yields y of the total amount of C02 excreted ; in summer % of the same (Bidder); thus, in 
these animals it is a more important respiratory organ than the lungs themselves. 
Suppression of the cutaneous activity by varnishing or dipping the skin in oil causes 
death by asphyxia (frogs) sooner than ligature of the lungs does. Varnishing the Skin.— 
When the skin of a warm-blooded animal is covered with an impermeable varnish [such as gel- 
atin] {Foucault, Becquerel, Brechet), death occurs after a time, probably owing to the loss of 
too much heat. The formation of crystalline ammonio-magnesic phosphate in the cutaneous 
tissue of such animals (Edenhuizen) is not sufficient to account for death, nor are congestion of 
internal organs and serous effusions satisfactory explanations. The retention of the volatile sub- 
stances (acids) present in the sweat is not sufficient. Strong animals live longer than feeble 
ones; horses die after several days (Ge?-lack); they shiver and lose flesh. The larger the 
cutaneous surface left unvarnished, the later does death take place. Rabbits die when y of 
their surface is varnished. When the entire surface of the animal is varnished, the temperature 
rapidly falls (to 190), the pulse and respirations vary; usually they fall when the varnishing pro- 
cess is limited; increased frequency of respiration has been observed (§ 225). Pigs, dogs, 
horses, when one-half of the body is varnished, exhibit only a temporary fall of the temperature 
and show signs of weakness, but do not die (Ellenberger and Hofmeister'). [In extensive 
burns of the skin, not only is there disintegration of the colored blood-corpuscles (v. Lesser), 
but in some cases ulcers occur in the duodenum. The cause of the ulceration, however, has not 
been ascertained satisfactorily (Curling).~\ 
2. Sebaceous Secretion.—The fatty matter, as it is excreted from the 
acini of the sebaceous glands, is fluid, but even within the excretory duct of the 
gland it stagnates and forms a white fat-like mass, which may sometimes be 
expressed (at the side of the nose) as a worm-like white body, the so-called 
comedo. The sebaceous matter keeps the skin supple, and prevents the hair 
from becoming too dry. Microscopically, the secretion is seen to contain 
innumerable fatty granules, a few gland-cells filled with fat, visible after the 
addition of caustic soda, crystals of cholesterin, and in some men a micro- 
scopic mite-like animal (Demodex folliculorum). 
[Formation of Sebum.—The cells lining the acini of the glands proliferate and push the 
older cells towards the centre of the alveoli, where they undergo a fatty transformation to form 
the sebum. Thus the shed cells are themselves bodily transformed into sebaceous matter, a 
condition different to that obtaining in most of the other secretory glands.] 
Chemical Composition of Sebum.—The constituents are for the most part fatty; chiefly 
olein (fluid) and palniitin (solid) fat, soaps, and some cholesterin ; a small amount of albumin 
and unknown extractives. Amongst the inorganic constituents, the insoluble earthy phosphates 
are most abundant; while the alkaline chlorides and phosphates are less abundant. 
The vernix caseosa, which covers the skin of a new-born child, is a greasy mixture of 
sebaceous matter and macerated epidermal cells (containing 47.5 per cent. fat). A similar 
product is the smegma praeputialis (52.8 per cent, fat), in which an ammonia soap is present. 
The cerumen or ear-wax is a mixture of the secretions of the ceruminous glands of the ear 
(similar in structure to the sweat-glands) and the sebaceous glands of the auditory canal. 
Besides the constituents of sebum, it contains yellow or brownish particles, a bitter yellow 
extractive substance derived from the ceruminous glands, potash soaps, and a special fat. The 
secretion of the Meibomian glands is sebum. 
[Lanoline.—Liebreich finds in feathers, hairs, wool, and keratin-tissues generally, a choles- 
terin fat, which, however, is not a true fat, although it saponifies, but an ethereal compound of Sec. 286.] 
SWEAT AND ITS COMPOSITION. 
567 
certain fatty acids with cholesterin. In commerce it is obtained from wool, and is known by 
the above name ; it forms an admirable basis for ointments, and it is very readily absorbed by 
the skin.] Thus, the fat-like substance for protecting the epidermis is partly formed along 
with keratin in the epidermis itself. 
3. The Sweat.—The sweat is secreted in the coil of the sweat-glands. At 
the same time the nuclei of the secretory cells become more spherical and the 
cells (horse) become more granular. As long as the secretion is small in 
amount, the water secreted is evaporated at once from the skin along with the 
volatile constituents of sweat; as soon, however, as the secretion is increased, 
or evaporation is prevented, drops of sweat appear on the surface of the skin. 
The former is called insensible perspiration, and the latter sensible per- 
spiration. [Broadly, the quantity is about 2 lbs. in twenty-four hours.] 
The sensible perspiration varies greatly; as a rule, the right side of the body perspires more 
freely than the left. The palms of the hands secrete most, then follow the soles of the feet, 
cheek, breast, upper arm, and fore-arm (Peiper). It falls from morning to mid-day, and rises 
again towards evening, reaching its maximum before midnight. Much moisture and cold in 
the surrounding atmosphere diminish it, and so does diuresis. In children, the insensible 
perspiration is relatively great. The drinking of water favors it, alcohol diminishes it (//. 
Schmid). 
Method.—Sweat is obtained from a man by placing him in a metallic vessel in a warm bath; 
the sweat is rapidly secreted and collected in the vessel. In this way Favre collected 2560 
grams of sweat in iy£ hour [by exposing himself to a hot-air bath and drinking at the same time 
hot drinks]. An arm may be inclosed in a cylindrical vessel, which is fixed air-tight round the 
arm with an elastic bandage (Schottin). 
Amongst animals, the horse sweats, so does the ox, but to a less extent; the vola and planta 
of apes, cats, and the hedgehog secrete sweat; the snout of the pig sweats (?), while the goat, 
rabbit, rat, mouse, and dog are said not to sweat (Luchsinger). [The skin over the body and 
the pad on the dog’s foot contain numerous sweat-glands, which open free on the surface of the 
pad and into the hair-follicles on the general surface of the skin ( W. Stirling).] 
Microscopically.—The sweat contains only a few epidermal scales accidentally mixed with 
it, and fine fatty granules from the sebaceous glands. 
Chemical Composition of Sweat.—Its reaction is alkaline, although 
it frequently is acid, owing to the admixture of fatty acids from decomposed 
sebum. During profuse secretion it becomes neutral, and lastly alkaline again 
( Triimpy and Luchsinger). The sweat is colorless, slightly turbid, of a saltish 
tasle, and has a characteristic odor varying in different parts of the body; the 
odor is due to the presence of volatile fatty acids [specific gravity, 1003-1005]. 
The constituents are water, which is increased by copious draughts of that 
fluid, and solids, which amount to 1.2 per cent. (0.70 to 2.66 percent.— 
Funke), and of these 0.90 per cent, is organic and 0.30 inorganic. Amongst 
the organic constituents are neutral fats (palmitin, stearin), also present in 
the sweat of the palm of the hand, which contains no sebaceous glands, choles- 
terin, volatile fatty acids (chiefly formic, acetic, butyric, propionic, caproic, 
capric acids), varying qualitatively and quantitatively in different parts of the 
body. These acids are most abundant in the sweat first (acid) secreted. There 
are also traces ofproteids (similar to casein) and a trace of albumin and urea, 
about 0.1 per cent. [Kast found sulphuric acid united as ethereal sulphate of 
skatol and phenol, also oxy-acids, and Capricana found kreatinin.] In uraemic 
conditions (anuria in cholera) urea has been found crystallized on the skin. 
When the secretion of sweat is greatly increased, the amount of urea in the 
urine is diminished, both in health and in uraemia (Leube). The nature of the 
reddish-yellow pigment, which is extracted from the residue of sweat by alco- 
hol, and colored green by oxalic acid, is unknown. Amongst inorganic 
constituents, those that are easily soluble are more abundant than those that 
are soluble with difficulty, in the proportion of 17 to 1 ; sodium chloride, 0.02 ; 
potassium chloride, 0.02; sulphates, 0.01 per 1000, together with traces of 
earthy phosphates and sodium phosphate. [Moreover, the relative proportion 568 
INFLUENCE OF NERVES ON SWEATING. 
[Sec. 286. 
of salts in sweat is quite different from that in urine.] Gases.—Sweat con- 
tains C02 in a state of absorption and some N. When decomposed with free 
access of air, it yields ammonia salt (Gorup-Besanez). 
Excretion of Substances.—Some substances when introduced into the body reappear in the 
■ sweat—benzoic, cinnamic, tartaric, and succinic acids are readily excreted; quinine and potassic 
iodide with more difficulty. Mercuric chloride, arsenious and arsenic acids, sodium and potas- 
sium arseniate have also been found. After taking arseniate of iron, arsenious acid has been 
found in the sweat, and iron in the urine. Mercury iodide reappears as a chloride in the sweat, 
while the iodine occurs in the saliva. 
Formation of Pigments in the Skin.—The leucocytes furnish the ma- 
terial, and the pigment is deposited in granules in the deeper layers, and, to a 
less extent, in the upper layers, of the rete Malpighii. This occurs in the folds 
around the anus, scrotum, nipple [especially during pregnancy], and every- 
where in the colored races. There is a diffuse, whitish-yellow pigment in the 
stratum corneum, which becomes darker in old age. The pigmentation de- 
pends on chemical processes, reduction taking place, and these processes are 
aided by light. Granular pigment lies also in the layers of prickle cells. The 
dark coloration of the skin may be arrested by free O [hydric peroxide], while 
the corneous change is prevented at the same time (Unna). [According to 
Delepine melanin is not derived from haemoglobin, but is formed by the deep 
layers of the epidermis.] 
Pathological.—To this belongs the formation of liver spots or cholasma, freckles, and the 
pigmentation of Addison’s disease [pigmentation round old ulcers, etc.] (\ 103, IV). [The 
curious cases of pigmentation, especially in neurotic women, e.g., in the eyelids, deserve further 
study in relation to the part played by the nervous system in this process.] 
287. INFLUENCE OF NERVES ON THE SECRETION OF 
SWEAT.—The -secretion of the skin, which averages about -fa of the body- 
weight, i. e., about double the amount of water excreted by the lungs, may be 
increased or diminished. The liability to perspire varies much in different 
individuals. The following conditions influence the secretion—1. Increased 
temperature of the surroundings causes the skin to become red, while there 
is a profuse secretion of sweat (§ 214, II, 1). Cold, as well as a temperature 
of the skin about 50° C., arrests the secretion. 2. A very watery condition 
of the blood, e.g., after copious draughts of warm water, increases the secre- 
tion. 3. Increased cardiac and vascular activity, whereby the blood-pres- 
sure within the cutaneous capillaries is increased, have a similar effect; in- 
creased sweating follows increased muscular activity. 4. Certain drugs 
favor sweating, e. g., pilocarpin, Calabar bean, strychnin, picrotoxin, muscarin, 
nicotin, camphor, ammonia compounds ; while others, as atropin and morphia, 
in large doses, diminish or paralyze the secretion. [Drugs which excite copious 
perspiration, so that it stands as beads of sweat on the skin, are called sudo- 
rifics, while those that excite the secretion gently are diaphoretics, the dif- 
ference being one of degree. Those drugs which lessen the secretion are called 
antihydrotics.] 5. It is important to notice the antagonis7n which exists, 
probably upon mechanical grounds, between the secretion of sweat, the urinary 
secretion, and the evacuation of the intestine. Thus copious secretion of urine 
(e.g., in diabetes) and watery stools coincide with dryness of the skin. If the 
secretion of sweat be increased, the percentage of salts, urea, and albumin is 
also increased, whilst the other organic substances are diminished. The more 
saturated the air is with watery vapor, the sooner does the secretion appear in 
drops upon the skin, while in dry air or air in motion, owing to the rapid evapo- 
ration, the formation of drops of sweat is prevented, or at least retarded. [The 
reciprocal relation between the skin and kidneys is well known. In sum- 
mer, when the skin is active, the kidneys separate less water ; in winter, when Sec. 287.] 
569 
COURSE OF THE SWEAT NERVES. 
the skin is less active, it is cold and comparatively bloodless, while the kidneys 
excrete more water, so that the action of these two organs is in inverse ratio.] 
The influence of nerves on the secretion of sweat is very marked. 
I. Just as in the secretion of saliva (§ 145), vaso-motor nerves are usually 
in action at the same time as the proper secretory nerves ; the vaso-dilator 
nerves (sweating with a red congested skin) are most frequently involved. 
The fact that secretion of sweat does occasionally take place when the skin is 
pale (fear, death-agony) shows that, when the vaso-motor nerves are excited, 
so as to constrict the cutaneous blood-vessels, the sweat secretory nerve-fibres 
may also be active. 
Under certain circumstances, the amount of blood in the skin seems to determine the occur- 
rence of sweating; thus, Dupuy found that section of the cervical sympathetic caused secretion 
on that side of the neck of a horse; while Nitzelnadel found that percutaneous electrical stimu- 
lation of the cervical sympathetic in man limited the sweating. 
[We may draw a parallel between the secretion of saliva and that of sweat. Both are formed 
in glands derived from the outer layer of the embryo. Both secretions are formed from lymph 
supplied by the blood stream, and if the lymph be in sufficient quantity, secretion may take 
place when there is no circulation, although in both cases secretion is most lively when the 
circulation is most active and the secretory nerves of both are excited simultaneously; both 
glands have secretory nerves distinct from the nerves of the blood-vessels; both glands may be 
paralyzed by the action of the nervous system, or in disease (fever), or conversely, both are 
paralyzed by atropine and excited by other drugs, eg., pilocarpin. In the gland-cells of both, 
histological changes accompany the secretory act, and no doubt similar electromotor phenomena 
occur in both glands.] 
II. Secretory or sweat nerves, altogether independent of the circulation, 
control the secretion of sweat. Stimulation of these nerves, even in a limb 
which has been amputated in a kitten, causes a temporary secretion of sweat, 
i.e., after complete arrest of the circulation (Goltz, Kendall and Luchsitiger, 
Ostroumoul). In the intact condition of the body, however, profuse perspira- 
tion, at all events, is always associated with simultaneous dilatation of the blood- 
vessels (just as, in stimulation of the facial nerve, an increased secretion of 
saliva is associated with an increased blood-stream—§ 145, A, I). The secre- 
tory nerves and those for the blood-vessels seem to lie in the same nerve- 
trunks. 
The secretory nerves of the hind limbs (cat) lie in the sciatic nerve. Luch- 
singer found that stimulation of the peripheral end of this nerve caused renewed 
secretion of sweat for a period of half an hour, provided the foot was always 
wiped to remove the sweat already formed. If a kitten, whose sciatic nerve is 
divided on one side, be placed in a chamber filled with heated air, all the three 
intact limbs soon begin to sweat, but the limb whose nerve is divided does not, 
nor does it do so when the veins of the limb are ligatured so as to produce con- 
gestion of its blood-vessels. [The cat sweats only on the hairless soles of the 
feet.] As to the course of the secretory fibres to the sciatic nerve, some pass 
directly from the spinal cord ( Vulpian), some pass into the abdominal sympa- 
thetic (.Luchsinger, Nawrocki, Ostroumow), through the rami communicantes 
and the anterior spinal roots from the upper lumbar and lower dorsal spinal cord 
(9th to 13th dorsal vertebrae—cat), where the sweat-centre for the lower 
limbs is situated. 
The spinal sweat-centre may be excited directly: (1) By a highly 
venous condition of the blood, as during dyspnoea, e.g., the secretion of sweat 
that sometimes precedes death; (2) by overheated blood (450 C.) streaming 
through the centre; (3) by certain drugs (see p. 568). The centre maybe 
also excited reflexly, although the results are variable, e.g., stimulation of the 
crural and peroneal nerves, as well as the central end of the opposite sciatic 
nerve excites it. [The pungency of mustard in the mouth may excite free 
perspiration on the face.] [Sec. 287. 
570 
MORBID SWEATING. 
Anterior Extremity.—The secretory fibres lie in the ulnar and median 
nerves, for the fore-limbs of a cat; most of them, or indeed all of them 
(.Nawrocki), pass into the thoracic sympathetic (Ggl. stellatum), and part (?) 
run in the nerve-roots direct from the spinal cord (Luchsinger, Vulpian, Ott'). 
A similar sweat-centre for the upper limbs lies in the lower part of the cer- 
vical spinal cord. Stimulation of the central ends of the brachial plexus causes 
a reflex secretion of sweat upon the foot of the other side (.Adamkiewicz). At 
the same time the hind feet also perspire. 
Pathological.—Degeneration of the motor ganglia of the anterior horns of the spinal cord 
causes loss of the secretion of sweat, in addition to paralysis of the voluntary muscles of the 
trunk. The perspiration is increased in paralyzed as well as in oedematous limbs. In nephritis 
there are great variations in the amount of water given off by the skin. 
Head.—The secretory fibres for this part (horse, man, snout of pig) lie in 
the thoracic sympathetic, pass into the ganglion stellatum, and ascend in the 
cervical sympathetic (§ 356, A.). Percutaneous electrical stimulation of the 
cervical sympathetic in man causes sweating of that side of the face and of the 
arm (Af. Meyer). In the cephalic portion of the sympathetic, some of the 
fibres pass into, or become applied to, the branches of the trigeminus, which 
explains why stimulation of the infraorbital nerve causes secretion of sweat. 
Some fibres, however, arise directly from the roots of the trigeminus (Luch- 
singer•), and the facial ( Vulpian, Adamkiewicz). 
Undoubtedly the cerebrum has a direct effect either upon the vaso-motor 
nerves (p. 569, I) or upon the sweat-secretory fibres (II), as in the sweating 
produced by psychical excitement (pain, fear, etc.). 
Adamkiewicz and Senator found that, in a man suffering from abscess of the motor region of 
the cortex cerebri for the arm, there were spasms and perspiration in the arm. 
Sweat-centre.—According to Adamkiewicz, the medulla oblongata contains 
the dominating sweat-centre (§ 373). When this centre is stimulated in a 
cat, all the four feet sweat, even three-quarters of an hour after death (Adam- 
kiewicz). 
III. The nerve-fibres which terminate in the s7nooth muscular fibres of the 
sweat-glands act upon the excretion of the secretion. 
Other Conditions.—If the sweat-nerves be divided (cat), injection of pilocarpin causes a secre- 
tion of sweat, even at the end of three days. After a longer period than six days there may 
be no secretion at all. This observation coincides with the phenomenon of dryness of the skin 
in paralyzed limbs. Dieffenbach found that transplanted portions of skin first began to sweat 
when their sensibility was restored. 
Experiments on man.—If a motor nerve (tibial, median, facial) of a man be stimulated, sweat 
appears on the skin over the muscular area supplied by the nerve, and also upon the correspond- 
ing area of the opposite non-stimulated side of the body. This result occurs when the circula- 
tion is arrested as well as when it is active. Sensory and thermal stimulation of the skin always 
cause a bilateral reflex secretion independently of the circulation. The area of sweating is inde- 
pendent of the part of the skin stimulated. 
[Changes in the Cells during Secretion.—In the resting glands of the horse, the cylindri- 
cal cells are clear with the nucleus near their attached ends, but after free perspiration they 
become granular, and their nucleus is more central (Renaut).] 
288. PATHOLOGICAL VARIATIONS.—1. Anidrosis or diminution of the secre- 
tion of sweat occurs in diabetes and the cancerous cachexia, and along with other disturbances 
of nutrition of the skin in some nervous diseases, e.g., in dementia paralytica; in some limited 
regions of the skin, it has occurred in certain tropho-neuroses, e.g., in unilateral atrophy of the 
face and in paralyzed parts. In many of these cases it depends upon paralysis of the correspond- 
ing nerves or their spinal sweat-cenlres. 
2. Hyperidrosis, or increase of the secretion of sweat, occurs in easily excitable persons, in 
consequence of the irritation of the nerves concerned (§ 287), e.g., the sweating which occurs in 
debilitated conditions and in the hysterical (sometimes on the head and hands), and the so- 
called epileptoid sweats (Eulenbnrg). Sometimes the increase is confined to one side of the head 
(H. unilateralis). This condition is often accompanied with other nervous phenomena, partly Sec. 288.] 
CUTANEOUS ABSORPTION. 
571 
with the symptoms of paralysis of the cervical sympathetic (redness of the face, narrow pupil), 
partly with symptoms of stimulation of the sympathetic (dilated pupil, exophthalmos). It’may 
occur without these phenomena, and is due perhaps to stimulation of the proper secretory fibres 
alone. [Increased sweating is very marked in certain fevers, both during their course and at 
the crisis in some; while the sweat is not only copious but acid in acute rheumatism. The 
“ night-sweats” of phthisis are very marked and disagreeable.] 
3. Paridrosis or qualitative changes in the secretion of sweat, e.g., the rare case of “ sweat- 
ing of blood" (haematohidrosis), is sometimes unilateral. According to Hebra, in some cases 
this condition represents a vicarious form of menstruation. It is, however, usually one of many 
phenomena of nervous affections. Bloody sweat sometimes occurs in yellow fever. Bile- 
pigments have been found in the sweat in jaundice; blue sweat from indigo (Bizio), from 
pyocyanin (the rare blue coloring-matter of pus), or from phosphate of the oxide of iron (Osc. 
Kollmann) is extremely rare. Such colored sweats are called chromidroses. Numerous micro- 
organisms (which, however, are innocuous) live between the epidermal scales and on the hairs, 
two varieties of Saccharomycetes; in cutaneous folds Leptothrix epidermalis, various Schizo- 
mycetes, and five kinds of Micrococci; and between the toes—Bacterium graveolens (Bordoni- 
Uffreduzzi), which causes th§ odor of the sweat of the feet. Micro-organisms are also the 
cause of yellow, blue, and red sweat; the last are due to Micrococcus hsematodes. 
Grape-sugar occurs in the sweat in diabetes mellitus; uric acid and cystin very rarely; and 
in the sweat of stinking feet, leucin, tyrosin, valerianic acid, and ammonia. Stinking sweat 
(bromidrosis) is due to the decomposition of the sweat, from the presence of a special micro- 
organism (Bacterium fcetidum—Thin). In the sweating stage of ague butyrate of lime has been 
found, while in the sticky sweat of acute articular rheumatism there is more albumin (Anselmino), 
and the same is the case in artificial sweating (Leube); lactic acid is present in the sweat in 
puerperal fever. 
The sebaceous secretion is sometimes increased, constituting seborrhcea, which may be local 
or general. It may be diminished (Asteatosis cutis). The sebaceous glands degenerate in 
old people, and hence the glancing of the skin (Rimy). If the ducts of the glands are occluded 
the sebum accumulates. Sometimes the duct is occluded by black particles or ultramarine (Unna) 
from the blue used in coloring the linen. When pressed nut, the fatty worm-shaped secretion 
is called “ comedo.” 
289. CUTANEOUS ABSORPTION—GALVANIC CONDUCTION.—After long 
immersion in water the superficial layers of the epidermis become moist and swell up. The skin 
is unable to absorb any substances, either salts or vegetable poisons, from watery solutions of 
these. This is due to the fat normally present on the epidermis and in the pores of the skin. If 
the fat be removed from the skin by alcohol, ether, or chloroform, absorption may occur in a few 
minutes (Parisot). According to Rohrig, all volatile substances, e.g., carbolic acid and others, 
which act upon and corrode the epidermis, are capable of absorption; while according to Juhl, 
such watery solutions as impinge on the skin, in a finely divided spray, are also capable of 
absorption, which very probably takes place through the interstices of the epidermis. 
[Inunction.—When ointments are rubbed into the skin so as to press the substance into the 
pores, absorption occurs, e.g., potassium iodide in an ointment so rubbed in is absorbed, so is 
mercurial ointment. V. Voit found globules of mercury between the layers of the epidermis, 
and even in the corium of a person who was executed, into whose skin mercurial ointment had 
been previously rubbed. The mercury globules, in cases of mercurial inunction, pass into the 
hair-follicles and ducts of the glands, where they are affected by the secretion of the glands and 
transformed into a compound capable of absorption. An abraded or inflamed surface (e.g., after 
a blister) where the epidermis is removed, absorbs very rapidly, just like the surface of a wound 
(Endermic method).] 
[Drugs may be applied locally where the epidermis is intact—epidermic method—as when 
drugs which affect the sensory nerves of a part are painted over a painful area to diminish the 
pain. Another method, the hypodermic, now largely used, is that of injecting, by means of a 
hypodermic syringe a non-corrosive, non-irritant drug, in solution, into the subcutaneous 
tissue, where it practically passes into the lymph-spaces and comes into direct relation with the 
lymph- and blood-stream; absorption takes place with great rapidity, even more so than from 
the stomach.] 
Absorption of Gases.—Under normal conditions minute traces of O are absorbed from the 
air; hydrocyanic acid, sulphuretted hydrogen—CO, C02, the vapor of chloroform and ether may 
be absorbed (Chaussier, Gerlach, Rohrig). In a bath containing sulphuretted hydrogen, this gas 
is absorbed, while C02 is given off into the water (Rohrig). 
Absorption of watery solutions takes place rapidly through the skin of the frog (Gutt- 
mann, W. Stirling, v. Wittich). Even after the circulation is excluded and the central nervous 
system destroyed, much water is absorbed through the.skin of the frog, but not to such an extent 
as when the circulation is intact (Spina). 
Galvanic Conduction through the Skin.—If the two electrodes of a cotistant current be COMPARATIVE AND HISTORICAL ON SKIN. 
[Sec. 289. 
572 
impregnated with a watery solution of certain substances and applied to the skin, and if the 
direction of the current be changed from time to time, strychnin may be caused to pass through 
the skin of a rabbit in a few minutes, and that in sufficient amount to kill the animal (H. Munk). 
In man, quinine and potassium iodide have been introduced into the body in this way, and their 
presence detected in the urine. This process is called the cataphoric action of the constant 
current (§ 328). 
290. COMPARATIVE—HISTORICAL.—In all vertebrates the skin consists of corium 
and epidermis. In some reptiles the epidermis becomes horny, and forms large plates or scales. 
Similar structures occur in the edentata among mammals. The epidermal appendages assume 
various forms—such as hair, nail, spines, bristles, feathers, claws, hoof, horns, spurs, etc. The 
scales of some fishes are partly osseous structures. Many glands occur in the skin; in some 
amphibia they secrete mucus, in others the secretion is poisonous. Snakes and tortoises are 
devoid of cutaneous glands; in lizards the “ leg-glands ” extend from the anus to the bend of 
the knee. In the crocodile, the glands open under the margins of the cutaneo-osseous scales. 
In birds the cutaneous glands are absent; the “ coccygeal glands ” form an oily secretion for 
lubricating the feathers. [This is denied by O. Liebreich, as he finds no cholesterin-fats in their 
secretion.] The civet glands, at the anus of the civet cat, the preputial glands of the musk 
deer, the glands of the hare, and the pedal glands of ruminants, are really greatly developed 
sebaceous glands. In some invertebrata, the skin, consisting of epidermis and corium, is 
intimately united with the subjacent muscles, forming a musculo cutaneous tube for the body 
of the animal. The cephalopoda have chromatophores in their skin, i. e., round or irregular 
spaces filled with colored granules. Muscular fibres are arranged radially around these spaces, 
so that when these muscles contract the colored surface is increased. The change of color in 
these animals is due to the play or contraction of these muscles (Brilcke). Special glands are 
concerned in the production of the shell of the snail. The annulosa are covered with a chitin- 
ous investment, which is continued for a certain distance along the digestive tract and the 
tracheae. It is thrown off when the animal sheds its covering. It not only protects the animal, 
but it forms a structure for the attachment of muscles. In echinodermata, the cutaneous cover- 
ing contains calcareous masses; in the holothurians, the calcareous structures assume the form of 
calcareous spicules. 
Historical.—Hippocrates (born 460 B. c.) and Theophrastus (born 371 b. c.) distinguished 
the perspiration from the sweat; and, according to the latter, the secretion of sweat stands in a 
certain antagonistic relation to the urinary secretion and to the water in the faeces. According 
to Cassius Felix (97 A. D.), a person placed in a bath absorbs water through the skin; Sanctorius 
(1614) measured the amount of sweat given off; Alberti (1581) was acquainted with the hair- 
bulb; Donatus (1588) described hair becoming gray suddenly; Riolan (1626) showed that the 
color of the skin of the negro was due to the epidermis. Physiology of the Motor Apparatus. 
291. [CILIARY MOTION—PIGMENT CELLS.—(V) Muscular 
Movement.—By far the greatest number of movements occurring in our 
bodies is accomplished through the agency of muscular fibre, which, when 
it is excited by a stimulus, contracts, i. e., it forcibly shortens, and thus brings 
its two ends nearer together, while it bulges to a corresponding extent laterally. 
In muscle the contraction takes place in a definite direction.] 
Amoeboid Movement.—Motion is also exhibited by colorless blood- 
corpuscles, lymph-corpuscles, leucocytes, and some other corpuscles. In 
these structures we have examples of amoeboid movement (§ 9), which is move- 
ment in an indefinite direction.] 
[(r) Ciliary Movement.—There is also a peculiar form of movement, 
known as ciliary movement. There is a gradual transition between these differ- 
ent forms of movement. The cilia which are attached to the ciliated epithe- 
lium are the motor agents (fig. 364).] 
[Ciliated epithelium—where found.—In the nasal mucous membrane, except the olfactory 
region; the cavities accessory to the nose; the upper half of the pharynx, Eustachian tube, 
larynx, trachea, and bronchi; in the uterus, except the lower half pf the cervix ; Fallopian tubes ; 
vasa efferentia to the lower end of epididymis; ventricles of brain (child); and the central canal 
of the spinal cord.] 
[The cilia are flattened blade-like or hair-like appendages attached to the 
free end of the cells. They are about s 0 inch in length, and are apparently 
homogeneous and structureless. They 
are planted upon a clear non-contrac- 
tile disc on the free end of the cell, 
and some observers state that they 
pass through the disc to become con- 
tinuous with the protoplasm of the 
cell, or with the plexus of fibrils which 
pervades the protoplasm, so that by 
some observers they are regarded as 
prolongations of the intra-epithelial 
plexus of fibrils. They are specially 
modified parts of an epithelial cell, 
and are contractile and elastic. They are colorless, tolerably strong, not tinged 
by staining reagents, and are possessed of considerable rigidity and flexibility. 
They are always connected with the protoplasm of cells, and are never out- 
growths of the solid cell membranes. There may be 10 to 20 cilia distributed 
uniformly on the free surface of a cell (fig. 364).] 
[In the large ciliated cells in the intestine of some molluscs (mussel), the cilia perforate the 
clear refractile disc, which appears to consist of small globules—basal pieces—united by their 
edge, so that a cilium seems to spring from e’ach of these, while continued downwards into the 
protoplasm of the cell, but not attached to the nucleus, there is a single varicose fibril—rootlet, 
and the leash of these fibrils passes through the substance of the cell and may unite towards its 
lower tailed extremity (Engelmann).] 
Ciliated 
epithelium. 
Clear 
■disc. 
Inter- 
mediate 
forms. 
Inner 
layer. 
Debove’s 
membrane. 
Ciliated epithelium. 
Fig. 364. CILIARY MOTION. 
[Sec. 291. 
Ciliary motion may be studied in the gill of a mussel, a small part of the 
gill being teased in sea water; or the hard palate and oesophagus of a frog, 
newly killed, may be scraped and the scraping examined in p.c. salt solution. 
The whole of the mucous membrane of the frog’s palate and oesophagus may 
be examined. In this case the particles moved by the cilia are carried towards 
the stomach. On analyzing the movement, all the cilia will be observed to 
execute a regular, periodic, to and fro rhythmical movement in a plane usually 
vertical to the surface of the cells, the direction of the movement being parallel 
to the long axis of the organ. The appearance presented by the movements 
of the cilia is sometimes described as a lashing movement, or like a field of corn 
moved by the wind. Each vibration of a cilium consists of a rapid forward 
movement or flexion, the tip moving more than the base, and a slower back- 
ward movement, the cilium again straightening itself. The forward movement 
is at least twice as rapid as the backward movement. The amplitude of the 
movement varies according to the kind of cell and other conditions, being less 
when the cells are about to die, but it is the same for all the cilia attached to 
one cell, and is seldom more than 20° to 50°. There is a certain periodicity 
in their movement—in the frog they contract about 12 times per second. The 
result of the rapid forward movement is that the surrounding fluid, and any 
particles it may contain, are moved in the direction in which the cilia bend. 
All the cilia of adjoining cells do not move at once, but in regular succession, 
the movement travelling from one cell to the other, but how this co-ordina- 
tion is brought about we do not know. At least it is quite independent of the 
nervous system, as ciliary movement goes on in isolated cells, and in man 
it has been observed in the trachea two days after death. [Kraft has shown, in 
the case of the frog, that when the ciliated cells of the palate are stimulated 
mechanically the condition of excitation is more readily propagated in a 
longitudinal direction towards the stomach than laterally or towards the mouth, 
so that its excitability to mechanical stimuli is most marked in the direction of 
its physiological activity. The co-ordination seems to depend on the trans- 
ference of the condition of excitement of the cells, in this case from higher to 
lower placed cells.] 
[Conditions for Ciliary Movement.—In order that the ciliary move- 
ment may go on, it is essential that (x) the cilia be connected with part of a 
cell; (2) moisture ; (3) oxygen be present; and (4) the temperature be within 
certain limits.] 
[A ciliated epithelial cell is a good example of the physiological division of labor. It is 
derived from a cell which originally held motor, automatic, and nutritive functions all combined 
in one mass of protoplasm; but in the fully developed cell, the nutritive and regulative functions 
are confined to the protoplasm, while the cilia alone are contractile. If the cilia be separated 
from the cell, they no longer move. If, however, a cell be divided so that part of it remains 
attached to the cilia, the latter still move. The nucleus is not essential for this act. It would 
seem, therefore, that though the cilia are contractile, the motor impulse probably proceeds from 
the cell. Each cell can regulate its own nutrition, for during life they resist the entrance of 
certain colored fluids.] 
[Effect of Reagents on Ciliary Motion.—Gentle heat accelerates the 
number and intensity of the movements, cold retards them. A temperature of 
450 C. causes coagulation of their proteids, makes them permanently rigid, and 
kills them, just in the same way as it acts on muscle, causing heat-stiffening 
(§ 295, 1). Weak alkalies may cause them to contract after their movement 
is arrested or nearly so ( Virchow), and any current of fluid in fact may do so. 
Cilia after being in action for a time sh,ow signs of fatigue like muscle. It 
may be, as in muscle, acid proteids are formed, and that the weak alkali 
neutralizes the acid fatigue-products. Lister showed that the vapor of ether 
and chloroform arrests the movements as long as the narcosis lasts, but if the Sec. 291.] 
FUNCTIONS OF CILIA. 
575 
vapor be not applied for too long a time, the cilia may begin to move again. 
The prolonged action of the vapor kills them. As yet we do not know any 
specific poison for cilia—atropin, veratrin, and curare acting like other sub- 
stances with the same endosmotic equivalent (Engeltnann). Electrical stimula- 
tion seems to act simultaneously at both poles (AVo/?).] 
[Functions of Cilia.—The moving cilia propel fluids or particles along 
the passages which they line. By carrying secretions along the tubes which 
they line towards where these tubes open on the surface, they aid in excretion. 
In the respiratory passages, they carry outwards, along the bronchi and trachea, 
the mucus formed by the mucous glands in these regions. When the mucus 
reaches the larynx it is either swallowed or coughed up. That the cilia carry 
particles upwards in a spiral direction in the trachea has been proved by actual 
laryngoscopic investigation, and also by excising a trachea and sprinkling a 
colored powder on its mucous membrane, when the colored particles (Berlin 
blue or charcoal) are slowly carried towards the upper end of the trachea. In 
bronchitis the ciliated epithelium is shed, and hence the mucus tends to accu- 
mulate in the bronchi. They remove mucus from cavities accessory to the nose, 
and from the tympanum, while the ova are carried partly by their agency from 
the ovary along the Fallopian tube to the uterus. In some of the lower animals, 
they act as organs of locomotion, and in others as adjuvants to respiration, by 
creating currents of water in the region of the organs of respiration. 
[The Force of Ciliary Movement.—Wyman and Bowditch found that the amount of work 
that can be done by cilia is very considerable. The work was estimated by the weight which a 
measured surface of the mucous membrane of the frog’s hard palate was able to carry up an 
inclined plane of a definite slope in a given time.] 
[Pigment-cells belong to the group of contractile tissues, and are well 
developed in the frog, and 
many other animals where 
their characters have been 
carefully studied. They are 
generally regarded as com- 
parable to branched connec- 
tive-tissue corpuscles, loaded 
with pigmented granules of 
melanin. The pigment- 
granules may be diffused in 
the cell, or aggregated around 
the nucleus; in the former 
case, the skin of the frog 
appears dark in color; in 
the latter, it is but slightly 
pigmented (fig. 365).] 
Conditions affecting 
frog’s pigment-cells.— 
They undergo marked 
changes of shape under vari- 
ous influences. If the motor-nerve to one leg of a frog be divided, the skin 
of the leg on that side becomes gradually darker in color than the intact leg. 
A similar result is seen in the curare experiment, when all parts are ligatured 
except the nerve. Local applications affect the state of diffusion of the pig- 
ment, as v. Wittich found that turpentine or electricity caused the cells of the 
tree-frog to contract, and the same effect is produced by light. In Rana tem- 
poraria local irritation has little effect, but light, on the contrary, has, although 
the effect of light seems to be brought about through the eye, probably by a 
Pigment-cells from the web of frog’s foot; a, cell with pig- 
ment-granules diffused ; b, granules more concentrated ; 
c, more concentrated still; d, cells with guanin-granules 
{Stirling). 
Fig- 365- 576 
PIGMENT CELLS AND STRIPED MUSCLE. 
[Sec. 291. 
reflex mechanism (Lister). A pale-colored frog, put in a dark place, assumes, 
after a time, a different color, as the pigment is diffused in the dark; but if it 
be exposed to a bright light it soon becomes pale again. The same phenomenon 
may be seen on studying the web of a frog’s leg under the microscope. The 
marked variations of color—within a certain range—in the chameleon is due 
to the condition of the pigment-cells in its skin, covered as they are by epi- 
dermis, containing a thin stratum of air (Brucke). When it is poisoned with 
strychnin, its whole body turns pale ; if it be ill, its body becomes spotted in a 
dendritic fashion, and if its cutaneous nerves be divided, the area supplied by 
the nerve changes to black. The condition of its skin, therefore, is readily 
affected by the condition of its nervous system, for psychical excitement also 
alters its color. If the sympathetic nerve in the neck of a turbot be divided, 
the skin on the dorsal part of the head becomes black. It is well known that 
the color of fishes is adapted to the color of their environment. If the 
nerve proceeding from the stellate ganglion in the mantle of a cuttle-fish be 
divided, the skin on one half of the body becomes pale. The intra-epithelial 
pigment-cells of the membrane lining the abdomen and those of the tail in the 
salamander undergo division by mitosis. At first the processes of the branched 
cell are retracted, the nucleus divides by mitosis, but at first the pigment is in 
the protoplasm outside the chromatin figure, but later it lies between the chro- 
matin loops, while in the dyaster stage it is all accumulated at the equator, but 
none occurs within the chromatin figures ( Waldeyer, Zimmermann).] 
[Guanin in Cells.—Besides the pigment-cells in the web of a frog’s foot (especially in Rana 
temporaria) there are other cells which contain granules of guanin (fig. 365, d). If the web of 
a frog’s foot be mounted in Canada balsam and examined microscopically between crossed 
Nicol’s prisms, each guanin-cell is seen to contain numerous very strongly doubly refractive 
granules of guanin ($ 283).] 
292. STRUCTURE AND ARRANGEMENT OF MUSCLES.— 
[Muscular Tissue is endowed with contractility, so that when it is acted 
upon by certain forms of energy or stimuli, it contracts. There are two 
varieties of this tissue— 
(1) Striped, striated (or voluntary) ; 
(2) Non-striped, smooth, organic (or involuntary). 
Some muscles are completely under the control of the will, and are hence 
called “ voluntary,” and others are not directly subject to the control of the 
will, and are hence called “ involuntary;” the former are for the most part 
striped, and the latter non-striped ; but the heart-muscle, although striped, is an 
involuntary muscle.] 
1. Striped Muscles.—The surface of a muscle is covered with a connec- 
tive-tissue envelope or perimysium externum, from which septa, carrying 
blood-vessels and nerves, the perimysium internum, pass into the substance 
of the muscle, so as to divide it into bundles of fibres or fasciculi, which are 
fine in the eye-muscles and coarse in the glutei. In each such compartment or 
mesh there lie a number of muscular fibres arranged more or less parallel to 
each other. [The fibres are held together by delicate connective-tissue or 
endomysium, which surrounds groups of the fibres; each fibre being, as it 
were, separated from its neighbor by delicate fibrillar connective-tissue.) Each 
muscular fibre is surrounded with a rich plexus of capillaries [which form an 
elongated meshwork, lying between adjacent fibres, but never penetrating the 
fibres, which, however, they cross (fig. 371). In a contracted muscle, the 
capillaries may be slightly sinuous in their course, but when a muscle is on the 
stretch these curves disappear. The capillaries lie in the endomysium, and 
near them are lymphatics.] Each muscular fibre receives a nerve-fibre. 
[Where found.—Striped muscular fibres occur in the skeletal muscles, heart, Sec. 292.] 
STRUCTURE OF STRIPED MUSCLE. 
577 
diaphragm, pharynx, upper part of oesophagus, muscles of the middle ear and 
pinna, the true sphincter of the urethra, and external anal sphincter.] 
A muscular fibre (fig. 366, 1) is a more or less cylindrical or polygonal 
fibre, 11 to 67 fj. to in.] in diameter, and never longer than 3 to 4 
centimetres [1 to i}{ in.]. Within short muscles, e. g., stapedius, tensor tym- 
pani, or the short muscles of a frog, the fibres are as long as the muscle itself; 
within longer muscles, however, the individual fibres are pointed, and are 
united obliquely by cement-substance with a similar bevelled or pointed end of 
another fibre lying in the same direction. Muscular fibres may be isolated by 
maceration in nitric acid with excess of potassic chlorate or by a 35 per cent, 
solution of caustic potash. 
Histology of muscular tissue. 1. Diagram of part of a striped muscular fibre; S, sarcolemma; 
Q, transverse stripes; F, fibrillse; K, the muscle-nuclei; N, a nerve-fibre entering it with 
a, its axis cylinder and Kiihne’s motorial end-plate, e, seen in profile; 2, transverse section 
of part of a muscular fibre, showing Cohnheim’s areas, c; 3, isolated muscular fibrillse; 4, 
part of an insect’s muscle greatly magnified; a, Krause-Amici’s line limiting the muscular 
cases; b, the doubly-refractive substance; c, Hensen’s disc; d, the singly-refractive sub- 
stance ; 5, fibres cleaving transversely into discs; 6, muscular fibre from the heart of a frog; 
7, development of a striped muscle from a human foetus at the third month; 8, 9, muscular 
fibres of the heart; c, capillaries; b, connective-tissue corpuscles; 10, smooth muscular 
fibres; 11, transverse section of smooth muscular fibres. 
Fig. 366. 
[Each muscular fibre consists of the following parts: — 
1. Sarcolemma or myolemma, an elastic sheath, enclosing the sarcous 
substance; 
2. The included sarcous substance ; 
3. The nuclei or muscle-corpuscles.] 578 
STRUCTURE OF STRIPED MUSCLE. 
[Sec. 292. 
Sarcolemma.—Each muscular fibre is completely enclosed by a thin, color- 
less, structureless, transparent elastic sheath (fig. 366, 1, S)—the sarcolemma 
—which, chemically, is mid-way between connective and elastic tissue, and 
within it is the contractile substance of the muscle. [When a muscular fibre is 
being digested by trypsin, Chittenden observed, at the beginning, the sarco- 
lemma raised from its sarcous contents as a folded tube, but it is ultimately 
digested by trypsin. It is thus distinguished from the collagen substance of 
connective-tissue, which is not digested by trypsin. It is not dissolved by 
boiling, and it resists the action of acids and dilute alkalies, while it is dissolved 
by concentrated alkalies. Thus, it differs from elastic fibres, and on the whole, 
chemically, it seems to be most closely related to the membrana propria of 
glands. It has much more cohesion than the sarcous substance which it 
encloses, so that sometimes, when teasing fresh muscular tissue under the 
microscope, one may observe the sarcous substance torn across, with the 
unruptured sarcolemma stretching between the ends of the ruptured sarcous 
substance. If muscular fibres be teased in distilled water, sometimes fine clear 
blebs are seen along the course of the fibre, due to the sarcolemma being raised 
by the fluid diffusing under it. The sarcous substance, but not the sarcolemma, 
may be torn across by plunging a muscle in water at 550 C., and keeping it 
there for some time (Runnier).~\ 
[In the frog there is an exceedingly thin membrane covering the retro-lingual lymph-sac. 
Ranvier calls this the retro-lingual membrane, and it contains isolated branched striped 
muscular fibres. He finds that the sarcolemma has elastic fibres directly continuous not only 
with its terminations, but also with its margins. Thus the one is attached to the other, the elastic 
fibre being cemented as it were to the sarcolemma. The elastic fibres are deeply stained by 
methyl-violet, the sarcolemma but slightly. He also finds that the sarcous matter ends in a broad, 
dim anisotropous disc.] 
Sarcous Substance.—The sarcous substance is marked transversely by 
alternate light and dim layers, bands, stripes or discs (fig. 366, 1, Q), so that 
each fibre is said to be “ transversely striped.” [The stripes do not occur 
in the sarcolemma, but are confined to the sarcous substance, and they involve 
its whole thickness.] 
[The animals most suited for studying the structure of the sarcous substance are some of the 
insects. The muscles of the water-beetle, Dytiscus marginalis, and the Hydrophilus piceus are 
well suited for this purpose. So is the crab’s muscle. In examining a living muscle micro- 
scopically, no fluid except the muscle-juice should be added to the preparation, and very high 
powers of the microscope are required to make out the finer details.] 
Bowman’s Discs.—If a muscular fibre be subjected to the action of 
hydrochloric acid (1 per 1000), or if it be digested by gastric juice, or if it be 
frozen, it tends to cleave transversely into discs (Bowman), which are artificial 
products, and resemble a pile of coins which has been knocked over (fig. 
366\5)\ 
Fibrillae.—Under certain circumstances a fibre may exhibit longitudinal 
striation. This is due to the fact that it may be split up longitudinally into 
an immense number of (1 to 1.7 in diameter) fine, contractile threads, the 
primitive fibrillae (fig. 366, 1, F), placed side by side, each of which is also 
transversely striped, and they are so united to each other by semi-fluid cement- 
substance that the transverse markings of all the fibrillae lie at the same level. 
Several of these fibrils are united together owing to the mutual pressure, and 
prismatic in form, so that when a transverse section of a perfectly fresh 
muscular fibre is observed after it is frozen, the end of each fibre is mapped 
out into a number of small polygonal areas called Cohnheim’s areas 
(fig. 366, 2). [Each bundle of fibrils or polygonal area represents what 
Kolliker called a “ Muscle-Column.”] 
Fibrillae are easily obtained from insects’ muscles, while those from a mam- Sec. 292.] 
STRUCTURE OF STRIPED MUSCLE. 
579 
mal’s muscle are readily isolated by the action of dilute alcohol, Muller’s fluid 
[or, best of all, per cent, solution of chromic acid] (fig. 366, 3). 
[In studying the structure of muscle, it is well to remember that there are con- 
siderable differences between the muscles of Vertebrates and those of Arthropoda.] 
[When a living unaltered vertebrate muscular fibre is examined micro- 
scopically, in its own juice, we observe the alternate dim and light transverse 
discs. Amici, Krause, and Dobie showed that a fine dark line runs across the light 
disc, and divides it into two (fig. 367). This line has been called Dobie’s 
line or intermediate line. Amici resolved it into a row of granules, and by 
others (<?. g., Krause) it is regarded as due to the existence of a membrane,— 
hence it is called Krause’s membrane,—which runs transversely across the 
fibre, being attached all round to the sarcolemma, thus dividing each fibre into 
a series of compartments placed end to end. Hensen described a disc or stripe 
in the centre of the dim disc.] 
[On Krause’s theory each muscular compartment contains (1) a broad 
dim disc, which is the contractile part of the sarcous substance. It is doubly 
refractive (anisotropous), and is composed of Bow- 
man’s sarcous elements. (2) On each end of this disc, 
and between it and Krause’s membranes, is a nar- 
rower, clear, homogeneous, and but singly refractile 
(isotropous), soft or fluid substance, which forms 
the lateral disc of Engelmann. In some insects it 
contains a row of refractive granules, constituting the 
granular layer of Flogel. If a muscular fibre be 
stretched and stained with logwood, the central part 
of the dim disc appears lighter in color than the two 
ends of the same disc. This has been described as 
a separate disc, and is called the median disc of 
Hensen (fig. 366, 4, r).] 
[In an unaltered fibre, the dim broad stripe may appear homo- 
geneous, but after a time it cleaves throughout its entire extent in 
the long axis of the fibre into a number of prismatic elements of 
fibrils, the sarcous elements of Bowman (fig. 366). These at 
first are prismatic, but as they solidify they shrink and seem to 
squeeze out of them a fluid, becoming at the same time more con- 
stricted in the centre. This separation into bundles of fibrils with 
an interstitial matter gives rise to the appearance seen on trans- 
verse section of a frozen muscle, and known as Cohnheim’s areas (fig. 366, 2, c). In all proba- 
bility the cleavage also extends through the lateral discs, and thus fibrils are formed by longitu- 
dinal cleavage of the fibre.] 
[Muscles of Arthropoda.—Engelmann showed that the muscles of these animals have a 
large number of discs. In a muscle of an animal killed by being plunged into alcohol, accord- 
ing to the position of the lens of the microscope, one sees— 
1. The broad dim disc, composed of two darker lateral portions or discs, and a lighter disc— 
that of Hensen, between them. In fig. 368 the whole disc is marked Q, and Hensen’s disc is 
distinguished as h. 
2. On both sides of this is a small, clear, slightly refractive stripe, J, corresponding to one of 
Engelmann’s isotropous stripes. 
3. On both sides there follows symmetrically a dark, strongly refractive stripe, N, correspond- 
ing to Engelmann’s accessory stripe and Flbgel’s granular layer. 
4. Then on both sides there is a clear, feebly refractive disc, E. 
5. Beyond E is a small, dark, highly refractive stripe, Z—usually the darkest—corresponding 
to the Amici-Krause line.] 
[From Z the stripes are repeated in the inverse order to Q, then in the same order to Z, and so 
on. This is the appearance with a low position of the lens. Many muscles do not show all 
these stripes, thus h is often absent.] 
[If the lens of the microscope be raised, to get a more superficial view of the fibre, the distribu- 
tion of the light is reversed (fig. 368, II), as all strongly refractive sections become light and all 
feebly refractive appear darker, while with a deep position of the lens, the reverse is the case.] 
Muscular fibre of a rabbit. 
a, disc.; b, light disc; c, 
intermediate or Dobie’s 
line; n, nucleus seen in 
profile. 
Fig. 367. 580 
[Sec. 292. 
[Experiment shows that the dim disc rapidly swells up in dilute acids, and also that the dim 
discs (Q), the accessory discs (N), and the Amici-Krause line (K), stain more deeply with log- 
wood than the other discs, and A less than the rest of Q.] 
[If a muscle which has been some time in alcohol be examined as to its longitudinal stria- 
tion, it will be seen to consist of rods with light intervals between them (fig. 369). The rods 
are thicker at their ends, and thinner and lighter at their middle. Rollett regards the clear in- 
tervals between these rods as consisting of sarcoplasma, a body closely related to protoplasm, 
and the rods as bundles of fibrillae or “ muscle-columns.”] 
[If a muscle be acted upon by certain acids the relative appearance of the muscle-columns and 
the sarcoplasma is altered ; and the latter may appear in these and in gold preparations as a 
plexus of fibrils with regular longitudinal and transverse meshes (Melland, Marshall, fig. 370.] 
[Muscle-Rods.—Schafer describes the appearance differently: Double rows of granules are 
seen lying in or at the boundaries of the light streaks (discs), and very fine longitudinal lines 
may be detected running through the dark streak (dim disc) and uniting the minute granules. 
These fine lines, with their enlarged extremities, are “ muscle-rods.” They are most conspicu- 
ous in insects. During the contraction of a living muscular fibre, Schafer describes the “ rever- 
sal of the stripes ” ($ 297) as follows : “ When the fibres contract, the light stripes are seen, as 
the fibres shorten and thicken, to become dark, an apparent reversal being thereby produced in 
the striae. This reversal is due to the enlargement of the rows of dark dots and the formation by 
their juxtaposition and blending of dark discs, whilst the muscular substance between these discs 
has by contrast a bright appearance.” With polarized light in a living muscular fibre, all the 
sarcous substance, except the muscle-rod, is doubly refractive or anisotropous, so that it appears 
bright on a dark field when the Nicol’s prisms are crossed, while under the same conditions con- 
tracted muscle and dead muscle show alternate dark and light bands (Schafer).] 
The nuclei or muscle-corpuscles are found immediately under the sarco- 
lemma in all mammals, and their long axis lies in the long axis of the fibre (8 
to 13 ix long, 3 to 4 ;j. broad). 
[In the muscles of the frog, reptiles, and some other animals, e.g., the red muscles of the 
rabbit and hare and in some muscles of birds, they lie in the substance of the fibre surrounded 
by a small amount of pro- 
toplasm.] When they oc- 
cur immediately under the 
sarcolemma they are more 
or less flattened,and lie em- 
bedded in a small amount 
of protoplasm (fig. 366, I 
and 2, K). They contain 
one or two nucleoli, and it 
is said that the protoplasm 
sends out fine processes 
which unite with similar 
processes from adjoining 
corpuscles, so that, accord- 
ing to this view, a branched 
protoplasmic network ex- 
ists under the sarcolemma. 
[Each nucleus has a re- 
ticulated appearance due 
to the presence of a plexus 
of fibrils, consisting of 
chromatin; in its meshes 
lies an achromatic sub- 
stance. The nuclei are specially large in Otiorhynchus planatus, one of the beetles. Mitotic figures 
indicating division of the nuclei have been observed. The nuclei are not seen in a perfectly fresh 
muscle, because, until they have undergone some change, their refractive index is the same as that 
of the sarcous substance.] They become specially evident after the addition of acetic acid. Histo- 
genetically, they are the remainder of the cells from which the muscular fibres were developed, 
(fig- 366) 7)- According to M. Schultze, the sarcous substance is an intercellular substance dif- 
ferentiated and formed by their activity. Perhaps they are the centres of nutrition for the mus- 
cular fibres. In amphibians, birds, fishes, and reptiles, they lie in the axis of the fibres between 
the fibrils. 
Sarcoplasma.—It is said that the protoplasm of the muscle-corpuscles forms a fine network 
throughout the whole muscular fibre, the transverse branches taking the course of the intermediate 
or Dobie’s line, and the longitudinal branches running in the interstices between Cohnheim’s 
areas, constituting the sarcoplasma (Ketzius, Bremer, Melland, fig. 370). 
STRUCTURE OF STRIPED MUSCLE. 
Fig. 368.—Insects’ muscle; I, with 
and II with a deeper position. 
Carabus cancellatus. 
Fig. 368. 
a high position of the lens, 
Fig. 369.—Muscular fibre of 
Fig. 369. Sec. 292.] 
581 
BLOOD-VESSELS OF MUSCLE. 
Relation to Tendons.—According to Toldt, the delicate connective-tissue 
elements, which cover the several muscular fibres, pass from the ends of the lat- 
ter directly into the connective-tissue elements of the tendon. The end of the 
muscular fibre is perhaps united to the smooth surface or hollow end of the tendon 
by means of a special cement ( Weismann—fig. 371, S). In arthropoda, the sar- 
colemma passes directly into and becomes continuous with the tendon (.Leydig). 
The tendon itself consists of longitudinally arranged bundles of white fibrous 
tissue with cells—tendon cells—embracing them (p. 588). There is a loose capsule 
or sheath of connective-tissue—the peritendineum of Kollman—surrounding 
the whole and carrying the blood-vessels, lymphatics, and nerves. The tendons 
move in the tendon-sheaths, which are moistened by a mucous fluid. In most 
situations, muscular fibres are attached by means of tendons to some fixed point, 
but in other situations (face) the ends terminate between 
the connective-tissue elements of the skin. [Relation to 
elastic fibres, p. 578.] 
[Blood-Vessels of Muscle.—Muscles, being very 
active organs, are richly supplied 
with blood. The blood-supply 
of a muscle differs from some 
organs in not constituting an 
actual vascular unit, supplied 
only by one artery and one vein, 
thus being unlike the kidney, 
spleen, etc. Each muscle usually 
receives several branches from 
different arteries, and branches 
enter it at certain distances along 
its whole length. The artery 
and vein usually lie together in 
the connective-tissue of the 
perimysium, while the capillaries 
lie in the endomysium. The 
capillaries lie between the mus- 
cular fibres, but outside the 
sarcolemma, where they form an elongated rich plexus with numerous trans- 
verse branches (fig. 372). The lymph to nourish the sarcous substance must 
traverse the sarcolemma to reach the former. In the red muscles of the 
rabbit (<?. g., semitendinosus) the capillaries are more wavy, while on the trans- 
verse branches of some of the capillaries, and on the veins, there are small, 
oval, saccular dilatations (fig. 373), which act as reservoirs for blood (.Ranvier).\ 
[Spalteholz finds that the arteries form a close plexus in muscle, with quadrangular meshes, 
the long axis being in the direction of the fibres. From this fine arteries proceed at right angles 
to break up into capillaries. In a relaxed muscle the capillaries are extended, but in a con- 
tracted muscle they are more or less curved. The veins run along with the arteries, and are 
provided with valves even to their finest branches. Each muscle is to be regarded as a closed 
system for its blood-stream. There is so free an anastomosis in muscle as to permit of a free 
distribution of blood to all its parts, while the venous system is so arranged that the products 
of muscular metabolism are carried out of the muscle as quickly and completely as possible.] 
[Lymphatics.—We know very little of the lymphatics of muscle, although the lymphatics of 
tendon and fascia have been carefully studied by Ludwig and Schweigger-Seidel. There are 
lymphatics in the endomysium of the heart, which are continuous with those under the peri- 
cardium. This subject still requires further investigation. Compare the lymphatics of the 
fascia lata of the dog (fig. 278, \ 201).] 
Entrance of the Nerve.—The trunk of the motor nerve, as a rule, enters the muscle at its 
geometrical centre (Schwalbe); hence, the point of entrance in muscles with long, parallel, or 
spindle-shaped fibres lies near its middle. If the muscle with parallel fibres is more than 2 to 
Fig. 370.—Network in a muscular fibre. Fig. 371.— 
Relation of a tendon, S, to its muscular fibre. 
Fig. 370. 
Fig- 371- 582 
[Sec. 292. 
NERVES TO MUSCLE. 
8 centimetres [1-3 inches] in length, several branches enter its middle. In triangular muscles, 
the point of entrance of the nerve is displaced more towards the strong tendinous point of con- 
vergence of the muscular fibres. A nerve-fibre usually enters a muscle at the point where there 
is the least displacement Qf the muscular substance during contraction. 
Fig . 372.—Injected blood-vessels of a human muscle, a, small artery; b, vein; c, capillaries. 
X 250. Fig. 373.—Blcod-vessels of a rabbit’s red muscle injected; A, artery; V, veins; 
n, dilatations on the transverse branch of the capillaries; m, position of the muscular 
fibres which are omitted ; s, longitudinal sinuous branches. 
Fig. 372. 
Fig. 373- 
Motor Nerve to Muscle.—Every muscle-fibre receives a motor nerve- 
fibre (fig. 366, 1, N). Each nerve does not contain originally as many motor 
nerve-fibres as there are 
muscular fibres in the mus- 
cle it enters ; in the human 
eye -muscles, there are only 
3 nerve-fibres to 7 muscu- 
lar fibres ; in other muscles 
(dog), 1 nerve-fibre to 40 
or 80 (Tergast). Hence, 
when a nerve enters a mus- 
cle it must divide, which 
occurs dichotomously [at 
Ranvier’s nodes], the struc- 
ture undergoing no change 
until there are exactly as 
many nerve-fibres as mus- 
cular fibres. In warm- 
blooded animals each mus- 
cular fibre has only one, while cold-blooded animals have several points of 
insertion of the nerve-fibre (Sandmann). A nerve-fibre enters each muscular 
fibre, and where it enters it forms an eminence (Doyere, 1840), the eminence 
of Doyere, or “ motorial end-plate” or “motor spray” of Kiihne 
(figs. 366, 1, 374, 375, 376, 377). 
End- 
plate. 
Muscle 
nucleus 
N erve. 
Muscular fibres with motorial end-plates. 
. Hg. 374. Sec. 292.] 
ENDING OF MOTOR NERVES. 
583 
[The elaborate investigations of K. Mays on the exact distribution of nerve- 
fibres in the muscles of the frog have conclusively proved—apart from experi- 
mental reasons—that parts of muscles receive no nerve-fibres at all, certain 
portions being free from nerves, e. g., the terminal portions of the sartorius 
muscle of the frog. This has been proved for all classes of vertebrates except 
osseous fishes.] 
[The mode of termination of a motor nerve in a muscular fibre is not the 
same in all animals, but in every case it pierces the sarcolemma, and its ultimate 
distribution has a distinct hypolemmal character. The Doyere’s eminence is 
present in most mammals and reptiles, but in amphibians and birds the ending 
is flat on the muscle-fibre. Most of the results known to us have been worked 
out by Kiihne. The nerve-endings, then, are confined to very small spots or 
areas on the muscular fibres, termed by Kiihne “ fields of innervation.” 
Most nerve-fibres have only one such field, but very long fibres may have, at 
most, eight. One or more medullated nerve-fibres pass—as preterminal or epi- 
lemmal fibres—from the point of division of the nerve-fibre to the muscular 
Fig- 375- 
Motor terminations in a lizard, stained by methylene blue, a, muscular fibres; b, a nerve trunk, 
which splits up into small branches, c, containing a few medullated fibres, d. The medul- 
lated fibres, d, end in motorial end-plates, e. 
fibre, to pass into the nerve-endings. The nerve-endings consist of divisions 
of the axial cylinder, which are distributed over the sarcous substance without 
(so far as is known) forming any direct connection with it. The endings, how- 
ever, lie in direct contact with it. This branched arrangement of the axis- 
cylinder under the sarcolemma Kiihne has called a “ motor-spray” (“mo- 
torisches Geweih ”), and the mode of distribution of the branches varies in 
different classes of animals. In the frog (fig. 376), tailed amphibians, and 
birds, the hypolemmal branches of the axis-cylinder form bayonet-like and 
branched endings. In the lizard, snakes, and mammals, the branches are often 
curved or twisted, and possessed qf lobes, and as the division is very variable, 
there is every form from a simple hook-like bend to a highly arborescent termi- 
nation (fig. 375).] 
[Where a motor nerve enters a muscular fibre at the eminence of Doyere, the 
sheath of the nerve-fibre, known as the perineural or Henle’s sheath (§ 321), 
becomes continuous with the sarcolemma. The eminence itself consists of a 
mass of protoplasm—or sarcoplasm—called by Kiihne sarcoglia—which con- 584 
ENDINGS OF NERVES IN MUSCLE. 
[Sec. 292. 
tains granules and nuclei, the latter with a membrane and peculiar nucleoli; 
the nuclei themselves are the fundamental or basal nuclei of the sarcoglia. The 
outer surface of the eminence is covered by a membrane called telolemma 
by Kiihne, but which in reality consists of two membranes, an outer one, the 
epilemma, continuous with the perineural or Henle’s sheath, and an inner 
one, the endolemma, the continuation of the sheath of Schwann of the nerve- 
fibre, both ultimately being connected with the sarcolemma. As the nerve 
pierces the muscular fibre, it loses its myelin, and with it disappears the keratin 
sheath or axilemma of the axis-cylinder, so that the spray-like ending is accom- 
panied only by the telolemma (fig. 377). The telolemma contains nuclei which 
are derived from Henle’s sheath (Kiihne).] 
[In some animals, such as the lizard, in order to see the nerve-terminations, 
it is sufficient to stain portions of fresh muscles with Delafield’s logwood or to 
inject methylene blue into the blood (fig. 375).] 
[Nerve-endings, then, are sublemmar, and the terniinations of the nerves 
never penetrate into the depth of the muscular fibre, but come into direct con- 
tact with the contractile prism or cylinder moistened by the fluids of the muscle. 
In many cases the striped substance is separated from the blunt nerve-endings 
by some of the sarcoglia, which in some cases penetrate and traverse the other 
constituent of the fibre. The latter Kiihne has called “ rhabdia.” The antler- 
like division of 
the axis-cylin- 
der or spray, 
in contact with 
the muscular 
substance, 
serves to con- 
duct the excita- 
tion from the 
former to the 
latter, but ex- 
citation of the 
muscular sub- 
stance is never 
transmitted in 
the reverse 
order to the 
n erve-ending 
{Kiihne). 
Each muscular 
fibre of the cray- 
fish is supplied by 
two nerve-fibrils 
arising from sepa- 
rate axis-cylinders 
(Biedermann). 
[Ramon y Cayal 
was unable to find 
any true emin- 
ences of Doyere 
in the wing-muscles of insects. By Golgi’s method Cayal finds that there is revealed on the 
muscular fibres of Calliphora vomitoria a plexus of nerve-fibrils with nerve-cells at the nodes.] 
Sensory fibres also occur in muscles, and they are the channels for mus- 
cular sensibility. They seem to be distributed on the outer surface of the 
sarcolemma where they form a branched plexus and wind round the muscular 
fibres {Arndt, Sachs); but, according to Tschirjew, the sensory nerves traverse 
Fig. 376.—Motor nerve-ending in the frog (.Kilhne). a, Profile view of 
entrance of the nerve; b, b, nuclei of the branches of the axial cylinder; 
c, c, c, nuclei of Henle’s sheath; e, muscle nuclei. Fig. 377.—Motor 
nerve-ending in lizards, mammals, and man. Schematic after Kiihne. 
A, axis-cylinder; A1, A1, terminal branches of A; a, a, myelin of nerves; 
b, perineural or Henle’s sheath, and its nuclei (c); d, nuclei of telolemma; 
B, bed; D, large granule in B; C, nuclei of the bed; E, muscle nuclei; 
F, contractile substance. 
Fig. 376. 
Fig- 377- Sec. 292.] 
CARDIAC AND SMOOTH MUSCLES. 
585 
the substance of the muscle, and after dividing dichotomously, end only in the 
aponeurosis, either suddenly or by means of a small swelling—a view con- 
firmed by Rauber. The existence of sensory nerves in muscles is also proved 
by the fact that stimulation of the central end of a motor nerve, e.g., the 
phrenic, causes increase of the blood-pressure and dilatation of the pupil (Asp, 
Kowalewsky, Nawrocki), as well as by the fact that when they are inflamed 
they are painful. They, of course, do not degenerate after section of the ante- 
rior root of the spinal nerves. 
Red and Pale Muscles.—In many fishes (skate, plaice, herring, mackerel) ( iV. Stirling), 
birds, and mammals (rabbits), there are two kinds of striped muscle \Krause), differing in color, 
histological structure (Ranvier), and physiological properties (Kronecker and Stirling). Some 
are “ red,” e.g., the soleus and semitendinosus of the rabbit, and others “ pale, ” e.g., the 
adductor magnus. [All the muscles of the bat are red.] In the pale muscles the fibres are 
thinner, the transverse striation is thicker, their longitudinal striation less marked, and their 
nuclei fewer than in the red muscles (Ranvier) ; they contain less glycogen, water, and myosin. 
[W. Stirling finds that the red muscles in many fishes, e.g., the mackerel, contain granules of 
oil, and present all the appearance of muscle in a state of fatty degeneration, while the pale 
muscles, lying side by side, contain no fatty granules.] 
Julius Arnold found in human muscles an extensive distribution of pale fibres amongst the red 
ones, and indeed in the same muscle in the frog and mammals, red and pale fibres occur 
together; in fact, this is the case in almost every muscle (Griitzner). 
[Spectrum of Muscle.—The red color of the ordinary skeletal muscle is due to haemo- 
globin in the sarcous substance (Jfiihne). This is proved by the fact that the color is retained 
after all the blood is washed out of the vessels, when a thin muscle still shows the absorption- 
bands of haemoglobin when examined with the spectroscope.] 
[Myo-haematin.—MacMunn points out that although most voluntary muscles owe their 
color to haemoglobin, it is accompanied by myo-hcematin in most cases, and sometimes entirely 
replaced by it ($ 293). Myo-haematin is found in the heart of vertebrates, in the papillary mus- 
cles of the human heart, and in abundance in the pectoral muscles of pigeons, and in some 
muscles of vertebrates and invertebrates, e.g., certain beetles (Hydrophilus, Dytiscus), the com- 
mon fly, and other insects, spiders, crustaceans, and molluscs.] 
Muscular Fibres of the Heart.—The mammalian cardiac muscle has 
certain peculiarities already mentioned (§ 43) : (1) It is striped, but it is invol- 
untary; (2) it has no sarcolemma; (3) its fibres branch and anastomose; (4) 
the transverse striation is not so distinct, and it is sometimes striated longitudi- 
nally; (5) the nucleus is placed in the centre of each cell (see § 43). [The 
cardiac muscle, viewed from a physiological point of view, stands midway be- 
tween striped and unstriped muscle. Its contraction occurs slowly and lasts for 
a long time (p. 101), while, although it is transversely striped, it is involuntary.] 
[Purkinje’s Fibres.—These fibres, which form a plexus of grayish fibres under the endocar- 
dium of the heart of ruminants, have been described already (fig. 38); the cells have, as it were, 
advanced only to a certain stage of development ($ 46).] 
Development of Muscular Fibre.—Each muscular fibre is developed from a uni-nucleated 
cell of the mesoblast, which elongates into the form of a spindle. As the cell elongates, the 
nuclei multiply. The superficial or parietal part of the cell-substance shows transverse markings 
(fig. 366, 7), while the nuclei with a small amount of protoplasm are continuous along the axis 
of the fibre, where they remain in some animals, but in man they pass to the surface where they 
come to lie under the sarcolemma. The muscles of the young are smaller and have fewer fibres 
than those of adults (Budge). In developing muscle, the number of fibres is increased by the 
proliferation of the muscle-corpuscles, which form new fibres. 
According to Paneth, in old individuals separate cells with aggregation of contractile sub- 
stance—so-called Sarcoplasts—unite to form new muscular fibres. Sig. Mayer regards these 
structures as retrogressive structures, and he calls them Sarcolytes ($ 103, II). 
Occurrence in lower Animals.—Striped muscle, besides occurring in the corresponding 
organs of vertebrata, occurs in the iris and choroid of birds. The arthropoda have only striped 
muscle, the molluscs, worms, and echinoderms chiefly smooth muscles; in the latter are muscles 
with double oblique striation (Sehwalbe). 
2. Non striped Muscle.—[Distribution.—It occurs very widely dis- 
tributed in the body, in the muscular coat of the lower half of the human 
oesophagus, stomach, small and large intestine, muscularis mucosse of the intes- 
tinal tract, in the arteries, veins, and lymphatics, posterior part of the trachea, 586 
STRUCTURE OF SMOOTH MUSCLE. 
[Sec. 292. 
bronchi, infundibula of the lung, muscular coat of the ureter, bladder, urethra, 
vas deferens, vesiculae seminales, and prostate; corpora cavernosa and spongiosa 
penis, ovary, Fallopian tube, uterus, skin, ciliary muscle, iris, upper eyelid, 
spleen and capsule of lymphatic glands, tunica dartos of the scrotum, gall- 
bladder, in ducts of glands, and in some other situations.] 
[Structure.—Smooth muscular fibres consist of fusiform or spindle-shaped 
elongated cells, with their ends either tapering to fine points or divided (fig. 
378). These contractile fibre-cells may be isolated by steeping a piece of the 
tissue in a 30 per cent, solution of caustic potash, or a strong solution of nitric 
acid. They are 45 to 230 /a to in.] in length, and 4 to 10 /1 to 
2Tirff in-] *n breadth. Each cell contains a solid oval elongated nucleus, which 
may contain one or more nucleoli. It is brought into view by the action of 
dilute acetic acid, or by staining reagents. The mass of the cell appears more 
or less homogeneous, although in some places the cell-substance shows longitu- 
dinal fibrillation [and is surrounded by a thin elastic envelope. They are not 
doubly refractive, so that the anisotropous substance seems to be absent]. 
Fig. 378.—Smooth muscular fibres (10); (11) transverse section. Fig. 379.—Smooth muscular 
fibre from the mesentery of a newt (ammonium chromate). N, nucleus; F, fibrils; S, 
markings in the sheath. Fig. 380.—Termination of nerve in non-striped muscle. 
Fig. 378. 
Fig- 379- 
Fig. 380. 
[Method .—This fibrillation is revealed more distinctly thus : Place the me- 
sentery of a newt {Klein) or the bladder of the salamandra maculata (Flemming) 
in a 5 per cent, solution of ammonium chromate, and afterwards stain it with 
picro-carmine. Each cell consists of a thin elastic sheath (sarcolemma of 
Krause) enclosing a bundle of fibrils (F) which run in a longitudinal direc- 
tion within the fibre (fig. 379). They are continuous at the poles of the nucleus 
with the plexus of fibrils which lies within the nucleus, and, according to Klein, 
they are the contractile part, and when they contract the sheath becomes 
shrivelled transversely and exhibits what looks like thickenings (S). These 
fibrils have been observed by Flemming in the cells while living. Sometimes 
the cells are branched, while in the frog’s bladder they are triradiate.] 
[Arrangement of the Fibres.—Sometimes the fibres occur singly, but 
usually they are arranged in groups, forming lamellae, sheets, or bundles, or in 
a plexiform manner, the bundles being surrounded by connective-tissue.] A 
very delicate elastic cement-substance unites the individual cells to each other. 
[This cement may be demonstrated by the action of nitrate of silver. In 
transverse section (fig. 378, 11) they appear oval or polygonal, with the delicate Sec. 292.] 
MUSCLE SPINDLES AND TENDON. 
587 
homogeneous cement between them ; but as the fibres are cut at various levels, 
the areas are unequal in size, and all of them, of course, are not divided at the 
position of the nucleus.] 
They vary in length from to of an inch; those in the middle coat of 
the arteries are short, while they are long in the intestinal tract, and especially 
so in the pregnant uterus. According to Engelmann, the separation of the 
smooth muscular substance into its individual spindle-like elements is a post- 
mortem change of the tissue. [Sometimes transverse thickenings are seen, 
which are not due to transverse striation, but to a partial contraction. Occa- 
sionally they have a tendinous insertion.] 
Blood-vessels in Smooth Muscle.—Non-striped muscle is richly sup- 
plied with blood-vessels, and the capillaries form elongated meshes between 
the fibres [although it is not so vascular as striped muscle]. Lymphatics 
also occur between the fibres. 
Motor Nerves to Smooth Muscle.—According to J. Arnold, 'they 
consist of medullated and non-medullated fibres [derived from the sympathetic 
system] which form a plexus—ground plexus—partly provided with gangli- 
onic cells, and lying in the connective-tissue of the perimysium. [The fibres 
are surrounded with an endothelial sheath.] Small branches [composed of 
bundles of fibrils] are given off from this plexus, forming the intermediary 
plexus with angular nuclei at the nodal points. It lies either immediately 
upon the musculature or in the connective-tissue between the individual bun- 
dles. From the intermediary plexus, the finest fibrillse (0.3 to 0.5 tx) pass off, 
either singly or in groups, and reunite to form the intermuscular plexus 
(fig. 380, d'), which lies in the cement substance between the muscle-cells, 
to end, according to Frankenhauser, in the nucleoli of the nucleus, or in the 
neighborhood of the nucleus (Lustig). According to J. Arnold, the fibrils 
traverse the fibre and the nucleus, so that the fibres appear to be strung upon 
a fibril passing through their nuclei. According to Lowit, the fibrils reach 
only the interstitial substance, while Gscheidlen also observed that the finest 
terminal fibrils, one of which goes to each muscular fibre, ran along the margins 
of the latter (fig. 380). The course of these fibrils can only be traced after the 
action of gold chloride. [Ranvier has traced their terminations in the stomach 
of the leech.] 
[Muscle-spindles.—Here and there in muscles there exist peculiar bundles of muscular 
fibres or single fibres, to which there proceeds a large nerve-fibre enveloped in several sheaths. 
The nerve perforates the sheath and terminates in the muscular fibre or 
fibres. They were first described by Kolliker in 1862, and the above 
name was given them by Kiihne in 1863. They appear to exist in all 
classes of vertebrates. These bodies were afterwards called sarcoplasts 
by Kiihne. Similar bodies were described by Roth as “ neuro muscular 
trunklets.” In frogs’ muscles they consist of groups of 3-10 very fine 
muscular fibres supplied by a large nerve-fibre covered with several 
sheaths, and as they are thickest where the nerve enters, and taper some- 
what towards their extremities, they received from Kiihne, the name of 
“ muscle-spindles,” although Kolliker called them “ muscle-buds.” As 
Ranvier points out, the sheaths are not unlike the lamellated sheath of a 
nerve. These structures occur in the muscles of frogs, reptiles, and 
higher animals, and even in human muscles; they seem to be muscular 
fibres in process of dividing longitudinally (Kolliker), although Bremer 
regards them as muscular fibres in process of development.] 
[Structure of Tendon.—A tendon consists chiefly of 
white fibrous tissue, with a very few elastic fibres. The white 
fibres are, for the most part, arranged longitudinally, and if 
a tendon be macerated in picric acid or 10 percent, solution 
of common salt and then frayed out at one end, the fine 
delicate fibrils which compose the fibres are readily obtained. The fibres 
Fig. 381. 
Tendon-cells, tail of a 
rat. a, Cells, tendon 
seen on edge and 
embracing a fibre; 
b b, on the flat, and 
showing their nuclei 
and ridges. 588 
[Sec. 292. 
STRUCTURE OF TENDON. 
are partially covered by the tendon-cells, which are simply modified connective- 
tissue corpuscles. In a longitudinal section of a tendon the cells appear as 
fusiform nucleated cells lying in rows, in single file, between the bundles. If, 
however, the tendons, e. g., from the tail of a rat or mouse, are stained with 
gold choride, the gold stains the protoplasm of the tendons deeper than the 
fibres, so that then the shape and relation of the cells can be more readily 
studied. The cells are flattened quadrilateral plates, which clasp the fibrous 
bundles, covering them, however, only on one side. They lie in rows on the 
fibres (fig. 381). 
The nuclei of the cells are generally less deeply stained and usually lie at the 
contiguous borders of two adjacent cells, as if the two cells had been produced 
by the splitting of one cell. Each cell has on it a longitudinal “stripe” or 
“ ridge” (fig. 381, b~), much like the ridge seen on the tiles of a roof. The 
ridge is produced by the soft plastic cell being compressed between several 
adjacent fibres. The fibres are arranged in groups, forming longitudinal bun- 
dles, and these again are held together by a common fibrous sheath, which 
sends in septa between the bundles to support them, and bind them together. 
Thus, in a transverse section of a tendon, one sees that the white fibres of the 
sheath and septa run somewhat circularly, and that they carry the few nerves 
and blood-vessels present in tendon. In the cross-section of each bundle are 
to be seen a number of stellate or branched spaces (fig. 382), lying between 
the smaller bundles of fascicules that make up a layer of bundles. These are 
the interfascicular or cell-spaces. In them lie the tendon-cells, of course closely 
applied to their respective fibres, and also some lymph. Each tendon exter- 
nally is covered with an endothelial sheath.] 
[Physical Properties of Tendon.—Moist tendon is highly flexible, is 
very inelastic and inextensible. It 
requires a very considerable force 
to rupture a tendon. The tendon 
of the frog’s gastrocnemius will 
readily carry a weight of two to three 
pounds without being ruptured.] 
[Termination of Nerves in 
Tendon.—For a long time it was 
believed that there were no nerves 
in tendon, but the fact that sprains 
are so painful, and that inflammation 
of tendons gives rise to severe pain, 
shows that there are sensory nerves 
present. The existence of nerve- 
terminations has been demonstrated 
in the tendons of all classes of ver- 
tebrates. They are readily obtained 
by the gold method in the sterno- 
radial tendon of the frog, and, as 
shown by Golgi, they are most abundant near the muscle. Meduliated nerve- 
fibres can be traced to the tendon, where the axis-cylinder splits up into a 
number of fibrils, which unite amongst themselves, and form a reticulated 
end-plate (Golgi’s end-plate), which is sometimes embedded in a granular- 
looking matter. The chief researches were made by Sachs (1875), Rollett 
(1876), and Golgi (1880), and most recently by Ciaccio. Golgi called the 
small tendon and the termination of the nerves in them “ musculo-tendinous 
organs,” but this name is not well chosen. The nerve-fibres which proceed to 
the tendon are always meduliated ; they lose their sheaths, and penetrate 
Fig. 382. 
Transverse section of a tendon from the tail of a rat, 
showing the branched stellate spaces. Sec. 292.] 
PHYSICAL PROPERTIES OF MUSCLE. 
589 
between the bundles of fibres of the tendon, where the axis-cylinder ramifies, 
and terminates either in free ends, or sometimes as a spiral around the tendon 
fibres. The nerve-end plaques of tendon have no nuclei belonging to them 
like those of motor nerve-plates; they are simply a bushy termination of 
branches of the axis-cylinder (fig. 383), and are usually arranged in two or 
three planes in a tendon, and never on the exterior of the tendon. In some 
situations, especially in fasciae, structures somewhat resembling end-bulbs have 
been found.] 
Within the tendons of the frog there is a plexus of medullated nerve-fibres, from which brush- 
like divided fibres proceed, which ultimately end with a point in nucleated plates, the nerve- 
flakes of Rollett. According to Sachs, bodies like end-bulbs occur in tendons, while Rauber 
found Vater’s corpuscles in their sheaths; Golgli found, in addition, spindle-shaped 
terminal corpuscles, which he regards as a specific apparatus for estimating tension. 
293. PHYSICAL AND CHEMICAL PROPERTIES OF 
MUSCLE.—1. The consistence of the sarcous substance is the same as 
that of living protoplasm, e. g., of lymph-cells; it is semi-solid, i. e., it is not 
fluid to such a degree as to flow like a fluid, nor is it so solid that, when its 
parts are separated, these parts are unable to come together to form a continu- 
Fig- 383- 
Termination of a nerve in the human tendo-Achillis. NR, node of Ranvier; SH, sheath of 
Henle; rfnc, final ramifications of the axis-cylinder in bands;///) primitive bundles of 
the tendon. 
ous whole. The consistence may be compared to a jelly at the moment when 
it is dissolved (e. g., by heat). 
Proofs.—The following facts corroborate the view expressed above: (a) The analogy 
between the function of the sarcous substance and the contractile protoplasm of cells ($ 9). 
(b) The so-called Porret’s phenomenon, which consists in this, that when a galvanic current 
is conducted through the living, fresh, sarcous substance, the contents of the muscular fibre 
exhibit a streaming movement from the positive to the negative pole (as in all other fluids), so 
that the fibre swells at the negative pole (.Kilhne). (c) By the fact that wave-movements 
have been observed to pass along the muscular fibre. (d) Direct observation has shown that a 
small parasitic round worm (Myoryctes Weismanni) moved freely in the sarcous substance 
within the sarcolemma, while the semi-solid mass closed up in the tract behind it (Kiihne, 
Eberth). 
2. Polarized Light.—The contractile substance doubly refracts light, and is said to be 
anisotropous, while the ground-substance causes single refraction, and is isotropous. 
According to Briicke, muscle behaves like a doubly refractive, positive uniaxial body, whose 
optical axis lies in the long axis of the fibre. When a muscular fibre is examined under the 
polarization microscope, the doubly refractive substance is recognized by its appearing bright in 
the dark field of the microscope when the Nicols are crossed ($ 297); in a colored field (purple, 
red, e. g., by inserting a plate of mica) these parts assume a different color (blue, yellowish-red, 
or yellow). During contraction of a muscular fibre, the contractile part of the fibre becomes 
narrower, and at the same time broader, whilst the optical constants do not thereby undergo 
any change. Hence Briicke concludes that the contractile discs are not simple bodies like [Sec. 293. 
590 
CHEMISTRY OF MUSCLE. 
crystals, but must consist of a whole series of small doubly refractive elements arranged in groups, 
which change their position during contraction and relaxation. These small elements Briicke 
called disdiaclasts. According to Schipiloff, Danielewsky, and O. Nasse, the contractile 
anisotropous substance consists of myosin, which occurs in a crystalline condition, and repre- 
sents the disdiaclasts. According to Engelmann, however, all contractile elements are doubly 
refractive, and the direction of contraction always coincides with the optical axis. 
As regards the anisotropous substance, the investigations of v. Ebner have shown that 
during the process of growth of the tissue, tension is produced—the tension of bodies subjected 
to imbibition—which results in double refraction, and so gives rise to the condition called aniso- 
tropous. During a sustained contraction in a dying muscle, the index of refraction of the mus- 
cular fibre increases, which is due to the loss of water by the tissue, thus causing a greater con- 
centration of the dissolved muscular constituents (Exner). 
[Reaction of Muscle.—If a transverse section of a living excised muscle be pressed upon 
a strip of blue litmus paper, the latter may assume a reddish tinge, and if upon a red litmus 
paper, the latter may assume a bluish tinge, but it will not alter violet litmus paper. This is the 
amphochromatic or amphoteric reaction, indicating that the muscle is neutral. It may, however, 
give only an alkaline reaction. A living muscle plunged into boiling water still retains its 
neutral or alkaline reaction; but a muscle, which has been tetanized, or is in rigor mortis, is 
decidedly acid.] 
[Chemical Composition of Muscle.—Living muscle in the resting con- 
dition is alkaline in reaction and has in round numbers the following compo- 
sition : — 
Water, 75 per cent. 
Solids, 25 “ “ 
Proteids and albuminoids, 21 per cent. 
Fats, extractives, and salts, 4 “ “ 
The human pectoralis major gave : — 
Water, 
73-5 
Solids, 
26.5 
Proteids, including sarcolemma, and proteidsof connective-tissue and 
vessels, 
Gelatin 1 p connective-tissue, 
f i-99 
hat j 
' ' l 3-27 
Extractives (kreatin, lactic acid, etc.), .... 
0*22 
Inorganic salts, 
• • : 3-12] 
The chemical composition of muscle rapidly undergoes a great change 
after death, owing to the spontaneous coagulation of a proteid within the 
muscular fibres. As frog’s muscles may be frozen and thawed, and still remain 
contractile, they cannot therefore be greatly changed by the process of freezing. 
Kuhne bled frogs, cooled their muscles to io° or 70 C., pounding them in an 
iced mortar, and expressed their juice through linen. The juice so expressed, 
when filtered in the cold, forms a neutral, or alkaline, slightly yellowish, 
opalescent fluid, the so-called “muscle-plasma.” Like blood-plasma, it 
coagulates spontaneously; at first it is like a uniform soft jelly, but soon 
becomes opaque ; doubly refractive fibres and specks, similar to the fibrin of 
blood, appear in the jelly, and as these begin to contract, they squeeze out of 
the jelly an acid “muscle-serum.” [Halliburton finds that the muscles of 
warm-blooded animals yield a similar muscle-plasma when they are cooled and 
subjected to pressure in a suitable press.] Cold prevents or delays the coagu- 
lation of the muscle-plasma; above o° coagulation occurs very slowly, and the 
rapidity of coagulation increases rapidly as the temperature rises, while coagu- 
lation takes place very rapidly at 40° C. in cold-blooded animals, or at 48° to 
50° C. in warm-blooded muscles. The addition of distilled water or an acid 
to muscle-plasma causes coagulation at once. The coagulated proteid most 
abundant in muscle, and which arises from the doubly refractive substance, is 
called “myosin” (W. Kuhne). 
Myosin.—It is a globulin ($ 245), and is soluble in strong (10 per cent.) solution of common 
salt, and is again precipitated from such a solution by dilution with water, or by the addition of 
very small quantities of acids (0.1 to 0.2 per cent, lactic or hydrochloric acid). It is soluble in Sec. 293.] 
COMPOSITION OF MUSCLE. 
591 
dilute alkalies or slightly stronger acids (0.5 per cent, lactic or hydrochloric acid), and also in 
13 per cent, ammonium chloride solution. [The more myosin is freed from salts (especially of 
calcium) by washing, the more insoluble does it become, both in saline solutions and weak hydro- 
chloric acid. When once precipitated from its' solution, it can be redissolved, reprecipitated, 
and again undergo coagulation a second or even a third time (.Halliburton).] Like fibrin, myosin 
rapidly decomposes hydric peroxide. When treated with dilute hydrochloric acid and heat, it is 
very rapidly changed into syntonin (§ 245). Myosin may be extracted from muscle by a 10 to 
15 per cent, solution of NH4C1, and if it be heated to 65°, it is precipitated again (Danielewsky). 
Danielewsky succeeded in partly changing syntonin into myosin by the action of milk of lime 
and ammonium chloride. Myosin occurs in other animal structures (cornea), nay, even in some 
vegetables ((?. Nasse). 
Muscle serum, according to Kiihne, still contains three proteids (2.3 to 3 
per cent.), viz. : 1. Alkali-albuminate, which is precipitated on adding an 
acid, even at 20° to 240 C. 2. Ordinary serum-albumin, 1.4 to 1.7 per 
cent. (§ 32, a), which coagulates at 730 C. 3. An albuminate which coagu- 
lates at 470 C. 
[Halliburton finds, however, the following proteids in muscle-plasma :— 
Name. 
Precipitated by 
Heat at 
Saturation with NaCl or Na2S04. 
Paramyosinogen, 
Myosinogen, 
Myoglobulin, 
Albumin, 
Myoalbumose, 
47° C. 
56° 
63° 
73° 
Not 4- 
Causes precipitation. 
ii ii 
ii it 
No | 
No -J- 
1 Proteids which go to 
I form muscle-clot. 
(_ Proteids of the 
| muscle-serum. 
Although the first two go to form the clot of muscle or myosin, paramyosinogen 
is not essential for coagulation. Besides these bodies there are haemoglobin 
and also myo-haematin, which is not identical with the blood-pigment 
(? p. 484). The latter can be extracted by ether from muscle (e. g., the breast 
muscle of a pigeon), whereby the ether becomes red. It can exist in an 
oxidized and reduced condition (MacMunn). According to Levy, it is iden- 
tical with hsemochromogen, while Hoppe-Seyler regards it as a mixture of 
Hb02 and Hb.] 
The other chemical constituents of muscle have been referred to in treating 
of flesh (§ 233). 1. Muscle-ferments.—Briicke found traces of pepsin 
and peptone in muscle-juice, [the latter is denied by Halliburton] ; Piotrowsky, 
a trace of a diastatic ferment. [When muscle becomes acid, as in rigor 
mortis, the pepsin at a suitable temperature (350 to 40° C.) acts on the pro- 
teids, and albumoses and peptones are formed. Halliburton found a myosin- 
ferment which has the characters of an albumose. It is prepared in the same 
way as fibrin-ferment by keeping muscle for some months under alcohol, and 
then making a watery extract of the muscle. It does not hasten the coagula- 
tion of blood-plasma, although it causes muscle plasma to coagulate. It does 
not seem to be identical with fibrin-ferment.] 2. In addition to volatile fatty 
acids (formic, acetic, butyric), there are two isomeric forms of lactic acid 
(C3H603) present in muscle with an acid reaction : (a) Ethylidene-lactic acid, 
in the modification known as right rotatory sarcolactic orparalactic acid, which 
occurs only in muscles, and some other animal structures. (' b) Ethylene-lactic 
acid in small amount (§ 251, 3, c). It was formerly assumed that lactic acid is 
formed by fermentation from the carbohydrates of the muscle (glycogen, dex- 
trin, sugar), and Maly has observed that paralactic acid is occasionally formed 
when these bodies undergo fermentation. According to Bohm, however, the 
glycogen of muscle does not pass into lactic acid, as during rigor mortis, if 
putrefaction be prevented, the amount of glycogen does not diminish. If [Sec. 293. 
592 
METABOLISM IN MUSCLE. 
muscle be suddenly boiled or treated with strong alcohol, the ferment is 
destroyed, and hence the acidification of the muscular tissue is prevented (Du 
Bois-Reymond). Acid potassium phosphate also contributes to the acid reac- 
tion. 3. Glycogen occurs to the amount of over 1 per cent, after copious 
flesh feeding, and to 0.5 per cent, during fasting. It is stored up in the mus- 
cles, as well as in the liver during digestion, but it disappears during hunger. 
It is perhaps formed in the muscles from proteids (§ 174, 2). 4. Carnin 
(C7H8N403) which is changed by bromine or nitric acid into sarkin, occurs to 
the extent of 1 per cent, in Liebig’s extract of meat ( Weidel). 5. Urea, 0.01 
per cent. (Haycraft). [There is much urea in the muscles of the skate and 
allied genera of fish.] 6. Lecithin, derived in part from the motor nerve- 
endings (§ 23 and § 251). 7. The gases are C02 (15 to 18 vol. per cent.), 
partly absorbed, partly chemically united (some absorbed N, but no free O, 
although muscle continually absorbs O from the blood passing through it 
(Z. Hermann). The muscles contain a substance whose decomposition yields 
C02. When muscles are exercised, this substance is used up so that severely 
fatigued muscles yield less C02 (Stinzing). [All muscles have not the same 
chemical composition (p. 442).] 
[The extractives of muscle are divided into— 
(A) Nitrogenous, e.g., Kreatin, C4H9N302 = 0.2 to 0.3 per cent. (This 
therefore indicates that a very considerable quantity of this substance (90 grams) 
must exist in the body, seeing that the muscles make up nearly one-half of the 
weight of the body): Kreatinin, C4H7N30; Hypoxanthin, C5H4N40; Xanthin, 
C5H4N402; Uric acid, C5H4N403; Carnin, C7H8N403 -j- H20 ; Urea, CON2H4; 
Taurin; Inosinic acid, C10H14N4On; Lecithin (?) which may be derived from 
the nerve-fibres in muscle. 
(B) Non-nitrogenous ; glycogen, inosite, fermentable sugar, lactic acids, 
and fats.] 
[Chemistry of Smooth Muscle.—Smooth muscle, as a rule, has an al- 
kaline or neutral reaction, although the adductor muscle of Anodonta, which 
is almost constantly in action, is acid. Smooth muscles pass into rigor and 
become acid. A spontaneously coagulable plasma has so far not been obtained, 
nor has myosin. A body related to myosinogen coagulating at 45-49 C. has 
been obtained by Heidenhain. Smooth muscles are said to contain alkali- 
albuminate and an albumin coagulating at 750 C. (Hammarsten).] 
294. METABOLISM IN MUSCLE.—[In living muscle we have to 
study the transformations of energy, and the chemical changes on which these 
depend. But as we cannot examine the chemical changes which occur during 
a contraction, we are confined to a study of— 
(1) The composition of a muscle before and after contraction, and 
(2) The effect of contraction on the medium surrounding or passing 
through a muscle. 
We may observe the effect produced by a muscle upon air or other gases to 
which an excised muscle is exposed, or we may investigate the changes which 
the blood undergoes in passing through a muscle, and if the muscle be still in 
situ, the effect upon the general excreta. These methods may be applied to 
muscle in various conditions, passive or active, dead or dying, to excised mus- 
cles or those still under normal conditions.] 
I. A passive muscle continually absorbs a certain amount of O from the 
blood flowing through its capillaries and returns a certain amount of C02 to 
the blood-stream. The amount of C02 given off is less than corresponds to 
the amount of O absorbed. Excised muscles freed from blood exhibit an 
analogous but diminished gaseous exchange. As an excised muscle remains Sec. 294.] 
METABOLISM IN MUSCLE. 
593 
longer excitable in O or in air than in. an atmosphere free from O, or in indif- 
ferent gases, we must conclude that the above-named gaseous exchange is con- 
nected with the normal metabolism, and is a condition on which the life and 
activity of the muscle depend. Resting living muscles also exhale C02. 
Perfusion of Blood.—If a living muscle be excised (dog), and if blood be perfused through 
its blood-vessels, the amount of O used up is, within pretty wide limits, almost independent of 
temperature; if the variations of temperature be great, it rises and falls with the temperature. 
The C02 given off by muscular tissue (less than the O used up) falls when the muscle is 
cooled, but it is not increased when the muscle is subsequently warmed (Rubner). 
Putrefaction.—This exchange of gases must be distinguished from the putrefactive phenomena 
due to the development of living organisms in the muscle. These putrefactive phenomena are 
also connected with the consumption of O and the excretion of C02 and occur soon after death 
(Z. Hermann'). 
II. In an active muscle the blood-vessels are always dilated (Ludwig 
and Sczelkow, Gaskell)—a condition pointing to a more lively material exchange 
in the organ. The dilatation of the blood-vessels can be absorbed microscopi- 
cally in the contracting mylo-hyoid muscle of the frog. If the motor-nerve 
passing to the mylo-hyoid muscle be stimulated, either with or without the use 
of curare, the blood-vessels dilate. This is due to the action of the vaso-dilator 
nerve-fibres on the smooth muscles of the blood-vessels, causing them to relax. 
Hence the active muscle is distinguished from the passive one by a series of 
chemical transformations. 
1. Reaction of Muscle.—The neutral or feebly alkaline reaction of a 
passive muscle (also of the non-striped variety) passes into an acid reaction 
during the activity of the muscle, owing to the formation of paralactic acid 
(.Du Bois-Reymo?id, 1859); the degree of acidity increases up to a certain ex- 
tent, according to the amount of work performed by the muscle (R. Heiden- 
hairi). The acidification is due, according to Weyl and Zeitler, to the phos- 
phoric acid produced by the decomposition of lecithin and (? nuclein). 
It is doubtful if the acidity is due to lactic acid, as Warren and Astaschewsky find that there 
is less lactic acid in the active than in the passive muscle. Marcuse, however, supports the lactic 
acid theory, while Moleschott and Battistini agree that the passive muscle contains acid, but the 
fatigued muscle contains more, especially of phosphoric acid and CO,. 
2. Production of C02.—An active muscle excretes considerably more C02 
than a passive one : (a) active muscular exertion on the part of a man or of 
animals increases the amount of C02 given off by the lungs (§ 126, 6); (h) 
venous blood flowing from a tetanized muscle of a limb contains more C02, 
more C02 being formed than corresponds to the O which has simultaneously 
been absorbed (.Ludwig and Sczelkow). The same result is obtained when 
blood is perfused through an excised muscle; (c) an excised muscle caused to 
contract excretes more C02 (compare § 368). 
3 Consumption of Oxygen.—An active muscle used up more O—(a) 
when more muscular work is done, the body absorbs much more O (§ 217)— 
even 4 to 5 times as much {Regnault and Reiset)\ (b) venous blood flowing from an 
active muscle of a limb contains less O (.Ludwig, Sczelkow, and Al. Schmidt). 
Nevertheless, the increase of O used up by the active muscle is not so great as 
the amount of C02 given off {v. Pettenkofer and v. Voit). The increase of O 
used up may be ascertained even during the period of rest directly following 
the period of activity, and the same is the case with the C02 excreted (v. 
Frey). 
As yet it is not possible to prove by gasometric methods that O is used up in 
an excised muscle free from blood. Indeed, the presence of O does not 
seem to be absolutely necessary for the activity of muscle during short periods, 
as an excised muscle may continue to contract in a vacuum, or in a mixture of 
gases free from O, and no O can be obtained from muscular tissue (Z. 594 
METABOLISM IN MUSCLE. 
[Sec. 294. 
Hermann). A frog’s muscles rob easily-reducible substances of their O ; they 
discharge the color of a solution of indigo; muscles which have rested for a 
time, acting less energetically than those which have been kept in a state of 
continued activity (Griitzner, Gscheidlen). 
[The following table quoted by Halliburton shows the consumption of oxygen 
and the elimination of C02 by living and rigid muscles, and that although the 
O absorbed is nearly identical in amount, the C02 given off is greatly increased 
by the onset of rigor and by contraction— 
Oxygen 
absorbed 
C02 given off 
Living muscle, 
18 per cent. 
8 per cent. 
Rigid muscle, 
16 “ 
16 “ 
Muscle at rest, 
Tetanized muscle, 
6 “ 
i “ 
8 “ 
9 “ 
The same result is shown by an analysis of the blood after being perfused 
through passive and active surviving muscles (Ludwig and Schmidt) :— 
Venous blood. 
O less than arterial blood. 
C02 more than arterial blood. 
Muscle at rest, 
9.0 per cent. 
6.7 per cent. 
Muscle in action, 
12.26 “ 
10.8 “ ] 
4. Glycogen.—The amount of glycogen (0.43 per cent, in the muscles of a 
frog or rabbit) and grape-sugar is diminished in an active muscle (O. Nasse, 
Weiss), but muscles devoid of glycogen do not lose their excitability and con- 
tractility. Hence glycogen is certainly not the direct source of the energy in 
an active muscle. Perhaps it is to be sought for in an as yet unknown decom- 
position-product of glycogen (Luchsinger). [There is more glycogen in the red 
than in the pale muscles of a rabbit.] 
[The question as to whether the glycogen of muscle is carried from the liver by the blood- 
stream to the muscles, or whether it is formed in the muscles themselves, has been answered in 
various ways. Kiilz observed in frogs whose livers were removed, that the amount of glycogen 
in the muscles increased after subcutaneous injection of sugar. The muscles also retain their 
glycogen for a longer time than does the liver during starvation. These facts indicate that the 
glycogen is formed in the muscles themselves. The normal circulation is one of the conditions 
for glycogenesis of muscle, for ligature of all the vessels of a muscle is followed by diminution 
of its glycogen.] 
[The muscle-glycogen is not so rapidly used up during starvation as that of 
the liver (p. 327). It is undoubtedly diminished during muscular work. 
Although removal of the liver diminishes the muscle-glycogen, this does not 
prove that the muscle-glycogen is derived from the hepatic glycogen. Section 
of a motor nerve to a muscle results in an accumulation of the glycogen in the 
muscle.] 
5. Extractives.—An active muscle contains less extractive substances solu- 
ble in water, but more extractives soluble in alcohol (v. Helmholtz, 1845); d 
also contains less of the substances which form C02 (Ranke); less fatty acids 
(Sczelkow); less kreatin and kreatinin (v. Volt). 
6. During contraction, the amount of water in the muscular tissue increases, 
while that of the blood is correspondingly diminished (y. Ranke). The solid 
substances of the blood are increased, while they (albumin) are diminished in 
the lymph (Fano). 
7. Urea.—The amount of urea excreted from the body is not materially 
increased during muscular exertion (v. Volt, Fick, and Wislicenus). Accord- 
ing to Parkes, however, although the excretion of urea is not increased imme- 
diately, yet after 1 to day there is a slight increase. The amount of work 
done cannot be determined from the amount of albumin which is changed into 
urea. 
[Relation of Muscular Work to Urea.—Ed. Smith, Parkes, and others have made numer- Sec. 294.] 
SOURCE OF MUSCULAR ENERGY. 
595 
ous investigations on this subject. Fick and Wislicenus (1866) ascended the Faulhorn,—one of 
the Swiss Alps, 1956 metres high. The actual amount of energy expended in the form of muscu- 
lar movement was obtained by multiplying the body-weight of each experimenter by the height 
which each climbed. This in the case of Fick was 66 kilos, x 1956= 129,096 kilogrammetres, 
and that of Wislicenus was 76 X 1956= 148,656 kilogrammeters. On calculating the amount of 
energy obtainable from the decomposition of all the albuminous material used up, this only gave 
66,690 kilogrammetres for Fick and 68,376 for Wislicenus, i.e., only about the half of the energy 
expended. It was plain, therefore, that the proteids were not the sole source of the energy 
expended, and also that the quantity of urea excreted was not in proportion to the work done. 
For seventeen hours before and for six hours after the ascent no proteid food was taken—the 
diet consisting of cakes made of fat, sugar, and starch. The urine was collected in three periods 
as follows:— 
Pick. 
Wislicenus. 
1. Urea of 11 hours before the ascent, . 
2. “ 8 “ during “ 
3. “ 6 “ after “ 
238.55 grs. 
109.44 “ \ „ 
80.33 “ 1 89-77 
221.05 grs- 
“ } i83-35 
A hearty meal was taken after this period, and the urine of the next eleven hours after the 
period of rest contained 159.15 grains of urea {Pick), and 176.71 ( Wislicemis). All the experi- 
ments go to show that the amount of urea excreted in the urine is far more dependent upon the 
nitrogen ingested, i.e., the nature of the food, than upon the decomposition of the muscular 
substance. A vegetable diet diminishes, while an animal diet greatly increases, the amount of 
urea in the urine. North’s researches confirm those of Parkes, but he finds that the disturbance 
produced by severe muscular labor is considerable. The elimination of phosphates is not 
affected, while the sulphates in the urine are increased.] 
According to Argutinsky, who conducted his experiments under Pfliiger’s direction, increased 
muscular exertion (mountain climbing) causes a considerable increase in the elimination of N 
by the urine, which may last for three days. On calculating from the increased amount of N the 
amount of albumin that must have been decomposed in the body during the increased work- 
period, it was found that a very considerable amount of the work must have been due to the 
decomposition of proteids. J. Munk, however, challenges the correctness of these results on the 
ground that the experimenter was not in a satisfactory condition as regards nutrition. 
During the activity of a muscle, all the groups of the chemical substances 
present in muscle undergo more rapid transformations (J. Ranke). It is still a 
matter of doubt, therefore, whether we may assume that the kinetic energy of a 
muscle is chiefly due to the transformation of the chemical energy of the carbohy- 
drates which are decomposed or used up in the process of contraction. As yet 
we do not know whether the glycogen is supplied by the blood-stream to the 
muscles, perhaps from the liver, or whether it is formed within the muscles 
themselves from some unknown derivative of the proteids. The normal circu- 
lation is certainly one of the conditions for the formation of glycogen in 
muscle, as glycogen diminishes after ligature of the blood-vessels ( Chandelon). A 
muscle in which the blood circulates freely is capable of doing more work than 
one devoid of blood, and even in the intact body, more blood is always sup- 
plied to the contracted muscles. 
[Sources of Muscular Energy.—The experiment of Fick and Wislicenus 
definitely proved that the proteids are not the exclusive, or by any means the 
chief, source of muscular energy. As it is conclusively proved that during 
muscular work there is a great increase in the amount of O absorbed, and C02 
given off, it is evident that the non-nitrogenous substances of the food must be 
the chief sources of this energy. We turn naturally to the carbohydrates, and 
as the latter are chiefly stored up in the form of glycogen in the muscles, it is as- 
sumed that glycogen is the chief source of the energy. Glycogen in muscle dimin- 
ishes during muscular work, and is stored up during rest {Bernard). Kiilz also 
found that in dogs the glycogen disappears from the liver during work, and 
Voit found that the muscle-glycogen disappears before that in the liver. But 
frog’s muscles still contract, and do work, although they may contain no gly- 596 
[Sec. 294. 
RIGOR MORTIS. 
cogen. It appears, therefore, that the carbohydrates are a source of muscular 
energy. But they, again, are not the only source. It is highly probable that 
glycogen can be formed from proteids, and it is allowable, therefore, to assume 
that proteids may also serve as a source of muscular energy. If this be not so, 
it is difficult to understand how carnivora can be fed and maintained in good 
health for long periods on lean flesh. The fats are probably also another source. 
Hence it would appear that all three of the chief groups of food-stuffs—carbo- 
hydrates, proteids, and fats—may serve as the source of muscular energy ; but 
that, so long as non-nitrogenous elements are supplied in the food in sufficient 
quantity, or are stored up in the body, the muscles do their woi*k chiefly on 
these. After they are used up, the proteids are, as it were, called up.] 
[The metabolism of muscle appears to be regulated by the central nervous 
system (Pflilger, Zuntz). Even when at rest in the ordinary sense, i. e., when 
the muscles are not doing any mechanical work, the muscle is in a condition 
which Zuntz and Rohrig have called “ chemical tonus.” It appears to be a 
reflex tonus, so that it can be set aside by severing the connection between the 
muscle and the central nervous system, and this may be done either by section 
of the motor nerve, or by the action of curare.] 
295.—RIGOR MORTIS.—Cause.—Excised striped, or smooth muscles, 
and also the muscles of an intact body, at a certain time after death, pass into 
a condition of rigidity—cadaveric rigidity or rigor mortis. When all the 
muscles of a corpse are thus affected, the whole cadaver becomes completely 
stiff or rigid. The cause of this phenomenon depends upon the spontaneous 
coagulation of a proteid, viz., the myosin within the sarcolemmas of the mus- 
cular fibres (.Kiihne). Under certain circumstances the coagulation of the 
other proteids of the muscle may increase the rigidity. During the process of 
coagulation, an acid is formed, heat is set free (v. Walther, Fick—§ 223), 
owing to the passage of the fluid myosin into the solid condition, and also to 
the simultaneous and subsequently increased density of the tissue. 
Properties of a Muscle in Rigor Mortis.—It is shorter, thicker, and 
somewhat denser (Schmulewitsch); stiff, compact, and solid ; turbid and 
opaque (owing to the coagulation of the myosin); incompletely elastic, less 
extensible, and more easily torn or ruptured; it is completely inexcitable to 
stimuli; the muscular electrical current is abolished (or there is a slight current 
in the opposite direction), [a dead muscle is negatively electrical to a living 
one], its reaction is acid, owing to the formation of both forms of lactic acid 
(§ 293), and glycero-phosphoric acid (Diakanow) ; while it also develops free 
C02. When an incision is made into a rigid muscle, a fluid, the muscle-serum, 
appears spontaneously in the wound (§ 293). 
The first formed lactic acid converts the salts of the muscle into acid salts; thus, potassium 
lactate and acid potassium phosphate are formed from potassium phosphate. The lactic acid, 
which is formed thereafter, remains free and ununited in the muscle. 
Amount of Glycogen.—The newest observations of Bohm are against the view that, during 
rigor mortis, a partial or complete transformation of the glycogen into sugar and then into lactic 
acid takes place. During digestion, a temporary storage of glycogen occurs in the muscles as 
well as in the liver, so that about as much is found in the muscles as in the liver. There is 
no diminution of the glycogen when rigidity takes place, provided putrefaction be prevented; so 
that the lactic acid of rigid muscles cannot be formed from glycogen, but more probably it is 
formed from the decomposition of the albuminates (Demant, Bohm). 
The amount of acid does not vary, whether the rigidity occurs rapidly or slowly (J. Ranke); 
when acidification begins, the rigidity becomes more marked, owing to the coagulation of the 
alkali-albuminate of the muscle. Less C02 is formed from a rigid muscle the more C02 it has 
given off previously, during muscular exertion. A rigid muscle gives off N, and absorbs O. In 
a cadaveric rigid muscle, fibrin-ferment is present [At. Schmidt and others). It seems to be a 
product of protoplasm, and is never absent where this occurs (Rauschenbach). [The myosin- 
ferment seems not to be identical with the fibrin-ferment (p. 591).] Sec. 295.] 
RIGOR MORTIS. 
597 
[Rigor Mortis and Coagulation of Blood.—Thus there is a marked 
analogy between the coagulation of the blood and that of muscle. In both 
cases, a fluid body yields a solid body, fibrin from blood, and myosin from 
muscle; the coagulation of blood is prevented by neutral salts, and so is the 
coagulation of myosin ; dilution of the salted plasma produces coagulation in 
both cases; and perhaps the coagulation in both is due to the action of a fer- 
ment, the one the fibrin-ferment, the other the myosin-ferment. There are, 
however, points of difference, for myosin can be dissolved, reprecipitated, and 
coagulated several times, while fibrin does not undergo recoagulation; the for- 
mation of myosin from myosinogen, again, is accompanied by the development 
of an acid, whereas that of fibrin from fibrinogen is not; further, the formation 
of myosin is not accompanied by the formation of another globulin, whereas 
that of fibrin from fibrinogen is.] 
Stages of Rigidity.—Two stages are recognizable in cadaveric muscles : In 
the first stage, the muscle is rigid, but still excitable; in this stage the myosin 
seems to be in a jelly-like condition. Restitution is still possible during this 
stage. In the second stage, the rigidity is well pronounced, with all the 
phenomena above mentioned. 
The onset of the rigidity varies in man from ten minutes to seven hours 
[but as a rule it is complete within four to six hours after death. The muscles 
of the jaws are first affected, then those of the neck and trunk, afterwards (as a 
rule) the lower limbs, and finally the upper limbs]. Its duration is equally 
variable—one to six days. After the cadaveric rigidity has disappeared, the 
muscles, owing to further decompositions and an alkaline reaction, become soft, 
and the rigidity disappears (Nysteri). The onset of the rigidity is always pre- 
ceded by a loss of nervous activity. Hence, the muscles of the head and neck 
are first affected, and the other muscles in a descending series (§ 352). Disap- 
pearance of the rigidity occurs first in the muscles first affected (Nysten). Great 
muscular activity before death (e.g., spasms of tetanus, cholera, strychnin, or 
opium poisoning) causes rapid and intense rigidity; hence, the heart becomes 
rigid relatively rapidly, and strongly. Hunted animals may become affected 
within a few minutes after death. Usually the rigidity lasts longer the later it 
occurs. Rigidity does not occur in a foetus before the seventh month of intra- 
uterine life. A frog’s muscle cooled at o° C. does not begin to exhibit cadav- 
eric rigidity for four to seven days. 
Stenson’s Experiment.—The amount of blood in a muscle has a 
marked effect upon the onset of the rigidity. Ligature of the muscular arteries 
causes at first in all mammals an increase of the muscular excitability, and then 
a rapid fall of the excitability (SchmulewitscK); thereafter stiffness occurs, the 
one stage following closely upon the other (Swammerdam, Nic. Stenson, 1667). 
[If the ligature be removed in the first stage, the muscle recovers, but in the 
later stages the rigidity is permanent.] If the artery going to a muscle be 
ligatured, Stannius observed that the excitability of the motor nerves disap- 
peared after an hour, that of the muscular substance after four to five hours, 
and then cadaveric rigidity set in. 
Pathological.—When the blood-vessels of a muscle are occluded, by coagulation taking 
place within them, rigidity of the muscles is produced (§ 102). True cadaveric rigidity may be 
produced by too tight bandaging; the muscles are paralyzed, rigid, and break up into flakes, 
while the contents of the fibre are afterwards absorbed (R. Volkmann). Occlusion of the blood- 
vessels of muscles by infarcts, especially in persons with atheromatous arteries, may even cause 
necrosis of the muscles implicated (Finch, Girandeau). In a completely anaemic limb, the 
sensory nerves are still excitable for 5-10 hours (Stefani). 
If the circulation be re-established during the first stage of the rigidity, 
the muscle soon recovers its excitability (Stannius). When the second stage 598 
CONDITIONS MODIFYING RIGOR MORTIS. 
[Sec. 295. 
has set in, restitution is impossible (Kiihne). In cold-blooded animals, cada- 
veric rigidity does not occur for several days after ligaturing the blood-vessels. 
Brown-Sequard, by injecting fresh oxygenated blood into the blood-vessels, 
succeeded in restoring the excitability of the muscles of a human cadaver four 
hours after death, i. e., during the first stage of cadaveric rigidity. Ludwig 
and Al. Schmidt found that the onset of cadaveric rigidity was greatly retarded 
in excised muscles, when arterial blood was passed through their blood-vessels. 
Blood deprived of its O did not produce this effect. Cadaveric rigidity occurs 
relatively early after severe hemorrhage. If a weak alkaline fluid be perfused 
through the blood-vessels of the dead muscles of a frog, cadaveric rigidity is 
prevented (Schipiloff). 
Section of Nerves.—Preliminary section of the motor nerves causes 
a later onset of the rigidity in the corresponding muscles (.Brown-Sequard, 
Heineke). [The same result occurs after a hemi-section of the spinal-cord or 
after removal of one cerebral hemisphere (.Bierfreund).~\ In fishes, whose 
medulla oblongata is suddenly destroyed, cadaveric rigidity occurs much more 
slowly than in those animals that die slowly (Blane). 
[Other Influences.—Rigidity begins much later in the red (n to 15 hours) than in pale 
muscles (1 to 3 hours post-mortem); the rigor is complete in the white muscles in 10 to 14 
hours, in the red in 52 to 58 hours. The extent of shortening due to the rigor is 2 to 2times 
as great as in the white. In both muscles the resolution of the rigor begins 12 to 15 hours after 
the completion of the rigidity, so that the red muscles are not completely rigid before the other 
muscles appear to have passed from a state of rigidity. Temperature has a marked effect, but it 
acts more on the resolution than on the onset of the rigor. At 6o° C. the onset begins almost 
at once, and is complete in a few minutes (Bierfreund). Ether and chloroform injected into 
the blood-vessels cause almost instantaneous rigor (Kussmaul) ] 
Rigidity may be produced artificially by various reagents :— 
1. Heat [“ Heat-stiffening”] causes the myosin to coagulate at 40° C. 
in cold-blooded animals, in birds about 530 C., and in mammals at 48° to 50° 
C. The protoplasm of plants and animals, e. g., of the amoeba, is coagulated 
by heat, giving rise to heat-rigor. 
Schmulewitsch found that the longer a muscle had been excised from the body, the greater 
was the heat required to produce stiffening. Heat-stiffening differs from cadaveric rigidity 
thus: a 13 per cent, solution of ammonium chloride dissolves out the myosin from a cadaveric 
rigid muscle, but not from one rendered rigid by heat (Schipiloff). If the rigid cadaveric 
muscles of a frog be heated, another proteid coagulates at 450, and lastly at 750 the serum- 
albumin itself. Hence, both processes together make the muscle more rigid (§ 295). 
2. When a muscle is saturated with distilled water it produces “ water- 
stiffening ”—an acid reaction being developed at the same time. 
Muscles rendered stiff by water still exhibit electromotive phenomena, while muscles rendered 
rigid by other means do not (Biedermann). If the upper limb of a frog be ligatured, deprived 
of its skin, and dipped in warm water, it becomes rigid. If the ligature be removed and the 
circulation re-established, the rigidity may be partially set aside. If there be well-marked 
rigidity, it can only be set aside by placing the limb in a 10 per cent, solution of common salt, 
which dissolves the coagulum of myosin (Preyer). 
3. Acids, even C02 rapidly produce “ acid-stiffening,” which is probably 
different from ordinary stiffening, as such muscles do not evolve any free C02 
(Z. Herniatin'). The injection of 0.1 to 0.2 percent, solutions of lactic or 
hydrochloric acid into the muscles of a frog produces stiffening at once, which 
may be set aside by injecting 0.5 per cent, solution of an acid, or by a solution 
of soda, or by 15 per cent, solution of ammonium chloride. The acids form 
a compound with myosin (Schipiloff). [The stiffening produced by acids and 
hot water is quite different from the spontaneous rigor occurring after death]. 
4. Freezing and thawing a part alternately rapidly produce stiffening ; 
and it is aided by mechanical injuries. Sec. 295.] 
MUSCULAR EXCITABILITY. 
599 
Poisons.—Rigor mortis is favored by quinine, cafiein, digitalin [a concentrated solution of 
caffein or digitalin, applied to the muscle of a frog, produces rigor mortis], veratrin, hydrocyanic 
acid, ether, chloroform, the oils of mustard, fennel, and aniseed; direct contact of muscular 
tissue with potassium sulphocyanide (Bernard, Setschenow), ammonia, alcohol, and metallic 
salts. 
Position of the Body.—The attitude of the body during cadaveric rigidity is generally that 
occupied at death; the position of the limbs is the result of the varying tensions of the different 
muscles. During the occurrence of rigor mortis, a limb, or more frequently the arm and fingers, 
may move (Sommer). Thus, if stiffening occurs rapidly and firmly in certain groups of muscles, 
this may produce movements, as is sometimes seen in cholera. If cadaveric rigidity occurs very 
rapidly, the body may occupy the same position which it did at the moment of death, as some- 
times happens on the battle-field. In these cases it does not seem that a contracted condition of 
the muscle passes at once into rigor mortis; but between these two conditions, according to 
Briicke, there is always a very short relaxation. 
Muscles which have been plunged into boiling water do not undergo rigor mortis, neither do 
they become acid (Du Bois-Reymond), nor evolve free C02 (L. Hermann). 
Work done during Rigidity.—A muscle in the act of becoming stiff will lift a weight, but 
the height to which it is lifted is greater with small weights, less with heavier weights, than 
when a living muscle is stimulated with a maximal stimulus. 
Analogy between Contraction and Rigidity.—L. Hermann has drawn 
attention to the analogy which exists between a muscle in a state of contraction 
and one in a state of cadaveric rigidity—both evolve C02 and the other acids 
from the same source; [both acts take place without the consumption of O]. 
The form of the contracted and of the stiffened muscles is shorter and thicker ; 
both are denser, less elastic, and evolve heat; in both cases the muscular con- 
tents behave negatively as regards their electromotive force, in reference to the 
unaltered, living, resting substance. Hence he is inclined to regard a muscular 
contraction as a temporary, physiological, rapidly disappearing rigor. Rigor 
mortis is in a certain sense the last flickering act of a living muscle, [and he 
regards contraction as partial death of a muscle. But this is no explanation, 
and moreover there are important points of difference. We have no proof of 
a coagulum being formed during contraction, while the extensibility is increased 
during contraction and much diminished during rigor.] 
Disappearance of Rigidity.—When rigor mortis passes off, there is a 
considerable amount of acid formed in the muscle, which dissolves the coagu- 
lated myosin. After a time putrefaction sets in, accompanied by the presence 
of micro-organisms and the evolution of ammonia and putrefactive gases (H2S, 
N, C02—§ 184). [Hermann and Bierfreund attach much importance to the 
resolution of rigor mortis independently of putrefaction.] 
According to Onimus, the loss of excitability which precedes the onset of rigor mortis 
occurs in the following order in man : left ventricle, stomach, intestine (55 minutes); urinary 
bladder, right ventricle (60 min.); iris (105 min.); muscles of face and tongue (180 min.); the 
extensors of the extremities (about one hour before the flexors); the muscles of the trunk (five 
to six hours). The oesophagus remains excitable for a long time (§ 325). 
296. MUSCULAR EXCITABILITY.—By the term excitability or 
irritability of a muscle is meant that property of a muscle in virtue of which 
it responds to stimuli, at the same time becoming shorter and correspondingly 
thicker. The condition of excitement is the active condition of a muscle pro- 
duced by the application of stimuli, and is usually indicated by the act of con- 
traction. Stimuli are simply various forms of energy, and they throw the 
muscle into a state of excitement, while at the moment of activity the chemical 
energy of the muscle is transformed into work and heat, so that stimuli act as 
“liberating” or “discharging forces.” [These “discharging forces” 
may themselves be very feeble, but they are capable of causing the manifesta- 
tion of the transformation of a large amount of energy.] The normal tem- 
perature of the body is most favorable for maintaining the normal muscular 
excitability; the excitability varies as the temperature rises or falls. 600 
[Sec. 296. 
ACTION OF CURARE. 
As long as the blood-stream within a muscle is uninterrupted, the first 
effect of stimulation of a muscle is to increase its energizing power, partly be- 
cause the circulation is more lively and the blood-vessels are dilated, but after a 
time, the energizing power is diminished. Even in excised muscles, espe- 
cially when the large nerve-trunks have already lost their excitability, the 
excitability is increased after a stimulus, so that the application of a series of 
stimuli of the same strength causes a series of contractions which are greater 
than at first ( Wundt). Hence, we account for the fact that, although the first 
feeble stimulus may be unable to discharge a contraction, the second may, be- 
cause the first one has increased the muscular excitability (Fick). 
Effects of Cold.—If the muscles of a frog or tortoise be kept in a cool place, they may 
remain excitable for ten days, while the muscles of warm-blooded animals cease to be excitable 
after one and a half to two and a half hours. (For the heart, see § 55.) A muscle, when stimu- 
lated directly, always remains excitable for a longer time when its motor nerve is already dead. 
Muscles just beginning to become dry exhibit excessive irritability. 
[Independent Muscular Excitability.—Since the time of Albrecht v. 
Haller, and R. Whytt, physiologists have ascribed to muscle a condition of 
excitability which is entirely independent of the existence of motor nerves, 
but is dependent on certain constituents of the sarcous substance. Excitability, 
or the property of responding to a stimulus, is a widely-distributed function of 
protoplasm or its modifications. A colorless blood-corpuscle or an amoeba is 
excitable, and so are secretory and nerve-cells. In the first case, the applica- 
tion of a stimulus results in motion in an indefinite direction, in the second in 
the formation of a secretion, and in the third in the discharge of nerve-energy. 
In the case of muscle, a stimulus causes movement in a definite direction, called 
a contraction, and depending on the contractility of the sarcous substance. 
There are many considerations which will show that excitability is independent of 
the nervous system, although in the higher animals, nerves are the usual medium 
through which the excitability is brought into action. Plants, however, are 
excitable, and they contain no nerves.] 
Numerous experiments attest the “ independent excitability ” of muscle : 
1. There are chemical stimuli, which do not cause movement when applied to 
motor nerves, but do so when they are applied directly to muscle ; ammonia, 
lime water, carbolic acid. 2. The ends of the sartorius of the frog, in which 
no nerve-terminations (fig. 387) are observable by means of the microscope, con- 
tract when they are stimulated directly (Kilhne). 3. Curare paralyzes the ex- 
tremities of the motor nerves, while the muscles themselves remain excitable 
( Cl. Bernard, Kolliker). The action of cold, or arrest of the blood-supply in an 
animal, abolishes the excitability of the nerves, but not of the muscles at the 
same time. 4. After section of its nerve, a muscle still remains excitable, 
even after the nerves have undergone fatty degeneration (.Brown-Sequard, 
Bidder). 5. Sometimes electrical stimuli act only upon the nerves and not 
upon the muscle itself (Brileke). [6. The foetal heart contracts rhythmically 
before any nervous structures are discoverable in it.] 
[The Action of Curare.—Curare, woorali, urari, or Indian arrow-poison of South America, 
is the inspissated juice of the Strychnos crevauxi. A watery extract of the drug, when injected 
under the skin or into the blood of an animal, acts chiefly upon the motor nerve-endings, and 
does not affect the muscular contractility. An active substance, curarin, has been isolated from 
it (p. 604). Poison a frog by injecting a few milligrammes into the dorsal lymph-sac. In a few 
minutes after the poison is absorbed, the animal ceases to support itself on its fore-limbs; it lies 
flat on the table, its limbs are paralyzed, and so are the respiratory movements in the throat. 
When completely under the action of the poison, the frog lies in any position, limp and 
motionless, neither exhibiting voluntary nor reflex movements. If the brain be destroyed and the 
skin removed, on faradizing the sciatic nerve, no contraction of the muscle of the hind-limb 
occurs, but if the electrical stimulus be applied directly to the muscles, they contract, thus prov- Sec. 296.] 
ACTION OF CURARE. 
601 
ing that curare poisons the motor connections and not the muscles. If the dose be not too 
large, the heart still continues to beat, and the vaso-motor nerves remain active.] 
[Methods.—(i) Local Application.—Bernard took two nerve-muscle 
preparations, put some solution of curare into two watch-glasses, and dipped 
the nerve into one glass and the muscle of the other preparation into the other 
glass. The curare penetrated into both preparations, and he found, on stimu- 
lating the nerve which had been steeped in curare, that its muscle still con- 
tracted, so that the curare had not acted on the motor nerve-fibres; while 
stimulation of the nerve of the other preparation produced no contraction, al- 
though the corresponding muscle contracted. In the latter case, the curare 
had penetrated into the muscle and affected the intra-muscular portions of 
the nerve.] 
[(2) But it is the terminal or intra-muscular portions of the nerves, not 
the nerve-trunk, which are paralyzed. Ligature the sciatic artery, or, better 
still, tie all the parts 
of the hind-limb of 
a frog, except the 
sciatic nerve, at the 
upper part of the 
thigh (fig. 384). In- 
ject curare into the 
dorsal lymph-sac. 
The poisoned blood 
will, of course, circu- 
late in every part of 
the body except the 
ligatured limb. The 
shaded parts are trav- 
ersed by the poison. 
The animal can still, 
at a certain stage of 
the poisoning, pull 
up the non-poisoned 
limb, while it cannot 
move the poisoned 
one. At this time, 
although poisoned 
blood has circulated 
in the sacral and in- 
tra-abdominal parts 
of the nerves, yet 
they are not paralyzed, so that the poison does not act on this part of the trunk 
of the nerve. But we can show that it does not act on any part of the extra- 
muscular trunk of the nerve. This is done by ligaturing the arteries going to 
the gastrocnemius muscle, and then poisoning the animal. On stimulating the 
nerve on the ligatured side, the gastrocnemius of that side contracts, although 
the whole length of the nerve-trunk was supplied by poisoned blood. There- 
fore it is the intra-muscular terminations of the nerves which are acted on.] 
[By means of the following arrangement we may prove that the terminal 
parts of the nerve are paralyzed. Ligature the sciatic artery of one leg of a 
frog, and then inject curare into a lymph-sac. After the animal is fully poi- 
soned, expose the sciatic nerve in both legs, leaving all the muscles below the 
knee joint, then clean and divide the femur at its middle. Pin a straw flag to 
each limb, and fix both femora in a clamp, with the gastrocnemii uppermost, 
Frog with sciatic artery 
ligatured. S. P., spinal 
cord with afferent and 
efferent nerves; P., 
poisoned, N. P., non- 
poisoned leg; M, gas- 
trocnemius muscle. 
Fig. 384. 
Fig- 385. 
Scheme of the curare experiment. B, 
battery; I, primary, II, secondary 
spiral; N, nerves; F, clamp; NP, 
non poisoned leg; P, poisoned leg; 
C, commutator; K, key. 602 
[Sec. 296. 
ACTION OF CURARE. 
as in fig. 385. Place the two nerves, N, on electrodes attached to two wires 
coming from a commutator, C (fig. 385). From the opposite binding-screws 
of the commutator, two wires pass to the gastrocnemii. The other two binding- 
screws of the commutator are connected with the secondary coil of an induc- 
tion machine (§ 330). The bridge of the commutator can be turned so as to 
pass the current either through both muscles or both nerves—the latter is the 
case in the diagram (H). When both nerves are stimulated, only the non- 
poisoned leg (NP) contracts. Reverse the commutator, and pass the current 
through both muscles, when both contract.'] 
[Rosenthal’s Modification.—Push the secondary coil far away from the primary, and pass 
the current through both muscles. Gradually approximate the secondary to the primary coil, 
and in doing so it will be found that the non-poisoned leg contracts first, but on continuing to 
push up the secondary coil, both limbs contract. Thus, the poisoned limb does not respond to so 
feeble a faradic stimulus as the non-poisoned one, a result which is not due to the action of the 
curare on the excitability of the muscle. The non-poisoned limb responds to a feebler stimulus 
Fig. 386.—Curve showing the excitability in the sartorius of a fiog in a normal and curarized 
muscle. Fig. 387.—Distribution of nerves in the sartorius of a frog and the curve of ex- 
citability in different parts of the muscle, i. e., the excitability is greatest where there are 
most nerve-endings, and lowest where there are none. 
Fig. 386. 
Fig- 387- 
because its motor-nerve terminations are not paralyzed while the poisoned leg does not do so, 
because the motor terminations are paralyzed. A feebler induced shock suffices to cause a 
muscle to contract when it is applied to the nerve, than when it is applied to the muscle itself 
directly. In large doses curare also affects the spinal cord (p. 604).] 
[On what structures does curare act ?—These experiments prove that curare does not 
paralyze the motor nerve-trunks, nor the muscular fibres, and that it acts on the motor termina- 
tions within the muscles, but they do not enable us to state the precise part of the nerve-ending 
so affected. It may act on (1) the nerve just before it pierces the sarcolemma, (2) the sub- 
lemmar axis-cylinder, (3) the end-plates, (4) the terminal branches or spray. Kiihne and Pol- 
litzer have made it probable that, even when a muscle is thoroughly impregnated with curare, 
some of the nervous apparatus is unaffected. The sartorius is most excitable where there are 
most nerves (fig. 387), and even in a muscle profoundly poisoned with curare, the distribution of 
excitability varies with the number of nerves in the several parts of the muscle (fig. 386) just as 
in a normal muscle, with this difference, that the excitability of all the parts of the muscle con- 
taining nerves is less than normal. That this variation in excitability is due to nervous struc- 
tures is shown by using a polarizing anelectrotonic current (g 335), which depresses the excita- 
bility of nerve-fibres, and then this difference of excitability disappears, the curve of excita- 
bility running parallel with the abscissa, so that the difference does not seem to be due to purely 
muscular causes.] Sec. 296.] 
MUSCULAR STIMULI. 
603 
[Pollitzer, speculating as to which part of the terminal nerve is affected, supposes that all 
parts beyond the last node of Ranvier retain their functions, and he supposes that it is not the 
axis-cylinders themselves, but the cement at the nodes, on which the drug exerts its specific 
action.] 
Neuro-Muscular Cells.—Even in the lower animals, e. g., Hydra and Medusae, there are 
unicellular structures called “ neuro-muscular cells,” in which the nervous and muscular sub- 
stances are represented in the same cell (Kleinenberg and Eimer). [This view, however, is 
very doubtful; the outer part of these cells is adapted for the action of stimuli, and corresponds 
to the nervous receptive organ, while the inner deeper part is contractile, and is the representa- 
tive of the muscular part.] 
Muscular Stimuli.—Various stimuli cause a muscle to contract, either by 
acting upon its motor nerve, or upon the muscular substance itself (§ 324). 
[The former is called indirect stimulation, the latter direct stimulation.] 
1. Under ordinary circumstances, the normal stimulus exciting a muscle 
to contract is the nerve impulse which passes along a nerve, but its exact 
nature is unknown. 
2. Chemical Stimuli.—All chemical substances which alter the chemical 
composition of a muscle with sufficient rapidity act as muscular stimuli. Min- 
eral acids (HC1 0.1 per cent.), acetic and oxalic acids, the salts of iron, zinc, 
copper, silver, and lead, bile, all act in weak solutions as muscular stimuli; they 
act upon the motor nerve only when they are more concentrated. Lactic acid 
and glycerin, when concentrated, excite only the nerve; when dilute, only the 
muscle. [The lower end of the sartorius, which contains no nerves, may be 
dipped into glycerin, and it will not contract, but if it be dipped deeper to 
where there are nerve-endings, it will contract at once.] Neutral alkaline salts 
act equally upon nerve and muscle ; alcohol and ether act on both very feebly. 
When water is injected into the blood-vessels, it causes fibrillar muscular con- 
tractions (v. WitticK), while a 0.6 per cent, solution of NaCl may be passed 
through a muscle for days without causing contraction (.Kdlliker, O. JVasse). 
[Carslaw, under Ludwig’s direction, however, found that solutions containing 
0.5 to 0.2 per cent. NaCl, when perfused through the muscles of a frog, excite 
many short, powerful attacks of tetanus, separated from each other by periods 
of rest. Solutions containing 0.5 to 0.7 per cent. NaCl, i. e., so-called “in- 
different fluids” or “normal saline,” are not without influence, but of all 
known saline solutions, they injure a nerve-muscle preparation least. Solutions 
of 1 to 2 per cent, rapidly kill the muscle.] Acids, alkalies, and extract of 
flesh diminish the muscular excitability, while the muscular stimuli, in small 
doses, increase it {Ranke). Gases and vapors stimulate muscle ; they cause 
either a simple contraction (<?. g., HC1), or at once permanent contraction 
or contracture (e.g., Cl). Long exposure to the gas causes rigidity. The 
vapor of bisulphide of carbon stimulates only the nerves, while most vapors 
(e.g., HC1) kill without exciting them (.Kilhne and Jani). 
Method.—In making experiments upon the chemical stimulation of muscle, it is inadvisable 
to dip the transverse section of the muscle into the solution of the chemical reagent (Hering). 
The chemical stimulus ought to be applied in solution to a limited portion of the uninjured 
surface of the muscle; after a few seconds we obtain a contraction or fibrillar twitchings of the 
superficial muscular layers (Hering). 
[Rhythmical Contraction.—While rhythmical contractions are very marked in smooth mus- 
cle (especially if it is stretched or subjected to considerable internal pressure, as in the hollow 
viscera), e.g., the intestine, uterus, ureter, blood-vessels, and also in the striped but involuntary 
cardiac musculature (§ 58), they are not, as a rule, very common in striped voluntary muscle. 
Chemical stimuli are particularly effective in producing them.] If the sartorious of a curarized 
frog be dipped into a solution composed of 5 grms. NaCl. 2 grms. alkaline sodium phosphate, 
and 0.5 grm. sodium carbonate in 1 litre of water, at io° C.,the muscle contracts rhythmically, 
and may do so for several days, especially with a low temperature (Biedermann). This recalls 
the rhythmical contraction of the heart. [Kilhne found a similar result. The rhythm is arrested 
by lactic acid and restored by an alkaline solution of NaCl.] Rhythmical movements may also 
be induced in the sartorius (frog), by the combined action of a dilute solution of sodic carbonate 604 
[Sec. 296. 
MUSCULAR STIMULI. 
and an ascending constant electrical current. Compare also the action of a constant current on 
the heart ($ 58). 
3. Thermal Stimuli.—If an excised frog’s muscle be rapidly heated to 28° 
C., a gradually increasing contraction occurs, which, at 30° C., is more pro- 
nounced, reaching its maximum at 450 C. If the temperature be raised, 
“heat-stiffening” rapidly ensues. The smooth muscles of warm-blooded 
animals also contract when they are warmed, but those of cold-blooded ani- 
mals are elongated by heat (Grilnhagen). If a frog’s muscle be cooled to o°, 
it is very excitable to mechanical stimuli (Griinhageti); it is even excited by a 
temperature under o° (Eckhard). 
Cl. Bernard observed that the muscles of animals, artificially cooled, remained excitable many 
hours after death (§ 225). Heat causes the excitability to disappear rapidly, but increases it 
temporarily. 
4. Mechanical Stimuli.—Every kind of sudden mechanical stimulus, 
provided it be applied with sufficient rapidity to a muscle (and also to a nerve), 
causes a contraction. If stimuli of sufficient intensity be repeated with suffi- 
cient rapidity, tetanus is produced. Strong local stimulation causes a weal-like, 
long-continued contraction at the part stimulated (§ 297, 3, a). Moderate 
tension of a muscle increases its excitability. 
5. Electrical Stimuli will be referred to when treating of the stimulation 
of nerve (§ 324). 
Other Actions of Curare.—When it is injected into a frog, either into the blood or sub- 
cutaneously, it causes at first paralysis of the intra-muscular ends of the motor nerves (p. 601), 
while the muscles themselves remain excitable. The sensory nerves, the central nervous system, 
viscera, heart, intestine, and the blood-vessels are not affected at first (Cl. Bernard, Kolliker). 
[If the skin be stimulated, the frog pulls up the ligatured leg reflexly, although the other leg 
remains quiescent; this shows that the sensory nerve and nerve-centres are still intact; but 
when the action of the drug is fully developed, no amount of stimulation of the skin or the pos- 
terior roots of the nerves will give rise to a reflex act, although the motor nerve of the ligatured 
limb is known to be excitable; hence it is probable that the nerve-centres in the cord themselves 
are ultimately affected. If the dose be very large, the heart and blood-vessels are affected.] In 
warm-blooded animals death takes place by asphyxia, owing to paralysis of the diaphragm, 
but of course there are no spasms. In frogs, where the skin is the most important respiratory 
organ, if a suitable dose be injected subcutaneously, the animal may remain motionless for days 
and yet recover, the poison being eliminated by the urine (Kiihne). If the dose be large, the 
inhibitory fibres of the vagus may be paralyzed. In electrical fishes, the sensory nerves, and in 
frogs, the lymph-hearts, are paralyzed. A dose sufficient to kill a frog, when injected under its 
skin, will not do so if administered by the mouth, because the poison seems to be eliminated as 
rapidly by the kidneys as it is absorbed from the gastric mucous n embrane. For the same rea- 
son the flesh of an animal killed by curare is not poisonous when eaten. If, however, the ureters 
be tied, the poison collects in the blood, and poisoning takes place (L. Hermann). [In this case 
the mammal may exhibit convulsions. Why? Curare paralyzes the respiratory nerves, so that 
asphyxia is produced from the venosity of the blood. It affects the respiratory nerve-endings 
before those in the muscles generally, so that when the venous blood stimulates the nerve-centres, 
the partially affected muscles respond by convulsions. Other narcotics may excite convulsions 
indirectly by inducing a venous condition of the blood, while the motor centres, nerves, and 
muscles are still unaffected.] Large doses, however, poison uninjured animals even when given 
by the mouth. The nerves and muscles of poisoned animals exhibit considerable electromotive 
force. [For the effect of curare on lymph-formation ($ 199, 6).] 
Atropin appears to be a specific poison for smooth muscular tissue, but different muscles 
are differently affected (Szpilmann, Luchsinger). [This is doubtful. A small quantity of 
atropin seems to affect motor nerves of smooth muscle in the same way that curare does those of 
striped muscle; we must remember, however, that there are no end-plates proper in the former, 
so that the link between the nerve-fibrils and the contractile substance is probably different in the 
two cases. It is well known that the amount of striped and smooth muscle varies in the oeso- 
phagus in different animals. Szpilmann and Luchsinger found that, after the action of atropin, 
stimulation of the peripheral end of the vagus will still cause contraction of the striped muscular 
fibres in the oesophagus, but not of the smooth fibres, although both forms of muscular tissue 
respond to direct stimulation.] 
After section of the motor nerve of a muscle, the excitability undergoes remarkable changes; 
after three to four days the excitability of the paralyzed muscle is diminished, both for direct Sec. 296.] 
CONTRACTION OF MUSCLE. 
605 
and indirect stimuli (p. 603); this condition is followed by a stage during which a constant 
current is more active than normal, while induced currents are scarcely or not at all effective 
(§ 339, !•)• The excitability to mechanical stimuli is also increased. The increased excitability 
occurs until about the seventh week; it gradually diminishes until it is abolished towards the 
sixth to the seventh month. Fatty degeneration begins in the second week after section of the 
motor nerve, and goes on until there is complete muscular atrophy. Immediately after section 
of the sciatic nerve, Sclimulewitsch found that the excitability of the muscles supplied by it was 
increased. 
297. CHANGES IN A MUSCLE DURING CONTRACTION. 
—I. Phenomena visible to the naked eye.—1. When a muscle contracts, 
it becomes shorter and at the same time correspondingly thicker. 
The degree of contraction, which in very excitable frogs may be 65 to 85 per cent. (72 per 
cent, mean) of the total length of the muscle, depends upon various conditions: (a) Up to a 
certain point, increasing the strength of the stimulus causes a greater degree of contraction; 
(b) as the muscular fatigue increases, i.e., after continued vigorous exertion, the stimulus 
remaining the same, the extent of contraction is diminished; (r) the temperature of the sur- 
roundings has a certain effect. The extent of the contraction is increased in a frog’s muscle— 
the strength of stimulus and degree of fatigue remaining the same—when it is heated to 
330 C. If the temperature be increased above this point, the degree of contraction is diminished 
(Sch mulewitsch). 
2. The volume of a contracted muscle is slightly diminished (Swammer- 
dam, \ 1680). Hence, the specific gravity of a contracted muscle is slightly 
increased, the ratio to the non-contracted muscle being 1062 : 1061 (Valen- 
tin') ; the diminution in volume is, however, only although this has 
recently been denied by J. Ewald. 
Methods.—(a) Erman placed portions of the body of a live eel in a glass vessel filled with 
an indifferent fluid. A narrow tube communicated with the glass vessel, and the fluid rose in 
the tube to a certain level. As soon as the muscles of the eel were caused to contract, the fluid 
in the index-tube sank. (6) Landois demonstrates the decrease in volume by means of a mano- 
metric flame. The cylindrical vessel containing the muscle is provided with two electrodes 
fixed into it in an air-tight manner. The interior of the vessel communicates with the gas 
supply, while there is a small narrow exit-tube for the gas, which is lighted. Every time the 
muscle contracts the flame diminishes. The same experiment may be performed with a con- 
tracting heart. 
3. Total and Partial Contraction.—Normally, all stimuli applied to a 
muscle or its motor nerve cause contraction in all its muscular fibres. Thus 
the muscle conducts the state of excitement to all its parts. Under certain 
circumstances, however, this is not the case, viz. : (a) when the muscle is 
greatly fatigued, or when it is about to die, violent mechanical stimuli, as a 
vigorous tap with the finger or a percussion hammer (and also chemical or 
electrical stimuli), cause a localized contraction of the muscular fibres. This 
is Schiff’s “ idio-muscular contraction.” The same phenomenon is ex- 
hibited by the muscles of a healthy man, when the blunt edge of an instrument 
is drawn transversely over the direction of the muscular fibres, (b) Under certain 
as yet but imperfectly known conditions, a muscle exhibits so-called fibrillar 
contractions, i. e., short contractions occur alternately in different bundles 
of muscular fibres. This is the case in the muscles of the tongue, after section 
of the hypoglossal nerve ) and in the muscles of the face, after section of the 
facial nerve (§ 349, 4). 
[In some phthisical patients there is marked muscular excitability, so that if the pectoral 
muscle be percussed, a local contraction—idio-muscular—occurs, either confined to the spot, or 
two waves may proceed outwards and return to the spot struck.] 
Cause of Fibrillar Contraction.—According to Bleuler and Lehmann, section of the hypo- 
glossal nerve in rabbits is followed by fibrillar contractions after sixty to eighty hours; these 
contractions may continue for months, even when the divided nerve has healed and is stimu- 
lated above the cicatrix so as to produce movements in the corresponding half of the tongue. 
Stimulation of the lingual nerve increases the fibrillar contractions or arrests them. This nerve 
contains vaso-dilator fibres derived from the chorda tympani. Schiff is of opinion that the 606 
[Sec. 297. 
increased blood-stream through the organ is the cause of the contractions. Sig. Mayer found 
that, by compressing the carotids and subclavian, and again removing the pressure so as to per- 
mit free circulation, the muscles of the face contracted. Section of the motor nerves of the face 
did not abolish the phenomenon, but compression of the arteries did. The cause of the phe- 
nomenon, therefore, seems to lie within the muscles themselves. This phenomenon may be com- 
pared to the paralytic secretion of saliva and pancreatic juice which follows section of the nerves 
going to these glands (pp. 255, 316). Similar fibrillar contractions occur in man under patho- 
logical conditions, but they may also occur without any signs of pathological disturbance. 
[Fibrillar contractions, due to a central cause, occur in monkeys after excision of the thyroid 
gland ($ 103, III). Some drugs cause fibrillar muscular contractions, e.g., aconitin, guanidin, 
nicotin, pilocarpin, but physostigmin produces them in warm-blooded animals (not in frogs). 
According to Brunton these drugs probably act by irritating the motor nerve-endings, as the 
contractions are gradually abolished by curare.] 
II. Microscopic Phenomena.—x. Single muscular fibrillcz exhibit the 
same phenomena as an entire muscle, in that they contract and become thicker. 
2. There is great difficulty in observing the changes that occur in the individual 
parts of a muscular fibre during the act of contraction. This much is certain, 
that the muscular elements become shorter and broader during contraction, and 
that the transverse striae approach nearer to each other (Bowman, 1840). 3. 
There is great difference of opinion as to the behavior of the doubly refractive 
(anisotropous) and the singly refractive media. 
Engelmann’s View.—Fig. 388, 1, represents a passive muscular element—from c to d is the 
doubly refractive contractile substance, with the median disc, a, b, in it; h and g are the 
lateral discs. Besides these, in each of the singly refractive discs there is a clear disc— 
“ secondary disc,” f and e, which is only slightly doubly refractive. This occurs only in the 
muscles of insects. Fig. 1, on the right, shows the same element in polarized light, whereby 
the middle area of the element, as far as the contractile substance proper extends, is, owing to 
its double refraction, bright; while the other part of the muscular element, owing to its being 
singly refractive, is black. Fig. 388, 2, is the transition stage, and 3 the proper stage of con- 
traction of the muscular element. In both cases the figures on the left are viewed in ordinary 
light, and on the right, in polarized light. According to Engelmann, during contraction (fig. 
388, 3), the singly refractive disc becomes as a whole more refractive, the doubly refractive less 
so. Consequently, a fibre at a certain degree of contraction (2), when viewed in ordinary light, 
may appear homogeneous and but slightly striped transversely — the homogeneous or transi- 
tion stage. During a greater degree of contraction (3), very dark transverse stripes reappear, 
corresponding to the singly refractive discs. At every 
stage of the contraction, as well as in the transition stage, 
the singly and doubly refractive discs are sharply de- 
fined, and are recognized by the polariscope as regular 
alternating layers (in 1, 2, and 3 on the right). These 
do not change places during the contraction. The height 
of both discs is diminished during contraction, but the 
singly refractive do so more rapidly than the doubly re- 
fractive discs. The total volume of each element does 
not undergo any appreciable alteration in volume during 
the contraction. Hence, the doubly refractive discs in- 
crease in volume at the expense of the singly refractive. 
From this it is concluded that, during the contraction, 
fluid passes from the singly refractive into the doubly 
refractive discs; the former shrink, the latter swell. 
[If a living portion of an insect’s muscle be examined 
in its own juice, contraction-waves may be seen to pass over 
the fibres. When a contraction-wave passes over part of 
the fibres, the discs become shorter and broader ; at the same time, in the fully contracted part, 
the dim disc appears lighter than the centre of the light disc. There is said to be a “ reversal 
of the stripes ” from what obtains in a passive muscle. Before this stage is reached, there is 
an intermediate stage where the two bands are almost uniform in appearance. According to 
Ranvier, however, who has examined the muscles of the retro-lingual membrane of the frog 
(p. 578), when a muscular fibre contracts, the stripes do not disappear nor are they reversed; the 
dim disc alone appears to be contractile, and it becomes shorter and broader. This disc, as it 
were, strives to assume a form with the smallest surface, i. e., to become spherical.] 
Methods.—These phenomena are best observed by “fixing” the different stages of rest or 
contraction, by suddenly plunging the muscular fibrillae of insects’ muscles into alcohol or osmic 
CONTRACTION OF MUSCLE. 
Fig. 388. 
The microscopic appearances during 
a muscular contraction in the indi- 
vidual elements of the fibrillae. x, 2, 
3 (after Engelmanri). Sec. 297.] 
MYOGRAPHS. 
607 
acid, which coagulates the muscle-substance. The actual contraction may be observed under the 
microscope in the transparent parts of the larvae of insects. 
Diffraction Spectrum.—A thin muscle, e.g., the sartorius of the frog, when placed directly 
behind a narrow slit running at right angles to the course of the fibres, yields a diffraction- 
spectrum. When the muscle contracts, as by mechanical stimulation, the spectrum broadens, 
a proof that the interspaces of the transverse stripes become narrower (Ranvier). 
298. MUSCULAR CONTRACTION.—Methods.—In order to 
determine the duration of each phase of a muscular contraction, myographs 
of various forms are used. 
V. Helmholtz’s Myograph is shown in fig. 389. A muscle, M—say the gastrocnemius of a 
frog attached to the femur—is fixed by the femur in a clamp, K; its lower end is attached to a 
movable lever carrying a scale-pan and weight, W, the weight being varied at pleasure. When 
the muscle contracts, necessarily it raises the lever. At the free end of the lever is a movable 
style, F, which inscribes its movements on a revolving cylinder caused to rotate at a uniform rate 
by means of clock-work. The cylinder is covered with smoked enamelled paper in the flame of 
a turpentine lamp. 
When the muscle contracts, it inscribes a curve—the “ muscle-curve ,” or 
“ myogram.” The abscissa of the curve indicates the duration of the 
contraction, but of course the rate at which the cylinder is moving must be 
known. The ordinates represent the height of contraction at any particular 
part of the curve. 
The muscle-curve may be inscribed upon a smoked glass plate attached to one limb of a 
vibrating tuning-fork. Such a curve registers the time units in all its parts. Suppose each vibra- 
tion of the tuning-fork = 0.01613 second, then the duration of any part of such a curve is ob- 
tained by counting the number of vibrations and multiplying by 0.01613 second. 
[Fick’s Pendulum Myograph.—A board fixed to the wall carries a heavy iron pendulum, 
P, whose axis, A, A, moves on friction rollers (fig. 390). At the lower swinging end are two 
glass plates, G and G/ fixed to a bearer, T. The plates can be adjusted by means of the screw, s, 
so that several curves can be written one 
above the other. The plate, G/, on the 
posterior surface is merely a compensator, 
so that, when G is elevated, G/ is lowered, 
and thus the duration of the oscillation is 
not altered. The spring catches, H, H, 
which can be turned inwards or outwards, 
are used to fix the pendulum by the teeth, 
a, a, when it is drawn to one side. The 
pendulum is drawn to one side and fixed, 
a, in H, so that when H is pulled down, 
it is liberated and swings to the other side, 
where it is caught by the detent H at the 
opposite side. In the improved form, the 
catches, H, are made to slide along a rod 
like the arc of a circle, so that the length 
of the swing can be varied. As the pen- 
dulum swings from one side to the other, 
the projecting points, a, a, knock over the 
contact key, b, and the current is opened 
and a shock transmitted to the muscle. 
The writing lever to which the muscle is 
attached is usually a heavy one, and a 
style writes upon the smoked surface of 
the glass. Of course, when the pendulum 
swings, it moves with unequal velocities at 
different parts of its course.] 
[When using the pendulum myograph to study a muscular contraction, arrange it as in fig. 
392. The frog’s muscle is attached to a writing lever, which is very like the lever in fig. 390, 
while the style inscribes its movements on the blackened plate.] 
[The pendulum is fixed in the catch, C, as shown in the figure; the key, K/, is closed and 
placed in the primary circuit, while two wires from the secondary coil of an induction machine 
are attached to the muscle. When the pendulum swings, the projecting tooth, S, knocks over 
the contact at K7, and breaks the primary circuit, when a shock is instantly transmitted through 
Scheme of v. Helmholtz’s myograph. M, muscle 
fixed in a clamp, K ; F, writing style; P, weight 
or counterpoise for the lever \ W, scale-pan for 
weights; S, S, supports for the lever. 
Fig. 389. 608 
VARIOUS MYOGRAPHS. 
[Sec. 298. 
the muscle. Before stimulating, allow the pendulum to swing to obtain an abscissa. The time 
is recorded by a vibrating tuning-fork, of known rate of vibration, connected with a Dupre’s 
electric chronograph. Dupre’s chronograph is merely a small electro-magnet with a fine writing- 
style attached, which vibrates when it is introduced in an electrical circuit, in which is placed a 
vibrating tuning-fork. The signal vibrates just as often as the tuning-fork.] 
[Du Bois-Reymond’s Spring Myograph.—It consists of a glass plate fixed in a frame, 
and moving on two polished steel wires, stretched between the supports A and B (fig. 393). At 
b is a spring which, when it is compressed between the upright, B, and the knob, <5, drives the 
glass plate from B to A. As the plate moves from one side to the other, a small tooth, d, on its 
under surface, opens the key, h, and thus a shock is transmitted to the muscle. The arrange- 
ment otherwise is the same as for the pendulum myograph. The smoked glass plate is liberated 
by the projecting finger plate attached to the upright, A.] 
[Marey’s Simple Myograph.—The gastrocnemius is attached to a horizontal lever, which 
inscribes its movements on a revolving cylinder. This form of myograph, when provided with 
two levers, is very useful for comparing the action of a poison on one limb, the other being un- 
poisoned.] 
[Pfliiger’s stationary form is 
simply a Helmholtz’s myograph (fig. 
389) arranged to record its movements 
on a stationary glass plate, so that the 
muscle merely makes a vertical line 
or ordinate instead of a curve; it thus 
merely indicates the height or extent 
of the contraction, not its duration.] 
A rapidly rotating disc was used 
by Valentin and Rosenthal for regis- 
tering the muscle-curve, while Harless 
used a plate which was allowed to fall 
rapidly, the so-called “ Fall-myo- 
graph.” In all these experiments it 
is necessary to indicate at the same 
time the moment of stimulation. 
[Moist-Chamber. — In studying 
the contraction of a muscle it should 
be kept under conditions as normal as 
possible. This is effected by suspend- 
ing it in a moist-chamber (fig. 391), 
the air of which is kept moist by means 
of a piece of blotting-paper moistened 
with normal saline.] 
Contraction - Curve of 
Human Muscle.—In man, 
another principle is adopted, 
viz., to measure the increase in 
thickness during the contrac- 
tion, either by means of a lever 
or a compressible tambour, such 
as is used in Brondgeest’s pan- 
sphygmograph (fig. 88). The 
thickening of the abductor mus- 
cles of the thumb may be regis- 
tered by means of Marey’s pince 
myographique (fig. 409). 
I. Simple Contraction. 
—If a single induction 
shock or stimulus of momentary 
duration be applied to a muscle, 
a “ simple muscular con- 
traction,” [or shortly, a con- 
traction or twitch] is the result, e., the muscle rapidly shortens and quickly 
returns again to its original relaxed condition. 
Fig. 390. 
Fick’s pendulum myograph, as improved by v. Helm- 
holtz (j natural size), side and front view. Sec. 298.] 
MUSCLE-CURVE. 
609 
Muscle-Curve or Myogram.—Suppose a single stimulus be applied to a 
muscle attached to a light writing-lever, which is not “over-weighted” with 
any weight attached to it, then, when the muscle contracts, the following events 
take place : — 
[(1) A period or stage of latent stimulation (figs. 394, 396). 
(2) A period of increasing energy or contraction. 
(3) A period of decreasing energy or more rapid relaxation. 
(4) A period of slow relaxation, or the elastic after-vibration.] 
The muscle-curve proper is composed of 2, 3, and 4. 
(1) The latent period (fig. 394, a, b') consists in this, that the muscle 
does not begin to contract precisely at the moment the stimulus is applied to it, 
Scheme of the arrangement of the pendulum 
myograph. B, battery; I, primary, II, 
secondary spiral of the induction machine; 
S, tooth; K/, key; C, C, catches or detents; 
K7 in the corner, scheme of I<7; K, key in 
primary circuit. The short-circuiting key 
in the secondary circuit is omitted. 
Fig. 392. 
A muscle chamber, C, for a frog’s 
muscle, the latter attached to Tiger- 
stedt’s recording lever, and the 
whole supported on a stand, S. 
(Made by Petzold, of Leipzig.) 
Fig. 391. 
but the contraction occurs somewhat later, i. e., a short, but measurable inter- 
val elapses between the application of a momentary stimulus and the contrac- 
tion (v. Helmholtz). If the entire muscle be stimulated by a momentary stimu- 
lus, e.g., a single break induction shock is found; the duration of the 
latent period is about o.oi second [/. e., when the muscle records its move- 
ments by means of a lever attached to the muscle]. In smooth muscle, the 
latent period may last for several seconds. 
[Although no change be visible in a muscle during the latent period, never- 
theless it has been held until quite recently that some change does take place 
within the muscle-substance, and it was maintained that the electrical current 
of the muscle is diminished during this period, or we have what is known as [Sec. 298. 
MUSCLE-CURVE. 
the negative variation of the muscle-current (Bernstein—§ 333).] [The re- 
cent careful experiments, however, of Burdon-Sanderson on frogs’ muscles, 
where the moment of stimulation, the electro-motive changes (determined by a 
capillary electrometer), and the change of muscular form, were all recorded 
simultaneously by photographic means, show that the electrical movement or 
Fig- 393- 
Spring myograph or “ shooter.” 
response, instead of preceding the mechanical change of form of the muscle, 
actually accompanies the latter (fig. 395). The theory, therefore, that the 
electrical variation precedes the actual muscular contraction and occurs during 
the latent period must be abandoned. Burdon-Sanderson has also shown that 
there is a true latent period in muscle which may be as short as 2y2 thousandths 
of a second = sec., i. e., second elapses in a frog’s muscle between the 
stimulation and the first sign of change of form in the muscle.] 
In man, the latent period varies between 0.004 and o 01 second. If the experiment be so 
arranged that the muscle can contract as soon as the stimulus is applied to it, i. e., before time is 
lost in making the muscle tense ; or to put it otherwise, if the muscle has not “ to take in slack,” 
as it were, the latent period may fall below 0.004 second [Gad). If the muscle be still attached 
to, the body, protected as much as 
possible from external influences and 
properly supplied with blood, the 
latent period may be reduced to 
0.0033 or even 0.0025. [All these 
results have reference to curves re- 
corded graphically. It is important 
to notice how the time is shortened 
when the record is taken by photo- 
graphic means as mentioned above.] 
Influences modifying the la- 
tent period.—The latent period is 
shortened by an increased strength 
of the stimulus and by heat; while 
fatigue, cooling, and increasing 
weight lengthen it [Lauierbach, 
Mendelssohn, Yeo, Cash). The latent period of a break-contraction is longer than that of a 
make-contraction. The red muscles have a longer latent period than the white. Before the 
muscle contracts as a whole, the individual fibres within it must have contracted. We must, 
Fig- 394- 
Muscle-curve produced by a single induction shock ap- 
plied to a muscle, a-/, abscissa; a-c, ordinate; a b, 
period of latent stimulation; b d, period of increasing 
energy; d e, period of decreasing energy; e f elastic 
after-vibrations. Sec. 298.] 
ANALYSIS OF A MUSCLE-CURVE. 
therefore, conclude that the latency of the individual muscular elements is shorter than that ot 
the entire muscle [Gad, Tigerstedt). 
(2) The contraction or stage of increasing energy, i. e., from the 
moment the muscle begins to shorten until it reaches its greatest degree of 
contraction d). At first the muscle contracts slowly, then more rapidly, 
and again more slowly, so that the ascending limb of the curve has somewhat 
the form of an f. This stage lasts o 03 to 0.04 second. It is shorter when the 
Electrical response = the sudden negativity and the subsequent relative positivity of the muscular 
surface of the gastrocnemius stimulated indirectly. Mechanical response = the beginning 
of the change of form of the part of the muscle stimulated directly; signal = the distance 
of the ordinates from each other = second. The rise of the line indicates the moment 
of opening the primary circuit, i. e., the moment of stimulation. Time marker = Deprez’s 
signal in the circuit of the tuning fork [Burdon-Sanderson). 
F'g- 395- 
contraction is shorter (weak stimulus) and the less the weight the muscle has 
to lift. It also varies with the excitability of the muscle, being shorter in a 
fresh, non-fatigued muscle. 
(3) Elongation or stage of decreasing energy.—After the muscle has 
contracted up to its maximum for any particular stimulus, it begins to relax— 
at first slowly, then rapidly—and lastly more slowly, so that an inverse of an f 
is obtained (d e). This stage is usually of shorter duration than (2). The 
duration varies with the strength of the stimulus, being shorter than (2) with a TIME RELATIONS OF A MUSCLE-CURVE. 
[Sec. 298. 
weak stimulus, and longer with a strong stimulus. It also depends upon the 
extent to which the muscle is loaded during contraction. 
(4) The fourth stage has received various names—stage of elastic after- 
vibration [residual contraction or contraction remainder (.Hermann). 
The after-vibrations (e f), which disappear gradually, depend upon the elas- 
Fig. 396. 
Pendulum myograph curve of a frog’s gastrocnemius. S, point of stimulation ; A, latent period; 
B, period of shortening, and C, of relaxation. 250 DV., tuning-fork vibrating 250 double 
vibrations per sec. The dotted vertical lines are ordinates {Stirling). 
ticity of the muscle. The duration of this stage is longest with a powerful con- 
traction, and when the weight attached to the muscle is small]. 
If the stimulus be applied to the motor nerve instead of to the muscle itself, 
the contraction is greater (Pfliiger), and lasts longer (JVund/) the nearer to 
the spinal cord the stimulus is applied to the nerve. 
[In studying a muscle-curve, the more or less vertical character of the 
ascent will indicate the rapidity of the con- 
traction, the height above the base line, its 
extent, the length of the curve, the dura- 
tion, and the line of descent, the rate of its 
extensibility. The form of the muscle- 
curve will vary with the kind of myograph 
used ; if it be stationary, then the muscle 
will merely record a vertical line; if the 
recording surface move quickly, the two 
parts of the curve will form an acute angle 
(fig. 398); and if it move with great rapidity, 
they will have the form of fig. 396, that ob- 
F*g- 397- 
Arrangement for estimating the time- 
relations during contraction of a 
muscle produced by a faradic shock. 
B, battery; K, key in primary circuit; 
I, primary, II, secondary spiral; /, 
muscle lever; e, electro-magnet in 
primary circuit; t, electric signal; St, 
support; RC, revolving cylinder 
(after Rutherford). 
Frog’s muscle stimulated alternately by a single 
break (B) and make shock (M). The lower curve 
shows the same, but with the muscle fatigued. 
Fig. 398. 
tained with a pendulum myograph. A vibrating tuning-fork records time 
directly under the tracing, whereby the duration of each part of the curve is 
readily determined.] 
[In measuring the myogram, all that is required is to know the moment at which the stimu- 
lus was applied, and to note when the curve begins to leave the base line or abscissa. Raise a Sec. 298.] 
FATIGUE OF MUSCLE. 
613 
vertical line or ordinate from each of these points, and the interval between these lines, as 
measured by the chronograph, indicates the time (fig. 396).] 
[The time-relations of a simple muscular contraction caused by a single 
induction shock may be studied by means of the following arrangement: 
Attach a frog’s gastrocnemius to a lever, as in fig. 397, and through the frog’s 
muscle place two wires from the secondary coil of an induction machine. A 
scale-pan with a weight is attached to the lever. On the same support adjust 
an electro-magnet with a writing-style in the primary circuit, and in this 
circuit also place a key ( K) to make and break the current. Fix also a Dupre’s 
chronograph to the same support, and make it vibrate by connecting it in 
circuit with a tuning-fork of known rate of vibration, and driven by a galvanic 
battery. See that the points of all three levers write exactly over each other 
on the revolving cylinder. The upper lever registers the contraction, the 
electro-magnet the moment the stimulus is applied to the muscle, and the 
electrical chronograph the time.] 
[Single make (closing) or break (opening) induction shocks. A muscle 
or nerve may be stimulated either with a “make” or “break” induction 
Fig- 399- 
I. Contraction of a fatigued frog’s muscle writing its contraction on a vibrating plate attached 
' to a tuning-fork. Each vibration = 0.01613 second ; a b, = latent period; b c, stage of 
- increasing energy; c d, of decreasing energy. II. The most rapid writing movements of 
the right hand inscribed on a vibrating plate. III. The most rapid trembling tetanic move- 
ments of the right fore-arm inscribed on the same plate. 
shock, but it is important to notice that the break shock is stronger than the 
make. In fig. 398, B shows the effect produced by a single break induction 
shock, and M that of a single make shock.] 
Overweighted Muscles.—The foregoing remarks apply to curves obtained by a light lever 
connected with the muscle. If the muscle lever be “overweighted,” or overloaded, i.e., if the 
lever be loaded so that when the muscle contracts it has to lift these weights, the course of the 
curve varies according to the weight to be lifted. It is necessary, however, to support the lever 
in the intervals when the muscle is at rest. As the weights are increased, the occurrence of the 
contraction is delayed. This is due to the fact that the muscle, at the moment of stimulation, 
must accumulate as much energy as is necessary to lift the weight. The greater the weight, the 
longer is the time before it is raised. Lastly, the muscle may be so “ loaded,” or “ overloaded,” 
that it cannot contract at all; this is the limit of the muscular or mechanical energy of the 
muscle {v. Helmholtz). 
Fatigue of Muscle.—If a muscle be caused to contract so frequently that 
it becomes “fatigued," the latent period is longer, the curve is not so high, 
because the muscular contraction is less, and the abscissa is longer, i. e., the 
contraction is slower and lasts longer (fig. 399). Cooling a muscle has the same 
effect. Soltmann finds that the fresh muscles of new-born animals behave in a 
similar manner. The myogram has a flat apex and considerable elongation in 
the descending limb of the curve. 614 
ACTION OF DRUGS ON MUSCLES. 
[Sec. 298. 
Constant Current.—If the motor nerve of a muscle be stimulated by a 
make or break shock of a constant current, the resulting muscular contraction 
corresponds exactly to that already described. If, however, the current be 
made or broken with the muscle itself directly in the circuit, during the make 
shock, i.e., when the 
muscle is stimulated di- 
rectly (the action of the 
nerves can be eliminated 
by using curare (§ 336)), 
there is a certain degree 
of contraction which lasts 
for a time, so that the 
curve assumes the form of 
fig. 400, where S represents the moment of closing or making the current, and 
O the moment of opening or breaking it (§ 336, D). 
Variations in Muscles.—The investigations of Cash and Kronecker show that individual 
muscles have a special form of muscle-curve; the omo hyoid of the tortoise contracts more 
rapidly than the pectoralis. Similar differences occur in the muscles of frogs and mammals. 
The flexors of the frog contract more rapidly than the extensors (Griitzner). Sometimes within 
one and the same muscle there are “red” (rich in glycogen) and “pale” fibres (§ 292). The 
muscles of the tortoise, the adductor muscles of the mussel, and the heart contract slowly. The 
red fibres contract more slowly, are less excitable, and less easily fatigued (Griitzner'). The 
muscles of flying insects contract very rapidly, even more than 360 times (fly) and 400 times 
(bee) per second. 
The pale muscles are more excitable, have a longer latent period, are 
more readily fatigued, and their contraction is of shorter duration than the red. 
The pale muscles also produce more acid than the red muscles when they con- 
tract (Gleiss). The red muscles execute the prolonged continued movements, 
while the white execute more rapid movements. Muscles which are composed 
chiefly of pale fibres have a greater “ lift ” and a considerably greater abso- 
lute force during a single contraction, but during tetanus they are second to the 
red (Griitzner). The muscle-curve of a muscle containing red and white 
fibres may show two elevations on the ascent, the first due to the rapidly 
contracting white fibres, and the second to the more slowly contracting red 
fibres. This also occurs after the action of strychnia on the muscle-substance 
( Over end'). 
Poisons.—Very small doses of curare or quinine increase the height of the contraction 
(excited by stimulation of the motor nerve), while larger doses diminish it, and finally abolish it 
altogether. Guanidin has a similar action in large doses, but the maximum of contraction lasts 
for a longer time. Suitable doses of veratrin also increase the contractions, but the stage of 
relaxation is greatly strengthened (Rossbach and Clostermeyer). Veratrin, antiarin, and 
digitalin, in large doses, act upon the sarcous substance in such a way that the contractions 
become very prolonged, not unlike a condition of prolonged tetanus {Harless, 1862). The 
latent period of muscles poisoned with veratrin and strychnin is shortened at first, and after- 
wards lengthened. The gastrocnemius of a frog supplied by blood containing soda contracts 
more rapidly (Griitzner). Kunkel is of opinion that muscular poisons act by controlling the 
imbibition of water by the sarcous substances. As muscular contraction depends on imbibition 
($ 297, II), the form of the contraction of the poisoned muscle will depend upon the altered 
condition of imbibition produced by the drug. 
[Action of Veratrin.—If a frog be poisoned with veratrin, and then be made to spring, it 
does so rapidly, but when it alights again the hind legs are extended, and they are only drawn 
up after a time. Thus, rapid and powerful contraction, with slow and prolonged relaxation, are 
the characters of the movement. In a muscle poisoned with veratrin, the ascent is quick 
enough, but it remains contracted for a long time, so that this condition has been called “ con- 
tracture.” A single stimulation may cause a contraction lasting five to fifteen seconds, accord- 
ing to circumstances (fig. 401). Brunton and Cash find that cold has a marked effect on 
the action of veratrin—in fact, its effect may be permanently destroyed by exposure to extremes 
Effect on a muscle of closing and opening a constant current. 
S, closing; O, opening shock. 
Fig. 400. Sec. 298.] 
RAPIDITY OF MUSCULAR CONTRACTION. 
615 
of heat or cold. The muscle-curve of a brainless frog cooled artificially, and then poisoned by 
veratrin, occasionally gives no indications of the action of the poison until its temperature is 
raised, and this is not due to non-absorption of the poison. Cold, therefore, abolishes or lessens 
the contracture peculiar to a veratrin-curve. Similar results are obtained with salts of barium, 
and to a less degree by those of strontium and calcium (Brunlon and Cash).] 
Smooth Muscles.—The muscle-curve of smooth or non-striped muscles is 
similar to that of the striped muscles, but the duration of the contraction is 
visibly much longer, and there are other points of difference. Some muscles 
stand midway between these two, at least as far as the duration of their con- 
tractions is concerned. 
The “ red ” muscles of rabbits, the muscles of the tortoise, the adductors of the common mussel, 
and the heart, all react in a similar manner. 
Contraction-Remainder.—A contracted muscle assumes its original 
length only when it is extended by sufficient traction, e.g., by means of a 
weight. Otherwise, the muscle may remain partially shortened for a long 
time. This condition has been called “contracture” (Tiegel), or, better, 
contraction-remainder (Hermann). This condition is most marked in 
muscles that have been previously subjected to strong, direct stimulation, and 
are greatly fatigued, which are distinctly acid, and ready to pass into rigor 
mortis, or in muscles excised from animals poisoned with veratrin (fig. 401). 
Lower curve is the normal muscle-curve (frog); upper one of the same muscle with veratrin 
(Stirling). 
Fig. 401. 
“Contracture” also occurs in man. Mosso by means of his ergograph 
(§ 304) found that occasionally it was so marked that the muscles so affected 
sustained a weight of 3 kilos. It occurs at the beginning of a series of con- 
tractions and diminishes with increasing fatigue. It is least marked when exe- 
cuting voluntary contractions, and most marked during strong direct or 
indirect muscular contraction. Mosso regards it as a kind of fatigue, produced 
by too strong stimulation, manifested by a muscle at the beginning of its 
activity (Mosso). 
Rapidity of Muscular Contraction.—In man, single muscular move- 
ments can be executed with great rapidity. The time-relations of such move- 
ments can be ascertained by inscribing the movements upon a smoked glass 
plate attached to a tuning-fork. Fig. 399, II, represents the most rapid volun- 
tary movements that Landois could execute, as, e.g., in writing the letters n, n, 
and every contraction is equal to about 3.5 vibrations (1 vibration = 0.01613 
second) = 0.0564 second. In III, the right arm was tetanized, in which case 
2 to 2.5 vibrations occur = 0.0323 to 0.0403 second. 
V. Kries found that a simple muscular twitch, caused by a single induction 
shock, is shorter than a momentary voluntary single movement. If the thicken- 
ing caused by a single voluntary contraction of a muscle be registered directly, 
the curve shows that the contraction within the muscle lasts longer than the ACTION OF TWO SUCCESSIVE STIMULI. 
[Sec. 298. 
duration of the movement produced in the passive motor apparatus itself. 
This paradoxical phenomenon is due to the fact that, shortly after the primary 
voluntary muscular contraction, there is a contraction of the antagonistic mus- 
cles, whereby a part of the intended movement is, as it were, cut off. During 
the most rapid voluntary movement in human muscles, v. Kries found that 4 
stimuli per second were active, so that a voluntary contraction is really a short 
tetanus. 
Pathological.—In secondary degeneration of the spinal cord after apoplexy, atrophic muscular 
anchylosis of the limbs, muscular atrophy, progressive ataxia, and paralysis agitans of long 
standing, the latent period is lengthened; while it is shortened in the contracture of senile chorea 
and spastic tabes (.Mendelssohn). The whole curve is lengthened in jaundice and diabetes 
(Edinger). In cerebral hemiplegia, during the stage of contracture, the muscle-curve resembles 
the curve of a muscle poisoned with veratrin, and the same is the case in spastic spinal paralysis 
and amyotrophic lateral sclerosis; in pseudo-hypertrophy of the muscles the ascent is short and 
the descent very elongated. In muscular atrophy, after cerebral hemiplegia, and in tabes, the 
latent period increases, while the height of the curve diminishes. In chorea, the curve is short 
(.Reaction of Degeneration, § 339). In rare cases in man, it has been observed that the execu- 
tion of spontaneous movements results in a very prolonged contraction (Thomsen’s disease). 
In such cases the muscular fibres are very broad, and the nuclei increased (Erb). 
II. Action of Two Successive Stimuli.—Let two momentary stimuli 
be applied successively to a muscle: (A) If each stimulus or shock be of itself 
sufficient to cause a “ maximal contraction,” i.e., the greatest possible con- 
traction which the muscle can accomplish, then the effect will vary according 
to the time which elapses between the application of the two stimuli. (a) If 
the second stimulus is applied to the muscle after the relaxation of the muscle 
following upon the first stimulus, we obtain merely two maximal contractions. 
(b) If, however, the second stimulus be applied to the muscle during the time 
that the effect of the first is present, i.e., while the muscle is in the phase of 
contraction or of relaxation; in this case the second stimulus causes a new 
maximal contraction, according to the time of the particular phase of the con- 
traction. (c) When, lastly, the second stimulus follows the first so rapidly 
that both occur during the latent period, we obtain only one maximal contrac- 
tion (v. Helmholtz). It is to be specially noted that a single maximal stimulus 
never excites the same degree of shortening as tetanic stimulation (HI), but 
only about of the height of the contraction in tetanus. 
(B) If the stimuli be not maximal, but only such as cause a medium or 
submaximal contraction, the effects of both stimuli are superposed, or there 
is a summation of the contractions (fig. 402). It is of no consequence at 
what particular phase 
of the primary con- 
traction the second 
shock is applied. In 
all cases, the second 
stimulus causes a con- 
traction, just as if the 
phase of contraction 
caused by the first 
shock was the natural 
passive form of the 
muscle, i. e., the new 
contraction (b, c) 
starts from that point 
as from an abscissa 
(fig. 402,1, b). Thus, 
under favorable con- 
Fig. 402. 
1, two successive sub-maximal contractions; II, successive contrac- 
tions produced by stimulating a muscle with 12 induction shocks 
per second; III, curve produced with very rapid induction shocks 
(complete tetanus). Sec. 298.] 
SUMMATION OF STIMULI. 
617 
ditions, the contraction may be twice as great as that caused by the first 
stimulus. The most favorable time for the application of the second stimulus 
is second after the application of the first (Sewall). The effects of both 
stimuli are obtained even when the second stimulus is applied during the latent 
period (v. Helmholtz). 
The second contraction of a summated contraction reaches its height in a shorter time than 
the first one would have done (v. Frey, v. Kries), i. e., in fig. 402 the time for b c is shorter than 
for a b. 
III. Tetanus—Summation of Stimuli.—If stimuli, each capable of 
causing a contraction, and following each other with medium rapidity, be 
applied to a muscle, the muscle has not sufficient time to elongate or relax in 
the intervals of stimulation. Therefore, according to the rapidity of the suc- 
cessive stimuli, it remains in a condition of continued vibratory contraction, 
or in a state of tetanus. Tetanus is, however, not a continuous uniform con- 
dition of contraction, but it is a discontinuous condition or form of the muscle, 
depending upon the summation or accumulation of contractions. If the 
stimuli are applied with moderate rapidity, the individual contractions appear 
in the curve (fig. 402, II) ; if they occur rapidly, and thus become superposed 
Fig. 403. 
Curves showing the analysis of tetanus of a frog’s muscle (gastrocnemius); the numbers under 
the curve indicate the number of shocks per second applied to the muscle. There is almost 
complete tetanus with 25 per sec. and it is a little lower than the previous one, because the 
muscle was slightly fatigued (Stirling). 
and fused, the curve appears continuous and unbroken by elevations and 
depressions (fig. 402, III). As a fatigued muscle contracts slowly, it is evident 
that such a muscle will become tetanic by a smaller number of stimuli per 
second than will suffice for a fresh muscle (Marey). All muscular movements 
of long duration occurring in our bodies are probably tetanic in their nature 
(Ed. Weber). 
The number of stimuli requisite to produce tetanus varies in different 
animals, and in different muscles of the same animal. About 15 stimuli per 
second are required to produce tetanus in the muscles of the frog (hyoglossus 
only 10, gastrocnemius 27, fig. 403); very feeble stimuli (more than 20 per 
second) cause tetanus (Kronecker) ; the muscles of the tortoise become tetanic 
with 2 to 3 shocks per second ; the red muscles of the rabbit by 10, the 
pale by over 20 (Kronecker and Stirling); muscles of birds not even with 70 
(Marey); muscles of insects 330 to 340 per second (Marey). Tetanic 
stimulation of the muscles of the crayfish (Astacus) and also in Hydrophilus, 
may cause rhythmical contractions (Richet), or rhythmically interrupted 
tetanus (Schonbein). 
[The number of stimuli required to produce tetanus in a frog’s gastrocnemius [Sec. 298. 
VOLUNTARY CONTRACTION 
is shown in fig. 403, and also various stages of incomplete tetanus by applica- 
tions of 4, 6, 8, 10, 15, 20, 25 
stimuli per second, the last 
showing almost complete te- 
tanus.] 
[Summation of Stim- 
uli.—If a stimulus, insuffi- 
cient in itself to cause con- 
traction of a muscle, be re- 
peatedly applied to a muscle 
in proper tempo and of suffi- 
cient strength, at first a slight 
and then a stronger or maximal contraction may be produced. This process 
of summation occurs also in nervous tissue (§ 360).] 
[Staircase or “ Treppe.’’-—Bowditch showed that the cardiac contractions exhibited a 
“ staircase ” character, i. e., the height of the second beat is greater than that of the first; and 
the third than that of the 
second (p. 100). The same 
occurs in the case of the mus- 
cles of the frog (Tiegel, Minot) 
and in mammals (Rossbac/i). 
Bohr showed that the succes- 
sive ascending apices in a 
tetanus-curve have really a 
staircase character, and that 
its exact form is that of a hy- 
perbola. Bohr found that (1) 
this form—the muscle not 
being fatigued—is independent 
of the strength and frequency 
of the stimuli. (2) The height 
of the series of contractions in 
tetanus is independent of the 
irequency of the stimuli, in- 
crease of frequency merely 
causing the staircase to reach 
its maximum more rapidly. 
(3) The height of the staircase increases—within certain limits—with the strength of the stimu- 
lus. Buckmaster has confirmed this for simple contractions, but as shown in fig. 404, when the 
stimuli are minimal or sub-maximal, there is usually no staircase character of the contractions, 
but maximal stimuli always cause it.] 
A continued voluntary contraction in man consists of a series of single 
contractions rapidly following each other. Every such movement, on being 
carefully analyzed, consists of intermittent vibrations, which reach their 
maximum when a person shivers (Ed. Weber). [Baxt found that the simplest 
possible voluntary contractions, e.g., striking with the index finger, occupies on 
an average nearly twice as long a time as a similar movement discharged by a 
single induction-shock.] 
The number of single impulses sent to our muscles during a voluntary 
movement is tolerably variable, during a slow contraction = 8 to 12, and 
during a rapid contraction = 18 to 20 impulses per second. Fig. 405, I, 
represents a myogram of a sustained contraction of the flexor brevis pollicis 
and abductor pollicis, recorded on a vibrating plate. The wave-like elevations 
indicate the single impulses, each tooth = 0.01613 second. II, is a similar 
curve registered by the extensor digiti tertii (Landois). [Schafer finds that 
prolonged voluntary contraction in man is an incomplete tetanus produced by 
8 to 13 successive nervous impulses per second. About 10 per second may be 
taken as the average.] 
Minimal. 
Maxima 
Sub-maximal. 
Maximal, 
Fig. 404. 
Four groups of contractions; interval ot stimulation 2 
seconds, and 5 minutes’ pause between two groups. 
I. 
II. 
Fig. 405. 
I, Vibration obtained from flexor brevis pollicis; II, from the 
extensor digiti tertii. Sec. 298.] 
ISOMETRICAL MUSCULAR ACTS. 
619 
Duration of Tetanus.—A tetanized muscle cannot remain contracted to the same extent for 
an indefinite period, even if the stimuli are kept constant. It gradually begins to elongate, at 
first somewhat rapidly, and then more slowly, owing to the occurrence of fatigue. If the tetanic 
stimulation is arrested, the muscle does not regain its original position and shape at once, but a 
contraction-remainder exists for a certain time, this being more evident after stimulation with 
induction shocks. 
[IV. If very rapid induction shocks (224 to 360 per second) be applied 
to a muscle, the tetanus after a so-called “ initial contraction ” (Bernstein) 
Curves obtained from red (upper) and pale (lower) muscles of a rabbit, by stimulating the sciatic 
nerve with a single induction shock. The lowest line indicates time, and is divided into 
second (Kronecker and Stirling'). 
Fig. 406. 
may cease (Harless, Heidenhaiti). This occurs most readily when the nerves 
are cooled. Kronecker and Stirling, however, found that stimuli following 
each other at greater rapidity than 24,000 per second produced tetanus.] 
[Tone-inductorium of Kronecker and Stirling.—This apparatus (fig. 408), consists of a 
rod of iron, d, fixed in an iron upright at a. The primary, s/t and secondary spiral, s//t rest on 
wooden supports, which can be pushed over both ends of the rod. One end of the rod lies 
between leather rollers, f which can be made to rub on the rod by moving the toothed 
Make and break induction shocks of 300 units, applied at intervals of a second to the pale 
(lower) and red (upper) muscles of a rabbit. The lowest line marks second (Kronecke7 
and Stirling). 
Fig. 4P7. 
wheels, h. In this way a tone is produced by the longitudinal vibrations of the rod, the 
number of vibrations being proportional to the length of the rod, so that by means of this instru- 
ment we can produce from 1000 to 24,000 alternating induction shocks per second.] 
Isometrical Muscular Acts.—Fick has recently investigated the changes 
—tension—undergone by a muscle when it is stimulated, and when its length 
remains constant, and he calls this process an “ isometrical muscular act.” 
He finds that a voluntary contraction in an isometrical act in man causes a 
higher tension than a contraction excited electrically. In the frog, the tension 620 
TRANSMISSION OF A CONTRACTION-WAVE. 
[Sec. 298. 
is nearly twice as great during tetanus as during a single maximal muscular 
contraction ; in human muscles, it may be ten times as great. 
299.—RAPIDITY OF TRANSMISSION OF A CONTRAC- 
TION.—1. If a long muscle be stimulated at one end, a contraction 
occurs at that point, and is rapidly propagated in a wave-like manner through 
the whole length of the muscle, until it reaches its other end. The condition 
of excitement or molecular disturbance is communicated to each successive 
part of the muscle, in virtue of a special conductive capacity of the muscle. 
The mean velocity of the contraction-wave is 3 to 4 metres per second in 
the frog (.Bernstein, 3.869 metres) ; rabbit, 4 to 5 metres (Bernstein and Steiner); 
lobster, 1 metre (Fredericq) ; in smooth muscle and in the heart, only 10 
to 15 millimetres per second (§ 58, 4). These results have reference only to ex- 
cised muscles, the velocity of transmission being much greater in the voluntary 
muscles of a living man, viz., 10 to 13 metres (Hermann, § 334, II). 
Methods.—(1) Aeby placed writing-levers upon both ends of a muscle, the levers resting 
transversely to the direction of the muscular fibres. The muscle was stimulated, and both levers 
Fig. 408. 
Tone-inductorium of Kronecker and Stirling, d, iron rod, clamped at a ; sy, primary, s//t 
secondary spiral, with a key, k ; leather rollers, f and g, driven by wheels, h. 
registered their movements, the one directly over the other on a revolving cylinder. On stimu- 
lating one end of the muscle, the lever nearest to this point is raised by the contraction wave, 
and a little later the other lever. When we know the rate at which the cylinder is moving and 
the distance between the two elevations, it is easy to calculate the rapidity of transmission of the 
contractio n-w a ve. 
[(2) Marey measured the rate of propagation of the wave of contraction by his “ pinces 
myographiques ” (fig. 409, 1, 2) each of which is connected to a recording tambour (i', 2/). 
When one end of the muscle is stimulated, e. g., at 1, the thickening which occurs during 
contraction of a muscle affects the first tambour, and as the wave of contraction passes along 
the muscle it affects the second tambour, so that two tracings are obtained on the drum. The 
two curves do not coincide, for that traced by 2r occurs slightly later than that traced by l/, 
the interval of time representing the time which the wave of contraction took to travel from 1 
to 2.] 
Duration and Wave-Length.—The time, corresponding to the length of 
the abscissa of the muscle-curve inscribed by each writing-lever, is equal to the 
duration of the contraction of this part of the muscle (according to Bernstein, 
0.053 t0 °-°98 second). If this value be multiplied by the rapidity of trans- 
mission of the muscular con traction-wave, we obtain the wave-length of the 
contraction-wave ( = 206 to 380 millimetres). Sec. 299.] 
621 
TRANSMISSION OF A CONTRACTION-WAVE. 
Modifying Influences.—Cold (fig. 410), fatigue, approaching death, and 
many poisons [veratrin, KCy] diminish the velocity and the height of the con- 
traction-wave, while the strength of the stimulus and the extent to which the 
Fig. 409. 
muscle is loaded are without any effect upon the velocity of the wave (Aefry). 
In excised muscles, the size of the wave diminishes as it passes along the mus- 
cle, but this is not 
the case in the mus- 
cles of living men 
and animals. The 
contraction - wave 
never passes from 
one muscular fibre to 
a neighboring fibre. 
[Fig. 410 shows the 
effect of cold on the 
muscles of a rabbit, in 
delaying the contrac- 
tion-wave. There is a 
longer distance between 
I and 2 in the lower than 
in the upper curves."! 
2. If a long muscle be stimulated locally near its middle, a contraction- 
wave is propagated towards both ends of the muscle. If several points be 
stimulated simultaneously, a wave movement sets out from each, the waves 
passing over each other in their course (Schiff). 
3. If a stimulus be applied to the motor nerve of a muscle, an impulse is 
specially communicated to every muscular fibre; a contraction-wave begins at 
the end-organ [motorial end-plate], and must be propagated in both directions 
along the muscular fibres, whose length is only 5-9 centimetres. As the length 
of the motor fibres from the nerve-trunk to where they terminate in the mo- 
torial end-plates is unequal, contraction of all the muscular fibres cannot take 
place absolutely at the same moment, as the nerve-impulse takes a certain time 
Pinces myographicjues of Marey (i and 2); l/ and 2' recording tambours. 
Fig. 410. 
Upper two curves, 2 and 1, obtained from a rabbit’s muscle by the 
above arrangement; the lower two curves from the same muscle 
when it was cooled by ice. 622 
MUSCULAR WORK. 
[Sec. 299. 
to travel along a nerve. Nevertheless, the difference is so small that, when a 
muscle is caused to contract by stimulation of its motor nerve, practically the 
whole muscle appears to contract simultaneously and at once. 
4. A complete, uniform, momentary contraction of all the fibres of a muscle 
can only take place when all the fibres are excited at the same moment. This 
occurs when the electrodes are placed at both ends of the muscle, and an 
electrical stimulus of momentary duration passes through the whole length of 
the muscle. 
300. MUSCULAR WORK. —Muscles are most perfect machines, not 
only because they make the most thorough use of the substances on which their 
activity depends (§ 2x7), but they are distinguished from all machines of human 
manufacture by the fact that by frequent exercise they become stronger, and 
are thereby capable of accomplishing more work (Du Bois-Reymond). 
The amount of mechanical work (W) which a muscle can perform is 
equal to the product of the weight lifted (/) and the height to which it is lifted 
(h), i. e., W = ph {Introduction), or 
height x weight = work. 
Hence it follows that when a muscle is not loaded (where p — o), then w must 
be = o, i.e., no work is performed. If, again, it be overloaded with too great a 
load, so that it is unable to contract (h — o), here also the work is nil. Be- 
tween these two extremes an active muscle is capable of doing a certain amount 
of “ mechanical work.” 
I. Work with Maximal Stimulation.—When the strongest possible, or 
maximal stimulus is applied—i. e., when the strength of the stimulus is 
such as to cause a muscle to contract to the greatest possible extent of which it 
is capable, the amount of work done increases more and more as the weight is 
increased, but only up to a certain maximum. If the weight be gradually in- 
creased, so that it is lifted to a less height, the amount of work diminishes 
more and more, and gradually falls to be = o, when the weight is not lifted at 
all. 
Example of the work done by a frog’s muscle (Ed. Weber) :— 
Weight lifted in Grams. 
Height in Millimetres. 
Work done in Gram-Millimetres. 
5 
27.6 
138 
i5 
25-1 
376 
• 25 
11.45 
286 
3° 
7-3 
220 
[Suppose a muscle be loaded with a certain number of grams, and then caused to contract, 
we get a certain height of contraction. Fig. 411 shows the result of an experiment of this kind. 
The vertical lines represent the height to which the weights (in grams) noted under them were 
raised, so that, as a rule, as the weight increases the height to which it is raised decreases.] 
Laws of Muscular Work.—1. A muscle can lift a greater load the 
larger its transverse section, i. e., the more fibres it contains arranged parallel 
to each other. 
2. The longer the muscle, the higher it can lift a weight. 
3. When a muscle begins to contract, it can lift the largest load; as the con- 
traction proceeds, it can only lift a less and less load, and when it is at its 
maximum of shortening, only relatively very light loads. 
4. By the term “ absolute muscular force ” is meant, according to Ed. 
Weber, just the weight which a muscle undergoing maximal stimulation is no 
longer able to lift (the muscle being in its normal resting phase), and without 
the muscle at the moment of stimulation being elongated by the weight. Sec. 300.] 
MUSCULAR WORK. 
623 
Comparative.—Comparing the absolute muscular force of different muscles, even in dif- 
ferent animals, it is usual to calculate it with reference to that of a square centimetre. The mean 
transverse section of a muscle is obtained by dividing its volume by its length. The volume is 
equal to the absolute weight of the muscles divided by its specific gravity = 1058. The absolute 
muscular force for 1 □ centimetre of a frog’s muscle = 2.8 to 3 kilos. [6.6 lbs.] (J. Rosenthal); 
for 1 Q centimetre of human muscle = 7 to 8 (Henke and Knorz), or even.9 to 10 kilos. [20 to 
23 lbs.] (Korster, Haughton). Insects can perform an extraordinary amount of work—an in- 
sect can drag along sixty-seven times its body-weight; a horse scarcely three times its own 
weight. 
5. During tetanus, when a weight is kept suspended, no work is done as 
long as the weight is suspended, but of 
course work is done in the act of lifting the 
load. To produce tetanus, successive stim- 
uli are required, the muscular metabolism is 
increased, and fatigue rapidly occurs. The 
potential energy in this case is converted into 
heat (§ 302). When a muscle is stimulated 
with a maximal stimulus, it cannot lift so 
great a weight with one contraction as when 
it is stimulated tetanically (Hermann). The 
energy evolved, even during tetanus, is 
greater the more frequent the stimulation, at 
least up to 100 stimuli persecond (Bernstein). 
II. Medium Stimuli.—If a muscle be 
caused to contract by stimuli of moderate 
strength, i. e., such as do not cause a maximal contraction, there are two possi- 
bilities : Either the feeble stimulus is kept constant whilst the load is varied, in 
which case the amount of work done follows the same law as obtains for maximal 
stimulation; or, the load may be kept the same, whilst the strength of the 
stimulus is varied. In the latter case Fick observed that the height to which 
the load was lifted increased in a direct ratio with the strength of the stimulus. 
The stimulus which causes a muscle to contract must reach a certain strength or intensity before 
it becomes effective, i. e., the “ liminal intensity ” of the stimulus, but this is independent of 
the weight applied to the muscle. With minimal stimuli, a small weight is raised higher than a 
large one, but as the stimulus is increased, the cont'actions also increase in a larger ratio with an 
increased load (v. Kries). 
The blood-stream within the muscles of an intact body is increased during 
muscular activity. The blood-vessels of the muscle dilate, so that the 
amount of blood flowing through them is increased (.Ludwig and Sczelkow). At 
the time that the motor fibres are excited, so also are the vaso-dilator fibres, 
which lie in the same nervous channels (§ 294, II). [Gaskell found that fara- 
dization of the nerve of the mylo-hyoid muscle of the frog not only caused teta- 
nus of the muscle, but also dilatation of its blood-vessels.] 
Testing Individual Muscles.—In estimating the absolute force of the individual muscles 
or groups of muscles in man, we must always pay particular attention to the physical relations, i. <?., 
to the arrangement of the levers, direction of the traction, degree of shortening, etc. (§ 306). 
Dynamometer.—The absolute force of certain groups of muscles is very conveniently and prac- 
tically ascertained by means of a dynamometer (fig. 412). This instrument is very useful for 
testing the difference between the power of the two arms in cases of paralysis. The patient grasps 
the instrument in his hand and an index registers the force exerted. Quetelet has estimated the 
force of certain muscles—the pressure of both hands of a man to be= 70 kilos.; while by pul- 
ling he can move double this weight. The force of the female hand is one-third less. A man 
can carry more than double his own weight; a woman about the half of this. Boys can carry 
about one-third more than girls. [Very convenient dynamometers are made by Salter of Bir- 
mingham, both for testing the strength of pull arrd squeeze ; in testing the former, the instru- 
ment is held as an archer holds his bow when in the act of drawing it, and the strength of pull is 
given by an index; in the latter another form of the instrument is used. Large numbers of ob- 
Fig. 411. 
grammes. 
Height to which each of the weights 
is raised. 624 
[Sec. 300. 
ELASTICITY OF MUSCLE. 
servations were made by means of these instruments by Francis Galton at the Health Exhibition, 
1885] 
Amount of Work Daily.—In estimating the work done by a man, we have to consider, not 
only the amount of work done at any one moment, but how often, time after time, he can succeed 
in doing work. The mean value of the daily work of a man working eight hours a day is io 
(10.5 to 11 at most) kilogram-metres per second, i.e., a daily amount of work = 288,000 
(300,000) kilogram-metres. 
[Ergostat.— Sometimes it is desirable that patients—especially those who suffer from exces- 
sive corpulence—should do a certain amount of work daily; this can be carried out by Gaertner’s 
Ergostat, which resembles a winch, driven by 
a handle. The pressure upon the wheel can be 
regulated by means of a strap, lever, and weights, 
and according to the weight and number of 
revolutions of the wheel, can the amount of 
mechanical work be accurately regulated. This 
instrument is recommended for therapeutical 
purposes ] 
Modifying Conditions.—Many substances, 
after being introduced into the body, diminish, 
and ultimately paralyze the production of work 
—mercury, digitalin, helleborin, potash salts, 
etc. Others increase the muscular activity— 
veratrin (Rossbach), glycogen, [caffein, and 
allied alkaloids], muscarin, (King and Fr. Hogyes), kreatin and hypoxanthin ; extract of meat 
rapidly restores the muscles after fatigue (Kobert). [Those drugs which excite muscular tissue 
restore it after fatigue. Kreatin is a waste product of muscle, and beef-tea and Liebig’s extract 
of meat perhaps owe their restorative qualities partly to these extractives.] 
301. THE ELASTICITY OF MUSCLE.—Physical.—Every elastic body has its 
“ natural shape,” i. e., its shape when no external force (tension or pressure) acts upon it so as to 
distort it. Thus, the passive muscle has a “ natural form.” If, however, a muscle be extended 
in the course of its fibres, the parts of the muscle are evidently pulled asunder. If the stretching 
be carried only to a certain degree, the muscle, in virtue of its elasticity, will regain its natural 
form. Such a body is said to possess “ complete elasticity,” i. e., after being stretched it re- 
gains exactly its original shape. By the term “ amount of elasticity ” (modulus) is meant the 
Fig- 412. 
Dynamometer of Mathieu. 
Fig. 413- 
Fig. 414. 
Fig. 415- 
Fig. 413.—Curve of elasticity from an inorganic body (india-rubber). Fig. 414.—Curve of elas- 
ticity from the sartorius of a frog, obtained by adding equal increments of weight at A, B, 
C, etc. Fig. 415 —Curve of elasticity produced by continuous extension and recoil of a frog’s 
muscle; 0 x, abscissa before, xf after extension. 
weight (expressed in kilograms) necessary to extend an elastic body 1 Q] millimetre in diameter, 
its own length, without the body breaking. Of course many bodies are ruptured before this occurs. 
For a passive muscle it is = 0.2734 (Wundt) [that of bone = 2264 (Wertheim), tendon = 
1.6693, nerve = 1.0905, the arterial walls = 0.0726 ( Wundt).) Thus, the amount of elasticity 
of a passive muscle is small, as it requires only a slight stretching force to extend it to its own length. 
It has, therefore, no great amount of elasticity. The term “ coefficient of elasticity ” is applied 
to the fraction of the length of an elastic body, to which it is elongated by the unit of weight 
applied to stretch it. It is large in a passive muscle. If the tension be sufficiently great, the 
elastic body ruptures at last. The “ carrying capacity ” of muscular tissue, until it ruptures, is 
in the following ratios for youth, middle, and old age, nearly 7:3:2. [Instead of the word 
“ elasticity,” Brunton suggests the use of extensibility and retractibility, terms suggested by 
Marey, the one referable to the elongation on the application of a weight, and the other to the 
shortening after its removal.] 
Curve of Elasticity.—In inorganic elastic bodies the line of elongation, Sec. 301.] 
ELASTIC AFTER-EFFECT. 
625 
or the extension, is directly proportioned to the extending weight (Hooke’s law) in 
inorganic bodies, and therefore in muscle this is not the case, as the weight is 
continually increased by equal increments—the muscle is less extended than at 
the beginning, so that the extension is not proportional to the weight. If equal 
weights be added to a scale-pan attached to a piece of india-rubber, with a 
writing-lever connected with it, and writing its movements on a plate of glass 
that can be moved with the hand, we get such a curve as in fig. 413, while, if 
the same be done with the sartorius of a frog, we get a result similar to fig. 414. 
A straight line joins the apices of the former, while the curve of elasticity is 
a hyperbola, or something near it, in the latter case. 
Elastic After-Effect.—At the same time, after the first elongation, corre- 
sponding to the extending weight, is reached, the muscle may remain for days, 
and even weeks, somewhat elongated. This is called the “ elastic after-effect" 
(§ 65). [Marey attached a lever to a frog’s muscle, and allowed the latter to 
record its movements on a slowly revolving cylinder. To the lever was fixed 
a vessel into which mercury slowly flowed. This extended the muscle, and 
when it had ceased to elongate, the mercury was allowed slowly to run out 
again. The curve obtained is shown in fig. 415. The abscissae, o x and x', 
indicate the position of the writing style before and after the experiment, and 
we observe that x’ is lower than 0 x, so that the recoil is imperfect. There has 
been an actual elongation of the muscle, so that the limit of its elasticity is 
exceeded. Although a frog’s gastrocnemius may be loaded with 1500 grams 
without rupturing it, 100 grams will prevent its regaining its original length.] 
Method.—In order to test the elasticity of a muscle, fix it to a support provided with a 
graduated scale, and to the lower end of the muscle attach a scale-pan, in which are placed 
various weights, measuring on each occasion the corresponding elongation of the muscle thereby 
obtained [Ed. Weber). In order to obtain the curve of elongation or extensibility, take as 
abscissse the successive units of weight added, and the elongation corresponding to each weight 
as ordinates. Example from the hyoglossus of the frog :— 
Weight in Grams. 
Length of the Muscle 
in Millimetres. 
Extension. 
In Millimetres. 
Percentage. 
o-3 
24.9 
i-3 
3°.° 
5-i 
20 
2.3 
32-3 
2-3 
7 
3-3 
33-4 
1.1 
3 
4-3 
34 2 
0.8 
2 
5-3 
34-6 
0.4 
1 
The elasticity of passive muscle is small in amount, but very com- 
plete, and is comparable to that of caoutchouc. Small weights greatly elongate 
a muscle. If the weights be uniformly increased, there is not a uniform elonga- 
tion ; with equal increments of weight, the greater the load, the increase in 
elongation always becomes less; or, to express it in another way, the amount 
of elasticity of the passive muscle increases with its increased extension (Ed. 
Weber). 
In inorganic bodies the curve of extension is a straight line, but in 
organic bodies it more closely resembles a hyperbola (Wertheini). The 
elasticity of a passive fatigued muscle does not differ essentially from that of a 
non-fatigued muscle. 
Fresh Muscles.—Muscles in the living body, and still in connection with their nerves and 
blood-vessels, are more extensible than excised ones. Muscles, when quite fresh, are elongated 
(within certain small limits as regards the weight) at first with a uniformly increasing weight, to 626 
ELASTICITY AND ITS USES. 
[Sec. 301. 
an extent proportional to the latter, just as with an inorganic body. When heavy weights are 
used, we must be careful to take into consideration the '■'■elastic after-effect'’’ (§ 65). 
The volume of a stretched muscle is slightly less than an unstretched one, similar to the con- 
tracted (§ 297, 2) and stiffened muscle ($ 295). 
Dead muscles and muscles in rigor mortis have a greater amount of elasticity, i. e., they 
require a heavier weight to stretch them than fresh muscles; but, on the other hand, the elasticity 
of dead muscles is less complete, i. e., after they are stretched, they only recover their original 
form within certain limits. 
Elasticity of Intact Muscles.—Normally, within the body, the muscles 
are stretched to a very slight extent, as can be shown by the slight degree of 
retraction which occurs when the insertion of a muscle is divided. This slight 
degree of extension, or stretching, is important. If this were not so, when a 
muscle is about to contract and before it could act upon a bone as a lever, it 
would have to “ take in so much slack.” The elasticity of muscles is mani- 
fested during the contraction of antagonistic muscles. The position of a pas- 
sive limb depends upon the resultant of the elastic tension of the different 
muscle groups. 
The elasticity of an active muscle is less than that of a passive muscle, 
i. e., it is elongated by the same weight to a greater extent than a passive 
muscle. For this reason the active muscle, as can be shown in an excised con- 
tracted muscle, is softer; the apparently great hardness manifested by stretched 
contracted muscles depends upon their tension. When the active muscle be- 
comes fatigued, its elasticity is diminished. [This is really seen in a fatigue- 
curve, where the muscle lever no longer reaches the abscissa] (§ 304). 
Method.—Ed. Weber took the hyoglossus muscle of a frog and suspended it vertically, 
noticing its length when it was passive. It was then tetanized with induction shocks, and its 
height again noted. One after the other heavier weights were attached to it, and the length of 
the passive and tetanized muscle observed for each weight. The extent to which the active 
loaded muscle shortened from the position of the passive loaded muscle he called the “ height 
of the lift” (or “ Hubhohe”). The latter becomes le-s as the weight increases, and lastly, the 
tetanized muscle may be so loaded that it cannot contract, i. <?., the height of the lift is = O. 
Weber’s Paradox.—The case may occur where, when a muscle is so loaded that it cannot 
contract when it is stimulated, it may even elongate. According to Wundt, even in this con- 
dition the elasticity is not changed. [The usual explanation given is that, as the elasticity of a 
muscle is diminished during contraction, it is more extended with the same weight in the con- 
tracted as compared with the passive or uncontracted state, so that a heavily weighted muscle, 
when stimulated, may elongate instead of shorten.] According to Wundt, however, as stated, 
there is no change in the elasticity of the muscle. In these experiments, the length of the active 
loaded muscle is equal to the length of the passive muscle when similarly loaded, minus the 
“ height of the lift.” 
Drugs.—Potash causes shortening of a muscle with simultaneous increase of its elasticity. 
Digitalin produces other changes with increased elasticity. Physostigmin increases it, while 
veratrin diminishes it, and interferes with its completeness (Rossbach and v. Anrep), and tannin 
makes a muscle less extensible, but more elastic (Lewin). Ligature of the blood-vessels pro- 
duces at first a decrease, and then an increase, of the elasticity; section of the motor nerve 
diminishes the elasticity (v. Anrep); heat increases it. 
Eduard Weber concluded from his experiments that a muscle assumes two forms, the active 
and the passive form. Each of these corresponds to a special natural form. The passive muscle 
is longer and thinner—the active is shorter and thicker in form. The passive as well as the- 
active muscle strives to retain its form. If the passive muscle be set into activity, the passive 
rapidly changes into the active form, in virtue of its elastic force. The latter is the energy 
which causes muscular work. Schwann compared the force of an active muscle to a long, 
elastic, tense spiral spring. Both can lift the greatest weight, only from that form in which they 
are most stretched. The more they shorten, the less the weight which they can lift. 
[Uses of Elasticity.—As already pointed out, all muscles are slightly on 
the stretch, so that no time is lost nor energy wasted, in “ taking in slack,” as 
it were; but the elasticity also lessens the shock of the contraction, so that it 
is developed gradually, and muscles are not liable to be torn from their attach- 
ments. The muscular energy is transmitted to the mass to be moved through Sec. 301.] 
HEAT AND MECHANICAL WORK. 
627 
an elastic and easily extensible body (muscle), whereby the shock due to the 
contraction is lessened, but, as Marey has shown, the amount of work is thereby 
considerably increased.] 
[Tonicity of Muscle (§ 362)—Sensibility of Muscle—That muscles contain sensory 
fibres is certain ($ 430). Section of inflamed muscles is painful, and during muscular cramp 
intense pain is felt. Sachs discharged a reflex action by stimulating the central end of an intra- 
muscular nerve-filament in a frog, while stimulation of the central end of the phrenic neive 
raises the blood-pressure (Muscular Sense, \ 430).] 
302. Formation of Heat in an Active Muscle.—After Bunzen, in 1805 
(§ 210, 1, b), showed that during muscular activity heat is evolved, v. Helm- 
holtz proved that an excised frog’s muscle, when tetanized for two to three 
minutes, exhibited an increase of its temperature of 0.140 to 0.180 C. 
R. Heidenhain succeeded in showing an increase of o.ooi° to 0.005° C. for 
each single contraction. The same is true of the beating heart, which is warmer 
during every systole (Marey). There is a very short latent period before the 
rise of temperature. 
[Method.—The rise in temperature of a frog’s muscle may be estimated by placing the two 
gastrocnemii muscles of a frog on the two junctions of a thermo-electric pile, connected with a 
heat galvanometer. Of course, when the two muscles are at the same temperature, the needle 
of the galvanometer is stationary; but, if one muscle is made to contract, or is tetanized, 
then an electrical current is set up which deflects the needle (£ 208 B). Lujankow has, by 
means of a delicate thermometer placed between the thigh muscles of a dog, estimated the rise 
of temperature under different conditions of the muscle, while the latter was still in situ and 
intact.] 
The following facts have been ascertained with regard to the development of 
heat:— 
1. Relation to Mechanical Work.—It bears a relation to the amount of 
work. 
(a) If a muscle during contraction carries a weight which extends it again 
during rest, no work is transferred beyond the muscle (§ 300). In this case all 
the chemical potential energy during this movement is converted into heat. 
Under these circumstances, the amount of heat evolved runs parallel with the 
amount of work done, i. e., it increases as the load and the height increase up 
to a maximum point, and afterwards diminishes as the load is increased. The 
heat-maximum is reached with a less load sooner than the work-maximum 
{Heidenhain). 
(b) If, when the muscle is at the height of its contraction, the load be re- 
moved, then the muscle has produced work referable to something outside itself; 
in this case the amount of heat produced is less (A. Hick). The amount of 
work produced, and the diminished amount of heat formed, when taken 
together, represent the same amount of energy, corresponding to the law of 
the conservation of energy. 
(c) If the same amount of work is performed in one case by many but small 
contractions, and in another by fewer but larger contractions, then in the latter 
case the amount of heat is greater {Heidenhain and Nawalichin). This shows 
that larger contractions are accompanied by a relatively greater metabolism of 
the muscular substance than small contractions, which is in harmony with 
practical experience; thus the ascent of a tower with steep high steps causes 
fatigue more rapidly (metabolism greater) than the ascent of a more gentle 
slope with lower steps. 
(d) If the weighted muscle executes a series of contractions one after the 
other, and at the same time does work, then the amount of heat it produces is 
greater than when it is tetanic, and keeps a weight suspended. Thus, the 
transition of the muscle into a shortened form causes a greater production of 
heat than the maintenance of this form. 628 
MUSCLE-SOUND. 
[Sec. 302. 
2. Relation to Tension.—The amount of heat evolved depends upon the 
tension of the muscle; it also increases as the muscular tension increases 
(Heidenhain). If the ends of a muscle be so fixed that it cannot contract, the 
maximum of heat is obtained (.Beclard), and this the more quickly the more 
rapidly the stimuli follow each other (Fick). Such a condition occurs during 
tetanus, in which condition the violently contracted muscles oppose each other, 
and very high temperatures have been registered by Wunderlich (§ 213, 7), 
while the same is true of animals that are tetanized (.Leyden). Dogs kept in a 
state of tetanus by electrical stimulation die, because their temperature rises so 
high (440 to 450 C.) that life can no longer be maintained (Richet). In addi- 
tion to the formation of heat, there is a considerable amount of acid, and of 
alcoholic extractives produced in the muscular tissue. 
3. Relation to Stretching.—Heat is also evolved during the elongation or 
relaxation of a contracted muscle, e.g., by causing a muscle to contract without 
the addition of any weight, and loading it when it begins to relax, whereby 
heat is produced (Steiner, Sclunulewitsch and Westerman). If weights be 
attached to a muscle by means of an inextensible medium, and the weights be 
allowed to fall from a height so as to give a jerk to the muscle, then an amount 
of heat equivalent to the work done by the drop is set free in the muscle (Fick 
and JDanilewsky). 
4. Fatigue.—The formation of heat diminishes as the muscular fatigue 
increases, and as the muscle recovers it increases (Fick). 
5. Blood Supply.—In a muscle duly supplied with blood the production 
of heat (as well as mechanical work) is far more active than in a muscle whose 
blood-vessels are ligatured or the blood-stream of which is cut off. Recovery 
takes place more rapidly and completely after fatigue, while, at the same time, 
there is a new increase in the production of heat (Meade Smith). 
The amount of work and heat in a muscle must always correspond to the transformation of an 
equivalent amount of chemical energy. A greater part of this energy is manifested as work, the 
greater the resistance that is offered to the muscular contraction. When the resistance is great, 
of the chemical energy may be manifested as work, but when it is small, only a small part of 
it is so converted. 
When the temperature is increased, as in fever, there is a greater metabolism in the muscle 
with the production of more heat, but without increasing the amount of work done. 
In man, if the muscles be stimulated with electricity or contracted voluntarily, the production 
of heat may be detected through the skin (v. Ziemssen). The venous blood flowing from an 
actively contracting muscle is o.6° C. warmer than the arterial blood [Meade Smith). 
It was stated that a nerve in action is C. warmer (Valentin), but this is denied by 
v. Helmholtz and Heidenhain; a dying nerve, however, becomes warmer (Rolleston). 
303. THE MUSCLE-SOUND.—Resting and Active Muscle.— 
When a muscle contracts, and is at the same time kept in a state of tension by 
the application of sufficient resistance, it emits a distinct sound or tone with a 
semi-musical quality, depending upon the intermittent variations of tension 
occurring within it ( Wollaston). 
Methods.—The muscle-sound may be heard by placing the ear over the tetanically con- 
tracted and tense biceps of another person; or we may insert the tips of our index fingers 
into our ears, and forcibly contract the muscles of our arm; or the sound of the muscles that 
close the jaw may be heard by forcibly contracting them, especially at night when all is still, and 
when the outer ears are closed. V. Helmholtz found that this tone coincides with the resonance 
tone of the ear, and he thought that the vibrations of the muscles caused this resonance tone. 
The sound of an isolated frog’s muscle may be heard by placing one end of a rod in the ear, 
the other ear being closed. To the other end of the rod is attached a loaded frog’s muscle kept 
in a tetanic condition. The pitch of the note, i.e., the number of vibrations, may be estimated 
by comparing the muscle-sound with that produced by elastic springs vibrating at a known 
rate. 
When a muscle contracts voluntarily, i. e., through the will, it makes 19.5 Sec. 303.] 
PASSIVE AND ACTIVE MUSCLE. 
629 
vibrations per second. [Schafer and others give the number as io successive 
nervous impulses per second, p. 618.] We do not hear this very low tone, 
owing to the number of vibrations per second being too few, but what we 
actually hear is the first overtone, with double the number of vibrations. The 
muscle-sound has 19.5 vibrations, when the muscles of an animal are caused to 
contract, by stimulating its spinal cord (v. Helmholtz), and also when the motor 
nerve-trunk is excited by chemical means (.Bernstein). If, however, tetanizing 
induction shocks be applied to a muscle, then the number of vibrations of the 
muscle-sound corresponds exactly with the number of vibrations of the vibrat- 
ing spring or hammer of the induction apparatus. Thus the tone may be 
raised or lowered by altering the tension of the spring. 
Loven found that the muscle-sound was loudest when the weakest currents capable of pro- 
ducing tetanus were employed. The sound corresponded to the number of vibrations of the 
octave just below it in the scale. With stronger currents the muscle sound disappears, but it 
reappears with the same number of vibrations as that of the interrupter of the induction appa- 
ratus, if still stronger currents are used. 
If the induction shocks be applied to the nerve the sound is not so loud, 
but it has the same number of vibrations as the interrupter. With rapid induc- 
tion shocks, tones caused by 704 (Loven) and 1000 vibrations per second have 
been produced (Bernstein). 
A single induction shock is said to cause the muscle-sound in a contracting muscle. If this 
be so, it is doubtful if the muscle-sound can be regarded as a sign that tetanus is due to a series 
of single variations of the muscle (£ 298, III). 
[The first heart-sound is said to be partly muscular and partly valvular 
(§ 53)> and, as already stated, Krehl has recently confirmed this view originally 
supported by Ludwig and Dogiel. Haycraft, however, states that the first 
sound is a valvular sound like the second sound.] 
[Bernstein has shown that a muscle-sound may be produced during a single contraction of a 
muscle, which is not due to friction of the muscle on its surroundings. Stimulation of a muscle 
by a single induction shock causes a short sharp sound (“ contraction sound.”) It coincides 
with the period of “ negative variation.”] 
[Resting living muscle versus active muscle.—It might be well to 
sum up the chief differences between a living resting or passive muscle and one 
actively contracting. When a muscle contracts it undergoes physical and 
chemical changes, resulting in the conversion of the energy of chemical affinity 
into other forms of energy. 
1. The naked eye changes are that the muscle becomes shorter and thicker 
with scarcely any appreciable change in its volume, thus resulting in mechanical 
motion. 
2. Microscopic changes.—It is admitted by all that the dim bands be- 
come broader across the fibre, and correspondingly thinner in the length of the 
fibre. Some say that the bright discs undergo similar changes. Under the 
polariscope both bands are seen to retain their specific characters in relation to 
the action of light. 
3. Thermal changes.—Heat is given off by a resting muscle, but the heat 
evolved is increased during contraction. 
4. Changes of electrical potential.—The contracted part becomes 
negative to the uncontracted part of the muscle, i. e., there is a current of 
action, or, put in another way, the electrical response results in a diminution of 
the muscle-current or the so-called “ negative variation.” 
5. Other physical changes.—The elasticity is diminished, the extensi- 
bility is increased, and the sound—the “ muscle-sound ”—is emitted. 630 
FATIGUE OF MUSCLE. 
[Sec. 303. 
6. The chemical changes in an active muscle are similar to those that occur 
in a muscle at rest, but on contraction taking place, there is a sudden increase 
of those changes. Gases—The contracting muscle gives off more C02, and 
takes up more O, but not in proportion to the C02 given off. Reaction— 
There is an increased formation of lactic acid, so that, with continued con- 
traction, the muscle may become acid. Extractives—During tetanus, at 
least, the extractives soluble in water decrease, and those soluble in alcohol in- 
crease. Some reducing substances seem to be produced, but there is no evi- 
dence that the proteids of the muscle itself undergo a change.] 
304. FATIGUE AND RECOVERY OF MUSCLE.—By the term 
fatigue is meant that condition of diminished capacity for work which is pro- 
duced in a muscle by prolonged activity. This condition is accompanied in 
the living person with a peculiar feeling of lassitude, which is referred to the 
muscles. A fatigued muscle rapidly recovers in a living animal, but an excised 
muscle recovers only to a slight extent (Ed. Weber, Valentin). 
[Waller recognizes a certain resemblance between experimental fatigue and the natural decline 
of excitability at death, in disease, and in poisoning.] 
The cause of fatigue is probably partly due to the accumulation of de- 
composition products—“fatigue stuffs”—in the muscular tissue, these pro- 
ducts being formed within the muscle itself during its activity. They are 
phosphoric acid, either free or in the form of acid phosphates, acid potassium 
phosphate (§ 294), glycerin-phosphoric acid (?) and C02. If these substances 
be removed from a muscle, by passing through its blood-vessels an indifferent 
solution of common salt (0.6 per cent.), or a weak solution of sodium carbonate 
[or a dilute solution of permanganate of potash (.Kronecker)'], the muscle again 
becomes capable of energizing (J. Ranke, 1863). The using up of O by an 
active muscle favors fatigue (v. Pettenkofer and v. Voit). The transfusion of 
arterial blood (not of venous—Bichat) removes the fatigue (Ranke, Kronecker), 
probably by replacing the substances that have been used up in the muscle. 
Conversely, an actively energizing muscle may be rapidly fatigued by injecting 
into its blood-vessels a dilute solution of phosphoric acid, of acid potassium 
phosphate, or dissolved extract of meat (Kemmerich). A muscle fatigued in 
this way absorbs less O, and when so fatigued, it evolves only a small amount 
of acids and C02. The conditions which lead up to fatigue are connected with 
considerable metabolism in the muscular tissue. 
[Massage.—Zabludowski found that if a frog’s muscles be systematically stimulated by 
maximum induction shocks until they cease to contract, massage or kneading them rapidly 
restored their excitability, while simple rest had little effect. Massage acts on the nerves, but 
chiefly by favoring the blood, and lymph-streams which wash out the waste products from the 
muscle. A similar result obtains in man, so that the ancient Roman practice of “ rubbing ” 
after a bath and after exercise was one conducive to restoration of the power of the muscles.] 
Conditions modifying fatigue.—In order to obtain the same amount of 
work from a fatigued muscle, a much more powerful stimulus must be applied 
to it than to a fresh one. A fatigued muscle is incapable of lifting a consider- 
able load, so that its absolute muscular force is diminished. If, during the 
course of an experiment, an excised muscle be loaded with the same weight, 
and if the muscle be stimulated at regular intervals with maximal stimuli 
(strong induction shocks), contraction after contraction gradually and regu- 
larly diminishes in height, the decrease being a constant fraction of the total 
shortening. Thus the fatigue-curve is represented by a straight line [i. <?., a 
straight line will touch the apices of all the contractions]. The more rapidly 
the contractions succeed each other, the greater is the fall in the height of the Sec. 304.] 
FATIGUE OF MUSCLE. 
631 
contraction [/. e., if the interval between the contractions be short, the fatigue- 
curve falls rapidly towards the abscissa], and conversely. After a certain num- 
ber of contractions an excised muscle becomes exhausted. 
This result occurs whether the stimuli are applied at short or long intervals 
(.Kronecker), and a similar result is obtained with sub-maximal stimuli (Tiegel). 
A fatigued muscle contracts more slowly than a fresh one, while the latent 
period is also longer during fatigue (p. 6r3). The fatigued muscle is said to 
be more extensible (Bonders and van Mansvelt). If a muscle be so loaded 
that, when it contracts, it cannot lift the load, fatigue occurs even to a greater 
extent than when the load is such that the muscle can lift it (.Leber). The 
metabolism and the formation of acid are greater in a contracted muscle kept 
on the stretch than in a contracted muscle allowed to shorten (.Heidenhain). If 
a muscle contract, but be not required to lift any load, it becomes fatigued only 
very gradually. If a muscle be loaded only during contraction, and not during 
relaxation, it is fatigued more slowly than when it is loaded during both 
phases ; and the same is true when a muscle has to lift its load only during the 
course of its contraction, instead of at the beginning of the contraction. A 
load may be suspended to a perfectly passive muscle without fatiguing it (.Har- 
less, Leber). 
[Signs of fatigue (fig 4r6).—In the record of the series of contractions; 
(r) the contractions become more prolonged; (2) they decrease in height; 
(3) the latent period becomes longer ; (4) if maximal shocks be used, the be- 
ginning of the series exhibits a “staircase” character of its contractions, just 
like the heart (§ 57).] 
[While an excised frog’s muscle is fairly rapidly exhausted by single opening induction 
shocks, at intervals of one second, human muscle in its normal relations may be almost in- 
definitely so treated, and there is no change in the record or any sensation of fatigue. Waller 
regards this as favoring the view that the 
“ fatigue consequent upon prolonged 
muscular exertion is normally central 
rather than peripheral.” Such results, 
however, do not harmonize with those of 
Zabludowski on the kneading of muscles, 
or massage. Probably there are two fac- 
tors, one central, the other peripheral.] 
Blood Supply.—If the arteries of a 
mammal be ligatured, stimulation of the 
motor nerves produces complete fatigue 
after 120 to 240 contractions (in two to 
four minutes), but direct muscular stimu- 
lation still causes the muscles to contract. 
In both cases the fatigue-curve is in the 
form of a straight line. If the blood sup- 
ply to a mammalian muscle be normal, _ . 
on stimulating the motor nerve, the muscular contractions at first increase in height and then 
fall, their apices forming a straight line (Rossbach and Harteneck). In persons who have used 
their muscles until fatigue sets in, it is found that at the beginning the nerves and muscles react 
better to galvanic and faradic stimulation, but afterwards always to a less degree (Orschanski). 
According to v. Kries, a muscle tetanized and fatigued with maximal stimuli behaves like a fresh 
muscle tetanized with sub-maximal stimuli; both show an incomplete transition from the passive 
to the active condition. 
[Relation of End-Plates. — Muscle is fatigued far more rapidly than nerve, and the fatigue 
begins in the muscle and not in the nerve; it seems to be the weakest link in the chain between 
nerve and muscle which is affected during excessive action, viz., the motor end-plate ( Waller). 
In a nerve its conductivity is sooner affected by fatigue than its direct excitability. Waller finds 
that after death “the excitability of a nerve persists when its action upon muscle has ceased, 
such muscle being still excitable by direct stimulation.” Some link in the chain is obviously 
affected, and it is perhaps the end-plates.] 
[Relation of Drugs to Fatigue.—Waller finds, in a frog poisoned with veratrin, that if the 
Fatigue curve of a frog’s muscle. The sciatic nerve 
was stimulated with maximal induction shocks and 
every fifteenth contraction recorded (Stirling). 
Fig. 416. 632 
ERGOGRAPH. 
[Sec. 304. 
muscles be stimulated electrically, the characteristic elongation of the descent (§ 298) gradually 
disappears, but reap- 
pears after a period of 
rest. In this respect, 
strychnin in its action 
on the spinal cord be- 
haves precisely the same 
as veratrin on muscle, 
viz., its effect is dissi- 
pated by action and re- 
stored by rest.] Curare 
and the ptomaines cause 
an irregular course of 
the fatigue-curve (Gu- 
areschi and Mosso). 
[If strychnin be in- 
jected into a frog, and 
the sciatic nerve on one 
side divided after the 
strychnin tetanus has 
lasted for a time, the 
leg muscles of the side 
with the nerve undivided exhibit signs of fatigue, as shown by direct stimulation of the muscles 
of both legs, when a curve similar to fig. 417 is obtained. The higher one is the non-fatigued, 
the lower that of the side with the nerve undivided ( Waller).~\ 
Recovery from the condition of fatigue is promoted by passing a constant 
electrical current through the entire length of the muscle (Heide7ihain), also by 
injecting fresh arterial blood into its blood-vessel, or by very small doses of 
veratrin [or permanganate of potash], and by rest. 
If the muscle of an intact animal be stimulated continuously (fourteen days or so) until 
complete fatigue occurs, the muscular fibres become granular and exhibit a wax-like degenera- 
Curves obtained by direct stimulation of the gastrocnemius of a frog 
poisoned with strychnin, the sciatic nerve divided on one side (upper 
curve) and not on the other (lower or fatigue-curve). 
Fig. 417. 
Ergograph of Mosso, as made by Verdin, of Paris. 
Fig. 418. 
tion. The transverse striation is still visible as long as the sarcous substance is in large masses 
but as soon as it breaks up into small pieces the transverse striation disappears completely 
(O. Roth). 
[Fatigue experiments on man with the Ergograph.—Mosso and 
Maggiora fixed the fore-arm in an appropriate holder and attached the middle 
finger to a string to which a weight was added. The person experimented on Sec. 304.] 
ERGOGRAPH. 
633 
contracted his flexor muscles and thus raised at a given signal a given weight, 
the extent of the movement being recorded simultaneously. This in principle 
is the ergograph shown in fig. 418.] 
Muscles excited to contract directly become sooner fatigued than those ex- 
cited indirectly (/. e., through their nerve). The fatigue-curve is a straight line 
only for medium weights, for small weights it is S-shaped, and for larger ones 
it is a hyperbola. 
[Kronecker found in the case of frogs’ muscle stimulated electrically, that 
the “fatigue-curve” was a straight line gradually falling towards the abscissa 
(p. 630). Mosso, however, finds that more usually the curve obtained is like 
fig. 419, A, or fig. 419, B, and that the form of curve is nearly constant for 
each individual under the same conditions; and, as a matter of fact, he has 
shown that the fatigue-curve obtained by raising a weight of 3 kilos, with the 
ergograph remains constant over an interval of several years.] 
A muscle tetanized continuously by electrical stimuli until its muscular energy is apparently 
exhausted, still retains some energy, which can be called into action by the will. Conversely, 
Fig. 419. 
Curves obtained by the ergograph from two individuals, A and B 
a muscle which no longer contracts in obedience to volitional stimuli will contract when stimu- 
lated by electrical stimuli. If electrical and volitional stimuli act directly the one after the 
other, in this way complete exhaustion and fatigue of the muscle may be brought about. 
Mental work diminishes considerably the muscular force. The most powerful volitional 
muscular contractions cannot be increased by strong electrical stimulation of the motor nerves. 
On the contrary, if the motor nerve is strongly stimulated, so as to cause a slightly stronger 
contraction, then the will cannot cause the muscle to contract still more. Anaemia causes 
symptoms similar to fatigue, but a free supply of blood rapidly restores the muscle. Fatigue of 
the legs, as in walking, accelerates the fatigue of the arms. Sustained wakefulness and fasting 
facilitate fatigue. Massage favors the disappearance of fatigue (Maggiora). [There would 
seem to be a central nervous factor associated with the production of muscular fatigue; for if a 
muscle be made to contract voluntarily until it no longer responds to volitional stimuli, and if 
meantime it be stimulated to contract by means of electrical stimuli, it again—although it has 
been contracting—becomes capable of responding to volitional stimuli. It would-seem as if the 
nerve-centres also became fatigued during muscular fatigue. They had apparently recovered in 
the interval. Work done by a fatigued muscle produces far more injurious consequences than a 
far larger amount done by the muscle under normal conditions. Fatigue of other muscles than 634 
STRUCTURE OF BONE. 
[Sec. 304. 
in those to be investigated, e.g., forced marching, fatigues even the unused muscles, e.g., of the 
arms.] 
305. STRUCTURE AND MECHANISM OF BONES AND 
JOINTS .— Bones exhibit in the inner architecture of their spongiosa an 
arrangement of their lamellae and spicules which represents the static result of 
those forces—pressure and traction—which act on the developing bone (§ 447). 
They are so arranged that, with the minimum of material, they afford the 
greatest resistance as a supporting structure or framework (H. v. Meyer, Cul- 
mann, Jul. Wolff). 
[Structure of Bone.—Next to enamel, bone is the hardest tissue in the 
body. Its hardness is due to the presence of lime-salts, chiefly phosphate of 
lime. If a bone be steeped for some time in dilute hydrochloric acid, the 
lime-salts are extracted and the bone loses its rigidity; it becomes soft, and 
pliable, and can be cut with a knife; indeed, such a bone, e.g., rib or fibula, 
may be tied into a knot. The bone, when softened or decalcified, still retains 
the shape and general structure of the original bone. If a bone be burned it 
first chars, and, finally, only the ash remains. The organic matter is all burned 
off, and now the bone is quite brittle.] 
[The chemical composition of dry bone is approximately as follows: — 
Ossein (collagen), or animal matter, 
• 31-03 
Calcic phosphate, 
■ 58.23 
Calcic carbonate, 
7-32 
Calcic fluoride, 
. 1.41 
Magnesic phosphate, . 
• i-32 
Sodic chloride, 
. 0.69] 
[If a longitudinal section be made of a long dried bone, the outer part is 
seen to be dense or compact; while, more interiorly, more especially towards 
the extremities of the bone, the bony texture is more cancellated or spongy. 
There is, however, a gradual transition from dense to spongy bone. The 
spicules of bone which bound the cancelli or spaces in cancellated bone are 
arranged in a definite order in each bone, corresponding to the lines of pressure 
and stress. This constitutes the architecture of the bones. In the central part 
of every long bone is a cavity, the medullary cavity, which in the fresh 
condition contains the marrow.] 
[Bone consists of cells embedded in a fibrous matrix.—The cells or 
bone-corpuscles, are branched corpuscles (fig. 422). The matrix consists 
of interlacing fibres, and there is a ground-substance which contains the lime 
salts. The corpuscles lie in spaces of the matrix called lacunae, and adjoining 
lacunae communicate by numerous fine canals—canaliculi—which perforate 
the matrix (fig. 420).] 
[A fresh bone is really a complex organ. It is invested externally by a 
fibrous membrane, the periosteum, in which numerous arteries ramify before 
they enter the bone. The arteries pass into the bone through small apertures, 
ramify, and run in channels in the compact bone, the Haversian canals 
(fig. 421). The medullary canal contains marrow, and so do the cancelli at 
the ends of the bone. The medullary canal is lined by a thin vascular mem- 
brane, the endosteum.] 
[Microscopic Structure of Macerated Compact Bone.—A thin trans- 
verse section of the shaft of such a bone is made up of lamellae, or plates dis- 
posed as follows: Some of them are arranged concentrically with reference to 
the outer surface of the bone, i.e., immediately under the periosteum—these 
are the peripheric lamellae ; others (5-15) are arranged around the sections 
of the Haversian' canals,—these are the Haversian lamellae, and each 
Haversian canal with its lamellae constitutes an Haversian system (fig. 420). Sec. 305.] 
STRUCTURE OF BONE. 
635 
Some vestiges of lamellae lie between the Haversian systems, but they always 
are arcs of circles with longer radii than 
the Haversian lamellae; they are inter- 
mediate or interstitial lamellae (fig. 
420, si). Some lamellae are arranged 
with reference to the central marrow 
cavity, and are the peri-medullary 
lamellae.] 
Transverse section of part of the shaft of a 
human femur. H, Haversian canals; 
Haversian lamellae; si, interstitial lamellae; 
o, lacunae with canaliculi. x 40. 
Fig. 420. 
Longitudinal section of the diaphysis of 
a human femur x 100. a, Haversian 
canals; b, lacunae seen from the side; 
c, from the surface. 
Fig. 421. 
[In the transverse section of each Haversian system are sections of oval 
flattened spaces, arranged concentrically—the lacunae (fig. 420). They 
appear black, because in dry bone they are filled with air. From these lacunae 
canaliculi, or fine branching tubes, proceed, and perforate the lamellae, so 
that the canaliculi from adjacent lacunae anastomose. The innermost lacunae 
communicate with the Haversian canal of their own system, and by this canal- 
icular system lymph is carried to the bone-corpuscles, which lie in the lacunae 
and quite close to the outermost part of each Haversian system. The canal- 
iculi from the outermost lacunae of any Haversian system do not communicate 
with the canaliculi of adjacent systems, but they bend on themselves, and open 
into the lacunae of their own system, and hence they have been called recur- 
rent canaliculi.] 
[The arrangement of the lacunae in the other parts of the bone follow the 
arrangement of the lamellae, several lamellae usually intervening between two 
adjacent rows of lacunae.] 
[Sharpey’s Fibres are calcified fibres which pierce obliquely or at right 
angles the peripheric and interstitial lamellae. Some of them are calcified white 
fibrous tissue, and others are yellow or elastic fibres. The latter are more 
abundant in the bones of birds.] 
[The appearance presented by a longitudinal section of compact dry bone is 
shown in fig. 421.] 
[The periosteum is a laminated fibrous membrane, composed chiefly of 636 
PERIOSTEUM AND BONE MARROW 
[Sec. 305 
fibrous tissue. It consists of an outer fibrous layer, which contains many 
blood-vessels, and branches of the latter, accompanied by connective-tissue, 
pass into the Haversian canals. The inner layer contains some fibrous tissue, 
also many elastic fibres, and, especially in young bones, numerous nucleated, 
somewhat cubical, cells—the osteoblasts, or bone-forming cells. The 
osteoblasts form several layers in young bones, and in adult bones they exist as 
thin flattened cells, lying on the outermost peripheric lamellae. They are 
carried into the interior of the bone, along the Haversian canals, with the 
blood-vessels. They form bone—secrete or form bone around themselves— 
and, in doing so, become embedded, as it were, in the products of their own 
activity; and, when so embedded in osseous tissue, they are then called bone- 
corpuscles, so that bone-corpuscles are embedded osteoblasts. In a section 
of a softened fresh bone which has b£en stained, it is easy to see bone-cor- 
puscles lying in their lacunae (fig. 422).] 
[The marrow of bone is of two varieties, yellow and red. Yellow 
Fibrous layer. 
Periosteum. 
Layers of 
osteoblasts. 
Osteoblasts. 
Osteoclast. 
Bone. 
Haversian canal 
Bone corpuscle. 
Fig. 422. 
Transverse section of a part of the shaft of a long bone, decalcified and stained with picro- 
carmine (Stirling). x 350. 
marrow occurs in the medullary canal, and is for the most part made up of 
fat-cells. Red marrow, however, occurs chiefly in the heads of large bones, 
in short bones, ribs, flat bones of the skull, and is really a blood-forming 
organ (§ 7). It contains several varieties of cells—small, round, nucleated 
cells—the marrow cell closely resembling lymph-corpuscles; others, not unlike 
these, but with a yellowish tint, the erythroblasts, from which red blood- 
corpuscles are formed. It also contains large multi-nucleated cells, osteoclasts 
or myeloplaxes. These osteoclasts absorb or eat away bone, and are the 
structures concerned in the absorption of bone during certain stages of bone- 
development (fig. 422).] 
I. The joints permit the freest movements of one bone upon another [such as exist between 
the extremities of the bones of the limbs. In other cases sutures are formed, which, while per- 
mitting no movement, allow the contents of the cavity which they surround to enlarge, as in the 
case of the cranium.] The articular end of a fresh bone is covered with a thin layer or plate of 
hyaline cartilage, or “ encrusting cartilage,” which in virtue of its elasticity moderates any Sec. 305.] 
637 
JOINTS AND ARTICULAR CARTILAGE. 
shocks or impulses communicated to the bones. The surface of the articular cartilage is per- 
fectly smooth, and.facilitates an easy gliding movement of the one surface upon the other. At 
the outer boundary line of the cartilage there is fixed the capsule of the joint, which encloses 
the articular ends of the bones like a sac. The inner surface of the capsule is lined by a synovial 
membrane, which secretes the sticky, semi-fluid, synovia, moistening the joint. The outer 
surface of the capsule is provided at various parts with bands of fibrous tissue, some of which 
strengthen it, while others restrain or limit the movement of the joint. Some osseous processes 
limit the movements of particular joints, e.g., the coronoid process of the ulna, which permits 
the fore-arm to be flexed on the upper arm only to a certain extent; the olecranon, which pre- 
vents over-extension at the elbow-joint. The joint-surfaces are kept in apposition—(i) by the 
adhesion of the synovia-covered smooth articular surface; (2) by the capsule and its fibrous 
bands; and (3) by the elastic tension and contraction of the muscles. 
[Structure of Articular Cartilage.—The thin layer of hyaline encrusting 
cartilage is fixed by an irregular surface upon the 
corresponding surface of the head of the bone 
(fig. 423). In a vertical section through the 
articular cartilage of a bone which has been 
softened in chromic or other suitable acid, we 
observe that the cartilage-cells are flattened near 
the free surface of the cartilage, and their long 
axes are parallel to the surface of the joint; 
lower down, the cells are arranged in irregular 
groups, and further down still, nearer the bone, 
in columns or rows, whose long axis is in the 
long axis of the bone. These rows are produced 
by transverse cleavage of pre-existing cells. In 
the upper two-thirds or thereby the matrix of 
the cartilage is hyaline, but in the lower third, 
near the bone, the matrix is granular and some- 
times fibrillated. This is the calcified zone, 
which is impregnated with lime salts and sharply 
defined by a nearly straight line from the hyaline 
zone above it, and by a very bold wavy line 
from the osseous head of the bone.] 
Synovial Membrane.—Synovial membrane consists of 
bundles of delicate connective-tissue mixed with elastic 
tissue, while on its inner surface it is provided with folds, 
some of which contain fat, and others blood-vessels (synovial 
villi). The inner surface is lined with endothelium. The 
intra-capsular ligaments and cartilages are not covered by 
the synovial membrane, nor are they covered by endo- 
thelium. 
The synovia is a colorless, stringy, alkaline fluid, with a chemical composition closely allied 
to that of transudations, with this difference, that it contains much mucin, together with 
albumin and traces of fat. Excessive movement diminishes its amount, makes it more inspis- 
sated, and increases the mucin, but diminishes the salts. 
Joints may be divided into several classes, according to the kind of move- 
ment which they permit:— 
1. Joints with movement round one axis: (a) The Ginglymus, or Hinge-Joint.— 
The one articular surface represents a portion of a cylinder or sphere, to which the other 
surface is adapted by a corresponding depression, so that, when flexion or extension of the 
joint takes place, it moves only on one axis of the cylinder or sphere. The joints of the fingers and 
toes are hinge-joints of this description. Lateral ligaments, which prevent a lateral displacement 
of the articular surfaces, are always present. 
The Screw-hinge Joint is a modification of the simple hinge form (.Langer, Henke'), e.g., the 
humero-ulnar articulation. Strictly speaking, simple flexion and extension do not take place 
at the elbow-joint, but the ulna moves on the capitellum of the humerus like a nut on a bolt; in 
the right humerus, the screw is a right spiral, in the left, a left spiral. The ankle-joint is another 
example; the nut or female screw is the tibial surface, the right joint is like a left-handed screw, 
Hyaline 
cartilage. 
Calcified 
cartilage. 
Bone. 
Fig- 423. 
Vertical section of articular cartilage 
(Stirling). 638 
JOINTS. 
[Sec. 305. 
the left the reverse. (b) The Pivot-Joint (rotatoria), with a cylindrical surface, e.g., the 
joint between the atlas and the axis, the axis of rotation being around the odontoid process of 
the axis. In the acts of pronation and supination of the fore-arm at the elbow-joint, the axis 
of rotation is from the middle of the cotyloid cavity of the head of the radius to the styloid 
process of the ulna. The other joints which assist in these movements are above the joint, 
between the circumferential part of the head of the radius and the sigmoid cavity of the ulna, 
and below the joint, between the sigmoid cavity of the radius which moves over the rounded 
lower end of the ulna. 
2. Joints with movements round two axes.—(a) Such joints have two unequally curved 
surfaces which intersect each other, but which lie in the same direction, e.g., the atlanto-occipital 
joint, or the wrist joint, at which lateral movements, as well as flexion and extension take place. 
(b) Joints with curved surfaces, which intersect each other, but which do not lie in the same 
direction. To this group belong the saddle-shaped articulations, whose surface is concave in 
one direction, but convex in the other, e.g., the joint between the metacarpal bone of the thumb 
and the trapezium. The chief movements are—(i) flexion and extension, (2) abduction and 
adduction. Further, to a limited degree, movement is possible in all other directions; and, lastly, 
a pyramidal movement can be described by the thumb. 
3. Joints with movement on a spiral articular surface (spiral joints), e.g., the knee- 
joint {Goodsir). The condyle of the femur, curved from before backwards, in the antero-posterior 
section of its articular surface, represents a spiral {Ed. Weber), whose centre lies nearer the 
posterior part of the condyle, and whose radius vector increases from behind, downwards and 
forwards. Flexion and extension are the chief movements. The strong lateral ligaments arise 
from the condyles of the femur corresponding to the centre of the spiral, and are inserted into 
the head of the fibula and internal condyle of the tibia. When the knee-joint is strongly flexed, 
the lateral ligaments are relaxed—they become tense as the extension increases: and when the 
knee-joint is fully extended, they act quite like tense bands which secure the lateral fixation of 
the joint. Corresponding to the spiral form of the articular surface, flexion and extension do not 
take place around one axis, but the axis moves continually with the point of contact; the axis 
moves also in a spiral direction. The greatest flexion and extension cover an angle of about 
1450. The anterior crucial ligament is more tense during extension, and acts as a check liga- 
ment for too great extension, while the posterior is more tense during flexion, and is a check 
ligament for too great flexion. The movements of extension and flexion at the knee are further 
complicated by the fact that the joint has a screw like movement, in that during the greater 
extension the leg moves outwards. Hence, the thigh, when the leg is fixed, must be rotated 
outwards during flexion. Pronation and supination take place during the greatest flexion to 
the extent of 410 {Albert) at the knee-joint, while with the greatest extension it is nil. It 
occurs because the external condyle of the tibia rotates on the internal. In all positions during 
flexion, the crucial ligaments are fairly and uniformly tense, whereby the articular surfaces are 
against each other. Owing to their arrangement, during increasing tension of the anterior 
ligament (extension), the condyles of the femur must roll more on to the anterior part of the 
articular surface of the tibia, while by increasing tension of the posterior ligament (flexion), they 
must pass more backwards. 
4. Joints with the axis of rotation round one fixed point.—These are the freely movable 
arthrodial joints. The movements can take place around innumerable axes, which all intersect 
each other in the centre of rotation. One articular surface is nearly spherical, tne other is 
cup-shaped. The shoulder and hip-joints are typical “ ball-and-socket-joints.” We may 
represent the movements as taking place around three axes, intersecting each other at right 
angles. The movements which can be performed at these joints may be grouped as: (1) 
pendulum-like movements in any plane, (2) rotation round the long axis of the limb, and (3) 
circumscribing movements [circumduction], such as are made round the circumference of a 
sphere; the centre is in the point of rotation of the joint, while the circumference is described 
by the limb itself. 
Limited arthrodial joints are ball joints with limited movements, and where rotation on the 
long axis is wanting, e.g., the metacarpo-phalangeal joints. 
5. Rigid joints or amphiarthroses are characterized by the fact that movement may occur in 
all directions, but only to a very limited extent, in consequence of the tough and unyielding 
external ligaments. Both articular surfaces are usually about the same size, and are nearly 
plane surfaces, e.g., the articulations of the carpal and the tarsal bones. 
II. Symphyses, synchondroses, and syndesmoses unite bones without the formation of 
a proper articular cavity, are movable in all directions, but only to the slightest extent. Physio- 
logically they are closely related to amphiarthrodial joints. 
III. Sutures unite bones without permitting any movement. The physiological importance 
of the suture is that the bones can still grow at their edges, which thus renders possible the 
distention of the cavity enclosed by the bones {Hertn. v. Meyer). Sec. 306.] 
639 
ARRANGEMENT OF MUSCLES. 
306. ARRANGEMENT AND USES OF MUSCLES. —The mus- 
cles form 45 per cent, of the total mass of the body, those of the right side being 
heavier than those on the left. Muscles may be arranged in the following 
groups, as far as their mechanical actions are concerned :— 
A. Muscles without a definite origin and insertion :— 
1. The hollow muscles surrounding globular, oval, or irregular cavities, 
such as the urinary bladder, gall-bladder, uterus, and heart; or the walls of 
more or less cylindrical canals (intestinal tract, muscular gland-ducts, ureters, 
Fallopian tubes, vasa deferentia, blood-vessels, lymphatics). In all these cases 
the muscular fibres are arranged in several layers, e.g., in a longitudinal and a 
circular layer, and sometimes also in an oblique layer. All these layers act 
together and thus diminish the cavity. It is inadmissible to ascribe different 
mechanical effects to the different layers, e.g., that the circular fibres of the 
intestine narrow it, while the longitudinal dilate it. Both sets of fibres rather 
seem to act simultaneously, and diminish the cavity by making it narrower and 
shorter at the same time. The only case where muscular fibres may act in 
partially dilating the cavity is when, owing to pressure from without, or from, 
partial contraction of some fibres, a fold, projecting into the lumen, has been 
formed. When the fibres, necessarily stretching across the depression thereby 
produced, contract, they must tend to undo it, i. e., enlarge the cavity. The 
various layers are all innervated from the same motor source, which supports 
the view of their conjoint action. 
2. The sphincters surround an opening or a short canal, and by their ac- 
tion they either constrict or close it, e. g., the following “ sphincter muscles” : 
sphincter pupillae, palpebrarum, oris, pylori, ani, cunni, urethrae. 
B. Muscles with a definite origin and insertion :— 
1. The origin is completely fixed when the muscle is in action. The 
course of the muscular fibres, as they pass to where they are inserted, permits 
of the insertion being approximated in a straight line towards their origin dur- 
ing contraction, e.g., the attolens, attrahens, and retrahentes of the outer ear, 
and the rhomboidei. Some of these muscles are inserted into soft parts which 
necessarily must follow the line of traction, e.g., the azygos uvulae, levator 
palati mollis, and most of the muscles which arise from bone and are inserted 
into the skin, such as the muscles of the face, styloglossus, stylopharyngeus, etc. 
2. Both Origin and Insertion Movable.—In this case the movements 
of both points are inversely as the resistance to be overcome. The resistance 
is often voluntary, which may be increased either at the origin or insertion of 
the muscle. Thus, the sterno-cleido-mastoid may act either as a depressor of the 
head or as an elevator of the chest; the pectoralis minor may act as an abductor 
and depressor of the shoulder, or as an elevator of the 3d to 5th ribs (when the 
shoulder girdle is fixed). 
3. Angular Course.—Many muscles having a fixed origin are diverted 
from their straight course ; either their fibres or their tendons may be bent out 
of the straight course. Sometimes the curving is slight, as in the occipito- 
frontalis and levator palpebrae superioris, or the tendon may form an angle 
round some bony process, whereby the muscular traction acts in quite a differ- 
ent direction, i. <?., as if the muscle acted directly from this process upon its 
point of insertion, e.g., the obliquus oculi superior, tensor tympani, tensor veli 
palatini, obturator internus. 
4. Many of the muscles of the extremities act upon the long bones as upon 
levers : (a) Some act upon a lever with one arm, in which case the insertion 
of the muscle (power) and the weight lie upon one side of the fulcrum or point 
of support, e.g., biceps, deltoid. The insertion (or power) often lies very ACTIONS OF MUSCLES. 
[Sec. 306. 
close to the fulcrum. In such a case, the rapidity of the movement at the end 
of the lever is greatly increased, but force is lost [i. e., what is gained in rapidity 
is lost in power]. This arrangement has this advantage, that, owing to the 
slight contraction of the muscle, little energy is evolved, which would be the 
case had the muscular contraction been more considerable (§ 300, I, 3). (i>) 
The muscles act upon the bones as upon a lever with two arms, in which case 
the power (insertion of the muscle) lies on the other side of the fulcrum oppo- 
site to the weight, e. g., the triceps and muscles of the calf. In both cases, the 
muscular force necessary to overcome the resistance is estimated by the prin- 
ciples of the lever: equilibrium is established when the static moments (= pro- 
duct of the power in its vertical distance from the fulcrum) are equal; or when 
the power and weight are inversely proportional, as their vertical distance from 
the fulcrum. 
[The Bony Levers.—All the three orders of levers are met with in the body. Indeed, in the 
elbow-joint all the three orders are represented. The annexed 
scheme shows the relative positions of P, W, and F (fig. 424). The 
first order represented by such a movement as nodding the head, 
the second by raising the body on the tiptoes by the muscles of the 
calf, and the third by the action of the biceps in raising the fore- 
arm. At the elbow-joint, the first order is illustrated by extending 
the flexed fore-arm on the upper arm, as in striking a blow on the 
table, where the triceps attached to the olecranon is the power, 
the trochlea the fulcrum, and the hand the weight. If the hand 
rest on the table and the body be raised on it, then the hand is the 
fulcrum, while the triceps is the power raising the humerus and the 
parts resting on it (W). The third order has already been referred 
to, e.g., flexing the fore arm.] 
Direction of Action.—It is most important to observe the direc- 
. tion in which the muscular force and weight act upon the lever- 
arm. Thus, the direction may be vertical to the lever in one position, while after flexion it may 
act obliquely upon the lever. The static moment of a power acting obliquely on the lever-arm is 
Fig. 424. 
The three orders of levers. 
Fig. 425. 
obtained by multiplying the power with the power acting in a direction vertical to the point of 
rotation. 
Examples ;—In fig. 425 I, B x represents the humerus, and x Z the radius; Ay, the direc- 
tion of the traction of the biceps. If the biceps acts at a right angle only, as by lifting horizon- 
tally a weight (P) lying on the fore-arm or in the hand, then the power of the biceps ( = A) is 
obtained from the formula, A y x = P x Z, i. e., A = (P x Z) : y x. It is evident that, when the 
radius is depressed to the position x C, the result is different; then the force of the biceps 
Scheme of the action of the muscles on bones. Sec. 306.] 
MUSCLES ACTING ON JOINTS. 
= Aj = (Px v x) : o x. In fig. 425, II, T F is the tibia, F, the ankle-joint, M C, the foot in a 
horizontal position. The power of the muscles of the calf ( = a) necessary to equalize a force,/, 
directed from below against the anterior part of the foot, would be a = (/ M F) : F C. If the 
foot be altered to the position R S, the force of the muscles of the calf would then be a1 = 
(/! MF):F C. 
In muscles also, which, like the coraco-brachialis, are stretched over the angle 
of a hinge, the same result obtains. 
In fig. 425, III, H E is the humerus, E, the elbow-joint, E R, the radius, B R, the coraco- 
brachialis. Its moment in this position is = A, a E. When the radius is raised to E Rlf then 
it is = A, a E. We must notice, however, that B Rj < B R. Hence, the absolute muscula r 
force must be less in the flexed position, because every muscle, as it becomes shorter, lifts less 
weight. What is lost in power is gained by the elongation of the lever-arm. 
5. Many muscles have a double action ; when contracted in the ordinary 
way they execute a combined movement, e. g., the biceps is a flexor and supi- 
nator of the fore-arm. If one of these movements be prevented by the action 
of other muscles, the muscle takes no part in the execution of the other move- 
ment. 
If the fore-arm be strongly pronated and flexed in this position, the biceps takes no part 
therein; or, when the elbow-joint is rigidly supinated, only the supinator brevis acts, not the 
biceps. The muscles of mastication are another example. The masseter elevates the lower jaw, 
and at the same time pulls it forward. If the depressed jaw, however, be strongly pulled back- 
wards, when the jaw is raised, the masseter is not concerned. The temporal muscle raises the 
jaw and at the same time pulls it backwards. If the depressed jaw be raised after being pushed 
forward, then the temporal is not concerned in its elevation. 
6. Muscles acting on two or more joints are those which, in their 
course from their origin to their insertion, pass over two or more joints. Either 
the tendons may deviate from a straight course, e. g., the extensors and flexors 
of the fingers and toes, as when the latter are flexed ; or the direction is always 
straight, e.g., the gastrocnemius. The muscles of this group present the following 
points of interest—(a) The phenomenon of so-called “ active insufficiency.” 
If the position of the joints over which the muscle passes be so altered that its 
origin and insertion come too near each other, the muscle may require to con- 
tract so much before it can act on the bones attached to it, that it cannot con- 
tract actively any further than to the extent of the shortening from which it 
begins to be active; e. g., when the knee-joint is bent, the gastrocnemius can 
no longer produce plantar flexion of the foot, but the traction on the tendo- 
Achillis is produced by the soleus. (£) “ Passive insufficiency ” is shown 
by many jointed muscles under the following circumstances: In certain posi- 
tions of the joint, a muscle may be so stretched that it may act like a rigid 
strap, and thus limit or prevent the action of other muscles, e.g., the gas- 
trocnemius is too short to permit complete dorsal flexion of the foot when 
the knee is extended. The long flexors of the leg, arising from the tuber ischii, 
are too short to permit complete extension of the knee-joint when the hip-joint 
is flexed at an acute angle. The extensor tendons of the fingers are too short 
to permit of complete flexion of the joints of the fingers when the hand is com- 
pletely flexed. 
7. Synergetic muscles are those which together subserve a certain kind 
of movement, e. g., the flexors of the leg, the muscles of the calf, and others. 
The abdominal muscles act along with the diaphragm in diminishing the abdo- 
men during straining, while the muscles of inspiration or expiration, even the 
different origins of one muscle, or the two bellies of a biventral muscle, may be 
regarded from the same point of view. 
Antagonistic muscles are those which, during their action, have exactly 
the opposite effect of other muscles, e.g., flexors and extensors—pronators and 
supinators—adductors and abductors—elevators and depressors—sphincters and 
dilators—inspiratory and expiratory. 642 
[Sec. 306. 
MOTOR DISTURBANCES. 
When it is necessary to bring the full power of our muscles into action we 
quite involuntarily bring them beforehand into a condition of the greatest ten- 
sion, as a muscle in this condition is in the most favorable position for doing 
work (§ 300, I, 3). Conversely, when we execute delicate movements requir- 
ing little energy, we select a position in which the corresponding muscle is 
already shortened. 
All the fasciae of the body are connected with muscles, which, when they contract, alter the 
tension of the former, so that they are in a certain sense aponeuroses or tendons of the latter (A”. 
Bardeleben). [For the importance of muscular movements and those of fasciae in connection 
with the movements of the lymph, see \ 201.] 
307. GYMNASTICS; MOTOR PATHOLOGICAL VARIA- 
TIONS.—Gymnastic exercise is most important for the proper develop- 
ment of the muscles and motor power, and it ought to be commenced in both 
sexes at an early age. Systematic muscular activity increases the volume of the 
muscles, and enables them to do more work. The amount of blood is in- 
creased with increase in the muscular development, while at the same time 
the bones and ligaments become more resistant. As the circulation is more 
lively in an active muscle, gymnastics favor the circulation, and ought to 
be practiced, especially by persons of sedentary habits, who are apt to suffer 
from congestion of blood in abdominal organs (<?.£•., haemorrhoids), as it 
favors the movement of the tissue juices [§ 201]. An active muscle also uses 
more O and produces more C02, so that respiration is also excited. The total 
increase of the metabolism gives rise to the feeling of well-being and vigor, 
diminishes abnormal irritability, and dispels the tendency to fatigue. The 
whole body becomes firmer, and specifically heavier (Jdger). 
By Ling’s, or the Swedish system, a systematic attempt is made to strengthen certain weak 
muscles, or groups of muscles, whose weakness might lead to the production of deformities. 
These muscles are exercised systematically by opposing to them resistances, which must either 
be overcome, or against which the patient must strive by muscular action. 
Massage, which consists in kneading, pressing, or rubbing the muscles, favors the blood- 
stream; hence, this system may be advantageously used for such muscles as are so weakened by 
disease that an independent treatment by means of gymnastics cannot be adopted. [The im- 
portance of massage as a restorative practice in getting rid of the waste products of muscular 
activity has been already referred to (| 304).] 
Disturbances of the normal movements may partly affect the passive motor organs (e.g., 
the bones, joints, ligaments, and aponeuroses), or the active organs (muscles with their tendons, 
and motor nerves). 
Passive Organs.—Fractures, caries and necrosis, and inflammation of the bones, which 
make movements painful, influence or even make movement impossible. Similarly, dislocations, 
relaxation of the ligaments, arthritis, or anchylosis interfere with movement. Also curvature of 
bones, hyperostosis or exostosis; lateral curvature of the vertebral column (Scoliosis), back- 
ward angular curvature (Kyphosis), or forward curvature (Lordosis). The latter interfere 
with respiration. In the lower extremities, which have to carry the weight of the body, genu 
valgum may occur in flabby, tall, rapidly-growing individuals, especially in some trades, e.g., 
in bakers. The opposite form, genu varum, is generally a result of rickets. FlaJ foot depends 
upon a depression of the arch of the foot, which then no longer rests upon its three points of sup- 
port. Its causes seem to be similar to those of genu valgum. The ligaments of the small tarsal 
joints are stretched, and the long axis of the foot is usually directed outwards; the inner margin 
of the foot is more turned to the ground, while pain in the foot and malleoli make walking and 
standing impossible. Club-foot (Talipes varus), in which the inner margin of the foot is raised, 
and the point of the toes is directed inwards and downwards, depends upon imperfect develop- 
ment during foetal life. All children are born with a certain very slight degree of bending of the 
foot in this direction. Talipes equinus, in which the toes, and T. calcaneus, in which the 
heel touches the ground, usually depend upon contracture of the muscles causing these positions 
of the foot, or upon paralysis of the antagonistic muscles. 
Rickets and Osteomalacia.—If the earthy salts be withheld from the food, the bones 
gradually undergo a change ; they become thin, translucent, and may even bend under pressure. 
In certain persistent defects of nutrition, the lime and other salts of the food are not absorbed, 
giving rise to rachitis, or rickets, in children. If fully formed bones lose their lime-salts to the Sec. 307.] 
DISEASES AFFECTING MUSCLES. 
643 
extent of ]/2 to )/$ (halisterisis), they become brittle and soft (osteomalacia). This occurs to 
a limited extent in old age. 
Muscles.—The normal nutrition of muscle is intimately dependent on a proper supply of 
sodium chloride and potash salts in the food, as these form integral parts of the muscular tissue 
(.Kemmerich, Forster). Besides the atrophic changes which occur in the muscles when these 
substances are withheld, there are disturbances of the central nervous system and digestive appa- 
ratus, and the animals ultimately die. The condition of the muscles during inanition is given 
in \ 237. If muscles and bones be kept inactive, they tend to atrophy (§ 244). In atrophic 
muscles, and in cases of anchylosis, there is an enormous increase, or “ atrophic proliferation,” 
of the muscle-corpuscles, which takes place at the expense of the contractile contents (Cohn- 
heim). A certain degree of muscular atrophy takes place in old age. The uterus, after delivery, 
undergoes a great decrease in size and weight—from 1000 to 350 grams—due chiefly to the 
diminished blood-supply to the organ. In chronic lead poisoning, the extensors and interossei 
chiefly undergo atrophy. Atrophy and degeneration of the muscles are followed by shortening 
and thinning of the bones to which the muscles are attached. 
Section and paralysis of the motor nerves cause palsy of the muscles, thus rendering 
them inactive, and they ultimately degenerate. Atrophy also occurs after inflammation or soften- 
ing of the multipolar nerve-cells in the anterior horn of the gray matter of the spinal cord, or 
the motor nuclei (facial, spinal accessory, and hypoglossal of Stilling in the medulla oblongata), 
in the muscles connected with these parts. Rapid atrophy takes place in certain forms of spinal 
paralysis and in acute bulbar paralysis (paralysis of the medulla oblongata), and in a chronic 
form in progressive muscular atrophy and progressive bulbar paralysis. The muscles and their 
nerves become small and soft. The muscles show many nuclei, the sarcous substance becomes 
fatty, and ultimately disappears. According to Charcot, these areas are at the same time the 
trophic centres for the nerves proceeding from them, as well as for the muscles belonging to 
them. According to Friedreich, the primary lesion in progressive muscular atrophy is in the 
muscles, and is due to a primary interstitial inflammation of the muscle, resulting in atrophy and 
degenerative changes, while the nerve-centres are affected secondarily, just as after amputation 
of a limb, the corresponding part of the spinal cord degenerates. 
In pseudo-hypertrophic muscular atrophy the muscular fibres atrophy completely, with 
copious development of fat and connective-tissue between the fibres, without the nerves or spinal 
cord undergoing degeneration. The muscular substance may also undergo amyloid or wax- 
like degeneration, whereby the amyloid substance infiltrates the tissue ($ 249, VI). Sometimes 
atrophic muscles have a deep brown color, due to a change of the haemoglobin of the muscle. 
When muscles are much used they hypertrophy, as the heart in certain cases of valvular lesion 
or obstruction (§ 40), the bladder, and intestine. [In true hypertrophy there is an increased 
number, or increase in the size, of its tissue elements, throughout the entire tissue or organ, with- 
out any deposit of a foreign body. Perhaps, in hypertrophy of the bladder, the thickened mus- 
cular coat not only serves to overcome resistance, but it offers greater resistance to bursting 
under the increased intra-vesical pressure. Mere enlargement is not hypertrophy, for this may 
be brought about by foreign elements. In atrophy there is a diminution in size or bulk, even 
when the blood-stream is kept up, the decrease being due to pressure. An atrophied organ may 
be even enlarged, as seen in pseudo-hypertrophic paralysis, where the muscles are larger, owing 
to the interstitial growth of fatty and connective-tissue, while the true muscular tissue is dimin- 
ished and truly atrophied.] 
Special Muscular Acts. 
308. STANDING.—' The act of standing is assured by muscular action, 
and is the vertical position of equilibrium of the body, in which a line drawn 
from the centre of gravity of the body falls within the area of both feet placed 
upon the ground. In the military attitude, the muscles act in two directions 
—(i) to fix the jointed body, as it were, into one unbending column ; and (2) 
in case of a variation of the equilibrium, to compensate by muscular action for 
the disturbance of the equilibrium. 
The following individual motor acts occur in standing:— 
I. Fixation of the head upon the vertebral column. The occiput may be moved in various 
directions upon the atlas, as in the acts of nodding. - As the long arm of the lever lies in front 
of the atlas, necessarily when the muscles of the back of the neck relax, as in sleep or death, 
the chin falls upon the breast. The strong neck muscles, which pull from the vertebral column 644 
STANDING. 
[Sec. 308. 
upon the occiput, fix the head in a firm position on the vertebral column. The chief rotatory 
movement of the head on a vertical axis occurs round the odontoid process of the axis. The 
articular surfaces on the pedicles, and part of the bodies of the 1st and 2d vertebrae, are convex 
towards each other in the middle, becoming somewhat lower in front and behind, so that the 
head is highest in the erect posture. Hence, when the head is greatly rotated, compression of 
the medulla oblongata is prevented (Henke). In standing, these muscles do not require to be 
fixed by muscular action, as no rotation can take place when the neck muscles are at rest. 
2. Fixed Vertebral Column.—The vertebral column itself must be fixed, especially where 
it is most mobile, i. e., in the cervical and lumbar regions. This is brought about by the strong 
muscles situate in these regions, e. g., the cervical spinal muscles, Extensor dorsi communis and 
Quadratus lumborum. 
Mobility of the Vertebrae.—The least movable vertebrae are the 3d to the 6th dorsal; the 
sacrum is quite immovable. For a certain length of the column the mobility depends on (a) 
the number and height of the interarticular fibro-cartilages. They are most numerous in the 
neck, thickest in the lumbar region, and relatively also in the lower cervical region. They 
permit movement to take place in every direction. Collectively the interarticular discs form 
one-fourth of the height of the whole vertebral column. They are compressed somewhat by the 
pressure of the body; hence, the body is longest in the morning and after lying in the horizontal 
position. The smaller periphery of the bodies of the cervical vertebrae favors the mobility of 
these vertebrae compared with the larger lower ones. (b) The position of the processes also 
influences greatly the mobility. The strongly depressed spines of the dorsal region hinder 
hyperextension. The articular processes on the cervical vertebrae are so placed that their sur- 
faces look obliquely from before and upwards, backwards, and downwards; this permits rela- 
tively free movement, rotation, lateral and nodding movements. In the dorsal region, the 
articular surfaces are directed vertically and directly to the front, the lower directly backwards; 
in the lumbar region the position of the articular processes is almost completely vertical and 
antero-posterior. In bending backwards as far as possible, the most mobile parts of the column 
are the lower cervical vertebrae, the nth dorsal to the 2d lumbar, and the lower two lumbar 
vertebrae (E. H. Weber). 
3. The centre of gravity of the head, trunk, and arms when fixed as above, lies in front ot 
the 10th dorsal vertebra. It lies further forward, in a horizontal plane, passing through the 
xiphoid process, the greater the distention of the abdomen by food, fat, or pregnancy. A line 
drawn vertically downwards from the centre of gravity passes behind the line uniting both hip- 
joints. Hence, the trunk would fall backwards on the hip-joint, were it not prevented partly 
by ligaments and partly by muscles. The former are represented by the ileo-femoral band and 
the anterior tense layer of the fascia lata. As ligaments alone, however, never resist permanent 
traction, they are aided, especially by the ileo-psoas muscle inserted into the small trochanter, 
and in part, also, by the rectus femoris. Lateral movement at the hip-joint, whereby the one 
limb must be abducted and the other adducted, is prevented especially by the large mass of the 
glutei. When the leg is extended, the ileo-femoral ligament, aided by the fascia lata, prevents 
adduction. 
4. The rigid part of the body, head, and trunk, with the arms and legs, whose centre of 
gravity lies lower and only a little in front, so that the vertical line drawn downwards intersects 
a line connecting the posterior surfaces of the knee-joints, must now be fixed at the knee-joint. 
Falling backwards is prevented by a slight action of the quadriceps femoris, aided by the tension 
of the fascia lata. Indirectly it is aided also by the ileo-femoral ligament. Lateral movement 
of the knee is prevented by the disposition of the strong lateral ligaments. Rotation cannot 
take place at the knee-joint in the extended position (§ 305, I, 3). 
5. A line drawn downwards from the centre of gravity of the whole body, which lies in the 
promontory, falls slightly in front of a line between the two ankle-joints. Hence, the body 
would fall forward on the latter joint. This is prevented especially by the muscles of the calf, 
aided by the muscles of the deep layer of the leg (tibialis posticus, flexors of the toes, peroneus 
longus et brevis). 
Other factors : (a) As the long axis of the foot forms with the leg an angle of 50°, falling 
forward can only occur after the feet are in a position more nearly parallel with their long axis. 
(3) The form of the articular surfaces helps, as the anterior broad part of the astragalus must be 
pressed between the two malleoli. The latter mechanism cannot be of much importance. 
6. The metatarsus and phalanges are united by tense ligaments to form the arch of the foot, 
which touches the ground at three points—tuber calcanei (heel), the head of the first metatarsal 
bone (ball of the great toe), and of the fifth toe. Between the latter two points, the heads of 
the metatarsal bones also form points of support. The weight of the body is transmitted to the 
highest part of the arch of the foot, the caput tali. The arching of the foot is fixed only by 
ligaments. The toes play no part in standing, although, when moved by their muscles, they 
greatly aid the balancing of the body. The maintenance of the erect attitude fatigues one 
more rapidly than walking. Sec. 309.] 
SITTING WALKING. 
645 
309. SITTING.—Sitting is that position of equilibrium whereby the body 
is supported on the tubera ischii, on which a to and fro movement may take 
place {//. v. Meyer). The head and trunk together are made rigid to form an 
immovable column, as in standing. 
We may distinguish—(i) the forward posture, in which the line of gravity passes in front 
of the tubera ischii; the body being supported either against a fixed object, e. g., by means of 
the arm on a table, or against the upper surface of the thigh. (2) The backward posture, 
in which the line of gravity falls behind the tubera. A person is prevented from falling back- 
ward either by leaning on a support, or by the counter-weight of the legs kept extended by mus- 
cular action, whereby the sacrum forms an additional point of support, while the trunk is fixed 
on the thigh by the ileo-psoas and rectus femoris, the leg being kept extended by the extensor 
quadriceps. Usually the centre of gravity is so placed that the heel also acts as a point of sup- 
port. The latter sitting posture is of course not suited for resting the muscles of the lower 
limbs. (3) When “ sitting erect ” the line of gravity falls between the tubera themselves. 
When the muscles of the legs are relaxed, the rigid trunk only requires to be balanced by slight 
muscular action. Usually the balancing of the head is sufficient to maintain the equilibrium. 
310. WALKING, RUNNING AND SPRINGING.—By the term 
walking is understood progression in a forward horizontal direction with the 
least possible muscular exertion, due to the alternate activity of the two legs. 
Methods.—The Brothers Weber were the first to analyze the various positions of the body in 
walking, running, and springing, and they represented them in a continuous series, which repre- 
sents the successive phases of locomotion. These phases may be examined with the zoetrope 
(| 398, 3). Marey estimated the time relations of the individual acts by transferring the move- 
ments by means of his air-tambours to a recording surface. Recently, by means of a revolving 
camera, he has succeeded in photographing, in instantaneous pictures second), the whole 
series of acts. Of course this series, when placed in the zoetrope, represents the natural move- 
ments. Figs. 427, 428, 429 represent these acts. 
In walking, the legs are active alternately; while one—the “ supporting ” 
or “active” leg—carries the trunk, the other is “inactive” or “passive.” 
Each leg is alternately in an active and a passive phase. Walking may be 
divided into the following movements: — 
I. Act (fig. 426, 2).—The active leg is vertical, slightly flexed at the knee, and it alone sup- 
ports the centre of gravity 
of the body. The passive 
leg is completely extend- 
ed, and touches the ground 
only with the tip of the 
great toe (z). This posi- 
tion of the leg corresponds 
to a right-angled triangle, 
in which the active leg 
and the ground form two 
sides, while the passive 
leg is the hypothenuse. 
II. Act.—For the for- 
ward movement of the 
trunk, the active leg is 
inclined slightly from its 
vertical position (cathetus) 
to an oblique and more 
forward (hypothenuse) po- 
sition (3). In order that 
the trunk may remain at 
the same height, it is 
necessary that the active 
leg be lengthened. This is accomplished by completely extending the knee (3, 4, 5), as well as 
by lifting the heel from the ground (4, 5), so that the foot rests on the balls or the heads of the 
metatarsal bones, and, lastly, by elevating it on the point of the great toe (2, thin line). During 
the extension and forward movement of the active leg, the tips of the toes of the passive leg 
have left the ground (3)- It is slightly flexed at the knee-joint (owing to the shortening), it 
Fig. 426. 
Phases of walking. The thick lines represent the active, the thin the 
passive leg; h, the hip-joint; k, a, knee; f, b, ankle; c, d, heel; 
m, e, ball of the tarso-metatarsal joint; z, g, point of great toe. 646 
WALKING. 
[Sec. 310. 
performs a “ pendulum-like movement ” (4, 5), whereby its foot is moved as far in front of the 
active leg as it was formerly behind it. The foot is then placed flat upon the ground (1,2, thick 
lines); the centre of gravity is now transferred to this active leg, which at the same time is 
slightly flexed at the knee, and placed vertically. The first act is then repeated. 
Simultaneous Movements of the Trunk.—During walking the trunk performs certain 
Fig. 427. 
Phases of slow walking. Instantaneous photograph ; only the side directed to the observer is 
shown. From the vertical position of the right, active leg; (I), all the phases of this leg 
are represented in six pictures (I to VI), while after VI the vertical position is regained. 
The Arabic numerals indicate the simultaneous position of the corresponding left leg; 
thus 1 = I, 2 = II, etc., so that during the position IV of the right leg, at the same time 
the left leg has the position as 1. 
characteristic movements. (1) It leans every time towards the active leg, owing to the traction 
of the glutei and the tensor fasciae latae, so that the centre of gravity is moved, which in short 
heavy persons with a broad pelvis leads to their “ waddling” gait. (2) The trunk, especially 
during rapid walking, is inclined slightly forward to overcome the resistance of the air. (3) 
During the “ pendulum-like action,” the trunk rotates slightly on the head of the active femur. 
This rotation is compensated, especially in rapid walking, by the arm of the same side as the 
Fig. 428. 
Instantaneous photograph of a runner. Ten pictures per second. The abscissa indicates the 
length of the step in metres. 
oscillating leg swinging'in the opposite direction, while that on the other side at the same time 
swings in the same direction as the oscillating limb. 
Modifying Conditions: I. The Duration of the Step.—As the rapidity of the vibration of 
a pendulum (leg) depends upon its length, it is evident that each individual, according to the 
length of his legs, must have a certain natural rate of walking. The “ duration of a step ”■ Sec. 310.] 
RUNNING. 
647 
depends also upon the time during which both feet touch the ground simultaneously, which, ot 
course, can be altered voluntarily. When “ walking rapidly ” the time = o, i. <?., at the same 
moment in which the active leg reaches the ground, the passive leg is raised. The length of the 
step is usually about 6 to 7 decimetres [23 to 27 inches], and it must be greater the more the 
length of the hypothenuse of the passive leg exceeds the cathetus of the active one. Hence, 
during a long step, the active leg is greatly shortened (by flexion of the knee), so that the trunk 
is pulled downwards. Similarly, long legs can make longer steps. 
According to Marey and others, the pendulum movement of the passive leg is not a true 
pendulum movement, because its movement, owing to muscular action, is of more uniform ra- 
pidity. During the pendulum movement of the whole limb, the leg vibrates by itself at the knee- 
joint (Luces, H. Vierordt). 
Fixation of the Femur.—According to Ed. and W. Weber, the head of the femur of the 
passive leg is fixed in its socket chiefly by the atmospheric pressure, so that no muscular ac- 
tion is necessary for carrying the whole limb. If all the muscles and the capsule be divided, 
the head of the femur still remains in the cotyloid cavity. Rose refers this condition not to the 
action of the atmospheric pressure, but to two adhesion surfaces united by means of synovia. 
The experiments of Aeby show that not only the weight of the limb is supported by the 
atmospheric pressure, but that the latter can support several times this weight. When traction is 
Fig. 429. 
High leap. Instantaneous photograph. The pictures partly overlap each other, as soon as the 
velocity of the forward movement on the descent diminishes after springing. In the left- 
hand corner is the dial plate, the radius of which moved one division in second. The 
abscissa indicates the distance in metres. 
exerted on the limb, the margins of the cotyloid ligament of the cotyloid cavity are applied like a 
valve tightly to the margin of the cartilage of the head of the femur. According to the Brothers 
Weber, the leg falls from its socket as soon as air is admitted by making a perforation into the 
articular cavity. 
Work done during Walking.—Marey and Demery estimate the amount done by a man 
weighing 64 kilos. [10 stones], when walking slowly, as = 6 kilogrammetres per second; rapid 
running = 56 kilogrammetres. The work done is due to the raising of the entire body and 
extremities, to the velocity communicated to the body, as well as to the maintenance of the centre 
of gravity. 
In springing or leaping, the body is rapidly projected upwards by the greatest possible and 
most rapid contraction of the muscles, while at the same time the centre of gravity is maintained 
by other muscular acts (fig. 429). 
The pressure upon the sole of the foot in walking is distributed in the following manner : 
The supporting leg always presses more strongly on the ground than the other; the longer the 
step the greater the pressure. The heel receives the maximum amount of pressure sooner than 
the point of the foot (Carlet). 
Running is distinguished from rapid walking by the fact that, at a particular 
moment, both legs do not touch the ground, so that the body is raised in the 648 
MOTOR ACTS IN ANIMALS. 
[Sec. 310. 
air. The active leg, as it is forcibly extended from a flexed position, gives the 
body the necessary impetus (fig. 429). 
Pathological.—Variations of the walking movements depend primarily upon diseases of 
bones, ligaments, muscles, and tendons, and also upon affections of the motor nerves. The effect 
of sensory nerves and the reflex mechanism of the spinal cord, and also of the muscular sense 
on walking, are stated in §§ 355, 360, 430. 
311. COMPARATIVE.—The absolute muscular force in animals is 
not, as a rule, much different from that in man. The great motor power exerted 
by animals results from the thickness and number of the muscles, as well as 
from the different arrangement of the levers and the action of muscles on them. 
Insects particularly exert a large amount of force; some insects can drag a body 
sixty-seven times their own weight; a horse scarcely its own weight. A man 
pressing upon a dynamometer with one hand exerts pressure — 0.70 times his 
own weight, while a dog lifting its lower jaw exerts 8.3 times ; a crab by closing 
its pincers 28.5 times; and a mussel on closing its shell 382 times its body- 
weight (Plateau). 
In mammals standing is much more easy, as they have four supporting surfaces. The 
springing animals have a sitting attitude, while the tail is often used as a support (kangaroo, 
squirrel). In birds there is a mechanical arrangement by which, while perching, the tendons are 
flexed; hence, a bird while sleeping can still retain its hold (Cuvier). In the stork and crane, 
which stand for a long time on one leg, this act is unaccompanied by muscular action, as the 
tibia is fixed by means of a process which fits into a depression of the articular surface of the 
femur. 
In walking, we distinguish in mammals the step (le pas)—the four feet are generally moved 
in four tempo, and usually diagonally, e.g., in the horse right fore, left hind; left fore, right 
hind. [The camel is an exception—it moves the fore and hind limbs simultaneously on each 
side.] In trotting this movement is accelerated; the two limbs in a diagonal direction lift to- 
gether, so that only two hoof-sounds are heard, while at the same time the body is raised more 
in the air. During the interval between two hoof-beats the body is free in the air, all the 
limbs having left the ground. Strictly speaking, the fore limb leaves the ground slightly sooner 
than the hind one. The gallop.—When a (right) galloping horse moves in the air, the upper 
part of its body is fairly horizontal; when it touches the ground, the left hind foot is the first to 
touch the ground. Shortly thereafter, the left fore and right hind foot touch the ground, while 
the right fore leg has not yet reached the ground and is directed forward. The upper part of 
the body still retains its horizontal direction. When, however, a few moments thereafter the left 
hind leg again leaves the ground, it is higher than the fore leg—simultaneously the right fore leg 
is thrown forward and lower, while the right hind and left fore leg are stretched to the extreme. 
Immediately thereafter these limbs leave the ground, while the hind limb so far overtakes the 
fore limb that it comes to lie higher than the latter. The body, therefore, is projected forwards 
and downwards until the right fore-limb, which alone touches the ground, actively contracts and 
again raises the body from the ground. When this happens, the horse again moves in the air, 
its body being directed horizontally. The long axis of the horse’s body in galloping is placed 
obliquely to the direction of movement, and forming a right angle. In forced galloping (la 
carriere), which is really a springing movement, the right hind leg and left fore leg do not touch 
the ground at the same time, but the former does so sooner. The amble is a modification of 
the step, which consists in this, that both feet on the same side move at the same time or shortly 
after each other (camel, giraffe, elephant). Marey attached compressible ampullae under the 
hoof of a horse, connecting them with registering apparatus, and thus accurately registered the 
time relation of each act. Muybridge photographed the actions of a horse and the different 
phases of the movement. 
In snakes the rudder-like elevation and depression of the ribs cause the progression of the 
body. 
Swimming is an acquired art in man. The specific gravity of the body is slightly greater 
than that of ordinary water, but slightly lighter than that of sea water. When lying quietly on 
the back, so that only the mouth and nose are at last above the water, very slight movements of 
the hands are necessary to keep a person from sinking. In this position, progression can be 
accomplished by extending and adducting the legs, while the movement is accelerated by 
rudder-like movements of the arms. Swimming belly downwards is more difficult, because the 
head being held above the water makes the body specifically heavier. The forward movement 
and the act of supporting the body in the water consist of three acts: First, horizontal, rudder- 
like movements of the extended arms from before backwards, until they reach the horizontal Sec. 311.] 
VOICE. 
649 
position (forward movement) ; second, pressure of the arms downward with subsequent adduc- 
tion of the elbow-joint to the body (elevation of the body), together with retraction of the 
extended legs; third, projection of the arms, now brought together, and at the same time exten- 
sion and adduction of the legs obliquely backwards and downwards, thus causing elevation of 
the body as well as a forward movement. Too rapid movements cause fatigue, while the respi- 
rations must be carefully regulated. Many land mammals, whose body is specifically lighter 
than water, can swim, especially with the aid of their hind limbs, while at the same time all the 
legs being directed downwards, and being specifically the heaviest part of the body, keep the 
trunk in the normal position. Fishes chiefly use their tail fin as a motor organ, which is moved 
by powerful lateral muscles. When the tail is suddenly extended, it presses upon the water and 
displaces it. Some fish, as the salmon, can lift their body out of the water by a blow of their tail 
fin. The dorsal and anal fins enable the animal to preserve the erect position. The pectoral 
and abdominal fins corresponding to the extremities execute slight movements, especially 
upwards and downwards, which are greater during sleep. The swimming-bladder is the 
homologue of the lung, and is used for hydrostatic purposes in some fishes, and as an auxiliary 
respiratory organ in others, e. g., the dipnoi ($ 140). It is absent or rudimentary in the cyclos- 
tomata. In swimming birds, the body is specifically very much lighter than the water, while 
their feathers are lubricated by the oily secretion of the coccygeal glands (§ 291). Their feet 
are usually webbed. 
Flight.—Bats and their allies are the only flying mammals. The bones of the upper limb 
and phalanges are greatly elongated, and between these and the elongated hind limb (except the 
foot) there is stretched a thin membrane. The membrane is moved by the powerful pectoral 
muscles. The flying squirrel has only a duplicature of the skin stretched between the large 
bones of the extremities, which serves as a parachute when the animal springs. In birds the 
body is specifically light; numerous air-sacs in the chest and belly communicate with the lungs, 
and with the cavities of most of the bones ($ 140). The modified upper extremities are supported 
by the coracoid bone and the united clavicles or furculum, and are moved by the powerful 
pectoral muscles attached to the keeled sternum. Marey, by means of his revolving photographic 
camera, has analyzed all the phases of flight in a bird. 
[Warner has studied the movements of the fingers, and correlated these movements with 
changes in the nerve-centres in certain diseased conditions, e. g., chorea. An india-rubber tube 
is attached to each finger, and this “motor” part of the apparatus is connected with a Marey’s 
tambour. The several finger-tubes are fixed to an arrangement not unlike a cricketer's glove, so 
that voluntary or involuntary movements of the fingers can be registered and studied.] 
Voice and Speech. 
312. VOICE, PHYSICAL CONSIDERATIONS.—The blast of 
expired air—and under certain circumstances, the inspiratory blast also—is 
employed to throw the tense vocal cords into a state of regular vibration, 
whereby a sound is produced. The sound so produced is the human voice. 
The true vocal cords are really elastic “ membranous” reeds. If a blast of air be forcibly 
driven upwards through the partially closed glottis, the vocal cords are pushed asunder, as the 
elastic tension of the air overcomes the resistance of the cords. After the escape of air from 
below, the cords rapidly return to their former position, and are again pushed asunder, and 
caused to vibrate. 
1. Thus, when a membrane vibrates, the air must be alternately condensed and rarefied. The 
condensation and rarefaction are the chief cause of the tone or note (as in the siren), not so much 
the membranes themselves (v. Helmholtz). 
2. The air-tube or “ porte vente,” conducting the air to the membranes in man is the lower 
portion of the larynx, the trachea, and the whole bronchial system; the bellows are represented 
by the chest and lungs, which are forcibly diminished in size by the expiratory muscles. 
3. The cavities which lie above the membranes constitute “ resonators,” and consist of the 
upper part of the larynx, pharynx, and also of the cavities of the nose and mouth, arranged, as 
it were, in two stories, the one over the other, which can be closed alternately. 
The pitch of the tone produced by a membranous apparatus depends upon the following 
factors :— 
(«) On the length of the elastic membranes or plates. The pitch is inversely proportional to 
the length of the elastic membrane, i. e., the shorter the membrane the higher the pitch, or the 
greater the number of vibrations per second. Hence, the pitch of a child’s vocal cords (shorter) 
is higher than that of an adult. 650 
THE LARYNX. 
[Sec. 312. 
(b) The pitch of the tone is directly proportional to the square root of the amount of the 
elasticity of the elastic membrane. In membranous reeds, and also with silk, it is directly pro- 
portional to the square root of the extending weight, which in the case of the larynx is the force 
of the muscle rendering the cords tense. 
(<r) The tone of membranous reeds is not only strengthened by a more powerful blast, as the 
amplitude of the vibrations is increased, but the pitch of the tone may also be raised at the same 
time, because, owing to the great amplitude of the vibration, the mean tension of the elastic 
membrane is increased. 
(d) The supra-laryngeal cavities, which act as resonators, are also inflated when the larynx 
is in action, so that the tone produced by these cavities is added to and blended with the sound 
Fig. 430. 
Fig. 43 *• 
Fig. 430.—Larynx from the front, with the ligaments and the insertions of the muscles. 
O. h., Os hyoideum; C.th., Cart, thyreoidea; Corp.trit., Corpus triticeum; C. c., Cart, 
cricoidea; C.tr., Cart, tracheales; Lig. thyr.-hyoid. med., Ligamentum thyreo-hyoideum 
medium; Lig. th.-h. lat., Ligam. thyreo-hyoideum laterale; Lig. cric.-thyr. med., Ligam. 
crico-thyreoideum medium; Lig. cric.-track., Ligam. crico-tracheale; M. st.-h., Muse, 
sterno-hyoideus ; M. th.-hyoid., Muse, thyreo-hyoideus; M.st.-lh., Muse, sterno-thyreo- 
ideus; M. cr.-tk., Muse, crico-thyreoideus. Fig. 431.—Larynx from behind after removal 
of the muscles. E., Epiglottis cushion (W.); L. ar.-ep., Lig. ary-epiglotticum; M. m., 
Membrana mucosa; C. W., Cart. Wrisbergii; C. S., Cart. Santorini; C.aryt., Cart, ary- 
tsenoidea; C. c., Cart, cricoidea; P. m., Processus muscularis of Cart, ary tarn.; L. cr.-ar., 
Ligam. crico-arytaen.; C. s., Cornu superius; C. i., Cornu inferius Cart, thyreoidea; 
L. ce.-cr. p. i., Lig. kerato-cricoideum. post, inf.; C. tr., Cart, tracheales; P.m.tr., Pars 
membranacea tracheae. 
of the elastic membranes, whereby certain partial tones of the latter are strengthened (§ 415). 
The characteristic timbre of the voice largely depends upon the form of the resonators. 
(f) When vocalizing, the strongest resonance takes place in the air-tubes, as they contain 
compressed air. It causes the vocal fremitus which is audible on placing the ear over the chest 
(I ”7,6). 
(f) Narrowing or dilating the glottis has no effect on the pitch of the tone, only with a wide 
glottis much more air must be driven through it, which, of course, greatly increases the work of 
the thorax. 
313. ARRANGEMENT OF THE LARYNX.—I. Cartilages and 
Ligaments.—The fundamental part of the larynx consists of the cricoid Sec. 313.] 
THE LARYNX. 
651 
cartilage, whose small narrow portion is directed forwards and the broad plate 
backwards. The thyroid cartilage articulates by its inferior cornu with the 
posterior lateral portion of the cricoid. This permits of the thyroid cartilage 
rotating upon a horizontal axis directed through both of the articular surfaces, 
so that the upper margin of the thyroid passes forward and downward, while 
the joint is so constructed as to permit also of a slight upward, downward, for- 
ward, and backward movement of the thyroid upon the cricoid cartilage. The 
triangular arytenoid cartilages articulate at some distance from the middle 
Fig. 432.—Larynx from behind with its muscles. E., Epiglottis, with the cushion (W.); 
C. W., Cart. Wrisbergii; C. S., Cart. Santorini; C. <r., Cart. cricoidea. Cornu sup.—Cornu 
inf., Cart, thyreoideae; M. ar.tr., Muse, arytaenoideus transversus; Mm.ar.ob/., Musculi 
arytaenoidei obliqui; M. cr. aryt. post., Musculus crico-arytaenoideus posticus; Pars 
cart., Pars cartilaginea; Pars memb., Pars membranacea tracheae. Fig. 433.—Nerves of 
the larynx. O. h., Os hyoideum; C.th., Cart, thyreoidea; C. c., Cart, cricoidea; Tr., 
Trachea; M. th.-ar., M. thyreo-arytaenoideus; M. cr.-ar. p., M. crico-arytaenoideus 
posticus; M. cr.-ar. /., M. crico-arytaen. lateralis; M. cr.-th., M. crico-thyreoideus; 
N. lar. sup. v., N. laryngeus sup.; R. /., Ramus internus; R. E., Ramus ext.; N. lar. rec. v., 
N. laryngeus recurrens; R. I. N. L. R., Ramus int., R. E. N. L. R., Ramus ext. nervi laryngei 
recurrentis vagi. 
Fig. 432. 
Fig- 433- 
line, with oval, saddle-like, articular surfaces placed upon the upper margin of 
the plate of the cricoid cartilage. The articular surfaces permit two kinds of 
movements on the part of the arytenoid cartilages; first, rotation on their 
base around their vertical long axis, whereby either the anterior angle or pro- 
cessus vocalis, which is directed forwards, is rotated outwards; while the pro- 
cessus muscularis, which is directed outwards and projects over the margin of 
the cricoid cartilage, is rotated backwards and inwards, or conversely. Further, 
the arytenoids may be slightly displaced upon their bases either outwards or 
inwards. 652 
ACTION OF THE LARYNGEAL MUSCLES. 
[Sec. 313. 
The true vocal cords, or thyro-arytenoid ligaments, are in man about 15 
millimetres, and in woman n millimetres in length, and consist of numerous 
elastic fibres. They arise close to each other from near the middle of the inner 
angle of the thyroid cartilage, and are inserted, each into the anterior angle or 
processus vocalis of the arytenoid cartilages. The ventricles of Morgagni 
permit free vibration of the true vocal cords, and separate them from the upper 
or false cords, which consist of folds of mucous membrane. The false vocal 
cords are not concerned in phonation, but the secretion of their numerous 
mucous glands moistens the true vocal cords. 
The obliquely directed under surface of the vocal cords causes the cords to come together very 
easily when the glottis is narrow during respiration (e.g., in sobbing), while the closure may be 
made more secure by respiration. The opposite is the condition of the false vocal cords, which, 
when they touch, are easily separated during inspiration ; while during expiration, owing to the 
dilatation of the ventricles of Morgagni, they easily come together and close (Wyllie, L. Brun- 
ton and Cash). 
Fig. 434.—Schematic horizontal section of the larynx. I, Position of the horizontally divided 
arytenoid cartilages during respiration; from their anterior processes run the converging 
vocal cords. The arrows show the line of traction of the posterior crico-arytenoid muscles; 
II, II, the position of the arytenoid muscles, as a result of this action. Fig. 435.— 
Schematic horizontal section of the larynx, to illustrate the action of the arytenoid muscle. 
I, I, position of the arytenoid cartilages during quiet respiration. The arrows indicate the 
direction of the contraction of the muscle; II, II, the position of the arytenoid cartilages 
after the arytenoideus contracts. 
Fig. 434- 
Fig. 435- 
II. Action of the Laryngeal Muscles.—[The representation of the 
movements of the larynx in the cortex cerebri is referred to under Cerebrum.] 
These muscles have a double function : i. One connected with respiration, 
in as far as the glottis is widened and narrowed alternately during respiration ; 
further, when the glottis is firmly closed by these muscles, the entrance of 
foreign substances into the larynx is prevented. The glottis is closed immedi- 
ately before the act of coughing (§ 120). 2. The laryngeal muscles give the 
vocal cords the proper tension and other conditions for phonation. 
1. The glottis is dilated by the action of the posterior crico arytenoid 
muscles. When they contract they pull both processus musculares of the 
arytenoid cartilages backwards, downwards, and towards the middle line (fig. 
434), so that the processus vocales (I, I) must go apart and upwards (II, II). 
Thus, between the vocal cords (glottis vocalis), as well as between the inner 
margins of the arytenoid cartilages, a large triangular space is formed (glottis Sec. 313.] 
ACTION OF THE LARYNGEAL MUSCLES. 
653 
respiratoria), and these spaces are so arranged that their bases come together, 
so that the aperture between the cords and the arytenoid cartilages has a rhom- 
boidal form. Fig. 434 shows the action of the muscles. The vocal cords, 
represented by lines converging in front, arise from the anterior angle of the 
arytenoid cartilages (I, I). When these cartilages are rotated into the position 
(II, II), the cords take the position indicated by the dotted lines. The widen- 
ing of the respiratory portion of the glottis between the arytenoid cartilages' 
is also indicated in the diagram. 
Pathological.—When these muscles are paralyzed, the widening of the glottis does not take 
place, and there may be severe dyspnoea during inspiration, although the voice is unaffected 
(Reigel, L. Weber). In a larynx just excised, the dilators are the first to lose their excitability 
(Semon and Horsley). In organic disease affecting the recurrent laryngeal nerve the branch to 
the posterior crico-arytenoid is first paralyzed [Semon). When the recurrent nerve is exposed 
and cooled, the branch to the posterior crico-arytenoid is the first to lose its excitability (.Frankel 
and Gad). 
2. The entrance to the glottis is constricted by the arytenoid muscle 
(transverse), which extends transversely between both outer surfaces of the 
arytenoids along their whole length 
(fig. 435). On the posterior sur- 
face of this muscle is placed the 
cross bundles (fig. 432) of the 
thyro-aryepiglotticus (or arytse- 
noidei obliqui); they act like 
the foregoing. The action of 
these muscles is indicated in fig. 
435 ; the arrows point to the line 
of traction. 
Pathological.—Paralysis of this mus- 
cle enfeebles the voice and makes it 
hoarse, as much air escapes between the 
arytenoid cartilages during phonation. 
3. In order that the vocal 
cords be approximated to each 
other, which occurs during pho- 
nation, the processus vocales of 
the arytenoid cartilages must be 
closely apposed, whereby they 
must be rotated inwards .and 
downwards. This result is brought 
about by the processus musculares being moved in a forward and upward direc- 
tion by the thyro-arytenoid muscles. These muscles are applied to, and 
in fact are embedded in, the substance of the elastic vocal cords, and their 
fibres reach to the external surface of the arytenoid cartilages. When they 
contract, they rotate these cartilages so that the processus vocales must rotate 
inwards. The glottis vocalis is thereby narrowed to a mere slit (fig. 436), 
whilst the glottis respiratoria remains as a broad triangular opening. The 
action of these muscles is indicated in fig. 436. 
The lateral crico-arytenoid muscle is inserted into the anterior margin 
of the articular surface of the arytenoid cartilage ; hence, it can only pull the 
cartilage forwards; but some have supposed that it can also rotate the arytenoid 
cartilage in a manner similar to the thyro-arytenoid (?), with this difference, 
that the processus vocales do not come so close to each other. 
Pathological.—Paralysis of both thyro-arytenoid muscles causes loss of voice. 
4. The vocal cords are rendered tense by their points of attachment 
Scheme of the closure of the glottis by the thyro- 
arytenoid muscles. II, II, position of the ary- 
tenoid cartilages during quiet respiration. The 
arrows indicate the direction of the muscular trac- 
tion.—I, I, position of the arytenoid cartilages after 
the muscles contract. 
Fig. 436. 654 
POSITION DURING PHONATION. 
[Sec. 313. 
being removed from each other by the action of muscles. The chief agents in 
this action are the crico-thyroid muscles, which pull the thyroid cartilage 
forwards and downwards. At the same time, however, the posterior crico- 
arytenoids must pull the arytenoid cartilages slightly backwards, and also keep 
them fixed. 
The genio hyoid and thyro hyoid, when they contract, pull the thyroid upwards and forwards 
towards the chin, and also tend to increase the tension of the vocal cords (C. Mayer, Griitzner). 
According to Kiesselbach the crico-thyroid elevates the ring of the cricoid cartilage. The plate 
of the cricoid is thereby directed backwards and downwards, and thus causes tension of the 
vocal cords. 
Pathological.—Paralysis of the crico-thyroid causes the voice to become harsh and deep, 
owing to the vocal cords not being sufficiently tense. 
Position during Phonation.—The tension of the vocal cords brought 
about in this way is not of itself sufficient for phonation. The triangular 
aperture of the glottis respiratoria between the arytenoid cartilages, produced 
by the unaided action of the internal thyro-arytenoid muscles (see 3) must be 
closed by the action of the transverse and oblique arytenoid muscles. The 
vocal cords themselves must have a concave margin, which is obtained through 
the action of the crico-thyroids and posterior crico-arytenoids, so that the 
glottis vocalis presents the appearance of a myrtle leaf (.Henle), while the rima 
glottidis has the form of a linear slit (fig. 440). The contraction of the 
internal thyro-arytenoid converts the concave margin of the vocal cords into a 
straight margin. This muscle adjusts the delicate variations of tension of the 
vocal cords themselves, causing more especially such variations as are necessary 
for the production of tones of slightly different pitch. As these muscles come 
close to the margin of the cords, and are securely woven, as it were, amongst 
the elastic fibres of which the cords consist, they are specially adapted for the 
above-mentioned purpose. When the muscles contract, they give the necessary 
resistance to the cords, thus favoring their vibration. As some of the muscular 
fibres end in the elastic fibres of the cords, these fibres, when they contract, can 
render certain parts of the cords more tense than others, and thus favor the 
modifications in the formation of the tones. The coarser variations in the 
tension of the vocal cords are produced by the separation of the thyroid from 
the arytenoid cartilages, while the finer variations of tension are produced by 
the thyro-arytenoid muscles. The value of the elastic-tissue of the cords does 
not depend so much upon its extensibility as upon its property of shortening 
without forming folds and creases. 
Pathological.—In paralysis of these muscles, the voice can only be produced by forcible 
expiration, as much air escapes through the glottis; the tones are at the same time deep and 
impure. Paralysis of the muscle of one side causes flapping of the vocal cord on that side 
(Gerhardt). 
5. The relaxation of the vocal cords occurs spontaneously when the 
stretching forces cease to act; the elasticity of the displaced thyroid and aryte- 
noid cartilages comes into play, and restores them to their original position. 
The vocal cords are also relaxed by the action of the thyro-arytenoid and 
lateral crico-arytenoid muscles. 
It is evident, from the above statements, that tension of the vocal cords 
and narrowing of the glottis are necessary for phonation. The tension 
is produced by the crico-thyroids and posterior crico-arytenoids ; the narrowing 
of the glottis respiratoria by the arytenoids, transverse and oblique, the glottis 
vocalis being narrowed by the thyro-arytenoids and (? lateral crico-arytenoids), 
the former muscles causing the cords themselves to become tense. 
Nerves (§ 352, 5).—The crico-thyroid is supplied by the superior laryngeal 
branch of the vagus, which at the same time is the sensory nerve of the mucous Sec. 313.] 
STRUCTURE OF THE LARYNX. 
655 
membrane of the larynx. All the other intrinsic muscles of the larynx are 
supplied by the inferior laryngeal. 
[Section of the superior laryngeal nerve in the horse, although it is a purely sensory nerve in 
this animal, causes cessation of the movements of the glottis on that side, and subsequently 
unilateral atrophy of the laryngeal muscles (Moller, Exner).~\ 
The mucous membrane of the larynx is richly supplied with elastic fibres, and so is the 
sub mucosa. The sub-mucosa is more lax near the entrance to the glottis and in the ventricle 
of Morgagni, which explains the enormous swelling that sometimes occurs in these parts in 
Fig. 437- 
Vertical section through the head and neck, to the 1st dorsal vertebra; a, position of the 
laryngoscope on observing the posterior part of the glottis, arytenoid cartilages, and upper 
. surface of the posterior wall of the larynx; b, its position on observing the anterior angle 
of the glottis, a, Small, and b, large laryngoscopic mirrors. 
oedema glottidis. A thin clear limiting membrane lies under the epithelium. The epithelium 
is stratified, cylindrical, and ciliated with intervening goblet cells. On the true vocal cords and 
the anterior surface of the epiglottis, however, this is replaced by stratified squamous epithelium, 
which covers the small papillae of the mucous membrane. Numerous branched mucous glands 
occur over the cartilages of Wrisberg, the cushion of the epiglottis, and in the ventricles of 
Morgagni; in other situations, as on the posterior surface of the larynx, the glands are more 
scattered. The blood-vessels form a dense capillary plexus under the membrana propria of 
the mucous membrane; under this, however, there are other two strata of blood-vessels. The 
lymphatics form a superficial narrow mesh work under the blood-capillaries, with a deeper, 
coarser plexus. The medullated nerves have ganglia in their branches, but their mode of ter- 656 
LARYNGOSCOPY. 
[Sec. 313. 
mination is unknown. [W. Stirling has described a rich sub-epithelial plexus of medullated 
nerve-fibres on the anterior surface of the epiglottis, while he finds that there are ganglionic 
cells in the course of the superior laryngeal nerve.] Cartilages.—The thyroid, cricoid, and 
nearly the whole of the arytenoid cartilages consist of hyaline cartilage. The two former are 
prone to ossify. The apex and processus vocalis of the arytenoid cartilages consist of yellow 
Jibro-cartilage, and so do all the other cartilages of the larynx. The larynx grows until about 
the sixth year, when it rests for a time, but it becomes again much larger at puberty ($ 434). 
314. LARYNGOSCOPY.—The Laryngoscope consists of a small 
mirror fixed to a long handle, at an angle of 1250 to 130° (fig. 437, a, b'). 
When the mouth is opened, and the tongue drawn forward, the mirror is intro- 
duced, as is shown in fig. 438. The position of the mirror must be varied, 
according to the position of the larynx we wish to examine; in some cases the 
soft palate has to be raised by the back of the mirror, as in the position b. A 
picture of the part of the larynx examined is formed in the small mirror, the 
rays of light passing in the direction indicated by the dotted lines from the 
mirror; they are reflected at the same angle through the mouth into the eye of 
the observer, who must place himself in the direction of the reflected rays. 
Method of examining the larynx. 
Fig. 438. 
The illumination of the larynx is accomplished either by means of direct sunlight or by 
light from an artificial source, e. g., an ordinary lamp, an oxyhydrogen lime-light, or the electric 
light. The beam of light impinges upon a concave mirror of 15 to 20 centimetres focus, and 10 
centimetres in width, and from its surface the concentrated beam of light is reflected through the 
mouth of the patient, and directed upon the small mirror held in the back part of the throat. 
The beam of light is reflected at the same angle toward the larynx by the small throat mirror, 
so that the larynx is brightly illuminated. The observer has now to direct his eye in the same 
direction as the illuminating rays, which can be accomplished by having a hole in the centre of 
the concave mirror, through which the observer looks. Practically, however, this is unnecessary; 
all that is necessary is to fix the concave mirror to the forehead by means of a broad elastic 
band, so that the observer, by looking just under the margin of the concave mirror, can see the 
picture of the larynx in the small throat mirror (fig. 438). 
In order to examine the larynx, place the patient immediately in front of you, and cause him 
to open his mouth and protrude his tongue. A lamp is placed at the side of the head of the 
patient, and light from this source is reflected from the concave mirror on the observer’s fore- 
head, and concentrated upon the laryngoscopic mirror introduced into the back part of the throat 
of the patient (fig. 438). 
Oertel was able, by means of a rapid intermittent illumination of the larynx through a strobo- 
scopic disc, to study the movements of the vocal cords directly with the eye. Simanowsky put 
a photographic camera in the position of the eye, and photographed the movements of the vocal 
cords of an artificial larynx. [Brown and Behnke have photographed the human vocal cords.] Sec. 314.] 
657 
PICTURE OF THE LARYNX. 
Historical.—After Bozzini (1807) gave the first impulse towards the investigation of the 
internal cavities of the body, by illuminating them with the aid of mirrors, Babington (1829) 
actually observed the glottis in this way. The famous singer, Manuel Garcia (1854), made 
investigations both on himself and other singers, regarding the movements of the vocal cords, 
during respiration and phonation. The examination of the larynx by means of the laryngoscope 
was rendered practicable chiefly by Tiirck (1857) and Czermak, the latter observer being the first 
to use the light of a lamp for the illumination of the larynx. Rhinoscopy was actually first 
practiced by (1838), but Czermak was the first person who investigated this subject 
systematically. 
Laryngeal Electrodes.—V. Ziemssen introduces long narrow electrodes into the larynx, to 
stimulate the muscles and study their actions. Rossbach finds that the muscles and nerves of the 
interior of the larynx may be stimulated by stimulating the skin, i. e., percutaneously. These 
methods are used both for physiological and therapeutical purposes. 
Picture of the Larynx.—Fig. 439 shows the following structures: Z., 
the root of the tongue, with the ligamentum glosso-epiglotticum continued from 
its middle: on each side of the latter are 
V. V., the so-called vallecula. The epiglot- 
tis (E.) appears like an arched upper lip; 
under it, during normal respiration, is the 
lancet-shaped glottis (R.) and on each side 
of it the true vocal cords (Z. v.). The 
length of the vocal cord in a child is 6 to 8 
mm., in the female 10 to 15 mm. when they 
are relaxed, and 15 to 20 mm. when tense. 
In man, the lengths under the same condi- 
tions are 15 to 20 mm. and 20 to 25 mm. 
The breadth varies from 2 to 5 mm. On 
the external side of each vocal cord is the 
entrance to the sinus of Morgagni (S. Ml), 
represented as a dark line. Further upwards 
and more external are (Z. v. s.) the upper or 
false vocal cords. [The upper or false vocal 
cords are red, the lower or true, white.] On 
each side of P. are (S. S.) the apices of 
the cartilages of Santorini, placed upon the 
apices of the arytenoid cartilages, while im- 
mediately behind is the wall of the pharynx, 
P. In the aryteno-epiglottidean fold are (IV. W.) the cartilages of Wrisberg, 
while outside these are the depressions (S. p.) constituting the sinuspiriformes. 
During normal respiration the glottis has the form of a lancet-shaped 
slit between the bright yellowish-white vocal cords (fig. 440). If a deep 
The larynx, as seen with the laryngo- 
scope. L., tongue; E., epiglottis; V, 
vallecula; E., glottis; Z. v., true 
vocal cords; S. M., sinus Morgagni; 
Z. v. s., false vocal cords ; P., position 
of pharynx; S., cartilage of San- 
torini; IV., of Wrisberg; S. p., sinus 
piriformes. 
Fig- 439- 
Fig. 440. 
Fig. 441. 
Position of the vocal cords on uttering a 
high note. 
View of the rings and bifurcation of 
trachea. 
inspiration be taken, the glottis is considerably widened (fig. 441), and if the 
mirror be favorably adjusted we may see the rings of the trachea, and even the 
bifurcation of the trachea. [Sec. 314. 
RHINOSCOPY. 
If a high note be uttered, the glottis is contracted to a very narrow slit 
(fig. 440). 
Rhinoscopy.—If a small mirror, fixed to a handle at an angle of ioo° to 1 io°, be introduced 
into the pharynx, as shown in fig. 442, 
and if the mirror be directed upwards, 
certain structures are with difficulty 
rendered visible (fig. 443). In the 
middle is the septum narium (S. n.), 
and on each side of it the long oval 
large posterior nares (Ch.), below this 
the soft palate (R. w.), with the pendant 
uvula {Id.). In the posterior nares are 
the posterior extremities of the lower 
(C. i.), middle (C. ml), and upper lur. 
binated bones (C. .?.). At the upper 
part, a portion of the roof of the 
pharynx (O. R.) is seen, with the arched 
masses of adenoid tissue lying between 
the openings of the Eustachian tubes 
(T. T.), and called by Luschka the 
pharyngeal tonsils. External to the 
openings of the Eustachian tube is the 
tubular eminence (IV.), and outside 
this is the groove of Rosenmiiller (R.). 
Experiments on the Excised 
Larynx.—Ferrein ($ 741) and Joh. 
Muller made experiments upon the 
excised larynx. A tracheal tube was 
tied into tbe excised human larynx, 
and air was blown through it, the 
pressure being measured by means of a 
mercurial manometer, while various 
arrangements were adopted for putting 
the vocal cords on the stretch and for 
opening or closing the glottis. 
Position of the laryngoscopic mirror in rhinoscopy. 
Fig. 442. 
315- CONDITIONS INFLUENCING THE LARYNGEAL 
SOUNDS.—The pitch of the note emitted by the larynx depends upon :— 
1. The Tension of the Vocal 
Cords, i. e., upon the degree of con- 
traction of the crico-thyroid and posterior 
crico-arytenoid muscles, and also of the 
internal thyro-arytenoids (§ 313, II, 4). 
2. The Length of the Vocal Cords. 
(a) Children and females with short vocal 
cords produce high notes. (b) If the 
arytenoid cartilages are pressed together 
by the action of the arytenoid muscles 
(transverse and oblique), so that the vocal 
cords alone can vibrate, while their inter- 
cartilaginous portions lying between the 
processus vocales do not, the tone thereby 
produced is higher (Garcia). In the pro- 
duction of low notes, the vocal cords, as 
well as the margins of the arytenoid carti- 
lages, vibrate. At the same time the 
space above the entrance to the glottis is 
enlarged and the larynx becomes more 
prominent. (c) Every individual has a certain medium pitch of his voice, 
Composite rhinoscopic view. S.n., Septum 
narium; C.i., C.m., C.s., lower, middle, 
and upper turbinated bones; 71, Eusta- 
chian tube; W., tubular eminence; P., 
groove of Rosenmiiller; P.m., soft palate; 
O.R., roof of pharynx ; U., uvula. 
Fig- 443- Sec. 315.] 
PRODUCTION AND RANGE OF VOICE. 
659 
which corresponds to the smallest possible tension of the intrinsic muscles of 
the larynx. 
3. The Strength of the Blast.—That the strength of the blast from below 
raises the pitch of the tones of the human larynx is shown by the fact, that 
tones of the highest pitch can only be uttered by powerful expiratory efforts. 
With tones of medium pitch, the pressure of the air in the trachea is 160 mm., 
with high pitch 200 mm., and with very high notes 945 mm., and in whispering 
20 mm., of water (Cagniard-Latour). These results were obtained in a ca-e 
of tracheal fistula. 
Accessory Phenomena.—The following as yet but partially explained phenomena are ob- 
served in connection with the production of high notes: (a) As the pitch of the note rises, the 
larynx is elevated, partly because the muscles raising it are active, partly because the increased 
intra-tracheal pressure so lengthens the trachea, that the larynx is thereby raised; the uvula is 
raised more and more (Labus). (b) The upper vocal cords approximate to each other more and 
more, without, however, coming into contact, or participating in the vibrations, (r) The epi- 
glottis inclines more and more backwards over the glottis. 
4. The falsetto voice, with its soft timbre and the absence of resonance 
or pectoral fremitus in the air-tubes, is particularly interesting. Oertel observed 
that, during the falsetto voice, the vocal cords vibrated so as to form nodes 
across them, but sometimes there was only one node, so that the free margin of 
the cord and the basal margin vibrated, being separated from each other by a 
nodal line (parallel to the margins of the vocal cord). During a high falsetto 
note there may be three such nodal lines parallel to each other. The nodal 
lines are produced probably by a partial contraction of the fibres of the thyro- 
arytenoid muscle (p. 653), while at the same time the vocal cords must be re- 
duced to as thin plates as possible by the action of the crico-thyroid, posterior 
arytenoid, thyro- and genio-hyoid muscles (Oertel). The form of the glottis is 
elliptical, while with the chest-voice the vocal cords are limited by straight 
surfaces; the air also passes more freely through the larynx. 
Oertel also found that during the falsetto voice the epiglottis is erect. The apices of the ary- 
tenoid cartilages are slightly inclined backwards, the whole larynx is larger from before back- 
wards, and narrower from side to side, the aryepiglottidean folds are tense with sharp margins, 
and the entrance to the ventricles of Morgagni is narrowed. The vocal cords are narrower, the 
processus vocales touch each other. The rotation of the arytenoid cartilages necessary for this 
is brought about by the action of the crico-arytenoid alone, while the thyro-arytenoid is to be re- 
garded only as an accessory aid. The pitch of the note is increased solely by increased tension 
of the vocal cords. In addition, there are a number of transverse and longitudinal partial vibra- 
tions. During the chest-voice, a smaller part of the margin vibrates than in the falsetto voice, 
so that in the production of the latter we are conscious of less muscular exertion in the larynx. 
The uvula is raised to the horizontal position. 
Production of Voice.—In order that voice be produced, the following 
conditions are necessary: (1) The necessary amount of air is collected in the 
chest; (2) the larynx and its parts are fixed in the proper position ; (3) air is 
then forced by an expiratory effort either through the linear chink of the closed 
glottis, so that the latter is forced open, or at first some air is allowed to pass 
through the glottis without producing a sound, but as the blast of air is 
strengthened the vocal cords are thrown into vibration. 
316. RANGE OF THE VOICE.—The range of the human voice for 
chest notes is given in the following scheme:— 
The accompanying figures indicate the number of vibrations per second in the corresponding 
tone. It is evident that from c' to f' is common to all voices, nevertheless, they have a different 
timbre. The lowest note or tone, which, however, is only occasionally sung by bass singers, is 
the contra-F, with 42 vibrations—the highest note of the soprano voice is «///, with 1708 vibra- 
tions. 660 
[Sec. 316. 
SPEECH—THE VOWELS. 
Alto. 
Soprano. 
Bass. 
Timbre.—The voice of every individual has a peculiar quality, clang, or 
timbre, which depends upon the shape of all the cavities connected with the 
larynx. In the production of nasal tones, the air in the nose is caused to vibrate 
strongly, so that the entrance to the nares must necessarily be open. 
317. SPEECH—THE VOWELS.—The motor processes connected 
with the production of speech occur in the resonating cavities, the pharynx, 
mouth, and nose, and are directed towards the production of musical tones and 
noises. 
Whispering and Audible Speech.—When sounds or noises are produced 
in the resonating chambers, the larynx being passive, the vox clandestina, or 
whispering is produced ; when the vocal cords, however, vibrate at the same 
time, “ audible speech ” is produced. [Whispering, therefore, is speech with- 
out voice.] Whispering may be fairly loud, but it requires great exertion, i. e., a 
great expiratory blast, for its production ; hence it is very fatiguing. It may 
be performed both with inspiration and expiration, while audible speech is but 
temporary and indistinct, if it is produced during inspiration. Whispering is 
caused by the sound produced by the air passing over the obtuse margins of the 
cords. During the production of audible sounds, however, the sharp margins 
of the vocal cords are directed towards the air by the position of the processus 
vocales. 
During speech the soft palate is in action ; at each word it is raised, while at the same time 
Passavant’s transverse band is formed in the pharynx ($ 156). The soft palate is raised highest 
when u and i are sounded, then with o and e, and least with a. When sounding m and n it 
does not move; it is high (like n) during the utterance of the explosives. With 1, s, and 
especially with the guttural r, it exhibits a trembling movement (Gentzen, Falksori). 
Speech is composed of vowels and consonants. 
A. Vowels (analysis and artificial formation, § 413).—A. During whis- 
pering, a vowel is the musical tone produced, either during expiration or inspi- 
ration, by the inflated characteristic form of the mouth, which not only has a 
definite pitch, but also a particular and characteristic timbre. The characteristic 
form of the mouth may be called “ vowel cavity. ” 
I. The pitch of the vowels may be estimated musically. It is remarkable that the funda- 
mental tone of the “ vowel-cavity ” is nearly constant at different ages and in the sexes. The 
different capacities of the mouth can be compensated for by different sizes of the oral aperture. 
The pitch of the vowel-cavity may be estimated by placing a number of vibrating tuning-forks of 
different pitch in front of the mouth, and testing them until we find the one which corresponds 
with the fundamental tone of the vowel-cavity. This is known by the fact that the tone of the 
tuning-fork is intensified by the resonance of the air in the mouth, or the vibrations may be trans- 
ferred to a vibrating membrane and recorded on a smoked surface, as in the phonautograph of 
Donders. 
Tenor. Sec. 317.] 
THE VOWEL SOUNDS. 
661 
According to Konig, the fundamental tones of the vowel-cavity are for • 
U == b, O = b', A = b", E = b"\ I = b"". 
If the vowels be whispered in this series, we find at once that their pitch 
rises. The fundamental tone in the production of a vowel may vary within 
certain limits. This may be shown by giving the mouth the characteristic 
position and then percussing the cheeks (Auerbach); the sound emitted is 
that of the vowel, whose pitch will vary accordingly to the position of the 
mouth. 
When sounding A, the mouth has the form of a funnel widening in front (fig. 444, A). The 
tongue lies in the floor of the mouth, and the lips are wide open. The soft palate is moderately 
raised (Czermak). It is more elevated successively with O, E, U, I. The hyoid bone appears 
as if at rest, but the larynx is slightly raised. It is higher than with U, but lower than with I. 
If we sound A to I, the larynx and the hyoid bone retain their relative position, but both are 
raised. In passing from A to U, the larynx is depressed as far as possible. The hyoid bone 
passes slightly forward {Briicke'). When sounding A, the space between the larynx, posterior 
wall of the pharynx, soft palate, and the root of the tongue, is only moderately wide; it 
becomes wider with E, and especially with I (Purkinje), but it is smallest with U. 
When sounding U (fig. 444), the form of the cavity of the mouth is like that of a capacious 
flask with a short, narrow neck. The whole resonance apparatus is then longest. The lips are 
protruded as far as possible, are arranged in folds and closed, leaving only a small opening. 
Fig. 444. 
Section of the parts concerned in phonation. Z, tongue; p, soft palate; e, epiglottis; g, glottis; 
k, hyoid bone; x, thyroid, 2, 3, cricoid, 4, arytenoid cartilage. 
The larynx is depressed as far as possible, while the root of the tongue is approximated to the 
posterior margin of the palatine arch. 
When sounding O, the mouth, as in U, is like a wide-bellied flask with a short neck, but the 
latter is shorter and wider as the lips are nearer to the teeth. The larynx is slightly higher than 
with U, while the resonance chambers also are shorter (fig. 444). 
When sounding I, the cavity of the mouth, at the posterior part, is in the form of a small- 
bellied flask with a long narrow neck, of which the belly has the fundamental tone, f, the neck 
that of d///. The resonating chambers are shortest, as the larynx is raised as much as possible, 
while the mouth, owing to the retraction of the lips, is bounded in front by the teeth. The 
cavity between the hard palate and the back of the tongue is exceedingly narrow, there being 
only a median narrow slit. Hence, the air can only enter with a clear piping noise, which sets 
even the vertex of the skull in vibration, and when the ears are stopped the sounds seem very 
shrill. When the larynx is depressed and the lips protruded, as for sounding U, I cannot be 
sounded. 
When sounding E, which stands next to I, the cavity has also the form of a flask with a 
small belly (fundamental tone F), and with a long, narrow neck (fundamental tone, b///). The 
neck is wider, so that it does not give rise to a piping noise. The larynx is slightly lower than 
for I, but not so high as for A. 
Fundamentally, there are only three primary vowels—I, A, U, the others and the so-called 
diphthongs standing between them (Briicke). 
Diphthongs occur when, during vocalization, we pass from the position of 662 
VOWELS AND CONSONANTS. 
[Sec. 317. 
one vowel into that of another. Distinct diphthongs are sounded only on 
passing from one vowel with the mouth wide open to one with the mouth 
narrow; during the converse process, the vowels appear to our ear to be 
separate (Briicke). 
II. Timbre or Clang-Tint.—Besides its pitch, every vowel has a special 
timbre, quality, or clang-tint. 
The vocal timbre of U (whispering) has, in addition to its fundamental tone, b, a deep piping 
timbre. The timbre depends upon the number and pitch of the partials or overtones of the 
vowel sound (§ 415). 
Nasal Timbre.—The timbre is modified in a special manner when the vowels are spoken 
with a “nasal ” twang, which is largely the case in the French language. The nasal timbre is 
produced by the soft palate not cutting off the nasal cavity completely, which happens every 
time a pure vowel is sounded, so that the air in the nasal cavity is thrown into sympathetic 
vibration. When a vowel is spoken with a nasal timbre, air passes out of the nose and mouth 
simultaneously, while, with a pure vowel sound, it passes out only through the mouth. 
When sounding a pure vowel (non-nasal), the shutting off of the nasal cavity from the mouth 
is so complete, that it requires an artificial pressure of 30 to 100 mm. of mercury to overcome it 
(Hartmann). 
The vowels, a, a (se), 6 (oe), o, e, are used with a nasal timbre—a nasal i does not occur in 
any language. Certainly it is very difficult to sound it thus, because when sounding i the mouth 
is so narrow that when the passage to the nose is open, the air passes almost completely through 
the latter, whilst the small amount passing through the mouth scarcely suffices to produce a 
sound. 
In sounding vowels, we must observe if they are sounded through a previously closed glottis, 
as is done in the German language in all words beginning with a vowel (spiritus lenis). The 
glottis, however, may be previously opened with a preliminary breath, followed by the vowel 
sound ; we obtain the aspirate vowel (spiritus asper of the Greeks). 
B. If the vowels are sounded in an audible tone, i. e., along with the sound 
from the larynx, the fundamental tone of the vocal cavity strengthens in a 
characteristic manner the corresponding partial tones present in the laryngeal 
sound ( Wheatstone, v. Helmholtz'). 
318. CONSONANTS .—The consonants are noises which are produced 
at certain parts of the resonance chamber. [As their name denotes, they can 
only be sounded in conjunction with a vowel.] 
Classification.—The most obvious classification is according to—(I) Their acoustic proper- 
ties, so that they are divided into—(1) liquid consonants, i.e., such as are appreciable without a 
vowel (m, n, 1, r, s); (2) mutes, including all the others, which cannot be distinctly heard 
without an accompanying vowel. (II) According to their mechanism of formation, as well as 
the type of the organ of speech, by which they are produced. They are divided into— 
1. Explosives.—Their enunciation is accompanied by a kind of bursting open of an obstacle, 
or an explosion, occasioned by the confined and compressed air which causes a stronger or weaker 
noise; or, conversely, the current of air is suddenly intermipted, while, at the same time, the 
nasal cavities are cut off by the soft palate. 
2. Aspirates, in which one part of the canal is constricted or stopped, so that the air rushes 
out through the constriction, causing a faint whistling noise. (The nasal cavity is cut off.) In 
uttering L, which is closely related to the aspirates, but differs from them in that the narrow 
passage for the rush of air is not in the middle, but at both sides of the middle of the closed part. 
(The nasal cavity is shut off.) 
3. Vibratives, which are produced by air being forced through a narrow portion of the 
canal, so that the margins of the narrow tube are set in vibration. (The nasal cavity is 
shut off.) 
4. Resonants (also called nasals or semi-vowels). The nasal cavity is completely free, while 
the vocal canal is completely closed in the front part of the oral channel. According to the 
position of the obstruction in the oral cavity, the air in a larger or smaller portion of the mouth 
is thrown into sympathetic vibration. 
We may also classify them according to the position in which they are produced 
—the “ articulation positions” of Briicke. These are :— 
A. Between both lips; B, between the tongue and the hard palate ; C, be- 
tween the tongue and the soft palate; D, between the true vocal cords. Sec. 318.] 
CONSONANTS. 
663 
A. Consonants of the First Articulation Position. 
1. Explosive Labials.—b, the voice is sounded before the slight explosion occurs; p, the 
voice is sounded after the much stronger explosion has taken place (.Kempelen). [The former 
is spoken of as ‘‘voiced” and the latter as “ breathed.”] 
2. Aspirate Labials.—f, between the upper incisor teeth and the lower lip (labio-dental). It 
is absent in all true Slavic words (Purkine); v, between both lips (labial); w is formed when 
the mouth is in the position for f, but instead of merely forcing in the air, the voice is sounded 
at the same time. Really there are two different w’s—one corresponding to the labial f, as in 
wiirde, and the labio-dental, e.g., quelle (Briicke). 
3. Vibrative Labials.—The burring sound, emitted by grooms, but not used in civilized 
language. 
4. Resonant Labials.—m is formed essentially by sounding the voice whereby the air in the 
mouth and nose is thrown into sympathetic vibration [“voiced”]. 
B. Consonants of the Second Articulation Position. 
1. The explosives, when enunciated sharply and without the voice, are T hard (also dt and 
th); when they are feeble and produced along with simultaneous laryngeal sounds (voice), we 
have D soft. 
2. The aspirates embrace S, including s sharp, written s s or s z, which is produced with- 
out any audible laryngeal vibration; or soft, which requires the voice. Then, also, there are 
modifications according to the position where the noises are produced. The sharp aspirates 
include Sch, and the hard English Th; to the soft belong the French J soft, and the English 
Th soft. L, which occurs in many modifications, appears here,.e.g., the L soft of the French. 
L may be sounded soft with the voice, or sharp without it. 
3. The vibrative, or R, which is generally voiced, but it can be formed without the larynx. 
The resonants are N-sounds, which also occur in several modifications. 
C. Consonants of the Third Articulation Position. 
1. The explosives are the K-sounds, which are hard and breathed and not voiced; G-sounds, 
which are voiced. 
2. The aspirates, when hard and breathed but not voiced, the Ch, and when sounded softly 
and not voiced, J is formed. 
3. The vibrative is the palatal R, which is produced by vibration of the uvula (Briicke). 
4. The resonant is the palatal N. 
D. Consonants of the Fourth Articulation Position. 
1. An explosive sound does not occur when the glottis is forced open, if a vowel is loudly 
sounded with the glottis previously closed. If this occurs during whispering, a feeble short 
noise, due to the sudden opening of the glottis, may be heard. 
2. The aspirates of the glottis are the H-sounds, which are produced when the glottis is 
moderately wide. 
3. A glottis-vibrative occurs in the so-called laryngeal R of lower Saxon {Briicke). 
4. A laryngeal resonant cannot exist. 
The combination of different consonants is accomplished by the successive movements neces- 
sary for each being rapidly executed. Compound consonants, however, are such as are formed 
when the oral parts are adjusted simultaneously for two different consonants, so that a mixed 
sound is formed from two. Examples: Sch—tsch, tz, ts—Ps (1p)—Ks (X2). 
319. PATHOLOGICAL VARIATIONS OF VOICE AND SPEECH.—Aphonia. 
—Paralysis of the motor nerves (vagus) of the larynx by injury, or the pressure of tumors, causes 
aphonia or loss of voice [Galen). In aneurism of the aortic arch, the left recurrent nerve 
may be paralyzed from pressure. The laryngeal nerves may be temporarily paralyzed by rheu- 
matism, over-exertion and hysteria, or by serous effusions into the laryngeal muscles. If the 
tensors are paralyzed, monotonia is the chief result; the disturbances of respiration in paralysis 
of the larynx are important. As long as the respiration is tranquil, there may be no disturbance, 
but as soon as increased respiration occurs, great dyspnoea sets in, owing to the inability of the 
glottis to dilate. 
If only one vocal cord is paralyzed, the voice becomes impure and falsetto-like, while we 
may feel from without that there is less vibration on the paralyzed side (Gerhardt). Sometimes 
the vocal cords are only so far paralyzed that they do not move during phonation, but do so 
during forced respiration and during coughing (phonetic paralysis). 
Diphthongia.—Incomplete unilateral paralysis of the recurrent nerve is sometimes followed 
by a double tone, owing to the unequal tension of the two vocal cords. According to Tiirck 
and Schnitzler, however, the double tone occurs when the two vocal cords touch at some part of 664 
VOICE AND SPEECH. 
[Sec. 319. 
their course (e.g., from the presence of a tumor, fig. 445), so that the glottis is divided into two 
unequal portions, each of which produces its own sound. 
Hoarseness is caused by mucus upon the vocal cords, by roughness, swelling, or laxness of 
the cords. If, while speaking, the cords are approximated, and suddenly touch each other, the 
“ speech is broken,” owing to the formation of nodal points 
($ 352)- Disease of the pharynx, naso-pharyngeal cavity, 
and uvula may produce a change in the voice reflexly. 
Paralysis of the soft palate (as well as congenital per- 
foration or cleft palate) causes a nasal timbre of all vowels; 
the former renders difficult the normal formation of conso- 
nants of the third articulation position; resonance is imper- 
fect, while the explosives are weak, owing to the escape of 
the air through the nose. 
Paralysis of the tongue weakens I; E and A (Hi) are 
less easily pronounced, while the formation of consonants of 
the second and third articulation position is affected. The 
term aphthongia is applied to a condition in which every 
attempt to speak is followed by spasmodic movements of the 
tongue (Fleury). 
In paralysis of the lips (facial nerve), and in hare-lip, regard must be had to the formation 
of consonants of the first articulation position. When the nose is closed, the speech has a char- 
acteristic sound. The normal formation of resonants is of course at an end. After excision of 
the larynx, a metal reed, enclosed in a tube, and acting like an artificial larynx, is introduced 
between the trachea and the cavity of the mouth (Czerny). 
Stammering is a disturbance of the formation of sounds. [Stammering is due to long-con- 
tinued spasmodic contraction of the diaphragm, just as hiccough is (§ 120), and, therefore, it is 
essentially a spasmodic inspiration. As speech depends upon the expiratory blast, the spasm 
prevents expiration. It may be brought about by mental excitement or emotional conditions. 
Hence, the treatment of stammering is to regulate the respirations. In stuttering, which is 
defective speech due to inability to form the proper sounds, the breathing is normal.] 
320. COMPARATIVE—HISTORICAL.—Speech may be classified with the “ expres- 
sion of the emotions” (Darwin). Psychical excitement causes in man characteristic move- 
ments, in which certain groups of muscles are always concerned, e.g., laughing, weeping, the 
facial expression in anger, pain, shame, etc. These movements afford a means whereby one 
creature can communicate with another. Primarily in their origin, the movements of expression 
are reflex motor phenomena; when they are produced for purposes of explanation, they are 
voluntary imitations of this reflex. Besides the emotional movements, impressions upon the 
sense-organs produce characteristic reflex movements, which may be used for purposes of ex- 
pression (Geiger), e.g., stroking or painful stimulation of the skin, movements after smelling 
pleasant or unpleasant or disagreeable odors, the action of sound and light, and the perception of 
all kinds of objects. 
The expression of the emotions occurs in its simplest form in what is known as expression by 
means of signs or pantomime or mimicry. Another means is the imitation of sounds by 
the organ of speech, constituting onomatopoesy, e.g., the hissing of a stream, the roll of thunder, 
the tumult of a storm, whistling, etc. The expression of speech is, of course, dependent upon the 
process of ideation and perception 
The occurrence of different sounds in different languages is very interesting. Some languages 
(e.g., of the Hurons) have no labials; in some South Sea Islands no laryngeal sounds are 
spoken; f is absent in Sanscrit and Finnish; the short e, 0, and the soft sibilants in Sanscrit; 
d, in Chinese and Mexican; s, in many Polynesian languages; r, in Chinese, etc. 
Voice in Animals.—Animals, more especially the higher forms, can express their emotions 
by facial and other gestures. The vocal organs of mammals are essentially the same as those 
of man. Special resonance organs occur in the orang-outang, mandril, macacus, and mycetes 
monkeys, in the form of large cheek pouches, which can be inflated with air, and open between 
the larynx and the hyoid bone. 
Birds have an upper (larynx) and a lower larynx (syrinx); the latter is placed at the 
bifurcation of the trachea, and is the true vocal organ. Two folds of mucous membrane (three 
in singing birds) project into each bronchus, and are rendered tense by muscles, and are thus 
adapted to serve for the production of voice. 
Amongst reptiles, the tortoise produces merely a sniffing sound, which in the Emys has a 
peculiar piping character. The blind snakes are voiceless, the chameleon and the lizards have a 
very feeble voice; the cayman and crocodile emit a feeble roaring sound, which is lost in some 
adults owing to changes in the larynx. The snakes have no special vocal organs, but by forcing 
out air from their capacious lung, they make a peculiar hissing sound, which in some species is 
loud. Amongst amphibians, the frog has a larynx provided with muscles. The sound emitted 
Fig- 445- 
Tumors on the vocal cords causing 
double tone from the larynx. Sec. 320.] 
665 
ORGANS OF VOICE IN ANIMALS. 
without any muscular action is a deep intermittent tone, while more forcible expiration, with 
contraction of the laryngeal constrictors, causes a clearer continuous sound. The male, in Rana 
esculenta, has at each side of the angle of the mouth a sound-hag, which can be inflated with 
air and acts as a resonance chamber. The “ croaking” of the male frog is quite characteristic. 
In Pipa, the larynx is provided with two cartilaginous rods, which are thrown into vibration by 
the blast of air, and act like vibrating rods or the limbs of a tuning-fork. Some fishes emit 
sounds, either by rubbing together the upper and lower pharyngeal bones, or by the expulsion of 
air from the swimming bladder, mouth, or anus. 
Some insects cause sounds partly by forcing the expired air through their stigmata provided 
wtih muscular reeds, which are thus thrown into vibration (bees and many diptera). The wings, 
owing to the rapid contraction of their muscles, may also cause sounds (flies, cockroach, bees). 
The Sphinx atropos (death head moth) forces air from its sucking stomach. In others, sounds 
are produced by rubbing their legs on the wing cases (Acridium), or the wing-cases on each 
other (Gryllus, locust), or on the thorax (Cerambyx), on the leg (Geotrupes), on the abdomen or 
the margin of the wing (Necrophorus). In Cicadacke, membranes are pulled upon by muscles, 
and are thus caused to vibrate. Friction sounds are produced between the cephalo-thorax and 
the abdomen in some spiders (Theridium), and in some crabs (Palinurus). Some mollusca 
(Pecten) emit a sound on separating their shells. 
Historical.—The Hippocratic School was aware of the fact that division of the trachea 
abolished the voice, and that the epiglottis prevented the entrance of food into the larynx. 
Aristotle made numerous observations on the voice of animals. The true cause of the voice 
escaped him as well as Galen. Galen observed complete loss of voice after double pneumo- 
thorax, after section of the intercostal muscles or their nerves, as well as after destruction of 
part of the spinal cord, even although the diaphragm still contracted. He gave the cartilages 
of the larynx the names that still distinguish them; he knew some of the laryngeal muscles, 
and asserted that voice was produced only when the glottis was narrowed. He compared the 
larynx to a flute. The weakening of the voice, in feeble conditions, especially after loss of 
blood, was known to the ancients. Dodart (1700) was the first to explain voice as due to the 
vibration of the vocal cords by the air passing between them. 
The production of vocal sounds attracted much attention amongst the ancient Asiatics and 
Arabians—less amongst the Greeks. Pietro Ponce (f 1584) was the first to advocate instruc- 
tion in the art of speaking in cases of dumbness. Bacon (1638) studied the shape of the mouth 
for the pronunciation of the various sounds. Kratzenstein (1781) made an artificial apparatus 
for the production of vowel sounds, by placing resonators of various forms over vibrating reeds. 
Von Kempelen (1769 to 1791) constructed the first speaking-machine. Rob. Willis (1828) 
found that an elastic vibrating spring gives the vowels in the series—U, O, A, E, I—according 
to the depth or height of its tone; further, that by lengthening or shortening an artificial resonator 
on an artificial vocal apparatus, the vowels may be obtained in the same series. The newest 
and most important investigations on speech are by Wheatstone, v. Helmholtz, Bonders, Briicke, 
etc., and are mentioned in the context. Hensen succeeded in showing exactly the pitch of 
vocal tone, thus: The tone is sung against a Konig’s capsule with a gas flame. Opposite the 
flame is placed a tuning-fork vibrating horizontally, and in front of one of its limbs is a mirror, 
in which the image of the flame is reflected. When the vocal tone is of the same number of 
vibrations as the tuning-fork, the flame in the mirror shows one elevation, if double, i. e., the 
octave, 2, and with the double octave, 4 elevations. General Physiology of the Nerves and 
Electro-Physiology. 
321. STRUCTURE OF THE NERVE ELEMENTS.—The 
nervous elements present two distinct forms:— 
I. Nerve-Fibres. 
Non-medullated. 
Medullated. 
II. Nerve-Cells. 
Of various forms 
and functions. 
An aggregation of nerve-cells constitutes a nerve-ganglion. The fibres 
represent a conducting apparatus, and serve to place the central nervous 
organs in connection with peripheral end-organs. The nerve-cells, however, 
besides transmitting impulses, act as physiological centres for automatic or 
reflex movements, and also for the sensory, perceptive, trophic, and secretory 
functions. 
i. (i) The non-medullated nerve-fibres occur chiefly in the sympathetic 
nervous system, although they are not confined to it; hence they are sometimes 
called sympathetic nerve-fibres. They occur in several forms :— 
1. Primitive Fibrils.—The simplest form of nerve-fibre, which is visible 
with a magnifying power of 500 to 800 diameters linear, consists of primitive 
nerve-fibrils. They are very delicate fibres (fig. 446, 1), often with small 
varicose swellings here and there in their course, which, however, are due to 
changes post-mortem. They are stained of a brown or purplish color by the 
gold-chloride method, and they occur when a nerve-fibre is near its termination, 
being formed by the splitting up of the axis-cylinder of the nerve-fibre, e. g., 
in the terminations of the corneal nerves, the optic nerve-layer in the retina, 
the terminations of the olfactory fibres, and in a plexiform arrangement in 
non-striped muscle (p. 586). Similar fine fibrils occur in the gray matter of 
the brain and spinal cord, and in the finely divided processes of nerve-cells. 
2. Naked or simple axial cylinders (fig. 446, 2), which represent bun- 
dles of primitive fibrils held together by a slightly granular cement, so that 
they exhibit very delicate longitudinal striation with fine granules scattered in 
their course. The best example is the axial cylinder process of nerve-cells (fig. 
446, I, z). [The thickness of the axis-cylinder depends upon the number of 
fibrils entering into its composition.] 
3. Axis-cylinders surrounded with Schwann’s sheath, or Remak’s 
fibres (3.8 to 6.8 //. broad), the latter name being given to them from their 
discoverer (fig. 446, 3). [These fibres are also called pale or non-medul- 
lated, and from their abundance in the sympathetic nervous system, sympa- 
thetic.] They consist of a sheath, corresponding to Schwann’s sheath [neuri- 
lemma, or primitive sheath, which encloses an axial cylinder; while lying here 
and there under the sheath, and between it and the axial cylinder are nerve- 
corpuscles. These fibres are always fibrillated longitudinally.] The sheath 
is delicate, structureless, and elastic. Dilute acids clear the fibres without 
causing them to swell up, while gold chloride makes them brownish-red. They Sec. 321.] 
STRUCTURE OF NERVE-FIBRES. 
667 
are widely distributed in the sympathetic nerves [e. g., splenic], and in the 
branches of the olfactory nerves. All nerves in the embryo, as well as the 
nerves of many invertebrata, are of this kind. [According to Ranvier, these 
Fig. 446. 
i, Primitive fibrillse; 2, axis-cylinder; 3, Remak’s fibres; 4, medullated varicose fibre; 5,6, 
medullated fibre, with Schwann’s sheath; r, neurilemma; t, t, Ranvier’s nodes; b, white 
substance of Schwann; d, cells of the endoneurium; a, axis-cylinder; x, myelin drops; 
7, transverse section of nerve-fibres; 8, nerve-fibre acted on with silver nitrate and showing 
Frommann’s lines. I, multipolar nerve-cell from the spinal cord ; z, axial cylinder process; 
y, protoplasmic processes—to the right of it a bipolar cell. II, peripheral ganglionic cell, 
with a connective-tissue capsule. Ill, ganglionic cell, with 0, a spiral, and n, straight pro- 
cess; tn, sheath. 
fibres do not possess a sheath, but the nuclei are merely applied to the surface, 
or slightly embedded in the superficial parts of the fibre, so that they belong to 668 
STRUCTURE OF NERVE-FIBRES. 
[Sec. 321. 
the fibre itself. These fibres also branch and form an anastomosing network in 
the course of a nerve (fig. 447). This the medullated 
fibres never do. These fibres, when acted on by silver 
nitrate, never show any crosses. The branched forms 
occur in the ordinary nerves of distribution, and they 
are numerous in the vagus, but the olfactory nerves have 
a distinct sheath which is nucleated.] 
(2) Medullated fibres occur also in several 
forms:— 
4. Axis-cylinders, or nerve-fibrils, covered only 
by a medullary sheath, or white substance of 
Schwann, are met with in the 
white and gray matter of the cen- 
tral nervous system, in the optic 
and auditory nerves. These me- 
dullated nerve-fibres, without any 
neurilettima, often show after death 
varicose swellings in their course 
[due to the accumulation of fluid 
between the medulla of myelin 
and the axis-cylinder]. Hence 
they are called varicose fibres. 
[The varicose appearance is easily 
produced by squeezing a small 
piece of the white matter of the 
spinal cord between a slide and a 
cover-glass. These fibres form the 
white matter of the spinal cord 
and brain, and it was formerly 
stated that nitrate of silver did not 
reveal any crosses, and that there 
are no nodes of Ranvier. Recent 
researches, however, have shown 
that these fibres of the cord are 
provided with Ranvier’s nodesand 
Node of 
Ranvier. 
Primitive 
Sheath. 
Interannular Segment. 
Nerve- 
Corpuscles. 
Axial 
Cylinder. 
White 
Substance ot 
Schwann. 
Node of 
Ranvier. 
Fig. 447. 
Fig. 448. 
Fig. 449. 
Fig- 447-—Transverse section of the nerve-fibres of the spinal cord, the axis-cylinders like dots 
surrounded by a clear space (myelin). Fig. 448.—Remak’s fibre from vagus of dog. 6, 
fibrils; n, nucleus; p, protoplasm surrounding it. Fig. 449.—Scheme of a medullated 
nerve-fibre of a rabbit acted on by osmic acid; the incisures are omitted, x 400. 
also with incisures. When acted upon by coagulating reagents, e. g., chromic 
acid, the medullary sheath appears laminated, so that on transverse section, when 
the axis-cylinder is stained, it is surrounded by concentric circles (fig. 447). Sec. 321.] 
669 
STRUCTURE OF NERVE-FIBRES. 
5- Medullated Nerve-Fibres with Schwann’s Sheath (fig. 446, 5, 
6).—These are the most complex nerve-fibres, and are 10 to 22.6 /j. to 
inch] broad. They are most numerous in, and in fact they make up the 
great mass of, the cerebro-spinal nerves, although they are also present in the 
sympathetic nerves. [When examined in the fresh and living condition in situ, 
they appear refractive and homogeneous (.Ranvier, Stirling); but if acted upon 
by reagents, they are not only refractive, but exhibit a double contour, the 
margins being dark and well defined.] Each fibre consists of — 
[1. Schwann’s sheath, neurilemma, or primitive sheath ; 
2. White substance of Schwann, medullary sheath, or myelin; 
3. Axis-cylinder composed of fibrils and surrounded by a sheath called 
the axilemma; 
4. Nerve-corpuscles.] 
A. The axis-cylinder, which occupies to \ of the breadth of the fibre, 
is the essential part of the nerve, and lies in the centre of the fibre like the 
wick in the centre of a candle (fig. 446, 6, a). Its usual shape is cylindrical, but 
sometimes it is flattened or placed eccentrically—[this is most probably due to 
the hardening process employed]. It is composed of fibrils [united by cement 
or stroma; they become more obvious near the terminations of the nerve, or 
after the action of reagents, which sometimes cause the fibrils to appear beaded. 
It is quite transparent, and stains deeply with carmine or logwood], while 
during life its consistence is semi-fluid. According to Kupffer, a fluid— 
“neuro-plasma”—lies between the fibrils [while, according to other 
observers, the whole cylinder is enclosed in an elastic sheath peculiar to itself 
and composed of neuro-keratin. This sheath is called by Kiihne the axi- 
lemma. Each axis-cylinder is an enormously long process of a ganglionic 
cell]. Chloroform and collodion render it visible, while it is most easily 
isolated as a solid rod by the action of nitric acid with excess of potassium 
chlorate. 
Frommann’s Lines.—When acted on by silver nitrate, Frommann 
observed transverse markings on the axis-cylinder, but their significance is un- 
known (fig. 446, 8). [These markings consist of alternate darker and lighter 
narrow transverse bars on the axis-cylinder, and are seen when a nerve is 
steeped for a long time in silver nitrate. They are readily made visible in this 
way in the nerve-fibres of the spinal cord, and, indeed, in the nerve-cells of 
the cord.] 
B. The white substance of Schwann, medullary sheath or myelin, 
surrounds the axis-cylinder, like an insulating medium around a telegraph wire. 
In the perfectly fresh condition it is quite homogeneous, highly glistening, 
bright, and refractive; its consistence is semi-fluid, so that it oozes out of the 
cut ends of the fibres in spherical drops (fig. 446, x), [myelin drops, which 
are always marked by concentric lines, are highly refractive, and best seen 
when a fresh nerve is teased in salt solution]. After death, or after the action 
of reagents, it shrinks slightly from the sheath, so that the fibres have a double 
contour, while the substance itself breaks up into smaller or larger droplets, 
due not to coagulation (.Pertik), but, according to Toldt, to a process like 
emulsification, the drops pressing against each other. Thus, the fibre is broken 
up into masses, so that it has a characteristic appearance (fig. 446, 6). It 
contains a large amount of cerebrin and lecithin, which swell up to form myelin- 
like forms in warm water. It also contains fatty matter, so that these fibres 
are blackened by osmic acid, [while boiling ether extracts cholesterin from 
them]. Chloroform, ether, and benzin, by dissolving the fatty and some 
other constituents of the fibres, make them very transparent. [Some observers 
describe a fluid lying between the medulla and the axis-cylinder.] 670 
STRUCTURE OF NERVE-FIBRES. 
[Sec. 321. 
C. The Sheath of Schwann, or the neurilemma, lies immediately out- 
side of and invests the white sheath (fig. 446, 6, c), and is a delicate structureless 
membrane, comparable to the sarcolemma of a muscular fibre. 
D. Nerve-Corpuscles.—At fairly wide intervals under the neurilemma, 
and lying in depressions between it and the medullary sheath, are the nucleated 
nerve-corpuscles, which are readily stained by pig- 
ments (fig. 449). [They may be compared to the 
muscle-corpuscles, the nuclei being surrounded by a 
small amount of protoplasm which sometimes contains 
pigment. They are not so numerous as in muscle.] 
[Adamkiewicz describes nerve-corpuscles, or “ demi- 
lunes ” under the neurilemma, quite distinct from 
the ordinary nerve-corpuscles. They are stained yel- 
low by saffranin, while the ordinary nerve-corpuscles 
are stained by methyl-anilin.] 
Ranvier’s Nodes or Constrictions.—The neu- 
rilemma forms in broad fibres at longer, and in nar- 
rower ones at shorter intervals, the nodes or con- 
strictions of Ranvier (fig. 446, 6, /, t \ fig. 449; 
fig. 450, fs). They are constrictions which occur at 
regular intervals along a nerve-fibre; at them the 
white substance of Schwann is interrupted, so that the 
sheath of Schwann lies upon the axis-cylinder [or its 
elastic sheath] at the nodes. The part 
of the nerve lying between any two 
nodes is called an interannular or 
inter-nodal segment, and each 
such segment contains one or more 
nuclei, so that some observers look 
upon the whole segment as equivalent 
to one cell. 
The function of the nodes 
seems to be to permit the diffusion 
of plasma through the outer sheath 
into the axis-cylinder, while the de- 
composition-products are similarly 
given off. [A coloring-matter like 
picro-carmine diffuses into the fibre 
only at the nodes, and stains the 
axis-cylinder red, although it does 
not diffuse readily through the white 
substance of Schwann.] 
Incisures (of Schmidt and Lan- 
termann).—Each interannular seg- 
ment in a stretched nerve shows, run- 
ning across the white substance, a 
number of oblique lines, which are 
called incisures (figs. 450, 451). 
They indicate that the segment is 
built up of a series of conical sec- 
tions, each of which is bevelled at 
its ends, and the bevels are arranged 
in an imbricate manner, the one over 
the other, while the slight interval between them appears as an incisure. 
Each such section of the white matter is called a cylinder cone (Kuhnt). 
Fig- 451- 
Fig. 450. 
Medullated nerve-fibres (with 
osmic acid), a, axis-cylinder; 
s, sheath of Schwann; n, 
nucleus; p, p, granular sub- 
stance at the poles of the 
nucleus; r, r, Ranvier’s 
nodes where the medullary 
sheath is interrupted and 
the axis cylinder appears; 
i, i, incisures of Schmidt. 
Medulla ted 
nerve - fibres 
blackened by 
osmic acid, fs, 
R a n v i e r’s 
node; s c h, 
Schwann’s 
sheath. Sec. 321.] 
STRUCTURE OF NERVE-FIBRES. 
671 
Neuro-Keratin Sheath.—According to Ewald and Kiihne, the axis- 
cylinder, as well as the white substance of Schwann, is covered with an exces- 
sively delicate sheath, consisting of neuro-keratin, and the two sheaths are 
connected by numerous transverse and oblique fibrils, which permeate the white 
substance. [The myelin seems to lie in the interstices of this mesh work.] 
[Rod-like Structures in Myelin.—If a nerve be hardened in ammonium 
chromate (or picric acid'), M’Carthy has shown that the myelin exhibits rod-like 
structures radiating from the axis-cylinder outwards, which are stained with log- 
wood and carmine. The rods are probably not distinct from each other, but 
are perhaps part of the neuro-keratin network already described.] 
Action of Nitrate of Silver.—When a small nerve, e.g., the intercostal 
nerve of a mouse, is acted on by silver nitrate, it is seen to be covered by an 
endothelial sheath composed of flattened endothelial, cells (fig. 432), while the 
nerve-fibres themselves exhibit crosses along their 
course. These crosses are due to the penetration of 
the silver solution at the nodes, where it stains the 
cement-substance and also part of the axis-cylinder, 
so that the latter sometimes exhibits transverse mark- 
ings called Frommann’s lines (fig. 446, 8).] 
[New Methods.—Much progress has recently 
been made in tracing the course of medullated 
nerve-fibres by the action of new staining reagents ; 
thus acid fuchsin stains the myelin deeply, leaving 
the other parts unstained; at least, it can be so 
manipulated as to yield this result. Weigert’s 
Method and its modifications have yielded most 
important results, and proved that medullated 
nerve-fibres exist in many parts of the central 
nervous system where they cannot be seen in the 
ordinary way. The nerve-tissue is hardened in a 
solution of a chromium salt, and placed in a half- 
saturated solution of cupric acetate; it is then 
stained with logwood, and afterwards the elements 
are differentiated by steeping the sections in a solu- 
tion of ferricyanide of potash and borax. The 
myelin is colored a logwood tint.] 
In the spinal nerves, those fibres are thickest which have 
the longest course before they reach their end-organ (Schwalbe), 
while those ganglion-cells are largest which send out the longest nerve-fibres (Pierret). [Gaskell 
finds that the longest nerves are not necessarily the thickest, for the visceral nerves in the vagus 
are small nerves, and yet run a very long course.] 
Division of Nerves.—Medullated nerve-fibres run in the nerve-trunks 
without dividing; but when they approach their termination they often divide 
dichotomously [at a node], giving rise to two similar fibres, but there may be 
several branches at a node (fig. 454, /). [The divisions are numerous in motor 
nerves to striped muscles.] In the electrical nerves of the malapterurus and 
gymnotus, there is a great accumulation of Schwann’s sheaths round a nerve, 
so that a nerve-fibre is as thick as a sewing-needle. Such a fibre, when it 
divides, breaks up into a bundle of smaller fibres. 
[Nerve-Sheaths.—A nerve-trunk consists of bundles, or fasciculi, of 
nerve-fibres. The bundles are held together by a common connective-tissue 
sheath (fig. 453, ep), the epineurium [sometimes called the perineurium ex- 
ternum, general perineurium, or in the older writers neurilemma], which con- 
tains the larger blood-vessels, lymphatics, and sometimes fat and plasma cells. 
Fig. 452. 
Intercostal nerve of a mouse 
(single fasciculus of nerve- 
fibres) stained with silver 
nitrate. Endothelial sheath 
stained, and some nodes of 
Ranvier indicated by crosses. 672 
NERVE-SHEATHS. 
[Sec. 321. 
Each bundle is surrounded with its own sheath or perineurium (pe), which 
consists of lamellated connective-tissue disposed circularly, and between the 
lamellae are lymph-spaces lined by flattened endothelial plates. These lymph- 
spaces may be injected from and communicate with the lymphatics (Key and 
Retzius).] The nerve-fibres within any bundle are held together by delicate 
connective-tissue, which penetrates between the adjoining fibres, constituting 
the endoneurium (ed). It consists of delicate fibres with branched connec- 
tive-tissue corpuscles (fig. 446, 6, d), and in it lie the capillaries, which are not 
very numerous, and are arranged to form elongated open meshes. 
[Henle’s Sheath.—When a nerve is traced to its distribution, it branches and becomes smaller, 
until it may consist only of a few bundles or even a single bundle of nerve-fibres. As the bundle 
branches, it has to give off part of its lamellated sheath or perineurium to each branch, so that, 
as we pass to the periphery, the smaller bundles are surrounded by few lamellae. In a bundle 
containing only a few fibres, this sheath may be much reduced, or may consist only of thin, 
flattened, connective-tissue corpuscles with a few fibres. A sheath surrounding a few nerve-fibres 
is called Henle's Sheath by Ranvier.] 
Fig. 453- 
Trans, section of a nerve (median), ep, epineurium; pe, perineurium; edt endoneurium. 
[Nervi Nervorum.—Marshall and V. Horsley have shown that the. nerve-sheaths are pro- 
vided with special nerve-fibres, in virtue of which they are endowed with sensibility.] 
Development of Nerve-Fibres.—At first nerve-fibres consist only of fibrils, i.e., of axis- 
cylinders, which become covered with connective substance, and ultimately the white substance 
of Schwann is developed in some of them. The growth in length of the fibres takes place by 
elongation of the individual “ interannular ” segments, and also by the new formation of these 
( Vignal). [Medullated nerve-fibres are derived from the epiblast. The axis-cylinders of those 
of the anterior root grow from, and are in reality, the axis-cylinders of nerve-cells—called 
neuroblasts in their early stage. The fibres of the posterior root of a spinal-nerve grow from 
the nerve-cells or neuroblasts of the rudiment of the spinal ganglion. The axis-cylinder processes, 
which ultimately form the fibres of the anterior roots, appear about the fourth week of the 
human foetus. They grow slowly and do not reach the tips of the toes or fingers until after the 
second month (His).~\ 
II. Ganglionic or Nerve-Cells [vary much in size and general characters. 
They may have one pole, when they are unipolar (spinal ganglion cells) ; or 
two poles—bipolar (spinal ganglion cells of fishes) ; or many poles, when they 
are multipolar (cells of the spinal cord).]—i. Multipolar nerve-cells 
(fig. 446, I) occur partly as large cells (100 p), and are visible to the unaided Sec. 321.] 
NERVE-CELLS. 
673 
eye, as in the anterior horn of the spinal cord, and in a different form in the 
cerebellum, and partly in a smaller form (20 to 10 \x) in the posterior horns of 
the spinal cord, many parts of the cerebrum and cerebellum, and in the retina. 
They may be spherical, ovoid, pyramidal [cerebrum], pear- or flask-shaped 
[cerebellum], (x) Each cell is provided with numerous branched pro- 
cesses, which gives the cells a characteristic appearance. [Deiters isolated 
such cells from the anterior horn of the gray matter of the spinal cord, so that 
this special form of cell is sometimes called “Deiters’ cell” (fig. 446, I).] 
Those of the spinal cord are devoid of a cell envelope, are of soft consistence, 
and exhibit a fibrillated structure, which may extend even into the processes. 
Fine granules lie scattered throughout the cell-substance between the fibrils. 
Not unfrequently yellow or brown granules of pigment are also found, either 
collected at certain parts in the cell or scattered 
throughout it. The relatively large nucleus con- 
sists of a clear envelope enclosing a resistant sub- 
stance. It does not appear to have a membrane in 
youth {Schwalbe'). Within the nucleus lies the 
nucleolus, which in the recent condition is angu- 
lar, provided with processes and capable of motion, 
but after death is highly refractive and spherical. 
(2) Each cell is provided with one unbranched 
process, constituting the axial-cylinder process 
(I, z) which remains unbranched, but it soon be- 
comes covered with the white substance of Schwann, 
and the other sheaths of a medullated nerve, so that 
it becomes the axial cylinder of a nerve-fibre. Thus 
a nerve-fibre is merely an excessively long, un- 
branched process of a nerve-cell pushed outwards 
towards the periphery.] It is now definitely ascer- 
tained that the cerebral cells have such processes. 
All the other processes divide very frequently until 
they form a branched, root-like, complex arrange- 
ment of the finest primitive fibrils. These are called 
protoplasmic processes (I, y). By means of 
these processes it is supposed adjoining ceils are 
brought into communication with each other, so that 
inpulses can be conducted from one cell to another. 
Further, many of these fibrils approximate to each 
other, and join together to form axis-cylinders of 
other nerve-fibres. The most recent observers, how- 
ever, state that the processes of neighboring cells 
do not anastomose, they merely come into relation 
with each other. [V. Thanhoffer states that he has 
traced the axis-cylinder process to the nucleus and 
nucleolus.] 
[His, Forel, and other observers deny the existence of these 
anastomoses. The processes of adjoining nerve-cells merely 
approach each other, but do not actually unite with each other, 
there being always an intermediate substance between them.] 
2. Bipolar cells are best developed in fishes, e. g., in the spinal ganglia 
of the skate, and in the Gasserian ganglion of the pike. They appear to be 
nucleated, fusiform enlargements of the axis-cylinder (fig. 446, on the right of I). 
The white substance often stops short on each side of the enlargement, but some- 
times the white substance and the sheath of Schwann passover the enlargement. 
Cell from the Gasserian gan- 
glion. n, nuclei of the 
sheath; t, fibre dividing at 
a node of Ranvier. 
Fig. 454- 674 
NERVE-CELLS. 
[Sec. 321. 
3. Nerve cells with connective-tissue capsules occur in the peripheral 
ganglia of man (fig. 446, II). The soft body of the cell, which is provided 
with several processes, is covered by a thick, tough capsule composed of several 
layers of connective-tissue corpuscles ; while the inner surface of the composite 
capsule is lined by a layer of delicate endothelial cells (fig. 454). The body 
of the cells in the spinal ganglia is traversed by a network of fine fibrils 
(.Flemming). The capsule is continuous with the sheath of the nerve-fibre. 
Rawitz and G. Retzius find that the cells of the spinal ganglia are unipolar, 
the outgoing fibre taking a half-turn within the capsule before it leaves the cell 
(fig. 454). Retzius [and Ranvier] observed the process to divide like a T- 
Perhaps this division corresponds to the two processes of a bipolar cell. The 
jugular ganglion and plexus gangliiformis vagi in man contain only unipolar 
cells, so that, in this respect, they may be compared to spinal ganglia. The 
same is the case in the Gasserian ganglion ; while the ciliary, spheno-palatine, 
otic, and submaxillary ganglia structurally resemble the ganglia of the sympa- 
thetic. 
4. Ganglionic cells with spiral fibres occur chiefly in the abdominal 
sympathetic of the frog (Beale, J. Arnold). The body of the cell is usually 
pyriform in shape, and from it proceeds an unbranched straight process 
(fig. 446, III, n), which ultimately becomes the axis-cylinder of a nerve. A 
spiral fibre springs from the cell (? a network), emerges from it, and curves in 
a spiral direction round the former (o'). The whole cell is surrounded by a 
nucleated capsule (:m). We know nothing of the significance of the different 
fibres. According to Ehrlich, the straight fibres conduct in a centrifugal and 
the spinal process in a centripetal direction. 
[Some light has recently been thrown upon the structure of the pyriform cells of the frog, by 
the use of methylene-blue (Ehrlich, Feist, Smirnow). This substance stains certain parts of 
the cell when it is injected into the blood, and the stain can afterwards be fixed. The capsule 
remains colorless, and from the body of the cell there arises a straight fibrillated process. 
Round the cell are a number of fine fibrils, pericellular fibrils, which unite to form the spiral 
fibre, which is much finer than the fortner, and stains blue with methylene blue when exposed 
to the air. Usually all the straight fibres from adjoining cells run in one direction, and all 
straight fibres in the opposite direction.] 
322. CHEMICAL AND MECHANICAL PROPERTIES OF 
NERVOUS SUBSTANCE.—1. Proteids.—Albumin occurs chiefly in 
the axis-cylinder and in the substance of the ganglionic cells. Some of this 
proteid substance presents characters not unlike those of myosin (§ 293). 
Dilute solution of common salt extracts a proteid from nervous matter, which 
is precipitated by the addition of much water and also by a concentrated solu- 
tion of common salt (.Petrowsky). Potash-albumin and a globulin-like substance 
are also present. [Halliburton finds that the proteids of nervous matter are all 
globulins; albumins, albumoses, and peptones being absent.] Nuclein occurs 
especially in the gray matter (§ 250, 2), while neuro-keratin, a body con- 
taining much sulphur and closely related to keratin, occurs in the corneous 
sheath of nerve-fibres (p. 671). If gray nervous matter be subjected to artificial 
digestion with trypsin, both of these substances remain undigested (Kuhne and 
Ewald~). Pure neuro-keratin is obtained by treating the residue with caustic 
potash. The sheath of Schwann does not yield gelatin, but a sub- 
stance closely related to elastin (§ 250, 6), from which it differs, however, 
in being more soluble in alkalies. The connective-tissue of nerves yields 
gelatin. 
2. Fats and other allied substances soluble in ether, more especially in the 
white matter:— 
(a) Protagon, wrhich contains N and P, is similar to cerebrin, and is, 
according to its discoverer, the chief constituent of the brain (.Liebreich). Sec. 322.] 
675 
CHEMICAL COMPOSITION OF NERVES. 
According to Hoppe-Seyler and Diaconow, it is a mixture of lecithin and cerebrin. [The 
investigations of Gamgee and Blankenhorn have shown, however, that protagon is a definite 
chemical body. They find that, instead of being unstable, it is a very stable body.] It is a 
glueoside, and crystalline, and can be extracted from the brain by warm alcohol, and when boiled 
with baryta yields the decomposition-products of lecithin. 
(b) Cerebrin, free from phosphorus (§ 250, 3). 
Cerebrin is a white powder composed of spherical granules soluble in hot alcohol and ether, 
but insoluble in cold water. It is decomposed at 8o° C., and its solutions are neutral. When 
boiled for a long time with acids, it splits up into a left rotatory body like sugar, and another 
unknown product. Preparation.—Rub up the brain into a thin fluid with baryta water. 
Extract the separated coagulum with boiling alcohol. The extract is frequently treated with 
cold ether to remove the cholesterin ( W. Milller). Parkus separated from cerebrin its homo- 
logue, homocerebrin, which is slightly more soluble in alcohol, and the clyster-like body, 
encepbalin, which is soluble in hot water. 
(c) Lecithin and its decomposition-products—glycero-phosphoric acid and 
oleo-phosphoric acid (§ 251). 
Lecithin is an ethereal compound of neurin, in which the latter takes the place of the alcohol. 
Neurin (or Cholin — C5H15N02) is a strongly alkaline, colorless fluid, forming crystalline salts 
with acids. It is soluble in water and alcohol, and has been formed synthetically from glycol 
and trimethylamin. Lecithin is a salt of the base neurin. 
3. The following substances are extracted by water : Xanthin and hypo- 
xanthin [Scherer), kreatin {Lerch), inosit (W. Muller), ordinary lactic acid 
(Gscheidlen), acetic and formic acids, uric acid (?), and volatile fatty acids; 
leucin (in disease), urea (in uraemia), and a substance like starch in the human 
brain (jaffe). All these substances are for the most part products of the regres- 
sive metabolism of the tissues. 
Reaction.—Nervous substance, when passive, is neutral or feebly alkaline in 
reaction, while active (? and dead) it is acid (.Funke). The gray matter of the 
brain, when quite fresh, is alkaline (Liebreich), but death rapidly causes it to 
become acid ( Gscheidlen). 
The reaction of nerve-fibres varies during life. After introducing methylene-blue into the 
body of a living animal, Ehrlich found that the axis-cylinder became blue, i.e., in those nerves 
which have an alkaline reaction. 
The nerves after death have a more solid consistence, so that in all proba- 
bility some coagulation or change, “nerve rigor,” comparable to the stiffen- 
ing of muscle, occurs in them after death, while at the same time a free acid is 
liberated (§ 295). If a fresh brain be rapidly “ broiled ” at ioo° C., it, like a 
muscle similarly treated, remains alkaline (§ 295). 
Chemical Composition of 
Gray Matter. 
White Matter. 
Water, 
81.6 per cent. 
68.4 per cent. 
Solids, 
18.4 “ 
31.6 “ 
The solids consist of:— 
— 
Proteids (Globulins), 
55-4 “ 
24.7 “ 
Lecithin, 
Cholesterin and fats, 
17.2 “ 
9.9 “ 
18.7 “ 
52.1 “ 
Cerebrin, 
0.5 “ 
9-5 “ 
Substances insoluble in ether, 
6.7 “ 
3-3 “ 
Salts, 
i-5 “ 
0.5 “ 
100.0 
100.0 
In ioo parts of ash, Breed found potash 32, soda 11, magnesia 2, lime 0.7, NaCl 5, iron phos- 
phate 1.2, fixed phosphoric acid 39, sulphuric acid 0.1, silicic acid 0.4. 
[Ptomaines ($ 166) are obtained from putrefying brain. They have an effect on the motor 
nerves like curare, but in much less degree, while the phenomena last for a much shorter time 
( Guar esc hi and Mosso).) 676 
[Sec. 322. 
METABOLISM AND STIMULI OF NERVES. 
Mechanical Properties.—One of the most remarkable mechanical proper- 
ties of nerve-fibres is the absence of elastic tension according to the varying 
positions of the body. Divided nerves do not retract; such nerves exhibit 
delicate, microscopic, transverse folds [like watered silk], or Fontana’s trans- 
verse markings. 
The cohesion of a nerve is very considerable. When a limb is forcibly 
torn from the body, as sometimes happens from its becoming entangled in 
machinery, the nerve not unfrequently remains unsevered, while the other soft 
parts are ruptured. [Tillaux found that a weight of no to 120 lbs. was re- 
quired to rupture the sciatic nerve at the popliteal space, while to break the 
median or ulnar nerve of a fresh body, a force equal to 40 to 50 lbs. was required. 
The toughness and elasticity of nerves are often well shown in cases of injury 
or gun-shot wounds. The median or ulnar nerve will gain 15 to 20 centimetres 
(6 to 8 inches) before breaking. Weir Mitchell has shown that a healthy nerve 
will bear a very considerable amount of pressure and handling, and, in fact, the 
method of nerve-stretching depends upon this property of a nerve-trunk.] 
323. METABOLISM OF NERVES.—Influence of Blood-Sup- 
ply.—We know very little regarding the metabolic processes which take place 
in nerve-tissue. Some extractives are obtained from nerve-tissue, and they 
may, perhaps, be regarded as decomposition-products (p. 675). It has not 
been proved satisfactorily that during the activity of nerves there is an exchange 
of O and C02. That there is an exchange of materials within the nerves is 
proved by the fact that, after compression of the blood-vessels of the 
nerves, the excitability of the nerves falls, and is restored again when the circu- 
lation is re-established. Compression of the abdominal aorta causes paralysis 
and numbness of the lower half of the body, while occlusion of the cerebral ves- 
sels causes almost instantaneously cessation of the cerebral functions. The meta- 
bolism of the central nervous organs is much more active than that of the 
nerves themselves. [If the abdominal aorta of a rabbit be compressed for a 
few minutes, the hind limbs are quickly paralyzed, the animal crawls forward 
on its fore-legs, drawing the hind limbs in an extended position after it.] The 
ganglia form much lymph. According to Hodge, the cells of the spinal ganglia 
when they are stimulated [/. e., by stimulating the central end of a divided 
spinal nerve with an electrical current] can be distinguished from resting gang- 
lionic cells by their smaller size, the presence of vacuoles in their protoplasm, 
as well as by their smaller nuclei. 
324. EXCITABILITY OF THE NERVES—STIMULI.—Nerves 
possess the property of being thrown into a state of excitement by stimuli, and 
are, therefore, said to be excitable or irritable. The stimuli may be applied 
to, and may act upon, any part of the nerve. [Such stimuli as act on a nerve 
in any part of its course are c alled general stimuli. The following are the 
various kinds of general stimuli, i. <?., modes of motion, which act upon 
nerves:— 
1. Mechanical, e.g., pinching. 
2. Thermal, e.g., suddenly raising its temperature. 
3. Chemical, e.g., dilute acids and alkalies. 
4. Physiological. 
5. Electrical, e.g., an induction shock. 
1. Mechanical stimuli act upon nerves when they are applied with suf- 
ficient rapidity to produce a change in the form of the nerve-particles, e.g., a 
blow, pressure, pinching, tension, puncture, and section. In the case of sen- 
sory nerves, when ihey are stimulated, pain is produced, as is felt when a 
limb “ sleeps,” or when pressure is exerted upon the ulnar nerve at the bend of Sec. 324.] 
THERMAL STIMULI. 
677 
the elbow. When a motor nerve is stimulated, motion results in the muscle 
attached to the nerve. If the continuity of the nerve-fibres be destroyed, or, 
what is the same thing, if the continuity of the axial cylinder be interrupted by 
the mechanical stimulus, the conduction of the impulse across the injured part is 
interrupted. If the molecular arrangements of the nerves be permanently de- 
ranged, e. g., by a violent shock, the excitability of the nerves may be thereby 
extinguished. 
A slight blow applied to the radial nerve in the fore-arm, or to the axillary nerves in the 
supraclavicular groove, is followed by a contraction of the muscles supplied by these nerves. 
Under pathological conditions, the excitability of a nerve for mechanical stimuli may be increased 
enormously. 
Tigerstedt ascertained that the minimal mechanical stimulus is represented by 900 milli- 
gram-millimetres, and the maximum by 7000 to 8000. Strong stimuli cause fatigue, but the 
fatigue does not extend beyond the part stimulated. A nerve when stimulated mechanically 
does not become acid. Slight pressure without tension increases the excitability, which dimin- 
ishes after a short time. The mechanical work produced by an excited muscle in consequence 
of a stimulus was 100 times greater than the mechanical energy of the mechanical nerve-stimulus. 
Continued pressure upon a mixed nerve paralyzes the motor sooner 
than the sensory fibres. If the stimulus be applied very gradually, the nerve 
may be rendered inexcitable without manifesting any signs of its being stimu- 
lated (.Fontana, 1758). Paralysis, due to continuous pressure gradually applied, 
may occur in the region supplied by the branchial nerves; the left recurrent 
laryngeal nerve also may be similarly paralyzed from the pressure of an aneur- 
ism of the arch of the aorta. 
By increasing the pressure on a nerve by using a gradually increasing weight, there is at first 
an increase and then a decrease of the excitability. Pressure on a mixed nerve abolishes reflex 
conduction sooner than motor conduction (.Kronecker and Zederbauni). 
Nerve-stretching is employed for therapeutical purposes. If a nerve be exposed and 
stretched, or if it be made sufficiently tense, the nerve is stimulated. Slight tension increases 
the reflex excitability (Schleich), while violent extension produces a temporary diminution or 
abolition of the excitability (Valentin). The centripetal or sensory fibres of the sciatic nerve 
are sooner paralyzed thereby than the centrifugal or motor (Conrad). During the process of 
extension, mechanical changes are produced, either in the nerve itself or in its end-organs, 
causing an alteration of the excitability, but it may also affect the central organs. The 
paralysis, which sometimes occurs after forcible stretching, usually rapidly disappears. There- 
fore, when a nerve is in an excessively excitable condition, or when this is due to an inflam- 
matory fixation or constriction of the nerve at some part of its course, nerve-stretching may 
be useful, partly by diminishing the excitability, partly by breaking up the inflammatory 
adhesions. In cases where stimulation of an afferent nerve gives rise to epileptic or tetanic 
spasms, nerve-stretching may be useful by diminishing the excitability at the periphery, in 
addition to the other effects already described. It has also been employed in some spinal 
affections, which may not as yet have resulted in marked degenerative changes. 
Tetanomotor.—For physiological purposes, a nerve may be stimulated mechanically by means 
of Heidenhain’s tetanomotor, which is simply an ivory hammer attached to the prolonged 
spring of a Neef’s hammer of an induction machine. [A more delicate form of this instrument 
was used by Tigerstedt ($ 335).] The rapid vibration of the hammer communicates a series of 
mechanical shocks to the nerve upon which it is caused to beat. Rhythmic extension of a nerve 
causes contractions and even tetanus. 
2. Thermal Stimuli.—If a frog’s nerve be heated to 450 C., its excita- 
bility is first increased and then diminished. The higher the temperature, the 
greater is the excitability, and the shorter its duration (Afanasieff). If a nerve be 
heated to 50° C. for a short time, its excitability and conductivity are abolished. 
The frog’s nerve alone regains its excitability on being cooled (.Pickford). If 
the temperature be raised to 65° C., the excitability is abolished without the 
occurrence of a contraction, while its medulla is broken up (Kckhard). Sud- 
den cooling of a nerve to 50 C. acts as a stimulus, causing contraction, in a 
muscle, while sudden heating to 40° or 450 C. produces the same result. If the 
temperature be increased still more, instead of a single contraction a tetanic 
condition is produced. All such rapid variations of temperature quickly 
exhaust the nerve and kill it. If a nerve be frozen gradually, it retains its 678 
CHEMICAL STIMULI. 
[Sec. 324. 
excitability on being thawed. The excitability lasts long in a cooled nerve ; 
in fact, it is increased in a motor nerve, but the contractions are not so high 
and more prolonged, while the conduction in the nerve takes place more slowly. 
Amongst mammalian nerves, the afferent and vaso-dilator nerves at 450 to 50° 
C. exhibit the results of stimulation, while the others only show a change in 
their excitability. When cooled to —(— 50 C., the excitability of all the fibres 
is diminished (Griitzner). 
3. Chemical Stimuli excite nerves when they act with a certain rapidity, 
and thereby alter the condition of the nerve (p. 603). Most chemical stimuli 
act by first increasing the nervous excitability, and then diminishing or paralyz- 
ing it. Chemical stimuli, as a rule, have less effect upon sensory than upon 
motor fibres (.Eckhard). According to Griitzner, the inactivity of chemical 
stimuli, so often observed when they are applied to sensory nerves, depends in 
great part upon the non-simultaneous stimulation of all the nerve-fibres. 
Amongst chemical stimuli are—(a) rapid abstraction of water by dry air, 
blotting paper, exposure in a chamber containing sulphuric acid, or by the 
action of solutions which absorb fluids, e. g., concentrated solutions of neutral 
alkaline salts (NaCl excites only motor fibres in mammals—Griitzner), sugar, 
urea, concentrated glycerin (and ? some metallic salts). The subsequent addi- 
tion of water may abolish the contractions, while the nerve may still remain 
excitable. The abstraction of water first increases and afterwards diminishes 
the excitability. The imbibition of water diminishes the excitability, (f) Free 
alkalies, mineral acids (not phosphoric), many organic acids (acetic, oxalic, 
tartaric, lactic), and most salts of the heavy metals. While the acids act as 
stimuli, only when they are somewhat concentrated, the caustic alkalies act in 
solutions of 0.8 to 0.1 percent. (Kiihne). Neutral potash salts, in a concen- 
trated form, rapidly kill a nerve, but they do not excite it nearly so strongly as 
the soda compounds. Dilute solutions of the neutral potash salts first increase 
and afterwards diminish it (Ranke), as can be shown by stimulation with an 
induction shock (Biedermann). (c) Various chemical substances, e. g., 
dilute alcohol, ether, chloroform, bile, bile-salts, and sugar. These substances 
usually excite contractions, and afterwards rapidly kill the nerve. Ammonia, 
lime-water, some metallic salts, carbon bisulphide, and ethereal oils kill the 
nerve without exciting it—at least without producing any contraction in a frog’s 
nerve-muscle preparation. [The nerve of a nerve-muscle preparation may be 
dipped into ammonia, but no contraction results, while the slightest traces of 
ammonia applied to a muscle cause contraction.] Carbolic acid does the 
same, although when applied directly to the spinal cord it produces spasms. 
These substances excite the muscles when they are directly applied to them. 
Tannic acid does not act as a stimulus either to nerve or muscle. As a general 
rule, the stimulating solution must be more concentrated when applied to a nerve 
than to muscle, in order that a contraction may be produced. 
[Methods.—If a nerve-muscle preparation of a frog’s limb be made, and a straw flag (p. 601) 
attached to the toes while the femur is fixed in a clamp, and its nerve be then dipped in a 
saturated solution of common salt, the toes soon begin to twitch, and by and by the whole limb 
becomes tetanic, and thus keeps the straw flag extended. The effect of fluid on a muscle or 
nerve is easily tested by fixing the muscle in a clamp, while a drop of the fluid is placed on a 
greased surface, which gives it a convex form. The end of the muscle or nerve is then brought 
into contact with the cupola of the drop (ATuhne).] 
4. The Physiological or normal stimulus excites the nerves in the nor- 
mal intact body. Its nature is entirely unknown. The “nerve-motion” 
thereby set up travels either in a “centrifugal” or efferent or outgoing 
direction from the central nervous system, giving rise to motion, inhibition of 
motion, or secretion ; or in a “centripetal ’ ’ or afferent or ingoing direction 
from the specific end-organs of the nerves of the special senses or the sensory 
nerves. In the latter case, the impulse reaches the central organs, where it may Sec. 324.] 
ELECTRICAL STIMULI. 
679 
excite sensation or perception, or it may be transferred to the motor areas, and 
be conducted in a centrifugal direction, constituting a “ reflex stimulation ” 
(§360). A single physiological nerve-impulse travels more slowly than that 
excited by the momentary application of an induction shock (Loven, v. Kries). 
It is not a uniform process excited by varying intensity and greater or less 
frequency of stimulation, but it is essentially a process varying considerably in 
duration, and it may even last as long as pi second (v. Kries). 
5. Electrical Stimuli.—[The following forms of electrical stimuli may be 
used : — 
(1) Constant current, which may be made or broken (§ 328). 
(2) Induction shocks, either make or break shocks (§ 329). 
(3) Interrupted current (§ 329). 
The electrical current acts most powerfully upon the nerves at the moment 
when it is applied, and at the moment when it ceases (§ 336) ; in a similar way, 
any increase or decrease in the strength of a constant current acts as a stimulus. 
If an electrical current be applied to a nerve, and its strength be very gradu- 
ally increased or diminished, then the visible signs of stimulation of the nerve 
are very slight. As a general rule, the stimulation is more energetic the more 
rapid the variations of the strength of the current applied to the nerve, i. e., 
the more suddenly the intensity of the stimulating current is increased or 
diminished (du Bois-Reymond). 
An electrical current must have a certain strength or liminal intensity 
before it is effective. By uniformly increasing the strength of the current, the 
size of the contraction increases rapidly at first, then more slowly (Tigerstedt 
and Willhard). 
An electrical current, in order to stimulate a nerve, must have a certain 
duration, it must act at least during o.oor5 second (Kick, 1863); even with 
'currents of slightly longer duration, the opening shock may have no effect. 
If the duration of the closing shock of a constant current be so arranged that 
it is just too short to be active, then it merely requires to last 1.3 to 2 times 
longer to produce the most complete effect ( Grilnhagen). 
The electrical current is most active when it flows in the long axis of the 
nerve ; it is inactive when applied vertically to the axis of the nerve ( Galvani). 
Similarly, muscles are incomparably less excited by transverse than by longi- 
tudinal currents (Giuffre). 
The greater the length of nerve traversed by the current, the less the 
stimulus that is required (Pfaff). 
Constant Current on a Nerve.—If the constant current be used as a 
nervous stimulus, the stimulating effect on the peripheral terminations of 
sensory nerves, e.g., tongue or skin, is most marked at the moment of mak- 
ing and breaking the current; during the time the current passes only slight 
excitement is perceived, but, even under these circumstances, very strong 
currents may cause very considerable, and even unbearable, sensations \i.e., con- 
formable to the rule that sudden variations in the intensity of a current act as 
a stimulus, there is, if the current be strong enough, a sensation on making 
(closing) or breaking (openirtg) the constant current or on both events. If, 
however, the current be strong, then sensations are experienced whilst the 
current is flowing. This is different from what obtains in motor nerves.] If 
a constant current be applied to a motor nerve, the greatest effect is produced 
when the current is made or closed [closing or make contraction], and when 
it is broken or opened [opening or break contraction]. [No contraction 
takes place while the current is passing. An important change takes place in 
the nerve all the time the constant current is flowing, viz., the condition of 
electrotonus is set up, whereby the physiological properties of the nerve 680 
EXCITABILITY OF NERVES. 
[Sec. 324. 
are greatly modified (§ 333), but these do not concern us at present.] Under 
certain circumstances, however, while the current is passing, the stimulation 
does not cease completely, for, with a certain strength of stimulus, the muscle 
remains in a state of tetanus (galvanotonus or “ closing tetanus ”) (.Pfliiger). 
For the effect of a constant current on muscles, see p. 614. With strong 
currents this tetanus does not appear, chiefly because the current diminishes 
the excitability of the nerves, and thus develops resistance, which prevents 
the stimulus from reaching the muscle. According to Hermann, a descending 
current applied to the nerve, at a distance from the muscles, causes this tetanus 
more readily, while an ascending current causes it more readily when the 
current is closed near the muscle. The constant current is said by Griitzner to 
have no effect on vaso-motor and secretory fibres. 
Over-maximal Contraction.—By gradually increasing the strength of the electrical stim- 
ulus applied to a motor nerve, Fick observed that the muscular contractions (height of the lift) 
at first increased proportionally to the increase of the stimulus, until a maximal contraction 
was obtained. If the strength of the stimulus be increased still further, another increase of the 
contraction above the first-reached maximum is obtained. This is called an “ over-maximal 
contraction.” Occasionally between the first maximum and the second there is a diminution, 
or indeed absence of, or gap or hiatus in, the contractions. The cause of this lies in the 
positive pole, which with a certain strength of current is sufficient to prevent the further trans- 
mission of the excitement ($ 335). On continuing to increase the induction current, ultimately 
a stage is reached where the stimulation at the negative pole again becomes stronger than the 
block caused at the positive pole, and this overcomes the latter. The contractions before the 
gap are caused by the occurrence of the induction current (their latent period is short); the 
contractions (long latent period, like that after all opening shocks—Waller), after the gap, are 
caused by the disappearance of the induction current, i.e., by polarization; this is added to 
the stimulation proceeding from the negative pole, which after the gap overcomes the inhibition 
at the positive pole, and excites the over-maximal contractions (Tigerstedt and Willhard). 
Tetanus.—If single electrical shocks either from a constant current or in- 
duced shocks of short duration be rapidly applied after each other to a nerve, 
tetanus in the corresponding muscle is produced (§ 298, 
III). 
A motor nerve has a greater specific excitability for 
electrical stimuli than the muscle-substance. This is 
proved by the fact that a feebler stimulus suffices to 
excite a muscle when applied to the nerve than when it 
is applied to the muscle directly, as occurs when the 
terminations of the motor nerves are paralyzed by 
curare (§ 296, 2, Rosenthal'). 
Soltmann found that the excitability of the motor 
nerves of new-born animals for electrical stimuli is 
less than in adults. The excitability increases until the 
5th to 10th month. 
Unequal Excitability of a Nerve.—Under cer- 
tain circumstances, the nearer the part of the motor 
nerve stimulated lies to the central nervous system, the 
greater is the effect produced (contraction) ; [or what 
is the same thing, the further the point of a nerve 
which is stimulated is from the muscle, the stimulus 
being the same, the greater is the contraction. This 
led Pfliiger to his “avalanche-theory,” i.e., that 
the “ nerve-motion” increases in the nerve as it passes 
towards the muscles. This effect is explained, however, 
by the unequal excitability of different parts of the 
same nerve. Suppose a motor nerve in a nerve-muscle preparation of a frog be 
excited with the same strength of stimulus, e.g., by very weak induction shocks, 
F'g- 455- 
Scheme of Rutherford’s 
experiment. Sp. Cd., 
spinal cord; S, afferent 
nerve-fibre; M, muscles; 
El., electrodes at A, 
near cord, and at B 
near muscle. Sec. 324.] 
EXCITABILITY OF NERVES. 
681 
at a point near the muscle, so as to obtain just a feeble contraction of the 
muscle, the same strength of stimulus applied at a point further away from the 
muscle will cause a much greater contraction in the muscle. This is not due 
to the nerve-impulse gaining strength as it traverses a long stretch of nerve, 
but is due to the fact that the excitability is greater at parts of the nerve away 
from the muscle than at parts nearer the muscle, i.e., the excitability is 
greatest near the nerve-centre, probably because of the trophic influence 
of the nerve-cells of the spinal cord on the nerve-fibres.] 
[That the length of nerve is not the cause is shown by the following experi- 
ment of Rutherford on the reflex movements of a frog.] 
[Expose the whole length of, but do not divide, one sciatic nerve of a frog 
in which the brain is destroyed. The sciatic nerve contains both motor and 
sensory fibres. On stimulating the nerve at any part of its course the limb of 
the opposite side contracts reflexly. The reflex contraction, caused on stim- 
ulating the afferent or sensory nerve-fibres at A, is greater than that caused by 
the stimulation of the nerve at B. In the latter case a much longer stretch of 
nerve is traversed by the impulse than in the former, yet the reflex contraction 
is greater in the former]. 
According to Fleischl, all parts of the nerve are equally excitable for chemi- 
cal stimuli. Further, it is said that the higher placed parts of a nerve are more 
excitable only when the stimulating current passes in a descending direction ; 
the reverse is the case when the current ascends (Hermann). On stimulating 
a sensory nerve, Rutherford and Hallsten found that the reflex contraction was 
greater the nearer the stimulated point was to the central nervous system. 
Unequal Excitability in the same Nerve.—Nerve-fibres, even when 
functionally the same and included in the same nerve-trunk, are not all equally 
excitable. Thus, feeble stimulation of the sciatic nerve of a frog causes con- 
traction of the flexor muscles, while it requires a stronger stimulus to produce 
contraction of the extensors (Ritter, 1805, Rolletf). According to Ritter, the 
nerves for the flexors die first. 
Direct stimulation of the muscles in curarized animals shows that the flexors contract with 
a feebler stimulus (but also fatigue sooner) than the extensors; the pale muscles of the rabbit 
are also more excitable than the red. As a rule, poisons affect the flexors sooner than the ex- 
tensors. In some muscles some pale fibres are present, and they are more excitable than the red 
(Griitzner) ($ 298). If a frog’s nerve-muscle preparation be exposed to the action of ether, on 
strong stimulation of the sciatic nerve, flexion occurs (Griitzner, Bowdilch), but, if the current 
be made stronger, extension takes place. During deep ether-narcosis strong stimulation of the 
recurrent nerve causes dilatation, and with slight narcosis, narrowing of the glottis takes place; 
dilatation occurs on slight stimulation (Bowditch). The adductor muscle of the claw of a 
crayfish is relaxed under a weak stimulus, but it contracts when a strong stimulus is applied to 
it. The reverse is the case with the muscle which opens the claw (Biedermann). 
Unipolar Stimulation.—If one electrode of an induction apparatus be ap- 
plied to a nerve, it may act as a stimulus. Du Bois-Reymond has called this “uni- 
polar induction action.” It is due to the movement of the electrical current to 
and from the free ends of the open induction current at the moment of induc- 
tion. [Unipolar induction is more apt to occur with the opening than the clos- 
ing shock, because the former is more intense.] 
Electrical Stimuli on Muscle.—Upon muscle, electrical stimuli act 
quite as they do upon nerves. Electrical currents of very short duration have 
no effect upon muscles whose nerves are paralyzed by curare (Brucke), and the 
same is true of greatly fatigued muscles, or muscles about to die or greatly weak- 
ened by diseased conditions (§ 399). [The instantaneous induction-shock has 
a greater effect on the labile nerve than the slower less intense constant current. 
In the case of a muscle whose nerves are paralyzed by curare an induction shock 
may fail to produce a contraction when applied to the muscle, but the constant 682 
EXCITABILITY OF NERVES. 
[Sec. 324. 
current may do so. The induced shock must then be made much stronger in 
order to excite contraction. Sometimes in man, after paralysis of motor 
nerves, the constant current may excite contractions when the induced current 
fails. A strong constant current applied to a curarized muscle causes con- 
traction not only at make and break, but during the passage of the current the 
muscle also remains contracted (p. 614). Smooth muscle is more readily 
excited by the constant current than by an induced shock.] 
325. DIMINUTION OF THE EXCITABILITY.—DEGEN- 
ERATION AND REGENERATION OF NERVES.—1. The 
continuance of the normal excitability in the nerves of the body 
depends upon the maintenance of the normal nutrition of the nerves 
themselves and a due supply of blood. Insufficient nutrition causes, in 
the first instance, increased excitability, and if the condition be con- 
tinued the excitability is diminished (§ 339, I). 
When the physician meets with the signs of increased excitability of the nerves, 
under bad or abnormal conditions of nutrition, this is to be regarded as the beginning 
of the stage of decrease of the nerve-energy. Invigorating measures are required. 
If the terminal nervous apparatus be subjected to a temporary dis- 
turbance of its nutrition, the return of the normal nutritive process is 
Fig. 456. 
Degeneration and regeneration of nerves. A, sub-division of the myelin ; B, further disintegra- 
tion thereof (osmic acid staining); C, interruption of the axial cylinder, which is surrounded 
with the broken-up myelin ; D, accumulation of nuclei, with the remainder of the myelin in 
a spindle-shaped fibre; E, a new nerve-fibre, with a new sheath of Schwann, sn, within the 
old sheath of Schwann, sa; F, a new nerve-fibre passing in a curved course through an old 
nerve-fibre sheath. Sec. 325.] 
DEGENERATION OF NERVES. 
683 
heralded by a more or less marked stage of excitement. The more excitable 
the nervous apparatus, the shorter must be the duration of the disturbance of 
nutrition, e.g., cutting off the arterial blood-supply or interfering with the 
respiration. 
2. Fatigue of a Nerve.—Continued excessive stimulation of a nerve, 
without sufficient intervals of repose, causes fatigue of the nerve, and by ex- 
haustion rapidly diminishes the excitability. A nerve-trunk is more slowly 
fatigued than a muscle (Bernstein), but it recovers more slowly (§ 304). 
[Nerves of cold-blooded animals ( Widenskii) and mammals (Bowditch) may 
be tetanized for hours without becoming fatigued.] 
[To show that a muscle is much more rapidly fatigued than a nerve, Bernstein arranged 
two nerve-muscle preparations so that both nerves were tetanized simultaneously, but through 
one of the nerves a polarizing constant current was passed by means of non-polarizable elec- 
trodes (§ 328), so that the condition of anelectrotonus (§ 335) was set up in this nerve, and thus 
“blocked” the propagation of impulses to the corresponding muscle. Only one muscle, there- 
fore, was tetanized. Both nerves were continuously stimulated untd fatigue of the contracting 
muscle took place, and on breaking the polarizing current applied to the other nerve, the corre- 
sponding muscle at once became tetanic. Now, as both nerves were equally stimulated, and the 
muscle in connection with one nerve was fatigued, while the other muscle at once contracted, it 
is evident that a muscle is much more rapidly fatigued than a motor nerve. In sensory nerves, 
fatigue and recovery are analogous to the corresponding processes in motor nerves {£ernstein).] 
Recovery.—When a nerve recovers, at first it does so slowly, then more 
rapidly, and afterwards again more slowly. If recovery does not occur within 
half an hour after a frog’s nerve has been subjected to very long and intense 
stimulation, it will not take place at all. 
3. Continued inaction of a nerve diminishes, and may ultimately abolish 
the excitability. 
Thus the central ends, e. g., of a nerve of special sense, after removal of the sense-organ, or 
divided sensory nerves, after amputation of a limb, lose their excitability, although the nerves 
are still connected with the central nervous system, because the end-organs through which they 
were normally excited have been removed. 
4. Separation from their Nerve Centres.—The nerve-fibres remain in 
a condition of normal nutrition only when they are directly connected with 
their centre, which governs the nutritive processes within the nerve. If a 
nerve within the body be separated from its “ nutritive centre ” or 
“trophic centre ”—either by section of the nerve or compressing it—within 
a short time it loses its excitability, and the peripheral end undergoes fatty 
degeneration, which begins in four to six days in warm-blooded animals, and 
after a long time in cold-blooded ones (Joh. Muller). See also the changes of 
the excitability during this condition, the so-called “ Reaction of degenera- 
tion ” (§339). If the sensory nerve-fibres of the root of a spinal nerve be 
divided on the central side of the ganglion, the fibres on the peripheral side do 
not degenerate, for the ganglion is the trophic or nutritive centre for the sen- 
sory nerves; but the fibres still in connection with the cord degenerate 
( Waller). 
Wallerian Law of Degeneration.—Experiments on Spinal 
Nerves.—If a spinal nerve be divided, the peripheral part of the nerve 
and its branches, including the sensory and motor fibres, degenerate com- 
pletely (fig. 457, A), while the central parts of the nerve remain unaltered. If 
the anterior root of a spinal nerve alone be divided before it joins the pos- 
terior root, all the peripheral nerve-fibres connected with the anterior root 
degenerate (fig. 457, B), so that in the nerve of distribution only the motor 
fibres degenerate. The portion of the nerve-root which remains attached to 
the cord does not degenerate. If the posterior root alone be divided, be- 
tween the spinal cord and the ganglion, the effect is reversed, the part of the 684 
DEGENERATION OF NERVES. 
[Sec. 325. 
nerve-root lying between the section and the spinal cord degenerates, while 
the part of the nerve connected with the ganglion does not degenerate (fig. 
457, C). The central fibres degenerate because they are separated from the 
ganglion. If the ganglion be excised, or if separated, as in fig. 457, D, both 
the central and peripheral parts of the posterior root degenerate. These 
experiments of Waller show that the fibres of the anterior and posterior roots 
are governed by different centres of nutrition or “ trophic centres.” As 
the anterior root degenerates when it is separated from the cord, and the 
posterior when it is separated from its own ganglion, it is assumed that the 
trophic centre for the fibres of the anterior root lies in the multipolar nerve- 
cells of the anterior horn of the gray matter of the spinal cord, while that for 
the fibres of the posterior root lies in the cells of the ganglion placed on it. 
The nature of this supposed trophic influence is entirely unknown.] 
Traumatic and Fatty Degeneration.—Both ends of the nerve at the point of section 
immediately begin to undergo “ traumatic degeneration.” (In the frog on the 1st and 2d 
day.) After a time neither the myelin nor axis-cylinder is distinguishable (Schiff). According 
to Engelmann, this condition extends only to the nearest node of Ranvier, and afterwards the 
so-called “ fatty degeneration ” begins. The process of “ fatty ” degeneration begins simul- 
taneously in the whole peripheral portion; the white substance of Schwann breaks up into 
Fig. 457- 
Diagram of the roots of a spinal nerve, showing the effect of section (the black parts represent 
the degenerated parts). A, section of the nerve trunk beyond the ganglion; B, of the 
anterior root, and C, of the posterior; D, excision of the ganglion; a, anterior, p, 
posterior, root; ganglion. 
masses (fig. 456, A), just as it does after death, in microscopic preparations; afterwards the 
myelin forms globules and round masses (B), the axial-cylinder is compressed or constricted, 
and is ultimately broken across (C) in many places (7th day). The nerve-fibre seems to break 
up into two substances—one fatty, the other proteid in constitution, the fat being absorbed 
(S. Mayer'). The nuclei of Schwann’s sheath swell up and proliferate (D—until the 10th day). 
According to Ranvier, the nuclei of the interannular segments and their surrounding protoplasm 
proliferate, and ultimately interrupt the continuity of the axis-cylinder and the myelin. They 
then undergo considerable development with simultaneous disappearance of the medulla and 
axis-cylinder, or at least fatty substances formed by their degeneration, so that the nerve-fibres 
look like fibres of connective-tissue. [According to this view, the process is in part an active 
one, due to the growth of the nerve-corpuscles breaking up the contents of the neurilemma, 
which then ultimately undergo chemical degenerative changes.] According to Ranvier, 
Tizzoni, and others, leucocytes wander into the cut ends of the nerves, and also at Ranvier’s 
nodes, insinuating themselves into the nerve-fibres, where they take myelin into their bodies, 
and subject it to certain changes. [These cells are best revealed by the action of osmic acid, 
which blackens any myelin particles in their interior.] Degeneration also takes place in the 
motorial end-plates, beginning first in the non-medullated branches, then in the terminal 
fibrils, and lastly in the nerve-trunks (Gessler). 
Regeneration of Nerves.—In order that regeneration of a divided nerve may take place 
(Cruickshank, 1795)> the divided ends of the nerve must be brought into contact ($ 244). In 
man this is done by means of sutures. About the middle of the fourth week, small clear 
bands appear within the neurilemma, winding between the nuclei and the remains of the 
myelin (E). They soon become wider, and receive myelin with incisures, and nodes, and a 
sheath of Schwann (2d to 3d month—F). The regeneration process takes place in each Sec. 325.] 
REGENERATION OF NERVES. 
685 
interannular segment, while the individual segments unite end to end at the nodes of Ranvier 
(£ 312, I, 5). On this view, each nerve-segment of the fibre corresponds to a “ cell-unit ” 
{E. Neumann, Eichhorst). The same process occurs in nerves ligatured in their course. Several 
new fibres may be formed within one old nerve-sheath. The divided axis-cylinders of the 
central end of the nerve begin to'grow about the 14th day, until they meet the newly formed 
ones, with which they unite. 
[Primary and Secondary Nerve Suture.—Numerous experiments on animals and man 
have established the fact that immediate or primary suture of a nerve, after it is divided, either 
accidentally or intentionally, hastens reunion and regeneration, and accelerates the restoration 
of function. Secondary suture, i. e., bringing the ends together long after the nerve has been 
divided, has been practiced with success. Surgeons have recorded cases where the function 
was restored after division had taken place for 3 to 16 months, and even longer, and in most 
cases the sensibility was restored first, the average time being 2 to 4 weeks. Motion is 
recovered much later. The ends of the nerve should be stitched to each other with catgut, 
the muscles at the same time being kept from becoming atrophied by electrical stimulation and 
the systematic use of massage ($ 307). After suture of a nerve, conductivity is restored in the 
rabbit in 40 days, on the 31st in dogs, and 25th in fowls, but after simple division without 
suture, not till the 60th day in the rabbit. Transplantation of nerve does not succeed 
{Johnson). It has been practiced on several occasions on the human subject.] 
Union of Nerves.—The central end of a divided motor nerve may unite with the peripheral 
end of another, and still conduct impulses (Rava). [It is stated that sensory fibres will reunite 
with sensory fibres, and motor fibres with motor fibres, and the regenerated nerve will, in the 
former case, conduct sensory impulses, and the latter motor impulses. There is very con- 
siderable diversity of opinion, however, as to the regeneration or union of sensory with motor 
fibres. Paul Bert made the following experiment: He stitched the tail of a rat into the 
animal’s back, and after union had taken place, he cut the tail from the body at the root, so that 
the tail, as it were, grew out of the animal’s back, broad end uppermost. On irritating the end 
of the tail, which was formerly the root, the animal gave signs of pain. This experiment was 
devised by Bert to try to show that nerve-fibres can conduct impulses in both directions. One of 
two things must have occurred. Either the motor fibres, which normally carried impulses down 
the tail, now convey them in the opposite direction, and convey them to sensory fibres with which 
they have united; or the sensory fibres, which normally conducted impulses from the tip up- 
wards, now carry them in the opposite direction. If the former were actually what happened, it 
would show that nerve-fibres of different function do unite ($ 349). Reichert asserts that he 
has succeeded in uniting the hypoglossal with the vagus in the dog. According to Gessler the 
end-plate is the first to regenerate ($ 338).] 
Trophic Centres.—The regeneration of the nerve seems to take place 
under the influence of the nerve-centres, which act as their nutritive or 
trophic centres. Nerves permanently separated from these centres never 
regenerate. 
During the regeneration of a mixed nerve, sensibility is restored first, 
subsequently voluntary motion, and lastly, the movements of the muscles, 
when their motor nerves are stimulated directly (Schiff, Erb, v. Ziemssen). 
Wallerian Method of Investigation.—As the peripheral end of a nerve 
undergoes degeneration after section, we use this method for determining the 
course of nerve-fibres in a complex arrangement of nerves. The course of 
special nerve-fibres may be ascertained by tracing the degeneration tract 
(Waller). If after section, reunion or regeneration of a motor nerve does 
not take place, the muscle supplied by this nerve ultimately undergoes fatty 
degeneration. 
5. Modifying Conditions.—Under the action of various operations, e. g., 
compressing a nerve [so as not absolutely to sever the physiological continuity], 
it has been found that voluntary impulses or stimuli applied above the com- 
pressed spot give rise to impulses which are conducted through the nerve, and 
in the case of a motor nerve, cause contraction of the muscles, whilst the 
excitability of the parts below the injured spot is greatly diminished (Schiff). 
In a similar manner, it is found that the nerves of animals poisoned with C02, 
curare, or coniin, sometimes even the nerves of paralyzed limbs in man, are 
not excitable to direct stimuli, while they are capable of conducting impres- 
sions coming from the central nervous system (Duchenne). The injured part 686 
DEATH OF A NERVE. 
[Sec. 325. 
of the nerve, therefore, loses its excitability sooner than its power of conduct- 
ing an impulse. 
6. Certain poisons, such as veratrin, at first increase the excitability of the 
nerves, and afterwards abolish it; with some other poisons, the abolition of 
the excitability passes off very rapidly, e. g., curare. Conium, cynoglossum, 
iodide of methylstrychnin, and iodide of sethylstrychnin have a similar action. 
If the nerve or muscle of a frog be placed in a solution of the poison, we obtain a different 
effect from that which results when the poison is injected into the body of the animal. Atropin 
diminishes the excitability of a nerve-muscle preparation of the frog without causing any 
previous increase, while alcohol, ether, and chloroform increase and then diminish the excita- 
bility (Mommsen). 
7. Ritter Valli Law.—If a nerve be separated from its centre, or if the 
centre die, the excitability of the nerve is increased; the increase of excitability 
begins at the central end, and travels towards the periphery—the excitability 
then falls until it disappears entirely. This process takes place more rapidly 
in the central than in the peripheral part of the nerve, so that the peripheral 
end of a nerve separated from its centre remains excitable for a longer time 
than the central end. 
The rapidity of the transmission of nerve impulses in a nerve is increased when the ex- 
citability is increased, but it is lessened when the excitability is diminished ($ 337). In the latter 
condition, an electrical stimulus must last longer in order to be effective ; hence rapid induction 
shocks may not produce any effect. 
The law of contraction also undergoes some modification in the different stages of the changes 
of excitability ($ 336, II). 
8. Excitable Points.—Many nerves are more excitable at certain parts of 
their course than at others, and the excitability may last longer at these parts. 
One of these parts is the upper third of the sciatic nerve of a frog, just where 
a branch is given off (Budge). 
The motor and sensory fibres of the upper third of the sciatic nerve of a frog (p. 681) are 
more excitable for all stimuli than the lower parts ( Griitzner and Elpon). Whether this arises 
from injury during preparation (a branch is given off there), or is due to anatomical conditions, 
e. g., more connective-tissue and more nodes in the lower part of the sciatic, is undetermined 
(<Clara Halperson). 
This increased excitability may be due to injury to the nerve in preparing it for experiment. 
After section or compression of a nerve, all electrical currents employed to stimulate the nerve 
are far more active when the direction of the current passes away from the point of injury than 
when they pass in the opposite direction. This is due to the fact that the current produced in 
the nerve after the lesion is added to the stimulation current (§ 331, 5). Even in intact nerves 
—sciatic of a frog—where the nerve ends at the periphery or at the centre, or where large 
branches are given off, there are points which behave in the same way as those points where a 
lesion has taken place (Griitzner and Moschner). 
Death of a Nerve.—In a dead nerve the excitability is entirely abolished, 
death taking place, according to the Ritter-Valli law, from the centre towards 
the periphery. The reaction of a dead nerve has been found by some ob- 
servers to be acid (§ 322). 
The functions of the brain cease immediately death takes place, while the vital functions of 
the spinal cord, especially of the white matter, last for a short time; the large nerve-trunks 
gradually die, then the nerves of the extensor muscles, those of the flexors after three to four 
hours; while the sympathetic fibres retain their excitability longest, those of the intestine even 
for ten hours (Onimus). Compare § 395. The nerves of a dead frog may remain excitable for 
several days, provided the animal be kept in a cool place. Sec. 326.] 
ELECTRO-MOTIVE FORCE. 
687 
Electro-Physiology. 
Before beginning the study of electro-physiology, the student ought to read 
and study carefully the following short preliminary remarks on the physics of 
this question : — 
326. PHYSICAL—THE GALVANIC CURRENT—RHEOCORD.-i. Electro- 
motive Force.—If two of the under-mentioned bodies be brought into direct contact, in one of 
them positive electricity, and in the other negative electricity can be detected. The cause of 
this phenomenon is the electro-motive force. The electro-motive substances may be arranged 
in a series of the first class, so that if the first-mentioned substance be brought into contact 
with any of the other bodies, the first substance is negatively, the last positively, electrified. This 
series is : carbon, platinum, gold, silver, copper, iron, tin, lead, zinc, -]-. 
The Electro-motive Force (E.M.F.) produced by the contact of two of these bodies is greater 
the further the bodies are apart in the series. The contact of the bodies may take place at one 
or more points. If several of the bodies of this series be arranged in a pile, the electrical tension 
thereby produced is just as great as if the two extreme bodies were brought into contact, the 
intermediate ones being left out. 
2. The nature of the two electricities is readily determined by placing one of the bodies of 
the series in contact with a fluid. If zinc be placed in pure or acidulated water, the zinc is 
-)- (positive) and the water — (negative). If copper be taken instead of zinc, the copper is -f- 
but the fluid—. Experiment shows that those metals, in contact with fluid, are negatively 
electrified most strongly which are most acted on chemically by the fluid in which they are 
placed. Each such combination affords a constant difference of tension or potential. The 
tension [or power of overcoming resistance] of the amount of electricity obtained from both 
bodies depends upon the size of the surfaces in contact. The fluids, e.g., the solutions of acids, 
alkalies, or salts are called exciters of electricity of the second class. They do not form among 
themselves a definite series with different tensions. When placed in these fluids, the metals 
lying next the end of the above series, especially zinc, are most strongly electrified negatively, 
and to a less extent those lying near the — end of the series. 
3. Galvanic Battery.—If two different exciters of the first class be placed in fluid, without 
the bodies coming into contact, e. g., zinc and copper, the projecting end of the (negative) zinc 
shows free negative electricity, while the free end of the (positive) copper shows free positive 
electricity. Such a combination of two electro-motors of the first class with an electro-motor 
of the second class is called a galvanic battery. [A battery is an arrangement for producing 
electricity. A single apparatus constitutes a cell or element, several elements form a battery.] 
As long as the two metals in this fluid are kept separate, the circuit is said to be broken or open, 
but as soon as the free projecting ends of the metals are connected outside the fluid, e. g., by a 
copper wire, the circuit or current is made or closed, and a galvanic or constant current of 
electricity is obtained. The galvanic current has resistance to encounter in its course, which is 
called “ conduction resistance ” (W). It is directly proportional—(1) to the length (/) of the 
circuit; (2) and with the same length of circuit, inversely as the section (y) of the same ; and 
(3) it also depends on the molecular properties of the conducting material (specific conduction 
resistance = s), so that— 
the conduction resistance W = (j /) : q. 
The resistance to conduction increases with the increase of the temperature of the metals, but 
diminishes under similar conditions with fluids. 
Ohm’s Law.—The strength of a galvanic current (C), or the amount of electricity passing 
through the closed circuit, i.e., the current strength, is proportional to the electro-motive force 
(E)—or the electrical tension or potential, but inversely proportional to the total resistance to 
conduction (R)— 
Electro-motive force 
Ohm’s Law (1827) -— Current = n • 
' '' 1 otal resistance 
E E 
C — or E — C X R or R = 
The total resistance to conduction, however, in a closed circuit is composed of (i) the resist- 
ance outside the battery (“ extraordinary resistance ”); and (2) the resistance within the battery 
itself (“ essential resistance”). The specific resistance to conduction is very variable in different 688 
RHEOCORDS. 
[Sec. 326. 
substances; it is relatively small in metals (e.g., for copper = I, iron = 6.4, German silver = 
12), but very great in fluids (e.g., for a concentrated solution of common salt 6,515,000, for a 
concentrated solution of copper sulphate 10,963,600). 
Conduction in Animal Tissues.—The resistance to the conduction of electricity is 
also very great in animal tissues, almost a million times greater than in metals. When a con- 
stant current is applied to the skin so as to traverse the body, the resistance diminishes because 
of the conduction of water in the epidermis under the action of the constant current (§ 289), and 
the congestion of the cutaneous blood-vessels in consequence of the stimulation. But the resist- 
ance varies in different parts of the skin, the least being in the palm of the hand and sole of the 
foot. The chief seat of the resistance is the epidermis, for after its removal by means of a blister, 
the resistance is greatly diminished. Dead tissue, as a rule, is a worse conductor than living 
tissues (Jolly). When the current is passed transversely to the direction of the fibres of a 
muscle, the resistance is nearly nine times as great as when the current passes in the direction 
of the fibres—a condition which disappears in rigor mortis (Hermann). In nerves, the resist- 
ance longitudinally is two and a half million times greater than in mercury, transversely about 
twelve million times greater (Hermann). Tetanus and rigor mortis diminish the resistance in 
muscle (du Bois-Reymond). According to Rosenthal, the conduction is the same in a dead as 
in a living muscle, both in a longitudinal and transverse direction. Charcot and Vigouroux have 
made the remarkable observation that in cases of Basedow’s disease ($ 371) there is a diminu- 
tion of the electrical resistance in the body. 
Deductions from Ohm’s Law.—It follows from Ohm’s law that—I. If there is very great 
resistance to the current outside the battery [»'.<?., between the electrodes], as is the case when a 
nerve or a muscle lies on the electrodes, the strength of the current can only be increased by 
increasing the number of the electro-motive elements. II. When, however, the extraordinary 
resistance is very small compared with that within the battery itself, the strength of the current 
cannot be increased by increasing the number of the elements, but only by increasing the surfaces 
of the plates in the battery. 
[The following system of electrical measurements was adopted in 1881. Some of the units of 
measurement are of importance physiologically. They are :— 
The Ohm, or the unit of resistance, is equal to the resistance of a column of pure mercury in 
a closed glass tube 1.06 metre long, and 1 square mm. in sectional area at o° C. 
The Ampere, or the unit of current, is the strength of current required to produce 0.172 c.c. 
of O and H (i. e., decompose water) in 1 sec. at o° C. and 760 mm. pressure. 1 milliampere = 
T(Jo7 amP^re- An ampere is approximately equal to the current of a Daniell’s cell through an 
ohm. 
The Volt, or unit of electro-motive force, is equal to about E.M.F. of a DanielPs cell. The 
relation between these is that 1 ampere = I volt: I ohm.] 
Strength and Intensity.—We must carefully distinguish the strength of the current from its 
intensity. As the same amount of electricity always flows through any given transverse section 
of the circuit, then, if the size of the transverse section of the circuit varies, the electricity must be 
of greater intensity in the narrower parts, and it is evident that the intensity will be less where 
the transverse section is greater. Let C = the strength of the current, and q the trans- 
verse section of the given part of the circuit, then the intensity (d) at the latter part is 
d — C : q. 
If the galvanic current passing from the positive pole of a battery is divided into two or more 
streams, which are again reunited at the other pole, then the sum of the strength of all the 
streams is equal to the strength of the undivided stream. If, however, the different streams are 
different as regards length, section, and material, then the strength of the current passing in each 
of the streams is inversely proportional to the resistance to the conduction. 
Du Bois-Reymond’s Rheocord.—This instrument, constructed on the principle of the 
“ secondary,” or “ short circuit,” enables us to graduate the strength of a galvanic current 
to any required degree, for the stimulation of nerve and muscle. From the two poles (fig. 458, 
a, b) of a constant battery, there are two conducting wires (a, c, and d, b), which go to the nerve 
of a frog’s nerve-muscle preparation (F). The portion of nerve (c,d) introduced into this circuit 
(a, c, d, b) offers very great resistance. The second stream or secondary circuit (a A, b B) 
conducted from a and b passes through a thick brass plate (A, B), consisting of seven pieces of 
brass (1 to 7) placed end to end, but not in contact. They ;an all, with the exception of 1 and 
2, be made to form a continuous conductor by placing in the spaces between them the brass 
plugs (Sj to S5). Evidently, with the arrangement shown in fig. 458, only a minimal part of the 
current will passthrough the nerve (c, d), owing to the very great resistance in it, while by far 
the greatest part will pass through the good conducting medium of brass (A, L, B). If new 
resistance be introduced into this circuit, then the a, c, d, b stream will be strengthened. This 
resistance can be introduced into the latter circuit by means of the thin wires marked I a, I b, I c, 
II, V, X. Suppose all the brass plugs from Sx to S5 to be removed, then the current entering at 
A must traverse the whole system of thin wires. Thus, there is more resistance to the passage Sec. 326.] 
689 
GALVANOMETER. 
of this current, so that the current through the nerve must be strengthened. If only one brass 
plug be taken out, then the current passes through only the corresponding length of wire. The 
resistances offered by the different lengths of wire from I a 
to X are so arranged that I a, I b, and I c each represents 
a unit of resistance; II, double; V, five times; and X, 
ten times the resistance. The length of wire, I «,can also 
be shortened by the movable bridge (L) [composed of a 
small tube filled with mercury, through which the wires 
Fig. 458.—Scheme of du Bois-Reymond’s rheocord. Fig. 459.—Scheme of the galvanometer. 
N, N, astatic needles suspended by the silk fibre, G; P, P, non-polarizable electrodes, con- 
taining zinc sulphate solution, s, and pads of blotting-paper, b, covered with clay, t, t, on 
which the muscle, M, is placed; II and III, arrangement of the muscle on the electrodes; 
IV, non-polarizable electrodes; Z, zinc wire; K, cork; a, zinc sulphate solution; t, t, clay 
points. 
Fig. 458. 
Fig- 459- 
pass], the scale (x,y) indicating the length of the resistance wires. It is evident that, by means of 
the bridge, and by the method of using the brass plugs, the apparatus can be graduated to yield 
very variable currents for stimulating nerve or muscle. When the bridge (L) is pushed hard 
up to 1 and 2, the current passes directly from A to B, and not through the thin wires 
(! <*)• . 
The rheostat is another instrument used to vary the resistance of a galvanic current 
(Wheatstone). 
327. ACTION OF THE GALVANIC CURRENT ON A MAGNETIC 
NEEDLE—GALVANOMETER.—In 1822, Oersted of Copenhagen found that a mag- 
netic needle, suspended in the magnetic meridian, was deflected by a constant current of 
electricity passed along a wire parallel to it. [The side to which the north pole is deflected 
depends upon the direction of the current, and whether it passes above or below the needle.] 
Ampere’s Rule.—Ampere has given a simple rule for determining the direction. If an 
observer be placed parallel to and facing the needle, and if the current be passing from his feet 
to his head, then the north pole of the needle will always be deflected to the left, and the south 
pole in the opposite direction. The effect exerted by the constant current acts always in a 
direction towards the so-called electro-magnetic plane. The latter is the plane passing through 
the north pole of the needle, and two points in the straight wire running parallel with the 
needle. The force of the constant current, which causes the deflection of the magnetic needle, 
is proportional to the sine of the angle between the electro-magnetic plane and the plane of 
vibration of the needle. 
Multiplicator or Galvanometer.—The deflection of the needle caused by the constant cur- 
rent may be increased by coiling the conducting wire many times in the same direction on a 690 
GALVANOMETER ELECTROLYSIS. 
[Sec. 327. 
rectangular frame, or merely around and in the same direction as the needle [provided that each 
turn of the wire be properly insulated from the other]. An instrument constructed on this prin- 
ciple is called a multiplicator, multiplier, or galvanometer. The greater the number of turns 
of the wire the greater is the angle of deflection of the needle, although the deflection is not 
directly proportional, as the several turns or coils are not at the same distance from, or in the 
same position as, the needle. By means of the multiplier we may detect the presence [and also 
the amount and direction] of feeble currents. Experience has shown that, when great resistance 
(as in animal tissues) is opposed to the weak galvanic currents, we must use a very large number 
of turns of thin wire round the needle. If, however, the resistance in the circuit is but small, 
e.g., in thermo-electrical arrangements, a few turns of a thick wire round the needle are sufficient. 
The multiplier may be made more sensitive by weakening the magnetic directive force of the 
needle, which keeps it pointing to the north. 
Galvanometer and Astatic Needles.— In the multiplier of Schweigger, used for physio- 
logical purposes, the tendency of the needle to point to the north is greatly weakened by using 
the astatic needles of Nobili. [A multiplier or 
galvanometer with a single magnetic needle al- 
ways requires comparatively strong currents to 
deflect the needle The needle is continually 
acted upon by the directive magnetic influence of 
the earth, which tends to keep it in the magnetic 
meridian, and, as soon as it is moved out of the 
magnetic meridian, the directive action of the 
earth tends to bring it back. Hence, such a 
simple form of galvanometer is not sufficiently sen- 
sitive for detecting feeble currents. In 1827, 
Nobili devised an astatic combination of needles, 
whereby the action of the earth’s magnetism was 
diminished.] Two similar magnetic needles are 
united by a solid light piece of horn [or tortoise 
shell], and are so arranged that the north pole of the one is placed over or opposite to the south 
pole of the other (fig. 459). 
[Fig. 460 shows two magnetic needles with their magnetic axes parallel and their similar 
poles pointing opposite ways, forming what is called an astatic pair, or astatic needles. As 
the earth’s attractive force on the N. pole of one needle is exactly counterbalanced by its repelling 
force on the S. pole of the other needle, there is no directive force to cause the combination to 
set in any particular position.] 
[If both needles are equally magnetized, then the earth’s influence on the needle is neutralized, 
so that the needles no longer adjust themselves in the magnetic meridian; hence, such a system 
is called as.tatic (statum, standing).] As it is impossible to make both needles of absolutely 
equal magnetic strength, one needle is always stronger than the other. The difference, however, 
must not be so great that the stronger needle points to the north, but only that the freely 
suspended system of needles forms a certain angle with the magnetic meridian, into which posi- 
tion the system always swings after it is deflected from this position. This angular deviation of 
the astatic system towards the magnetic meridian is called the “ free deviation.” The more 
perfectly an astatic condition is reached, the nearer does the angle formed by the direction of the 
free deviation with the magnetic meridian become a right angle. The greater, therefore, the 
astatic condition, the fewer vibrations will the astatic system make in a given time, after it has 
been deflected from its position. The duration of each single vibration is also very great. [Hence, 
when using a galvanometer, and adjusting its needle to zero, if the magnets dance about or move 
quickly, then the system is not sensitive, but a sensitive condition of the needles is indicated by 
a slow period of oscillation.] 
In making a galvanometer, the turns of the wire must have the same direction as the needles. 
In Nobili’s galvanometer, as improved by du Bois-Reymond, the upper needle swings above a 
card divided into degrees (fig. 459), on which the extent of its deflection may be read off. Even 
the purest copper wire used for the coils round the needles always contain a trace of iron, which 
exerts an influence upon the needles. Hence, a small fixed directive or compensatory magnet (r) 
is placed near one of the poles of the upper needle to compensate for the action of the iron on 
the needles. 
328. ELECTROLYSIS, POLARIZATION, BATTERIES.—Electrolysis.—Every 
galvanic current which traverses a fluid conductor causes decomposition or electrolysis of the 
fluid. The decomposition-products, called “ ions,” accumulate at the poles (electrodes) in the 
fluid, the positive pole (-j- ) being called the anode [ar>d, up, odof, a way], the negative pole 
( — ) the cathode (/card, down, odof, a way). The anions accumulate at the anode and the 
kations at the cathode. 
Transition Resistance.—When the decomposition-products accumulate upon the electrodes 
Asiatic needles. 
Fig. 460. Sec. 328.] 
GALVANIC BATTERIES. 
by their presence they either increase or diminish the resistance to the electrical current. This 
is called transition resistance. If the resistance within the battery is thereby increased, the 
transition resistance is said to be positive ; if diminished, negative. 
Galvanic Polarization.—The ions accumulated on the electrodes may also vary the strength 
of the current, by developing between the anions and kations a new galvanic current, just as 
occurs between two different bodies connected by a fluid medium. This phenomenon is called 
galvanic polarization. Thus, when water is decomposed, the electrodes being of platinum, 
the oxygen (negative) accumulates at the -f- pole, and the hydrogen (positive) at the — pole. 
Usually the polarization current has a direction opposite to the original current; hence, we speak 
of negative polarization. When the two currents have the same direction, positive polari- 
zation obtains. Of course, transition resistance and polarization may occur together during 
electrolysis. 
Test of Polarization.—Polarization, when present, may be so slight as not to be visible to 
the eye, but it may be detected thus: After a time exclude the primary source of the current, 
especially the element connected with the electrodes, and place the free projecting end of the 
electrodes in connection with a galvanometer, which will at once indicate, by the deflection of 
its needle, the presence of even the slightest polarization. [Polarization of Electrodes.— 
By means of copper electrodes, pass a constant current of electricity through a nerve of a nerve- 
muscle preparation, introducing a key in the circuit. After three minutes remove the battery, 
and open and close the key; on doing so the muscle will contract, owing to polarization of the 
electrodes.] 
Secondary Decompositions.—The ions excreted during electrolysis' cause, especially at 
their moment of formation, secondary decompositions. With platinum electrodes in a solution of 
common salt, chlorine accumulates at the anode and 
sodium at the cathode; but the latter at once decom- 
poses the water, and uses the oxygen of the water to 
oxidize itself, while the hydrogen is deposited second- 
arily upon the cathode. The amount of polarization 
increases, although 
only to a slight ex- 
tent,with the strength 
of the current, while 
it is nearly propor- 
tional to the increase 
of the temperature. 
Non - polarizable 
Electrodes.— The 
attempts to get rid o: 
polarization, which 
obviously must very 
soon alter the 
strength of the gal- 
vanic current, have 
led to the discovery 
of two important ar- 
rangements, viz., the 
construction of con- 
stant galvanic 
batteries, and non- 
polarizable elec- 
trodes (du Bois 
Reymond). 
Constant Batteries, Elements, or Cells.—A perfectly constant element produces a con- 
stant current, i. <?., one remaining of equal strength, by the ions produced by the electrodes 
being got rid of the moment they are formed, so that they cannot give rise to polarization. For 
this purpose, each of the substances from the tension series used is placed in a special fluid 
(§ 326), both fluids being separated by a porous septum (porcelain cylinder). 
Grove’s cell, or platinum-zinc cells, has two metals and two fluids (figs. 461, 462, 463). 
The zinc is in the form of a roll placed in dilute sulphuric acid [1 acid to 7 of water, which is 
contained in a glass, porcelain, or ebonite vessel]. The platinum is in contact with strong nitric 
acid, [which is contained in a porous cell placed inside the roll of zinc.] The O, formed by 
the electrolysis and deposited on the zinc plate, forms zinc oxide, which is at once dissolved by 
the sulphuric acid. The hydrogen on the platinum unites at once with the nitric acid, which 
gives up O and forms nitrous acid and water, thus— 
Fig. 462. 
Fig. 461. 
Outside view of a Grove’s cell, 
showing platinum (p) and zinc 
plates (z) as well as porous pot 
(v) of next cell in series. 
Large Grove’s cell. 
[H2 + HNO, = HNO, + H.O.] • 
[Platinum is the -j- pole, and zinc the —.] 692 
GALVANIC BATTERIES. 
[Sec. 328. 
[Grove’s battery is very powerful, but the nitrous fumes are very disagreeable and irritating • 
hence these elements should be kept in a special well-ventilated recess in the laboratory, in an 
evaporating chamber, or under glass. The fumes also attack instruments. The E. M. F. is 
about 2 volts.] 
The zinc plate in this battery is generally cast in the form of a U and is generally placed in 
an ebonite vessel (EV) (fig. 463). 
Bunsen’s cell, or carbon-zinc cell (fig. 464), is similar to Grove’s, only a piece of com- 
pressed carbon is substituted for the platinum in contact with the nitric acid. The E. M. F. = 
1.9 volt. 
[The carbon is the -(- pole, the zinc the —.] 
[Daniell’s cell consists of an outer vessel of glass or earthenware, and sometimes of metallic 
copper, filled with a saturated solution of cupric sulphate (fig. 465). A roll of copper, per- 
forated with a few holes, is placed in the copper solution, and in order that the latter be kept 
saturated, and to supply the place of the copper used up by the battery when in action, there is 
a small shelf on the copper roll, on which are placed crystals of cupric sulphate. A porous 
earthenware vessel containing zinc in contact with dilute sulphuric acid (1 : 7) is placed within 
Fig. 463.—Vertical section through a Grove’s cell; p, porous pot; EV, ebonite vessel. 
Fig. 464.—Outside view of a Bunsen cell. 
Fig. 463. 
Fig. 464. 
the copper cylinder. When the circuit is completed, the zinc is acted on, zinc sulphate being 
formed, and hydrogen liberated. The hydrogen in statu nascendi passes through the porous 
cell, reduces the cupric sulphate to metallic copper, which is precipitated on the copper cylinder, 
so that the latter is always kept bright and clean. The liberated sulphuric acid replaces that in 
contact with the zinc. Owing to the absence of polarization, the Daniell is one of the most 
constant batteries, and is generally taken as the standard of comparison. The E. M. F. = 
1.072 volt.] 
[The copper is the -(- pole, and zinc the —.] 
[Smee’s cell contains only one fluid, viz., dilute sulphuric acid (1 : 7), in which the two 
metals, zinc and platinum, or zinc and platinized silver, are placed. The E. M. F. = .47 volt. 
The platinum is the -)- pole, and zinc the —.] 
[Grennet’s or the Bichromate cell consists of one plate of zinc and two plates of com- 
pressed carbon in a fluid, containing bichromate of potash, sulphuric acid, and water. The 
fluid consists of 1 part of potassium bichromate dissolved in 8 parts of water, to which one part 
of sulphuric acid is added. Measure by weight. The cell consists of a wide-mouthed glass 
bottle (fig. 466); the carbofls remain in the fluid, while the zinc can be raised or depressed. Sec. 328.] 
GALVANIC BATTERIES. 
693 
When not in action, the zinc, which is attached to a rod (B), is lifted out of the fluid. It is not 
a very constant battery. When in action, the zinc is acted on by the sulphuric acid, hydrogen 
being liberated, which reduces the bichromate of potash. The 
E.M.F. = 1.8 volt. 
The carbon is the -f- pole, and the zinc the —.] 
[Leclanche’s cell (fig. 467) consists of an outer glass vessel 
containing zinc in a solution of ammonium chloride, while the 
porous cell contains compressed carbon in a fluid mixture of black 
oxide of manganese and carbon. It is most frequently used for 
electric bells, as its feeble current lasts for a long time. The 
E. M. F. = 1.48 volt. 
The carbon is the -j- pole, and the zinc the —.] 
[Noe-Dorffel Thermo-Electric Battery.—This consists of a 
number of thermo-electric junctions of German silver and an alloy 
of antimony and zinc arranged concentrically. The apparatus is 
heated by means of a gas flame or a Bunsen burner. Twenty ele- 
ments in a battery give a current equal to about 1.25 volts. The — pole is connected with the 
German silver.] 
[Storage Cell.—If a dynamo be available storage cells may be used. They require to be 
charged from time to time, from the 
dynamo.] 
[The kind of electricity 
yielded by all these batteries is 
DanielFs cell. 
Fig. 465. 
Fig. 466.—Grennet’s cell. A, glass vessel; K, K, carbon; Z, zinc; D, E, binding screws for 
the wires; B, rod to raise the zinc from the fluid; C, screw to fix B. Fig. 467.— 
Leclanche’s cell. A, outer vessel; T, porous cylinder, containing K, carbon; B, binding 
screw; Z, zinc; C, binding screw of negative pole. 
Fig. 466. 
Fig. 467. 
spoken of as the constant current, or voltaic, or galvanic electricity.] 
[When a number of cells are used, and it is desired to obtain a strong current of electricity, 
the cells are joined in series (fig. 468), i.e., the positive terminal of one cell is joined to the 
negative of the next, and so on. A current of higher potential is obtained if several elements 694 
NON-POLARIZABLE ELECTRODES. 
[Sec. 328. 
of small size are used, but if a large quantity of electricity is required, as for thermo-cautery, 
use elements of large size.] 
Non-polarizable Electrodes.—If a constant current be applied to moist animal tissues, 
e.g., nerve or muscle, by means of ordinary electrodes composed either of copper or platinum, 
of course electrolysis must occur, and in consequence thereof polarization takes place (p. 691). 
In order to avoid this, non-polarizable 
electrodes (figs. 459, 469) are used. 
Such electrodes are made by taking two 
pieces of carefully amalgamated, pure 
zinc wire (2, 2), and dipping these in a 
saturated solution of zinc sulphate 
contained in tubes (a, a), whose lower 
ends are closed by means of modeller’s 
clay ((, i), moistened with 0.6 per cent, 
normal saline solution or water. The 
contact of the tissues with these elec- 
trodes does not give rise to polarity. 
[The brush electrodes of v. Fleischl 
are very serviceable (fig. 470). The 
lower end of the glass tube is plugged 
with a camel-hair pencil, moistened with 
modeller’s clay, otherwise the arrangement is the same as shown in fig. 459, IV.] 
Arrangement for the Muscle- or Nerve-Current.—In order to investigate the electrical 
currents of nerve or muscle, the tissue must be placed on non-polarizable electrodes, 
which may either be one of the forms described above or the original form used by du Bois- 
Reymond (fig. 459). The last consists of two zinc troughs (/,/), thoroughly amalgamated 
inside, insulated on vulcanite, and filled with a saturated solution of zinc sulphate (x, s). In 
Two simple voltaic cells joined in series. C, copper; 
Z, zinc. 
Fig. 468. 
Fig. 469. 
Fig. 470. 
Fig. 469.—Non-polarizable electrode of du Bois-Reymond. Z, zinc; H, movable support; C, 
clay point—the whole on a universal joint. Fig. 470.—Brush electrodes of v. Fleischl. 
each trough is placed a thick pad or cushion of white blotting-paper (b, b) saturated with the 
same fluid [deriving cushions]. [The cushion consists of many layers, almost sufficient to 
fill the trough, and they are kept together by a thread. To prevent the action of the zinc sul- 
phate upon the tissue, each cushion is covered with a thin layer of modeller’s clay (/, t), moistened 
with 0.6 per cent, saline solution, which is a good conductor [clay guard]. The clay guard 
prevents the action of the solution upon the tissue. Connected with the electrodes are a pair of 
binding screws whereby the apparatus is connected with the galvanometer (fig. 459). 
[Reflecting Galvanometer.—The form of galvanometer, used in this country for physio- 
logical purposes, is that of Sir William Thomson (fig. 471). In Germany, Wiedemann’s form is 
more commonly used. In Thomson’s instrument, the astatic needles are very light, and con- 
nected to each other by a piece of aluminium, and each set of needles is surrounded by a sepa- 
rate coil of wire, the lower coil (/) winding in a direction opposite to that of the upper (u). A 
small, round, light, slightly concave mirror is fixed to the upper set of needles. The needles 
are suspended by a delicate silk fibril, and they can be raised or lowered as required by means of 
a small milled head. When the milled head is raised, the system of needles swings freely. Sec. 328.] 
REFLECTING GALVANOMETER. 
695 
The coils are protected by a glass shade, and the whole stands on a vulcanite base, which 
is levelled by three screws (j, j). On a brass rod (3) is a 
feeble magnet (m), which is used to give an artificial meridian. 
The magnet (m) can be raised or lowered by means of a 
milled head.] 
[Lamp and Scale.—When the instrument is to be used, 
place it so that the coils face east and west. At 3 feet distant 
from the front of the galvanometer, facing west, is placed the 
lamp and scale (fig. 472). There is a small vertical slit in 
front of the lamp, and the image of this slit is projected on the 
mirror attached to the upper needles, and by it is reflected on 
to the paper scale fixed just above the slit. The spot of light 
is focussed at zero by means of the magnet, m. The needles 
are most sensitive when the oscillations occur slowly. The 
sensitiveness of the needles can be regulated by means of the 
magnet. In every case the instrument must be quite level, 
and for this purpose there is a small spirit-level in the base of 
the galvanometer.] 
[Shunt.—As the galvanometer is very delicate, it is con- 
venient to have a shunt to regulate to a certain extent the 
amount of electricity transmitted through the galvanometer 
(fig. 473). The shunt consists of a brass box containing coils 
of German silver wire, and is constructed on the same 
principle as resistance coils of the rheocord (§ 326). On 
the upper surface of the box are several plates of brass 
separated from each other, like those of the rheocord, but 
which can be united by brass plugs. The two wires coming 
from the electrodes are connected with the two binding 
screws, and from the latter two wires are led to the outer 
two binding screws of the galvanometer. By placing a plug 
between the brass plates attached to the two binding screws 
in the figure, the current is short-circuited. On removing 
both plugs, the whole of the current must pass through the 
galvanometer. If one plug be placed between the central disc 
of brass and the plate marked (the other being left out), 
then TV of the current goes through the galvanometer and -Aths 
to the electrodes. If the plug be placed as shown in the figure 
opposite then of the current goes to the galvanometer, 
while T9ff9(yths are short-circuited. If the plug be placed oppo- 
site only xcsW1*1 Part g°es through the galvanometer.] 
Internal Polarization of Moist Bodies.—Nerves and muscular fibres, the juicy parts of 
vegetables and animals, fibrin, and other similar bodies possessing a porous structure filled 
with fluid, exhibit the phenomena of polarization when sub- 
jected to strong currents—a condition termed internal polari- 
zation of moist bodies by du Bois-Reymond. It is assumed 
that the solid parts in the interior of these bodies which are 
better conductors produce electrolysis of the adjoining fluid, 
just like metals in contact with fluid. The ions produced by 
the decomposition of the internal fluids give rise to differences 
of potential, and thus cause internal polarization (£ 333). 
Cataphoric Action.—If the two electrodes from a galvanic 
battery be placed in the two compartments of a fluid, separated 
from each other by a porous septum, we observe that the fluid 
particles pass in the direction of the galvanic current, from 
the -\- to the — pole, so that after some time the fluid in the 
one half of the vessel increases, while it diminishes in the 
other. The phenomena of direct transference were called by 
du Bois-Reymond the cataphoric action of the constant current. 
The introduction of dissolved substances through the skin by 
means of a constant current depends upon this action (§ 289), 
and so does the so-called Porret’s phenomenon in living 
muscle ($ 293, 1, !?). 
External Secondary Resistance.—This condition also depends on cataphoric action. If 
the copper electrodes of a constant battery be placed in a vessel filled with a solution of cupric 
sulphate, and from each electrode there project a cushion saturated with this fluid, then, on 
Fig. 471. 
Thomson’s reflecting galvano- 
meter. u, upper, /, lower 
coil; s, s, levelling screws; m, 
magnet, on a brass support, b. 
Fig. 472. 
Lamp and scale for Thomson's 
galvanometer. 696 
INDUCTION CURRENTS. 
[Sec. 328. 
placing a piece of muscle, cartilage, vegetable tissue, or even a prismatic strip of coagulated 
albumin across these cushions, we observe that, very soon after the circuit is closed, there is a con- 
siderable variation of the current. If the direction of the current be reversed, it first becomes 
stronger, but afterwards diminishes. By constantly altering the direction of the current we 
cause the same changes in the intensity. If a prismatic strip of coagulated albumin be used for 
the experiment, we observe that, simultaneously with the enfeeblement of the current in the 
neighborhood of the -(- pole, the albumin loses water and becomes more shrivelled, while at the 
— pole the albumin is swollen up and contains more water. If the 
direction of the current be altered, the phenomena are also changed. 
Fig. 473- 
Fig. 474. 
Fig. 473.—Shunt for galvanometer. Fig. 474.—Induced currents in straight parallel closed 
circuits. B, battery; K, key; P, S, primary and secondary circuits; G, galvanometer. 
The shrivelling and removal of water in the albumin at the positive pole must be the cause of 
the resistance in the circuit, which explains the enfeeblement of the galvanic current. This 
phenomenon is called “external secondary resistance” (du Bois-Reymond). 
[Induced currents in a closed secondary circuit.—Suppose the parallel straight wires to 
be joined up, as shown in fig. 474. (1) Close the primary circuit (P), by putting down the key 
(K). A momentary current is induced in the opposite direction in the secondary circuit (S). 
(2) Suddenly increase the current by switching in one or more cells, and again a momentary in- 
verse current is observed in the secondary. (3) Break the current in the primary coil by raising 
the key (K). A momentary direct current, i. e., one in the same direction, is induced in the 
secondary circuit; and (4) the same result is obtained by suddenly diminishing the current in 
the primary (by switching out one or more cells). 
Precisely the same results are obtained with two closed spirals or selenoidal coils of wire, only 
the induced currents will be stronger; and the effects will be made still stronger by putting a 
piece of soft iron into the heart of each coil. 
Table of Induction Currents (Jamieson). 
Momentary inverse currents are induced 
in a secondary circuit 
By (i) Approach to primary. 
“ (2) Starting primary current. 
“ (3) Increasing primary current. 
Momentary direct currents are induced in 
a secondary circuit 
By (i) Withdrawal from primary. 
“ (2) Stopping primary current. 
“ (3) Decreasing primary current.] 
329. INDUCTION—EXTRA-CURRENT —MAGNETIC-INDUCTION. —In- 
duction of the Extra-Current.—If a galvanic element is closed by means of a short arc of 
wire, at the moment the circuit is again opened or broken, a slight spark is observed. If, how- 
ever, the circuit is made or closed by means of a very long wire rolled in a coil, then on break- 
ing the circuit there is a strong spark. If the wires be connected with two electrodes, so that a 
person can hold one in each hand, the current at the moment it is opened must pass through the 
person’s body; then there is a violent shock communicated to the hand. This phenomenon is 
due to a current induced in the long spiral of wire which Faraday called the extra-current. It 
is caused thus : When the circuit is closed by means of the spiral wire, the galvanic current 
passing along it excites or induces an electric current in the adjoining coils of the same spiral. 
At the moment of closing or making the circuit in the spiral, the induced current is in the oppo- 
site direction to the galvanic current in the circuit; hence its strength is lessened, and it causes Sec. 329.] 
MAKE AND BREAK INDUCTION SHOCKS. 
697 
no shock. At the moment of opening, however, the induced current has the same direction as 
the galvanic stream, and hence its action is strengthened. 
Magnetization of Iron by the Galvanic Current.—If a rod of soft iron be placed in the 
cavity of a spiral of copper wire, then the soft iron remains magnetic as long as a galvanic cur- 
rent circulates in the spiral. If one end of the iron rod be directed towards the observer, and the 
other away from him, and if, further, the positive current traverse the spiral in the same direc- 
tion as the hands of a clock, then the end of the magnet directed towards the person is the 
negative pole of the magnet. The power of the magnet depends upon the number of spiral 
windings and on the thickness of the iron bar. As soon as the current is opened, the magnetism 
of the iron rod disappears. 
Induced or Faradic Current.—If a very long, isolated wire be coiled into the form of a 
spiral roll, which we may call the secondary spiral, and if a similar spiral, the primary spiral, 
be placed near the former, and the ends of the wire of the primary spiral be connected with the 
poles of a constant battery, every time the current in the primary circuit is made (closed), or 
broken (opened), a current takes place, or, as it is said, is induced in the secondary spiral. 
If the primary circuit be kept closed, and if the secondary spiral be brought nearer to, or 
removed further from, the primary spiral, a current is also induced in the secondary spiral 
{Faraday, 1832). The current in the secondary circuit is called the induced or Faradic cur- 
rent. When the primary circuit is closed, or when the two spirals are brought nearer to each 
other, the current in the secondary spiral has a direction opposite to that in the primary spiral, 
while the current produced by opening the primary circuit, or by removing the spirals further 
apart, has the same direction as the primary. During the time the primary circuit is closed, or 
when both spirals remain at the same distance from each other, there is no current in the secon- 
dary spiral. 
Difference between the Opening [break] and Closing [make] Induction Shocks.— 
[Every time the current is made or broken in the primary circuit a shock is induced in the sec- 
ondary circuit. The induced shock is called the make and the other the break induction 
shock.] The opening and closing shocks induced in the secondary spiral are distinguished 
from each other in the following respects (fig. 475): The amount of electricity is the same dur- 
ing the opening as during the closing shock, but during the opening shock the electricity 
rapidly reaches its maximum of intensity and lasts but a short time, while during the closing 
shock it gradually increases, but does not reach the high maximum, and this occurs more 
slowly. (In fig. 475, Pj and S0 are the abscissae of the primary (inducing) and induced cur- 
rents respectively. The vertical lines or ordinates represent the intensity of the current, while 
the length of the abscissa indicates its duration. Curve 1 indicates the course of the primary 
current, and 2, that in the secondary spiral (induced) when the current is closed, while at I the 
primary current is suddenly opened, when it gives rise to the induced current, 4, in the secondary 
spiral.] The cause of the difference is the following: When the primary circuit is made or 
closed, there is developed in it the extra-current, which is opposite in direction to the primary 
current. Hence, it opposes considerable resistance to the complete development of the strength 
of the primary current, so that the current induced in the secondary spiral must also develop 
slowly [thus the make induction shock is weakened]. But when the primary spiral is broken 
or opened, the extra-current in the latter has the same direction as the primary current—there is 
no extra resistance. [Hence the break induction shock is stronger than the make.] The 
rapid and intense action of the break or opening induction shock is of great physiological im- 
portance. 
Break or Opening Shock.—[On applying a single induction shock to a nerve or a 
muscle, the effect is greater with the break or opening shock, i. e., the break is stronger than 
the make induction shock. If the secondary spiral be-separated from the primary, so that the 
induced currents are not sufficient to cause contraction of a muscle when applied to its motor 
nerve, then, on gradually approximating the secondary to the primary spiral, the break or 
opening shock will cause a contraction before the closing one does so.] 
Helmholtz’s Modification.—Under certain circumstances, it is desirable to equalize the 
make and break shocks. This may be done by greatly weakening the extra-current, which 
may be accomplished by making the primary spiral of only a few coils of wire. V. Helmholtz 
accomplishes the same result by introducing a secondary circuit into the primary current. By 
this arrangement the current in the primary spiral never completely disappears, but at alternate 
making and breaking this secondary circuit where the resistance is much less it is alternately 
weakened and strengthened. 
[In fig. 476 a wire is introduced between a and f, while the binding screw f is separated from 
the platinum contact, c, of Neefs hammer, but at the same time the screw, d, is raised so that it 
nearly touches Neefs hammer, so that, when the hammer is attached, c touches d. The current 
passes from the battery, K, through the pillar, a, to f in the direction of the arrow, through the 
primary spiral, P, to the coil of soft wire, g, and back to the battery, through h and e. But g is 
magnetized thereby, and when it is so, it attracts c and makes it touch the screw d. Thus a 698 
INDUCTION CURRENTS. 
[Sec. 329. 
secondary circuit, or short circuit, is formed through a, b, c, d, e, which weakens the current 
passing through the electro-magnet, £•, so that the elastic metallic spring flies up again and the 
current through the primary spiral is long-circuited, and thus the process is repeated. [The 
break shock in the secondary coil is due to the weakening of the current in the primary coil 
when the latter is short-circuited. Consequently an extra-current, having a direction reverse to 
that in the primary current, is induced in the primary coil; when the shock is made, the break 
shock is reduced in strength and becomes nearly equal to the make shock. In fig. 475 the lines 
1 and 7 indicate the course of the current in the primary circuit at closing (a), and opening (<?). 
It must be remembered that in this arrangement there is always a current passing through the 
primary spiral P (fig. 476). The dotted lines 6 and 8, above and below S0, represent the course 
of the opening (a) and closing shocks (<?) in the secondary spiral. Even with this arrangement 
the opening is still slightly stronger than the closing shock.] The two shocks, however, may 
be completely equalized by placing a resistance coil or rheostat in the short circuit, which in- 
creases the resistance, and thus increases the current through the primary spiral when the short 
circuit is closed. 
[Extra-current with Helmholtz’s Arrangement.—An extra-current is induced in the 
primary coil both at make and break of the primary circuit. This extra-current may be led off 
and used for stimulating by connecting electrodes with d and f] 
Unipolar-Induction.—When there is a very rapid current in the primary spiral, not only is 
Fig- 475- 
Fig. 476. 
Fig. 475.—Scheme of the induced currents. P1( abscissa of the primary and S0, of the secondary 
current; A, beginning, and E, end of the inducing current; 1, curve of the primary current 
weakened by an extra-current; 3, where the primary current is opened; 2 and 4, corre- 
sponding currents induced in the secondary spiral; P2, height, i. e., the strength of the con- 
stant inducing current; 5 and 7, the curve of the inducing current when it is opened and 
closed during Helmholtz’s modification; 6 and 8, the corresponding currents induced in the 
secondary circuit. Fig. 476.—Helmholtz’s modification of Neef’s hammer. As long as c 
is not in contact with d, g h remains magnetic; thus c is attracted to a and a secondary cir- 
cuit, a, b, c, d, e is formed; c then springs back again, and thus the process goes on. A 
new wire is introduced to connect a with f K, battery. 
there a current induced in the secondary spiral, when its free ends are closed, e.g., by being 
connected with an animal tissue, but there is also a current when one wire is attached to a bind- 
ing screw connected with one end of the wire of the secondary spiral (p. 681). A muscle of a 
frog’s leg, when connected with this wire, contracts, and this is called a unipolar induced 
contraction. It usually occurs when the primary circuit is opened. The occurrence of these 
contractions is favored when the other end of the spiral is placed in connection with the ground, 
and when the frog’s muscle preparation is not completely insulated. 
Magneto-Induction.—If a magnet be brought near to, or thrust into the interior of, a coil 
of wire, it excites a current, and also when a piece of soft iron is suddenly rendered magnetic or 
suddenly demagnetized. The direction of the current so induced in the spiral is exactly the 
same as that with Faradic electricity, i. e., the occurrence of the magnetism, on approximating 
the spiral to a magnet, excites an induced current in a direction opposite to that supposed to cir- 
culate in the magnet. Conversely, the demagnetization, or the removal of the spiral from the 
magnet, causes a current in the same direction. 
Acoustic Tetanus.—If a magnet be rapidly moved to and fro near a spiral, which can easily 
be done by fixing a vibrating magnetic rod at one end and allowing the other end to swing freely 
near the spiral, then the pitch of the note of the vibrating rod gives us the rapidity of the induc- Sec. 330.] 
INDUCTION MACHINE. 
699 
tion shocks. If a frog’s nerve-muscle preparation be stimulated, we get what Grossmann called 
“ acoustic tetanus.” 
330. DU BOIS-REYMOND’S INDUCTORIUM — MAGNETO-INDUCTION 
APPARATUS.—The inductorium of du Bois-Reymond, which is used for physiological 
purposes, is a modification of the magneto-electromotor apparatus of Wagner and Neef. A 
scheme of the apparatus is given in fig. 477. D represents the galvanic battery. The wire from 
the positive pole, a, passes to a metallic column, S, which has a horizontal vibrating spring, F, 
attached to its upper end. To the outer end of the spring a square piece of iron, e, is attached. 
The middle point of the upper surface of the spring [covered with a little piece of platinum] is 
in contact with a movable screw, b. A moderately thick copper wire, c, passes from the screw, 
b, to the primary spiral or coil, x, x, which contains in its interior a number of pieces of soft 
iron wire, i, i, covered with an insulating varnish. The copper wire which surrounds the primary 
spiral is covered with silk. The wire, d, is continued from the primary spiral to a horse-shoe 
piece of soft iron, FI, around which it is coiled spirally, and from thence it proceeds, at f, back 
to the negative pole of the battery, g. When the current in this circuit—called the primary 
circuit—is closed, the following effects are produced: The horse-shoe, H, becomes magnetic, 
in consequence of which it attracts the movable spring or Neef’s hammer, e, whereby the contact 
of the spring, F, with the screw, b, is broken. Thus the current is broken, the horse-shoe is 
Fig. 477. 
I, Scheme of du Bois-Reymond’s sledge induction machine. D, galvanic battery; a, wire!from 
pole, (g) — pole; S, brass upright; F, elastic spring; b, binding screw; c, wire round 
primary spiral [x, x), containing (i, i) soft iron wire; K, K, secondary spiral, with board 
(p,p) on which it can be moved ; H, soft iron magnetized by current \d, f) passing round 
it. II, key for secondary circuit, as shown it is short-circuited. Ill, electrodes (r, r), with 
a key (K) for breaking the circuit. 
demagnetized, the spring, e, is liberated, and being elastic, it springs upward again to its original 
position in contact with b, and thus the current is re-established. The new contact causes H to 
be remagnetized, so that it must alternately rapidly attract and liberate the spring, e, whereby the 
primary current is rapidly made and broken between F and b. 
A secondary spiral or coil (K, K) is placed in the same direction as the primary (x, x), but 
having no connection with it. It moves in grooves upon a long piece of wood (p,p). The 
secondary spiral consists of a hollow cylinder of wood covered with numerous coils of thin silk- 
covered wire. The secondary spiral, moving in slots, can be approximated to or even pushed 
entirely over the primary spiral, or can be removed from it to any distance desired. 
[Fig. 478 shows the actual arrangement of du Bois-Reymond’s inductorium. The primary 
coil (R7) consists of about 150 or even 400 coils of thick insulated copper wire, the wire being 
thick to offer slight resistance to the galvanic current, the resistance being equal to about 1.5 
ohm. The secondary coil (R///) consists of 6000 or 12000 turns of thin insulated copper wire 
arranged on a wooden bobbin. The resistance is equal to about 1350 ohms. The whole spiral 
can be moved along the board (B) to which a millimetre scale (I) is attached, so that the dis- 
tance of the secondary from the primary spiral may be ascertained. At the left end of the ap- 
paratus is Wagner’s hammer, as adapted by Neef, which is an automatic arrangement for 700 
MAGNETO-INDUCTION. 
[Sec. 330. 
opening and breaking the primary circuit. When Neef’s hammer is used, the wires from 
the battery are connected as in the figure; but when single shocks are required, the wires 
from the battery are connected with a key, and this again with the two terminals of the primary 
spiral, S// and S///. In the improved form of this apparatus (fig. 479) the secondary spiral is 
equipoised over a pulley with a back weight, so that it can move easily in a vertical direction to 
and from the primary spiral. A. de Watteville has used a form similar to this for a long time.] 
According to the law of induction (g 329), when the primary circuit is closed, a current is 
induced in the secondary circuit in a direction the reverse of that in the primary, while, when it 
is opened, the induced current has the same direction. Further, according to the laws of 
magneto-induction, the magnetization of the iron rods (i, i) within the primary spiral (x, x), 
causes a reverse current in the secondary spiral (K, K), while the demagnetization of the iron 
rods, on opening the primary circuit, causes an induced current in the same direction. Thus 
we explain the much more powerful action of the opening or break shock as compared with the 
closing or make shock (p. 697). [The direction of the inducing current remains the same, 
while the direction of the induced currents are constantly reversed.] 
The magneto-induction (R) apparatus of Pixii, as improved by Stohrer, consists of a very 
powerful horse-shoe steel magnet (fig. 480). Opposite its two poles (N and S) is a horse-shoe- 
shaped piece of iron (H), which rotates on a horizontal axis 
[a, i>). On the ends of the horse-shoe are fixed wooden bobbins 
(c,d), with an insulated wire coiled round them. When the 
horse-shoe is at rest, as in the figure, it becomes magnetized 
by the steel magnet, while in the wires of both bobbins (c and 
d) an electric current is developed every time the horse-shoe 
is demagnetized and again magnetized. When the bobbins 
rotate in front of the magnet as each coil approaches one pole, 
a current is induced, and similarly when it is carried past the 
pole of the magnet, so that four currents are induced in each 
coil by a single rotation. By means of Stohrer’s commutator 
(m, n) attached to the spindle (a, b), and the divided metal 
Fig. 478. 
Fig. 479. 
Fig. 478.—Induction apparatus of du Bois-Reymond. R', primary, R", secondary spiral; B, 
board on which R" moves; 1, scale; -) , wires from battery; P/, P//, pillars; H, Neef’s 
hammer; B', electro magnet; S/, binding screw touching the steel spring (H); S// and 
S'", binding screws to which to attach wires where Neef’s hammer is not required. Fig. 
479.—New form of du Bois-Reymond’s inductorium. 
plates (y, z) which pass to the electrodes, the two currents induced in the bobbins are obtained 
in the same direction. 
Keys, or arrangements for opening or closing a circuit, are of great use. Fig. 477, II, shows 
a scheme of the friction key of du Bois-Reymond, introduced into the secondary circuit. It 
consists of two brass bars (z andjj/) fixed to a plate of ebonite, and as long as the key is down 
on the metal bridge (y, r, z) it is “ short-circuited,” i. e., the conduction is so good through 
the thick brass bars that none of the current goes through the wires leading from the left of the 
key. When the bridge (r) is lifted the current is opened. [Fig. 481 shows the form of the 
key, v being a screw wherewith to clamp it to the table.] Similarly the key electrodes (III) Sec. 330.] 
KEYS. 
701 
may be used, the current being made as soon as the spring connecting-plate (e) is raised by 
pressing upon k. This instrument is opened by the hand; a, b are the wires from the battery or 
induction machine; r, r, those going to the tissue; G, the handle of the instrument. 
[Plug Key.—Other forms of keys are in use, e. g., fig. 482, the plug key, the two brass plates 
to which the wires are attached being fixed on a plate of ebonite. The brass plug is used to 
Fig. 480. 
Fig. 481. 
Magneto-induction apparatus, with Stohrer’s 
commutator. 
Du Bois-Reymond’s friction key. 
connect the two brass plates. All these are dry contacts, but sometimes a fluid] contact is 
used, as in the mercury key, which merely consists of a block of wood with a cup of mercury 
in its centre. The ends of the wires from the battery dip into the mercury; when-both wires 
dip into the mercury the circuit is made, and when one is out it is broken.] 
Fig. 482. 
Fig. 483. 
Fig. 482.—Plug key. Fig. 483.—Capillary contact, e, vibrating platinum style adjustable 
by f and g and dipping into mercury at a ; b, bent tube filled with mercury, into which 
dips a wire (d); a, opening in cross tube (c). 
[Capillary Contact Key.—Where an ordinary mercury key is used to open and close the 
primary circuit, the layer of oxide formed on the surface by the opening spark disturbs the con- 
duction after a short time; hence, it is advisable to wash the surface of the mercury with a dilute 
solution of alcohol and water. A handy form of “ capillary contact” is shown in fig. 483, such 
as was used by Kronecker and Stirling in their experiments on the heart. A glass j-tube is 702 
CAPILLARY ELECTROMETER. 
[Sec. 330. 
provided at the crossing point with a small opening (a). The vertical tube (b) is bent in the 
form of a U, and filled so full with mercury that the convex surface of the latter projects within 
the lumen of the transverse tube (c). One end of c is connected with a Mariotte’s flask con- 
taining diluted alcohol, and the supply of the latter can be regulated by means of a stop-cock. 
The fluid flows over the apex of the mercury and keeps it clean. The vibrating platinum style 
(c) is attached to the end of a rod, which in turn is connected with the positive pole of the 
battery, while the platinum wire (d) is connected with the negative pole of the “ battery.”] 
331. ELECTRICAL CURRENTS IN RESTING MUSCLE 
AND NERVE—SKIN CURRENTS.—Methods.—In order to inves- 
tigate the laws of the muscle-current, we must use a muscle composed of par- 
allel fibres, and with a simple arrangement of its fibres in the form of a prism 
or cylinder (fig. 484, I and II). The sartorius muscle of the frog supplies 
these conditions. In such a muscle, we distinguish the surface or the natural 
longitudinal section; 
its tendinous ends or 
the natural transverse 
section; further, when 
the latter is divided trans- 
versely to the long axis, 
the artificial transverse 
section (fig. 484,1, c, d) ; 
lastly, the term equator 
(a, b-m, ri) is applied to a 
line so drawn as exactly to 
divide the length of the 
muscle into halves. As 
the currents are very feeble, 
it is necessary to use a gal- 
vanometer with a peri- 
odic damped magnet (figs. 
459, I, and 471), or a tan- 
gent mirror-boussole simi- 
lar to that used for thermo- 
electric purposes (fig. 230). 
The wires leading from the 
tissue are connected with 
non-polarizable electrodes 
(fig. 459, P, P). 
The capillary-electrometer 
of Lippmann may be used for 
detecting the electrical current of a muscle or nerve (fig. 485). A thread of mercury enclosed 
in a capillary tube and touching a conducting fluid, e. g., dilute sulphuric acid, is displaced by 
the constant current, in consequence of the polarization taking place at the point of contact alter- 
ing the constancy of the capillarity of the mercury. The displacement of the mercury which 
the observer (B) detects by the aid of the microscope (M) is in the direction of the positive cur- 
rent. R is a capillary glass tube, filled from above with mercury, and from below with dilute 
sulphuric acid. Its lower narrow end opens into a wide glass tube, provided below with a plati- 
num wire fused into it and filled with Hg and this again is covered with dilute sulphuric 
acid (s). The wires are connected with non-polarizable electrodes applied to the -f- and — sur- 
faces of the muscle. On closing the circuit, the thread of mercury passes downwards from c in 
the direction of the arrow. 
Compensation of a Current.—The strength of the current in animal tissues is best measured 
by the compensation method of Poggendorf and du Bois-Reymond. A current of known 
strength, or which can be accurately graduated, is passed in an opposite direction through the 
same galvanometer or boussole, until the current from the animal tissue is just neutralized or com- 
pensated. [When this occurs, the needle deflected by the tissue-current returns to zero. The 
principle is exactly the same as that of weighing a body in terms of some standard weights 
placed in the opposite scale-pan of the balance. 
Capillary electrometer. 
R, mercury in tube; 
capillary tube; s, sul- 
phuric acid ; q, Hg; 
B, observer; M, mi- 
croscope. 
Fig. 485. 
Scheme of the muscle-current. 
Fig. 484. Sec. 331.] 
MUSCLE-CURRENTS. 
703 
[Hermann calls the current obtained from an injured muscle, i. e, one on 
which an artificial transverse or other section has been made, a demarcation- 
current, while the currents obtained when such a muscle contracts he calls 
action-currents. This section deals with demarcation-currents, or the muscle- 
current of du Bois-Reymond.] 
1. Perfectly fresh uninjured muscles yield no current, and the same is 
true of dead muscle (L. Hermann, 1867). 
2. Strong electrical currents are obtained when the artificial transverse 
section of a muscle is placed on one of the cushions of the non-polarizable elec- 
trodes (fig. 459 I, M), while the longitudinal surface is in connection with the 
other (Nobili, Matteucci, du Bois-Reymond'). The direction of the current 
is from the (positive) longitudinal section to the (negative) transverse section in 
the conducting wires (i. e., within the muscle itself from the transverse to the 
longitudinal section (figs. 459, I, and 384, I)). This current is stronger the 
nearer one electrode is to the equator and the other to the centre of the trans- 
verse section; while the strength diminishes the nearer the one electrode is to 
the end of the surface, and the other to the margin of the transverse section. 
Smooth muscles also yield similar currents between their transverse and longitudinal surfaces 
(S 334, II). 
3. Weak electrical currents are obtained when—(a) two points at un- 
equal distances from the equator are connected with the galvanometer, the cur- 
rent then passes from the point near the equator (-(-) to the point lying further 
from it (—), but of course this direction is reversed within the muscle itself 
(fig. 384, II, ke and le'). (fi) Similarly weak currents are obtained by connect- 
ing points of the transverse section at unequal distances from the centre, in 
which case the current outside the muscle passes from the point lying nearer 
the edge of the muscle to that nearer the centre of the transverse section 
(fig. 484, II, i, c). 
4. When two points on the surface are equidistant from the equator (fig. 
484, I, x, y, v, z,—II, r, <?), or two equidistant from the centre of the trans- 
verse section (II, c) are connected, no current is obtained, because the points 
are iso-electrical, that is, of equal potential. 
5. If the artificial transverse section of the muscle be oblique (fig. 484, HI), 
so that the muscle forms a rhomb, the conditions obtaining under III are dis- 
turbed. The point lying nearer to the obtuse angle of the transverse section or 
surface is positive to the one lying near to the acute angle. The equator is 
oblique (a, c). These currents are called “ deviation currents or inclination 
currents ” by du Bois-Reymond, and their course is indicated by lines 1, 2, 
and 3. 
The electro-motive force of a strong muscle-current (frog) is equal to 0.05 to 0.08 of a 
Daniell’s element; while the strongest deviation current may be 0.1 Daniell. The muscles of 
a curarized animal at first yield stronger currents; fatigue of the muscle diminishes the strength 
of the current (Roeber), while it is completely abolished when the muscle dies. Heating a 
muscle increases the current; but above 40° C. it is diminished (Steiner). Cooling diminishes 
the electro-motive force. The warmed living muscular and nervous substances is positive to the 
cooler portions (Hermann); while, if the dead tissues be heated, they behave practically as 
indifferent bodies as regards the tissues that are not heated. 
6. The passive nerve behaves like muscle, as far as 1, 2, and 3 are con- 
cerned. [If one electrode be placed on the longitudinal surface and another on 
the artificial transverse section of a nerve, and the current led off to a galva- 
nometer, the needle of the latter is slightly deflected by the “ nerve-current,” 
the direction of the current being from the -f- longitudinal surface through the 
galvanometer to the — transverse section.] 
The electro-motive force of the strongest nerve-current, according to du Bois-Reymond, 704 
PROOFS OF CURRENTS FROM MUSCLE. 
[Sec. 331. 
is 0.02 of a Daniell. Heating a nerve from 150 to 250 C. increases the nerve current, while 
high temperatures diminish it (Steiner). 
7. If the two transversely divided ends of an excised nerve, or two points 
on the surface equidistant from the equator, be tested, a current—the axial 
current—flows in the nerve-fibre in the opposite direction to the direction of 
the normal impulse in the nerve; so that in centrifugal nerves it flows in a 
centripetal direction and in centripetal nerves in a centrifugal direction {Men- 
dels short and Christiani). 
The electro-motive force increases with the length of the nerve and with the area of its 
transverse section. Fatigue (e. g., tetanic stimulation) weakens it, especially in motor nerves, 
and to a less extent in centripetal nerves. 
Rheoscopic Limb.—The existence of a muscle-current may be proved 
without the aid of a galvanometer : 1. By means of a sensitive nerve- 
muscle preparation of a frog, or the so-called “ physiological rheoscope ” 
or ‘ ‘ rheoscopic limb. ’ ’ Place a moist conductor on the transverse and another 
on the longitudinal surface of the gastrocnemius of a frog. On placing the 
sciatic nerve of a nerve-muscle preparation of a frog on these conductors, so 
as to bridge over or connect their two surfaces, contraction of the muscle con- 
nected with the nerve occurs at once ; and the same occurs when the nerve is 
removed. 
[Nerve-muscle Preparation.—This term has been used on several occa- 
sions. It is simply the sciatic nerve with the gastrocnemius of the frog at- 
tached to it (fig. 486). The sciatic nerve is dissected out 
entire from the vertebral column to the knee; the muscles 
of the thigh separated from the femur, and the latter di- 
vided about its middle, so that the preparation can be fixed 
in a clamp by the remaining portion of the femur; while 
the tendon of the gastrocnemius is divided near to the foot. 
If a straw flag is to be attached to the foot, do not divide 
the tendo-Achillis]. 
Make a transverse section of the gastrocnemius muscle of 
a frog’s nerve-muscle preparation, and allow the sciatic 
nerve to fall upon this transverse section ; the limb will 
contract as the muscle-current from the longitudinal to the 
transverse surface now traverses the nerve {Galvani, Al. v. 
Humboldf). These experiments have long been known as 
“ contraction without metals.” 
[Use a nerve-muscle preparation, or, as it is called, a physiological 
limb. Hold the preparation by the femur, and allow its own nerve to 
fall upon the gastrocnemius, and the muscle will contract, but it is better 
to allow the nerve to fall suddenly upon the cross-section of the muscle. 
The nerve then completes the circuit between the longitudinal and 
transverse section of the muscle, so that it is stimulated by the current 
from the latter, the nerve is stimulated, and through it the muscle. 
That it is so is proved by tying a thread round the nerve near the muscle, when the latter no 
longer contracts.] 
2. Self-Stimulation of the Muscle.—We may use the muscle-current 
of an isolated muscle to stimulate the latter directly and cause it to contract. 
If the transverse and longitudinal surfaces of a curarized frog’s nerve-muscle 
preparation be placed on non-polarizable electrodes, and the circuit be closed 
by dipping the wires coming from the electrodes in mercury, then the muscle 
contracts. Similarly a nerve may be stimulated with its own demarcation- 
current {du Bois-Reymond and others). If the lower end of a muscle with 
its transverse section be dipped into normal saline solution (0.6 per cent. 
NaCl), which is quite an indifferent fluid, this fluid forms an accessory circuit 
Fig. 486. 
Nerve-muscle prepa- 
ration of a frog. F, 
femur; S, sciatic 
nerve; I, tendo- 
Achillis. Sec. 331.] 
ACTION CURRENTS. 
705 
between the transverse and adjoining longitudinal surface of the muscle, so 
that the muscle contracts. Other indifferent fluids used in the same way pro- 
duce a similar result. 
[Kiihne’s Experiment (fig. 487).—The demarcation-current of the nerve 
of a nerve-muscle preparation may be used as the stimulus to that nerve on 
completing the circuit. On an 
earthenware bowl (B) is fixed a 
glass plate (G) and thin rolls of 
modeller’s clay (P P') are bent over 
G. A nerve-muscle preparation is 
placed with its nerve (N) on the 
clay, touching the latter with its 
transverse and longitudinal surfaces. 
On dipping the clay into a vessel 
containing normal saline (C) the 
muscle contracts, and on withdraw- 
ing the normal saline it again con- 
tracts. In this case the nerve is 
stimulated by the completion of the 
circuit of its own demarcation-cur- 
3. Electrolysis.—If the muscle-current be conducted through starch mixea 
with potassic iodide, then the iodine is deposited at the -j- pole, where it makes 
the starch blue. 
Frog Current.—It is asserted that the total current in the body is the sum of the electrical 
currents of the several muscles and nerves which, in a frog deprived of its skin, pass from the 
tip of the toes toward the trunk, and in the trunk from the anus to the head. This is the 
“ corrente propria della rana ” of Leopoldo Nobili (1827), or the “ frog-current ” of du Bois- 
Reymond. In mammals, the corresponding current passes in the opposite direction. 
When the nerves have lost their excitability in the condition of narcosis after the administra- 
tion of ether or chloroform, the muscle-current may even be slightly increased (Biedermann). 
After death, the currents disappear sooner than the excitability (Valentin) ; they remain 
longer in the muscle than the nerves, and in the latter they disappear sooner in the central por- 
tions. If the nerve-current after a time become feeble, it may be strengthened by making a 
new transverse section of the nerve. A motor nerve completely paralyzed by curare gives a 
current (Funke), and so does a nerve beginning to undergo degeneration, even two weeks after 
it has lost its excitability. Muscles in a state of rigor mortis give currents in the opposite 
direction, owing to inequalities, which take place during decomposition. The nerve-current is 
reversed by the action of boiling water or drying. 
Currents from Skin and Mucous Membranes.—In the skin of the 
frog the outer surface is -j-, the inner is — (du Bois-Reymond), and the same 
is true of the mucous membrane of the intestinal tract {Rosenthal), the 
cornea (Griinhagen), as well as the non-glandular skin of fishes {Hermann) 
and molluscs (Oehler). Currents are also manifested by glands (§ 145). 
332. CURRENTS OF STIMULATED MUSCLE AND 
NERVE—ACTION-CURRENTS.—1. Negative Variation of the 
Muscle-Current.—If a muscle which yields a strong electrical current be 
thrown into a state of tetanic contraction by stimulating its motor nerve, then, 
when the muscle contracts, there is a diminution of the muscle-current, 
and occasionally the needle of the galvanometer may swing almost to zero. 
This is the “negative variation of the muscle-current” (du Bois-Rey- 
mond). It is larger the greater the primary deflection of the galvanometer 
needle and the more energetic the contraction. 
After tetanus the muscle-current is weaker than it was before. If the muscle was so placed 
upon the electrodes that the current was “ feeble,” equally during tetanus there is a diminution 
Fig. 487. 
Kiihne’s nerve demarcation-current experiment. 706 
[Sec. 332. 
ACTION CURRENTS. 
of this current. In the inactive arrangement, the contraction of the muscle has no effect on 
the needle. If the muscle be prevented from shortening, as by keeping it tense, the negative 
variation still takes place. 
2. Current During Tetanus.—An excised frog’s muscle teta?iized through 
its nerve shows electro-motive force—the so-called “ action-current.” In a 
tetanized frog’s gastrocnemius, there is a descending current. In completely 
uninjured human muscles, however, thrown into tetanus by acting on their 
nerves, there is no such current (Z. Hermann); similarly, in quite uninjured 
frog’s muscles, as well as when these muscles are directly and completely tetanized, 
there is no current. 
3. Muscle-Current accompanying the contraction-wave.—If one 
end of a muscle be directly excited with a momentary stimulus, so that the 
contraction-wave (§ 299) rapidly passes along the whole length of the muscular 
fibres, then each part of the muscle, successively and immediately before it 
contracts, becomes negatively electrical. It is usually stated that the “ con- 
traction-wave ” is preceded by a “ negative wave ” of the muscle- 
current, and that the latter occurs during the latent period (?). Both waves 
have the same velocity, about 3 metres per second. The negative wave, which 
first increases and then diminishes, lasts at each point only 0.003 second {Bern- 
stein). [Suppose two points, A and B, on the longitudinal surface of a muscle 
to be led off with non-polarizable electrodes to a galvanometer. There will 
be no deflection of the needle, as the points are iso-electrical. If a single in- 
duction shock be applied at one end of the muscle, a contraction-wave will be 
propagated along the muscle. It is usually stated that preceding the contrac- 
tion-wave, however, a wave of negativity will 
pass along the fibre. It will reach A before B, 
so that A will be negative to B and to the rest of 
the fibre, and the needle will be deflected. The 
wave of negativity as it travels will reach B, and 
make B negative to the rest of the fibre, and to 
A, from which the negativity is disappearing. 
This will cause the needle to be deflected in the 
opposite direction, so that a single wave of con- 
traction in a muscle is preceded by two currents 
of different phases, i.e., it gives rise to a dipha- 
sic variation or change. Burdon-Sanderson, 
however, has shown that the electro-motive 
changes, instead of preceding the change of mus- 
cular form, actually accompany the latter, so 
that the view that it occurs during the latent 
period must be abandoned (p. 610, fig. 395).] 
4. During a single Contraction. — A 
single contraction also shows a muscle-current. 
[The electrical variation takes place during the 
latent period of the muscular contraction, so 
that it precedes the latter (?) The variation 
begins 0.1" to .04" after excitation, while the 
contraction does not begin until .11" to .33" 
(Waller). A frog’s muscle may be made to 
record its contraction, and simultaneously the 
variation of the electrical current, as ascertained 
by the capillary electrometer, may be photo- 
graphed (fig. 488), and the same may be done in the case of the heart (fig. 
489). The capillary electrometer may with advantage be employed to measure 
Fig. 488. 
Frog. Gastrocnemius led oft 
to electrometer from the 
middle of the muscle and 
from the tendon. Contrac- 
tion excited by a single break 
induction shock applied to 
the sciatic nerve, e, electro- 
meter; m, muscle; t, time in 
sec. (muscle to H2S04; 
tendon to Hg) ( Waller). Sec. 332.] 
HEART CURRENT. 
707 
this time-difference, the electrical and mechanical events being simultaneously 
recorded.] 
The diphasic variation.— 1st phase middle negative to end; 2d phase and negative to 
middle begins about .oi// before the commencement of muscular contraction (Waller). 
The variation is diphasic.—1st phase base negative to apex; 2d phase apex negative to base 
( Waller). The first phase begins Tl0// before the commencement of contraction. 
One of the best objects for this purpose is the contracting heart, which is 
placed upon the non-polarizable electrodes connected with a sensitive galvano- 
meter. Each beat of the heart causes a deflection of the needle, which occurs 
before the contraction of the cardiac muscle (.Kolliker and H. Muller). The 
electrical disturbance in the muscle causing the negative variation always pre- 
cedes the actual contraction (v. Helmholtz, 1845). Still it lasts throughout the 
whole duration of the contraction (Zee). When the completely uninjured 
frog’s gastrocnemius contracts by stimulating the nerve, there is at first a 
descending and then an ascending current (Sig. Mayer, § 334, II). 
More exact observations on the electrical processes of the pulsating 
heart show that complicated phenomena occur. With every beat of the 
heart, first the apex, and then the base of the ventricle becomes negative 
Fig. 489. 
Frog’s heart. Spontaneous contraction, e, e, electrometer; h, h, heart’s contraction ; t, t, time 
in jlyth sec. (apex to H2S04, base to Hg) (Waller). 
(.Fredericq and Waller), so that necessarily there is a diphasic variation 
with each beat (fig. 489). If the heart be arrested in diastole by stimulation 
of the vagus (§ 369), there is a positive variation of the muscle-current (Gas- 
kell, Fano). Waller has demonstrated a true electrical variation of the human 
intact heart. 
[Heart.—Gaskell has shown that when the vagus of a tortoise is stimulated 
so as to arrest its heart in diastole, the action of the inhibitory nerve is accom- 
panied by a positive electrical variation of the heart current, while stimulation 
of the sympathetic (augmentor) nerve causes an electrical variation of the same 
sign as that caused by a contraction in the non-beating tissue of the ventricle 
of the toad. In both cases the respective nerves can produce their electrical 
effect after the heart has been brought to a standstill by the application of 
muscarin to the sinus. These experiments are of the utmost importance in 
connection with the theory of the action of these nerves on the heart (§ 370), 
and the mode of action of poisons on the heart itself.] 
[Waller has succeeded in showing the electrical variation occurring during the beat of the 
human heart in an uninjured person. The readings are made by photographing the oscillations 
of the mercury of a capillary electrometer. The currents obtained are due to the ventricles 708 
[Sec. 332. 
SECONDARY CONTRACTION AND TETANUS. 
just as much as to the auricles. There is a diphasic variation, beginning with a first phase oi 
short duration, which shows that the apex is negative to the base, and this is followed by a 
stronger variation in the opposite direction, which shows that during this period the base of the 
ventricle is negative to the apex. Waller therefore infers that the state of excitement of the 
ventricle begins at the apex and is propagated to the base. Owing to the oblique position of 
the human heart, the variation is obtained when the right and left hand, or the right hand with 
one of the feet, are connected with the electrometer, but not when one of the feet and the left 
hand are so connected.] 
Secondary Contraction.—A nerve-muscle preparation may be used to 
demonstrate the electrical changes that occur during a simple contraction. 
If the sciatic nerve, A, of such a preparation be placed upon another muscle, 
B, as in fig. 490, then every time the latter, B, contracts, the frog’s muscle, A, 
connected with the nerve also contracts. 
If the nerve of a frog’s nerve-muscle preparation be placed on a contracting 
mammalian heart, then a contraction of the muscle occurs with every beat 
of the heart (.Matteucci, 1842). The diaphragm, even after section of the 
phrenic nerve, especially the left, also contracts during the heart-beat (Schiff). 
This is the “ secondary contraction ” of Galvani. 
[Secondary Contraction from Muscle to Muscle, and Muscle- 
press (Kiihne).—If 5 mm. of one end of the sartorius of a curarized frog be 
laid upon a corresponding 5 mm. of the other sartorius, so that both muscles 
are in line, and if the surfaces of contact be pressed together, either by an 
ebonite press or other means, on stimulating the free end of one of the mus- 
cles—either electrically, mechanically, or chemically—the other muscle also 
contracts, and if the first one be tetanized, the second one also is thrown into 
tetanus. The experiment may be repeated with five or six muscles in line. 
The conduction is interrupted at once by ligature of the muscle. The second 
muscle contracts, because it is stimulated directly by the action-currents of 
the contracting muscular fibres. The effect is prevented by introducing, be- 
tween the overlapping ends of the muscle, a thin plate of gutta-percha, tinfoil, 
or any insulator. This experiment of Kiihne’s shows 
us how important a rdle electrical phenomena play in 
connection with muscular contraction. Secondary 
contraction from nerve has long beenknown.] 
Secondary Tetanus.—Similarly, if a nerve of a 
nerve-muscle preparation be placed on a muscle 
which is tetanized, then the former also contracts, 
showing “ secondary tetanus ” (du Bois-Reymond'). 
The latter experiment is regarded as a proof that, 
during the process of negative variation in the mus- 
cle, many successive variations of the current must 
take place, as only rapid variations of this kind can 
produce tetanus by acting on a nerve—continuous 
variations being unable to do so. 
Usually, there is no secondary tetanus in a frog’s nerve-muscle 
preparation when it is laid upon a muscle which is tetanized 
voluntarily, or by chemical stimuli, or by poisoning with strych- 
nin (.Hering, Kiihne); still, Loven has observed secondary strych- 
nin tetanus composed of six to nine shocks per second. Observa- 
tions with a sensitive galvanometer, or Lippmann’s capillary electrometer (fig. 485), show that 
the spasms of strychnin poisoning, as well as a voluntary contraction, are discontinuous pro- 
cesses [Loven, p. 601). 
Biedermann observed that striped muscle, under the influence of the vapor of ether, passes 
into a condition in which it shows no obvious change of form or movement when it is stimula- 
ted, whilst at the spot stimulated there are galvanometric variations of the same strength as 
occurred during stimulation before the action of the ether. Owing to the abolition of the power 
of conductivity, they can only manifest themselves locally. 
Fig. 490. 
Secondary contraction. The 
sciatic nerve of A lies on B ; 
E, electrodes applied to the 
sciatic nerve of B. Sec. 332.] 
RHEOTOME. 
709 
5. Negative Variation in Nerve.—If a nerve be placed with its artifi- 
cial transverse section on one non-polarizable electrode, and its longitudinal 
surface on the other, and if it be stimulated electrically, chemically, or me- 
chanically, the nerve-current is also diminished (du Bois-Reymond). This 
negative variation is propagated towards both ends of a nerve, and is com - 
posed of very rapid, successive, periodic interruptions of the original current, 
just as in a contracted muscle (.Bernstein). Hering succeeded in obtaining 
from a nerve, as from a muscle, a secondary contraction or secondary tetanus. 
The amount of the negative variation depends upon the extent of the primary 
deflection, also upon the degree of nervous excitability, and on the strength 
of the stimulus employed. The negative variation occurs on stimulating with 
tetanic as well as with single shocks. The negative variation is not ob- 
served in completely uninjured nerves. 
Hering found that the negative variation of the nerve-current caused by tetanic stimulation 
is followed by apositive variation, which occurs immediately after the former, i. e., it is diphasic. 
It increases to a certain degree with the duration of the stimulation, as well as with the strength 
of the stimulus, and with the drying of the nerve [Head). (Effect of Electrotonus, § 335, I). 
Negative Variation in the Spinal Cord.—This is the same as in 
nerves generally. If a current be conducted from the transverse and longitudi- 
nal surfaces of the upper part of the medulla oblongata, we observe spontaneous, 
intermittent, negative variations, perhaps due to the intermittent excitement 
of the nerve-centres, more especially of the respiratory centre. Similar varia- 
tions are obtained reflexly by single stimuli applied to the sciatic nerve, while 
strong stimulation by common salt or induction shocks inhibits them. [Gotch 
and Horsley obtained “ action currents ” from the cord when the motor areas 
of the brain were stimulated (§ 375).] 
Velocity of the Negative Variation.—The process of negative varia- 
tion is propagated at a measurable velocity along the nerve, most rapidly at 150 
to 250 C. (Steiner), and at the same rate as the velocity of the nervous impulse 
itself, about 27 to 28 metres per second. The duration of a single variation 
(of which the process of negative variation is composed) is only 0.0005 t0 
0.0008 second, while the wave-length in the nerve is calculated by Bern- 
stein at 18 mm. 
Differential Rheotome.—J. Bernstein estimated the velocity of the negative variation 
in a nerve by means of a differential rheotome thus (figs. 491, 492) : A long stretch of a nerve 
(N n) is so arranged that at one end of it (N) its transverse and longitudinal surfaces are con- 
nected with a galvanometer (G), [2. <?., an artificial transverse section and the longitudinal sur- 
face are led off by non-polarizable electrodes to the galvanometer], while at the other end (22) 
are placed the electrodes of an induction machine (J) [2'. e., the stimulating electrodes]. A disc 
(B) rapidly rotating on its vertical axis (A) has an arrangement (C) at one point of its circum- 
ference, by means of which the current of the primary circuit (E) is rapidly opened and 
closed during each revolution. This causes, with each rotation of the disc, an opening and a 
closing shock to be applied to the end of the nerve through the stimulating electrodes («). At 
the diametrically opposite part of the circumference is an arrangement (c) by which the galvano- 
meter circuit is closed and opened during each revolution. Thus the stimulation of the nerve 
and the closing of the galvanometer circuit occur at the same moment. On rapidly rota- 
ting the disc, the galvanometer indicates a strong nerve-current, an excursion of the magnetic 
needle to y. At the moment of stimulation, the negative variation has not yet reached the 
other end of the nerve. If, however, the arrangement which closes the galvanometer circuit be 
displaced along the circumference (to 0) so that the galvanometer circuit is closed somewhat 
later than the nerve is stimulated, then the current is weakened by the negative variation (the 
needle passing backward to x). When we know the velocity of rotation of the disc, it is found 
that the time for the distance of the displaced closing arrangement for the galvanometer circuit 
must be equal to the velocity at which the impulse causing the negative variation passes along a 
given distance of nerve from N to n. 
The negative variation is absent in degenerated nerves as soon as they lose their excita- 
bility. 710 
RETINAL AND EYE CURRENTS. 
[Sec. 332. 
Retinal and Eye Currents.—If a freshly excised eyeball be placed on the 
non-polarizable electrodes connected with a galvanometer, and if light fall 
Fig. 491. 
Scheme of Bernstein’s differential rheotome; N n, nerve; J, induction machine ; G, galvano- 
meter; x,y, deflection of needle; E,battery and primary circuit with C for opening it at 
0 ; c, for closing galvanometer circuit; z z, electrodes in galvanometer circuit; S, motor. 
upon the eye, then the normal eye-current from the cornea ( -f) to the 
transverse section of the optic nerve ( — ) is at first increased. 
Yellow light is most powerful, and less so the other colors {Holmgren, M’Kendrick ana 
Dewar). The inner surface of the passive retina is positive to the posterior. When the retina 
General view of a differential rheotome, as made by Petzold, of Leipzig. 
Fig. 492. 
is illuminated there is a double variation, a negative variation with a preliminary positive increase; 
while, when the light ceases, there is a simple positive variation. Retinas, in which the visual 
purple has disappeared owing to the action of light, show smaller variations (.Kuhne and Steiner). Sec. 332.] 
ELECTROTONIC CURRENTS. 
711 
Stimulation of the secretory nerves of glandular membranes, be- 
sides causing secretion, affects the current of rest (Roeber). This secretion- 
current passes in the same direction in the skin of the frog and warm-blooded 
animals as the current of rest, although in the frog it is occasionally in the 
opposite direction (.Hermann). 
If the current be conducted uniformly from the skin of both hind feet of a cat, on stimulating 
the sciatic nerve of one side, not only is there a secretion of sweat (§ 288), but a secretion-cur- 
rent is developed (Luchsinger and Hermann). If two symmetrical parts of the skin in the leg 
or arm of a man be similarly tested, and the muscle of one side be contracted, a similar current 
is developed. Destruction or atrophy of the glands abolishes both the power of secretion and 
the secretion-current. There is no secretion-current from skin covered with hairs, but devoid of 
glands (Biibnoff). [The secretion-current from the salivary glands, e.g., the submaxillary, is 
referred to in \ 145 (Bayliss and Bradford).) 
333. ELECTROTONIC CURRENTS IN NERVE AND 
MUSCLE.—[When a constant current, called the “ polarizing cur- 
rent,” is passed through a stretch of nerve, the nerve is thrown into a peculiar 
condition, called the “electrotonic condition,” or briefly electrotonus. In 
this condition the vital properties of the nerve are modified, i. e. :— 
(1) Its electromotivity (§ 333). 
(2) Its excitability (§ 335). 
(3) Its conductivity (§ 335). 
The first is considered in this section, and the latter two in a subsequent 
section.] 
1. Positive Phase of Electrotonus.—If a nerve be so arranged upon 
the electrodes (fig. 493, I) that its artificial transverse section lies on one, and 
its longitudinal on the other electrode, then the galvanometer indicates a strong 
current. If now a constant current be transmitted through the end of the 
nerve projecting beyond the electrodes (the so-called “polarizing" end of the 
nerve), and if the direction of this current coin- 
cide with that in the nerve, then the magnetic 
needle gives a greater deflection, indicating an 
increase of the nerve-current—“ the positive 
phase of electrotonus.” The increase is 
greater the longer the stretch of nerve traversed 
by the current, the stronger the galvanic cur- 
rent, and the less the distance between the part 
of the nerve traversed by the constant current 
and that on the electrodes. 
2. Negative Phase of Electrotonus.—If 
in the same length of nerve, the constant cur- 
rent passes in the opposite direction to the 
nerve-current (fig. 493, II), there is a diminu- 
tion of the electro-motive force of the latter— 
“negative phase of Electrotonus.” 
3. Equator.—If two points of the nerve 
equi-distant from the equator be placed on the 
electrodes (III), there is no deflection of the 
galvanometer needle (p. 703, 4). If a constant 
current be passed through one free projecting 
end of the nerve, then the galvanometer indi- 
cates an electro-motive effect in the same direction as the constant current. 
Electrotonus.—These experiments show that a constant current causes a 
change of the electromotive force of the part of the nerve directly traversed by 
the constant current, i. e., in the intrapolar area, and also in the part of the 
Fig- 493- 
Nerve-current in electrotonus, a, 
galvanometer; b, electrodes ; E, 
constant current. 712 
ELECTROTONUS. 
[Sec. 333. 
nerve outside the electrodes, i. e., in the extrapolar area. [The positive pole 
or the condition of anelectrotonus increases the electromotivity, while the neg- 
ative pole or cathelectrotonus diminishes it, exactly the opposite of what ob- 
tains with the excitability.] This condition is called electrotonus (du Bois- 
Reymond, 1843). 
The electrotonic current is strongest not far from the electrodes, and it may be twenty-five 
times as strong as the nerve-current of rest ($ 331, 5); it is greater on the anode than on the 
cathode side; it undergoes a negative variation like the resting nerve-current during tetanus; 
it occurs at once on closing the constant current, although it diminishes uninterruptedly at the 
cathode [du Bois-Reymond). On the contrary, between the electrodes, besides the polarizing 
current itself, there is no obvious electrotonic increase of the current to be observed [Hermann). 
These phenomena take place only as long as the nerve is excitable. If the nerve be ligatured 
in the projecting part in the galvanometer circuit, the phenomena cease in the ligatured part. 
The above-described galvanic electrotonic changes of the extra-polar part are absent in non- 
medullated nerve-fibres, whilst, on the contrary, the physiological electrotonus is present. 
The physiological electrotonus of medullated nerves can be set aside by treating medullated 
nerves with ether, whilst the physical phenomena remain [Biedermann). 
The negative variation (jJ 332) occurs more rapidly than the electrotonic increase of the current, 
so that the former is over before the electro-motive increase occurs. The velocity of the electro- 
tonic change in the current is less than the rapidity of propagation of the excitement in the 
nerves—being only 8 to 10 metres per second ( Tsckirjew, Bernstein). 
“ The secondary contraction from a nerve ” depends upon the electrotonic state. If the 
sciatic nerve of a frog’s nerve-muscle preparation be placed on an excised nerve, and if a con- 
stant current be passed through the free end of the latter—non-electrical stimuli being inactive 
—the muscles contract. This occurs because the electrotonizing current in the excised nerve 
stimulates the nerve lying on it. By rapidly closing and opening the current, we obtain “ sec- 
ondary tetanus from a nerve ” (p. 708). 
[Paradoxical Contraction.—Exactly the same occurs when the current is 
applied to one of the two branches into which the sciatic nerve of the frog 
divides. The sciatic nerve of the frog divides at the lower end of the thigh 
into the peroneal and tibial branches. If the sciatic nerve be divided above, 
and the peroneal branch be also divided and stimulated with the constant cur-, 
rent, the muscles supplied by the tibial branch will contract. There is no con- 
traction of the muscle if the peroneal nerve be ligatured.] 
Polarizing After-Currents.—When the constant current is opened, there are after-cur- 
rents depending upon internal polarization (§ 328). In living nerves, muscle, and electrical 
organs this internal polarization current, when a strong primary current of very short duration is 
used, is always positive, i. e., has the same direction as the primary current. Prolonged dura- 
tion of the primary current ultimately causes negative polarization. Between these two is a 
stage when there is no polarization. Positive polarization is especially strong in nerves when the 
primary current has the direction of the impulse in the nerve; in muscle, when the primary 
current is directed from the point of entrance of the nerve into the muscle towards the end of 
the muscle (g 334, II). 
4. Muscle-Current during Electrotonus.—The constant current also 
produces an electrotonic condition in muscle ; a constant current in the same 
direction increases the muscle-current, while one in an opposite direction 
weakens it, but the action is relatively feeble. 
[Electrotonic Phenomena in Conductors.—Matteucci found that a metallic wire sur- 
rounded by a moist conductor, when traversed by a galvanic current, exhibits currents possessing 
the properties of electrotonic currents of nerves. He also found that the currents ceased if the 
wire was of zinc, and the envelope a saturated solution of zinc sulphate. This shows that 
these currents were due to polarization between the core and the fluid. Hermann finds that 
the currents only obtain when a polarizable core is present. A straw without joints, if filled 
with a saturated solution of common salt, or the tentacles of a lobster when moistened with 
saline solution, and traversed by a constant current, exhibit similar electrotonic currents 
[He ring).'] 
[Effect of Stimulation on the Polarization of Nerve.—I. During the flow of the 
polarizing current.—When a constant current is being passed through a piece of nerve, stimu- 
lation of the nerve causes a positive variation of the current [Griinhagen, Hermann). This is 
due, not to a change in the resistance of the nerve, but probably to a change in the intensity of Sec. 333.] 
THEORIES OF MUSCLE-CURRENTS. 
the excitatory process as it passes along the polarized nerve. When the cathode of the polar- 
izing current lies between the led-ofif area and the point of stimulation, the positive variation 
increases at first as the strength of the polarizing current is increased, then diminishes, and finally, 
with a current which is not very strong, disappears. The nerve-impulse is, in fact, completely 
blocked by the cathode (Hermann).] 
[If at this stage the nerve be stimulated in the intrapolar area, the positive variation can still 
be obtained. When the anode is next the point of stimulation, the stimulating electrodes being 
extrapolar, a limiting density of the polarizing current can also be reached for which stimulation 
has no effect. This limit is far higher than for the cathode (G. N. Stewart).'] 
[When the extrapolar regions of a nerve through which a constant current is being passed are 
connected with a galvanometer, it is seen that on stimulation the electrotonic currents, both 
anodic and cathodic, undergo a negative variation {Bernstein). This is true only for current- 
densities below a certain limit. As the current is strengthened the negative variation on the 
anodic side gives place to a positive variation. This stage is reached with greater difficulty the 
greater is the distance between the region of the nerve led off to the galvanometer and the region 
traversed by the polarizing current (G. N. Stewart).] 
[II. After the opening of the polarizing current.—When a voltaic current is passed 
through a nerve and the intrapolar region of the nerve connected with a galvanometer, immedi- 
ately after the opening of the current the galvanometer may show, according to the strength of 
the current used and its time of closure, a deflection in the same direction as the current (posi- 
tive polarization deflection), or in the opposite direction (negative polarization deflection), or a 
double deflection, first in the opposite, and then in the same direction (du Bois-Reymond).] 
[If the nerve be stimulated as soon as the image has come to rest, there will be a movement 
in the opposite direction to the polarizing current. Above a certain limit of current-density the 
effect is less when the excitation has to pass the anode than when it has to pass the cathode 
(G. N Stewart).] 
[When a voltaic current is passed through a nerve and the extrapolar regions connected with 
a galvanometer, immediately after the opening of the polarizing current, the galvanometer indi- 
cates, in the case of the cathodic area, a deflection in the same direction as the polarizing cur- 
rent ; in the case of the anodic area a main deflection in the opposite direction, preceded under 
certain conditions by a smaller and more transitory deflection in the same direction.] 
[When the anodic region is connected with the galvanometer, and the nerve is stimulated, the 
image moves in the direction of diminution of the main after-current. When the cathodic 
region is connected with the galvanometer the movement produced by stimulation is in the 
direction of increase of the after-current, but where the polarizing current has been closed only 
for a very short time it is in the opposite direction.] 
[The electromotive effects of stimulation in polarized nerves may be all explained on the 
assumption that during the flow of the polarizing current the conductivity for the nerve-impulse 
is less in the neighborhood of the cathode than in the neighborhood of the anode, and that 
after the opening of the current this relation is reversed. This assumption is borne out by the 
results of experiments on muscular contraction. When a fairly strong voltaic current is being 
passed through a nerve, stimulation of the middle point of the intrapolar region causes contrac- 
tion more readily when the excitation has to pass the anode than when it has to pass the 
cathode. After the opening of the current the reverse is the case (G. N. Stewart).] 
334. THEORIES OF MUSCLE- AND NERVE-CURRENTS. 
—I. Molecular or pre-existence Theory.—To explain the currents in 
muscle and nerve, du Bois-Reymond proposed the so-called molecular theory. 
According to this theory, a nerve or muscle fibre is composed of a series of 
small electro-motive molecules arranged one behind the other, and surrounded 
by a conducting indifferent fluid. The molecules are supposed to have a 
positive equatorial zone directed towards the surface, and two negative polar 
surfaces directed towards the transverse section. Every fresh transverse section 
exposes new negative surfaces, and every artificial longitudinal section new 
positive areas. 
This scheme explains the strong currents,—when the longitudinal surface is connected 
with the — transverse surface, a current is obtained from the former to the latter,—but it does 
not explain the feeble currents. To explain their occurrence we must assume that, on the one 
hand, the electro-motive force of the molecules is weakened with varying rapidity at unequal 
distances from the equator; on the other, at unequal distances from the transverse section. 
Then, of course, differences of electrical potential obtain between the stronger and the feebler 
molecules. 
Parelectronomy.—But the natural transverse section of a muscle, i. <?., the end of the tendon, 714 
THEORIES OF MUSCLE-CURRENTS. 
[Sec. 334. 
is not negative, but more or less positive electrically. To explain this condition, du Bois- 
Reymond assumes that on the end of the tendon there is a layer of electro-positive muscle- 
substance. He supposes that each of the peripolar elements of muscle consists of two bipolar 
elements, and that a layer of this half element lies at the end of the tendon, so that its positive 
side is turned towards the free surface of the tendon. This layer he calls the “ parelectrono- 
mic layer.” It is never completely absent. Sometimes it is so marked as to make the end of 
the tendon -f- in relation to the surface. Cauterization destroys it. [It is supposed to be favored 
by cold.] 
The negative variation is explained by supposing that during the action of a muscle and 
nerve the electro-motive force of all the molecules is diminished. During partial contraction 
of a muscle, the contracted part assumes more the character of an indifferent conductor, which 
now becomes connected with the negative zone of the passive contents of the muscular fibres. 
The electrotonic currents beyond the electrodes in nerves must be explained. To explain the 
electrotonic condition, it is assumed that the bipolar molecules are capable of rotation. The 
polarizing current acts upon the direction of the molecules, so that they turn their negative 
surfaces towards the anode and their positive surfaces to the cathode, whereby the molecules of 
the intrapolar region have the arrangement of a Volta’s pile. In the part of the nerve outside 
the electrodes, the further removed it is, the less precisely are the molecules arranged. Hence, 
the swing of the needle is less the further the extrapolar portion is from the electrodes. 
II. Difference or Alteration Theory.—The difference theory was pro- 
posed by L. Hermann, and, according to him, the four following considerations 
are sufficient to explain the occurrence of the galvanic phenomena in living 
tissues :—(i) Protoplasm, by undergoing partial death in its continuity, whether 
by injury or by (horny or mucous) metamorphosis, becomes negative towards 
the uninjured part. (2) Protoplasm, by being partially excited in its con- 
tinuity, becomes negative to the uninjured part. (3) Protoplasm, when partially 
heated in its continuity, becomes positive, and by cooling negative, to the 
unchanged part. (4) Protoplasm is strongly polarizable on its surface (muscle, 
nerve), the polarization constants diminishing with excitement and in the process 
of dying. 
Streamless Fresh Muscles.—It seems that passive, uninjured, and abso- 
lutely fresh nerves and muscles are completely devoid of a current, e.g., the 
heart (Engelmann), also the musculature of fishes while still covered by the 
skin. 
[According to Hermann, the currents obtained from muscle are due to injury 
of the muscle-substance, whereby a difference of potential is set up, the injured 
part being negative to the uninjured. In fact, it is impossible to isolate a 
muscle without injuring it, owing to its connections. Frogs exhibit skin-c.ur- 
rents after the skin is destroyed ; the muscles still exhibit currents, but Her- 
mann explains this by the action of the irritant used to destroy the skin, also 
affecting the muscle. In fishes, however, there are no skin-currents, and if 
they be curarized, absolutely no current is obtained from their uninjured muscles 
{Hermann). The heart also when passive and uninjured gives no current, i. <?., 
it is iso-electrical, although it exhibits an action-current when it contracts, and 
every injured part in it possesses a negative electrical potential with reference 
to the rest.] 
L. Hermann also finds that the muscle-current is always developed after a time, which is very 
short, when a new transverse section is made. [By means of his “ Fall-rheotom ” an arrange- 
ment whereby a weight, covered with shagreen, injured a muscle, and at the same time closed 
and opened a galvanometer circuit, Hermann was able to show that the current—demarcation- 
current—took a certain time to develop. Had it been pre-existent, as supposed by du Bois- 
Reymond, this ought not to have been the case.] 
Demarcation-Current.—Every injury of a muscle or nerve causes at the 
point of injury {demarcation surface) a dying substance, which behaves nega- 
tively to the positive intact substance. The currenPthus produced is called by 
Hermann the “ demarcation-current." If individual parts of a muscle be moist- 
ened with potash salts or muscle-juice, they become negatively electrical; if 
these substances be removed these parts cease to be negative {Biedermami). Sec. 334.] 
THEORIES OF MUSCLE-CURRENTS. 
715 
It appears that all living protoplasmic substance has a special property, whereby injury of a 
part of it makes it, when dying, negative, while the intact parts remain positively electrical. 
Thus, all transverse sections of living parts of plants are negative to their surface (Buff); and 
the same occurs in animal parts, eg., glands and bones. 
Engelmann made the remarkable observation that the heart and smooth muscle again lose 
the negative condition of their transverse section, when the muscle-cells are completely dead, as 
far as the cement-substance of the nearest cells; in nerves, when the divided portion dies, as far 
as the first node of Ranvier. When all these organs are again completely streamless, then the 
absolutely dead substance behaves essentially as an indifferent moist conductor. Muscles 
divided subcutaneously and healed do not exhibit a negative reaction of the surface of their 
section. 
All these considerations go to show that the pre-existence of a ctirrent in 
living uninjured tissues can no longer be maintained. 
Theoretical.—Griinhagen and L. Hermann explain the electrotonic currents as being due 
to internal polarization in the nerve-fibre between the conducting core of the nerve and the 
enclosing sheaths. Matteucci found that, when a wire is surrounded with a moist conductor, and 
the covering placed in connection with the electrodes of a constant current, currents similar to 
the electrotonic currents in nerves, and due to polarization, are developed. If either the wire or 
the moist covering be interrupted at any part, then the polarization current does not extend be- 
yond the rupture (p. 712). The polarization developed on the surface of the wire by its transi- 
tion-resistance causes the conducted current to extend much beyond the electrodes. 
Muscles and nerves consist of fibres, surrounded by indifferent conductors. As soon as a con- 
stant current is closed, on their surface, internal polarization is developed, which produces the 
electrotonic variation ; it disappears again on opening or breaking the current. Polarization is 
detected by the fact that, in living nerve, the galvanic resistance to conduction across a fibre is 
about'five times, and in muscles about seven times, greater than in the longitudinal direction. 
Action-Currents.—The term “ action-current ” is applied by L. Her- 
mann to the currents obtained during the activity of a muscle or nerve. 
When a single contraction-wave passes along a muscular fibre, connected 
at two points with a galvanometer, then that point through which the wave is 
just passing is negative to the other. Occasionally, in excised muscles, local con- 
tractions occur, and these points are negative to the other passive parts of the 
muscle (.Biedermann). In order, therefore, to explain the currents obtained 
from a frog’s leg during tetanus, we must assume that the end of the fibre 
which is negative participates less in the excitement than the middle of the fibre. 
But this is the case only in dying or fatigued muscles. 
According to § 336, D, the direct application of a constant current to a muscle causes contrac- 
tion first at the cathode, when the current is closed, and, when it is opened, at the anode. This 
is explained by assuming that, during the closing contraction, the muscle is negative at the 
cathode, while with the opening contraction the negative condition is at the anode. 
If a muscle be thrown into contraction by stimulating its nerve, then the wave of excite- 
ment travels from the entrance of the nerve to both ends of the muscle, which also behave 
negatively to the passive parts of the muscle. According to the point at which the nerve enters 
the muscle the ascending or descending wave of excitement will reach the end (origin or inser- 
tion) of the muscle sooner than the other. On placing such a muscle in the galvanometer cir- 
cuit, then at first that end of the muscle will be negative which lies nearest to the point of 
entrance of the nerve (e.g., the upper end of the gastrocnemius), and afterwards the lower end. 
Thus, there appear rapidly after each other, at first a descending—or diphasic—current in the 
galvanometer circuit, of course reversed within the muscle itself ( Sig. Mayer) (§ 332, 4). 
The same occurs in the muscles of the human fore-arm. When these were caused to con- 
tract through their nerves, at first the point of entrance of the nerve (10 cm. above the elbow- 
joint) was negative, and then followed the ends of the muscles when the contraction-wave, with 
a velocity of 10 to 13 metres per second, reached them (L. Hermann) ($ 399, 1). 
If a completely uninjured, streamless muscle be made to contract directly and in toto, then 
neither during a single contraction, nor in tetanus, is there a current, because the whole of the 
muscle passes at the same moment into a condition of contraction. 
Dying Nerve.—Hermann also supposes that the contents of dying and active nerves behave 
negatively to the passive normal portions. 
Imbibition Currents.—When water flows through capillary spaces, this is accompanied by 
an electrical movement in the same direction (Quincke, Zollner). Similarly, the forward move- 
ment of water in the capillary interspaces of non-living parts (pores of a porcelain plate) is also 716 
EXCITABILITY DURING ELECTROTONUS. 
[Sec. 334. 
connected with electrical movements, which have the same direction as the current of water. 
The same effect occurs in the movement of water, which results in that condition known as 
imbibition of a body. We must remember that at the demarcation surface of an injured nerve or 
muscle imbibition takes place ; that also at the contracted parts of a muscle imbibition of fluid 
occurs (§ 227, II); and that during secretion there is a movement of the fluid particles. 
In plants, electrical phenomena have been observed during the passive bending of vegetable 
parts (leaves or stalks), as well as during the active movements which are associated with the 
bending of certain parts, e.g., as in the mimosa and dionaea (Burdon-Sanderson). These 
phenomena are perhaps explicable by the movement of water which must take place in the inte- 
rior of the vegetable parts (A. G. Knnkel). The root-cap of a sprouting plant is negative to the 
seed coverings (Hermann); the cotyledons positive to the other parts of the seedling (Muller- 
Hettlingen). In the incubated hen’s egg, the embryo is -f- , the yelk— (.Hermann and v. 
Gendre). 
335. ELECTROTONIC ALTERATION OF THE EXCITA- 
BILITY.—Cause of Electrotonus. If a certain stretch of a living nerve 
be traversed by a constant electrical or “ polarizing ” current, it passes into 
a condition (.Ritter, 1802, and others) which du Bois-Reymond called the 
electrotonic condition, or electrotonus, whereby its vital properties, includ- 
ing its excitability, conductivity, and electromotivity, are modified. 
Here we shall consider the electrotonic variation of the excitability. 
This condition of altered excitability extends not only over the part actually 
Scheme of the electrotonic excitability, 
Fig. 494. 
traversed by the current, i.e., the intrapolar portion, but it is communicated to 
the entire nerve, i.e., to the extrapolar portions. Pfluger discovered the fol- 
lowing laws of electrotonus :— 
At the positive pole or anode the excitability is diminished—this is the 
region of anelectrotonus ; at the negative pole or cathode (K) it is increased 
—this is the region of cathelectrotonus. The chances of excitability are most 
marked in the regions of the poles themselves (fig. 494, A). 
Indifferent Point.—In the intrapolar region a point must exist where 
the anelectrotonic and cathelectrotonic regions meet, where, therefore, the 
excitability is unchanged; this is called the indifference or neutral point. 
This point lies nearer the anode (i) with a weak current, but with a strong cur- 
rent nearer the cathode (/" ) ; hence, in the first case, almost the whole intrapolar 
portion is more excitable; in the latter, less excitable. [Expressed otherwise, 
a weak current increases the area over which the negative pole prevails, while 
the reverse is the case with a strong current. Or in the intrapolar region, the 
diminution of excitability extends as the strength of the current increases, or, to 
put it otherwise, with an increasing strength of current the indifferent point 
moves from the positive to the negative pole.] Very strong currents greatly 
diminish the conductivity at the anode, and, indeed, may make the nerve 
completely incapable of conduction at this part. Sec. 335.] 
EXCITABILITY DURING ELECTROTONUS. 
717 
At the cathode also, but only after the polarizing current has passed for some time through 
the nerve (Werigo), the excitability is diminished, and the nerve in this area is rendered 
incapable of conduction (Griinhagen). 
Extrapolar Region.—The extrapolar area, or that lying outside the 
electrodes, is greater the stronger the current. Further, with the weakest cur- 
rents, the extrapolar anelectrotonic area is greater than the extrapolar cath- 
electrotonic. With strong currents this relation is reversed. 
Fig. 494 shows the excitability of a nerve (W, n) traversed by a constant current in the 
direction of the arrow. The curve shows the degree of increased excitability in the neighbor- 
hood of the cathode {PC) as an elevation above the nerve, diminution at the anode {A) as a 
depression. The curve m, o, i",p, r, shows the degree of excitability with a strong current; 
c, f, iv, h, k, with a medium current; lastly, a, b, i, c, d, with a weak current. 
The electrotonic effect increases with the length of the nerve traversed by the current. The 
changes of the excitability in electrotonus occur instantly when the circuit is closed, while 
anelectrotonus develops and extends more slowly. Cold diminishes electrotonus (Hermann and 
v. Gendre). 
When the polarizing current is opened or broken, at first there is a reversal 
of the relations of the excitability, and then there follows a transition to the 
normal condition of excitability of the passive nerve (Pfliiger). At the very 
first moment of closing, Wundt observed that the excitability of the whole 
nerve was increased. 
I. Proof of Electrotonus in Motor Nerves.—To test the laws of electrotonus, take a frog’s 
nerve-muscle preparation (fig. 486). A constant current (p. 691) is applied to a limited part 
of the nerve by means of non-polarizable electrodes. A stimulus, 
electrical, chemical (saturated solution of common salt), or mechan- 
ical is applied either in the region of the anode or cathode ; and we 
observe whether the contraction which results is greater when the 
polarizing current is opened or closed. We shall consider the fol- 
lowing cases (fig. 495). 
(a) Descending extrapolar anelectrotonus. With a descend- 
ing current we have to test the excitability of the extrapolar region 
at the anode. If the stimulus (common salt) applied at R (while 
the circuit was open) causes in this case (A) moderately strong 
contractions in the limb, then these at once become weaker, or 
disappear as soon as the constant current is transmitted through the 
nerve. After the circuit is opened, the contractions produced by the 
salt again occur of the original strength. 
(b) Descending extrapolar cathelectrotonus (A). The 
stimulus (salt) is at Rj, and the contractions thereby produced are at 
once increased after closing the polarizing current. On opening it 
they are again weakened. 
(c) Ascending extrapolar anelectrotonus (B). The salt lies 
at rx; the moderately strong contractions excited by the salt before 
the current is made become feebler after the current is made. 
(d) Ascending extrapolar cathelectrotonus (B). The salt 
lies at r. In this case we must distinguish according to the strength 
of the polarizing current: (1) When the current is very weak, 
which can be obtained with the aid of the rheocord (fig. 458), on 
closing the polarizing current, there is an increase of the contraction 
produced by salt. (2) If, however, the current is stronger, the 
contractions become either smaller or cease. This is due to the fact 
that with strong currents the conductivity of the nodes is diminished or even abolished (see 
above). Although the salt acts on the excitable nerve, there is no contraction of the muscle, as 
the conduction of an impulse is prevented by the resistance in the nerve. 
The law of electrotonus may also be demonstrated on a completely isolated nerve. 
The end of the nerve is properly disposed upon electrodes connected with a galvanometer, so as 
to obtain a strong nerve-current. If the nerve, when the constant current is closed, is stimu- 
lated in the anelectrotonic area, e. g., by an induction shock, then the negative variation is 
weaker than when the polarizing circuit was open. Conversely, it is stronger when it is stimu- 
lated in the cathelectrotonic area. The currents from the extrapolar areas of a nerve in a con- 
dition of electrotonus, exhibit the negative variation when the nerve is stimulated {Bernstein). 
Fig- 495- 
Method of testing the ex- 
citability in electrotonus. 
R, r, Rj, rv where the 
common salt (stimulus) is 
applied. 718 
ELECTROTONUS LAW OF CONTRACTION. 
[Sec. 335. 
[Tigerstedt, instead of employing an electrical or chemical stimulus to excite the electrotonic 
nerve, used an apparatus like Heidenhain’s tetanometer, whereby the nerve was beaten gently 
with a small ivory hammer. He fully confirms Pfluger’s results.] 
Proof in Man.—In performing this experiment it is important to remember the distribution 
of the current in the body. If both electrodes, for example, be placed over the course of the 
ulnar nerve (fig. 496), the currents entering the nerve at the anode (-j- a a) must diminish the 
excitability; only above and below the anode (at c c) the positive current emerges from the 
nerve and excites cathelectrotonus at these points. Similarly, where the cathode is applied 
(— c e) there is increased excitability, but in higher and lower parts of the nerve, where (at 
a a) the positive current (coming from -|- ) enters the nerve, the excitability is diminished 
(anelectrotonus) (v. Helmholtz, Erb). If we desire to stimulate in the neighborhood of an 
electrode, then we cannot act upon that part of the nerve whose excitability is influenced by the 
electrode. In order, therefore, to stimulate directly the same point on which the electrode acts, 
it is necessary to apply the stimulus at the same time by the electrode itself, e. g., either mechan- 
ically or by conducting the stimulating current through the polarizing circuit (Waller and de 
Watteville). 
II. Proof of Electrotonus in Sensory Nerves.—Isolate the sciatic nerve of a decapitated 
frog. When this nerve is stimulated in its course with a saturated solution of common salt), 
reflex movements are excited in the other leg, the spinal cord being intact. These disappear as 
soon as a constant current is applied to the nerve, provided the salt lies in the anelectrotonic 
area (Pfluger and Zurhelle, Hallsten). 
III. Proof of Electrotonus in Inhibitory Nerves.—To show this, proceed thus : On 
Fig. 496. 
Scheme of the distribution of an electrical current in the nerve on galvanizing the ulnar 
nerve. 
causing dyspnoea in a rabbit, the number of heart beats is diminished, owing to the action of the 
dyspnoeic blood on the cardio-inhibitory centre in the medulla oblongata. If, after dividing the 
vagus on one side, a constant descending current be passed through the other intact vagus, the 
number of pulse-beats is again increased (descending extrapolar anelectrotonus). If, however, 
the current through the nerve be an ascending one, then with weak currents the number of heart- 
beats increases still more (ascending extrapolar cathelectrotonus). Hence, the action of inhib- 
itory nerves in electrotonus is the opposite of that of motor nerves. 
During the electrotonus of muscle, the excitability of the i?itrapola7■ portion 
is altered. The delay in the conduction is confined to this area alone 
(v. Bezold)—compare § 337, 1. 
336. ELECTROTONUS—LAW OF CONTRACTION.—Open- 
ing and Closing Shocks.—A nerve is stimulated both at the moment of the 
occurrence and that of disappearance of electrotonus (/. e., by closing and 
opening the current—Ritter) : (1) When the current is closed, the stimulation 
occurs only at the cathode, i. «?., at the moment when the cathelectrotonus 
takes place (fig. 498). (2) When the current is opened, stimulation occurs 
only at the anode, i. <?., at the moment when the anelectrotonus disappears. 
[This is Pfliiger’s well-known principle—“ A given tract of nerve is stimulated Sec. 336.] 
LAW OF CONTRACTION. 
719 
by the appearance of cathelectrotonus and the disappearance of anelectrotonus— 
not, however, by the disappearance of cathelectrotonus nor by the appearance of 
anelectrotonus. ” From this principle can be deduced the so-called law of con- 
traction.] (3) The stimulation at the occurrence of cathelectrotonus is stronger 
than that at the disappearance of anelectrotonus (Pfliiger). 
Proof of stimulation at the anode at break. Ritter’s Opening Tetanus.—That stimu- 
lation occurs only at the anode when the current is opened, i. e., broken, was proved by Pfliiger 
by means of “ Ritter’s opening tetanus.” Ritter’s tetanus consists in this, that when a constant 
current is passed for a long time through a long stretch of nerve, on opening the current, tetanus 
lasting for a considerable time results. If the current was a descending one [i.e., with the — 
pole next the muscle], then this tetanus ceases at once after section of the intrapolar area, 
a proof that the tetanus resulted from the now separated anode. If the current was an 
ascending one [*. e., with the 4- pole next the muscle], section of the nerve has no effect on 
the tetanus. 
Proof of stimulation at the cathode at make.— Pfliiger and v. Bezold found a further 
proof that the closing or make contraction proceeds from the cathode, and the opening or break 
contraction froyn the anode, by showing that with a descending current, the closing contrac- 
tion in the muscle at the moment of closing occurred earlier, while the opening contraction at 
the moment of opening occurred later; and, conversely, with an ascending current the closing 
contraction occurred later, and the opening contraction sooner. The difference in time corres- 
ponds to the time required for the propagation of the impulse in the intrapolar region ($ 337). 
If a large part of the intrapolar region in a frog’s nerve be rendered inexcitable by applying 
ammonia to it, then only the electrode next the muscle stimulates, i. e., always on closing 
or making a descending current and on opening or breaking an ascending one (Biedermann). 
A. The law of contraction is valid for all kinds of nerves—I. The con- 
traction at the closing or opening of a constant current varies with— 
(a) The direction (Pfaff), and 
{b) The strength of the current (Heidenhain). 
(1) A weak current, in conformity with the third of the above statements, 
causes only a closing contraction, both with an ascending and a 
descending current. The disappearance of electrotonus is so feeble a 
stimulus as not to excite the nerve. 
(2) A medium current causes contractions at make and break, both with 
an ascending and a descending current. 
(3) A strong current causes only a closing contraction with a 
descending current; there is no contraction at break, because with very 
strong currents almost the whole of the intrapolar portion of the electrotonic 
nerve is incapable of conducting an impulse (p. 717); an ascending cur- 
rent causes only a contraction at break for the same reason. With a certain 
strength of current, the muscle remains tetanic while the current is closed 
(“ closing tetanus. ”). 
[The Pfluger’s so-called law of contraction may be formulated as fol- 
lows : R = rest; C = contraction (fig. 497).] 
Strength of Current. 
Ascending. 
Descending. 
On Closing. 
On Opening. 
On Closing. 
On Opening. 
Weak, 
c 
R 
c 
R 
Medium, 
c 
C 
c 
C 
Strong, 
R 
C 
c 
R 
II. In a dying nerve, losing its excitability, according to the Ritter-Valli 
law (§ 325, 7), the law of contraction is modified. In the stage of increased 720 
LAW OF CONTRACTION. 
[Sec. 336. 
excitability, weak currents cause only closing contractions with both directions 
of the current. In the 
following stage, when 
the excitability begins 
to diminish, weak cur- 
rents cause opening 
and closing contrac- 
tions with both cur- 
rents. Lastly, when 
the excitability is very 
greatly diminished, 
the descending current 
is followed only by a 
closing contraction, 
and the ascending by 
an opening contrac- 
tion (.Ritter, 1829). 
III. As the various changes in excitability occur in a centrifugal direction 
along the nerve, we may detect the various stages simultaneously at different 
parts along the course of the nerve. According to Valentin and Fick, the 
living intact nerve shows only a closing contraction with both directions of the 
current, and opening contractions only with very strong currents. 
Eckhard observed that, on opening an ascending medium current applied to the hypoglossal 
nerve of a rabbit, one-half of the tongue exhibited a trembling movement instead of a contrac- 
tion, while on closing a descending current, the same result occurred ($ 297, 3). 
According to Pfliiger, we may represent to ourselves what happens as fol- 
lows : The molecules of the passive nerve are in a certain state of medium 
mobility. In cathelectrotonus the mobility of the molecules is increased, 
in anelectrotonus it is diminished. When the nerve-molecules pass from 
the condition of rest to a more mobile condition, i. <?., the appearance of cath- 
electrotonus; or when they pass from a more stable into a medium state 
of mobility, i. e., the disappearance of anelectrotonus, each condition acts as a 
stimulus. 
B. The law for inhibitory nerves is similar. Moleschott, v. Bezold, 
and Donders have found similar results for the vagus, with this difference, 
that, instead of the contraction of a muscle, there is inhibition of the heart. 
C. For sensory nerves also the result is the same, but we must remember 
that the perceptive organ lies at the central end of the nerve, while in a motor 
nerve it is at the periphery (muscle). Pfluger studied the effect of closing and 
opening a current on sensory nerves by observing the reflex movement 
which resulted. Weak currents cause only closing contractions; medium 
currents both opening and closing contractions; strong descending currents 
only opening contractions; and ascending only closing contractions. Weak 
currents applied to the human skin cause a sensation with both directions of 
the current only at closing; strong descending currents a sensation only at open- 
ing; strong ascending currents a sensation only at closing (Marianini, Matteucci). 
When the current is closed, there is prickly feeling, which increases with the 
strength of the current ( Volta). Analogous phenomena have been observed in 
the sense organs (sensations of light and sound) by Volta and Ritter. 
D. In muscle, the law of contraction is proved thus—by fixing one end of 
the muscle, keeping it tense, so that it cannot shorten, and opening and closing 
the current at this end. The end of the muscle, which is free to move, shows 
the same law of contraction as if the motor nerve were stimulated (v. Bezold). 
ASCENDING 
DESCENDING 
WEAK 
MEDIUM 
STRONG 
Scheme illustrating Pfliiger’s so-called law of contraction {Stirling). 
Fig. 497. Sec. 336.] 
LAW OF CONTRACTION. 
721 
On closing the current, the contraction begins at the cathode ; on opening, at 
the anode (Engelmann). 
[Engelmann’s Experiment.—In order to demonstrate that, when a con- 
stant current is applied to a muscle, stimulation occurs only at the cathode 
when the current is made (closed) and at the anode when it is broken (opened), 
suspend a curarized sartorius of a frog (fig. 498, R), and pass through its upper 
end a constant current. On closing the current the contraction takes place at 
the cathode and the muscle contracts towards (C), but at break it contracts at 
the anode and turns towards (B).] 
E. Hering and Biedermann showed more clearly that both the closing and 
opening contractions are purely polar effects ; when a weak current applied to a 
muscle is made, the first effect is a small contraction, 
limited to the cathodic half of the muscle. Increase of 
the current causes increased contraction, which extends 
to the anode, but which is weaker there than at the 
cathode; at the same time, the muscle remains con- 
tracted during the time the current is made. At break, 
the contraction begins at the anode; even after break- 
ing the current, the muscle for a time may remain con- 
tracted, which condition ceases on making the current 
in the same direction. The law of polar stimulation 
obtains in the case of smooth muscle, e. g., in the 
excised uterus and intestines, in the cutaneous muscle 
of worms and holothurians. Most Rhizopoda show the 
reverse effect, viz., the anodic action on closing the 
current. 
By killing the end of a muscle in various ways the excitability is 
diminished near this part. Hence, at such a place the polar action 
is feeble (van Loon and Engelmann, Biedermann). Touching a part with extract of flesh, 
potash, or alcohol diminishes locally the polar action, while soda salts and veratrin increase it 
(.Biedermann). 
Closing Continued Contraction.—The moderate continued contraction, which is sometimes 
observed in a muscle while the current is closed (fig. 400, O), depends upon the abnormal pro- 
longation of the closing contraction of the cathode when a strong stimulus is used, or during 
the stage of dying, or in cooled winter frogs; sometimes the opening of the current is accom- 
panied by a similar contraction proceeding from the anode (Biedermann). This tetanus is also 
due to the summation of a series of simple contractions ($ 298, III). By acting on a muscle 
with a 2 per cent, saline solution containing sodic carbonate, the duration of the contrac- 
tion is increased considerably, and occasionally the muscle contracts rhythmically ($ 296) 
(Biedermann). - 
If the whole muscle is placed in the circuit, the closing contraction is strong- 
est with both directions of the current; during the time the circuit is closed, a 
continued contraction is strongest when the current is ascending ( Wundt). 
Inhibitory Polar Action on Muscle.—The constant current, when 
applied to a muscle in a condition of continued and sustained contraction, has 
exactly the opposite effect to that on a relaxed muscle. If by means of non- 
polarizable electrodes a constant current be sent through the long axis of a 
muscle in a state of continued contraction (e. g., after poisoning with veratrin or 
through the contracted ventricle), when the current is made, it causes a relax- 
ation beginning at the anode and extending to the other parts; on breaking 
the current applied to a muscle in continued contraction, the relaxation pro- 
ceeds from the cathode. 
Corresponding to this remarkable phenomenon, Biedermann found, as regards the currents in 
the muscle-substance following the ordinary law, that every contracted part is negative to every 
passive section of the muscle. Perhaps the experiment of Pawlow, who found nerve-fibres in 
Fig. 498. 
Scheme of Engelmann’s 
experiment on the sar- 
torius (R) of a frog. 722 
TRANSMISSION OF NERVOUS IMPULSES. 
[Sec. 336. 
the adductor muscle of the mussel, whose stimulation caused relaxation of the muscular contrac- 
tion, may throw some light on this question. 
Ritter’s Opening Tetanus.—If a nerve or muscle be traversed by a con- 
stant current for some time, we often obtain a prolonged tetanus, after open- 
ing the current (Ritter’s opening tetanus, 1798). It is set aside by closing 
the original current, while closing a current in the opposite direction increases 
it (“ Volta’s alternative”). The continued passage of the current in- 
creases the excitability for the opening of the current in the same direction, 
and for the closing of the reverse current; conversely, it diminishes it for the 
closing of the current in the same direction, and for the opening of the reverse 
current {Volta). 
According to Griitzner and Tigerstedt, the cause of the opening contraction is partly due to 
the occurrence of polarizing after-currents ($ 333), and according to Hermann to a diminution of 
the anodic positive polarization. 
Engelmann and Griinhagen explain the occurrence of opening and closing tetanus, thus, as 
due to latent stimulations, drying, variations of the temperature of the prepared nerves, which of 
themselves are too feeble to cause tetanus, but which become effective if an increased excitability 
obtains at the cathode after closure, and at the anode after opening the current. 
Biedermann showed that, under certain conditions, two successive opening contractions can 
be obtained in a frog’s nerve-muscle preparation, the second and later one corresponding to 
Ritter’s tetanus. The first of these contractions is due to the disappearance of anelectrotonus 
in Pfliiger’s sense; the second is explained, like Ritter’s opening tetanus, in Engelmann and 
Griinhagen’s sense. 
Simultaneous action of the constant current and the nerve-current.—Action of two 
currents. In a nerve-muscle preparation used to prove the law of contraction, of course a 
demarcation-current is developed in the nerve ($ 334, II). If an artificial, weak, stimulating 
current be applied to such a nerve, we obtain an interference effect due to these two currents ; 
closing a weak constant current causes a contraction, which, however, is not properly a closing 
contraction, but depends upon the opening (or derivation) of a branch of the demarcation- 
current ; conversely, the opening of a weak constant current may excite a contraction, which is 
really due to the closing of a side branch of the nerve-current, in a secondary circuit through the 
electrodes (Hering, Biedermann, Griitzner). 
If two induction shocks be simultaneously applied to a motor nerve, two cases are possible. 
Either the one shock is so feeble that the nerve is not thereby sufficiently excited to cause a 
contraction, while the other shock causes only a feeble contraction. In this case, the sub- 
maximal shock plays the part of a weak constant current, and the size of the contraction depends 
only upon whether the effective stimulus was applied in the area of the anode or the cathode of 
the submaximal shock (Sewall, Griinhagen, Werigo). If, however, unequal, strong induction 
shocks, each of which is effective—but separated from each other on account of the electrotonic 
action—be applied to a nerve, then the result is as if the stronger alone was active. The feebler 
wave of excitation passes completely into the stronger one (Griinhagen, Werigo). 
337. TRANSMISSION OF NERVOUS IMPULSES.—1. If a 
motor nerve be stimulated at its central end (1) a condition of excitation 
is set up, and (2) an impulse is transmitted along the nerve to the muscle 
with a certain velocity. The latter depends on the former and represents the 
function of conductivity. The velocity is about 28 metres [about 90 feet] 
per second {v. Helmholtz), and for the human motor nerves 33.9 [100 to 120 
feet per second] {v. Helmholtz and Baxt). 
The velocity is less in the visceral nerves, e. g., in the pharyngeal branches of the vagus 8.2 
metres [26 feet] (Chauveau) ; in the motor nerves of the lobster 6 metres [18 feet] (Fredericq 
and van de Velde). 
Modifying Conditions.—The velocity is influenced by various condi- 
tions : Temperature.—It is lessened considerably by cold (v. Helmholtz), 
but both high and low temperatures of the nerve (above or below 15° to 250 
C.) lessen it {Steiner and Trojtzky), as also the action of curare, and the 
electrotonic condition {v. Bezold). The condition of anelectrotonus 
diminishes the velocity, while cathelectrotonus increases it {Rutherford, 
Wundt). It varies also with the length of the conducting nerve, but it Sec. 337.] 
VELOCITY OF NERVOUS IMPULSES. 
723 
increases with the strength of the stimulus (v. Hehnholtz and Baxt), although 
not at first (v. Vintschgau). 
Methods.—V. Helmholtz in 1850 estimated the velocity of the nerve-impulse in a frog’s 
motor nerve by a method which is not now usually employed. 
[The method now generally used is that shown in the scheme, fig. 499. Use 
a pendulum or spring myograph (fig. 393), and suspend in a suitable manner 
a frog’s gastrocnemius (in'), with a long portion of the sciatic nerve (N) dis- 
sected out, by fixing the femur in a clamp (/), while the tendo-Achillis is fixed 
to a lever, which inscribes its movements on the smoked glass plate (P) of the 
myograph ; place the key of the myograph (2) in the circuit with the battery 
(B), and the primary circuit of the induction machine (I). To the secondary 
coil (II), attach two wires, and connect them with a commutator without 
cross-bars (C). Connect the other binding screws of the commutator with two 
pairs of wires, arranged so that one pair can stimulate the nerve near the muscle 
{a) and the other at a distance from it (b). When the glass plate flies from one 
side to the other, the tooth 
(3) on its framework opens 
the key (2) in the primary 
circuit, and if the commu- 
tator be in the position in- 
dicated, then the induced 
current will stimulate the 
nerve at a, and a curve will 
be obtained on the glass 
plate. Rearrange the pen- 
dulum as before, i.e., near 
the muscle, close the key in 
the primary circuit, but turn 
the handle of the commuta- 
tor, and allow the glass plate 
to fly again. 
This time the induced cur- 
rent will stimulate the nerve 
at b, i.e., away from the 
muscle, and a second con- 
traction, a little later than 
the first one, will be obtained. Register the velocity of the glass plate by 
means of a tuning-fork, and the curve obtained will be something like fig. 500, 
although this curve was obtained on a cylinder travelling at a uniform rate, and 
the curves were drawn on abscissae at different levels. The difference between 
the beginning of the a (1) and b (2) curves indicates the time that the nerve- 
impulse took to travel from b to a. This time is measured by the tuning-fork, 
and if the distance between the points a and b is known, then the calculation 
is a simple one. Suppose the stretch of nerve between a and b to be 2 inches, 
and the time required by the impulse to travel from a to b to be second, 
then we have the simple calculation—2 inches : 12 inches : : or 80 
feet per second. In fig. 500 the experiment was made on man ; the curve 1 
was obtained by stimulating the nerve near the muscle, and 2 when the nerve 
was stimulated at a distance of 30 centimetres. The interval between the ver- 
tical lines corresponds to second, i. e., the time required by the nerve- 
impulse to pass along 30 centimetres of nerve, which is equal to a velocity of 30 
metres (90 feet) per second.] 
In man, v. Helmholtz and Baxt estimated the velocity of the impulse in the median nerve 
Fig. 499. 
Scheme for measuring the velocity of nerve energy, f, 
clamp for femur; m, muscle; N, nerve; a, near, b, re- 
moved from C, commutator; II, secondary; I, primary 
spiral of induction machine; B, battery; 1,2,key; 3, 
tooth on the smoked plate. [Sec. 337. 
724 
VELOCITY OF NERVOUS IMPULSES. 
by causing the muscles of the ball of the thumb to write off their contractions on a rapidly revolv- 
ing cylinder. [In this case the “ pince myographique ” of Marey (fig. 409) may be used ($ 708). 
The ends of the pince are applied so as to embrace the ball of the thumb, so that when the 
muscles contract, the increase in thickness of the muscles expands the pince, which acts on a 
Marey’s tambour, by which the movement is transmitted to another tambour provided with a 
writing style, and inscribing its movements upon a rapidly moving surface, either rotatory or 
swinging.] The nerve is stimulated at one time in the axilla and again at the wrist. Two 
curves are obtained, which, of course, do not begin at the same time. The difference in time 
between the beginning of the two curves is the time taken by the impulse to traverse the above- 
mentioned length of nerve. [The time is easily ascertained by causing a tuning-fork of a known 
rate of vibration to write its movements under the curves.] 
According to Bernstein, the stimulus which traverses the motor nerve to the 
end-plate and thus excites the muscle must last on an average 0.0032 sec. (frog). 
2. In the sensory nerves of man, the velocity of the impulse is probably 
about the same as in motor nerves. The rates given vary between 94 to 30 
metres [280 to 90 feet] per second (v. Helmholtz). 
Method of Investigation.—Two points are chosen, as far apart as possible, and at unequal 
distances from the brain, and they are successively excited by a momentary stimulus, e.g., an 
opening induction shock applied successively to the tip of the ear and the great toe. The 
moment of the application of the stimulus is indicated on the registering surface. The person 
experimented on is provided with a key in connection with an electric arrangement, by which 
he can mark on the registering surface the moment he feels the sensation in each case ($ 374). 
Fig. 500. 
I, curve obtained on stimulating a nerve (man) near the muscle; 2, when the stimulus was 
applied to the nerve at a distance from the muscle; D, vibrations of a tuning-fork (250 per 
second). 
Pathological.—The conduction in the cutaneous nerves is sometimes greatly delayed in 
alterations of the cutaneous sensibility, in certain diseases of the spinal cord (§ 364). The 
sensation itself may be unchanged. Sometimes only the conduction for painful impressions is 
retarded, so that a painful impression on the skin is first perceived as a tactile sensation, and 
afterwards as pain, or conversely. When the interval of time between these two sensations is 
long, then there is a distinctly double sensation (Naunyn). It is rarely that voluntary move- 
ments are executed much more slowly from causes depending on the motor nerves, but occa- 
sionally the time between the voluntary impulse and the contraction is lengthened, but there may 
be in addition slower or longer continued contraction of the muscle. In tabes dorsalis, or loco- 
motor ataxia, the discharge of reflex movements is delayed; it is slower with thermal stimuli (6o°) 
than with cold ones (0.50 C., Ewald). 
338. DOUBLE CONDUCTION IN NERVES.—Conductivity is 
that property of a living nerve in virtue of which, on the application of a 
stimulus, it transmits an impulse. [The nature of a nerve-impulse is en- 
tirely unknown; we may conveniently term the process nerve-motion, but 
there is some reason to believe that nerve-energy is transmitted by some sort of 
molecular vibration.] The conductivity is destroyed by all influences or 
conditions which injure the nerve in its continuity (section, ligature, compres- 
sion, destruction by chemical agents) ; or which abolish the excitability at any 
part of its course (absolute deprival of blood; certain drugs, e.g., curare for 
the termination of motor nerves ; also strong anelectrotonus (§335).) [If a 
motor nerve be ligatured, and then the nerve be stimulated above the ligatured Sec. 338.] 
CONDUCTION IN NERVES. 
725 
point, the muscle does not contract. The impulse requires integrity of the 
axis-cylinders in order to its conduction.] 
[The following are the laws of conduction in a nerve:— 
(1) There must be continuity and integrity of the nerve. 
(2) The law of isolated conduction. 
(3) There is double conduction in a nerve. 
(4) The nerve-fibres possess independent excitability, and the result of 
stimulation depends on the structure in which the nerve-fibre ends. 
If the fibre ends in a muscle, the result is motion ; if in a gland, 
secretion ; in certain cells of the brain, sensation.] 
[Law of Isolated Conduction.—Conduction always takes place only in 
the continuity of the fibres stimulated, the impulse never being transferred to 
adjoining nerve-fibres.] 
Double Conduction in Nerves.—Although apparently conduction in 
motor nerves takes place only in a centrifugal direction towards the muscles, 
and in sensory nerves in a centripetal direction, i. e., towards the centre, never- 
theless, experiment has proved that a nerve conducts an impulse in both direc- 
tions, just as in a non-living conductor. If a pure motor or sensory nerve be 
stimulated in its course, an impulse is propagated at the same time in a centri- 
fugal and in a centripetal direction. This is the phenomenon of “ double con- 
duction. ’ ’ 
Proofs of Double Conduction.—1. If a nerve be stimulated, its electro- 
motive properties are affected both above and below the point of stimulation 
(see Negative Variation in Nerves, § 332). 
2. Electrical Nerves.—If the posterior free end of the electrical centri- 
fugal nerves of the malapterurus be stimulated, the branches given off above the 
point of stimulation are also excited, so that the whole electrical organ dis- 
charges its electricity (Babuchin, Mantey). 
3. Kiihne’s Experiments.—(a) The sartorius of the frog has no nerve- 
fibres at its upper and lower ends. If the lower end be cut off, and if the 
lower third of the muscle be suspended and divided vertically, 
on stimulating mechanically one apex of the muscle, then the 
impulse passes in the motor nerves centripetally to the place 
where the nerve-fibre bifurcates in the muscle, and from thence 
centrifugally into the other or non-stimulated apex, and 
causes it to contract. 
[(£) The Gracilis of the frog is divided into a larger (L) 
and smaller portion (K) by a tendinous inscription running 
across it (fig. 501). The nerve (N) enters at the hilum in 
the larger portion, bifurcates, and gives a branch (k) 
to the smaller portion and another to the larger portion of 
the muscle. Let the muscle be cut as shown in fig. 501, 
avoiding injury to the nerves, so that only the nerve-twig (£) 
connects the larger and smaller portions of the muscle. If 
the tongue or tip of muscle (Z) with its nerves be stimulated, contraction 
occurs both in L and K, which is due to centripetal conduction in the motor 
nerve. The nerve-fibres divide dichotomously above where the nerves are 
given off to the portions L and K.] 
[If the inscription be left, and the lower tip of the muscle (which is devoid 
of nerves) be stimulated, only the lower and not the upper part twitches; but 
if a part of the muscle containing nerves common to both parts be stimulated, 
then both parts of the muscle contract. This also proves that pure muscular 
excitation does not travel backwards from the muscle to the nerves. How this 
comes about we are entirely ignorant.] 
Fig. 501. 
Kiihne’s Gracilis 
experiment. 726 
ELECTRO-THERAPEUTICS. 
[Sec. 338. 
The following experiments used to be cited as proofs, but they do not stand 
the test of criticism. 
4. Union of Motor and Sensory Nerves.—If the hypoglossal and lingual nerves be 
divided in a dog, and if the peripheral end of the hypoglossal be stitched, so as to unite with 
the central end of the lingual (Bidder), then, several months after the union and restitution of 
the nerves, stimulation of the central end of the lingual causes contraction in the corresponding 
half of the tongue. Hence it has been assumed that the lingual, which is the sensory nerve of 
the tongue, must conduct the impulse in a peripheral direction to the end of the hypoglossal. 
This experiment is not conclusive, as the trunk of the lingual receives high up the centrifugal 
fibres from the seventh, viz., the chorda tympani, which may unite with or grow into the hypo- 
glossal. Further, if the chorda be divided and allowed to degenerate before the above-described 
experiment is made, then no contractions occur on stimulating the lingual above the point of 
union (g 349). 
5. Bert’s Experiment.—Paul Bert removed the skin from the tip of the tail of a rat, and 
stitched it into the skin of the back of the animal, where it united with the tissues. After the first 
union had taken place, the tail was then divided at its base, so that the tail, as it were, grew out 
of the skin on the back of the animal. On stimulating the tail, the animal exhibited signs of 
sensation. For the explanation of this experiment, see \ 325. 
33g. ELECTRO-THERAPEUTICS—REACTION OF DEGENERATION.— 
Electricity is frequently employed for 
therapeutical purposes, the rapidly 
interrupted current of the induction 
machine, or Faradic current, be- 
ing frequently used (especially since 
Duchenne, 1847), the magneto-elec- 
trical apparatus, and the extra-cur- 
rent apparatus. The constant or 
galvanic current is also used, es- 
pecially since Remak’s time, 1855 
(2 33°)- 
I. In paralysis, Faradic currents 
are applied, either to the muscles 
themselves {Duchenne'),ox the points 
of entrance of the motor nerves, by 
means of suitable electrodes, or 
rheophores covered with sponge, 
&c., and moistened (v. Ziemssen). 
[Rheophores. — Many different 
forms are used, according to the or- 
gan or part to be stimulated, or the 
effect desired. When electricity is 
applied to the skin to remove anaes- 
thesia, hypersesthesia, or altered 
sensibility, and we desire to limit 
the effect to the skin alone, then the 
rheophores are applied dry, and are 
usually made of metal. If, however, 
deeper-seated structures, as muscles 
or nerve-trunks, are to be affected, 
the skin must be well moistened 
and softened by sponging with warm 
water, while the rheophores are fitted with sponges moistened with common salt and water, which 
diminishes the resistance of the skin to the passage of electricity (figs. 502-504).] 
In faradizing the paralyzed muscle, the object is to cause artificial movements in it, and thus 
prevent the degeneration which it would otherwise undergo, merely from inaction. If, in 
addition to the motor-nerves, its trophic nerves are also paralyzed, then a muscle atrophies, 
notwithstanding the faradization ($ 325, 4). The use of the induced current also improves a 
paralyzed muscle, as it increases the blood-stream through it, while it affects the metabolism 
of the muscle reflexly. In addition, weak currents may restore the excitability of enfeebled 
nerves (v. Bezold, Engelmann). 
The figs. 505-508 indicate the positions of the motor points of the extremities, where, by 
stimulating at the entrance of the nerve, each muscle may be caused to contract singly. In § 
349 the motor points of the face, and in \ 347 those of the neck, are indicated. 
The constant current may be employed as a stimulus, when it is closed and opened, in the 
Fig. 502. 
F'g- 503- 
Fig. 504. 
Double sponge rheophore. 
Disc rheophore. 
Metallic brush. Sec. 339.] 
ELECTRO-THERAPEUTICS. 
727 
form of an interrupted current, by altering its direction and increasing or diminishing its 
intensity, but it also causes a polar action. On closing the current, the nerve at the cathode is 
N. radialis. 
SI. triceps (caput ex .) 
M. triceps 
I (>aput long) 
SI. supinator long. 
SI. brachial, intern 
SI. deltoideus 
(post. half). 
. (N. axillaris) 
M. radia . ext. brev 
Si. radial, ext. long. 
M ulnar, ext. 
M. extens digit, communis. 
M. extens. digit, min 
M supinat. buev. / 
M. abduct, pollic. long. 
M. extens. indicis. 
SI. extens. pollic. brev. 
SI. extens. poll. long. 
Mm. inteross. dorsal. I, II, III, et IV. 
(N. uluaris.) 
SI. abduct, digit, min. (N. ulnaris.) 
Motor points of the radial nerve and the muscles supplied by it; dorsal surface. 
Fig. 505- 
stimulated; similarly, on opening the current, at the anode ($ 336). Thus, when the current 
is closed, the excitability of the nerve is increased at the cathode ($ 335), which may act 
41. deltoideus (ant. half) N. axillaris. 
N. musculo-cutaneus. 
M. biceps brachii. 
M. brach. anticus. 
N. medianus 
M. pronator teres. 
M. abductor pollic. brer. 
M. flex, digitor. commun. profund 
M. flex, carpi radialis. 
M. flex, digitor. sublim. 
M. opponens pollicis. 
M. flex. poll. brev. 
M flex dig subl. 
(dig. ind. et min.) 
M. flex poll, 
longus. 
\ is. medi- 
' anus. 
M. abductor pollic- brer. 
Jim. lumbricalss 
1 et II. 
Mm. lumbri- 
ca esill etIV. 
M. opponens digit. lain. 
M. flexor digit, min. 
M. abductor digit min. 
M. almaris brer. 
N. ulnaris. 
M. flexor carpi ulnaris. 
Fig. 506. 
N. ulnaris. 
favorably upon the nerve. Increased excitability in electrotonus at the anode, although feebler, 
has been observed during percutaneous galvanization in man. This is especially the case by 
Motor points of the median and ulnar nerves, with the muscles supplied by them. 728 
ELECTRO-THERAPEUTICS. 
[Sec. 339. 
repeatedly reversing the current, sometimes also by opening and closing, or even with a uniform 
current. If the increase of the excitability is obtained, then the direction of the current increases 
the excitability on closing the reverse current, and on opening the one in the same direction. 
Restorative Effect of the Constant Current.—Further, in using the constant current, we 
have to consider its restorative effects, especially when it is ascending. R. Heidenhain found 
that feeble and fatigued muscles recover after the passage of a constant current through them. 
Lastly, the constant current may be useful from its catalytic or cataphoric action (g 328). 
The effect is directly upon the tissue elements. It may also act directly or reflexly upon the 
blood- and lymph-vessels. 
Faradization in Paralysis.—If the primary cause of the paralysis is in the muscles them- 
N. cruralis. 
M. tensor fasciae 
latae (Nn. glut, 
sup.) 
Nervus obturatoris. 
N. obturator. 
M. quadriceps fe- 
moris (general 
centre). 
Nervus cruralis. 
M. adductor magnus. 
M. pectineus. 
M. adduct, longus. 
M. rectus femoris. 
M. cruralis. 
M. vastus externus 
M. vastus internus 
N. peroneus. • 
M. gastrocnem. 
extern. 
M. tibial. antic. - 
M. soleus. 
Nervus peroneus. 
M. extend, dig. com. long. ' 
M. peroneus longus.' 
Nervus tibialis. 
M. extens. hallucis long. 
M. peroneus brevis. - 
M. flexor hallucis 
long. 
M. abductor digiti 
min. 
M. extens. digit, comm, 
brevis. 
Mm. interossei 
dorsales. 
F>g- 507. 
Motor points of the peroneal and tibial nerves on the front of the leg; the peroneal on the left, 
the tibial on the right (after Eichhorst). 
selves, then the induced current is generally applied directly to the muscles themselves by means 
of sponge electrodes (fig. 502); while, if the motor nerves are the primary seat, then the elec- 
trodes are applied over them. The current used must be only of very moderate strength ; strong 
tetanic contractions are injurious, and so is too prolonged application (Eulenburg). 
The constant current may also be applied to the muscles or to their motor nerves, or to the 
centres of the latter, or to both muscle and nerve simultaneously. As a rule, the cathode is 
placed nearer the centre, as it increases the excitability. When the electrode is moved along 
the course of the nerve, or when the strength of the current is varied, the action is favored. 
If the seat of the lesion is in the central nervous system, then the electrodes are applied along 
the vertebral column, or on the vertebral column, and the course of the nerves at the same time, Sec. 339.] 
ELECTRO-THERAPEUTICS. 
729 
or one on the head and the other on a point as near as possible to the supposed seat of the lesion. 
The current must not be too strong nor applied too long. 
Induced v. Constant Current: Reaction of Degeneration.—Paralyzed nerves and 
muscles behave quite differently as regards the induced (rapidly interrupted) and the constant 
current. This is called the “ reaction of degeneration.” We must remember the physio- 
logical fact that a dying nerve attached to a muscle (§ 325), and also the muscles of a curarized 
animal, react much less strongly to rapidly interrupted currents than fresh non-curarized muscles. 
Baierlacher, in 1859, found that, in a case of facial paralysis, the facial muscles contracted but 
feebly to the induced current, but very energetically on the constant current being used. The 
excitability for the constant current may be abnormally increased, but may disappear on recovery 
taking place. According to Neumann, it is the longer duration of the constant current as 
opposed to the momentary closing and opening of the induced current which makes the con- 
traction of the muscle possible. If the constant current be broken as rapidly as the Faradic 
M. gluteus maximus 
(great sciatic). 
M.biceps fem.(cap. long.) 
(grt. sciat.). 
N. ischiadicus. 
Nervus peroneus. 
M. adduct, magnus (n. 
obt.). 
M. semitendinosus (grt 
sciat.). 
M. semimembranosus 
(grt. sciat.). 
M.biceps fem.(cap. brev.) 
(grt. sciat.). 
N. tibialis. 
Nervus tibialis. 
N. peroneus. 
M. gastrocnem. (cap. 
extr.). 
M. gastrocnem. (cap. 
int). 
M. soleiis. 
M .flex. dig. comm, long 
M .flexor hallucis longus 
N. tibialis. 
Fig. 508. 
Motor points of the sciatic nerve and its branches; the peroneal and tibial nerves. 
current is broken, then the constant current does not cause contraction. Conversely, the induced 
current may be rendered effective by causing it to last longer. We may also keep the primary 
circuit of the induction machine closed, and move the secondary spiral to and fro along the slots. 
Thus we obtain slow gradations of the induced current which act energetically upon curarized 
muscles (Briicke). Hence, in stimulating a muscle or nerve, we have to consider not only the 
strength, but also the duration of the current, just as the deflection of the magnetic needle 
depends upon these two factors. 
[Galvanic excitability is the term applied to the condition of a nerve or muscle, whereby it 
responds to the opening or closing of a continuous current. The effects differ according as the 
current is opened or closed, and according to its strength. As a rule, the cathode causes a 
contraction chiefly at closure, the anode at opening the current, while the cathode is the stronger 
stimulus. With a weak current, the cathode produces a simple contraction on closing the 
current, but no contraction from the anode. With a mediutn current, we get with the cathode 730 
REACTION OF DEGENERATION. 
[Sec. 339. 
a strong closing contraction but no opening contraction, while the anode excites feeble opening 
and closing contractions. With a strong current, we get with the cathode a tetanic contraction 
at closure, and a perceptible contraction at opening, while with the anode there is contraction 
both at opening and closing.] 
[The law of contraction is usually expressed by the following formula (Erb): An — anode, 
Ca ■= cathode, C = contraction, c — feeble contraction, C/=strong contraction, S = closure of 
current, O = opening of current, Te = tetanic contraction—so that, expressing the above 
statement briefly, we have— 
Weak currents produce Ca S C; 
Medium “ “ Ca S CF, An S c, An O c; 
Strong « “ Ca STe,AnSC, AnOC.CaOc.] 
[Typical Reaction of Degeneration.—When the reaction of the nerve 
and muscle to electrical stimulation is altered both qualitatively and quan- 
titatively, we have the reaction of degeneration, which is characterized essen- 
tially by the following conditions :] The excitability of the muscles is diminished 
or abolished for the Faradic current, while it is increased for the galvanic current 
from the 3d to 58th day; it again diminishes, however, with variations, from the 
72d to 80th day ; the anode closing contraction is stronger than the cathode clos- 
ing contraction. The contractions in the affected muscles occur slowly in a peris- 
taltic manner, and are local, in contrast with the rapid contraction of normal 
muscle. The diminution of the excitability of the nerves is similar for the gal- 
vanic and Faradic currents. If the reaction of the nerves be normal while 
the muscle during direct stimulation with the constant current exhibits the 
reaction of degeneration, we speak of “ partial reaction of degeneration,” 
which is constantly present in progressive muscular atrophy (.Erb). 
[The “ reaction of degeneration ” may occur before there is actual paralysis, as in lead 
poisoning. When it occurs we have to deal with some affection of the nerve-fibres, or of the 
trophic nerve-cells. When it is established, (1) stimulation of the nerve with Faradic or galvanic 
electricity does not cause contraction of the muscle; (2) direct Faradic stimulation of the 
muscles does not cause contraction; (3) the galvanic current usually excites contraction more 
readily than in a normal muscle, so that the muscle responds to much feebler currents than act 
on healthy muscles, but the contraction is longer and more of a tonic character, and shows a 
tendency to become tetanic. The electrical excitability is generally unaffected in paralysis of 
cerebral origin, and in some forms of spinal paralysis, as primary lateral sclerosis and transverse 
myelitis, but the “ reaction of degeneration ” occurs in traumatic paralysis, due to injury of the 
nerve-trunks, neuritis, rheumatic facial paralysis, lead palsy, and in affections of the nerve cells 
in the anterior cornu of the gray matter of the spinal cord.] In rare cases the contraction of the 
muscles, caused by applying a Faradic current to the nerve, follows a slow peristaltic-like course 
—“ Faradic reaction of degeneration ” (E. Remak, Erb). 
II. In Various Forms of Spasm (spasms, contracture, muscular tremor) the constant 
current is most effective (Remak). By the action of anelectrotonus, a pathological increase of 
the excitability is subdued. Hence, the anode ought to be applied to the part with increased 
excitability, and if it be a case of reflex spasm, to the points which are the origin or seat of the 
increased excitability. Weak currents of uniform intensity are most effective. The constant 
current may also be useful from its cataphoric action, whereby it favors the removal of irritants 
from the seat of the irritation. Further, the constant current increases the voluntary control 
over the affected muscles. In spasms of central origin, the constant current may be applied to 
the central organ itself. Faradization is used in spasmodic affections to increase the vigor of 
enfeebled antagonistic muscles. Muscles in a condition of contracture are said to become more 
extensible under the influence of the Faradic current (Remak), as a normal muscle is more 
excitable during active contraction ($ 301). 
In Cutaneous Anaesthesia, the Faradic current applied to the skin by means of hair- 
brush electrodes is frequently used (fig. 504). When using the constant current, the cathode 
must be applied to the parts with diminished sensibility. The constant current alone is applied 
to the central seat of the lesion, and care must be taken to what extent the occurrence of 
cathelectrotonus in the centre affects the occurrence of sensation. 
III. In Hyperaesthesia and Neuralgias, Faradic currents are applied with the object of 
over-stimulating the hyper-sensitive parts, and thus to benumb them. Besides these powerful 
currents, weak currents act reflexly and accelerate the blood-stream, increase the heart’s action, 
and constrict the blood-vessels, while strong currents cause the opposite effects (O. Naumann). 
Both may be useful. In employing the constant current in neuralgia (Remak), one object is by Sec. 339.] 
ELECTRICAL FISHES. 
731 
exciting anelectrotonus in the hyper-sensitive nerves, to cause a diminution of the excitability. 
According to the nature of the case, the anode is placed either on the nerve-trunk, or even on 
the centre itself, and the cathode on an indifferent part of the body. The catalytic and cataphoric 
effects also are most important, for by means of them, especially in recent rheumatic neuralgias, 
the irritating inflammatory products are distributed and conducted away from the part. A 
descending current is transmitted continuously for a time through the nerve-trunk, and in recent 
cases its effects sometimes are very striking. Lastly, of course, the constant current may be 
used as a cutaneous stimulus, while the Faradic current also acts reflexly on the cardiac and 
vascular activity. 
Recently, Charcot and Ballet have used the electric spark from an electrical machine in cases 
of anaesthesia, facial paralysis, and paralysis agitans. In some cases of spinal paralysis, muscles 
can be made to contract with the electric spark which do not contract to a Faradic current. 
[Electricity is sometimes used to distinguish real from feigned disease, or to distinguish death 
from a condition of trance.] 
Galvano-cautery.—The electrical current is used for thermal purposes, as in the galvano- 
cautery. 
Galvano-puncture.—The electrolytic properties of electric currents are employed to 
cause coagulation in aneurisms or varix. [If the electrodes from a constant battery in action be 
inserted in an aneurismal sac, after a time the fibrin of the blood is deposited in the sac, whereby 
the cavity of the aneurism is gradually filled up. A galvanic current passed through defibrinated 
blood causes the formation of a coagulum of proteid matter at the positive pole and bubbles of 
gas at the negative (p. 474.)] 
340. ELECTRICAL CHARGING OF THE BODY.—Saussure investigated by 
means of the electroscope the “charge” of a person standing on an insulated stool. The phe- 
nomena observed by him, which were always inconstant, were due to the friction of the clothes 
upon the skin. Gardini, Hemmer, Ahrens (1817), and Nasse regarded the body as normally 
charged with positive electricity, while Sjosten and others regarded it as negatively charged. 
Most probably all these phenomena are due to friction, and are modified effects of the air in con- 
tact with the heterogeneous clothing (Hankel). A strong charge resulting in an actual spark 
has frequently been described. Cardanus (1553) obtained sparks from the tips of the hair of the 
head. According to Horsford (1837), long sparks were obtained from the tips of the fingers of 
a nervous woman in Oxford, when she stood upon an insulated carpet. Sparks have often been 
observed on combing the hair, or stroking the back of a cat in the dark. Freshly voided tirine 
is negatively electrical ( Vasalli-Eandi, Volta); so is the freshly formed web of a spider, while 
the Hood is positive. 
341. COMPARATIVE—HISTORICAL.—Electrical Fishes.—Some of the most in- 
teresting phenomena connected with animal electricity are obtained in electrical fishes, of which 
there are about fifty species, including the electrical eel, or Gymnotus electricus, of the lagoons 
of the region of the Orinoco in South America—it may measure over 7 feet in length—the 
Torpedo marmorata, and some allied species, 30 to 70 centimetres [1 to 2]/2 feet], in the 
Adriatic and Mediterranean, the Malapterurus electricus or thunderer fish of the Arabs, a native 
of the Nile and the Niger, and the Mormyrus, allied to the pike, also of the Nile river. 
[Rhinobatis electricus of the Brazilian seas, and Trichiurus electricus of the Indian 
Ocean, and the Raia batis, or Skate of our own shores. Fifty species of fishes are believed to 
possess electrical organs.] By means of special electrical organs (Redi, 1666), these animals 
can in part voluntarily (gymnotus and malapterurus), and in part reflexly (torpedo), give a very- 
powerful electrical shock. The electrical organ consists of “ compartments ” of various forms, 
separated from each other by connective-tissue, and filled with a jelly-like substance, which the 
nerves enter on one surface and ramify to produce a plexus. From this plexus there proceed 
branches of the axial cylinder, which end in a nucleated plate, the “electrical plate ” (Bil- 
harz, M. Schulze). When the “ electrical nerves ” proceeding to the organ are stimulated, 
an electrical discharge is the result. 
Torpedo.—The electrical organs are two in number and lie immediately under the skin later- 
ally on each side of the head, reaching as far as the pectoral fins. [Each electrical organ con- 
sists of about 800 hexagonal prisms placed vertically between the abdominal and dorsal integu- 
ment, and separated from each other by membranous septa. Each prism is composed of about 
600 plates, which are placed horizontally, and separated from each other by thin membranes. 
Thus there are about 1,000,000 electrical plates, each of which is supplied by a branch of a 
nerve-fibre.] Each nerve-fibre on reaching a prism divides, according to Wagner, into a “ tuft ” 
of fine nerve-fibrils, a fibril running to each plate in the column. The fibrils divide dichoto- 
mously in the plate, and the finer twigs anastomose with each other. The electric organs are 
developed from and replace the outer gill-muscles of the fifth gill arch. The electrical organs 
receive several nerves, which arise from the lobus electricus between the corpora quadrige- 
mina and the medulla oblongata, and also branches from the trigeminus. The plates, which do 732 
ELECTRICAL FISHES. 
[Sec. 341. 
not increase in number with the growth of the animal {Della Chiaje, Babuchin), lie horizontally, 
while the nerve-fibres enter them on their dorsal surfaces, the current in the fish being from the 
abdominal to the dorsal surface {Galvani). 
In Malapterurus, the organ surrounds the entire body, except the head and fins, like a man- 
tle, and each half of it receives only one nerve-fibre (p. 671), whose axis-cylinder arises near 
the medulla oblongata from one gigantic ganglionic cell (Bilharz), and is composed of proto- 
plasmic processes (Fritsch). The plates are also vertical, and receive their nerves from the 
posterior surface. The direction of the current is descending in the fish during the discharge 
{du Bois-Reymond). 
In Gymnotus, the electrical organ consists of several rows of columns arranged along both 
sides of the spinal column of the animal under the skin as far as the tail. [There are four 
electrical organs, two on each side, stretching from the pectoral fins to near the tail.] It receives 
on the anterior surface several branches from the intercostal nerves. Besides this large organ 
Transverse septum. 
Medullated fibres of ■) 
the plexus. 
Nervous 
lamina. 
Terminal ramif. of 
non-med. nerve. 
Nucleated lamina. 
Striated lamina. 
The disc. 
Alveolar lamina. 
Connective-tissue. 
Transverse septum. 
Vertical section of part of the electrical organ of a skate. 
Fig. 509. 
there is a smaller oner lying-cm both sides above the anal fins. Here the plates are vertical, and 
the direction of the electrical current in the fish is ascending, so that of course it is descending 
in the surrounding water {Faraday, du Bois-Reymond). [The plates arise from embryonic 
muscle. The nerve-cells from which the electrical nerves spring are arranged along the spinal 
cord, forming a special column.] 
[In Raia batis, or the Skate, a fusiform electrical organ exists under the skin on each side 
of the tail (Stark), consisting of a number of longitudinal discs ; the discs are arranged in rows, 
and have one surface (flat) looking forwards and the other backwards, showing a number of 
alveolar depressions. The anterior surface is covered with a nervous layer, into which numerous 
nerve-endings, showing dichotomous division, penetrate. It seems to correspond to the end-plate 
of muscles (fig. 509). The substance of the disc beneath the nervous or electric membrane con- 
sists of fine laminse parallel to its surface.] 
It is extremely probable that the electric organs are modified muscles, in which the nerve- 
terminations are highly developed, the electrical plates corresponding to the motorial end-plates Sec. 341.] 
ELECTRICAL FISHES. 
733 
of the muscular fibres, the contractile substance having disappeared, so that during physiological 
activity the chemical energy is changed into electricity alone, while there is no “ work” done. 
This view is supported by the observation of Babuchin, that during development the organs 
are originally formed like muscles; further, that the organs when at rest are neutral, but when 
active or dead, acid ; and lastly, they contain a substance related to myosin which coagulates 
after death (§ 295—IVeyl). The organs manifest fatigue; they have a “latent period” 
of 0.016 second, while one shock of the organ (comparable to the current in an active muscle) 
lasts 0.07 second. [Sanderson and Gotch found the latent period in curarized torpedoes — 
sec.] About twenty-five of these shocks go to make a discharge, which lasts about 0.23 
second. The discharge, like tetanus, is a discontinuous process (Marey). Mechanical, chemical, 
thermal, and electrical stimuli cause a discharge; a single induction shock is not effective (Sachs). 
During the electrical discharge the current traverses the muscles of the animal itself; the latter 
contract in the torpedo, while they do not do so in the gymnotus and malapterurus during the dis- 
charge (Steiner). A torpedo can give about fifty shocks per minute ; it then becomes fatigued, 
and requires some time to recover itself. It may only partially discharge its organ (At. v. Hum- 
boldt, Sachs). Cooling makes the organ less active, while heating it to 220 C. makes it more so. 
The organ becomes tetanic with strychnin (Becquerel), while curare paralyzes it (Sachs). Stimu- 
lation of the electrical organ of the torpedo causes a discharge (Matteucci); cold retards it, 
while section of the electrical nerves paralyzes the organ. The electrical fishes themselves are 
but slightly affected by very strong induction shocks transmitted through the water in which they 
are swimming (du Bois-Reymond). The substance of the electrical organs is singly refractive; 
excised portions give a current during rest, which has the same direction as the shock; tetanus 
of the organ weakens the current (Sachs, du Bois-Reymond). Perhaps the electrical organ 
of malapterurus is evolved from modified cutaneous glands (Fritsch). 
[In the torpedo, the organ seems to be to a certain extent under the control of the will. 
Direct stimulation of the electric lobe causes a discharge in the electric organ of its own side; 
the organ may be discharged reflexly (i. e., by stimulating any part of the animal’s skin, and 
also indirectly by stimulating the electrical nerve passing to the organ. The “ reflex discharge ” 
consists of a succession of shocks. The discharge of an organ is comparable to tetanus of a 
muscle, and the individual shocks composing it to the single contractions that, when superposed, 
constitute tetanus. Curare has no effect on the excitation of the organ through its nerve 
(Moreau). According to Pacini the nerves are always distributed to the electric plate on the 
side which becomes negative in the discharge.] 
Historical.—Richer (1672) made the first communication about the gymnotus. Walsh 
(1772) made investigations on the torpedo, on its discharge, and its power of communicating a 
shock. J. Davy magnetized particles of steel, caused a deflection of the magnetic needle, and 
obtained electrolysis with the electrical discharge. Becquerel, Brechet, and Matteucci studied 
the direction of the discharge. Al. v. Humboldt described the habits and actions of the gym- 
notus of South America. Hausen (1743) and de Sauvages (1744) supposed that electricity 
was the active force in nerves. The actual investigations into animal electricity began with G. 
Aloisio Galvani (1791), who observed that frogs’ legs connected with an electrical machine con- 
tracted, and also when they were touched with two different metals. He believed that nerves 
and muscles generated electricity. Alessandro Volta ascribed the second experiment to the 
electrical current produced by the contact of dissimilar metals, and therefore outside the tissues 
of the frog. The contraction without metals described by Galvani was confirmed by Alex. v. 
Humboldt (1798). Pfaff (1793) first observed the effect of the direction of the current upon the 
contraction of a frog’s leg obtained by stimulating its nerve. Bunzen made a galvanic pile of 
frogs’ legs. The whole subject entered on a new phase with the construction of the galvano- 
meter and since the introduction of the classical methods devised by du Bois-Reymond, i. e., 
from 1843 onwards. [The more recent investigations on electrical organs have been made by 
Ranvier, Marey, Sanderson, Gotch and Ewart.] Physiology of the Peripheral Nerves. 
342. FUNCTIONAL CLASSIFICATION OF NERVE- 
FIBRES.—As nerve-fibres, on being stimulated, are capable of conducting 
impulses in both directions (§ 338), it is obvious that the physiological position 
of a nerve-fibre must depend essentially upon its relations to the peripheral 
end-organ on the one hand, and its central connection on the other. 
Thus each nerve is distributed to a special area within which, under normal 
circumstances, in the intact body, it performs its functions. This function of 
the individual nerves, determined by their anatomical connections, is called 
their “specific energy.” Nerve-fibres are classified as follows: — 
I. Centrifugal or Efferent Nerves. 
[Efferent fibres are those fibres that carry impulses from the centre, i. e., the 
central nervous system, to the periphery.] 
(a) Motor.—Those nerve-fibres whose peripheral end-organ consists of a 
muscle, the central ends of the fibres being connected with nerve-cells :— 
1. Motor fibres of striped muscle (gg 292-320). 
2. Motor nerves of the heart (g 57). 
3. Motor nerves of smooth muscle, e.g., the intestine (g 171). The vaso-motor nerves 
are specially treated of in g 371. 
(b) Secretory.—Those nerve-fibres whose peripheral end-organ consists 
of a secretory cell, the central ends of the fibres being connected with nerve- 
cells. 
Examples of secretory nerves are the secretory nerves for saliva (g 145) and those for 
sweating (g 289, II). [It is to be remembered, however, that these fibres not unfrequently lie 
in the same sheath with other nerve-fibres, so that stimulation of a nerve may give rise to several 
results, according to the kind of nerve-fibres present in the nerve. Thus, the secretory and 
vaso-motor nerves of glands may be excited simultaneously.] 
(c) Trophic.—The end-organs of these nerve-fibres lie in the tissues 
themselves, and are as yet unknown. These nerves are called trophic, because 
they are supposed to govern or control the normal metabolism of the tissues. 
In some tissues, we know of a direct connection of their elements with nerve-fibres, which 
may influence their nutrition. Nerves are connected with the corneal corpuscles (g 201, 7), 
with the pigment-cells of the frog’s skin (Ehrmann), the connective-tissue corpuscles of the 
serous membrane of the stomach of the frog, and the cells around the stomata of lymphatic 
surfaces (g 196, 5) (E. F. Hoffmann). 
Trophic Influence of Nerves.—The trophic functions of certain nerves are referred to as 
under: On the influence of the trigeminus on the eye, the mucous membrane of the mouth 
and nose, the face (g 347); the influence of the vagus on the lungs (g 352); motor nerves 
on muscle (g 307); nerve-centres on nerve-fibres (g 325,4); certain central organs upon 
certain viscera (g 379). 
Section of certain nerves influences the growth of the bones. H. Nasse found that, after 
section of their nerves, the bones showed an absolute diminution of all their individual con- 
stituents, while there was an increase of the fat. Section of the spermatic nerve is followed by 
degeneration of the testicle (Nilaton, Obolensky). After extirpation of their secretory nerves, 
there is degeneration of the sub-maxillary glands (p. 255). Section of the nerves of the Sec. 342.] 
TROPHO-NEUROSES. 
735 
cock’s-comb interferes with the nutrition of that organ (Legros, Schiff). After section of the 
2d cervical nerve in rabbits and cats, the hair falls off the ear on that side {Joseph). Section of 
the cervical sympathetic nerve in young, growing animals is followed by a more rapid growth of 
the ear upon that side (Bidder, Stirling, Strieker), also of the hair on that side {Schiff, Stir- 
ling) ; while it is said that the corresponding half of the brain is smaller, which, perhaps, is due 
to the pressure from the dilated blood-vessels {Brown-Sequard). 
Blood-Vessels.—Lewaschew found that prolonged uninterrupted stimulation of the sciatic 
nerve of dogs, by means of chemical stimuli [threads dipped in sulphuric acid], caused hyper- 
trophy of the lower limb and foot, together with the formation of aneurismal dilatations upon 
the blood-vessels. 
Skin and Cutaneous Appendages.—In man, stimulation or paralysis of nerves, or degen- 
eration of the gray matter of the spinal cord, is not unfrequently followed by changes in the 
pigmentation of the skin, in the nails, in the hair and its mode of growth and color {Jarisch). 
[Injury to the brain, as by a fall, sometimes results in paralysis of the hair-follicles, so that, after 
such an injury, the hair is lost over nearly the whole of the body.] Sometimes there may be 
eruptions upon the skin, apparently traumatic in their origin {v. Barensprtmg). Sometimes there is 
a tendency to decubitus ($ 379), and in some rare cases of tabes there is a peculiar degeneration 
of the joints (Charcot’s disease). The changes which take place in a nerve separated from 
its centre are described in \ 325. 
[Tropho-neuroses.—Some of the chief data on which the existence of trophic nerves is 
assumed are indicated above. There are many pathological conditions referable to diseases or 
injuries of nerves.] 
[Muscles.—As is well known, paralysis of a motor nerve leads to simple atrophy of the 
corresponding muscle, provided it be not exercised; but when the motor ganglionic cells of the 
anterior horn of gray matter, or the corresponding cells in the crus, pons, and medulla, are 
destroyed, there is an active condition of atrophy with proliferation of the muscular nuclei. 
Progressive muscular atrophy, or wasting palsy, is another trophic change in muscle, whereby 
either individual muscles, or groups of muscles, are one after the other paralyzed and become 
atrophied. In pseudo-hypertrophic paralysis there is cirrhosis or increased development of 
the connective-tissue, with a diminution of the true muscular elements, so that although the 
muscles increase in bulk their power is diminished.] 
[Cutaneous Trophic Affections.—Amongst these maybe mentioned the occurrence of red 
patches or erythema, urticaria or nettle-rash, some forms of lichen, eczema, the bullae or blebs 
of pemphigus, and some forms of ichthyosis, each of which may occur in limited areas after 
injury to a nerve or its spinal or cerebral centre. The relation between the cutaneous eruption 
and the distribution of a nerve is sometimes very marked in herpes zoster, which frequently 
follows the distribution of the intercostal and supraorbital nerves. Glossy skin {Paget, Weir 
Mitchell) is a condition depending upon impaired nutrition and circulation, and due to injuries 
of nerves. The skin is smooth and glossy in the area of distribution of certain nerves, while 
the wrinkles and folds have disappeared. In myxeedema the subcutaneous tissue and other 
organs are infiltrated with, while the blood contains, mucin. The subcutaneous tissue is swollen, 
and the patient looks as if suffering from renal dropsy. There is marked alteration of the 
cerebral faculties, and a condition resembling a “ cretinoid state ” such as occurs after the ex- 
cision of the thyroid gland. Victor Horsley has shown that a similar condition occurs in 
monkeys after excision of the thyroid gland ($ 103, III). Laycock described a condition of 
nervous oedema which occurs in some cases of hemiplegia, and apparently it is independent of 
renal or cardiac disease.] 
[There are alterations in the color of the skin depending on nervous affections, including 
localized leucoderma, where circumscribed patches of the skin are devoid of pigment. The 
pigmentation of the skin in Addison’s disease or bronzed skin, which occurs in some cases of 
disease of the suprarenal capsules, may be partly nervous in its origin, more especially when we 
consider the remarkable pigmentation that occurs around the nipple and some other parts of the 
body during pregnancy, and in some uterine and ovarian affections. 
In anaesthetic leprosy, the anaesthesia is due to the disease of the nervous structure, which 
results in disturbance of motion and nutrition. Amongst other remarkable changes in the skin, 
perhaps due to trophic conditions, are those of symmetrical and local gangrene, and acute 
decubitus or bed-sores.] 
[Bed-Sores.—Besides the simple chronic form, which results from over-pressure, bad nursing, 
and inattention to cleanliness, combined with some defect of the nervous conditions, there is 
another form, acute decubitus, which is due directly to nerve influence {Charcot). The latter 
usually appears within a few hours or days of the cerebral or spinal lesion, and the whole cycle 
of changes—from the appearance of the erythematous dusky patch to inflammation, ulceration, 
and gangrene of the buttock—is completed in a few days. An acute bed-sore may form when 
every attention is paid to the avoidance of pressure and other unfavorable conditions. When it 
depends on cerebral affections, it begins and develops rapidly in the centre of the gluteal region 736 
CLASSIFICATION OF NERVE-FIBRES. 
[Sec. 342. 
on the paralyzed side, but when it is due to disease of the spinal cord it forms more in the middle 
line in the sacral region; while in unilateral spinal lesions it occurs not on the paralyzed, but on 
the anaesthetic side, a fact which seems to show that the trophic, like the sensory fibres, decussate 
in the cord (^jj).] 
[There are other forms due to nervous disease, including symmetrical gangrene and local 
asphyxia of the terminal parts of the body, such as toes, nose, and external ear, caused perhaps 
by spasm of the small arterioles (Raynaud’s disease); and the still more curious condition of 
perforating ulcer of the foot. Hemorrhage of nervous origin sometimes occurs in the skin, 
including those that occur in locomotor ataxia after severe attacks of pain, and haematoma 
aurium, or the insane ear, which is specially common in general paralytics.] 
(d) [Inhibitory nerves are those nerves which modify, inhibit, or suppress 
a motor or secretory act already in progress.] 
Take as an example the effect of the vagus upon the action of the heart. Stimulation of 
the peripheral end of the vagus causes the heart to stand still in diastole ($ 85); see also the 
effect of the splanchnic upon the intestinal movements (§ 161). The vaso-dilator nerves, 
or those whose stimulation is followed by dilatation of the blood-vessels of the area which 
they supply, are referred to especially in \ 237. 
[There is the greatest uncertainty as to the nature and mode of action of inhibitory 
nerves, but take as a type the vagus which depresses the function of the heart, as shown by 
the slower rhythm, diminution of the contractions, relaxation of the muscular tissue, lowering of 
the excitability and conduction. These phenomena are not due to exhaustion. Gaskell points 
out that the action is beneficial in its after-effects, so that this nerve, although it causes diminished 
activity, is followed by repair of function; hence, he groups it as an anabolic nerve, the out- 
ward symptoms of cessation of function indicating that constructive chemical changes are going 
on in the tissue.] 
(e) Thermic and electrical nerves have also been surmised to exist. 
[Gaskell classifies the efferent nerves differently. Besides motor nerves 
to striped muscle, he groups them as follows:— 
1. Nerves to vascular muscles. 
(a) Vaso-?notor, i. e., vaso-constrictors; accelerators and augmentors of the heart. 
(b) Vaso-inhibitory, i. <?., vaso-dilators; and inhibitors of the heart. 
2. Nerves of the visceral muscles. 
(a) Viscero-motor. 
(b) Viscero-inhibitory. 
3. Glandular nerves.] 
[Other terms are applied to nerves with reference to the chemical changes 
they excite in a tissue in which they terminate. The ordinary metabolism is 
the resultant of two processes—one constructive, the other destructive, or of 
assimilation and dissimilation respectively. The former process is anabolism, 
the latter katabolism. A motor nerve excites chemical destructive changes in 
a muscle, and is so far the katobolic nerve of that tissue ; secretory nerves 
are also katabolic in this sense; in the same way the sympathetic to the heart, 
by causing more rapid contraction, is also a katabolic nerve, while the vagus, as 
it arrests the heart’s action, and brings about a constructive metabolism of the 
cardiac tissue, is an anabolic nerve, and so are the inhibitory nerves of the 
blood-vessels and the viscera (Gaskell).] 
II. Centripetal or Afferent Nerves. 
[Afferent nerve-fibres are those fibres that carry impulses from the periphery 
to the centre, usually the central nervous system.] 
(a) Sensory nerves (sensory in the narrower sense), which by means of 
special end-organs conduct sensory impulses to the central nervous system. 
(b) Nerves of Special Sense. 
(c) Reflex or Excito-motor Nerves.—When the periphery of one of 
these nerves is stimulated, an impulse is set up which is conducted by them to a 
nerve-centre, from whence it is transferred to a centrifugal or efferent fibre, and Sec. 342.] 
OLFACTORY NERVE. 
737 
the mechanism (I, a, b, c, d) in connection with the peripheral end of this 
efferent fibre is set in action; thus there are— 
Reflex motor, Reflex secretory, and Reflex 
inhibitory fibres. [Fig. 510 shows the simplest 
mechanism necessary for a reflex motor act. The 
impulse starts from the skin, S, travels up the 
nerve, af, to the nerve-centre or nerve-cell, N, 
situate it may be in the spinal cord, where it is 
modified and transferred to the outgoing fibre, ef, 
and conveyed by it to the muscle, M.] 
[In all probability the mechanism is not so 
simple as is shown in fig. 510. In some cases 
both the ingoing and the outgoing fibres are con- 
nected with separate nerve-cells, so that the fig. 
511 would represent what occurs in this case. Fig. 
51X represents, on the same hypothesis, schemata of a reflex secretory act, and 
also of a reflex inhibitory act. In the last case, the impulses carried along the 
fibre, inh, prevent the reflex motor effect from taking place.] 
Fig. 510. 
Scheme of a reflex motor act. S, 
skin; af, afferent nerve; N, 
nerve-cell; ef, efferent fibre. 
Reflex motor. 
Reflex sensory. 
Reflex inhibitory 
Schemata of various reflex acts (Stirling) 
Fig. 511 - 
III. Intercentral Nerves. 
These fibres serve to connect ganglionic centres with each other, as, for 
example, in co-ordinated movements and in extensive reflex acts. 
THE CRANIAL NERVES. 
343- !• NERVUS OLFACTORIUS.—Anatomical.—The three-sided prismatic tractus 
olfactorius, lying in a groove on the under surface of the frontal lobe, arises by means of an 
inner, outer, and middle root, from the tuber olfactorium (fig. 428, I). The tractus swells out 
upon the cribriform plate of the ethmoid bone, and becomes the bulbus olfactorius, which is 
the analogue of the special portion of the brain, existing in different mammals with a well-devel- 
oped sense of smell (Gratiolet'). From twelve to fifteen olfactory filaments pass through the 
foramina in the cribriform plate of the ethmoid bone. At first they lie between the periosteum 
and the mucous membrane, but in the lower third of their course they enter the mucous mem- 
brane of the regio olfactoria. The bulb consists of white matter below, and above of gray mat- 
ter mixed with small spindle-shaped ganglionic cells (§ 420). Henle describes six, and Mey- 
nert eight layers, of nervous matter seen on transverse section. [The centre for smell lies in 
the tip of the uncinate gyrus on the inner surface of the cerebral hemisphere (Ferrier).'] According 
to Gudden, removal of the olfactory bulb is followed by atrophy of the gyrus uncinatus on the same 
side. According to Hill, the three roots of the olfactory bulb stream backwards, the inner one is 
small, the middle one is a thick bundle, which grooves the head of the caudate nucleus, curves in- 
wards to the anterior commissure, and crosses via this commissure where it decussates, and passes 
to the extremity of the tempero-sphenoidal lobe. The outer roots pass transversely into the pyriform 
lobe, thence vid the fornix, corpora albicantia, the bundle of Vicq d’Azyr into the anterior end 
of the optic thalamus. Hill also points out that the elements contained in the olfactory bulb are 
identical with those contained in the four outer layers of the retina. Flechsig traces its origin 738 
OPTIC NERVE. 
[Sec. 343. 
(i) to the gyrus fornicatus, (2) through the lamina perforata anterior to the interior capsule 
(sensory part), and to the gyrus uncinatus (sensory area of the cerebrum) (§ 378, IV). Probably 
the fibres at their origin cross to the cerebrum. There is a connection between the olfactory 
bulbs in the anterior commissure. [Each nerve is related to both hemispheres.] 
Function.—It is the only nerve of smell. Physiologically, it is excited 
only by gaseous odorous bodies—(Sense of Smell, § 420). Stimulation of the 
nerve, by any other form of stimulus, in any part of its course, causes a sensa- 
tion of smell. [It also conveys those impressions which we call flavors, but in 
this case the sensation is combined with impressions from the organs of taste. 
In this case also the stimulus reaches the nerve by the posterior nares.] Con- 
genital absence or section of both olfactory nerves abolishes the sense of smell 
(easily performed on young animals—Biff). 
Pathological.—The term hyperosmia is applied to cases where the sense of smell is exces- 
sively and abnormally acute, as in some hysterical persons, and in cases where there is a purely 
subjective sense of smell, as in some insane persons. The latter is perhaps due to an abnormal 
stimulation of the cortical centre (§ 378, IV). Hyposmia and anosmia [i. e., diminution and 
abolition of the sense of smell) may be due to mechanical causes, or to over-stimulation. Strych- 
nin sometimes increases, while morphia diminishes, the sense of smell. [Method of Testing, 
$ 421.] 
344. II. NERVUS OPTICUS.—Anatomical.—The tractus opticus (fig. 517, II) 
arises from the anterior corpora quadrigemina, the corpus geniculatum externum, and the thala- 
mus opticus (fig. 528), as well as from the gray matter which lines the third ventricle (Tartuferi). 
A broad bundle of fibres passes from the origin of the optic tract to the cortical visual centre, 
in the occipital lobe on the same side ( Wernicke—g 379, IV). Fibres pass from the cerebellum 
through the crura. 
The optic tract bends round the pedunculus cerebri, where it unites with its fellow of the 
opposite side to form the chiasma, and from the opposite side of this the two optic nerves 
spring. 
[Connections of Optic Tract.—There is very considerable difficulty in ascertaining the 
exact origin of all the fibres of the optic tract. Although as yet the statement of Gratiolet is not 
proved, that the optic tract is directly connected with every part of the cerebral hemisphere in 
man, from the frontal to the occipital lobe, still the researches of D. J. Hamilton have shown 
that its connections are very extensive. It is certain that some of them are ganglionic, i. e., 
connected with the ganglia at the base of the brain, while others are cortical, and form connec- 
tions with the cortex cerebri. The ganglionic fibres arise from the lateral corpora geniculata, 
pulvinar, and anterior corpora quadrigemina, and probably also from the substance of the thala- 
mus. The cortical fibres join the ganglionic to form the optic tract. According to D. J. Ham- 
ilton, the connection with the cortex in the frontal region is brought about by “ Meynert’s com- 
missure.” The latter arises directly from the lenticular-nucleus-loop, decussates in the lamina 
cinerea, and passes into the optic nerve of the opposite side. The lenticular-nucleus-loop is 
formed below the lenticular nucleus by the junction of the striae medullares; the striae medullares 
form part of the fibres of the internal capsule, and the inner capsule is largely composed of fibres 
descending from the cortex. Hamilton also asserts that other cortical connections join the tract 
as it winds round the pedunculus cerebri, and they include (a) a large mass of fibres coming from 
the motor areas of the opposite cerebral hemisphere, crossing in the corpus callosum, entering 
the outer capsule, and joining the tract directly: {/>) fibres uniting it to the temporo-sphenoidal 
lobe of the same side, especially the first and second temporo-sphenoidal convolutions ; (<r) fibres 
to the gyrus hippocampi of the same side; (d) a large leash of fibres forming the “ optic radi- 
ation ” of Gratiolet, which connect it directly with the tip of the occipital lobe. There are 
probably also indirect connections with the occipital region through some of the basal ganglia. 
Although some observers do not admit the connections with the frontal and sphenoidal lobes, all 
are agreed as to its connection with the occipital by means of the “ optic radiation.”] 
[The optic radiation of Gratiolet is a wide strand of fibres expanding and terminating in 
the occipital lobes. It is composed of, or, stated otherwise, gives branches to (a) the optic tract 
directly, (3) the corpus geniculatum internum and externum, (r) to the pulvinar and substance of 
the thalamus, (d) a direct sensitive band (Meynert’s “ Sensitive band ”), to the posterior third of 
the posterior limb of the inner capsule, (e) fibres which run between the island of Reil and the 
tip of the occipital lobe (D. f. Hamilton). 
Chiasma.—The extent of the decussation of the optic fibres in the chiasma 
is subject to variations. As a rule, rather more than half of the fibres of one 
tract cross to the optic nerve of the opposite side (fig. 572), so that the left Sec. 344.] 
739 
OPTIC NERVE. 
optic tract sends fibres to the left half of both eyes, while the right tract sup- 
plies the right half of both eyes (§ 378, IV). [Thus, the corresponding 
regions of each retina are brought into relation with one hemisphere. The fibres 
which cross are from the nasal half of each retina (fig. 513).] 
Hence, in man, destruction of one optic tract (and its central continuation in the occipital 
lobe of the cerebrum) produces “ equilateral or homonymous hemianopia.” In the cat there 
is a semi-decussation; hence, in this animal extirpation of one eyeball causes atrophy and 
degeneration of half of the nerve-fibres in both optic tracts {Gudden). Baumgarten and Mohr 
have observed a similar result in man. A sagittal section of the chiasma in the cat produces 
partial blindness of both eyes {Nicati). According to Gudden, the fibres which decussate are 
more numerous than those which do not, although J. Stilling maintains that they are only 
slightly more numerous. According to J. Stilling, the decussating fibres lie in the central axis 
of the nerve, while those which do not decussate form a layer around the former. 
In very rare cases the decussation is absent in man, so that the right tract passes directly into 
the right eyeball, and the left into the left eyeball (Vesalius, Caldani), the sight not being inter- 
fered with. 
Tig. 512.—Scheme of the semi-decussation of the optic nerves. L. A., left eye; R. A., right 
eye. Fig. 513.—Diagram of the relation of the field of vision, retina, and optic tracts. 
RF, LF, right and left fields of vision—the asterisk is at the fixing point; RR, LR, right 
and left retina—the asterisk is at the macula lutea ; l. h., r. h., left half and right half of 
each retina, receiving rays from the opposite half of the field; RN, LN, right and left 
optic nerves; Ch, chiasma; RT, LT, right and left optic tracts; below, the halves of the 
fields from which impressions pass by each optic tract are superimposed {Gowers). 
Fig- 512 
Fig- 513- 
Other observers maintain that there is complete decussation of all the fibres in the chiasma. 
Hence, section of one optic nerve causes dilatation of the pupil and blindness on the same side, 
while section of one optic tract causes dilatation of the pupil and blindness of the opposite eye 
{Knoll). 
Amongst animals, there is partial decussation in the rabbit, cat, and dog; total decussation 
in the mouse, guinea-pig, pigeon, and owl. In osseous fishes, both optic nerves are isolated and 
merely cross over each other, while in the cyclostomata they do not cross at all. [Total 
decussation occurs in those animals where the eyes do not act together.] 
Injury of the external geniculate body and section of the anterior brachium have the same 
effect as section of the optic tract of the same side (§ 359—Bechterew). 
It is quite certain that the individual fibres do not divide in the chiasma. Two commissures, 
the inferior commissure (Gudden) and Meynert’s commissure, unite both optic tracts further 
back. 
A special commissure (C. inferior) extends in a curved form across the posterior angle of the 
chiasma {Gudden). It does not degenerate after enucleation of the eyeballs, so that it is 
regarded as an intercentral connection. After excision of an eye, there is central degenera- 
tion of the fibres of the optic nerve entering the eyeball {Gudden), and in man about the half 
of the fibres in the corresponding optic tract {Baumgarten, Mohr). After section of both [Sec. 344. 
740 
OPTIC NERVE. 
optic nerves, or enucleation of both eyeballs, there is a degeneration, proceeding centrally, 
of the whole optic tract. The degeneration extends to the origins in the corpora quadrigemina, 
external corpora geniculata, and pulvinar, but not into the conducting paths leading to the cor- 
tical visual centre (v. Monakow) (§ 378, IV, I). [This shows that perhaps the nerve-cells of 
the retina are the trophic centres for the fibres of the optic nerve.] 
[Hemianopia and Hemianopsia.—When one optic tract is interfered with or divided, 
there is interference with or loss of sight in the lateral halves of both retinae, the blind part 
being separated from the other half of the field of vision by a vertical line. When it is spoken 
of as paralysis of one-half of the retina, the term hemiopia, or preferably hemianopia, is 
applied to it; when with reference to the field of vision, the term hemianopsia is used (see 
Eye). Suppose the left optic tract to be divided or pressed upon by a tumor at K (fig. 514), 
then the outer half of the left and the inner half of the right eye are blind, causing right lateral 
hemianopsia, i.e., the two halves are affected which correspond in ordinary vision, so that the 
condition is spoken of as homonymous hemianopsia. Suppose the lesion to be at T (fig. 
514), then there is paralysis of the inner halves of both eyes, causing double temporal hemian- 
opsia. When there are two lesions at NN, which is very rare, the outer halves of both retinae 
are paralyzed, so that there is double nasal hemianopsia. In order to explain some of the eye 
symptoms that occasionally occur in cerebral disease, Charcot has supposed that some of the 
fibres which pass from the external geniculate 
body to the visual centres in the occipital lobe 
cross behind the corpora quadrigemina, and this 
is represented in the diagram as occurring at 
TQ, in the corpora quadrigemina. On this view, 
all the occipital cortical fibres from one eye 
would ultimately pass to the cortex of the occip- 
ital lobe of the opposite hemisphere. This view, 
however, by no means explains all the facts, for 
in cases of homonymous hemianopsia the points 
of central vision on both sides, i.e., both mac- 
ulae luteae, are always unaffected, so that it is 
assumed that each macula lutea is connected 
with both hemispheres. The second crossing 
suggested by Charcot probably does not occur. 
Affections of the optic nerve, e.g., between the 
eyeball and the chiasma, i.e., in the orbit, optic 
foramen, or within the skull, affect one eye only; 
of the middle of the chiasma, cause temporal 
hemiopia; of the optic tract, between the chi- 
asma and occipital cortex, hemiopia, which is 
always symmetrical (Gowers).) 
Fig. 513, reduced from that of Gowers, shows 
the relation of the fields of vision of the retina, 
tracts, and the cerebral optic centre. 
Function.—The optic nerve is the 
nerve of sight; physiologically, it is 
excited only by the transference of the 
vibrations of the ether to the rods and 
cones of the retina (§ 383). Every 
other form of stimulus, when applied 
to the nerve in its course or at its centre, 
causes the sensation of light. Section 
or degeneration of the nerve is followed 
by blindness. Stimulation of the optic 
nerve causes a reflex contraction of the 
pupils, the efferent nerve being the oculomotorius or third cranial nerve. If 
the stimulus be very strong, the eyelids are closed and there is a secretion of 
tears. The influence of light upon the general metabolism is stated at § 126, 9. 
As the optic nerve has special and independent connections with the (1) 
so-called visual centre (§ 378, IV), as well as with (2) the centre for narrowing 
the pupil (§ 345), it is evident that, under pathological circumstances, there 
may be, on the one hand, blindness with retention of the action of the iris, 
Fig- 514- 
Diagram of the decussation of the optic tracts. 
T, semi-decussation in the chiasma; TQ, 
decussation of fibres behind the ext. geni- 
culate bodies (CG); a'b, fibres which do not 
decussate in the chiasma; b' a', fibres pro- 
ceeding from the right eye, and coming 
together in the left hemisphere (LOG); 
LOG, K, lesion of the left optic tract pro- 
ducing right lateral hemianopsia ; A, lesion 
in the left hemisphere producing crossed 
amblyopia (right eye); T, lesion producing 
temporal hemianopsia; NN, lesion pro- 
ducing nasal hemianopsia. Sec. 344.] 
NERVUS OCULOMOTORIUS. 
741 
and on the other loss of the movements of the iris, the sense of vision being 
retained ( Wernicke). 
Gudden found two different kinds of nerve-fibres in the optic nerve ; fine 
or visual fibres, with their centre in the opposite corpora quadrigemina, and 
larger ones—pupil-contracting fibres—arising in the external geniculate body. 
Destruction of the visual fibres causes blindness, of the others dilatation of 
the pupil. 
Pathological.—Stimulation of almost the whole of the nervous apparatus may cause excessive 
sensibility of the visual apparatus (hyperaesthesia optica), or even visual impressions of the 
most varied kinds (photopsia, chromatopsia), which in cases of stimulation of the visual 
centre may become actual visual hallucinations ($ 378, IV). Material change in, and 
inflammation of, the nervous apparatus are often followed by a nervous weakness of vision 
(amblyopia), or even by blindness (amaurosis). Both conditions, however, may be the signs 
of disturbances of other organs, i. <?., they are “ sympathetic” signs, due it may be to changes 
in the movement of the blood stream, depending upon stimulation of the vaso-motor nerves. 
The discovery of the partial origin of the optic nerve from the spinal cord explains the 
occurrence of ambylopia with partial atrophy of the optic nerve, in disease of the spinal cord, 
especially in tabes. Many poisons, such as lead and alcohol, disturb vision. There are 
remarkable intermittent forms of amaurosis known as day-blindness or hemeralopia, which 
occurs in some diseases of the liver, and is sometimes associated with incipient cataract. [The 
person can see better in a dim light than during the day or in a bright light. In night- 
blindness or nyctalopia, the person cannot see at night or in a dim light, while vision is good 
during the day or in a bright light. It depends upon disorder of the eye itself, and is usually 
associated with imperfect conditions of nutrition.-] 
345. III. NERVUS OCULOMOTORIUS.—Anatomical.—It springs from the oculo- 
motorius nucleus (united with that of the trochlearis), which is a direct continuation of the 
anterior horn of the spinal cord, and lies under the aqueduct of Sylvius (figs. 517, 520). [The 
motor nucleus (fig. 516) gives origin to three sets of fibres, for (1) the most of the muscles of the 
eye-balis, (2) the sphincter pupillae, (3) ciliary muscle. The nucleus of the 3d andqth nerves is 
also connected with that of the 6th under the iter, so that all the nerves to the ocular muscles 
are thus co-related at their centres.] 
The origin is connected with the corpora quadrigemina, to which the intraocular fibres may 
be traced, and also with the opposite half of the brain to the angular gyrus (§ 378, I) through 
the pedunculus cerebri. Beyond the pons, it appears on the inner side of the cerebral peduncle, 
between the superior cerebellar and posterior cerebral arteries (fig. 517, III). 
Functions.—It contains—(1) the voluntary motor fibres for all the external 
muscles of the eyeballs—except the external rectus and superior oblique—and 
for the levator palpebrse superioris. The co-ordination of the movements of 
both eye-balls, however, is independent of the will. (2) The fibres for the 
sphincter pupillae, which are excited reflexly from the retina. (3) The 
voluntary fibres for the muscle of accommodation, the tensor choroideae or 
ciliary muscle. The intra-bulbar fibres of 2 and 3 proceed from the branch for 
the inferior oblique muscle, as the short root of the ciliary ganglion (fig. 518). 
They reach the eyeball through the short ciliary nerves of the ganglion. V. 
Trautvetter and others observed that stimulation of the nerve caused changes 
in the eye similar to those which accompany near vision. The three centres 
for the muscle of accommodation, the sphincter pupillae, and the internal rectus 
muscle, lie directly in relation with each other, in the most posterior part of 
the floor of the third ventricle (.Hensen and Volckers). 
The centre for the reflex stimulation of the sphincter fibres by light was 
said to be in the corpora quadrigemina, but newer researches locate it in the 
medulla oblongata (§§ 379, 392). The narrowing of the pupil, which accom- 
panies the act of accommodation for a near object, is to be regarded as an asso- 
ciated movement (§ 392, 5). 
Anastomoses.—In man, the nerve anastomoses on the sinus cavernosus with the ophthalmic 
branch of the trigeminus, whereby it receives sensory fibres for the muscles to which it is distri- 
buted ( Valentin, Adamilk), with the sympathetic through the carotid plexus, and (?) indirectly 
through the abducens, whereby it receives vaso-motor fibres (?). 742 
SQUINTING—CONJUGATE DEVIATION. 
[Sec. 345. 
Varieties.—In some rare cases, the pupillary fibres for the sphincter run in the abducens 
(.Adamiik), or even in the trigeminus (Schiff, v. Grafe). 
Atropin paralyzes the intrabulbar fibres of the oculomotorius, while Calabar 
bean stimulates them (or paralyzes the sympathetic, or both—compare § 392). 
Stimulation of the nerve, which causes contraction of the pupil, is best demonstrated on the 
decapitated and opened head of a bird. The pupil is dilated in paralysis of the oculomotorius, 
in asphyxia, sudden cerebral anaemia (<?. g., by ligature of the carotids, or beheading), sudden 
venous congestion, and at death. 
Pathological.— Complete paralysis of the oculomotorius is followed by—(1) drooping of 
the upper eyelid (ptosis paralytica); (2) immobility of the eyeball; (3) squinting (strabismus) 
outwards and downwards, and consequently there is double vision (diplopia); (4) slight protru- 
sion of the eyeball, because the action of the superior oblique muscle in pulling the eyeball for- 
ward is no longer compensated by the action of three paralyzed recti muscles. In animals 
provided with a retractorbulbi muscle, the protrusion of the eyeball is more pronounced; (5) 
moderate dilatation of the pupil (mydriasis paralytica) ; (6) the pupil does not contract to 
light; (7) inability to accommodate for a near object. It is to be noted, however, that the 
paralysis may be confined to individual branches of the nerve, i. e., there may be incomplete 
paralysis. 
[Squinting.—In paralysis of the superior rectus, the eye cannot be moved upwards, and 
especially upwards and outwards. There is diplopia on looking upwards, the false image being 
above the true, and turned to the right when the left eye is affected (fig. 515,3). Inferior 
Rectus.—Defect of downward, and especially downward and outward movement, the eye being 
directed upwards and outwards. Diplopia with crossed images, the false one is below the true 
image and placed obliquely, being turned to the left when the left eye is affected. Diplopia is 
Internal 
rectus. 
External 
rectus. 
Superior 
rectus. 
Inferior 
oblique. 
Inferior 
rectus. 
Superior 
oblique. 
The black cross represents the true image, the thin cross the false image. The left eye is 
represented as affected in all cases [Bristow). 
F'g- 515- 
most troublesome when the object is below the line of vision (fig. 515, 5). Internal Rectus. 
Defective inward movement, divergent squint, and diplopia, the images being on the same plane, 
the false one to the patient’s right when the left eye is affected. The head is turned to the 
healthy side, when looking at an object, while there is secondary deviation of the healthy eye 
outwards (fig. 5!5> 0- Inferior oblique—is rare, the eye is turned slightly downwards and in- 
wards, and defective movement upwards. Diplopia with the false image above the true one, 
especially on looking upwards; the false image is oblique, and directed to the patient’s left 
when the left eye is affected (fig. 515, 4).] 
Stimulation of the branch supplying the levator palpebrse in man causes lagophthalmus 
spasticus, while stimulation of the other motor fibres causes a corresponding strabismus spas- 
ticus. The latter form of squinting may be caused also reflexly—e. g., in teething, or in cases 
of diarrhoea in children; [the presence of worms or other source of irritation in the intestines of 
children is a frequent cause of squinting]. Clonic spasms occur in both eyes, and also as in- 
voluntary movements of the eyeballs constituting nystagmus, which may be produced by 
stimulation of the corpora quadrigemina, as well as by other means. Tonic contraction of the 
sphincter pupillce is called myosis spastica, and clonic contraction, hippus. Spasm of the 
muscle of accommodation (ciliary muscle) is sometimes observed ; owing to the imperfect judg- 
ment of distance, this condition is not unfrequently associated with macropia. 
[Conjugate Deviation.—Some movements are produced by non-corresponding muscles; thus, 
on looking to the right, we use the right external rectus and left internal rectus, and the same 
is the case in turning the head to the right, e. g., the inferior oblique, some muscles of the right 
side act along with the left sterno-mastoid. In hemiplegia, the muscles on one side are paralyzed, 
so that the head and often the eyes are turned away from the paralyzed side, i. <?., to the side of 
the brain on which the lesion occurs. This is called “ conjugate deviation ” of the eyes, with 
rotation of the head and neck. If the right external rectus be paralyzed from an affection of 
the sixth nerve, on telling the patient to look to the right it will be found that the left eye will 
squint more inwards even than the right eye, i. e., owing to the strong voluntary effort, the Sec. 345.] 
FOURTH CRANIAL NERVE. 
743 
muscle, the left internal rectus, which usually acts along with the right external rectus, contracts 
vigorously, and so we get secondary deviation of the sound eye. Similar results occur in 
connection with paralysis of other ocular muscles.] 
346. IV. NERVUS TROCHLEARIS.—Anatomical.—It arises from the valve of 
Vieussens, i. e., behind the fourth ventricle, but its fibres pass to the oculomotorius from the 
trochlearis nucleus, which is to a certain extent a continuation of the anterior horn of the spinal 
cord (figs. 516, 520). It passes to the lower margin of the corpora quadrigemina, pierces the roof 
of the aqueduct of Sylvius, then into the velum medullare superius, and after decussating with 
Conarium or pineal gland. 
Pulvinar •* 
Brachium conjunctivum anticum. 
Brachium conjunctivum 
posticum. 
Corpus I 
quadti- < 
getuiiruin j 
anticum 
Corpus geniculatum 
medial© 
posticum 
Pedun cuius cerebri. 
Locus coeruleus 
ad corpora 
gremina, or 
-superior cerebellar 
peduncle. 
ad medullam oblon- 
ffatam, or inferior 
cerebellar i 
peduncle. J 
Euuinentia terc: 
Crus 
cerebellL 
Crus cerebelli 
ad ponteirt 
Middle cerebellar 
peduncle. 
Ala cinerea m 
Accessorius nucleus 
Obex 
Funiculus cuneatus 
(Part of restiform body). 
Clava 
Funiculus gracPI* 
(Posterior pyramid). 
Medulla oblongata, with the corpora quadrigemina. The numbers 1V-XII indicate the 
superficial origins of the cranial nerves, while those (3-12) indicate their deep origin, i. <?., 
the position of their central nuclei; t, funiculus teres. 
Fig. 516. 
the root of the opposite side behind the iter, it pierces the crus at the superior and external border 
(fig. 517). Its fibres cross between its nucleus and its distribution. It has also an origin from 
the locus coeruleus. The root of the nerve receives some fibres from the nucleus of the 
abducens of the opposite side. Physiologically, there is a necessity for a connection between 
the centre and the cortica motor centre for the eye muscles. 
Function.—It is the voluntary motor nerve of the superior oblique muscle. 
(In co-ordinated movements, however, it is involuntary.) 744 
FIFTH CRANIAL NERVE, 
[Sec. 346. 
Anastomoses.—Its connections with the plexus carotidus sympathici, and with the first 
branch of the trigeminus, have the 
same significance as similar branches 
of the oculomotorius. 
Pathological. — Paralysis of 
the trochlearis nerve causes a very 
slight loss of the mobility of the 
eyeball outwards and downwards. 
There is slight squinting inwards 
and upwards, with diplopia or 
double vision. The images are 
placed obliquely over each other 
[the false image being the lower, 
and directed to the patient’s right 
when the left eye is affected (fig. 
515, 6)] ; they approach each other 
when the head is turned towards 
the sound side, and are separated 
when the head is turned towards 
the other side. The patient at first 
directs his head forwards, later he 
rotates it round a vertical axis to- 
wards the sound side. In rotating 
his head (whereby the sound eye 
may retain the primary position), 
the eye rotates with it. Spasm of 
the trochlearis causes squinting out- 
wards and downwards. 
347. V. NERVUS TRIGE- 
MINUS.— Anatomical.— T h e 
trigeminus (fig. 518, 5) arises like a 
spinal nerve by two roots (fig. 
517, V). The smaller, anterior, 
motor root proceeds from the 
“ motor trigeminal nucleus ” 
(5), which is provided with many 
multipolar nerve cells, and lies in 
the floor of the medulla oblongata, 
not far from the middle line (fig. 
520). Fibres connect this nucleus 
with the cortical motor centres on 
the opposite side of the cerebrum. 
Besides this the “ descending 
root ” also supplies motor fibres. 
It extends laterally from the cor- 
pora quadrigemina along the aque- 
duct of Sylvius downwards to the 
exit of the nerve (Henle, Foret). 
The large posterior sensory root 
receives fibres: (1) From the small 
cells of the “ sensory trigeminal 
nucleus ” which lies at the level of 
the pons, and is the analogue of the 
posterior horn of the gray matter of 
the spinal cord. (2) From the gray 
matter of the posterior horn of the 
spinal cord, downwards as far as 
the second cervical vertebra. These 
fibres run into the posterior column 
of the cord and then appear as the 
“ ascending root ” in the trige- 
minus. (3) Some fibres come from 
the cerebellum, through the crura 
cerebelli. The origins of the sen- 
sory root anastomose with the motor 
nuclei of all the nerves arising from 
Fig. S1/- 
Part of the base of the brain, with the origins of the cra- 
nial nerves; the convolutions of the island of Reil on 
the right side, but removed on the left. V, olfactory 
tract cut short; II, left optic nerve; IV, right optic 
tract; Th, cut surface of the optic left thalamus; C, 
central lobe, or island of Reil; Sy, fissure of Sylvius; 
XX, the locus perforatus anticus; e, the external, and 
i, the internal corpus geniculatum; h, hypophysis cere- 
bri ; tc, tuber cinereuin, with the infundibulum ; a, points 
to one of the corpora albicantia; P, the cerebral ped- 
uncle ; f the fillet; III, left oculomotor nerve; X, the 
locus perforatus posticus; PV, pons Varolii; V, the 
greater part of the fifth nerve; -j-, the lesser root (on 
the right side this mark is placed on the Gasserian gang- 
lion and points to the lesser root); r, ophthalmic divi- 
sion of the fifth; VII a, facial, VII b, auditory; VIII, 
vagus; VIII a, glosso-pharyngeal; VIII b, spinal ac- 
cessory ; IX, hypo-glossal; Jl, flocculus ; fh, horizontal 
fissure of the cerebellum (C<?); am, amygdala; pa, an- 
terior pyramid; o, olivary body; e, restiform body; d, 
* anterior median fissure; cl, the lateral column of the 
spinal cord; Cl, the sub-occipital or first cervical nerve. Sec. 347.] 
FIFTH CRANIAL NERVE. 
745 
the medulla oblongata, with the exception of the abducens. This explains the vast number of 
reflex relations of the fifth nerve. The thick trunk appears on each side of the pons (fig. 517), 
when its posterior root (perhaps in connection with some fibres from the anterior) forms the Gas- 
serian ganglion, upon the tip of the petrous part of the temporal bone (fig. 518). Fibres from 
the sympathetic proceed from the plexus cavernosus to the ganglion. The nerve divides into 
three large branches. 
I. The ophthalmic division (fig. 518, d) receives sympathetic fibres {vaso- 
motor nerves) from the plexus cavernosus; it passes through the superior orbital 
fissure [sphenoidal] into the orbit. Its branches are : — 
1. The small recurrent nerve which gives sensory branches to the ten- 
torium cerebelli. Fibres—the vaso-motor nerves for the dura mater—pro- 
ceed along with it from the carotid plexus of the sympathetic. 
2. The lachrymal nerve gives off—(a) Sensory branches to the con- 
junctiva, the upper eyelid, and the neighboring part of the skin over the temple 
(fig. 5x8, a) ; (b) true sensory fibres to the lachrymal gland (?). Stimulation 
of this nerve is said to cause a secretion of tears, while its section prevents the 
reflex secretion excited through the sensory nerves of the eye. After a time, 
section of the nerve is followed by a paralytic secretion of tears (.Herzenstein 
and Wol/erz), although the statement is contested by Reich. The secretion of 
tears may be excited reflexly, by strong stimulation of the retina by light, by 
stimulation of the first and second branches of the trigeminus, and through all 
the sensory cranial nerves (Demtschenko) (§ 356, A, 6). 
3. The frontal (/) gives off the supratrochlear, which supplies sensory 
fibres to the upper eyelids, brow, glabella, and those which excite the secre- 
tion of tears reflexly; and by its supraorbital branch (b), analogous 
branches to the upper eyelid, skin of the forehead, and the adjoining skin over 
the temple as far as the vertex. 
4. The naso-ciliary nerve (nc), by its infratrochlear branch supplies 
fibres, similar to those of 3, to the conjunctiva, caruncula, and saccus lacrimalis, 
the upper eyelid, brow, and root of the nose. Its ethmoidal branch supplies 
the tip and alse of the nose, outside and inside, with sensory branches, as well 
as the upper part of the septum and the turbinated bones with sensory fibres, 
which can act as afferent nerves in the reflex secretion of tears; while it is 
probable that vaso-motor fibres are supplied to these parts through the same 
channel. (These fibres may be derived from the anastomosis with the sympa- 
thetic (?).) The naso-ciliary nerve gives off the long root (/) of the ciliary 
ganglion (c), and 1 to 3 long ciliary nerves. 
The ciliary ganglion (fig. 518, c), which, according to Schwalbe, perhaps 
belongs rather to the third than the fifth nerve, has three roots —(a) the 
short or oculomotorius (3—see § 345) ; (b) the long (/), from the naso-ciliary; 
and (c) the sympathetic (j) sometimes united with b, from the carotid plexus. 
The short ciliary nerves (/), six to ten in number, proceed from the gan- 
glion, along with the long ciliary nerves, to near the entrance of the optic 
nerve, where they perforate the sclerotic coat and run forwards between it and 
the choroid. 
Ciliary Nerves.—Physiologically, these nerves contain :— 
1. The motor fibres for the sphincter pupillae and the tensor cho- 
roideae from the root of the oculomotorius (§ 345, 2, 3). 
2. Sensory fibres for the cornea, which are distributed as excessively fine 
fibrils between the epithelium of the conjunctiva bulbi; they perforate the 
sclerotic. These fibres cause a reflex secretion of tears (N. lacrimalis) and 
closure of the eyelids (N. facialis). Sensory fibres are supplied to the iris 
(pain in iritis and in operations on the iris), the choroid (painful tension when 
the ciliary muscle is strained), and the sclerotic. 
3. Vaso-motor nerves for the blood-vessels of the iris, choroid, and Semi-diagrammatic representation of the nerves of the eyeball, the connections of the trigeminus 
and its ganglia, together with the facial and glosso pharyngeal nerves. 3. Branch to the 
inferior oblique muscle from the oculomotorius, with the thick short root, to the ciliary gan- 
glion (c) ; t, ciliary nerves; /, long root to the ganglion from the naso-ciliary (nc); s, sym- 
pathetic root from the sympathetic plexus (Ay) surrounding the internal carotid (G); d, first 
or ophthalmic division of the trigeminus (5), with the naso-ciliary (nc), and the terminal 
branches of the lachrymal (a), supra orbital (b), and frontal (f); e, second or superior 
maxillary division of the trigeminus; R, infra-orbital; n, spheno-palatine (Meckel’s) gang- 
lion with its roots; j, from the facial, and v, from the sympathetic; N, the nasal branches, 
and ppv the palatine branches of the ganglion; g, third or inferior maxillary division of the 
trigeminus; k, lingual; i i, chorda tympani; m, otic ganglion, with the roots from the 
tympanic plexus, the carotid plexus, and from the 3d branch, and with its branches to the 
auriculo-temporal (A), and to the chorda (i i); L, sub-maxillary ganglion with its roots 
from the tympanico-lingual, and the sympathetic plexus on the external artery (q). 7. 
Facial nerve—its great superficial petrosal branch; a, gang, geniculatum; /?, branch to 
the tympanic plexus; y, branch to the stapedius ; 6, anastomotic twig to the auricular branch 
of the vagus; i i, chorda tympani; S, stylo-mastoid foramen, 9. Glosso-pharyngeal—A, 
its tympanic branch ; tt and e, connections with the facial; U, terminations of the gustatory 
fibres of 9 in the circumvallate papillae; Sy, sympathetic with G g, s, the superior cervical 
ganglion; /, II, III, IV, the four upper cervical nerves; P, parotid, M, sub-maxillary 
gland. 
Fig. 518. Sec. 347.] 
FIFTH CRANIAL NERVE. 
747 
retina. They arise in part from the sympathetic root, and the anastomosis 
of the sympathetic with the ophthalmic division of the trigeminus ( Wegner). 
The iris and retina receive most of their vaso-motor nerves from the trigeminus 
itself (.Rogow), and few from the sympathetic ; according to Klein and Svetlin, 
the retinal vessels are not influenced either by stimulation or division of the 
sympathetic. 
4. Motor fibres for the dilator pupillae, which for the most part are de- 
rived from the sympathetic (Petit, 1727), through the sympathetic root of the 
ganglion and the anastomosis of the sympathetic with the trigeminus (Baiogh, 
Oehl). Some observers deny altogether the existence of a dilator pupillae 
muscle (§ 384). The ophthalmic division contains independent fibres for the 
dilatation of the pupil (Schiff), which arise in the medulla oblongata and pro- 
ceed directly into the ophthalmic (? or arise from the Gasserian ganglion— Oehl). 
It is not conclusively determined whether in man dilator fibres also proceed through the sym- 
pathetic root of the ciliary ganglion, and reach the iris through the ciliary nerves. In the dog 
and cat these fibres do not pass through the ciliary ganglion, but go directly along the optic 
nerve to the eye (Hensen and Votckers) through the Gasserian ganglion, to its ophthalmic 
branch and through the long ciliary nerves (fegorow). In birds, the dilator fibres run only in 
the fifth (Zeglinski). For the centre ($ 367, 8). 
After section of the trigeminus the pupil becomes contracted after a 
short period of dilatation (rabbit, frog), but this effect is not permanent. After 
excision of the superior cervical ganglion of the sympathetic, the power of 
dilatation of the pupil is not completely abolished. The narrowing of the 
pupil which follows section of the trigeminus in the rabbit, and which rarely 
lasts more than half an hour, may be regarded as due to a reflex stimulation of 
the oculomotorius fibres of the sphincter, in consequence of the painful stimu- 
lation caused by section of the trigeminus. 
Stimulation of the Cervical Sympathetic.—Either in the neck, or in its course to the eye, 
when the peripheral end of the cervical sympathetic is stimulated, besides causing constriction 
on the blood-vessels on that side of the head, there is dilatation of the ptipil, as well as contrac- 
tion of the smooth muscular fibres in the orbit and eyelids. The membrana orbitalis, which 
separates the orbit from the temporal fossa in animals, contains numerous smooth muscular 
fibres (muscular orbitalis). The corresponding membrane of the inferior orbital fissure [spheno- 
maxillary fissure] in man has a layer of smooth muscle, one millimetre thick, and arranged for 
the most part longitudinally. Both eyelids contain smooth muscular fibres which serve to close 
them; in the upper lid they lie as if they were a continuation of the levator palpebrse superioris, 
in the lower lid they lie close under the conjunctiva. Tenon's capsule also contains smooth 
muscular fibres. The sympathetic nerve supplies all these muscles (Heinr. Muller) —(the orbital 
muscle is partly supplied from the spheno-palatine ganglion); in animals, the retractor of the 
third eyelid at the inner angle of the eye is similarly supplied. Hence, stimulation of the sym- 
pathetic causes dilatation of the pupil and of the palpebral fissure, with protrusion of the eyeball. 
This result may be caused reflexly by strong stimulation of sensory nerves. Strong stimulation 
of the nerves of the sexual organs is followed by similar phenomena in the eye. The dilatation 
of the pupil, which occurs in children affected with intestinal worms, is perhaps an analogous 
phenomenon. The pupil is dilated when the spinal cord is stimulated (at the origin of the sym- 
pathetic), as in tetanus. 
Section of the cervical sympathetic, besides other effects, notably those on the blood- 
vessels on that side of the head and face (fig. 532), causes narrowing of the fissure between the 
eyelids, the eyeball sinks in its socket (and in animals, the third eyelid is relaxed and pro- 
truded). In dogs, section causes internal squint, as the external rectus receives some motor 
fibres from the sympathetic. (Origin of these fibres from the cilio-spinal region. Spinal Cord, 
l 362, I.) 
5. It is probable that trophic fibres occur in the trigeminus, and pass 
through the ciliary nerves to reach the eye. If the trigeminus be divided 
within the cranium, after six to eight days, inflammation, necrosis of the 
cornea, and ultimately complete destruction of the eyeball take place, con- 
stituting panophthalmia {Fodera, 1823; Magendie). 748 
FIFTH CRANIAL NERVE. 
[Sec. 347. 
Trophic Fibres in the fifth nerve.—In weighing the evidence for and against the exist- 
ence of trophic fibres, we must bear in mind the following considerations: r. Section of the 
trigeminus makes the whole eye insensible; the animal is therefore unconscious of direct 
injury to its eye, and cannot therefore remove any offending body. Dust or mucus, which may 
adhere to the eye, is no longer removed by the reflex closing of the eyelids; while, owing to the 
absence of the reflex, the eye is more open and is therefore subject to more injuries; the reflex 
secretion of tears is also arrested. Snellen (1857) fixed the ear of a rabbit in front of its eye so 
as to protect the latter and shield it from injuries, and he found that the inflammation and other 
events occurred at a later date, while, according to Meissner and Buttner, if th'e eye be protected 
by means of a complete capsule, the inflammation does not occur at all. There can be no doubt 
that the loss of the sensibility of the eye favors the occurrence of inflammation. But Meissner, 
Buttner, and Schiff observed that inflammation of the eye occurred when the trophic (most 
internal) fibres alone were divided, the eye at the same time retaining its sensibility; this would 
seem to indicate the existence of trophic fibres, but Cohnheim and Senftleben dispute the state- 
ment. Conversely, the sensibility of the eye may be abolished by partial section of the nerve, 
yet the eye does not become inflamed (Schiff). Ranvier, who denies the existence of trophic 
nerves, made a circular incision round the margin of the cornea through its superficial layers, so 
as to divide all the corneal nerves. Insensibility of the cornea was thereby produced, but never 
keratitis. Further, in man and animals, when they are unable to close their eyelids, there is red- 
ness with secretion of tears, or slight dryness and opacity of the surface of the eyeball (xerosis), 
but never the inflammation already described (Samuel). 2. We must also take into considera- 
tion the following: Section of the trigeminus paralyzes the vaso-motor nerves in the interior of 
the eyeball, which must undoubtedly cause a disturbance in the intraocular circulation. Accord- 
ing to Jesner and Griinhagen, the trigeminus also contains vaso-dilatorfibres, whose stimulation 
is followed by increased flow of blood to the eye, with consecutive excretion of the fibrin-factors 
and increase in the amount of albumin of the aqueous humor. 3. After section of the nerve, the 
intraocular tension is diminished (while stimulation of the nerve is followed by increase of 
the intraocular pressure (Hippell, Griinhagen). This diminution of the normal tension neces- 
sarily must alter the normal relation of the filling of the blood- and lymph-vessels, and also the 
movement of the fluids, upon which the normal nutrition is largely dependent. 4. Kiihne 
observed that stimulation of the corneal nerves was followed by contraction of the so-called 
corneal corpuscles. Perhaps the movements of these corpuscles may influence the normal move- 
ment of the lymph in the canalicular system of the cornea (§ 384); these movements, however, 
would seem to depend upon the nervous system, so that its destruction is likely to produce dis- 
turbance of nutrition. 
[There are three conditions on which the changes may depend—(1) mere loss of sensibility, 
which alone is not sufficient to explain the phenomena; (2) vaso-motor disturbance, which is 
excluded by the above facts, and also by the other consideration that, if the fifth nerve be 
divided and the superior cervical ganglion excised simultaneously, ophthalmia does not occur, 
and, in fact, excision of this sympathetic ganglion may modify the results of section of the fifth 
(Sinitzin). Thus, we are forced to (3) the theory of trophic fibres, whose centre is the Gasserian 
ganglion.] 
Pathological.—In cases of anaesthesia of the trigeminus in man, and, more rarely, in severe 
irritation of this nerve, inflammation of the conjunctiva, ulceration and perforation of the cornea, 
and finally panophthalmia, have been observed (Charles Bell). This condition has been called 
ophthalmia neuroparalytica. Samuel found that a similar result was produced by electrical 
stimulation of the Gasserian ganglion in animals. 
There are other affections of the eye depending upon disease of the vaso-motor nerves, 
which are quite different from the foregoing, as they never lead to degenerative changes. Such 
is ophthalmia intermittens (due to malaria), a unilateral, intermittent, excessive filling of the 
blood-vessels of the eye, accompanied by the secretion of tears, photophobia, often accompanied 
by iritis and effusion of pus into the chambers of the eye. This condition is regarded by Eulen- 
burg as a vaso-neurotic affection of the ocular blood-vessels. Pathological observations, as well 
as experiments upon animals, have shown that there is an intimate physiological connection 
between the vascular areas of both eyes, so that affections of the vascular area of one eye are 
apt to induce similar disturbances of the opposite eye. This serves to explain the fact that 
inflammatory processes in the interior of one eyeball are apt to produce a similar condition in 
the other eye. This is the so-called “ sympathetic ophthalmia.” Thus, stimulation of the 
ciliary nerves, or the fifth on one side causes dilatation of the blood-vessels not only on its own 
side but also on the other side as well (Jesner and Griinhagen). The pathological condition of 
glaucoma simplex, where the intraocular tension is greatly increased, is ascribed by Donders 
to irritation of the trigeminus. [Increased intraocular tension may be produced by irritation of 
the secretory fibres contained in the fifth nerve (Donders), by stimulating the nucleus of the 
trigeminus in the medulla oblongata (Hippell and Griinhagen), and also reflexly by irritation of 
the peripheral branches of the fifth, as by nicotin placed in the eye. It is possible, however, Sec. 347.] 
FIFTH CRANIAL NERVE. 
749 
that some forms of glaucoma are produced by diminished removal of the aqueous humor from 
the eye.] Unilateral secretion of tears, due to irritation of the ophthalmic division of the fifth, 
has been repeatedly observed, but unilateral cessation of tears, due to paralytic conditions, very 
rarely. 
II. Superior Maxillary Division (fig. 518, e).—It gives off— 
1. The delicate recurrent nerve, a sensory branch to the dura mater, 
which accompanies the vaso motor nerves, derived from the superior cervical 
ganglion of the sympathetic, and is distributed to the area of the middle 
meningeal artery. 
2. The subcutaneous malar or orbital (o') supplies by its temporal and 
orbital branches sensibility to the lateral angle of the eye and the adjoining 
area of skin of the temple and cheek. Certain fibres are said to be the true 
secretory nerves for tears. Compare N. lacrimalis, p. 745. 
3. The dental, anterior, posterior, and median, and with them the anterior 
fibres from the infraorbital nerve, supply sensory fibres to the teeth in the 
upper jaw, the gum, periosteum, and the cavities of the jaw (p. 746). The 
vaso-motor nerves of all these parts are supplied from the upper cervical gang- 
lion of the sympathetic. 
4. The infraorbital (R), after its exit from the infraorbital foramen, supplies 
sensory nerves to the lower eyelid, the bridge and sides of the nose, and the 
upper lip as far as the angle of the mouth. The accompanying artery receives 
its vaso-motor fibres from the superior cervical ganglion of the sympathetic. 
For the sweat-secreting fibres which occur in it (pig) see § 288. 
The spheno-palatine ganglion (Meckel’s—ri) forms connections with 
the second division. To it pass two short sensory root-fibres from the second 
division itself, which are called spheno-palatme. Motor fibres enter the gang- 
lion from behind, through the large superficial petrosal branch of the facial 
(/); and gray vaso-motor fibres (zi) from the sympathetic plexus on the 
carotid (the deep large petrosal nerve). The motor and vaso-motor fibres 
from the Vidian nerve, which reach the ganglion through the canal of the 
same name. 
Branches of Meckel’s Ganglion.—(1) The sensory fibres (N) which 
supply the roof, lateral walls, and septum of the nose (posterior and superior 
nasal) ; the terminal fibres of the naso-palatine pass through the canalis incisivus 
to the hard palate, behind the incisor teeth. The sensory inferior and posterior 
nasals for the lower and middle turbinated bones, and both lower nasal ducts, 
are derived from the anterior palatine branch of the ganglion, which descends 
in the palato-maxillary canal. Lastly, the sensory branches for the hard (/) 
and soft palate (pP) and the tonsils arise from the posterior palatine nerve. AH 
the sensory fibres of the nose (see also the Ethmoidal nerve), when stimulated, 
cause the reflex act of sneezing (§ 120). Preparatory to the act of sneezing, 
there is always a peculiar feeling of tickling in the nose, which is perhaps due 
to dilatation of the nasal blood-vessels. This dilatation is rapidly caused by 
cold, more especially when it is applied directly to the skin. The dilatation of 
the vessels is followed by an increased secretion of watery fluid from the nasal 
mucous membrane. Stimulation of the nasal nerves also causes a reflex secre- 
tion of tears, and it may also cause stand-still of the respiratory movements 
in the expiratory phase (Hering and Kratschmer)—(compare Respiratory cen- 
tre, § 368). (2) The motor branches descend in the posterior palatine 
nerve through the small palatine canal, and give off ([h) motor branches to the 
elevator of the soft palate and azygos uvulae (Nuhn). [Beevor and Horsley 
find that in the monkey the levator palati is not supplied from the facial nerve 
via the superficial petrosal nerve, for stimulation of the seventh nerve at its 
origin does not cause any movement in the palate. They suggest that this 750 
FIFTH CRANIAL NERVE. 
[Sec. 347. 
muscle is supplied by the spinal accessory nerve, perhaps through the upper 
branches of the pharyngeal plexus.] The sensory fibres for these muscles are 
supplied by the trigeminus. According to Politzer, spasmodic contraction of 
these muscles occasionally causes crackling noises in the ears. (3) The vaso- 
motor nerves of this entire area arise from the sympathetic root, i. e., from the 
upper cervical ganglion. (4) The root of the trigeminus supplies the secretory 
nerves of the mucous glands of the nasal mucous membrane. Stimulation 
excites secretion, while section of the trigeminus diminishes it with simulta- 
neous atrophic degeneration of the mucous membrane. Thus, trophic func- 
tions for the mucosa have been ascribed to the trigeminus (Aschenbrandt). 
Stimulation of the Ganglion.—Feeble electrical stimulation of the exposed ganglion causes 
a copious secretion of mucus and an increase of the temperature in the nose (Prevost), with dila- 
tion of the vessels (Aschenbrandt). [Meckel’s ganglion has been excised in certain cases of 
neuralgia (Walsham).'] 
III. Inferior Maxillary (g).—It contains all the motor fibres of the 
fifth, along with a number of sensory fibres; it gives off— 
1. The recurrent, which springs by itself from the sensory root, enters the 
skull through the foramen spinosum, and along with the nerve of the same 
name from the II division, supplies sensory fibres to the dura mater. Fibres 
proceed from it through the petroso-squamosal fissure to the mucous membrane 
of the cells of the mastoid process. 
2. Motor fibres for the muscles of mastication, viz., the masseteric, the 
two deep temporal nerves, and the internal and external pterygoid nerves. 
The sensory fibres for the muscles are supplied by the sensory fibres. 
3. The buccinator is a sensory nerve for the mucous membrane of the 
cheek, and the angle of the mouth as far as the lips. 
According to Jolyet and Laffont, it contains, in addition, vaso-motor fibres for the mucous 
membrane of the cheek, lower lip, and their mucous glands; but these fibres are probably 
derived from the sympathetic. 
Trophic Fibres.—As this region of the mucous membrane of the mouth ulcerates after sec- 
tion of the trigeminus, some have supposed that the buccinator nerve contains trophic fibres. 
But, as Rollett pointed out, section of the inferior maxillary nerve paralyzes the muscles of mas- 
tication on the same side, and hence the teeth do not act vertically upon each other, but press 
against the cheek. Owing to the loss of the sensibility of thq mouth, food passes between the 
gum and the cheek, where it may remain attached, undergo decomposition, and perhaps chemi- 
cally irritate the mucous membrane. At a later stage, owing to the wearing away of the teeth 
in an oblique manner, ulcers begin to form on the sound side. Hence, there is no necessity for 
assuming the existence of trophic fibres in this nerve. After section of the trigeminus, the nasal 
mucous membrane on the same side becomes red and congested. This is due to the fact that 
dust or mucus, not being removed from the nose by the usual reflex acts, remains there, irritates, 
and ultimately causes inflammation. 
4. The lingual nerve (k) receives at an acute angle the chorda tympani 
{it), a branch of the facial coming from the tympanic cavity. The lingual 
does not contain any motor fibres ; it is the sensory and tactile nerve of 
the anterior two-thirds of the tongue, of the anterior palatine arch, the tonsil, 
and the floor of the mouth. These, as well as all the other sensory fibres of the 
mouth, when stimulated, cause a reflex secretion of saliva (compare § 145). 
The lingual is accompanied by the nerve of taste (chorda) for the tip and mar- 
gins of the tongue {i. e., the parts not supplied by the glosso-pharyngeal). After 
section of the lingual nerve in man, Busch, Inzani, and Lusanna found that the 
tactile sensibility was lost in the half of the tongue, and there was loss of taste 
in the anterior part [two-thirds] of the tongue. The fibres which administer 
to the sense of taste do not as a rule belong to the lingual itself, but are de- 
rived from the chorda tympani (p. 755). According to Schiff, the lingual 
nerve is the gustatory nerve, and some cases of Erb and Senator support this 
view. Such cases, however, seem to be exceptions to the general rule. The Sec. 347.] 
FIFTH CRANIAL NERVE. 
751 
lingual nerve in the substance of the tongue is provided with small ganglia 
(.Remak, Stirling). Schiff observed that section of the lingual (and also of the 
hypoglossal) causes redness of the tongue, so that vaso-motor fibres are present 
in its course. It is unknown whether these are derived from the anastomoses 
of the Gasserian ganglion with the sympathetic. The lingual appears to receive 
vaso-dilator fibres from the chorda for the tongue and gum (§ 349). 
After section of the trigeminus, animals frequently bite their tongue, as they cannot feel the 
position and movement of this organ in the mouth. 
5. The inferior dental is the sensory branch to the teeth and gum of 
the lower jaw ; the vaso-motor fibres reach it from the superior cervical gang- 
lion. Before it passes into the canal in the lower jaw, it gives off the mylo- 
hyoid nerve, which supplies motor fibres to the mylo-hyoid and the anterior 
belly of the digastric, and also some fibres to the triangularis menti and the 
platysma; the muscular sensory nerves also lie in these branches. The 
mental nerve, which issues from the mental foramen, is the sensory nerve for 
the chin, lower lip, and the skin at the margin of the jaw. 
6. The auriculo-temporal gives sensory branches to the anterior wall 
of the external auditory meatus, the tympanic membrane, the anterior part of 
the ear, the adjoining region of the temple, and to the maxillary articulation. 
Fig. 519 shows the distribution of the branches of the trigeminus on the head, and the cer- 
vical nerves, so that the distribution of anaesthetic and hyperaesthetic areas may easily be made 
out. 
The otic ganglion (m) lies beneath the foramen ovale on the inner side of the 
third division. Its roots are—(1) short motor fibres from the third divi- 
sion ; (2) vaso-motor from the plexus around the middle meningeal artery 
(ultimately derived from the cervical ganglion of the sympathetic) ; (3) fibres (X) 
run from the tympanic branch of the glosso-pharyngeal to the tympanic plexus, 
and from thence through the canaliculus petrosus in the small superficial petrosal 
in the cranium, then through a small canal between the apex of the petrous 
bone and the sphenoid to reach the otic ganglion. Through the chorda tympani 
the facial nerve is constantly connected with the ganglion (fig. 519). 
The branches of the otic ganglion are—(1) motor twigs for the tensor 
tympani and tensor of the soft palate (these fibres are mixed with muscular 
sensory fibres—Ludwig and Politzer) ; (2) one or more branches connecting 
the ganglion with the auriculo-temporal are carried by the roots 2 and 3 from 
the sympathetic and glosso-pharyngeal, which the auriculo-temporal nerve (A), 
as it passes through the parotid gland (P), gives off to the gland. These are the 
secretory fibres for the parotid; their functions are stated in § 145. 
Section of the trigeminus is followed by inflammatory changes in the tympanic cavity 
(rabbit); the degree of inflammation varies much (.Berthold and Griinhagen). Section of the 
sympathetic or glosso-pharyngeal has no effect. 
The sub-maxillary ganglion (fig. 518, L) lies close to the convex arch of 
the tympanico-lmgual nerve and the excretory duct of the sub-maxillary gland 
(M) [in what Langley has called the chorda-lingual triangle]. Its roots are— 
(1) branches of the chorda tympani, i i, which undergo fatty degeneration 
after section of the facial nerve. This root supplies secretory fibres to the 
sub-maxillary and sub-lingual glands, but it also supplies vaso dilator fibres 
for the blood-vessels of the same glands (§ 145). In addition, fibres are sup- 
plied to the smooth muscular fibres in Wharton’s duct. All the fibres of the 
chorda do not pass into the gland ; some pass along with the lingual nerve 
into the tongue (see Chorda, under Facial Nerve). (2) The sympathetic 
root of the ganglion arises from the plexus around the submental branch of 
the external maxillary artery (q), i. e., ultimately from the superior cervical 752 
FIFTH CRANIAL NERVE. 
[Sec. 347. 
ganglion ; it passes to the gland, and contains secretory fibres, whose stimu- 
lation is followed by the secretion of thick concentrated saliva (trophic nerve 
of the gland (?)). It also carries the vaso-constrictor nerves to the gland 
(§ 144). (3) The sensory root springs from the lingual. Some of the fibres, 
after passing through the ganglion, supply the gland and its excretory ducts, 
while a few issue from the ganglion, and again join the tympanico-lingual nerve 
to reach the tongue. 
Muse. temporalis 
Muse, masseter 
N. hypoglossus. 
Muse, splenius. 
Muse, steniocleidomastoldeus. 
N. accessorius. 
Muse, levator anguli scapulae. 
Platysma inyoide •. 
Muse, stern oh yoideus 
Muse, sternothyreoideua. 
Muse, cucul laris or trapezium. 
N. dorsalis scapulae. 
Muse, omohyoideus. 
Nn. thoracici anter.'ores.« 
N. axillaris. 
N. thoracicua lciigoa. 
N. phrenicus. 
Erb’s 
Supraclavicul ar- 
Doint. 
Plexus 
brachial is. 
Fig- 5*9- 
Distribution of the sensory nerves on the head as well as the position of the motor points on 
the neck. SO, area of distribution of the supraorbital nerve; ST, supratrochlear; IT, 
infratrochlear; L, lachrymal; AT, ethmoidal; IO, infraorbital; B, buccinator; SAT, sub- 
cutaneous malse; A T, auriculo-temporal; AM, great auricular; OMj, great occipital; OMi, 
lesser occipital; three cervical nerves; CS, cutaneous branches of the cervical nerves; 
C, W, region of the central convolutions of the brain; SC, region of the speech-centre 
(third left frontal convolution). 
[Action of Nicotin.—In the dog and cat Langley has shown that the 
ganglion which is called the “sub-maxillary ganglion ” in these animals should 
more properly be called the sub-lingual ganglion, as the chorda tympani has 
no connection with the nerve-cells of the so-called sub-maxillary ganglion, so 
that this ganglion, together with nerve-cells lying near it between the chorda- 
lingual nerve and Wharton’s duct, and also some cells lying outside the hilum 
of the sub-maxillary gland, are for the greater part in the course of nerve-fibres 
to the sub-lingual gland. The real sub-maxillary ganglion lies in the hilum of Sec. 347.] 
FIFTH CRANIAL NERVE. 
753 
the corresponding gland. The sympathetic fibres which pass along the facial 
artery include some—chiefly fine—medullated nerve-fibres, but the sympathetic 
nerve-fibres are not connected with the nerve-cells which occur in the course 
of the chorda tympani; they run along the artery of the gland to the ganglion 
at the hilum of the sub-maxillary gland.] 
[Experimental evidence supports the above conclusions, based on histological examination, for 
stimulation of the chorda-lingual and “ sub-maxillary ganglion ” after section of the chorda near 
the lingual does not cause secretion, at least to any extent, from the sub-maxillary gland, but it 
causes slight secretion from the sub-lingual gland. The action of nicotin also confirms the above 
statements. Nicotin paralyzes the nerve-cells of various sympathetic ganglia without paralyzing 
the peripheral ends of the nerve-fibres (Langley and Dickinson). 
If nicotin be injected into the vein of a dog, stimulation of the chorda-lingual nerve causes no 
secretion either in the sub-lingual or sub-maxillary gland, but if the hilum of the sub-maxillary 
gland be stimulated, secretion takes place, because the fibres issuing from the sub-maxillary 
hilum ganglion are excited.] 
[After the local application of nicotin to the “sub-maxillary ganglion ” and the adjacent gang- 
lionic cells, stimulation of the chorda-lingual nerve causes a secretion in the sub-maxillary gland, 
but none in the sub-lingual; while the local application of nicotin to the sub-maxillary hilum 
ganglion prevents the sub-maxillary secretion which, under ordinary circumstances, results from 
stimulation of the chorda-lingual nerve or chorda tympani. But nicotin thus applied does not 
affect the secretion obtained from the sub-maxillary gland after stimulation of the sympathetic 
fibres, so that the secretory fibres of the sympathetic are not connected with nerve-cells in the 
hilum of the gland; they are, as we shall see, connected with nerve-cells in the superior cervical 
ganglion (g 356).] 
[By the nicotin method of investigation it has been shown that the vaso-dilator fibres of the 
chorda tympani are connected with nerve-cells, but the latter are not so easily paralyzed as 
the peripheral nerve-cells connected with the secretory fibres of the chorda.] 
[By the same method Langley has shown that the vaso-constrictor fibres in the cervical sym- 
pathetic, and the vaso-dilator fibres in the same trunk, are only connected with nerve-cells in the 
superior cervical ganglion, and not anywhere else in their course from their origin in the medulla 
to their ultimate endings.] 
Pathological.—Trismus, or spasm of the muscles of mastication supplied by the third divi- 
sion, is usually bilateral; it may be clonic in its nature (chattering of the teeth), or tonic, when 
it constitutes the condition of lock-jaw or trismus. The spasms are usually individual symptoms 
of more extensive convulsions; more rarely when they occur alone, they are symptomatic of dis- 
ease of the cerebrum, medulla, pons, and cortex of the motor convolutions (Eulenburg). The 
spasms may be caused reflexly, e. g., by stimulation of the sensory nerves of the head. 
Paralysis.—Degeneration of the motor nuclei, or an affection of the intracranial root of 
the nerve, causes paralysis of the muscles of mastication, which is very rarely bilateral. Paraly- 
sis of the tensor tympani is said to cause difficulty of hearing (Romberg), or buzzing in the ears 
{Benedict). We require further observations upon this point, as well as upon paralysis of the 
tensor of the soft palate. 
Neuralgia may occur in all branches of the fifth. It consists of severe attacks of pain shoot- 
ing into the expansions of the nerves. It is usually unilateral, and in fact is often confined to 
one branch, or even to a few twigs of one branch. The point from which the pain proceeds is 
frequently the bony canal through which the branch issues. The ear, dura mater, and tongue 
are rarely attacked. The attack is not unfrequently accompanied by contractions or twitchings 
of the corresponding group of the facial muscles. The twitchings are either reflex, or are due to 
direct peripheral irritation of the fibres of the facial nerve, which are mixed with the terminal 
branches of the trigeminus. The reflex twitchings may be extensively distributed, involving even 
the muscles of the arm and trunk. 
Redness, or congestion of the affected part of the face, is not an unfrequent symptom in 
neuralgia, and it may be accompanied by increased or diminished secretion from the nasal and 
buccal mucous membranes. This is a reflex phenomenon, the sympathetic being affected. Re- 
flex stimulation of the vaso motor nerves frequently gives rise to disturbance of the cerebral activ- 
ities, owing to changes in the distribution of the blood in the head. Ludwig and Dittmar found 
that stimulation of sensory nerves caused a reflex contraction of the arterial blood-vessels, and 
increase of the blood-pressure in the cerebral vessels. Sometimes there is melancholy or hypo- 
chondriasis, and in one case of violent pain in the inferior maxillary nerve, the attack was accom- 
panied by hallucinations of vision. 
The trophic disturbances which sometimes accompany affections of the trigeminus are par- 
ticularly interesting. They are—a brittle character of the hair, which frequently becomes gray, 
or may fall out; circumscribed areas of inflammation of the skin, and the appearance of a 
vesicular eruption upon the face [often following the distribution of certain nerves], and consti- 754 
SIXTH AND SEVENTH CRANIAL NERVES. 
[Sec. 347. 
tilting herpes, which may also occur on the cornea, constituting the neuralgic herpes corneae 
of Schmidt-Rimpler. Lastly, there is the progressive atrophy of the face which is usually 
confined to one side, but may occur on both sides (Eulenburg). It is caused very probably by 
a trophic affection of the trigeminus, although the vaso-motor nerves may also be affected reflexly. 
Landois found that in the famous case of Romberg, a man named Schwahn, the sphygmo- 
graphic tracing of the carotid pulse of the atrophied side was distinctly smaller than on the sound 
side. 
Urbantschitsch made the remarkable observation that stimulation of the branches of the tri- 
geminus, especially those going to the ear, caused an increase of the sensation of light in the 
person so stimulated. Blowing upon the cheeks or nasal mucous membrane, electrical stimula- 
tion, the use of snuff, smelling strong perfumes—all temporarily increase the sensation of light. 
The senses of taste and smell, as well as the sensibility of certain areas of the skin, can all be 
exalted reflexly by gentle stimulation of the trigeminus. In intense affections of the ear, whereby 
the fibres of the trigeminus are often affected sympathetically, these sensory functions may be 
diminished. As the ear-malady begins to improve, the excitability of these sense organs also 
again begins to improve. 
[Complete section of the trigeminus results in loss of sensibility in all 
the parts supplied by it (fig. 519), including one side of the face, temple, part 
of the ear, the fore part of the head, conjunctiva, cornea, mouth, gums, 
Schneiderian mucous membrane, anterior two-thirds of the tongue, and part of 
pharynx. In drinking from a vessel, the patient feels as if one side of it were 
cut away. The muscles of mastication are paralyzed on that side, food is not 
chewed on one side, and fur accumulates on the tongue on that side. The 
mucous membranes tend to ulcerate, that of the mouth being chafed by the 
teeth, the gums get spongy, the nasal mucous membrane tends to ulcerate, so 
that smelling is interfered with, and ammonia excites no reflex acts, while the 
eye undergoes panophthalmia.] 
[Gowers is of opinion that the sensation of taste on the posterior part of the tongue, soft palate, 
and palatine arch depends on the fifth nerve and not on theglosso-pharyngeal nerve.] 
348. VI. NERVUS ABDUCENS.—Anatomical.—It rises slightly in front of and partly 
from the nucleus of the facial nerve (which corresponds to the anterior horn of the spinal cord), 
from large-celled ganglia in the deeper part of the anterior region of the fourth ventricle (emi- 
nentia teres, figs. 516, 520). [Its nucleus is connected with the nucleus of the third nerve of the 
opposite side. It appears at the posterior margin of the pons (fig. 517, VI). This nerve has a 
very long course before it enters the orbit, and as it bends over the posterior margin of the pons, 
it is liable to be compressed there or from pressure upon the tentorium cerebelli, so that both 
nerves are very liable to paralysis.] 
Function.—It is the voluntary nerve of the external rectus muscle. In co- 
ordinated movements of the eyeballs, however, it is involuntary. 
Anastomoses.—Branches reach it from the sympathetic upon the cavernous sinus (fig. 518). 
A few come from the trigeminus, and their function is analogous to similar fibres supplied to the 
trochlearis and oculomotorius. 
Pathological.—Complete paralysis causes squinting inwards [or convergent squint~\ and con- 
sequent diplopia. [The eye cannot be rotated outwards beyond the middle line, the double 
images are in the same horizontal plane and vertical, the false one is to the left of the patient’s 
eye when the left eye is affected (fig. 515, 2). The feeling of giddiness is often severe. There 
is secondary deviation to the inner side, and the head is turned towards the affected side.] In 
dogs, section of the cervical sympathetic causes a slight deviation of the eyeball inwards [Petit). 
This is explained by the fact that the abducens receives a few motor fibres from the cervical 
sympathetic. Spasm of the abducens causes external squint. 
Squint.—In addition to paralysis or stimulation of certain nerves producing squint, it is to be 
remembered that it may also be caused by a primary affection of the muscles themselves, e.g., 
congenital shortness, contracture, or injuries of these muscles. It may also be brought about 
owing to opacities of the transparent media of the eye; a person with, say, an opacity of the 
cornea, rotates the affected eye involuntarily, so that the rays of light may enter the eye through 
a clear part of the media. 
349- VII. NERVUS FACIALIS.—Anatomical.—This nerve consists entirely of effer- 
ent fibres, and arises from the floor of the fourth ventricle from the “ facial nucleus ” (figs. 
516, 7, 520), which lies behind the origin of the abducens, and also by some fibres from the Sec. 349.] 
SEVENTH CRANIAL NERVE. 
755 
nucleus of the abducens [although Gowers’ observations do not confirm this (§ 366)]. Other fibres 
arise from the cerebrum of the opposite side ($ 378, I). It consists of two roots, the smaller— 
portio intermedia of Wrisberg—forms a connection with the auditory nerve (see § 350). The 
original fibres of the portio intermedia are developed from the glosso-pharyngeal nucleus 
(Sapolini). It would thus appear that the sensory and gustatory fibres which are present in the 
chorda tympani enter it through these fibres [Duval, Schultze, Vulpian), so that the portio inter- 
media is a special part of the nerve of taste, which becomes conjoined with the facial, and runs 
to the tongue in the chorda. Along with the auditory nerve, it traverses the porus acusticus 
internus, where it passes into the facial or Fallopian canal. At first it has a transverse direction 
Scheme of the disposition of the nuclei of origin of the cranial nerves in the region 
of the bulb and pons. 
Fig. 520. 
as far as the hiatus of this canal; it then bends at an acute angle at the “ knee ” (a) above the 
tympanic cavity, to descend in an osseous canal in the posterior wall of this space (fig. 518). It 
emerges from the stylo-mastoid foramen, pierces the parotid gland, and is distributed in a fan- 
shaped manner (pes anserinus major). [The superficial origin is at the lower margin of the pons, 
in the depression between the olivary body and the restiform body, as indicated in fig. 517, 
VII «.] 
Its branches are: 1. The motor large superficial petrosal (/). It 
arises from the “knee ” or geniculate ganglion within the Fallopian canal, in 
the cavity of the skull, runs upon the anterior surface of the temporal bone, 
traverses the foramen lacerum medium on the under surface of the base of the 
skull, and passes through the Vidian canal to reach the spheno-palatine 
ganglion (p. 749). It is uncertain whether this nerve conveys sensory 
branches from the second division of the trigeminus to the facial. 
2. Connecting branches (/9) pass from the geniculate ganglion to the otic 
ganglion. For their course and function, see Otic ganglion (p. 751). 
3. The motor branch to the stapedius muscle (7). 
4. The chorda tympani (ii') arises from the facial before it emerges at the 
stylo-mastoid foramen (j), runs through the tympanic cavity (above the tendon 
of the tensor tympani, between the handle of the malleus and the long process 
of the incus), passes out of the skull through the petro-tympanic fissure, and 
then joins the lingual nerve at an acute angle (p. 750, 4). Before it unites 
with this nerve, it exchanges fibres with the otic ganglion (m). Thus, sensory 
fibres can enter the chorda from the third division of the trigeminus, which 
may run centripetally to the facial to be distributed along with it. In the same 
way, sensory fibres may pass from the lingual nerve through the chorda into the 
facial (Longet). Stimulation of the chorda—which even in man may be done 
in cases where the tympanic membrane is destroyed—causes a prickling feeling 756 
[Sec. 349. 
SEVENTH CRANIAL NERVE. 
in the anterior margins and tip of the tongue (Troltsch). O. Wolfe found 
that the section of the chorda in man abolished the sensibility for tactile and 
thermal stimuli upon the tip of the tongue; and the same was true of the 
sense of taste in this region. It is supposed by Calori that these fibres enter 
the facial nerve at its periphery (especially through the auriculo-temporal into 
the branches of the facial), that they run in a centripetal direction in the 
facial, and afterwards pursue a centrifugal course in the chorda. [It is possible 
that sensory fibres pass from the spheno-palatine ganglion of the fifth through 
the Vidian nerve and large superficial petrosal to enter the facial. These 
fibres may be those that appear in the seventh as the chorda fibres which 
administer to taste. Bigelow asserts that the chorda tympani is not a branch 
of the facial, but the continuation of the nervus intermedius of Wrisberg.] 
The chorda also contains secretory and vaso dilator fibres for the sub-max- 
illary and sub-lingual glands (§ 145). 
[The chorda is composed of several bundles of medullated nerve-fibres, 
chiefly small (2.5 to 3.5 fi), mixed with a few medium-sized ones. It has 
already been pointed out (p. 751) that the secretory and vaso-dilator fibres of 
the chorda are connected with nerve-cells before they reach their ultimate 
endings in the glands; the nerve-cells for the sub-lingual gland lying in 
what is usually called the sub-maxillary ganglion, some cells in the chorda- 
lingual triangle, and others in the gland itself, while the nerve-fibres of the 
chorda for the sub-maxillary gland are chiefly connected with the ganglion in 
the hilum of the sub-maxillary gland.] 
Gustatory Fibres.—The chorda also contains fibres administering to the 
sense of taste, for the margin and tip of the tongue (anterior two-thirds), 
which are conveyed to the tongue along the course of the lingual. Urbant- 
schitsch made observations upon a man whose chorda was freely exposed, and 
in whom its stimulation in the tympanic cavity caused a sensation of taste (and 
also of touch) in the margins and tip of the tongue. 
It would seem, therefore, that the gustatory fibres of the chorda have 
their origin in the glosso pharyngeal nerve. They may reach the chorda: 
1. Through the portio intermedia of Wrisberg, as already mentioned. 
2. There is a channel beyond the stylo-mastoid foramen, viz., through the ramus communicans 
cum glosso pharyngeo (fig. 518), which passes from the last-mentioned nerve in that branch of 
the facial which contains the motor fibres for the stylo-hyoid and posterior belly of the digastric 
muscle (Henle’s N. styloideus). This nerve also supplies muscular sensibility to the stylo-hyoid 
and posterior belly of the digastric muscles. It is also assumed that, by means of these anasto- 
moses, motor fibres are supplied by the facial to the glosso pharyngeal nerve. 3. A union of the 
glosso-pharyngeal and facial nerves occurs in the tympanic cavity. The tympanic branch of 
the glosso-pharyngeal (A) passes into this cavity, where it unites in the tympanic plexus with 
the small superficial petrosal nerve (/3), which springs from the knee on the facial. The 
gustatory fibres may first pass into the otic ganglion, which is always connected with the 
chorda (Otic ganglion, p. 751, 3). Lastly, a connection is described through a twig (rr) from 
the petrous ganglion of the glosso-pharyngeal, direct to the facial trunk within the Fallopian 
canal (Garibaldi). 
According to some observers, the chorda contains vaso dilator fibres for 
the anterior two-thirds of the tongue ( Vulpiari). 
Pseudo-motor Action of the Chorda.—From one to three weeks after 
the section of the hypoglossal nerve, stimulation of the chorda causes move- 
ments in the tongue (Philippeaux and Vulpiari). These movements are not so 
energetic as, and occur more slowly than, those caused by stimulation of the 
hypoglossal. Nicolin first excites, then paralyzes, the motor effect of the chorda. 
Even after cessation of the circulation, stimulation of the chorda causes move- 
ments. Heidenhain supposes that, owing to the stimulation of the chorda, 
there is an increased secretion of lymph within the musculature, which acts as 
the cause of the muscular contraction. He called this action 11 pseudo-motor." Sec. 349.] 
SEVENTH CRANIAL NERVE. 
757 
[If, after the union of the central end of the lingualis and the peripheral end of the hypo- 
glossal nerve, the lingualis be stimulated, there is a genuine contraction of the musculature of 
the tongue on that side. A pseudo-motor contraction is easily distinguished from a true contrac- 
tion, for when a telephone is connected with the tongue, on stimulating the hypoglossal the tone 
of the tetanus thereby produced is heard, but on stimulating the lingual, although the pseudo- 
motor contractions occur, no sound is heard (Rogowicz).] 
5. Connection with Vagus.—Before the chorda is given off, the trunk of the facial comes 
into direct relation with the auricular branch of the vagus (d), which crosses it in the mastoid 
canal, and supplies it with sensory nerves (see Vagus). 
6. Peripheral Branches.—After the facial issues from its canal, it sup- 
plies motor fibres to the stylo-hyoid and posterior belly of the digastric, 
occipitalis, all the muscles of the external ear, the muscles of expression, buc- 
M. frontalis. 
M. corrugator supercilii. 
-VI. orbicular palpebr. 
M. compressor nasi etpyramnasi. 
Upper branches of the Facial. 
Trunk of the Facial. 
M. levator lab. sup. alaque nasi. 
M. levator lab. sup. propr. 
M. zygomatic minor. 
M. dilatat. narium. 
Mm retrahens et attolens auricul. 
Muse, occipitalis. 
Middle branches of the Facial. 
M. zygomatic major. 
M. stylohyoideus. 
M. digastricus. 
M. orbicularis oris. 
Lower branches of the Facial. 
M. levator menti. 
M. quadratus menti. 
M. triangularis inenti. 
Fig. 521. 
Motor points of the facial nerve and the facial muscles supplied by it, 
cinator and platysma. The facial also contains secretory fibres for the face 
(compare § 288). 
Although most of the branches of the facial are under the influence of the will, yet most men 
cannot voluntarily move the muscles of the nose and ear. 
Anastomoses of the Facial Nerve.—The branches of the seventh 
nerve on the face anastomose with those of the trigeminus, whereby sensory 
fibres are conveyed to the muscles of expression. The sensory branches of 
the auricular branch of the vagus, and the great auricular, enter the peripheral 
ends of the facial, and supply sensibility to the muscles of the ear; while the 
sensory fibres of the third cervical nerve similarly supply the platysma with 
sensibility. Section of the facial at the stylo-mastoid foramen is painful, but 758 
SEVENTH CRANIAL NERVE. 
[Sec. 349. 
it is still more so if the peripheral branches on the face are divided (.Recurrent 
sensibility, § 355). 
Pathological.—In all cases of paralysis of the facial, the most important point to deter- 
mine is whether the seat of the affection is in the periphery, in the region of the stylo-mastoid 
foramen, or in the course of the long Fallopian canal, or is central (cerebral) in its origin. This 
point must be determined by an analysis of the symptoms. Paralysis at the stylo-mastoid 
foramen is very frequently rheumatic, and probably depends upon an exudation compressing 
the nerve; the exudation probably occupying the lymph space described by Riidinger on the 
inner side of the Fallopian canal, between the periosteum and the nerve, and which is a contin- 
uation of the arachnoid space. Other causes are—inflammation of the parotid gland, direct 
injury, and pressure from the forceps during delivery. In the course of the canal, the causes 
are—fracture of the temporal bone, effusion of the blood into the canal, syphilitic effusions, and 
caries of the temporal bone; the last sometimes occurs in inflammation of the ear. Amongst 
intracranial causes are—affections of the membranes of the brain, and of the base of the 
skull in the region of the nerve, disease of the “facial nucleus;” lastly, affection of the 
cortical centre of the nerve and its connections with the nucleus. [No nerve is so liable as the 
seventh to be paralyzed independently.] 
Symptoms of Unilateral Paralysis of the Facial [or Bell’s Paralysis].—1. Paralysis 
of the muscles of expression: The forehead is smooth, without folds, the eyelids remain open 
(lagophthalmus paralyticus), the outer angle being slightly lower. The anterior surface of 
the eye rapidly becomes dry, the cornea is dull, as, owing to the paralysis of the orbicularis, the 
tears are not properly distributed over the conjunctiva, and, in fact, in consequence of the dryness 
of the eyeball, there may be temporary inflammation (keratitis xerotica). In order to pro- 
tect the eyeball from the light, the patient turns it upwards under the upper eyelid {Bell), 
relaxes the levator palpebrse, which allows the lid to fall somewhat {Basse). The nose is im- 
movable, while the naso-labial fold is obliterated. As the nostrils cannot be dilated, the sense 
of smell is interfered with. The impairment of the seilse of smell depends more, however, 
upon the imperfect conduction of the tears, owing to paralysis of the orbicularis palpebrarum 
and Horner’s muscle, thus causing dryness of the corresponding side of the nasal cavity. 
Horses, which distend the nostrils widely during respiration, after section of both facial nerves, 
are said by Cl. Bernard to die from interference with the respiration, or at least they suffer from 
severe dyspnoea {Ellenberger). The face is drawn towards the sound side, so that the nose, 
mouth, and chin are oblique. Paralysis of the buccinator interferes with the proper formation 
of the bolus of food; the food collects between the cheek and the gum, from which it is 
usually removed by the patient with his fingers; saliva and fluids escape from the angle of the 
mouth. During vigorous expiration the cheeks are puffed outwards like a sail. The speech 
may be affected owing to the difficulty of sounding the labial consonants (especially in double 
paralysis), and the vowels u, u (ue), 0 (oe); while the speech, in paralysis of the branches to 
both sides of the palate, becomes nasal ($ 628). The acts of whistling, sucking, blowing, and 
spitting are interfered with. In double paralysis, many of these symptoms are greatly inten- 
sified, while others, such as the oblique position of the features, disappear. The features are 
completely relaxed; there is no mimetic play of the features, the patients weep and laugh, “ as it 
were, behind a mask ” {Romberg). 2. In paralysis of the palate, when the uvula is directed 
towards the sound side, and the paralyzed half of the palate hangs down and cannot be raised 
(large superficial petrosal nerve), it is not determined to what extent this condition influences 
the act of deglutition and the formation of the consonants. 3. Taste is interfered with; 
either it is absent on the anterior two-thirds of the tongue, or the sensation is delayed and 
altered. This is due to an affection of the chorda. 4. Diminution of saliva on the affected 
side was first described by Arnold; still, we must determine to what extent a simultaneous 
affection of the sense of taste may cause a reflex interference with the secretion of saliva, or 
whether rapid removal of the saliva through the opened lips and angle of the mouth may cause 
the dryness on the affected side of the mouth. 5. Loux pointed out that hearing is affected, 
the sensibility to sounds being increased (oxyakoia, hyperakusis willisiana). The paralysis 
of the stapedius muscle makes the stapes loose in the fenestra ovalis, so that all impulses from 
the tympanum act vigorously upon the stapes, which consequently excites considerable vibrations 
in the fluid of the inner ear. More rarely, in paralysis of the stapedius, it has been observed 
that low notes are heard at a greater distance than on the sound side {Lucae, Mow). 6. As the 
facial in man appears to contain fibres for the secretion of sweat, this explains the loss of the 
power of sweating in the face when the nerve begins to atrophy {Strauss, Block). 
Section of the facial in young animals causes atrophy of the corresponding muscles. 
The facial bones are also imperfectly developed; they remain smaller, and hence the bones of 
the sound side of the face grow towards, and ultimately across, the middle line towards the 
affected side {Brown-Slquard). The salivary glands also remain smaller. 
Stimulation—or irritation in the area of the facial—causes partial or extensive, either Sec. 349.] 
NERVUS ACUSTICUS. 
759 
direct or reflex, tonic or clonic spasms. The extensive forms are known as “ mimetic facial 
spasm.” Amongst the partial forms are tonic contraction of the eyelid (blepharospasm), 
which is most common; and is caused reflexly by stimulation of the sensory nerves of the eye, 
e.g., in scrofulous ophthalmia, or from excessive sensibility of the retina (photophobia). More 
rarely, the excitement proceeds from some distant part, eg., in one case recorded by v. Grafe, 
from inflammatory stimulation of the anterior palatine arch. The centre for the reflex is the 
facial nucleus. The clonic form of spasm—spasmodic winking (spasmus nictitans)—is 
usually of reflex origin, due to irritation of the eye, the dental nerves, or even of more distant 
nerves. In severe cases, the affection may be bilateral, and the spasms may extend to the 
muscles of the neck, trunk, and upper extremities. Contraction of the muscles of the lip may 
be excited by emotions (rage, grief), or reflexly. Fibrillar contractions occur after section of 
the facial as a “ degeneration phenomenon ” (p. 605). [If the facial be torn out at the stylo- 
mastoid foramen, there is paralytic oscillation of the lip muscles (Schiff). If, in such an 
animal, the posterior root of the annulus of Vieussens be stimulated electrically, as it contains 
vaso-dilator fibres (Daslre and Moral), not only do the blood-vessels of the cheek and lips 
dilate, but the veins pulsate and florid blood escapes from the veins, just as occurs in the sub- 
maxillary gland when the chorda is stimulated. On stimulating the ansa, alter section of the 
seventh, there is a pseudo-motor effect on the muscles of the cheek and lips, so that there is 
an analogy between the chorda and the ansa (Rogowicz).~\ Intracranial stimulation of the 
most varied description may cause spasms. Lastly, facial spasm may be part of a general spas- 
modic condition, as in epilepsy, chorea, hysteria, tetanus. Aretaeus (81 A. d.) made the inter- 
esting observation that the muscles of the ear contracted during tetanus. Very rarely have 
spasmodic elevation of the palate and increased salivation been described as the result of irrita- 
tion of the facial (Leube). Moos observed a profuse secretion of saliva on stimulating the 
chorda during an operation on the tympanic cavity. 
350. VIII. NERVUS ACUSTICUS—Arises by two roots (Slieda); a larger anterior 
with coarser fibres and a smaller posterior one with finer fibres. From the former proceeds the 
vestibular nerve, and from the latter the cochlear nerve; these are separated in the sheep 
and horse (.Horbaczewski). Each root springs from a median and a lateral nucleus, so that there 
are four nuclei (fig. 520). The vestibular branch is chiefly connected with the gray matter 
in relation with the cerebellum, and these fibres may be connected with equilibration. The 
chief mass of the cochlear nerve crosses to the other side and passes to the posterior part of 
the corpora quadrigemina, the internal geniculate body, and finally to the temporo-sphenoidal 
lobe of the cerebrum ($ 378, IV, 2). After extirpation of the temporo-sphenoidal lobe, these 
fibres atrophy into the internal capsule and internal geniculate body (v. Monakow). The striae 
acusticae form a second decussating projection system like a chiasma. The origin of both 
acoustic nerves are connected by commissures in the brain (Flechsig). 
In the course of the internal auditory meatus, the auditory and portio-intermedia of the facial 
exchange fibres, but the physiological significance of this is unknown. 
Function.—The acusticus or auditory nerve has a double function : 1. 
It is the nerve of hearing ; when stimulated, either at its origin, in its course, 
or at its peripheral terminations, it gives rise to sensations of sound. Every injury, 
according to its intensity and extent, causes hardness of hearing or even deaf- 
ness. 
2. Quite distinct from the foregoing is the other function, which depends 
upon the semicircular canals, viz., that stimulation of the peripheral expan- 
sions in the ampullae influences the movements necessary for maintaining the 
equilibrium of the body. 
Brenner’s Formula.—The relation of the auditory nerve to the galvanic current is very 
important. In healthy persons, when there is closure at the cathode, there is the sensation of a 
clang (or tone) in the ear, which continues with variations while the current is closed. When 
the anode is opened, there is a feebler tone (Brenner's Nor?7ial Acoustic Formula). This clang 
coincides exactly with the resonance fundamental tone of the sound-conducting apparatus of the 
ear itself. 
Pathological.—Increased sensibility of the auditory nerve in any part of its course, its centre, 
or peripheral expansions causes the condition known as hyperakusis, which usually is a sign of 
greatly increased nervous excitability, as in hysteria. When excessive, it may give rise to dis- 
tinctly painful impressions, which condition is known as acoustic hyperalgia (Eulenburg). 
Stimulation of the parts above named causes sensations of sound, the most common being the 
sensation of singing in the ears, or tinnitus. This condition is often due to changes in the 
amount of blood in the blood-vessels of the ear—either anaemic or hypersemic stimulation. There 
is well-marked tinnitus after large doses of quinine or salicin, due to the vaso-motor effect of these 760 
SEMICIRCULAR CANALS. 
[Sec. 350. 
drugs upon the vessels of the labyrinth (Kirchner). Not unfrequently, in cases of tinnitus, the 
reaction due to the galvanic current is often increased. More rarely there is the so-called “para- 
doxical reaction ”—i. e., on applying the galvanic current to one ear, in addition to the reaction 
in this ear, there is the opposite result in the non-stimulated ear. In other cases of disease of the 
auditory nerve, noises rather than musical notes are produced by the current; stimulation, espe- 
cially of the cortical centre of the auditory nerve, chiefly in lunatics, may cause auditory delu- 
sions ($ 378, IV). According as the excitability of the auditory nerve is diminished or abol- 
ished, there is the condition of nervous hardness of hearing (hypakusis), or nervous deafness 
(anakusis). 
The Semicircular Canals of the Labyrinth.—Section or injury to these 
canals does not interfere with hearing, but other important symptoms follow 
their injury, such as disturbances of equilibrium due to a feeling of giddiness, 
especially when the injury is bilateral (Flourens). This does not occur in fishes 
(.Kiesselbach). The pendulum-like movement of the head, in the direc- 
tion of the plane of the injured canal, is very characteristic. If the horizontal 
canal be divided, the head (of the pigeon) is turned alternately to the right and 
left. The rotation takes place especially when the animal is about to execute 
a movement; when it is at rest, the movement is less pronounced. The phe- 
nomenon may last for months, and injury to the posterior vertical canals causes 
a well-marked up and down movement or nodding of the head, the animal 
itself not unfrequently falling forwards or backwards. Injury to the superior 
vertical canals also causes pendulum-like vertical movements of the head, while 
the animal often falls forwards. When all the canals are destroyed, various 
pendulum-like movements are performed, while standing is often impossible. 
Breuer found that electrical stimulation of the canals caused rotation of the 
head, while Landois on applying a solution of salt to the canals observed pen- 
dulum-like movements, which, however, disappeared after a time. A 25 per 
cent, solution of chloral dropped into the ear of a rabbit causes, after fifteen 
minutes, similar effects to destruction of the canals ( Vulpian). Section of the 
acoustic nerves within the cranium has the same result (.Bechterew). 
[From the foregoing and other experiments there seems to be no doubt that 
the semicircular canals and the impressions proceeding from them form a most 
important part of the afferent mechanism of equilibration. Marked disturb- 
ances of equilibrium take place in all animals after section of the auditory nerve, 
or destruction of the semicircular canals, the effects being most marked and per- 
sistent when the canals on both sides are destroyed, so that it may be taken that 
certain disturbances of equilibrium stand in causal relation to lesions of the 
semicircular canals. The other effects associated with injury of these canals are 
movements of the head in the plane of the injured canal, and movements 
of the eyeballs. These organs seem to be in no way associated with hearing. 
Animals with their semicircular canals destroyed still hear by means of aerial 
vibrations, while an animal without its cochlea is deaf/but its equilibration is 
not thereby affected.] 
Explanation.—Goltz regards the canals as organs of sense for ascertaining the equilibrium or 
position of the head in space; Mach as an organ for ascertaining the movements of the head. 
According to Goltz’s statical theory, every position of the head causes the endolymph to exert 
the greatest pressure upon a certain part of the canals, and thus excites in a varying degree the 
nerve-terminations in the ampullae. According to Breuer, when the head is rotated, currents are 
produced in the endolymph of the canals, which must have a fixed relation to the direction and 
extent of the movements of the head, and these currents, therefore, when they are perceived, 
afford a means of determining the movement of the head. The nervous end-organs of the am- 
pullae are arranged for ascertaining this perception. If the semicircular canals are an apparatus — 
in fact, “ sense-organs ”—for the sensation of the equilibrium, and if their function is to determine 
the position or movements of the head, necessarily their destruction or stimulation must alter these 
perceptions, and so give rise to abnormal movements of the head. Vulpian regards the rotation of 
the head as due to strong auditory perceptions (?) in consequence of affections of the canals. 
Bottcher, Tomaszewicz, and Baginsky regard the injury to the cerebellum as the cause of the Sec. 350.] 
GIDDINESS. 
761 
phenomena. The pendulum-like movements, however, are so characteristic that they cannot be 
confounded with disturbances of the equilibrium which result from injury to the cerebellum. 
[Kinetic Theory.—In 1875 Crum Brown pointed out that if a person be rotated passively, 
his eyes being bandaged, he can, up to a certain point, indicate pretty accurately the amount of 
movement, but after a time this cannot be done, and if the rotation, as on a potter’s wheel, be 
stopped, the sense of rotation continues. Crum Brown suggested that currents were produced in 
the endolymph, while the terminal hair-cells lagged behind, and were, in fact, dragged through 
the fluid. He pointed out that the right posterior canal is in line with the left superior, and 
the left posterior with the right superior, a fact which is readily observed by looking from behind 
at a skull, with the semicircular canals exposed (fig. 522). He assumes that the canals are paired 
organs, and that each pair is connected with rotation or movement of the head in a particular 
direction.] 
Giddiness.—This feeling of false impressions as to the relations of the sur- 
roundings and consequent movements of the body occurs especially during 
acquired changes in the normal movements of the eyes, whether due to invol- 
untary to and fro movements of the eyeballs (nystagmus) or to paralysis of 
some eye muscle. 
Active or passive movements of the head or of the body are normally accom- 
panied by simultaneous movements of both eyeballs, which are characteristic for 
every position of the body. The general character of these “ compensatory” 
bilateral movements of the eyes consists in this, that during the various changes 
in the position of the head and body the eyes strive to maintain their primary 
passive position. Section of the aqueduct of Sylvius at the level of the corpora 
quadrigemina, of the floor of the fourth ventricle, of the auditorv nucleus, both 
acustici, as well as destruction of both membranous 
labyrinths, causes disappearance of these move- 
ments; while, conversely, stimulation of these parts 
is followed by bilateral associated movements of 
the eyeballs. 
Compensatory movements of the eyeballs, un- 
der normal circumstances, may be caused reflexly 
from the membranous labyrinth. Nerve chan- 
nels, capable of exciting reflex movements of 
both eyes, proceed from both labyrinths, and, 
indeed, both eyes are affected from both laby- 
rinths. These channels pass through the audi- 
tory nerve to the centre (nuclei of the 3d, 4th, 
6th, and 8th cranial nerves), and from the latter 
efferent fibres pass to the muscles of the eye 
(■Hogyes). 
Effects of Section of the Canals.—Cyon found that stimulation of the horizontal semi- 
circular canal was followed by horizontal nystagmus; of the posterior, by vertical, and of the 
anterior canal, by diagonal nystagmus. Stimulation of one auditory nerve is followed by 
rotating nystagmus, and rotation of the body of the animal on its axis towards the stimulated 
side. 
Drugs.—Chloroform and other poisons enfeeble the compensatory movements of the eyeballs, 
while nicotin and asphyxia suppress them, owing to their action on their nerve-centre. 
It is probable that the disturbances of equilibrium and the feeling of giddi- 
ness which follow the passage of a galvanic current through the head between 
the mastoid processes are also due to an action upon the semicircular canals of 
the labyrinth (§ 300). Deviation of the eyeballs is produced by such a galvanic 
current (Hitzig). The same result is produced when the two electrodes are 
placed in the external auditory meatuses. 
Pathological.—Meniere’s Disease.—The feeling of giddiness, not unfrequently accompa- 
nied by tinnitus, which occurs in Meniere’s disease, must be referred to an affection of the nerves 
of the ampulke or their central organs, or of the semicircular canals themselves. By injecting 
LS 
RS 
LE 
RE 
LP 
Fig. 522. 
RP 
Diagram of the disposition of the 
semicircular canals. RS and 
LS, right and left superior; 
LP and RP, right and left 
posterior; LE and RE, right 
and left external. 762 
GLOSSOPHARYNGEAL NERVE. 
[Sec. 350. 
fluid violently into the ear of the rabbit, giddiness, with nystagmus and rotation of the head 
towards the side operated on, are produced (Baginsky). In cases in man, where the tympanic 
membrane was defective, Luca;, when employing the so-called ear air-douche at o.i atmosphere, 
observed abduction of the eyeball with diplopia, giddiness, darkness in front of the eyes, while 
the respiration was deeper and accelerated. These phenomena must be due to stimulation or 
exhaustion of the vestibular branch of the auditory nerve (Hogyes). In chronic gastric catarrh, 
a tendency to giddiness is an occasional symptom (Trousseau’s gastric giddiness). This may 
perhaps be caused by stimulation of the gastric nerves exciting the vaso-motor nerves of the 
labyrinth, which must affect the pressure of the endolymph. Analogous giddiness is excited 
from the larynx (Charcot) and from the urethra (Erlenmeyer). 
[Vertigo or giddiness is a very common symptom in disease, and may be produced by a 
great many different conditions. It literally means “ a turning.” As Gowers points out, the 
most common symptom is that the patient himself has a sense of movement in one or other 
direction ; or objects may appear to move before him; and more rarely there is actual movement, 
“ commonly in the same direction as the subjective sense of movement.” It is sometimes due 
to a want of harmony between the impressions derived from different sense-organs or “ contra- 
dictoriness of sensory impressions ” [Grainger Stewai't), as is sometimes felt on ascending or 
descending a stair, or by some persons while standing on a high tower, constituting tower or 
cliff giddiness. One of the most remarkable conditions is that called “ agoraphobia ” (Bene- 
dikt, Westphal). The person can walk quite well in a narrow lane or street, but when he 
attempts to cross a wide square, he experiences a feeling closely allied to giddiness. The giddi- 
ness of sea-sickness is proverbial, while some persons get giddy with waltzing or swinging. Be- 
sides occurring in Meniere’s disease, it sometimes occurs in locomotor ataxia, and some cerebral 
and cerebellar affections, including cerebral anaemia. Very distressing giddiness and headache 
are often produced by paralysis of some of the ocular muscles, e. g., the external rectus, i.e., 
ophthalmic vertigo. Defective or perverted ocular impressions, as well as similar auditory- 
impressions, may give rise to vertigo ; in the latter or labyrinthine form the vertigo may be very 
severe. Severe vertigo is often accompanied by vomiting. A hard plug of ear-wax may press 
on the membrana tympani and cause severe giddiness. Vertigo depending on conditions in the 
ear is aural vertigo. The forms of dyspeptic giddiness and the toxic forms due to the abuse of 
alcohol, tobacco, and some other drugs are familiar examples of this condition.] 
[Tinnitus Aurium, or subjective noises in the ear, is a very common symptom in disease of 
the ear, and maybe caused by very varied conditions; the noise may be continuous or dis- 
continuous, be buzzing, singing, or rumbling in character.] 
351. IX. NERVUS GLOSSO-PHARYNGEUS.—Anatomical.—This nerve (figs. 
518, 9, 520) arises from the nucleus of the same name, which consists partly of large cells (motor) 
and partly of small cells (belonging to the gustatory fibres). The nucleus lies in the lower half 
of the fourth ventricle, deep in the medulla oblonga, near the olive (figs. 516, 520), and poste- 
riorly it abuts on that of the vagus. The anterior part of the central nucleus is regarded as the 
root of the portio intermedia of the facial (§ 349). The nerve also receives fibres from the 
vagal centres. The fibres collect into two trunks, which afterward unite and leave the medulla 
oblongata in front of the vagus. In the fossula petrosa it has on it the petrous ganglion, from 
which, occasionally, a special part on the posterior twig is separated within the skull, as the 
ganglion of Ehrenritter. Communicating branches are sent from the petrous ganglion to the 
trigeminus, facial (e and tt) vagus and carotid plexus. From this ganglion also the tympanic 
nerve (A) ascends vertically in the tympanic cavity, where it unites with the tympanic plexus. 
This branch (§ 349, 4) gives sensory fibres to the tympanic cavity and the Eustachian tube; 
while, in the dog, it also carries secretory fibres for the parotid into the small superficial petrosal 
nerve (Heidenhain—\ 145). 
Functions.—1. It is the nerve of taste for the posterior third of the 
tongue, the lateral part of the soft palate, and the glosso-palatine arch (com- 
pare § 422). 
The nerve of taste for the anterior two-thirds of the tongue is referred to under the lingual 
($ 347, III, 4) and chorda tympani nerves (£ 349, 4). The glossal branches are provided with 
ganglia, especially where the nerve divides at the base of the circumvallate papillae (Reinak, 
Kolliker, Stirling). The nerve ends in the circumvallate papillae (fig. 429, U), and the end- 
organs are represented by the taste bulbs (§ 423). 
2. It is the sensory nerve for the posterior third of the tongue, the ante- 
rior surface of the epiglottis, the tonsils, the anterior palatine arch, the soft 
palate, and a part of the pharynx. From this nerve there may be discharged 
reflexly movements of the palate and pharynx, which may pass into those of Sec. 351.] 
VAGUS NERVE. 
763 
vomiting (§ 158). These fibres, like the gustatory fibres, can excite a reflex 
secretion of saliva (§ 145). 
3. It is motor for the stylo-pharyngeus and middle constrictor of the 
pharynx (Volkmann); and, according to other observers, to the (?) glosso- 
palatinus (Hein) and the (? ?) levator veli palatini and azygos uvulae (compare 
Spheno-palatineganglion, § 347, II). It is doubtful whether the glosso-pharyn- 
geal nerve is really a motor nerve at its origin—although Meynert and others 
have described a motor nucleus—or whether the motor fibres reach the nerve 
at the petrous ganglion, through the communicating branch from the facial. 
[4. It is the inhibitory nerve for the act of deglutition (p. 278).] 
5. A twig accompanies the lingual artery; this nerve, perhaps, is vaso-dilator for the lingual 
blood-vessels. 
Pathological.—There are no satisfactory observations on man of uncomplicated affections of 
the glosso-pharyngeal nerve. 
352. X. NERVUS VAGUS.—Anatomical.—T he nucleus from which the vagus arises 
along with the 9th and nth nerve is in (1) the ala cinerea in the lower half of the calamus 
scriptorius (fig. 516, 10) [and it is very probably the representative of the cells of the vesicular 
column of Clarke (§ 366)]. (2) Other fibres come from the “longitudinal bundle” or 
“ respiratory bundle ” lying outside the nucleus, and reaching down into the cervical enlarge- 
ment. (3) A motor nucleus—the nucleus ambiguus—a prolongation of some of the cells of 
the anterior horn of the spinal cord, gives some motor fibres (fig. 520). It leaves the medulla 
oblongata by 10 to 15 threads behind the 9th nerve, between the divisions of the lateral column, 
and has a ganglion (jugular) upon it in the jugular foramen (fig. 517, VIII). Its branches 
contain fibres which subserve different functions [see also p. 771]. 
1. The sensory meningeal branch from the jugular ganglion accompa- 
nies the vaso-motor fibres of the sympathetic on the middle meningeal artery, 
and sends fibres to the occipital and transverse sinus. 
When it is irritated, as in congestion of the head and inflammation of the dura mater, it gives 
rise to vomiting. 
2. The auricular branch (fig. 523, au.) from the jugular ganglion receives 
a communicating branch from the petrous ganglion of the 9th nerve, traverses 
the canaliculus mastoideus, crossing the course of the facial, with which it 
exchanges fibres whose function is unknown. On its course, it gives sensory 
branches to the posterior part of the auditory meatus and the adjoining part of 
the outer ear. A branch runs along with the posterior auricular branch of the 
facial, and confers sensibility on the muscles. 
When this nerve is irritated, either through inflammation or by the presence of foreign bodies 
in the outer ear passage, it may give rise to vomiting. Stimulation of the deep part of the 
external auditory meatus in the region supplied by the auricular branch causes coughing reflexly 
[e. g., from the presence of a pea in the ear]. Similarly, contraction of the blood-vessels of the 
ear may be caused reflexly (Snellen, Lovht). 
The nerve is the remainder of a considerable branch of the vagus which exists in fishes and 
the larvae of frogs, and runs under the skin along the side of the body. 
3. The connecting branches of the vagus are : (1) A branch which di- 
rectly connects the petrous ganglion of the 9th with the jugular ganglion of 
the 10th; its function is unknown. (2) Directly above the plexus gangliifor- 
mis vagi, the vagus is joined by the whole inner half of the spinal accessory. 
This nerve conveys to the vagus the motor fibres for the larynx, and the cervi- 
cal part of the oesophagus (which according to Steiner lie in the inner part of 
the nerve-trunk), as well as the inhibitory fibres for the heart ( Cl. Bernard'). 
(3) The plexus gangliiformis fibres, whose function is unknown, join the trunk 
of the vagus from the hypoglossal, superior cervical ganglion of the sympathetic, 
and the cervical plexus. 
4. Pharyngeal Plexus.—The vagus sends one or two branches (fig. 
523, 2) from the upper part of the plexus gangliiformis to the pharyngeal plexus, I. Scheme of the distribution of the vagus and accessorius.—io, Exit of left vagus from the skull; 
Fig- 523- Sec. 352.] 
765 
VAGUS NERVE. 
where at the level of the middle constrictor of the pharynx, it is joined by the 
pharyngeal branches of the 9th nerve and those of the upper cervical sympa- 
thetic ganglion, near the ascending pharyngeal artery, to form the pharyngeal 
plexus. The vagal fibres in this plexus supply the three constrictors of the 
pharynx with motor fibres, while the tensor palati {Otic ganglion, § 347, III) 
and levator of the soft palate (compare Spheno-palatine ganglion, § 347, II) also 
receive motor (? sensory) fibres. Sensory fibres of the vagus from the pharyn- 
geal plexus supply the pharynx from the part beneath the soft palate down- 
wards. These fibres excite the pharyngeal constrictors reflexly, during the act 
of swallowing (§ 156). If stimulated very strongly, they may cause vomiting. 
(The sympathetic fibres of the oesophageal plexus give vaso-motor nerves to the 
oesophageal vessels; for the oesophageal branches of the 9th nerve see above.) 
5. The vagus supplies two branches to the larynx, the superior and inferior 
laryngeal. 
(a) The superior laryngeal receives vaso-motor fibres from the superior 
cervical ganglion of the sympathetic (fig. 523, 3). It divides into two branches, 
external and internal: (1) The external branch receives vaso-motor fibres 
from the same source (they accompany the superior thyroid artery), and sup- 
ply the crico-thyroid muscle with motor fibres, and sensory fibres to the 
lower lateral portion of the laryngeal mucous membrane. (2) The internal 
branch gives off sensory branches only to the glosso-epiglottidean fold, and the 
adjoining lateral region of the root of the tongue, the aryepiglottidean fold, 
and to the whole anterior part of the larynx, except the part supplied by the 
external branch ('Longet). Stimulation of any of these sensory fibres causes 
coughing reflexly. Coughing is produced by stimulation of the boundaries 
of the glottis respiratoria, but not of the vocal cords, and by stimulation of the 
sensory branches of the vagus to the tracheal mucous membrane, especially at 
the bifurcation, and also from the bronchial mucous membrane (Kohts). 
Coughing is also caused by stimulation of the auricular branch of the vagus, 
especially in the deep part of the external auditory meatus, of the pulmonary 
tissue, especially when altered pathologically ; in pathological conditions (in- 
flammation) of the pleura (? certain changes in the stomach [stomach cough]), 
of the liver and spleen (fig. 165). The coughing centre is said to lie on 
each side of the raphe, in the neighborhood of the ala cinerea {Kohts). Cases 
of violent coughing may, owing to stimulation of the pharynx, be accom- 
panied by vomiting as an associated movement (§ 120). 
In many individuals, coughing can be excited by stimulation of distant sensory nerves 
(| 120, 1), e. g., from the outer ear (auricular nerve), nasal mucous membrane, liver, spleen, 
stomach, intestine, uterus, mammse, ovaries, and even from certain cutaneous areas (.Ebstein). 
It is uncertain if these conditions act directly upon the coughing centre, or first of all affect the 
iOj, right vagus; 9, glosso-pharyngeal; 7, facial; 1, deep post-auricular from the facial; 
2, pharyngeal branches of vagus; 6, pharyngeal branch of the glosso-pharyngeal; 3, 
superior laryngeal, with its anastomoses, yj with the sympathetic and its division, 4, into 
its internal, v, and external branches, e; 5, inferior or recurrent laryngeal; aw., auricular 
branch of vagus. Cardiac nerves : g, cardiac branches from the vagus and superior laryn- 
geal ; i, h, the three cardiac branches from the upper, g, middle, x, and lower, y, cervical 
ganglion of the sympathetic; k, ring of Vieussens; /, cardiac branch from the recurrent 
laryngeal; Z, lung with the anterior and posterior pulmonary plexuses; r, oesophageal 
plexus; 00, gastric branches, and near them the hepatic branches, n; m, coeliac plexus; 
k, splanchnic entering former; n, accessory nerve sending its inner branch into the 
gangliform plexus of the vagus—its outer branch, ac, supplies the sterno-mastoid, Si and 
acx, and the trapezius, Cc; O, external auditory meatus; Oh, hyoid bone; K, thyroid 
cartilage; T, trachea; H, heart; P, pulmonary artery; A A, aorta; c, right carotid; 
cv left carotid; s and sv right and left subclavian artery; Z Z, diaphragm; N, kidney; Nn, 
suprarenal capsule; M, stomach; m, spleen; Z Z, lung and liver. II. Scheme of the 
course of the depressor and accelerans in the cat. 766 
DEPRESSOR NERVE. 
[Sec. 352. 
vascularization and secretion of the respiratory organs, which in their turn affect the coughing 
centre. 
The cough (dog, cat) caused by stimulation of the trachea and bronchi occurs at once, and 
lasts as long as the stimulus lasts; in stimulation of the larynx, the first effect is inhibition of 
the respiration accompanied by movements of deglutition, while the cough occurs after the 
cessation of the stimulation (Kandarazky). 
The superior laryngeal contains afferent fibres which, when stimulated, 
cause arrest of the respiration and closure of the rima glottidis (.Rosenthal 
—see Respiratory centre, § 368), and fibres which discharge movements of 
deglutition, (p. 277). Lastly, fibres which are efferent and serve to excite 
the vaso-motor centre, and are in fact “ pressor fibres ”—(see Vaso-motor 
centre, § 371, II). 
('b) The inferior laryngeal or recurrent nerve bends on the left side 
around the arch of the aorta, and on the right around the subclavian artery, 
and ascends in the groove between the trachea and oesophagus, giving motor 
fibres to these organs, and the lower constrictors of the pharynx, and passes to 
the larynx, to supply motor fibres to all its muscles, except the crico-thyroid. 
It also has an inhibitory action upon the respiratory centre (see § 368). 
A connecting branch runs from the superior laryngeal to the inferior (the anastomosis of 
Galen), which occasionally gives off sensory branches to the upper half of the trachea (sometimes 
to the larynx ?); perhaps also to the oesophagus (Longet), and sensory fibres (?) for the muscles 
of the larynx supplied by the recurrent laryngeal. According to Francois Franck, sensory fibres 
pass by this anastomosis from the recurrent into the superior laryngeal. According to Waller and 
Burckhard, the motor fibres of both laryngeal nerves are all derived from the accessorius; 
while Chauveau maintains that the crico-thyroid is an exception. 
Stimulation of the superior laryngeal is painful, and causes contraction 
of the crico-thyroid muscle (while the other laryngeal muscles contract reflexly). 
Section of both nerves, owing to paralysis of the crico-thyroids, causes slight 
slowing of the respirations (Sklarek). In dogs, the voice becomes deeper and 
hoarser, owing to diminished tension of the vocal cords (Longet). The larynx 
becomes insensible, so that saliva and particles of food pass into the trachea and 
lungs, without causing reflex contraction of the glottis or coughing. This ex- 
cites “traumatic pneumonia,’’which results in death. Unilateral section is 
followed by unilateral atrophy of the laryngeal muscles (p. 655). 
Stimulation of the recurrent nerves causes spasm of the glottis. Sec- 
tion of these nerves paralyzes the laryngeal muscles supplied by them, the voice 
becomes husky and hoarse (in the pig—Galen, Riolan, 16x8) in man, dog, 
and cat; while rabbits retain their shrill cry. The glottis is small, with every 
inspiration the vocal cords approximate considerably at their anterior parts, 
while during expiration they are relaxed and are separated from each other. 
Hence, the inspiration, especially in young individuals whose glottis respira- 
toria is narrow, is difficult and noisy (Legallois); while the expiration takes 
place easily. After a few days, the animal (carnivore) becomes more quiet, it 
respires with less effort, and the passive vibratory movements of the vocal cords 
become less. Even after a considerable interval, if the animal be excited, it is 
attacked with severe dyspnoea, which disappears only when the animal has be- 
come quiet again. Owing to paralysis of the laryngeal muscles, foreign bodies 
are apt to enter the trachea, while the paralysis renders difficult the first part of 
the process of swallowing in the oesophageal region. Broncho-pneumonia may 
be produced. [Effect of ether, see p. 681.] 
6. The depressor nerve, which in the rabbit arises by one branch from 
the superior laryngeal, and usually also by a second root from the trunk of the 
vagus itself [runs down the neck in close relation with the vagus, sympathetic, 
and carotid artery, enters the thorax], and joins the cardiac plexus (fig. 524, sc). 
It is an afferent nerve, and when its central end is stimulated [provided both 
vagi be divided], it diminishes the energy of the vaso-motor centre, and thus Sec. 352.] 
CARDIAC AND PULMONARY BRANCHES. 
767 
causes a fall of the blood-pressure (hence the name given to it by Cyon and 
Ludwig, § 371, II). At the same time [if the vagus on the opposite side be 
intact], its stimulation affects the cardio-inhibitory centre, and thus reflexly 
diminishes the number of heart-beats. [Its stimulation also gives rise to pain, 
so that it is the sensory nerve of the heart. If in a rabbit the vagi be divided 
in the middle of the neck, and the central end of the depressor nerve, which 
is the smallest of the three nerves near the carotid, be stimulated, after a short 
time there is no alteration of the heart-beats, but there is steady fall of the 
blood-pressure (fig. 119), which is due to a reflex inhibition of the vaso-motor 
centre, resulting in a dilatation of the blood-vessels of the abdomen. Of 
course, if the vagi be intact, there is a reflex inhibitory effect on the heart. It 
is doubtful if the depressor comes into action when the heart is over-distended. 
If it did, of course the blood-pressure would be reduced by the reflex dilatation 
of the abdominal blood-vessels.] 
The depressor nerve is present in the cat (§ 370), hedgehog (Aubert, Rover), rat and mouse; 
in the horse and in man, fibres analogous to the depressor re-enter the trunk of the vagus 
(.Bernhardt, Kreidmann). Depressor fibres are also found in the rabbit in the trunk of the vagus 
(Dreschfeldt, Stelling). 
7. Tne cardiac branches (fig. /), as well as the cardiac plexus, 
have been described in § 57. These nerves contain the 
inhibitory fibres for the heart (fig. 524, ic—cardio- 
inhibitory—Edward Weber, November, 1845 > Budge, 
independently in May, 1846), also sensory fibres for 
the heart [in the frog (Budge), and partly in mammals 
(Goltz)]. Lastly, in some animals the heart receives some 
of the accelerating fibres through the trunk of the vagus. 
Feeble stimulation of the vagus occasionally causes accel- 
eration of the beats of the heart (Schiff). [This occurs 
when the vagus contains accelerator fibres.] In an animal 
poisoned with nicotin, or atropin, which paralyzes the in- 
hibitory fibres of the vagus, stimulation of the vagus is 
followed by acceleration of the heart-beats (Schiff\ 
Schmiedeberg) [owing to the unopposed action of any 
accelerated fibres that may be present in the nerve, e.g., 
of the frog]. 
8. The pulmonary branches of the vagus join the 
anterior and posterior pulmonary plexuses. The anterior 
pulmonary plexus gives sensory and motor fibres to 
the trachea, and runs on the anterior surface of the branches 
of the bronchi into the lungs (Z). The posterior plexus 
is formed by three to five large branches from the vagus, near 
the bifurcation of the trachea, together with branches 
from the lowest cervical ganglion of the sympathetic and 
fibres from the cardiac plexus. [It also receives fibres from 
the second, third, and fourth thoracic ganglia of the sym- 
pathetic ; and through the latter channels the vaso-con- 
strictor fibres reach the blood-vessels of the lung (§ 371).] 
The plexuses of opposite sides exchange fibres, and branches 
are given off which accompany the bronchi in the lungs. 
Ganglia occur in the course of the pulmonary branches 
in the frog (Arnold, W. Stirling) [newt—W. Stirling; and 
in mammals (.Remak, Egorow, W. Stirling)'], in the larynx 
[Cock, W. Stirling], in the trachea and bronchi [IF. Stir- 
ling, Kandarazki]. Branches proceed from the pulmonary 
plexus to the pericardium and the superior vena cava (Luschka, Zuckerkandl). 
Scheme of the cardiac 
nerves in the rabbit. 
P, pons; M, medulla 
oblongata; Vag, 
vagus; sl, superior, 
il, inferior laryngeal; 
sc, superior cardiac or 
depressor; ic, inferior 
cardiac or cardio-in- 
hibitory; H, heart. 
Fig. 524. 768 
EFFECTS OF SECTION OF VAGI. 
[Sec. 352. 
The functions of the pulmonary branches of the vagus are—(i) they 
supply motor branches to the smooth muscles of the whole bronchial system 
(§ 106) ; (2) they supply a small part of the vaso-motor nerves of the pul- 
monary vessels (?) (Schiff), but by far the largest number of these nerves (? all) 
is supplied from the connection with the sympathetic (in animals from the 
upper dorsal ganglion)—(Rose and Bradford, % 371, A. Fick, Badoud, Lich- 
theim) ; (3) they supply sensory (cough exciting) fibres to the whole bronchial 
system and to the lungs ; (4) they give afferent fibres, which, when stimu- 
lated, diminish the activity of the vaso-motor centre, and thus cause a fall of the 
blood-pressure during forced expiration; (5) similar fibres which act upon the 
inhibitory centre of the heart, and so influence it as to accelerate the pulse- 
beats (§ 369, II). Simultaneous stimulation of 4 and 5 alters the pulse rhythm 
(.Sommerbrodt); (6) they also contain afferent fibres from the pulmonary 
parenchyma to the medulla oblongata, which stimulate the respiratory centre. 
[These fibres are continually in action], and consequently section of both vagi 
is followed by diminution of the number of respirations; the respirations be- 
come at the same time deeper, while the same volume of air is changed 
(Valentin). Stimulation of the central end of the vagus again accelerates the 
respirations (Traube, J. Rosenthal). Thus, labored and difficult respiration 
is explained by the fact that the influences conveyed by these fibres which excite 
the respiratory centre reflexly are cut off; so it is evident that centripetal or 
afferent impulses proceeding upwards in the vagus are intimately concerned in 
maintaining normal reflex respiration ; after these nerves are divided, conditions 
exciting the respiratory movements must originate directly, especially in the 
medulla oblongata itself (§ 368). 
Pneumonia after Section of both Vagi.—The inflammation which follows section of both 
vagi has attracted the attention of many observers since the time of Valsalva, Morgagni (1740), 
and Legallois (1812). In attempting to explain this phenomenon, we must bear in mind the 
following considerations : (a) Section of both vagi is followed by loss of motor power in the 
muscles of the larynx, as well as the sensibility of the larynx, trachea, bronchi, and the lungs, 
provided the section be made above the origin of the superior laryngeal nerves. Hence, the 
glottis is not closed during swallowing, nor is it closed reflexly when foreign bodies (saliva, 
particles of food, irrespirable gases) enter the respiratory passages. Even the reflex act of cough- 
ing, which, under ordinary circumstances, would get rid of the offending bodies, is abolished. 
Thus, foreign bodies may readily enter the lungs, and this is favored by the fact that, owing to 
the simultaneous paralysis of the oesophagus, the food remains in the latter for a time, and 
may therefore easily enter the larynx. That this constitutes one important factor was proved 
by Traube, who found that the pneumonia was prevented when he caused the animals to respire 
by means of a tube inserted into the trachea through an aperture in the neck. If, on the con- 
trary, only the motor recurrent nerves were divided and the oesophagus ligatured, so that in 
the process of attempting to swallow, food must necessarily enter the respiratory passages, 
“ traumatic pneumonia ” was the invariable result (Traube, O. Frey), (b) A second factor 
depends on the circumstance that, owing to the labored and difficult respiration, the lungs 
beco?ne surcharged with blood, because during the long time that the thorax is distended, the 
pressure of the air within the lungs is abnormally low. This condition of congestion, or abnormal 
filling of the pulmonary vessels with blood, is followed by serous exudation (pulmonary oedema) 
and even by exudation of blood and the formation of pus in the air-vesicles (Frey). This same 
circumstance favors the entrance of fluids through the glottis (§ 352, b). The introduction of 
a trachea cannula will prevent the entrance of fluids and the occurrence of inflammation. It 
is probable that a partial paralysis of the pulmonary vaso-motor nerves may be concerned in the 
inflammation, as this conduces to an engorgement of the pulmonary capillaries, (c) Lastly, 
it is of consequence to determine whether trophic fibres are present in the vagus, which may 
influence the normal condition of the pulmonary tissues. According to Michaelson, the 
pneumonia which takes place immediately after section of the vagi occurs especially in the lower 
and middle lobes; the pneumonia which follows section of the recurrents occurs more slowly, 
and causes catarrhal inflammation, especially in the upper lobes. Rabbits, as a rule, die within 
twenty-four hours, with all the symptoms of pneumonia; when the above-mentioned precautions 
are taken, they may live for several days. Dogs may live for a long time. If the 9th, 10th, and 
12th nerves be torn out on one side in a rabbit, death takes place from pneumonia (Griinhagen). 
In birds, bilateral section of the vagi is not followed by pneumonia (Blainville, Billroth), Sec. 352.] 
BRANCHES OF VAGUS. 
769 
because the upper larynx remains capable of closing firmly—death takes place in eight to ten days 
with the symptoms of inanition (Einbrodt, Zander, v. Anrep), while the heart undergoes fatty 
degeneration (Eichhorst), and so do the liver, stomach, and muscles (v. Anrep). According 
to Wassilieff, the heart shows cloudy swelling and slight wax-like degeneration. Frogs, which 
at every respiration open the glottis, and close it during the pause, die of asphyxia. Section of 
the pulmonary branches has no injurious effect {Bidder). [Unilateral section of the vagus in 
rabbits is followed within forty-eight hours by the appearance of yellowish-white spots on the 
myocardium, especially near the interventricular septum, on the papillary muscles, and along the 
furrows for the coronary arteries. The muscular fibres exhibit retrogressive changes, whereby 
their striae disappear ; they become swollen up and filled with albuminous granules. After eight 
to ten days, the interstitial tissue of these foci becomes infiltrated with small round granular 
cells, especially near the blood-vessels. At a later stage the interstitial connective-tissue increases 
in amount, and the muscle atrophies. No effect is produced by section of the depressor or 
sympathetic, and Fantino concludes that some of the fibres of the vagus exert a trophic action 
on the myocardium.] 
9. The oesophageal plexus (fig. 524, r) is formed principally by branches 
from the vagus above the inferior laryngeal, from the pulmonary plexus, and 
below from the trunk itself. This plexus supplies the oesophagus with motor 
power (§ 156), the sensibility which is present only in the upper part, and it 
also supplies fibres capable of exciting reflex actions. 
10. The gastric plexus (00) consists of (a) the anterior (left) termination 
of the vagus, which supplies fibres to the oesophagus and courses along the small 
curvature, and sends a few fibres through the portal fissure into the liver; (b) 
the posterior (right) vagus, after giving off a few fibres to the oesophagus, takes 
part in the formation of the gastric plexus to which (c) sympathetic fibres are 
added at the pylorus. Section of the vagi is followed by hypersemia of the 
gastric mucous membrane (Panum, Pincus), but it does not interfere with 
digestion (.Bidder and Schmidt), even when it is performed at the cardia 
(.Kritzler, Schiff). 
After bilateral section of the vagi below the diaphragm, the animal loses flesh, and after three 
months or so there are inflammatory changes in the gastric mucous membrane and pericellular 
proliferation in the liver and kidneys, and ultimately death takes place. 
11. About two-thirds of the right vagus on the stomach joins the cceliac 
plexus ini) and from it branches accompany the arteries to the liver, spleen, 
pancreas, duodenum, kidneys, and suprarenal capsules. The vagus supplies motor 
fibres to the stomach, which belong to the root of the vagus itself and not to 
the accessorius (Stilling, Bischoff). The gastric branches also contain afferent 
fibres, which, when stimulated, cause reflexly a secretion of saliva (§ 145). It 
is undetermined whether they also cause vomiting. (For the effect of the 
vagus upon the movements of the intestine see § 161). According to 
some observers, stimulation of the vagus is followed by movement of the large 
as well as of the small intestine (Stilling, Kupffer, C. Ludwig, Remak). Stimu- 
lation of the peripheral end of the vagus causes contraction of the smooth muscular 
fibres in the capsulse and trabeculae of the spleen (in the rabbit and dog, § 103). 
Stimulation of the vagus at the cardia causes increase in the secretion of urine 
with dilatation of the renal vessels, while the blood of the renal vein becomes 
more arterial (CY. Bernard). According to Rossbach and Quellhorst, a few 
vaso-motor fibres are supplied by the vagus to the abdominal organs, whilst 
the greatest number comes from the splanchnic. 
12. Reflex Effects discharged from the Vagus.—The vagus and its 
branches contain fibres, some of which have been referred to already, which act 
reflexly (afferent) upon certain nervous mechanisms. 
(a) On the vaso-motor centre there act (a) pressor fibres (especially in 
both laryngeal nerves) whose stimulation is followed by a reflex contraction of 
the arterial blood-channels, and thus cause a rise of the blood-pressure ; (/3) 
depressor fibres (in the depressor or the vagus itself), which have exactly an [Sec. 352. 
770 
CARDIO-INHIBITORY CENTRE 
opposite effect. (This subject is specially referred to under the head of the 
Vaso-motor nerve-centre, § 371.) 
(h) On the respiratory centre there act (a) fibres (pulmonary branches) 
whose stimulation is followed by acceleration of the respiration ; and (ft) 
inhibitory fibres (in both laryngeals), whose stimulation is followed by slowing 
or arrest of the respiration. (See Respiratory centre, § 368.) 
(<r) On the cardio-inhibitory system.— [When the central end of one 
vagus is stimulated, provided the other vagus is intact, the heart may be arrested 
reflexly in the diastolic phase.] Mayer and Pribram observed that sudden 
distention of the stomach caused slowing and even arrest of the heart, while, 
at the same time, there was contraction of the arteries of the medulla oblongata 
and increase of the blood-pressure. 
(d) On the vomiting centre.—This centre may be affected by stimulation of the central end 
of the vagus, and, as already mentioned, by stimulation of many afferent fibres in the vagus 
($ 158). 
(e) On the pancreatic secretion.—Stimulation of the central end of the vagus is followed 
by arrest of this secretion (§ 171). 
(_/■) According to Cl. Bernard, there are fibres present in the pulmonary nerves, which, when 
they are stimulated, increase reflexly the formation of sugar in the liver, perhaps through 
the hepatic branches of the vagus. 
Unequal Excitability of the Branches of the Vagus.—The various branches of the vagus 
are not all endowed with the same degree of excitability. If the peripheral end of the vagus 
be stimulated first of all with a weak stimulus, the laryngeal muscles are first affected, and after- 
wards the heart is slowed (Rutherford). If the central end be stimulated with feeble stimuli, 
the “ excito-respiratory ” fibres are exhausted before the “ inhibito-respiratory ” (Burkart). 
According to Steiner, the various fibres are so arranged in the vagus that the afferent fibres lie 
in the outer, and the efferent in the inner, half of the tiunk, in the cervical region. 
Pathological.—Stimulation or paralysis in the area of the vagus must necessarily present a 
very different picture according as the affection is referred to the whole trunk or only to some 
of its branches, or whether the affection is unilateral or bilateral. Paralysis of the pharynx 
and oesophagus, which is usually of central or intracranial origin, interferes with or abolishes 
deglutition, so that when the oesophagus becomes filled with food there is difficulty of breathing, 
and the food may even pass into the nasal cavities. A peculiar sonorous gurgling is occasionally 
heard in the relaxed canal (deglutatio sonora). In incomplete paralysis, the act of deglu- 
tition is delayed and rendered more difficult, while large masses are swallowed more easily than 
small ones. Increased contraction and spasmodic stricture of the oesophagus are referred to 
under the phenomena of general nervous excitability (§ 186). 
Spasm of the laryngeal muscles causes spasmodic closure of the glottis (Spasmus glot- 
tidis). This condition is most apt to occur in children, and takes place in paroxysms, with 
symptoms of dyspnoea and crowing inspiration; if the case be very severe, there may be mus- 
cular contractions (of the eye, jaw, digits, etc ). The symptoms are very probably due to the 
reflex spasms which may be discharged from the sensory nerves of several areas (teeth, intestine, 
skin). The impulse is conducted along the sensory nerves proceeding from these areas to the 
medulla oblongata, where it causes the discharge of the reflex mechanism which produces the 
above-mentioned results. There may be spasm of the dilators of the glottis and other laryngeal 
muscles (Frantzel). 
Stimulation of the sensory nerves of the larynx, as is well known, produces coughing. 
If the stimulation be very intense, as in whooping cough, the fibres lying in the laryngeal nerves, 
which inhibit the respiratory centre, may also be stimulated; the number of respirations is 
diminished, and ultimately the respiration ceases, the diaphragm being relaxed; while, with .the 
most intense stimulation, there may be spasmodic expiratory arrest of the respiration with closure 
of the glottis, which may last for fifteen seconds. Paralysis of the laryngeal nerves, which 
causes disturbances of speech, has been referred to in $ 313. In bilateral paralysis of the recur- 
rent nerves, in consequence of tension upon them due to dilatation of the aorta and the sub- 
clavian artery, a considerable amount of air is breathed out, owing to the futile efforts which the 
patient makes in trying to speak; expectoration is more difficult, while violent coughing is 
impossible (v. Ziemssen). Attacks of dyspnoea occur just as in animals, if the person makes 
violent efforts. Some observers (Salter, Bergson) have referred the paroxysms of nervous 
asthma, which last for a quarter of an hour or more, and constitute asthma bronchiale, to 
stimulation of the pulmonary plexus, causing spasmodic contraction of the bronchial muscle ($ 
106). Physical investigation during the paroxysms reveals nothing but the existence of some 
rhonchi (§ 117). If this condition is really spasmodic in its nature (? of the vessels), it must be Sec. 352.] 
SPINAL ACCESSORY NERVE. 
771 
usually of a reflex character; the afferent nerves may be those of the lung, skin, or genitals (in 
hysteria). Perhaps, however, it is due to a temporary paralysis of the pulmonary nerves 
(afferent), which excite the respiratory centre (excito-respiratory). 
Stimulation of the cardiac branches of the vagus may cause attacks of temporary suspension 
of the cardiac contractions, which are accompanied by a feeling of great depression and of 
impending dissolution, with occasionally pain in the region of the heart. Attacks of this sort 
may be produced refiexly, e.g., by stimulation or irritation of the abdominal organs (as in the 
experiment of Goltz of tapping the intestines, \ 369, II). Hennoch and Silbermann observed 
slowing of the action of the heart in children suffering from gastric irritation. Similarly, the 
respiration may be affected refiexly through the vagus, a condition described by Hennoch as 
asthma dyspepticum. In cases of intermittent paralysis of the cardiac branches of the vagus, 
we rarely find acceleration of the pulse above 160 (Riegel), 200 (Tuczek, L. Longer)’, even 
240 pulse-beats per minute have been recorded (Kuppert), and in such cases the beats vary 
much in rhythm and force, and they are very irregular. These cases require to be more minutely 
analyzed, as it is not clear how much is due to paralysis of the vagus and how much to the 
action of the accelerating mechanism of the heart. Little is known of affections of the intra- 
abdominal fibres of the vagus. It seems that the sensory branches of the stomach do not come 
from the vagus. If the trunk of the vagus or its centre be paralyzed, there are labored, deep, 
slow respirations, such as follow the section of both vagi (Gutlmann). 
353. XI. NERVUS ACCESSORIUS WILLISII.—Anatomical.—This nerve arises 
by two completely separate roots; one from the accessorius nucleus of the medulla oblongata 
(fig. 516, 11), which is connected with the vagus nucleus; while the other root arises between 
the anterior and posterior nerve-roots from the spinal cord, usually between the 5th and 6th 
cervical vertebrae (fig. 520). In the spinal cord its fibres can be traced to an elongated nucleus 
lying on the outer side of the anterior cornu, as far downwards as the 5th cervical vertebra. 
Near the jugular foramen both portions come together, but do not exchange fibres (Holl); both 
roots afterwards separate from each other to form two distinct branches, the anterior [inner), 
which arises from the medulla oblongata, passing en masse into the plexus gangliiformis vagi. 
This branch supplies the vagus with most of its motor fibres (compare \ 352, 3), and also its 
cardio-inhibitory fibres (fig. 523). [The upper cervical metameres or segments give origin 
not only to the anterior and posterior roots of the corresponding nerve-roots, but between these 
roots arise the roots of the spinal accessory nerve. This nerve contains large medullated nerve- 
fibres, and fine medullated fibres such as characterize the visceral branches of the thoracic and 
sacral regions ($ 356). The nerve passes by the jugular ganglion of the vagus, then divides 
into the external and internal branch. All the large fibres pass into the external branch, 
which, along with branches from the cervical plexus, supply the sterno-mastoid and trapezius. 
The internal branch, composed of small fibres, passes into the ganglion of the trunk of the 
vagus. Gaskell therefore regards the internal branch “ as formed by the rami viscerales of the 
upper cervical and vagus nerves.” It has been suggested that these fine medullated nerve-fibres 
arise from the cells of the posterior vesicular column of Clarke. The motor fibres to the trape- 
zius and sterno-mastoid arise from the cells of the lateral horn of gray matter.] 
If the accessorius be pulled out by the root in animals, the cardio-inhibitory 
fibres undergo degeneration. If the trunk of the vagus be stimulated in the 
neck four to five days after the operation, the action of the heart is no longer 
arrested thereby [owing to the degeneration of the cardio-inhibitory fibres] 
(Waller, Schiff, Daszkiewicz, Heidenhain); according to Heidenhain, the 
heart-beats are accelerated immediately after pulling out the nerve. 
The external branch arises from the spinal roots. This nerve communi- 
cates with the sensory branches of the posterior root of the 1st, more rarely 
of the 2d cervical nerve, and these fibres supply sensibility to the muscles; it 
then turns backwards above the transverse process of the atlas, and terminates 
as a motor nerve in the sterno-mastoid and trapezius (fig. 523). The latter 
muscle usually receives motor fibres also from the cervical plexus (fig. 518). 
The external branch communicates with several cervical nerves. These fibres either participate 
in the innervation of the above-named muscles, or the accessorius returns part of the sensory 
fibres supplied by the posterior roots of the two upper cervical nerves. 
•Pathological.—Stimulation of the otiter branch causes tonic or clonic spasm of the above- 
named muscles, usually on one side. If the branch to the sterno-mastoid be affected alone, the 
head is moved with each clonic spasm. If the affection be bilateral, the spasm usually takes 
place on opposite sides alternately, while it is rare to have it on both sides simultaneously. In 
spasm of the trapezius the head is drawn backwards and to the side. Tonic contraction of the 
flexors of the head causes the characteristic position of the head known as caput obstipum (spas- 772 
HYPOGLOSSAL NERVE. 
[Sec. 353. 
ticum) or wryneck. In paralysis of one of these muscles, the head is drawn towards the sound 
side (torticollis paralyticus). Paralysis of the trapezius is usually only partial. 
Paralysis of the whole trunk of the spinal accessory (usually caused by central conditions), 
besides causing paralysis of the sterno-mastoid and trapezius, also paralyzes the motor branches 
of the vagus already referred to (‘Erb, Frankel). 
354. XII. NERVUS HYPOGLOSSUS. — Anatomical. — It arises from two large- 
celled nuclei within the lowest part of the calamus scriptorius, and one adjoining small-celled 
nucleus (Roller), while additional fibres come from the brain (§ 378), and also perhaps from the 
olive (fig. 5t6, 12, 520). It springs by 10 to 15 twigs in a line with the anterior roots of the 
spinal nerve (fig. 516, IX). In its development part of the hypoglossal behaves as a spinal 
nerve (Froriep). 
Function.—It is motor to all the muscles of the tongue, including the 
genio-hyoid and thyro-hyoid. 
Connections.—The trunk of the hypoglossal is connected wfith—(1) the superior cervical 
ganglion of the sympathetic, which supplies it with vaso-motor fibres for the blood-vessels of the 
tongue. After section of the hypoglossal and lingual nerves, the corresponding half of the tongue 
becomes red and congested (Schiff). (2) There is also a branch from the plexus gangliiformis 
vagi, its small lingual branch to the commencement of the hypoglossal arch. These fibres supply 
the hypoglossal with sensory fibres for the muscles of the tongue, for even after section of the 
lingual the tongue still possesses dull sensibility. It is uncertain whether fibres with a similar 
function are partly derived from the cervical nerves or from the anastomosis which takes place 
with the lingual. (3) It is united with the upper cervical nerves by means of the loops known 
as the ansa hypoglossi. These connecting fibres run in the descendens noni to the sterno-hyoid, 
omo-hyoid,and sterno-thyroid. Cervical fibres do not, as a rule, enter the tongue; stimulation of 
the root of the hypoglossal acts upon the above-named muscles only very rarely and to a very 
slight extent ( Volhmann). [Beevor and Horsley find that the motor fibres which pass via the 
hypoglossal to innervate the muscles that depress the hyoid bone, are derived from the first and 
second cervical nerves.] (Compare \ 297, 3, and \ 336, III). 
Bilateral section of the nerve causes complete motor paralysis of the 
tongue. Dogs can no longer lap, they bite the flaccid tongue. Frogs, which 
seize their prey with the tongue, must starve; when the tongue hangs from the 
mouth, it must prevent the closure of the mouth, so that these animals must die 
from asphyxia, as air is pumped into the lungs only when the mouth is closed. 
Pathological.—Paralysis of the hypoglossal (glossoplegia), which is usually central in its 
origin, causes disturbance of speech ($ 319). [In unilateral palsy, the tongue lies in the mouth 
in its normal position, but the base is more prominent on the paralyzed side. When the tongue 
is protruded, it passes to the sound side by the genio-hyoglossus (£ 155).] Paralysis of the 
tongue also interferes with mastication, the formation of the bolus in the mouth, and deglutition 
in the mouth. Owing to the imperfect movements of the tongue, taste is imperfect, and the 
singing of high notes and the falsetto voice, which require certain positions of the tongue, appear 
to be impossible (Bennati). 
Spasm of the tongue, which causes aphthongia (§ 318), is usually reflex in its origin, and is 
extremely rare. Idiopathic cases of spasm of the tongue have been described; the seat of the 
irritation lay either in the cortex cerebri or in the oblongata (Berger, E. Remak). For Pseudo- 
motor Action, \ 349. 
355. THE SPINAL NERVES. —Anatomical. —The thirty-one 
pairs of spinal nerves arise by means of a [superior, gangliated] posterior 
root (consisting of a few large rounded bundles), from the sulcus between the 
posterior and lateral columns of the spinal cord, and by means of an [inferior, 
non-gangliated] anterior root (consisting of numerous fine flat strands), 
from the furrow between the anterior and lateral columns (fig. 525). The 
posterior roots, with the exception of the 1st cervical nerve, are the larger. 
Occasionally the roots on opposite sides are not symmetrical; one or other 
root, or even a whole nerve, may be absent from the dorsal region (.Adam- 
kiewicz). On the posterior root is the spindle-shaped spinal ganglion 
(§ 321, II, 3), which is occasionally double on the lumbar and sacral nerves. 
Beyond the ganglion, the two roots unite to form within the spinal canal the 
mixed trunk of a spinal nerve. The branches of the nerve-trunk invariably 
contain fibres coming from both roots. The number of fibres in the nerve- 
trunk is exactly the same as in the two roots; hence, we must conclude that Sec. 355.] 
LIMB PLEXUSES. 
773 
the nerve-cells in the spinal ganglion are intercalated in the course of the 
afferent fibres ( Gaule and Birge). 
Varieties.—The spinal ganglion is sometimes double, and, according to Hyrtl, isolated 
ganglionic cells frequently occur in the posterior root, between the ganglion and the cord [and 
they also occur in the anterior roots]. Occasionally the roots are somewhat unsymmetrical on 
opposite sides; in the dorsal part one or other or both roots of a spinal nerve are sometimes absent. 
[Morphology of the Spinal Nerves and Limb-Plexuses.—Atypical segmental spinal 
nerve (fig. 525) divides, after its formation, into three parts, a dorsal branch, or superior primary 
division, distributed to the back; a somatic branch, or inferior primary division, supplying the 
body-wall or limbs; and a splanchnic or visceral branch, or ramus communicans, connected 
with the sympathetic gangliated cord, and distributed to the large vessels and viscera. The 
somatic branch is the largest, and is generally, by human anatomists, spoken of as the “ anterior 
primary division.” In the thoracic and upper lumbar regions the distribution of this nerve is 
simple. It divides into an external (or lateral) branch, and an internal (or anterior) branch, 
which supply respectively the lateral and anterior portions of the thoracic and abdominal walls ] 
[In the region of the neck, and in relation to the limbs, the arrangement of the somatic branches 
becomes complicated by the formation of the plexuses. In the embryo, however, the distribu- 
tion of the nerves is simpler, and a comparison can be made both with the adult arrangement, and 
with the typical nerve as seen in the thoracic region. In the embryo, the neck as such does not 
exist, and the upper limb sprouts out directly beyond the segmented visceral arches. In this state 
the somatic branch is distributed as in the thoracic region; the nerve divides into an external and 
an internal branch, distributed to the side and front of the corresponding part of the arches in the 
neck, in the regions where the limbs are appearing as two flattened buds from the ventro-lateral 
aspect of the body. The somatic branch sweeps round into the blastema forming the limb, and 
divides into its two branches, external and internal, or dorsal and ventral, which are distributed to 
the outer (dorsal) and inner (ventral) surfaces, respectively, of the primitive limb. At this time the 
cartilaginous and muscular elements of the limb have not become differentiated. While this is 
occurring the dorsal and ventral parts of the somatic branches of the nerves entering the limb 
unite with adjacent dorsal and ventral branches, in various combinations, so as to produce the 
limb-plexuses. The nerves resulting from 
these combinations are distributed to the 
primitive, dorsal, and ventral surfaces of 
the limbs. Thus, the plexuses are formed, 
and the peripheral distribution of the 
nerves has taken place before the period 
of flexion and angulation of the limbs. 
These processes mark the conditions in the 
adult; but even then it is easy to make 
out that the nerves in the upper limb de- 
rived from the posterior (dorsal) cords of 
the brachial plexus supply the scapular 
region, extensor surface of the arm and 
fore arm, and the back of the hand,—parts 
which are derived from the dorsal surface 
of the primitive limb; while the nerves 
produced from the anterior (ventral) cords 
supply the pectoral region, front of the 
arm, fore-arm, and hand,—parts represent- 
ing the primitive ventral surface.] 
[In the lower limb, the nerves derived 
from a union of the posterior branches are 
the external cutaneous, anterior crural, 
gluteal, and external popliteal. These 
supply the iliac surfaces, the front of the 
thigh, leg, and foot,—belonging to the 
primitive dorsal surface of the limb. The 
nerves formed by the union of anterior branches, genito-crural, obturator, and internal popliteal, 
in like manner supply the parts of the limb corresponding to the ventral surface,—the inner side 
and back of the thigh, the back of the leg, and the sole of the foot [A. M. Paterson).] 
[Structure of a Spinal Ganglion.—The ganglion is invested by a thin, 
firmly adherent sheath of connective-tissue, which sends processes into the 
swelling, and continuous with the sheaths of the nerve entering and leaving the 
ganglion (fig. 526, c). In mammals, e. g., rabbit, a longitudinal section of 
such a ganglion exhibits the cells arranged in groups, with strands of nerve- 
Diagram of a spinal nerve; C, spinal cord; pr, ar, 
posterior and anterior roots ; SPD, IPD, superior 
and inferior primary divisions; d v, dorsal and 
ventral branches; sr. sympathetic root (Ross). 
Fig- 525- 774 
SPINAL GANGLION. 
[Sec. 355. 
fibres coursing longitudinally between them (fig. 526, a, b). The nerve-cells 
are usually globular in form, with a distinct capsule lined with epithelium, and 
the cell-substance itself contains a well-defined nucleus with a nuclear envelope 
and a nucleolus (fig. 527). The capsule of the cell is continuous with the 
sheath of Schwann of a nerve-fibre. The exact relation between the nerve- 
fibres and the nerve-cells is difficult to establish, but it is probable that each 
nerve cell is connected with one nerve-fibre, i. e., they are unipolar. In the 
spinal ganglia of the vertebrates above fishes, and also in the Gasserian gang- 
lion, cells are found with a single process or fibre attached to them, the nerve- 
fibre-process not unfrequently coiling a few times within the capsule. This 
process, after emerging from the capsule, becomes coated with myelin, and 
usually soon divides at a node of Ranvier (fig. 527, e). Ranvier, who first ob- 
served this arrangement, describes it as a T-shaped fibre. These nerve-cells 
with T-shaped fibres have been observed in the spinal ganglia of all vertebrates 
above fishes, in the Gasserian and geniculate ganglia, as well as in the jugular 
and cervical ganglia of the vagus. In fishes, the nerve-cells of the spinal 
ganglia are bipolar (fig. 446, 4). There is a rich plexus of capillaries in these 
ganglia, and each cell is surrounded by a meshwork of capillaries, which never 
penetrate the cell capsules.] 
Bell’s Law.—Sir Charles Bell discovered (1811) that the anterior roots 
of the spinal nerves are 
motor, the posterior are 
sensory. 
Recurrent Sensibility. 
—Magendie discovered 
(1822) the remarkable fact 
that sensory fibres are also 
present in the anterior roots, 
so that their stimulation 
causes pain. This is due to 
the fact that sensory fibres 
pass into the anterior root 
after the two roots have 
joined, and these fibres run 
in the anterior root in a 
centripetal direction (Schiff, 
Cl. Bernard). The sensi- 
bility of the anterior root is 
abolished at once by section 
of the posterior root. This 
condition is called “ recur- 
rent sensibility ” of the ante- 
rior root. When the sensi- 
bility of the anterior root is 
abolished, so is the sensibil- 
ity of the surface of the 
spinal cord in the neighbor- 
hood of the root. A long 
time after section of the 
anterior, and when the de- 
generation phenomena have 
had time to develop (§ 325), 
a few non-degenerated sen- 
sory fibres are always to be found in the central stump (Schiff, Vulpian). Schiff 
found that in cases where the motor fibres had undergone degeneration, there 
Fig. 527. 
Nerve-cell isolated 
from the spinal 
ganglion, and 
showing a nerve- 
fibre divided in a 
T-shaped man- 
ner ; x, nuclei of 
cells lining the 
cell-capsule; e', 
first, and e, sec- 
ond node of 
Ranvier; n, nu- 
cleus of nerve- 
fibre ; a, nerve- 
fibre. 
Fig. 526. 
Longitudinal section of a spinal gang- 
lion. a, nerve fibre 5 b, nerve-cells; 
c, capsule. Sec. 355.] 
bell’s law. 
775 
were always non-degenerated fibres to be found in the anterior root, which 
passed into the membranes of the spinal cord. The sensory fibres pass into 
the motor root, either at the angle of union of the roots, or in the plexus, 
or in the region of the peripheral terminations. Sensory fibres enter many 
of the branches of the motor cranial nerves at their periphery, and after- 
wards run in a centripetal direction (p. 757). Even into the trunks of sensory 
nerves, sensory branches of other sensory nerves may enter. This explains the 
remarkable observation, that after section of a nerve trunk (e. g., the median), 
its peripheral terminations still retain their sensibility (Arloing and Tripier). 
The tissue of the motor and sensory nerves, like most other tissues of the body, 
is provided with sensory nerves (Nervi nervorum, p. 672). 
[It does not follow that section of a peripheral cutaneous nerve will cause anaesthesia in the 
part to which it is distributed; in fact, one of the principal nerve trunks of the brachial plexus 
may be divided without giving rise to complete anaesthesia in any part of the area of distribution 
of the sensory branches of the nerve, and even if there be partial or complete cutaneous anaes- 
thesia, it is much less in extent than corresponds to the anatomical area of distribution. The 
anaesthetic area tends to become smaller in extent 
(AW). Thus, there is not complete independence 
in the distribution of these nerves. These results are 
explained by the anastomosis between branches of 
nerves, the exchange of fibres in the terminal net- 
works, while some sensory fibres enter the peripheral 
parts of a nerve and run centripetally, perhaps being 
distributed to the skin and conferring recurrent sensi- 
bility on the peripheral part of the nerve.] 
Deduction from Bell’s Law.—Care- 
ful observations of the effects of section of 
the roots of the spinal nerves (Magendie, 
1822), as well as the discovery of the reflex 
relation of the stimulation of the sensory 
roots to the anterior, constituting reflex 
movements {MarshallHall, Johannes Muller, 
1832), enable us to deduce the following 
conclusions from Bell’s law : 1. At the mo- 
ment of section of the anterior root there 
is a contraction in the muscles supplied by 
this root. 2. There is at the same time a 
sensation of pain due to the “ recurrent 
sensibility.” 3. After the section, the cor- 
responding muscles are paralyzed. 4. Stim- 
ulation of the peripheral trunk of the ante- 
rior root (immediately after the operation) 
causes contraction of the muscles, and even- 
tually pain, owing to the recurrent sensibil- 
ity. 5. Stimulation of the central end is 
without effect. 6. The sensibility of the 
paralyzed parts is retained completely. At 
the moment of section of the posterior 
root, there is severe pain. 8. At the same 
time movements are discharged reflexly. 9. 
After the section, all parts supplied by the 
divided roots are devoid of sensibility. 10. 
Stimulation of the peripheral trunk of the 
divided nerve is without effect. 11. Stimu- 
lation of the central end causes pain and 
reflex movements. 12. The central end 
Distribution of the cutaneous nerves of 
the arm. A, Dorsal surface—1 sc, su- 
pra-clavicular; 2 ax, axillary; j cps, 
superior posterior cutaneous; 4 cmd, 
median cutaneous; 5 cpi, inferior pos- 
terior cutaneous; 6 cm, median cuta- 
neous; 7 cl, lateral cutaneous; 8 u, 
ulnar; g ra, radial; 10 me, median. 
B, volar surface—/ sc, supra-clavicular; 
2 ax, axillary; j cmd, internal cutane- 
ous ; 4 cl, lateral cutaneous; 5 cm, cuta- 
neous medius; 6 me, median; 7 u, ulnar. 
Fig. 528. 776 
EXCITABILITY OF NERVE-ROOTS. 
[Sec. 355. 
ultimately degenerates. 13. Movement is retained completely in the paralyzed 
parts, e.g., in the extremities. 
The ultimate effects, known as Wallerian degeneration, which follow sec- 
tion of the nerve or its roots, are referred to in § 325. Recently, Joseph has 
slightly modified the statements of Waller on the degeneration in the posterior 
roots. According to him, the spinal ganglion is the nutritive centre for by far 
the largest number of the fibres of this root; but individual fibres traverse the 
ganglion without forming connections 
with its cells, so that the nutritive or 
trophic centre for this small number of 
nerve-fibres is in the spinal cord. 
Inco-ordinated Movements of Insensible 
Limbs.—After section of the posterior roots, 
e.g., of the nerves for the posterior extremities, 
the muscles retain their movements, nevertheless 
there are characteristic disturbances of their 
motor power. This is expressed in the awkward 
manner in which the animal executes its move- 
ment—it has lost to a large extent its harmony and 
elegance of motion. This is due to the fact that, 
owing to the absence of the sensibility of the 
muscles and skin, the animal is no longer con- 
scious of the resistance which is opposed to its 
movements. Hence, the degree of muscular 
energy necessary for any particular effort cannot 
be accurately graduated. Animals which have 
lost the sensibility of their extremities often allow 
their limbs to lie in abnormal positions, such as a 
healthy animal would not tolerate. In man also, 
when the peripheral ends of the cutaneous nerves 
are degenerated, there are ataxic phenomena 
(S 364. 3). 
Increased Excitability. — Harless (1858), 
Ludwig, and Cyon (controverted by v. Bezold, 
Uspensky, Grtinhagen, and G. Heidenhain) ob- 
served that the anterior roots are more excitable as 
long as the posterior roots remain intact and are 
sensitive, and that their excitability is diminished 
as soon as the posterior roots are divided. In order 
to explain this phenomenon, we must assume that, 
in the intact body, a series of gentle impulses (im- 
pressions of touch, temperature, position of limbs, 
etc.) are continuously streaming through the pos- 
terior roots to the spinal cord, where they are 
transferred to the motor roots, so that a less stimu- 
lus is required to excite the anterior roots than 
when these reflex impulses of the posterior root, 
which increase the excitability, are absent. Clearly, 
a less stimulus will be required to excite a nerve 
already in a gentle state of excitement than in the 
case of a fibre which is not so excited. In the 
former case, the discharging stimulus becomes as 
it were superposed on the excitement already pre- 
sent. (Compare \ 362.) 
The anterior roots of the spinal 
nerves supply efferent fibres to— 
1. All the voluntary muscles of the 
trunk and extremities. 
Every muscle always receives its motor fibres 
from several anterior roots (not from a single nerve- 
root). Hence, every root supplies branches to a 
Distribution of the cutaneous nerves of the 
leg (after Henle). A, Anterior surface— 
i, crural nerve; 2, external lateral cuta- 
neous; 3, ilioinguinal; 4, lumbo-in- 
guinal; 5, external-spermatic; 6, pos- 
terior cutaneous; 7, obturator; 8, great 
saphenous; 9, communicating peroneal; 
10, superficial peroneal; 11, deep peroneal; 
12, communicating tibial. B, Posterior 
surface—1, posterior cutaneous; 2 exter- 
nal femoral cutaneous; 3, obturator; 4, 
median posterior femoral cutaneous; 5, 
communicating peroneal; 6, great saph- 
enous ; 7, communicating tibial; 8, 
plantar cutaneous; 9, median plantar; 10, 
lateral plantar. 
Fig. 529. Sec. 355.] 
FUNCTIONS OF SPINAL NERVE-ROOTS. 
777 
particular group of muscles (Prayrer, P. Bert, Gad). The experiments of Ferrier and Yeo show 
that stimulation of each of the anterior roots in apes (brachial and lumbo-sacral plexuses) caused 
a complex co-ordinated movement. Section of one root did not cause complete paralysis of the 
muscles concerned in these co-ordinated movements, although the force of the movement was 
impaired. These experiments confirm the results of clinical observation on man. The fibres for 
groups of muscles of different functions (e.g., for flexors, extensors) arise from special limited 
areas of the spinal cord. The cervical and lumbar enlargements of the spinal cord are great 
centres for highly co-ordinated muscular movements. 
2. The anterior roots also supply mqtor fibres for a number of organs 
provided with smooth muscular fibres, e.g-., the bladder (§ 280), ureter, uterus. 
[These are the viscero-motor nerves of Gaskell, and from them come also vis- 
cero-inhibitory nerves.] 
3. Motor fibres for the smooth muscular fibres of the blood-vessels, the 
vaso-motor, vaso-constrictor, or vaso-hypertonic nerves [also accelerator or 
augmentor nerves of the heart]. They run in the sympathetic for a part of 
their course (§ 371). 
4. Inhibitory fibres for the blood-vessels. These are but imperfectly known. 
They are also called vaso-dilator or vaso-hypotonic nerves (§ 372). [The 
spinal cord also supplies inhibitory nerves for the heart, which leave the spinal 
axis in the vagus.] 
5. Secretory fibres for the sweat-glands of the skin (§ 289). For a part 
of their course they run in the sympathetic. 
6. Trophic fibres of the tissues (§ 342, I, e). 
The posterior roots contain all the sensory nerves of the skin and the 
internal tissues, except the front part of the head, face, and the internal part of 
the head. They also contain the tactile nerves for the areas of the skin al- 
ready mentioned. Stimuli which discharge reflex movements are conducted to 
the spinal cord through the posterior roots. The sensory fibres of a mixed 
nerve-trunk supply the cutaneous area, which is moved by those muscles (or 
which covers those muscles) to which the same branch supplies the motor fibres. 
The special distribution of the motor and sensory nerves of the body belongs 
to anatomy (figs. 518, 519, 528, 529). 
[Physiology of the Limb-Plexuses.—The idea that the nerve-strands become rearranged 
in the limb-plexuses so as to connect nerves derived from different parts of the spinal cord with 
particular groups of muscles, in order to allow of “ co-ordination of muscular action,” does not 
seem to be borne out by more extended observation. Herringham has shown by dissection (and 
the same is seen in cases of paralysis of motion and sensation) that a given muscle or part of a 
muscle, and a given spot of skin, are supplied by particular branches of individual spinal nerves 
proceeding directly from the spinal cord. The reason that the plexuses exist is, apparently, not 
a physiological one. Co-ordination cannot be effected in the plexus, where the axis-cylinder of 
the nerves do not divide; but only in the spinal cord and central nervous system, and through 
the intervention of nerve-cells. The existence of the plexuses is due to the fact that embryo- 
logically the limb consists of a flattened lappet, or bud, derived from certain somites, but at first 
presenting no signs of segmentation, with a preaxial and a postaxial border, and outer (dorsal) 
and inner (ventral) surfaces of skin, covering a double layer of muscle on each surface. The 
dorsal and ventral branches of the nerves supply these respective surfaces ; and after the nerves 
have grown out, the simple muscular strata becomes split up into individual muscles, which con- 
tain elements derived from one or more segments represented in the primitive limb. Each nerve 
is segmental, and, therefore, supplies a muscle derived, for example, from the elements of two 
segments; the nerve of distribution must contain corresponding parts of two segmental nerves. 
The plexuses appear, therefore, from an embryological cause, and have no direct physiological 
significance [A. M. Paterson).] 
356. THE SYMPATHETIC NERVE.—[Anatomical.—The sym- 
pathetic nervous system contains a large number of non-medullated or Remak’s 
fibres, and consists of a series of ganglia lying on each side of the vertebral 
column and connected with each other by inter-ganglionic fibres. The typical dis- 
tribution obtains in the thoracic region, where the lateral or vertebral ganglia 
lie close on the vertebrae. In front of this is a second series of ganglia, which 778 
SYMPATHETIC NERVOUS SYSTEM. 
[Sec. 356. 
do not form a double line, but are connected with the former and with each 
other. They are the pre-vertebral or collateral ganglia, e.g., semilunar, in- 
ferior mesenteric, etc., the nerves connecting them with the former being called 
rami efferentes. From these ganglia fibres proceed to connect them with 
ganglia lying in or about tissues or organs—the terminal ganglia {Gaskell').~\ 
[Each spinal nerve in this region 
is connected with its corresponding 
sympathetic ganglion by the ramus 
communicans, which is formed 
by fibres both from the anterior and 
posterior roots of a spinal nerve. 
It corresponds to the visceral nerve 
of the morphologist, and is com- 
posed of two parts—a white and a 
gray ramus. The white ramus 
is composed entirely of medul- 
lated fibres, and coming from the 
anterior and posterior roots of a 
spinal nerve, passes into the lateral 
and collateral ganglia. These white 
rami occur in the dog only from 
the 2d thoracic to the 2d lumbar 
nerve (fig. 530). Above and below 
this the rami are all gray and com- 
posed of non-medullated nerve- 
fibres (Cask ell). 
[In man, the upper four rami communi- 
cantes from the four upper cervical nerves 
all join the superior cervical ganglion (fig. 
517, G g, j),the 5th and 6th join the middle 
cervical, the 7th and 8th the inferior cervical 
ganglion. The lowest pair of ganglia are 
generally united by a loop on the front of 
the first coccygeal vertebra, and they lie in 
relation with the coccygeal ganglion.] 
[Cephalic Portion.—As the sympa- 
thetic ascends to the head it forms connec- 
tions with many of the cranial nerves, and 
there is a free exchange of fibres between 
these nerves. (The function and signifi- 
cance of these exchanges are referred to 
under the physiology of the cranial nerves.)] 
[Dorsal and Abdominal Portion.— 
Numerous fibres pass from these parts 
chiefly to the thoracic and abdominal cav- 
ities, where they form large gangliated 
plexuses, from which functionally different 
fibres proceed to the different organs.] 
[In the dog, the 2d, 3d, 4th, and 5th 
thoracic pass upwards into the cervical sym- 
pathetic, those in the dorsal region being 
directed downwards from the lateral ganglia 
to form the splanchnics (fig. 530). The 
gray non-medullated nerve-fibres of each 
gray ramus are connected with the cells of 
its ganglion (lateral); the fibres do not go 
beyond the ganglion, but really run to the corresponding spinal nerve to ramify in the sheaths of 
the nerves, the connective-tissue on the vertebrae and the dura mater, and perhaps the other 
spinal membranes; so that, according to Gaskell, no non-medullated nerves leave the central 
nervous system by the spinal nerve-roots. Thus, the white rami communicantes alone con- 
Diagram of the visceral nerves of the dog; the arrangement of the cranial visceral nerves is taken from Henle. The nerves 
which contain bundles of fine medullated nerve-fibres are indicated thus: ; those which consist chiefly of non- 
medullated fibres are indicated thus: . The formation of the rami viscerales in the cervico-cranial, thoracic and 
sacral regions, and the general distribution of the visceral nerves are shown (Gasket/). 
Fig. 530. Sec. 356.] 
VASO-MOTOR AND VASO-DILATOR FIBRES. 
779 
stitute the rami viscerales of the morphologist, and all the visceral nerves passing out from the 
central nervous system into the sympathetic system pass out by them alone. All the nerves in 
the white ramus are of small calibre (1.8 /z to 2.7 //) and medullated, while the true motor fibres 
are much larger (14.4 /z to 19 fi). The small, white fibres can be traced upwards as medul- 
lated fibres into the superior cervical ganglion, and in the thorax over the lateral ganglia to 
form the splanchnics into the collateral ganglia, beyond which they cease to be medullated. 
By the 2d and 3d sacral nerves some fibres of smallest calibre issue to form the nervi erigentes, 
which pass over and do not communicate with the lateral ganglia, but enter the hypogastric 
plexus, whence they send branches upwards to the inferior mesenteric plexus and downwards to 
the bladder, rectum, and generative organs. Gaskell proposes to call them the pelvic 
splanchnic nerves (fig. 530).] 
[In the cervical region there is no white ramus, and the nerve-roots contain no nerve-fibres 
of small calibre. But in this region rises the spinal accessory nerve, between the anterior 
and posterior roots. It contains small and large nerve-fibres; the former pass into the internal 
division of this nerve and join the ganglion of the trunk of the vagus, while the large motor 
fibres form its external branch and supply the sterno-mastoid and trapezius muscles.] 
[All the vaso-motor nerves arise in the central nervous system, and they 
leave the spinal cord as the finest medullated fibres in the anterior roots of all 
the spinal nerves between the 2d thoracic and 2d lumbar (dog) “ along the 
corresponding ramus visceralis, enter the lateral or main sympathetic chain of 
ganglia, where they become non-medullated, and are thence distributed either 
directly or after communication with other ganglia” (Gaske//). In the lateral 
ganglia they terminate in the multipolar nerve-cells, where they become non- 
medullated ; at least, this seems to be the case with some of the vaso-constrictor 
fibres.] 
[“The vaso-dilator nerves leave the central nervous system among the 
fine medullated fibres, which help to form the 
cervico-cranial and sacral rami viscerales, and pass 
without altering their character into the distal 
ganglia” (Gaskell).] 
[“The viscero-motor nerves, upon which 
the peristaltic contraction of the thoracic portion 
of the oesophagus, stomach and intestines depends, 
leave the central nervous system in the outflow of 
fine medullated nerves which occurs in the upper 
part of the cervical region, and pass by way of 
the rami viscerales, of the accessory and vagus 
nerves to the ganglion trunci vagi, where they 
become non-medullated” (Gas&e/l).~\ 
[“ The inhibitory nerves of the circular mus- 
cles of the alimentary canal and its appendages 
leave the central nervous system in the anterior 
roots, and pass out among the fine medullated fibres 
of the rami viscerales into the distal ganglia with- 
out communication with the proximal ganglia” 
(Gaskell).] 
[Structure of a sympathetic ganglion.— 
The structure of the sympathetic nerve-fibres and 
nerve-cells has already been described in § 321. 
On making a section of a sympathetic gang- 
lion, e. g., the human superior cervical, we 
observe groups of cells with bundles of nerve- 
fibres—chiefly non-medullated—running between 
them, and the whole surrounded by a laminated 
capsule of connective-tissue, which sends septa 
into the ganglion. The nerve-cells have many processes, and are, therefore, 
Nerve-cells isolated from the 
superior cervical sympathetic 
ganglion of a rabbit, f f, Re- 
mak’s fibres; n'n/, nuclei of 
these fibres; n n, cell nuclei. 
F'g- 531- 780 
FUNCTIONS OF THE SYMPATHETIC. 
[Sec. 356. 
multipolar, and each cell is surrounded by a capsule with nuclei on its inner 
surface (fig. 446, II). The processes pierce the capsule, and one of them 
certainly—and perhaps all the processes—are connected with a nerve-fibre. 
Ranvier states that each cell has a fibrillated outer portion and a more granular 
inner part. Each of the processes becomes continuous with a fibre of Remak 
(fig. 531). Not unfrequently yellowish-brown pigment is found in the cell- 
substance. Similar cells have been found in the ophthalmic, sub-maxillary, 
otic, and spheno-palatine ganglia. The number of medullated nerve-fibres 
diminishes as the sympathetic nerves are traced towards their distribution. 
Ranvier states that it is possible in the rabbit to trace the conversion of a 
medullated fibre into a branched fibre of Remak. The blood-vessels of the 
sympathetic ganglia in mammals are peculiar. The arteries are small, and 
after subdivision form a capillary network, each mesh of which encloses several 
ganglionic cells. The veins on the contrary are very large, tortuous, varicose, 
and often terminate in culs-de-sac, into which several capillaries open. The 
arrangement of the veins is spoken of as the venous sinuses of these ganglia, 
being compared by Ranvier to the sinuses of the dura mater and venous 
plexuses of the spinal canal.] 
Functions of the sympathetic nerves.—The following is merely a 
general summary :— 
I. Independent Functions of the sympathetic are those of certain nerve- 
plexuses which remain after all the nervous connections with the cerebro-spinal 
branches have been divided. The activities of these plexuses may be influ- 
enced—either in the direction of inhibition or stimulation—through fibres 
reaching them from the cerebro-spinal nerves. 
To these belong :— 
1. The automatic ganglia of the heart (§ 58). 
2. The mesenteric plexus of the intestine (§ 161). 
3. The plexuses of the uterus, Fallopian tubes, ureters (also of the blood- 
and lymph-vessels). 
II. Dependent Functions.—Fibres run in the sympathetic, which (like 
the peripheral nerves) are active only when their connection with the central 
nervous system is maintained, e. g., the sensory fibres of the splanchnic. Others 
again convey impulses from the central nervous system to the ganglia, while the 
ganglia in turn modify the impulses which inhibit or excite the movements of 
the corresponding organs. 
The following statement is a resumi of the functions of the sympathetic, according to the 
anatomical arrangement:— 
A. Cervical Part of the Sympathetic. 
1. Pupil-dilating fibres (compare Ciliary ganglion, § 347, I, and Iris, 
§ 392). According to Budge, these fibres arise from the spinal cord, and run 
through the upper two dorsal and lowest two cervical nerves into the cervical 
sympathetic, which conveys them to the head. Section of the cervical sympa- 
thetic or its rami communicates causes contraction of the pupil. (The central 
origin of these fibres is referred to in § 362, 1, and § 367, 8.) 
2. Motor fibres for Muller’s smooth muscle of the orbit, and partly for the 
external rectus muscle (§ 348). 
3. Vaso-motor branches for the outer ear and the side of the face (Cl. 
Bernard'), tympanum (Prussak), conjunctiva, iris, choroid, retina (only in part 
—see Ciliary ganglion, § 347, I), for the vessels of the oesophagus, larynx, 
thyroid gland—fibres for the vessels of the brain and its membranes (Bonders 
and Callenfels). [In the dog the vaso-motor fibres for the head leave the cord Sec. 356.] 
CERVICAL SYMPATHETIC. 
781 
by the anterior roots of the second, third, fourth, and fifth dorsal nerves, enter 
the corresponding sympathetic ganglia, and run through the annulus of Vieus- 
sens forward into the cervical sympathetic, and thus reach their terminations in 
the blood-vessels of the head.] 
4. In the cervical portion are afferent fibres which excite the vaso-motor 
centre in the medulla (.Aubert). 
5. Secretory (trophic) and vaso-motor fibres for the salivary glands 
(§ 145)- 
6. Sweat-secretory fibres (see § 288, II). 
7. According to Wolferz and Demtschenko the lachrymal glands receive 
sympathetic secretory fibres (?). 
[The cervical sympathetic contains secretory fibres for the glands in the 
muzzle of the ox, but it also, according to Arloing, contains inhibitory-secre- 
tory fibres. It also seems to contain trophic nerve-fibres; at least marked 
histological changes occur in the muzzle of the ox and nose of the dog after 
section of the cervical sympathetic. In the dog, after two months or so, the 
skin of the nose becomes papillated and dry, while there is a great hypertrophy 
of the corneous layer of the epidermis.] 
[Section of the Cervical Sympathetic.—This experiment is easily done 
on a rabbit, preferably an albino one. Divide the nerve in the neck, and imme- 
diately thereafter (1) the ear 
and adjoining parts on that 
side become greatly congested 
with blood, blood-vessels ap- 
pear that were formerly not 
visible, and as a result of the 
increased quantity of blood in 
the ear (hypersemia), there is 
(2) a rise of the temperature 
amounting to even 40 to 6° C. 
(C/. Bernard). These are the 
vaso-motor changes. (3) The 
pupil is contracted, the cornea 
flattened, and there is retraction 
of the eyeball and consequent 
narrowing of the palpebral 
fissure. These are the oculo- 
pupillary symptoms. Stimu- 
lation (electrical) of the peri- 
pheral end produces the oppo- 
site results,—pallor of the ears, 
owing to contraction of the 
blood-vessels, with consequent 
fall of the temperature ; dila- 
tation of the pupil, bulging of the cornea, protrusion of the eyeball (exoph- 
thalmos), and widening of the palpebral fissure. At the same time, the 
blood-vessels to the salivary glands are contracted, and there is a secretion of 
thick saliva. The last results are due to the vaso-constrictor and secretory fibres. 
The vaso-motor and oculo-pupillary fibres, although they lie in the same trunk 
in the neck, do not issue from the cord by the same nerve-roots; the latter 
come out of the cord with the anterior roots of the 1st and 2d dorsal nerves 
(dog), while section of the cord between the 2d and 4th dorsal vertebrae pro- 
duces the vaso-motor changes only. The nasal mucous membrane and lachry- 
mal gland are influenced by the sympathetic.] 
Fig- 532- 
Normal ear of a rabbit. B, effect on the blood-vessels oi 
section of the cervical sympathetic nerve. 782 
[Sec. 356. 
THORACIC AND ABDOMINAL SYMPATHETIC. 
[Division of the cervical sympathetic in young,growing animals results in hypertrophy of 
the ear, and increased growth of the hair on that side {Bidder, IV. Stirling).'] 
[The vago-sympathetic nerve (dog) in the neck contains vaso-dilator fibres (really in 
the sympathetic) for the skin and mucous membranes of that side of the head. Weak stimula- 
tion of the central end of the sympathetic causes dilatation of the blood-vessels of these parts. 
[The local application of nicotin to the superior cervical sympathetic ganglion prevents stimu- 
lation below this ganglion from causing dilation of the vessels, but stimulation above the ganglion 
still causes the normal effect, so that Langley concludes that the vaso-dilator fibres are connected 
with nerve-cells in the superior cervical ganglion.] The vaso-dilator fibres of the superior 
maxillary nerve probably come from the same source. The centre for these nerves is in the 
dorsal region of the cord between the 1st and 5th dorsal vertebrae, where the fibres pass out with 
the rami communicantes to enter the cervical sympathetic {Dastre and Moral). The vaso dilator 
fibres occur in the posterior segment of the ring of Vieussens, and when they are stimulated 
after section of the 7th cranial nerve, there is a “pseudo-motor” effect on the muscles of the 
cheek and lip (£ 349).] 
[Action of Nicotin on the nerve-cells of the superior cervical 
ganglion.—If nicotin be injected into a vein of a rabbit or dog, or if a 1 per 
cent, solution be applied locally to the superior cervical ganglion, stimulation 
of the cervical sympathetic below this ganglion, or of the ganglion itself, does 
not cause dilation of the pupil or constriction of the blood-vessels of the ear 
or face, nor does it cause secretion of saliva, but stimulation of the nerve 
above the ganglion causes these changes in a normal manner. From the results 
of the local application of nicotin solution to the superior cervical ganglion, it 
is evident that nicotin paralyzes the nerve-cells of this ganglion, so Langley con- 
cludes that the dilator fibres for the pupil, the vaso-constrictor fibres for the ear 
and head, and the secretory fibres for the glands end in cells in the superior cer- 
vical ganglion {Langley and Dickinson).] 
B. Thoracic and Abdominal Sympathetic. 
1. The sympathetic portion of the cardiac plexus (§ 57, 2), which receives 
accelerating or augumentor fibres for the heart from the lower cervical and 
1st thoracic ganglion (Cl. Bernard, v. Bezold, Cyon, Schmiedeberg). The 
fibres arise partly from the sympathetic and partly from the plexus around the 
vertebral artery (v. Bezold, Sever). (Compare § 370.) 
2. For the vaso-motor fibres passing through the sympathetic to the extremi- 
ties, skin of the trunk, and lungs (see § 371). For vaso-dilators (§ 372). 
3. The cervical sympathetic and the splanchnic contain fibres which, when 
their central ends are stimulated, excite the cardio-inhibitory system in 
the medulla oblongata {Bernstein). 
4. The functions of the splanchnic are referred to in §§ 164, 175, 276, and 
371- 
5. The functions of the solar and mesenteric plexuses are referred to 
in §§ 183 and 192. After extirpation of the coeliac ganglion, Lamansky ob- 
served temporary disturbance of digestion, undigested food being passed per 
anum. 
[Action of Nicotin on the solar plexus.—The inhibitory fibres of the 
splanchnic end in cells of the solar plexus, and this is true for the vaso-con- 
strictor as well as for the vaso-dilator fibres, while the splanchnic vaso-motor 
fibres for the kidney end in the cells of the renal plexus. The fibres of the 
vagus, which are motor for the intestines, do not end in the nerve-cells of the 
solar plexus {Langley and Dickinson). These results have been obtained by a 
study of the action of nicotin applied locally to the solar plexus, and observing 
the results that follow stimulation of the nerves passing to and those leading 
from the solar plexus ; thus the local application of nicotin to the solar plexus 
prevented stimulation of the splanchnic nerve from causing inhibition of the Sec. 356.] 
PATHOLOGY OF SYMPATHETIC. 
783 
movements of the stomach and intestines, while stimulation of the branches 
proceeding from the solar plexus caused these effects. Even when the solar 
plexus and the hypogastric plexus are eliminated by the action of nicotin, 
stimulation of the vagus still causes movements of the intestine and stomach ; 
therefore Langley and Dickinson conclude that the vagus does not form con- 
nection with the nerve-cells at these plexuses.] 
6. For the secretory fibres for sweating, see § 289, II. 
7. Lastly, the abdominal portion of the sympathetic contains motor and 
vaso-motor fibres for the spleen, the large intestine (accompanying its 
arteries), bladder (§ 280), ureters, uterus (running in the hypogastric 
plexus), vas deferens, and vesiculae seminales. Stimulation of all of 
these nerve-channels causes increased movement of the organs, but it must be 
remembered that the diminished supply of blood thereby produced also acts as 
a stimulus (§ 161). Section of these nerves is followed by dilatation of the 
blood-vessels, with subsequent derangement of the circulation, and ultimately 
of the nutrition. The relation of the suprarenal bodies to the sympathetic 
is referred to in § 103, IV. [It is important to note that the medulla and cor- 
tex of these glands have totally different origins. The cortex is developed 
from mesoblastic cells round the blood-vessels, while the medulla represents 
modified sympathetic ganglia ] The renal plexus is referred to in § 276, 
while the cavernous plexus is treated of in § 436. 
Pathological.—Considering the numerous connections of the sympathetic, we would naturally 
suppose that it offers an extensive area for pathological changes. Affections involving the vaso- 
motor system are referred to in § 371. 
The cervical sympathetic is most frequently paralyzed or stimulated by traumatic conditions, 
wounds by bullets or knives, tumors, enlarged lymph-glands, aneurisms, inflammation of the 
apices of the lungs and the adjacent pleurae, while exostoses of the vertebrae may stimulate it in 
part or paralyze it in part. The phenomena so produced have partly analyzed in treating of the 
ciliary ganglion (§ 347, I). Stimulation of the cervical sympathetic in man causes dila- 
tation of the pupil (mydriasis spastica), pallor of the face, and occasionally hyperidrosis or 
profuse sweating ($ 289, 2, and $ 288); disturbance of vision for near objects, as the pupil 
cannot be contracted (see Accommodation, \ 387), and hence the spherical aberration of the lens 
(§ 391) must also interfere with vision; protrusion of the eyeball with widening of the palpebral 
fissure. Paralysis or section of the cervical sympathetic causes increased fullness of the 
blood-vessels of the side of the head, with occasional anidrosis; contraction of the pupil (myosis 
paralytica), which undergoes changes in its diameter during accommodation, but not as the 
effect of the stimulation of light—atropin dilates it slightly. The slit between the eyelids is 
narrowed, the eyeball retracted and sunk in the orbit, the cornea somewhat flattened, and the 
consistence of the eyeball diminished. Stimulation of the sympathetic is followed by an 
increased secretion of saliva (§ 145). The above-described symptoms have been occasionally 
accompanied by unilateral atrophy of the face. 
Irritation in the area of the splanchnic, as occurs occasionally in lead poisoning, is character- 
ized by violent pain (lead colic), inhibition of the intestinal movements (hence the persistent 
constipation),slowing of the heart’s action, brought about reflexly, just as Goltz’s “tapping” 
experiment (§ 369). Irritation in the area of the sensory nerves of the sympathetic may give 
rise to that condition which is called by Romberg neuralgia hypogastrica, a painful affection of 
the lower abdominal and sacral regions, hysteralgia, neuralgia testis, which are localized in the 
plexuses of the sympathetic. In affections of the abdominal sympathetic, there may be severe 
constipation, with diminished or increased secretion of the intestinal glands (§ 186). 
357. COMPARATIVE—HISTORICAL.—Comparative. — Some of the cranial 
nerves may be absent, others, again, may be abortive, or exist as branches of other nerves. 
The facial nerve, which supplies the muscles of expression in man, and is, at the same time, the 
nerve for facial respiratory movements, diminishes more and more in the lower classes of the 
vertebrata, pari passu, with the diminution of the facial muscles. In birds and reptiles, it 
supplies the muscles of the hyoid bone, or the superficial cervical muscles of the nape of the 
neck. In amphibians (frog), the facial no longer exists as a separate nerve, the nerve which 
corresponds to it springing from the trigeminus. In fishes, the 5th and 7th nerves form a joint 
complex nerve. The part corresponding to the facial (also called ramus opercularis trigemini) 
is the chief motor nerve of the muscles of the gill-cover, and is, therefore, the respiratory nerve. 
In the cyclostomata (lamprey) there is an independent facial. The vagus is present in all verte- 784 
COMPARATIVE AND HISTORICAL. 
[Sec. 357. 
brata ; in fishes it gives off a large nerve, the lateral nerve of the body (N. lateralis), which 
runs along each side of the body close to the lateral canal. It is also present in the tadpole. 
Its rudimentary representative in man is the auricular branch. In the frog the 9th, 10th, and 
nth arise together from one trunk, and the 7th and 8th from another. In fishes and amphibia, 
the hypoglossal is, the first cervical nerve. In amphioxus, the cerebral and spinal nerves are 
not distinct from each other. The spinal nerves are remarkably similar in all classes of the 
vetebrata. The sympathetic is absent in the cyclostomata, where it is represented by the 
vagus. Its course is along the vertebral column, where it receives the rami communicantes of 
the spinal nerves. In the region of the head its connections with the 5th and 10th nerves are 
specially developed. In frogs, and still more so in birds, the number of connections with the 
cranial nerves increases. 
Historical.—The vagus and sympathetic were known to the Hippocratic School. According 
to Erasistratus, all the nerves proceed from the brain and spinal cord; Herophilus was the first 
to distinguish the nerves from the tendons, which Aristotle confounded with each other. 
Marianus (8o A. D.) recognized seven pairs of cranial nerves. Galen was in possession of a wide 
range of important facts in the physiology of the nervous system ($ 140); he observed that loss 
of voice followed ligature of the recurrent nerves; and he was acquainted with the accessorius, 
and the ganglia on the abdominal nerves. The cauda equina is referred to in the Talmud; 
Coiter (1573) described exactly the anterior and posterior spinal-nerve roots. Van Helmont 
(f 1644) states that the peripheral motor nerves also give rise to impressions of pain, and 
Cesalpinus (1571) remarks that interruption of the blood-stream makes the parts insensible. 
Thomas Willis described the chief ganglia (1664). In Des Cartes there is the first indication of 
a study of reflex movements; Stephen Hales and Robert Whytt showed that the spinal cord 
was necessary for such acts. Prochaska described the reflex channels, [while Marshall Hall 
established the doctrine of reflex, or, as he called them, “ diastaltic ” actions.] Duverney 
(1761) discovered the ciliary ganglion. Gall traced more carefully the course of the 3d and 
6th nerves, and also the spinal nerve, into the gray matter. Hitherto only nine nerves of the 
brain have been enumerated; Sommerring (1791) separated the facial from the auditory nerve, 
Andersch (1797) the 9th, 10th, and nth nerves. Physiology of the Nerve-Centres. 
358. GENERAL.—[The nerve-fibres and nerve-cells constitute the ele- 
ments out of which nerve-centres are formed, being held together by connective 
tissue. In the process of evolution, groups of nerve-cells with connecting 
fibres are arranged to constitute nervous masses, whereby there is a correspond- 
ing integration of function. Thus, with structural integration there is a func- 
tional integration. When the structure suffers, so also does the function, and 
those parts which are most evolved, as well as those actions which have to be 
learned by practice, are the first to suffer during the dissolution of the ner- 
vous system.] 
General Functions.—The central organs of the nervous system are in 
general characterized by the following properties :— 
1. They contain nerve-cells, which are either arranged in groups in the 
interior of the central organs of the nervous system, or embedded in the periph- 
eral branches of the nerves. [Nerve-cells are centres of activity, originate 
impulses and conduct impulses as well, while nerve-fibres are chiefly conductors.] 
2. The nerve-centres are capable of discharging reflexes, e. g., reflex-motor, 
reflex-secretory, and reflex-inhibitory acts (fig. 511). 
3. The centres may be the seat of automatic excitement, i. <?., they may 
manifest phenomena, without the application of any apparent external stimulus. 
The energy so liberated may be transferred to act upon other organs. This 
automatic state of excitement or stimulation may be continuous, i. e., may be 
continued without interruption, when it is called tonic automatic or tonus ; or 
it may be intermittent, and occur with a certain rhythm (rhythmical automatic). 
4. The central organs are trophic centres for the nerves proceeding from 
them; they may also perform similar functions for the tissues innervated by 
them. 
5. The psychical activities are dependent upon an intact condition of the 
ganglionic central organs. These various functions are distributed over dif- 
ferent centres. 
[The term “ centre ” is merely applied to an aggregation of nerve-cells so related to each 
other as to subserve a certain function, but, inasmuch as these cells are in relation to each other 
and with other cells in many ways, various combinations of them may result; again, we have 
also to take into account the greater or less resistance in some paths than in others, so that the 
variety of combinations which these cells may subserve is enormous. 1 These cells give off pro- 
cesses which branch, and come into relation with processes from other cells. Thus, innumerable 
ways are opened up to nervous impulses by these combinations, so that in a certain way we may 
regard a cell as a junction of these conducting fibres, or a “ shunt ” whereby an impulse may be 
shunted on to one or other branch in the direction of least resistance, or in the best beaten path, 
as it were, while there may be a “ block ” in other directions.] 
[In connection with the histology of the central nervous system we have to 
study:— 
A. The nervous constituents. 
(1) Nerve-fibres. 
(2) Nerve-cells. 
B. Non-nervous constituents. 
(1) Vessels (blood and lymph). 
(2) Epithelium. 
(3) Sustentacular tissue. 
(a) Connective tissue. 
(b) Neuroglia.] 786 
STRUCTURE OF THE SPINAL CORD. 
[Sec. 359. 
The Spinal Cord. 
359. STRUCTURE OF THE SPINAL CORD.—[The key to the 
study of the central nervous system is to remember that it begins as an involu- 
tion of the epiblast, and is originally tubular, with a central canal, dilated in 
the brain-end into ventricles. In the spinal cord there are three concentrated 
parts: first, the columnar ciliated epithelium, outside this the central gray 
tube, and, covering in all, the outer white conducting fibres (ZT/Y/).] 
[Structure.—The spinal cord forms a more or less cylindrical column 40-50 
cm. (18 inches) in length, reaching from the lower end of the medulla ob- 
longata or bulb at the level of the first cervical vertebra to the first or second 
lumbar vertebra, where it ends in a slender filament, the filum terminate, which 
lies amongst a leash of nerve-roots called the cauda equina. Above, the cord 
is continuous with the medulla oblongata or bulb at the margin of the foramen 
magnum. The whole cord is enclosed in the vertebral canal, and is further 
protected by its “ membranes.” Although the cord does not present uni- 
formity of characters throughout its extent, still there are certain general fea- 
tures common to it as a whole.] 
[It is invested by membranes—the pia mater, composed of two layers 
and consisting of connective-tissue with blood-vessels, being firmly adherent to 
the surface of the cord and sending septa into the substance of the latter. Both 
layers dip into the anterior median fissure, and only the inner one into the pos- 
terior median groove. The arachnoid is a more delicate membrane and non- 
vascular, while the dura mater is a tough membrane lining the vertebral canal, 
and forming a theca or protective coat for the cord (§ 381).] 
The spinal cord consists of white matter externally, giving the cord its 
opaque, white appearance, and gray matter internally ; and in each the gray 
matter has the form of two crescents )-( placed back to back [or a capital H]. 
In each crescent we can distinguish an anterior (co.a), a posterior horn 
(co.p), and a middle part, cervix or neck. An isthmus or gray commissure 
connects the two crescents across the middle line. In the centre of this gray 
commissure is a canal—central canal—which runs from the calamus scriptorius 
downwards; it is lined throughout by a single layer of ciliated cylindrical epi- 
thelium in the foetus, the cilia not being visible in the adult, and the canal 
itself is the representative of the embryonal “ medullary tube ” (figs. 533, 540). 
[The central canal is the remains of the neural canal of the embryo, which was 
originally the comparatively wide neural canal of the embryo. Some observers 
doubt whether the cilia are really true cilia. This epithelium is epiblastic in 
origin.] [The part of the gray commissure in front of this canal is called the 
anterior gray commissure, and the part behind, the posterior gray com- 
missure. In front of the gray commissure, and between it and the base of 
the anterior median fissure, are bundles of white nerve-fibres passing in a hori- 
zontal or oblique direction from the anterior column of one side to the gray 
matter of the anterior cornu of the opposite side (fig. 533). These decussating 
fibres constitute the anterior white commissure.] 
The white matter surrounds the gray, and is arranged in several columns 
[anterior, lateral, and posterior—by the passage of the nerve-roots to the 
cornua (figs. 533, 540)]. Along the anterior surface of the cord there runs a 
well-marked fissure, which dips into the cord itself, but does not reach the gray 
matter, as a mass of white matter—the white commissure—runs from one 
side of the cord to the other. Between this fissure, known as the ventral or Sec. 359.] 
STRUCTURE OF THE SPINAL CORD. 
787 
anterior median fissure, and the line of exit of the anterior roots of the 
spinal nerves, lies the anterior column {f.a)] the white matter lying laterally 
between the origin of the anterior and posterior roots of the spinal nerves is 
the lateral column {f.l), while the white matter lying between the line of 
origin of the posterior roots of the so-called dorsal or posterior median 
fissure is the posterior column {fp). [The posterior median fissure is not 
a real fissure, but is filled up with the inner layer of the pia mater, which dips 
down from the under surface of this membrane quite to the gray matter of the 
Fig- 533- 
Transverse section of the human spinal cord at the level of the 8th dorsal vertebra; X 10. s.a, 
anterior longitudinal fissure; s.p, septum posterium; c.a, anterior commissure; s.g.c, sub- 
stantia gelatinosa centralis; c.c, central canal; c.p, posterior commissure; v, vein; co.a, 
anterior horn ; co.l, lateral horn, and behind it the processus reticularis; cop, posterior horn; 
a, antero-lateral, b, anteromedian group of ganglionic cells; c, cells of the lateral horn; 
d, cells of Clarke’s column; e, solitary cells of the posterior horn; r.a, anterior root; rp, 
posterior root, with f its bundle of fibres; f', postero-internal bundle ; f", longitudinal 
fibres of the posterior cornu ; sg.R, gelatinous substance of Rolando; fa, anterior column; 
f.l, lateral column; fp, posterior column. 
posterior commissure.] Each posterior column, in certain regions of the cord, 
may be subdivided into an inner part lying next the fissure, the postero- 
median or Goll’s column, or the inner root-zone (Charcot, fig. 533,/); 
and an outer larger part next the posterior root, known as the postero- 
external or Burdach’s column, or the outer root-zone (Charcot, fig. 
533’ /')• . . 
The white matter consists chiefly of medullated fibres without the sheath 
of Schwann, but provided with the neuro-keratin sheaths of Kiihne and Ewald 788 
STRUCTURE OF THE SPINAL CORD. 
[Sec. 359. 
(§ 321), the fibres themselves being 
chiefly arranged longitudinally. 
[The incisures of Schmidt exist in 
these fibres, and can be demon- 
strated by the interstitial injection of 
osmic acid (Ranvier). The fibres 
are also provided with Ranvier’s 
Fig- 534- 
Fig- 535- 
Fig. 534.—Transverse section of the white matter of the cord; X 150. a, peripheral layer. 
Besides the transverse sections of the nerve-fibres, large and fine, there are three branched 
connective-tissue corpuscles (r). Fig. 535.—Multipolar nerve-cells from the gray matter of 
the anterior horn of the spinal cord (ox), a, nerve-cell; b, axis-cylinder; c, gray matter; 
d, white matter of column; e, e, branches of cells. 
nodes.] The nerve-fibres of the nerve-roots, as well as those that pass from the 
gray matter into the columns, have a transverse or oblique course. There are 
also decussating fibres in the anterior or white commissure. [In a transverse 
section of the white matter of the spinal cord, the nerve-fibres are of different 
Diagram of the absolute and relative extent of the gray matter, and of the white columns in 
successive sectional areas of the spinal cord as well as the sectional areas of the several 
entering nerve-roots. NR, nerve-roots; AC, LC, PC, anterior, lateral, and posterior 
columns; Gr, gray matter. 
F>g- 536- 
sizes, and appear like small circles with a rounded dot in their centre—the axis- 
cylinder; the latter may be stained with carmine or other dye (fig. 534). 
They are smallest in the postero-median or Goll’s column, and largest in the 
crossed and direct pyramidal tracts, which are motor. The white substance of 
Schwann, especially in preparations hardened in salts of chromium, often pre- 
sents the appearance of concentric lines. Fine septa of connective-tissue 
carrying blood-vessels lie between groups of the nerve-fibres, w’hile here and 
there between the nerve-fibres may be seen branched neuroglia corpuscles. Im- Sec. 359.] 
789 
STRUCTURE OF THE SPINAL CORD. 
mediately underneath the pia mater there is a 
pretty thick layer of neuroglia, which in- 
vests the prolongations of the pia into the 
cord (fig. 534, a).] 
[The gray matter differs in shape in the 
different regions of the cord, and so does 
the gray commissure (fig. 537). The latter 
is thicker and shorter in the cervical than 
in the dorsal region, while it is narrow in 
the lumbar region. The amount of gray 
matter undergoes a great increase opposite 
the origins of the large nerves, the increase 
being most marked opposite the cervical and 
lumbar enlargements. Ludwig and Woro- 
schilofif constructed a series of curves from 
measurements by Stilling of the sectional 
areas of the gray and white matter of the 
cord, as well as of the several nerve-roots. 
These curves have been arranged in the an- 
nexed convenient form by Schafer after 
Woroschiloff (fig. 536)] :— 
[In the cervical region, the lateral 
white columns are large, the anterior cornu 
of the gray matter is wide and large, while 
the posterior cornu is narrow; Goll’s column 
is marked off by a depression and a pro- 
longation of the pia mater; the cord itself 
is broadest from side to side. In the dorsal 
region, the gray matter is small in animals, 
and both cornua are narrow and of nearly 
equal breadth, while the cord itself is 
smaller and cylindrical. In it the inter- 
medio-lateral and posterior vesicular groups 
of cells are distinct. They have probably 
relations to viscera. The commissure, and 
therefore the central canal, lie well forward 
between the crescents. In the lumbar region the gray matter is relatively and 
absolutely greatest, while the white lateral columns are small, the central canal 
in the commissure being nearly in the middle of the cord. In the conus 
medullaris, the gray matter makes up the great mass of it, with a few white 
fibres externally (figs. 537, 538).] 
The anterior cornu of the gray matter is shorter and broader, and does 
not reach so near to the surface as the posterior; moreover, each anterior 
nerve-root arises from it by several bundles—it contains several groups of large 
multipolar ganglionic cells (fig. 535); the posterior cornu is more pointed, 
longer, and narrower, and reaches nearer to the surface, the posterior root 
arising by a single bundle at the postero-lateral fissure; while the cornu itself 
contains a few small fusiform nerve-cells, and is covered by the substantia 
gelatinosa of Rolando, which is in part an accumulation of neuroglia. 
[The substantia gelatinosa on the posterior cornu is marked by striation 
where the posterior root-fibres traverse it. It contains some connective-tissue 
cells and some fusiform nerve-cells, especially near the margins. The substance 
itself stains deeply with carmine.] 
[The outer margin of the gray matter near its middle is not so sharply defined 
from the white matter as elsewhere ; and, in fact, a kind of anastomosis of the 
Transverse sections of the spinal cord 
in different regions. A, through the 
middle of the cervical; B, the dorsal; 
C, the lumbar enlargement; D, 
upper part of the conus medullaris; 
E, at the 5th sacral vertebra; F, at 
coccyx; A, B, C, enlarged twice; 
D, E, F, thrice; a, anterior; p, pos- 
terior root. 
Fig- S37- 790 
NERVE-CELLS IN CORD. 
[Sec. 359. 
gray matter projects into the lateral column, especially in the cervical region, 
constituting the processus reticularis (fig. 540).] 
[Arrangement of Nerve-Cells.—The nerve-cells are arranged in several 
groups, forming columns more or less continuous. There are those of the 
anterior and posterior horns, those of the lateral column (intermedio-lateral), 
and the posterior vesicular column of Clarke (fig. 538). The anterior and 
posterior groups exist as continuous columns along the entire cord. The cells 
in the anterior cornu are subdivided into smaller groups, which vary in the 
different regions of the cord. There is an inner or median group near the 
anterior angle of the cornu. It is the smallest group, and is absent in the lumbar 
region. Near the anterior edge is the anterior group, and in the external part 
of the cornu is the antero-laleralgroup. These two groups are often united, 
as in the mid-cervical region. There is usually a third large group—the external 
or postero-lateral in the posterior outer angle of the anterior cornu. The cells 
of the anterior horn being very large (67 to 135 fi). The cells of the posterior 
cornu usually do not lie in groups, but singly, hence they have been called 
solitary cells. They are bipolar or fusiform cells, and are about 18 u in 
C, Transverse section of the human spinal cord at the level of the 6th cervical nerves; Prfn, 
median process of the anterior horn; Til, intermedio-lateral tract or lateral horn; D, at 
the level of the 3d dorsal nerves; CCl, Clarke’s column; L, at the level of the 5th lumbar 
nerve; m, median; Iv, latero-ventral; Id, latero-dorsal; c, central groups of cells of ante- 
rior horn. 
Fig- 538- 
diameter. They lie especially at the outer side of the base of the cornu of the 
gray matter, and are placed with their long axis horizontal, and their processes 
are directed forwards and backwards. Those of the lateral column are distinct, 
except in the lumbar and cervical enlargements, where they blend with the 
anterior horn. The vesicular column of Clarke (cells 40 to 90 //) is dis- 
continuous, and is limited to (1) the thoracic region, (2) cervico-cranial region, 
(3) sacral region, being most conspicuous in (1), where it corresponds abso- 
lutely to the outflow of visceral nerves {Gaskell). In the sacral region it is 
said by some observers to correspond to the “sacral nucleus of Stilling,” while 
in the cervical region it begins in the dog at the 2d cervical nerve, forming the 
cervical nucleus, being continued above into the nuclei of the vagus and glosso- 
pharyngeal nerves. It is important to note that the vesicular column of Clarke 
(fig. 538, CCl) does not extend throughout the cord. A small group of cells 
exists opposite the 2d and 3d cervical nerve ; it extends as a continuous column 
from the 8th cervical to the 3d lumbar nerve, so that it is best developed in the 
thoracic region. 
[Connections of Clarke’s Column.—Gaskell showed that a large num- Sec. 359.] 
CELLS OF THE CORD. 
791 
ber of fine medullated nerve fibres leave the cord in the anterior roots of the 
dorsal nerves (§ 356), and as the distribution of Clarke’s column corresponds to 
this outflow of fine fibres, it was suggested that these fine medullated fibres—or, 
as Gaskell called them, leucenteric fibres, were connected with the cells of 
Clarke’s column. There is reason to believe, however, that this is not the case. 
The cells of Clarke’s column are large cells (90 p ; the smallest is 40 p in 
diameter). Some of the fibres which come from the lumbar and sacral nerves, 
and form part of the postero-external column, pass towards the cells of Clarke’s 
column, where they break up into a brush or pencil of fibrils, to form a fibrillar 
plexus or spongy network of fine nerve fibrillae around the cells of Clarke’s 
column {Mott). Cayal has also shown the existence of an enormous number 
of fibrils,—according to him, not forming a plexus around these cells. The 
cells are bipolar, and it is suggested by Mott that their distal connections are 
with fibres of the postero-external column as also that to them are transmitted 
various afferent impulses coming from viscera, and it may be from tendons and 
other parts, and that these impulses pass via the direct cerebellar tract to the 
cerebellum. In locomotor ataxia the fibrillar thicket of fibrils around these 
cells is degenerated. The average size of the cells at birth is about 25 /z-30 p, 
at two years 60 p, and in the adult 70 p. From the cells of Clarke’s column, 
there proceed large fibres, which run upwards, slightly forwards, and then 
outwards through the lateral column to reach the direct cerebellar tract of the 
same side, whence they proceed to the cerebellum. The direct cerebellar fibres 
of the cord do not degenerate unless Clarke’s column be injured. These cells 
appear to act as stations for afferent impulses between the peripheral nervous 
system and the cerebellum (Ross, Mott).~\ 
[The intermedio-lateral tract of cells is also best developed in the thoracic 
region (fig. 538, Tit). In the cervical region it fuses with the lateral group of 
cells in the anterior cornu. It cannot be traced in the lumbar region.] 
[The cells of the intermedio-lateral tract confined to the dorsal region are 
arranged in groups of eight to twelve bipolar cells, with their long axis vertical 
or more or less oblique. The smaller cells are about 20 p in diameter, and 
seem to be identical with the solitary cells of the posterior cornu, the larger 
ones are 30 p in diameter, and these cells attain their full size, or nearly so, at 
birth. Mott considers that these cells correspond in form and size with the 
cells of the vagus nucleus, and that these cells give origin to the fine medullated 
or leucenteric fibres that leave the cord by the anterior roots of the dorsal 
nerves (p. 818), i. e., to the splanchnic efferent fibres of the anterior roots of 
the dorsal nerves.] 
The multipolar ganglion cells are largest, and arranged in groups in the 
anterior horns of the gray matter (fig. 540—“ motor ganglionic cells ”). 
['['hey also occur in the lateral process and in the processus reticularis. It is to 
be noted that the cells become more branched as we proceed upwards amongst 
the vertebrata. These cells usually contain pigment-granules, and, according 
to Pierret, their size has a direct relation to the length of the nerve-fibre pro- 
ceeding from them ; so that they are largest in the lumbar enlargement, 
smaller in the cervical enlargement, and smallest in the dorsal region. Smaller 
spindle-shaped (“ sensory ”) cells occur in much smaller numbers in the gray 
matter of the posterior horn. The cells of Clarke’s column (fig. 539) are 
smaller (30-60 p) and are usually arranged with their long axis in the long axis 
of the cord. The processes are fewer, but one is generally directed towards the 
head, and some towards the caudal end of the body. They usually contain 
pigment, which is generally disposed towards the cerebral pole of the cell.] 
[In a longitudinal section of the cord (fig. 541), these cells are seen to be 
arranged in columns, the large multipolar cells in the anterior horn (m); in the 
same section are shown the longitudinal direction of the nerve-fibres in the GRAY MATTER OF THE CORD. 
[Sec. 359. 
792 
anterior (a) and posterior white columns (V), the horizontal direction of the 
fibres of the anterior and posterior nerve roots (b and/). 
[Outlying Cells of the Cord.—Beisso, Schiefferdecker, and more recently 
Sherrington, have shown that in certain situations in the anterior lateral and 
posterior columns of the mammalian cord, ganglionic cells lie outside the gray 
matter in the surrounding white substance. In the Alligator there is a remark- 
able group of ganglionic cells lying quite at the periphery of the antero-lateral 
column, and quite removed from the gray matter (.Berger, Gaskell); its sig- 
nificance is quite unknown.] 
The gray matter contains an exceedingly delicate fibrous thicket of the 
finest nerve-fibrils, which is produced by the repeated division of the protoplas- 
Fig- 539- 
Fig. 540. 
Fig. 539.—Nerve-cell from Clarke’s column (horse). The arrow indicates the cerebral end. 
Fig. 540.—Transverse section of the spinal cord (lower dorsal). A, L, P, anterior, lateral, 
and posterior columns; A.M.F., P.M.F., anterior and posterior median fissures; a,b,c, cells 
of the anterior horn; d, posterior cornu and substantia gelatinosa; e, central canal; f 
veins; root bundles; h, posterior root bundles; i, white commissure; j, gray 
commissure ; /, reticular formation. 
mic processes of the multipolar ganglionic cells. Many medullated nerve-fibres 
—chiefly of the fine variety—traverse and divide in the gray matter and become 
non-medullated. Many of them split up into terminal fibrils, branches of the 
axis cylinder. Some of them merely pass through the gray matter of the non- 
medullated fibres and terminate in the nervous network or thicket of the gray 
matter. Fibres pass from the gray matter of one side to that of the other 
through the commissures in front of and behind the central canal. 
[By means of Weigert’s method of staining medullated nerve-fibres (p. 671), 
it has been proven that numerous fine medullated nerve-fibres exist in the gray 
substance.] 
[The anterior root enters in several bundles of coarse fibres which diverge Sec. 359.] 
COURSE OF THE ROOT-FIBRES. 
793 
before they reach the gray matter. Most of the fibres end in the large motor 
Fig. 541.—Longitudinal section of the human spinal cord, a, anterior, c, posterior, d, lateral 
white columns; b, anterior, c, posterior nerve roots; f horizontal (pyramidal) fibres passing 
to ?n, cells of anterior cornu; n, oblique fibres of posterior root. Fig. 542. — Multipolar 
nerve-cell, from the anterior horn of the spinal cord, z, axis-cylinder process; y, branched 
processes. 
Fig. 541. 
Fig. 542. 
nerve-cells in the anterior cornu or 
its lateral process (fig. 543, a, b, c, 
d, e). But the fibres diverge in all 
directions, some of the fibres of the 
bundle nearest the middle line (3) 
end in the laterally placed cells (c) ; 
a part (4) crosses the anterior com- 
missure to end in cells on the opposite 
side (d). Some of them (6) run 
upwards to become connected with 
motor cells lying further up the cord. 
Some of the fibres present in the 
anterior roots, e.g., the vaso-motor 
and secretory fibres, appear not to be 
connected with the nerve-cells of the 
anterior cornu. Perhaps all the 
motor fibres for the skeletal muscles 
are so connected, so that each motor 
nerve-fibre is merely the prolonga- 
tion of the unbranched axis-cylinder 
process of a nerve-cell.] 
[The posterior root enters as a 
single bundle (fig. 533), composed 
of finer fibres intermixed with bun- 
dles of thicker ones.] 
[Two distinct bundles enter the 
cord. There is an outer lateral 
bundle, or outer radicular fibres, 
which curve into the longitudinal 
fibres, so that they are cut across in a transverse section, but they again take a 
F'g- 543- 
Scheme of the course of the fibres in the spinal 
cord. The longitudinal fibres are indicated by 
small circles, while the nerve-cells are black. [Sec. 359. 
794 
COURSE OF THE ROOT-FIBRES. 
horizontal course and enter the substantia gelatinosa. The finest fibres in the 
bundle are usually placed most laterally. Lying on the inner side of this is the 
larger bundle, constituting the inner radicular fibres of the median bundle. 
The lateral bundle divides into an intermediate or central bundle, and a 
small external lateral bundle (7). The small external lateral bundle consists of 
fine fibres, which ascend for a short distance in the cord, and form the poste- 
rior marginal zone or Lissauer’s zone (fig. 557). They enter the gray matter 
higher up and terminate in the cells of the gray matter of the posterior horn. 
The central fibres, which are coarse fibres (8 to 10), pass into the substantia 
gelatinosa, where they divide into 
several strands, some of which 
pass into the central part of the 
gray matter (10), while others (8) 
pass upwards and downwards in a 
longitudinal direction, and form 
the “longitudinal bundles of the 
posterior horn.’’ Some of the 
fibres (9) perhaps end in the 
nerve-cells in the posterior 
cornu. The inner median bun- 
Fig. 544- 
Longitudinal section of the spinal cord. 
a, white, b, gray matter; c, crystals of 
mercuric chloride. Prepared by Gol- 
gi’s mercuric chloride method; X 80. 
Fig. 545- 
Isolated connective-tissue corpuscle or “ glia-cell ” 
from the human spinal cord; X 800. 
die or internal radicular fasciculus (n to 14), composed of comparatively 
coarse fibres, sweeps through the postero-external column—hence this column is 
also called the posterior root-zone—and, after running a longitudinal course in 
the white matter, enters the gray substance of the posterior cornu. Some 
fibres (11) pass to the small fusiform cells (g) ; and others (13) pass to be con- 
nected with the cells of Clarke’s column (/i), when it is present. From the 
cells of Clarke’s column, fibres seem to pass to the direct cerebellar tract (20). 
Some of the fibres (12) pass into the posterior gray commissure, to reach the 
opposite side. This so far only accounts for a part of the fibres. Some of 
them (8 to 10) are concerned in the formation of the fine nerve thicket in the 
gray matter, whereby, perhaps, they become connected with the cells in the 
anterior cornu. It is asserted that some of the fibres (14) ultimately pass into 
Goll’s column. Many of the fibres in the posterior root have been proved to 
be directly connected with nerve-cells, e.g., in Petromyzon by Freund, and in 
the Proteus by Klaussner.] 
[Size of Nerve-Cells and Nerve-Fibres.—There is reason to believe 
that the size of nerve-fibres bears a relation to the size of the nerve-cell from Sec. 359.] 
NEUROGLIA. 
795 
which it arises. It has been suggested by Schwalbe that nerve-fibres which run 
a long course are larger than those running a short course. This is not invari- 
ably the case (p. 671).] 
Neuroglia.—The connective-tissue of the spinal cord arises in part 
from the pia mater and passes into the white matter, carrying with it blood- 
vessels, and forming septa, which separate the nerve-fibres into bundles. [The 
connective-tissue of the central nervous system is so far peculiar, that the inter- 
cellular substance is reduced to a minimum. It consists of a reticulated con- 
nective-tissue composed of fine fibres, which form a network. Fig. 544 shows 
one of the cells, “ glia-cells ” or “ Deiter’s cells,” isolated. It consists of 
a small, granular, nucleated body, with numerous excessively fine, slightly 
branched, stiff processes. The processes form a sustentacular tissue for the 
nerve-fibres and blood-vessels. The arrangement and distribution of these 
cells is best seen in sections of a cord hardened by Golgi’s method in corrosive 
sublimate solution (fig. 545). In some situations, e. g., the white matter of the 
cerebrum and cerebellum, the cells are smaller and more angular, and the pro- 
cesses are often connected with the outer coat of the blood-vessels. On the 
whole, the connective-tissue is much finer in the brain than in the cord. 
Chemically, these glia-cells consist of neuro-keratin, and they seem to be of 
epiblastic origin, thus differing from ordinary connective-tissue, which is meso- 
blastic in origin.] The central canal is surrounded with a denser layer of this 
tissue, known as the “ central ependyma,” which stains deeply with carmine, 
and is very like the substantia gelatinosa in its structure (p. 789). We must 
distinguish from this form of connective-tissue that special form in 
the gray matter to which Virchow gave the name of neuroglia. It is 
specially adapted to fill up the spaces left by the other elements, and without 
interfering with the exchange of fluids 
serves to hold the elements together. 
It is an excessively finely granular 
ground-substance in the gray matter. 
It is also an intercellular substance, but 
in the adult the cells to which it owes 
its origin are no longer to be found. It 
is doubtful, from its chemical nature, 
Fig. 546. 
*ig- 547' 
Fig. 546.— Semi-diagrammatic arrangement of the arteries in the spinal cord. Spa, anterior 
spinal; s, sulcine artery; sc, sulco-commissural; an, its anastomosing branch; cl, to 
Clarke’s column; Fp, posterior fissure; ra, rp, branches along anterior and posterior roots; 
cp, for post, cornu ; if, interfunicular; la, Im, Ip, anterior, median, and posterior lateral. 
Fig. 547.—Injected blood-vessels of the spinal cord. 796 
[Sec. 359. 
BLOOD-VESSELS OF THE CORD. 
if it is really to be reckoned along with the connective-tissues. It seems to be 
rather a tissue suigeneris, belonging to the nervous system, and it is present in 
very small amount. It seems to consist of neuro-keratin, and the cells are 
epiblastic in origin, being derived from the cells of the epiblast.] The neu- 
roglia is also abundant on the sides and apex of the posterior horns, where it 
is called the gelatinous substance of Rolando. 
[Blood-Vessels.—The spinal cord is partly supplied with blood by arteries 
from the vertebrals, and partly by branches of the intercostal, lumbar, and 
sacral arteries, which reach it through the intervertebral foramina, and pass to 
the cord along the anterior and posterior roots.] 
[Blood-Vessels.—The anterior median artery (or anterior spinal) (fig. 546) gives off 
branches, which dip into the fissure of the same name, pass to its base, and, after perforating the 
anterior commissure, divide into two branches, one for each mass of gray matter, and each branch 
in turn splits into three, which supply part of the anterior median, and posterior gray matter. 
The arteries lying in the sulci are called arteriae sulci (s) by Adamkiewicz. In the gray 
Fig. 548.—Longitudinal section of the cord in the cervical region of a sheep’s embryo, 22 cm. 
long, to show the division of the posterior nerve-fibres after entering the cord. Fig. 549.— 
Lateral column of a new-born rabbit; c, collateral fibres; el, bending round of the longi- 
tudinal fibres to end in the gray matter; n, axis-cylinder process of a nerve-cell bending in 
amongst the longitudinal fibres of the white column. 
Fig. 548. 
Fig. 549- 
matter there is usually a special branch to Clarke’s column (el). The vaso-coronary arteries 
include all those arterial branches which proceed from the periphery into the white matter; the 
finer branches pass only into the white matter, but the larger into the gray substance. The 
largest branch is the artery of the posterior fissure (Fp), which passes along the posterior septum 
and reaches almost to the commissure, giving branches in its course. There is a large artery 
between the column of Goll and the postero-external column, viz., the interfunicular artery (if). 
Arteries enter along the anterior and posterior roots (ra, rp). There are also a median lateral 
artery (Im), and an anterior and posterior lateral (Ip, la), which enter the lateral column. The gen- 
eral result is that the gray matter is much more vascular than the white, as is shown in fig. 547. 
Some small vessels come from the pia and send branches to the white matter, and unbranched 
arteries to the gray matter, where they form a capillary plexus. The blood-vessels are sur- 
rounded by perivascular lymph-spaces (His). With regard to the blood-vessels supplying 
the cord as a whole, Moxon has pointed out that, owing to the cord not being as long as the 
vertebral canal, the lower nerves have to run down within the vertebral canal, before they emerge 
from the appropriate intervertebral foramina. As re-enforcing arteries enter the cord along 
the course of these nerves, necessarily the branches entering along the course of the lumbar and Sec. 359.] 
RECENT RESEARCHES ON THE CORD. 
797 
lower dorsal nerves are long, and this, together with their small size, offers considerable resist- 
ance to the blood-stream. Hence, perhaps, the reason why the lower part of the cord is so apt 
to be affected by various pathological conditions.] 
[Recent Researches of Golgi, Ram6n y Cayal and Kolliker.— 
Golgi’s method was adopted by all these observers, viz., prolonged steeping 
of the nerve-centres in a dilute solution of silver nitrate, after previous harden- 
ing in Muller’s fluid, or other fluid containing a chromium salt, or by the 
rapid hardening method—viz., a mixture of potassium bichromate and osmic 
acid. The nerve-cells and the axis-cylinders become black; but all the cells 
or axis-cylinders in any piece of tissue are by no means affected by the reagent. 
Ramon y Cayal made the great advance of using the embryonic nerve-centres, 
and results have been obtained on them that are not so easily obtained in the 
adult. The axis-cylinders stain best before the myelin is developed, and hence 
the reason why embryonic nerve-centres stain so well before the myelin covers 
the axis-cylinders.] 
[The above description of the cord is based on a study of the cord prepared by the ordinary 
methods, but Golgi’s method reveals further complications in the structure of the cord, some of 
which are here noted. The sensory nerve-fibres on entering the white matter divide into an 
ascending and a descending fibre, which run longitudinally in the posterior column and in the 
posterior marginal zone, just superficial to the substantia gelatinosa (fig. 548, S). The longi- 
tudinal fibres have been traced for a distance of 4-6 cm., but a large number of them bend 
round and enter the gray matter, and end free in fine branches, without forming any connections 
with nerve-cells (fig. 550). All the sensory or afferent longitudinal fibres in the posterior 
column give off at nearly a right angle fibres called by Ramon y Cayal, who discovered them, 
collateral fibres, which penetrate into the gray matter, and run to all its parts, and split up into 
numerous fibrils and end free (figs. 549 c, /, 552). The free fibrillar terminations of these col- 
lateral fibres are specially numerous in the ventral portion of the substantia gelatinosa and Clarke’s 
column, and in the ventral and lateral parts of the 
anterior horns, to which pass numerous bundles of 
collateral fibres.] 
The nerve-fibres of the anterior root spring from 
large and small multipolar nerve cells from all parts 
Transverse section of the cervical enlargement of the cord of a new-born rabbit with the col- 
lateral fibres from all the columns of the cord, and the anterior and posterior commissures, 
ca and cp. Fig. 551.—A nerve-cell in the anterior cornu of the lumbar region of an ox- 
embryo, 20 cm. long; n, axis-cylinder process, passing at n' into a longitudinal fibre of 
the anterior column; n", much branched lateral processes of n. All prepared by the silver 
nitrate method of Golgi. 
t'g- 55°- 
Fig- 55 *• 
of the anterior cornu (fig. 552), but it appears that the axis-cylinder process of the nerve-cell 
gives off a few lateral branches (fig. 551). 
The anterior and lateral columns consist in part of fibres which spring from nerve-cells in 798 
RECENT RESEARCHES ON THE CORD. 
[Sec. 359. 
all regions of the gray matter (fig. 550). These cells give off from their axis-cylinder or nervous 
process numerous lateral processes, which end free in the gray matter. Most, or perhaps all, of 
the fibres in the anterior and lateral columns give off collateral fibres, which enter the gray 
matter, especially the anterior horns and the anterior part of the posterior cornu, where they 
end free. The longitudinal fibres of these two columns usually bend at a right angle and end 
free in the gray matter. 
It is remarkable that all the collateral fibres and all the lateral branches of the nervous pro- 
cess of the nerve-cells, as well as those longitudinal fibres of the posterior, lateral, and anterior 
columns that enter the gray matter, break up into a greater or less number of branches, and end 
at last in a fine tuft of fibrils which surround the nerve-cells, without, however, forming connec- 
tions with the nerve-cells or the fibrils anastomosing amongst themselves.] 
[Three kinds of nerve-cells have been distinguished:— 
(1) Large motor cells; (2) cells which give nerve-fibres to the columns of the cord ; and (3) 
cells with a nervous process which does not pass out of the gray matter, but divides uniformly 
in the gray matter itself. The last variety of cell occurs only in the posterior cornu. The pro- 
toplasmic processes of all the nerve-cells branch and are continued sometimes as enormously 
long processes in all directions; sometimes they pass into the white matter, but they never 
anastomose, and never give rise to a nerve-fibre (figs. 551, 552).] 
[The anterior commissure contains— 
(1) Nervous processes from cells in all parts of the gray matter, and after they decussate are 
continued as longitu- 
dinal fibres of the an- 
tero-lateral columns. 
(2) Decussating col- 
lateral fibres from the 
anterior and lateral 
columns. 
(3) Decussating pro- 
toplasmic processes of 
some of the median 
cells of the anterior 
cornua. 
The posterior com- 
missure contains— 
(1) Decussating col- 
lateral fibres of the pos- 
terior columns, and 
perhaps also from the 
posterior part of the 
iateral columns, as well 
as some decussating pro- 
toplasmic nervous pro- 
cesses from some of the 
cells of the posterior 
cornu and gelatinous 
substance.] 
[The following fibres 
are directly connected 
with nerve-cells, and 
must be influenced by 
the latter:— 
(1) The motor fibres 
in the anterior 
roots. 
(2) Many fibres in the 
lateral and an- 
terior columns.] 
[In the following instances, however, there is no direct continuity between fibres and cells, so 
that they can only act on each other by contact:— 
(1) The sensory fibres that end free in the cord. 
(2) The free terminations in the cord of the collateral fibres from all the columns. 
(3) Many of the longitudinal fibres of the antero-lateral column, which bend round and end 
free in the gray matter. 
(4) The free terminations of many lateral processes of the nervous or axis-cylinder process ot 
many nerve-cells of the gray matter. 
Transverse section of the spinal cord in the thoracic region in an em- 
bryo fowl (9th day of incubation). A, anterior, and P, posterior 
root; C, axis-cylinder of a motor nerve-cell; D, intra medullary part 
of the posterior root; e, origin of a collateral branch, which ramifies 
as f S> terminal ramifications of the collateral fibres; d, final bifur- 
cation ; h, bipolar ganglionic cells; i, a unipolar nerve-cell like those 
in mammals [Ramon y Cayal). 
TTg. 552. Sec. 359.] 
CONDUCTING PATHS IN THE CORD. 
799 
(5) The free terminations of the branched processes of certain cells of the posterior horn, 
that end in toto in the gray matter.] 
[The glia-cells are developed from the elements of the original medullary plate, and are 
divided into primary and secondary. The former are represented by the epithelium lining 
the central canal. The others arise in the gray and white matter and appear to be epiblastic in 
origin.] 
[The foregoing account represents Kolliker’s resumt of his own researches on embryo 
mammals, which are practically a confirmation of the prior observations of Golgi and Ramon y 
Cayal, but more especially of the latter. It is obvious that the statements here made that the 
protoplasmic processes of nerve-cells do not anastomose, and that many white nerve-fibres termi- 
nate in the cord in free endings, without forming direct anatomical continuity with nerve-cells, 
must profoundly modify our conceptions and theories regarding the mode of action of these 
structures. It would seem that in certain cases an impulse reaching the gray matter through 
such nerve-fibres must act on nerve cells merely as the result of contact between the nerve- 
fibrils and the nerve-cell, and not in virtue of actual anatomical continuity.] 
[Functions of the Spinal Cord.—(i) It is a great conducting me- 
dium, conducting impulses upwards and downwards, and within itself from 
side to side ; (2) the great reflex centre, or rather a series of so-called 
centres; (3) impulses originate within it, i. e., its automatic functions.] 
Conducting Systems.—The whole of the longitudinal fibres of the spinal 
cord may be arranged systematically in special bundles,according to their function. 
[Methods of ascertaining Conducting Paths in the Cord.—The 
course of the fibres and their division into so-called systems has been ascer- 
tained partly by anatomical and embryological, partly by physiological 
and pathological means. Apart from experimental methods, such as dividing 
one column of the cord and observing the 
results, we have the following methods of 
investigation : (1) Turck found that injury 
or disease of certain parts of the brain was 
followed by a degeneration downwards, or 
secondary descending degeneration 
of certain of the nerve-fibres connected 
with the seat of injury, i. e., they were 
separated from their trophic centres and 
underwent degeneration. (2) P. Schiefer- 
decker found also, after section of the cord, 
that above the level of the section, certain 
definite tracts of white matter underwent 
degeneration [thus showing that certain 
tracts had their trophic centre below ; this 
constitutes secondary ascending de- 
generation]. (3) Gudden’s Method.— 
He showed, as regards the brain, that ex- 
cision of a sense-organ in a young growing 
animal was followed by atrophy of the 
nerve-fibres and some other parts con- 
nected with it. Thus, the optic nerve and 
anterior corpora quadrigemina atrophy after 
excision of the eyeball in young rabbits.] (4) Embryological.—Flechsig 
showed that the fibres of the cord [and the brain also] during development 
became covered with myelin at different periods, those fibres becoming medul- 
lated latest which had the longest course. By a combination of these methods 
the following tracts of fibres have been mapped out:— 
Conducting Systems of Fibres.—1. In the anterior column lie (a) the 
uncrossed, anterior, or direct pyramidal tract [also called the Column of 
Turck] ; and external to it is (b) the anterior ground bundle, or anterior 
radicular zone (fig. 553). [The direct pyramidal tract varies in size, and ii 
Scheme of the conducting paths in the 
spinal cord at the 3d dorsal nerve. 
The black part is the gray matter. V, 
anterior, hw, posterior root; a, di- 
rect, andg, crossed, pyramidal tracts; 
b, anterior column ground bundle; 
c, Goll’s column ; d, postero-external 
column; e and f, mixed lateral paths; 
h, direct cerebellar tracts. 
F'g- 553- 800 
PYRAMIDAL TRACTS. 
[Sec. 359. 
generally extends downwards in the cord to about the middle of the dorsal 
region, diminishing steadily in its course. It is called direct pyramidal tract 
because, unlike the rest of the pyramidal tract, it does not decussate in the 
bulb. It is found only in man and the monkey, is very variable in size, and 
forms 10 to 20 per cent, of the total pyramidal tract. We do not know exactly 
how these fibres end, whether they cross to the opposite side, or remain on the 
same side, but most probably most of them pass through the anterior commis- 
sure to the gray matter of the opposite side.] 
2. In the posterior column we distinguish (c) Goll’s column, or the 
postero-median (postero-internal) column ; and (d) the outer root zone, 
or the funiculus cuneatus, or Burdach's column, or the posterior radicular 
zone, or the postero-external column (figs. 553, 557). 
Ill 
Dorsal 
Nerve. 
I 
Cervical 
Nerve. 
VI 
Dorsal 
Nerve. 
Ill 
Cervical 
Nerve. 
XII 
Dorsal 
Nerve. 
' VI 
Cervical 
Nerve. 
IV 
Lumbar 
Nerve. 
F'g- 554- 
Scheme of the distribution of the chief paths in the spinal cord. 1 pvs, direct pyramidal tract; 
2 psb, crossed pyramidal tracts; 3 ksb, direct cerebellar tract; 4 aks, postero-external 
column; 5 iks, postero-internal column, or Golfs column; 6 vsr, anterior mixed zone. X 2. 
3. In the lateral column are (e) the antero-lateral tract and (/) the 
lateral mixed paths, or lateral limiting tract [this tract is still further sub- 
divided, p. 805], (g) the lateral or crossed pyramidal tract, and (h) the 
direct cerebellar tract. 
[All the impulses from the central convolutions or motor areas of the cere- 
brum, by means of which voluntary movements (§ 365) are executed, are 
conducted by the pyramidal tracts (figs. 553 a, g, 554, 557). The fibres 
in these tracts descending from the central convolutions—i.e., the motor- 
areas—pass through the white matter of the cerebrum, converging like the rays 
of a fan to the internal capsule, where they lie in the knee and anterior two- 
thirds of its posterior segment (the fibres for the face at the knee, and behind 
this in order those for the arm and leg), they then enter the middle-third of 
the crusta (fig. 62S,Py), pass through the pons into the anterior pyramids of Sec. 359.] 
TRACTS OF THE CORD. 
801 
the medulla oblongata, where the great mass crosses over to the lateral column 
of the opposite side of the cord (crossed pyramidal tract), a small part 
descending in the cord on the same side as the direct pyramidal tract, a. 
The crossed pyramidal tract lies external to the posterior half of the gray 
matter in the lateral column (fig. 553, g), and it extends throughout the length 
of the cord. It contains nerve-fibres of all sizes. In the greater part of its 
course it is separated from the surface by the direct cerebellar tract, but where 
the latter lies further forward, as at the third cervical.segment and lower dorsal 
region, its posterior surface reaches the surface, while from the last dorsal seg- 
ment, throughout the lumbar region, it comes quite to the surface, as the direct 
cerebellar tract ceases at the first lumbar vertebra. The pyramidal tract dimin- 
ishes from above downwards, and its fibres pass into the gray matter of the an- 
terior cornu, and in all probability they subdivide to form fine fibrils, which come 
into relation with the dense thicket of fine fibrils produced by the subdivision 
of the processes of the multipolar nerve-cells. At least they come into intimate 
relation—(direct union or contact?)—with the nervous mechanism in the ante- 
rior cornua of the gray matter of the cord. From each multipolar nerve-cell a 
nerve-fibre proceeds and passes into the anterior root. The facts connected 
with the descending degeneration of this tract seem to indicate that in the 
cord some of the fibres cross and descend in the opposite side of the cord. 
These are called the “ recrossed fibres ’’ (Sherrington). It would seem that 
the fibres of the direct pyramidal tract, as they descend in the cord, cross to 
the opposite side of the cord before they become continuous with the nerve- 
cells of the anterior cornu. They perhaps cross via the anterior white 
commissure.] 
[The direct cerebellar tract (figs. 553, 554, 557 h), begins about the first 
lumbar nerve, and increases in thickness from below upwards, but many of 
its fibres enter it at the first lumbar and lowest dorsal nerves. It is obvious, 
therefore, that the tract receives fibres as it passes upwards. It forms a thin 
layer on the surface of the cord. Its fibres, which are broad and coarse, very 
probably arise in the cells of Clarke’s column (p. 791). As Clarke’s column is 
connected with some of the fibres of the posterior root (for the trunk of the 
body), it follows that this tract connects certain parts of the posterior roots with 
the cerebellum. The fibres pass up through the cord and restiform body to the 
cerebellum. When it is divided, it degenerates upwards, so that it is supposed 
to conduct impulses in a centripetal direction. The degeneration, however, 
diminishes as we trace it upwards. This means that all the fibres do not neces- 
sarily ascend to the cerebellum. The tract receives new fibres as we trace it up- 
wards, but some of the fibres pass to other parts of the cord as it is traced up- 
wards, while others go direct to the cerebellum. Degeneration in it cannot be 
caused by injury or section of the nerves or nerve-roots; the cord itself must be 
injured ; so that it is evident that the fibres of the tract do not come directly 
from the posterior root. Their trophic centre seems to be in Clarke’s column 
(P- 791)-] 
The anterior (fig. 553, <?) and lateral paths (/) and the anterior ground bun- 
dle represent the channels which connect the gray matter of the spinal cord 
and that of the medulla oblongata ; they represent the channels for reflex effects, 
and they also contain those fibres which are the direct continuation of the 
anterior spinal nerve-roots, which enter the cord at different levels and pene- 
trate into the gray matter. In e and f there are some sensory paths. Lastly, 
c unites the posterior roots with the gray nuclei of the funiculi graciles of the 
medulla oblongata ; d connects some of the posterior nerve-roots through the 
restiform body with the vermiform process of the cerebellum (Flechsig). The 
direction of conduction in the posterior columns, which are continuations 802 
[Sec. 359. 
DEGENERATION TRACTS AND NUTRITIVE CENTRES. 
of some of the fibres of the posterior roots, is upwards, as part of them degen- 
erate upwards after section of the posterior root. Of the fibres of each pos- 
terior root, some pass directly into the posterior horn, another part ascends in 
the posterior column of the same side, and gradually as it ascends it comes 
nearer the posterior median fissure. Some of these fibres enter the gray matter 
of the posterior horn at a higher level. The fibres of the posterior columns 
run upwards as far as the interolivary layer and the decussation of the pyramids, 
where they seem to end, or at least form connections with the nerve-cells of the 
funiculi graciles [clava] and cuneati [triangular nucleus]. A small part as 
arcuate fibres join the restiform body, and thus the cerebellum is connected 
with the posterior columns. 
Further, the transverse sectional area of the direct and crossed pyramidal 
tracts (fig. 554), the lateral cerebellar tract, and Goll’s column gradually dimin- 
ish from above downwards; they serve to connect intracranial central parts 
with the ganglionic centres distributed along the spinal cord. The anterior 
root bundle, the funiculus cuneatus, and the anterior mixed lateral tracts vary 
in diameter at different parts of the cord, corresponding to the number of nerve- 
roots. It has been concluded from this that these tracts serve to connect the 
gray matter at different levels in the cord with each other, and ultimately with 
the medulla oblongata, so that they do not pass directly to the higher parts of 
the brain (fig. 536). 
Trophic Centres of the Conducting Paths.—Ttirck observed that the 
destruction of certain parts of the brain caused a secondary degeneration of 
certain parts of the cord, corresponding to the parts calledpyraitiidal tractsby 
Flechsig (fig. 554). P. Schieferdecker found the same effects below where he 
divided the spinal cord in a dog. Hence it is concluded that the nutritive or 
trophic centre of the pyramidal tracts lies in the cerebrum. [Section of the 
cord, or an injury compressing the cord, besides giving rise to loss of certain 
functions (p. 819), results in structural changes in certain limited areas of the 
cord itself.] 
[All that is meant by the terms descending and ascending degeneration is, that 
after section or injury of the cord, or certain parts of the brain, definite areas 
of the white matter of the cord above 
and below the seat of the lesion un- 
dergo degeneration. It does not 
mean that the degeneration proceeds 
at a given rate upwards or downwards 
from the seat of the lesion, for it ap- 
pears that the degeneration may be 
quite as far advanced at a distance 
from the lesion as near it, so that, 
perhaps, the degenerations in the 
cord are not exactly identical with 
those that occur in a nerve after it is 
divided. In the cord the axis- 
cylinders break up and are absorbed, 
and we know that in the cord nerve- 
fibres have no primitive sheath, and 
there are no nuclei, i.e., nerve-cor- 
puscles, to proliferate, as is the case in the Wallerian degeneration of a nerve.] 
[The tracts which in each half of the cord undergo descending degener- 
ation are (figs. 555,557):— 
1. The crossed pyramidal tract. 
2. The direct pyramidal tract. 
Fig. 555.—Ascending degeneration in the cervical 
enlargement. GC, Goll’s column, degenerated 
on both sides, and to a less degree the cerebellar 
tract, C T, and Gower’s tract, G T. x2- Fig. 
556.—Descending degeneration after a lesion on 
the left side of the brain. The anterior pyra- 
midal tract of the left side and the crossed 
pyramidal tract of the opposite side are degen- 
erated. x 2- 
Fig. 555- 
Fig- 550- Sec. 359.] 
803 
DEGENERATION TRACTS. 
3. The antero-lateral descending tract. 
4. The descending comma tract. 
The tracts undergoing ascending degeneration are (figs. 556, 557) :— 
1. Goll’s column or posterior-median tract. 
2. The cerebellar tract. 
3. The ascending antero-lateral tract or tract of Gowers.] 
Below the section, after a time, the direct and crossed pyramidal tracts 
(figs. 557, 558, 1, 1', 2, 2') degenerate downwards, i.e., they undergo descend- 
ing degeneration, because they are cut off from their nutritive or trophic 
centres, which are situated above in the pyramidal cells of the motor areas of 
the brain (§ 378). [It is important to note that almost all the fibres in these 
tracts degenerate, so that these tracts are sharply defined after they have de- 
generated.] The trophic centres for the fibres of the anterior root lies in the 
multipolar nerve-cells of the anterior cornu of the gray matter of the cord. 
[These are the most conspicuous descending tracts, but there is also a very 
diffuse area, some of the fibres only in which undergo descending degeneration. 
It lies in the antero-lateral column, and is called the antero-lateral de- 
scending tract. It stretches as a somewhat narrow curved area from the 
crossed pyramidal tract towards the anterior column (fig. 557), and internal to 
the ascending tract of the same name. Only a limited number of the fibres in 
this area degenerate, many remaining unchanged. The Small narrow descend- 
ing comma tract (fig. 557), which lies in the postero-external column, can 
hardly be called a tract, as it does not extend along the length of the cord after 
section of the latter ; in fact, it only extends a short distance, and it may repre- 
sent some fibres of the posterior root which take a descending course after 
entering the cord.] 
[Ascending Tracts.—After section of the spinal cord, Goll’s column and 
the direct cerebellar tracts and the tract of Gowers degenerate upwards, i. e., 
they undergo ascending degeneration. If the posterior columns even be 
divided, Goll’s column or the postero-median column degenerates 
upwards towards the medulla oblongata, and the degeneration ends in the pos- 
terior pyramidal nucleus or clava. Goll’s column extends along the whole 
length of the cord, varying, however, in size at different levels. It consists of 
small fibres of a nearly uniform size (fig. 556). The same result occurs if the 
posterior nerve-roots of the cauda equina, or other posterior nerve-roots, be 
injured. Hence fibres seem to pass from the posterior root into these columns, 
and the nerve-cells in the clava must also have an important relation to these 
nerve-fibres and the parts whence they are derived. The postero-external 
column remains undegenerated, so that there is a very sharp distinction between 
the two parts of the posterior column. As Goll’s column degenerates upwards, 
it points to its fibres conducting impulses in a centripetal direction, and to the 
nutritive centre for its nerve-fibres being below. The trophic centre is probably 
in the spinal ganglion of the posterior root.] 
[It is a most important fact that ascending degeneration occurs in Goll’s 
column after section of the posterior roots of any of the spinal nerves. Sup- 
pose the lower two or three dorsal posterior roots to be divided, the degenera- 
tion proceeds centripetally along the nerve-roots to the cord, and can be traced 
into the postero-external column for a short distance upward in this column— 
as the zone of Lissauer—but at a certain distance above the entrance of the 
nerve-roots no degeneration is found in the postero-external column, while now 
the degenerated fibres can be traced in the postero-internal or Goll’s column, 
and some of the degenerated fibres—not all—can be traced up to the bulb. 
The degeneration is confined to the side in which the nerve-roots are divided. 
This means that fibres of the posterior root enter the cord, run for a short dis- [Sec. 359. 
804 
DEGENERATION TRACTS. 
tance in the postero-external zone, and in Lissauer’s zone; they then enter 
Goll’s column, and some of them pass up to the bulb, while others enter the 
Scheme showing the degeneration tracts, and the paths that do not undergo degeneration in the 
cord. AMF, anterior median fissure; DPT and CPT, direct and crossed pyramidal tracts; 
AR and PR, anterior and posterior roots; AAL and DAL, ascending and descending 
antero-lateral tracts; CT, cerebellar tract; D, comma-shaped tract; PMZ, posterior 
marginal zone; PEC, postero-external column. The parts left white do not undergo 
degeneration. 
Fig- 557- 
gray matter to form connections with its nerve-cells. The fibres proceeding from 
the several posterior nerve- 
roots,and which pass through 
Goll’s column to the bulb, 
occupy a definite position in 
this column. Those fibres 
which arise from the sacral 
nerves lie near the middle 
line dorsally, while those 
from the lumbar region lie 
near the middle line, but 
are placed ventrally, while 
those from the dorsal region 
are in front of the lumbar 
area and extend laterally, 
and are nearer the commis- 
sure of the cord.] 
[The direct cerebellar 
tract (fig. 557), also an 
elongated curved tract of 
fibres lying in the dorsal 
part of the cord and super- 
ficial to the crossed pyra- 
midal tract, also undergoes 
ascending degeneration if 
the cord be divided at any level above the junction of the dorsal and lumbar region. 
F'g- 558. 
Transverse section of the spinal cord, showing some of the 
secondary degeneration tracts. AR, anterior, TR, pos- 
terior root; i, i' (CPT), region of the crossed pyramidal 
tract; 2 2/ (DPT) PEC, postero-external column; LC, 
lateral column. Sec. 359.] 
SPINAL REFLEXES. 
805 
This tract appears to begin in the upper lumbar region, about the level of the first 
lumbar nerve, and it appears to be absent in the lower lumbar and sacral regions. 
At least, section of the cord in these regions is not followed by degeneration in 
the cerebellar tract. The tract increases in size from below upwards, and the 
degeneration can be traced through the restiform body into the cerebellum. 
The fibres composing this tract are mostly all large, coarse, or broad fibres, and 
it is suggested that their trophic centre lies in the cells of Clarke’s column (p. 
791).. It is'important to note that degeneration of this tract follows only 
when the cord itself is divided, and not when the posterior nerve-roots 
are cut.] 
[The ascending antero-lateral tract or tract of Gowers also under- 
goes ascending degeneration, but only after injury of the cord, not of the nerve- 
roots (figs. 556, 557). It lies superficially on the anterior aspect of the lateral 
column (fig. 557), and extends along the whole length of the cord. It fills up 
the area superficial to the crossed pyramidal, cerebellar, and descending antero- 
lateral tracts. All the fibres in this area do not degenerate. The degenerate 
ones are always intermixed with a considerable number of normal fibres. The 
nerve-fibres which compose this tract are intermediate in size between the large 
fibres of the cerebellar tracts and the fine fibres of Goll’s column. By some 
it is said to pass to the cerebellum, and to be merely an outlying part of the 
cerebellar tract. Its fibres are perhaps derived from certain cells in the 
gray matter of the cord in which some of the fibres of the posterior root 
terminate.] 
[Areas which do not degenerate.—Even when we have accounted for the 
foregoing fibres, there still remains considerable areas of fibres which do not 
undergo degeneration either after section, injury, or disease of the cord. This 
area includes the anterior ground bundle or antero-external column, the pos- 
tero-external column, and a considerable part of the lateral column, forming 
an elongated area bounding the gray matter of its own half of the cord. It 
has been suggested that those fibres of the spinal cord which do not degen- 
erate after section of the cord are commissural in function, connecting gang- 
lionic cells with each other, and are, therefore, provided with a trophic centre 
at both ends. Of the above-named areas, the postero-external column is com- 
posed chiefly of fibres of the posterior root.] 
[To the posterior root also belongs a very small area of fibres lying on the 
posterior aspect of the tip of the posterior horn, and known as the posterior 
marginal zone or zone of Lissauer, which is composed of very fine fibres 
(fig- 557)-] 
Time of Development of the Spinal Tracts.—With regard to the time of development 
of the individual systems, Flechsig finds that the first-formed paths are those between the 
periphery and the central gray matter, especially the nei-ve-roots, i. e., they are the first to be 
covered with the myelin. Then fibres which connect the gray matter at different levels are 
formed—the fibres which connect the gray matter of the cord with the cerebellum, and also 
the former with the tegmentum of the cerebral peduncle. At last the fibres which connect the 
ganglia of the pedunculus cerebri, and perhaps also the gray matter of the cortex cerebri with 
the gray matter of the cord are formed. In cases of anencephalous foetuses, i. e., where the 
Cerebrum is absent, neither the pyramidal tracts nor the pyramids are developed. In the brain 
before birth, medullated nerve-fibres are formed in the paracentral, central, and occipital con- 
volutions, and in the island of Reil, and last of all in the frontal convolutions ffuczek). [At 
birth, all the tracts of the cord are medullated except the pyramidal tracts, so that in a section of 
the cord of a new-born child these tracts appear gray in the contrast to the other white tracts of 
the cord.] 
360. SPINAL REFLEXES.—By the term reflex movement is meant 
a movement caused by the stimulation of an afferent (sensory) nerve. The 806 
SPINAL REFLEXES. 
[Sec. 360. 
stimulus, on being applied to an afferent nerve, sets up a state of excitement 
(nervous impulse) in that nerve, which state of excitement is transmitted or 
conducted in a centripetal direction along the nerve to the centre (spinal cord 
in this case) ; where the nerve-cells represent the nerve-centre in the cord, 
the impulse is transferred to the motor, efferent or centrifugal channel. 
Three factors, therefore, are essential for a reflex motor act—a centripetal or 
afferent fibre, a transferring centre, a centrifugal or efferent fibre ; these 
together constitute a reflex arc (fig. 559). In a purely reflex act all voluntary 
activity is excluded. 
Reflex movements may be divided into the three following groups:— 
I. The simple or partial reflexes, which are characterized by the fact 
that stimulation of a sensory area discharges movement in one muscle only, or 
at least in one limited group of muscles. Example : Contact with the con- 
junctiva causes closure of the eyelids; the afferent nerve is the 5th and the 
efferent the 7th cranial nerve, and the centre lies in the gray matter of the 
medulla oblongata. 
II. The extensive inco-ordinate reflexes, or reflex spasms.—These 
movements occur in the form of clonic or tetanic contractions; individual 
Fig. 559.—Scheme of a reflex arc. S, skin; M, muscle; N, nerve-cell, with af, afferent, and 
ef, efferent fibres. Fig. 560.—Section of a spinal segment, showing a unilateral and crossed 
reflex act. A, anterior, and P, posterior surface; M, muscle; S, skin; G, ganglion. 
Fig- 559- 
Fig. 560. 
groups of muscles, or all the muscles of the body may be implicated. Causes : 
A reflex spasm depends upon a double cause—(a) Either the gray matter or 
the spinal cord is in a condition of exalted excitability, so that the nervous 
impulse, after having reached the centre, is easily transferred to the neighboring 
centres. This excessive excitability is produced by certain poisons, more 
especially by strychnin, brucia, caffein, atropin, nicotin, carbolic acid, etc. 
The slightest touch applied to an animal poisoned with strychnin is sufficient 
to throw the animal at once into spasms. Pathological conditions may cause a 
similar result; thus, there is excessive excitability in hydrophobia and tetanus. 
On the other hand, the central organ may be in such a condition that extensive 
reflexes cannot take place; thus, in the condition of apnoea, the spasms that 
occur in poisoning with strychnin do not take place (f. Rosenthal and Lenbe') ; 
this is brought about by the passive artificial respiratory movements stretching 
the cutaneous nerves of the chest and abdomen (§ 361, 3). The performance 
of other passive periodic movements in various parts of the body also produces 
a similar condition (.Buchheim). If the spinal cord be cooled very consider- 
ably, reflex spasms may not occur (Kunde). (b) Extensive reflex movements 
may also take place when the discharging stimulus is very strong. Examples Sec. 360.] 
SUMMATION OF STIMULI. 
807 
of this condition occur in man, thus— 
intense neuralgia may be accompanied 
by extensive spasmodic movements. 
[Fig. 561 shows the mechanism of simple and 
complex reflex movements. Suppose the skm 
to be stimulated at P; an impulse is sent to A 
and from it to a muscle 1 on the same side, re- 
sulting in a unilateral simple reflex movement— 
the resistance being less in this direction than in 
the other channels. If the impulse be stronger, 
or the transverse resistance in the cord dimin- 
ished, the impulse may pass to B, thence to 2, 
resulting in a symmetrical reflex movement on 
both sides. But if a very strong impulse reach 
the cord, or if the excitability of the gray matter 
be increased, e.g., by strychnin, the resistance to 
the diffusion of the impulse is diminished, and 
it passes upward to C and D, resulting in more 
complex movements—thus there is irradiation— 
or it may even affect the centres in the medulla 
oblongata, E, giving rise to general convulsive 
movements.] 
General spasms usually manifest themselves 
as “ extensor tetanus ” or “opisthotonos," 
because the extensors overcome the flexor mus- 
cles. Nerves which arise from the medulla 
oblongata may be excited through the stimulation 
of distant afferent nerves, without general spasms 
being produced. 
Strychnin is the most powerful reflex-produc- 
ing poison we possess, and it acts upon the gray 
matter of the spinal cord, [An animal poisoned 
with strychnin exhibits tetanic spasms on the 
application of the slightest stimulus. All the 
muscles become rigid, but the extensors overcome 
the flexors.] If the heart of a frog be ligatured, and the poison afterwards applied directly to 
the spinal cord, reflex spasms are produced, proving that strychnin acts upon the spinal cord. 
During the spasm the heart is arrested in diastole, owing to the stimulation of the vagus, 
while the arterial blood-pressure is greatly increased owing to stimulation of the central vaso- 
motor centres of the medulla oblongata and spinal cord. Mammals may die from asphyxia 
during the attack; and after large doses, death may occur, owing to paralysis of the spinal 
cord, due to the frequently recurring spasms. Fowls are unaffected by comparatively large doses. 
[We can prove that strychnin does not produce spasms by acting on the brain, muscle, or nerve. 
Destroy the brain of a frog, divide one sciatic nerve high up, and inject a small dose of strychnin 
into the dorsal lymph-sac; in a few minutes all the muscles of the body, except those supplied 
by the divided nerve, will be in spasms, showing that although the poisoned blood has circulated 
in the nerves and muscles of the leg, it does not act on them. Destroy the spinal cord, and the 
spasms cease at once.] 
Summation of Stimuli.—By this term is meant that a single weak stimulus, 
which in itself is incapable of discharging a reflex act, may, if repeated 
sufficiently often, produce this act. The single impulses are conducted to the 
spinal cord, in which the process of “ summation ” takes place. According to 
J. Rosenthal, 3 feeble stimuli per second are capable of producing this effect, 
although 16 stimuli per second are most effective. On increasing the number 
of stimuli per second, no further increase of the reflex act is possible. Other 
observers {Stirling, Ward) have found that stimuli, such as induction shocks, 
are active within much wider limits, e.g., from 0.05 to 0.4 second interval. W. 
Stirling has shown it to be extremely probable that all reflex acts are due to the 
repetition of impulses in the nerve-centres. 
[Strychnin interferes with the summation of stimuli, but the reflex excitability is so greatly ex- 
alted that a minimal stimulus is at the same time a maximal one.] 
Scheme of mode of propagation of reflex 
movements. P, skin ; A, B, C, D, motor 
cells in spinal cord ; I, 2, 3, 4, 5, muscles. 
(In the light of the recent results of Golgi 
and Cayal, the scheme is no longer valid.) 
Fig. 561. 808 
EXAMPLES OF REFLEX ACTIONS. 
[Sec. 360. 
Pfliiger’s Law of Reflex Actions.—(i) The reflex movement occurs on the same side on 
which the sensory nerve is stimulated; while only those muscles contract whose nerves arise from 
the same segment of the spinal cord. (2) If the reflex occur on the other side, only the corre- 
sponding muscles contract. (3) If the contractions be unequal upon the two sides, then the 
most vigorous contractions always occur on the side which is stimulated. (4) If the reflex 
excitement extend to other motor nerves, those nerves are always affected which lie in the 
direction of the medulla oblongata. Lastly, all the muscles of the body may be thrown into 
contraction. 
Crossed Reflexes.—There are exceptions to these rules If the region of the eye be irritated 
in a frog whose cerebrum is removed, there is frequently a reflex contraction in the hind limb of 
the opposite side (Luchsirtger, Langendorff). In beheaded tritons and tortoises, and in deeply 
narcotized dogs and cats, tickling one fore limb is frequently followed by a movement of the hind 
limb of the opposite side (Luchsinger). This phenomenon is called a “ crossed reflex ” (fig. 
560). If the spinal cord be divided along the middle line throughout its entire extent, then of 
course the reflexes are confined to one side only (Schiff). 
III.—Extensive co-ordinated reflexes are due to stimulation of a sen- 
sory nerve, causing the discharge of complicated reflex movements in whole 
groups of different muscles, the movements being “ purposive ” in character, 
i.e., as if they were intended for a particular purpose. 
Methods.—The experiments are made upon cold-blooded animals (decapitated or pithed frogs, 
tortoises, or eels) or upon mammals. In the latter, artificial respiration is kept up, and the four 
arteries going to the head are ligatured, in order to eliminate the action of the brain (Sig. Mayer, 
Luchsinger). The reflexes of the lower part of the spinal cord may be studied on animals (or 
men), in cases where the spinal cord is divided transversely in the upper dorsal region. In such 
cases some time must elapse in order that the primary effect of the lesion (the so-called shock), 
which usually causes a diminution of the reflexes, may pass off. Very young mammals exhibit 
reflexes for a considerable time after they are beheaded. 
Examples:—1. The protective movements of pithed or decapitated 
frogs, [if a drop of a dilute acid be applied to the skin of such a frog, im- 
mediately it strives to get rid of the offending body, and it generally succeeds 
in doing so.] Similarly, it kicks against any fixed body pushed against it. 
These movements are so purposive in their character, and the actions of groups 
of muscles are so adjusted to perform a particular act, that Pfliiger regarded 
them as directed by and due to “ consciousness of the spinal cord.” If a flame 
be applied to the side or part of the body of an eel, the body is moved away 
from the flame. The tail of a decapitated triton, tortoise, newt, eel, or snake 
is directed towards a gentle stimulus, but if a violent stimulus is used, it is di- 
rected away from it (.Luchsinger). 
2. Goltz’s Croaking Experiment.—A pithed (male) frog, i.e., one with 
its cerebral lobes alone removed (or one with its eyes or ears destroyed— 
Langendorff), croaks every time the skin of its back or flanks is gently stroked. 
[Some male frogs, when held up by the finger and thumb immediately behind 
the fore legs, croak every time gentle pressure is made on their flank.] 
3. Goltz’s “ Embrace Experiment.”—During the breeding season in 
spring, the part of the body of the male frog between the skull and the fourth 
vertebra embraces every rigid object, which is brought into contact with, and 
gently stimulates, the skin over the sternum. 
In the intact animal, the exciting stimulus lies in the degree of filling of the male seminal organ 
( Tarchanoff). The reflex ceases at once on gently stimulating the optic lobes (Albertoni). 
4. In mammals (dogs), the following reflex acts are performed by the pos- 
terior part of the spinal cord, even after it is separated from the rest of the 
cord :—[In mammals, however, the cord takes a long time to recover from the 
shock of the operation, compared with the time required for this result in cold- 
blooded animals.] Scratching with the hind feet a part of the skin which has 
been tickled (just as in intact animals) ; the movements necessary for emptying 
the bladder and for defsecation, as well as those necessary for erection ; the Sec. 360.] 
INHIBITION OF REFLEXES. 
809 
movements necessary for parturition (Goliz, Freusberg and Gergens). Co-ordi- 
nated movements do not, as a rule, occur simultaneously in portions of the 
spinal cord lying widely apart after removal of the medulla oblongata. Accord- 
ing to Ludwig and Owsjannikow, the medulla oblongata perhaps contains a 
reflex organ of a higher order, which forms, as it were, a centre for combining, 
through the medium of the nerve-fibres, the various reflex provinces in the 
spinal cord. 
5. £o-ordinated reflexes may occur in man during sleep and during patho- 
logical comatose conditions. 
Most of the movements which we perform while we are awake, and which we execute uncon- 
sciously—or even when our psychical activities are concentrated upon some other object—really 
belong to the category of co-ordinated reflexes. Many complicated motor acts must first be 
learned—e.g., dancing, skating, riding, walking—before unconscious harmonious co ordinated 
reflexes can again be discharged. The co ordinated reflex movements of coughing, sneezing, and 
vomiting depend upon the spinal cord, together with the medulla oblongata. 
The following facts are also important:— 
1. Reflexes are more easily and more completely discharged when the 
specific end-organ of the afferent nerve is stimulated, than when the trunk 
of the nerve is stimulated in its course {MarshallHall, 1837). [Thus, by 
gently tickling the skin, it is easy to discharge a reflex act, while it requires a 
strong stimulus to be applied to an exposed sensory nerve in order to do so.] 
2. A stronger stimulus is required to discharge a reflex movement than for the 
direct stimulation of motor nerves. 
3. A movement produced reflexly is of shorter duration than the correspond- 
ing movement executed voluntarily. Further, the occurrence of the move- 
ment after the moment of stimulation is distinctly delayed. In the frog, a 
period nearly twelve times as long elapses before the occurrence of the con- 
traction than is occupied in the transmission of the impulse in the sensory and 
motor nerves (.Helmholtz, 1854). Thus, the spinal cord offers resistance to the 
transmission of impulses through it. 
The term “reflex time ” is applied to the time necessary in the cord itself for transferring the 
impulse from the afferent fibre to the nerve-cells of the cord, and from them to the efferent fibre. 
In the frog it is equal to 0.008 to 0.015 second. The time, however, is increased by almost one- 
third, if the impulse pass to the other side of the cord, or if it pass along the cord, e.g., from the 
sensory nerves of the anterior extremity to the motor roots of the posterior limb. Heat diminishes 
the reflex time and increases the reflex excitability. Lowering the temperature (winter frogs), 
as well as the reflex-exciting poisons already mentioned, lengthens the rejlex time, whilst the 
reflex excitability is simultaneously increased. Conversely, the reflex time diminishes as the 
strength of the stimulus increases, and it may even become of minimal duration (J. Rosenthal), 
The reflex time is determined by ascertaining the moment at which the sensory nerve is stimu- 
lated, and the subsequent contraction occurs. Deduct from this the time of latent stimulation 
(| 298, I), and the time necessary for the conduction of the impulse ($ 298) in the afferent and 
efferent nerves (v. Helmholtz, J. Rosenthal, Exner, Wundt). 
[Influence of Drugs.—The latent period and reflex time are influenced by a large num- 
ber of conditions. In a research, still unpublished, W. Stirling finds that the latent period may 
remain nearly constant in a pithed frog for nearly two days, when tested by Tiirck’s method. 
Sodic chloride does not influence the time, nor does sodic bromide or iodide. Potassic chloride, 
however, lengthens it enormously, or even abolishes reflex action after a very short time, and so 
do potassic bromide, ammonium chloride and bromide, chloral and croton-chloral. The lithia 
salts also lengthen the reflex time, or abolish the reflex act after a time.] 
361. INHIBITION OF THE REFLEXES.—Within the body 
there are mechanisms which can suppress or inhibit the discharge of reflexes, 
and they may therefore be termed mechanisms inhibiting the reflexes. 
These are :— 
1. Voluntary Inhibition.—Reflexes may be inhibited voluntarily, both 
in the region of the spinal cord and brain. Examples : Keeping the eyelids 
open when the eyeball is touched ; arrest of movement when the skin is tickled. INHIBITION OF REFLEXES. 
[Sec. 361. 
We must observe, however, that the suppression of reflexes is possible only up 
to a certain point. If the stimulus be strong, and repeated with sufficient fre- 
quency, the reflex impulse ultimately overcomes the voluntary effort. It is 
impossible to suppress those reflex movements which cannot at any time be 
performed voluntarily. Thus, erection, ejaculation, parturition, and the move- 
ments of the iris, are neither direct voluntary acts, nor can they, when they are 
excited reflexly, be suppressed by the will. 
2. Setschenow’s inhibitory centre is another cerebral apparatus, which 
in the frog is placed in the optic lobes. If the optic lobes be separated from 
the rest of the brain and spinal cord, by a section made below it, the reflex 
excitability is increased. If the lower divided surface of the optic lobes be 
stimulated with a crystal of common salt or blood, the reflex movements are 
suppressed. The same results obtain when only one side is operated on. 
Similar organs are supposed to be present in the corpora quadrigemina and 
medulla oblongata of the higher vertebrates. From i and 2 we may explain 
why reflex movements occur more regularly and more readily after separation 
of the brain from the spinal cord. 
[Quinine greatly diminishes the reflex excitability in the frog, but if the medulla oblongata 
be divided, the reflex excitability of the cord is restored. The depression is ascribed by Chaperon 
to the action of the quinine on Setschenow’s centres.] 
3. Strong stimulation of a sensory nerve inhibits reflex movements. 
The reflex does not take place if an afferent nerve be stimulated very power- 
fully ( Goltz, Lewissori). Examples : Suppressing a sneeze by friction of the 
nose [compressing the skin of the nose over the exit of the nasal nerve] ; sup- 
pression of the movements produced by tickling, by biting the tongue. Very 
violent stimulation may even suppress the co-ordinated reflex movements usually 
controlled by voluntary impulses. Violent pain of the abdominal organs 
(intestine, uterus, kidneys, bladder, or liver) may prevent a person from 
walking or even from standing. To the same category belongs the fact that 
persons fall down when internal organs richly supplied with nerves are injured, 
there being neither injury of the motor nerves nor loss of blood to account for 
the phenomenon. Excitement of the central organs through other centripetal 
channels (nerves of special sense, and those of the generative organs) diminishes 
the reflexes in other channels. 
4. It is important to note that in the suppression of reflexes, antagonistic muscles are often 
thrown into action, whether voluntarily or by the stimulation of sensory nerves, i. e., reflexly. 
In some cases, in order to cause suppression of the reflex, it appears to be sufficient to direct our 
attention to the execution of such a complicated reflex act. Thus some persons cannot sneeze 
when they think intently upon this act itself {Darwin). The voluntary impulse rapidly reaches 
the reflex centre, and begins to influence it so that the normal course of the reflex stimulation, 
due to an impulse from the periphery, is interfered with [Scklosser). 
5. Drugs.—Chloroform diminishes the reflex excitability by acting upon 
the centre, and a similar effect is produced by picrotoxin, morphia, narcotin, 
thebain, aconitin, quinine, hydrocyanic acid. [Chloroform may abolish the 
reflexes without arresting conduction. W. Stirling finds that chloral, potassic 
bromide and chloride, ammonium chloride, but not sodium chloride, greatly 
diminish the reflex excitability. Nicotin increases it in frogs (Freusberg).~\ 
A constant current of electricity passed longitudinally through the cord 
diminishes the reflexes {Ranke'), especially if the direction of the current is from 
above downwards (Legros and Onimus, Uspensky). 
[Some drugs affect the reflex excitability directly by acting on the spinal cord, e.g., 
methylconine, but other drugs may produce the same result indirectly by affecting the heart 
and the blood-supply to the cord. If the abdominal aorta of a rabbit be compressed for a few 
minutes to cut off the supply of blood to the cord and lower limbs, temporary paraplegia is 
produced.] Sec. 361.] 
turck’s method. 
If frogs be asphyxiated in air deprived of all its O, the brain and spinal cord become com- 
pletely unexcitable, and can no longer discharge reflex acts. The motor nerves and the muscles, 
however, suffer verv little, and may retain their excitability for many days (Aubert). 
[Nature of Inhibition.—The foregoing view assumes the existence of inhibitory centres, 
but it is important to point out that it has been attempted to'explain this phenomenon without 
postulating the existence of inhibitory centres. During inhibition the function of an organ is 
restrained—during paralysis it is abolished, so that there is a sharp distinction between the two 
conditions. The analogy between inhibitory phenomena and the effects of interference of 
waves of light or sound has been pointed out by Bernard and Romanes, while Lauder Brunton 
has tried to explain the question on a physical basis, indicating that inhibition is not dependent 
on the existence of special inhibitory centres, but that stimulation and inhibition are different 
phases of excitement, the two terms being relative conditions depending on the length of the 
path along which the impulse has to travel, and the rate of its transmission. Brunton points 
out that the known facts are most consistent with an hypothesis of the interference of waves, 
one with another, than with the supposition that there are inhibitory centres for every so-called 
inhibitory act in the body. In discussing this question great regard must be had to the action of 
the vagus on the heart 369).] 
Tiirck’s method of testing the reflex excitability of a frog is the following : 
A frog is pithed, and after it has recovered from the shock its foot is dipped 
into dilute sulphuric acid [2 per 1000]. The time which elapses between the 
leg being dipped in and the moment it is withdrawn is noted. [The time may 
be estimated by means of a metronome, or the movements may be inscribed 
upon a recording surface. The time which elapses is known as the “period 
of latent stimulation.”] 
This time is greatly prolonged after the optic lobes have been stimulated with a crystal of 
common salt or blood, or after the stimulation of a sensory nerve. 
Setschenow distinguished tactile reflexes, which are discharged by stimulation of the nem/es 
of touch ; and pathic, which are due to stimulation of sensory (pain-conducting) fibres. He 
and Paschutin suppose that the tactile reflexes are suppressed by voluntary impulses, and the 
pathic by the centre in the optic lobes. 
Theory of Reflex Movements.—The following theory has been propounded to account 
for the phenomena already described : It is assumed that the afferent fibre within the gray matter 
of the spinal cord joins one or more nerve-cells, and thus is placed in communication in all direc- 
tions with the network of fibres in the gray substance. Any impulse reaching the gray matter 
of the cord has to overcome considerable resistance. The least resistance lies in the direction 
of those efferent fibres which emerge in the same place and upon the same side as the entering 
fibre. Thus, the feeblest stimulant gives rise to a simple reflex, which generally is merely a 
simple protective movement for the part of the skin which is stimulated. Still greater resistance 
is opposed in the direction of other motor ganglia. If the reflex impulse is to pass to these 
ganglia, either the discharging stimulus must be considerably increased, or the resistance within 
the connections of the ganglia of the gray matter must be diminished. The latter condition is 
produced by the action of the above-named poisons as well as during general increased nervous 
excitability (hysteria, nervousness). Thus, extensive reflex spasms may be produced either by 
increasing the stimulus, or by diminishing the resistance to conduction in the spinal cord. 
Those conditions which render the occurrence of reflexes more difficult, or abolish them alto- 
gether, must be regarded as increasing the resistance in the reflex arc in the cord. The action 
of the reflex inhibitory mechanism may be viewed in a similar manner. 
The fibres of the reflex arc must have a connection with the reflex inhibitory paths; we must 
assume that equally by the reflex inhibitory stimulation resistance is introduced into the reflex 
arc. The explanation of extensive co-ordinated movements is accompanied with difficulties. It 
is assumed that by use and also by heredity those ganglionic cells which are the first to receive 
the impulse are placed in the path of least resistance in connection with those cells which trans- 
fer the impulse to the groups of muscles, whose contraction, resulting in a co-ordinated purposive 
movement, prevents the body or the limb from being affected by any injurious influences. 
[In the light of the recent results of Ramon y Cayal (p. 797), viz., that the afferent fibres 
break up in the gray matter of the cord, and terminate in fibrils which end free and do not anas- 
tomose with the processes of nerve-cells, we must assume that contact of fibrils is sufficient to 
enable impulses to be communicated from one fibril to another.) 
Pathological.—Anomalies of reflex activity afford an important field to the physician in the 
investigation of nervous diseases. Enfeeblement, or even complete abolition of the reflexes 
may occur: (1) Owing to diminished sensibility or complete insensibility of the afferent fibres; (2) 
in analogous affections of the central organ; (3) or, lastly, of the efferent fibres. Where there is 
general depression of the nervous activity (as after shocks, compression or inflammation of the 812 
CUTANEOUS REFLEXES. 
[Sec. 361. 
central nervous organs; in asphyxia, in deep coma, and in consequence of the action of many 
poisons), the reflexes may be greatly diminished or even abolished. 
[Reflexes.—The physician, by studying the condition of the reflexes, can 
form an idea as to the condition of practically every inch of the spinal cord. 
There are three groups of reflexes, (#) the superficial, (t$) the deep or ten- 
don, (c) the organic reflexes.] 
[The superficial cutaneous or skin reflexes are excited by stimulating 
the skin, e.g., by tickling, pricking, scratching, etc. We can obtain a series 
of reflexes from below as far up as the lower part of the cervical region. The 
plantar reflex is obtained by tickling the soles of the feet, when the leg 
on that side, or, it may be, both legs are drawn up. It is always present in 
health, and its centre is in the lumbar enlargement of the cord. The cremas- 
teric reflex is well marked in boys, and is easily produced by exciting the skin 
on the inner side of the thigh, when the testicle on that side is retracted. The 
gluteal reflex consists in a contraction of the gluteal muscles, when the skin 
over the buttock is stimulated. The abdominal reflex consists in a similar 
contraction of the abdominal muscles, when the skin over the abdomen in the 
mammary line is stimulated. The epigastric reflex is obtained by stimulating 
the skin in front between the fourth and sixth ribs. The interscapular reflex 
results in a contraction of the muscles attached to the scapula, when the skin 
between the scapulae is stimulated. Its centre corresponds to the lower cervical 
and upper dorsal region.] 
[The following table, after Gowers, shows the relation of each reflex to the spinal segment or 
segments on which it depends :— 
Cervical, . . . 
... 6) 
a 
... 7 
... 8 
Interscapular. 
Dorsal, . . . 
• • • i, 
“ 
... 5 
ii 
. . . 6 
- Epigastric. 
(( 
a 
. . . 81 
<< 
... 9 
it 
. . . io 
Abdominal. 
... ii 
iC 
. . . 12) 
Lumbar, 
i 
Cremasteric. 
«' . 
:. •::: L 
j- Knee-jerk. 
(( 
;;;;;; J 
••••’•• 1 
■ Gluteal. 
Sacral, . 
s 'I Plantar. 
a 
:::::: 32J 
y s | 1 Vesical. 
\ Rectal. 
<< ; 
4 
5 
J Sexual.] 
Another important diagnostic reflex is the “abdominal reflex,” which 
consists in this, that when the skin of the abdomen is stroked, e.g., with the 
handle of a percussion-hammer, the abdominal muscles contract. When this 
reflex is absent on both sides in a cerebral affection, it indicates a diffuse dis- 
ease of the brain ; its absence on one side indicates a local affection of the 
opposite half of the brain. The cremasteric, conjunctival, mammillary, 
pupillary, and nasal reflexes may also be specially investigated. In hemi- 
plegia complicated with cerebral lesions, the reflexes on the paralyzed side are 
diminished, whilst not unfrequently the patellar reflex may be increased. In 
extensive cerebral affections accompanied by coma the reflexes are absent on 
both sides, including of course those of the anus and bladder ( O. Rosenbacli). 
[Horsley finds that in the deepest narcosis produced by nitrous oxide gas the superficial re- 
flexes (e.g., plantar, conjunctival) are abolished, while the deep (knee-jerk) remain. Anaemia 
of the lumbar enlargement (compression of the abdominal aorta) causes disappearances of both 
reflexes (Prtvost). Chloroform and asphyxia abolish the deep as well as the superficial reflexes. 
Horsley regards the so-called deep reflex or knee-jerk not as depending on a centre in the cord, 
but the contraction of the rectus femoris is due to local irritation of the muscle from sudden 
elongation.] 
Deep or so-called Tendon Reflexes.—Under pathological conditions, 
special attention is directed to the so-called tendon reflexes [or better still, Sec. 361.] 
DEEP REFLEXES. 
813 
tendon reactions], which depend upon the fact that a blow upon a tendon 
(e. g., the quadriceps femoris, tendo-Achillis, etc.) discharges a contraction of 
the corresponding muscle ( Westphal, Erb, 1875). The patellar-tendon reflex 
[also called “knee phenomenon’’] or simply “ knee reflex ” or “ knee- 
jerk,” is invariably absent in cases of ataxic tabes dorsalis, while in spastic 
spinal paralysis it is abnormally strong and extensive (.Erb). [The “ knee- 
jerk” is elicited by percussing the ligamentum patellae, and is due to a single 
spasm of the rectus. The latent period is 0.03 to 0.04 second, and it is argued 
by Waller and others that it is doubtful if this reaction is subserved by a spinal 
nervous arc, while admitting the effect of the spinal cord in modifying the re- 
sponse of the muscle.] Section of the motor nerves abolishes the patellar phe- 
nomenon in rabbits (Schultze), and so does section of the cord opposite the 
5th and 6th lumbar vertebrae (Tschirjew). Landois finds that in his own per- 
son the contraction occurs 0.048 second after the blow upon the ligamentum 
patellae. According to Waller, the patellar reflex and the tendo-Achillis reflex 
occur 0.03 to 0.04 second, and according to Eulenburg, 0.032 second after the 
blow. According to Westphal, these phenomena are not simple reflex pro- 
cesses, but complex conditions intimately dependent upon the muscle tonus, so 
that when the tonus of the quadriceps femoris is diminished, the phenomenon 
is abolished. In order that the phenomenon may take place, it is necessary 
that the outer part of the posterior column of the spinal cord remain intact 
( Westphal). [The knee-jerk can be increased or reinforced by volitional acts 
directed to other parts of the body, e. g., by exercising voluntary pressure with 
the hand (Jendrassik) extremely prolonged contractions and high tension en- 
feeble it.] [A “jaw-jerk” is obtained by suddenly depressing the lower jaw 
{Gowers, Beevor, and De Watteville), and the last observer finds that the latent 
period is 0.02 second, and if this be the case, it is an argument against these 
so-called “ tendon reflexes” being true reflexes, and that they are direct con- 
tractions of the muscles due to sudden stimulation by extension.] 
[Method.—The knee-jerk is easily elicited by striking the patellar tendon 
with the edge of the hand or a percussion-hammer when the leg is semi-flexed, 
as when the legs are hanging over the edge of a table or when one leg is crossed 
over the other. It is almost invariably present in health, but it becomes greatly 
exaggerated in descending degeneration of the lateral columns and lateral scle- 
rosis.] 
[Ankle clonus is another tendon reflex, and it is never present in health. 
If the leg be nearly extended, and pressure made upon the sole of the foot so 
as suddenly to flex the foot at the ankle, a series of (5 to 7 per second) rhyth- 
mical contractions of the muscles of the calf takes place. Gowers describes a 
modification elicited by tapping the muscles of the front of the leg, the “ front- 
tap contraction." Ankle clonus is excessive in sclerosis of the lateral columns 
and spastic paralysis.] 
[In “ ankle clonus ” excited by sudden passive flexion of the foot, there is a multiple spasm 
of the gastrocnemius. Here also the latent period is about 0.03 to 0.04 second, and the rhythm 
8 to 10 per second. This short latent period has led some observers to doubt the essentially 
reflex nature of this act.] 
When we are about to sleep (§ 374), there is first of all a temporary increase of the reflexes; 
in the first sleep the reflexes are diminished, and the pupils are contracted. In deep sleep the 
abdominal, cremasteric, and patellar reflexes are absent; while tickling the soles of the feet and 
the nose only acts when the stimulus is of a certain intensity. In narcosis, e. g., chloroform or 
morphia, the abdominal, then the conjunctival and patellar reflexes disappear; lastly, the pupils 
contract (O. Rosenbach). 
Abnormal increase of the reflex activity usually indicates an increase of the excitability of 
the reflex centre, although an abnormal sensibility of the afferent nerve may be the cause. As 
the harmonious equilibrium of the voluntary movements is largely dependent upon and regulated 
by the reflexes, it is evident that in affections of the spinal cord there are frequent disturbances 814 
CENTRES IN THE CORD. 
[Sec. 361. 
of the voluntary movements, e.g., the characteristic disturbance of motion in attempting to walk, 
and in grasping movements exhibited by persons suffering from ataxic tabes dorsalis [or as it is 
more generally called, locomotor ataxia\ 
[The organic reflexes include a consideration of the acts of micturition, 
erection, ejaculation, defaecation, and those connected with the motor and 
secretory digestive processes, respiration, and circulation.] 
362. CENTRES IN THE SPINAL CORD.—Centres capable of 
being excited reflexly, and which can bring about the discharge of certain 
complicated, yet well-co-ordinated motor acts exist in various parts of the spinal 
cord. They still retain their activity after the spinal cord is separated from 
the medulla oblongata; further, those centres lying in the lower part of the 
spinal cord still retain their activity after being separated from the higher 
centres, but in the normal intact body they are subjected to the control of 
higher reflex centres in the medulla oblongata. Hence, we may speak of them 
as subordinate spinal centres. The cerebrum also, partly by the production of 
perceptions, and partly as the organ of volition, can excite or suppress the 
action of certain of these subordinate spinal centres. [For the significance of 
the term “ Centre,” see p. 785.] 
1. The cilio-spinal centre connected with the dilatation of the pupil 
lies in the lower cervical part of the cord, and extends downwards to the region 
of the 1st to the 3d dorsal vertebra. It is excited by diminution of light; 
both pupils always react simultaneously, when one retina is shaded. Unilateral 
extirpation of this part of the spinal cord causes contraction of the pupil on 
the same side. The motor fibres pass out by the anterior roots of the two lower 
cervical and two upper dorsal nerves into the cervical sympathetic (§ 392). 
Even the idea of darkness may sometimes, though rarely, cause dilatation of 
the pupil (Budge). 
In goats and cats, this centre, even after being separated from the medulla oblongata, can be 
excited directly by dyspnceic blood, and also reflexly by the stimulation of sensory nerves, e. g., 
the median, especially when the reflex excitability of the cord is increased by the action of 
strychnin or atropin (Luchsinger). For the dilator centre in the medulla oblongata, see \ 367, 8. 
2. The ano-spinal centre, or centre controlling the act of defaecation. 
The afferent nerves lie in the hgemorrhoidal and inferior mesenteric plexuses, 
the centre at the 5th (dog) or 6th to 7th (rabbit) lumbar vertebra ; the efferent 
fibres arise from the pudendal plexus and pass to the sphincter muscles. For 
the relation of this centre to the cerebrum see § 160. After section of the 
spinal cord [in dogs], Goltz observed that the sphincter contracted rhythmi- 
cally upon the finger introduced into the anus; the co-ordinated activity of 
the centre therefore would seem to be possible only when the centre remains in 
connection with the brain. 
3. The vesico-spinal centre for regulating micturition, or Budge’s vesico- 
spinal centre. The centre for the sphincter muscle lies at the 5th (dog) or the 
7th (rabbit) lumbar vertebra, and that for the muscles of the bladder somewhat 
higher. The centre acts only in a properly co-ordinated way in connection 
with the brain (§ 280). 
4. The erection centre also lies in the lumbar region (§ 436). The 
afferent nerves are the sensory nerves of the penis; the efferent nerves for the 
deep artery of the penis are the vaso-dilator nerves, arising from the 1st to 
3d sacral nerves, or Eckhard’s nervi erigentis—while the motor nerves for 
the ischio-cavernosus and deep transverse perineal muscles arise from the 3d to 
4th sacral nerves (§ 356). The latter may also be excited voluntarily, the 
former also partly by the brain, by directing the attention to the sexual activity. 
Eckhard observed erection to take place after stimulation of the higher regions 
of the spinal cord, as well as of the pons and crura cerebri. Sec. 362.] 
CENTRES IN THE CORD. 
815 
5. The ejaculation centre. The afferent nerve is the dorsal of the penis, 
the centre (Budge’s genito-spinal centre) lies at the 4th lumbar vertebra (rabbit); 
the motor fibres of the vas deferens arise from the 4th and 5th lumbar nerves, 
which pass into the sympathetic, and from thence to the vas deferens. The 
motor fibres for the bulbo-cavernosus muscle, which ejects the semen from the 
bulb of the urethra, lie in the 3d and 4th sacral nerves (perineal). 
6. The parturition centre lies at the 1st and 2d lumbar vertebrae (§ 453); 
the afferent fibres come from the uterine plexus, to which also the motor fibres 
proceed (Kdrner). Goltz and Freusberg observed that a bitch became pregnant 
after its spinal cord was divided at the 1st lumbar vertebra. 
7. Vaso-motor Centres.—Both vaso-motor and vaso-dilator centres are 
distributed throughout the whole spinal axis. To them belongs the centre for 
the spleen, which in the dog is opposite the 1st to 4th cervical vertebrae (.Bulgak). 
They can be excited reflexly, but they are also controlled by the dominating 
centre in the medulla oblongata (§ 371). Psychical disturbance (cerebrum) 
influences them (§ 377). 
[8. Perhaps there are vaso-dilator centres (§ 372).] 
9. The sweat centre is perhaps distributed similarly to the vaso-motor 
centre (§ 288). 
The reflex movements discharged from these centres are orderly co-ordinated reflexes, and 
may thus be compared to the orderly reflexes of the trunk and extremities. 
Muscle Tonus.—Formerly auto7natic functions were ascribed to the spinal cord, one of these 
being that it caused a moderate active tension of the muscles—a condition that was termed 
muscle tone, or tonus. The existence of tonus in a striped muscle was thought to be proved by 
the fact that, when such a muscle was divided, its ends retracted. This is due merely to the 
fact that all the muscles are stretched slightly beyond their normal length (£ 301). Even 
paralyzed muscles, which have lost their muscular tone, show the same phenomenon. Formerly 
the stronger contraction of certain muscles, after paralysis of their antagonists, and the retraction 
of the facial muscles to the sound side, after paralysis of the facial nerve, were also regarded as 
due to tonus. This result is due to the fact that, during the activity of the intact muscle, the 
other ones have not sufficient power to restore the parts to their normal median position. The 
following experiment of Auerbach and Heidenhain is against the assumption of a tonic con- 
traction : If the muscles of the leg of a decapitated frog be stretched, it is found that they do 
not elongate after section of the sciatic nerve, or after it is paralyzed by touching it with 
ammonia or carbolic acid. 
Reflex Tonus.—If, however, a decapitated frog be suspended in an abnormal position, we 
observe, after section of the sciatic nerve, or the posterior nerve-roots on one side, that the leg 
on that side hangs limp, while the leg on the sound side is slightly retracted. The sensory 
nerves of the latter are slightly and continually stimulated by the weight of the limb, so that a 
slight reflex retraction of the leg takes place, which disappears as soon as the sensory nerves of 
the leg are divided. If we choose to call this slight retraction tonus, then it is a reflex tonus 
(Brondgeest). (See the experiments of Harless, C. Ludwig, and Cyon—\ 355-) 
363. EXCITABILITY OF THE SPINAL CORD.—Even at the 
present time observers are by no means agreed whether the spinal cord, like 
peripheral nerves, is excitable, or whether it is distinguished by the remarkable 
peculiarity that most of its conducting paths and ganglia do not react to direct 
electrical and mechanical stimuli. 
It is contended by some observers that if stimuli be cautiously applied either to white or 
gray matter, there is neither movement nor sensation ( Van Deen (1841), Brown-Sequard). Care 
must be taken not to stimulate the, roots of the spinal nerves, as these respond at once to stimuli, 
and thus may give rise to movements or sensations. As the spinal cord conduces to the brain 
impulses communicated to it from the stimulated posterior roots, but does not itself respond to 
stimuli which produce sensations, Schiff has applied to it the term “ aesthesodic.” Further, as 
the cord can conduct both voluntary and reflex motor impulses, without, however, itself being 
affected by motor impulses applied to it directly, he calls it “ kinesodic.” 
Schiff’s views are as follows :— 
1. In the posterior columns the sensory root fibres of the posterior root 
which traverse these columns give rise to painful impressions, but the proper EXCITABILITY OF THE CORD. 
[Sec. 363. 
paths of the posterior columns themselves do not do so. The proof that stimu- 
lation of the posterior column produces sensory impressions, he finds in the fact 
that dilatation of the pupil occurred with every stimulation (§ 292). Removal 
of the posterior column produces anaesthesia (loss of tactile sensation). Algesia 
[or the sensation of pain] remains intact, although at first there may even be 
hyperalgesia. 
2. The anterior columns are non-excitable, as long as the stimuli are ap- 
plied only to the proper paths of this column, but movements may follow, 
both in striped and non-striped muscle, either when the anterior nerve-roots 
are stimulated, or when, by the escape of the current, the posterior columns are 
affected, whereby reflex movements are produced. 
According to Schiff, therefore, all the phenomena of irritation, which occur when an uninjured 
cord is stimulated (spasms, contracture), are caused either by simultaneous stimulation of the 
anterior roots, or are reflexes from the posterior columns alone, or simultaneously from the 
posterior columns and the posterior roots. Diseases affecting only the anterior and lateral 
columns alone never produce symptoms of irritation, but always of paralysis. In complete 
anaesthesia and apnoea, every form of stimulus is quite inactive. According to Schiff’s view, all 
centres, both spinal and cerebral, are inexcitable by artificial means. 
Direct Excitability.—Many observers, however, oppose these views, and contend that the 
spinal cord is excitable to direct stimulation. Fick observed movements to take place 
when he stimulated the white columns of the cord of a frog, isolated for a long distance so as to 
avoid the escape of the stimulating currents. Sirotinin, also, who stimulated the transverse 
section of the frog’s cord from point to point, obtained contraction of the muscles both by 
mechanical and electrical stimuli. Biedermann comes to the following conclusions : The trans- 
verse section of a motor nerve is most excitable. Weak stimuli (descending opening shocks) 
excite the cut surface of the transversely divided spinal cord, but do not act when applied 
further down. Luchsinger asserts that, after dipping the anterior part of a beheaded snake into 
warm water, the reflex movements of the upper part of the cord are abolished, while the direct 
excitability remains. 
3. Excitability of the Vaso-motors.—The vaso-constrictor nerves, 
which proceed from the vaso-motor centre and run downwards in the lateral 
columns of the cord, are excitable by all stimuli along their whole course; 
direct stimulation of any transverse section of the cord constricts all the blood- 
vessels below the point of section (C. Ludwig and Thiry). In the same way, 
the fibres which ascend in the cord, and increase the action of the vaso-motor 
centre—pressor fibres—are also excitable ( C. Ludwig and Dittmar—§ 364, 10). 
Stimulation of these fibres, although it affects the vaso-motor centre reflexly, 
does not cause sensation. 
4. Chemical stimuli, such as the application of common salt, or wetting 
the cut surface with blood, appear to excite the spinal cord. 
5. The motor centres are directly excited by (1) blood heated above 
40° C., or (2) by asphyxiated blood, or by sudden and complete anaemia of 
the cord produced by ligature of the aorta (Sigm. Mayer); and (3) also by 
certain poisons—picrotoxin, nicotin, and compounds of barium (Luchsinger). 
Action of Blood and Drugs.—In experiments of this kind, the spinal cord ought to be 
divided at the 1st lumbar vertebra, at least twenty hours before the experiment is begun. It is 
well to divide the posterior roots beforehand to avoid reflex movements. If, in a cat thus 
operated on, dyspnoea be produced, or its blood overheated, then spasms, contraction of the 
vessels, and secretion of szveat occur in the hind limbs, together with evacuation of the contents 
of the bladder and rectum, while there are movements of the uterus and the vas deferens. 
Some poisons act in a similar manner. In animals with the medulla oblongata divided, rhyth- 
mical respiratory movements may be produced if the spinal cord has been previously rendered 
very sensitive by strychnin or overheated blood (P. v. Rokitansky, v. Schroff—§ 368). 
The ganglion-cells of the anterior cornu can be excited (mechanically) 
(.Birge), and, according to Biedermann, the gray matter also responds to electri- 
cal stimuli. 
Hyperaesthesia.—After unilateral section of the cord, or even only of the Sec. 363.] 
CONDUCTION IN THE CORD. 
817 
posterior or lateral columns, there is hypercesthesia on the same side below the 
point of section (Fodera, 1823, and others), so that rabbits shriek on the 
slightest touch. The phenomenon may last for three weeks, and then give place 
to normal or sub-normal excitability. On the sound side the sensibility re- 
mains permanently diminished. A similar result has been observed in cases of 
injury in man. An analogous phenomenon, or a tendency to contraction in the 
muscles below the section (hyperkinesia), has been observed by Brown- 
Sequard after section of the anterior columns. 
Sudden and complete anaemia (by occluding the abdominal aorta in the dog) causes at first 
spasms (20 seconds), then paralysis (1 min.), then loss of response to sensory (2 mins.), and 
lastly complete loss of sensibility (3 mins.) (Fredericq). 
The excitability of the cord is intimately dependent on the continuance of 
the normal circulation, for ligature of the abdominal aorta rapidly paralyzes 
the lower extremities (Stenson, 1667), due to anaemia of the cord (Schiffer). 
After a time the anterior roots of the spinal nerves, and the anaemic part of 
the gray matter of the cord, undergo degeneration. 
364. THE CONDUCTING PATHS IN THE SPINAL 
CORD.—[Posterior Root.—(a) The inner part, or internal radicular 
fasciculus is supposed to convey the impressions from tendons and those for 
touch and locality. When the postero-external column is diseased, as in loco- 
motor ataxia, the deep reflexes, especially the patellar tendon jerk, are en- 
feebled, or it may be abolished, while the implication of the fibres of the inter- 
nal fasciculus gives rise to severe pain. (b) The outer radicular fibres enter 
the gray matter of the posterior horn, and are supposed to convey the impres- 
sions for cutaneous reflexes and temperature. (c) The central fibres pass 
directly into the gray matter, and are supposed to conduct painful impressions 
into the gray matter (fig. 543).] 
1. Localized tactile sensations (temperature, pressure, and the muscular 
sense impressions) are conducted upwards through the posterior roots of the 
ganglia of the posterior cornu, and lastly into the posterior column of the 
same side. 
In man, the conducting path from the legs runs in Goll’s column, while those for the arm 
run in the ground-bundle (fig. 553) (Flechsig). In rabbits, the path of localized tactile impres- 
sions lies in the lower dorsal region in the lateral columns [Ludwig and Woroschiloff, Ott and 
Meade-Smith). 
Anaesthesia.—Section of individual parts of the lateral columns abolishes the sensibility for 
the parts of the skin connected with the part destroyed, while total section produces the same 
result for the whole of the opposite side of the body below the section. The condition where 
tactile and muscular sensibility is lost is known as ancesthesia. 
2. Localized voluntary movements in man are conducted on the same 
side through the anterior and lateral columns (§§ 358 and 365), in the parts 
known as the pyramidal tracts. The impulses then pass into the cells of 
the anterior cornu, and thence to the corresponding anterior nerve-roots to the 
muscles. The exact section experiments of Ludwig and Woroschiloff showed 
that, in the lower dorsal region of the rabbit, these paths were confined to the 
lateral columns. Every motor nerve-fibre is connected with a nerve-cell in the 
anterior horn of the frog’s spinal cord (Gaule and Birge). Section of one 
lateral column abolishes voluntary movement in the corresponding individual 
muscles below the point of section. It is obvious, from the conduction in 1 
and 2, that the lateral columns must increase in thickness and number of fibres 
from below upwards (Stilling, Woroschiloff') [see fig. 536]. 
3. Tactile reflexes (extensive and co-ordinated).—The fibres enter by the 
posterior root, and proceed to the posterior cornu. The groups of ganglionic CONDUCTION IN THE CORD. 
[Sec. 364. 
cells, which control the co-ordinated reflexes, are connected together by fibres 
which run in the anterior tracts, the anterior ground bundle, and (?) the direct 
cerebellar tracts (p. 801). The fibres for the muscles which are contracted 
pass from the motor ganglia outwards through the anterior roots. 
In ataxic tabes dorsalis, or locomotor ataxia, there is a degeneration of the posterior 
columns, characterized by a peculiar motor disturbance. The voluntary movements can be exe- 
cuted with full and normal vigor, but the finer harmonious adjustments are wanting or impaired, 
both in intensity and extent. These depend in part upon the normal existence of tactile and 
muscular impressions, whose channels lie in the posterior columns. After degeneration of the 
latter, there is not only anaesthesia, but also a disturbance in the discharge of tactile reflexes, for 
which the centripetal arc is interrupted. But a simultaneous lesion of the sensory nerves alone 
may in a similar manner materially influence the harmony of the movements, owing to the 
analgesia and the disappearance of the pathic reflexes (§ 355). As the fibres of the posterior 
root traverse the white posterior columns, we can account for the disturbances of sensation which 
characterize the degenerations of these parts [Charcot and Pierret). But even the posterior 
roots themselves may undergo degeneration, and this may also give rise to disturbances of sensa- 
tion (p. 775). The sensory disturbances usually consist in an abnormal increase of the tactile or 
painful sensations, with lightning pains shooting down the limbs, and this condition may lead to 
one where the tactile and painful sensations are abolished. At the same time, owing to stimu- 
lation of the posterior columns, the tactile sensibility is altered, giving rise to the sensation of 
formication, or a feeling of constriction [“ girdle sensation ”]. The conduction of sensory 
impressions is often slowed ($ 337). The sensibility of the muscles, joints, and internal parts is 
altered. 
The maintenance of the equilibrium is largely guided by the impulses which travel 
inwards to the co-ordinating centres through the sensory nerves, special and general, deep and 
superficial. In many cases of locomotor ataxia, if the patient place his feet close together and 
close his eyes, he sways from side to side, and may fall over, because by cutting off the guiding 
sensations obtained through the optic nerve, the other enfeebled impulses obtained from the skin 
and the deeper structures are too feeble to excite proper co-ordination. 
4. The inhibition of tactile reflexes occurs through the anterior columns 
(?) ; the impulses pass from the anterior column at the corresponding level into 
the gray matter, where they form connections with the reflex conducting 
apparatus. 
5. The conduction of painful impressions occurs through the posterior roots, 
and thence through the whole of the gray matter. There is a partial decussa- 
tion of these impulses in the cord, the conducting fibres passing from one side 
to the other. The further course of these fibres to the brain is given in § 365. 
If all the gray matter be divided, except a small connecting portion, this is sufficient to con- 
duct painful impressions. In this case, however, the conduction is slower (Schiff). Only when 
the gray matter is completely divided is the conduction of painful impressions from below com- 
pletely interrupted. This gives rise to the condition of analgesia, in which, when the posterior 
columns are still intact, tactile impressions are still conducted. This condition is sometimes 
observed in man during incomplete narcosis from chloroform and morphia ( Thiersch). Those 
poisons act sooner on the nerves which administer to painful sensations than on those for tactile 
impressions, so that the person operated on is conscious of the contact of a knife, but not of the 
painful sensations caused by the knife dividing the parts. As painful impressions are conducted 
by the whole of the gray matter, and as the impressions are more powerful the stronger the 
painful impression, we may thus explain the so-called irradiation of painful impressions. 
During violent pain, the pain seems to extend to wide areas; thus, in violent toothache, pro- 
ceeding from a particular tooth, the pain may be felt in the whole jaw, or it may be over one side 
of the head. 
According to Bechterew, the paths for the conduction of painful impressions lie in the anterior 
part of the lateral column (dog, rabbit). 
The experiments of Weiss on dogs, by dividing the lateral column at the limit of the dorsal 
and lumbar regions, showed that each lateral column contains sensory fibres for both sides. The 
chief mass of the motor fibres remains on the same side. Section of both lateral columns 
abolishes completely sensibility and motility on both sides. The anterior columns and the gray 
matter are not sufficient to maintain these. 
6. The conduction of spasmodic, involuntary, inco-ordinated move- Sec. 364.] 
CONDUCTION IN THE CORD. 
819 
ments takes place through the gray matter, and from the latter through the 
anterior roots. 
It occurs in epilepsy, poisoning with strychnin, uraemic poisoning, and tetanus (§ 360, II). 
The anaemic and dyspnoeic spasms are excited in and conducted from the medulla oblongata, and 
communicated through the whole of the gray matter. 
7. The conduction of extensive reflex spasms takes place from the pos- 
terior roots, and then to the cells of the anterior cornu, above and below the 
plane of the entering impulse (fig. 458), and, lastly, into the anterior roots, 
under the conditions already referred to in § 360, II. 
8. The inhibition of pathic reflexes occurs through the anterior 
columns downwards, and then into the gray matter to the connecting channels 
of the reflex organ, into which it introduces resistance. 
9. The vaso-motor fibres run in the lateral columns (.Dittmar), and, after 
they have passed into the ganglia of the gray matter at the corresponding level, 
they leave the spinal cord by the anterior roots. They reach the muscles of 
the blood-vessels either through the paths of the spinal nerves, or they pass 
through the rami communicantes into the sympathetic, and thence into the 
visceral plexuses (§ 356). 
Section of the spinal cord paralyzes all the vaso-motor nerves below the point of section; 
while stimulation of the peripheral end of the spinal cord causes contraction of all these vessels. 
[Ott’s experiments on cats show that the vaso-motor fibres run in the lateral columns, and that 
they as well as the sudorific nerves decussate in the cord.] 
10. Pressor fibres enter in the posterior roots, run upwards in the lateral 
columns, and undergo an incomplete decussation (.Ludwig and Miescher). 
They ultimately terminate in the dominating vaso-motor centre in the medulla oblongata, which 
they excite reflexly. Similarly, depressor fibres must pass upwards in the spinal cord, but we 
know nothing as to their course. 
11. From the respiratory centre in the medulla oblongata, respiratory 
nerves run downwards in the lateral columns on the same side, and after form- 
ing connections with the ganglia of the gray matter pass through the anterior 
roots into the motor nerves of the respiratory muscles (,Schiff). 
Unilateral, or total destruction of the spinal cord, the higher up it is done, accordingly 
paralyzes more and more of the respiratory nerves, on the same or on both sides. Section of the 
cord above the origin of the phrenic nerves causes death in some animals, owing to the paralysis 
of these nerves of the diaphragm (§ 113). 
In pathological cases, in degeneration of, or direct injury to, the spinal cord or its individual 
parts, we must be careful to observe whether there may not be present simultaneously paralytic 
and irritative phenomena, whereby the symptoms are obscured. 
Degeneration of the posterior columns without involving the posterior root-fibres causes loss 
of tactile sensibility, the feeling for heat remaining intact. Degeneration of the nerve-cells of 
the anterior cornu, as in infantile spinal paralysis, causes paralysis of the motor nerves pro- 
ceeding from them, and at the same time the muscles supplied by these nerves rapidly undergo 
atrophy, as these cells are the trophic centres both for these nerves and the muscles they 
supply. Degeneration of the posterior cornu causes disturbance of the cutaneous sensibility 
and produces trophic changes in the skin. 
If the abdominal aorta be temporarily closed in rabbits, there results permanent motor and 
sensory paralysis, and in the region of the cord rendered anaemic the ganglion cells and fibres 
of the anterior cornu undergo degeneration (Ehrlich, Singer). 
[Complete transverse section of the cord results immediately in 
complete paralysis of motion and sensation in all the parts supplied by nerves 
below the seat of the injury, although the muscles below the injury retain their 
normal trophic and electrical conditions. There is a narrow hypersesthetic area 
at the upper limit of the paralyzed area, and when this occurs in the dorsal 
region it gives rise to the feeling of a belt tightly drawn round the waist, or the 
“girdle sensation.” There is also vaso-motor paralysis below the lesion, but 820 
SECTION OF THE CORD. 
[Sec. 364. 
the blood-vessels soon regain their tone, owing to the subsidiary vaso-motor 
centres in the cord. Thus the person has no voluntary control over the parts 
supplied by nerves coming off below the injury. If the section be in the lower 
dorsal region, the processes of micturition and defaecation cease to be under 
voluntary control, but after a time these acts can be executed reflexly. The 
remote effects come on much later, and are secondary descending degenera- 
tion in the crossed and direct pyramidal tracts and ascending degeneration in 
the postero-internal columns (fig. 558). According to the seat of the lesion, 
the functions of the bladder and rectum may be interfered with. Injury to 
the upper cervical region sometimes causes hyperpyrexia. Of course section 
high up in the cervical region will interfere with the respiratory movements, 
the result depending on the level at which the section is made.] 
[Unilateral section results in paralysis of voluntary motion in the muscles 
of the same side supplied by nerves given off below the seat of the injury, 
although the muscles do not atrophy, but when secondary 
descending degeneration occurs they become rigid, and 
exhibit the ordinary signs of contracture. There is vaso- 
motor paralysis on the same side, although this passes off 
below the injury, while the ordinary and muscular sensibility 
are diminished on both sides (fig. 562). There is bilateral 
anaesthesia. On the opposite side there is total anaesthesia 
and analgesia below the lesion, but on the same side in the 
dorsal region there is a narrow circular anaesthetic zone 
(fig. 562, 6), corresponding to the sensory nerve-fibres 
destroyed at the level of the section. The sensory nerves 
decussate shortly after they enter the cord, hence the anaes- 
thesia on the opposite side, but they do not cross at once, 
but run obliquely upwards before they enter the gray matter 
of the opposite side, so that a unilateral section will involve 
some fibres coming from the same side, and hence the 
slightly diminished sensibility in a circular area on the same 
side.. There is a narrow hyperaesthetic area on the same side 
as the lesion, at the upper limit of the paralyzed cutaneous 
area (fig. 562, c), due perhaps to stimulation of the cut ends 
of the sensory fibres on that side. In man there is hyper- 
esthesia (to touch, tickling, pain, heat, and cold) on the 
parts below the lesion on the same side, but the cause of 
this is not known. The remote effects are due to the usual 
descending and ascending degeneration which set in.] 
[In monkeys, after hemi-section of the cord in the dorsal region, 
there is paralysis of voluntary motion and retention of sensibility with 
vaso-motor paralysis of the same side, and retention of voluntary motion 
with anaesthesia and analgesia on the opposite side. The existence of 
hyperaesthesia on the side of the lesion is not certain in these animals, but 
there is no doubt of it in man. Ferrier also finds (in opposition to Brown-Sequard) that the 
muscular sense is paralyzed, as well as all other forms of sensibility, on the side opposite to the 
lesion, but unimpaired on the side of the lesion. The muscular sense, in fact, is entirely sepa- 
rable from the motor innervation of muscle (Ferrier). The power of emptying the bladder and 
rectum was not affected.] 
Fig. 562. 
Diagrammatic repre- 
sentation of a lesion 
of the left half of 
the spinal cord in 
the dorsal region, 
(a) oblique lines, 
motor and vaso- 
motor paralysis; 
(b,d), complete an- 
aesthesia; (rt, r), 
hyperaesthesia of 
the skin. Sec. 365.] 
SCHEMA OF THE BRAIN. 
821 
The Brain. 
365. GENERAL SCHEMA OF THE BRAIN.—In an organ so 
complicated in its structure as the brain, it is necessary to have a general view 
of the chief arrangements of its individual parts. Meynert gave a plan of the 
general arrangement of this organ, and although this plan may not be quite 
correct, still it is useful in the study of brain function. The average weight 
of the brain is in man about 1358 grams, and in woman 1220 grams (Bischoff). 
[A special layer of gray matter of the cerebrum is placed externally and 
spread as a thin coating over the white matter or centrum ovale—which lies 
internally, and consists of nerve-fibres or the white matter. That part lying 
in each hemisphere is the centrum semi-ovale. The gray matter is folded into 
gyri or convolutions separated from each other by fissures or sulci. Some 
of the latter are very marked, and serve to separate adjacent lobes, while the 
lobes themselves are further subdivided by sulci into convolutions. For a 
description of the lobes see 
§ 375. Some masses of gray 
matter are disposed at the 
base of the brain, forming 
the corpus striatum (pro- 
jecting into the lateral ven- 
tricles), which in reality is 
composed of two parts, the 
nucleus caudatus and lenti- 
cular nucleus (fig. 563, b), 
the optic thalamus, which 
lies behind the former, and 
bounds the 3d ventricle (fig. 
563, a), the corpora quad- 
rigemina lying on the upper 
surface of the crura cerebri 
(fig- 563? hi); within the 
tegmentum of the crura 
cerebri are the red nucleus 
and locus niger (fig. 628). 
Lastly, there is the continua- 
tion of the gray matter of 
the cord up through the 
medulla, pons, and around 
the iter, forming the central 
gray tube, and terminating 
anteriorly at the tuber cine- 
reum. These various parts 
are connected in a variety of 
ways with each other, some 
by transverse fibres stretch- 
ing between the two sides 
of the brain, while other 
longitudinal fibres bring the 
hinder and lower parts into 
relation with the fore parts.] 
[Under cover of the occi- 
pital lobes, but connected with the cerebrum in front and the spinal cord 
Dissection of the brain from above, showing the lateral 3d 
and 4th ventricles, with the basal ganglia, and surrounding 
parts, a, knee of the corpus callosum ; b, anterior part of 
the right corpus striatum; b', gray matter dissected off to 
show white fibres; c, points to taenia semicircularis; d, 
optic thalamus; e, anterior pillars of fornix, with 5th ven- 
tricle in front of them, between the two laminae of the 
septum lucidum; f, middle or soft commissure; g, 3d 
ventricle; h,i, corpora quadrigemina ; k, superior cere- 
bellar peduncle; /, hippocampus major; m, posterior cornu 
of lateral ventricle; n, eminentia collaterals; 0, 4th ven- 
tricle ; p, medulla oblongata; s, cerebellum, with r, arbor 
vitae. 
Fig- 563. 822 
meynert’s projection systems. 
[Sec. 365. 
below, is the cerebellum, which has its gray matter externally and its white 
core internally. Thus we have to consider cerebro-spinal and cerebello-spinal 
connections.] 
Fig. 564. 
I, Scheme of the brain.—C, C, cortex cerebri; C.j, corpus striatum, N./, nucleus lenticularis; 
T.o, optic thalamus; v, corpora quadrigemina; P, pedunculus cerebri; H, tegmentum; 
andp, crusta; 1, x, corona radiata of the corpus striatum; 2, 2, of the lenticular nucleus; 
3, 3, of the optic thalamus; 4, 4, of the corpora quadrigemina; 5, pyramidal fibres from 
the cortex cerebri (Flechsig); 6, 6, fibres from the corpora quadrigemina to the tegmentum; 
m, further course of these fibres; 8, 8, fibres from the corpus striatum and lenticular nucleus 
to the crusta of the pedunculus cerebri; M, further course of these; S, S, course of the 
sensory fibres; R, transverse section of the spinal cord; v. W, anterior, and h. W, posterior 
roots; a, a, association system of fibres; c, c, commissural fibres. II, Transverse section 
through the posterior pair of the corpora quadrigemina and the pedunculi cerebri of man 
—p, crusta of the peduncle; s, substantia nigra ; v, corpora quadrigemina, with a section 
of the aqueduct. Ill, The same of the dog; IV, of an ape; V, of the guinea-pig. [See 
p. 821.] 
[Meynert’s Projection Systems.—The cortex of the cerebrum consists of convolutions and 
sulci, the “ peripheral gray matter ” (fig. 564, C), which is recognized as a nervous structure, 
from the presence in it of numerous ganglionic cells (§ 358, 1). From it proceed all the Sec. 365.] 
meynert’s projection systems. 
823 
motor fibres which are excited by the will, and to it proceed all the fibres coming from the 
organs of special sense and sensory organs, which give rise to the psychical perception of ex- 
ternal impressions. [In fig. 564 the decussation of the sensory fibres is represented as occurring 
near the medulla oblongata. It is more probable that a large number of the sensory fibres 
decussate shortly after they enter the cord, as is represented in fig. 569. Some of the sensory 
fibres, however, decussate in the medulla oblongata.] 
First Projection System.—The channels lead to and from the cortex cerebri, some of them 
traversing the basal ganglia, or ganglia of the cerebrum—the corpus striatum (C.r) (composed 
of the caudate nucleus and lenticular nucleus (N./)), optic thalamus (T.0), and corpora quad- 
rigemina—some fibres form connections with cells within this central gray matter. The fibres 
which proceed from the cortex through the corona radiata in a radiate direction constitute 
Meynert's first projection system. Besides these, the white substance also contains two other 
systems of fibres: (a) Commissural fibres, such as the corpus callosum and the anterior com- 
missure (c, c), which are supposed to connect the two hemispheres with each other; and (<$) a 
connecting or association system, whereby two different areas of the same side are connected 
together (a, a). The ganglionic gray matter of the basal ganglia forms the first stage in the 
course of a large number of the fibres. When they enter the central gray matter, they are 
interrupted in their course. According to Meynert, the corona radiata contains bundles of fibres 
from the corpus striatum (1, 1), lenticular nucleus (2, 2), optic thalamus (3, 3), and corpora 
quadrigemina (4, 4). 
The second projection system consists of longitudinal bundles of fibres, which proceed 
downwards and reach the so-called “ central gray tube,” which is the ganglionic gray matter 
reaching from the 3d ventricle through the aqueduct of Sylvius, and the medulla oblongata, to the 
lowest part of the gray matter of the spinal cord. It lines the inner surface of the medullary 
tube. It is the second stage in the course of the fibres extending from the basal ganglia to the 
central tubular gray matter. The fibres of this system must obviously vary greatly in length; 
some fibres end in the central gray mat- 
ter above the medulla oblongata, e.g., in 
the oculo-motor nucleus, while others 
reach to the level of the last spinal 
nerves. In the central gray matter, 
not only is the course of the fibres inter- 
rupted, but there is in it an increase in 
the number of fibres, for far more fibres 
proceed peripherally from the gray mat- 
ter of the medulla and spinal cord than 
are sent to it from the central gray matter 
of the brain. 
As to the arrangement of the fibres in 
this second system, the fibres descending 
from the caudate and lenticular nucleus 
(8, 8) are grouped into a special channel, 
which descends through the crusta of the 
cerebral peduncle, and enters the med- 
ulla oblongata, or (according to Flechsig) 
the pons. In the same way there pro- 
ceeds from the thalamus (S) and corpora 
quadrigemina (6, 6) a bundle which de- 
scends through the tegmentum (H) of 
the cerebral peduncle. Both sets of fibres 
—those in the crusta and in the tegmen- 
tum—come together in the cord. 
According to Wernicke, the lenticular 
nucleus and caudate nucleus are not the 
parts of the brain into which, from the 
cerebral cortex and through the corona, 
radiate fibres enter; but they are inde- 
pendent parts, analogous to the cortex, 
and from them fibres proceed. These 
fibres pass into the crusta and run along 
with those fibres proceeding from the 
thalamus and corpora quadrigemina. 
According to Meynert, the fibres which 
pass from the thalamus and corpora quadrigemina, through the tegmentum of the cerebral pedun- 
cle, are reflex channels; so that these portions of the brain are centres for certain extensive, co- 
fig- 565- 
Floor ot the 4th ventricle and the connections of the 
cerebellum. On the left side the three cerebellar 
peduncles are cut short; on the right the connec- 
tions of the superior and inferior peduncles have 
been preserved, while the middle one has been cut 
short. I, median groove of the 4th ventricle with 
the fasciculi teretes; 2, the striae of the auditory 
nerve on each side emerging from it; 3, inferior 
peduncle; 4, posterior pyramid and clava, with the 
calamus scriptorius above it; 5, superior peduncle; 
6, fillet to the side of the crura cerebri; 8, corpora 
quadrigemina. 824 
CONNECTIONS OF THE CEREBELLUM. 
[Sec. 365. 
ordinated reflexes. This is shown by the fact that, after destruction of the voluntary motor paths 
in animals, the technical completeness of movements, so far as these are discharged reflexly, is 
still intact. These channels run in the spinal cord, at first on the side (/»), and probably 
ultimately cross in the spinal cord itself. 
The Third Projection System.—Lastly, from the central tubular gray matter there pro- 
ceeds the third system, or the peripheral nerves, motor and sensory. These are more numer- 
ous than the fibres of the second system. 
[While there are three concentric tubes in the spinal cord ($ 359), in the part which forms 
the brain an extra layer of gray matter is added—the peripheral gray tube—constituting the 
cortex of the cerebral hemispheres and cerebellum, and the corpora quadrigemina. Thus, the 
white matter lies between two concentric masses of gray matter (Hill).] 
Connections of the Cerebellum.—The cerebellum consists of two some- 
what flattened hemispheres connected across the middle line by the middle 
lobe or vermiform process, which is the fundamental portion of the organ, as 
it is best developed in lower animals, while as yet the lateral lobes are but 
small or absent, e. g., in birds. The surface is furrowed by sulci so as to cause 
it to resemble a series of folia, leaflets or laminae; larger fissures divide it 
into lobes. Peduncles.—The two superior peduncles connect it with 
the corpora quadrigemina and the crura cerebri. The fibres come from the 
lower part of the cerebellum and from its dentate nucleus, and a number of 
these fibres decussate in the upper part of the pons and the tegmentum, some 
of them becoming connected with the red nucleus in the tegmentum of the 
opposite side. Some of the fibres seem to connect the cerebellum with the 
frontal lobes, constituting a fronto-cerebellar tract, and they are also crossed 
{ Gowers). When the cerebellum is congenitally absent, these fibres are absent 
(.Flechsig). By the two inferior peduncles or restiform bodies, it is con- 
nected with all the columns of the spinal cord, and it is to be noted that some 
of the fibres forming these peduncles are connected with the olivary body 
of the opposite side, so that they decussate. The middle peduncle is 
formed by the transverse fibres of the pons (figs. 5x7, 566). It is evident 
that there is a cerebello-spinal as well as a cerebro-spinal connection to be 
considered. 
[The gray matter is external and the white internal, and on section the 
foliated branched appearance of the cerebellum constitutes the arbor vitez. 
Within each lateral lobe is a folded mass of gray matter like that in the olivary 
body, called the corpus dentatum, and from its interior white fibres pro- 
ceed. Stilling describes in the front part of the middle lobe roof-nuclei— 
so called because they lie in the roof of the 4th ventricle. As is shown in fig. 
565, the white fibres of the superior peduncle pass to the gray matter on the 
inferior surface of the cerebellum, while the inferior peduncular fibres pass to the 
superior surface, chiefly of the median part; but both are said to form 
connections with the corpus dentatum; the middle peduncle is connected with 
the gray matter of the lateral lobes. The minute structure is described in 
§ 38o.] 
The distribution of the blood-vessels of the brain is of much practical 
importance. The middle cerebral artery of the Sylvian fissure supplies the 
motor areas of the brain in animals; in man, the paracentral lobule is supplied 
by the anterior cerebral artery (Duret). The region of the third left frontal 
convolution, which is the speech-centre, is supplied by a special branch of the 
middle cerebral. According to Ferrier, that part of the brain, any injury to 
which causes disturbance of intelligence, is supplied by the anterior cerebral; 
while those regions, where injury is followed by hemi-anaesthesia, are supplied 
by the posterior cerebral. It is stated that anaemia of isolated parts of this 
area of the brain is associated with melancholia in man. 
Conduction to and from the cerebrum.—Voluntary motor fibres.— 
The course of the fibres which convey impulses for voluntary motion—the Sec. 365.] 
PYRAMIDAL TRACTS. 
825 
pyramidal tracts—proceeds from the motor regions of the cerebrum 
(§§ 375, 378, I), passing into and through the white matter of the cerebrum 
through the corona radiata (fig. 566, a, b, c), and converges to the internal 
capsule, which lies between the nucleus caudatus and opticus thalamus inter- 
nally and the lenticular nucleus externally (fig. 626). They enter the cerebral 
peduncle, and occupy the middle part of 
the circumference of the crusta (fig. 566, 
Pc), and pass through the pons on the same 
side, and from thence into the pyramids 
(Py) of the medulla oblongata. [The motor 
fibres for the face and tongue occupy the 
knee of the capsule, those for the arm the 
anterior third of the posterior segment or 
limb, and those for the leg the middle third 
(fig. 566). They pass beneath the optic 
thalamus, enter the crusta of the cerebral 
peduncle, and occupy its middle third, or 
two-fifths, extending almost to the substan- 
tia nigra, the fibres for the face being next 
the middle line, and those for the leg most 
external, the fibres for the arm lying be- 
tween the two. They pass into the pons on 
the same side, where the fibres for the face 
(and tongue) cross to the opposite side, to 
become connected with the nuclei from 
which the facial and hypoglossal nerves 
arise (fig. 566,/). The fibres for the arm 
and leg (and trunk) continue their course 
to the medulla oblongata, where they form 
the anterior pyramids. In the pons, the 
pyramidal tracts are broken up into bun- 
dles lying between its superficial and deep 
transverse fibres, and surrounded by gray 
matter (fig. 629); but they have no con- 
nection with the gray matter of the pons. 
By far the greater proportion of the fibres 
cross to the opposite side at the decussation 
of the pyramids, to form the crossed pyra- 
midal tracts, or lateral pyramidal tracts, 
of the lateral column of the opposite side 
(pc). The small uncrossed portion (fig. 
566, b) is continued as the direct pyra- 
midal tract (2) on the same side. The 
latter fibres, perhaps, supply those muscles 
of the trunk (e. g., respiratory, abdominal, 
and perineal), which always act together on 
both sides. According to other observers, 
however, they cross to the other side of the 
cord through the anterior white commissure, and descend in the crossed pyra- 
midal tract or pyramidal tract of the lateral column. The fibres of the pyra- 
midal tracts split up into fine fibrils, which come into connection with the fibrils 
produced by the subdivision of the processes of the multipolar nerve-cells. 
Thus, the pyramidal fibres come into connection with the multipolar ganglionic 
cells of the anterior cornu of the gray matter of the spinal cord at successively 
Fig. 566. 
Course of the fibres for voluntary move- 
ment. ab, path for the motor nerves 
of the trunk; c, fibres of the facial 
nerve; B, corpus callosum; Nc, nu- 
cleus caudatus; G.i, internal capsule; 
N.l, lenticular nucleus; P, pons ; N.f, 
origin of the facial; Py, Pyramids and 
their discussion; Ol, olive, Gr, resti- 
form body; PR, posterior root; AR, 
anterior root; x crossed and z direct 
pyramidal tracts. 826 
MOTOR IMPULSES. 
[Sec. 365. 
lower levels, and from each multipolar cell is directed peripherally a single 
unbranched axis-cylinder process, which ultimately becomes a nerve-fibre (fig. 
566, a). The pyramidal tracts thus end in, or at least come into connection 
with, the multipolar nerve-cells of the gray matter of the spinal cord, from 
which the anterior roots of the spinal nerves arise.] 
[The course of the pyramidal tracts, and the decussation of these fibres in 
the medulla oblongata, explain why a hemorrhage involving the cerebral motor 
centres, or affecting these fibres in any part of their course above the decussa- 
tion, results in paralysis of the muscles supplied by the fibres so involved on 
the opposite side of the body. In their passage through the brain, the paths for 
direct motor impulses are not interrupted anywhere in their course. by gan- 
glion-cells, not even in the corpus striatum or pons. They pass in a direct 
uninterrupted line, until each fibre becomes connected with—or at least its 
fibrils come into relation with—the processes of a multipolar nerve-cell in the 
anterior horn of the gray matter of the spinal cord, so that they have the 
longest course of any fibres in the central nervous system.] 
Variation in Decussation.—There are variations as to the number of fibres which cross at 
the pyramids (Flechsig). In some cases the usual arrangement is reversed, and in some rare 
instances there is no decussation, so that the pyramidal tracts from the brain remain on the same 
side. In this way we may explain the very rare cases where paralysis of the voluntary move- 
ments takes place on the same side as the lesion of the cerebrum (Morgagni, Pierret). This is 
direct paralysis. [Usually about 90 per cent, of the fibres decussate.] 
The motor cranial 
nerves also have centres in 
the cortex cerebri through 
which they are excited vol- 
untarily (§ 378). The paths 
for such voluntary impulses 
also pass through the in- 
ternal capsule and the crusta 
of the cerebral peduncle, 
but they lie in front of and 
internal to the pyramidal 
tracts. [In the internal 
capsule the fibres for the 
face (and tongue) lie in the 
knee, while they occupy the 
part of the middle of the 
crusta next the middle line. 
Their course is then direct- 
ed across the middle line 
to their respective nuclei, 
from which fibres proceed 
to the muscles supplied by 
these nuclei.] In fig. 5 66 
shows the course of the 
fibres to the facial centre. 
The exact course of many 
of the fibres is still un- 
known. The hypoglossal 
nerve runs with the pyra- 
midal tracts, and behaves 
like the anterior root of a spinal nerve (§§ 354, 357). 
[Sensory Paths.—Our knowledge is by no means precise. ' Sensory im- 
Course of the motor and sensory paths in a spinal segment. 
1, Anterior pyramidal tract; 3, crossed pyramidal tract; 
4 and 5, sensory paths decussating in the cord; 6, sensory 
paths which do not decussate in the cord ; 7, afferent 
paths leading to Clarke’s column and from thence passing 
as uncrossed fibres upwards via the direct cerebellar tract ; 
2, origin of a motor fibre from a ganglionic cell of the 
anterior cornu. 
Fig- 567- Sec. 365.] 
COURSE OF SENSORY IMPULSES. 
827 
pulses, passing into the cord, enter it by the posterior nerve-roots, and may 
pass to the cerebrum or cerebellum. There does not seem to be a direct termi- 
nation of the fibres of the posterior roots in the ganglionic cells of the gray 
matter of the spinal cord. The fibres always split up first into fibrils. If to 
the cerebellum, the course, probably, is partly to the direct cerebellar tract 
and posterior column to the restiform body, thence to the cerebellum. It is to 
be noted, however, that the fibres that proceed to the cerebellum do not do 
so directly. They enter the cord and run to come into relation with the cells 
of Clarke’s column, so that Clarke’s column of cells is their first terminal 
station, and from the cells of the latter fibres proceed which enter the direct 
cerebellar tracts (p. 801). If to the cere- 
brum, some of the fibres cross the middle 
line in the cord not far above where they enter 
and pass to the lateral column, in front of the 
pyramidal tract. Some enter the posterior col- 
umn, and others ascend in the gray matter to 
pass upwards. As the two subdivisions of the 
posterior column terminate above in the nuclei 
of the funiculus gracilis and funiculus cuneatus, 
and this column contains fibres from the pos- 
terior root, it is suggested that above the clava 
and cuneate nucleus the fibres cross in the 
superior pyramidal decussation to reach the 
pons and tegmentum. In the medulla, it is 
probable that those fibres which do not decus- 
sate there do so in the pons, the impulses per- 
haps travelling upwards in the formatio reticu- 
laris, thence into the posterior half of the pons, 
into the tegmentum of the crus under the cor- 
pora quadrigemina, to enter the posterior third 
of the posterior limb of the internal capsule 
(fig. 626, S). But, of course, the sensory 
fibres from the face have to be connected with 
the sensory centres in the cerebrum, so that 
the sensory paths from the cord, i.e., from the 
trunk and limbs, are joined by those from the 
face in the pons, and they also occupy part of 
the posterior third of the posterior segment of 
the internal capsule, so that this important part 
of the internal capsule conducts sensory im- 
pulses from the opposite half of the body. 
Some of the fibres pass into the optic thalamus, 
and others enter the white matter of the cere- 
brum, but their exact course is very uncertain. 
The sensory fibres derived from the organs of special sense, e.g., the ear, go 
to the superior temporo-sphenoidal convolution, but whether directly or indi- 
rectly we do not know; perhaps some of those for vision traverse the optic 
thalamus. Some of the afferent fibres perhaps go to the occipital region, and 
Gowers asserts that some of them go to the parietal and central regions, /.<?., 
to the “ motor ” regions, for he holds “ that disease of the motor cortex often 
causes impairment of the tactile sensibility.”] 
[Charcot has called the posterior third of the posterior segment of the inter- 
nal capsule, lying between the posterior part of the lenticular nucleus and 
the optic thalamus, the “ carefour sensitif” or “sensory crossway” (fig. 
626, S). If it be divided there is hemi-ansesthesia of the opposite side.] 
Course of the sensory impulses from 
the posterior roots through the cord 
to the brain. Compare fig. 569. 
A.R., anterior, and P.R., posterior 
roots; V.G., anterior ground bun- 
dle ; Py. V., direct pyramidal tract; 
Py.S., crossed pyramidal tract; 
G.S., lateral tract ground bundle ; 
JOl.S., direct cerebellar tract; G, 
Goll’s column; B, posteroexternal 
or Burdach’s column; Py, pyra- 
mids ; 01, olivary body; L, inter- 
olivary body or fillet. Arcuate fibres. 
Restiform body. Funiculus gra- 
cilis and funiculus cuneatus of the 
medulla oblongata. 
Fig. 568. 828 
CONDUCTING PATHS IN THE CORD. 
[Sec. 365. 
Fig. 569. 
Diagram of a spinal segment as a spinal centre and conducting medium. B, right, B7, left 
cerebral hemisphere; MO, lower end of medulla oblongata; i, motor tract from the right 
hemisphere, the larger part decussating at MO, and passing down the lateral column of the 
cord on the opposite side to the muscles M and M/; 2, motor tract from the left hemi- 
sphere; S, S', sensitive areas on the left side of the body; 3/, 3, the main sensory tract 
from the left side of the body—it decussates shortly after entering the cord; S2, S3, sen- 
sitive areas, and 4/, 4, tracts from the right side of the body. The arrows indicate the di- 
rection of the impulses (Bramwell). [Here all the sensory fibres are shown as crossingin 
the cord.] Sec. 365.] 
CROSSING OF IMPULSES IN THE CORD. 
829 
The posterior columns appear to conduct upwards sensory impulses 
reaching them from the posterior roots. The posterior root after entering the 
cord shows a division into a median and a lateral bundle. The median 
bundle of each posterior nerve-root as it ascends in the posterior column of 
its own side tends chiefly to pass outwards near to the posterior cornu (fig. 
568, 2). Each successively higher entering root (fig. 568, 1) tends to press 
inwards the fibres proceeding from the roots below it. Hence in the cervi- 
cal part of the cord the afferent fibres coming from the lower limbs lie chiefly 
in Goll’s column, while the postero-external column still contains many such 
fibres from the fore-limbs. The fibres of Goll’s column end in the nucleus 
of the clava, and those of the postero-external column in the nucleus 
cuneatus of the bulb. From these nuclei many fibres proceed to enter the 
fillet or lemniscus (fig. 568, L) of the opposite side (Edinger, Flechsig). 
Some of the fibres are said to pass to the cerebellum. 
[Of the sensory impulses which pass into the cord some cross over to the 
opposite side ; in the cord at higher levels than the plane on which they enter 
are other fibres. Other impulses, however, are conducted by fibrils which re- 
main on the same side of the cord as that on which they enter. They reach 
the nucleus gracilis and nucleus cuneatus. From these nuclei fibres pass off 
which pass forward through the gray matter of the bulb, and decussate with 
those of the opposite side. These fibres pass to the fillet or inter-olivary layer, 
and this constitutes the supra-pyramidal decussation of sensory impulses 
passing to the cerebrum (fig. 571, d.a.'). This decussation of sensory fibres is 
best made out in a foetus of seven months (.Edinger). Thus some sensory im- 
pulses decussate in the cord and others in the bulb.] 
The lateral bundles of the nerve-roots, composed of coarse and fine fibres 
(fig. 568, 3, 4), enter the gray matter of the posterior cornu ( Gerlach, Lissauer), 
and some of them appear to split up into fibres in the gray matter of their own 
side, while other fibres cross and ascend in the anterior and lateral columns. 
At the level of the bulb these fibres come to lie, along with their original com- 
panions, in the fillet or interolivary body (fig. 568, 4), so that almost all the 
fibres of the posterior roots lie together, but on the opposite side of the body 
(.Edinger). A number of the fibres of the posterior root (fig. 568, 5) appear to 
end in connection with the cells of Clarke’s vesicular column, which is their 
nutritive or trophic centre. From Clarke’s column fibres proceed which pass out- 
wards and upwards in the direct cerebellar tract of the same side. These fibres 
pass to the restiform body and thence to the cerebellum. These fibres are con- 
cerned with the regulation of the equilibrium of the body, and they, together 
with the cells of Clarke’s column, are often diseased in locomotor ataxia. 
Sensory Decussation in Cord.—As the greater part of the sensory fibres 
from the skin decussate in the spinal cord, and thus pass to the opposite 
side of the cord (fig. 569), unilateral section of the spinal cord in man (and 
monkey—Ferrier) abolishes sensibility on the opposite side below the lesion. 
There is hyperaesthesia of the parts below the seat of the section on the side of 
the injury (§ 363). From experiments on mammals, Brown-Sequard concludes 
that the decussating sensory nerve-fibres pass to the opposite side within the 
cord at different levels, the lowest being the fibres for touch, then those for 
tickling and pain, and, highest of all, those which administer to sensations of 
temperature. 
All the fibres, therefore, which connect the spinal cord with the gray matter 
of the brain, undergo a complete decussation in their course. Hence, in man 
a destructive affection of one hemisphere usually causes complete motor paralysis- 
and loss of sensibility on the opposite side of the body.. The fibres proceeding 
from the nuclei of origin of the cranial nerves also cross within the cranium. MEDULLA OBLONGATA. 
[Sec. 365. 
Not unfrequently the motor paralysis and anaesthesia occur on the same side of the head, in 
which case the lesion (due to pressure or inflammation) involves the cranial nerves lying at the 
base of the brain. 
The positions of decussation are (1) in the spinal cord, (2) in the me- 
dulla oblongata, and lastly (3) in the pons. The decussation is complete in 
the peduncle. 
Alternate Paralysis.—Gubler observed that unilateral injury to the pons caused paralysis of 
the facial nerve on the same side, but paralysis of the opposite half of the body. He concluded 
that the nerves of the trunk decussate before they reach the pons, while the facial fibres decussate 
within the pons. To these rare cases the name “ alternate hemiplegia ” is given. [When hemor- 
rhage takes place into the lower part of the lateral half of the pons, there may be alternate 
paralysis, but when the upper part of the lateral half is injured, the facial is paralyzed on the 
same side as the body, \ 379.] 
The olfactory nerve is said not to decussate (?), while the optic nerve undergoes a partial de- 
cussation at the chiasma (§ 344). Some observers assert that the fibres of the trochlearis decus- 
sate at their origin. 
Fig. 570. 
Section of the decussation of the pyramids. Jia, anterior median fissure, displaced laterally by 
the fibres decussating at d; V, anterior column; Ca, anterior cornu, with its nerve-cells, 
a, b; cc, central canal; S, lateral column; fr, formatio reticularis; ce, neck, andg, head 
of the posterior cornu; rpCI, posterior root of the 1st cervical nerve; nc, first indication 
of the nucleus of the funiculus cuneatus; ng, nucleus (clava) of the funiculus gracilis; H1, 
funiculus gracilis; H2, funiculus cuneatus; sip, posterior median fissure; x, groups of gan- 
glionic cells in the base of the posterior cornu. X 6. 
366. THE MEDULLA OBLONGATA OR BULB—[Structure. 
—In the medulla oblongata, the fibres from the cord are rearranged, the gray 
matter is also much changed, while new gray matter is added. Each half of the 
medulla oblongata consists of the following parts, from before backwards: The 
anterior pyramid, olivary body, restiform body, and posterior pyra- 
mid, or funiculus gracilis (figs. 570, 571, 572). By the divergence of the pos- 
terior pyramids and the restiform bodies, the floor of the 4th ventricle is ex- 
posed. As the central canal of the cord gradually comes nearer to the posterior 
surface of the medulla, it opens into the 4th ventricle. At the lower end of Sec. 366.] 
MEDULLA OBLONGATA. 
831 
the medulla oblongata, on separating the anterior pyramids, we may see the 
decussation of the pyramids, where the fibres cross over to the lateral 
columns of the cord. The anterior pyramid receives the direct pyramidal tract 
of the anterior column of the cord from its own side, and the crossed pyramidal 
tract from the lateral column of the cord of the opposite side (fig. 570). The 
decussating fibres (crossed pyramidal tract) of the lateral column pass across in 
bundles to form the decussation of the pyramids. Most of the pyramidal fibres 
pass through the pons directly to the cerebrum, a few fibres pass to the cere- 
bellum, while some join fibres proceeding from the olivary body to form the 
olivary fasciculus or fillet.] 
[Thus only a part of the anterior column of the cord—direct pyramidal 
tract—is continued into the anterior pyramid, where it lies external to the 
fibres which pass to the lateral column of the opposite side. The remainder of 
the anterior column—the antero-external fibres—are continued upwards, but 
lie deeper under cover of the anterior-pyramid, where they serve to form part 
of the formatio reticularis (p. 833).] 
[Of the fibres of the lateral column of the cord, some, the direct cerebel- 
lar tract, pass backwards to join the restiform body and go to the cerebellum. 
These fibres lie as a thin layer on the surface of the restiform body. The 
crossed pyramidal fibres cross obliquely, at the lower end of the medulla, to the 
anterior pyramid of the opposite side, and in their course they traverse the gray 
matter of the anterior cornu (fig. 570, py). These fibres form the larger and 
mesial portion of the anterior pyramid. The remaining fibres of the lateral 
columns are continued upwards, and pass beneath the olivary body, where they 
are concealed by this structure and also by the arcuate fibres, but they appear 
in the floor of the medulla oblongata and are here known as the fasciculus teres, 
which goes to the cerebrum. As they pass upwards, they help to form the 
lateral part of the formatio reticularis.] 
[The posterior pyramid of the oblongata is merely the upward continu- 
ation of the postero-median column, or funiculus gracilis of the cord. As it 
passes upwards at the medulla it broadens out, forming the clava, which 
tapers away above. The clava contains a mass of gray matter—the clavate 
nucleus.] 
[The restiform body consists partly of the upward continuation of the 
postero-external column or funiculus cuneatus of the cord. The funiculus 
cuneatus contains a mass of gray matter, called the cuneate or triangular 
nucleus. Some of the fibres emerging from this nucleus pass to join the resti- 
form body. Above the level of the clava, the funiculus cuneatus forms part of 
the lateral boundary of the 4th ventricle. Immediately outside this, i. e., be- 
tween it and the continuation of the posterior nerve-roots, is a longitudinal 
prominence, which Schwalbe has called the funiculus of Rolando. It is 
formed by the head of the posterior cornu of gray matter coming nearer the 
surface. It also forms part of the restiform body. Some arcuate fibres issue 
from the anterior median fissure, turn transversely outwards over the anterior 
pyramids and olivary body, and pass along with the funiculus cuneatus, the 
funiculus of Rolando, and the direct cerebellar fibres, to enter the correspond- 
ing lateral lobe of the cerebellum, all these structures forming its inferior 
peduncle. Some observers suggest that the funiculus cuneatus and funiculus of 
Rolando do not pass into the cerebellum.] 
[The olivary body or inferior olive forms a well-marked oval or olive-shaped body, which 
does not extend the whole length of the medulla (fig. 572, 0). Above, it is separated from the 
pons by a groove from which the 6th nerve emerges. In the groove between it and the anterior 
pyramid arise the strands of the hypoglossal nerve, while in a corresponding groove along its 
outer surface is the line of exit of the vagus, glosso-pharyngeal, and spinal accessory nerves. 832 
MEDULLA OBLONGATA. 
[Sec. 366. 
It is covered on its surface by longitudinal and arcuate fibres, while in its interior it contains the 
dentate or olivary nucleus.] 
The olivary nucleus is a flask-shaped structure, with folded walls and with a wide open mouth 
towards the middle line (fig. 571, 0). It consists of small rounded nerve-cells embedded in a 
basis of neuroglia and nerve-tissue. Immediately internal and dorsal to it is the internal par- 
olivary body or accessory olivary nucleus (fig. 572, oam), and external to it is the external 
accessory nucleus (fig 572, oal). The ninth nerve (fig. 572, XII) runs between the inner 
accessory nucleus and the olivary body itself. 
[The functions of the olivary bodies are quite unknown, but it is important to remember 
that these organs are connected by fibres with the dentate nuclei of the cerebellum. Fibres pass 
into the olivary body from the posterior column of the cord of the opposite side, and it is also 
connected with the dentate body of the opposite side, while, as we know, the dentate body is 
connected with the tegmentum, so that through the left dentate body of the opposite side, the 
tegmentum of, say, the right crus, is connected with the right olivary body (Gowers). In young 
animals removal of the half of the cerebellum causes atrophy of the olivary nucleus of the 
opposite side.] 
Fig. 571.—Section of the medulla oblongata at the so-called upper decussation of the pyramids. 
fl.a, anterior, s.l.p, posterior median fissure ; n.XI, nucleus of the accessorius vagi; n.XII, 
nucleus of the hypoglossal; da, the so-called superior or anterior decussation of the pyra- 
mids; py, anterior pyramid ; n.ar, nucleus arciformis ; o1, median parolivary body ; 0, be- 
ginning of the nucleus of the olivary body; n.l, nucleus of the lateral column; F.r, for- 
matio reticularis; g, substantia gelatinosa, with (a. V) the ascending root of the trigeminus; 
nc, nucleus of the funiculus cuneatus; n.c1, external nucleus of the funiculus cuneatus; 
ng, nucleus of the funiculus gracilis (or clava): H1, funiculus gracilis; H2, funiculus 
cuneatus; canal; f.a, fa1, fa2, external arciform fibres. X 4. Fig. 572.— 
Section of the medulla oblongata through the olivary body. n.XII, nucleus of the hypo- 
glossal; nX, nX1, more or less cellular parts of the nucleus of the vagus; XII, hypoglos- 
sal nerve; X, vagus; n.am, nucleus ambiguus; n.l, nucleus lateralis; 0, olivary nucleus; 
oal, external, and oatn, internal parolivary body; f.s, the round bundle, or funiculus soli- 
tarius; C.r, restiform body; p, anterior pyramid, surrounded by arciform fibres; f.a.e,p.o.l, 
fibres proceeding from the olive to the raphe (pedunculus olivse); r, raphe. X 4. 
Fig. 571- 
Fig. 572. 
[Decussation of the pyramids is the term given to those fibres which 
cross obliquely in several bundles, at the lower part of the medulla, from the 
anterior pyramid of the medulla into the lateral column of the cord of the 
opposite side (fig. 570, </) to form its lateral pyramid tracts, or crossed pyra- 
midal tracts. The number of fibres which decussate varies, and in some rare 
cases all the fibres may cross.] Sec. 366.] 
MEDULLA OBLONGATA. 
833 
[The gray matter of the medulla is largely a continuation of that of the cord, although it is 
arranged differently. As the fibres from the lateral column of the cord pass over to form part 
of the anterior pyramid of the medulla on the opposite side, they traverse the gray matter, 
and thus cut off the tip of the anterior cornu, which is also pushed backwards by the olivary 
body, and exists as a distinct mass, the nucleus lateralis (fig. 572, nt). Part of the anterior 
gray matter also appears in the floor of the 4th ventricle as the eminence of the fasciculus teres, 
and from part of it springs the hypoglossal nerve (fig. 571, XI/). The neck joining the modi- 
fied anterior and posterior cornua is much broken up by the passage of longitudinal and trans- 
verse fibres through it, so that it forms a formatio reticularis, separating the two cornua (fig. 
571 ,fr). The caput cornu posterioris comes to be covered higher up by the ascending root of 
the 5th nerve (fig. 571,a V), and arcuate fibres passing to the restiform body. The posterior cornu 
is also broken up and is thrown outwards, its caput giving rise to part of the elevation seen on 
the surface and described as the funiculus of Rolando, while part of the base now greatly 
enlarged forms the gray matter in the funiculus gracilis [clavate nucleus] (fig. 570, ng) and funi- 
culus cuneatus [cuneate or triangular nucleus] (fig. 570, nc). Nearer the middle line the gray 
matter of the posterior gray cornu appears in the floor of the 4th ventricle, above the point where 
the central canal opens into it, as the nuclei of the spinal accessory, vagus, and glosso-pharyngeal 
nerves.] 
[In the floor of the 4th ventricle near the raphe, and quite superficial, is a longitudinal mass 
of large multipolar nerve-cells, derived from the base of the anterior cornu from which spring 
the several bundles forming the hypoglossal nerve; it is the hypoglossal nucleus (figs. 572, 
n.XII, 573), the nerve-fibres passing obliquely outwards to appear between the anterior pyramid 
and the olivary body. Internal to it, and next the median groove, is a small mass of cells con- 
tinuous with those in the raphe, and called the nucleus of the funiculus teres (fig. 572, n.t). 
Around the central canal at the lower part of the medulla is a group of cells (fig. 572, n.XI), 
which becomes displaced laterally as it comes nearer the surface in the floor of the medulla 
oblongata, where it lies outside the hypoglossal nucleus, and corresponds to the prominence of the 
ala cinerea (fig. 572, n.X); and fron\ it and its continuation upwards arise from below upwards 
part of the spinal accessory (nth), and the vagus (10th, corresponding to the position of the 
eminentia cinerea—fig. 572, X), so that this column of cells forms the vago-accessorius 
nucleus. External to and in front of this is the nucleus for the glosso-pharyngeal nerve. 
Further up in the medulla, on a level with the auditory striae and outside the previous column, is 
a tract of cells from which the auditory -nerve (8th) in great part arises; it is the principal 
auditory nucleus, and lies just under the commencement of the inferior cerebellar peduncle 
(fig. 516, 8/, 8", 8///). It consists of an outer and inner nucleus, which extend to the middle 
line. It forms connections with the cerebellum, and some fibres are said to enter the inferior 
cerebellar peduncle. This is an important relationship, as we know that the vestibular branch 
of the auditory nerve comes partly from the semi-circular canals, so that in this way these organs 
may be connected with the cerebellum.] 
[Superadded Gray Matter.—There is a superadded mass of gray matter not represented 
in the cord, that of the olivary body enclosing a nucleus, the corpus dentatum, with its wavy 
strip of gray matter containing many small multipolar nerve-cells embedded in neuroglia. The 
gray matter is covered on the surface by longitudinal and transverse fibres. It is open towards 
the middle line (hilum), and into it run white fibres forming its peduncle (fig. 572,p, 0, /). 
These fibres diverge like a fan, some of them ending in connection with the small multipolar 
cells of the dentate body, while others traverse the lamina of gray matter and pass backwards 
to appear as arcuate fibres which join the restiform body; others, again, pass directly through 
to the surface of the olivary body, which they help to cover as the superficial' arcuate fibres. 
The accessory olivary nuclei (fig. 571, o', 0") are two small masses of gray matter similar to 
the last, and looking as if they were detached from it, one lying above and external, sometimes 
called the parolivary body and the other slightly below and internal to the olivary nucleus, the 
latter being separated from the dentate body by the roots of the hypoglossal nerve. The latter 
is sometimes called the internal parolivary body, or nucleus of the pyramid.] 
The formatio reticularis occupies the greater part of the central and lateral parts of the 
medulla, and is produced by the intercrossing of bundles of fibres running longitudinally and 
more or less transversely in the medulla (fig. 571 ,fr). In the more lateral portions are large 
multipolar nerve-cells, perhaps continued upwards from part of the anterior cornu, while the 
part next the raphe has no -such cells. The longitudinal fibres consist of the upward prolonga- 
tion of the antero-external columns of the cord, while some seem to arise from the clavate nuclei 
and olives as arcuate fibres passing upwards. Just above the decussation of the pyramids, some 
fibres proceed from the clava, and cuneate nuclei, and pass round the central gray matter, and 
decussate between this and the anterior fissure (p. 829). They form connections between these 
two nuclei and parts of the brain above, and they form the superior decussation or sensory 
decussation. In the lateral portions the longitudinal fibres are the direct continuation upwards 
of Flechsig’s antero-lateral mixed tracts of the lateral columns (p. 800). The horizontal fibres 834 
MEDULLA OBLONGATA. 
[Sec. 366. 
are formed by arcuate fibres, some of which run more or less transversely outwards from the 
raphe. The superficial arcuate fibres (fig. 572,/, a, e) appear in the anterior median fissure, and 
perhaps come through the raphe from the opposite side of the medulla, curve round the anterior 
pyramids, form a kind of capsule for the olives, and join the restiform body (p. 831), but they 
are reinforced by some of the deep arcuate fibres which traverse the olivary body (p. 833). The 
deep arcuate fibres run from the clavate and triangular nuclei horizontally inwards to the raphe, 
and cross to the other side; others pass from the raphe to the olivary body, and through it to the 
restiform body in the raphe, which contains nerve-cells, some fibres run transversely, others 
longitudinally, and others from before backwards.] 
[Other Nerve Nuclei—Sixth Nerve.—Under the elevation called eminentia teres (fig. 516) 
in front of the auditory striae, close to the mid- 
dle line, is a tract of large multipolar nerve- 
cells. It was once thought to be the common 
nucleus of the 6th and 7th facial nerves, but 
Gowers has shown that “ the facial ascends to 
this nucleus, forms a loop round it (some 
fibres indeed go through it), and then passes 
downwards, forwards, and outwards, to a col- 
umn of cells more deeply placed in the medulla 
than any other nucleus in the lower part.” 
But the 7th has no real origin from this 
nucleus. Facial Nerve.—The nucleus lies 
deep in the formatio reticularis of the pons 
under the floor of the 4th ventricle, but outside 
the position of the nucleus of the 6th (figs. 
516, 520, 573). It extends downwards about 
as far as the auditory striae, or a little lower. 
The fifth nerve arises from its motor nu- 
cleus (with large multipolar cells), which lies 
more superficially above and external to the 
6th (fig. 573, 5). The fibres run backwards, 
where they are joined by fibres from the upper 
sensory nucleus, but another sensory nucleus 
extends down nearly to the lower end of the 
medulla (5//). Doubtless this extensive origin 
brings this nerve into intimate relation with the 
other cranial nerves, and accounts for the 
numerous reflex acts which can be discharged 
through the fifth nerve. Some sensory fibres 
are said to pass up beneath the corpora quad- 
rigemina (Gowers). The fourth nerve arises 
from the valve of Vieussens, i. <?., the lamina 
of white and gray matter which stretches be- 
tween the superior cerebellar peduncles. It 
arises, therefore, behind the 4th ventricle (fig. 
516), but some of the fibres spring from nerve- 
cells at the lower part of the nucleus of the 
3d nerve. Some fibres also descend in the 
pons to form a connection with the nucleus 
of the 6th nerve. The fibres decussate behind 
the aqeduct, so that in it alone, of all the cranial 
nerves, decussation occurs between its nucleus 
and its superficial origin (Gowers). The third 
nerve arises from a tract of cells beneath the 
aqueduct and near the middle line, and the 
fibres descend through the tegmentum to ap- 
pear at the inner side of the crus cerebri. Gowers points out that, in reality, there are three dis- 
tinct functional centres, (1) for accommodation (ciliary muscle), (2) for the light reflex of the 
iris, and (3) most of the external muscles of the eyeball. It is important to notice the connec- 
tion between the nuclei of the 3d, 4th, and 6th nerves, in relation to the innervation of the 
ocular muscles.] 
[When we trace up the tracts from the cord to the medulla oblongata, two tracts at least pass 
through the bulb without forming connections with its structures to higher parts, viz., the 
pyramidal tracts to the cerebrum and the direct cerebellar tract to the cerebellum. Perhaps 
all the other longitudinal fibres of the cord form connections with some parts of the medulla 
Fig. 573- 
Schematic projection of the medulla oblongata. 
Po, pons; Brcj, superior cerebellar ped- 
uncles ; Va, ascending; Vc, descending; 
Vm, motor; Vs, sensory roots of the fifth 
nerve; NVm, motor; NVs, sensory trige- 
minal nucleus; NVII, facial nucleus; VII 
a, b, c, facial root; VII, point of exit of 
facial nerve; NVI, nucleus of abducens; 
IX, a, ascending glosso-pharyngeal root; 
IX, its point of exit; No, olivary nucleus; 
X, vagus (or glosso-pharyngeal nerve), with 
the origin of certain fine fibres in the nucleus 
ambiguus; Na', Ca, anterior cornu of the 
spinal cord; Ca, Na, NVII, NVm, column 
of motor nuclei; NXII, nucleus of hypo- 
glossal nerve. Sec. 366.] 
FUNCTIONS OF THE BULB. 
835 
oblongata, thus the fibres of Goll’s column end in the cells of the clava or gracilis nucleus, 
and those of the postero-external column with the cells of the cuneate nuclei. By means of 
these nuclei, the fibres of the posterior columns of the cord form indirect connections with the 
cerebrum and cerebellum. Fibres proceed from both nuclei to form the superior decussation— 
which after decussation form the inter-olivary layer, which is continued into and forms the 
chief part of the longitudinal bundle known as the fillet, which is continued to the brain. 
Some fibres proceed from these two nuclei, decussate, and appear as external arcuate fibres, 
which join the restiform body and thus pass to the cerebellum. It has also been suggested 
that these two nuclei are connected with the cerebellum of the same side.] 
Functions of the Bulb.—The medulla oblongata, which connects 
the spinal cord with the brain, has many points of resemblance with the 
former. [Like the cord, it is concerned (i) in the conduction of im- 
pulses.] (2) In it, numerous reflex centres are present, e.g., for simple 
reflexes similar to the nerve-centres in the spinal cord, e.g., closure of the 
eyelids, [so that they subserve the transference of the afferent into efferent 
impulses]. There are other centres which seem to dominate or control simi- 
lar centres placed in the cord, e.g., the great vaso-motor centre, the sweat- 
secreting, pupil-dilating centres, and the centre for combining the reflex move- 
ments of the body. Some of the centres are capable of being excited re- 
flexly (§ 358, 2). (3) It is also said to contain automatic centres (§ 358, 3). 
The normal functions of the centres depend upon the exchanges of blood- 
gases, effected by the circulation of the blood through the medulla. If this 
gaseous exchange be interrupted or interfered with, as by asphyxia, sudden 
anaemia, or venous congestion, these centres are first excited, and exhibit 
a condition of increased excitability, and at last, if they are over-stimulated, 
they are paralyzed. An excessive temperature also acts as a stimulus. 
All the centres, however, are not active at the same time, and they do not 
all exhibit the same degree of excitability. Normally the respiratory centre 
and the vaso-motor centre are continually in a state of rhythmical activity. 
In some animals, the inhibitory centre of the heart remains continually non- 
excited; in others it is stimulated very slightly under normal conditions 
simultaneously with the stimulation of the respiratory centre, and only during 
inspiration. The spasm centre is not stimulated under normal conditions; 
and during intra-uterine life the respiratory centre remains quiescent. The- 
medulla oblongata, therefore, contains a collocation of nerve-centres which 
are essential for the maintenance of life, as well as various conducting paths of 
the utmost importance. We shall treat of the reflex, and afterwards of the 
automatic centres. 
367. REFLEX CENTRES OF THE MEDULLA OBLON- 
GATA.—The medulla oblongata contains a number of reflex centres, which 
minister to the discharge of a large number of co-ordinated movements. 
1. Centre for Closure of the Eyelids.—The sensory branches of the 5th 
cranial nerve to the cornea, conjunctiva, and the skin in the region of the eye, 
are the afferent nerves. They conduct impulses to the medulla oblongata, 
where they are transferred to, and excite part of, the centre of the facial nerve, 
whence, through branches of the facial, the efferent impulses are conveyed to 
the orbicularis palpebrarum. The centre extends from about the middle of the 
ala cinerea upwards to the posterior margin of the pons (Nickell). 
The reflex closure of the eyelids always occurs on both sides, but closure may be produced 
voluntarily on one side (winking). When the stimulation is strong, the corrugator and other 
groups of muscles which raise the cheek and nose towards the eye may also contract, and so 
form a more perfect protection and closure of the eye. Intense stimulation of the retina causes 
closure of the eyelids [and in this case the shortest reflex known, the latent period, is 0.05 
second (Waller)]. 
2. Sneezing Centre.—The afferent channels are the internal nasal 836 
CENTRES IN THE CORD. 
[Sec. 367. 
branches of the trigeminus and the olfactory, the latter in the case of intense 
odors. The efferent or motor paths lie in the nerves' for the muscles of 
expiration (§§ 120, 3, and 347, II). Sneezing cannot’ be performed volun- 
tarily, [but it may be inhibited by compressing the nasal nerve at its exit on 
the nose]. 
3. Coughing Centre.—According to Kohts, it is placed a little above the 
inspiratory centre ; the afferent paths are the sensory branches of the vagus 
(§ 352> 5> «)• The efferent paths lie in the nerves of expiration and those 
that close the glottis (§ 120, 1). 
4. Centre for Sucking and Mastication.—The afferent paths lie in 
the sensory branches of the nerves of the mouth and lips (2d and 3d branches 
of the trigeminus and glosso-pharyngeal). The efferent nerves for sucking are 
(§ 152) : Facial for the lips, hypoglossal for the tongue, the inferior maxillary 
division of the trigeminus for the muscles which elevate and depress the jaw. 
For the movements of mastication, the same nerves are in action (§ 153) ; but 
when food passes within the dental arch, the hypoglossal is concerned in the 
movements of the tongue, and the facial for the buccinator. 
Centre for the secretion of saliva (p. 256) lies in the floor of the 4th 
ventricle. Stimulation of the medulla oblongata causes a profuse secretion of 
saliva when the chorda tympani and glosso-pharyngeal nerves are intact, a much 
feebler secretion when the nerves are divided, and no secretion at ail when the 
cervical sympathetic is extirpated at the same time (Griitzner). 
6. Swallowing centre lies in the floor of the 4th ventricle (§ 156).—The 
afferent paths lie in the sensory branches of the nerves of the mouth, palate, 
and pharynx (2d and 3d branches of the trigeminus, glosso-pharyngeal, and 
vagus) ; the efferent channels, in the motor branches of the pharyngeal plexus 
(§ 352, 4). Stimulation of the glosso-pharyngeal nerve does not cause degluti- 
tion; on the contrary, this act is inhibited (p. 278). Hence every act of 
deglutition excited by stimulation of the palatal nerves or of the superior 
laryngeal nerve is followed by a feeble abortive contraction of the diaphragm 
(.Marckwald). 
According to Steiner, every time we swallow there is a slight stimulation of the respiratory 
centre, resulting in a contraction of the diaphragm. [Kronecker has shown that if a glass of 
water be sipped slowly, the action of the cardio-inhibitory centre is interfered with reflexly, so 
that the heart beats much more rapidly, whereby the circulation is accelerated, hence probably 
the reason why sipping an alcoholic drink intoxicates more rapidly than when it is quickly 
swallowed (p. 278).] 
7. Vomiting Centre (§ 158).—The relation of certain branches of the 
vagus to this act are given at § 352, 2, and 12, d. 
8. The upper centre for the dilator pupillae muscle, the smooth mus- 
cles of the orbit, and the eyelids lies in the medulla oblongata. The fibres pass 
out partly in the trigeminus (§ 347, I, 3), partly in the lateral columns of the 
spinal cord as far down as the cilio-spinal region, and proceed by the two 
lowest cervical and the two upper dorsal nerves into the cervical sympathetic 
(§ 356, A, 1). The centre is normally excited reflexly by shading the retina, 
i. e., by diminishing the amount of light admitted into the eye. It is directly 
excited by the circulation of dyspnceic blood in the medulla. (The centre for 
contracting the pupil is referred to at §§ 345 and 392.) 
The centre may be excited reflexly by stimulation of a sensory nerve, e.g., the sciatic. These 
afferent fibres pass upwards through both lateral columns to their centre (/Cowalewsky). 
9. There is a subordinate centre in the medulla oblongata, which seems to be 
concerned in bringing the various reflex centres of the cord into relation with 
each other. Owsjannikow found that, on dividing the medulla 6 mm. above 
the calamus scriptorius (rabbit), the general reflex movements of the body still Sec. 367.] 
RESPIRATORY CENTRE. 
837 
occurred, and the anterior and posterior extremities participated in such general 
movements. If, however, the section was made i mm. nearer the calamus, 
only local partial reflex actions occurred (§ 360, III, 4) [thus, on stimulating 
the hind-leg, the fore-legs did not react—the transference of the reflex was 
interfered with]. The centre reaches upwards to slightly above the lowest 
third of the oblongata. 
The medulla in the frog also contains the general centre for movements from 
place to place. Section of this region abolishes the power to move from place 
to place; when external stimuli are applied, there remains only simple reflex 
movements {Steiner). No reflex movements, such as springing, creeping, or 
swimming, involving a change of place, result. 
Pathological.—The medulla oblongata is sometimes the seat of a typical disease, known as 
bulbar paralysis, or glosso-pharyngo-labial paralysis (Duchenne, i860), in which there is a 
progressive invasion of the different nerve-nuclei (centres) of the cranial nerves which arise 
within the medulla, these centres being the motor portions of an important reflex apparatus. 
Usually, the disease begins with paralysis of the tongue, accompanied by fibrillar contractions, 
whereby speech, formation of the food into a bolus, and swallowing are interfered with ($ 354). 
The secretion of thick, viscid saliva points to the impossibility of secreting a thin watery facial 
saliva ($ 145, A), owing to paralysis of this nerve-nucleus. Swallowing may be impossible, 
owing to paralysis of the pharynx and palate. This interferes with the formation of consonants 
[especially the linguals, l, t, s, r, and, by and by, the labial explosives, b, p ] (§ 318, C); the 
speech becomes nasal, while fluids and solid food often pass into the nose. Then follows 
paralysis of the branches of the facial to the lips, and there is a characteristic expression of the 
mouth “ as if it were frozen.” All the muscles of the face may be paralyzed ; sometimes the 
laryngeal muscles are paralyzed, leading to loss of voice and. the entrance of food into the wind- 
pipe. The heart-beats are often retarded, pointing to stimulation of the cardio inhibitory fibres 
(arising from the accessorius). Attacks of dyspnoea, like those following paralysis of the recur- 
rent nerves (§ 313, II, 1, and \ 352, 5, b), and death may occur. Paralysis of the muscles of 
mastication, contraction of the pupil, and paralysis of the abducens are rare. [This disease is 
always bilateral, and it is important to note that it affects the nuclei of those muscles that guard 
the orifices of the mouth, including the tongue, the posterior nares, including the soft palate, and 
the rima glottidis with the vocal cords.] 
368. RESPIRATORY MOVEMENTS AND CENTRE.—In- 
nervation of the Respiratory Organs.—[A respiratory act requires the 
nicely co-ordinated action of many voluntary muscles under the influence of a 
nerve-centre. Normally the act of respiration is involuntary, although the 
muscles which execute the act are voluntary, and may be influenced by a direct 
act of the will. Respiration goes on even when we are asleep and unconscious, 
and it may still be carried on if all the parts of the brain above a certain part 
of the medulla oblongata be removed. The co-ordinated impulses proceed 
from the respiratory centre in the medulla oblongata via the nerves which sup- 
ply the muscles of respiration and the movements which are associated with the 
thoracic respiratory movements, e.g., those of the face, nose, and larynx.] 
[Section of the cord below the level of the fifth cervical nerve, i. e., below 
the origin of the roots of the phrenic nerves, causes arrest of the costal respira- 
tion, although the movements of the diaphragm continue. Section of the cord 
just below the medulla oblongata or bulb causes arrest not only of the costal 
movements, but also of those of the diaphragm, because the section is above 
the level of origin of the roots of the phrenic nerves. The respiratory move- 
ments, however, in the face—the muscles supplied by the seventh nerve—and 
those of the larynx (supplied by the vagus) still continue. Section of one 
phrenic nerve paralyzes the diaphragm on that side, and section of both 
phrenics paralyzes both sides of the diaphragm.] 
The respiratory centre lies in the medulla oblongata or bulb (.Legal- 
lois, 1811), behind the superficial origin of the vagi, on both sides of the pos- 
terior aspect of the apex of the calamus scriptorius, between the nuclei of the 838 
RESPIRATORY CENTRE. 
[Sec. 368. 
vagus and accessorius, and was named by Flourens the vital point, or nceud 
vital. The centre is double, one for each side, and it may be separated by 
means of a longitudinal incision (.Longet, 1847), whereby the respiratory 
movements continue symmetrically on both sides. Section of vagi.—If one 
vagus be divided, respiration on the same side is slowed. If both vagi be 
divided, the respirations become much slower and deeper, but the respiratory 
movements are symmetrical on both sides (fig. 575). [The fact that section of 
the vagi modifies the respiratory movements shows that impulses must be con- 
tinually passing upwards in the vagi—from the lungs—to modify the activity 
of the respiratory centre, and that these impulses influenced the rate and depth 
of the respiratory discharges]. Stimulation of the central end of one vagus, 
both being divided, causes an arrest of the respiration only on the same side, 
the other side continues to breathe. The same result is obtained by stimulation 
of the trigeminus on one side (.Langendorff). When the centre is divided 
transversely on one side, the respiratory movements on the same side cease 
(Schiff). Most probably the dominating respiratory centre lies in the me- 
dulla oblongata, and upon it depend the rhythm and symmetry of the respiratory 
movements; but, in addition, other and subordinate centres are placed in 
the spinal cord, and these are governed by the oblongata centre. If the spinal 
cord be divided in newly-born animals (dog, cat) below the medulla oblongata, 
respiratory movements of the thorax are sometimes observed {Bracket, 1835). 
[If the cord be divided below the medulla, or the cranial arteries ligatured (rabbit), there may 
still be respiratory movements, which become more distinct if strychnin be previously admin- 
istered, so that Langendorff assumes the existence of a spinal respiratory centre, which he 
finds is also influenced by reflex stimulation of sensory nerves.] 
Nitschmann, by means of a vertical incision into the cervical cord, divided the spinal centre 
into two equal halves, each of which acted on both sides of the diaphragm after the medulla 
was divided just below the calamus scriptorius. The spinal centres must, therefore, be connected 
with each other in the cord. The spinal respiratory centre can be excited or inhibited reflexly 
(Wertheimer). 
Anatomical.—Schiff locates the respiratory centre near the lateral margins of the gray 
matter in the floor of the 4th ventricle, but not reaching so far backwards as the ala cinerea. 
According to Gierke, Heidenhain, and Langendorff, those parts of the medulla oblongata whose 
destruction causes cessation of the respiratory movements are single or double strands of nervous 
matter, containing gray nervous substance with small ganglion cells, and running downwards in 
the substance of the medulla oblongata. These strands are said to arise partly from the roots of 
the vagus, trigeminus, spinal accessory, and glosso-pharyngeal (Meynert), forming connections 
by means of fibres with the other side, and descending as far downwards as the cervical enlarge- 
ment of the spinal cord (Goll). According to this view, this strand represents an inter-central 
band connecting the spinal cord (the place of origin of the motor respiratory nerves) with the 
nuclei of the above named cranial nerves. 
Cerebral Inspiratory Centre.—According to Christiani, there is a cere- 
bral inspiratory centre in the optic thalamus in the floor of the 3d ventricle, 
which is stimulated through the optic and auditory nerves, the cerebrum and 
corpora striata having been previously removed ; when it is stimulated directly, 
it deepens and accelerates the inspiratory movements, and may even cause a 
standstill of the respiration in the inspiratory phase. This inspiratory centre 
may be extirpated. After this operation, an expiratory centre is active in the 
substance of the anterior pair of the corpora quadrigemina, not far from the 
aqueduct of Sylvius. Martin and Booker describe a second cerebral inspira- 
tory centre in the posterior pair of the corpora quadrigemina. These three 
centres are connected with the centres in the medulla oblongata. 
According to Marckwald, not only the posterior corpora quadrigemina, but also the sensory 
nucleus of the trigeminus, is concerned in maintaining the regular respiratory rhythm. In the 
brain also there are said to exist subordinate “ cerebral respiratory centres.” Ott found on 
stimulating the tissue between the corpus striatum and optic thalamus that the number of Sec. 368.] 
APNCEA. 
839 
respirations was greatly increased. If this “ centre ” be destroyed, a dyspnoeic respiratory 
acceleration caused by heat (heat dyspnoea) ceases. 
The respiratory centre consists of two 
centres, which are in a state of activity 
alternately—an inspiratory and an expira- 
tory centre (fig. 574), each one forming 
the motor central point for the acts of inspi- 
ration and expiration (§ 112). The centre 
is automatic, for, after section of all the 
sensory nerves which can act reflexly upon 
the centre, it still retains its activity. The 
degree of excitability and the stimulation of 
the centre depend upon the state of the 
blood, and chiefly upon the amount of the 
blood-gases, the O and C02 (fi. Rosenthal'). 
According to the condition of the centre, 
there are several well-recognized respiratory 
conditions:— 
1. Apncea.—Complete cessation of the 
respiration constitutes apncea, /. <?., cessation 
of the respiratory movements, owing to the 
absence of the proper stimulus, due to the 
blood being saturated with O and poor in 
C02. Such blood saturated with O fails to 
stimulate the centre, and hence the respira- 
tory muscles are quiescent. This seems to 
be the condition in the foetus during intra- 
uterine life. If air be vigorously and rapidly 
forced into the lungs of an animal by arti- 
ficial respiration, the animal will cease to 
breathe for a time, after cessation of the 
artificial respiration {Hook, 1667), the blood 
being so arterialized that it no longer 
stimulates the respiratory centre. If a per- 
son takes a series of rapid, deep respirations 
his blood becomes surcharged with oxygen, 
and long “ apnceic pauses” occur. 
Apnceic Blood.—A. Ewald found that the arterial blood of apnoeic animals was completely 
saturated with O, while the C02 was diminished; the venous blood contained less O than normal 
—this latter condition being due to the apnoeic blood causing a considerable fall of the blood- 
pressure and consequent slowing of the blood-stream, so that the O can be more completely 
taken from the blood in the capillaries (Pfiilger). The amount of O used in apncea on the whole 
is not increased (§ 127). Gad remarks that during forced artificial respiration, the pulmonary 
alveoli contain a very large amount of atmospheric air; hence, they are able to arterialize the 
blood for a longer time, thus diminishing the necessity for respiration. According to Gad and 
Knoll, the excitability of the respiratory centre is reduced during apncea, and this is caused 
reflexly during artificial respiration by the distention of the lungs stimulating the branches of 
the vagus. In quite young animals apncea cannot be produced (Riinge). 
[Drugs.—If the excitability of the respiratory centre be diminished by chloral, apncea is 
readily induced, while, if the centre be excited, as by apomorphine, it is difficult to produce it.] 
[The state of rest of the respiratory movements, called apnoea, and brought 
about by rapidly increased respirations, was formerly thought to be due to 
increased oxygenation of the blood. There is, however, room for doubt as to 
this being the true explanation. In spite of the statement of Ewald, other 
observers are not agreed that the blood actually does become hyperoxygenated. 
Fig- 574- 
Scheme of the chief respiratory nerves. 
ins, inspiratory, and exp, expiratory 
centre—motor nerves are in smooth lines. 
Expiratory motor nerves to abdominal 
muscles, ab; to muscles of back, DO. 
Inspiratory motor nerves. PH, phrenic 
to diaphragm, D; INT, intercostal 
nerves; RL, recurrent laryngeal; cx, 
pulmonary fibres of vagus that excite 
inspiratory centre; cx/, pulmonary fibres 
that excite expiratory centre; cx//, 
fibres of sup. laryngeal that excite ex- 
piratory centre; inh, fibres of sup. 
laryngeal that inhibit the inspiratory 
centre. 840 
ASPHYXIA. 
[Sec. 368. 
Moreover, it is very difficult to cause apnoea after section of both vagi. Now 
section of the vagi can have no effect on the aeration of the blood during rapid 
artificial but under these circumstances the afferent impressions 
from the lungs to the respiratory centre are cut off. The more recent theory 
suggests that apnoea is due to the rapid respirations exciting the terminations of 
the inhibitory respiratory fibres in the lungs, and thus presenting a respiratory 
discharge from the respiratory centre in the medulla oblongata. It has been 
found that artificial respiration of pure hydrogen in intact animals will Cause 
apnoea. This seems to support the view that ordinary apnoea is in some way 
intimately related in its cause to the inhibitory impulses generated by rapid 
inflation of the lungs.] 
[Deglutition Apnoea.—Kronecker has shown that if a person slowly 
swallows a glass of water, that the mere act of swallowing arrests the activity of 
the respiratory centre, and brings about a condition of apnoea, and this even 
when the nostrils are closed, and no air is admitted to the lungs. This is an 
additional proof that the production of apnoea has more to do with the gene- 
ration of inhibitory impulses than with hyperoxygenation of the blood.] 
2. Eupnoea.—The normal stimulation of the respiratory centre, eupnosa, is 
caused by the blood, in which the amount of O and C02 does not exceed the 
normal limits (§§ 35 and 36). 
3. Dyspnoea.—All conditions which diminish the O and increase the C02 
in the blood circulating through the medulla and respiratory centre cause ac- 
celerating and deepening of the respirations, which may ultimately pass into 
vigorous and labored activity of all the respiratory muscles, constituting 
dyspnoea, when the difficulty of breathing is very great (§ 134). [Changes in 
the rhythm, § hi.] 
During normal respiration, and with the commencement of the need for more air, according 
to Gad, the gases of the blood excite only the inspiratory centre; while the expiration follows 
owing to reflex stimulation of the pulmonary vagus by the distention of the lungs (p. 847). He 
is also of opinion that the normal respiratory movements are excited by the C02. 
[Muscular work, as is well known, increases the respirations and may even cause dyspnoea. 
This is not due to the nervous connection of the muscles or other organs with the respiratory 
centre, but to changes in the blood. Geppert and Zuntz have shown, however, that the result 
cannot be explained by changes in the blood caused either by diminution of O or increase of 
C02. It seems to be due to the blood taking up some as yet unknown products from the con- 
tracting muscle, and carrying them to the respiratory centre, which is directly excited by them. 
The nature of these substances is unknown. It has been shown that the alkalinity of the blood 
is reduced by the formation of an acid. The substances, whatever they may be, are not excreted 
by the urine, and are, therefore, perhaps readily oxidized (Loewy). C. Lehmann has proved 
that, in rabbits, the acidification of the blood produced by muscular exertion plays an important 
part in the stimulation of the respiratory centre.] 
4. Asphyxia.—If blood, abnormal as regards the amount and quality of 
its gases, continue to circulate in the medulla, or if the condition of the blood 
become still more abnormal, the respiratory centre is over-stimulated, and ulti- 
mately exhausted. The respirations are diminished both in number and depth, 
and they become feeble and gasping in character ; ultimately the movements 
of the respiratory muscles cease, and the heart itself soon ceases to beat. This 
constitutes the condition of asphyxia, and if it be continued, death from suffo- 
cation takes place. (Langendorff asserts that in asphyxiated frogs the muscles 
and gray nervous substance have an acid reaction.) If the conditions causing 
the abnormal condition of the blood be removed, the asphyxia may be pre- 
vented under favorable circumstances, especially by using artificial respira- 
tion (§ 134) ; the respiratory muscles begin to act and the heart begins to 
beat, so that the normal eupnoeic stage is reached through the condition of 
dyspnoea. If the venous condition of the blood be produced slowly and very Sec.-368.] 
ASPHYXIA. 
841 
gradually, asphyxia may occur without there being any symptoms of dyspnoea, 
as happens when death takes place quietly and very gradually (§ 324, 5). 
[Experiment with Crossed Heads.—That the condition of the blood influences the respira- 
tory centre in the medulla oblongata is demonstrated by the following ingenious experiment ol 
Fredericq. Two large rabbits, A and B, are taken, and in both the vertebral arteries are liga- 
tured and the carotids exposed. Cannulae are introduced into the carotids, so that the blood 
of the one animal flows into the head of the other. The carotids of the rabbit A carry their 
blood, into the head of rabbit B, and the head of B similarly receives only the blood coming 
from the body of A. If, at a given moment, A respires air poor in oxygen, or if its trachea be 
closed, it is the rabbit B—the one which receives the asphyxiated blood of A—which shows 
signs of dyspnoea or asphyxial convulsions, whilst A remains quiescent and undisturbed. 
There is, therefore, an intimate relation between the composition qf the blood circulating in the 
head and the activity of the respiratory movements.] 
Amongst the causes of Dyspncea are—(1) Direct limitation of the activity of the res- 
piratory organs ; diminution of the respiratory surface by inflammation, acute oedema ($ 47), 
or collapse of the alveoli, occlusion of the capillaries of the alveoli, compression of the lungs, 
entrance of air into the pleura, obstruction or compression of the windpipe. (2) Obstruction 
to the entrance of the normal amount of air by strangulation, or enclosure in an insuffi- 
cient space. (3) Enfeeblement of the circulation, so that the medulla oblongata does not 
receive a sufficient amount of blood; in degeneration of the heart, valvular cardiac disease ; 
and artificially by ligature of the carotid and vertebral arteries (Kussmaul and Tenner), or by 
preventing the free efflux of venous blood from the skull, or by the injection of a large quantity 
of air or indifferent particles into the right heart. (4) Direct loss of blood, which acts by 
arresting the exchange of gases in the medulla [J. Rosenthal). This is the cause of the “ biting 
or snapping at the air ” manifested by the decapitated heads of young animals, e. g., kittens. 
[The phenomenon is well marked in the head of a tortoise separated from the body (IV. Stirling).] 
If we study the rapidly fatal effects of these factors on the respiratory activity, we observe 
that at first the respirations become quicker and deeper, then after an attack of general convul- 
sions, ending in expiratory spasm, there follows a stage of complete cessation of respiration. 
Before death takes place, there are usually a few “snapping” or gasping efforts at inspiration 
[Hogyes, Sigtn. Mayer—$ in). 
Condition of the Blood-Gases.—As a general rule, in the production of dyspnoea, the 
want of O and the excess of C02 act simultaneously (Pfliiger and Dohmen), but each of these 
alone may act as an efficient cause. According to Bernstein, blood containing a small amount 
of O acts chiefly upon the inspiratory centre, and blood rich in C02 on the expiratory centre. 
(1) Dyspncea from want of O occurs during respiration in a space of moderate size [\ 133), 
in spaces where the tension of the air is diminished, and by breathing indifferent gases or those 
containing no free O. When the blood is freely ventilated with N or H, the amount of C02 
in the blood may even be diminished, and death occurs with all the signs of asphyxia (PJiuger). 
(2) Dyspncea from the blood being overcharged with C02 occurs by breathing air con- 
taining much C02 (§ 133). Air containing much C02 may cause dyspnoea, even when the 
amount of O in the blood is greater than that in the atmosphere ( Thiry). The blood may even 
contain more O than normal [PJiuger). 
Heat Dyspncea.—An increased temperature increases the activity of the respiratory 
centre (§ 214, II, 3). This occurs when blood warmer than natural flows through the brain, as 
Fick and Goldstein observed when they placed the exposed carotids in warm tubes, so as to heat 
the blood passing through them. In this case the heated blood acts directly upon the brain, the 
medulla and the cerebral respiratory centres (Gad). Direct cooling diminishes the excitability 
[Fredericq). When the temperature is increased, vigorous artificial respiration does not produce 
apnoea, although the blood is highly arterialized [Ackermann). Emetics act in a similar manner 
[Hermann and Grimm). 
Electrical stimulation of the medulla oblongata, after it is separated from the brain, dis- 
charges respiratory movements or increases those already present [Kronecker and Marckwald). 
Langendorff found that electrical, mechanical, or chemical (salts) stimulation usually caused an 
expiratory effect, while stimulation of the cervical spinal cord (subordinate centre) gave an 
inspiratory effect. According to Laborde, a superficial lesion in the region of the calamus 
scriptorius causes standstill of the respiration for a few minutes. If the peripheral end of the 
vagus be stimulated, so as to arrest the action of the heart, the respirations also cease after a 
few seconds. Arrest of the heart’s action causes a temporary anaemia of the medulla, in conse- 
quence of which its excitability is lowered, so that the respirations cease for a time [Langendorff) 
Conditions affecting the Respiratory Centre.—This centre, besides 
being capable of being stimulated directly, may be influenced by the will, 
and also reflexly by stimulation of a number of afferent nerves. 842 
RESPIRATORY CENTRE. 
[Sec. 368. 
1. By a voluntary impulse we may arrest the respiration for a short time, 
but only until the blood becomes so venous as to excite the centre to increased 
action. The number and depth of the respirations may be voluntarily in- 
creased for a long time, and we may also voluntarily change the rhythm of 
respiration. 
2. The respiratory centre may be influenced reflexly both by fibres which 
excite it to increased action and by others which inhibit its action, (a) The 
exciting fibres lie in the pulmonary branches of the vagus, in the optic, audi- 
tory, and cutaneous nerves; normally their action overcomes the action of the 
inhibitory fibres. Thus, a cold bath deepens the respirations, and causes a 
moderate acceleration of the pulmonary ventilation (Speck). 
3. Impulses pass from the deglutition centre to the respiratory by what is 
termed “irradiation,” and give rise to “deglutition-respiration,” i. e., to a 
feeble contraction of the diaphragm with each act of deglutition. 
Section of both vagi causes slower and deeper respiratory movements, 
owing to the cutting off of those impulses which under normal conditions pass 
from the lungs to excite the respiratory centre (p. 838). [The inspirations are 
long and deep, and are followed by a short active expiration and a long pause 
Fig- 575- 
Effect on the respiratory movements of section of the second vagus in the rabbit. At S the 
respirations become slower and deeper. T indicates seconds [Stirling). 
(fig. 575). The effect may be studied by recording the respiratory movements 
with a stethograph, or by means of a sound placed in the oesophagus. Gad 
froze the vagi, and thus set aside their activity—thus avoiding the stimulation 
inseparable from the act of dividing them—and observed that the effects were 
almost the same as those produced by their section.] 
After section of both vagi, the amount of air taken in, and the C02 given 
off, however, are unchanged, but the inspiratory efforts are more vigorous and 
not so purposive (Gad). Weak tetanizing currents applied to the central end 
of the vagus cause acceleration of the respirations, while, at the same time, the 
efforts of the respiratory muscles may be increased (fig. 576), or diminished, or 
remain unchanged (Gad). [They may be increased in number and dimin- 
ished in extent (Stirling, fig. 577).] Strong tetanizing currents applied to the 
central end of the vagus may cause standstill of the respiration in the inspira- 
tory phase(Traube) [i.e., there is a true tetanus of the diaphragm (fig. 579)], or 
especially in fatigue of the nerves, in the expiratory phase (fig. 578). Single 
induction shocks have no effect (Marckwald and Kronecker). 
[The inspiratory fibres, which reflexly either accelerate the respirations or Sec. 368.] 
EFFECT OF SECTION OF VAGI. 
843 
cause tetanus of the diaphragm in the inspiratory phase, run in the trunk of the 
vagus in the neck, and come from the lungs. These fibres are normally in 
action when the lungs are strongly diminished in volume, e.g., at the end of 
each expiration, so that the contraction of the lung excites the next inspiratory 
act.] 
[But the vagus in the neck also contains some expiratory fibres, i.e., fibres 
whose excitation excites reflexly arrest of the respiration in the expiratory 
phase. They are not so numerous as the inspiratory fibres. Sometimes one 
Fig. 576- 
Effect of stimulating the central end of one vagus (rabbit) at S, with weak tetanizing stimuli, 
both vagi being divided. The number of respirations is increased. T = time, i. e., seconds 
(Stirling). 
succeeds, on stimulating the central end of the vagus, in causing reflexly a sus- 
pension of the contraction of the diaphragm and ribs, and consequently an arrest 
in the expiratory phase. Chloral diminishes the action of the inspiratory fibres, 
Effect of stimulating the central end of one vagus (rabbit) at S, both vagi being divided. 
T = time, i. e., seconds (Stirling). 
Fig. 577- 
and allows the expiratory to manifest their action (.Fredericq). In a rabbit poi- 
soned with a large dose of chloral stimulation of the central end of the vagus is 
invariably followed by an arrest in expiration (fig. 5 78). These fibres are excited 
every time the lungs are distended, either by a normal inspiration or by in- 
sufflating the lungs artificially.] 844 
EFFECTS ON RESPIRATORY CENTRE. 
[Sec. 368. 
[If the respiratory movements be arrested by stimulation of the central end of 
the vagus—both vagi being divided, the respirations, however, begin—at first 
small and feeble, and gradually gain, especially in frequency (fig. 580), and to 
a less degree in force, in spite of continuation of the stimulation (Stirling).] 
Respiratory tracing obtained by stimulation of the central end of the vagus in a chloralized 
rabbit. Arrest of the respiration in expiration. 
Fig. 578. 
[Marckwald, while admitting that the respiratory centre is automatically active, as well as 
capable of being affected reflexly, comes to the conclusion, that, when the centre is separated 
from all nerve-channels by which afferent impulses can be conveyed to it, it is incapable of dis- 
Fig- 579- 
Effect of stimulating the central end of the vagus (rabbit). The respiratory movements are 
arrested in the inspiratory phase. Stimulation began at D and ended at C. E, expiration ; 
I, inspiration. 
charging rhythmical respiratory movements. He also asserts that the normal rhythmical respi- 
ration is a reflex act discharged chiefly through the vagi, and that the normal excitant of the 
respiratory centre is not dependent on the condition of the blood, either on the diminution of 
Respiratory movements of a rabbit arrested by stimulation of the central end of the vagus at S, but 
the movements begin and increase in spite of continuation of the stimulation [Stirling). 
Fig. 580. 
O, or the increase of C02. These results are opposed to the usually accepted view, and they are 
controverted by Loewy. Division of the medulla oblongata above the respiratory centre, so as 
to cut off all cerebral channels of communication, has very little effect on the respiration. If, after 
this, one or both vagi be divided there is—(i) an extraordinary slowing of the respiration; 
the number of respirations may fall in the rabbit from 20 to 2 or 4 per minute ; (2) the rhythm 
is changed, in some cases the inspiration may be twice or thrice as long as the expiration, but, Sec. 368.] 
ACTION OF NERVES ON RESPIRATORY CENTRE. 
845 
whatever the ratio of inspiration to expiration, the respiration is rhythmical; (3) the volume 
of air respired is diminished (p. 842), but the volume for each respiration is deeper; (4) the intra- 
thoracic pressure is increased during inspiration, and during expiration it is the same as before 
the vagotomy.] 
to *-< 
Experiment. 
mm. 
—30 to — 40 
—22 to—24 
Intra-thoiacic 
Pressure. 
S3 
a 
o' 
OZ 
Frequency. 
< 
CTQ 
Cn OJ 
OJ M 
OOP 
O 
Volume Resp. 
3 
01 oj 3 
■f* <-n • 
O O 
per Min. 
c.cm. 
16 
l6 
Volume Resp. 
per Respir. 
t 1 
Ln On 
O O 
I I 
Intra-thoracic 
Pressure. 
O'^J 
O O 
K) 4^ 
X 
Frequency. 
tK.^\ 
Relation of 
Exp. Insp. 
> 
< 
ug 
0 OJ - 
Ur O 0 
LLb 
to -£* * 
0 0 
Volume Resp. 
per Min. 
0 
2 
*<l Ln 
NC “O 
Cn 
Diminution of 
Vol. per Min. 
Co 
O CO 
Volume Resp. 
per Respir. 
1 
* 
100 
15° 
Increase of 
Vol. for each 
Resp. 
[The above table (from Loewy) shows the result. Loewy finds that, if the centre be sepa- 
rated from all centripetal channels, it still discharges respiratory movements, which are rhythmical, 
and he has shown that these rhythmical discharges are due to the condition of the blood.] 
[If one lung be made atelectatic, i. e., devoid of air, e.g., by plugging its bronchus with a 
sponge-tent, then the pulmonary fibres of the vagus from this lung are no longer excited during 
respiration, and their section has no effect on the respiration. Section of the vagus on the sound 
side, however, has the same consequence as double vagotomy (Loewy). 
Wedenskii and Heidenhain find that a temporary, weak, electrical stimulus applied to the 
central end of the vagus, at the beginning of inspiration (rabbit), affects the depth of the suc- 
ceeding inspirations, while a similar strong stimulus affects also the depth of the following expira- 
tions. If the stimulus be applied just at the commencement of expiration, stronger stimuli 
being required in this case, there is a diminution of the expiration and of the following inpira- 
tion. Continued tetanic stimulation of the vagus may cause decrease in the depth of the expira- 
tions, or at the same time alteration in the depth of the inspirations, without affecting the respi- 
ratory rhythm; when the stimulation is stronger, inspiration and expiration are diminished with 
or without alteration of the frequency, and with the strongest stimuli, respirations cease either in 
the inspiratory or expiratory phase. 
(b) The inhibitory nerves which affect the respiratory centre run in the 
superior laryngeal nerve (Rosenthal), and also in the inferior laryngeal nerve 
(.Pfluger and Burkart, Hering, Breuer), to the respiratory centre (fig. 574 
ink). [The superior laryngeal nerve is remarkable for containing a large 
number of inhibitory respiratory nerves, or nerves which cause arrest of the 
respiration in expiration, or even fibres causing expiration. One knows that it 
is the sensory nerve of the larynx, and that foreign bodies or irritating matter 
in the larynx excites coughing, i. e., forced expiratory acts, reflexly.] 
According to Langendorff, direct electrical, mechanical, or chemical stimulation of the centre 
may arrest respiration, perhaps in consequence of the stimulus affecting the central ends of these 
inhibitory nerves where they enter the ganglia of the respiratory centre. During the reflex inhi- 
bition of the respiration in the expiratory phase, there is a suppression of the motor impulse in 
the inspiratory centre (IVegele). 
Stimulation of the superior or inferior laryngeal nerves (b) or their central 
ends causes slowing, and even arrest of the respiration (in expiration—Rosen- 
thal). Arrest of the respiration in expiration is also caused bv stimulation of 
the nasal (.Hering and Kratschmer) and ophthalmic branches of the trigeminus 
(Christiani), of the olfactory, and glosso-pharyngeal (Marckwald). [Kratsch- 
mer found that tobacco-smoke blown into a rabbit’s nostrils, or puffed through 
a hole in the trachea into the nose, by stimulating the nasal branch of the fifth 
nerve, arrested the respiration in the expiratory phase, while it had no effect 
when blown into the lungs. Ammonia vapor applied to the nostrils arrests it 
in the same way. If ammonia vapor be blown into the lungs (the nasal cavity 
being protected from its action), the respiration may be accelerated, or deepened, 846 
INHIBITION OF RESPIRATORY CENTRE. 
[Sec. 368. 
or arrested occasionally in expiration, i. e., according to the fibres of the vagus 
acted on by the vapor in the lungs (Knoll'). A stream of water dropped on a 
rabbit’s nose will arrest the respirations in expiration for 10-20 secs., and in 
the duck the same means will arrest the respiration for 10 minutes (Fredericq). 
These reflex arrests of respiration obviously play a protective role for the animal.] 
Stimulation of the pulmonary branches of the vagus by breathing irritating 
gases (Knoll) causes standstill in expiration, although some other gases cause 
standstill in inspiration. Chemical stimulation of the trunk of the vagus,—by 
dilute solutions of sodic carbonate,—causes expiratory inhibition of the respi- 
ration ; and mechanical stimulation,—rubbing with a glass rod,—inspiratory 
inhibition (Knoll). The stimulation of sensory cutaneous nerves, especially of 
the chest and abdomen (as occurs on taking a cold douche), and stimulation 
of the splanchnics, cause standstill in expiration, the first cause often giving rise 
to temporary clonic contractions of the respiratory muscles. The respirations 
are often slowed to a very great extent by pressure upon the brain [whether 
Fig. 581. 
Effect on respiration of stimulation of central end of the sciatic nerve in the rabbit (Stirling). 
the pressure be due to a depressed fracture or effusion into the ventricles and sub- 
arachnoid space]. The respiration may be greatly oppressed and stertorous. 
[All sensory nerves may act reflexly more or less like the vagus on the respi- 
ratory movements. Stimulation of the central end of the sciatic nerve usually 
accelerates the respiration (fig. 581), more rarely reflex expiratory arrest. The 
change may result in an increased number of respirations as well as increased 
depth. 
If the respiratory movements and blood pressure be recorded simultaneously, 
and a particular strength of stimulus applied to the central end of the sciatic 
nerve (rabbit), the blood-pressure is raised (fig. 582, B. P.), and the respira- 
tions may be increased in number but not raised in depth (fig. 582).] 
The amount of work done by the respiratory muscles is altered during the reflex slowing of 
the respiratory muscles, the work being increased during slow respiration, owing to the ineffectual 
inspiratory efforts (Gad). The volume of the gases which passes through the lungs during a 
given time remains unchanged (Valentin), and the gaseous exchanges are not altered at first 
( Vo it and Rauber). Sec. 368.] 
REGULATION OF RESPIRATION. 
847 
Automatic Regulation of Respiration.—Under normal circumstances, 
it would seem that the pulmonary branches of the vagus act upon the two res- 
piratory centres, so as to set in action what has been termed the self-adjusting 
mechanism ; thus, the inspiratory dilatation of the lungs stimulates mechanically 
the fibres which reflexly excite the expiratory centres, while the diminution of 
the lungs during expiration excites the nerves which proceed to the inspiratory 
centre (.Hering and Breuer, Head). [Thus blowing into the lungs excites the 
act of expiration, and sucking air out of them excites inspiration.] 
In this way we may explain the alternate play of inspiration and expiration. In deep narcosis, 
however, dilatation of the thorax in animals is followed first by cessation of the respiratory 
movements, and then by inspiration (P. Guttmanri). 
Discharge of the First Respiration.—The foetus is in an apnoeic con- 
dition until birth, when the umbilical cord is cut. During intra-uterine life, O 
is freely supplied to it by the activity of the placenta. All conditions which 
interfere with this due supply of O, as compression of the umbilical vessels and 
Fig. 582. 
Effect of stimulation (S) of the central end of the sciatic nerve (rabbit) on the respirations and 
blood-pressure (B.P), (Stirling). 
prolonged labor pains, cause a decrease of the O and an increase of the C02 in 
the blood, so that the condition of the foetal blood is so altered as to stimu- 
late the respiratory centre, and thus the impulse is given for the discharge of 
the first respiratory movement {Schwartz). A foetus still within the unopened 
foetal membranes, may make respiratory movements ( Vesalius, 1542). If the 
exchange of gases be interrupted to a sufficient extent, dyspnoea and ultimately 
death of the foetus may occur. If, however, the venous condition of the 
mother’s blood develops very slowly, as in cases of quiet slow death of the 
mother, the medulla oblongata of the foetus may gradually die without any res- 
piratory movement being discharged (§ 324, 5). 
According to this view, the respiratory movements are due to the direct action of the dyspnceic 
blood upon the medulla oblongata. [The excitability of the respiratory centre is less in the 
foetus than in the newly born, and it increases from day to day after birth. Amongst the causes 
of the diminished excitability are the small amount of O in foetal blood, and the slow velocity 
of the circulation. If an inspiration is discharged in the foetus, it is at once arrested by fluid 
passing into the nostrils and inhibiting the act reflexly. The chief cause of the first respiration 848 
CARDIO-INHIBITORY CENTRE. 
[Sec. 368. 
after birth is undoubtedly the increasing venosity of the blood, and also the disappearance of 
the above-named reflex inhibitory process.] Death of the mother acts like compression of the 
umbilical cord. In the former case, the maternal venous blood robs the foetal blood of its O, so 
that death of the foetus occurs more rapidly (Zuntz). If the mother be rapidly poisoned with 
CO (§ 17), the foetus may live longer, as the CO-hsemoglobin of the maternal blood cannot take 
any O from the foetal blood ($ 16—Hogyes). In slow poisoning the CO passes into the foetal 
blood ( Grihant and Quinquand). 
In many cases, especially in cases of very prolonged labor, the excitability of the respiratory 
centre may be so diminished, that after birth the dyspnoeic condition of the blood alone is not 
sufficient to excite respiration in a normal rhythmical manner. In such cases stimulation of the 
skin also acts, e.g., partly by the cooling produced by the evaporation of the amniotic fluid from 
the skin. When air has entered the lungs by the first respiratory movements, the air within the 
lungs also excites the pulmonary branches of the vagus (Pfliiger), and thus the respiratory centre 
is stimulated reflexly to increased activity. According to v. Preuschen’s observations, stimulation 
of the cutaneous nerves is more effective than that of the pulmonary branches of the vagus. In 
animals which have been rendered apnoeic by free ventilation of their lungs, respiratory move- 
ments may be discharged by strong cutaneous stimuli, e.g., dashing on of cold water. The 
mechanical stimulation of the skin by friction or sharp blows, or the application of a cold 
douche, excites the respiratory centre. When the placental circulation is intact, cutaneous 
stimuli do not discharge respiratory movements (Zuntz and Cohnslein), (Artificial respira- 
tion, § 134). 
[Action of Drugs on the Respiratory Centre.—Ammonia, salts of zinc and copper, 
strychnin, atropin, duboisin, apomorphin, emetin, the digitalis group, and heat increase the 
rapidity and depth of the respirations, while they become frequent and shallower after the use of 
alcohol, opium, chloral, chloroform, physostigmin. The excitability of the centre is first in- 
creased and then diminished by caffein, nicotin, quinine, and saponin (Brunton).] 
369. CENTRE FOR THE INHIBITORY NERVES OF THE 
HEART—(CARDIO-INHIBITORY).—The fibres of the vagus, when 
moderately stimulated, diminish the action of the heart; when strongly stim- 
ulated, however, they arrest its action and cause it to stand still in diastole 
(§ 35 2, 7); they are supplied to the vagus through the spinal accessory nerve, 
and have their centre in the medulla oblongata (§ 353). 
[Gaskell has shown that stimulation of the vagus not only influences the 
rhythm of the heart’s action, but modifies the other functions of the cardiac 
muscle. Stimulation of the vagus influences—(a) the autotnatic rhythm, 
i. e., the rate at which the heart contracts automatically ; (h) the force of the 
contractions, more especially the auricles, although in some animals, e.g., the 
tortoise, the ventricles are not affected; (c) the power of conduction, i.e., the 
capacity for conducting the muscular contractions. According to Gaskell, the 
vagus acts upon the rhythmical power of the muscular fibres of the heart.] 
This centre may be excited directly in the medulla, and also reflexly, by 
stimulating certain afferent nerves. 
Many observers assume that this centre is in a state of tonic excitement, i.e., that there is a 
continuous, uninterrupted, regulating, and inhibitory action of this centre upon the heart through 
the fibres of ttie vagus. According to Bernstein, this tonic excitement is caused reflexly through 
the abdominal and cervical sympathetic. 
I. Direct Stimulation of the Centre.—This centre may be stimulated 
directly by the same stimuli that act upon the respiratory centre. (1) Sudden 
anaemia of the oblongata, ligature of both carotids or both subclavians, or de- 
capitating a rabbit, the vagi alone being left undivided, cause slowing and even 
temporary arrest of the action of the heart. (2) Sudden venous hypercemia acts 
in a similar manner, e.g., by ligaturing all the veins returning from the head. 
(3) Increased venosity of the blood, produced either by direct cessation of the 
respirations (rabbit), or by forcing into the lungs a quantity of air containing 
much C02 (Traube). As the circulation in the placenta (the respiratory organ 
of the foetus) is interfered with during severe labor, this sufficiently explains the 
enfeeblement of the action of the heart which occurs during protracted labor; 
it is due to stimulation of the central end of the vagus by the dyspnoeic blood Sec. 369.] 
CARDIO-INHIBITORY CENTRE. 
849 
(.B. A. Schultze). (4) At the moment the respiratory centre is excited, and an 
inspiration occurs, there is a variation in the inhibitory activity of the cardiac 
centre (Donders, Pfliiger, Fredericq—§ 74, a, 4). (5) The centre is excited 
by increased blood-pressure within the cerebral arteries. 
II. The centre may be excited reflexly by—(1) Stimulation of sensory 
nerves (Lovett). 
[This is illustrated in fig. 583, which shows the effect produced on the heart 
by stimulation of the central end of the infra-orbital nerve, at c. The heart 
movements were recorded by means of a needle inserted into the heart. The 
heart-beat was arrested for a moment and pulse-beats were much slower, and 
there was consequently a great fall of the blood-pressure.] 
(2) Stimulation of the central end of one vagus, provided the other 
vagus is intact. 
(3) Stimulation of the sensory nerves of the intestines, by tapping 
upon the belly (Goltz’s tapping experiment), whereby the action of the 
heart is arrested. Stimulation of the splanchnic nerve directly (Asp and 
Ludwig), or of the abdominal or cervical sympathetic, produces the same 
Fig- 583- 
Momentary arrest and slowing of the heart-beat produced reflexly by stimulation of the central 
end of the infra-orbital nerve in the rabbit. 
result. Very strong stimulation of sensory nerves, however, arrests the aboVe- 
named reflex effects upon the vagus (§ 361, 3). 
Tapping Experiment.—Goltz’s experiment succeeds at once, by tapping the intestines of a 
frog directly, say, with the handle of a scalpel, especially if the intestine has been exposed to 
the air for a short time, so as to become inflamed ( Tarchanoff). Stimulation of the stomach of 
the dog causes slowing of the heart-beat (Sig. Mayer and Pribram). [M’William finds that 
the action of the heart of the eel may be arrested reflexly with very great facility. The reflex 
inhibition is obtained by slight stimulation of the gills (through the branchial nerves), the skin 
of the head and tail, and parietal peritoneum, by severe injury of almost any part of the animal, 
except the abdominal organs.] 
[Effect of Swallowing Fluids.—Kronecker has shown that the act of 
swallowing interferes with or abolishes temporarily the cardio-inhibitory action 
of the vagus, so that the pulse-rate is greatly accelerated. Merely sipping a 
wineglassful of water may raise the rate 30 per cent. Hence, sipping cold 
water acts as a powerful cardiac stimulant.] 
According to Hering, the excitability of the cardio-inhibitory centre is 
diminished by vigorous artificial ventilation of the lungs with atmospheric air. 
At the same time, there is a considerable fall of the blood-pressure (§ 352, 8, 4). 
In man, a vigorous expiration, owing to the increased intra-pulmonary pressure, causes an ACTION OF THE VAGUS ON THE HEART. 
[Sec. 369. 
acceleration of the heart-beat, which Sommerbrodt ascribes to a diminution of the activity of the 
vagi. At the same time the activity of the vaso-motor centre is diminished ($ 60, 2). 
Stimulation of the trunk of the vagus at any point from the centre 
downwards, along its whole course, and also of certain of its cardiac branches 
[inferior cardiac] causes the heart either to beat more slowly, or arrests its action 
in diastole. The result depends upon the strength of the stimulus employed ; 
feeble stimuli slow the action of the heart, while strong stimuli arrest it in 
diastole. The frog’s heart may be arrested by stimulating the fibres of 
the vagus UDon the sinus venosus Tor by stimulating the vagus in its course, as 
in fig. 584]. If strong stimuli 
be applied either to the centre 
or to the course of the nerve, 
for a long time, the part stim- 
ulated becomes fatigued and 
the heart beats more rapidly 
in spite of the continued stim- 
ulation. If a part of the nerve 
lying nearer the heart be 
stimulated, inhibition of the 
heart’s action is brought 
about, as the stimulus acts 
upon a fresh portion of nerve. 
[The action of the heart 
may be arrested by stimulation of the vagus, not only by means of electrical 
stimuli, but also by chemical (common salt, glycerin) or mechanical stimuli. 
As a rule, the right vagus is more powerful than the left. Suppose the heart to 
be arrested by stimulation of the vagus, the arrest is not permanent; in spite 
of continuation of the stimulation the heart begins to beat. At first the con- 
tractions are slower, and afterwards 
quicker. Fig. 585 shows the effect of 
stimulation of the vagus in a rabbit, 
the result being shown by recording 
the blood-pressure, and noting the 
sudden fall in the arterial pressure 
consequent on the arrest of the heart 
in diastole.] 
The following points have also been 
ascertained regarding the stimulation 
of the inhibitory fibres :— 
1. The experiments of Lowit on the frog’s 
heart, confirmed by Heidenhain, showed that 
electrical and chemical stimulation of the vagus 
produce different results, as regards the extent 
of the ventricular systole, as well as the num- 
ber of heart-beats; the contractions either be- 
come smaller, or less frequent, or they become 
smaller and less frequent simultaneously. Strong stimuli cause, in addition, well-marked relax- 
ation of the heart during diastole. 
2. In order to cause inhibition of the heart, continuous stimulus is not necessary. A rhythmi- 
cally interrupted moderate stimulus suffices (v, Bezola); 18 to 20 stimuli per second are required 
for mammals, and 2 to 3 per second for cold-blooded animals. 
3. Donders, with Prahl and Niiel, observed that arrest of the heart’s action did not take place 
immediately the stimulus was applied to the vagus; but about ]/(, of a second—period of latent 
stimulation—elapsed before the effect was produced on the heart. 
4. If the heart be arrested by stimulation of the vagus, it can still contract, if it be excited 
directly, e. g., by pricking it with a needle, when it executes a single contraction. [This holds 
good only for some animals, e. g., frog, tortoise, birds and mammals. In fishes, only the 
Heart Beat. 
Time in Secs. 
Stimulation. 
Fig. 584. 
Beating of a frog’s heart taken by means of a lever resting 
on the heart. The lowest curve shows when the vagus 
was stimulated and the consequent arrest of the heart- 
beat (Stirling). 
rig- 585- 
Blood-pressure tracing of the carotid artery of 
a rabbit. Effect of stimulation of the vagus 
(at a) causing a rapid fall of the blood-pres- 
sure (Stirling). Sec. 369.] 
ACTION OF THE VAGUS ON THE HEART. 
851 
ventricle responds to stimulation during marked inhibition; in the newt, only the bulbus 
arteriosus. In the newt’s heart, the sinus, auricles, and ventricle are all inexcitable to direct 
stimulation during strong inhibition.] 
5. According to A. B. Meyer, inhibitory fibres are present only in the right vagus in the 
turtle. It is usually stated that the right vagus is more effective than the left in other animals, 
e.g., rabbit (Masoin); but this is subject to many exceptions (Landois and Langendorff). [In 
the newt, the right vagus acts more readily on the ventricle than on the other parts of the 
heart; slight stimulation of the right vagus can arrest the ventricle, while the sinus and auricles 
go on beating.] 
6. The vagus has been compressed by the finger in the neck of man (Czermak, Concato); but 
this experiment is accompanied by danger, and ought not to be undertaken. The electrotonic 
condition of the vagus is stated in $ 335, III. 
7. Schiff found that stimulation of the vagus of the frog caused acceleration of the heart-beat, 
when he displaced the blood of the heart with saline solution. If blood-serum be supplied to 
the heart, the vagus regains its inhibitory action. 
8. Many soda salts in a proper concentration arrest the inhibitory action of the vagus, while 
potash salts restore the inhibitory function of the vagi suspended by the soda salts. If, how- 
ever, the soda or potash salts act too long upon the heart, they produce a condition in which, after 
the inhibitory function of the vagi is abolished, it is not again restored. The heart’s action in 
this condition is usually arhythmical (Loxvit). 
9. If the intracardial pressure be greatly increased, so as to accelerate greatly the cardiac 
pulsations, the activity of the vagus is correspondingly diminished (J. M. Ludwig and 
Luchsinger). 
[Differences in Animals.—Perhaps the most remarkable fact in connection with the influ- 
ence of the vagus on the eel’s heart and that of all other fishes examined, is, that vagus- 
stimulation causes the sinus and auricle to be entirely inexcitable to direct stimulation during 
strong inhibition. Nerve-stimulation has in this case the very peculiar effect of rendering the 
muscular tissue temporarily incapable of responding to even the strongest direct stimuli, e.g., 
powerful induction shocks This would appear to be decisive evidence that the vagus acts on 
muscle directly, and not simply on automatic motor ganglia, as was held according to the old 
view (M’ William).] 
Poisons.—Muscarin stimulates the terminations of the vagus in the heart, and causes the 
heart to stand still in diastole (Schmiedeberg and Koppe). [See p. 101 for Gaskell’s views.] If 
atropin be applied in solution to the heart, this action is set aside, and the heart begins to beat 
again. [Atropin abolishes completely the inhibitory action of the vagus on the heart. If it 
be injected into the jugular vein of a rabbit, the pulse-beats are increased 27 per cent., in the 
dog they may be trebled, and in a man under its full influence the pulse beats may rise from 
70 to 150 or more. After atropin, it is impossible to arrest the action of the heart by stimulation 
of the vagus, and in the frog this cannot be done even by stimulation of the inhibitory centre in 
the heart itself, so that atropin must be regarded as paralyzing the intracardiac terminations of 
the vagus.] Digitalin diminishes the number of heart-beats by stimulating the cardio-inhibi- 
tory centre (vagus) in the medulla. Large doses diminish the excitability of the vagus centre, 
and increase at the same time the accelerating cardiac ganglia, so that the heart-beats are thereby 
increased. In small doses, digitalin raises the blood-pressure by stimulating the vaso-motor 
centre and the elements of the vascular wall (ATug). Nicotin first excites the vagus, then 
rapidly paralyzes it. Hydrocyanic acid has the same effect (Preyer). Atropin (v. Bezold ) and 
curare (large dose—Cl. Bernard and Kolliker) paralyze the vagi, and so does a very low 
temperature or high fever. 
370. CENTRE FOR THE ACCELERATOR OR AUGMENTOR 
CARDIAC NERVES.—Nervus Accelerans.—It is more than probable 
that a centre exists in the medulla oblongata, which sends accelerating fibres to 
the heart. These fibres pass from the medulla oblongata—but from which part 
thereof has not been exactly ascertained—through the spinal cord, and leave 
the cord through the rami communicantes of several of the upper dorsal nerves, 
to pass into the sympathetic nerve. Some of these fibres, issuing from the 
spinal cord, pass through the first thoracic sympathetic ganglion and the ring 
of Vieussens, to join the cardiac plexus (figs. 586, 587). [These fibres, pro- 
ceeding from the spinal cord, frequently accompany the nerve running along 
the vertebral artery], and they constitute the Nervus accelerans cordis. [Fig. 
587 shows the accelerator fibres passing through the ganglion stellatum of the 
cat to join the cardiac plexus.] 
[Accelerans in the Dog.—These fibres leave the spinal cord as medullated 852 
[Sec. 370. 
ACCELERANS CENTRE. 
fibres by the anterior roots of the second and third dorsal nerves, and it may 
be by the fourth and fifth nerves as well—pass via the white rami communi- 
cantes to the second thoracic ganglion and ganglion stellatum—the latter is the 
first thoracic ganglion—and thence forwards through the annulus or ring of 
Vieussens to the inferior cervical ganglion. They then pass along the nerves 
arising either from the inferior cervical ganglion or one loop of the annulus of 
Vieussens. These emerging nerve-fibres are non-medullated, and as the aug- 
mentor fibres are medullated before they enter the sympathetic ganglia it is 
evident that they become non-medullated in these ganglia probably by ending 
in the multipolar nerve-cells of these ganglia, so that the emerging fibres may 
be regarded as continuous with the non-medullated processes of the sympathetic 
Fig. 586. 
Fig. 587. 
Fig. 586.—Scheme of the course of the accelerans fibres. P, pons; MO, medulla oblongata ; 
C, spinal cord; V, inhibitory centre for heart; A, accelerans centre; Vag., vagus; SL, 
superior, IL, inferior laryngeal; SC, superior, IC, inferior cardiac ; H, heart; C, cerebral 
impulse; S, cervical sympathetic; a, a, accelerans fibres. Fig. 587.—Cardiac plexus, and 
ganglion stellatum of the cat. R, right, L, left X I, vagus ; 2/, cervical sympathetic, 
and in the annulus of Vieussens; 2, communicating branches from the middle cervical gang- 
lion and the ganglion stellatum; 2//, thoracic sympathetic; 3, recurrent laryngeal; 4, 
depressor nerve ; 5, middle cervical ganglion ; 5/, communication between 5 and the vagus; 
6, ganglion stellatum (1st thoracic ganglion); 7, communicating branches with the vagus; 
8, nervous accelerans; 8, 8/, S//, roots of accelerans; 9, branch of the ganglion stellatum. 
nerve-cells. They remain non-medullated from the ganglion to the heart. In 
this respect these fibres differ markedly from the inhibitory fibres of the vagus. 
The inhibitory fibres of the vagus, although they pass through ganglia, remain 
as fine medullated fibres all the way to the heart.] 
[Stimulation of the accelerans nerve not only quickens the heart-beat and Sec. 370.] 
NERVUS ACCELERANS. 
853 
diminishes the diastole, but it increases its force, hence the term “ augmentor ” 
applied to it. It requires a pretty strong stimulus to excite it, and if the 
stimulation be kept up, the augmentor fibres are less easily exhausted than the 
inhibitory fibres of the vagus. Prolonged stimulation of the nerve results in 
increased rapidity of the heart’s action, and leads to a period of diminished 
energy on the part of the heart, the latter becoming exhausted. Thus this 
nerve may be regarded as the katabolic nerve of the heart, in opposition to the 
vagus, which is the anabolic nerve of the heart.] 
If the vagi of an animal be divided, stimulation of the medulla oblongata, of 
the lower end of the divided cervical spinal cord, even of the lower cervical 
ganglion, or of the upper dorsal ganglion of the sympathetic (Gang. s tel latum), 
causes acceleration of the heart-beats in the dog and rabbit, without the blood- 
pressure undergoing any change {Cl. Bernard, v. Bezold, Cyori). 
[Fig. 588 shows the effect on the rate of the heart-beat—acceleration—by 
stimulation of the accelerans nerve in dog.] 
On stimulating the medulla oblongata or the cervical portion of the spinal cord, the vaso- 
motor nerves are, of course, simultaneously excited. The consequence is that the blood-vessels, 
supplied by vaso motor nerves from the spot which is stimulated, contract, and the blood-pres- 
sure is greatly increased. Again, a single increase of the blood-pressure accelerates the action 
of the heart; this experiment does not prove directly the existence of accelerating fibres lying in 
Fig. 588. 
Effect produced by stimulation of peripheral end of the accelerans cordis nerve. The heart 
beats quicker. Stimulation begun at S. 
the upper part of the spinal cord. If, however, the splanchnic nerves be divided beforehand 
(when, as they supply the largest vaso-motor area in the body, the result of their division is to 
cause a great fall of the blood-pressure), then on stimulating the above-named parts, after this 
operation, the heart-beats are still increased in number, so that this increase cannot be due to the 
increased blood-pressure. Indirectly it may be shown, by dividing or extirpating all the nerves 
of the cardiac plexus, or at least all the nerves going to the heart, that stimulation of the medulla 
oblongata, or cervical part of the spinal cord, no longer causes an increased frequency of the 
heart’s action to the same extent as before division of these nerves. The slightly increased 
frequency in this case is due to the increased blood-pressure. 
The accelerating centre is certainly not continually in a state of tonic excite- 
ment, as section of the accelerans nerve does not cause slowing of the action of 
the heart; the same is true of destruction of the medulla oblongata or of the 
cervical spinal cord. In the latter case, the splanchnic nerves must be divided 
beforehand, to avoid the slowing effect on the action of the heart produced by 
the great fall of the blood-pressure consequent upon destruction of the cord, 
otherwise we might be apt to ascribe the result to the action of the accelerating 
centre, when it is in reality due to the diminished blood-pressure {Cyori). 
According to the results of the older observers {v. Bezold and others), some 
accelerating fibres run in the cervical sympathetic. A few fibres pass through the 
vagus to reach the heart (§ 352, 7), and when they are stimulated, either the 
heart-beat is accelerated or the cardiac contractions strengthened {Heidenhain 
and Lowit), or the latter alone occurs (Pawlow). The inhibitory fibres of the 854 
ACCELERANS IN THE FROG. 
[Sec. 370. 
vagus lose their excitability more readily than the accelerating fibres, but the 
vagus fibres are more excitable than those of the accelerans. 
Tarchanoff has described some very rare cases of individuals who, by a merely voluntary 
effort, and while at rest, the respirations remaining unaffected, could nearly double the number 
of their pulse-beats. 
Modifying Conditions.—When the peripheral end of the nervus accelerans is stimulated, 
a considerable time elapses before the effect upon the frequency of the heart takes place, i. e., it 
has a long latent period. Further, the acceleration thus produced disappears gradually. If 
the vagus and accelerans fibres be stimulated simultaneously, only the inhibitory action of 
the vagus is manifested. If, while the accelerans is being stimulated, the vagus be suddenly 
excited, there is a prompt diminution in the number of the heart-beats; and if the stimulation 
of the vagus is stopped, the accelerating effect of the accelerans is again rapidly manifested 
(C. Ludwig with Schmiedeberg, Bowditch, Baxt). According to the experiments of Strieker 
and Wagner on dogs, with both vagi divided, a diminution of the number of the heart-beats 
occurred when both accelerantes were divided. This would indicate a tonic innervation of the 
latter nerves. 
[Accelerans in the Frog.—Gaskell showed that stimulation of the vagus 
in the frog might produce two opposing effects : the one of the nature of in- 
hibition, the other of augmentation. The augmentor fibres in the frog leave 
the cord by the anterior roots of the third spinal nerve, and by the ramus 
communicans of this nerve they pass into the third sympathetic ganglion, they 
run up through the second ganglion, and thence through the annulus of Vieus- 
sens to the first sympathetic ganglion, i. e., the ganglion connected with the 
first spinal nerve. They then run up the short sympathetic nerve, enter the 
ganglion of the trunk of the vagus, pass through it and emerge, and are dis- 
tributed with the vagus fibres, emerging from the ganglion trunci vagi. In the 
crocodile, the accelerans fibres leave the sympathetic chain at the large gang- 
lion corresponding to the ganglion stellatum of the dog, and run along the 
vertebral artery up to the superior vena cava, and, after anastomosing with 
branches of the vagus, pass to the heart. “ Stimulation of these fibres increases 
the rate of the cardiac rhythm, and augments the force of auricular contrac- 
tions ; while stimulation of the vagus slows the rhythm, and diminishes the 
strength of the auricular contractions.” The strength of the ventricular con- 
traction, both in the tortoise and crocodile, does not seem to be influenced by 
stimulation of the vagus, and probably also it is unaffected by the sympathetic. 
The so-called vagus of the frog, in reality, consists of pure vagus fibres and 
sympathetic fibres, and is in fact a vago-sympathetic. Gaskell finds that stimu- 
lation of the sympathetic, before it joins the combined ganglion of the sympa- 
thetic and vagus, produces purely augmentor or accelerating effects ; while 
stimulation of the vagus, before it enters the ganglion, produces purely inhibitory 
effects. The two sets of fibres are quite distinct, so that in the frog the sym- 
pathetic is a purely augmentor (accelerator), and the vagus a purely inhibitory 
nerve. Acceleration is merely one of the effects produced by stimulation of these 
nerves; hence, Gaskell suggests that they ought to be called “ augmentor,” 
or simply cardiac sympathetic nerves. The augmentor fibres are non-medulla- 
ted in the trunk of the vagus, while the inhibitory fibres are medullated.] 
[In his more recent researches Gaskell asserts that vagus stimulation produces 
first an inhibitory or depressing effect, but that it ultimately improves the con- 
dition of the heart as regards force, rate, or regularity—one or all of these. 
He regards it as a true anabolic nerve (§ 342, d).] 
371. VASO-MOTOR CENTRE AND VASO-MOTOR 
NERVES.—Vaso-Motor Centre.—The chief dominating or general 
centre, which supplies all the non-striped muscles of the arterial system 
with motor nerves (vaso-motor, vaso-constrictor, vaso-hypertonic nerves), lies Sec. 371.] 
VASO-MOTOR CENTRE. 
855 
in the medulla oblongata, at a spot which contains many ganglionic cells (.Lud- 
wig and Thiry). Those nerves which pass to the blood-vessels are known as 
vaso-motor nerves. The centre (which is 3 millimetres long and 1)4 milli- 
metre broad in the rabbit) reaches from the region of the upper part of the 
floor of the medulla oblongata to within 4 to 5 mm. of the calamus scriptorius. 
Each half of the body has its own centre, placed 2)4 millimetres from the 
middle line on its own side, in that part of the medulla oblongata which repre- 
sents the upward continuation of the lateral columns of the spinal cord ; accord- 
ing to Ludwig, Owsjannikow, and Dittmar, in the lower part of the superior 
olives. Stimulation of this central area causes contraction of all the arteries, 
and, in consequence, there is great increase of the arterial blood-pressure, re- 
sulting in swelling of the veins of the heart. Paralysis of this centre causes 
relaxation and dilatation of all the arteries, and consequently there is an enor- 
mous fall of the blood-pressure. Under ordinary circumstances, the vaso- 
motor centre is in a condition of moderate tonic excitement (§ 366). Just as 
in the case of the cardiac and respiratory centres, the vaso-motor centre may 
be excited directly and reflexly. 
[Position—How ascertained.—As stimulation of the central end df a 
sensory nerve, e.g., the sciatic, in an animal under the influence of curare, 
causes a rise in the blood-pressure, even after removal of the cerebrum, it is 
evident that the centre is not in the cerebrum itself. For the effect of chloral, 
under the same conditions, see p. 858. By making a series of sections of the 
brain from above downwards, it is found that this reflex effect is not affected until 
a short distance above the medulla oblongata is reached. If more and more of 
the medulla oblongata be removed from above downwards, then the reflex rise 
of the blood-pressure becomes less and less, until, when the section is made 4 
to 5 mm. above the calamus scriptorius, the reflex effect on the blood-pressure 
ceases altogether. This is taken to be the lower limit of the general vaso-motor 
centre. The bilateral centre corresponds to some large multipolar nerve-cells, 
described by Clarke as the antero-lateral nucleus.] 
I. Direct Stimulation of the Centre.—The amount and quality of 
the gases contained in the blood flowing through the medulla are of primary 
importance. In the condition of apncea (§ 368, 1), the centre seems to be very 
slightly excited, as the blood-pressure undergoes a considerable decrease. 
When the mixture of blood-gases is such as exists under normal circumstances, 
the centre is in a state of moderate excitement, and running parallel with the 
respiratory movements are variations in the excitement of the centre (Traube- 
Hering curves—§ 85), these variations being indicated by the rise of the blood- 
pressure. When the blood is highly venous, produced either by asphyxia or 
by the inspiration of air containing a large amount of C02, the centre is strongly 
excited, so that all the arteries of the body contract, while the venous system 
and the heart become distended with blood {Thiry). At the same time, the 
velocity of the blood-stream is increased (Heidenhain). The same result is 
produced by ligature of both the carotid and subclavian arteries, thus causing 
sudden angemia of the medulla oblongata; and, no doubt, also by the sudden 
stagnation of the blood in venous hypergemia. 
Emptiness of the Arteries after Death.—The venosity of the blood which occurs after 
death always produces an energetic stimulation of the vaso motor centre, in consequence of 
which the arteries are firmly contracted. The blood is thereby forced towards the capillaries 
and veins, and thus is explained the “ emptiness of the arteries after death.” 
Effect on Hemorrhage.—Blood flows much more freely from large wounds, when the vaso- 
motor centre is intact, than if it be destroyed (frog). As psychical excitement undoubtedly 
influences the vaso-motor centre, we may thus explain the influence of psychical excitement 
(speaking, etc.) upon the cessation of hemorrhage. If the hemorrhage be severe, stimulation of 
the medulla oblongata, due to the anaemia, may ultimately cause constriction of the small arteries, 856 
COURSE OF VASO-MOTOR FIBRES. 
[Sec. 371. 
and thus arrest the bleeding. Thus, surgeons are acquainted with the fact that dangerous 
hemorrhage is often arrested as soon as unconsciousness, due to cerebral anaemia, occurs. If the 
heart be ligatured in a frog, all the blood is ultimately forced into the veins, and this result is 
also due to the anaemic stimulation of the oblongata (Goltz). In mammals, when the heart is 
ligatured, the equilibration of the blood-pressure between the arterial and venous systems takes 
place more slowly when the medulla oblongata is destroyed than when it is intact (v. Bezold, 
Gscheidlen). 
[Effect of Destruction of the Vaso-motor Centre.—If two frogs be pithed and their 
hearts exposed, and both be suspended, then the hearts of both will be found to beat rhyth- 
mically and fill with blood. Destroy the medulla oblongata and spinal cord of one of them, 
then immediately in this case, the heart, although continuing to beat with an altered rhythm, 
ceases to be filled with blood; it appears collapsed, pale, bloodless. There is a great accumula- 
tion of the blood in the abdominal organs and veins, and it is not returned to the heart, so that 
the arteries are empty. This experiment of Goltz is held to show the existence of venous tonus 
depending on a cerebro-spinal centre. If a limb of this frog be amputated, there is little or no 
hemorrhage, while in the other frog the hemorrhage is severe. The bearing of this experiment 
on conditions of “shock” is evident.] 
Action of Poisons.—Strychnin stimulates the centre directly, even in curarized dogs, and 
so do nicotin and Calabar bean. 
Direct Electrical Stimulation.—On stimulating the centre directly in animals, it is found 
that single induction shocks only become effective when they succeed each other at the rate of 
2 to 3 shocks per second. Thus there is a “summation” of the single shocks. The maxi- 
mum contraction of the arteries, as expressed by the maximum blood-pressure, is reached when 
io to 12 strong, or 20 to 25 moderately strong, shocks per second are applied (.Kronecker and 
Nicolaides). 
Course of the Vaso-motor Nerves.—From the vaso-motor centre fibres 
proceed directly through some of the cranial nerves to their area of distribution ; 
through the trigeminus partly to the interior of the eye (§ 347, I, 2), through 
the lingual and hypoglossal to the tongue (§ 347, III, 4), through the vagus to a 
limited extent to the lungs (frog) (§ 352, 8, 2) [the vaso-motor fibres pass to 
the lungs from the anterior roots of the 2d to the 7th upper dorsal nerves in the 
dog (§ 356)], and to the intestines via the splanchnics (§ 352, n). 
All the other vaso-motor nerves descend in the lateral columns of the spinal 
cord (§ 364, 9) ; hence, stimulation of the lower cut end of the spinal cord 
causes contraction of the blood-vessels supplied by the nerves below the point 
of section (.Pfliiger). In their course through the cord these fibres form con- 
nections with the subordinate vaso-motor centres in the gray matter of the cord 
(§ 362, 7), and then leave the cord either directly through the anterior roots of 
the spinal nerves to their areas of distribution, or pass through the rami com- 
municantes into the sympathetic, and from them reach the blood-vessels to 
which they are distributed (§ 356) [see fig. 530]. 
The following is the arrangement of these nerves in the region of the head : 
The cervical portion of the sympathetic supplies the great majority of the blood- 
vessels of the head (see Sympathetic, § 356, A, 3). In some animals, the great 
auricular nerve supplies a few vaso-motor fibres to its own area of distribution 
{Schiff, Loven, Moreau). The vaso-motor nerves to the upper extremities 
pass through the anterior roots of the middle dorsal nerves into the thoracic 
sympathetic, and upwards to the 1st thoracic ganglion, and from thence through 
the rami communicantes to the brachial plexus (Schiff\ Cyon). The skin of 
the trunk receives its vaso-motor nerves through the dorsal and lumbar nerves. 
The vaso-motor nerves to the lower extremities pass through the nerves of 
the lumbar and sacral plexuses into the sympathetic, and from thence to the lower 
limbs {Pfliiger, Schiff, Cl. Bernard). The lungs are supplied from the dorsal 
spinal cord through the first thoracic ganglion {Brown-Sequard, Pick and 
Badoud, Lichtheini). [In the dog fibres come through the 2d to the 7th dorsal 
nerves.] It is said that in the frog the vaso-motor nerves to the lungs pass by 
the vagus {Coureur). The splanchnic is the greatest vaso-motor nerve in the 
body, and supplies the abdominal viscera (§ 356, B—v. Bezold, Ludwig and Sec. 371.] 
STIMULATION OF VASO-MOTOR CENTRES. 
857 
Cyori). The vaso-motor nerves of the liver (§ 173, 6), kidney (§ 276), and 
spleen (§ 103) have been referred to already. According to Strieker, most of 
the vaso-motor nerves leave the spinal cord between the 5th cervical and the 
1st dorsal vertebrae. [Gaskell finds that in the dog (fig. 439) they begin to 
leave the cord at the 2d dorsal nerve (§ 366), and the great outflow of vaso- 
motor nerves is between the 2d dorsal and the 2d lumbar nerves in the dog.] 
As a general rule, the blood-vessels for the skin of the trunk and extremities 
are innervated from those nerves which give other fibres (e. g., sensory) to those 
regions. The different vascular areas behave differently with regard to the 
intensity of the action of the vaso-motor nerves. The most powerful vaso- 
motor nerve's are those that act upon the blood-vessels of peripheral parts, e.g., 
the toes, the fingers, and ears; while those that act upon central parts seem to 
be less active (Lewaschew), e.g., on the pulmonic circulation (§ 88). 
II. Reflex Stimulation of the Centre.—There are fibres contained in 
the different afferent nerves, whose stimulation affects the vaso-motor centre. 
There are nerve-fibres whose stimulation excites the vaso-motor centre, thus 
causing a stronger contraction of the arteries, and consequently an increase of 
thearterial blood-pressure. These are called “ pressor ” fibres. Conversely, 
there are other fibres whose stimulation reflexly diminishes the excitability of 
the vaso-motor centre. These act as reflex inhibitory nerves on the centre, and 
are known as “ depressor ” fibres. 
Fig. 589. 
Effect on the blood-pressure in carotid, produced by stimulation of the central end of the 
sciatic nerve in the rabbit. Stimulation began at S. 
Pressor, or excito-vaso-motor nerves, have already been referred to in con- 
nection with the superior and inferior laryngeal nerves (§ 352, 12, a), in the 
trigeminus, which, when stimulated directly (§ 347), causes a pressor action, 
as well as when stimulating vapors are blown into the nostrils (.Hering and 
Kratschmer). [The rise of the blood-pressure in this case, however, is accom- 
panied by a change in the character of the heart’s beat and in the respirations. 
Rutherford has shown that in the rabbit the vapor of chloroform, ether, amyl 
nitrite, acetic acid, or ammonia held before the nose of a rabbit greatly 
retards or even arrests the heart’s action, and the same is true if the nostrils 
be closed by the hand. This arrest does not occur if the trachea be opened, 
and Rutherford regards the result as due not to the stimulation of the sensory 
fibres of the trigeminus, but to the state of the blood acting on the cardio- 
inhibitory nerve apparatus.] Hubert and Roever found pressor fibres in the 
cervical sympathetic; S. Mayer and Pribram found that mechanical stimulation 
of the stomach, especially of its serosa, caused pressor effects (§ 352, 12, e). 
According to Loven, the first effect of stimulating every sensory nerve is a 
pressor action. 
[If a dog be poisoned with curare, and the central end of one sciatic nerve 
be stimulated, there is a great and steady rise of the blood-pressure, chiefly owing 858 
PRESSOR FIBRES. 
[Sec. 371. 
to the contraction of the abdominal blood-vessels, and at the same time there 
is no change in the heart-beat (fig. 589). If, however, the animal be poisoned 
with chloral, there is a fall of the blood-pressure resembling a depressor 
effect.] 
[The effect of the vaso-motor nerves on the blood-vessels, and consequently 
on the blood-pressure, may be illustrated by the following experiment. In a 
curarized dog artificial respiration is kept up, and a blood-pressure taken by 
means of the kymograph. Fig. 590, 1, gives the tracing obtained, which may 
be taken as normal. The spinal cord is then divided transversely at the level 
of the atlas, with the result that there is a sudden fall of the blood-pressure 
(fig. 590, 2), equal to 5 cm. of Hg. This is due to dilatation of the small 
arteries previously kept in a state of tonus by the vaso-motor nerves. The 
latter are now divided, the blood-vessels dilate, and therefore the blood-pressure 
falls. At the same time the temperature of superficial parts rises, because they 
contain more blood. Suppose the peripheral end of the divided cord to be 
faradized, besides contraction of the muscles of the body generally, the vaso- 
motor nerves are stimulated ; there is consequent contraction, especially of the 
small arteries, resulting in a rise of the blood-pressure (fig. 590, 3), and a fall 
Fig. 590. 
1, Normal blood-pressure tracing in a dog. 2, Fall of the blood-pressure after section of the 
bulb. 3, (4-), faradic stimulation of the peripheral end of the divided cord. 5, Return 
and subsequent fall of the blood-pressure after cessation of the stimulation. 
of temperature in the superficial parts. The rise of the blood-pressure takes 
place gradually, and remains at a certain level (equal in this experiment to 9 
cm. Hg). At 4 the stimulation ceases, and after a short period the pressure 
falls (fig. 590, 5), and continues to fall until it is lower at the outset of the 
experiment (fig. 590, 1).] 
O. Naumann found that weak electrical stimulation of the skin caused at first contraction 
of the blood-vessels, especially of the mesentery, lungs, and the web, with simultaneous excite- 
ment of the cardiac activity and acceleration of the circulation (frog). Strong stimuli, how- 
ever, had an opposite effect, i.e., a depressor effect, with simultaneous decrease of the cardiac 
activity. Griitzner and Heidenhain found that contact with the skin caused a pressor 
effect, while painful impressions produced no effect. The application of heat and cold to the 
skin produces reflexly a change in the lumen of the blood-vessels and in the cardiac activity 
(Rohrig, Winternilz). Pinching the skin causes contraction of the vessels of the pia mater of 
the rabbit {Schuller), and the same result was produced by a warm bath, while cold dilated the 
vessels. These results are due partly to pressor and partly to depressor effects, but the chief 
cause of the dilata'ion of the blood-vessels is the increased blood-pressure due to the cold con- 
stricting the cutaneous vessels. Heat, of course, has the opposite effect. In man, most stimuli 
applied to sensory nerves, produce an effect: feeble cutaneous stimuli, tickling (even unpleasant Sec. 371.] 
DEPRESSOR EFFECTS. 
859 
odors, bitter or acid tastes, optical and acoustic stimuli) at the part where they are applied, cause 
a fall of the cutaneous temperature, and diminution of the volume of the corresponding limb, 
sometimes increase of the general blood-pressure and change of the heart-beat. The opposite 
effects are produced by painful stimulation, the action of heat (and even by pleasant odors and 
sweet tastes). The former cause simultaneously dilatation of the cerebral vessels and increase 
the vascular contents of the skull,—the latter cause the opposite results (.Istomanow and 
Tarchanoff). 
Depressor fibres, i.e., fibres whose stimulation diminishes the activity of 
the vaso-motor centre, are present in many nerves. They are specially 
numerous in the superior cardiac branch of the vagus, which is known as 
the depressor nerve (§ 352, 6). [When the central end of the depressor 
nerve is stimulated in the rabbit, after a rather long latent period there is a 
steady fall of the blood-pressure. This is due to the afferent impulses passing 
up the depressor nerve and through the vagus to the vaso-motor centre in the 
bulb. The vaso-motor action of the bulb is thereby diminished, so that there 
is dilatation of the blood-vessels, especially of the splanchnic area of blood- 
vessels in the abdomen, and this great dilatation of blood-vessels in the abdo- 
men is consequently followed by a steady and marked fall of the blood-pressure 
(% 590-] 
The trunk of the vagus below the origin of the depressor also contains other 
depressor fibres (v. Bezold'), as well as the pulmonary fibres (dog). The latter 
Fig- 591- 
Fall of the blood-pressure in the carotid of a rabbit, produced by stimulation of the depressor 
nerve [Stirling). 
also act as depressors, during strong expiratory efforts (§ 74). Moreover, 
Hering found that inflating the lungs (to 50 mm. Hg pressure) caused a fall of 
the blood-pressure (and also’ accelerated the heart-beats—§ 369, II). Stimu- 
lation of the central end of sensory nerves, especially when it is intense and 
long continued, causes dilatation of the blood-vessels in the area supplied by 
them {Lovett). According to Latschenberger and Deahna, all sensory nerves 
contain both pressor and depressor fibres. 
[If a rabbit be poisoned with curare, and the central end of the great 
auricular nerve be stimulated, there is a double effect—one local and the 
other general; the blood-vessels throughout the body, but especially in the 
splanchnic area, contract, so that there is a general rise of the blood-pressure, 
while the blood-vessels of the ear are dilated. If the central end of the tibial 
nerve be stimulated, there is a rise of the general blood-pressure, but a local 
dilatation of the saphena artery in the limb of that side (.Loven). Again, the 
temperature of one hand and the condition of its blood-vessels influence that 
of the other. If one hand be dipped in cold water, the temperature of the 
other hand falls. Thus, pressor and depressor effects may be obtained from 
the same nerve. The vaso-motor centre, therefore, primarily regulates the 
condition of the blood-vessels, but through them it obtains its importance 860 
RESULTS OF VASO-MOTOR ACTION. 
[Sec. 371. 
by regulating and controlling the blood-supply according to the needs of an 
organ.] 
The central artery of a rabbit’s ear contracts regularly and rhythmically 3 to 5 times per 
minute. Schiff observed that stimulation of sensory nerves caused a dilatation of the artery, 
which was preceded by a slight temporary constriction. 
Depressor effects are produced in the area of an artery on which direct pressure is made, as 
occurs, for example, when the sphygmograph is applied for a long time—the pulse-curves 
become larger, and there are signs of diminished arterial tension ($ 75). 
Rhythmical Contraction of Arteries.—In the intact body slow alter- 
nating contraction and dilatation, without a uniform rhythm, have been 
observed in the arteries of the ear of the rabbit, the membrane of a bat’s wing, 
and the web of a frog’s foot. This arrangement, observed by Schiff, supplies 
more or less blood to the parts, according to the action of external conditions. 
It has been called a “ periodic regulatory vascular movement.” This 
movement may be useful when a vessel is occluded, as after ligature, and may 
help to establish more rapidly the collateral circulation. Stefani has shown 
that this occurs with more difficulty after section of the nerves. 
Direct, local applications may influence the lumen of the blood-vessels; 
cold and moderate electrical stimuli cause contraction ; while, con- 
versely, heat and strong mechanical or electrical stimuli cause dilata- 
tion, although with the last two there is usually a preliminary constriction. 
Drugs.—Almost all the digitalis group of substances cause constriction; quinine and 
salicin constrict the splenic vessels. The other febrifuges dilate the vessels {Thomson). See 
p. 112. 
Effect on Temperature.—The vaso-motor nerves influence the tempera- 
ture, not only of individual parts, but of the whole body. 
1. Local Effects.—Section of a peripheral vaso-motor nerve, e.g., the 
cervical sympathetic, is followed by dilatation of the blood-vessels of the 
parts supplied by it (such as the ear of the rabbit), the intra-arterial pressure 
dilating the paralyzed walls of the vessels. Much arterial blood, therefore, 
passes into and causes congestion and redness of the parts, or hypersemia, while, 
at the same time, the temperature is increased. There is also increased 
transudation through the dilated capillaries within the dilated areas; the 
velocity of the blood-stream is of course diminished, and the blood-pressure 
increased. The pulse is also felt more easily, because the blood-vessels are 
dilated. Owing to the increase of the blood-stream, the blood may flow from 
the veins almost arterial (bright red) in its characters, and the pulse may even 
be propagated into the veins, so that the blood spouts from them (CY. Bernard'). 
Stimulation of the peripheral end of a vaso-motor nerve causes the opposite 
results—pallor, owing to contraction of the vessels, diminished transudation, 
and fall of the temperature on the surface. The smaller arteries may contract 
so much that their lumen is almost obliterated. Continued stimulation ulti- 
mately exhausts the nerve, and causes at the same time the phenomena of 
paralysis of the vascular wall. 
Secondary Results.—The immediate results of paralysis of the vaso-motor nerves lead to 
other effects; the paralysis of the muscles of the blood-vessels must lead to congestion of the 
blood in the part; the blood moves more slowly, so that the parts in contact with the air cool 
more easily, and hence the first stage of increase of the temperature may be followed by a fall 
of the temperature. The ear of a rabbit with the sympathetic divided, after several weeks 
becomes cooler than the ear on the sound one. If in man the motor muscular nerves, as well 
as the vaso-motor fibres, are paralyzed, then the paralyzed limb becomes cooler, because the 
paralyzed muscles no longer contract to aid in the production of heat (| 338), and also because 
the dilatation of the muscular arteries, which accompanies a muscular contraction, is absent. 
Should atrophy of the paralyzed muscles set in, the blood-vessels also become smaller. Hence, 
paralyzed limbs in man generally become cooler as time goes on. The primary effect, however, Sec. 371.] 
SPLANCHNIC AREA. 
in a limb, e. g., after section of the sciatic or lesion of the brachial plexus, is an increase of the 
temperature. 
If, at the same time, the vaso-motor nerves of a large area of the skin be 
paralyzed, e.g., the lower half of the body after section of the spinal cord, 
then so much heat is given off from the dilated blood-vessels that either the 
warming of the skin lasts for a very short time and to a slight degree, or there 
may be cooling at once. Some observers (Tschetschichin, Naunyn, Quincke) 
have recorded a rise of the temperature after section of the cervical spinal 
cord, but Riegel did not observe this increase. 
2. Effect on the Temperature of the Body.—Stimulation or paralysis 
of the vaso-motor nerves of a small area has practically no effect on the gen- 
eral temperature of the body. If, however, the vaso-motor nerves of a consid- 
erable area of the skin be suddenly paralyzed, then the temperature of the 
entire body falls, because more heat is given off from the dilated vessels than 
under normal circumstances. This occurs when the spinal cord is divided 
high up in the neck. The inhalation of a few drops of amyl nitrite, which 
dilates the blood-vessels of the skin, causes a fall of the temperature (Sassetzki 
and Manasse'iri). Conversely, stimulation of the vaso-motor nerves of a large 
area increases the temperature, because the constricted vessels give off less 
heat. The temperature in fever may be partly explained in this way 
(§ 220, 4).. 
The activity of the heart, i. e.,, the number and energy of the cardiac 
contractions, is influenced by the condition of the vaso-motor nerves. When 
a large vaso-motor area is paralyzed, the blood-channels are dilated, so that 
the blood does not flow to the heart at the usual rate and in the usual amount, 
as the pressure is considerably diminished. Hence, the heart executes ex- 
tremely small and feeble contractions. Strieker observed that the heart of a 
dog ceased to beat on extirpating the spinal cord from the ist cervical to the 
8th dorsal vertebra. Conversely, we know that stimulation of a large vaso- 
motor area, by constricting the blood-vessels, raises the arterial blood-pressure 
considerably. As the arterial pressure affects the pressure within the left ven- 
tricle, it may act as a mechanical stimulus to the cardiac wall, and increase the 
cardiac contractions both in number and strength. Hence, the circulation is 
accelerated (.Heidenhain, Slavjansky). 
Splanchnic Area.—By far the largest vaso-motor area in the body is that 
controlled by the splanchnic nerves, as they supply the blood-vessels of the 
abdomen (§ 161); hence, stimulation of their peripheral ends is followed by a 
great rise of the blood-pressure. When they are divided, there is such a fall 
of the blood-pressure that other parts of the body become more or less anaemic, 
and the animal may even die from “ being bled into its own belly,” i. e., from 
what has been called “intravascular hemorrhage.” Animals whose 
portal vein is ligatured die for the same reason (C. Ludwig and Thiry) [see 
§ 87]. The capacity of the vascular system, depending as it does in part upon 
the condition of the vaso-motor nerves, influences the body-weight. Stimulation 
of certain vascular areas may cause the rapid excretion of water, and we may 
thus account in part for the diminution of the body-weight which has been 
sometimes observed after an epileptic attack terminating with polyuria. 
Trophic Disturbances sometimes occur after affections of the vaso-motor nerves (§ 343, II, c). 
Paralysis of the vaso-motor nerves not only causes dilatation of the blood-vessels and local 
increase of the blood-pressure, but it may also cause increased transudation through the capil- 
laries [$ 203]. When the active contraction of the muscles is abolished, the blood-stream at 
the same time becomes lower, and in some cases the skin becomes livid, owing to the venous 
congestion. There is a diminution of the normal transpiration, and the epidermis may be dry 
and peel off in scales. The growth of the hair and nails may be affected by the congestion 
of blood, and, other tissues may also suffer. 862 
INFLUENCES MODIFYING VASO-MOTOR ACTIVITY. 
[Sec. 371. 
Vaso-motor Centres in the Spinal Cord.—Besides the dominating 
centre in the medulla oblongata, the blood-vessels are acted upon by local or 
subordinate vaso-motor centres in the gray matter of the spinal cord, as is proved 
by the following observations: If the spinal cord of an animal be divided, 
then all the blood-vessels supplied by vaso-motor nerves below the point of 
section are paralyzed as the vaso-motor fibres proceed from the medulla oblon- 
gata. If the animal lives, the blood-vessels regain their tone and their former 
calibre, while the rhythmical movements of their muscular walls are ascribed 
to the subordinate centres in the lower part of the spinal cord (Lister, Goltz,— 
§ 36z> 7)- 
The subordinate spinal centres may, further, be stimulated directly by dyspnceic blood, 
and also reflexly, in the rabbit and frog (Ustimowitsch). After destruction of the medulla 
oblongata, the arteries of the frog’s web still contract reflexly when the sensory nerves of the hind 
leg are stimulated (Putnam, Nussbaum, Vulpian). In the dog, opposite the 3d to 6th dorsal 
nerve is a spinal vaso-motor centre (origin of the splanchnic), which can be excited reflexly 
(Smirnow), and there is a similar one in the lower part of the spinal cord ( Vulpian). 
If the lower divided part of the cord be crushed, the blood-vessels again 
dilate, owing to the destruction of the subordinate centres. In animals which 
survive this operation, the vessels of the paralyzed parts gradually recover their 
normal diameter and rhythmical movements. This effect is ascribed to ganglia, 
which are supposed to exist along the course of the vessels. [It is to be recol- 
lected that the existence of these peripheral nervous mechanisms has not been 
proved.] These ganglia [or peripheral nervous mechanisms] might be com- 
pared to the ganglia of the heart, and seem by themselves capable of sustaining 
the movements of the vascular wall. Even the blood-vessels of an excised 
kidney exhibit periodic variations of their calibre ( C. Ludwig and Mosso). It 
is important to observe that the walls of the blood-vessels contract as soon as 
the blood becomes highly venous. Hence, the blood vessels offer a greater 
resistance to the passage of venous than of arterial blood (67. Ludwig). Never- 
theless, the blood-vessels, although they recover part of their tone and mobility, 
never do so cotnpletely. 
The effects of direct mechanical, chemical, and electrical stimuli on blood-vessels may be due 
to their action on these peripheral nervous mechanisms. The arteries may contract so much 
as almost to disappear, but sometimes dilatation follows the primary stimulus. 
Lewaschew found that limbs in which the vaso-motor fibres had undergone degeneration 
reacted, like intact limbs, to variations of temperature; heat relaxed the vessels, and cold con- 
stricted them. It is, however, doubtful if the variations of the vascular lumen depend upon 
the stimulation of the peripheral nervous mechanisms. Amyl nitrite and digitalis are supposed 
to act on those hypothetical mechanisms. 
The pulsating veins in the bat’s wing still continue to beat after section of all their nerves, 
which is in favor of the existence of local peripheral nervous mechanisms (Luchsinger, Schiff). 
Influence of the Cerebrum.—The cerebrum influences the vaso-motor 
centre, as is proved by the sudden pallor that accompanies some psychical condi- 
tions, such as fright or terror. There is a centre in the gray matter of the 
cerebrum where stimulation causes cooling of the opposite side of the body. 
Although there is one general vaso-motor centre in the medulla oblongata, 
which influences all the blood-vessels of the body, it is really a complex compo- 
site centre, consisting of a number of closely aggregated centres, each of which 
presides over a particular vascular area. We know something, e. g., of the 
hepatic (§ 175) and renal centres (§ 276). 
Many poisons excite the vaso-motor nerves, such as ergotin, tannic acid, copaiba, and cubebs; 
others first excite and then paralyze, e.g., chloral hydrate, morphia, laudanosin, veratiin, nicotin, 
Calabar bean, alcohol; others rapidly paralyze them, e.g., amyl nitrite, CO (§ 17), atropin, 
muscarin. The paralytic action of the poison is proved by the fact that, after section of the 
vagi and accelerantes, neither the pressor nor the depressor nerves, when stimulated, produce 
any effect. Many pathological infective agents affect the vaso-motor nerves. Sec. 371]. 
VASO-DILATOR NERVES. 
863 
The veins are also influenced by vaso-motor nerves, and so are the lym- 
phatics, but we know very little about this condition. 
[Tonus of the Portal Vein.—The portal vein is certainly supplied by many nerve-fibres 
[Mall), and it seems to be endowed with a marked tonus, for it is capable of accommodating 
itself either to a very large or a very small quantity of blood, in fact it can diminish its capacity 
tenfold [Kronecker).\ 
Pathological.—The angio-neuroses, or nervous affections of blood-vessels, form a most 
important group of diseases. The parts primarily affected may be either the peripheral nervous 
mechanisms, the subordinate centres in the cord, the dominating centre in the medulla, or the 
gray matter of the cerebrum. The effect may be direct or reflex. The dilatation of the vessels 
may also be due to stimulation of vaso-dilator nerves, and the physician must be careful to 
distinguish whether the result is due to paralysis of the vaso-constrictor nerves or stimulation of 
the vaso-dilator fibres. 
Angio-neurosis of the skin occurs in affections of the vaso-motor nerves, either as a diffuse 
redness or pallor ; or there may be circumscribed affections. Sometimes owing to the stimula- 
tion of individual vaso-motor nerves, there are local cutaneous arterio-spasms (Nothnagel). In 
certain acute febrile attacks—after previous initial violent stimulation of the vaso-motor nerves, 
especially during the cold stage of fever—there may be different forms of paralytic phenomena 
of the cutaneous vessels. In some cases of epilepsy in man, Trousseau observed irregular, red, 
angio-paralytic patches (tdches cerebrates). Continued strong stimulation may lead to 
interruption of the circulation, which may result in gangrene of the skin and deeper-seated 
parts (IVeiss). 
H emicrania, due to unilateral spasm of the branches of the carotid on the head, is accom- 
panied by severe headache [Du Bois-Reymond). The cervical sympathetic nerve is intensely 
stimulated—a pale, collapsed, and cool side of the face, contraction of the temporal artery like 
a firm whip-cord, dilatation of the pupil, secretion of thick saliva, are sure signs of this affec- 
tion. This form may be followed by the opposite condition of paralysis of the cervical sympa- 
thetic, where the effects are reversed. Sometimes the two conditions may alternate. 
Basedow’s disease is a remarkable condition, in which the vaso-motor nerves are concerned; 
the heart beats very rapidly (90 to 129-200 beats per minute), causing palpitation; there is 
swelling of the thyroid gland (struma), and projection of the eyeballs (exophthalmos), with 
imperfectly co-ordinated movements of the upper eyelid, whereby the plane of vision is raised 
or lowered. Perhaps in this disease we have to deal with a simultaneous stimulation of the 
accelerans cordis ($ 370), the motor fibres of Muller’s muscles of the orbit and eyelids ($ 347,1), 
as well as of the vaso-dilators of the thyroid gland. The disease may be due to direct stimula- 
tion of the sympathetic channels or their spinal origins, or it may be referred to some reflex cause. 
It has also been explained, however, thus, that the exophthalmos and struma are the consequence 
of vaso-motor paralysis, which results in enlargement of the blood-vessels, while the increased 
cardiac action is a sign of the diminished or arrested inhibitory action of the vagus. All these 
phenomena may be caused, according to Filehne, by injury to the upper part of both restiform 
bodies in rabbits. 
Visceral Angio-Neuroses.—The occurrence of sudden hypersemia with transudations and 
ecchymoses in some thoracic or abdominal organs may have a neurotic basis. As already men- 
tioned, injury to the pons, corpus striatum, and optic thalamus may give rise to hypersemia, and 
ecchymoses in the lungs, pleurae, intestines, and kidneys. According to Brown-Sequard, com- 
pression or section of one-half of the pons causes ecchymoses, especially in the lung of the 
opposite side; he also observed ecchymoses in the renal capsule after injury of the lumbar 
portion of the spinal cord (§ 379). 
The dependence of diabetes mellitus upon injury to the vaso-motor nerves is referred to in 
| 175 ; the action of the vaso-motor nerves on the secretion of urine in £ 276; and fever in 
| 220. 
372. VASO-DILATOR CENTRE AND NERVES.—Although a 
vaso-dilator centre has not been definitely proved to exist in the medulla, 
still its existence there has been surmised. Its action is opposed to that of the 
vaso-motor centre. The centre is certainly not a continuous or tonic state of 
excitement. The vaso-dilator nerves behave in their functions similarly to the 
cardiac branches of the vagus ; both, when stimulated, cause relaxation and 
rest [Schiff, Cl. Bernard). Hence, these nerves have been called vaso- 
inhibitory, vaso-hypotonic, or vaso-dilator nerves. Dyspnceic blood 
stimulates this centre as well as the vaso-motor centre, so that the cutaneous 
vessels are dilated, while simultaneously the vessels of the internal organs are 864 
VASO-DILATOR NERVES. 
[Sec. 372. 
contracted and the organs anaemic, owing to the stimulation of their vaso- 
motor centre (Dastre and Morat). Nicotin is a powerful excitant of the vaso- 
dilator nerves (Ostronmoff); it raises the temperature of the foot (dog), and 
increases the formation of lymph (.Rogowicz). 
[The existence of vaso-dilator nerves is assumed in accordance with 
such facts as the following: If the chorda tympani be divided, there is no 
change in the blood-vessels of the sub-maxillary gland; but if its peripheral 
end be stimulated, in addition to other results (§ 145), there is dilatation of 
the blood-vessels of the sub-maxillary gland, so that the veins of this gland dis- 
charge bright florid blood, and, indeed, the vein may spout like an artery. 
Similarly, if the nervi erigentes be divided, there is no effect on the blood- 
vessels of the penis (§ 362, 4) ; but if their peripheral ends be stimulated with 
Faradic electricity, the sinuses of the corpora cavernosa dilate, become filled 
with blood, and erection takes place (§ 436). Other examples in muscle and 
elsewhere are referred to below.] 
Course of the Vaso-Dilator Nerves.—To some organs they pass as special nerves—to 
other parts of the body, however, they proceed along with the vaso-motor and other nerves. 
According to Dastre and Morat, the vaso-dilator nerves for the bucco-labial region (dog) pass 
out from the cord by the 1st to the 3d dorsal nerves, and go through the rami communicantes 
into the sympathetic, then to the superior cervical ganglion, and lastly through the carotid and 
inter-carotid plexus into the trigeminus. [The fibres occur in the posterior segment of the ring 
of Vieussens, and if they be stimulated there is dilatation of the vessels in the lip and cheek on 
that side. The maxillary branch of the trigeminus, however, also contains vaso-dilator fibres 
proper to itself (Laffont). In the gray matter of the cord there is a special subordinate centre 
for the vaso-dilator fibres of the bucco-labial region. This centre may be acted on reflexly by 
stimulation of the vagus, especially its pulmonary branches, and even by stimulating the sciatic 
nerve. The ear receives its nerves from the 1st dorsal and lowest cervical ganglion, the upper 
limb from the thoracic portion, and the lower limb from the abdominal portion of the sym- 
pathetic. The vaso-dilator fibres run to the sub-maxillary and sub-lingual glands, and also 
to the anterior part of the tongue in the chorda tympani ($ 349, 4), while those for the pos- 
terior part of the tongue run in the glosso-pharyngeal nerve (§ 351, 4—Vulpian). The vaso- 
dilator fibres for the kidneys are contained chiefly in the lower dorsal and upper lumbar nerves 
(§ 276). Stimulation of the nervi erigentes proceeding from the sacral plexus causes dilata- 
tion of the arteries of the penis, together with congestion of the corpora cavernosa ($ 436) 
{Eckhard, Loven). Eckhard found that erection of the penis can be produced by stimulation 
of the spinal cord and of the pons as far as the peduncles, which may explain the phenomenon 
of priapism in connection with pathological irritations in these regions. The muscles receive 
the vaso-dilator fibres for their vessels through the trunks of the motor nerves. Stimulation of 
a motor nerve or the spinal cord causes not only contraction of the corresponding muscles, but 
also dilatation of their blood-vessels ($ 294, II—C. Ludwig and Sczelkow, Hafix, Gaskell)— 
the dilatation of the vessels taking place even when the muscle is prevented from shortening. 
[Gaskell observed under the microscope the dilatation produced by stimulation of the nerve to 
the mylo-hyoid muscle of the frog.] The vaso-dilator nerve-fibres remain medullated up to their 
terminal ganglion {Gaskell). 
The vaso-dilators (like the vaso-motors, p. 862) also have subordinate 
centres in the spinal cord, e. g., the fibres of the labio-buccal region at the 
xst to 3d dorsal vertebrae. This centre may be influenced reflexly through the 
pulmonary fibres of the vagus, and also through the sciatic (.Laffont, Smirnow). 
According to Holtz, a similar centre lies in the lowest part of the cord, which 
may be affected reflexly through the nerves of the intestines (Pal). 
Goltz showed that, in the nerves to the limbs (e.g., in the sciatic nerve 
or nerves of the brachial plexus), the vaso-motor and vaso-dilator fibres lie side 
by side in the same nerve. If the peripheral end of the sciatic nerve be stimu- 
lated immediately after it is divided, the action of the vaso-constrictor fibres 
overcomes that of the dilators. If the peripheral end be stimulated 4 to 6 
days after the section, when the vaso-constrictors have lost their excitability, 
the blood-vessels dilate under the action of the vaso-dilator fibres. Stimuli, 
which are applied at long intervals to the nerve, act especially on the vaso-dilator Sec. 372.] 
VASO-DILATOR NERVES. 
865 
fibres; while tetanizing stimuli act on the vaso-motors. The latent period of the 
vaso dilators is longer, and they are more easily exhausted than the vaso-motors 
(.Bowditch and Warren). The sciatic nerve receives both kinds of fibres from 
the sympathetic. It is assumed that the peripheral nervous mechanisms in 
connection with the blood-vessels are influenced by both kinds of vascular 
nerves; the vaso-motors (constrictors) increase, while the vaso-dilators dimin- 
ish the activity of these mechanisms or ganglia. [It is, however, possible to 
explain their effects by supposing that they act directly upon the muscular 
fibres of the blood-vessels, without the intervention of any nervous ganglionic 
structures.] 
[The vaso-dilator fibres arise within the central nervous system, but they 
present a marked contrast to the vaso-constrictor fibres in many respects, some 
of which have already been stated. While the vaso-constrictors arise from a 
limited but extensive area of the cord (§ 356), the vaso-dilators, at least so far 
as they have been investigated, are said to arise from a wide area, which, 
unlike that of the vaso-constrictors, is not limited chiefly to the thoracic region 
of the cord, but on the contrary, there is a copious outflow of these nerve- 
fibres from the cranial and sacral regions of the central nervous system. In 
fact, it would seem that vaso-dilator fibres arise from all parts of the spinal cord. 
As to the course of these fibres, it is to be noted that in several respects this 
differs from that of the vaso-constrictors. As already stated, the latter consists 
of fine medullated fibres (1.8 ;x to 3.5 ix) which become non-medullated in the 
ganglia of the sympathetic system. The vaso-dilators, however, appear to fol- 
low a more direct course—and they also are fine medullated fibres as they leave 
the cord by the anterior roots—but they present this difference, that they run 
as medullated fibres to the organs in which they are distributed, where they 
become non-medullated.] 
[Section of the spinal cord high up in the neck causes, of course, a great fall of the blood- 
pressure, owing to the division of the vaso-motor nerves. In the dog the pressure may fall to 
30-40 mm. Hg. After isolation of the cord, in rabbits alone, stimulation of the central end of 
a sensory nerve causes a rise of the blood-pressure; in dogs, however, under the same con- 
ditions, the blood-pressure falls. Dyspnoeic blood also causes a rise of the blood-pressure, which 
is preceded by a fall (Ustimowitch). This reflex fall of the blood-pressure takes place after 
section of the splanchnics, and the nerves to the extremities, but it does not take place if the 
spinal cord be divided at the lumbar or lower dorsal region. If the cord be divided in the 
lower dorsal region stimulation of the brachial plexus has no effect, while the fall occurs after 
stimulation of the central end of the sciatic. These experiments indicate that the vaso dilator 
nerves which cause the fall of the blood-pressure arise in the lower part of the spinal cord 
(lumbar), and that they are probably contained in the visceral nerves and not in those for the 
extremities (Thayer and Pal).~\ 
In the muscles of the face, paralyzed by extirpation of the facial nerve, 
stimulation of the ring of Vieussens causes pseudo-motor contractions of these 
muscles, just as stimulation of the chorda tympani causes such contractions in 
the paralyzed tongue (§ 349, 4), after section of the hypoglossal nerve (Rogo- 
wicz). 
In analyzing the vascular phenomena resulting from experiments on these nerves, we must be 
very careful to determine whether the dilatation is the result of stimulation of the vaso-dilators, 
or a consequence of paralysis of the vaso-constrictors. Psychical conditions act upon the vaso- 
dilator nerves—the blush of shame, which is not confined to the face, but may even extend 
over the whole skin, is probably due to stimulation of the vaso-dilator centre. 
Influence on Temperature.—The vaso dilator nerves obviously have a considerable influ- 
ence on the te?nperature of the body and on the heat of the individual parts of the body. Both 
vascular centres must act as important regulatory mechanisms for the radiation of heat through 
the cutaneous vessels (g 214, II). Probably they are kept in activity reflexly by sensory nerves. 
Disturbances in their function may lead to an abnormal accumulation of heat, as in fever (§ 220), 
or to abnormal cooling (§ 213, 7). Some observers, however, assume the existence of an intra- 
cranial “ heat-regulating centre” ( Tschelschichin, Naunyn, Quincke). According to Wood, 866 
SPASM-CENTRE. 
[Sec. 372. 
separation of the medulla oblongata from the pons causes an increased radiation and a dimin- 
ished production of heat, due to the cutting off of the influences from the heat-regulating 
centre (g 377). 
373. SPASM-CENTRE—SWEAT-CENTRE.—Spasm-Centre. 
—In the medulla oblongata, just where it joins the pons, there is a centre, whose 
stimulation causes general spasms. The centre may be excited by suddenly 
producing a highly venous condition of the blood (“ asphyxia spasms”), in 
cases of drowning in mammals (but not in frogs), sudden anaemia of the 
medulla oblongata, either in consequence of hemorrhage or ligature of both 
carotids and subclavians (Kussmaul and Tenner), and lastly, by sudden venous 
stagnation caused by compressing the veins coming from the head. In all 
these cases, the stimulation of the centre is due to the sudden interruption of 
the normal exchange of the gases. When these factors act quite gradually, 
death may take place without convulsions. Direct stimulation by means of 
chetnical substances (ammonia carbonate, potash, and soda salts, etc.) applied 
to the medulla, quickly causes general convulsions (.Papellier). Intense direct 
mechanical stimulation of the medulla, as by its sudden destruction, causes gen- 
eral convulsions. 
Position.—Nothnagel attempted by direct stimulation to map out the position of the spasm- 
centre in rabbits; it extends from the area above the ala cinerea upwards to the corpora quadri- 
gemina. It is limited externally by the locus coeruleus and the tuberculum acusticum. In the 
frog, it lies in the lower half of the 4th ventricle (Heubel). The centre is affected in extensive 
reflex spasms ($ 364, 6), e.g., in poisoning with strychnin and in hydrophobia. 
Drugs.—Many inorganic and organic poisons, most cardiac poisons, nicotin, picrotoxin, 
ammonia (§ 277), and the compounds of barium cause death after producing convulsions, by 
acting on the spasm-centre (Rober, Heubel, Bohm). 
If the arteries going to the brain be ligatured so as to paralyze the medulla oblongata, then, 
on ligaturing the abdominal aorta, spasms of the lower limbs occur, owing to the anaemic 
stimulation of the motor ganglia of the spinal cord [Sigm. Mayer). 
Pathological—Epilepsy.—Schroder van der Kolk found the blood-vessels of the oblongata 
dilated and increased in cases of epilepsy. Brown-S6quard observed that injury to the central 
or peripheral nervous system (spinal cord, oblongata, peduncle, corpora quadrigemina, sciatic 
nerve) of guinea-pigs produced epilepsy, and this condition even became hereditary. Stimula- 
tion of the cheek or of the face, “epileptic zone,” on the same side as the injury (spinal cord), 
caused at once an attack of epilepsy; but when the peduncle was injured, the opposite side must 
be stimulated. Westphal made guinea-pigs epileptic by repeated light blows on the skull, and 
this condition also became hereditary. In these cases there was effusion of blood in the medulla 
oblongata and upper part of the spinal cord (§$ 375 and 378, I). Direct stimulation of the 
cerebrum also produces epileptic convulsions. Strong electrical stimulation of the motor areas 
of the cortex cerebri is often followed by an epileptic attack (g 375). [It is no unfrequent 
occurrence while one is stimulating electrically the motor areas of the cortex cerebri of a dog, to 
find the animal exhibiting symptoms of local or general epilepsy.] 
Sweat-Centre.—A dominating centre for the secretion of the sweat of 
the entire surface of the body (§ 289, II)—with subordinate spinal centres 
(§ 362, 8)—occurs in the medulla oblongata (Adamkiewicz, Mar me, Nawrocki). 
It is double, and in rare cases the excitability is unequal on the two sides, as is 
manifested by unilateral perspiration (§ 289, 2). 
[Drugs.—Calabar bean, nicotin, picrotoxin, camphor, and ammonium acetate, cause a secre- 
tion of sweat by acting directly on the sweat-centre. Muscarin causes local stimulation of the 
peripheral sweat-fibres—it causes sweating of the hind limbs after section of the sciatic nerves. 
Atropin arrests the action of muscarin (Ott, Wood, Field, Nawrocki).] 
[Regeneration of the Spinal Cord.—In some animals, true nervous matter is reproduced 
after part of the spinal cord has been destroyed, at least this is so in tritons and lizards {H. 
Muller). In these animals, when the tail is removed, it is reproduced, and Muller found that a 
part of the spinal cord corresponding to the new part of the tail is reproduced. Morphologically, 
the elements were the same, but the spinal nerves were not reproduced, while physiologically, 
the new nerve-substance was not functionally active; it corresponds, as it were, to a lower stage 
of development. According to Masius and Vaulair, an excised portion of the spinal cord of a 
frog is reproduced after six months; while Brown-Sequard maintains that re-union of the divided Sec. 373.] 
PSYCHICAL FUNCTIONS OF THE BRAIN. 
867 
surfaces of the cord takes place in pigeons after six to fifteen months. A partial re-union is 
asserted to occur in dogs by Dentan, Naunyn, and Eichhorst, although Schieferdecker obtained 
only negative results, the divided ends being united only by connective-tissue (Schwalbe).~\ 
374.—PSYCHICAL FUNCTIONS OF THE BRAIN.—The hemi- 
spheres of the cerebrum are usually said to be the seat of all the psychical activi- 
ties. Only when they are intact are the processes of thinking, feeling, and willing 
possible. After they are destroyed, the organism comes to be like a complicated 
machine, and its whole activity is only the expression of the external and internal 
stimuli which act upon it. The psychical activities appear to be located in both 
hemispheres, so that after destruction of a considerable part of one of them, 
the other seems to act in place of the part destroyed. [Objection has been 
taken to the term the “ seat of” the will and intelligence, and undoubtedly it 
is more consistent with what we know, or rather do not know, to say that the 
existence of volition and intelligence is dependent on the connection of the 
cerebral cortex with the rest of the brain.] 
[That a certain condition of the cerebral hemispheres is necessary for the 
manifestation of the intellectual faculties is admitted on all hands; for compres- 
sion of the brain, e.g., by a depressed fracture of the skull, and sudden cessa- 
tion of the supply of blood to the brain, abolish consciousness. The intellec- 
tual faculties are affected by inflammation of the meninges involving the 
surface of the brain, the action of drugs affects the intellectual and other facul- 
ties; but while all this is admitted we cannot say precisely upon what parts of 
the brain ideation depends.] 
[The pre-frontal area, or the convolutions in front of the ascending frontal supplied by the 
anterior cerebral artery, are sometimes regarded as the anatomical substratum of certain mental 
acts. At any rate, electrical stimulation of these parts is not followed by muscular motion, and, 
according to Ferrier, if this region be extirpated in the monkey, there is no motor or sensory 
disturbance in this animal; it still exhibits emotional feeling, all its special senses remain, and 
the power of voluntary motion is retained; but, nevertheless, there is a decided alteration in the 
animal’s character and behavior, so that it exhibits considerable psychological alterations, and, 
according to Ferrier, “ it has lost to all appearance the faculty of attention and intelligent obser- 
vation.”] 
Observations on Man.—Cases in which considerable unilateral lesions or destruction of one 
hemisphere have taken place, without the psychical activities appearing to suffer, sometimes 
occur. The following is a case communicated by Longet: A boy, 16 years of age, had his 
parietal bone fractured by a stone falling on it, so that part of the protruding brain-matter had 
to be removed. On reapplying the bandages, more brain-matter had to be removed. After 18 
days he fell out of bed, and more brain-matter protruded, which was removed. On the 35th 
day he got intoxicated, tore off the bandages, and with them a part of the brain-matter. After 
his recovery the boy still retained his intelligence, but he was hemiplegic. Even when both 
hemispheres are moderately destroyed, the intelligence appears to be intact; thus, Trousseau de- 
scribes the case of an officer whose fore-brain was pierced transversely by a bullet. There was 
scarcely any appearance of his mental or bodily faculties being affected. In other cases, destruc- 
tion of parts of the brain peculiarly alters the character. We must be extremely careful, how- 
ever, in forming conclusions in all such cases. [In the celebrated “American crowbar case ” 
recorded by Bigelow, a young man was hit by a bar of iron 1 inch in diameter, which tra- 
versed the anterior part of the left hemisphere, going clean out at the top of his head. This 
man lived for thirteen years without any permanent alterations of motor or sensory functions; 
but “ the man’s disposition and character were observed to have undergone a serious change. 
There were, however, some changes which might be referable to injury to the frontal region.” 
In all cases it is most important to know both the exact site and the extent of the lesion. Ross 
points out that the characteristic features of lesions in the pre-frontal cortical region are afforded 
by “ psychical disturbances, consisting of dementia, apathy, and somnolency.”] 
Imperfect Development of the Cerebrum.—Microcephalia and hydrocephalus yield 
every result between diminution of the psychical activities and idiocy. Extensive inflammation, 
degeneration, pressure, anaemia of the blood-vessels, and the actions of many poisons produce the 
same effect. 
Flourens’ Doctrine.—-Flourens’ assumed that the whole of the cerebrum is concerned in 
every psychical process. From his experiments on pigeons, he concluded that if a small part of 
the hemispheres remained intact, it was sufficient for the manifestation of the mental functions; 868 
REMOVAL OF THE CEREBRUM. 
[Sec. 374. 
just in proportion as the gray matter of the hemispheres is removed, all the functions of the cere- 
brum are enfeebled, and when all the gray matter is removed all the functions are abolished. 
According to this view, neither the different faculties nor the different perceptions are localized in 
special areas. Goltz holds a somewhat similar view to that of Flourens. He assumes that if 
an uninjured part of the cerebrum remain, it can to a certain extent perform the functions of the 
parts that have been removed. This Vulpian has called the law of “ functional substitution ” 
(loi de suppleance). 
The phrenological doctrine of Gall (f 1828) and Spurzheim assumes that the different 
mental faculties are located in different parts of the brain, and it is assumed that a large 
development of a particular organ may be detected by examining the external configuration of the 
head (Cranioscopy). 
Removal of the Cerebrum.—After the removal of both cerebral hemi- 
spheres, in most animals, every voluntary movement and consciousness of im- 
pressions, and sensory perception and signs of intelligent volition, appear to 
cease. On the other hand, the whole mechanical movements and the mainten- 
ance of the equilibrium of the movements are retained. The maintenance 
of the equilibrium depends upon the mid-brain, and is regulated by important 
reflex channels (§ 379). 
Sudden cessation of the circulation in the brain, e.g., by decapitation, is followed at once by 
cessation of the mental faculties. When Hayem and Barrier perfused the blood of a horse 
through the carotids of a decapitated dog’s head, the head showed signs of consciousness for 10 
seconds, but not longer. 
The mid-brain (corpora quadrigemina) is connected not only with the gray 
matter of the spinal cord and medulla oblongata, the seat of extensive reflex 
mechanisms (§ 367), but it also receives fibres coming from the higher organs of 
sense,which also excite movements reflexly. The corpora quadrigemina are also 
supposed to contain a reflex inhibitory apparatus (§ 361, 2). The joint action 
of all these parts makes the corpora quadrigemina one of the most important 
organs for the harmonious execution of movements, and this even in a higher 
degree than the medulla oblongata itself ( Goltz). Animals with their corpora 
quadrigemina intact retain the equilibrium of their bodies under the most 
varied conditions, but they lose this power as soon as the mid-brain is destroyed 
(Goltz). Christiani locates the co-ordinating centre for the change of place 
and the maintenance of the equilibrium, in mammals, in front of the inspiratory 
centre in the 3d ventricle (§ 368). 
That impressions from the skin and sense-organs are concerned in 
the maintenance of the equilibrium is proved by the following facts : A 
frog without its cerebrum at once loses its power of balancing itself as soon as 
the skin is removed from its hind limbs. The action of impressions commu- 
nicated through the eyes is proved by the difficulty or impossibility of main- 
taining the equilibrium in nystagmus (§ 350), and by the vertigo which often 
accompanies paralysis of the external ocular muscles. In persons whose 
cutaneous sensibility is diminished, the eyes are the chief organs for the main- 
tenance of the equilibrium ; they fall over when the eyes are closed. [This is 
well illustrated in cases of locomotor ataxia (p. 818).] 
Frog without cerebrum.—A frog with its cerebrum or cerebral ganglia 
(fig. 592, 1) removed retains its power of maintaining its equilibrium. It can 
sit, spring, or execute complicated co-ordinated movements when appropriate 
stimuli are applied ; when placed on its back, it immediately turns into its nor- 
mal position on its belly ; if stimulated it gives one or two springs, and then 
comes to rest; when thrown into water, it swims to the margin of the vessel, 
and it may crawl up the side, and sit passive upon the edge of the vessel. 
When incited to move, it exhibits the most complete harmony and unity in all 
its movements. Unless it is stimulated, it does not make independent, volun- 
tary, purposive movements. It continues to sit in the same place, it takes no Sec. 374.] 
FROG WITHOUT CEREBRUM. 
869 
food, it shows no symptoms of fear, and ultimately, if left alone, it becomes 
desiccated like a mummy on the spot where it sits. [If the flanks of such a 
frog be stroked, it croaks with the utmost regularity according to the number of 
times it is stroked. Langendorff has shown that a frog croaks under the same 
circumstances when both optic nerves are divided. It seems to be influenced 
by light, provided its optic lobes be uninjured; for, if an object be placed in 
front of it so as to throw a strong shadow, then on stimulating the frog it will 
spring not against the object, a, but in the direction, b (fig. 593), so that it 
seems to possess some kind of vision. Steiner finds that if a glass plate be 
substituted for an opaque object like a book, the frog always jumps against this 
obstacle. Its balancing movements on a board are quite remarkable and 
acrobatic in character. If it be placed on a board, and the board gently in- 
clined (fig. 594), it does not fall off, as a frog with only its spinal cord will do, 
but as the board is inclined, so as to alter the animal’s centre of gravity, it slowly 
crawls up the board until it reaches such a position that its equilibrium is 
restored. If the board be sloped as in fig. 594, it will crawl up until it sits on 
the edge, and if the board be still further tilted, the frog will move as indicated 
Fig- 592- 
Fig- 593- 
Fig- 594- 
Fig- 595- 
Fig. 592.—Brain of the frog seen from above. O, olfactory lobe; I, cerebral hemispheres; 2, 
optic lobes; 3, cerebellum; 4, medulla oblongata. Fig. 593.—Frog without its cerebrum 
avoiding an object placed in its path. Fig. 594.—Frog without its cerebrum moving on an 
inclined board. Fig. 595.—Brain of pigeon seen from above. O, olfactory lobe; I, 
cerebral hemispheres ; 2, lateral part of the cerebellum; and 3, its central part or vermis; 
4, medulla oblongata. 
in the figure. It only does so, however, when the board is inclined, and it 
rests as soon as its centre of gravity is restored. It responds to every stimulus 
just like a complex machine, answering each stimulus with an appropriate action, 
and the movements come to an end when the stimulus ceases. It has been found, 
however, that if the frog be kept for a long time, in spite of the absence of re- 
generation of the cerebral hemispheres, there is a tendency for what may be 
apparently spontaneous movements to show themselves occasionally. But still 
apparently in such frogs there is wanting what is ordinarily called “ will.” The 
frog without its cerebrum possesses all the nervous and other mechanisms required 
for the execution of many complex co-ordinated movements, but it seems to 
want the power of voluntarily originating impulses to set this machine in 
motion, i.e., there is a want of spontaneity (Goltz, Steiner). Schroder, how- 
ever, states that in a frog deprived of its cerebral hemispheres there is not a 
complete absence of spontaneity nor of ability to feed itself, and states that 
such frogs may bury themselves in the earth at the beginning of winter and in 
summer they may catch flies.] 
A pigeon without its cerebral hemispheres (fig. 595) becomes drowsy, dull, 
and stupid, and behaves in a passive and motionless manner (fig. 596). When 
undisturbed it sits continuously, as if in sleep, but when stimulated, it exhibits 870 
EFFECTS OF REMOVING THE CEREBRUM. 
[Sec. 374. 
complete harmony of all its movements; it can walk, fly, perch, and balance 
its body on one leg; there is no paralysis. [It regains its position if put on its 
side or back. When flying it can 
imperfectly avoid obstacles in its 
path.] The sensory nerves and those 
of special sensation conduct impulses 
to the remaining parts of the brain, 
but such impulses only discharge re- 
flex movements, and they do not 
appear to excite conscious impres- 
sions. The bird starts when a pistol 
is fired close to its ear; it closes its 
eyes when it is brought near a flame, 
and the pupils contract; it turns 
away its head when the vapor of am- 
monia is applied to its nostrils. All 
these impressions are, perhaps, not 
perceived as conscious perceptions. 
The perceptive faculties—the will and memory—are abolished; the animal 
never takes food or drinks spontaneously. Food placed at the back part of its 
throat is swallowed [reflex act], or if its beak be plunged in corn it eats, and 
in this way the animal may be maintained alive for months (.Flourens). [In 
a certain number of cases the drowsy condition diminishes or may even pass 
off, and the pigeon may exhibit what appear to be spontaneous movements, 
but still these movements are very different from those of an intact bird. 
These movements are not necessarily volitional. It never flies or feeds itself, 
although placed in the midst of plenty of food, but it may walk aimlessly 
about for a time, and then resume its usually stolid, sleepy attitude.] 
Fish appear to behave differently. A carp with its cerebrum removed (fig. 
609, VI, 1) can see and may even select its food, and seems to execute its 
movements voluntarily (Steiner, Vulpiari). 
[In Teleostean fishes, if the homologues of the cerebral ganglion be removed such fish appear 
at first sight like normal fish. They maintain their normal attitude, and swim by means of the 
tail and fins with precision, and in their course they avoid obstacles, as if still possessed of some 
sense of vision. In them also there is apparently not complete absence of spontaneity. They 
not only see, but they seek their food, and can discriminate between different kinds of food or 
objects thrown into the water. It seems, then, that such fish to some extent see, distinguish 
colors, catch prey, direct its movements, but it is more impulsive and less cautious than a normal 
fish. An Elasmobranch fish, such as the dog-fish, deprived of its cerebral ganglion, is quite 
unable to find its food, because removal of the cerebrum necessitates removal of the organ of 
smell by which this animal is guided to its food.] 
Mammals, owing to the great loss of blood consequent on removal of the 
cerebrum, are not well suited for experiments of this kind. Immediately after 
the operation rabbits and rats show signs of great muscular weakness. When 
they recover, they present the same general phenomena as are observed in the 
pigeon. When stimulated they run, as it were blindfold, against an obstacle. 
Vulpian heard a peculiar shriek or cry which such a rabbit makes under the 
circumstances. [They regain their equilibrium if placed on their side or 
back ; they usually remain passive, taking no heed of food placed within their 
reach, but they masticate food placed in their mouth.] Sometimes even in 
man a peculiar cry is emitted in some cases of pressure or inflammation ren- 
dering the cerebral hemispheres inactive. 
[The dog does not survive removal of the whole cerebrum at one time, but 
parts of the cerebral convolutions have been removed at different times. 
Animals, which survive the operation for a long time, can execute many com- 
Fig. 596. 
Pigeon with its cerebral hemispheres removed. Sec. 374.] 
EFFECTS OF REMOVING THE CEREBRUM. 
871 
plicated acts, the performance of their ordinary bodily movements being only 
somewhat interfered with, but they exhibit signs of spontaneity in their acts, 
which lead one to infer that they still possess some intelligence and volitional 
power. It is plain that the nervous machinery for executing most or all of the 
ordinary movements of the foregoing animals lies in some part of the nervous 
system other than the cerebral hemispheres—probably in the middle and hind 
brains]. 
[A study of the phenomena exhibited by animals deprived of their cerebral 
lobes goes to show that such animals not only maintain all their organic func- 
tions, but they still possess the power of equilibration, co-ordination of 
locomotion, some degree of emotional expression, and “adaptive reactions in 
accordance with impressions made upon their organs of sense ” (Ferrier).] 
Observations on somnambulists show that in man also complete harmony 
of all movements may be retained, without the assistance of the will or 
conscious impressions and perceptions. As a matter of fact, many of our 
ordinary movements are accomplished without our being conscious of them. 
They take place under the guidance of the basal ganglia. 
The degree of intelligence in the animal kingdom is in relation to the size of the 
cerebral hemispheres, in proportion to the mass of the other parts of the central nervous system. 
Taking the brain alone into consideration, we observe that those animals have the highest intel- 
ligence in which the cerebral hemispheres greatly exceed the mid-brain in weight. The mid- 
brain is represented by the optic lobes in the lower vertebrates, and by the corpora quadrigemina 
in the higher vertebrates. In fig. 609, VI represents the brain of a carp; V, of a frog; and 
IV of a pigeon. In all these cases 1 indicates the cerebral hemispheres; 2, the optic lobes; 3, 
the cerebellum; and 4, the medulla oblongata. In the carp, the cerebral hemispheres are smaller 
than the optic lobes ; in the frog they exceed the latter in size. In the pigeon, the cerebrum 
begins to project backward over the cerebellum. The degree of intelligence increases in these 
animals in this proportion. In the dog’s brain (fig. 609, II) the hemispheres completely cover 
the corpora quadrigemina, but the cerebellum still lies behind the cerebrum. In man the 
occipital lobes of the cerebrum completely overlap the cerebellum (fig. 606). [The projec- 
tion of the occipital lobes over the cerebellum is due to the development of the frontal lobes 
pushing backwards the convolutions that lie behind them, and not entirely to increased develop- 
ment of the occipital lobes.] 
Meynert’s Theory.—According to Meynert, we may represent this relation in another way. 
As is known, fibres proceed downwards from the cerebral hemispheres, through the crusta or 
pes of the cerebral peduncle. These fibres are separated from the upper fibres or tegmentum 
of the peduncle by the locus niger, the tegmentum being connected with the corpora quadrigemina 
and the optic thalamus. The larger, therefore, the cerebral hemispheres, the more numerous 
will be the fibres proceeding from it. In fig. 564, II, is a transverse section of the posterior 
corpora quadrigemina, with the aqueduct of Sylvius and both cerebral peduncles of an adult 
man; p,p, is the crusta of each peduncle, and above it lies the locus niger, s. Fig. 564, IV, 
shows the same parts in a monkey; III, in a dog; and V, in a guinea pig. The crusta 
diminishes in the above series. There is a corresponding diminution of the cerebral hemi- 
spheres, and, at the same time, in the intelligence of the corresponding animals. 
Sulci and Gyri.—The degree of intelligence also depends upon the number and depth of 
the convolutions. In the lowest vertebrates (fish, frog, bird) the furrows or sulci are absent 
(fig. 564, IV, V, VI); in the rabbit there are two shallow furrows on each side (III). The dog 
has a completely furrowed cerebrum (I, II). Most remarkable is the complexity of the sulci and 
convolutions of the cerebrum of the elephant, one of the most intelligent of animals. Never- 
theless, some very stupid animals, as the ox, have very complex convolutions. 
The absolute weight of the brain cannot be taken as a guide to the intelligence. The 
elephant has absolutely the heaviest brain, but man has relatively the heaviest brain. [We ought 
also to take into account the complexity of the convolutions and the depth of the gray matter, 
its vascularity, and the number of connections between its nerve-cells.] 
Time an Element in all Psychical Processes.—Every psychical pro- 
cess requires a certain time for its occurrence—a certain time always elapses 
between the application of the stimulus and the conscious reaction. 872 
TIME IN CEREBRAL PROCESSES. 
[Sec. 374. 
Nature of Stimulus. 
Reaction Time. 
Name of Observer. 
Shock on left hand, 
.12 
Exner. 
Shock on forehead, 
•13 
Do. 
Shock on toe of left foot 
•17 
Do. 
Sudden noise, . 
•!3 
Do. 
Visual impression of electric spark, 
•IS 
Do. 
Hearing a sound, 
.16 
Donders. 
Current to tongue causing taste, 
.l6 
1 v. Vintschgau and 
\ Honigschmied. 
Saline taste, 
•15 
Do. 
Taste of sugar, 
.16 
Do. 
“ acids, 
.16 
Do. 
“ quinine, 
•23 
Do. 
Reaction Time.—This time is known as “ reaction time,” and is distinctly longer than the 
simple reflex time required for a reflex act. It can be measured by causing the person experi- 
mented on to indicate by means of an electrical signal the moment when the stimulus is 
applied. The reaction time consists of the following events: (i) Th & duration of perception, 
i. e., when we become conscious of the impression; (2) the duration of the time required to 
direct the attention to the impression, i. e., the duration of apperception ; and (3) the duration 
of the voluntary impulse, together with (4) the time required for conducting the impulse in the 
afferent nerves to the centre, and (5) the time for the impulse to travel outwards in the motor 
nerves. If the signal be made with the hand, then the reaction time for the impression of 
sound is 0.136 to 0.167 second; for taste, 0.15 to 0.23 ; touch, 0.133 to 0.201 second (Horsch, 
v. Vintschgau and Honigschmied); for olfactory impressions, which, of course, depend upon 
many conditions (the phase of respiration, current of air), 0.2 to 0.5 second. Intense stimula- 
tion, increased attention, practice, expectation, and knowledge of the kind of stimulus to be 
applied, all diminish the time. Tactile impressions are most rapidly perceived when they are 
applied to the most sensitive parts (v. Vintschgau). The time is increased with very strong 
stimuli, and when objects difficult to be distinguished are applied [v. Helmholtz and Baxt). The 
time required to direct the attention to a number consisting of 1 to 3 figures, Tigerstedt and 
Bergquist found to be 0.015 to 0.035 second. Alcohol and the anaesthetics alter the time; accord- 
ing to their degree of action, they shorten or lengthen it (.Kraplin). In order that two shocks 
applied after each other be distinguished as two distinct impressions, a certain interval must 
elapse between the two shocks—for the ear, 0.002 to 0.0075 second; for the eye, 0.044 to 0.47 
second; for the finger, 0.277 second. 
[The Dilemma.—When a person is experimented on, and he is not told whether the right or 
left side is to be stimulated, or what colored disc may be presented to the eye, then the time to 
respond correctly is longer.] 
[Drugs and other conditions affect the reaction time. Ether and chloroform lengthen it, 
while alcohol does the same, but the person imagines he really reacts quicker. Noises also 
lengthen it.] 
In sleep and waking, we observe the periodicity of the active and. passive conditions of the 
brain. During sleep there is diminished excitability of the whole nervous system, which is 
only partly due to the fatigue of afferent nerves, but is largely due to the condition of the cen- 
tral nervous system. During sleep, we require to apply strong stimuli to produce reflex acts. In 
the deepest sleep the psychical or mental processes seem to be completely in abeyance, so that a 
person asleep might be compared to an animal with its cerebral hemispheres removed. Towards 
the approach of the period when a person is about to waken, psychical activity may manifest 
itself in the form of dreams, which differ, however from normal mental processes. .They 
consist either of impressions, where there is no objective cause (hallucinations), or of voluntary 
impulses which are not executed, or trains of thought where the reasoning and judging powers 
are disturbed. Often, especially near the time of waking, the actual stimuli may so act as to 
give rise to impressions which become mixed with the thoughts of a dream. The diminished 
activity of the heart (§ 70, 3, c), the respiration (§ 126, 4), the gastric and intestinal movements 
(| 2x3, 4), the formation of heat (§ 216, 4), and the secretions, point to a diminished excitability 
of the corresponding nerve-centres, and the diminished reflex excitability to a corresponding 
condition of the spinal cord. The pupils are contracted during sleep, the deeper the latter is ; 
so that in the deepest sleep they do not become contracted on the application of light. The 
pupils dilate when sensory or auditory stimuli are applied, and the lighter the sleep the more is 
this the case; they are widest at the moment of awaking (Plotke). [Hughlings Jackson finds 
that the retina is more anaemic than in the waking state.] During sleep there seems to be a Sec. 374-] 
HYPNOTISM. 
873 
condition of increased action of certain sphincter muscles—those for contracting the pupil and 
closing the eyelids (Rosenbach). The soundness of the sleep may be determined by the inten- 
sity of the sound required to waken a person. Kohlschiitter found that at first sleep deepens 
very quickly, then more slowly, and the maximum is reached after one hour (according to 
Monninghoff and Priesenbergen after 1% hour); it then rapidly lightens, until several hours 
before waking it is very light. External or internal stimuli may suddenly diminish the depth of 
the sleep, but this may be followed again by deep sleep. The deeper the sleep the longer it lasts. 
[Durham asserts that the brain is anaemic, that the arteries and veins of the pia mater are con- 
tracted during sleep and the brain smaller; but is this cause or effect ?] 
The cause of sleep is the using up of the potential energy, especially in the central nervous 
system, which renders a restitution of energy necessary. Perhaps the accumulation of the de- 
composition-products of the nervous activity may also act as producers of sleep (? lactates— 
Preyer). Sleep cannot be kept up for above a certain time, nor can it be interrupted volunta- 
rily. Many narcotics rapidly produce sleep. [The “ disastolic phase of cerebral activity,” as sleep 
has been called, is largely dependent on the absence of stimuli. We must suppose that there 
are two factors, one central, represented by the excitability of the cerebrum, which will vary 
under different conditions, and the other external, represented by the impulses reaching the cere- 
brum through the different sense-organs. We know that a tendency to sleep is favored by removal 
of external stimuli, by shutting the eyes, retiring to a quiet place, etc. The external sensory im- 
pressions, indeed, influence the whole metabolism. Strumpell describes the case of a boy whose 
sensory inlets were all paralyzed except one eye and one ear, and when these inlets were closed 
the boy fell asleep, showing how intimately the waking condition is bound up with sensory affer- 
ent impulses reaching the cerebral centres.] 
[Hypnotics, such as opium, morphia, bromide of potassium, chloral, are drugs which induce 
sleep.] 
Hypnotism, or Animal Magnetism.—[Most important observations on this subject were made 
by Braid of Manchester, whose results are confirmed by many of the recentre-discoveries of Wein- 
hold, Heidenhain, and others.] Heidenhain assumes that the cause of this condition is due to 
an inhibition of the ganglionic cells of the cerebrum, produced by continuous feeble stimulation 
of the face (slightly stroking the skin or electrical applications), or of the optic nerve (as by 
gazing steadily at a small brilliant object), or of the auditory nerve (by uniform sounds); while 
sudden and strong stimulation of the same nerves, especially blowing upon the face, abolishes 
the condition. Berger attributes great importance [as did Carpenter and Braid long ago] to the 
psychological factor, whereby the attention was directed to a particular part of the body. The 
facility with which different persons become hypnotic varies very greatly. When the hypnotic 
condition has been produced a number of times, its subsequent occurrence is facilitated, e. g., 
by merely pressing upon the brow, by placing the body passively in a certain position, or by 
stroking the skin. In some people the mere idea of the condition suffices. A hypnotized per- 
son is no longer able to open his eyelids when they are pressed together. This is followed by 
spasm of the apparatus for accommodation in the eye, the range of accommodation is diminished, 
and there may be deviation of the position of the eyeballs ; then follow phenomena of stimula- 
tion of the sympathetic in the oblongata; dilatation of the fissure of the eyelids and the pupil, 
exophthalmos, and increase of the respiration and pulse. At a certain stage there may be a 
great increase in the sensitiveness of the functions of the sense-organs, and also of the muscular 
sensibility. Afterwards there may be analgesia of the part stroked, and loss of taste; the sense 
of temperature is lost less readily, and still later that of sight, of smell, and of hearing. Owing 
to the abolition or suspension of consciousness, stimuli applied to the sense-organs do not pro- 
duce conscious impressions or perceptions. But stimuli applied to the sense-organs of a hypno- 
tized person cause movements, which, however, are unconscious, although they stimulate volun- 
tary acts. In persons with greatly increased reflex excitability, voluntary movements may excite 
reflex spasms ; the person may be unable to co-ordinate his organs for speech. 
Types.—According to Griitzner, there are several forms of hypnotism: (i) Passive sleep, 
where words are still understood, which occurs especially in girls; (2) owing to the increased 
reflex Excitability of the striped muscles, certain groups of tnuscles may be contracted—a condi- 
tion which may last for days, especially in strong people; at the same time ataxia may occur, 
and the muscles may fail to perform their functions (artificial katalepsy). During the stage 
of lethargy in hysterical persons, the tendon reflexes are often absent (Charcot and Richer); (3) 
autonomy at call, i. e., the hypnotized person—in most cases the consciousness is still retained— 
obeys a command, in his condition of light sleep. When the hand is grasped or the head 
stroked, he executes involuntary movements—runs about, dances, rides on a stool, and the like ; 
(4) hallucinations occur only in some individuals when they waken from a deep sleep, the 
hallucinations (usually consisting of the sensation of sparks of fire or odors) being very strong 
and well pronounced; (5) imitation is rare, ordinary movements, such as walking, are easily 
imitated, the finer movements occur rarely. The “ echo-speech ” is produced by pressure upon 
the neck, speaking into the throat, or against the abdomen. Pressure over the right eyebrow often 
ushers in the speech. Color-sensation is suspended by placing the warm hand on the eye, or by 874 
STRUCTURE OF THE CEREBRUM. 
[Sec. 374. 
stroking the opposite side of the head (Cohn). Stroking the limbs in the reverse direction 
gradually removes the rigidity of the limbs and causes the person to awaken. Blowing on a part 
does so at once. Insane persons can be hypnotized. Disagreeable results follow only when the 
condition is induced too often and too continuously. 
Hypnotism in Animals.—A hen remains in a fixed position when an object is suddenly 
placed before its eyes, or when a straw is placed over its beak, or when the head of the animal 
is pressed on the ground and a chalk line made before its beak (Kircher’s experimentum mira- 
bile, 1644). [Langley has hypnotized a crocodile.] Birds, rabbits, and frogs remain passive 
for a time after they have been gently stroked on the back. Crayfish stand on their head and 
claws (Czermak). 
375. STRUCTURE OF THE CEREBRUM—MOTOR COR- 
TICAL CENTRES.—[Cerebral Convolution. —A vertical section of a 
cerebral convolution consists of a thin layer of gray matter externally enclosing 
a white core or central white matter (figs. 597, 598). The cortex consists of 
cells and fibres embedded in a “ molecular ” matrix, and to some of the nerve- 
cells nerve-fibres proceed from the white matter. The nerve-cells of the cor- 
tex vary in size, form, and distribution in the different layers and also in differ- 
ent convolutions. [The layers of cells lie more or less parallel to the surface 
of the convolutions, so that the gray matter is thereby divided into a series of 
zones or layers. Usually five layers can be recognized. The thickness of the 
gray matter is about 3 mm., but it is 2 mm. in some parts of the occipital lobe, 
and 4.2 mm. in some parts of the ascending frontal convolution.] Taking 
such a convolution as the ascending frontal or motor-area type, we get the 
appearances shown in fig. 598. It is covered on its surface by the pia mater. 
(1) The most superficial layer is narrow, and consists of much neuroglia, a 
network of branched nerve-fibrils, which together form the chief mass of the 
abundant molecular ground-substance; a few scattered small multipolar nerve- 
cells, and a layer of very fine medullated nerve-fibres, which traverse it in a 
horizontal direction. The surface of the layer seems to consist of neuroglia 
alone. (2) Layer of small pyramidal cells. A layer (.25 mm. to .75 
mm. in thickness) of close-set, small, angular or short pyramidal nerve-cells. 
The cells are pyramidal and small, and give off processes which ramify and 
break up in the general molecular ground-substance of the cortex. It has not 
been proved that they possess median basilar axis-cylinder processes. (3) 
Layer of large pyramidal cells. The thickest layer (.4 mm. to .1 mm.) 
or “ formation of the cornu ammonis,” consists of many layers of large pyra- 
midal cells, which are larger in the deeper than in the more superficial layers. 
They are not so closely packed together, as many granules lie between them. 
At the lowest part of this layer the cells are larger than elsewhere, presenting 
some resemblance to the cells of the anterior cornu of the gray matter of 
the spinal cord. By some it is described as a special layer and termed the 
ganglion-cell layer. This layer is specially well marked in those convolutions 
which are described as containing motor centres, but pyramidal cells resembling 
these are found over the whole cortex. The cells are connected by their axial- 
cylinder process to white nerve-fibres. Amongst the large cells are a few small 
angular-looking cells, which become more numerous lower down. (4)- The 
fourth layer—a narrow layer (.35 mm. to .15 mm.) is composed of numer- 
ous small, branched, irregular, ganglionic cells—the “ granular formation ” of 
Meynert. In the motor areas mixed with these are large pyramidal cells, dis- 
posed in groups, called “cell-clusters.” This layer is divided like the suc- 
ceeding one into -vertical columns by the groups of white fibres which pass 
outwards into the cortex from the central white matter. There are also hori- 
zontal fine medullated fibres in it. 
(5) The fifth layer next the central white matter (.1 mm. thick), and from 
which it is not everywhere sharply defined, contains scattered in it spindle- 
shaped fusiform branched cells—the claustral formation of Meynert—lying for Sec. 375.] 
STRUCTURE OF THE CEREBRUM. 
875 
Fig- 597- 
Fig. 598- 
Fig- 599- 
Fig. 597.—Vertical section of a motor cerebral convolution of man. I, superficial layer; 2, 
layer of small, and 3, of large pyramidal cells; 4, granule formation; 5, claustral forma- 
tion; m, medulla. Fig. 598.—Cortex of motor area of brain of monkey (x 150). 1, 
superficial layer; 2, small angular cells; 3, pyramidal cells; 4, ganglionic cells and cell- 
clusters; 5, fusiform cells (terrier, after Bevan Lewis). Fig. 599.—Cortex of occipital 
lobe. 1, superficial layer; 2, small angular cells; 3, 5, pyramidal cells; 4, granule layer; 
6, granules and ganglionic layer; 7, spindle-cells [Perrier, after Bevan Lewis). 876 
STRUCTURE OF THE CEREBRUM. 
[Sec. 375. 
the most part parallel to the surface of the convolution. It is broken up into 
vertical columns by the white fibres proceeding from the central white matter 
into the cortex. Then follows the central white matter (ni), consisting of 
medullated nerve-fibres, which run in groups into the gray matter, where they 
lose their myelin. The fibres are somewhat smaller than in the other parts of 
the nervous system (diameter Ytfan inch), and between them lie a few nuclear 
elements. 
It will be seen that no layer is composed exclusively of one form of cell. In 
the above, which represents the motor type, such as occurs in the “ motor 
areas ” of the brain, the layer is very thick, the pyramidal cells which it con- 
tains are both large and numerous, and in the fourth layer there are very large 
pyramidal cells (no /x to 50 fi), which are largest at the upper part of the as- 
cending frontal convolution.] 
[In the sensory type, as in the occipital lobe (fig. 599), the first and second 
layers are not unlike the corresponding layers in the motor type, and the fusi- 
form cells in the 
seventh layer also 
resemble the latter. 
The layer of pyra- 
midal cells (3) is not 
so large, while its 
deeper part, some- 
times called the“gan- 
glion - cell layer,” 
contains no large 
cells. (5) Between 
the two is (4), a 
layer with numerous 
angular granule-like 
bodies or cells, the 
“granule-layer.” The abundance of these small “ nuclear ” with “angular ” 
cells is the chief characteristic of the occipital region. There are also numerous 
horizontal medullated fibres in the fourth layer.] 
[The hippocampus or cornu ammonis, a portion of the cerebral cortex 
peculiarly modified, and in part projecting into the descending horn of the 
lateral ventricle, contains, besides a layer of neuroglia and some white matter on 
the surface, a regular series of pyramidal cells of the third layer, which give it 
a characteristic appearance. This is the part which varies most. The fourth 
and fifth layers are small, while the pyramidal cells of the third layer are re- 
markably long (fig. 600). 
[In the frontal non-motor region the third layer is much thinner than in the 
motor areas, while the layer of fusiform cells is well developed.] 
[It is to be remembered that the transition from one type to the other takes 
place gradually and that the transition from one anatomical region to another 
is very gradual.] 
[Pyramidal Cells of the Cortex.—Each cell is more or less pyramidal 
in shape, granular or fibrillated in appearance and with a large conspicuous 
nucleus. Each cell gives off several processes—(0) an apical process, which 
is often very long, and runs towards the surface of the cerebrum, and as it does 
so gives off lateral processes, which break up into fine fibrils. (3) The un- 
branched axial cylinder, median basilar process, which is an axial cylinder 
process, and becomes continuous with the axial cylinder of a nerve-fibre of the 
white matter. It ultimately becomes invested by myelin. Sometimes the axis- 
cylinder process divides at a node of Ranvier, like the T-shaped fibres of the 
spinal ganglion, (c) The lateral processes are given off chiefly near the 
Vli. 
Fd 
Fig. 600. 
C. Am. 
Cortex of the cornu ammonis (C. Am.), and a part of the Fascia dentata 
(Fd). Vli, inferior horn of the lateral ventricle, x 20. Sec. 375.] 
STRUCTURE OF THE CEREBRUM. 
877 
base of the cell, and they soon branch to form part of the ground plexus or 
molecular ground-substance of fibrils which everywhere pervades the gray 
Fig. 601.—Perivascular and pericellular lymph-spaces, a, capillary with a lymph-space com 
municating with the pericellular lymph-space b, round the cell a lymph-space c, containing 
two lymph-corpuscles, x I5°- Fig. 602.—Vertical section of a frontal convolution 
(Weigert’s method) x 5°- P> pia mater; 1-5, five layers of Meynert; a, superficial layer 
of connective-tissue; b—i, successive layers of medullated nerve-fibres; k, white matter. 
Fig. 603.—Section of a cerebral convolution stained by Golgi’s method. 1, neuroglia layer; 
2, layer of small cells; 3, layer of large pyramidal cells; 4, layer of irregular cells. 
Fig. 602. 
Fig. 603. 878 
NERVE-FIBRES IN THE CORTEX. 
[Sec. 375. 
matter. The largest pyramidal cells—those known as giant cells—in the motor 
areas maybe 110-50 /ubut the ordinary large pyramidal cells are 20 to 40 /z, 
and the small pyramidal cells (which have not been proved to possess an axial 
cylinder process) are 8-12 ju in breadth. The large pyramidal cells are trophic 
in function for the very long nerve-fibres which are connected with them.] 
[Golgi’s Method of staining Nerve-cells.—The nerve-cells are stained black by long 
immersion in silver nitrate or mercuric chloride solution after the brain is hardened in a chro- 
mium salt. The metal is deposited in, or rather on, the cell and its processes, and in this way 
the ramifications of these cells can be traced for a long distance.] 
Each cell is surrounded by a lymph-space in which it lies. The blood-vessels are provided 
with a perivascular space, which communicates with the pericellular lymph-space, as in fig. 
601. 
[Nerve-fibres in the Cortex.—The ordinary methods of hardening the brain do not enable 
us to detect the enormous number of medullated nerve-fibres in the gray matter. By using 
Exner’s osmic acid method, or Weigert’s or Pal’s method, we obtain such a result as is shown 
in fig. 602. Under the pia (P) is a layer of connective-tissue (a) devoid of nerve-fibres. Beneath 
it is a layer (b) occupying about the half of the outer layer, which is almost entirely taken up 
by medullated nerve-fibres; most of these are fine, but a few of them are coarse, and run parallel 
to the surface and tangential to the arc of the outer contour of the convolution. Internal to this 
is a layer of medullated fibres (r), which cross each other in various directions; while a similar 
network (of) occur in the small-celled layer. (2) In the layer of large pyramidal cells (3) 
there are bundles of medullated fibres, running radially (e); but at the lower part of this layer 
there is a very dense network (f), forming (in a Weigert’s preparation) a dense, dark band, 
corresponding to the outer layer of Baillarger. In the layers marked (g and h), which are 
partly in the third and partly in the fourth cortical layer, the radial arrangement is more 
marked and more compact, and the thick fibres are more numerous. In the middle is (h) a 
narrow dense network corresponding to Baillarger’s inner layer. The lower part of the fourth 
layer, and the whole of the fifth, are occupied by i. It is to be remembered that all the convo- 
lutions do not present exactly the same structure and arrangement (Obersteiner).] 
[The existence of such an enormous number of nerve-fibres passing from the 
central white matter into the cortex makes it evident that the white matter 
must be connected to the gray cortical matter by some means other than 
axis-cylinder processes, the prolongations of the median basilar processes of 
the pyramidal cells. Perhaps most of the white fibres entering the cortex, 
either as callosal, pyramidal, tegmental, or association fibres split up into 
fibrils to form a large part of the molecular ground-substance. We do not 
know if they become continuous anatomically with the fibrils.] 
[Variations.—The gray matter differs in different parts of the brain. In the gray matter of 
the cornu ammonis, the large pyramidal cells of (3) make up the chief mass (fig. 600) ; in the 
claustrum (4) is most abundant. In the central convolutions (ascending frontal and parietal), 
according to Betz. Mierzejewski, and Bevan Lewis, very large pyramidal cells are found in the 
lower part of the third layer. Similar cells have been found in the posterior extremities of the 
frontal convolutions in some animals—the posterior parietal lobule, and para-central lobule, all 
of which have motor functions. In those convolutions, which are regarded as subserving 
sensory functions, a somewhat different type prevails, e.g., the occipital gyri or annectant con- 
volution (B. Lewis). The very large pyramidal cells are absent, while the granule layer exists 
as a well-marked layer between the layer of large pyramidal cells and the ganglion cell-layer 
(fig- 599)-] 
[Fuchs finds that there are no medullated fibres either in the cortex or medulla until the end 
of the first month of life. The medullated fibres appear in the uppermost layer at the fifth 
month, and in the second at the end of the first year, the radial bundles in the deeper layers at 
the second month. The medullated fibres increase until the seventh or eighth year, when they 
have the same arrangement as in the adult.] 
[Results of Golgi’s Method.—Fig. 603 shows a general view of the nerve-cells of the 
cortex cerebri stained by Golgi’s method. The pyramidal cells give off branched protoplasmic 
processes and a central axial cylinder process which becomes continuous with a medullated 
nerve-fibre in the white matter (figs. 603, 604).] 
[Blood-Vessels.—The adventitia of the small cerebral vessels contains 
pigment and granular cells, filled with oil-granules. In the new-born child, 
the blood-vessels of the brain are beset with cells, filled with fatty granules. Sec. 375.] 
BLOOD-VESSELS OF THE CEREBRUM. 
879 
Perhaps the granules supply part of the material for the formation of the 
myelin sheath on the nerve-fibres. About the fifth year the fat is replaced by 
a yellow pigment. In adults, yellow or brown glancing pigment-granules are 
found in the adventitia of the arteries. In the adventitia of the veins there is 
no pigment, but generally some fat. The gray matter is much more vascular 
than the white, and when injected, a section of a convolution presents the ap- 
pearance shown in fig. 605. The nutritive arteries consist of—(a) the long 
medullary arteries (1) which pass from the pia mater through the gray 
matter into the central white matter or centrum ovale. They are terminal 
arteries, and do not communicate with each other in their course ; thus, they 
supply independent vascular areas; nor do they anastomose with any of the 
arteries derived from the ganglionic system of blood-vessels; 12 to 15 of them 
are seen in a section of a convolution. (b) The short cortical nutritive 
arteries (2) are smaller and shorter than the foregoing. Although some of 
them enter the white matter, they chiefly supply the cortex, where they form 
an open meshed plexus in the first layer (a), while in the next layer lb) the 
plexus of capillaries is dense, the plexus again being wider in the inner layers 
(0-1 
Fig. 604. 
Scheme of a transverse section of the cerebrum of a new-born rat by Golgi’s method [Cayat). A, 
corpus callosum; B, antero-posterior fibres arising from the large pyramidal cells ; C, 
lateral ventricle; a, large pyramidal cell whose axis-cylinder process passes into the anterior 
posterior layer; b, fibre of the corpus callosum bifurcating; c, callosal fibre; d, callosal 
fibre arising from a pyramidal cell; e, axis-cylinder process descending obliquely to enter 
the corpus callosum; f, final ramifications of a callosal fibre in the gray matter of the 
cortex; h, collateral fibre from a large pyramidal cell; g, epithelial cell ramifying in the 
surface of the cortex cerebri, n; i, fusiform cells with the axis-cylinder process ascending 
to the molecular layer; j, final ramification of a callosal fibre arising in the opposite side 
of the cortex. 
[Central or Ganglionic Arteries.—From the trunks constituting the 
circle of Willis (fig. in § 381), branches are given off, which pass upwards and 
enter the brain to supply the basal ganglia with blood. They are arranged in 
several groups, but they are all terminal, each one supplying its own area, nor 
do they anastomose with the arteries of the cortex.] 
Cerebral Arteries.—From a practical point of view, the distribution of 
the blood-vessels of the brain is important. The artery of the Sylvian fissure 
supplies the motor areas of the brain in animals; in man, the praecentral lobule 
is supplied by a branch of the anterior cerebral artery (Duret). The region 
of the third left frontal convolution, which is connected with the function of 
speech, is supplied by a special branch of the Sylvian artery. Those areas of 880 
lobes OF THE CEREBRUM. 
[Sec. 375- 
the frontal lobes whose injury results in disturbance of the intelligence, are 
supplied by the anterior cerebral artery. Those regions of the cortex cerebri, 
whose injury, according to Ferrier, causes hemiansesthesia, are supplied by the 
posterior cerebral artery. 
[In connection with the localization of the centres in the cortex, it is important to be thor- 
oughly acquainted with the arrangement of the cerebral convolutions. Each half of the 
outer cerebral surface is divided by certain fissures into five lobes—frontal, parietal, occipi- 
tal, temporo-sphenoidal, and central, or island of Reil. The frontal lobe (fig. 606) con- 
sists of three convolutions, with numerous secondary folds running nearly •horizontal, named 
superior (Fj), middle (F2), and inferior (F3) frontal convolutions. Behind these is a large 
convolution, the ascending frontal (A), which ascends almost vertically, immediately behind 
these— separated from them, however, by the praecentral fissure (f3), and mapped off behind by 
the fissure of Rolando, or the central sulcus (c).] 
[The parietal lobe (fig. 606, P) is limited in front by the fissure of Rolando, below in part by 
the Sylvian fissure, and behind by the parieto-occipital fissure. It consists of the ascending 
parietal (posterior central) convolu- 
tion (fig. 606, B), which ascends 
just behind the fissure of Rolando, 
and parallel to the ascending frontal, 
with which it is continuous below; 
above, it becomes continuous with 
the superior parietal lobule (P,), 
while the latter is separated from 
the inferior parietal lobule (“pit 
courbe”) by the interparietal sulcus. 
The inferior parietal lobule consists 
of (a) a part arching over the upper 
end of the Sylvian fissure, the supra- 
marginal convolution (P2), which is 
continuous with the superior tem- 
poro-sphenoidal convolution. Be- 
hind is the angular gyrus (P2/), 
which arches round the posterior 
end of the parallel fissure, and be- 
comes connected with the middle 
temporo-sphenoidal convolution.] 
[The temporo - sphenoidal or 
temporal lobe (fig. 606, T) con- 
sists of three horizontal convolutions 
—superior, middle, and inferior— 
the two former being separated by 
the parallel sulcus, while the whole 
lobe is mapped off from the frontal 
by the Sylvian fissure (S).] 
[The occipital lobe (fig. 606, 
O) is small, forms the rounded pos- 
terior end of the cerebrum, and is 
separated from the parietal lobe by 
the parieto-occipital fissure, which 
fissure is bridged over at the lower 
Pa.rt by the four annectant gyri 
(plis depassage of Gratiolet). It has three convolutions—superior (OJ, middle (02), and inferior 
(O.j)—on its outer surface.] 
[The central lobe or island of Reil, consists of five or six short, straight convolutions (gyri 
operti) radiating outwards and backwards from near the anterior perforated spot, and can only 
be seen when the margins of the Sylvian fissure are pulled asunder. The operculum, consist- 
ing of the extremities of the inferior frontal, ascending parietal, and frontal convolutions, lie 
outside it, cover it, and conceal it from view.] 
[On the inner or mesial surface of the cerebrum are the gyrus fornicatus (fig. 607, Gf), or 
convolution of the corpus callosum, which runs parallel to and bends round the anterior and 
posterior extremities of the corpus callosum, terminating posteriorly in the gyrus uncinatus or 
gyrus hippocampi (fig. 607, H), and ending anteriorly in a crooked extremity, the subiculum 
cornu ammonis (fig. 607, U). Above it is the calloso-marginal fissure (fig. 607, cm), and run- 
ning parallel to it is the marginal convolution (fig. 607), which lies between the latter fissure 
Fig. 605. 
I, i, medullary arteries; and i/, i/, in groups between 
the convolutions; 2, 2, arteries of the cortex cerebri; 
a, large meshed plexus in first layer; b, closer plexus 
in middle layer; c, opener plexus in the gray matter 
next the white substance, with its vessels (</). Sec- 375-] 
COMMISSURES OF THE BRAIN. 
and the margin of the longitudinal fissure; it is, however, merely the mesial aspect of the frontal 
and parietal convolutions. The quadrate lobule or praecuneus lies (fig. 607, Pi) between 
the posterior extremity of the calloso-marginal fissure and the parieto-occipital fissure; it is 
merely the mesial aspect of the ascending parietal convolution. The parieto-occipital fissure 
terminates below in the calcarine fissure (fig. 607, oc), and the latter runs backwards in the 
occipital lobe dividing it into two branches, oc', oc". Between the parieto-occipital and calca- 
rine fissures lies the wedge-shaped lobule termed the cuneus (fig. 607, Oz). The calcarine 
fissure indicates on the surface the position of the calcar avis or hippocampus minor, in the 
posterior cornu of the lateral ventricle. The dentate fissure or sulcus hippocampi (fig. 480, hi) 
marks the position of the elevation of the hippocampus major, or cornu ammonis, in the lateral 
ventricle. The temporo - sphenoidal lobe terminates anteriorly in the uncinate gyrus, 
Left side of the human brain (diagrammatic). F, frontal; P, parietal; O, occipital; T, temporo- 
sphenoidal lobe ; S, fissure of Sylvius; S/, horizontal, S//, ascending ramus of S; c, sulcus 
centralis, or fissure of Rolando; A, ascending frontal, and B, ascending parietal convolu- 
tion ; Fj, superior, F2, middle, and F3, inferior frontal convolutions; f, superior, and fv 
inferior frontal sulcus praecentralis; P, superior parietal lobule; P2, inferior 
parietal lobule, consisting of P2, supra-marginal gyrus, and P/, angular gyrus; ip, sulcus 
interparietalis; cm, termination of calloso-marginal fissure; 04, first, 02, second, 03, third 
occipital convolutions; po, parietal-occipital fissure; o, transverse occipital fissure; ov 
inferior longitudinal occipital fissure; Tx, first, T2, second, T3, third temporo-sphenoidal 
convolutions; lx, first, tv second temporo-sphenoidal fissures. 
Fig. 606. 
while, running along the former and the occipital lobes, is the collateral fissure (occipito-tem- 
poral sulcus), which marks the position of the eminentia collateralis in the descending cornu of 
the lateral ventricle, while it also separates the superior from the inferior temporo-occipital con- 
volutions (T4 and T5).] 
[Transverse or Commissural Fibres.—The corpus callosum unites the two cerebral 
hemispheres. Fibres originate from all parts of the cerebral cortex (but only to a small extent 
from the temporal convolutions), and converge to the thick flattened arched band of the corpus 
callosum, intercrossing in the white matter of the cerebrum with the fibres of the corona radiata, 
i. e., the fibres of the crusta and tegmentum, ascending to the cortex cerebri. They are supposed 
to connect corresponding convolutions in opposite hemispheres.] 882 
MOTOR AREAS OF THE BRAIN. 
[Sec. 375. 
[The anterior white commissure at the front of the third ventricle connects the temporo- 
sphenoidal lobes of opposite sides. It proceeds from one side through the inner and middle 
divisions of the lenticular nucleus to the opposite side of the brain. A very small part belongs 
to the olfactory tract.] 
[The middle or soft commissure of the third ventricle is really a part of the central gray 
matter.] 
[The posterior commissure connects chiefly the two optic thalami, and perhaps also the 
tegmentum on the two sides.] 
Association fibres pass from one convolution to another on the same hemisphere. 
Longitudinal Commissure.—The fornix begins in gray matter of the corpora albicantia, 
while as it arches backwards its posterior pillars diverge and pass in the walls of the descending 
horn of the lateral ventricle. 
Motor Areas or Regions.—In 1870 Fritsch and Hitzig discovered a series 
of circumscribed regions on the surface of the cerebral convolutions of the 
Median aspect of the right hemisphere. CC, corpus callosum divided longitudinally; Gf, 
gyrus fornicatus; H, gyrus hippocampi; h, sulcus hippocampi; U, uncinate gyrus; cm, 
calloso-marginal fissure; F, first frontal convolution; c, terminal portion of fissure of 
Rolando; A, ascending frontal; B, ascending parietal convolution and paracentral lobule; 
P/, praecuneus or quadrate lobule; Oz, cuneus; Po, parieto-occipital fissure; ov transverse 
occipital fissure; or-, calcarine fissure; oc/, superior, oc", inferior ramus of the same; D, 
gyrus descendens; T4, gyrus occipito-temporalis lateralis (lobulus fusiformis); T5, gyrus 
occipito-temporalis medialis (lobulus lingualis). 
Fig. 607. 
dog, whose stimulation by means of electricity causes co-ordinated movements 
in quite distinct groups of skeletal muscles of the opposite side of the body 
(fig. 609, I, II) [while stimulation of some adjacent areas is not followed by 
any such movements]. 
Methods—Stimulation.—The surface of the cerebrum is exposed in an animal (dog, 
monkey) by removing a part of the skull covering the so-called motor-convolutions and dividing 
the dura mater. When the convolutions are fully exposed, a pair of blunt non-polarizable 
(§ 328) needle electrodes are applied near each other to various parts of the cerebral surface. 
We may employ the closing or opening shock of a constant current, or the constant current 
may be rapidly interrupted, the current being of such a strength as to be distinctly perceived 
when it is applied to the tip of the tongue (Fritsch and Hitzig). Or, the induced current 
may be used, also of such a strength that it is readily felt when applied to the tip of the tongue 
(Ferrier, 1873). The cerebrum is completely insensible to severe operations made upon it. 
The areas of the cerebral cortex, whose stimulation discharges the character- 
istic movements, are regarded by some as actual centres, because the reaction- Sec. 375.] 
STIMULATION OF THE CORTEX. 
883 
time after stimulation of the centres and the duration of the muscular contrac- 
tion are longer than when the subcortical fibres which lead towards the deeper 
parts of the brain are stimulated. Another circumstance favoring this view 
is that the excitability of these areas is influenced by the stimulation of afferent 
nerves (Bubnoff and Heidenhain). It may be that these centres are acted 
upon by voluntary impulses in the execution of voluntary movements. Hence, 
they have been called 11 psychomotor centres." [At any rate, these areas have 
a definite relation to certain motor acts, and perhaps it is well to speak of them 
as “ areas of representation ” of the function to which they are related.] The 
motor areas of the cerebrum (dog, cat, sheep) are characterized by the presence 
of specially large pyramidal cells (Betz, Merzejewsky, Bevan Lewis); while 
similar cells were found by Obersteiner in the areas marked 4 and 8 (fig. 609), 
and Betz found them in the ascending frontal convolution of man, in the third 
frontal convolution, and in the island of Reil. O. Soltmann found that stim- 
ulation of the motor areas in newly-born animals is without result, while 
only the deeper fibres of the corona radiata are excitable. 
Modifying Conditions.—In the condition of deep narcosis produced by chloroform, ether, 
chloral, morphia, or in apncea, the excitability of the centres is abolished (Schiff), whilst the 
subcortical conducting parts still retain their excitability (.Bubnoff and Heidenhain). Small 
doses of these poisons and also of atropin at first increase the excitability of the centres. Mod- 
erate loss of blood excites them, while a great loss of blood diminishes and then abolishes the 
excitability (Munk and Orschansky). Slight inflammation increases, while cooling diminishes 
the excitability. If the cortex cerebri be removed in animals, the excitability of the fibres of 
the corona radiata is completely abolished about the fourth day, just as in the case of a peripheral 
nerve separated from its centre (.Albertoni, Dupuy, Franck and Pitres). 
Stimulation of Subcortical Parts.—As the fibres of the corona radiata 
converge towards the centre of the hemisphere, it is evident that, after removal 
of the cortex, stimulation of these fibres in the deeper parts of the hemisphere 
is followed by the same motor effects (Gliky and Eckhard). The stimulus is 
applied merely to a deeper part of the motor path. If the stimulus be applied 
to parts situated still more deeply, as for example to the internal capsule, 
general contraction of the muscles on the opposite side is the result. 
Time Relations of the Stimulation.—According to Franck and Pitres, the time which 
elapses between the moment of stimulation of the cortex and the resulting movement, after 
deducting the period of latent stimulation for the muscles, and the time necessary for the con- 
duction of the impulse through the cord and nerves of the extremities, is 0.045 second. Hei- 
denhain and Bubnoff found that, during moderate morphia narcosis, when the stimulating current 
was increased in strength, the muscular contraction and the reaction-time became shorter. After 
removal of the cortex, the occurrence of the muscular contraction from the moment of stimula- 
tion of the white matter is diminished % to The form of the muscular contraction is longer 
and more extended when the cortex, than when the subcortical paths are stimulated. If the 
animal (dog) be in a state of high reflex excitability, these differences disappear; in both cases 
the contraction follows very rapidly (.Bubnoff and Heidenhain). If the stimulus be very strong 
the muscles of the same side may contract, but somewhat later than those on the opposite side. 
If the motor areas for the fore and hind limbs be stimulated simultaneously, the latter contract 
somewhat after the former. 
Number of Stimuli.—If 40 stimuli per second be applied to a motor area, then the corre- 
sponding muscles yield 40 single contractions; while with 46 single stimuli per second there 
results a continued complete contraction (.Franck and Pitres). In one and the same animal, 
the same number of stimuli is required to produce a continuous contraction, whether the cortical 
centre, the motor nerve, or even the muscle itself be stimulated. With very feeble stimuli, 
summation of stimuli takes place, for the muscular contraction only begins after several in- 
effective stimuli have been applied. [It is generally held that the rhythm of a contracting 
muscle is the same as the rhythm of the stimuli applied to its motor nerve, but Schafer and 
Horsley contend that this holds good for rates of stimuli to about 10 or 12 per second. They 
find that the same is true for the cortex cerebri, corona radiata, and medulla spinalis, viz., that 
the muscular response does not vary with the rhythm, i.e., number of stimuli per sec.), but 
that the rhythm is constant—about 10 per sec.— and independent of the number of stimuli per 
sec., provided they are above 10 per sec. applied to these parts. Indeed, all voluntary contrac- 884 
ANATOMY OF DOG’S BRAIN. 
[Sec. 375. 
tions show a smilar rate of undulation in the muscle-curve. Perhaps the rhythm of the efferent 
impulses is modified in the motor nerve-cells of the spinal cord.] 
[The matter, as regards electrical stimulation of the cortex cerebri, resolves 
itself into this, that stimulation of certain cortical areas always causes contrac- 
tion in definite muscles or groups of muscles, resulting, as a rule, in definite 
co-ordinated movements on the opposite side of the body ; the areas have been 
called “motor areas.” In some cases, however, stimulation of an area on 
one side results in bilateral movements in the case of corresponding muscles on 
opposite sides of the body, that usually act together, e.g., those of the eyes 
and trunk. They have been mapped out and ascertained in a large number of 
animals, and the question comes to be—Are there similar areas in man ?] 
Primary Fissures and Convolutions of the Dog’s Brain.—The position of the motor 
centres in the dog’s brain is indicated in fig. 609, I, and II. The dog’s brain is marked by two 
View of the brain from above (semi-diagrammatic). S1; end of ramus of the Sylvian fissure. 
The other letters refer to the same parts as in fig. 606. 
Fig. 608. 
“ primary fissures,” viz., the sulcus cruciatus (S), which intersects the longitudinal fissure at a 
right angle at the junction of its anterior with its middle third. This fissure has been called the 
sulcus frontalis, or the fissura coronalis. [It is bounded in front and behind by the “ sigmoid 
gyrus.”] The second primary fissure is the fossa Sylvii (F). Four “ primary convolu- 
tions,” in addition, are arranged with reference to these primary fissures. The first primary con- 
volution (I), in the form of a sharply-curved knee, embraces the fossa Sylvii (F). The second 
convolution (II) runs nearly parallel to the first. The fourth primary convolution (IV) bounds 
the longitudinal fissure, and is separated from its fellow of the opposite side by the falx cerebri; 
anteriorly it embraces the sulcus cruciatus (S), so that it is divided into two parts by this sulcus, Sec. 375.] 
dog’s BRAIN. 
885 
a part, the gyrus prsecruciatus or proefrontalis, lying in front of the sulcus, and the gyrus post- 
cruciatus (postfrontalis) lying behind it. The third primary convolution (III) runs parallel to the 
fourth. Some authors count the convolutions from the longitudinal fissure outwards. In fig. 
609, I and II, the motor areas or centres are indicated by dots on the individual primary con- 
Fig. 609. 
I, Cerebrum of the dog from above; II, from the side; I, II, ill, iv, the four primary con- 
volutions,—s, sulcus cruciatus; F, Sylvian fossa; o, olfactory lobe; p, optic nerve; i, 
motor area for the muscles of the neck; 2, extensors and abductors of the fore limb; 3, 
flexors and rotators of the fore limb; 4, the muscles of the hind limb; 5, the facial 
muscles; 6, lateral switching movements of the tail; 7, retraction and abduction of the fore 
limb; 8, elevation of the shoulder and extension of fore limb (movements as in walking); 
9, 9, orbicularis palpebrarum, zygomaticus, closure of the eyelids. II, a, a, retraction and 
elevation of the angle of the mouth; b, opening of the mouth and movements of the oral 
centre; c, c, platysma; d, opening of the eye. I, t, thermic centre, according to Eulen- 
burg and Landois. Ill, cerebrum of the rabbit from above; IV, cerebrum of the pigeon 
from above; V, cerebrum of the frog from above; VI, cerebrum of the carp from above— 
(in all these r>is the olfactory lobe; 1, cerebrum; 2, optic lobe; 3, cerebellum; 4, medulla 
oblongata). 886 
STIMULATION OF THE CENTRAL AREAS. 
[Sec. 375. 
volutions. We must remember, however, that the centres are not mere points, but that they vary 
in size from that of a pea upwards, according to the size of the animal. Motor areas have been 
mapped out in the brain of the monkey, rabbit, rat, bird, and frog. 
Position of the Motor Centres (Dog).—Fritsch and Hitzig, in 1870, mapped out the fol- 
lowing motor areas, whose position may be readily found on referring to fig. 609 : X, is the centre 
for the muscles of the neck; 2, for the extensors and adductors of the fore limb ; 3, for the 
flexion and rotation of the fore leg; 4, for the movements of the hind limb, which Luciani and 
Tamburini resolved into two antagonistic centres; 5, for the muscles of the face, or the facial 
centre. In 1873, Ferrier discovered the following additional centres : 6, for the lateral switch- 
ing movements of the tail; 7, for the retraction and abduction of the fore limb; 8, for the 
elevation of the shoulder and extension of the fore limb, as in walking; the area marked 
9, 9, 9, controls the movements of the orbicularis palpebrarum, and of the zygomaticus (closure 
of the eyelids), together with the upward movement of the eyeball and narrowing of the pupil. 
Stimulation of the areas a, a (fig. II) is followed by retraction and elevation of the angle of the 
mouth, with partial opening of the mouth; at b, Ferrier observed opening of the mouth with pro- 
trusion and retraction of the tongue, while the dog not unfrequently howled. He called this 
centre the “ oral centre.” Stimulation of c c causes retraction of the angle of the mouth, owing 
to the action of the platysma, while cf causes elevation of the angle of the mouth and of one half 
of the face, until the eye may be closed, just as in 9. Stimulation of d is followed by opening of 
the eye and dilatation of the pupil, while the eyes and head are turned towards the other side. 
According to H. Munk, the prefrontal region has an influence upon the attitude of the body (?). 
The perineal muscles contract when the gyrus postcruciatus is stimulated. Stimulation of the 
gyrus praecruciatus on its anterior and sloping aspect causes movements in the pharynx and 
larynx. 
[The motor areas in the dog are not very sharply defined, and indeed they 
may overlap somewhat, so that the localization of representation of movement 
in the dog’s cortex is much less perfect than in the higher animals, e. g., mon- 
key. In the rabbit and still lower vertebrates the localization is still less pre- 
cise and more diffuse.] 
[Experiments on monkeys indicate that in them the motor areas are more 
sharply defined from each other, and that there is a great differentiation of 
representation of movement in the cortex of the anthropoid apes as compared 
with the dog. In man this differentiation of the representation of movements 
appears to be more precise still.] 
[In birds, such as the dove and hen, the limb muscles do not appear to be 
represented in the cortex, but in the owl and hawk there is representation of 
the hind limbs in the cortex (Schrader).] 
The position of the individual motor areas may vary somewhat, and they 
may be slightly different on the two sides (Luciani and Tamburini'). 
Strong Stimuli.—If the stimulation be very strong, not only the muscles 
on the opposite side, but those on the same side, may contract. These latter 
movements belong to the class of associated movements, and are due to conduc- 
tion through commissural fibres. Those muscles, which usually (muscles of 
mastication) or always (muscles of eye, larynx, and face) act together, appear 
to have a centre not only in the opposite but also in the hemisphere of the same 
side (.Exner). [All observers have found that stimulation of the facial centre 
causes identical (associated) movements on both sides of the face, so that both 
sides of the face seem to be represented in each hemisphere. Schafer and 
Horsley’s experiments make it very probable that some other muscles, e. g., 
some of the trunk muscles, pectorals, and recti abdominis, are represented bi- 
laterally in the hemispheres. This is an important point in relation to recovery 
after the supposed destruction of a centre, and has an intimate bearing on the 
question of “Substitution,” in reference to the restoration of nerve-function 
(p. 868).] 
Strong stimulation of the motor regions may give rise in dogs to a complete general con- 
vulsive epileptic attack, which usually begins with contractions of the groups of muscles espe- 
cially related to the stimulated centre (Ferrier, Eulenburg and Landois, Albertoni, Luciani and 
Tamburini) ; then often passes to the corresponding limb of the opposite side (associated move- Sec. 375.] 
CEREBRAL EPILEPSY. 
887 
ments); and lastly, all the muscles of the body are thrown into tonic and then into clonic spasms. 
The opposite side of the body has been observed to pass into spasms from below upwards, after 
the contractions were developed in the other side. The spasmodic excitement passes from centre 
to centre, an intermediate motor region never being passed over. After this condition has once 
been produced, the slightest stimulation may suffice to bring on a new epileptic attack (§ 373). 
During the attack the cerebral circulation is accelerated. According to Eckhard and Danillo, 
epileptic attacks cannot be discharged from the posterior part of the cerebrum by means of weak 
currents. Stimulation of the sub-cortical white matter causes epilepsy, which, however, begins 
in the muscles of the same side (Bubnoff and Heidenhain). These contractions are due to an 
escape of the electrical current, which thus reaches the medulla oblongata (§ 373). 
Mechanical stimulation, e.g., scraping the motor areas for the limbs, 
produces movements in these parts (Luciani). 
Cerebral Epilepsy.—It is of great practical diagnostic importance to as- 
certain if stimulation of the motor areas in man, due to local diseases (inflam- 
mation, tumors, softening, degenerative irritation), causes movements. [Hugh- 
lings-Jackson has shown that local diseases of the cortex may cause spasmodic 
contractions in certain groups of muscles, a condition known as “Jacksonian 
Epilepsy,” and he explains in this way the occurrence of unilateral local epi- 
leptiform spasms, which were observed by Ferrier and Landois to occur after 
inflammatory irritation.] Luciani observed these spasms in dogs, and some- 
times they were so violent and general as to constitute an attack of epilepsy. 
This condition became hereditary, and the animals ultimately died from epi- 
lepsy (§ 373). According to Eckhard, epileptic attacks are never produced by 
stimulation of the surface of the posterior convolutions. [In passing from apes 
to carnivora, epilepsy as a result of electrical stimulation of the cortex is far 
more readily produced in the latter animals than in the former. Indeed, in 
the Orang, Beevor and Horsley never observed epilepsy to follow excitation of 
any part of the cortex.] 
If certain motor areas are extirpated, the epileptic attack is absent from the muscles controlled 
by these areas (Luciani). Separation of the motor cortical area by means of a horizontal section 
during an attack cuts short the latter (Muni). During an epileptic attack it is possible to excise 
the motor area of one extremity, and thus exclude this limb from the attack whilst the rest of the 
body is convulsed. 
Drugs.—The continued use of potassium bromide prevents the production of epilepsy on 
stimulating the cortical areas. 
Chemical Stimulation.—Substances such as occur in urine, e. g., kreatinin, 
kreatin, acid potassic phosphate, and sediment of urates, when sprinkled on the 
motor areas of the dog, cause pronounced eclampsic, clonic convulsions, which 
recur spontaneously, and are followed by deep coma. These symptoms are 
like those of uraemic poisoning. The sensory centres, especially that for 
vision, seem also to be affected by chemical stimulation (Landois). 
[Motor Centres in the M'onkey.—Ferrier has mapped out a large number 
of centres on the outer surface of the brain in the monkey, and to each centre 
he has given a number. These numbers have been transferred to correspond- 
ing convolutions on the human brain, numbered accordingly. These areas are 
specially distributed on the convolutions around the fissure of Rolando, includ- 
ing in the monkey the posterior extremities of the posterior and middle frontal 
convolutions, the ascending frontal, ascending parietal, and part of the parietal 
lobule.] 
[Areas mapped out by Ferrier.—Fig. 610 represents these areas transferred to the corre- 
sponding areas in man. (1) On the superior parietal lobule (advance of the opposite hind limb, 
as in walking. (2), (3), (4) Around the upper extremity of the fissure of Rolando (complex 
movements of the opposite leg and arm, and of the trunk, as in swimming), (a), (b), (c), (d) 
On the ascending parietal or posterior central convolution (individual and combined movements 
of the fingers and wrist of the opposite hand, or prehensile movements). (5) Posterior end of 
the superior frontal convolution (extension forward of the opposite arm and hand). (6) Upper 
part of the ascending frontal or anterior central convolution (supination and flexion of the oppo- 888 
MOTOR AREAS IN MONKEYS. 
[Sec. 375. 
site fore-arm). (7) Middle of the same convolution (retraction and elevation of the opposite 
angle of the mouth). (8) At the lower end of the same convolution (elevation of the ala nasi 
and upper lip, and depression of the lower lip on the opposite side). (9), (10) Broca’s convolution 
(opening of the mouth with protrusion and retraction of the tongue—aphasic region). (11) 
Between 10 and the lower end of the ascending parietal convolution (retraction of the opposite 
angle of the mouth, the head turns towards one side). (12) Posterior part of the superior and 
middle frontal convolutions (the eyes open widely, the pupils dilate, and the head and eyes turn 
towards the opposite side). (13), (13O Supra-marginal and angular gyrus (the eyes move 
towards the opposite side, and upwards or downwards—centre of vision). (14) Superior tem- 
poro-sphenoidal convolution (pricking of the opposite ear, pupils dilate, and the head and eyes 
turn to the opposite side—hearing centre).] 
Fig. 610. 
The brain with the chief convolutions (after Ecker). See also figs. 624, 625 in their relation to 
the skull. The numbers 1 to 14, and the letters a to d, indicate cortical areas (p. 887). S, 
Sylvian fissure; C, central sulcus, or fissure of Rolando; A, anterior, and B, posterior cen- 
tral convolutions; Fj, upper, F2, middle, and Fs, lowest frontal convolutions; fv superior, 
and fv inferior frontal fissure ; fv sulcus prsecentralis; Px, superior, P2, inferior parietal lobe, 
with P2, gyrus supra-marginalis; Pj1, gyrus angularis; ip, sulcus inter-parietalis; cm, end 
of calloso-marginal fissure; O,, 02, 03, occipital convolutions; po, parieto occipital fissure ; 
Tj, T2, T3, temporo sphenoidal convolutions; Kp K2, K3, points in the coronal suture; 41; 
42, in the lambdoidal suture. 
[Experiments on Monkeys.— Electrical stimulation of the anterior part 
of the frontal lobes yields negative results; but behind the anterior end of the 
sagittal limb of the precentral sulcus there are lateral movements of the head 
and eyes. If the anterior third or fourth be removed, Schafer and Horsley 
observed no motor paralysis nor any deficiency of general or special sensibility. 
Excitation of the external surface (motor area) led Ferrier to map out the Sec. 375.] 
MOTOR AREAS IN MONKEYS. 
889 
areas named on p. 887. Schafer and Horsley’s experiments agree with Ferrier’s, 
and they map out the motor area into a number of main areas, each of which 
is particularly concerned with the movement of a particular part or limb, and 
in some of which centres concerned with more specialized movements may be 
marked out. The arm-area is roughly triangular (fig. 611), and “ occupies most 
of the upper half of the ascending parietal and ascending frontal gyri, from a 
little beneath the level of the sagittal part of the precentral fissure below, nearly 
to the margin of the hemisphere above, together with the adjacent part of the 
frontal lobe below the small antero-posterior sulcus.” It bends round and is 
continuous with a part of the marginal gyrus. The special movements of the 
arm are indicated in fig. 611.] 
[Within any particular area there is motor representation of the movements 
capable of being executed by the corresponding muscles. Thus in the arm- 
area the movements represented are from above downwards, those at the shoul- 
der, elbow, wrist, digits, and thumb, and of course all the complex com- 
binations of movements which these parts can execute.] 
[The face-area, lying ventral to the arm-area, gives rise not only to move- 
Fig. 611. 
Fig. 612. 
Fig. 6il.—Diagram of the motor areas on the outer surface of a monkey’s brain (Horsley and 
Schafer. Fig. 612.—Diagram of the motor areas on the marginal convolution of a mon- 
key’s brain (Horsley and Schafer). 
ments of the facial muscles, but also of the whole of the upper end of the ali- 
mentary tube. It comprises the whole of the ascending parietal and frontal 
convolutions below the arm-area, down to the fissure of Sylvius, and including 
the external surface of the operculum. As is shown in fig. 6n, at the upper 
part of the area the eyelids are represented, below or ventral to this curve 
successively the movements of the mouth, tongue, those for mastication 
and swallowing, and at the lower or ventral end of the ascending frontal 
convolution is the area for the larynx and phonation (p. 890).] 
[The head-area—i. e., for movements of the head brought about by the 
muscles of the neck—or area for visual direction—comprise part of the frontal 
lobe from the margin of the hemisphere to the face-area. In front it is bounded 
by the non-excitable part of the frontal lobe. Its stimulation gives the results 
obtained by Ferrier on stimulating his No. 12 centre. Occupying the ventral 
part of the head-area on the posterior extremity of the middle frontal convolu- 
tion—i. e., in front of the precentral sulcus—is the area for the movements of 
the eyeballs or “ area for the eyes ” (fig. 611).] 
[The leg area, or “ area for the hind limb,” is partly situate on the 
mesial surface—i. e., the marginal convolution—but it extends over to the MOTOR AREAS OF CORTEX. 
[Sec. 375. 
external surface from the parieto-occipital fissure nearly to the level of the 
anterior end of the small sulcus marked leg (fig. 607). Within this area are 
to be distinguished from before backwards special areas for the hip, knee, 
ankle, hallux, and digits.] 
[The trunk-area scarcely extends over the margin to reach the external 
surface. It exists on the marginal convolution lying between the area for the 
head in front, and that for the leg behind.] 
[Schafer and Horsley have extended Ferrier’s researches, and shown that 
motor centres exist in the marginal convolution (fig. 612), which is excit- 
able only in that portion corresponding in extent (antero-posteriorly) to the 
excitable portion of the outer surface of the hemisphere. Anteriorly it reaches 
forward to a line which is opposite the junction of the posterior and middle 
thirds of the superior frontal convolution (centre 12), while posteriorly it 
extends backwards opposite to the parietal lobule, including the paracentral 
lobule, which contains large multipolar pyramidal motor cells. The rest of 
the mesial surface is inexcitable. They find that the centres are arranged from 
before backwards in the following order: (1) Movements of the head—this 
area is very small, and belongs to the large head-area on the external surface ; 
(2) of the fore-arm and hand; (3) of the arm at the shoulder; (4) of the 
upper dorsal part of the trunk ; (6) of the leg at the hip; (7) of the lower 
leg at the knee ; (8) of the foot and toes.] 
[Just as there are differences in motor representation in the cortex as we 
descend in the animal scale, so there are differences amongst animals belonging 
to the same group, e.g., monkeys. Comparing a Macacque monkey with an 
Orang, it is difficult to get single primary movements uncomplicated by move- 
ments of other parts on stimulation of the cortex of a Macacque monkey, but 
in the Orang single primary movements are readily obtained, and this seems 
to demonstrate the great advance in evolution of function in the Orang’s cor- 
tex above that of the Macacque. Moreover, in the Orang, instead of the ex- 
citable area of the cortex being continuous, as in the Macacque, it is in the 
Orang much interrupted by spaces from which no effect can be obtained even 
by the application of strong stimuli. Thus excitable areas are separated from 
each other by inexcitable areas. Direct observation has shown that for certain 
centres at least a similar interrupted mode of representation exists in man (.Bee- 
vor and Horsley). It appears in addition that motor representation in the cor- 
tex is found only on the summits of the gyri of the convoluted surface, while at 
a sulcus it is inexcitable.] 
Excitation of the Area AS produces movements of the arm (fig. 615). These vary ac* 
cording to the spot stimulated, but towards the anterior part of the area movements of the wris1 
and fore-arm, towards the posterior part movements of the arm and shoulder, are more fre- 
quently the result of the excitation. Excitation of Tr produces movements of the trunk, gen- 
erally arching and rotation. Those movements which are called forth by stimulating the anterior 
part of the area are usually confined to the upper part of the trunk (thoracic region), and are 
often associated with movements of the shoulder and arm ; those called forth by stimulating the 
posterior part are movements of the abdominal and pelvic regions and of the tail, and are often 
associated with movements of the hip and leg. Excitation of the area L produces movements 
in the lower limb. These vary according to the part stimulated, extension of the hip being 
especially associated with excitation of the anterior part of the area, and contraction of the ham- 
strings with excitation of the middle part.] 
[Motor Representation of the Larynx.—In this connection we must 
remember that the larynx subserves the two purposes of respiration and phona- 
tion. The bulb is the main seat of respiration, and recent researches by Krause, 
Horsley, and Semon show that there seems to be independent representation of 
the larynx in the bulb for respiratory laryngeal movements, and independent Sec. 375.] 
MOTOR CENTRES IN MAN. 
891 
of that for thoracic movements. Moreover, the larynx is independently repre- 
sented in the bulb for the movements of phonation; thus a purely reflex cry is 
produced in animals after removal of the cerebrum, and stimulation of one 
side of the bulb near the calamus scriptorius causes adduction of the vocal cord 
on the same side. Perhaps the abductors and adductors are represented inde- 
pendently. 
In the cortex cerebri the representation of the larynx seems to be independ- 
ent of that of respiration, and amongst animals the cat has the greatest, the 
monkey the least development of representation in the cortex, while the respira- 
tory movements are also represented in the cortex.] 
[Horsley and Semon find that “ there is in each cerebral hemisphere an area of bilateral repre- 
sentation of adductor movements of the vocal cords, situated in the monkey just posterior to the 
lower end of the prsecentral sulcus at the base of the third frontal gyrus, and in the carnivora in 
the prsecrucial and neighboring gyrus. This area has a focus of intensest representation in the 
anterior half of the foot of the ascending frontal convolution. Stimulation of this point pro- 
duces complete bilateral adduction of the vocal cords, which lasts as long as the stimulation is 
continued.” Thus unilateral stimulation produces a bilateral effect, so that with bilateral repre- 
sentation of both sides of the larynx in one hemisphere, excision of that centre does not neces- 
sarily produce unilateral paralysis of a vocal cord; indeed, the phonatory centre and even one 
hemisphere has been excised, yet on stimulation of the remaining phonatory cortical area bi- 
lateral adduction occurs. The fibres from the cortical area run in the corona radiata, those for 
respiration run first in the anterior limb of the internal capsule, and at a lower plane in the region 
of the genu. Those that subserve phonation, and excitation of which produces adduction of the 
vocal cords, are grouped just posterior to the genu (cat), and at a lower plane in the posterior 
limb. These fibres proceed to form connections with the bulbar laryngeal apparatus (Horsley 
and Semon).'] 
[It will be noticed that the areas are spoken of in terms of the part of the 
body which is affected by the stimulation of a particular area. There is reason 
for believing, however, that what is represented in the cerebral cortex is not 
mere muscular mass, but rather the variety and complexity of movements cap- 
able of being executed by these muscles. Thus one speaks not of representa- 
tion of the muscles in the motor areas, but of “ representation of muscular 
movements.” This view is supported by a study of the relative size of certain 
motor areas as compared with the size of the area of the body which such 
areas represent. Thus the thumb area is relatively far larger than that of the 
shoulder or area for the hip, but the difference is explained by the great com- 
plexity of movements executed by the thumb as compared with the simpler 
movements of the shoulder.] 
[Do similar Centres exist in Man ?—The results of clinical and patho- 
logical investigations show that similar, although not absolutely identical, 
areas exist in man. The motor areas, or those which have a special relation to 
voluntary motion in man, exist in part in the convolutions bounding the fissure 
of Rolando, and occupy the “ central convolutions,” i. e., the ascending 
frontal and ascending parietal convolutions along with the superior parietal 
lobule, and along the mesial surface of the hemisphere, the paracentral lobule, 
and precuneus (fig. 614). In this region the upper third of the ascending 
frontal and parietal convolutions, along with the superior parietal, are the leg 
area (fig. 614, leg), the middle third of the ascending parietal and ascending 
frontal for the arm, and the upper part of the lowest third of these convolu- 
tions for the face, while the very lowest part of the ascending frontal convolu- 
tion is the area for the movements of the lips (lips) and tongue (T). (Com- 
pare figs. 611, 616.) The last area, with the posterior extremity of the third 
left frontal convolution, is the centre for voluntary speech. We cannot say 
whether these “ centres ” are sharply mapped off from each other. In any case 
a very strong stimulation of one centre may involve an adjacent area. So far 892 
REMOVAL OF CORTEX CEREBRI. 
[Sec. 375. 
as is yet known, centres Nos. 5 and 12, as represented in the monkey’s brain— 
those on the posterior extremity of the superior and middle frontal convolu- 
tions,—(5) for extension forward of the arm and hand, and (12) for opening 
the eyes and turning the head towards the opposite side (as in surprise), are 
not represented in the human brain. So accurately have certain of these areas 
been located, that surgeons, in suitable cases, have been able not only to 
diagnose the position of a tumor causing certain symptoms, but also to 
excise it.] 
Bilateral Movements.—Movements in both sides of the body following 
upon excitation of one hemisphere are common, but many of these movements 
cannot be claimed as examples of strictly bilateral representation in the cortex. 
The movements of the trunk (rectus, abdominis, etc.), tongue, turning the 
head, and conjugate deviation of the eyeballs are often classed as such, but in 
reality they are not so. The movements of pouting of the lips, mastication, 
swallowing, and movements of the soft palate, adduction of the vocal cords 
seem to be truly bilateral movements (Beevor and Horsley).~\ 
[We may, therefore, assert as a general proposition that the muscles of one 
lateral half of the body are regulated by certain areas in the opposite cerebral 
hemisphere, except in the case of bilateral muscles usually acting together.] 
[Gowers maintains that the motor region is not exclusively motor, but that destruction of this 
area also leads to some loss of sensation. Starr also asserts that perceptions occur in the gray 
matter of the cortex of the “ central ” region and parietal convolutions and that the various 
sensory areas for the various parts of the body lie about, and coincide to some extent with, the 
motor various areas for similar parts, but the sensory area is more extensive than the motor area, 
extending into the parietal behind the motor area, which is confined to the ascending frontal and 
parietal convolutions.] 
II. Method of Destruction or Ablation of Parts of the Cortex.— 
Much confusion in this matter has arisen from comparing the results obtained 
on animals of different species. [It seems quite certain that the results obtained 
in the dog are quite different from those in the monkey. The motor areas 
may be simply excised with a knife, or the surface of the brain may be 
washed away with a stream of water, as was done by Goltz in dogs.] 
[In the dog, the areas which are described as motor may be removed either by the knife (Her- 
mann) or by means of a stream of water so directed as to wash away the gray matter (Goltz). 
In both cases, although there was some paralysis on the opposite side of the body, this was but 
temporary, for the paralysis disappeared within a few days, the animals having very decided con- 
trol over their muscles, although Goltz admits that certain acts, especially those which the dogs 
had been trained to execute, e. g., giving a paw, were executed “ clumsily,” indicating some 
failure of complete control, which Goltz ascribed to loss of tactile sensibility. Goltz thinks that 
the extent of the injury has more to do with the result than the locality. The restoration of 
motion was not due to the action of the corresponding centre of the opposite side, as destruction 
of this centre, although it produced the usual symptoms on the side which it governed, had no 
effect on the previous result (CarvilleandDuret).~\ 
[In the monkey, the experiments of Ferrier tend to show that destruction 
of a motor centre, e. g., that for the arm, results in permanent paralysis of the 
arm of the opposite side, and if the centres for the arm and leg are destroyed, 
there is permanent hemiplegia of the opposite side. “ In order that the hemi- 
plegia or paraplegia produced by cortical ablation shall be complete, it is nec- 
essary to include the part of the marginal gyrus corresponding in longitudinal 
extent to the excitable areas of the external surface.” The amount of paralysis 
produced by ablation of the marginal gyri alone is as great as that caused by 
removal of the much more extensive external areas ; but the complexity of 
the muscular movements which are governed from these areas is much greater 
than in those governed from the marginal gyrus (Schafer and Horsley).~\ Sec. 375.] 
REMOVAL OF CORTEX CEREBRI. 
893 
[In man, records of destructive lesions of the motor areas in whole or part 
have now accumulated to such an extent as to leave no doubt that if there be, 
say, a destructive lesion of the middle third of the cortex of the ascending 
frontal and ascending parietal convolutions, there will be paralysis of the arm of 
the opposite side; and the same is true for the other centres.] 
In extirpation or ablation of the motor centres, again, much confusion 
has arisen from comparing the results obtained on different animals. In the dog 
there is no permanent motor paralysis, in the monkey and man there is. The 
difference is this, that in the dog the lower centres, perhaps the basal ganglia, 
are able to subserve the execution of those co-ordinated movements required for 
standing, progression, etc. As we proceed higher in the animal scale, the 
motor cortical centres assume more and more of the functions subserved by the 
basal ganglia in lower animals. There is, as it were, a gradual displacement of 
motor centres connected with volitional motor acts to the cortical region, as we 
ascend in the zoological scale.] 
Differences in Animals.—The higher the development of the intelligence of animals, the 
more have their movements been learned, and the more have they gradually come to be controlled 
by the will; in them the disturbance of the motor phenomena becomes more pronounced and per- 
sistent after destruction of the cortical psychomotor centres. Whilst in the lower vertebrates, 
including the birds, extirpation of the whole hemispheres does not materially interfere with move- 
ments, the co-ordinated reflex movements being sufficient—in dogs occasionally, but exception- 
ally, extirpation of several motor areas produces visible permanent disturbance of motor acts— 
and in monkeys and men (§ 378) the paralytic phenomena may be intense and persistent. 
Acquired Movements.—Among the movements performed by men are many which have 
been acquired after much practice, and have been subjected to voluntary control, eg., the move- 
ments of the hands for many manual occupations. After a lesion of certain motor areas, such 
movements are re-acquired only very slowly and incompletely, or it may be not at all. [The in- 
terference with these finer acquired movements sometimes becomes very marked in lesions of the 
motor areas produced by hemorrhage, and in some cases of hemiplegia.] Those movements, 
however, which are, as it were, innate [or as they are sometimes termed fundamental, in 
opposition to acquired], and are under the control of the will without much practice—such as 
the associated movements of the eyes, face, some of those of the limbs—are either rapidly 
restored after the lesion, or they appear to suffer but slightly after a lesion of the cerebral cortex ; 
the facial muscles are never so completely paralyzed as from a lesion of the trunk of the facial 
nerve ; usually the eye can be closed in the former case. The movements necessary for sucking 
have been performed by hemicephalic infants. 
Theoretical.—Hitzig ascribes the disturbance of movement, after the removal of the motor 
centres, to the loss of the “muscular sensibility.'’’ Schiff refers it to the loss of tactile sensibility. 
According to Ferrier, the tactile and sensory impressions are not appreciably diminished or altered. 
The descending degeneration of the pyramidal tracts in the lateral columns, according to Schiff, 
occurs after section of the posterior half of the cervical spinal cord, or even after section of the 
posterior part of the lateral columns. After dividing the latter, and allowing secondary degen- 
eration to take place, it is not possible to discharge movements by stimulating the cortex cerebri. 
[Schiff divided the posterior column of the cord, and found that stimulation of the opposite 
motor cortex failed to excite movements in the opposite fore limbs. He supposed that this result 
was due to ascending degeneration. Horsley finds, however, that Schiff’s results are due to 
transverse aseptic myelitis at the seat of operation, thus causing a “block ” there in the motor 
tract.] The posterior columns, and their continuation upwards to the brain, are supposed to 
carry the impulses upwards to the cerebrum (ascending the limb of the reflex arc), where, after 
being modified in the centres, they are carried outwards by the pyramidal tracts (descending limb 
of the reflex arc). [Some hold that the posterior columns are directly connected with the cortical 
motor area, while others think that a sensory perceptive centre is interposed between the afferent 
and efferent impulses.] Between, but deeper in the brain, lie the centres for tactile sensibility. 
Landois and Eulenburg observed in a dog, from which the motor centres for the extremities had 
been removed on both sides, that the movements became completely ataxic, i.e., the animal could 
not execute such co-ordinated movements as walking, standing, etc. Goltz regards the disturb- 
ances of movement after injury of the cortex as due to inhibition. Schiff maintains that when 
the cortex cerebri is stimulated we do not stimulate a cortical centre, but only the sensory 
channels of a reflex arc, the continuation of the posterior columns, so that on this supposition the 
movements resulting from stimulation of the motor points would be reflex movements. Thf 
centres lie deeper in the brain. This view is not generally entertained. 894 
CONDITIONS MODIFYING EXCITABILITY. 
[Sec. 375. 
Modifying Conditions.—The excitability of the motor centres is capable 
of being considerably modified. [In deep ether-narcosis, stimulation of the 
motor region of the cortex does not produce contraction, but stimulation of 
the subjacent white matter does.] Stimulation of sensory nerves diminishes it; 
thus, the curve of contraction of the muscles becomes lower and longer, while 
the reaction-time is lengthened simultaneously. Only when, owing to strong 
stimulation, the reflex muscular contractions are vigorous, the excitability of the 
cortical centres appears to be increased. Specially noteworthy is the fact that, 
in a certain stage of morphia-narcosis, a stimulus which is too feeble to 
discharge a contraction becomes effective at once, if immediately before the 
stimulus is applied to the cortical centre, the skin of certain cutaneous areas be 
subjected to gentle tactile stimulation. When strong pressure is applied to the 
foot, the contractions become tonic in their nature, so that all stimuli, which 
under normal conditions produce only temporary stimulation, now stimulate 
these centres continuously. If, during the tonic contraction, during morphia- 
narcosis, one gently strokes the back of the foot, blows on the face, gently taps 
the nose, or stimulates the sciatic nerve, suddenly relaxation of the muscles 
again occurs. These phenomena call to mind the analogous observations in 
hypnotized animals (§ 374). [Sub-minimal stimuli applied to a centre fail to 
excite movement, but sometimes if the skin over the muscle corresponding to 
the area stimulated be gently stroked, contraction may take place. These 
results seem to show how complex volitional motor acts are, and that they have 
some relation to afferent impulses arising in cutaneous surfaces.] Another very 
remarkable observation is, that when either owing to a reflex effect, or to strong 
electrical stimulation of a cortical centre, contraction of the corresponding 
muscles is produced, then feeble stimulation of the same centre, but also of 
other centres, suppresses the movement. Thus, we have the remarkable fact 
that, according to the strength of the stimulus applied to the motor apparatus, 
we can either produce movement or suppress a movement already in progress 
(.Bubnoff and Heidenhain). 
[Excision of the Thyroid affects the nerve-centres. After thyroidectomy (twenty-four 
hours) the tetanus obtained by stimulating the cortex is greatly changed. It ceases when the 
stimulating current is shut off, as suddenly as that observed on stimulating the coronar adiata. 
In more advanced cases the tetanus is soon exhausted, and is often followed by clonic epileptoid 
spasms. In the latter stages, after thyroidectomy, there may be only a feeble tetanus, or none 
at all, on stimulating the motor areas, so great is the state of depression of function of these 
centres (Horsley). Actual structural changes take place in the central nervous system, and Au- 
tokratoff concludes that, in the absence of the thyroid, a poison accumulates in the organism, 
and acts specially on the nervous system.] 
[Warner has directed attention to visible muscular movements apart from those studied in 
epilepsy, chorea, athetosis—and including attitude, gait, movements of the eyeballs, position of 
the hand, and posture in general, etc.—as expressive of states of the brain and nerve-cen- 
tres.] 
[Electrical Variations accompanying cerebral action.—That an im- 
pulse is conducted along the pyramidal tracts when the motor areas are stimu- 
lated was proved by Gotch and Horsley. By means of non-polarizable elec- 
trodes applied, one to the transverse section of the cord in the lower dorsal 
region, and the other a little higher up on the longitudinal surface of the cord, 
they led off to an electrometer the current thus obtained from the cord. They 
found on stimulating the area for the hind limb in the cortex that they obtained 
a negative variation of the cord current, or, in other words, a current of 
action : but no current was obtained when other parts of the cortex were 
stimulated. If from stimulation of any area other than the leg area, epilepsy 
happened to be produced, then currents of action were noted in the lower Sec. 375.] 
SENSORY CORTICAL CENTRES. 
895 
dorsal region, and moreover the oscillations of the mercury of the electrometer 
corresponded to the type of muscular contraction, i. e., whether the contrac- 
tions were tonic or clonic. It seems evident, therefore, that when the motor 
regions of the cortex are excited, nervous impulses accompanied by “ currents 
of action ” are transmitted downwards along the pyramidal tracts.] 
[Beck and Fleischl have recently asserted that afferent impulses passing to 
the cerebral areas lead to a negative variation of the nerve-current of the 
cortex cerebri. Caton, in 1875, described electrical currents of the cortex 
cerebri.] 
376. SENSORY CORTICAL CENTRES.—[There must be some 
connection between the surface of the brain and the afferent channels through 
which sensory impulses pass inwards, and although the channels for sensory 
impulses are, perhaps, not so definitely localized as those for voluntary motion, 
still we know that sensory impulses for the opposite half of the body travel 
upwards through the posterior third of the posterior limb of the internal cap- 
sule (fig. 626, S), to radiate in all probability into the occipital and temporo- 
sphenoidal lobes. Parts of these convolutions are sometimes spoken of as 
“ sensory centres ” or “ psycho-sensorial ” areas.] 
[The same methods have been applied to the investigation of these centres, viz., stimulation 
and extirpation. Stimulation.—Ferrier found that electrical stimulation of the angular gyrus 
(monkey) caused movements of the eyeballs towards the side, with sometimes associated move- 
ments of the head, but he regarded these as reflex movements, so that for this and other reasons 
he, in his earliest contributions, considered the angular gyrus and adjacent parts as the “ centre 
for vision.” On stimulating the first temporo-sphenoidal convolution, the monkey pricked the 
opposite ear, the pupils dilated, while the head and ears turned to the opposite side; it exhibited 
movements similar to those caused by a loud sound ; these movements are also reflex phenom- 
ena, so that he located the “ auditory centre ” in this region, and on somewhat similar grounds. 
As the result of inferences from the stimulation and extirpation of other parts, he referred the 
centres for smell and taste to the tip of the temporo-sphenoidal lobe, and for touch to the hip- 
pocampus major, but all these statements have not been confirmed.] 
[Goltz experimented on dogs by washing away the cortex cerebri, and found that when a 
sufficient amount of the gray matter is removed, and after recovery from the immediate effects 
of the operation, there is a peculiar defect of vision and other sensory defects, but so far Goltz 
has not found that there is any difference in this respect between removal of the anterior and 
posterior lobes of the dog’s brain. The dog is not blind, as it can see and use its eyes to avoid 
obstacles, but it seemed as if the animal failed to recognize food or flesh as such, when placed 
before it; while exhibitions, which, before the operation, greatly excited the dog, ceased to do 
so. Goltz caused his servant to dress himself in a mummer’s red-colored garb, which previously 
had greatly excited the dog, but after the operation the dog, although it was not blind, was no 
longer excited thereby. Nor was it afterwards cowed by the appearance of a whip. After a 
time there was recovery to a certain extent if the animal was trained, whether by the deposition 
of new impressions, or by opening up new channels, or by the partial recovery of some parts of 
the gray matter not removed, it is impossible to say.] 
[Munk has mapped out the surface of the brain into a series of “ sensory ” or psycho-sensorial 
centres, but he distinguishes between complete and total extirpation of these centres and the 
phenomena which follow these operations.] 
When these centres are partially disorganized, the mechanism of the sensory 
activity may remain intact, but “ the conscious link is wanting.” A dog with 
its centres thus destroyed, sees, hears, or smells, but it no longer knows what 
it sees, hears, or smells. These centres are in a certain sense the seat of expe- 
rience that has been acquired through the organs of sense. Stimulation of 
these centres may give rise to movements, such as occur when sudden intense 
sensory impressions are produced. These movements are in no way to be 
confounded with the movements which result from direct stimulation of the 
motor cortical centres. To this group of movements belong dilatation of the 
pupil and the fissure of the eyelids, as well as lateral movements of the eye- 
ball. 896 
VISUAL CENTRES. 
[Sec. 376. 
i. “The visual area,” according to Munk, embraces the outer convex 
part of the occipital lobe of the dog’s brain. 
[This area and its connections are represented in 
fig. 613. It is, therefore, in the area supplied by 
the posterior cerebral artery. In all probability, 
however, it also embraces the mesial aspect of the 
occipital lobe, including the cuneus (fig. 607).] If 
the occipital lobes be completely destroyed, the 
dog remains permanently blind (“ cortical or ab- 
solute blindness ”). If,however, only the central 
circular area be destroyed, there is loss of the con- 
scious visual sensation, which may be called 
“psychical blindness” (Munk) [a condition 
of visual defect like that observed by Goltz in the 
dog, in which the dog saw an object, e. g., its food, 
but failed to recognize it as such. There is a cer- 
tain amount of recovery if the whole visual area be 
not removed. According to Schafer, the visual 
area of the cerebral cortex in the monkey comprises 
the whole of the occipital lobe, and perhaps a part 
of the angular gyrus. He finds, with Munk, that re- 
moval of one occipital lobe is followed by hemiano- 
pia, i. e., blindness in the lateral half of each retina 
corresponding to the side operated on. The 
blindness passes off. Removal of both occipital 
lobes is said to produce total and permanent blindness, whereas destruction of 
the cortex of both angular gyri is not followed by any appreciable permanent 
defect of vision. Ferrier, however, does not accept these statements.] 
[Ferrier and Yeo find that after operations conducted antiseptically, removal 
of both occipital lobes (monkeys) does not cause any recognizable disturbance 
of vision, or other bodily or mental derangement, provided the lesion does not 
extend beyond the parieto-occipital fissure. Nor does destruction of both 
angular gyri cause permanent loss of vision ; such loss of vision lasts only three 
days, so that in Ferrier’s original experiments the animals lived for too short a 
time after the operation to enable a just conclusion to be arrived at. Destruc- 
tion of both angular gyri and occipital lobes causes total and permanent blind- 
ness in both eyes in monkeys, without any impairment of the other senses or 
motor power. This region Ferrier calls the “ occipito-angular region.” 
[Stimulation of the angular gyrus causes movements of the eyes to the 
opposite side, with closure of the eyelids and contraction of the pupil. The 
eyeballs were directed upwards or downwards according as the electrodes were 
applied to the anterior or posterior limb of the angular gyrus (Ferrier). Stimu- 
lation of the whole of the cortex of the occipital lobe, including its mesial and 
under surfaces, causes conjugate deviation of the eyes to the opposite side, the 
direction of movement varying with the position of the electrodes.] 
Mauthner denies the existence of cortical blindness, and believes that, after destruction of 
the middle of the visual centre, the reason why the dog does not recognize the object with the 
opposite eye is because, owing to there being only indirect vision, there is no distinct impression 
on the retina. The position of the visual centre has been variously stated by different 
observers. According to Ferrier, in the dog it lies in the occipital part of the III primary con- 
volution, near the spots marked e, e, e, in fig. 609; according to his newer researches, in the 
occipital lobe and gyrus angularis. 
Connection with the Retina.—Munk asserts that in dogs both retinae are connected with 
each visual cortical centre, and in such a manner that the greatest part of each retina is connected 
with the opposite cortical centre, and only by the most external lateral marginal part with the 
Course of the psycho-optic 
fibres (after Munk). 
Fig. 613. Sec. 376.] 
VISUAL CENTRES. 
897 
centre of the same side (fig. 613). If we imagine the surface of one retina to be projected upon 
the centres, then the most external margin of the first is connected with the centre of the same 
side, the inner margin of the retina with the inner area of the opposite centre, the upper margin 
with the anterior area, and the lower marginal part of the retina with the posterior area of the 
opposite side. The (shaded) middle of the centre corresponds to the position of direct vision of 
the retina of the opposite side (compare § 344). 
Stimulation of the visual centre in the dog causes movements of the eyes 
towards the other side, sometimes with similar movements of the head and con- 
traction of the pupils. If one eye be excised from new-born dogs, the opposite 
visual centre, after several months, is less developed (.Munk). After extirpa- 
tion of the visual centre in young dogs, the channels which connect it with 
the optic nerve undergo degeneration (Monakow) (§ 344). 
In monkeys, the centre occupies the occipital lobe. Unilateral destruction causes temporary 
blindness of the halves of both retinse, i. e., hemianopia on the side of the injury. The visual 
centre in pigeons (fig. 609, IV, where 1 is placed) lies somewhat behind and internal to the 
highest curvature of the hemispheres (M'Kendrick, Ferrier, Musehold). The visual centre in 
the frog lies in the optic lobe (Blaschko). 
[The visual path is along the optic nerve to the chiasma, where the fibres 
from the nasal half of each retina cross to the optic tract, some of the fibres 
perhaps becoming connected with the external corpora geniculata, and 
some with the pulvinar of the optic thalamus and anterior corpora quad- 
rigemina, while the great mass sweeps backwards to the occipital lobes as the 
optic expansion or radiation of Gratiolet. Fibres arise in and pass from the 
optic thalamus through the internal capsule (p. 912) to the occipital lobe. 
Destruction of this path behind the chiasma causes hemiopia or hemianopia, 
and certain diseases of the occipital cortex causes a similar result. Perhaps, 
however, there is another centre in the angular gyrus (and supra-marginal 
lobe), for in cases of word-blindness disease has been found in these regions. 
Sometimes flashes of light or the appearance of a ball of fire form the aura in 
epilepsy, and Hughlings Jackson thinks that discharging lesions of the right 
occipital lobe cause colored vision more frequently than those of the left.] 
[Removal of the eyeball and section of the optic nerve result in degeneration 
of the optic tract, for if the eyeballs be removed in a young animal not only is 
there this centripetal degeneration, but the external geniculate body, the pulvi- 
nar and anterior corpora quadrigemina do not undergo complete development. 
The trophic centre for the fibres of the optic tract is in the nerve-cells of the 
retina, which, as its development shows, is really a part of the cerebral cortex 
greatly modified.] 
[It is stated that in new-born animals destruction of the temporal region 
results in imperfect development of the internal geniculate body and part of the 
posterior corpus quadrigeminum. Destruction of the internal ear leads to 
partial atrophy of the fillet. On theSe grounds it has been suggested, but not 
proved, that auditory impulses pass along the cochlear branch of the auditory 
nerve to the opposite auditory nucleus, thence into part of the fillet, from the 
latter into the posterior corpus quadrigeminum and internal geniculate body, 
and thence into the temporal region.] 
2. The centre for hearing, or “ auditory area,” lies in the dog, 
according to Ferrier, in the region of the second primary convolution at f,f,f 
{fig. 609, II), while in the monkey and man it is in the first temporal or 
temporo-sphenoidal gyrus (Ferrier’s centre, No. 14). Munk locates it in the 
same region. According to Munk, destruction of the entire region causes 
deafness of the opposite ear, while destruction of the middle shaded part alone 
causes “ psychical deafness ” (“ Seelentaubheit”). Electrical irritation of 
the upper two-thirds of the superior temporal convolution is followed by a 
reaction which closely resembles that produced by a sudden fright, or that 898 
CENTRE FOR HEARING. 
[Sec. 376. 
produced by a sudden unexpected noise. [There is a quick retraction of the 
opposite ear, i. e., “pricking ” of the ear as if toward the supposed origin of 
the sound, combined generally with turning of the head and eyes to that side, 
and dilatation of the pupil.] Ferrier locates the centre of the hearing in the 
monkey in the superior iemporo-sphenoidal convolution, and he finds that, when 
the centres on both sides are extirpated, the animal is absolutely deaf; it takes 
no cognizance of a pistol fired in its neighborhood. [From his experiments 
on monkeys, Schafer denies absolutely the conclusions of the above-named 
experiments. Schafer points out that it is not difficult to substantiate hearing 
in monkeys; it is difficult to substantiate deafness, for quite normal monkeys 
will often fail to pay the least attention to loud sounds. In six monkeys, 
Schafer asserts that after more or less complete destruction of the superior 
temporal gyrus on both sides, hearing was not perceptibly affected. In one 
case both temporal lobes were completely removed without any permanent 
diminution in the acuteness of hearing. These results are opposed to the 
ordinary clinical teaching on this subject.] In man, injuries to the first and 
second temporo-sphenoidal convolutions on one side do not appear to cause 
complete deafness of one ear, as it seems that the sense of hearing for each ear 
is perhaps represented on both sides. Bilateral lesions of these convolutions in 
man cause complete deafness. Disease of these two convolutions is associated 
with word-deafness (p. 906). Wernicke cites the case of a person first 
affected with word-deafness, who afterwards became completely deaf; and after 
death a bilateral lesion was found in the first temporo-sphenoidal convolution. 
These convolutions are supplied with blood by the middle cerebral or Sylvian 
artery. 
[The auditory paths are from the auditory nuclei in the medulla oblongata 
through the pons, where they perhaps cross into the tegmentum, thence into 
the “sensory crossway,” and onwards to the auditory centre.] 
[Auditory Aurae.—Equally important with these effects of disease are the sensory impres- 
sions, or “aurae,” which sometimes usher in an attack of epilepsy; sometimes these aurae con- 
sist of sounds or noises, and in these cases the seat of the disease is often in the first temporo- 
sphenoidal convolution.] 
[3. The olfactory centre has not been so definitely located as some of 
the others. There is strong presumptive evidence that it is situated in the 
hippocampal region of the temporal lobe, at its lower extremity. This view is 
strengthened by the anatomical relations of this region to the olfactory tract 
and anterior commissure (Ferrier). M’Lane Hamilton has recorded a case of 
epilepsy ushered in by an aura of a disagreeable odor, in which there was 
atrophy of the gray matter of the right uncinate gvrus.] 
[Olfactory Path.—Although the outer root of the olfactory tract runs direct to the uncinate 
gyrus, in hemiancesthesia resulting from injury to the “ sensory crossway,” smell is lost on the 
opposite side, while it is lost on the same side when the uncinate gyrus is involved. It may be 
that the impulses go first to their own side, and cross afterwards.] 
[4. We do not know the centre for taste, and even the course of the nerve 
of taste is disputed. Ferrier places it close to that of smell.] 
On stimulating the subiculum in monkeys, dogs, cats, and rabbits, he observed peculiar move- 
ments of the lips and partial closure of the nostrils on the same side (§ 365). In man, sub- 
jective olfactory and gustatory perceptions are regarded as irritative phenomena, while loss of 
these sensory activities, often complicated with other cerebral phenomena, is regarded as a 
symptom of their paralysis. 
[The gustatory path crosses in the posterior part of the posterior segment of the internal 
capsule. While Gowers admits that the chorda tympani is the nerve of taste for the interior two- 
thirds of the tongue, he thinks that it reaches the facial nerve from the spheno palatine ganglion 
through the Vidian nerve. He denies that the glosso-pharyngeal is concerned in taste, and “ he Sec. 376.] 
TACTILE CENTRE. 
899 
believes that taste impressions reach the brain solely by the roots of the 5th nerve.” He 
admits that the nerves of taste to the back part of the tongue may be distributed with the glosso- 
pharyngeal, reaching them through the otic ganglion by the small superficial petrosal and tympanic 
plexus.] 
[5. Ferrier places the centre for tactile sensation in the hippocampal 
region, close to the distribution of part of the posterior cerebral artery; so far 
this has not been confirmed. The centre for the sensation of pain has not 
been defined; probably it is very diffuse. The limbic lobe, according to 
Broca, includes the hippocampal convolution and the gyrus fornicatus. 
Ferrier found that removal of the hippocampal region resulted in a diminution 
of the sensibility of the opposite side of the body. Horsley and Schafer ob- 
served only a temporary hemiansesthesia, but they found that an extensive lesion 
of the gyrus fornicatus was followed by hemianaesthesia, more or less marked 
and persistent, so that cutaneous sensibility has been referred to this con- 
volution (fig. 607). From their experiments these observers conclude that the 
limbic lobe “ is largely if not exclusively, concerned in the appreciation of 
sensations, painful and tactile.”] 
6. Munk is of opinion that the surface of the cerebrum in the region of the motor centres 
acts at the same time as “ sensory areas ” (“Fuhlsphare ”), i. e., they serve as centres for the 
tactile and nmscular sensations and those of the innervation of the opposite side. He asserts 
that after injury to these regions the corresponding functions are affected. 
According to Bechterew, the centres for the perception of tactile impressions, those of inner- 
vation, of the muscular sense, and painful impressions are placed in the neighborhood of the 
motor areas (dog); the first immediately behind and external to the motor areas, the others in 
the region close to the origin of the Sylvian fissure. (See also p. 910.) 
Goltz, who first accurately described the disturbances of vision following upon injuries to the 
cortex in dogs, is opposed to the view of sensory localization. He believes that each eye is con- 
nected with both hemispheres. He asserts that the disturbance of vision, after injury to the brain, 
consists merely in a diminished color- and space-sense. The recovery of the visual perception 
of one eye after injury of one side of the cortex cerebri, he explains by supposing that this injury 
merely causes a temporary inhibition of the visual activity in the opposite eye, which disappears 
at a later period. Instead of psychical blindness and deafness he speaks of a “ cerebro optical ” 
and “ cerebro-acoustical weakness.” 
377. THERMAL CORTICAL CENTRES.—Eulenburg and Landois discovered an 
areal on the cortex cerebri, whose stimulation produced an undoubted effect upon the tempera- 
ture and condition of the blood-vessels of the opposite extremities. This region (fig. 609, I, t) 
generally embraces the area in which, at the same time, the motor centres for the flexors and 
rotators of the fore limb (3), and for the muscles of the hind limb (4) are placed. The areas for 
the anterior and posterior limbs are placed apart, that for the anterior limb lies somewhat more 
anteriorly, close to the lateral end of the crucial sulcus. Destruction of this region causes in- 
crease of the temperature of the opposite extremities; the temperature may vary considerably 
(1.50 to 2°, and even rising to 130 C.). This result has been confirmed by Hitzig, Bechterew, 
Wood, and others. This rise of the temperature is usually present for a considerable time after 
the injury, although it may undergo variations. Sometimes it may last three months, in other 
cases it gradually reaches the normal in two or three days. In well-marked cases there is a 
diminution of the resistance of the wall of the femoral artery to pressure, and the pulse-curve is 
not so high (Reinke). Local electrical stimulation of the area causes a slight temporary cool- 
ing of the opposite extremities, which may be detected by the thermo electric method. Stimula- 
tion by means of common salt acts in the same way, but in this case the phenomena of destruc- 
tion of the centre soon appear. As yet, it has not been proved that there is a similar area for 
each half of the head. The cerebro-epileptic attacks (£ 375) increase the bodily temperature, partly 
owing to the increased production of heat by the muscles ($ 302), partly owing to diminished 
radiation of heat through the cutaneous vessels, in consequence of stimulation of the thermal 
cortical nerves. The experiments led to no definite results when performed on rabbits. Accord- 
ing to Wood, destruction of these centres occasions an increased production of heat that can be 
measured by calorimetric methods, while stimulation causes the opposite result. 
These experiments explain how psychical stimulation of the cerebrum may have an effect upon 
the diameter of the blood-vessels and on the temperature, as evidenced by sudden paleness and 
congestion (§ 378, III). 
[Heat Production.—Injury to the fore-brain has no effect on the tempera- 900 
THERMAL CENTRES. 
[Sec. 377. 
ture. If the brain of a rabbit be punctured through the large fontanelle, and 
the stylet be forced through the gray matter on the surface, white matter, and 
the median portion of the corpus striatum right to the base of the brain, there 
is a rapid rise of the temperature, which may last several days. Injury to the 
gray cortex does not affect the temperature. After puncture of the corpus 
striatum, the highest temperature is reached only after twenty-four to seventy 
hours, but when the puncture reaches the base of the brain this result occurs in 
two to four hours. Electrical stimulation of these areas causes the same effect 
on the temperature. Direct injury to certain parts of the brain is followed by 
a rise of the temperature—or fever. See also p. 416 for further evidence of the 
existence of thermal centres. There is at the same time an increase of the O 
taken in, the C02 given off, and a decided increase of the N given off, indicating 
an increase in the proteid metabolism, which points to an increased production 
of heat (Aronsohn and Sachs, Richet, Wood ).] 
General and Theoretical.—Goltz’s View.—Goltz uses a different method to remove the 
cortex cerebri—he makes an opening in the skull of a dog, and by means of a stream of water 
washes away the desired amount of brain-matter. He describes, first of all, inhibitory pheno- 
mena, which are temporary and due to a temporary suppression of the activity of the nervous 
apparatus, which, however, is not injured anatomically; this may be explained in the same way 
as the suppression of reflexes by strong stimulation of sensory nerves ($ 361, 3). In addition, 
there are the permanent phenomena, due to the disappearance of the activity of the nervous 
apparatus, which is removed by the operation. A dog, with a large mass of its cerebral cortex 
removed, may be compared to an eating, complex, reflex machine. It behaves like an intensely 
stupid dog, walks slowly, with its head hanging down ; its cutaneous sensibility is diminished in 
all its qualities—it is less sensitive to pressure on the skin; it takes less cognizance of variations 
of temperature, and does not comprehend how to feel; it can with difficulty accommodate itself 
to the outer world, especially with regard to seeking out and taking its food. On the other hand, 
there is no paralysis of its muscles. The dog still sees, but it does not understand what it does 
see; it looks like a somnambulist, who avoids obstacles without obtaining a clear perception of 
their nature. It hears, as it can be wakened from sleep by a call, but it hears like a person just 
wakened from a deep sleep by a voice—such a person does not at once obtain a distinct percep- 
tion of the sound. The same is the case with the other senses. It howls from hunger, and eats 
until its stomach is filled ; it manifests no symptoms of sexual excitement. 
Goltz supposes that every part of the brain is concerned in the functions of willing, feeling, 
perception, and thinking. Every section is, independently of the others, connected by conducting 
paths with all the voluntary muscles, and, on the other hand, with all the sensory nerves of the 
body. He regards it as possible that the individual lobes have different functions. 
After removal of the anterior or frontal convolutions and the motor areas, there is at first 
unilateral motor and sensory paralysis and affection of vision. After some months, there remains 
only the loss of the muscular sense. If the operation be bilateral, the phenomena are more marked; 
there are innumerable purposeless associated movements, and the dogs become vicious. Marked 
and permanent disturbance in the capacity to utilize the impressions from the sense-organs is not 
a necessary consequence of removal of the frontal convolutions. 
Removal of the occipital lobes interferes most with vision. Bilateral removal makes the 
animal almost blind. The dog remains obedient and lively. There is no disturbance of motion 
or of the muscular sense. 
Inhibitory Phenomena.—Injury to the brain also causes inhibitory phenomena, such as the 
disturbances of motion, the complete- hemiplegia which is frequently observed after large uni- 
lateral injuries of the cortex cerebri; these are regarded by Goltz as inhibitory phenomena, due 
to the injury acting on lower infra-cortical centres, whose action inhibits movement, but these 
movements are recovered as soon as the inhibitory action ceases. 
Other Effects of Cortical Stimulation.—Some observers noticed variations of the blood- 
pressure and a change in the number of heart-beats after stimulation of the cortex cerebri, e.g., 
after electrical stimulation of the motor areas for the extremities (Bochefontaine). Balogh 
observed acceleration of the pulse, on stimulating several points on the cortex cerebri of a dog, 
and from one point slowing of the pulse. Eckhard stimulated the surface of the brain in rabbits, 
and, as a rule, he observed that, as long as single crossed movements occurred in the anterior 
extremities, there was no effect upon the heart, but that the heart became affected as soon as 
other movements occurred. This consists in slow, strong pulse-beats, with occasional weaker 
beats, while at the same time the blood pressure is slightly increased (.Bochefontaine). If the 
vagi be divided beforehand, the effect upon the pulse disappears, while the increase of the blood- 
pressure remains. That psychical processes affect the action of the heart was known to Homer Sec. 377.] 
MOTOR AREAS. 
901 
and Chrysipp. Bochefontaine and Lepine, on stimulating several points, especially in the neigh- 
borhood of the sulcus cruciatus in the dog, observed increased secretion of saliva, slowing of 
the movements of the stomach, peristalsis of the intestine, contraction of the spleen, of the 
uterus, of the bladder, and increased respirations. Bufalini, on stimulating those parts of the 
cortex which cause movements of the jaw, observed secretion of gastric juice with increase of the 
temperature of the stomach. Schiff, Brown-Sequard, Ebstein, Klosterhalfen, and others have 
observed that injury to the pons, corpus striatum, thalamus, cerebral peduncle, and medulla 
oblongata often causes hyperaemia and hemorrhage into the lung (according to Brown-Sequard, 
especially after injury to one side of the pons, which affects the opposite lung), under the pleura, 
in the stomach, intestine, and kidneys. Gastric hemorrhage is common after injury to the pons 
just where the cerebral peduncles join it. Similar phenomena have been observed in man after 
apoplexy or cerebral hemorrhage. 
378. TOPOGRAPHY OF THE CORTEX CEREBRI.—A short 
resume of the arrangement of convolutions, according to Ecker, is given in 
§ 375- 
I. The cortical motor areas for the face and the limbs are grouped around 
Fig. 614.—Motor areas in man, shaded—outer surface of the left side of human brain. Dotted 
area, the aphasic region (modified from Gowers). Fig. 615.—Inner surface of right hemi- 
sphere. A. S., area governing the movements of the arm and shoulder; Tr, of the trunk; 
leg, those of the leg; Gf, gyrus fornicatus; CC, corpus callosum; U, uncinate gyrus; O, 
occipital lobe. 
Fig. 614. 
Fig. 615. 
the fissure of Rolando, including the ascending frontal, ascending parietal, and 
part of the parietal lobule on the outer convex surface of the cerebrum (fig. 
614). The centre for the face occupies the lowest third of the ascending 
frontal convolution, and reaches also to the lowest fifth of the ascending 
parietal. The arm centre occupies the middle third of the ascending frontal 
and middle three-fifths of the ascending parietal convolutions, while the leg 
centre lies at the upper end of the sulcus and extends backwards into the parietal 
lobule (and perhaps on to the superior frontal convolution) (fig. 614). The leg 
centre is continued over on to the paracentral lobule, opposite the upper end 
of the fissure of Rolando, in the marginal convolution on the mesial aspect of 
the hemisphere (fig. 616), where the centres for the muscles of the trunk also 
exist (p. 890). The centre for speech is in the posterior part of the third left 
frontal convolution (fig. 614). 
Blood Supply.—These convolutions are supplied with blood from 4 to 5 branches of the 
Sylvian artery, which may sometimes be plugged with an embolon. When a clot lodges in 
this artery, the branches to the basal ganglia may remain pervious, whilst the cortical branches 
may be plugged (Duret, Heubner') (§ 381). 
[Hemiplegia consists of motor paralysis of one-half of the body, although, 
as a rule, all the muscles are not paralyzed to the same extent; sometimes there 902 
HEMIPLEGIA. 
[Sec. 378. 
may be complete paralysis, i. e., they are entirely removed from voluntary con- 
trol, while in others there'is merely impaired voluntary control. It may be 
caused by affections of the cor- 
tical areas or by lesion of the 
motor tracts above the medulla, 
and the paralysis is always on 
the side opposite to the lesion, 
owing to the decussation of the 
motor paths in the medulla. If 
the case be a severe one, we 
have what Charcot terms hemi- 
plegie centrale vulgaire, or 
“complete hemiplegia,” due to 
Fig. 616.—Transverse section of a cerebral hemisphere. CCa, corpus callosum; NC, caudate 
nucleus ; NL, lenticular nucleus; IC, internal capsule; CA, internal carotid artery; aSL, 
lenticulo striate artery; (“ Artery of hemorrhage ”); F, A, L, T, position of motor areas 
governing the movements of the face, arm, leg, and trunk muscles of the opposite side 
{Horsley). Fig. 617.—Scheme of the innervation of bilaterally associated muscles {Ross). 
Fig. 616. 
Fig. 617. 
lesion of the cortical centres for the face, arm, and leg. While the arm and 
leg are completely paralyzed, the lower part of the face is more affected than 
the upper half, which is usually not much affected. All those movements under 
voluntary control, and especially those that have been learned, are abolished, 
whilst the associated and bilateral movements, which even animals can execute 
immediately after birth, remain more or less unaffected. Hence, the hand is more 
paralyzed than the arm ; this, again, than the leg; the lower facial branches 
more than the upper; the nerves of the trunk scarcely at all (Ferrier). When 
an extraordinary effort is made, it will be found that there is some impairment 
of the power of the muscles of mastication and respiration, although the mus- 
cles on opposite sides act together (Gowers). The trunk-muscles, as a rule, are 
but slightly affected, or not at all, as their centre is elsewhere. There may be 
alterations of sensibility and of the reflexes.] 
[Conduction through the whole of the pyramidal fibres coming from one hemisphere may be 
interrupted, and yet all the muscles on the opposite side of the body are not paralyzed. The 
muscles which are comparatively unaffected are those associated in their action with the muscles 
of the opposite side, e.g., the respiratory muscles. Broadbent assumes that such muscles have 
a bilateral representation in the motor areas. Suppose in fig. 617, B, B/, to represent the cere- 
bral cortex; M, M, motor centres in it; N, N', nerve nuclei in the spinal cord or medulla ob- 
longata; P, P/, the pyramidal tracts passing to spinal nuclei N, N/ ; m, mnerves proceeding 
from the last. I, 2, 3,4, 5, represent different lesions. In the case of muscles on opposite sides 
of the body, which act independently, e.g., those of the hand, this is all the mechanism, but in Sec. 378.] 
RESULTS OF HEMIPLEGIA. 
903 
bilaterally associated muscles there is another mechanism, viz., commissural fibres between the 
nerve nuclei, the one c conducting from right to left, and c' from left to right. When there is 
an injury at X or 3, impulses can still pass from the uninjured side M to N' and through cf to 
the muscles m, m'. In this way both muscles receive motor impulses from one hemisphere 
(.AW).] 
Conjugate deviation of the eyes, with rotation of the head, is frequently present in the 
early period of hemiplegia, although it usually disappears. When a person turns his head to 
one side, there is an associated movement of certain of the ocular muscles with those of the 
neck. The head and eyes ate usually turned to the side of the lesion; this is termed “ conju- 
gate deviation,” so that the power of voluntarily moving the eyes and head to the paralyzed 
side is temporarily lost. The unopposed muscles rotate the head and eyes to the sound side. 
If the lesion be in the posterior part of the pons, the deviation is to the paralyzed side (Prevost). 
[Such movements have been obtained by stimulating the angular gyrus, and the posterior 
extremity of the middle frontal convolution.] 
[Subsequent Effects.—If there be a hemorrhage, say into these motor regions, or from the 
lenticulo-striate artery, so as to compress the pyramidal fibres in the knee and anterior two- 
thirds of the posterior segment of the internal capsule, then there is usually tonic or persistent 
contraction of the muscles affected. These tonic spasms may accompany the hemorrhage, or 
come on a few days after it, and set up the condition of early rigidity. The contraction or 
spasm—if any—accompanying the hemorrhage, is due to direct irritation of the pyramidal 
fibres, while that which comes on a few days later, and usually lasts a few weeks, is also due 
to irritation of these fibres, probably produced by inflammatory action in and around the seat 
of the lesion. The affected limb is stiff and resists passive movement. After a few weeks, late 
rigidity sets in and is persistent, and it is characterized by structural changes in the pyramidal 
paths which lead to other results. There is secondary descending degeneration in the 
pyramidal tracts, which causes “ contracture ” in the paralyzed limbs, while at the same time 
the deep or tendinous and periosteal reflexes (ankle-clonus, rectus-clonus, and the deep reflexes 
of the arm-tendons) are exaggerated. The spastic rigidity is usually more marked in the arm 
than in the leg, and it generally affects the flexors more than the extensors, so that the upper 
arm is drawn close to the trunk, the elbow, arm, and fingers flexed; in the leg, the extensors 
of the leg overcome the peronei. Hitzig has pointed out that the contracture is less during 
sleep and after rest. The muscles at first can be stretched by sustained pressure, but after 
months or years structural changes occur in the muscles, ligaments, and tendons, and the limbs 
assume a permanent and characteristic attitude.] 
In hemiplegic persons the power of the unparalyzed side is sometimes diminished, which is 
not sufficiently explained by the fact that some bundles of the pyramidal tracts remain on the 
same side (Brown-Sequard, Charcof). 
[Acquired Movements.—Some movements performed by man are learned only after much 
practice, and are only completely brought under the influence of the will after a time, such as 
the movements of the hand in learning a trade. Such movements are reacquired only very 
slowly, or not at all, after injury to the motor areas in which they are represented. Those 
movements, however, which the body performs without previous training, such as the associated 
movements of the eyeballs, the face, and some of those of the legs, are rapidly recovered after 
such an injury, or they suffer but little, if at all. Thus, the facial muscles seem never to be so 
completely paralyzed after a lesion of the facial cortical centre, as in affections of the trunk of 
the facial nerve; the eye especially can be closed. Sucking movements have been observed in 
hemicephalous foetuses.] 
Degeneration of the Pyramidal Tracts.—After destruction of the corti- 
cal motor areas, descending degeneration of the cortico-motor paths, or “pyra- 
midal tracts," takes place (§ 365). Degenerative changes have been found to 
occur within the white matter under the cortex in the anterior two-thirds of 
the posterior segment of the internal capsule [in the middle third of the 
crusta (figs. 618, *, 619, L)], pons, in the interior pyramids of the medulla 
oblongata (fig. 618), and thence they have been traced into the pyramidal 
paths (direct and crossed) of the spinal cord (Charcot, Singer). It is evident 
that lesions of these tracts at any part of their course must have the same result, 
viz., to produce hemiplegia. (For the subsequent effects, see p. 803). In a 
case of congenital absence of the left forearm, Edinger found that the right 
central convolutions were less developed. 
[The descending degeneration in the pyramidal tracts shows that their 
trophic centre lies in the cells of the motor part of the cortex. The course 
of the fibres from the motor areas and their relative position in the internal PYRAMIDAL TRACTS. 
[Sec. 378. 
capsule may be traced by the course of the descending degeneration following 
upon removal of a particular cortical motor area. France has shown that 
removal either of the marginal or fornicate gyrus is followed by descending 
degeneration of the opposite crossed pyramidal tract traceable to the lower 
lumbar region.] 
It is doubtful if the muscular sense is represented in the motor areas; Nothnagel supposes 
it to be located in the temporal parietal lobes. It is to be noted, however, that in man there may 
be general loss of the muscular sense or of motor representations, and, on the other hand, a pure 
motor paralysis without loss of the former. 
Ataxic motor conditions, similar to those that occur in animals (p. 776), take place in man, 
and are known as cerebral ataxia. 
The position of the centres is given at p. 887. 
[But we may have localized lesions affecting one or more of the cortical 
motor areas; these are called monoplegiae. Cases in man are now suffi- 
ciently numerous to permit of accurate diagnosis.] Crural monoplegia 
[rare lesions recorded in the convolutions at the upper end of the fissure of 
Fig. 618.—Secondary descending degeneration in middle third of right crus and medulla, after 
destruction of the cortical motor centres on the right side. Fig. 619.—Horizontal section 
of the cerebral peduncle in secondary degeneration of the pyramidal tracts, where the lesion 
was limited to the middle third of the posterior segment of the internal capsule. F, healthy 
crusta; L, locus niger; P, internal third of the crusta on the diseased side; D, secondary 
degeneration in the middle third of the crusta; CQ, corpora quadrigemina with the iter 
below them. 
Fig. 618. 
Fig. 619. 
Rolando, and the continuation of this area on to the paracentral lobule of the 
marginal convolution], brachio-crural, more common, in the upper and 
middle thirds of the ascending frontal and ascending parietal convolutions— 
brachial, brachio-facial—facial, the last in the lowest part of the central 
convolutions. 
Paralysis of the muscles of the neck and throat indicates a lesion of the central convolutions, 
and so does paralysis of the muscles of the eye. Lesions of the cortex always cause simultaneous 
movements of the head and eyeballs. 
Irritation of the Motor Centres.—If the motor centres are irritated by 
pathological processes, such as hypenemia, or inflammation in a syphilitic Sec. 378.] 
SPEECH CENTRE. 
905 
diathesis—more rarely by tumors, tubercle, cysts, cicatrices, fragments of bone 
—there arise spasmodic movements in the corresponding muscle-groups. This 
condition of a sudden discharge of the gray matter resulting in local spasms is 
called “Jacksonian, or cerebral epilepsy.” 
[Convulsions and spasms may be discharged from motor cortical lesions, and 
these, whether they affect the general or localized areas, give rise to unilateral 
convolutions and monospasm respectively.] 
Monospasm.—According to the seat of the spasm, it is called facial, brachial, crural mono- 
spasm, etc. Of course these spasms may affect several, groups of muscles. Bartholow and 
Sciamanna have stimulated the exposed human brain successfully with electricity. 
Cerebral Epilepsy.—Very powerful stimulation of one side may give rise 
to bilateral spasms, with loss of consciousness. In this case, impulses are con- 
ducted to the other hemisphere by commissural fibres (§ 379). [It is most 
readily produced in animals lower in the scale than monkeys (p. 887).] 
Movements of the Eyeball.—Nothing definite is known regarding the centre in the cortex 
for voluntary combined movements of the eyeballs in man. In paralytic affections of the cortex 
and of the paths proceeding from it, we occasionally find both eyes with a lateral deviation. If 
the paralytic affection lies in one cerebral hemisphere, the conjugate deviation of the eyeballs 
is toward the sound side ($ 345). If it is situated in the conducting paths, after these have 
decussated, viz., in the pons, the eyes are turned towards the paralyzed side (Prevost). 
If the part be irritated so as to produce spasms in the opposite half of the body, of course the 
eyes are turned in the direction opposite to that in pure paralysis. Instead of the lateral devia- 
tion of the eyeballs already described, there is occasionally in cerebral paralysis merely a weaken- 
ing of the lateral recti muscles, so that during rest the eyes are not yet turned towards the sound 
side, but they cannot be turned strongly towards the affected side (Leichtenstern, Hunnius). 
The centre for the levator palpebrse superioris appears to be placed in the angular gyrus (Grasset, 
Landouzy). 
II. The Centre for Speech.—The investigations of Bouilland [1825], 
Dax [1836], Broca [1861], Kussmaul, Broadbent, and others have shown that 
the third left frontal convolution of the cerebrum (figs. 610, F3, and 614) 
is of essential importance for speech, while probably the island of Reil also is 
concerned. The island is deeply placed, and is seen on lifting up the over- 
hanging part of the brain called the operculum, lying between the two branches 
of the Sylvian fissure (S). The motor centres for the organs of speech (lips, 
tongue) lie in this region, and here also the psychical processes in the act of 
speech are completed. In the great majority of mankind, the centre for 
speech is located in the left hemisphere. The fact that most men are right- 
handed also points to a finer construction of the motor apparatus for the upper 
extremity, which must also be located in the left hemisphere. Men, therefore, 
with pronounced right-handedness (“droitors”) are evidently left-brained 
(“ gauchers du cerveau”—Broca). By far the greater number of mankind 
are “ left-brained speakers ” (Kussmaul) ; still there are exceptions. As a 
matter of fact, cases have been observed of left-handed persons who lost their 
power of speech after a lesion of the right hemisphere (Ogle). Investigations 
on the brains of remarkable men have shown that in them the third frontal 
convolution is more extensive and more complex than in men of a lower mental 
calibre. In deaf-mutes it is very simple; microcephales and monkeys possess 
only a rudimentary third frontal (Riidinger). 
The motor tract for speech passes along the upper edge of the island of 
Reil, then into the substance of the hemisphere internal to the posterior edge 
of the knee of the internal capsule ; from thence through the crusta of the left 
cerebral peduncle into the left half of the pons, where it crosses, then into 
the medulla oblongata, which is the place where all the motor nerves (trige- 
minus, facial, hypoglossal, vagus, and the respiratory nerves) concerned in 
speech arise. Total destruction of these paths, therefore, causes total aphasia; 906 
APHASIA. 
[Sec. 378. 
while partial destruction causes a greater or less disturbance of the mechanism 
of articulation, which has been called “ anarthria " by Leyden and Wer- 
nicke. 
Conditions for Speech.—Three activities are required for speech—(i) 
the normal movement of the vocal apparatus (tongue, lips, mouth, and respira- 
tory apparatus) ; (2) a knowledge of the signs for objects and ideas (oral, writ- 
ten and imitative or mimetic signs) ; (3) the correct union of both. 
Aphasia (a priv. and <pd<n$ speech).—Injury of the speech-centre causes 
either a loss or more or less considerable disturbance of the power of speech. 
The loss of the power of speech is called “aphasia." [Aphasia, as usually 
understood, means the partial or complete loss of the power of articulate speech 
from cerebral causes. The person is speechless, but not necessarily absolutely 
wordless.] 
The following forms of aphasia may be distinguished: — 
1. Ataxic aphasia (or the oro lingual hemiparesis of Ferrier), i.e., the loss of speech owing 
to inabdity to execute the various movements of the mouth necessary for speech. Whenever 
such a person attempts to speak, he merely executes inco-ordinated grimaces and utters inarticu- 
late sounds. [The muscles concerned in articulation, however, are not paralyzed, but there is 
an absence of co-ordination of these muscles due to disease of the cortical centre.] Hence, the 
patient cannot repeat what is said to him. Nevertheless, the psychical processes necessary for 
speech are completely retained, and all words are remembered; and hence, these persons can 
still give expression to their thoughts graphically or by writing. If, however, the finely adjusted 
movements necessary for writing are lost, owing to an affection of the centre for the hand, then 
there arises at the same time the condition of agraphia, or inability to execute those movements 
necessary for writing. Such a person, when he desires to express his ideas in writing, only suc- 
ceeds in making a few unintelligible scrawls on the paper. Occasionally such patients suffer 
from loss of the power of imitation or the execution of particular movements of the limbs and 
body constituting pantomime speech or amimia (Kussmaul). 
2. Amnesic Aphasia or Loss of the Memory of Words.—Should the patient, however, hear 
the word, its significance recurs to him. The movements necessary for speech remain intact; 
hence, such a patient can at once repeat or write down what is said to him. Sometimes only 
certain kinds of words are forgotten, or it may be only parts of certain words, so that only part 
of these words is spoken. [Nouns and proper names usually go first.] Cases of amnesic aphasia, 
or the mixed ataxic-amnesic form of disturbance of speech, point to a lesion of the third frontal 
convolution and of the island of Reil on the left side. Another form of amnesic aphasia con- 
sists in this, that the words remain in one’s memory but do not come when they are wanted, i. e., 
the association between the idea and the proper word to give expression to it is inhibited (Kuss- 
maul). It is common for old people to forget the names of persons or proper names; indeed, 
such a phenomenon is common within physiological limits, and it may ultimately pass into the 
pathological condition of amnesia senilis. Amongst the disturbances of speech of cerebral 
origin, Kussmaul reckons the following :— 
3. Paraphasia, or the inability to connect rightly the ideas with the proper words to express 
these ideas, so that, instead of giving expression to the proper ideas, the sense may be inverted, 
or the form of words may be unintelligible. It is as if the person were continually making a 
“ slip of the tongue.” 
4. Agrammatism and ataxaphasia, or the inability to form the words grammatically and 
to arrange them synthetically into sentences. Besides these, there is— 
5. A pathological slow way of speaking (bradyphasia), or a pathological and stuttering way 
of reading (tumultus sermonis), both conditions being due to derangement of the cortex 
(Kussmaul). The disturbances of speech depending essentially upon affections of the peripheral 
nerves, Or of the muscles of the organs of the voice and speech, are already referred to in \\ 319, 
349 and 354- 
[In word-blindness, the person cannot name a letter or a word, so that he 
cannot understand symbols, such as printed or written words, or it may be any 
familiar object, although he can see quite well, while he can speak fluently and 
write correctly.] 
[In word-deafness, the person hears other sounds and is not deaf, but he 
does not hear words.] 
[The study of aphasia in its various forms is simplified by a study of the mode of acquisition 
of language by a child. The child hears spoken words and obtains auditory memories of Sec. 378.] 
APHASIA. 
907 
impressions of these sounds (called by Lichtheim “auditory word-representations”), and 
this must form the starting-point of language, and by and by it begins to co-ordinate its muscles 
to produce sounds imitative of these. Thus we have two centres, one for “ auditory images” 
(fig. 620, A), and the other for “ motor images” (fig. 620, M), and these two must be con- 
nected, thus establishing a reflex arc. There is a receptive and an emissive department as repre- 
sented in the scheme. We must assume the existence of a higher centre (B), “in which concepts 
are elaborated,” where these sounds become intelligible. Volitional language requires a con- 
nection between B and M, as well as between A and M. But we have also reading and writing. 
Suppose O to represent a 
centre for visual impres- 
sions (printed words or 
writing); these we can 
understand through the 
connection between such 
visual impressions and 
auditory impressions, 
whereby a path is estab- 
lished through OA (fig. 
621). In reading aloud, 
however, the orolingual 
muscles must be co-ordi- 
nated, so we have the 
path OAM opened up. 
In writing, or copying 
written characters, the 
movements of the hand 
are special, and perhaps 
require a special centre, 
or at least a special arrangement of the channels for impulses in the centre; the movements are 
learned under the guidance of ocular impressions, so we connect O and E, E being the centre 
guiding the movements in writing. As to volitional writing, the impulse passes through M—but 
does it pass directly to E, err indirectly through A ? Lichtheim assumes that it goes direct 
from M to E. It is evident that there are seven channels which may be interrupted, each one 
giving rise to a different form of aphasia (1 to 7).] 
[Looked at from another point of view, either the ingoing (a) or outgoing (m) channels or 
centres, or the commissural fibres between both, may be affected. If the motor centre is 
affected, we have Wernicke’s “ motor aphasia ”; if the sensory, his “ sensory aphasia.”] 
[In the most common form, or ataxic aphasia (.Kussmaul), which was that described by 
Broca, or the “ motor aphasia” of Wernicke, the lesion is in fig. 620, in M, i. e., in the motor, 
or what Ross calls the emissive department. In such a case, it is obvious that there will be 
loss of (1) volitional speech, (2) repetition of words, (3) reading aloud, (4) volitional writing, 
and (5) writing to dictation; while there will exist (0) understanding of spoken words, (6) also 
of written words, (r) and the faculty of copying. If the lesion be in A, we have the “ sensory 
aphasia ” of Wernicke, i. e., in the acoustic word-centre; we find loss of (1) understanding 
of spoken language, (2) also of written language, (3) faculty of repeating words, (4) and of 
writing to dictation, (5) and of reading aloud ; there will exist (a) the faculty of writing, (3) of 
copying words, and (*r) of volitional speech, but the volitional speech is imperfect, the wrong 
word being often used, so that there is the condition of “ paraphasia.” If the connection 
between A and M be destroyed, other results will follow, and such cases of “ commissural ” 
aphasia have been described by Wernicke. If the interruption be between B and M, we have 
a not uncommon variety of motor aphasia (4), where there is loss of (1) volitional speech, and 
(2) volitional writing, and there exist (#) understanding of spoken language, (£) of written 
language, (c) and the faculty of copying; but it differs from Broca’s aphasia in that there also 
exists the faculty (d) of repeating words, (e) of writing to dictation, (/) and of reading aloud. 
If the lesion is in Mm (5), the symptoms will be those of Broca’s aphasia, but there will exist 
(1) the faculty of volitional writing, and (2) of writing to dictation. Many examples of this 
occur where patients have lost the faculty of speaking, but can express their thoughts in writing. 
In lesions of the path AB (6), there will be loss of (1) understanding of spoken language, and 
(2) of written language, and there will exist (a) volitional speech (but it willbeparaphasic), (b) 
volitional writing (but it will have the characters of paragraphia), (r) the faculty of repeating 
words, (d) reading aloud, (e) writing to dictation, and (f) power of copying words. The per- 
son will be quite unable to understand what he repeats, reads aloud, or copies.] 
[Fig. 622 shows diagrammatically the conditions in motor and sensory aphasia. From the 
eye and ear centripetal fibres (v and a) ascend to terminate in the visual (V) and auditory cen- 
tres (A), in the cortex, while afferent fibres (s, s', s//), indicated by dotted lines, also pass from 
Fig. 620. 
Fig. 621. 
Figs. 620, 621.—Schemes of aphasia. A, centre for auditory images; 
M, for motor images; B, perception centre; Oc, eye; E, reading 
centre; 1 to 7, lesions (Lichtheim). 908 
VISUAL CENTRE. 
[Sec. 378. 
the articulators, muscles of the hand, and orbit to the cerebrum. The dotted lines on the 
surface of the cortex represent the association system of fibres which connects the centres with 
each other. The centres for vocal (V) and written expression (W) are connected by centrifugal 
fibres, m and m/, with the hand and larynx respectively (.AW).] 
III. The thermal centre for the' extremities is associated with the 
motor areas (§ 377). Injury or degeneration of these areas causes inequality 
of the temperature on both sides (.Bechterew). 
IV. The sensory regions are those areas in which conscious percep- 
tions of the sensory impressions are accomplished. Perhaps they are the sub- 
stratum of sensory perceptions, and of the memory of sensory impressions. 
1. The visual centre, according to Munk, includes the occipital lobes 
(fig. 610, O1, O2, O3), while, according 
to Ferrier, it also includes the angular 
gyrus. Huguenin observed, in a case of 
long-standing blindness, consecutive dim- 
inution of the occipital convolutions on 
both sides of the parieto-occipital fissure, 
while Giovanardi, in a case of congenital 
absence of the eyes, observed atrophy of 
the occipital lobes, which were separated 
by a deep furrow from the rest of the 
brain. Stimulation of the centre gives 
rise to the phenomena of light and color. 
Injury causes disturbance of vision, es- 
pecially hemiopia of the same side (§ 344 
— Westphal). When one centre is the 
seat of irritation} there is photopsia of 
the same halves of both eyes (Charcot). 
Stimulation of both centres causes the oc- 
currence of the phenomena of light or 
color, or visual hallucinations in the en- 
tire field of vision. Cases of injury to 
the brain, where the sensations of light 
and space are quite intact, and where the 
color sense alone is abolished, seem to 
indicate that the color sense centre must 
be specially localized in the visual centre 
(Samelsohn). After injury of certain 
parts, especially of the lower parietal 
lobe, “psychical blindness" may occur. 
A special form of this condition is known 
as “ word-blindness ” or alexia (Coecitas verbalis), which consists in this 
that the patient is no longer able to recognize ordinarily written or printed 
characters (p. 906). 
Charcot records an interesting case of psychical blindness. After a violent paroxysm of rage, 
an intelligent man suddenly lost the memory of visual impressions; all objects (persons, streets, 
houses) which were well known to him appeared to be quite strange, so that he did not even rec- 
ognize himself in a mirror. Visual perceptions were entirely absent from his dreams. 
Clinical observations on hemianopia ($ 344) show that the field of vision of each eye is 
divided into a larger outer and a smaller inner portion, separated from each other by a vertical 
line passing through the macula lutea. Each right or left half of both visual fields is related 
to one hemisphere ; both left halves are projected upon the left occipital lobes, and both right 
upon the right occipital lobes (fig. 613). Thus, in binocular vision, every picture (when not too 
small) must be seen in two halves; the left half by the left, the right half by the right hemi- 
sphere (Wernicke'). 
As a result of pathological stimulation of the visual centre, especially in the insane, visual 
Scheme to illustrate aphasia. 
Fig. 622. Sec. 378.] 
CEREBRAL CENTRES. 
909 
spectres may be produced. Pick observed a case where the hallucinations were confined to the 
right eye. Celebrated examples of ocular spectra occurred in Cardanus, Swedenborg, Nicolais, 
J. Kerner, and Holderlin. 
After degeneration of the cortical centre the fibres which connect the occipital lobes with the 
external geniculate body, the anterior corpora quadrigemina, pulvinar, these structures, them- 
selves, and the origin of the optic tract undergo degeneration (v. Monakoiv). 
2. The auditory centre lies on both sides (crossed) in the temporo-sphe- 
noidal lobes [according to Ferrier in the superior temporal convolution] ; when 
it is completely removed, deafness results, while partial (left side) injury causes 
psychical deafness. [See p. 898 for contradictory results.] Amongst the 
phenomena caused by partial injury is surditas verbalis (word-deafness), 
which may occur alone or in conjunction with coecitas verbalis. Wernicke 
found in all cases of word-deafness softening of the first left temporo-sphenoidal 
convolution (p. 906). In left-handed persons the centre lies perhaps in the 
right temporo-sphenoidal lobes ( Westphal). 
Clinical.—We may refer word-blindness and word-deafness to the aphataxic group of dis- 
eases, in so far as they resemble the amnesic form. A person word-blind or word-deaf resembles 
one who, in early youth, has learned a foreign tongue, which he has completely forgotten at a 
later period. He hears or reads the words and written characters; he can even repeat or write 
the words, but he has completely lost the significance of the signs. While an amnesic aphasic 
person has only lost the key to open his vocal treasure, in a person who is word-blind or word- 
deaf even this is gone. From a case of recovery it is known that to the patient the words sound 
like a confused noise. Huguenin found atrophy of the temporo-sphenoidal lobes after long- 
continued deafness. 
3. Gustatory and Olfactory Centre.—In the uncinate gyrus on the 
inner side of the temporo-sphenoidal lobe (especially on the inner side of that 
marked U in fig. 607), Ferrier locates the joint centres for smell and taste. 
These two centres do not seem to be distinct locally from each other. 
4. Tactile Areas and Cutaneous Sensibility.—According to Tripier 
and others, all the tactile cerebral fields from different parts of the body coin- 
cide with the motor cortical centres for these parts (compare p. 899). [Schafer 
and Horsley find that stimulation of the gyrus fornicatus gives rise to no mus- 
cular contractions, but its removal is followed by diminution in general and 
tactile sensibility of the opposite side of the body. See fig. 607, where this 
convolution is marked with the words “ cutaneous sensation.”] 
Occasionally, in epileptics, strong stimulation of the sensory centres, as expressed in the exces- 
sive subjective sensations, accompanies the spasmodic attacks (compare $ 393, 12). Such epi- 
leptiform hallucinations, however, occur without spasms, and are accompanied only by distur- 
bances of consciousness of very short duration (Berger). 
Course of the Sensory Paths.—The nerve-fibres which conduct im- 
pulses from the sensory organs to the sensory cortical centres pass through the 
posterior third of the posterior limb of the internal capsule between the optic 
thalamus and the lenticular nucleus (fig. 626, S). Hence, section of this part 
of the internal capsule causes hemiansesthesia of the opposite half of the body 
{Charcot). In such a case, sensory functions are abolished—only the viscera 
retaining their sensibility. There may also be loss of hearing, smell, and 
taste,—and hemiopia {Bechterew). 
Pathological.—In cases where there is more or less injury or degeneration of these paths, 
there is a corresponding greater or less pronounced loss of the pressure and temperature sense, 
of the cutaneous and muscular sensibility, of taste, smell, and hearing. The eye is rarely quite 
blind, but the sharpness of vision is interfered with, the field of vision is narrowed, while the 
color sense may be partially or completely lost. The eye on the same side may suffer to a slight 
extent. 
V. Numerous cases of injury of the anterior frontal region, without in- 
terference with motor or sensory functions, have been collected by Charcot, 910 
TOPOGRAPHY OF THE BRAIN. 
[Sec. 378. 
Fig. 623. 
Fig. 624. 
Fig. 625. 
Fig. 623.—Relation of the fissures and convolutions to the surface of the scalp, -f, most pro- 
minent part of the parietal eminence; a, convex line bounding parietal lobe below; b, con- 
vex line bounding the temporo-sphenoidal lobe behind (R. IV. Reid). Fig. 624.—The 
fissures of Rolando and Sylvius are marked as broad dark lines. The shaded circles mark 
approximately the motor areas. 1, lower extremity; 2, 3, 4, 5, 6, and a, b, c, d, upper ex- 
tremity ; 7, 8,9, 10, II, oro-lingual muscles (A. IV. Hare). Fig. 625.—Head, skull, and 
cerebral fissures. OP, occipital protuberance ; EAP, external angular process; SF, Sylvian 
fissure; A, its ascending limb; FR, fissure of Rolando; PE, parietal eminence, MMA, 
middle meningeal artery; TS. tip of temporo-sphenoidal lobe; B, Broca’s convolution; 
IF, inferior frontal sulcus; POF, parieto-occipital fissure. Sec. 378.] 
BASAL GANGLIA. 
Ferrier, and others. On the other hand, enfeeblement of the intelligence and 
idiocy are often observed in acquired or congenital defects of the prefrontal 
region. In highly intellectual men, Rudinger found in addition a considerable 
development of the temporo-sphenoidal lobe. According to Flechsig, there is 
no doubt that the frontal lobes and the temporo-occipital zone are related to 
intellectual processes, more especially the “higher” of these. 
Topography of the Brain.—The relations of the chief fissures and convolutions of the brain 
to the surface of the skull are given in fig. 610, the brain being represented after Ecker. [Turner 
and others have given minute directions for finding the position of the different convolutions by 
reference to the sutures and other prominent parts of the skull. The annexed diagram by R. 
W. Reid shows the relation of the convolutions to certain fixed lines (fig. 623).] 
[The position of the fissure of Rolando, where its upper end joins the great longitudinal 
fissure, is obtained by measuring on the scalp K in the middle line the distance between the 
glabella and the external occipital protuberance, or the inion, which in ordinary heads varies 
from 11 to 13 inches (fig. 625). Measured from before backwards, along this line, the distance 
from the glabella to the top of the fissure is 55.7 per cent, of the length of the whole line. The 
direction of the fissure is downwards and forwards, and the long axis of the fissure forms, with 
the average mesial line, an angle of 67°, the angle opening forwards. Its average length is 
inches.] 
[The fissure of Sylvius is found by drawing a line from the external angular process of the 
frontal bone backwards to the occipital protuberance, taking the nearest route between these two 
points. A point, I inch backwards from the angular process along this line, marks the origin 
of the fissure; while a straight line drawn to the centre of the parietal eminence marks the course 
of its posterior limb. The parieto occipital fissure will be two inches behind the upper end of 
the Rolandic fissure [A. IV. Hare).'] 
Corpus Callosum.—It is usually stated that the corpus callosum connects 
the convolutions of one side of the brain with those on the other, i. e., that it 
is an inter-hemispherical commissure. 
D. J. Hamilton, however, is of opinion that it is not an inter-hemispheric commissure, but is 
due to cortical fibres coming from the cortex cerebri to be connected with the basal ganglia of the 
opposite side. 
Section of the corpus callosum in dogs, however, produces no obvious disturbance (v. Koranyi). 
In man a case was described by Erb in which it was almost completely destroyed, yet there was 
no marked disturbance of motion, co-ordination, sensibility, the reflexes, intelligence, speech, or 
any marked impairment of the intelligence. The posterior part of the anterior commissure serves 
to connect the two gyri linguales (Popoff). 
[379. BASAL GANGLIA—MID BRAIN.—By the term “basal 
ganglia ” is meant the masses of gray matter constituting the corpus striatum 
and optic thalamus lying on the crus cerebri and at the base of the brain. 
Although they are grouped together, they are quite different in their origin, 
connections, and functions. The corpus striatum is developed in the wall of 
the cerebral vesicle, and comes to form the lateral wall of the lateral ventricles. 
It has few direct connections with the cortex. The optic thalamus is developed 
in the wall of the third ventricle, which it bounds laterally. It has connec- 
tions with almost every part of the cortex cerebri above, and with the tegmen- 
tum of the crus cerebri. It is thus intercalated in the course of afferent im- 
pulses passing to the cortex through the tegmentum.] 
[The corpus striatum consists of two parts, an intra-ventricular portion 
projecting into the lateral ventricle, the caudate nucleus, and an extra- 
ventricular portion, the lenticular nucleus. Between the head of the cau- 
date nucleus internally and the lenticular nucleus externally, lies the anterior 
division or anterior limb of the internal capsule. The fibres which pass between 
these ganglia do not seem to form connections with them. The expanded head 
of the caudate nucleus is in front, and lies inside and around the front, of the 
lenticular nucleus, with which and the anterior perforated space it is continuous ; 
it sweeps backwards into a tailed extremity, which nearly surrounds the len- 
ticular nucleus like a loop. The lenticular nucleus is biconvex in a hori- 912 
OPTIC THALMUS. 
[Sec. 379. 
zontal section, but triangular and subdivided into three divisions when seen in 
a vertical section (fig. 627). The older observations on the corpora striata in 
man may be dismissed, as a distinction was not drawn between injury to its 
two parts on the one hand and the internal capsule on the other.] 
[The caudate nucleus and lenticular nucleus in their development are 
co-ordinate with the development of the cortex cerebri. Electrical stimu- 
lation of these ganglia causes general muscular contractions in the opposite 
half of the body, which are due to simultaneous stimulation of the neighboring 
cortico-muscular paths. The same result is obtained as if all the motor cor- 
tical centres were stimulated simultaneously. Beevor and Horsley regard the 
basal ganglia as inexcitable, at least they failed to get the slightest movement 
by exciting the sectional surfaces of either of these ganglia.] 
Gliky did not observe movements on stimulating the corpus striatum in rabbits; it would seem 
that in these animals the motor paths do not traverse these ganglia, but merely pass alongside of 
them. 
[Lesions of the lenticular nucleus or of the caudate nucleus do not seem to 
give rise to any permanent symptoms, provided the internal capsule be not in- 
jured.] Destruction of the internal capsule, however, causes paralysis of motion 
of sensibility, or both, on the opposite side of the body, according to the part 
of it which is injured. The corpus striatum is quite insensible to painful stimu- 
lation (.Longet). 
Pathological.—In man, a lesion, not too small, destroying the anterior part of the corpus 
striatum, is followed by permanent paralysis of the opposite side, provided the internal capsule is 
injured, but the paralysis gradually disappears if the lenticular and caudate nucleus only are af- 
fected (compare \ 365). Sometimes there is dilatation of the blood vessels in consequence of 
vaso-motor paralysis (| 377) if the posterior part is injured (Nothnagel); redness and a slightly 
increased temperature of the paralyzed extremities, at least for a certain time ; swelling or oedema 
of the extremities ; sweating; anomalies of the pulse detectable by the sphygmograph; decubi- 
tus acutus on the paralyzed side; abnormalities of the nails, hair, skin; acute inflammation of 
joints, especially of the shoulder. Later, contracture or permanent contraction of the paralyzed 
muscles takes place {Huguenin, Charcot'). In some cases there is cutaneous anaesthesia, and 
occasionally enfeeblement of the sense-organs of the paralyzed side, and both when the posterior 
third or sensory crossway of the posterior section of the internal capsule is affected. Usually, 
however, hemiplegia and hemiancesthesia occur together. 
[Optic Thalamus.—It is developed in the wall of the vesicle of the third 
ventricle, and hence forms the lateral wall of this cavity. It is a mass of gray 
matter lying obliquely on and partly embedded in the crus. Its ventricular sur- 
face is covered with a thin layer of gray matter, and the whole thalamus con- 
sists of gray matter mixed with white matter. The nerve-cells are large and 
branched and frequently contain pigment. The posterior free cushion-like 
part is called the pulvinar, while the larger anterior part contains three nuclei 
known as the inner or median nucleus, the lateral, and anterior nucleus. 
Under the thalamus and dorsal to the tegmentum is the sub-thalamic region 
in which the tegmentum ends.] 
[Connections of the Optic Thalamus.—This body is said to receive 
fibres from all parts of the cortex, while it is also connected with the tegmental 
system and with certain fibres of the optic tract.] 
Functions of the Optic Thalamus.—Ferrier did not observe any move- 
ments on stimulating the optic thalami with electricity. As the pulvinar, or 
posterior extremity of the optic thalamus, is in part the origin of the optic 
nerve, and is also connected by fibres with the cortex cerebri, it is probably 
related to the sense of sight. Injury to its posterior third in man results in 
disturbance of vision {Nothnagel). Ferrier surmises that the sensory fibres pass 
through the optic thalami on their way to the cortex, so that when they are 
destroyed insensibility of the opposite half of the body is produced. Removal Sec. 379]. 
INTERNAL CAPSULE, 
of the optic thalamus, or destruction of the part in the neighborhood of the 
inspiratory centre in the wall of the third ventricle, influences the co-ordinated 
movements in the rabbit (Christiani). 
We know very little definitely as to the functions of these organs. After injury to one thala- 
mus, there has been observed enfeeblement or paralysis of the muscles of the opposite side, 
together with mouvements de manege; and sometimes hemiansesthesia of the opposite side, with 
Gyrus fornicatus 
Corpus callosum 
Cornu anticum. 
Septum lucidum. 
Caput nuclei caudati. 
Columnae fomicis. - 
Capsula interna 
(anterior limb). 
Corpus striatum. 
Capsula externa. 
Island of Reil. 
Stria terminalis. 
Nucleus lentiformis. 
Claustruin. 
Thalamus opticus. _ 
Capsula interna 
(posterior limb). 
- Thalamus opticus. 
Pulvinar. 
Corpus genieula- 
tum mediate. 
Caudate nucleus. 
Brachium conjunc- — 
tivum anticum. 
Pedunculus cerebri. 
Hippocampus. 
ad corpora 
quadrige- 
mina. 
ad medullam 
oblongatam. 
. ad pontem. 
Crus 
cere belli 
Calcar avis. 
A.la cinerere 
Obex. 
Clava. 
Funiculus cuneatus 
Funiculus gracilis. 
Human brain, with the hemispheres removed by a horizontal incision on the right side. 4, 
trochlear; 8, acoustic nerve; 6, origin of the abducens ; F, A, L, position of the pyramidal 
(motor) fibres for the face, arm, and leg; S, sensory fibres. 
Fig. 626. [Sec. 379. 
914 
INTERNAL CAPSULE. 
or without affections of the motor areas, have been recorded. Extirpation of certain cortical 
areas (rabbit) is followed by atrophy of certain parts of the thalamus (v. Monakow.') 
Relation of Basal Ganglia to Internal Capsule.—The corpus striatum 
consists of an intra-ventricular part, the caudate nucleus, and an extra- 
ventricular part—i. <?., no part of this appears in the lateral ventricle—the len- 
ticular nucleus. The lenticular nucleus, a mass of gray matter, consists 
of three parts, best seen in a vertical section (fig. 627, 1, 2, 3), with white 
matter between them, the striae medullares. [These striae medullares are 
inexcitable to electrical stimuli.] Of the three masses of gray matter into which 
the ventricular nucleus is split up by the white fibres or striae medullares, 
the inner and central ones (fig. 627, 3, 2) are called the globus pallidus 
on account of their paler color, while the outer one (fig. 627, 1) is called the 
putamen.] 
The anterior limb of the internal capsule sweeps between the caudate and 
lenticular nucleus, while the posterior segment lies between the optic thalamus 
and the lenticular nucleus (fig. 626). External to the first division of the 
lenticular nucleus is the external capsule (figs. 626, 627), whose function is 
unknown. External to this is the claustrum, whose function is also unknown. 
It is evident that hemorrhage into or about the basal ganglia is apt to involve 
the fibres of the internal capsule. [When the lenticulo-striate artery, or, as it is 
called, the “ artery of hemorrhage,” ruptures (fig. 615, aSL), it may not only 
destroy the lenticular nucleus, but the internal capsule will be compressed ; 
and the same is the case with the lenticulo-optic artery—the external capsule 
will tend to force the blood inwards. We know that in the posterior limb 
of the capsule the volitional or pyramidal fibres lie in the following order from 
before backwards—those for the face (and tongue) in the knee, in the anterior 
third those for the arm and hand, and in the middle third for the leg, and per- 
haps behind these those for the trunk (fig. 626), so that a very small lesion in 
this region will affect a large number of these fibres, converging as they do 
like the rays of a fan from the motor cortical areas where the arrangement of 
these centres is a supero-inferior one (fig. 614), to become an antero-posterior 
one in the knee and posterior limb of the internal capsule (fig. 626). The 
posterior third of this limb is sensory and is the “ sensory crossway.” This, 
however, is true only for the lowest levels of the capsule (.Beevor and Horsley).] 
[Horsley points out that hemorrhage from the lenticulo-striate artery affects in order the mus- 
cles of the face, arm, leg, and trunk, while recovery is in the inverse order.] 
[The internal capsule is composed of fibres converging through the corona 
radiata and coming from and going to the cortex cerebri ; it varies in its shape 
in different parts of its course. It contains several sets of fibres, some of which 
are sharply marked off from their neighbors.] 
[The arrangement of the fibres in the internal capsule in order from before 
back, and classified according to the region of the cortex with which they are 
connected, is— 
1. Praefrontal. 
2. Pyramidal or fronto-parietal. 
3. Temporal. 
4. Occipito-temporal. 
5. Occipital. 
The praefrontal fibres occur in the anterior limb of the internal capsule ; 
they are inexcitable to electrical stimulation, and are certainly not efferent 
in function. They pass to the mesial side of the crus, and also to the sub- 
thalamic region. They degenerate when the frontal area is destroyed. The 
course of the pyramidal fibres has been stated already. The temporal, oc- Sec. 379.] 
FIBRES OF THE PYRAMIDAL TRACT. 
915 
cipito-temporal and occipital fibres are inexcitable and seem to be con- 
nected with the general and special senses (.Beevor and Hors ley). ] 
[The fibres of the pyramidal tract arise in the motor areas (§ 378) of the 
cortex, and converge to form that part of the internal capsule which in a hori- 
zontal section, such as is shown in fig. 626, go to form the knee and the an- 
terior two-thirds of the posterior limb of the capsule. The fibres from the 
several motor areas occupy definite positions in the capsule (fig. 626), and it is 
to be noted that while the arrangement of the cortical motor areas is hardly a 
vertical one, the corresponding tracts have an anterior posterior or fore and aft 
arrangement in the internal capsule, as seen in a horizontal section. Traced 
from the capsule, they run into the pes, and occupy its central and larger 
portion, being bounded internally by a median strand of fibres and externally 
by another group of fibres. From the pes they pass into the pons, where they are 
split up into a number of bundles interlacing with the deeper transverse fibres 
of the pons. In the pons some of the fibres form connections with certain of 
the nerve nuclei, i. e., with the nuclei of the motor cranial nerves, and the 
remainder of the fibres proceed onwards to the bulb to form its anterior pyra- 
mids. The prolongation of these to the cord is given in § 365. Thus it is 
evident that there is a set of cranial pyramidal fibres and a spinal set.] 
[Anterior or Fronto-cortical Fibres.—The frontal convolutions lying 
anterior to the motor areas also send fibres to the corona radiata, which converge 
and enter the anterior limb of the internal capsule (fig. 626). Thence they 
enter the crus and occupy its small median part. They can be traced through 
the pons, lying internal to the pyramidal fibres, and they seem to end in the 
pons, ending perhaps in the gray matter of the pons. Perhaps they are con- 
nected by transverse fibres 
in the pons with the cere- 
bellum. They degenerate 
in a downward direction. 
These fibres are called the 
fronto-pontine or fron- 
to-cerebellar fibres.] 
[Posterior or Tem- 
poro - occipito- cortical 
Fibres.—Fibres pass from 
the temporal and occipital 
regions to the internal cap- 
sule, and occupy its poste- 
rior third or thereby be- 
hind the pyramidal fibres; 
they pass into the pons and 
occupy its outer part and 
appear to end in the gray 
matter of the pons. These 
three tracts undergo 
descending degeneration, 
and their trophic centres 
are the cells of the cortex 
cerebri.] 
[Some fibres arise in the 
nucleus caudatus, and can 
be traced as a descending 
tract as far as the pons, but lying dorsal to the previously mentioned tracts.] 
[Corona Radiata.—Although the internal capsule is chiefly made up of 
Nucleus 
caudatus. 
Corpus 
callosum. 
Pillars of 
the fornix. 
Internal 
capsule. 
Optic 
thalamus. 
Soft com- 
missure. 
External 
capsule. 
Claustrum. 
Frontal section through the right cerebral hemisphere in front 
of the soft commissure (posterior surface of the section). 
Fig. 627. 916 
CORONA RADIATA AND CRURA CEREBRI. 
[Sec. 379. 
fibres that enter the crusta, still there are other fibres coming from the cortex, 
which form part of the corona radiata, but which, however, do not enter the 
crusta. Some fibres coming from the frontal and parietal areas of the brain 
converge to the extreme anterior end of the anterior limb of the internal cap- 
sule in front of the fronto-pontine fibres, and appear to end in the optic thala- 
mus. Passing from or to the occipital and temporal regions, but chiefly the 
former, are fibres which lie at the tip of the posterior limb of the internal 
capsule, and are for the most part the fibres which form the optic radiation 
of Gratiolet. They enter the optic thalamus. But some fibres pass to the 
optic thalamus without entering the internal capsule. Thus the optic thalamus 
has wide and extensive connection with the cortex, so that other parts of the 
nervous system connection with the thalamus may thus indirectly be brought 
into connection with the cortex cerebri.] 
[The crura cerebri (fig. 564, P), or cerebral peduncles, are two thick strands 
as they emerge above the pons, and as they are much larger than the pyramidal 
tracts, they must receive many fibres within the pons. A transverse section 
(fig. 628) shows that on them posteriorly, and connecting them, are the cor- 
pora quadrigemina (CQ). The crus proper is divided by the substantia nigra 
(SN) into a lower ventral part, the crusta, pes, or basis, and an upper dorsal 
part, or tegmentum. The crusta is composed exclusively of ascending and 
descending nerve-fibres, which can be traced from the cerebrum to the pons, 
bulb, and spinal cord. But the tegmentum, in addition to many nerve-fibres, 
contains much gray matter with nerve-cells. Near the middle of the teg- 
mentum is the “red nucleus” or “tegmental nucleus” (RN). Outside 
this is the fillet (F), a well-defined bundle of nerve-fibres running upwards 
from the pons. Above the nucleus, near the middle line, is the “ posterior 
longitudinal bundle ” (p. 1. b.), which is triangular in section. Above 
the tegmentum lie many nerve-cells, the origin of the third nerve (III), and 
arranged around the iter is much gray matter. The tegmentum itself ends 
partly in the optic thalamus and partly in the sub-thalamic region, i. e., ventral 
to the optic thalamus.] 
[The fillet arises in the inter-olivary layer of the bulb from fibres derived 
from the supra-pyramidal or sensory decussation ; the fibres come from the 
clava and caudate nuclei of the opposite side (p. 829). As it runs upwards, it 
joins the tegmentum, and receives accessions of fibres in its course from the gray, 
matter of the pons. Some of its fibres—lateral—appear to end in the poste-* 
rior corpus quadrigeminum, and others in the white matter below the anterior 
corpus quadrigeminum ; the median fibres pass onwards, some to end in the 
sub-thalamic region, others in the optic thalamus, and others again appear to 
be continued on to the cortex.] 
[The posterior longitudinal bundle appears to be a continuation up- 
wards of some of the fibres of the anterior ground-bundle of the anterior 
column of the cord; it runs dorsal to the formatio reticularis of the bulb. It 
perhaps gives origin to part of the nuclei for the nerves of the eyeball.] 
The pes or crusta of the cerebral peduncle when traced onwards gradually 
rises more dorsally, and spreads out like a hollow case, with the convexity look- 
ing outwards, forming between the optic thalamus and caudate nucleus inter- 
nally and the lenticular nucleus externally the internal capsule. The internal 
capsule necessarily varies in its shape according as it is viewed in a vertical 
transverse (fig. 627) or sagittal or horizontal section of the brain (fig. 626), the 
fibres of the internal capsule diverge from each other, forming part of the 
corona radiata, which radiates to all parts of the cortex cerebri.] 
Injury to one cerebral peduncle causes, in the first place, violent pain 
and spasm of the opposite side, while the blood-vessels on that side contract Sec. 379.] 
PONS VAROLII. 
917 
and the salivary glands secrete. These phenomena of irritation are followed 
by paralytic symptoms of the opposite side, viz., anaesthesia (§ 365) and paresis, 
or incomplete voluntary control over the muscles, as well as paralysis of the 
vaso-motor nerves. In affections of the cerebral peduncle in man, we must 
remember the relation of the oculo-motorius to it, as the latter is often para- 
lyzed on the same side [while the extremities, tongue, and half the face are 
paralyzed on the opposite side from the lesion]. 
The middle third of the crusta of the cerebral peduncle (fig. 502) includes the direct pyra- 
midal tracts (g§ 365, 378). The fibres of the inner third connect the frontal lobes with the 
cerebellum through the superior cerebellar peduncles. In the outer third are fibres which con- 
nect the pons with the temporal and occipital cerebral lobes (Flechsig). The fibres which pass 
from the tegmentum into the coronar radiata conduct sensory impulses (Flechsig\ 
[The pons Varolii contains ascending and descending fib es, as well as 
transverse ones, and, in addition, the continuation upwards of gray matter from 
the medulla, special masses of gray matter, and the nuclei of certain cranial 
nerves. Its appearance in section necessarily varies with the region where the 
section is made. Fig. 629 is a transverse section through part of the seventh 
nerve. The lower part shows the superficial (s. t. f.) and deep (d. t. f.) trans- 
verse fibres, with the pyramidal fibres (Py) between them.] 
Stimulation or section of the pons causes pain and spasms ; after the section, 
there may be sensory, motor, and vaso- 
motor paralysis, together with forced 
movements. For diagnostic purposes 
in man, it is important to observe it 
alternate hemiplegia be present. 
[In lesions situated in the lower half of one 
side of the pons, there is facial paralysis on the 
same side as the lesion and paralysis (motor 
and sensory, and more or less complete) on the 
opposite side of the body—this is called alter- 
nate paralysis ; while, if the lesion be in the 
upper half of one side of the pons, the facial 
paralysis is on the same side as the paralysis of 
the body. But the parts supplied by the 5th 
and 6th nerves may also be involved. This is 
explained by fig. 630, where the upper facial 
fibres cross in the pons. Sudden and extensive 
lesions of the pons are frequently associated 
with hyperpyrexia, the temperature often rising 
rapidly within an hour, perhaps from the gray 
matter in the floor of the 4th ventricle being 
affected; but whether it is due to some effect on 
a heat-regulating or heat-producing centre is 
uncertain. Tumors of considerable size may 
press on the pons without producing very 
marked symptoms, as tumors tend to push aside tissues, unless they be infiltrating in their char- 
acter. Lesions of the transverse superficial fibres (middle cerebellar peduncles) often give 
rise to involuntary forced movements, there being a tendency to move to one side or the other.] 
[Corpora Quadrigemina.—The anterior brachium arises from the gray 
matter of each corpus, and passes downwards and forwards to join the external 
corpus geniculatum and help to form the optic tract, but some of its deeper 
fibres pass towards the thalamus, and from it to the corona radiata, and so on to 
the cerebral cortex. The posterior brachium passes to the internal geniculate 
body, whence it is continued on to the tegmentum.] 
Destruction of the Corpora Quadrigemina.— On one side in mammals 
(or their homologues, the optic lobes in birds, amphibians, and fishes) causes 
actual blindness, which may be on the same or the opposite side, according to 
Scheme of transverse section of the cerebral 
peduncles. CQ, corpora quadrigemina; Aq, 
aqueduct; p.l.b., posterior longitudinal 
bundle; F, fillet or lemniscus; RN, red, 
nucleus; SN, substantia nigra; III, third 
nerve; Py, pyramidal tracts; Fc, fronto- 
cerebellar ; and TOC, temporo-occipital fibres 
of the crusta; CC, caudate-cerebellar fibres 
in upper part of crusta (after Wernicke and 
Gowers). 
Fig. 628. 918 
CORPORA QUADRIGEMINA. 
[Sec. 379. 
the relation of the fibres crossing at the optic chiasma (§ 344). .7h/tf/destruction 
causes blindness of both eyes. At the same time the reflex contraction of the 
pupil, due to stimulation of the retina with light, no longer takes place 
(.Flourens), where the optic is the afferent and the oculomotorius the efferent 
nerve (§ 345). If the cerebral hemispheres alone be removed, the pupil still 
contracts to light, as well as after mechanical stimulation of the optic nerve 
(ZZ. Mayo). Destruction of the corpora quadrigemina interferes with the 
complete harmony of the motor acts; disturbance of equilibrium and inco- 
ordination of movements occur (Serves). In frogs, Goltz observed not only 
awkward, clumsy movements, but at the same time the animals have to a large 
extent lost the power of completely balancing the body (p. 869). A similar 
result was observed in pigeons (M'Kendrick) and rabbits (.Ferrier). Extir- 
pation of the eyeball is followed by atrophy of the opposite anterior corpus 
quadrigeminum ( Gudden). 
Fig. 629. 
Fig. 630. 
Fig. 629.—Transverse section of the pons through part of the seventh nerve, x 2- F. R., for- 
matio reticularis; VII, seventh nerve; Va, ascending root, and Vm. motor root of the 
fifth nerve; F, fillet; s. o., superior olive ; s.l.b., superior longitudinal bundle; Py, pyra- 
midal fibres; R, restiform body; M. P., middle peduncles of cerebellum; d.t.f. and s.t.f., 
deep and transverse superficial fibres of the pons (after Wernicke). Fig. 630.—Scheme of 
the fibres in the pons; PT, pyramidal tracts; ,F, facial fibres; u, upper, /, lower lesion; 
MO, medulla oblongata ; DP, decussation of pyramids. 
According to Bechterew, the fibres of one optic tract pass through the anterior brachium 
(fig. 626) into the anterior pair (nates) of the corpora quadrigemina; while those fibres which 
cross in the chiasma (fig. 514) pass into the posterior pair (testes). According to this arrange- 
ment we have partial blindness, according as one or other pair of these bodies is destroyed. 
[In man, very little is known regarding the effects of disease of the corpora quadrigemina, 
interference with the ocular muscles being the most marked symptom ; but the inco-ordination 
of movement which has been observed may be due to pressure upon the superior cerebellar 
peduncle, while it is by no means certain that the defects of vision are directly due to lesions of 
these bodies.] 
Stimulation of the Corpora Quadrigemina.—The corpora quadrigemina react to electri- 
cal, chemical, and mechanical stimuli. The results of stimulation are very variously stated. 
According to some observers, there is dilatation of the pupil on the same side; according to 
Ferrier, it may be the pupil on the opposite or on the same side. The stimulation may be 
conducted from the corpora quadrigemina to the medulla oblongata, and to the origin of the 
sympathetic, for, after section of the sympathetic nerve in the neck, dilatation of the pupil no 
longer takes place. According to Knoll, the contraction of the pupil observed by the older 
experimenters occurs only when the adjoining optic tract is stimulated. Stimulation of the 
right anterior corpus quadrigeminum causes deviation of both eyes to the left (and conversely) ; 
on continuing the stimulation, the head is turned to this side. On dividing the corpora quad- 
rigemina by a vertical median incision, stimulation of one side causes the result to take place Sec. 379.] 
FORCED MOVEMENTS. 
919 
only on one side (Adamiik). Ferrier observed signs of pain on stimulating these organs in 
mammals. Carville and Duret conclude from their experiments that these organs are centres 
for the extensor movements of the trunk. Ferrier found, on stimulating one optic lobe in a 
pigeon, dilatation of the opposite pupil, turning of the head towards the other side and back- 
wards, movement of the opposite wing and leg; strong stimulation caused flapping movements 
of both wings. Danilewsky, Ferrier, and Lauder Brunton observed a rise of the blood-pressure 
and slowing of the heart-beat, together with deeper inspiration and expiration. 
Bechterew ascribes all the phenomena, except those of vision itself, which accompany injury 
or stimulation of these bodies, to affections of deeper-seated parts. He asserts that the corpora 
quadrigemina contain neither the centre for the movements of the pupils nor that for the 
combined movements of the eyeballs; not even the centre for maintaining the equilibrium of 
the body. Stimulation of these bodies causes the animals to perform marked movements. 
Reflex phenomena, nystagmus, forced movements, and unsteadiness of the gait only occur, how- 
ever, when the deeper parts are injured. 
Pathological.—Lesions of the anterior pair in man, according to the extent of the lesion, 
cause disturbance of vision, failure of the pupil to contract to light, and even blindness; there 
may be paralysis of the oculomotorii on both sides. Disease of the posterior pair may be asso- 
ciated with disturbances of co-ordination (Nothnagel). 
Forced Movements.—It is evident from what has been said regarding 
the importance of the corpora quadrigemina for the harmonious execution of 
movements, that unilateral injury of such parts as are connected with them by 
conducting channels, must give rise to peculiar unilateral disturbance of the 
equilibrium, causing variations from the symmetrical movements of both sides 
of the body. These movements are called forced movements. To this class 
belong the “ mouvements de manege,” where the animal, instead of 
moving in a straight line, runs round in a circle; index movements, where 
the anterior part of the body is moved round the posterior part, which remains 
in its place, just like the movements of an index round its axis; and rolling 
movements, when the animal rolls on its long axis. All these forms of 
movement may pass into each other, and they are, in fact, merely different 
varieties of the same kind of movement. The parts of the nervous system 
whose injury produces these movements are the corpus striatum, optic thala- 
mus, cerebral peduncle, pons, middle cerebellar peduncles, and certain parts of 
the medulla oblongata. Eulenburg observed index movements in the rabbit, 
after injury to the surface of the brain, and Bechterew observed the same in 
dogs. Forced movements, together with nystagmus and rotation of the eye- 
balls, are caused by injury to the olives (Bechterew). The statements of 
observers vary as to the direction and kind of movement produced by injuring 
individual parts. The following observations have been made : Section of 
the anterior part of the pons, and of the crura cerebelli cause index, or, 
it may be, rolling movements towards the other side; section of the posterior 
part of the same regions causes rolling movements towards the same side, while 
the same result is caused by a deeper puncture into the tuberculum acusticum, 
or into the restiform body. Section of one cerebral peduncle causes mouve- 
ments de manege, while the body is curved with the convexity toward the 
same side. The nearer to the pons the section is made the smaller is the 
circle described; ultimately index movements occur. Injury to one optic 
thalamus produces results similar to puncture of the anterior part of the cerebral 
peduncle, because the latter is injured along with it at the same time. Injury 
to the anterior part of one optic thalamus causes the opposite kind of 
forced movement, viz., with the concavity of the body towards the injured 
side. Injury to the spinal portion of the medulla oblongata is followed by 
bending of the head and vertebral column, with the convexity towards the 
injured side, along with movements in a circle. When the anterior end of the 
calamus and the part above it are injured, the movements are towards the sound 
side. 
Strabismus and Nystagmus.—Amongst the forced movements may be 920 
PINEAL AND PITUITARY BODIES. 
[Sec. 379. 
reckoned deviation of the eyeballs, strabismus or squinting, and involuntary 
oscillation of the eyeballs, constituting nystagmus. The latter condition occurs 
after superficial lesions of the restiform body, as well as of the floor of the 4th 
ventricle. A unilateral, deep, transverse injury, from the apex of the calamus 
upwards as far as the tuberculum acusticum, causes the eye of the same side to 
squint downwards and forwards, that of the other side backwards and upwards. 
Section of both sides causes this condition to disappear (Schwahn). Hence, 
Eckhard assumes that the medulla oblongata is the seat of an apparatus con- 
trolling the movements of the eyes (Eckhard'), which can be excited by sudden 
anaemia, e.g., ligature of the cephalic arteries in a rabbit. 
In pathological degeneration of the olivary body of the medulla oblongata in man, Meschede 
observed intense rotary movements towards the same side. 
Theory.—In order to explain the occurrence of forced movements, it is suggested that there 
is unilateral incomplete paralysis (Lafarque), so that the animal in its efforts to move onwards 
leaves the paralytic side slightly behind the other, and hence there is a variation from the 
symmetry of the movements. Brown-S6quard regards the matter in exactly an opposite light, 
viz., as due to stimulation from injury, causing an excessive activity of one-half of the body. 
Henle ascribes the movements to vertigo, or a feeling of giddiness caused by the injury. In all 
operations on the central nervous system, where the equilibrium is deeply affected, there is a 
considerable increase in the number and depth of the respirations (Landois). 
Specially interesting is the cerebral unilateral decubitus acutus or bed-sore, described by 
Charcot, which always occurs on the paralyzed side of the body, i. <?., on the side opposite to the 
cerebral injury. It begins on the second or third day, rapidly causes enormous destruction and 
sloughing of the tissues on the back and lower extremities, and death soon takes place. The 
decubitus which occurs after spinal injuries usually begins in the middle line of the buttocks, 
and extends symmetrically on both sides. In cases of unilateral injury to the spinal cord, the 
decubitus occurs on the corresponding 
side of the sacral region (p. 736). 
[The Pineal Gland or epiphysis 
cerebri lies on the back of, and is con- 
nected with, the third ventricle (fig. 
631, Z). It projects backwards be- 
tween the corpora quadrigemina. It is 
originally developed as a hollow out- 
growth from that part of the embryonic 
brain which becomes the third ventricle. 
The hollow centre usually disappears, 
while the distal portion becomes en- 
larged and is often lobulated. Its distal 
portion may terminate outside the skull; 
and in some animals there is developed 
in the median line of the skull an eye 
—pineal eye—arranged on the inver- 
tebrate plan, as in Anguis, Hatteria, etc. 
(De Graaf, Spencer) (§405).] 
[The pituitary body or hypophysis 
cerebri consists of two lobes, different 
in origin and structure (fig. 631, H). 
The posterior lobe is developed as a 
hollow outgrowth from the part of the 
embryonic brain connected with the 
third ventricle. It loses its cavity and 
its nervous tissue ; is permeated by con- 
nective-tissue and blood-vessels; and 
is connected with the floor of the third 
ventricle by the infundibulum. The 
anterior lobe is developed as a tubular 
invagination of the stomodaeum, i. e., 
from the ectoderm of the buccal cavity ; 
but it soon loses its connection with this cavity as the upper end enlarges and the stalk atrophies. 
In mammalia, the upper expanded end unites with the anterior lobe to form the pituitary body. 
For the effects of its removal, see § 103, V.] 
Fig. 631. 
Longitudinal section of an adult human brain. Aq, 
aqueduct of Sylvius; B, corpus callosum; Ca, ante- 
rior commissure; Cm, middle commissure; Col, 
lamina terminalis; Cp, posterior commissure; FM, 
foramen of Munro; G, fornix; H, pituitary body; 
HH, cerebellum ; MH, corpora quadrigemina; NH, 
medulla oblongata ; P, pons Varolii; R, spinal cord; 
Sp, septum lucidum; I, infundibulum; Tch, tela 
choroidea; To, optic thalamus; VH, cerebrum; Z, 
pineal gland; /, olfactory lobe and nerve; II, optic 
nerve. Sec. 380.J 
STRUCTURE OF THE CEREBELLUM.. 
921 
Increase of surface is obtained in the cerebellum by means of a number of leaf-like folds, each 
of which has a number of secondary leaflets or folds. 
380. STRUCTURE AND FUNCTIONS OF THE CEREBELLUM.—[Structure. 
—On examining a vertical section of a cerebellar leaflet, we observe the following microscopic 
appearances :—Externally is the pia mater with its blood-vessels (fig. 632, a), which penetrate 
into the gray matter, which forms a thin, continuous layer on the surface ; within is the medulla 
or central white matter, composed of white 
nerve-fibres. The gray matter consists of b, 
a broad outer or molecular layer (400 /x 
thick), largely composed of branched fibrils; 
and internal to it is d, the “granular,” or 
nuclear, or rust-colored layer. On the 
boundary line between these two is the layer 
of Purkinje’s cells, c. The cells of Purkinje 
form a single layer of large multipolar flask- 
shaped nerve-cells (40 fx by 30 fx), which have 
been compared to the branched antlers of a 
stag (fig. 633). From their outer surface is 
given off a process which rapidly divides and 
gives rise to a large number of smaller pro- 
cesses running outwards in the outer gray 
layer. These processes branch to form fibrils, 
and the latter form part of the ground-plexus 
of fibrils in this layer. An unbranched axial 
cylinder process is sent inwards to the granu- 
lar layer, which it traverses obliquely and 
becomes continuous with a perve-fibre in the 
Fig. 632. 
Fig- 633. 
Fig. 632.—Vertical section of the cerebellum, a, pia mater; b, external layer; c, layer of 
Purkinje’s cells; d, inner layer; e, medullary white matter. Fig. 633.—Purkinje’s cell, 
sublimate preparation, x 120. 
central white matter—every cell of Purkinje being continuous with a straight unbranched 
medullated nerve-fibre. The unbranched nerve-fibres run straight from the medulla through 
the granular layer, forming no connection with its granules. A second set of branched or 
anastomosing, often varicose, nerve-fibres, finer than the foregoing, pass from the medulla into 
the granular layer, where they form a network of fibrils, which is continued into the molecular 
layer. This shows that the gray superficial matter of the cerebellum is connected with the 
central white matter by two sets of nerve-fibres. The granular or nuclear layer is composed 
of closely packed granules of two kinds; one is stained by hsematoxylin, and the other with 
eosin (.Denissenko). The hsematoxylin stained cells are most numerous; they consist of a nucleus [Sec. 380. 
922 
.STRUCTURE OF THE CEREBELLUM. 
surrounded by protoplasm, and are what were formerly called granules. The eosin-stained cells, 
which are also stained by nigrosin (Beevor), are interposed in the course of medullated nerve- 
fibres. The haematoxylin cells, called glia cells by Beevor, have processes, and form a net- 
work throughout the granular layer, which also extends into the molecular layer. This net- 
work is regarded as the continuation of the modified myelin of the nerve-fibres, and it forms 
a capsule for the cells of Purkinje. The molecular layer consists of a ground substance, com- 
posed of a spongy network of fine fibrils, some of which seem to be of the nature of neuroglia, 
and others are nerve-fibrils. When these fibrils are cut across they give the layer its molecular 
dotted appearance. Some authors describe it as containing a homogeneous substance, part of 
which is more condensed to form a limitans externa on the surface of the cerebellum, while on 
the boundary line next the granular layer the branches of the glia-cells form a limitans interna, 
and between the two stretches the neuro-keratin network. Some small varicose nerve-fibres 
exist in this layer continuous with those in the granular layer. The branched process of the 
cells of Purkinje is fibrillated, and the finer processes are composed also of fibrils, which are 
gradually distributed until they become isolated. It is suggested by Beevor that these fibrils 
bend at a right angle in a plane parallel to the surface, and rearrange themselves as fibres sur- 
rounded by a medullated sheath, and that these fibres run inwards through the molecular and 
granular layers—as the branched fibres—to the medulla.] 
[Results by Golgi’s Method.—It has been shown by Golgi, Ramon y 
Cayal and Kolliker that the nuclear layer contains a very large number of mul- 
tipolar, nerve-cells, some small and others large. From the smaller nerve-cells 
an axis-cylinder process proceeds vertically into the molecu- 
lar layer, where it divides into two horizontal and longitu- 
dinal unbranched fine fibres whose terminations are unknown. 
The larger cells occur more seldom, and their numerous 
branched protoplasmic processes penetrate deep into the 
molecular and central white matter. 
In the molecular layer also are branched nerve-cells; the 
innermost ones have been called “basket-cells.” They have 
numerous long protoplasmic processes, the branches of some 
of which reach to the outer parts of the molecular layer. 
The axis-cylinder process is very long and runs transversely 
parallel to the cerebellar folds over the bodies of the cells of 
Purkinje, and sends inwards branches which rapidly split up 
and form a sort of basket-like plexus round the bodies of 
Purkinje’s cells.] 
Purkinje’s cells give off an extraordinary number of 
protoplasmic processes, which pass quite to the surface of 
the molecular layer, but these processes never anastomose 
amongst themselves and they all lie in one plane, viz., in the 
transverse direction of the leaflet, so that the cell appears as 
in fig. 633 when the plane of ramification is directed to one 
side, but if looked at on edge they present the appearance 
seen in fig. 634. The processes end free. The axis-cylinder 
process gives off some lateral branches, some of which run 
backwards into the molecular layer. Numerous fine medul- 
lated branched nerve-fibres exist in the molecular layer, and 
they form a dense network in the granular layer under 
Purkinje’s cells. Some of the nerve-fibres in the central white matter divide 
before they enter the gray matter.] 
Function of the Cerebellum.—Injuries of the cerebellum cause dis- 
turbances in the harmony of the movements of the body. Most probably the 
cerebellum is a great and important central organ for the finer co-ordination 
and integration of movements. The fact that it is connected with all the col- 
umns of the spinal cord and with all the central ganglionic masses renders 
this very probable. The direct cerebellar tracts from the lateral column of 
the cord conduct sensory impressions to the cerebellum, and thus indicate the 
Purkinje’s cell seen 
from the side, the 
section being 
made vertical to 
the surface and 
parallel with the 
long axis of a 
convolution. 
Fig. 634. Sec. 380.] 
FUNCTIONS OF THE CEREBELLUM. 
923 
posture of the trunk. The cerebellum may affect the motor nerves of the cord 
through fibres which pass downward in the lateral columns of the cord from 
the restiform bodies (Flechsig). Injury of the cerebellum neither produces dis- 
turbance of the psychical activities, nor does it interfere with the will or con- 
sciousness. Injuries to the cerebellum itself do not give rise to pain. 
According to Schiff, the cerebellum does not actually regulate the co-ordination of move- 
ments. According to him, there is a mechanism on both sides of the middle line, which 
increases all the complicated muscular movements—not only those for powerful contractions, 
but also the peculiar fine movements which fix the limbs and joints. Luciani asserts that 
destruction of the cerebellum produces a condition of incomplete tonus, there being a want of 
energy to control the voluntary muscles. Each half of the organ acts on both halves of the 
body. 
Injury or Removal of Cerebellum.—The immediate results produced 
by injury to or removal of the cerebellum have been admirably described by 
Flourens (fig. 635). On removing the most superficial layers in a pigeon, the 
animal merely showed signs of weakness and interference with the uniformity 
of its movements. On removing more of the cerebellum, the animal became 
greatly excited, and made violent irregular movements, which did not partake 
of the character of convulsions. The sensorium was unaffected, while vision 
and hearing were intact. Co-ordinated movements, such as walking, flying, 
springing, and turning, could be executed but imperfectly. After removal of 
the deepest layers, the power of executing the above-named movements was 
completely abolished. On placing the pigeon on its back, it could not get on 
its legs; at the same time it made continually the greatest exertions in its 
movements, but these were always inco-ordinated, and therefore without any 
satisfactory result. The will, intelligence, and perception remained intact; 
the animal could see and hear, and sought to avoid obstacles placed in its way. 
It gradually exhausted itself in fruitless efforts to get on its legs, and ultimately 
remained in its abnormal position, quite exhausted. Flourens concluded from 
these experiments that the cerebellum is the centre for co-ordinating voluntary 
movements. Lussana and Morganti regard the cerebellum as the seat of the 
muscular sense. 
[Extirpation in Mammals.—The dangers attending this operation are so great that but few 
animals survive. Luciani, however, by using antiseptic and other precautions, has been able to 
operate so that complete cicatrization was obtained, the animal (young bitch) being restored to 
health for a few months. The cerebellum alone was removed, but not its peduncles. As in all 
other similar operations, we must distinguish sharply the phenomena manifested during recovery 
from those after complete recovery. During the first period of six weeks, from the time of the 
operation until complete recovery, the symp- 
toms are those of injury and irritation of the 
divided peduncles, along with those resulting 
from the removal of the organ. They are 
clonic contractions of the muscles of the fore 
limb, neck, and back, passing into tonic con- 
tractions when the animal attempts to move, 
and also weakness of the hind legs, so that 
all the normal voluntary movements are in- 
terfered with, i. e., inco-ordinated, although 
these symptoms may be explained by the 
injury to adjoining parts. There was no 
sensory disturbance or loss of the muscular 
sense, although closing the eyes rendered 
standing impossible. As recovery takes place, 
these symptoms disappear, and the animal en- 
ters on the second period, where the symptoms 
depending on the actual loss of the organ are 
pronounced. The contracture and pseudo- 
paralytic weakness disappear, while there are 
alterations in the tone of the individual muscles, producing a sort of “ cerebellar ataxy.” 
Fig. 635. 
Pigeon with its cerebellum removed. 924 
FUNCTIONS OF THE CEREBELLUM. 
[Sec. 380. 
The dog could swim in quite a normal manner, its power of equilibration was not interfered 
with, but acts requiring a greater development of muscular energy could not be properly exe- 
cuted. This period lasted four to five months. After this time its health gave way, there 
was otitis, conjunctivitis, articular and cutaneous inflammations, while a peculiar form of 
marasmus set in, and the animal died after eight months. In fishes also, the removal of the 
cerebellum does not affect their power of locomotion (Bandelot).] 
Duration of the Phenomena.—After superficial lesions, or after a deep 
incision, the disturbances of co-ordination soon pass away (Flourens). If the 
injury affects the lowest third of the cerebellum, the motor disturbances remain 
permanently. Symmetrical lesions do not disturb co-ordination (Schiff). 
After removing the greater portion of the cerebellum in birds, Weir-Mitchell 
has observed that the original disturbances gradually disappear; and after 
months only slight weakness and a condition of. rapid fatigue remain. 
After ablation of the cerebellum, secondary degeneration occurs in the part of the pons 
around the pyramids, the lower olives, all the cerebellar peduncles, and the direct cerebellar 
tract, usually on the same side (Flechsig). It is found also in individual fibres in all the cranial 
nerves and the anterior roots of the spinal nerves (Marchi). 
In the dog, superficial injuries of the vermiform process, or of one-half of the organ, produce 
merely temporary disturbances; while deep injuries to the vermiform process, or removal of one 
hemisphere and a part of the vermiform process, causes permanent rigidity of the legs and shaking 
of the head; if the worm and both halves are destroyed, there follows permanent pronounced 
disturbance of co-ordination (v. Mering). According to Baginsky, destruction of a large part 
of the vermiform process alone causes in mammals permanent disturbance of co-ordination. 
Ferrier found that a vertical section of the cerebellum in monkeys produced only inconsiderable 
disturbances of equilibrium; after injury of the anterior part of the middle lobe, the animal 
often falls forward; while, when the posterior part is injured, it falls backward. After injury 
of the lateral lobe, the animal is drawn towards the affected side (Schiff\ Vulpian, Ferrier, 
Hitzig'). If the middle commissure is injured, the animal rolls violently on its long axis towards 
the injured side (Magendie). Paralysis never occurs after injuries of the cerebellum, nor is 
there ever disturbance of sensation or of the sense of touch. Luciani found that, in animals 
with the cerebellum extirpated, marasmus ultimately set in. In frogs, an important organ 
concerned with motion lies at the junction of the oblongata with the cerebellum (Eckhard). 
After it is removed the animal can no longer execute co-ordinated jumping movements, nor can 
it crawl (Goltz). 
[In man the cerebellum is connected with the maintenance of the equilibrium. There may 
be a lesion of the hemispheres without any marked symptoms ; but if the middle lobe be injured 
or pressed on by a tumor, there is usually a reeling or staggering gait, like that of a drunken 
man. Ross points out that if the tumor affect the upper part of this lobe, the tendency is to 
fall backwards, and if in the lower part, to fall forwards or to revolve round a horizontal axis. 
Vomiting is frequently persistent and well marked, while there may be nystagmus and tonic re- 
traction of the head.] 
After injuries of the cerebellum, involuntary oscillations of the eyeballs or nystagmus, as 
well as squinting (Magendie, Hertwig), have been observed; while Ferrier observed movements 
of the eyeballs after electrical stimulation. According to Curschmann, Eckhard, and Schwann, 
this occurs only when the medulla oblongata is involved ($ 379). 
Effects of Electricity and Vertigo.—If an electrical current be passed through the head, 
by placing the electrodes in the mastoid fossae behind both ears, with the + pole behind the right 
and the — pole behind the left ear, then on closing the current there is severe vertigo, and the 
head and body lean to the + pole, while the objects around seem to be displaced to the left. 
If the eyes be closed while the current is passing, the movements appear to be transferred to 
the person himself, so that he has a feeling of rotation to the left At the moment 
the head leans towards the anode, the eyes turn in that direction, and often exhibit nystagmus. 
The electrical current probably stimulates the nerves of the ampullae, as we know that affections 
of these bodies cause vertigo (§ 350). The cerebellum has no relation to the sexual activities, 
as was maintained by Gall. The contractions of the uterus observed by Valentin, Budge, and 
Spiegelberg, after stimulation of the cerebellum, are as yet unexplained. 
Pathological.—Lesions of one hemisphere may give rise to no symptoms; but if the middle 
lobe is involved, there is inco-ordination of movement, especially a tendency to fall, unsteady 
gait, and pronounced vertigo. Irritative lesions of the middle peduncle cause complete gyrating 
movements of the body around its axis, together with rotation of the eyes and head (Noth- 
nag el). Sec. 381.] 
MEMBRANES OF THE BRAIN. 
925 
381. PROTECTIVE APPARATUS OF THE BRAIN.—The Membranes.—The 
dura mater cerebralis is intimately united to the periosteum of the cavity of the skull, while 
the spinal dura mater forms around the spinal cord a freely suspended long sac, fixed only on 
its anterior surface. It is a fibrous membrane, consisting of firm bundles of connective-tissue 
intermixed with numerous elastic fibres, and provided with flattened connective-tissue corpuscles 
and Waldeyer’s plasma cells. The smooth, inner surface is covered with a layer of endothelium. 
It is but slightly supplied with blood-vessels, although they are more numerous in the outer 
layers; the lymphatics are numerous, while nerves whose terminations are unknown give to the 
dura its exquisite sensibility to painful operations on it. Pacinian corpuscles have been found 
in the dura over the temporal bone. The lymphatic subdural space (Key and Retzius) lies 
between the dura and the arachnoid, and between the pia and arachnoid is the subarachnoid 
space (fig. 636). These two spaces do not communicate directly. The delicate arachnoid, 
thin and partially perforated, poor in blood-vessels and without nerves, is covered on both sur- 
faces with squamous endothelium. Only on the spinal cord is it separated from the pia, so that 
between the two lies the lymphatic subarachnoid space; over the brain, the two membranes are 
for the most part united together, except the parts bridging over the sulci between adjacent con- 
volutions. The arachnoid passes from convolution to convolution without dipping into the sulci, 
while the pia dips into each sulcus (fig. 636, a). The ventricles of the brain communi- 
cate freely with the lymphatic subarachnoid space, but not with the subdural space. The 
pia consists of delicate bundles of connective tissue without any admixture of elastic fibres; it 
is richly supplied with blood-vessels and lymphatics, and carries nerves which accompany the 
blood-vessels into the substance of the brain. The lymphatics open into the subarachnoid 
space (§ 196). 
Subarachnoid Fluid, or cerebro-spinal fluid, lies in the subarachnoid space, which is 
traversed by trabeculae of connective tissue. Within the brain are a series of cavities called 
ventricles, which communicate one with another in a definite way. The fourth ventricle is 
lined by a layer of columnar epithelium, and covered in dorsally by a membrane and continua- 
tion of the pia mater, from the middle of which there hangs into the roof of the fourth ventricle 
two vascular processes composed of capillaries—the choroid plexuses of the fourth ventricle, 
which are comparable to the larger plexuses of the lateral ventricles. In this membrane is the 
foramen of Magendie and two other smaller foramina, whereby the fluid in the subarachnoid 
space communicates with that in the fourth ventricle; but the lymphatics of the nerve-sheaths 
can be injected from the subarachnoid space, so that there is direct continuity of the fluid in 
the ventricles of the brain with that in the subarachnoid space, perivascular spaces of the 
cerebral substance, and the perineural lymphatics of nerves. The average quantity is about 2 
ounces, and if it be suddenly with- 
drawn epilepsy or convulsions may 
be produced ; or, if it be rapidly 
increased in amount, coma may be 
produced. The base of the mid- 
dle and posterior parts of the brain 
and the medulla oblongata do not 
rest directly on bone, but are sepa- 
rated by a distinct interval from 
their osseous case, an interval occu- 
pied by the cerebro-spinal fluid 
and traversed by trabeculae, so that 
as Hilton expresses it, this fluid 
forms a perfect water-bed for those 
parts, being sustained by the 
venous circulation and the elastic- 
ity of the dura. It has important 
mechanical functions, protecting 
delicate parts of the brain from 
injury; by distributing vibratory 
impulses it insulates the nerve- 
roots, and has important relations 
to the quantity of blood in the 
brain and the cerebral circulation 
(Chemical Composition, $ 198).] 
[Spina bifida.—Sometimes the 
laminse of the vertebra; in the lumbar or other region of the spinal column are imperfectly 
developed, in which case the membranes project through as a tumor distended by cerebro- 
spinal fluid and covered by skin. The effects of rapid tapping or compressing the sac are 
readily studied in such cases.] 
Fig. 636. 
Vertical section of the cortex cerebri and its membranes; 
X co, cortex cerebri; p, intima pise dipping into the 
sulci; a, arachnoid, connected with p by means of the 
loose subarachnoid trabeculae in the subarachnoid space, 
sa ; v, v, blood-vessels; d, dura; sd, subdural space. 926 
MOVEMENTS OF THE BRAIN. 
[Sec. 381. 
The Pacchionian bodies, or granulations, are connective-tissue villi, which serve for the 
outflow of lymph from the subdural and subarachnoid spaces into the sinuses of the dura mater, 
especially the longitudinal sinus. The subarachnoid space also communicates with the spaces in 
the spongy bone of the skull, and with the veins of the skull and surface of the face (Kollmann). 
The subdural space also communicates with the lymphatic spaces in the dura, while the latter 
communicate directly with the veins of the dura. Both the subdural and subarachnoid lym- 
phatic spaces communicate with the lymphatics of the nasal mucous membrane. The space out- 
side the dura of the spinal cord is called the epidural space, and may be regarded as lymphatic 
in its nature; the pleural and peritoneal cavities may be filled from it; but it does not commu- 
nicate with the cavity of the skull. The plexuses of blood-vessels are surrounded by unde- 
veloped connective-tissue. The telse choroideae in the new-born are still covered with ciliated 
epithelium. 
Movements of the Brain.—The pulsations of the large basal cerebral 
vessels communicate their pulsatile movements (§ 79, 6) to the brain—the 
respiratory movements also affect it, so that the brain rises during expiration 
and sinks during inspiration. Lastly, there are slight alternating vascular ele- 
vations and depressions, occurring 2 to 6 times per minute, due to the periodic 
dilatation and contraction of the blood-vessels (§ 371). Psychical excitement 
influences these, and they are most regular during sleep. The movements are 
best seen especially where the membranes of the brain offer little resistance, 
e. g., over the fontanelles in children, and where the membranes have been 
exposed by trephining. The presence of the cerebro-spinal fluid is most im- 
portant for the occurrence of these movements, as it propagates the pressure 
uniformly, so that every systolic and expiratory dilatation of the blood-vessels 
is concentrated upon those parts of the cerebral membrane which do not offer 
any resistance (Bonders). When the fluid escapes, the movements may almost 
disappear. 
[Methods.—The following methods have been used by different observers in studying the 
cerebral circulation: (1) Inspection of the pia mater {Halier'), and the modification of this 
method by Donders, who trephined the skull, and inserted a glass plate in the aperture. (2) 
Over the fontanelles of children, or in cases of imperfect ossification of the skull bones, other 
observers have applied a receiving Marey’s tambour, and thus recorded the movements of the 
brain synchronous with respiration and heart-beat (Mosso). (3) In the adult a hole is trephined 
in the skull, and a modified cannula inserted, and the movements of the brain recorded by means 
of a Marey’s tambour (Fredericq). (4) Measuring the outflow of blood from a cerebral vein. 
(5) Measuring simultaneously the blood-pressure in the cerebral end of the divided internal 
carotid artery, and in a systemic artery {Franck). (6) A plethysmographic method was used 
by Roy and Sherrington. A trepan hole is made in the skull, and the dura mater divided, and 
into the hole in the skull is fixed a metallic capsule, closed below by a flexible membrane, which 
rests on the surface of the brain, and follows its movements. The upper end of the capsule is 
connected with a recording apparatus, similar to that used for recording the volume of the 
kidney, or for studying the pulse-wave, in fact a kind of oncograph (p. 546). This method 
registers the variations in the vertical thickness of the cerebral hemisphere. At the same time 
it is most important to estimate the blood-pressure in a large vein and a systemic artery.] 
[Stimulation of the central end of the sciatic nerve, and other sensory nerves, causes expansion 
of the brain, which is due to the rise of pressure in the systematic arteries, so that the expansion 
is due to the passive distention of the cerebral vessels as a result of the rise in the systemic 
blood-pressure.] 
[Asphyxia also causes a great expansion of the brain, which is partly due to 
the passive distention of the cerebral vessels following on the rise of pressure 
in the systemic vessels, but partly also to active expansion of the cerebral ves- 
sels. Muscular movements also increase the cerebral congestion. The brain- 
curves exhibit Traube-Hering undulations under certain conditions. Chloral 
hydrate causes contraction of the brain, unaccompanied by any corresponding 
fall in the arterial blood-pressure. Chloroform causes marked cerebral contrac- 
tion. Ether causes expansion, and strychnin an enormous expansion. Intra- Sec. 381.] 
BLOOD-VESSELS OF THE BRAIN. 
927 
venous injection of dilute acids produces great and immediate expansion of the 
brain, but there is no rise of pressure in the systemic arteries to account for the 
cerebral congestion ; alkalies diminish the volume of the brain. As a result of 
these and other experiments, it seems that the blood-supply to the brain varies 
directly with the blood-pressure in the systemic arteries. Roy and Sherrington, 
however, have found no evidence of the existence of vaso-motor nerves for the 
brain in the neck, or outside the cerebro-spinal canal, or indeed in the medulla 
or cord. If there are vaso-motor fibres directly regulating the calibre of the 
vessels of the pia mater, there must be some other explanation of the adapta- 
tion of the state of the cerebral blood-vessel to the needs of the brain. Roy 
and Sherrington are inclined to think that the chemical products of cerebral 
metabolism can cause variations of the cerebral vessels, and thus the brain pos- 
sesses an intrinsic mechanism by which its vascular supply can be varied 
locally in correspondence with local variations of functional activity, and this 
independent of the existence of vaso-motor nerve-fibres acting directly on the 
cerebral vessels, as is the case in other regions of the body.] 
Mental excitement increases the pulsations of the brain. At the moment of awaking, the 
amount of blood in the brain diminishes; sensory stimuli applied during sleep, so that the 
sleeper does not awake, increase the amount of blood. As the arteries within the rigid skull- 
case change their volume with each pulse-beat, the veins (sinuses) exhibit at every beat a 
pulsatile variation in volume, the opposite of that occurring in the arteries (Mosso). 
The Cerebral Blood-Vessels.—The blood-vessels of the pia are said to be regulated by the 
vaso-motor nerves (§ 356, A, 3), and their calibre may also be influenced by the stimulation of 
more distant parts of the body (§ 347). Donders trephined the skull so as to make a round 
hole, and filled it with a piece of glass, so that with a microscope he could observe changes in 
the calibre of the blood-vessels. Paralysis of the vaso-motor nerves and narcotics dilate the 
blood-vessels; they become greatly contracted at death (§ 373, I). The blood-vessels are 
dilated during cerebral activity (% 100, A), as well as during sleep. Increased pressure within 
the skull causes great derangement of the cerebral activity—labored respiration ($ 368, B), 
unconsciousness even to coma, and paralytic phenomena—all of which may in part be referable 
to disturbances of the circulation. If all the cranial arteries be ligatured suddenly, there is 
immediate loss of consciousness, together with strong stimulation of the medulla oblongata and 
its centres, and death takes place rapidly, with convulsions (compare $ 373). 
By the free anastomosis which takes place at the base of the brain, forming the circle of 
Willis (fig. 637), the individual parts of the brain are preserved from want of blood, when one 
or other blood-vessels is compressed or occluded. Within the brain the arteries are distributed 
as “ terminal arteries,” i. e., the terminal branches of any one artery end in their own area, and 
do not anastomose with those of adjoining areas (Cohnheim). On the other hand, the peripheral 
arteries (arteries of the corpus callosum, Sylvian fissure, and deep cerebral) which run externally 
on the brain, form free anastomoses (Tichomirow). 
[The nutrient or ganglionic arteries for the central ganglia arise in groups from the circle 
of Willis, or from the first two centimetres of its trunks. The antero-median group (1) sup- 
plies the anterior part of the head of the caudate nucleus. The postero-median group (2) 
enter the posterior perforated space and supply the internal surface of the optic thalami and the 
vvalls of the third ventricle. The antero-lateral groups (3, 3) from the middle cerebral enter 
the anterior perforated space, supply the corpora striata, the anterior part of the optic thalamus, 
and the internal capsule. These branches! are apt to rupture. The postero-lateral (4,4) 
supply a large part of the optic thalami (Charcot). A line drawn at a distance of two centi- 
metres outside the circle of Willis encloses the ganglionic area. The cerebral convolutions 
are supplied by the large branches of the circle of Willis. The anterior cerebral curves round 
the corpus callosum, and supplies the gyrus rectus and the supraorbital, the first and second 
frontal convolutions, the upper part of the ascending frontal, and the inner surface of the 
hemisphere as far as the quadrate lobule (fig. 637, I). The posterior cerebral goes to the 
region of the occipital lobe and the inferior aspect of the temporal lobe; the middle cerebral 
or Sylvian artery divides into four branches, which go to the posterior part of the frontal lobe, 
ascending frontal, and to all the parietal lobes, i. <?., chiefly to the motor areas (III) the angular 
gyrus, and to the first temporo-sphenoidal lobule. The terminal branches of these ganglionic 
arteries do not anastomose with the cortical system [although this seems to be subject to 
variations]. Fig. 638 shows the ganglionic arteries piercing the basal ganglia. Obviously, when 
hemorrhage of the lenticulo-striate artery or “artery of hemorrhage” (4, 4) occurs, it 
will compress the lenticular nucleus, or tear it up, and may even injure the parts outside, 928 
BLOOD-VESSELS OF THE BRAIN. 
[Sec. 381. 
such as the external capsule, claustrum (T), and island of Reil (R), or those inside, e. g., 
the internal capsule.] 
[Thus the anterior cerebral 
supplies the prefrontal area and 
a small part of the motor area, 
that for the leg-centre in the 
paracentral lobule and upper 
end of the ascending frontal 
(and perhaps that for the 
trunk). The posterior cere- 
bral supplies the centre for 
vision, and that connected with 
the course of the posterior part 
of the optic expansion, and also 
the sensory part of the inter- 
nal capsule. The middle 
cerebral supplies the motor 
areas of the cortex, except part 
of the leg-centre and the basal 
ganglia, the auditory centre, 
and that for speech.] 
[The cerebral circulation 
has many peculiarities. For its 
size, the percentage of blood in 
the brain at any one time is 
small. In the rabbit it is only 
i per cent, of the total volume 
of blood of the body, and not 
more than 5 per cent, of the 
total weight of the brain itself, 
thus forming a sharp contrast to 
the liver and kidney as regards 
blood-supply. The curves on 
the arteries serve to modify the 
effect of the cardiac shock, the 
circle of Willis permits within 
limits a free circulation; but, in 
as far as the skull is largely a 
rigid box, it was at one time 
taught that, as the brain sub- 
stance and its fluids were prac- 
tically incompressible, it was im- 
possible to alter the amount of blood in the brain. This is a mistake. The amount of blood 
undergoes an alteration in this way, that when more blood passes in, some cerebro-spinal fluid 
moves out, and vice versa, so that there is an intimate relation between these fluids. The sinuses 
form reservoirs for blood, and have much to do with the adjustment of the relative quantities of 
blood in the cerebral arteries and veins. They are easily filled, and more easily emptied, to 
permit of more arterial blood being supplied to the brain. In the developing skull, the cerebro- 
spinal fluid may accumulate in large amount within the ventricles, and greatly distend both them 
and the yielding skull-case from internal pressure, as in acute hydrocephalus. The peculi- 
arities and independence of the cortical and ganglionic arteries have already been referred to. 
Plugging by means of a clot, vegetation, or wart, carried from the heart, is common in the left 
middle cerebral artery. Why ? When the plug is washed away by the blood-stream, owing to 
the left carotid springing from the aorta nearly in line with the blood-current, the plug readily 
passes into the left carotid and so into the left middle cerebral which is in line with the internal 
carotid. In such a case the convolutions and parts supplied by it are suddenly deprived of 
blood, with immediate and serious results.] 
[The venous circulation is peculiar. The sinuses are really spaces between the layers of 
the tough dura mater, and partly bounded by bone. The blood moves in the longitudinal sinus 
from before backwards, but most of the cortical veins open into it in a forward direction, so 
that their stream is opposed to that in the sinus. Thus, the blood which enters the brain by 
ascending arteries reaches the sinuses by ascending veins, the reverse of what obtains elsewhere, 
in parts where ascending veins convey blood from descending arteries, whereby the hydrostatic 
pressure and gravity aid the circulation, but here gravitation is opposed to the flow of blood in 
the cerebral veins. This will help to explain the occurrence of thrombosis in these vessels. 
Fig. 637. 
Arteries of the base of the brain, or circle of Willis. C, C, 
internal carotids; CA, anterior cerebral; S, S, Sylvian 
arteries; V, V, vertebrals; B, basilar; CP, posterior cere- 
brals; i, 2, 3, 3, 4, 4, groups of nutrient arteries. The 
dotted line shows the limit of the ganglionic area. Sec. 381.] 
CRANIAL CIRCULATION. 
929 
Some of the veins on the surface communicate with intracranial veins, eg., those of the nose, 
the facial through the ophthalmic, mastoid veins and veins of the diploe. Hence, morbid 
processes affecting the scalp (erysipelas), ear (caries), or face (carbuncle) may readily affect 
intracranial structures (Gowers).] 
If a person who has been in bed for a long time, and whose blood is small in amount, be 
suddenly raised into the erect position, cerebral anaemia is not unfrequently produced, owing to 
hydrostatic causes. At the same time, there may be loss of consciousness and impairment of 
the senses. Liebermeister regards the thyroid gland as a collateral blood-reservoir which 
empties its blood towards the bead during such changes of the position of the body. Perhaps 
this may explain the swelling of the thyroid as a compensatory act, when the heart beats 
violently, and the brain is surcharged with blood (|| 103, III, and 371). Very violent muscular 
exertion, as well as marked activity of other organs, causes a very considerable fall of the 
blood-pressure in the carotid. 
Pressure on the Brain.—The brain and the fluid surrounding it are constantly subjected to 
a certain mean pressure, which must ultimately depend upon the blood-pressure within the 
vascular system. The investigations of Naunyn and Schreiber on the cerebral pressure (or 
Fig. 638. 
Transverse section of the cerebrum behind the optic chiasma. Arteries of the corpus striatum. 
C h, optic chiasma; B, section of optic tract; L, lenticular nucleus; I, internal capsule; 
C, caudate nucleus; E, external capsule; T, claustrum; R, convolutions of the island of 
Reil; V, V, section of the lateral ventricles ; P, P, pillars of the fornix; O, gray substance 
of the third ventricle. Vascular areas—I, anterior cerebral artery; II, Sylvian artery; 
III, posterior cerebral artery; I, internal carotid; 2, Sylvian, 3, anterior cerebral artery; 
4, 4, lenticulo-striate arteries; 5, 5, lenticular arteries. 
cerebro-spinal pressure) showed that the pressure must be slightly less than the pressure 
within the carotid, before the symptoms proper to pressure on the brain occur. These are, 
sudden attacks of headache, with vertigo, or it may be loss of consciousness, vomiting, slowing 
of the pulse, slow and shallow respiration, convulsions—while the pressure of the cerebro- 
spinal fluid is increased. The cause of these phenomena lies in the anaemia of the brain. If 
the pressure is moderate, the above named symptoms may remain latent; nevertheless, disturb- 
ances of the nutrition of the brain occur, with consecutive phenomena, such as persistent slight 
headache, feeling of vertigo, muscular weakness, and disturbances of vision (owing to neuro- 
retinitis with choked disc). Increase of the blood-pressure diminishes the symptoms, while 
diminution of the blood-pressure causes more pronounced phenomena of cerebro-spinal pressure. 
In the dog, pain begins with a pressure of 70 to 80 mm. Hg. Consciousness is abolished when 
the pressure is higher, and at 80 to 100 mm. spasms take place. A pressure of 100 to 120 mm. 
causes slowing of the pulse, owing to stimulation of the vagus at its origin; the respirations 
are temporarily accelerated, and then diminish. Long-continued severe compression always, 
sooner or later, ends fatally. The blood-pressure at first is increased, owing to reflex stimula- 
tion of the vaso motor centre from the pressure stimulating the sensory nerves; ultimately, the 
blood-pressure falls, and the pulse becomes very slow. Irregular variations in the blood-pressure 
point to a direct central stimulation of the vaso-motor centre by pressure. The application of 930 
COMPARATIVE AND HISTORICAL. 
[Sec. 382. 
continued slowly increasing pressure compresses the brain . At the level of the 
cauda equina the pressure of the subarachnoid fluid — 7.5-12 mm. Hg in the dog (Naunyn). 
382. COMPARATIVE—HISTORICAL.—Comparative.—Nerves are absent in the 
protozoa. Neuro muscular cells occur in the ccelenterata, ih the hydroida and medusae, and 
they are the first indications of a nervous apparatus ($ 296). The umbrella of the medusa is 
covered with a plexus of nerve-fibrils, which at various parts along its margin is provided with 
small cellular thickenings corresponding to ganglia, and from these nerve-fibres proceed to the 
sense organs. Many of the worms possess a nervous ring in the cephalic portion, and in those 
provided with an intestine a single or double nervous cord, in the form of a ring, surrounds the 
pharynx. Branches (often two) pass from this into the elongated body, and usually these carry 
ganglia corresponding to each ring of the body of the animal. In the leech, only one gangliated 
cord is present. In the echinodermata, a large nerve-ring surrounds the mouth; and from it 
large nerves proceed, corresponding to the chief trunks of the water-vascular system. At the 
points where the nerves are given off, the nervous ring is provided with the so called “ ambulacral 
brains.” The arthropoda are provided with a large cephalic ganglion placed above the pharynx, 
from which nerves pass to the sense organs. Another ganglion lies on the under surface of the 
pharynx, and is connected with the former by commissures. The pharynx is thus embraced by 
a gangliated ring, and from it proceeds the abdominal gangliated double chain, along the ventral 
surface of the body, through the thorax and abdomen. Sometimes several ganglia unite to form 
a large compound ganglion, while, in other cases, each segment of the body contains its own 
ganglia. In the mollusca, the oesophageal nervous ring is present, although the ganglionic 
masses vary much in position within it. A number of compound ganglia lie scattered in different 
parts of the body, and are united by nerves to the former. They represent the sympathetic 
system. In the cephalopoda, the oesophageal ring has almost no commissure, and a part of 
the ganglionic matter is enclosed in a cartilaginous capsule, and is o'ten spoken of as a “ brain.” 
Additional ganglia are found in the mantle, heart, and stomach. In vertebrates, the nervous 
system invariably lies on the dorsal aspect of the body. In the amphioxus, there is no separation 
into brain and spinal cord. (See §§ 374 and 375.) 
Historical.—Alkmaon (580 b.c.) placed the seat of consciousness in the brain; Galen (131- 
203 a.d.) regarded it as the seat of the impulses for voluntary movements. Aristotle (384 B.c.) 
ascribed the relatively largest brain to man; he stated that it was inexcitable to stimuli (insen- 
sible). One of the functions he ascribed to the brain was to cool the heat ascending from the 
heart. Herophilus (300 B.c.) gave the name calamus scriptorius; and he regarded the 4th ven- 
tricle as the most important organ for the maintenance of life. Even in Homer there are repeated 
references to the dangers of injuries of the neck. Aretseus and Cassius Felix (97 a.d.) were 
aware of the fact that lesion of one cerebral hemisphere caused paralysis on the opposite side of 
the body. Galen was acquainted with the path in the spinal cord connected with movement and 
sensation. Vesalius (1540) described the five ventricles of the brain. R. Colombo (1559) 
observed the movements of the brain isochronous with the action of the heart. A more careful 
description of these movements was given by Riolan (1618). Coiter (1573) discovered that an 
animal can live after removal of its cerebrum. About the middle of the 17th century, Wepfer 
discovered the hemorrhagic nature of apoplexy. Schneider (1660) estimated the weight of the 
brain in different animals. Mistichelli (1709) and Petit (1710) described the decussation of the 
fibres of the spinal cord below the pons. Gall discovered the partial origin of the optic nerve 
from the anterior pair of the corpora quadrigemina, and by dissecting the brain from below, he 
attempted to trace the course of the nerve-fibres to the convolutions (1810). Rolando described 
more accurately the form of the gray matter of the spinal cord. Cams (1814) discovered the 
central canal. The most compendious work on the brain was written by Burdach (1819-1826). 
The more recent observations are referred to in the text. Physiology of the Sense Organs. 
383. INTRODUCTORY OBSERVATIONS.—Requisite Condi- 
tions.—The sense organs have the function of transferring to the sensorium 
impressions of the various phenomena of the external world; they are, in fact, 
the intermediate instruments of sensory perceptions. In order that this may 
occur, the following conditions must be fulfilled: (1) The sense organ, pro- 
vided with its specific end-organ, must be anatomically perfect, and capable 
of acting physiologically. (2) A “specific stimulus” must be present, 
which under normal conditions acts upon the end-organ. (3) The sense organ 
must be connected with the cerebrum by means of a nerve, and the conduction 
through this path must be uninterrupted. (4) During the act of stimulation, 
the psychical activity (attention) must be directed to the process, and then the 
sensation results, e. g., of light or sound, through the sense organ. (5) 
Lastly, when, by a psychical act, the sensation is referred to the external cause, 
then there is a conscious sensory perception. Often, however, this relation is 
completed as an unconscious conclusion, as it is essentially a deduction from 
previous experience. 
Stimuli.—With regard to the stimuli which are applied to the sensory apparatus, we dis- 
tinguish : (1) Adequate or homologous stimuli, i. e., stimuli for whose action the sense 
organs are specially adapted, such as the rods and cones of the retina for the vibrations of the 
ether. Thus, each sense organ has a specific form of stimulus best adapted to act upon it. This 
is what Johannes Muller called the “ law of specific energy.” (2) There are many other 
forms of stimuli (mechanical, thermal, chemical, electrical, internal somatic) which act upon the 
sense organs, producing the flash of light beheld when the eye is struck; singing in the ears 
when there is congestion of the head. These heterologous stimuli act upon the nervous ele- 
ments of the sensory apparatus along their entire course, from the end-organ to the cortex cerebri. 
The homologous stimuli, on the other hand, act only on the end organ, i. e., light has no effect 
whatever upon the trunk of the exposed optic nerve. 
Liminal Intensity.—Homologous stimuli act upon the sensory organs 
only within certain limits as to strength. Very feeble .stimuli at first produce 
no effect. That strength of stimulus which is just sufficient to cause the first 
trace of a sensation is called by Fechner the “liminal intensity” of the 
sensation. As the strength of the stimulus increases, so also do the sensations, 
but the sensations increase equally when the strength of the stimulus increases 
in relative proportions. Thus, we have the same sensation of equal increase 
of light when, instead of 10 candles, n, or instead of 100 candles, no are 
lighted—the proportion of increase in both cases is equal to one-tenth. As the 
logarithm of the numbers increases in an equal degree, when the numbers 
increase in the same relative proportion, the law may be expressed thus: “The 
sensations do not increase with the absolute strength of the stimuli, but nearly 
as the logarithm of the strength of the stimulus.” This is Fechner's “ psycho- 
physical law,” but its accuracy has recently been challenged by E. Hering. 
[It holds good only with regard to stimuli of medium strength.] If the specific 
stimulus be too intense, it gives rise to peculiar painful sensations, e. g., a feeling 
of blindness or deafness, as the case may be. The sense organs respond to 
adequate stimuli, but only within certain limits of the stimulus, e. g., the ear 
responds only to vibrating bodies emitting a certain range of vibrations per FECHNEIi’s LAW. 
[Sec. 383. 
second ; the retina responds only to the vibrations of the ether between red and 
violet, but not to the so-called heat vibrations or to the chemically active 
vibrations. 
[It was Weber who worked out the relation between the intensity of stimuli and the changes 
in the quantity of the resulting sensations. He used the method of “ least observable differ- 
ences,” as applied to sensations of pressure and the measurements of lines by the eye. Hence, 
it is called Weber’s Law ; but Fechner expanded it and assumed that all just observable differ- 
ences are equally great, and so the law is sometimes called by his name.] 
[Fechner’s Law.—Expressed in another way, the result depends on (1) 
the strength of the stimulus, and (2) the degree of excitability. Supposing 
the latter to be constant, while the former is varied, it is found that if the 
stimulus be doubled, tripled, or quadrupled, the sensation increases only as the 
logarithm of the stimulus.] 
[Suppose the stimulus to be increased 10, 100, or 1000 times, then the sensation increases 
only as 1,2, or 3. Just as there is a lower limit of excitation liminal intensity [or threshold), so 
there is an upper limit or maximum of excitation or height of sensibility, when any further 
increase produces no appreciable increase in the sensation. Thus, we do not notice any differ- 
ence between the central and peripheral portion of the sun’s disc, though the difference of light 
intensity is enormous [Sully). Between these two is the range of sensibility ( Wundt). There 
is always a constant ratio between the strength of the stimulus and the intensity of the sensa- 
tion. The stronger the stimulus already applied, the stronger must be the increase of the 
stimulus in order to cause a perceptible increase of the sensation (Weber’s Law). The neces- 
sary increment is proportional to the intensity of the stimulus, and it varies for each sense organ. 
If a weight of 10 grams be placed in the hand, it is found that 3.3 grams must be added or 
removed before a difference in the sensation is perceptible; if 100 grams are held, 33.3 grams 
must be added or removed to obtain a perceptible difference in the sensation. The magnitude 
of the fraction indicating the increment of stimulus necessary to obtain a perceptible difference 
of the sensation, is spoken of as the constant proportion or the discriminative sensibility. 
In the above case it is 1 : 3. The following table gives approximately the constant propor- 
tion for each sense :— 
Tactile Sensation, . .1:3.^ 
Thermal “ . .1:3.^ 
Auditory “ . • 1 : 3* Vi 
Muscular Sensation, . 6 : ioo. T$<y 
Visual “ . I : ioo. 
[The application of the law to temperature sensations is beset with great difficulties, while 
for taste and smell we do not know that it is really applicable. From an experimental point 
of view, it cannot be said to be proved, and its application is obviously somewhat restricted to 
certain sensations, and to these only within a certain range. It certainly does not hold good 
for sensations of pressure, and muscular sense, near the lower limits for these senses. “ At 
best it is only an approximately correct statement of what holds true of the relative intensity of 
certain sensations of light and hearing, and less exactly of pressure and the muscular sense, 
when these sensations are of moderate strength ” [Ladd).'] 
The term after-sensation is applied to the following phenomenon, viz., 
that, as a rule, the sensation lasts longer than the stimulus producing it; thus, 
there is an after-sensation after pressure is applied to the skin. Subjective 
sensations occur when stimuli due to internal somatic causes excite the 
nervous apparatus of the sense organ. The highest degrees of these, depend- 
ing mostly upon pathological stimulation of the sensory cortical centres, are 
characterized as hallucinations, e.g., when a delirious person imagines he 
sees figures or hears sounds which have no objective reality. In opposition to 
this condition the term illusion is applied to modifications by the sensorium 
of sensations actually caused by external objects, e.g., when the rolling of a 
wagon is mistaken for thunder. 
In a new-born child the sense of touch is strongly developed, that of pain slightly; muscular 
sensations are undoubtedly present, while smell and taste are frequently confounded. Auditory 
stimuli are heard from the second day onwards, the stimulus of light immediately afterbirth, but a 
peirpheral field of vision does not yet exist (Cuignet). Towards the fourth to fifth week, the 
movements of convergence and accommodation are noticeable, while after four months colors 
are distinguished. The various stimuli are not perceived simultaneously—a reflex inhibitory 
centre is not yet developed (Genzmer). Sec. 384.] 
THE EYE. 
933 
The Visual Apparatus—The Eye. 
384. HISTOLOGICAL OBSERVATIONS.—In the following re- 
marks it is assumed that the student is familiar with the anatomical structure 
of the eye :— 
The cornea, for the sake of simplicity, is regarded as uniformly spherical, although, properly 
speaking, it differs slightly from this form. It is more like a vertical section of a somewhat 
oblate ellipsoid, which we must suppose to be formed by rotating an ellipse around its long axis. 
It is nearly of uniform thickness throughout, only in the infant it is slightly thicker in the centre, 
and in the adult slightly thinner. 
The cornea consists of the following layers :— 
[1. Anterior stratified epithelium. 
2. Anterior elastic lamina. 
3. Substantia propria. 
4. Posterior elastic lamina. 
5. Single layer of epithelium.] 
1. The anterior epithelium, stratified and nucleated, consists of many 
layers of cells (fig. 641, a). The deepest cells are more or less columnar, are 
Fig. 639.—Cornea of the frog treated with chloride of gold, showing the corneal corpuscles 
stained, and a few nerve-fibrils. Fig. 640.—Cornea of the frog treated with silver nitrate; 
the ground substance is stained, while the spaces for the corneal corpuscles are left 
unstained. 
Fig. 639. 
Fig. 640. 
arranged side by side, and are called supporting cells. [Frequently nuclei 
divided by mitosis are to be seen, so that new cells are produced by prolifera- 
tion of the deepest cells.] The cells of the middle layers are more arched, 
and dip with finger-shaped processes into corresponding spaces between their 
neighbors. The most superficial cells are flat, perfectly smooth, hard, keratin- 
containing squamous epithelium [and in many respects resemble the squames 
of the mouth]. 
2. The epithelial layer rests upon the anterior elastic membrane (Bow- 
man’s elastic lamina), a structureless, clear, basement-like membrane In 
man it is about io /< in thickness, but its thickness varies with the animal 
investigated. 934 
THE CORNEA. 
[Sec. 384. 
3. The substantia propria of the cornea consists of (chondrin-yielding) 
fibres composed of delicate fibrils of connective-tissue. The fibres are arranged 
in mat-like thin lamellae (/), more or less united together, and are placed in 
layers over each other. Towards the anterior elastic lamina, the fibres bend 
round and perforate the superficial lamellae, thus serving as supporting fibres. 
[These perforating fibres are comparable to Sharpey’s fibres in bone.] Between 
the lamellae are a series of inter-communicating spaces lined with endothelium. 
Fig. 641. 
Anteroposterior section at the junction of the cornea with the sclerotic, a, anterior corneal 
epithelium; b, Bowman’s lamina; c, corneal corpuscles; /, corneal lamellae (the whole 
thickness lying between b and d is the substantia propria corneae); d, Descemet’s mem- 
brane; <?, its epithelium; f junction of cornea with the sclerotic; g, limbus conjunctivas; 
h, conjunctiva; i, canal of Schlemm ; k, Leber’s venous plexus (is regarded by Leber as 
belonging to i); m, m, meshes in the tissue of the lig. iridis pectinatum; n, attachment 
of the iris; o, longitudinal, p, circular (divided transversely) bundles of fibres of the 
sclerotic; q, perichoroidal space; s, meridional [radiating], /, equatorial (circular) bundles 
of the ciliary muscle; u, transverse section of a ciliary artery; v, epithelium of the iris (a 
continuation of that on the posterior surface of the cornea); w, substance of the iris; 
x, pigment of the iris; z, a ciliary process. 
These spaces are really lymph-spaces, and they communicate with the lym- 
phatics of the conjunctiva. The fixed corneal corpuscles lie in these 
spaces (V), and are provided with numerous processes, which anastomose with 
the processes of corpuscles lying between the lamellae above and below, and 
on either side of them. Kiihne observed that stimulation of the corneal nerves Sec. 384.] 
THE CORNEA. 
935 
was followed by contraction of these cells (§ 201, 7), while Kiihne and Wal- 
deyer maintain that they are connected with the corneal nerve-fibrils. 
[The corneal corpuscles are looked upon as branched connective-tissue 
corpuscles lying in and not quite filling the branched spaces between the 
lamellae. The processes anastomose freely with similar cells in the same plane, 
and to a less extent with the processes of cells in planes immediately above and 
below them. In a section stained with gold chloride, they present the appear- 
ance seen in fig. 639. In a vertical section of the cornea they appear fusiform 
and parallel to the free surface of the cornea (fig. 641). If the cornea of a 
frog be pencilled with silver, cell-spaces remain clear, as in fig. 640. The one 
figure represents, as it were, the nitrate, the cement-substance between the 
lamellae is blackened, and the branched positive, and the other the negative 
image.] Leucocytes also pass into these lymph-spaces, or juice-canals. The 
importance of these leucocytes in inflammation is referred to in § 200. 
[The lamellae of the cornea in the Rays are traversed by “ sutural fibres ” which pass at 
right angles to the plane of the lamellae from the anterior elastic lamina to Descemet’s membrane 
(Ranvier).~] 
4. The transparent, structureless, posterior elastic membrane (d), the 
membrane of Descemet or Demours, is in many animals fibrillated, and shows 
evidence of stratification, while towards the margin of the cornea there are 
occasionally slight conical elevations. This membrane is very tough and very 
resistant (of great importance in inflammation). If it be removed, it rolls up 
towards the convex side. At its periphery it becomes continuous with the 
fibro-elastic reticulated ligamentum pectinatum iridis, whose trabeculae are 
covered by epithelium. 
5. The posterior single layer of epithelium consists of flat, delicate, 
nucleated cells (e), which are continued from the margin of the cornea on to 
the anterior surface of the iris (v). Fine juice-canals exist in the spaces be- 
tween the individual cells 
(v. Recklinghausen'). 
These spaces communi- 
cate with a system of fine 
tubes under the epithe- 
lium, perforate Desce- 
met’s membrane, and 
thus communicate with 
the corneal spaces. 
[Bowman’s tubes are 
artificial productions, formed 
by forcing air or a colored fluid 
between the lamellae, when it 
passes between the bundles of 
fibrils, forming a series of tubes 
with dilatations on them and 
running at right angles to one 
another between the lamellae.] 
The nerves of the 
cornea, which are de- 
rived from the long and short ciliary nerves (§ 347), are partly sensory 
in function. They enter the cornea at its margin as medullated fibres, but the 
myelin soon disappears, while the axial cylinders split up into fibrils. [The 
axial cylinders branch and form a plexus between the lamellae, especially near 
the anterior surface, the fundamental or ground plexus (fig. 642, n). 
There are triangular nuclei at the nodal points, but they probably belong to 
the sheath of flattened cells which cover the larger branches. There is a finer 
Fig. 642. 
Vertical section of the cornea stained with gold chloride, n, 
nerve-fibrils; a, perforating branch ; r, nucleus ; p, b, inter- 
epithelial termination of fibrils; s, anterior elastic lamina. 936 
THE SCLEROTIC. 
[Sec. 384. 
and denser plexus of fibrils immediately under the anterior epithelium, sub- 
epithelial plexus, which is derived from the former, the fibrils arising in 
pencils or groups (fig. 643). Some fibrils perforate the anterior elastic lamina, 
rami-perforantes, and pass between the anterior epithelial cells to form the 
intra epithelial network (fig. 642, b, ft). Some observers suppose that they 
terminate in free, pointed, or bulbous ends. There is also a fine plexus of 
fibrils in the posterior layers of the cornea, near Descemet’s membrane. It 
gives off numerous fine fibrils, which come into intimate, if not direct, ana- 
tomical relation with the corneal corpuscles. The trophic fibres of the cornea 
(§ 347) are, perhaps, those deeper branches which are connected with the 
corneal corpuscles. 
[Method.—These fibrils are best revealed by staining a cornea with chloride of gold, which 
tinges them of a purplish hue after exposure to light (Cohnheim). They are also readily stained 
by methylene blue.] 
Blood-vessels occur only in the outer margin of the cornea (fig. 645, v), 
and extend 2 mm. over the cornea above, 1.5 mm. below, and 1 mm. laterally— 
the most external capillaries form arched loops, and thus turn on themselves. 
The cornea is nourished from the blood-vessels in its margin. Opacities of the 
cornea give rise to many forms of visual defects. 
The sclerotic is a thick fibrous membrane, composed of,/, circular (equa- 
torial) and, 0, longitudinal (meridional) bundles of connective-tissue woven 
together (fig. 641). The spaces between the bundles contain colorless and 
pigmented connective-tissue corpuscles and also leucocytes. It is thickest pos- 
teriorly, thinner at the equator, while in front of this it again becomes thicker, 
owing to the insertion of the tendons of the straight muscles of the eyeball. It 
contains few blood-vessels, which form a wide-meshed capillary plexus, imme- 
diately under its deep surface. Other vessels form an arterial ring round the 
entrance of the optic nerve. It rarely is quite spherical; it rather resembles 
an ellipsoid, which we might imagine to be formed by the rotation of an 
ellipse around its short axis (short eyes) or around its long axis (long eyes). 
Above and below, the sclerotic overlaps like a fold the clear margin of the 
cornea; hence, when the cornea is viewed from before, it appears transversely 
elliptical; when seen from behind, it appears circular. Following the margin 
of the cornea, but lying still within the substance of the sclerotic, is the circu- 
lar canal of Schlemm (/), which communicates with other anastomosing 
veins, the venous plexus of Leber (k). Schwalbe and Waldeyer regard Schlemm’s 
canal as a lymphatic. Posteriorly, the sclerotic becomes continuous with the 
fibrous covering of the optic nerve derived from the dura mater. The sclerotic 
is provided with nerves, which are said to terminate in the cells of the scleral 
substance (.Helfreich). 
The tunica uvea, or the uveal tract, is composed of the choroid, the ciliary 
part of the choroid, and the iris. 
The choroid is composed of the following layers (fig. 644) : (1) Most in- 
ternally is the transparent limiting membrane, 0.7 [i in thickness, but it is 
slightly thicker anteriorly. (2) The very vascular capillary network of the 
chorio-capillaris, or membrane of Ruysch, embedded in a homogeneous 
layer. Then follows—(3) a layer of a thick elastic network, covered on both 
surfaces by endothelium (Sattler). (4) The choroid proper consists of a layer 
with pigmented connective-tissue corpuscles, together with a thick elastic net- 
work, containing the numerous venous vessels as well as the arteries. The pig- 
mented layers are known as the supra-choroidea, or lamina fusca, which 
surrounds the large lymphatic space lined with endothelium and called the 
perichoroidal space, q. In new-born infants, which, according to Aristotle, 
have the iris dark blue, the uveal tissue is devoid of pigment; in brunettes it 
is developed later, and in blondes not at all. Sec. 384.] 
THE IRIS. 
937 
In the ciliary part of the choroid, the pigmented connective-tissue cor- 
puscles are not so numerous. The ciliary muscle (tensor choroidese, or 
muscle of accommodation) is placed in this region. It arises (s) by means of 
a branched, reticulated, connective-tissue origin, from the inner side of the 
junction of the cornea and sclerotic, near the canal of Schlemm, and passes 
backwards to be inserted into the choroid. This constitutes the radiating 
fibres. Other fibres lying internal to these are arranged circularly, t, in bun- 
dles in the ciliary margin. These circular fibres are sometimes called Heinrich 
Muller’s muscle. The muscle consists of smooth muscular fibres, and is sup- 
plied by the oculomotorius (§ 345, 3). 
The iris consists of the following parts from before backwards : a layer of 
epithelial cells (v) continuous with those covering the posterior surface of the 
cornea, a layer of reticulated connective-tissue, the layer of blood-vessels, and 
lastly a posterior limiting membrane, which contains the pigmentary epithe- 
lium (.*) {Michel). In brunettes, the texture of the iris contains pigmented 
connective-tissue corpuscles. The iris in some animals is described as contain- 
Fig. 643. 
Fig. 644. 
Fig. 643.—Nerve-plexus in the cornea after gold chloride, n, nerve; a, fibrils. Fig. 644.—Ver- 
tical section of the choroid and a part of the sclerotic. (1) sclerotic; (2) lamina®supra- 
choroidea; (3) layer of large vessels; (4) limiting layer; (5) chorio-capillaris; (6) hyaline 
membrane; (7) pigment epithelium; (_§•) large blood-vessels; {/) pigment cells; (c) sections 
of capillaries. 
ing two muscles composed of smooth muscular fibres—one set constituting the 
sphincter pupillae (circular—fig. 660), which surrounds the pupil, and lies 
nearer the posterior than the anterior surface of the iris (§ 392). Its nerve of 
supply is derived from the oculomotorius (§ 345, 2). The other fibres consti- 
tute the dilator pupillae (radiating), which consists of a thinner layer of fibres 
arranged in a radiate manner. Some of the fibres reach to the margin of the 
pupil while others bend into the sphincter. [The existence of a dilator pupillse 
in man is denied (§ 392).] At the outer margin of the iris, the radial bundles 
are arranged in anastomosing arches, and form a circular muscular layer 
(.Merkel). The chief nerve of supply for the dilator fibres is the sympathetic 
(§ 347> 3)- Ganglia occur in the ciliary nerves in the choroid [and they are 
found also in the iris]. Gerlach has recently applied the term ligamentum 938 
THE CHOROID. 
[Sec. 384. 
annulare bulbi to that complex fibrous arrangement which surrounds the iris, 
and at the same time forms the point of union of the ciliary body, iris, 
ciliary muscle, sinus venosus iridis, and the line of junction of the cornea and 
sclerotic. 
The choroidal vessels are of great importance in connection with the nutri- 
tion of the eye. According to Leber, 
they are arranged as follows: The 
arteries are—i. The short poste- 
rior ciliary, which are about twenty 
in number, and perforate the sclerotic 
near the optic nerve (fig. 645, a, a). 
They terminate in the vascular net- 
work of the chorio-eapillaris (m), 
which reaches as far as the ora serrata. 
2. The long posterior ciliary; one 
of these lies on the nasal and the other 
on the temporal side, and they run (b) 
to the ciliary part of the choroid, 
where they divide dichotomously, and 
penetrate into the iris, where they 
help to form the circulus arteriosus 
iridis major (p). 3. The anterior 
ciliary (c), which arise from the mus- 
cular branches, perforate the sclerotic 
anteriorly, and give branches to the 
ciliary part of the choroid and to the 
iris. About twelve branches run 
backwards (a) from them to the chorio- 
capillaris. 
Veins of the Choroid.—1. The 
anterior ciliary veins (e) receive 
the blood from the anterior part of the 
uvea and carry it outwards. These 
branches are connected with Schlemm’s 
canal and Leber’s venous plexus. 
They do not receive any blood from 
the iris. 2. The venous plexus of 
the ciliary processes (r) receives the 
blood from the iris (y), and passes 
backwards to the choroidal veins. 3. 
The large vasa vorticosa (h) per- 
forate the sclerotic behind the equator 
of the bulb. 
The inner margin of the iris rests 
upon the anterior surface of the lens; 
the posterior chamber is small in 
adults, and in the new-born child it 
may be said scarcely to exist—it is so 
small. When Berlin blue is injected 
into the anterior chamber of the eye, 
it generally passes into the anterior 
ciliary veins {Schwalbe'). Even in 
living animals, carmine also behaves 
in a similar manner (.Heisrath) ; hence 
these observers conclude that there is a direct communication between the 
Fig. 645. 
Diagram of the blood-vessels of the eye (hori- 
• zontal view; veins black, arteries light, with 
a double contour), a, a, short posterior cili- 
ary ; b, long posterior ciliary; c, c', anterior 
ciliary artery and vein; d, d', artery and vein 
of the conjunctiva ; e, e/, central artery and 
vein of retina; f, blood-vessels of the inner, 
and g, of the outer optic sheath; h, vorticose 
vein; i, posterior short ciliary vein confined 
to the sclerotic; k, branch of the posterior 
short ciliary artery to the optic nerve; /, anas- 
tomosis of the choroidal vessels with those of 
the optic; chorio-capillaris; n, episcleral 
branches; o, recurrent choroidal artery; p, 
great circular artery of iris (transverse sec- 
tion); q, blood-vessels of the iris; r, ciliary 
process; s, branch of a vorticose vein from 
the ciliary muscle; t, branch of the anterior 
ciliary vein to the ciliary muscle ; u, circular 
vein; v, marginal loops of vessels on the 
cornea; w, anterior artery and vein of the 
conjunctiva. Sec. 384.] 
STRUCTURE OF THE RETINA. 
939 
veins and the aqueous chamber, as these substances do not diffuse through 
membranes. 
Internal to the choroid lies the single layer of hexagonal cells (0.0135 to 
0.02 mm. in breadth) filled with crystalline pigment. This layer really belongs 
to the retina. It consists of a single layer of cells as far as the ora serrata— 
it is continued on to the ciliary processes and the posterior surface of the iris, 
where it forms several layers (fig. 641, x). In albinos it is devoid of pigment; 
on the other hand, the uppermost cells, which lie on the ridges of the ciliary 
processes, are always devoid of pigment. [The processes of these cells vary in 
length with the kind of light acting on the retina (§ 398).] 
The retina externally is in contact with the layer of hexagonal pigment-cells 
(Ei), which in its development and functions really belongs to the retina. The 
cells are not flat, but they send pigmented processes into the space between the 
ends of the rods. [Du Bois states that the processes are continuous with the 
cones.] In some animals (rabbit) the cells contain fatty granules and other 
substances (p. 941). The cells are larger and darker at the ora serrata (Kiihne). 
The retina is composed of the following layers, proceeding from without 
inwards:— 
[1. Layer of pigment-cells. 
2. Rods and cones. 
3. External limiting membrane. 
4. Outer nuclear layer. 
5. Outer molecular (granular re- 
ticular or internuclear layer). 
6. Inner nuclear layer. 
7. Inner molecular (granular or 
reticular) layer. 
8. Layer of nerve-cells (gangli- 
onic) layer. 
9. Layer of nerve-fibres. 
10. Internal limiting membrane.] 
i. The hexagonal pigment-cells already described. 2. The layer of 
rods and cones (St) or neuro-epithelium of Schwalbe \bacillary layer, or 
the visual cells, or visual epithelium of Kiihne] (fig. 647). These lie externally 
next the choroid, but they are absent at the entrance of the optic nerve. Then 
follows the external limiting membrane (Le), which is perforated by the 
bases of the rods and cones. 3. The external nuclear layer (au.K) ; this 
and all the succeeding layers are called “ brain-layers ” by Schwalbe. 4. The 
external granular (au.gr), or inter-nuclear layer, which is perforated by the 
fibres which proceed inwards from the nuclei of 3 to reach 5, the nuclei of the 
internal nuclear layer (inK). The nuclei of this layer, which are con- 
nected by fibres with the rods and cones, are marked by transverse lines in the 
macula lutea (Krause, Denissenko). [The so-called nuclei of the internal nu- 
clear layer are not all of the same nature. The innermost layer consists of 
branched multipolar nerve-cells, so-called “ spongio-blasts,” and from many, 
but not all of them, an axis-cylinder process proceeds to the optic nerve-fibre 
layer. The other nuclei chiefly belong to bipolar nerve-cells, which send off a 
central process which breaks up into fine branches in the internal reticular 
layer, while a peripheral process breaks up in the external reticular layer. These 
are also the nuclei of the radiating fibres of Muller.] 6. The finely granular 
internal granular layer (in.gr), [called also neuro-spongium] through which 
the fibres proceeding from the inner nuclear layer cannot be traced. It would 
seem as if these fibres break up into the finest fibrils, into which also the 
branched processes of the ganglionic cells of 7, the ganglionic layer, extend. 
[The cells are nervous ganglionic cells, arranged in a single layer, and they con- 
tain no pigment. Each cell gives off centrally an unbranched axis-cylinder 
process which becomes continuous with a fibre of the optic nerve, and several 
branched protoplasmic processes which run peripherally and form numerous 
branches in the inner reticular layer. According to v. Vintschgau, the pro- 940 
STRUCTURE OF THE RETINA. 
[Sec. 384. 
cesses of the ganglionic cells are connected with the fibres. 8. The next, or 
fibrous layer, consists of the fibres of the optic nerve (o) and most inter- 
nally is the internal limiting membrane (Li). The fibres of the optic 
nerve are devoid of myelin and arranged in bundles which radiate from the 
entrance of the optic nerve toward the ora serrata]. According to W. Krause, 
there are 400,000 broad, and as many narrow, optic fibres, so that for every 
fibre there are 7 cones, about 100 rods, and 7 pigment-cells. The optic fibres 
are absent from the macula lutea, where, how- 
ever, there are numerous ganglionic cells. Be- 
tween the two homogeneous limiting membranes 
Fig. 646. 
Fig. 647. 
Fig. 646.—Vertical section of human retina, a, rods and cones; b, ext., and j, int. limit, memb.; 
c, ext., and J,\ int. nucl. layers; e, ext., and g, int. gran, layers ; h, blood-vessel and nerve- 
cells ; i, nerve-fibres. Fig. 647.—Layers of the retina. Pi, hexagonal pigment-cells; St, 
rods and cones; Le, ext. limiting membrane; au,K, ext. nuclear layer; du.gr, ext, granu- 
lar layer; inK, int. nuclear; in.gr, int. granular; Ggl, ganglionic nerve-cells; 0, fibres of 
optic nerve; Li, int. limit, membrane ; Rk, fibres of Muller; K, nuclei; Sg, spaces for the 
nervous elements. 
(Le and Li) lies the connective-tissue substance of the retina. It con- 
tains the perforating fibres, or Muller’s fibres, which run in a radiate man- 
ner between the two membranes, and hold the various layers of the retina 
together. They begin by a wing-shaped expansion at the internal limiting 
membrane (Lk), and in their course outwards contain nuclei (k). They are 
absent at the yellow spot. The supporting tissue forms a network in all the 
layers, holes being left for the nervous portions (Sg). The inner segments of 
the rods and cones are also surrounded by a sustentacular substance. As the Sec. 384.] 
STRUCTURE OF THE RETINA. 
941 
retina passes forward to the ora serrata, it becomes thinner and thinner, gradu- 
ally becoming richer in connective-tissue elements and poorer in nerve elements, 
until, in the ciliary part, only the cylindrical cells remain (fig. 646). 
[Ranvier divides the layers of the retina into an inner or cerebral part in which the blood- 
vessels are distributed, and an outer layer—neuro-epithelial—which contains no blood-vessels. 
The following classification shows the difference:— 
Table of the Layers of the Retina. 
After Ranvier. 
Classical Classification. 
I. Neuro-epithelial part. 
Pigmentary layer. 
Pigmentary layer. 
Rods and cones. 
Jacob’s membrane. 
External limiting membrane. 
External limiting membrane. 
Bodies of the visual cells, i. e., ] 
rods and cones. / 
\ 
External nuclear layer. 
Basal plexus. 1 
Basal cells. J 
External granular layer. 
II. Cerebral part. 
Layer of unipolar nerve-cells. 1 
Layer of bipolar nerve-cells, j 
Internal nuclear layer. 
Cerebral plexus. 
Internal granular layer. 
Multipolar nerve-cells. 
Multipolar nerve-cells. 
Fibres of the optic nerve. 
Fibres of the optic nerve. 
Internal limiting membrane. 
Internal limiting membrane.] 
Fig. 648. 
Section of the fovea centralis, a, cones ; b and^-, int. and ext. limit, memb.; c, ext., and 
e, nuclear layer; d, fibres; f, nerve-cells. 
[Macula Lutea and Fovea Centralis.—There are no rods in the fovea, 
cones only are present, and they are longer and narrower than in the other parts 
of the retina (fig. 648). The other layers also are thinner, especially at the 
macula lutea, but they become thicker towards the margins of the fovea, where 
the ganglionic layer consists of several rows of bipolar cells. The yellow tint 
is due to pigment lying between the layers composing the yellow spot.] 
The blood-vessels of the retina lie in the inner layers near the inner 
granular layer. Only near the entrance of the optic nerve are they connected 
by fine branches with the choroidal vessels; they are surrounded by perivascu- 
lar lymph-spaces. The greatest number of capillaries run in the layers external 
to the inner granular layer (Hesse). The fovea centralis is devoid of blood- 
vessels (JVettleshifi, Becker). Except in mammals, the eel (Denissenko), and 
some tortoises (Zf. Muller), the retina receives no blood-vessels. Destruction 
of the retina is followed by blindness. 942 
VISUAL PURPLE. 
[Sec. 384. 
[Retinal Epithelium.—The single layer of pigmentary cells containing 
granules of a kind of melanin sends processes downwards, like the hairs of a 
brush, between the rods and cones (§ 398). Kiihne has shown that the nature 
and amount of light influence the condition of these processes (fig. 693). The 
protoplasm of these cells in a frog kept for several hours in the dark is retracted, 
and the pigment-granules lie chiefly in the body of the cell and in the pro- 
cesses near the cell. In a frog kept in bright daylight, the processes loaded 
with pigment penetrate downwards between the rods and cones as far as the 
external limiting membrane. 
[The black variety of melanin found in the hexagonal cells of the retina is called fuscin. 
The outer part of each cell consists of neuro-keratin, but the inner part is loaded with granules 
of fuscin, and the cell-protoplasm exhibits movements like those of protoplasm under the influ- 
ence of light. It is a nitrogenous pigment, but it is doubtful if it contains iron, and even if it is 
derived from haemoglobin], 
[Tapetum.—In the eye of the cat and dog a glancing iridescent appearance 
is seen in the retina. This is the tapetum, which is due to many of the retinal 
epithelial cells containing no fuscin. They, however, contain fine transparent 
crystals. In some fishes crystals of guanin occur, while the iridescent appear- 
ance of the tapetum in the eye of the ox and sheep is due to fibrous tissue.] 
[Each rod and cone consists of an outer and an inner segment. During 
life, the outer segments of the rods contain a reddish pigment or the visual 
purple (BolT). Each rod is 60 p long and 2 p broad. The outer segment of 
each rod is doubly refractive and tends to split up into transverse discs. It is 
narrower than the inner segment and is stained black by osmic acid. The inner 
finely granular segment is stained by carmine and often presents a striated ap- 
pearance. At its outer part it contains an elliptical fibrous apparatus. The 
nucleus in the body of each rod lying in the external nuclear layer is marked 
by two or three transverse bands. The outer segment of the cones is shorter 
and more conical than that of the rods, while the inner segment is thick and 
bulging. The outer segment of each rod and cone consists externally of a 
membrane composed of neuro-keratin, containing a substance described by 
Kiihne as myeloidin, which is the substance stained black by osmic acid, and it 
is perhaps a compound of lecithin and a globulin.] 
Visual purple [or rhodopsin] may be preserved by keeping the eye in 
darkness ; but it is soon bleached by daylight, while it is again restored when 
the eye is placed in darkness. It can be extracted from the retina by means of 
a 2.5 per cent, solution of the bile acids, especially from eyes that have been 
kept in 10 per cent, solution of common salt (Ayres). The rods are 0.04 to 0.06 
mm. high and 0.0016 to 0.0018 mm. broad, and exhibit longitudinal striation, 
produced by the presence of fine grooves ; a fine fibril runs in their interior 
{Ritter). The external segment occasionally cleaves transversely into a number 
of fine transparent discs. [It is a very resistant structure, and in this respect 
resembles neuro-keratin.] Krause found an ellipsoidal body, the “ rod 
ellipsoid,” at the junction at the inner and outer segments of the rods. The 
cones are devoid of visual purple, but their outer segment is striated longitudin- 
ally, and it also readily breaks across into thin discs. Only cones are present 
in the macula lutea. In the neighborhood of the yellow spot, each cone is sur- 
rounded by a ring of rods. The cones become less numerous towards the 
periphery of the retina. In nocturnal animals, such as the owl and bat, there 
are either no cones or imperfect ones. The retinae of birds contain many cones, 
that of the tortoise only cones. The rods and cones rest on the sieve-like per- 
forated external limiting membrane {Le). Both send processes through the 
membrane, the cones to the larger and higher-placed nuclei, the rods to the 
nuclei, with transverse markings in the external nuclear layer. [The cones are Sec. 384.] 
THE LENS. 
943 
particularly large in some fishes, e.g., the cod, while the skate has no cones, but 
only rods. The same is the case in the shark and sturgeon, hedgehog, bat, and 
mole.] 
[Distribution and Regeneration of Rhodopsin.—Keep a rabbit in the dark for some 
time, kill it, remove its eyeball, and examine its retina by the aid of monochromatic (sodium) 
light. The retina will be purple-red in color, all except the macula lutea and a small part at the 
era serrata. The pigment is confined to the outer segments of the rods. It is absent in pigeons, 
hens, and one bat, although the last has only rods. It is found both in nocturnal and diurnal 
animals. Its color is quickly bleached by light, and it fades rapidly at a temperature of 50° to 
76° C., while trypsin, alum, and ammonia do not affect it. It is restored in the retina by the 
action of the retinal epithelium. If the retinal epithelium or choroid be lifted off from an excised 
eye exposed to light, the purple is destroyed ; but if the eye be placed in darkness and the 
retinal epithelium replaced, the color is restored.] 
Chemistry of the Retina.—The reaction of the retina, when quite fresh, 
is acid, and becomes alkaline in darkness. The rods and cones contain albumin, 
neurokeratin, nuclein, and in the cones are the pigmented oil-globules, the so- 
called “ chromophanes.” The other layers contain the constituents of the 
gray matter of the brain. 
[Chromophanes, the Pigments of the Cones.—There is no coloring matter in the outer 
segment of the cones, but in fishes, reptiles, and birds the inner segment contains a globular or 
colored body, often red and yellow, the pigment being held in solution by a fatty body. Klihne 
has separated a green (chlorophane), a yellow (xanthophane), and a red (rhodophane) pig- 
ment. They all give a blue with iodine, and are bleached by light (Schwalbe).'] 
The crystalline lens is enclosed in a transparent capsule, thicker anteri- 
orly than posteriorly, and it is covered on the inner surface of the anterior wall 
by a layer of low epithelium. Towards the margin 
of the lens, these cells elongate into nucleated 
fibres, which all bend round the margin of the lens, 
and on both sides of the lens abut with their ends 
against each of the triradiate figures. The lens 
fibres contain globulin enclosed in a kind of mem- 
brane. Owing to mutual pressure, they are hexa- 
gonal when seen in transverse section (fig. 649, 
2), while in many animals, especially fishes, their 
margins are serrated, and the teeth dovetail into 
each other. For the sake of simplicity, we may 
regard the lens as a biconvex body with spherical 
surfaces, the posterior surface being more curved. 
As a matter of fact, the anterior part is part of an 
ellipsoid formed by rotation on its short axis. 
The posterior surface resembles the section of a 
paraboloid, i.e., we might regard it as formed by 
the rotation of a parabola on its axis (Briicke). 
The outer layers of the lens have less refractive 
power than the more internal layers. The central 
part of the lens or nucleus is, at the same time, 
firmer, and more convex than the entire lens. The margin of the lens is always 
separated from the ciliary processes by an intermediate space. 
[Chemistry of the Lens.—The lens contains about two-thirds of its weight 
of water (63.50 per cent.), while its chief solid is a globulin, called by Berzelius 
crystallin (24.6 per cent.), salts, cholesterin, and fats. Albumin is said to be 
absent, but it is present in the ox lens.] 
[Cataract.—Sometimes the lens becomes more or less opaque, the opacity 
beginning either in the middle or outer parts of the lens. This is generally due 
to fatty degeneration of the fibres, cholesterin being deposited. An opaque, 
Fig. 649. 
I, Fibres of the lens; 2, trans- 
verse sections of the lens fibres. 944 
THE VITREOUS HUMOR. 
[Sec. 384. 
cataractous condition of the lens may be produced in frogs by injecting a solu- 
tion of some salts or sugar into the lymph-sacs ; the result is that these salts 
absorb the water from the lens, and thus make it opaque. The cataract of 
diabetes is probably produced from the presence of grape-sugar in the blood.] 
The zonule of Zinn, at the ora serrata, is applied as a folded membrane to 
the ciliary part of the uvea, so that the ciliary processes are pressed into its folds, 
and are united to it. It passes to the margins of the lens, where it is inserted 
by a series of folds into the anterior part of the capsule of the lens. Behind 
the zonule of Zinn, and reaching as far as the vitreous humor, is the canal of 
Petit. The zonule is a fibrous perforated membrane. According to Merkel, 
the canal of Petit is enclosed by very fine fibres, so that it is really not a canal, 
but a complex communicating system of spaces (Gerlach). Nevertheless, the 
Horizontal section of the entrance of the optic nerve and the coats of the eye. a, inner, b, outer 
layers of the retina; c, choroid ; d, sclerotic; e, physiological cup ; f, central artery of retina 
in axial canal; g, its point of bifurcation; h, lamina cribrosa; /, outer (dural) sheath; 
tn, outer (subdural) space; n, inner (subarachnoid) space ; r, middle (arachnoid) sheath; 
J), inner (pial) sheath; i, bundles of nerve-fibres; k, longitudinal septa of connective- 
tissue. 
Fig. 650. 
zonule represents a stretched membrane, holding the lens in position, and may 
therefore be regarded as the suspensory ligament of the lens. 
Opacity or cloudiness of the lens (gray cataract) hinders the passage of light into the eye. 
Aphakia, or the absence of the lens (as after operations for cataract), may be remedied by a 
pair of strong convex spectacles. Of course, such an eye does not possess the power of accom- 
modation. 
The vitreous humor, so far as the ora serrata, is bounded by the internal 
limiting membrane of the retina (.Henle, Iwanoff'). From here forwards, lying 
between both, are the meridional fibres of the zonule, which are united with 
the surface of the vitreous and the ciliary processes. A part of the fibrous layer 
bends into the saucer-shaped depression and bounds it. A canal, 2 mm. in Sec. 384.] 
INTRAOCULAR PRESSURE. 
945 
diameter, runs from the optic papilla to the posterior surface of the capsule of 
the lens; it is called the hyaloid canal, and was formerly traversed by blood- 
vessels. The peripheral part of the vitreous humor is laminated like an onion, 
the middle is homogeneous; in the former, especially in the foetus, are round 
fusiform or branched cells of the mucous tissue of the vitreous, while in the 
centre there are disintegrated remains of these cells (Iwanoff). The vitreous 
humor contains a very small percentage of solids, 1.5 per cent, of mucin [and 
according to Pickard there is 0.5 per cent, of urea, and about .75 of sodic 
chloride]. 
[Structure of the Vitreous Humor.—It consists essentially of mucous tissue, in whose 
meshes lies a very watery fluid, containing the organic and inorganic bodies in solution. It con- 
tains 1.1 per cent, of solids, including a trace of albumin, a mucoid body, a trace of urea, and 
salts. According to Younan, the vitreous contains two types of cells—(1) amoeboid cells of 
various shapes and sizes. They lie on the inner surface of the lining hyaloid membrane and 
the other membranes in the cortex of the vitreous; (2) large branching cells. The vitreous 
is permeated by a large number of transparent, clear, homogeneous hyaloid membranes, 
which are so disposed as to give rise to a concentric lamination. The canal of Stilling repre- 
sents in the adult the situation of the hyaloid artery of the foetus. It can readily be injected by 
a colored fluid.] 
The lymphatics of the eye consist of an anterior and a posterior set. The 
anterior system consists of the anterior and posterior chambers of the eye 
(aqueous), which communicate with the lymphatics of the iris, ciliary processes, 
cornea, and conjunctiva. The posterior consist of the perichoroidal space 
between the sclerotic and the choroid {Schwalbe). This space is connected 
by means of the perivascular lymphatics around the trunks of the vasa vorticosa, 
with the large lymph-space of Tenon, which lies between the sclerotic and 
Tenon’s capsule. Posteriorly, this is continued into a lymph-channel, which 
invests the surface of the optic nerve; while anteriorly it communicates 
directly with the sub-conjunctival lymph-spaces of the eyeball. The optic 
nerve has three sheaths—(1) the dural; (2) the arachnoid ; and (3) the 
pial sheath, derived from the corresponding membranes of the brain. Two 
lymph-spaces lie between these three sheaths—the subdural space between 
1 and 2, and the subarachnoid space between 2 and 3 (fig. 636). Both 
spaces are lined by endothelium; and the fine trabeculae passing from one wall 
to the other are similarly covered. According to Axel Key and Retzius, these 
lymph-spaces communicate anteriorly with the perichoroidal space. 
The aqueous humor closely resembles the cerebro spinal fluid, and contains albumin [and a 
reducing body, which is not sugar] ; the former is increased and the latter disappears after 
death. The same occurs in the vitreous. The albumin increases when the difference between 
the blood-pressure and the intraocular pressure rises. Such variations of pressure, and also 
intense stimuli applied to the eye, cause the production of fibrin in the anterior chamber (Jesner 
and Griinhagen). [It is a clear alkaline fluid, specific gravity 1003-1009, and containing 1.3 
per cent, of solids, the proportion of proteids being only .12 per cent. It is lymph, containing 
a very small quantity of solids, the chief inorganic solid being sodic chloride. The proteids are 
fibrinogen, serum-albumin, and serum-globulin. Traces of urea and sarco-lactic acid are present. 
The reducing substance does not undergo the alcoholic fermentation, and is therefore not sugar.] 
Intraocular Pressure.—The cavity of the bulb is practically filled with 
watery fluids, which, during life, are constantly subjected to a certain pressure, 
the “intraocular pressure.” Ultimately, this depends upon the blood-pres- 
sure within the arteries of the retina and uvea, and must rise and fall with it. 
The pressure is determined by pressing upon the eyeball, and ascertaining 
whether it is tense, or soft and compressible. 
Just as in the case of the arterial pressure, the intraocular pressure is influenced by many cir- 
cumstances; it is increased at every pulse-beat and at every expiration, while it is decreased 
during inspiration. The elastic tension of the sclerotic and cornea regulates the increase of the 
arterial pressure by acting like the air-chamber in a fire-engine; thus, when arterial blood is 946 
DIOPTRIC OBSERVATIONS. 
[Sec. 384. 
pumped into the eyeball, more venous blood is also expelled. The constancy of the intraocular 
pressure is also influenced by the fact that, just as the aqueous humor is removed, it is secreted, 
or rather formed, as rapidly as it is absorbed (§ 392). [Fick has invented an instrument for the 
direct measurement of the intraocular pressure; a small plate of known size is pressed against 
the eyeball, and the pressure exerted is registered by means of a spring and index.] 
The secretion of the aqueous humor occurs pretty rapidly, as may be 
surmised from the fact that haemoglobin is found in the aqueous humor half an 
hour after dissolved blood (lamb’s) is injected into the blood-vessels of a dog. 
It is rapidly reformed, after evacuation through a wound in the cornea. 
According to Knies, the watery fluid within the eyeball is secreted, especially from the chorio- 
capillaris, and reaches the suprachoroidal space, in the lymph-sheaths of the optic nerve, and 
partly through the network of the sclerotic. It saturates the retina, vitreous humor, lens, and 
for the most part passes through the zonula ciliaris into the posterior chamber, and through the 
pupil into the anterior chamber. The movements of the fluid within the eyeball have been 
recently studied by Ehrlich, who used fluorescin, an indifferent substance, which, on being 
introduced into the body, passes into the fluids of the eyeball, and in a very dilute solution may 
be recognized by its green fluorescence in reflected light. From observations on the entrance of 
this substance into the eye, Scholer and Uhthoff regard the posterior surface of the iris and the 
ciliary body as the secretory organs for the aqueous humor. It passes through the pupil into the 
anterior chamber; some passes into the lens, and along the canal of Petit into the vitreous humor 
(Pfliiger). Section of the cervical sympathetic, and still more of the trigeminus, accelerates the 
secretion of the aqueous, but its amount is diminished. If the substance is dropped into the 
conjunctival sac, it percolates towards the centre of the cornea, and through the latter into the 
anterior chamber (PJluger). 
A current passes forwards from the vitreous humor around the lens, and there is an outflow 
along the central artery of the retina backwards through the optic nerve to the cavity of the 
skull (Gifford). The current in the spaces between the sheaths flows from the brain to the eye 
(Quincke). 
The outflow of the aqueous humor, according to Leber and Heisrath, takes place chiefly 
between the meshes of the ligamentum pectinatum iridis (fig. 645, m, m), and the canal ot 
Schlemm (i, k), into the anterior circular veins (p. 936). A small part of the aqueous humor 
diffuses into the posterior layers of the cornea, to nourish it [Leber). None of the water is con- 
ducted from the eyeball by any special efferent lymphatics [Leber). Under normal circum- 
stances, the pressure is nearly the same in the vitreous and aqueous chambers, but atropin seems 
to diminish the pressure in the former and to increase it in the latter, whilst Calabar bean has an 
opposite action [Ad. Weber). Arrest of the outflow of the venous blood often increases the 
pressure in the vitreous, and diminishes that in the aqueous chamber. Compression of the bulb 
from without causes more fluid to pass out of the eye temporarily than enters it. The diminution 
of the intraocular pressure is well marked after section of the trigeminus, while it rises when this 
nerve is stimulated. The statements of observers regarding the effect of the sympathetic nerve 
upon the pressure vary. Interruption to the venous outflow increases the pressure, while an 
imperfect supply of blood, the outflow being normal, diminishes the pressure. The innervation 
of the blood-vessels of the eye is referred to at \ 347. 
385. DIOPTRIC OBSERVATIONS.—The eye as an optical in- 
strument is comparable to a camera obscura; in both, an inverted 
diminished image of the objects of the external world is formed upon a 
background, the field of projection. Instead of the single lens of the camera, 
however, the eye has several refractive media placed behind each other— 
cornea, aqueous humor, lens (whose individual parts—capsule, cortical 
layers, and nucleus, all possess different refractive indices), and vitreous 
humor. Every two of these adjacent media are bounded by a “ refractive 
surface,” which may be regarded as spherical. The field of projection of 
the eye is the retina, which is colored with the visual purple (.Boll, Kiihne). 
As this substance is bleached chemically by the direct action of light, so that 
the pictures may be temporarily fixed upon the retina, the comparison of the 
eye with the camera of the photographer becomes more striking. In order that 
the passage of the rays of light through the media of the eye may be rightly 
understood, we must know the following factors : (1) the refractive indices of 
all the media; (2) the form of the refractive surfaces; (3) the distance of the 
various media from each other and from the field of projection or retina. Sec. 385.] 
ACTION OF LENSES. 
947 
Action of a Converging Lens.—We must know how a convex lens acts upon light. In a 
convex lens we distinguish the centre of curvature, i. e., the centre of both spherical surfaces (fig. 
651, I, 222, mj). The line connecting both is called the chief axis; the centre of this line is 
the optical centre of the lens (0). All rays which pass through the optical centre of the lens 
pass through unbent, or without being refracted; they are called the chief or principal rays (22, 
22j). The following are the laws regulating the action of a convex lens upon rays of light:— 
x. Rays which fall upon the lens, parallel with the principal axis (II, f a.), are so refracted 
that they are collected on the other side of the lens, at a point called the focus or principal focus 
(f). The distance of this point from the central point (0) of the lens is called the focal dis- 
tance of the lens (f o). The converse of this condition is evident, viz., rays which diverge 
from a focus and reach the lens, pass through it to the other side, parallel with the principal axis, 
without again coming together. 
2. Rays of light proceeding from a source of light (IV, /) in the prolonged principal axis, but 
beyond the focal point (/), again converge to a point on the other side of the lens. The fol- 
lowing cases may occur: (a) When the distance of the light from the lens is equal to twice the 
focal distance, the focus or point of convergence lies at the same distance on the other side of 
Fig. 651. 
Figures illustrating the action of lenses upon rays of light passing through them. 
the lens, i. e., twice the focal distance, (b) If the luminous point be moved nearer to the focus, 
then the focal point is moved farther away. (c) If the light is still farther from the lens than 
twice the focal distance, then the focal point comes correspondingly near to the lens. 
3. Rays proceeding from a point of the chief axis (III, b) within the focal distance pass out at 
the other side less divergent, but do not come to a focus again. Conversely, rays which are con- 
vergent and pass through a collecting lens have their focal point within the focal distance. 
4. If the luminous point (V, a) is placed in the secondary ray (a, b), the same laws obtain, 
provided the angle formed by the secondary ray with the principal axis is small. 
Formation of Images by Convex Lenses.—After what has been stated regarding the 
position of the point of convergence of rays proceeding from a luminous point, the construction 
of the image of any object by a convex lens is easily accomplished. This is done simply by 
projecting images of the various parts of the object. Thus, evidently (in V), b is the focal point 
of the object a, while v is the focal point of the object /. The picture is inverted. Collecting 
lenses form an inverted and real image (2. e., upon a screen) only of such objects as are placed 
beyond the focal point of the lens. 
With regard to the size and distance of the image from the lens, there are the following 
cases: (a) If the object be placed at twice the focal distance from the lens, the image of the 948 
ACTION OF LENSES. 
[Sec. 385. 
same is just the same size and at the same distance from the lens as the object is. (b) If the 
object be nearer than the focus, the image recedes and at the same time becomes larger, (z) If 
the object be farther removed from the lens than twice the focal distance, then the image is 
nearer to the lens and at the same time becomes smaller. 
Position of the Focal Point.—The distance of the focal point from the lens is readily 
calculated according to the following formula: Where l — the distance of the luminous point, b 
I I I I II 
= the distance of the image, and f=. the focal distance of the lens: y + y = y, or y = y— 
1 1 I I 
Example.—Let /= 24 centimetres, f— 6 cm. Then y == y — y = -g; so that <5 = 8 cm., 
i.e., the image is formed 8 cm. behind the lens. Further, let 1= locm.,/= 5 cm. (i.e.,l= 2f). 
1 1 I 1 
Then y = y — — = --; so that b— 10, i.e., the image is placed at twice the focal distance of 
the lens. Lastly, let / = 00 . Then y = y — oo; so that b—f, i.e., the image of parallel 
rays coming from infinity lies in the focal point of the lens. 
Refractive Indices.—A ray of light which passes in a perpendicular direction from one 
medium into another medium of different density, passes through the latter without changing its 
course or being refracted. In fig. 652, if G D is j_ A B, then so is D D j_ A B; for a plane 
surface A B is the horizontal, and G D the vertical line. If the surface be spherical, then the 
vertical line is the prolonged radius of this sphere. If, however, the ray of light fall obliquely 
Fig. 652. 
Fig- 653. 
upon the surface, it is “ refracted,” i.e., it is bent out of its original course. The incident and 
the refracted ray nevertheless lie in one plane. When the oblique incident ray passes from a 
less dense medium (e.g., air) into one more dense {e.g., water), the refracted or excident ray is 
bent towards the perpendicular. If, conversely, it pass from a more dense to a less dense medium, 
it is bent away from the perpendicular. The angle (t G D S) which the incident ray (S D) 
forms with the perpendicular (G D) is called the angle of incidence, the angle formed by the 
refracted ray (D Sx) with the prolonged perpendicular (D D) is called the angle of refraction, 
DDS, (r). The refractive power is expressed as the refractive index. The term refractive 
index (n) means that number which shows for a certain substance how many times the sine of 
the angle of incidence is greater than the sine of the angle of refraction, when a ray of light 
passes from the air into that substance. Thus, n — sin. i : sin. r — ab -. cd. On comparing the 
lefractive indices of two media, we always assume that the ray passes from air into the medium. 
On passing from the air into water, the ray of light is so refracted that the sine of the angle of 
4 
incidence is to the sine of the angle of refraction as 4 : 3; the refractive index — (or more 
exactly = 1.336). With glass the proportion is = 3 : 2 = 1.535—(Snellius, 1620; Descartes'). 
The sine of the incident and refractive angles are related as the velocity of light with both 
media. 
The construction of the refracted ray, the refractive index being given, is simple: 
Example.—Suppose in fig. 653, L = the air, G = a dense medium (glass) with a spherical sur- 
face, xy, and with its centre at m; po = the oblique incident ray; mZ is the perpendicular; Sec. 385.] 
.3 
the <( ) i = the angle of incidence. The refractive index given is — ; the object is to find the 
direction of the refracted ray. From o as centre describe a circle with a radius of any length ; 
from a draw a perpendicular, a b to m Z ; then a b is the sine of the angle of incidence, i. 
Divide the line a b into three equal parts, and prolong it to the extent of two of these parts, 
viz., to p. Draw the line p parallel to m Z. The line joining o to n is the direction of the 
refracted ray. On making a line, n s, perpendicular to m Z,ns = bp. Further, ns — sine <[ ) 
3 
= r. So that a b : s n or : bp) — 3 : 2 or sin. i : sin. r — —. 
Optical Cardinal Point of a Simple Collecting System.—Two refractive media (fig. 
654, L and G), which are separated from each other by a spherical surface (a, b), form a simple 
collecting system. It is easy to estimate the construction of an incident ray coming from the first 
medium (L) and falling obliquely upon the surface (a, b) separating the two media, as well as 
to ascertain its direction in the second medium, G, and also from the position of a luminous 
point in the first medium, to estimate the position of the corresponding focal point in the second 
medium. The factors required to be known are the following: L (fig. 654) is the first, and G 
the second medium, a, b — the spherical surface whose centre is m. Of course, all the radii 
drawn from m to a b (m x, m n) are perpendiculars, so that all rays falling in the direction of 
the radii must pass unrefracted through m. All rays of this sort are called rays or lines of 
direction; m, as the point of intersection of all these, is called the nodal point. Ihe line 
which connects m with the vertex of the spherical surface, x, and which is prolonged in both 
directions, is called the optic axis, O Q. A plane (E, F) in x, perpendicular to O Q, is called 
the principal plane, and in it x is the principal point. The following facts have been ascer- 
ACTION OF LENSES. 
949 
Fig. 654. 
tained: (i) All rays (a to a5), which in the first medium are parallel with each other and with 
the optic axis and fall upon a b, are so refracted in the second medium that they are all again 
united in one point (pf) of the second medium. This is called the second principal focus. A 
plane in this point perpendicular to O Q is called the second focal plane (CD), (2) All rays 
(c to c2), which in the first medium are parallel to each other, but not parallel to O Q, reunite 
in a point of the second focal plane (r), where the non-refracted directive ray (clf m r) meets 
this. (In this case, the angle formed by the rays c to c2 with C Q must be very small.) The 
propositions 1 and 2 of course may be reversed; the divergent rays proceeding from p towards 
a b pass into the first medium parallel to each other, and also with the axis C Q (a to «5); and 
the rays proceeding from r pass into the first medium parallel to each other, but not parallel 
to the axis O Q (as c to cf). (3) All rays, which in the second medium are parallel to each 
other (b to b5) and with the axis O Q, reunite in a point in the first medium (/) called the first 
focal point; of course the converse of this is true. A plane in this point perpendicular to O Q 
is called the first focal plane (A, B). The radius of the refractive surface (m, x) is equal to the 
difference of the distance of both focal points (p and pf) from the principal focus (x); thus m x = 
pxxpx. From these comparatively simple propositions it is easy to determine the following 
points:— 
1. The Construction of the Refracted Ray.—Let A be the first (fig. 655); B, the second 
medium; c d, the spherical surface separating the two; a b, the optical axis; k, the nodal point; 
p, the first and px the second principal focus; C, D, the second focal plane. Suppose xy to 
represent the direction of the incident ray, what is the construction of the refracted ray in the 
second medium ? Prolong the unrefracted ray, P k, to Q parallel to x y, then y Q is the direction 
of the refracted ray (according to 2). [Sec. 385. 
950 
ACTION OF LENSES. 
2. Construction of the Image for a Given Object.—In fig. 656, B, c, d, a, b, k, p, 
andpx, C, D are as before. Suppose a luminous point (0) in the first medium, what is the posi- 
tion of the image in the second medium? Prolong the unrefracted ray (0, k, P), and draw the 
ray (0, x) parallel to the axis (a, b). The parallel rays (a, e and 0, x) reunite in p (according to 
proposition 1). Prolong x,p1 until it intersects the ray (0, P), then the image of 0 is at P—that 
is, the rays of light (0 x and 
0 k) proceeding from the 
luminous point (o) reunite 
in P. 
Construction of the 
Refracted Ray and the 
Image in Several Re- 
fractive Media.—If several 
refractive media be placed 
behind each other, we must 
proceed from medium to 
medium with the same 
methods as above described. 
This would be very tedious, 
especially when dealing with 
small objects. Gauss (1840) calculated that in such cases the method of construction is very 
simple. If the several media are “ centred,” i. e., if all have the same optic axis, then the 
refractive indices of such a centred system may be represented by two equal, strong, refractive 
Fig- 655- 
Fig. 656. 
surfaces at a certain distance. The rays falling upon the first surface are not refracted by it, 
but are essentially projected forwards parallel with themselves to the second surface. Refraction 
takes place first at the second surface, just as if only one refractive surface was present. In 
order to make the calculation, we must know the refractive indices of the media, the radii of the 
refractive surfaces, and the distance of the refractive surfaces from each other. 
Construction of the refracted ray is accomplished as follows : Let a b represent the 
optical axis (fig. 657, I); H, the first focal point determined by calculation; h h, the principal 
plane; H, the second foeal point; hx hv the second principal plane ; k, the first, and kv the 
second nodal point; F, the second focal point; and F1} F,, the second focal plane. Make the 
ray of direction p kx parallel to mv nv According to proposition 2, p, kx and mv nx must 
meet in a point of the plane Fx Fj. As p kx passes through unrefracted, the ray from nx must 
fall at r; nx r is, therefore, the direction of the refracted ray. 
Construction of the Focal Point.—Let 0 be a luminous point (fig. 657, II), what is the 
position of its image in the last medium ? Prolong from o the ray of direction 0 k, and make 
0, x parallel to a b. Both rays are prolonged in a parallel direction to the second focal plane. 
The ray parallel to a b goes through F; vi, kx as the ray of direction passes through unrefracted. 
O, where n, F, and m kx intersect each other, is the position of the image of 0. 
386. DIOPTRICS —RETINAL IMAGE — OPHTHALMOME- 
TER.—Position of the Cardinal Points.—The eye surrounded with air on 
the anterior surface of the cornea represents a concentric system of refractive 
media with spherical separating surfaces. In order to ascertain the course of 
the rays through the various media of the eye we must know the position of 
both principal foci of both nodal points as well as the two principal focal points. 
Gauss, Listing, and v. Helmholtz have calculated the position of these points. 
In order to make this calculation, we require to know the refractive indices of 
the media of the eye, the radii of the refractive surfaces, and the distance of Sec. 386.] 
FORMATION OF THE RETINAL IMAGE. 
951 
the latter from each other. These will be referred to afterwards. (1) The 
first principal point is 2.1746 mm. ; and (2) the second principal point 
is 2.5724 mm. behind the anterior surface of the cornea. (3) The first nodal 
point, 0.7580 mm.; and (4) the second nodal point, 0.3602 mm. in front 
of the posterior surface of the lens. (5) The second principal focus, 
14.6470 mm. behind the posterior surface of the lens ; and (6) the first prin- 
cipal focus, 12.8326 in front of the anterior surface of the cornea. 
Listing’s Reduced Eye.—The distance between the two principal points, 
or the two nodal points, is so small (only 0.4 mm.), that practically, without 
introducing any great error in the construction, we may assume one mean nodal 
or principal point lying between the two nodal or principal points. By this 
simple procedure we gain one refractive surface for all the media of the eye, 
and only one nodal point, through which all the rays of direction from with- 
out must pass without being refracted. This schematic simplified eye is called 
“ the reduced eye ” of Listing. 
Fig. 657. 
Formation of the Retinal Image.—Thus, the construction of the image 
on the retina becomes very simple. In distinct vision, the inverted image is 
formed on the retina. Let A B represent an object placed vertically in front of the 
eye (fig. 658). A pencil of rays passes from A into the eye ; the ray of direc- 
tion, A d, passes without refraction through the nodal point, k. Further, as the 
focal point for the luminous point, A, is upon the retina, all the rays proceeding 
from A must reunite in d. The same is true of the rays proceeding from B, 
and, of course, for rays sent out from an intermediate point of the body, A B. 
The retinal image is, as it were, a mosaic, composed of innumerable foci of the 
object. As all the rays of direction must pass through the common nodal 
point, k, this is also called the “ point of intersection of the visual 
rays.” 
The inverted image on the retina is easily seen in the excised eye of an albino rabbit, by hold- 
ing up any object in front of the cornea and observing the inverted image through the trans- 
parent coats of the eyeball. 952 
OPHTHALMOMETER. 
[Sec. 386. 
The size of the retinal image may also be calculated, provided we know the size of the object, 
and its distance from the cornea. As the two triangles, A B k and c d k are similar, A B : c d — 
f k : kg, so that c d = (A B, k g) : f k. All these values are known, viz., kg— 15.16 mm.; 
further, f k — a k x af, where a f is measured directly, and a k — 7.44 mm. The size of A B 
is measured directly. 
The angle, A k B, is called the visual angle, and of course it is equal to 
the angle c k d. It is evident that the nearer objects, xy, and r s, must have 
the same visual angle. Hence, all the three objects, A B, x y, and r s, give 
a retinal image of the same size. Such objects, whose ends when united with 
the nodal point form a visual angle of the same size, and consequently form 
retinal images of the same size, have the same “ apparent size.” 
In order to determine the optical cardinal points by calculation, after the 
method of Gauss, we must know the following factors:— 
1. The refractive indices : for the cornea, x.377 ; aqueous humor, 1.377 ; 
lens, 1.454 (as the mean value of all the layers) ; vitreous humor, 1.336; air 
being taken as 1, and water 1.335. 
2. The radii of the spherical refractive surfaces: of the cornea, 7.7 
mm.; of the anterior surface of the lens, 10.3; of the posterior, 6.1 mm. 
Fig. 658. 
Mode of formation of an image on the retina. 
3. The distance of the refractive surfaces: from the vertex of the 
cornea to the anterior surface of the lens, 3.4 mm.; from the latter to the pos- 
terior surface of the lens (axis of the lens), 4 mm.; diameter of the vitreous 
humor, 14.6 mm. The total length of the optic axis is 22.0 mm. 
[Kiihne’s Artificial Eye.—The formation of an inverted image, and the other points in the 
dioptrics of the eye can be studied most effectively on Kiihne’s artificial eye, the course of the 
rays of light being visible in water tinged with eosine, resculin, or milk.] 
Ophthalmometer.—This is an instrument to enable us to measure the radii 
of the refractive media of the eye. As the normal curvature cannot be accu- 
rately measured on the dead eye, owing to the rapid collapse of the ocular 
tunics, we have recourse to the process of Kohlrausch, for calculating the radii 
of the refractive surfaces from the size of the reflected images in the living eye. 
The size of a luminous body is to the size of its reflected image as the distance 
of both to half the radius of the convex mirror. Hence, it is necessary to 
measure the size of the reflected image. This is done by means of the oph- 
thalmometer of Helmholtz (fig. 659). 
The apparatus is constructed on the following principle: If we observe an object through a 
glass plate placed obliquely, the object appears to be displaced laterally; the displacement be- 
comes greater the more obliquely the plate is moved. Suppose the observer, A, to look through 
the telescope, F, which has the plate, G, placed obliquely in front of the upper half of its objec* Sec. 386.] 
ACCOMMODATION. 
953 
tive, he sees the corneal reflected image, a />, of the eye, B, and the image appears to be dis- 
placed laterally, viz., to a' b'. If a second plate, G, be placed in front of the lower half of the 
telescope, but placed in the opposite direction, so that both plates, corresponding to the middle 
line of the objective, intersect at an angle, then the observer sees the reflected image, a b, 
displaced laterally to a" b". As both glass plates rotate round their point of intersection, 
the position of both is so selected that both reflected images just touch each other with their 
inner margins (so that b' abuts closely upon a"). The size of the reflected image can be deter- 
mined from the size of the angle formed by both plates, but we must take into calculation the 
thickness of the glass plates and their refractive indices. The size of the corneal image, and 
also that in the lens, may be ascertained in the passive eye, and also in the eye accommodated 
for a near object, and the length of the radius of the curved surface may be calculated there- 
from (.Helmholtz and others). 
Fluorescence.—All the media of the eye, even the retina, are slightly fluorescent; the lens 
most, the vitreous humor least (v. Helmholtz). 
Erect Vision.—As the retinal image is inverted, we must explain how 
we see objects upright. By a psychical act, the impulses from any point of 
the retina are again referred to the exterior, in the direction through the nodal 
point; thus the stimulation of the point d is referred to A, that of c to B 
(fig. 658). The reference of the image to the external world happens thus, 
that all points appear to lie in a surface floating in front of the eye, which is 
called the field of vision. The field of vision is the inverted surface of the 
retina projected externally ; hence, the field of vision appears erect again, as 
the inverted retinal image is again projected externally but inverted (fig. 658). 
Fig. 659. 
That the stimulation of any point is again projected in an inverse direction through the nodal 
point is proved by the simple experiment, that pressure upon the outer aspect of the eyeball is 
projected or referred to the inner aspect of the field of vision. The entoptical phenomena of 
the retina are similarly projected externally and inverted ; so that, e. g., the entrance of the optic 
nerve is referred externally to the yellow spot (see § 393). All sensations from the retina are 
projected externally. 
387. ACCOMMODATION OF THE EYE.—According to No. 2 (p. 950), the rays of 
light proceeding from a luminous point, e. g., a flame, and acted upon by a collecting (convex) 
lens, are brought to a focus or focal point, which has always a definite relation to the luminous 
object. If a projection-surface or screen be placed at this distance from the lens, a real and in- 
verted image of the object is obtained upon the screen. If the screen be placed nearer to the 
lens (fig. 651, IV, a, b), or farther away from it (c, d), no distinct image of the object is formed, 
but diffusion circles are obtained; because, in the former case, the rays have not united, and 
in the latter, because the rays, after uniting, have crossed each other and become divergent. If 
the luminous point be brought nearer to, or removed farther from, the lens, in order to obtain a 
distinct image, in every case, the screen must be brought nearer, or removed from the lens, to 
keep the same distance between the lens and the screen. If, however, the screen be fixed per- 
manently, whilst the distance between the luminous point and the lens varies, a distinct image 
can only be obtained upon the screen, provided the lens, as the luminous point approaches it, 
becomes more convex, i. e., refracts the rays of light more strongly—conversely, when the dis- 
tance between the luminous point and the lens becomes greater, the lens must become less 
curved, i. e., refract less strongly. 
In the eye, the projection surface or screen is represented by the retina, which is permanently 
fixed at a certain distance; but the eye has the power of forming distinct images of near and 
distant objects upon the retina, so that the refractive power, i. e., the form of the crystalline lens 
in the eye, must undergo a change in curvature corresponding in every case to the distance of 
the object. 
Scheme of the ophthalmometer of Helmholtz. [Sec. 387. 
954 
ACCOMMODATION. 
Accommodation.—By the term “accommodation of the eye ” is under- 
stood that property of the eye whereby it forms distinct images of distant as 
well as near objects upon the retina. [It is important to remember that we 
cannot see a near object and a distant one with equal distinctness at the same 
time, and hence arises the necessity for accommodation.] This power depends 
upon the fact that the crystalline lens alters its curvature, becoming 
more convex (thicker), or less curved (flatter), according to the distance of 
the object. When the lens is absent from the eyeball, accommodation is im- 
possible (Th. Young, Donders—p. 944). 
During rest [or negative accommodation], or when the eye is passive, 
it is accommodated for the greatest distance, i. e., images of objects placed at 
an infinite distance, (e. g., the moon) are 
formed upon the retina. In this case, rays 
coming from such a distance are practically 
parallel and when they enter the eye are in 
the passive normal eye (emmetropic) 
brought to a focus 
on the retina. When 
looking at a distant 
object, a distinct im- 
age is formed on the 
retina without the 
aid of any muscular 
action. 
Anterior quadrant of a horizontal section of the eyeball, cornea, and lens; 
a, substantia propria of the cornea; b, Bowman’s elastic membrane; c, 
anterior corneal epithelium; d, Descemet’s membrane ; e, its epithelium ; 
_/, conjunctiva; g, sclerotic ; h, iris; i, sphincter iridis ; j, ligamentum pec- 
tinatum iridis, with the adjoining vacuolated tissue; k, canal of Schlemm ; 
/, longitudinal, m, circular muscular fibres of the ciliary muscle; n, ciliary 
process; o, ciliary part of the retina ; q, canal of Petit, with Z, zonule of 
Zinn in front of it; and p, the posterior layer of the hyaloid membrane ; r, anterior, s, pos- 
terior part of the capsule of the lens; t, choroid; u, perichoroidal space; T, pigment epi- 
thelium of the iris; x, margin of the lens. 
Fig. 660. 
That distant objects are seen without the aid of any muscular action is shown by the follow- 
ing considerations: (1) With the normal or emmetropic eye, we can see distant objects clearly 
and distinctly, without experiencing any feeling of effort. On opening the eyelids after a long 
period of rest, the objects at a distance are at once distinctly visible in the field of vision. (2) 
If, in consequence of paralysis of the mechanism of accommodation (e.g., through paralysis of 
the oculomotor nerve—\ 345, 7), the eye is unable to focus images of objects placed at different 
distances, still distinct images are obtained of distant objects. Thus, paralysis of the mechan- 
ism of accommodation is always accompanied by inability to focus a near object, never a dis- 
tant object. A temporary paralysis occurs with the same results when a solution of atropin or 
duboisin is dropped into the eye, and also in poisoning with these drugs (§ 392). 
When the eye is accommodated for a near object [positive accommo- 
dation], the lens is thicker, its anterior surface is more curved (convex), and 
projects farther into the anterior chamber of the eye (Cramer, 1851, v. Helm- 
holtz, 1853). The mechanism producing this result is the following : During Sec. 387.] 
ACCOMMODATION. 
955 
rest, the lens is kept somewhat flattened against the vitreous humor lying 
behind it, by the tension of the stretched zonule of Zinn, which is attached 
round the margin of the lens (fig. 660, Z). When the muscle of accommo- 
dation, the ciliary muscle (/, m), contracts, it pulls forward the margin of the 
choroid, so that the zonule of Zinn in intimate relation with it is relaxed. 
[When we accommodate for a near object, the ciliary muscle contracts, 
pulls forward the choroid, relaxes the zonule of Zinn, and this in turn dimin- 
ishes the tension of the anterior part of the capsule of the lens.] The lens 
assumes a more curved form, in virtue of its elasticity, so that it becomes 
more convex as soon as the tension of the zonule of Zinn, which keeps it flat- 
tened, is diminished (fig. 661). As the posterior surface of the lens lies in the 
saucer-shaped unyielding depression of the vitreous humor, the anterior sur- 
face of the lens in becoming more convex must necessarily protrude more 
forwards. 
Nerves.—According to Hensen and Volckers, the origin of the nerves of 
accommodation lies in the most anterior root-bundles of the oculomotorius. 
Fig. 661. 
Scheme of accommodation for near and distant objects. The right side of the figure represents 
the condition of the lens during accommodation for a near object and the left side when 
the eye is at rest. The letters indicate the same parts on both sides; those on the right 
side are marked with a dash; A, left, B, right half of the lens; C, cornea ; S, sclerotic; 
C. S, canal of Schlemm; V. K, anterior chamber; J, iris; P, margin of the pupil; V, 
anterior surface; H, posterior surface of the lens; R, margin of the lens ; F, margin of 
the ciliary processes; a and b, space between the two former; the line Z, X, indicates the 
thickness of the lens during accommodation for a near object; Z, Y, the thickness of the 
lens when the eye is passive. 
Stimulation of the posterior part of the floor of the third ventricle causes ac- 
commodation ; if a part lying slightly posterior to this be stimulated, contrac- 
tion of the pupil occurs. On stimulating the limit between the third ventricle 
and the aqueduct, there results contraction of the internal rectus muscle, while 
stimulation of the other parts around the iter causes contraction of the superior 
rectus, levator palpebrse, rectus inferior, and inferior oblique muscles. 
Proofs.—That the lens alters its curvature during accommodation is 
proved by the following facts:— 
i. Purkinje-Sanson’s Images.—If a lighted candle be held at one side 
of the eye, or if light be allowed to fall on the eye through two triangular 
holes, placed above each other and cut in a piece of cardboard, in the latter 
case the observer will see three pairs of reflected images [in the former, three 
images]. The brightest and most distinct image (or pair of images) is erect 
and is produced by the anterior surface of the cornea (fig. 662, a). The sec- 
ond image (or pair of images) is also erect. It is the largest, but it is not so 956 
ACCOMMODATION. 
[Sec. 387. 
bright (b), and it is reflected by the anterior surface of the lens. (The size 
of a reflected image from a convex mirror is greater the longer the radius of 
curvature of the reflecting surface.) The latter image lies 8 mm. behind the 
plane of the pupil. The third image (or pair of images) is of medium size and 
medium brightness—it is inverted and lies nearly in the plane of the pupil 
(c). The posterior capsule of the lens, which reflects the last image, acts like 
a concave mirror. If a luminous object be placed at a distance from a con- 
cave mirror, its inverted, diminished, real image lies close to the focus towards 
the side of the object. If the images be studied when the observed eye is 
passive, i. e., in the phase of negative accommodation, on asking the person 
experimented upon to accommodate his eye for a near object, at once a change 
in the relative position and size of some of the images is apparent. The middle 
pair of images reflected by the anterior 
surface of the lens diminish in size and 
approach each other (b), which depends 
upon the fact that the anterior surface of 
the lens has become more convex. At 
the same time the image (or pair of 
images) comes nearer to the image 
formed by the cornea (a, and as the 
anterior surface of the lens lies nearer to 
the cornea. The other images (or pairs 
of images) neither change their size nor 
position. Helmholtz, with the aid of the 
ophthalmometer, has measured the diminution of the radius of curvature of the 
anterior surface of the lens during accommodation for a near object. 
[Phakoscope.—These images may be readily shown by means of the phakoscope of v. 
Helmholtz (fig. 663). It consists of a triangular box, with its angles cut off, and blackened 
inside. The observer’s eye is placed at a, while on the opposite side of the box are two prisms, 
b, bx \ the observed eye is placed at the side of the box opposite to C. When a candle is held 
in front of the prisms, b and bx, three pairs of images are seen in the observed eye. Ask the 
person to accommodate for a distant object, and note the position of the images. On pushing 
up the slide C with a pin attached to it, and asking him to accommodate for the pin, i. e., for a 
near object, the position and size of the middle images chiefly will be seen to alter as described 
above.] 
2. In consequence of the increased curvature of the lens during accommodation for a near 
object, the refractive indices within the eye must undergo a change. According to v. Helmholtz 
the annexed measurements obtain in negative and positive accommodation respectively. 
Fig. 662. 
Sanson-Purkinje’s images, a, b, c, during 
negative, and a„ b/t cy, positive accom- 
modation. 
Accommodation. 
Negative—mm. 
Positive—mm. 
Radius of the cornea, 
8 
8 
Radius of anterior surface of lens, 
IO 
6 
Radius of posterior surface of lens, . 
6 
5-5 
Position of the vertex of the outer surface of the lens be-1 
hind the vertex of the cornea, / 
3-6 
3-2 
Position of the posterior vertex of the lens, 
7.2 
7.2 
Position of the anterior focal point, . 
12.9 
11.24 
Position of the first principal point, 
1.94 
2.03 
Position of the second principal point 
6.96 
6.51 
Position of the posterior focal point behind the anterior I 
vertex of the cornea, j 
22.23 
20.25 
3. Lateral View of the Pupil.—If the passive eye be looked at from the side, we observe 
only a small black strip of the pupil, which becomes broader as soon as the person experi- 
mented on accommodates for a near object, as the whole pupil is pushed more forwards. Sec. 387.] 
ACCOMMODATION. 
957 
4. Focal Line.—If light be admitted through the cornea into the anterior chamber, the 
“ focal line ” formed by the concave surface of 
the cornea falls upon the iris. If the experi- 
ment be made upon a person whose eye is accom- 
modated for a distant object, so that the line 
Phakoscope of Helmholtz. 
Fig. 663. 
Scheiner’s Experiment. 
Fig. 664. 
lies near the margin of the pupil, it gradually recedes towards the scleral margin of the iris, as 
soon as the person accommodates for a near object, because the iris becomes more oblique as its 
inner margin is pushed forward. 
5. Change in Size of Pupil.—On accommodating for a near object, the 
pupil contracts, while in accommodation for a distant object, it dilates 
(.Descartes, 1637). The contraction takes place slightly after the accommoda- 
tion (Donders). This phenomenon may be regarded as an associated move- 
ment, as both the ciliary muscle and the sphincter pupillse' are supplied by the 
oculomotorius (§ 345, 2, 3). A reference to fig. 660 shows that the latter also 
directly supports the ciliary muscle; as the inner margin of the iris passes 
inwards (towards r), its tension tends to be propagated to the ciliary margin of 
the choroid, which also must pass inwards. The ciliary processes are made 
tense, chiefly by the ciliary muscle (tensor choroideae). Accommodation can 
still be performed, even though the iris be absent or cleft. 
6. Internal Rotation of the Eye.—On rotating the eyeball inwards, 
accommodation for a near object is performed involuntarily. As rotation of 
both eyeballs inwards takes place when the axes of vision are directed to a near 
object, it is evident that this must be accompanied involuntarily by an accom- 
modation of the eye for a near object. 
7. Time for Accommodation.—A person can accommodate from a near to a distant object 
(which depends upon relaxation of the ciliary muscle) much more rapidly than conversely, from 
a distant to a near object ( Vierordt, Aeby). The process of accommodation requires a longer 
time the nearer the object is brought to the eye (Vierordt, Volckers and Hensen). The time 
necessary for the image reflected from the anterior surface of the lens to change its place during 
accommodation is less than that required for subjective accommodation (Aubert and 
Angelucci). 
8. Line of Accommodation.—When the eye is placed in a certain position during accom- 958 
scheiner’s experiment. 
[Sec. 387. 
modation, we may see not one point alone distinctly, but a whole series of points behind each 
other. Czermak called the line in which these points lie the line of accommodation. The more 
the eye is accommodated for a distant object, the longer does this line become. All objects 
placed at a greater distance from the eye than 60 to 70 metres appear equally distinct to the eye. 
The line becomes shorter the more we accommodate for a near object—i. e., when we accommo- 
date as much as possible for a near object a second point can only be seen indistinctly at a short 
distance behind the object looked at. 
9. The nerves concerned in the mechanism of accommodation are referred to under Oculo- 
motorius ($ 345, and again in \ 704). 
Scheiner’s Experiment.—The experiment which bears the name of 
Scheiner (1619) serves to illustrate the refractive action of the lens during 
accommodation for a near object, as well as for a distant object. Make two 
small pin-holes (S, d) in a piece of cardboard (fig. 664, K Kj), the holes being 
nearer to each other than the diameter of the pupil. On looking through 
these holes, S, d, at two needles (p and r) placed behind each other, then on 
accommodating for the near needle (p), the far needle (r) becomes double and 
inverted. On accommodating for the near needle (/), of course the rays 
proceeding from it fall upon the retina at the focus (/x); while the rays coming 
from the far needle (r) have already united and crossed in the vitreous humor, 
whence they diverge more and more and form two pictures (r/f on the 
retina. If the right hole in the cardboard (d) be closed, the left picture on the 
retina (ry/) of the double images of the far needle disappears. An analogous 
result is obtained on accommodating for the far needle (R.) The near needle 
(P) gives a double image (Py, P/y), because the rays from it have not yet come to 
a focus. On closing the right hole (</y), the right double image (Py), disappears 
(Porterfield). When the eye of the observer is accommodated for the near 
needle, on closing one aperture the double image of the distant point disappears 
on that side; but if the eye is accommodated for the distant needle, on closing 
one hole the crossed image of the near needle disappears. 
388. REFRACTIVE POWER OF THE EYE—ANOMALIES 
OF REFRACTION.—The limits of distinct vision vary very greatly in dif- 
ferent eyes. We distinguish the far point [p. r., punctum remotum] 
and the near point [p. p., punctum proximum] ; the former indicates the 
distance to which an object may be removed from the eye, and may still be 
seen distinctly; the latter, the 
distance to which any object 
may be brought to the eye, and 
may still be seen distinctly. 
The distance between these two 
points is called the range of 
accommodation. The types 
of eyeball are characterized as 
follows: — 
1. The normal or emme- 
tropic eye is so arranged when 
at rest that parallel rays (fig. 
665, r, f) coming from the most 
distant objects can be focussed 
on the retina (rf). The far 
point, therefore, is — 00 (infin- 
ity). When accommodating as 
much as possible for a near ob- 
ject, whereby the convexity of 
the lens is increased (fig. 665, a), rays from a luminous point placed at a dis- 
tance of 5 inches are still focussed on the retina, i. e., the near point is = 5 
Condition of refraction in the normal passive eye and 
during accommodation. 
Fig. 665. Sec. 388.] 
ANOMALIES OF REFRACTION. 
959 
inches (i inch = 27 mm.). The range of accommodation [or the “ range 
of distinct vision ”], therefore, is from 5 inches (10-12 cm.) to 00 . 
2. The short-sighted or myopic eye (long eye) cannot, when at rest, 
bring parallel rays from infinity to a focus on the retina (fig. 666). These rays 
decussate within the vitreous humor (at O), and after crossing form diffusion 
circles upon the retina. The object must be removed from the passive eye to a 
distance of 60 to 120 inches (to f), in order that the rays may be focussed on 
the retina. The passive myopic eye, therefore, can only focus divergent rays 
upon the retina. The far point, therefore, lies abnormally near. With an 
intense effort at accommodation, objects at a distance of 4 to 2 inches, or even 
less, from the eye may be seen distinctly. The near point, therefore, lies 
abnormally near; the range of accommodation is diminished. 
Short - sightedness, 
or myopia, usually de- 
pends upon congenital, 
and frequently hereditary, 
elongation of the eyeball. 
This anomaly of the re- 
fractive media is easily 
corrected by using a 
diverging lens (con- 
cave), which makes par- 
allel rays divergent, so 
that they can then be 
brought to a focus on the retina. It is remarkable that most children are 
myopic when they are born. This myopia, however, depends upon a too 
curved condition of the cornea and 
lens, and on the lens being too near 
to the cornea. As the eye grows, 
this short-sightedness disappears. 
Amongst the causes of myopia in 
children are the continued activity 
of the ciliary muscle in reading, 
writing, etc., especially in a bad 
light, or when the reader is in an 
awkward position, or the continued 
convergence of the eyeballs, where- 
by the external pressure upon the 
eyeball is increased. 
3. The long-sighted or hypermetropic eye, hyperoptic (“ flat eye ”) 
when at rest, can only cause convergent rays to come to a focus on the retina 
(fig. 667). Distinct images can only be formed when the rays proceeding from 
objects are rendered convergent by means of a convex lens, as parallel rays 
would come to a focus behind the retina (at/). All rays proceeding from 
natural objects are either divergent, or at most nearly parallel, never convergent. 
Hence, a long-sighted person, when the eye is passive, i. <?., is negatively ac- 
commodated, cannot see distinctly without a convex lens. When the ciliary 
muscle contracts, slightly convergent, parallel, and even slightly divergent rays 
may be focussed, according to the increasing degree of the accommodation. 
The far point of the eye is negative, the near point abnormally distant (over 
8 to 80 inches), while the range of accommodation is infinitely great. 
The cause of hypermetropia is abnormal shortness of the eye, which is 
generally due to imperfect development in all directions. It is corrected by 
using a convex lens. 
Fig. 666. 
Myopic eye. 
Hypermetropic eye. 
Fig. 667. 960 
snellen’s types. 
[Sec. 388. 
[Defective Accommodation.—In the presbyopic eye, or long-sighted 
eye of old people, the near point is farther away than normal, but the far 
point is still unaffected. In such cases, the person cannot see a near object dis- 
tinctly, unless it be held at a considerable distance from the eye. It is due to 
a defect in the mechanism of accommodation, the lens becoming somewhat 
flatter, less elastic, and denser with old age, while the ciliary muscle becomes 
weaker. In hypermetropia, on the contrary, the mechanism of accommodation 
may be perfect, yet from the shape of the eye the person cannot focus on his 
retina the rays of light from a near object. In presbyopia the range of distinct 
vision is diminished. The defect is remedied by weak convex glasses. The 
defect usually begins about forty-five years of age.] 
Estimation of the Far Point—Snellen’s Types.—In order to determine the far point of 
an eye, gradually bring nearer to the eye objects which form a visual angle of 5 minutes (e.g., 
Snellen’s small type letters, or the medium type, 4 to 8, of Jaeger), until they can be seen dis- 
tinctly. The distance from the eye indicates the far point. In order to determine the far point 
of a myopic person, place at 20 inches distant from the eye the same objects which give a visual 
angle of 5 minutes, and ascertain the concave lens which will enable the person to see the objects 
distinctly. To estimate the near point, bring small objects (e. g., the finest print) nearer and 
nearer to the eye, until it finally becomes indistinct. The distance at which one can still see 
distinctly indicates the near point. 
Optometer.—The optometer may also be used to determine the near and far points. A 
small object, e.g., a needle, is so arranged as to be movable along a scale, along which the eye 
to be investigated can look as a person looks along the sight of a rifle. The needle is moved as 
near as possible, and then removed as far as possible, in each case as long as it is seen distinctly. 
The distance of the near and far point and the range of accommodation can be read off directly 
upon the scale (Grafe). 
389. FORCE OF ACCOMMODATION.—Force.—The range of accommodation, which 
is easily determined experimentally, does not by itself determine the proper power or force of 
accommodation. The measure of the latter depends upon the mechanical work done by the 
muscle of accommodation, or the ciliary muscle. Of course this cannot be directly determined 
in the eye itself. Hence, this force 
is measured by the optical effect, 
which results in consequence of the 
change in the shape of the lens, 
brought about by the energy of the 
contracting muscle. 
In the normal eye, during the 
passive condition, the rays coming 
from infinity, and therefore parallel 
(which are dotted in fig. 668), are 
focussed upon the retina at f If 
rays coming from a distance of 5 
inches (p. 958) are to be focussed, 
the whole available energy of the ciliary muscle must be brought into play to allow the lens 
to become more convex, so that the rays may be brought to a focus at f The energy of 
accommodation, therefore, produces an optical effect in as far as it increases the convexity 
of the anterior surface of the passive lens (A), by the amount indicated by B. Practically, 
we may regard the matter as if a new convex lens (B) were added to the existing convex 
lens (A). What, therefore, must be the focal distance of the lens (B), in order that rays 
coming from the near point (5 inches) may be focussed upon the retina at f ? Evidently 
the lens B must make the diverging rays coming from p, parallel, and then A can focus 
them at f Convex lenses cause those rays proceeding from their focal points to pass out at 
the other side as parallel rays (g 385, I). Hence, in our case, the lens must have a focal distance 
of 5 inches. The normal eye, therefore, with the far point = 00, and the near point = 5 
inches, has a power of accommodation equal to a lens of 5 inches focal distance. When the 
lens by the energy of accommodation is rendered more powerfully refractive, the increase (B) 
can readily be eliminated by placing before the eye a concave lens which possesses exactly the 
opposite optical effect of the increase of accommodation (B). Hence it is possible to indicate 
the power (force) of accommodation of the eye by a lens of a definite focal distance, i. e., by the 
optical effect produced by the latter. Therefore, according to Donders, the measure of the force 
of accommodation of the eye is the reciprocal value of the focal distance of a concave lens, 
Fig. 668. Sec. 389.] 
FORCE AND RANGE OF ACCOMMODATION. 
961 
which, when placed before the accommodated eye, so refracts the rays of light coming from the 
near point (/) as if they came from the far point. 
Example.—We may calculate the force of the accommodation according to the following 
1 i 1 
formula: — = — i. <?., the force of accommodation, expressed as the dioptric value of a 
lens (of x inch focal distance), is equal to the difference of the reciprocal values of the dis- 
tances of the near point (/) and of the far point (r) of the eye. In the emmetropic eye, 
I i i 
as already mentioned, t> = z, r — oo . Its force of accommodation is therefore = , — —- 
J J x p oo 
so that x = 5, i. <?., it is equal to a lens of 5 inches focal distance. In a myopic eye, / = 4, 
III 
r — 12, so that — = — —2, i. e., x — 6. In another myopic eye, with p — 4 and r = 20, then 
x — 5, which is a normal force of accommodation. Hence, it is evident that two different eyes, 
possessing a very different range of accommodation, may nevertheless have the same force of 
accommodation. Example.—The one eye has / = 4, r= 00 , the other, / = 2, r — 4. In 
1 1 
both cases, — = —, so that the force of accommodation of both eyes is equal to the dioptric 
value of a lens of 4 inches focal distance. Conversely, two eyes may have the same range of 
accommodation, and yet their force of accommodation be very unequal. Example.—The one 
eye has / = 3, r = 6; the other / = 6, r = 9. Both, therefore, have a range of accommoda- 
1 1 1 
tion of 3 inches. For these, the force of accommodation, — = — — x = 6; and 
o ’ ’ x 3 6 * ’ 
1 1 1 
— —~z — - , X = 18. 
x o 9 
Relation of Range to Force of Accommodation.—The general law is, that the ranges 
of accommodation of two eyes being equally great, then their forces of accommodation are equal, 
provided that their near points are the same. If the ranges of accommodation for both eyes 
are equally great, but their near points unequal, then the forces of accommodation are also un- 
equal—the latter being greater in the eyes with the smallest near point. This is due to the 
fact that every difference of distance near a lens has a much greater effect upon the image as 
compared with differences in the distance far from a lens. The emmetropic eye can see dis- 
tinctly objects at 60 to 70 metres, and even to infinity, without accommodation. 
While / and r may be directly estimated in the emmetropic and myopic eyes, this is impos- 
sible with the hypermetropic (long-sighted) eye. The far point in the latter is negative; indeed, 
in very pronounced hypermetropia even the near point may be negative. The far point may 
be estimated by making the hypermetropic eye practically a normal eye by using suitable convex 
lenses. The relative near point may then be determined by means of the lens. 
Even from the 15th year onwards the power of accommodation is greatly diminished for 
near objects—perhaps this is due to a diminution of the elasticity of the lens (Donders). 
390. SPECTACLES. —The focal distance of concave (diverging), as well as convex (con- 
verging) spectacles, depends upon the refractive index of the glass (usually 3:2), and on the 
length of the radius of curvature. If the curvature of both sides of the lens is the same (bicon- 
cave or biconvex), then with the ordinary refractive index of glass, the focal distance is the same 
as the radius of curvature. If one surface of the lens is plane, then the focal distance is twice as 
great as the radius of the spherical surface. Spectacles are arranged according to their focal 
distance in inches, but a lens of shorter focal distance than 1 inch is generally not used. They 
may also be arranged according to their refractive power. In this case, the refractive power of 
a lens of I inch focus is taken as the unit. A lens of 2 inches focus refracts light only half as 
much as the unit measure of 1 inch focus; a lens of 3 inches focus refracts as strongly, etc. 
This is the case both with convex and concave lenses, the latter, of course, having a negative 
focal distance ; thus, “concave—indicates that a concave lens diverges the rays of light one- 
eighth as strongly as the concave lens of 1 inch (negative) focal distance. 
Choice of Spectacles.—Having determined the near point in a myopic eye, of course we 
require to render parallel the divergent rays coming from the far point, just as if they came 
from infinity. This is done by selecting a concave lens of the focal distance of the far point. 
The greatest distance is the far point of the emmetropic eye. Suppose a myopic eye with a far 
point of 6 inches, then such a person requires a concave lens of 6 inches focus to enable him to 
see distinctly at the greatest distance. Thus, in a myopic eye, the distance of the far point from 
the eye is directly equal to the focus of the (weakest) concave lens, which enables one to see 
distinctly objects at the greatest distance. These lenses generally have the same number as the 
spectacles required to correct the defect. Example.—A myopic eye with a far point of 8 
inches requires a concave lens of 8 inches focus, i. e., the concave spectacles No. 8. For the 
hypermetropic (long-sighted) eye, the focal distance of the strongest convex lens, which 962 
DIOPTRICS AND CHROMATIC ABERRATION. 
[Sec. 390. 
enables the hypermetropic eye to see the most distant objects distinctly, is at the same time the 
distance of the far point from the eye. Example,—A hypermetropic eye which can see the 
most distant objects with the aid of a convex lens of 12 inches focus has a far point of 12; the 
proper spectacles are convex No. 12. 
[Diopter or Dioptric.—The focal length of a lens used to be expressed in 
inches ; and as the unit was taken as 1 inch, necessarily all weaker lenses were 
expressed in fractions of an inch. In the method advocated by Donders, the 
standard is a lens of a focal distance of 1 metre (39.370 English inches, about 
40 inches), and this unit is called a dioptric. Thus, the standard is a weak 
lens, so that the stronger lenses are multiples of this. Hence, a lens of 2 
dioptrics = one of about 20 inches focus; 10 dioptrics = 4 inches focus ; and 
so on. The lenses are numbered from No. 1, /. <?., 1 dioptric, onwards. It is 
convenient to use signs instead of the words convex and concave. For con- 
vex the sign plus -f- is used, and for concave the sign minus —. Thus a -f- 4.0 
means a convex lens of 4 dioptrics, and a — 4.0 = a concave lens of 4 diop- 
trics.] 
In all cases of myopia or hypermetropia, the person ought to wear the proper spectacles. In 
a myopic eye, when the far point is still more than 5 inches, the patient ought always to wear 
spectacles; but generally the working distance, e. g., for reading, writing, and for handicrafts, 
is about twelve inches from the eye. If the person desires to do finer work (etching, drawing), 
requiring the object to be brought nearer to the eye, so as to obtain a larger image upon the 
retina, then he should either remove the spectacles altogether or use a weaker pair. 
The hypermetropic person ought to wear his convex spectacles when looking at a near 
object, and especially when the illumination is feeble, because then, owing to the dilatation of 
the pupil, the diffusion circles of the eye tend to become very pronounced. It is advisable to 
wear at first convex spectacles which are slightly too strong. Cylindrical lenses are referred 
to under Astigmatism. Spectacles provided with dull-colored or blue glasses are used to pro- 
tect the retina when the light is too intense. Stenopaic spectacles are narrow diaphragms 
placed in the front of the eye, which cause it to move in a definite direction in order to see 
through the opening of the diaphragm. 
391. CHROMATIC AND SPHERICAL ABERRATION, AS- 
TIGMATISM.—Chromatic Aberration.—All the rays of white light, 
which undergo refraction, are at the same time broken up by dispersion into 
a bundle of rays which, when they are received on a screen, form a spectrum. 
This is due to the fact that the different colors of the spectrum possess differ- 
ent degrees of refrangibility. The violent rays are refracted most strongly; 
the red rays least. 
A white point on a black ground does not form a sharp simple image on the retina, but many 
colored points appear after each other. If the eye is accommodated so strongly as to focus the 
violet rays to a sharp image, then all the other colors must form concentric diffusion circles, 
which become larger towards the red. In the centre of all the circles, where all the colors of 
the spectrum are superposed, a white point is produced by their mixture, while around it are 
placed the colored circles. The distance of the focus of the red rays from that of the violet in 
the eye = 0.58 to 0.62 mm. The focal distance for red is, according to v. Helmholtz, for the 
reduced eye, 30.524 mm.; for violet, 20.140 mm. Thus, the near and far points for violet 
light are nearer each other than in the case of red light; white objects, therefore, appear red- 
dish when beyond the far point, but when nearer than the near point they are violet. Hence, 
the eye must accommodate more strongly for red rays than for violet, so that we judge red 
objects to be nearer us than violet objects placed at an equal distance (Briicke). 
Monochromatic, or Spherical Aberration.—Apart from the decomposition or dispersion 
of white light into its components—the rays of white light proceeding from a point, if trans- 
mitted through refractive spherical surfaces—we find that, before the rays are again brought to 
a focus, the marginal rays are more strongly refracted than those passing through the central 
parts of the lens. Hence, there is not one focus but many. In the eye this defect is naturally 
corrected by the iris, which, acting as a diaphragm, cuts off the marginal rays (fig. 658), 
especially when the lens is most convex, when the pupil also is most contracted. In addition, 
the margin of the lens has less refractive power than the central substance; lastly, the margins 
of the refractive spherical surfaces of the eye are less curved towards their margins than the 
parts lying nearer to the optical axis. Compare the form of the cornea (p. 933) and the lens 
(P- 943). Sec. 391.] 
ASTIGMATISM. 
963 
Imperfect Centring of the Refractive Surfaces.—The sharp projection of an image is 
somewhat interfered with by the fact that the refractive surfaces are not exactly centred 
(Briicke). Thus, the vertex of the cornea is not exactly in the termination of the optic axis; 
the vertices of both surfaces of the lens, and even the different layers of the lens itself, are not 
exactly in the optic axis. The variations, however, and the disturbances produced thereby, are 
very small indeed. 
Regular Astigmatism.—When the curvature of the refractive surfaces of 
the eye is unequally great in its different meridians, of course the rays of light 
cannot be united or focussed in one point. Generally, in such cases, the cornea 
is more curved in its vertical meridian and least in the horizontal (as is shown 
by ophthalmometric measurements, p. 953). The rays passing through the 
vertical meridian come to a focus, first, in a horizontal focal line ; while the 
rays entering horizontally unite afterwards in a vertical line. There is thus no 
common focus for the light-rays in the eye ; hence the name “ astigmatism.” 
Action of an astigmatic surface on a cone of light (Frost). 
Fig. 669. 
The lens also is unequally curved in its meridians, but it is the reverse of the 
cornea; consequently, a part of the inequality of the curvature of the cornea 
is thereby compensated, and only a part of it affects the rays of light. The 
emmetropic eye has a very slight degree of this inequality (normal astig- 
matism). If two very fine lines of equal thickness be drawn on white paper, 
so as to intersect each other at right angles, it will be found that, in order to 
see the horizontal line quite sharply, the paper must be brought slightly nearer 
to the eye, than when we focus the vertical line. When the inequality of cur- 
vature of the meridians is considerable, of course exact vision is no longer 
possible. 
Fig. 669 shows the effect of an astigmatic surface on the rays of light. Let abed be such 
a surface, and suppose diverging rays to proceed from f. The rays passing 
through c d come to a focus at fv while those passing through the vertical 
meridian are focussed at fv The outline of the cone of rays between abed 
and varies, as shown in the figure. At a certain part it is oval, with 
its axis vertical, at another the long axis of the oval is horizontal, while at 
other places it is circular, or the rays are focussed in a horizontal or vertical 
line.] 
Correction of Astigmatism.—This condition is corrected by a cylin- 
drical lens, i.e., a lens so cut as to be without curvature in one direction, 
while in the other direction (vertical to the former) it is curved. The lens 
is placed in front of the eye, so that the direction of its curvature coincides 
with the direction of least curvature of the eye (v. Helmholtz, Knapp, 
Donders). The section C a b c d of the cylindrical lens (fig. 670) repre- 
sents a plano-convex, the section C a /? y 6, a concavo-convex lens. 
[Test.—Draw two lines of equal thickness at right angles to each other. 
An astigmatic person cannot see both lines with equal distinctness at the 
same time, one line will appear thicker than the other. Or a series of lines 
radiating from a centre maybe used (astigmatic clock, fig. 671) when 
that line which is parallel to the astigmatic meridian will be seen most 
distinctly; while, with the vertical meridian most curved, it would be the 
vertical line.] 
Irregular Astigmatism.—Owing to the radiate arrangement of the fibres in the interior of 
Fig. 670. 
Cylindrical glasses 
for astigmatism. 964 
THE IRIS. 
[Sec. 391. 
the crystalline lens, and in consequence of the unequal course of the fibres within the different 
parts of one and the same meridian of the lens, the rays of light passing through one meridian 
of the lens cannot all be brought to one focus. Hence, we do not obtain a distinct, sharp 
image of distant luminous points, such as stars or street lamps, but we see a radiate jagged 
figure provided with rays. The same obtains on holding a piece of cardboard with a small 
hole in it towards the light, at a distance from the eye slightly greater than the far point. 
Slight degrees of this irregular astigmatism are normal, but when it is highly developed it greatly 
interferes with vision, by forming several foci of an object instead of one (Polyopia monocu- 
laris). Of course this condition cannot obtain in an eye devoid of a lens. 
392. Iris.—Functions.—1. The iris acts like a diaphragm in an optical 
apparatus by cutting off the marginal rays, which, if they entered the eye, 
would cause spherical aberration, and thus produce indistinct vision (fig. 658). 
2. As the pupil contracts strongly in a bright light, and dilates when the 
light is feeble, it regulates the amount of light entering the eye ; thus, 
fewer rays enter the eye when the light is strong than when it is feeble. 
3. To a certain extent it supports 
the action of the ciliary muscle. 
Muscles and Nerves.—The iris 
is usually described as being provided 
with two sets of muscular fibres— 
the sphincter, which immediately 
surrounds the pupil and is supplied 
by the oculomotorius (§ 345, 2), and 
the dilator pupillae (p. 937), sup- 
plied chiefly by the cervical sympa- 
thetic (§ 356, A, 1), and the trige- 
minus (§ 347, 3). Both muscles 
stand in an antagonistic relation to 
each other (§ 345), the pupil dilates 
moderately after section or paralysis 
of the oculomotorius, owing to the 
contraction of the dilator fibres which 
are supplied by the cervical sympa- 
thetic ; conversely the pupil contracts 
when the sympathetic is divided or 
extirpated {Petit, 1727). When both 
nerves are stimulated simultaneously, the pupil contracts, so that the excitability 
of the oculomotorius overcomes the sympathetic. 
[The existence of a dilator pupillae muscle is not universally recognized, and in fact 
some observers doubt its existence. The muscular nature of the radial fibres in the posterior 
limiting membrane of the iris is denied by Griinhagen, while Koganei regards these as in no 
case muscular, and the dilating fibres as represented by fibres radiating from the iris. These 
fibres are well developed in birds and the otter, exist in traces in the rabbit, and are absent in 
man. Gaskell points out that in this case the size of the pupil must in part depend on the 
elasticity of the radial fibres of the iris, while the dilator nerve-fibres must act on the sphincter 
fibres, causing them to relax. Gaskell groups the sphincter of the iris with those muscles 
“ supplied by two nerves of opposite character, the one motor, the other inhibitory.” The 
dilatation of the pupil caused by stimulation of the cervical sympathetic is usually explained by 
the hypothesis that this nerve contains motor fibres, which act on the dilator fibres. Griinhagen 
thought that it might be due chiefly to the constriction of the blood-vessels of the iris; Gaskell 
suggests that the nerve acts on the sphincter muscle, and is the inhibitory nerve of that muscle, 
dilatation taking place because the sphincter is normally in a condition of tonic contraction, and 
also because the posterior limiting membrane is elastic.] 
Nerves of the Iris.—Arnstein and A. Meyer have studied the mode of termination of the 
nerve-fibres in the iris. All the medullated nerve-fibres lose their white sheaths after a time ; 
most of the fibres [motor) in the region of the sphincter consist of naked bundles of fibrils. A 
network of very delicate sensory nerves lies under the anterior epithelium. Numerous fibrils 
pass to the capillaries and arteries as vaso-molor nerves. [Many ganglionic cells are intercalated 
in the course of the fibres.] 
Astigmatic clock for testing astigmatism. 
Fig. 671. Sec. 392.] 
THE PUPIL. 
965 
Movements of the iris occur under the following conditions:— 
1. Action of light on the retina causes (according to its intensity and 
amount) a corresponding contraction of the pupil; the same effect is pro- 
duced by stimulation of the optic nerve itself {Herbert Mayo'). This movement 
is a reflex act [the afferent nerve being the optic and the efferent the oculomo- 
torius; the impulse is transferred from the former to the latter in a centre 
situated somewhere below the corpora quadrigemina (fig. 672, C)]. 
The older observers locate the centre in the corpora quadrigemina, the recent observers in the 
medulla oblongata ($ 362). Both pupils always react, although only one retina be stimulated; 
generally under normal circumstances both contract to the same extent (.Bonders), owing to the 
intercentral communication [coupling] of the two pupillo-constricting centres. [This is called 
consensual contraction of the pupil.] After section of the optic nerve the pupil dilates, and 
subsequent section of the oculomotorius no longer produces any further dilatation (Knoll). 
2. The centre for the dilator fibres of the pupil (pupillo-dilating centre) is excited by 
dyspnceic blood (§ 367, 8). If the dyspnoea ultimately passes into asphyxia, the dilatation of the 
pupil diminishes. Of course, if the peripheral dilating fibres (§ 247, 3) [e. g., the sympathetic 
nerve in the neck] be previously divided, this effect cannot take place, as the dyspnceic blood 
acts on the centre and not on the nerve-fibres. 
3. The centre, as well as the subordinate “ cilio-spinal region ” of the spinal cord (§ 362, 
1), is also capable of being excited reflexly; painful stimulation of sensory nerves, in addition 
to causing protrusion of the eyeballs ($ 347), a fact proved in the case of persons subjected to 
torture, produces dilatation of the pupils (Arndt, Bernard, IVestphal, Luchsinger); while a 
similar effect is caused by labor pains, a loud call in the ear, stimulation of the nerves of the 
sexual organs, and even by slight tactile impressions (Fod and Schiff). According to Bechterew, 
the foregoing results are due to inhibition of the light-reflex in the sense expressed in $ 361, 3. 
4. The condition of the blood-vessels of the iris influences the size of the pupil; all condi- 
tions causing injection or congestion of these vessels contract the pupil, all conditions diminish- 
ing them dilate it. The pupil, therefore, is contracted by forced expiration, which prevents 
the return of venous blood from the head ; momentarily by every pulse-beat, owing to the dias- 
tolic filling of the arteries; diminution of the intraocular pressure, e. g., after puncture of the 
anterior chamber, because, owing to the diminished intraocular pressure, there is less resistance 
to the passage of blood into the blood-vessels of the iris (Hensen and Volckers); paralysis of the 
vaso-motor fibres of the iris (§ 347, 2). Conversely, the pupil is dilated by conditions the reverse 
of those already mentioned, and also by strong muscular exertion, whereby blood flows freely 
into the dilated muscular blood-vessels; also, when death takes place. The condition of the fill- 
ing of the blood-vessels also explains the fact that the pupil dilated with atropin becomes smaller 
when a part of the sympathetic in the upper cervical ganglion, carrying the vaso-motor fibres of 
the iris, is excised; also, that after extirpation of this ganglion, atropin always causes a less 
diminution of the pupil on this side. The fact that when the pupil is already dilated by 
stimulation of the sympathetic, it is further dilated by atropin, is due to a diminished injection 
of the blood-vessels of the iris. If an animal with its pupils dilated with atropin be rapidly 
bled, the pupils contract, owing to the anaemic stimulation of the origin of the oculomotorius 
(Moriggia). The dilatation of the pupils observed in cases of neuralgia of the trigeminus is 
partly due to the stimulation of the dilating fibres, partly to the stimulation of the vaso-motor 
fibres of the iris ($ 347, 2). 
5. Contraction of the pupil occurs as an associated movement, 
during accommodation for a near object (p. 957, 5), and when the eyeballs are 
rotated inwards, which is the case during sleep (p. 872). 
Conversely, intense movements of the iris, caused by variations in the brightness of dazzling 
illumination, e. g., of the electric light, are followed by disturbing associated movements of the 
ciliary muscle (Ljubinsky). In certain movements discharged from the medulla oblongata 
(forced respiration, chewing, swallowing, vomiting), dilatation of the pupil occurs as a kind of 
associated movement. 
[Argyll Robertson Pupil.—In this condition the pupil does not contract 
to light, although it contracts when the eye is accommodated for a near object, 
vision usually being normal.] 
[The lesion is situated in those structures connecting the afferent and efferent fibres at their 
central ends (at A in fig. 672), i. e., the connection between the corpora quadrigemina and the 
oculomotorius. It is most frequently found in locomotor ataxia, although it also occurs in pro- 
gressive paralysis of the insane.] 966 
ACTION OF DRUGS ON THE PUPIL. 
[Sec. 392. 
Direct stimulation at the margin of the cornea causes dilatation of the pupil {£. H. Weber) 
in fact, direct stimulation of circumscribed areas of the margin of the iris causes partial con- 
traction of the dilator fibres (.Bernstein and Dogiel). Stimulation near the centre of the cornea 
contracts the pupil (E. H. Weber). In addition, we must assume that the iris itself contains 
elements that influence the diameter of the pupil {Sig. Mayer and Pribram). 
Our knowledge of the action of drugs on the iris is still very obscure. 
Those substances which dilate the pupil are called mydriatics, e. g., atropin, 
homatropin, duboisin, daturin, and hyoscyamin. 
They act chiefly by paralyzing the oculomotorius. But, in addition, there must be also an 
effect upon the dilating fibres, for after complete paralysis (section) of the oculomotorius, the 
moderate dilatation of the pupil thereby produced (§ 345, 5) is still further increased by 
atropin. Minimal doses of atropin contract the pupil, owing to stimulation of the pupillo- 
constrictor fibres; enormous doses cause moderate dilatation of the pupil in consequence of 
paralysis of the dilating as well as of the constricting nerve-fibres. Atropin acts after destruc- 
tion of the ciliary [ophthalmic] ganglion (Hensen 
and Volckers) [and division of all the nerves 
except the optic], and in the excised eye (De 
Ruyter), [so that atropin is a local mydriatic. 
In moderate doses it paralyzes the nervous 
terminations of the 3d nerve (but not in birds 
whose iris contains striped muscle), and in larger 
doses it also paralyzes the muscular fibres]. 
[Cocaine, or cucaine, is obtained from the leaves 
of Erythroxylon coca. When applied locally it 
acts as a powerful local anaesthetic, and hence it 
is very useful for operations about the muco- 
cutaneous orifices. A 4 per cent, solution 
dropped into the eye produces complete insensi- 
bility of the cornea in a few minutes. It causes 
dilatation of the pupils, though they react to 
light and to the movements of accommodation. 
It also causes temporary paralysis of accommo- 
dation, a sensation of heaviness and coldness of 
the eyeball, enlargement of the palpebral fissure, 
constriction of the small peripheral vessels, and 
slight lachrymation.] 
Myotics are those substances which 
contract the pupil: Physostigmin 
(= Eserin, the alkaloid of Calabar bean), 
nicotin, pilocarpin, muscarin, morphia, 
according to some observers ( Griinhagen) 
cause stimulation of the oculomotorius 
while others say they paralyze the sympa- 
thetic. 
As these substances cause spasm of the ciliary 
muscle, it is supposed that the first of these 
has an analogous action on the sphincter. It is probable that they paralyze the dilator fibres 
and stimulate the oculomotor fibres. [Amongst local myotics, i. <?., those which act on the eye, 
some act on the muscular fibres of the iris, e. g., physostigmin or eserin, while others act on the 
peripheral terminations of the 3d nerve, e.g., pilocarpin, muscarin. Muscarin causes very great 
contraction of the pupil from spasm of the circular fibres, due to its action on the 3d nerve; 
eserin, on the other hand, although contracting the pupil, also affects the dilator fibres. The 
contraction of the pupil due to opium is central in its cause.] 
If the one pupil be contracted or dilated by these substances the other pupil conversely is 
dilated or contracted, owing to the change in the amount of light admitted into the eye into 
which the poison has been introduced. The anaesthetics (ether, chloroform, alcohol, etc.), when 
they begin to cause stupor, contract the pupil, and when their action is intense they dilate it 
{Dogiel). Chloroform, during the stage when it causes excitement (preceding the narcosis), 
stimulates the centre for the dilatation of the pupil; after a time this centre is paralyzed, so that 
the pupil no longer dilates on the application of external stimuli. Thereafter the pupillo-con- 
Scheme of the nerves of the iris. B, centrum 
optici; C, oculomotor centre; D, dilator 
centre (spinal); E, iris ; G, optic nerve; 
H, oculomotor (sphincter) roots ; I, sym- 
pathetic (dilator); K, L, anterior roots; 
M, N, O, posterior roots ; A, seat of lesion, 
causing pupillary immobility; * probable 
seat of lesion, causing myosis. 
Fig. 672. Sec. 392.] 
PUPILOMETER. 
967 
stricter centre is stimulated, whereby the pupil maybe contracted to the size of a pin’s head; 
ultimately this centre is paralyzed, and the pupil becomes dilated. 
Intraocular Pressure.—The movements of the iris are always accompanied by variations of 
the intraocular pressure. The muscles of the iris affect the intraocular pressure, in that the 
dilatation of the pupil increases it, while contraction of the pupil diminishes it. The increased 
or diminished tension can be felt when two fingers are pressed on the eyeball. Stimulation of 
the sympathetic increases, while its section diminishes the pressure. Action of Drugs.— 
Atropin dropped into the eye, after producing a short temporary diminution of the tension, in- 
creases it; eserin, after a primary increase, causes a diminution of the pressure (Graser and 
Holzle). According to Hocker, atropin diminishes the intraocular pressure, eserin first increases 
it and then diminishes it. 
Time for Movements of Iris.—The reflex dilatation of the pupil occurs slightly later 
than the reflex contraction, the time in the two cases being 0.5 and 0.3 second respectively, after 
stimulation by light (v. Vintschgan). A certain time always elapses, until the iris, correspond- 
ing to the strength of the stimulus of light exciting the retina, “ adapts ” itself to produce a suitable 
size of the pupil (Aubert). Contraction of the pupil occurs very rapidly after stimulation of the 
oculomotorius in birds; in rabbits 0.89 second elapses after stimulation of the sympathetic, until 
the dilatation begins (Arlt). 
Action of Light on Excised Eye.—Light causes contraction of the pupil 
in the excised eye of amphibians and fishes (Arnold). Even the iris of the eel, 
when cut out and placed in normal saline solution, contracts to light (Arnold), 
the green and blue rays being most active. Increase of the temperature causes 
mvdriasis in the excised eye of the frog or eel, while cooling causes myosis (H. 
Miiller). 
[Size of the Pupil.—A pupilometer consists of a metal plate perforated with a series of 
holes of different sizes (fig. 
673). The plate is placed 
just below the patient's 
eye, and the hole is 
selected which corre- 
sponds with the size of 
the pupil.] 
[Gorham’s Pupil 
Photometer.—This in- 
genious instrument may 
be used as a pupilome- 
ter, and also as a photometer. It consists of a piece of bronzed tubing 1.9 in. long and 1.5 
in. diameter (figs. 674 and 675). One end is closed by a disc or cap, which is pierced in its radii 
by a series of holes at distances varying from .05 in. to .28 in. There is a slot in the cap, which 
Fig. 673. 
Pupilometer of Edgar Browne. 
Gorham’s pupil photometer. Fig. 674 shows the disc with a slot and two holes. Fig. 675 gives 
a side view with the diameter of the pupil marked on it. The upper end is closed by the 
disc, while the lower end is open. 
Fig. 674. 
Fig. 675. 
allows one pair of holes to be visible at a time, while on the cylinder is engraved the linear dis- 
tance of each pair of holes. In using the instrument as a pupilometer, look through the open 
end of the tube (the bottom in fig. 675), with both eyes open, towards a sheet of white paper or 968 
ENTOPTICAL PHENOMENA. 
[Sec. 392. 
the sky, when two discs of light will be seen. Then revolve the lid or cap slowly until the two 
white discsywi'/ touch one another at their edges. The decimal fraction opposite the two apertures 
seen on the scale outside indicates the diameter of the pupil in iooths of an inch. When using 
it as a photometer, it is assumed that the size of the pupil gives an index of the intensity of the 
amount of light which influences the diameter of the pupil.] 
[The following table from Beaunis shows the chief conditions which affect 
the pupil:— 
Contraction of the Pupil. 
Stimulation of the optic nerve. 
Stimulation of the third cranial nerve. 
Section of the fifth cranial nerve. 
Section or paralysis of the cervical sym- 
pathetic. 
Paralysis of the vaso-motor fibres of the 
iris. 
Filling of the vessels of the iris. 
Light acting on the retina, or directly on 
the iris. 
Accommodation for a near object. 
Rotation of the eyeball inwards. 
Diminution of intra-ocular pressure. 
Puncture of the anterior chamber. 
Expiration. 
Sleep. 
Myotics (Calabar bean, nicotin, opium). 
Anaesthetics (at first). 
Heat. 
Dilatation of the Pupil. 
Section of the optic nerve. 
Paralysis of the third cranial nerve. 
Stimulation of the fifth cranial nerve. 
Stimulation of the sympathetic. 
Stimulation of the vaso motor fibres of 
the iris. 
Contraction of the vessels of the iris. 
Stimulation of sensory nerves. 
Vision of distant objects. 
Rotation of the eyeball outwards 
Increase of the intra ocular pressure. 
Stimulation of the margin of the iris or 
cornea. 
Inspiration, dyspnoea, asphyxia. 
Syncope and approach of death. 
Mydriatics (atropin). 
Anaesthetics (at the end). 
Cold. 
Strong muscular contraction.] 
Fig. 676. 
Entoptical Shadows. 
393. ENTOPTICAL PHENOMENA.—Entoptical phenomena 
depend upon the perception of objects present within the eyeball itself. 
I. Shadows are formed upon the retina by different opaque bodies. In order to see them in 
one’s own eye, proceed thus: By means of a strong convex lens project a small image of a flame 
upon a paper screen, prick a small opening through the image of the flame, and place one eye 
at the other side of the screen, so that the illuminated puncture lies in the anterior focus of the 
eye, i. <?., about 13 mm. in front of the cornea. As the rays proceeding from this point pass 
parallel through the media of the eye, a diffuse bright field of vision, surrounded by the black 
margins of the iris, is obtained. All dark bodies which lie in the course of the rays of light 
throw a shadow upon the retina, and appear as specks. There are various kinds of these shadows 
(fig. 676):— 
(a) The spectrum mucro-lacrimale, especially upon the margin of the eyelids, depending 
upon particles of mucus, fat globules from the Meibomian glands, dust mixed with tears, causing 
cloudy or drop-like retinal shadows, which are removed by winking. 
(b) Folds in the Cornea.—If the cornea be pressed laterally with the finger, wrinkled shad- 
ows, due to temporary wrinkles in the cornea, are produced. Sec. 393.] 
ENTOPTICAL PHENOMENA. 
969 
(c) Lens Shadows.—Bead-like or dark specks, bright and star-like figures, the former due 
to deposits on and in the lens, the latter to the radiate structure of the lens. 
(d) Muscae volitantes (Dechales, 1690), like strings of beads, circles, groups of balls or 
pale stripes, depend upon opaque particles (cells, disintegrating cells, granular fibres) in the 
vitreous humor. They move about when the eye is moved rapidly. Listing [1845] showed 
that one may determine pretty accurately the position of these objects. Whilst making the obser- 
vation upon one’s own eyes, raise or depress the source of light; those shadows which are 
caused by bodies on a level with the pupil retain their relative positions in the bright fields of 
vision. Shadows which appear to move in the same direction as the source of light are caused 
by bodies which lie in front of the plane of the pupil—those, however, which appear to move in 
the opposite direction, depend upon objects behind the plane of the pupil. 
2. Purkinje’s figure (1819) depends upon the blood-vessels within the retina, which cast 
a shadow upon the most external layer of the retina, viz., upon the rods and cones, these being 
the parts acted upon by light. In ordinary vision we do not observe these shadows. According 
to v. Helmholtz, this is due to the fact that the sensibility of the shaded parts of the retina is 
greater, and their excitability is less exhausted than all the other parts of the retina. As soon, 
however, as we change the position of the shadow of the blood-vessels, instead of being directly 
behind, so that the blood-vessels come to lie more laterally and behind them, i.e., upon places 
which do not receive shadows from the blood-vessels when the rays of light pass through the 
eye in the ordinary way, then the figure of the blood-vessels becomes apparent at once. All that 
is necessary is to cause the light to enter the eyeball obliquely. Methods.—(1) This may be 
done by passing an intense light through the sclerotic, e. g., by throwing upon the sclerotic a 
small, bright, luminous image from a source of light. On moving the source of light, the figure 
of the blood-vessels moves in the same direction. (2) Look directly upwards to the sky, wink 
with the upper eyelid drooping, so that for a moment, corresponding to the act of winking, rays 
of light enter obliquely the lowest part of the pupils. (3) Look through a small aperture towards 
a bright sky, and move the aperture rapidly to and fro, so that from both sides of the blood-vessels 
shadows fall rapidly upon the nearest series of rods and cones. (4) In a darkened room look 
straight ahead, and move a light to and fro close under the eyes. Occasionally, whilst performing 
this experiment, one may see the macula lutea as a non-vascular shaded depression, and owing 
to the inversion of the objects, it lies on the inner side of the entrance of the optic nerve. 
3. Movements of the Blood-corpuscles in the Retinal Capillaries.—On looking, without 
accommodating the eye, towards a large bright surface, or through a dark blue glass towards the 
sun, we see bright spots, like points, forming longer or shorter chains, moving in tortuous paths. 
The phenomenon is, perhaps, caused by the red blood-corpuscles (in the capillaries posterior to 
the external granular layer) acting as small light-collecting concave discs, concentrating the light 
falling upon them from bright surfaces, and throwing it upon the rods of the retina. Each corpuscle 
must be in a special position; should it rotate, the phenomenon disappears. Vierordt, who 
projected the movement upon a screen, calculated, from the velocity of their motion, the 
velocity of the blood-stream in the retinal capillaries as equal to 0.5 to 0.75 mm. in a second, 
which corresponds very closely with the results obtained directly in other capillaries by E. H. 
Weber and Volkmann (§ 90, 4). When the carotids are compressed, the movement is slower on 
freeing them from the compression ; during short forced expirations the movement is accelerated 
(Landois). 
4. The entoptical pulse ($ 79, 2) depends upon the pulsating arteries irritating mechanically 
the rods lying outside them. 
5. Pressure Phosphenes.—Pressure applied to the eye causes a series of phenomena : («) 
Pressure upon part of the eyeball causes the so-called illuminated “ pressure-picture ” or 
phosphene, which was known to Aristotle. As the impression upon the retina is referred to 
something outside the eye, the phosphene is always perceived on the side of the field of vision 
opposite to where the pressure affects the retina, e.g., pressure upon the outer surface of the 
eyeball causes the flash of light to appear on the inner side. If the retina is not well lighted, 
the phosphene appears luminous ; if the retina is well lighted, it appears as a dark speck, within 
which the visual perception is momentarily abolished. (l>) If a uniform pressure be applied to 
the eyeball continuously from before backwards, as Purkinje pointed out, after some time there 
appear in the field of vision very sparkling variable figures which perform a wonderful fantastic 
play, and often resemble the sparkling effects obtained in a kaleidoscope (v. Helmholtz), and are 
probably comparable to the feeling of formication produced by pressure upon sensory nerves (“sleep- 
ing of the limbs ”). (c) By applying equable and continued pressure, Steinbach and Purkinje ob- 
served a network with moving contents of a bluish-silvery color, which seemed to correspond to the 
retinal veins. Vierordt and Laiblin observed the branching of the blood-vessels of the choroid 
as a red network upon a black ground. (d) According to Houdin, we may detect the position 
of the yellow spot by pressure upon the eyeball. 
6. The entrance of the optic nerve may be detected on moving the eyes rapidly backwards,' 
and especially inwards, as a fiery ring or semicircle about the size of a pea. Probably, owing to 970 
ENTOPTICAL PHENOMENA. 
[Sec. 393. 
the movement of the retina, the entrance of the optic nerve is stimulated mechanically by the 
rapid bending. Purkinje and others observed that the ring remained persistent on turning the 
eye strongly inwards. If the retina be brightly illuminated, the ring appears dark, and when the 
field of vision is colored, the ring has a different tint. If Purkinje’s figure be produced at the 
same time, one may observe that the vascular trunk proceeds from this ring—a proof that the 
ring corresponds to the entrance of the optic nerve (Landois). 
7. Accommodation Spot.—On accommodating the eye strongly towards a white surface, 
there appears in the middle a small bright trembling shimmer, and in its centre a coarse brown 
speck, about the size of a pea, is seen (Purkinje). If pressure be applied externally to the eye- 
ball, this speck becomes more distinct. After having once observed the phenomenon, occasion- 
ally on pressing laterally upon the opened eye we may see it as a bright speck in the field of 
vision—another proof that the intraocular pressure is increased during accommodation. 
8. Mechanical Optical Stimulation.— On dividing the optic nerve in man, as in extirpation 
of the eyeball, a flash of light is observed at the moment of section by the person operated on. 
The section of the nerve-fibres themselves is painless, but section of the sheaths is painful. 
9. The accommodation phosphene is the occurrence of a fiery ring at the periphery of the 
field of vision, seen on suddenly bringing the eyes to rest after accommodating for along time in 
the dark [Purkinje). The sudden tension of the zonule of Zinn resulting from the relaxation 
causes a mechanical stretching of the outermost part of the margin of the retina, or it may be 
of a part of the retina behind this. Purkinje observed the phenomenon after suddenly relaxing 
the pressure on the eye. 
10. Electrical Phenomenon.—Electrical currents, when applied to the eye, cause a strong 
flash of light over the whole field of vision. One pole of the battery may be placed on the under 
eyelid and the other on the neck. The flash at closing [making] the current is strongest with 
an ascending current, that with opening [breaking] the current with a descending current. If a 
uniform continuous ascending current be transmitted through the closed eyes, the dark disc of the 
elevation at the entrance of the optic nerve appears in a field of vision; with a 
descending current, the field of vision is reddish and dark, in which the position of the optic nerve 
appears light blue (v. Helmholtz). If external colors are looked at simultaneously, these colors 
blend to form a violet or yellow with the colors looked at (Schelske). During the passage of the 
ascending current we see external objects indistinctly and smaller when the eyes are open ; while 
with the descending current they are larger and more distinct [Ritter). Sometimes the position 
of the macula lutea appears dark on a bright ground, or the reverse, according to the direction of 
the current. If the current be opened [broken] the phenomena are reversed (§ 335), and the 
eye soon returns to rest. 
11. The yellow spot appears sometimes as a dark circle when there is a uniform blue illumi- 
nation. In a strong light the position of the yellow spot is surrounded by a bright area, twice or 
thrice as large, called “ Lowe’s ring.” [Clerk-Maxwell’s Experiment.—On looking through 
a solution of chrome-alum in a bottle or vessel with parallel glass sides, we observe an oval rosy- 
purplish spot in the greenish color of the alum. This is due to the pigment of the yellow spot.] 
Haidinger’s Brushes.—On directing the eye towards a source of polarized light; “Haidin- 
ger’s polarized brushes ” appear at the point of fixation. They are seen on looking through a 
Nicol’s prism at a bright cloud (v. Helmholtz). They are bright and bluish on a surface, bounded 
by two neighboring hyperbola on a white field; the dark bundle separating them is smallest in 
the centre and yellow. Of the various colors of homogeneous light, blue alone shows the 
brushes [Stokes). According to v. Helmholtz, the seat of the phenomenon is the yellow spot, 
and is due to the yellow-colored elements of the yellow spot being slightly doubly refractive, 
while at one part they absorb more, at another less, of the rays entering the eye. 
12. Lastly, there are the visual sensations depending on internal causes, eg., increased 
bounding of the blood through the retina, as during violent coughing, increased intraocular pres- 
sure. Stimulation of the visual areas ($ 378, IV) may produce spectra, which Cardanus (1550), 
Goethe, Nicolai, and Johannes Muller could produce voluntarily. 
394. ILLUMINATION OF THE EYE.—OPHTHALMO- 
SCOPE.—The light which enters the eye is partly absorbed by the black 
uveal pigment, and partly again reflected from the eye, and always in the 
same direction in which the rays entered the eye. By placing oneself in front 
of the eye of another person, of course the head, being an opaque body, cuts 
off a large number of rays. Owing to the position of the head, no rays of 
light can enter the eye ; and of course none can be reflected back to the eye of 
the observer. Hence, the eye of the person being examined always appears 
♦black, because those rays which alone could be reflected in the direction of 
the eye of the observer are cut off. As soon, however, as we succeed in causing Sec. 394.] 
OPHTHALMOSCOPE. 
971 
rays of light to enter the eye at the same time and in the same direction in 
which we observe the eye of another person, the fundus of the eye appears 
brightly illuminated. 
The following simple arrangement is sufficient for the 
purpose (fig. 677) : Let B be the eye of the patient, A 
that of the observer, and let a flame be placed at x. The 
rays of light proceeding from x impinge upon the ob- 
liquely placed plate of glass (S,S), and are reflected in the 
direction of the dotted lines into the eye (B). The fun- 
dus of the eye appears in this position to be brightly illu- 
minated in diffusion circles around b. As the observer 
Arrangement for examining the eye of B. A, eye of observer ; x, source of light; S, S, plate 
of glass directed obliquely, reflecting light into B. 
Fig. 677. 
(A) can see through the obliquely placed glass plate (S, S), and in the same direction as the 
reflected rays {x,y), he sees the retina around b brightly illuminated. 
In order that this method be made available for practical purposes, we must, of course, be able 
to distinguish the details, such as the blood-vessels of the fundus of the eye, the macula lutea, 
the entrance of the optic nerve, abnormalities of the retina, and the choroidal pigment, etc. The 
following considerations show us how to proceed in order to accomplish this. As already men- 
Fig. 678. 
tioned, and as fig. 658 shows, a small inverted image is formed on the retina (c, d) when we 
look at an object (A, B) ; conversely, according to the same dioptric law, an enlarged inverted 
real image of a small distinct area of the retina (c, d—depending on the distance for which the 
eye was accommodated) must be formed outside the eye (A, B). 
If the fundus of this eye be sufficiently illuminated, this aerial image will be correspondingly 
bright. 
In order to see the individual parts of the retinal picture more distinctly, the observer must 972 
OPHTHALMOSCOPE. 
[Sec. 394. 
accommodate his own eye for the position of this image. In such circumstances the eye of the 
observer would be too near the observed eye. His eye when so accommodated is removed from 
the eye of the patient by his own visual distance, and by the visual distance of the patient. As 
Fig. 679. 
this distance is considerable, the individual small details of the fundus cannot be seen distinctly. 
Further, owing to the contraction of the pupil of the patient, only a small area of the fundus can 
Fig. 680. 
be seen, and this only under a small visual angle, quite apart from the fact that it is often impos- 
sible to accommodate for the real image of the fundus of the patient. 
Hence the eye of the observer must be brought nearer to the eye of the patient. This may 
Fig. 681. 
Fig. 682. 
Fig. 681.—The entrance ot the optic nerve with the adjacent parts of the fundus of the normal 
eye. a, ring of connective-tissue; b, choroidal ring; c, arteries; d, veins; of 
the central artery; h, division of the central vein; L, lamina cribrosa; t, temporal (outer) 
side; n, nasal (inner) side. Fig. 682.—Morton’s ophthalmoscope. 
be done in two ways: (I) Either by placing in front of the eye of the patient a strong convex 
lens (of i to 3 inches focus—fig. 678, C). This causes the retinal image to be nearer to the eye Sec. 394.] 
OPHTHALMOSCOPE. 
973 
(at B), owing to the strong lens refracting the rays of light. The observer (M) can come nearer 
to the eye, and can still accommodate for the image of the fundus of the eye. (2) Or a concave 
lens is placed immediately in front of the eye of the patient (fig. 679, 0). The rays of light 
emerging from the eye of the patient (P) are either made parallel by the concave lens (0), and 
are brought to a focus on the retina of the emmetropic observer (A); or, if the lens causes the 
rays to diverge (fig. 680), an erect, virtual image is formed at a distance behind the eye of the 
patient (at R). In these cases hlso the observer can go much nearer to the eye of the patient. 
The ophthalmoscope invented by v. Helmholtz enables us to examine the 
whole of the fundus of the eye. 
[Direct Method.—Use a concave mirror of 20 centimetres focal distance, 
with a central opening. Reflect a beam of light into the patient’s eye, where 
the rays cross in the vitreous and illuminate the fundus of the eye. These rays 
again pass out of the eye and reach the observer’s eye through the central hole 
in the mirror. If the observer be emmetropic they come to a focus on his retina. 
In this way all the parts of the retina are seen in their normal position, but en- 
larged. Hence it is sometimes called the examination of the upright image. 
The eye of the patient and observer must be at rest, i. e., be negatively accom- 
modated, while the mirror must be brought as near as possible to the eye of 
the patient.] 
[Indirect Method, by which a more general view of the fundus is obtained. 
Throw the light into the patient’s eye by an ophthalmoscopic mirror as above, 
but held at a distance of about 25 cm. (10 inches) from the patient’s eye. 
Hold a biconvex lens of 14 dioptrics focal length vertically between the mirror 
and the patient’s eye (fig. 678), the observer looking through the hole of the 
mirror. What he does see is an inverted aerial image at B. Only a small 
part of the fundus oculi can be seen at one time.] 
[The ophthalmoscope, besides being used for examining the interior of the eyeball, is of the 
utmost use in determining the existence and amount of anomalies of refraction in the refrac- 
tive media. For this purpose an ophthalmoscope requires to be provided with plus and minus 
lenses, which can be readily brought before the eye of the observer. This is readily done by an 
ingenious mechanism devised by Couper, and made use of in the handy students’ ophthalmoscope 
of Morton (fig. 682). The lenses are moved by a driving-wheel on the left figure, while at the 
same time is indicated at a certain aperture the lens presented at the sight hole. The instrument 
is also provided with a movable arrangement carrying a concave mirror at either end. One of 
these mirrors is 10 inches in focus, and is used for indirect examination and retinoscopy, while 
the other is of 3 inches focus for direct examination, and is fixed at an angle of 250.] 
[Retinoscopy.—The ophthalmoscope is used also for this purpose. A beam of light is reflected 
into the eye by the ophthalmoscopic mirror, and the play of light and shade on the fundus oculi 
observed. A study of this is important in determining anomalies of refraction. For the method, 
the student is referred to a text-book on “ Diseases of the Eye.”] 
[Artificial Eye.—The student may practice the use of the ophthalmoscope on an artificial 
eye, such as that of Frost (fig. 683) or Perin or Priestley Smith.] 
Illumination of the Retina.—In order to illuminate the interior of the eye, V. Helmholtz 
used several plates of glass, placed behind each other, in the position of S, S, in fig. 677. 
Afterwards he used a plane or concave mirror of 7 inches focus (fig. 677), with a hole in the 
centre. Fig. 681 shows the appearance of the fundus of the eye, as seen with the ophthalmo- 
scope. In albinos the fundus of the eye appears red, because light passes into the eye through 
the sclerotic and uvea, which are devoid of pigment. If a diaphragm be placed over the eye, 
so that the pupil alone is free, the eye appears black (Donders). 
Tapetum.—In many animals the eyes have a bright green lustre. These eyes have a special 
layer, the tapetum, or the membrana versicolor of Fielding; in carnivora it consists of cells 
[devoid of melanin granules], in herbivora of fibres, placed between the capillaries of the choroid 
and the stroma of the uvea. These structures exhibit interference-colors and reflect much light, 
so that the colored lustre appears in the eye (p. 942). 
Oblique illumination is used with advantage for investigating the anterior chamber. A 
bright beam of light, condensed by a convex lens, is thrown laterally upon the cornea into the 
eye, and so directed upon the point to be investigated as to illuminate it. A point so illuminated, 
e. g., a part of the iris, may be examined from a distance by means of a lens, or even by a micro- 
scope (Liebreich). 
Orthoscope.—Czermak constructed this instrument, in which the eye is placed under water 974 
mariotte’s experiment. 
[Sec. 394. 
(fig. 684). It consists of a small glass trough with one of its walls removed. The margins of 
the open side are pressed firmly against the region of the eye. The eye and its surroundings 
form, as it were, the sixth side of the trough, which is filled with water, so that the cornea is 
bathed therewith. As the refractive index of water is almost the same as the refractive index of 
the media of the eye, the rays of light pass into the eye in a straight direction without being 
refracted. Hence, objects in the anterior chamber can be seen directly, as if they were not within 
Fig. 683. 
Fig. 684. 
Frost’s artificial eye. 
Action of the orthoscope. 
the eye at all. Another advantage is that the objects can be brought nearer to the eye of the 
observer. The rays of light emerging from the point (a) of the fundus, if the eye were sur- 
rounded by air, would leave the eye as the parallel lines, b, c, b, c. Under water, these rays, a, 
b, continue in the direction a, b, as far as b, d, where they emerge from the water, and are bent 
from the perpendicular to d, e, d, e. The eye of the observer, looking in the direction e, d, sees 
the point, a, nearer, viz., in the direction, e, d, a', lying at a. 
395. ACTIVITY OF THE RETINA IN VISION.—I. Blind 
Spot.—The rods and cones alone are the parts of the retina sensitive to 
light; they alone are excited by the vibrations of the ether. This is confirmed 
Mariotte’s experiment. 
Fig. 685. 
by Mariotte’s experiment (1688), which proves that the entrance of the optic 
nerve, where rods and cones are absent, is devoid of visual sensibility. Hence 
it is spoken of as the “ blind spot.” Sec. 395.] 
ACTION OF LIGHT ON RETINA. 
975 
[Mariotte’s Experiment.—Make a cross and a circle, about 3 inches 
apart, upon paper (fig. 685). Look at the cross with the right eye, keeping the 
left eye closed, and hold the paper about a foot from the eye, when both the 
cross and the circle will be seen. Gradually approximate the paper to the eye, 
keeping the open eye steadily fixed on the cross; at a certain moment the circle 
will disappear, and on bringing the paper nearer to the eye it will reappear. 
The moment when the circle disappears is when its image falls upon the en- 
trance of the optic nerve.] 
Position and Size.—The entrance of the optic nerve lies about 3.5 mm. internal to the visual 
axis of the eyeball, in the retina. Its diameter is 1.8 mm. The apparent diameter of the blind 
spot in the field of vision is in a horizontal direction 6° $6'—this lies 120 35/ to 180 55/ horizon- 
tally from the fixed point. Eleven full moons placed side by side would disappear on the sur- 
face, and so would a human face at a distance of over 2 metres. 
Proofs.—The following facts prove that the entrance of the optic nerve is insensible to 
light: (1) Donders projected, by means of a mirror, the small image of a flame upon the en- 
trance of the optic nerve of another person, and the person had no sensation of light. But a 
sensation of light was experienced when the image of the flame was projected upon the neigh- 
boring parts of the retina. (2) On combining with Mariotte’s experiment the experiment which 
causes entoptical phenomena at the entrance of the optic nerve, this coincides with the blind 
spot (| 393, 6 and 7). 
Form of Blind Spot.—In order to determine the form and apparent size of the blind spot 
in one’s own eye, fix the head at about 25 centimetres from a surface of white paper; select a 
small point on the latter and keep the eye directed towards it; then, starting from the position 
of the blind spot, move a white feather in all directions over the paper; whenever the tip of 
the feather becomes visible, make a mark at this spot. The blind spot may be mapped out in 
this way. It has an irregular, elliptical form from which processes proceed, due to the equally 
non-sensitive origins of the large blood-vessels of the retina (Hueck). (Mariotte concluded 
from his experiment that the choroid, which is perforated by the optic nerve, is the membrane 
sensitive to light, as the nerves are nowhere absent from the retina.) 
The Blind Spot Causes no Appreciable Gap in the Field of Vision.—As the area is not 
excited by light, a black spot cannot appear in the field of vision, for the sensation of black 
implies the presence of retinal elements, which; however, are absent from the blind spot. The 
circumstance, however, that in spite of the existence of an inexcitable 
spot during vision, no part of the field of vision appears to be unoccu- 
pied, is due to a psychical action. The unoccupied area of the field of 
vision, corresponding to the blind spot, is filled in according to probabil- 
ity, by a psychical process (£. H. IVeber). Hence, when a white point 
disappears from a black surface, the whole surface appears to us black; 
a white surface, from which a black point falls on the blind spot, 
appears quite white; a page of print, gray throughout, etc. According 
to the probabilities, certain parts are supplied—parts of a circle, the 
middle parts of a long line, the central part of a cross. Such images, 
however, as cannot be constructed according to the probabilities, are not 
perfected, e.g., the end of a line or a human face. In other cases the condition known as 
“ contraction ” of the field of vision tends to fill up the gap. This will be evident on looking at 
the nine adjoining letters, so that e disappears; we no longer see the three letters on each side 
of it in straight lines, but b, f \ h, d are turned in towards e. The adjoining parts of the field 
of vision seem to extend over and around the blind spot, and thus help to compensate for the 
blind spot. 
II. Optic Fibres Inexcitable to Light.—The layer of the fibres of the 
optic nerve in the retina is not sensitive to light. This is proved by the fact 
that, in the fovea centralis, which is the area of most acute vision, there are no 
nerve-fibres. Further, Purkinje’s figure proves that, as the arteries of the 
retina lie behind the optic fibres, the latter cannot be concerned in the percep- 
tion of the former. 
III. Rods and Cones.—The outer segments of the rods and cones have 
rounded outlines, and are packed close together; but natural spaces must exist 
between them, corresponding to the spaces that must exist between groups of 
bodies with a circular outline. These parts are insensible to light, so that a 
retinal image is composed like a mosaic of round stones. The diameter of a 976 
DIRECT VISION. 
[Sec. 395. 
cone in the yellow spot is 2 to 2.5 /z (J/. Schultze'). If two images of two 
small points, placed very near each other, fall upon the retina, they will still 
be distinguished as distinct images, provided that both images fall upon two 
different cones. The two images on the retina need only be 3-4-5.4 // apart, 
in order that each may be seen separately, for then the images fall upon two 
adjoining cones. If the distance be diminished so very much that both 
Horizontal section of the right eye. a, cornea; b, conjunctiva; c, sclerotic; d, anterior 
chamber containing the aqueous humor; e, iris; f f', pupil; g, posterior chamber; /, 
Petit’s canal; j, ciliary muscle; k, corneo-scleral limit; i, canal of Schlemm ; m, choroid; 
11, retina; o, vitreous humor; No, optic nerve; q, nerve-sheaths; p, nerve-fibres; Ic, 
lamina cribrosa. The line O A indicates the optic axis; A r, the axis of vision; r, the 
position of the fovea centralis. 
Fig. 686. 
images fall upon one cone, or one upon one cone and the other upon the inter- 
mediate or cement substance, then only one image is perceived. The images 
must be further apart in the peripheral portion of the retina in order that they 
may be separately distinguished. 
As the rounded end-surfaces of the cones do not lie exactly under each other, but are so 
arranged that one series of circles is adapted to the interstices of the following series, this Sec. 395.] 
INDIRECT VISION. 
977 
explains why fine dark lines lying near each other appear to have alternating twists upon them, 
as the images of these must fall upon the cones, at one time to the right, at another to the 
left. 
IV. The fovea centralis is the region of most acute vision, where 
only cones are present, and where they are very numerous and closely packed 
(fig. 648). The cones are less numerous in the peripheral areas of the retina, 
and consequently vision is much less acute in these regions. We may, there- 
fore, conclude that the cones are more important for vision than the rods. 
When we wish to see an object distinctly we involuntarily turn our eyes so that 
the retinal image falls upon the fovea centralis. In doing this, we are said to 
“fix ” our eyes upon an object. The line drawn from the fovea to the object 
is called the axis of vision (fig. 686, S r). It forms an angle of only 3.5-70 
Fig. 687. 
M’Hardy’s perimeter. I, porcelain button ; M,bit; E, for fixing the head \ g, h, quadrant; 0, 
fixation point; p, pointer for piercing the record chart held in the frame (e) which moves on 
c; D, upright supporting the quadrant and the automatic arrangement of slides (/& and /), 
which are moved by j. 
with the 11 optical axis" (O A), which unites the centres of the spherical 
surfaces of the refractive media of the eye. The point of intersection, of 
course, lies in the nodal point (.Kn) of the lens (p. 976). The term “ direct 
vision ” is applied to vision when the direction of the axis of vision is in 
line with the object [?.<?., when the image of the object falls directly on the 
fovea centralis]. 
“ Indirect vision ” occurs when the rays of light from an object fall upon 
the peripheral parts of the retina. Indirect vision is much less acute than 
the direct. Still the periphery of the retina is in a high degree capable of 
62 978 
PERIMETRY. 
[Sec. 395. 
distinguishing movements, changes, or intermission of visual impressions 
(.Exner). 
To test the acuity of direct vision, draw two fine parallel lines close to each other, and 
gradually remove them more and more from the eye, until both appear almost to unite and form 
one line. The size of the retinal image may be ascertained by determining the distance of the 
two lines from each other, and the distance of the lines from the eye, or, from the corresponding 
visual angle, which is generally from 60 to 90 seconds. 
Perimetry.—In order to test indirect vision, we may use a perimeter. 
The eye is placed opposite a fixed point, from which a quadrant proceeds, so 
that the eye lies in the centre of it. As the quadrant rotates round the fixed 
point, on rotating the former we can circumscribe the surface of a hemisphere, 
in the centre of which the eye is placed. Proceeding from the fixed point, 
objects are placed upon semicircles, and are gradually pushed more and more 
towards the periphery of the field of vision, until the object becomes indis- 
tinct, and finally disappears. The process of testing is continued by placing 
the arc successively in the different meridians of the field of vision. 
[M’Hardy’s perimeter is a very convenient form (fig. 687). It consists of two uprights (C 
and D), which are fixed to the opposite ends of a flat basal plate (A). C carries an arrangement 
for supporting the patient’s head, while D carries the automatic arrangement for the perimetric 
record. Both of these can be raised or depressed by the screws (G and b). The patient’s chin 
rests on the chin-rest (E), while in the mouth is placed Landolt’s biting fixation (L), which is 
detachable. The position of the head can be altered by sliding F on L, which can be fixed in 
any position by the screw (O). The porcelain button (I) iust below the patient’s eye (/) is con- 
nected with the adjustment of the “ fixation point.” The automatic recording apparatus 
consists of a revolving quadrant [A, A), which describes a hemisphere round a horizontal axis 
passing through the centre of the hollow male axle, turning in the female end of a, which is 
supported by D. The quadrant can be fixed at 
any point by g. On the front concave surface 
of the quadrant is fixed a circular white piece of 
ivory, representing the “ fixation point,” from 
which a needle projects and which is the zero of 
the instrument. A carriage (*), in which the 
test objects are placed, can be moved in the 
concave face of the quadrant by means of the 
milled head (/), which moves the carriage by 
means of a tooth and pinion wheel.] 
[When the milled head (j) is turned, it moves 
the carriage and two slides (A and /], the two 
slides moving in the ratio of 2 to 1. The rate 
of the carriage is so adjusted that it travels ten 
times faster than /, and five times faster than A. 
The pointer (/>) is connected with these slides, 
so that it moves when they move, and records 
its movements by piercing the record chart, 
which is fixed in the double-faced frame (e). 
The frame for the record chart is hinged near 
c to the upright (D). The frame, when upright, 
comes so near the pointer (hat the latter can 
pierce a chart placed in the frame. The patient 
is directed to look at the “fixation point,” 
which is merely a small ivory button placed in 
the imaginary axis of the hemisphere on the 
front of the centre of the concave surface of the 
quadrant; the projecting needle-point (0) indi- 
cates its position. This is the zero of-the quad- 
rant, and on each side of it the quadrant is divided into 900.] 
[Jn testing the field of vision, place the carriage so as to cover zero, adjust the eye for the 
fixation point, and look steadily at it, when, if all is right, the pointer (p) ought to pierce the 
centre of the chart. Move the carriage along the quadrant by j until it disappears from the field 
of vision, and when it does so the pointer is made to pierce the chart. Make another observa- 
Fig. 688.—Priestley Smith’s perimeter. Sec. 395.] 
PERIMETRY. 
979 
tion in another direction by altering the position of the quadrant, and go on doing so until a com- 
plete record is obtained of the field of vision. Test the other eye in the same way. The color- 
field may be tested by using colored papers in the carriage.] 
[Priestley Smith’s Perimeter (fig. 688).—The wooden knob on the left of the figure is 
placed under the eye of the patient, who stares at the fixed point in the axis of the quadrant, 
which can be moved in any meridian. The test object is a square piece of white paper, which is 
moved along the quadrant. The chart is placed on the posterior surface of the hand-wheel and 
moves with it, so that the meridians of the chart move with the quadrant. There is a scale be- 
hind the hand-wheel corresponding with the circles on the chart, so that the observer can prick 
off his observations directly.] 
[Scotoma is the term applied to dimness or blindness in certain parts of the field of vision, 
which may be central, marginal, or in patches.] 
The capacity for distinguishing colors diminishes more rapidly at the periphery of the 
retina than that for distinguishing differences in the brightness or intensity of light. In fact, the 
Perimetric chart of a healthy and a diseased eye. 
Fig. 689. 
periphery of the retina is slightly red blind. The diminution is greater in the vertical meridian 
of the eye than in the horizontal, and it diminishes with the distance from the fixation point 
(.Anbert and Forster). These observers also state that, during accommodation for a distant 
object, the diminution of the capacity to distinguish brightness and color towards the periphery 
of the lens, occurs more rapidly than with near vision. , The excitability of the retina for colors 
and brightness is greater at a point equally distant from’the fovea centralis on the temporal than 
on the nasal side of the eye (Schon). 
Perimetric Chart. —If the arc of the perimeter (fig. 688) be divided into 90 degrees, begin- 
ning at the fixation point (central point), and proceeding to L and M (fig. 689); and if a series 
of concentric circles be inscribed on this, with the point of fixation as their centre, we can con- 
struct a topographical chart of the visual capacity of the normal or healthy eye from the data 
obtained by the examination of the retina. 
Fig. 689 is an example; the thick lines indicate a diseased eye, the corresponding thin lines 
a healthy eye. The continuous line indicates the limits for the perception of white ; the inter- 980 
PERIMETRY. 
[Sec. 395. 
rupted line that for blue; the punctuated and interrupted line that for red; m is the blind spot. 
In the normal eye the limits for the perception of colors are as under— 
White. 
Blue. 
Red. 
Green. 
Externally, 
O 
00 
00 
1 
o 
o 
65° 
6o° 
40° 
Internally, 
5o°-6o° 
6o° 
5°° 
4o° 
Upwards, 
45°-55° 
45° 
40° 
30°-35° 
Downwards, 
650-7°° . 
6o° 
50° 
35° 
V. Specific Energy.—The rods and cones alone are endowed with what 
Johannes Muller called “specific energy,” i. e., they alone are set into activity 
by the ethereal vibrations, to produce those impulses which result in vision. 
Mechanical and electrical stimuli, however, when applied to any part of the 
course of the nervous apparatus, produce visual phenomena. Mechanical stimuli 
are more intense stimuli than light rays, as is shown by performing the dark 
pressure figure with the eyes open (§ 393, 5, a), whereby the circulation in the 
retina is interfered with ; in the region of pressure, we cannot see external 
objects which affect the retina uniformly and continuously. 
VI. The duration of the retinal stimulation must be exceedingly short, 
as the electrical spark lasts only 0.000000868 second ; still, as a general rule, a 
shorter time is required, the larger and brighter the object looked at. Alter- 
nate stimulation with light, 17 to 18 times per minute, is perceived most 
intensely (Briicke). An interval of 0.027 second must elapse between two 
flashes of light in order that both may be seen separately (Charpentier). Fur- 
ther, an increase or diminution of 0 01 part of the intensity of the light is 
perceptible (§ 383). A shorter time is required to perceive yellow than is 
required for violet and red ( Vierordt). The retina becomes more sensitive to 
light after a person has been kept in the dark for a long time, and also after 
repose during the night. If light be allowed to act on the eyes for a long time, 
and especially if it be intense, it causes fatigue of the retina, which begins 
sooner in the centre than in the periphery of the organ (Aubert). At first the 
fatigue comes on rapidly, and afterwards develops more slowly—it is most 
marked in the morning {A. Fick). 
VII. During direct vision, objects must traverse at an angular velocity of 
1-2 minutes per second in order to appear to be in motion {Aubert). 
VIII. Visual Purple.—The mode of the action of light upon the end- 
organs of the retina has already been referred to (p. 942) in connection with 
the “visual purple" or rhodopsin {Boll, Kiihne). Kiihne showed that, by 
illuminating the retina, actual pictures {e. g., the image of a window) could be 
produced on the retina, but they gradually disappeared. From this point of 
view we might regard the retina as comparable, to a certain extent, to the sen- 
sitive plate of a photographic apparatus. 
Optogram.—The visual purple is formed by the pigment-epithelium of the retina. ' Perhaps 
we might compare the process to a kind of secretion. The visual purple may be restored in a 
retina by laying the latter upon living choroidal epithelium. The pigment disappears from the 
mammalian retina by the action of light 60 times more rapidly than from the retina of the frog. 
In a rabbit’s eye, whose pupil was dilated with atropin, Ewald and Kiihne obtained a sharp 
picture or optogram of a bright object placed at a distance of 24 cm. from the eye—the image 
was “ fixed ” by a 4 per cent, solution of alum. Visual purple withstands all the oxidizing re- 
agents ; zinc chloride, acetic acid, and corrosive sublimate change it into a yellow substance—it 
becomes white only through the action of light; the dark heat-rays are without effect, while it 
is decomposed above a temperature of 520 C. [As visual purple is absent from the cones, and 
as cones only are present in the fovea centralis, we cannot explain vision by optograms formed 
by the visual purple.] 
Movements of Rods and Cones.—The inner limb of the cones under Sec. 395.] 
PERCEPTION OF COLOR. 
981 
the action of light becomes shorter, and elongates in darkness. The action 
occurs in both eyes, even when the light acts only on one eye. After destruc- 
tion of the brain, the effect is confined to the eye directly acted on by light. 
Strychnine tetanus acts like light. It would seem, therefore, that the optic 
nerve, in addition to afferent light-exciting fibres, contains also motor fibres— 
retino-motor fibres, according to Engelmann and Stort. Angelucci has ob- 
served movements in the outer limbs, and Gradenigo in the inner limbs of the 
rods. Heat is said to act in a manner similar to light. The isolated inner 
limbs of the cones exhibit changes of form when acted on by light (Gra- 
denigo). 
IX. Destruction of the rods and cones of the retina causes correspond- 
ing dark spots in the field of vision. 
396. PERCEPTION OF COLORS.—Physical.—The vibrations of 
the light-ether are perceived by the retina only within distinct limits. If a beam 
of white light, e. g., from the sun, be transmitted through a prism, the light 
rays are refracted and dispersed, and a “ prismatic spectrum ” is obtained 
(fig. 23). [If a beam of white light be transmitted through a hole in a shutter 
into a dark room, and a prism be held in the course of the beam behind the 
shutter, and in the position shown in fig. 690, then a spectrum or band of colors 
will be obtained on a white screen placed several feet from the prism. The 
colors will be in the definite order shown in the diagram ; i. e., in order from 
the least refrangible red to the most refrangible violet. Thus white light con- 
tains rays of very different wave-lengths or periods of vibration.] 
The dark heat-rays, or ultra-red rays, whose wave-length is 0.00194 mm., 
are refracted least, do not act upon the retina, and are therefore invisible. 
They act, however, upon sensory nerves, and give rise to the sensation of 
heat. About 90 per cent, of these rays is absorbed by the media of the eye 
(Briicke and Knoblauch). From Fraunhofer’s line, A, onwards, the oscillations 
of the light-ether excite the retina in the following order, and constitute the 
visible spectrum (fig. 690) : Red with 481 billions of vibrations per second, 
orange with 532, yellow with 563, green with 607, blue with 653, indigo 
with 676, and violet with 764 billion vibrations per second. The sensation 
of color therefore depends on the number of vibrations of the light- 
ether, just as the pitch of a note depends on the number of vibrations of the 
sounding body {Newton, 1704; Hartley, 1772). Beyond the violet lie the 
chemically active ultra-violet or actinic rays of the spectrum. After 
cutting out all the spectrum, including the violet-rays, v. Helmholtz succeeded 
in seeing the ultra-violet rays, which had a feeble grayish-blue color. The heat- 
rays in the colored part of the spectrum are transmitted by the media of the 
eye in the same 
way as through 
water. The exist- 
ence of the ultra- 
violet rays is best 
ascertained by the 
phenomenon of 
flu or es cence. 
Von Helmholtz, on 
illuminating a solu- 
tion of sulphate of 
quinine with the 
ultra-violet rays, 
saw a bluish-white 
light proceeding from all parts of the solution which were acted on by the 
Violet. 
Indigo. 
Blue. 
Green. 
Yellow. 
Orange. 
Red. 
Fig. 690. 
Spectrum obtained by means of a prism. 982 
COMPLEMENTARY COLORS. 
[Sec. 396. 
ultra-violet rays. As the media of the eye themselves exhibit fluorescence 
(v. Helmholtz), they must increase the power of the retina to distinguish these 
ravs. The ultra-violet rays are not largely absorbed by the media of the eye 
(Bril eke). 
In order that a color be perceived, it is essential that a certain amount of light fall upon the 
retina. Blue, when at the lowest degree of brightness, gives a color sensation with an amount of 
light which is sixteen times less than that required for red (Dobrowlosky). 
Intensity of the Impression of Light.—While light of different periods of vibration applied 
to the eye excites the different sensations of color, the amplitude of the vibrations (height of the 
waves) determines the intensity of the impression of light; just as the loudness of a note de- 
pends on the amplitude of the vibrations of the sounding body. The sun’s light contains all the 
rays which excite the sensation of color in us, and when all these rays fall simultaneously upon 
the retina we experience the sensation of white. If the colors of the spectrum obtained by means 
of a prism be reunited, white light is again obtained. If no vibrations of the light-ether reach the 
retina, every sensation of light and color is absent, but we can scarcely apply the term black to 
this condition. It is rather the absence of sensation, such as, for example, is the case when a 
beam of light falls on the skin of the back. This does not give the sensation of black, but rather 
that of no sensation of light. 
Simple and Mixed Colors.—We distinguish simple colors, e. g., those 
of the spectrum. In order to perceive these, the retina must be excited (set 
into vibration) by a distinct number of oscillations (see p. 981). Further, we 
distinguish “mixed colors,” whose sensations are produced when the retina 
is excited by two or more simple colors, simultaneously or rapidly alternating. 
The most complex mixed color is white, which is composed of a mixture of 
all the simple colors of the spectrum. 
The “ complementary colors ” are important. Any two colors which 
together give the sensation of white are complementary to each other. The 
“ contrast colors ” are mentioned here merely to complete the list. They 
are closely related to the complementary colors. Any two colors which, when 
mixed, supplement the generally prevailing tone of the light, are contrast colors. 
When the sky is blue, the two contrast colors must be bluish-white ; with bright 
gaslight they must be yellowish-white, and in pure white light of course all the 
complementary are the same as the contrast colors (Briicke). 
Methods of Mixing Colors.—1. Two solar spectra are projected upon a screen, and the 
spectra are so arranged as to cause any one part of one spectrum to cover any part of the other. 
2. Look obliquely through a vertically arranged glass plate at a color placed behind it. Another 
color is placed in front of the glass plate, so that its image is also reflected into the eye of the 
observer; thus, the light of one color transmitted through the glass plate and the reflected light 
from the other color reach the eye simultaneously. [Lambert’s Method.—This is easily done 
by Lambert’s method. Use colored wafers and a slip of glass; place a red wafer on a sheet of 
black paper, and about 3 inches behind it another blue one. Hold the plate of glass midway and 
vertically between them, and so incline the glass that, while looking through it at the red wafer, 
a reflected image of the blue one will be projected into the eye in the same direction as that of 
the red image, when we have the sensation of purple.] 
3. A rotatory disc, with sectors of various colors, is rapidly rotated in front of the eyes. On 
rapidly rotating the colored disc, the impressions produced by the individual colors are united to 
produce a mixed color. If the rotating disc, which yields, let us suppose, white, on mixing the 
colors of the spectrum, be reflected in a rapidly rotating mirror, then the individual components 
of the white reappear. 
4. Place in front of each of the small holes in the cardboard used for Scheiner’s experiment 
(fig. 664) two differently colored pieces of glass; the colored rays of light passing through the 
holes unite on the retina, and produce a mixed color (Czermak). 
Complementary Colors.—Investigation shows that the following colors 
of the spectrum are complementary, i. e., every pair gives rise to white :— 
Red and greenish-blue, 
Yellow and indigo-blue, 
Orange and cyan-blue, 
Greenish-yellow and violet, 
while green has the compound complementary color, purple (v. Helmholtz). 
The mixed colors may be determined from the following table. At the top of the vertical Sec. 396.] 
COMPLEMENTARY COLORS. 
983 
and horizontal columns are placed the simple colors ; the mixed colors occur where they inter- 
sect the corresponding vertical and horizontal columns (Dk. = dark; wh. =• whitish):— 
Violet. 
Indigo. 
Cyan-blue. 
Bluish- 
green. 
Green. 
Greenish- 
yellow. 
Yellow. 
Red 
Orange 
Yellow 
Gr -yellow 
Green 
Bluish-green 
Cyan-blue 
Purple 
Dk.-rose 
Wh.-rose 
White 
White-blue 
Water-blue 
Indigo 
Dk.-rose 
Wh.-rose 
White 
Wh.-green 
Water-blue 
Water-blue 
Wh.-rose 
White 
Wh.-green 
Wh. -green 
Bl.-green 
White 
Wh.-yellow 
Wh.-yellow 
Green 
Wh.-yellow 
Yellow 
Gr.-yellow 
Gold-yellow 
Yellow 
Orange 
The following results have been obtained from observations on the mixture 
of colors :— 
1. If two simple, but non-complementary, spectral colors be mixed with each 
other, they give rise to a color sensation, which may be represented by a color 
lying in the spectrum between both, and mixed with a certain quantity of white. 
Hence we may produce every impression of mixed colors by a color of the 
spectrum -{- white (Grassman). 
2. The less white the colors contain, the more “ saturated ” they are said 
to be; the more white they contain, the more unsaturated do they appear. 
The saturation of a color diminishes with the intensity of the illumination. 
Geometrical Color Table.—Since the time of Newton, attempts have been made to con- 
struct a so-called “ geometrical color table,” which will enable any mixed color to be readily 
found. Fig. 691 shows such a color table; white is placed in the middle, and from it to every 
point in the curve,—which is marked with the names of the colors,—suppose each color to be so 
placed that, proceeding from white, the colors are arranged, beginning with the brightest tone, 
always followed by the most saturated tone, until the pure saturated spectral color lies in the 
point of the curve marked with the name of the color. The mixed color, purple, is placed be- 
tween violet and red. In order to determine from this table the mixed color of any two spectral 
colors, unite the points of these colors by a straight line. Suppose weights corresponding to the 
units ofintensity of these colors to be placed ou both points of the curve indicating colors, then 
the position of the centre of gravity of both in the line connecting the colors indicates the posi- 
tion of the mixed color in the table. The mixed color of two spectral colors always lies in the 
color table in the straight line connecting the two color points. Further, the impression of the 
mixed color corresponds to an intermediate spectral color mixed with white. The complemen- 
tary color of any spectral color is found at 
once by making a line from the point of 
this color through white, until it intersects 
the opposite margin of the color table ; the 
point of intersection indicates the com- 
plementary color. If pure white be pro- 
duced by mixing two complementary 
colors, the color lying nearest white on the 
connecting line must be specially strong, 
as then only would the centre of gravity 
of the lines uniting both colors lie in the 
point marked white. 
By means of the color table we may 
ascertain the mixed color of three or more 
colors. For example, it is required to 
find the mixed color resulting from 
the union of the point, a (pale yellow), 
b (fairly saturated bluish-green), and c 
(fairly saturated blue). On the three 
points place weights corresponding to 
their intensities, and ascertain the centre 
of gravity of the weight, a, b, c; it will 
lie at p. It is obvious, however, that the impression of this mixed color, whitish green-blue, can 
be produced by green-blue -(- white, so that p may be also the centre of gravity of two weights, 
which lie in the line connecting white and green-blue. 
Cyan blue/ 
Green 
Indigo 
Yellow 
\ 
White 
Orange 
Violet 
«Red 
Geometrical color cone or table. 
Fig. 691. 984 
THEORIES OF COLOR VISION. 
[Sec. 396. 
We may describe a triangle, V, Gr, R, about the color table so as to enclose it completely. 
The three fundamental or primary colors lie in the angles of this triangle, red, green, 
violet. It is evident that each of the colored impressions, i. e., any point of the color table, 
may be determined by placing weights corresponding to the intensity of the primary colors at 
the angles of the triangle, so that the point of the color table, or what is the same thing, the 
desired mixed color, is the centre of gravity of the triangle with its angles weighted as above. 
The intensity of the three primary colors, in order to produce the mixed color, must be repre- 
sented in the same proportion as the weights. 
Theories of Color Visions.—Various theories have been proposed to 
account for color sensation. 
1. According to one theory, color sensation is produced by one kind of element present in the 
retina, being excited in different ways by light of different colors (oscillations of the light ether 
of different wave-lengths, number of vibrations, and refractive indices). 
2. Young-Helmholtz Theory.—The theory of Thomas Young (1807) 
and v. Helmholtz (1852) assumes that three different kinds of nerve-ele- 
ments, corresponding to the three primary colors, are present in the retina. 
Stimulation of the first kind causes the sensation of red, of the second green, 
and of the third violet. 
The elements sensitive to red are most strongly excited by light with the 
longest wave-length, the red rays; those for green by medium wave-lengths, 
green rays; those for violet by the rays of shortest wave-length, violet rays. 
Further, it is assumed, in order to explain a number of phenomena, that every 
color of the spectrum excites all the kinds of fibres, some of them feebly, others 
strongly. 
Fig. 692. 
Suppose in fig. 692 the colors of the spectrum are arranged in their natural order from red to 
violet horizontally, then the three curves raised upon the abscissa might indicate the strength of 
the stimulation of the three kinds of retinal elements. The continuous curve corresponds to 
the rays producing the sensation of red, the dotted line that of green, and the broken line that 
of violet. Pure red light, as indicated by the height of the ordinates in R, strongly excites the 
elements sensitive to red, and feebly the other two kinds of terminations, resulting in the 
sensation of red. Simple yellow excites moderately the elements for red and green, and feebly 
those for violet = sensation of yellow. Simple green excites strongly the elements for green, 
but much more feebly the other two kinds = sensation of green. Simple blue excites to a 
moderate extent the elements for green and violet; more feebly those for red — sensation of 
blue. Simple violet excites strongly the corresponding elements, feebly the others = sensation 
of violet. Stimulation of any two elements excites the impression of a mixed color; while, if 
all of them be excited in a nearly equal degree, the sensation of white is produced. As a 
matter of fact, the Young-Helmholtz theory gives a simple explanation of the phenomena of 
the physiological doctrine of color. It has been attempted to make the results obtained by 
examination of the structure of the retina accord with this view. According to Max Schultze, 
the cones alone are end organs connected with the perception of color. The presence of 
longitudinal striation in their outer segments is regarded as constituting them multiple terminal 
end-organs. Our power of color sensation, so far as it depends on the retina, would, on this 
view of the matter, bear a relation to the number of cones. The degree of color sensation is 
most developed in the macula lutea, which contains only cones, and diminishes as the distance 
from the point increases, while it is absent in the peripheral parts of the retina. The rods of 
the retina are said to be concerned only with the capacity to distinguish between quantitative 
sensations of light. 
3. Hering’s Theory.—E\v. Hering, in order to explain the sensation of 
light proceeds from the axiom stated under i, above. What we are conscious Sec. 396.] 
THEORIES OF COLOR BLINDNESS. 
985 
of, and call a visual sensation, is the psychical expression for the metabolism 
in the visual substance (“Sehsubstanz”), i.e., in those nerve-masses 
which are excited in the process of vision. Like every other corporeal matter, 
this substance during the activity of the metabolic process undergoes decom- 
position or “ disassimilation ” ; while during rest it must be again renewed, 
or “ assimilate ” new material. Hering assumes that for the perception of 
white and black, two different qualities of the chemical processes take place 
in the visual substance, so that the sensation of white corresponds to the dis- 
assimilation (decomposition), and that of black to the assimilation (resti- 
tution) of the visual substance. 
According to this view, the different degrees of distinctness or intensity with which these two 
sensations appear, occur in the several transitions between pure white and deep black; or, the 
proportions in which they appear to be mixed (gray) correspond to the intensity of these two 
psycho physical processes. Thus, the consumption and restitution of matter in the visual sub- 
stance are the primary processes in the sensation of white and black. In the production of the 
sensation of white, the consumption of the visual substance is caused by the vibrating ethereal 
waves acting as the discharging force or stimulus, while the degree of the sensation of whiteness 
is proportional to the quantity of the matter consumed. The process of restitution discharges 
the sensation of black; the more rapidly it occurs, the stronger is the sensation of black. The 
consumption of the visual substance at one place causes a greater restitution in the adjoining 
parts. Both processes influence each other simultaneously and conjointly. [In the production 
of a visual sensation, it is important to remember that the condition of one part of the retina 
influences contemporaneously the condition of adjoining parts of the retina, i. <?., “ the sensation 
which arises through the stimulation of any given point of the retina, is also a function of the 
state of other immediately contiguous points.”] This explains physiologically the phenomenon 
of contrast of which the old view could give only a psychical interpretation (p. 989). 
Similarly, color sensation is regarded as a sensation of decomposition (disassimilation) and 
of restitution (assimilation); in addition to white, red and yellow are the expression of 
decomposition; while green and blue represent the sensation of restitution. Thus, the 
visual substance is subject to three different ways of chemical change or metabolism. We may 
explain in this way the colored phenomena of contrast and the complementary after-images. 
The sensation of black-white may occur simultaneously with all colors; hence, every color 
sensation is accompanied by that of dark or bright, so that we cannot have an absolutely pure 
color. There are three different constituents of the visual substance; that connected with the 
sensation of black-white (colorless), that with blue-yellow, and that with red-green. All the rays 
of the visible spectrum act in disassimilating the black-white substance, but the different rays 
act in different degrees. The blue-yellow or the red-green substances, on the other hand, are 
disassimilated only by certain rays, some rays causing assimilation, whilst others are inactive. 
Mixed light appears colorless when it causes an equally strong disassimilation and assimilation 
in the blue-yellow and in the red green substance, so that the two processes mutually antagonize 
each other, and the action on the black-white substance appears pure. Two objective kinds of 
light, which together yield white, are not to be regarded as complementary, but as antagonistic 
kinds of light, as they do not supplement each other to produce white, but only allow this to 
appear pure, because, being antagonistic, they mutually prevent each other’s action. 
The imperfection of the Young-Helmholtz theory of color sensation is that it recognizes only 
one kind of excitability, excitement, and fatigue (corresponding to Hering’s disassimilation), and 
that it ignores the antagonistic relation of certain light rays to the eye. It does not regard white 
as consisting of complementary light rays, which neutralize each other by their action on the 
colored visual substance, but as uniting to form white [Hering). 
[While it suffices to explain a great many of the phenomena of light and color, eg., the 
mixing of colors and complementary colors, it does not satisfactorily explain contrast or color- 
blindness. Fick admits that it does not explain the following important fact: Every ray of 
light, while exciting a color sensation if it falls on a sufficient area of the posterior polar part 
of the eyeball, provided it acts on an extremely limited part of the retina, even if it be colored 
light, produces a whitish impression. This is exactly the opposite of what we should expect, 
viz., the smaller the area of retina acted on, the more readily should the particular nerve-ending 
be excited and a pure color-sensation result.] 
In applying this theory to color-blindness (§ 397), we must assume 
that those who are red-blind want the red-green visual substance; there are 
but two partial spectra in their solar spectrum, the black-white and the yellow- 
blue. The position of green appears to such an one to be colorless; the rays 986 
COLOR-BLINDNESS. 
[Sec. 396. 
of the red part of the spectrum are visible, so far as the sensation of yellow 
and white produced by these rays is strong enough to excite the retina. Hering 
divides his spectrum into a yellow and a blue half. A violet-blind person 
wants the yellow-blue visual substance; in his spectrum there are only two 
partial spectra, the black-white and the red-green. In cases of complete 
color-blindness, the yellow-blue and red-green substances are absent. 
Hence, such a person has only the sensation of bright and dark. The sensi- 
bility to light and the length of the spectrum are retained ; the brightest part 
in this case, as in the normal eye, is in the yellow (.Hering). 
397. COLOR-BLINDNESS AND ITS PRACTICAL IM- 
PORTANCE.—Causes.—By the term color-blindness (dyschroma 
topsy) is meant a pathological condition whereby some individuals are unable 
to distinguish certain colors. Huddart (1777) was acquainted with the condi- 
tion, but it was first accurately described by Dalton (1794), who himself was 
red-blind. The term color-blindness was given to it by Brewster. 
The supporters of the Young-Helmholtz theory assume that, corresponding 
to the paralysis of the three color-perceiving elements of the retina, there are 
the following kinds of color-blindness:— 
1. Red-blindness. 2. Green-blindness. 3. Violet-blindness. 
The highest degree being termed complete color-blindness. 
The supporters of E. Hering’s theory of color sensation distinguish the following kinds :— 
1. Complete Color-blindness (Achromatopsy).—The spectrum appears achromatic; the 
position of the greenish-yellow is the brightest, while it is darker on both sides of it. A colored 
picture appears like a photograph or an engraving. Occasionally the different degrees of light 
intensity are perceived in one shade of color, eg., yellow, which cannot be compared with any 
other color. O. Becker and v. Hippel observed cases of unilateral congenital complete color- 
blindness, whilst the other eye was normal for color perception. 
2. Blue-yellow Blindness.—The spectrum is dicnromatic, and consists only of red and 
green. The blue-violet end of the spectrum is usually greatly shortened. In pure cases only 
the red and green are correctly distinguished (Mauthner’s erythrochloropy), but not the other 
colors. Unilateral cases have been observed. 
3. Red-green Blindness.—The spectrum is also dichromatic. Yellow and blue are cor- 
rectly distinguished; violet and blue are both taken for blue. The sensations for red and green 
are absent altogether. There are several forms of this—(a) Green-blindness, or the red-green 
blindness, with undiminished spectrum (Mauthner’s xanthokyanopy), in which bright-green 
and dark-red are confounded. In the spectrum yellow abuts directly on blue, or between the 
two, at most, there is a strip of gray. The maximum of brightness is in the yellow. It is often 
unilateral and often hereditary. Red-blindness (or the red-green blindness with undimin- 
ished spectrum, also called Daltonism), in which bright-red and dark-green are confounded. 
The spectrum consists of yellow and blue, but the yellow lies in the orange. The red end of 
the spectrum is uncolored, or even dark. The greatest brightness, as well as the limit between 
yellow and blue, lies more towards the right. 
4. Incomplete color-blindness, or a diminished color sense, indicates the condition in 
which the acuteness of color perception is diminished, so that the colors can be detected only 
in large objects, or only when they are near, and when they are mixed with white, they no 
longer appear as such. A certain degree of this form is frequent, in as far as many persons are 
unable to distinguish greenish-blue from bluish green. 
Acquired color-blindness occurs in diseases of the retina and atrophy of the optic nerve 
in commencing tabes, in some forms of cerebral disease (§ 378, IV, 1), and intoxication. At 
first green-blindness occurs, which is soon followed by red-blindness. The peripheral zone of 
the retina suffers sooner than the central area. In hysterical persons there may be intermittent 
attacks of color-blindness (Charcot); and the same occurs in hypnotized persons (p. 873). 
H. Cohn found that, on heating the eyeball of some color-blind persons, the color-blindness 
disappeared temporarily. Occasionally in persons without a lens red vision is present, and is 
due to unknown causes. Percentage.—Holmgren found that 2.7 per cent, of persons were 
color-blind, most being red and green blind, and very few violet blind. 
Limits of Normal Color-blindness.—The investigations on the power of color-perception 
in the normal retina are best carried out by means of Aubert-Forster’s perimeter, or that of Sec. 397.] 
COLOR-BLINDNESS. 
987 
M’Hardy ($ 395). It is found that our color perception is coviplete only in the middle of the 
field of vision. Around this is a middle zone, in which only blue and yellow are perceived, in 
which, therefore, there is red-blindness. Outside this zone there is a peripheral girdle, where 
there is complete color-blindness (§ 395). Hence, a red-blind person is distinguished from a 
person with normal vision, in that the central area of the normal field of vision is absent in the 
former, this being rather included in the middle zone. The field of vision of a green-blind 
person differs from that of a person with normal vision, in that his peripheral zone corresponds 
to the intermediate and peripheral zones of the normal eye. The violet-blind person is distin- 
guished by the complete absence of the normal peripheral zone. The incomplete color blindness 
of these two kinds is characterized by a uniformly diminished central field. [When very intense 
colors are used, such as those of the solar spectrum, the retina can distinguish them quite up to 
its margin (Landolt).~\ 
In poisoning with santonin, violet-blindness (yellow vision) occurs in consequence of the 
paralysis of the violet perceptive retinal elements, which not unfrequently is preceded by stimu- 
lation of these elements, resulting in violet vision, i.e., objects seem to be colored violet (Hiifnei-). 
Such is the explanation of this phenomenon given by Holmgren. Max Schultze, however, 
referred the yellow vision, i.e., seeing objects yellow, to an increase of the yellow pigment in 
the macula lutea. 
When colored objects are very small, and illuminated only for a short time, the normal eye 
first fails to perceive red (Aubert); hence, it appears that a stronger stimulus is required to 
excite the sensation of red. Briicke found that very rapidly intermittent white light is per- 
ceived as green, because the short duration of the stimulation fails to excite the elements of the 
retina connected with the sensation of red. 
[The practical importance of color-blindness was pointed out by George Wilson, and 
again more recently by Holmgren.] No person should be employed in the marine or railway 
service until he has been properly certified as able to distinguish red from green. 
Methods of Testing Color-blindness.—Following Seebeck, Holmgren used small skeins 
of colored wools as the simplest material, in red, orange, yellow, greenish-yellow, green, 
greenish-blue, blue, violet, purple, rose, brown, gray. There are five finely graduated shades of 
each of the above colors. When testing a person, select only one skein—e.g., a bright green or 
rose—from the mass of colored wools placed in front of him, and place it aside, asking him to 
seek out those skeins which he supposes are nearest to it in color. 
Mace and Nacati have measured the acuteness of vision by illuminating a small object with 
different parts of the spectrum. They compared the observations on red- and green-blind' 
persons with their own results, and found that a red-blind person perceives green light as much 
brighter than it appears to a normal person. The green-blind had an excessive sensibility for 
red and violet. It appears that what the color-blind lose in perceptive power for one color 
they gain for another. They have also a keen sense for variations in brightness. 
398. STIMULATION OF THE RETINA.—As with every other 
nervous apparatus, a certain very short, but still determinable time elapses 
after the rays of light fall upon the eye before the action of the light takes 
place, whether the light acts so as to produce a conscious impression, or pro- 
duces merely a reflex effect upon the pupil. The strength of the impression 
produced depends partly and chiefly upon the excitability of the retina and 
the other nervous structures. If the light acts for a long time with equal 
intensity, the excitation, after having reached its culminating point, rapidly 
diminishes again, at first more rapidly, and afterwards more and more slowly. 
[When the retina is stimulated by light, there is (1) an effect on the 
rhodopsin (p. 943). (2) The electro-motive force is diminished (§ 332). (3) 
The processes of the hexagonal pigment-cells of the retina dipping between 
the rods and cones are affected; thus they are retracted in darkness, and pro- 
truded in the light (fig. 693). (4) Engelmann has shown that the length and 
shape of the cones vary with the action of light (p. 981). The cones are 
retracted in darkness and protruded under the influence of light (fig. 693). 
This alteration in the shape of the cones takes place even if the light acts on 
the skin, and not on the eyeball at all.] 
After-Images.—If the light acts on the eye for some time so as to excite 
the retina, and if it be suddenly withheld, the retina still remains for some 
time in an excited condition, which is more intense and lasts longer, the 
stronger and the longer the light may have been applied, and the more excit- 988 
AFTER-IMAGES. 
[Sec. 398. 
able the condition of the retina. Thus, after every visual perception, especially 
if it is very distinct and bright, there remains a so-called “ after-image.” 
We distinguish a “ positive after- 
image,” which is an image of similar 
brightness and a similar color. 
“ That the impression of any picture remains 
for some time upon the eye is a physiological phe- 
nomena; when such an impression can be seen for 
a long time it becomes pathological. The weaker 
the eye is the longer the image remains upon it. 
The retina does not recover itself so quickly, and 
we may regard the action as a kind of paralysis. 
This is not to be wondered at in the case of daz- 
zling pictures. After looking at the sun, the image 
may remain on the retina for several days. A 
similar result sometimes occurs with pictures which 
are not dazzling. Busch records that the impres 
sion of an engraving, with all its details, remained 
on his eye for 17 minutes” {Goethe). 
Experiments and Apparatus for Positive 
After-Images.—1. When a burning stick is 
rapidly rotated, it appears as a fiery circle. 
2. The Phanakistoscope (Plateau) or the 
stroboscopic discs (Stampfer). Upon a disc 
or cylinder, a series of objects is so depicted that 
successive drawings represent individual factors of one continuous movement. On looking 
through an opening at such a disc rotated rapidly, we see pictures of the different phases moving 
so quickly that each rapidly follows the one in front of it. As the impression of the one pic- 
ture remains until the following one takes its place, it has the appearance as if the successive 
phases of the movement were continuous and one and the same figure. The apparatus under 
the name of zoetrope, which is extensively used as a toy, is generally stated to have been 
invented in 1832. It was described by Cardanus in 1550. It may be used to represent certain 
movements, e.g., of the spermatozoa and ciliary motion, the movements of the heart and those 
of locomotion. 
3. The color top contains on the sectors of its disc the colors which are to be mixed. As 
the color of each sector leaves a condition of excitation for the whole duration of a revolution, 
all the colors must be perceived simultaneously, i. e., as a mixed color. 
[Illusions of Motion.—Silvanus P. Thompson points out that if a series of concentric 
circles in black and white be made on paper, and the sheet on which the circles are drawn be 
moved with a motion as if one were rinsing out a pail, but with a very minute radius, then all 
the circles appear to rotate with the same angular velocity as that imparted. Professor Thompson 
has contrived other forms of this illusion, in the form of strobic discs.] 
Negative After-Images.—Occasionally, when the stimulation of the 
retina is strong and very intense, a “negative,” instead of a positive after- 
image, appears. In a negative after-image, the bright parts of the object appear 
dark, and the colored parts in corresponding contrast colors (p. 990). 
Examples of Negative After-Images.—After looking for a long time at a dazzlingly- 
illuminated white window, on closing the eyes we have the impression of a bright cross, or 
crosses, as the case may be, with dark panes. 
Negative colored after-images are beautifully shown by Norrenberg’s apparatus. Look steadily 
at a colored surface, e.g., a yellow board with a small blue square attached to the centre of its 
surface. A white screen is allowed to fall suddenly in front of the board—the white surface now 
has a bluish appearance, with a yellow square in its centre. 
The usual explanation of dark negative after-images is that the retinal elements are fatigued 
by the light, so that for some time they become less excitable, and consequently light is but 
feebly perceived in the corresponding areas of the retina; hence, darkness prevails. 
Hering explains the dark after images as due to a process of assimilation in the black-white 
visual substance. In explaining colored after-images, the Young-Helmholtz theory assumes that, 
under the action of the light waves, e.g., red, the retinal elements connected with the perception 
of this color are paralyzed. On now looking suddenly on a white surface, the mixture of all 
the colors appears as white minus red, i. e., the white appears green. In bright daylight the 
contrast color lies very near the complementary color. According to Hering, the contrast after- 
The cones of the retina and pigment-cells 
(of the frog) as affected by light and dark- 
ness: i, after two days in darkness; 2, 
after ten minutes in daylight. 
Fig. 693. Sec. 398.] 
IRRADIATION. 
989 
image is explained by the assimilation of the corresponding colored visual substance, in this 
case, of the “red-green” (g 397). From the commencement of a momentary illumination 
until the appearance of an after-image, 0.344 sec. elapses (v. Vintschgau and Lustig). 
Not unfrequently, after intense stimulation of the retina, positive and negative 
after-images alternate with each other until they gradually fuse. After looking 
at the dark-red setting sun we see alternately 
discs of red and green. 
The phenomena of contrast undergo some 
modification in the DeriDheral areas of the retina. 
Fig. 694. 
For irradiation. 
For irradiation. 
Fig. 695. 
owing to the partial color-blindness which occurs in these areas (Adamiick and 
Woinow). 
Irradiation is the term applied to certain phenomena where we form a false 
estimate of visual impressions, owing to inexact accommodation. If, from 
inexact accommodation, the margins of the object are projected upon the retina 
in diffusion circles, the mind tends to add the undefined margin to those parts 
of the visual image which are most prominent in the image itself. What is 
bright appears larger and overcomes what is dark, while an object, without ref- 
erence to brightness or color, has the same relation to its background (fig. 694). 
When the accommodation is quite accurate, the phenomenon of irradiation is 
not present. [On looking at fig. 695 from a distance, the white squares appear 
larger and as if they were united by a white band.] 
“A dark object appears smaller than a bright one of the same size. On looking at the same 
time from a certain distance at two circles of the same size, a white one on a black background, 
and a black one on a white background, we estimate the latter to be about one-fifth less than the 
former (fig. 694). On making the black circle one-fifth larger they will appear equal. Tycho 
de Brahe remarks that the moon, when in conjunction (dark), appears to be one-fifth smaller 
than in opposition (full, bright). The first lunar crescent appears to belong to a larger disc than 
the dark one adjoining it, which can occasionally be distinguished at the time of the new light. 
Black clothes make persons appear to be much smaller than light clothes. A light seen behind 
a margin gives the appearance of a cut in the margin. A ruler, behind which is placed a lighted 
candle, appears to the observer to have a notch in it. The sun, when rising and setting, appears 
to make a depression in the horizon” (Goethe). 
[Contrast.—The fundamental phenomena are such as these, that a bright 
object looks brighter surrounded by objects darker than itself; and darker with 
surroundings brighter than itself. There may be contrasts either with bright 
or dark objects or with colored ones.] 
Simultaneous Contrast.—By this term is meant a phenomenon like the 
following: When bright and dark parts are present in a picture at the same 
time, the bright (white) parts always appear to be more intensely bright the 
less white there is near them, or, what is the same thing, the darker the sur- 
roundings, and, conversely, they appear less bright the more white tints that 
are present near them. A similar phenomenon occurs with colored pictures. 
A color in a picture appears to us to be more intense the less of this color there 
is in the adjoining parts, that is, the more the surroundings resemble the tints 990 
CONTRAST. 
[Sec. 398. 
of the contrast color. Simultaneous contrast arises from simultaneous impres- 
sions occurring in two adjoining and different parts of the retina. 
Examples of Contrast for Bright and Dark.— i. Look at a white network on a black 
ground; the parts where the white lines intersect appear darker, because there is least black 
near them. 
2. Look at a point of a small strip of dark gray paper in front of a dark black background. 
Push a large piece of white paper between the strip and the background ; the strip on the white 
ground now appears to be much darker than before. On again removing the white paper, the 
strip at once again appears bright (liering). 
3. Look with both eyes towards a grayish-white surface, e.g., the ceiling of a room. After 
gazing for some time, place in front of the eye a paper tube eight inches long, and an inch to an 
inch and a quarter in diameter, blackened in the inside. The part of the ceiling seen through 
the tube appears as a round white spot (Landois). 
Examples for Colors.—1. Place a piece of gray paper on a red, yellow, or blue ground ; 
the contrast colors appear at once, viz., green, blue, or yellow. The phenomenon is made still 
more distinct by covering the whole with transparent tracing paper (Herm. Meyer). Under 
similar circumstances, printed matter on a colored ground appears in its complementary color 
(W. v. Bezold). 
2. An air-bubble in the strongly tinged field of vision of a thick microscopical preparation 
appears with an intense contrast color (Landois). 
3. Paste four green sectors upon a rotatory white disc, leave a ring round the centre of the disc 
uncovered by green, and cover it with a black strip. On rotating such a disc the black part 
appears red and not gray (Briicke). 
4. Look with both eyes towards a grayish-white surface, and place in front of one eye a tube 
about the length and breadth of a finger, composed of transparent oiled paper, gummed together 
to such thickness as will permit light to pass through its walls. The part of the surface seen 
through the tube appears in its contrast color. The experiment also shows the contrast in the 
intensity of the illumination (Landois). A white piece of paper, with a round black spot in its 
centre, when looked at through a blue glass, appears blue with a black spot. If a white spot 
of the same size on a black ground be placed in front, so that it is reflected in the glass plate 
and just covers the black spot, it shows the contrast color yellow (Ragona Scina). 
5. The colored shadows also belong to the group of simultaneous contrasts. “Two condi- 
tions are necessary for the production of colored shadows—firstly, that the light gives some kind 
of a color to the white surface; second, that the shadow is illuminated, to a certain extent, by 
another light. During the twilight, place a short lighted candle on a white surface, between it 
and the fading daylight hold a pencil vertically, so that the shadow thrown by the candle is 
illuminated, but not abolished, by the feeble daylight; the shadow appears of a beautiful blue. 
The blue shadow is easily seen, but it requires a little attention to observe that the white paper 
acts like a reddish-yellow surface, whereby the blue color apparent to the eye is improved. One 
of the most beautiful cases of colored shadows is seen in connection with the full moon. The 
light of the candle and that of the moon can be completely equalized. Both shadows can 
be obtained of equal strength and distinctness, so that both colors are completely balanced. 
Place the plate opposite the light of the moon, the lighted candle a little to one side at a suitable 
distance. In front of the plate hold an opaque body, when a double shadow appears, the one 
thrown by the moon and lighted by the candle being bright reddish-yellow; and, conversely, 
the one thrown by the candle and lighted by the moon appears of a beautiful blue. Where 
the two shadows come together and unite is black” (Goethe). 
6. “ Take a plate of green glass of considerable thickness and hold it so as to get the bars of 
a window reflected in it, the bars will be seen double, the image formed by the under surface 
of the glass being green, while the image coming from the under surface of the glass, and which 
ought really to be colorless, appears to be purple. The experiment may be performed with a 
vessel filled with water, with a mirror at its base. With pure water colorless images are obtained, 
while by coloring the water colored images are produced” (Goethe). 
Explanation of Contrast.—Some of these phenomena may be explained as due to an error 
of judgment. During the simultaneous action of several impressions, the judgment errs, so that 
when an effect occurs at one place, this acts to the slightest extent in the neighboring parts. 
When, therefore, brightness acts upon a part of the retina, the judgment ascribes the smallest 
possible action of the brightness to the adjoining parts of the retina. It is the same with colors. 
It is far more probable that the phenomena are to be referred to actual physiological processes 
(Hering). Partial stimulation with light affects not only the parts so acted on but also the sur- 
rounding area of the retina (p. 985); the part directly excited undergoing increased disassimi- 
lation, the (indirectly stimulated) adjoining area undergoing increased assimilation ; the increase 
of the latter is greatest in the immediate neighborhood of the illuminated portion, and rapidly 
diminishes as the distance from it increases. By the increase of the assimilation in those parts Sec. 398.] 
MOVEMENTS OF THE EYEBALL. 
not acted on by the image of the object, this is prevented, so that the diffused light is perceived. 
The increase of the assimilation in the immediate neighborhood of the illuminated spot is greatest, 
so that the perception of this relatively stronger different light is largely rendered impossible 
{ He ring). 
[Helmholtz thus ascribed the phenomena of contrast to psychical conditions, i. e , errors of 
judgment, but this explanation is certainly not complete. A far more satisfactory solution of the 
problem is that of Hering, that stimulation of one part of the retina affects the condition of ad- 
joining parts. If a white disc on a black background be looked at for a time, and then the eyes 
be closed, a negative after-image of the disc appears, but it is darker and blacker than the visual 
area, and it has a light area around, brightest close to the disc, i. e., the adjacent part of the retina 
is affected. This Hering has called successive light induction.] 
Successive Contrast.—Look for a long time at a dark or bright object, or at a colored (e. g. 
red) one, and then allow the effect of the contrast to occur on the retina, i. e., with reference to 
the above, bright and dark, or the contrast color green, then these become very intense. This 
phenomenon has also been called “ successive contrast.” In this case the negative after-image 
obviously plays a part. 
[Some drugs cause subjective visual sensations, but these do so by acting on the brain, e. g., 
alcohol, as in delirium tremens, cannabis indica, sodic salicylate, and large doses of digitalis 
(Brunt on).] 
399. MOVEMENTS OF THE EYEBALLS—EYE MUSCLES. 
—The globular eyeball is capable of extensive and free movement on the cor- 
respondingly excavated fatty pad of the orbit, just like the head of a long bone 
in the corresponding socket of a freely movable arthroidal joint. The move- 
ments of the eyeball, however, are limited by certain conditions, by the mode 
in which the eye muscles are attached to it. Thus, when one muscle contracts, 
its antagonistic muscle acts like a bridle, and so limits the movement; the 
movements are also limited by the insertion of the optic nerve. The soft 
elastic pad of the orbit on which the eyeball rests is itself subject to be moved 
forward or backward, so that the eyeball also must participate in these move- 
ments. 
Protrusion of the eyeball takes place—1. By congestion of the blood-vessels, especially of 
the veins in the orbit, such as occurs when the outflow of the venous blood from the head is 
interfered with, as in cases of hanging. 2. By contraction of the smooth muscular fibres in 
Tenon’s capsule, in the spheno maxillary fissure, and in the eyelids (£ 404), which are innervated 
by the cervical sympathetic nerve. 3. By voluntary forced opening of the palpebral fissure, 
whereby the pressure of the eyelids acting on the eyeball is diminished. 4. By the action of the 
oblique muscles, which act by pulling the eyeball inwards and forwards. If the superior oblique 
be contracted when the eyelids are forcibly opened, the eyeball may be protruded about 1 mm. 
When protrusion of the eyeball occurs pathologically (as in I and 2), the condition is called 
exophthalmos. 
Retraction of the eyeball is the opposite condition, and is caused—I. By closing the eye- 
lids forcibly. 2. By an empty condition of the retrobulbar blood-vessels, diminished succulence, 
or disappearance of the tissue of the orbit. 3. Section of the cervical sympathetic in dogs causes 
the eyeball to sink somewhat in the orbit. The smooth muscular fibres of Tenon’s capsule are 
perhaps antagonistic in their action to the four recti when acting together, and thus prevent the 
eyeball from being drawn too far backwards. Many animals have a special retractor bulbi 
muscle, e. g., amphibians, reptiles, and many mammals; the ruminants have four. 
The movements of the eyes are almost always accompanied by similar move- 
ments of the head, chiefly on looking upwards, less so on looking laterally, and 
least of all when looking downwards. 
The difficult investigations on the movements of the eyeballs have been carried out, especially 
by Listing, Meissner, Helmholtz, Donders, A. Fick, and E. Hering. 
Axes.—All the movements of the eyeball take place round its point of 
rotation (fig. 696, O), which lies 1.77 mm. behind the centre of the visual 
axis, or 10.957 111111 • from the vertex of the cornea (.Donders). In order to 
determine more carefully the movements of the eyeball, it is necessary to have 
certain definite data : 1. The visual axis (S, or the antero-posterior axis 
of the eyeball, unites the point of rotation with the fovea centralis, and is con- 992 
MOVEMENTS OF THE EYEBALL. 
[Sec. 399. 
tinued straight forwards to the vertex of the cornea. 2. The transverse, or 
horizontal axis (Q, is the straight line connecting the points of rotation 
of both eyes and its extension outwards. Of course, it is at right angles to i. 
3. The vertical axis passes vertically through the point of rotation at right 
angles to 1 and 2. These three axes form a co-ordinate system. We must 
imagine that in the orbit there is a fixed determinate axial system, whose point 
of intersection corresponds with the point of rotation of the eyeball. When 
the eye is at rest (primary position), the three axes of the eyeball completely 
coincide with the three axes of the co-ordinate system in the orbit. When the 
eyeball, however, is moved, two or more axes are displaced from this, so that 
they must form angles with the fixed orbital system. 
Planes of Separation.—In order to be more exact, and also partly for 
further estimations, let us suppose three planes passing through the eyeball, and 
that their position is secured by any two axes. 1. The horizontal plane of 
separation divides the eyeball into an upper and lower half; it is determined 
by the visual transverse axis. In its course through the retina it forms the hori- 
zontal line of separation of the latter; the coats of the eyeball itself cut 
it in their horizontal meridian. 2. The vertical plane divides the eyeball 
into an inner and outer half; it is determined by the visual and vertical axes. 
It cuts the retina in the vertical line of separation of the latter and the 
periphery of the bulb in the vertical meridian of the eyeball. 3. The equato- 
rial plane divides the eyeball into an anterior and posterior half; its position 
is determined by the vertical and transverse axes, and it cuts the sclerotic in 
the equator of the eyeball. The horizontal and vertical lines of separation of 
the retina, which intersect in the fovea centralis, divide the retina into four 
quadrants. 
In order to define more precisely the movements of the eyeball, v. Helmholtz has introduced 
the following terms: He calls the straight line which connects the point of rotation of the eye 
with the fixed point in the outer world, the visual line (“ Blicklinie ”), while a plane passing 
through these lines in both eyes he called the visual plane ; the ground line of this plane is the 
line uniting the two points of rotation, viz., the transverse axis of the eyeball. Suppose a 
sagittal section (antero-posterior) to be made through the head, so as to divide the Utter into a 
right and left half, then this plane would halve the ground line of the visual plane, and when 
prolonged forward would intersect the visual plane in the median line. The visual point of the 
eye can be (1) raised or lowered—the field which it traverses being called the visual field 
(“ Blickfeld ”); it is part of a spherical surface with the point of rotation of the eye in its 
centre. Proceeding from the primary position of both eyes, which is characterized by both 
visual lines being parallel with each other and horizontal, then the elevation of the visual plane 
can be determined by the angle which this forms with the plane of the primary position. This 
angle is called the angle of elevation—it is positive when the visual plane is raised (to the fore- 
head), and negative when it is lowered (chinwards). (2) From the primary position the visual 
line can be turned laterally in the visual plane. The extent of this lateral deviation is measured 
by the angle of lateral rotation, i. e., by the angle which the visual line forms with the 
median line of the visual plane; it is said to be positive when the posterior part of the visual 
line is turned to the right, negative when to the left. The following are the positions of the 
eyeball:— 
1. Primary position [or “position of rest”], in which both the lines of 
vision are parallel with each other, and the visual planes are horizontal. The 
three axes of the eyeball coincide with the three fixed axes of the co-ordinate 
system in the orbit. 
2. Secondary positions are due to movements of the eye from the primary 
position. There are two different varieties—(a) where the visual lines are 
parallel, but are directed upwards or downwards. The transverse axis of both 
eyes remains the same as in the primary position ; the deviations of the other 
two axes expressed by the amount of the angle of elevation of the line of 
vision. (b) The second variety of the secondary position is produced by the 
convergence or divergence of the lines of vision. In this variety the vertical Sec. 399.] 
POSITIONS OF THE EYEBALL. 
993 
axis, round which the lateral rotation takes place, remains as in the primary 
position ; the other axes form angles; the amount of the deviation is expressed 
by the “angle of lateral rotation.” The eye, when in the primary position, 
can be rotated from this position 420 outwards, 450 inwards, 340 upwards, and 
57° downwards (Schuurmann). 
3. Tertiary position is the position brought about by the movements of 
the eye, in which the lines of vision are convergent, and are at the same time 
inclined upwards or downwards. 
[Listing’s Law is that which expresses the movements of the eyeball. When the eyeball 
moves from the primary position, or position of rest, the angle of rotation of the eye in the 
Fig. 696. 
Scheme of the action of the ocular muscles. 
second position is the same as if the eye were turned about a fixed axis perpendicular to both 
the first and the second positions of the visual line {Helmholtz).] 
All the three axes of the eye are no longer coincident with the axes in the 
primary position. The exact direction of the visual lines is determined by the 
amount of the angle of lateral rotation and the angle of elevation. There is 
still another important point. The eyeball is always rotated at the same time 
round the line of vision and round its axis (Volkmann, Hering). As the iris 
rotates round the visual line like a wheel round its axis, this rotation is called 
“ circular rotation ” (“Raddrehung"') of the eye, which is always connected 
with the tertiary positions. Even oblique movements may be regarded as com- 
posed of—(i) a rotation round the vertical axis, and (2) round the transverse OCULAR MUSCLES. 
[Sec. 399. 
axis; or it may be referred to rotation round a single constant axis placed 
between the above-named axes, passing through the point of rotation of the 
eyeball, and at right angles to the secondary and primary direction of the visual 
axis (line of vision)—(.Listing). The amount of circular rotation is measured 
by the angle which the horizontal separation line of the retina forms with the 
horizontal separation of the retina of the eye in the primary position. This 
angle is said to be positive, when the eye itself rotates in the same direction as 
the hand of a watch observed by the same eye, i. e., when the upper end of the 
vertical line of separation of the retina is turned to the right. 
According to Donders, the angle of rotation increases with the angle of elevation and the 
angle of lateral rotation—it may exceed io°. With equally great elevation or depression of the 
visual plane, the rotation is greater, the greater the elevation or depression of the line of vision. 
On looking upwards in the tertiary position, the upper ends of the vertical lines of separation 
of the retina diverge ; on looking downwards they converge. If the visual plane be raised, the 
eye, when it deviates laterally to the right, makes a circular rotation to the left. When, the 
visual plane is depressed, on deviating the eye to the right or left, there is a corresponding circu- 
lar rotation to the right or left. Or we may express the result thus : When the angle of eleva- 
tion and the angle of deviation have the same sign (-)- or —), then the rotation of the eye- 
ball is negative; when, however, the signs are unequal, the rotation is positive. In order to 
make the circular rotation visible in one’s own eye, accommodate one eye for a surface divided 
by vertical and horizontal lines until a positive after-image is produced, and then rapidly rotate 
the eye into the third position. The lines of the after-image then form angles with the lines of 
the background. As the position of the vertical meridian of the eye is important from a practi- 
cal point of view, it is necessary to note that, in the primary and secondary positions of the eyes, 
the vertical meridian retains its vertical position. On looking to the left and upwards, or to the 
right and downwards, the vertical meridians of both eyes are turned to the left; conversely, they 
are turned to the right on looking to the left and downwards, or to the right and upwards. 
In the secondary positions of the eye, rotation of the axis of the eye never occurs (Listing). 
Very slight rolling of the eyes occurs, however, when the head is inclined towards the shoulder, 
and in the direction opposite to that of the head; it is about i° for every io° of inclination of 
the head (Skrebitzk). 
Ocular Muscles.—The movements of the eyeball are accomplished by 
means of the four straight and two oblique ocular muscles (fig. 697). In 
order to understand the action of each of these muscles, we must know the 
plane of traction of the muscles and the axis of rotation of the eyeball. The 
plane of traction is found by the plane lying in the middle of the origin and 
insertion of the muscle and the point of rotation of the eyeball. The axis of 
rotation is always at right angles to the plane of traction in the point of rota- 
tion of the eyeball. 
1. The rectus internus (I) and externus (E) rotate the eye almost ex- 
actly inwards and outwards (fig. 696). The plane of traction lies in the plane 
of the paper; Q, E, is the direction of the traction of the external rectus ; 
Qx, I, that of the internal. The axis of rotation is in the point of rotation, 
O, at right angles to the plane of the paper, so that it coincides with the verti- 
cal axis of the eyeball. 2. The axis of rotation of the R. superior and in- 
ferior (the dotted line, R. sup., R. inf.), lies in the horizontal plane of sepa- 
ration of the eye, but it forms an angle of about 20° wijh the transverse axis 
(Q, Qx); the direction of the traction for both muscles is indicated by the 
line, s. i. By the action of these muscles, the cornea is turned upwards and 
slightly inwards, or downwards and slightly inwards. 3. The axis of rotation 
of both oblique muscles (the dotted lines, Obi. sup. and Obi. inf.) also lies in 
the horizontal plane of separation of the eyeball, and it forms an angle of 6o° 
with the transverse axis. The direction of the traction of the inferior oblique 
gives the line, a, b; that of the superior, the line, c. d. The action of these 
muscles, therefore, is in the one case to rotate the cornea outwards and upwards, 
and in the other outwards and downwards. These actions, of course, only Sec. 399.] 
MUSCLES OF THE EYEBALL, 
995 
obtain when the eyes are in the primary position—in every other position the 
axis of rotation of each muscle changes. ! 
When the eyes are at rest, the muscles are in equilibrium. Owing to the 
power of the internal recti, the visual axes converge and would meet, if pro- 
longed 40 centimetres in front of the eye. In the movements of the eyeball, 
one, two, or three muscles may be concerned. One muscle acts only when 
the eye is moved directly outwards or inwards, especially the internal and ex- 
ternal rectus. Two muscles act when the eyeball is moved directly upwards 
(superior rectus and inferior oblique) or downwards (inferior rectus and superior 
oblique). Three muscles are in action when the eyeballs take a diag- 
onal direction, especially for inwards and upwards, by the internal and the 
superior rectus and inferior oblique ; for inwards and downwards, the internal 
and inferior rectus and superior oblique ; for outwards and downwards, the ex- 
Fig. 697. 
Lateral view of the muscles of the eyeball. 5, Trochlea or pulley of the superior oblique mus- 
cle, 12. 6, Optic nerve. 8, Superior, 9, inferior, and 12, external rectus. 13, Inferior 
oblique. 
ternal and inferior rectus and superior oblique ; for outwards and ttpwards, the 
external and superior rectus and inferior oblique. 
[The following table shows the action of the muscles of the eyeball:— 
Inwards, Rectus internus. 
Outwards, Rectus externus. 
Rectus internus. 
Rectus inferior. 
Obliquus superior. 
Upwards, 
Rectus superior. 
Obliquus inferior. 
Inwards and 
downwards, 
Downwards, 
Rectus inferior. 
Obliquus superior. 
Outwards and 
upwards, 
Rectus externus. 
Rectus superior. 
Obliquus inferior. 
Inwards and 
upwards 
Rectus internus. 
Rectus superior. 
Obliquus inferior. 
Outwards and 
downwards, 
Rectus externus. 
Rectus inferior. 
Obliquus superior. 
Ruete imitated the movements of the eyeballs by means of a model, which he called the 
ophthalmotrope. 
The extent of the movements of the eyeball and its length diminish with age. The mobility 
is less in the vertical than in the lateral direction, and less upwards than downwards. The 
normal and myopic eye can be moved more outwards, and the long-sighted eye more inwards; 996 
BINOCULAR VISION. 
[Sec. 399. 
the external and internal recti act most when the eye is moved outwards, the oblique when it 
is rotated inwards. An eye can be turned inwards to a greater extent when the other eye at 
the same time is turned outwards than when the other is turned inwards. During near vision, 
the right eye can be turned less to the right, and the left to the left, than during distant vision 
(Bering). 
Simultaneous Ocular Movements.—Both eyes are always moved simul- 
taneously. Even when one eye is quite blind the ocular muscles move when 
the whole eyeball is excited. When the head is straight the movements always 
take place so that both visual planes (visual axes) lie in the same plane. In 
front both visual axes can diverge only to a trifling extent, while they can con- 
verge considerably. If individual ocular muscles are paralyzed, the position 
of the visual axis in the same plane is disturbed, and squinting results, so that 
the patient no longer can direct both visual axes simultaneously to the same 
point, but he directs the one eye after the other. Even nystagmus (p. 920) 
occurs in both eyes simultaneously and in the same direction. The innate 
simultaneous movement of both eyes is spoken of as an associated movement 
(Joh. Milller). E. Hering showed that in all ocular movements there is a 
uniformity of the intiervation as well. Even during such movements in which 
one eye apparently is at rest, there is a movement, due to the action of two 
antagonistic forces, the movements resulting in a slight to and fro motion of 
the eyeball. 
The motor nerves of the ocular muscles are the oculomotorius ($ 345), the trochlearis (§ 346), 
and the abducens (g 348). The centre lies in the corpora quadrigemina, and below it ($ 379), 
and partly in the medulla oblongata (§ 379). 
400. BINOCULAR VISION.—Advantages.—Vision with both eyes 
affords the following advantages: (1) The field of vision of both eyes is con- 
siderably larger than that of one eye. (2) The perception of depth is rendered 
easier, as the retinal images are obtained from two different points. (3) A 
more exact estimate of the distance and size of an object can be formed, in 
consequence of the perception of the degree of convergence of both eyes. (4) 
The correction of certain errors in the one eye is rendered possible by the other. 
When the position of the head is fixed, we can easily form a conception as to the form of the 
entire field of vision if we close one eye and direct the open eye inwards. We observe that it is 
pear-shaped, broad above and smaller below, the silhouette, or profile of the nose, causes the 
depression between the upper and lower part of the field. 
401. IDENTICAL POINTS—HOROPTER.—Identical Points. 
—If we imagine the retinae of both eyes to be a pair of hollow saucers placed 
one within the other, so that the yellow spots of both eyes coincide, and also 
the similar quadrants of the retinae, then all those points of both retinae which 
coincide or cover each other are called “identical” or “corresponding 
points” of the retina. The two meridians which separate the quadrants 
coinciding with each other are called the “ lines of separation.” Physio- 
logically, the identical points are characterized by the fact that, when they are 
both simultaneously excited by light, the excitement proceeding from them is, 
by a psychical act, referred to one and the same point of the field of vision, 
lying, of course, in a direction through the nodal point of each eye. Stimula- 
tion of both identical points causes only one image in the field of vision. Hence 
all those objects of the external world whose rays of light pass through the 
nodal points to fall upon identical points of the retina, are seen singly, because 
their images from both eyes are referred to the same point of the field of vision, 
so that they cover each other. All other objects whose images do not fall upon 
identical points of the retina cause double vision, or diplopia. 
Proofs.—If we look at a linear object with the points r, 2, 3, then the corresponding retinal 
images are 1, 2, 3, and 1, 2, 3, which are obviously identical points of the retinae (fig. 698). If, Sec. 401.] 
HOROPTER. 
997 
while looking at this line, there be a point, A, nearer the eyes, or B, further from them, then, 
on focussing for 1,2, 3, neither the rays (A, a, A, a) coming from A, nor those (B, b, B, b) from 
B, fall upon identical points; hence A and B appear double. 
Make a point (e.g., 2) with ink on paper; of course the image will fall upon both foveae cen- 
trales of the retinae (2, 2)-, which of course are identical points. Now press laterally upon one 
eye, so as to displace it slightly, then two points at once appear, because the image of the point 
no longer falls upon the fovea centralis of the displaced eye, but on an adjoining non-identical 
part of the retina. When we squint voluntarily all objects appear double. 
The vertical surfaces of separation of the retina do not exactly coincide with the vertical 
meridians. There is a certain amount of divergence (o.5°-3°), less above, which varies in 
different individuals, and it may be in the same individual at different times (Hering). The 
horizontal lines of separation, however, coincide. Images which fall upon the vertical lines of 
separation appear to be vertical to those on the horizontal lines, although they are not actually 
so. Hence, the vertical lines of separation are the apparent vertical meridians. Some observers 
regard the identical points of the retina as an acquired arrangement; others regard it as nor- 
mally innate. Persons who have had a squint from their birth see singly; in these cases, the 
identical points must be differently disposed. 
The horopter represents all those points of the outer world from which rays 
of light passing into both eyes fall upon identical points of the retina, the eyes 
being in a certain position. It varies with the different positions of the eyes. 
Scheme of identical and non-identical points 
of the retina. 
Fig. 698. 
Horopter for the secondary position, with 
convergence of the visual axes. 
Fig. 699. 
1. In the primary position of both eyes with the visual axes parallel, the rays of direction 
proceeding from two identical points of the two retinse are parallel and intersect only at infinity. 
Hence for the primary position the horopter is a plane in infinity. 
2. In the secondary position of the eyes with converging visual axes, the horopter for the 
transverse lines of separation is a circle which passes through the nodal points of both eyes (fig. 
699, K, Kx), and through the fixed points I, II, III. The horopter of the vertical lines of sepa- 
ration is in this position vertical to the plane of vision. 
3. In the symmetrical tertiary position, in which the horizontal and vertical lines of separa- 
tion form an angle, the horopter of the vertical lines of separation is a straight line inclined 
towards the horizon. There is no horopter for the identical points of the horizontal lines of sepa- 
ration, as the lines of direction prolonged from the identical points of these points do not 
intersect. 
4. In the unsymmetrical tertiary position (with rolling) of the eyes, in which the fixed point 
lies at unequal distances from both nodal points, the horopter is a curve of a complex form. 
All objects, the rays proceeding from which fall upon non-identical points 998 
STEREOSCOPIC VISION. 
[Sec. 401. 
of the retinae, appear double. We can distinguish direct or crossed double 
images, according as the rays prolonged from the non-identical points of the 
retina intersect in front of or behind the fixed point. 
Experiment.—Hold two fingers — the one behind the other—before both eyes. Accommodate 
for the far one and then the near one appears double, and when we accommodate for the near 
one the far one appears double. If, when accommodating for the near one, the right eye be 
closed, the left (crossed) image of the far finger disappears. On accommodating for the far 
finger and closing the right eye, the right (direct) double image of the near finger disappears. 
Double images are referred to the proper distance from the eyes just as single 
images are. 
Neglect of Double Images.—Notwithstanding the very large number of 
double images which must be formed during vision, they do not disturb 
vision. As a general rule, they are “neglected,” so that the attention must, 
as a rule, be directed to them before they are perceived. This condition is 
favored thus :— 
1. The attention is always directed to the point of the field of vision which is accommodated 
for at the time. The image of this part is projected on to both yellow spots, which are identical 
points of the retina. 
2. The form and color of objects on the lateral parts of the retina are not perceived so 
sharply. 
Stereoscopic views of blocks of wood 
Fig. 700. 
3. The eyes are always accommodated for those points which are looked at. Hence, indistinct 
images with diffusion circles are always formed by those objects which yield double images, so 
that they can be more readily neglected. 
4. Many double images lie so close together that the greater part of them, when the images 
are large, covers the other. 
5. By practice images which do not exactly coincide may be united. 
402. STEREOSCOPIC VISION.—On looking at an object, both eyes 
do not yield exactly similar images of that object—the images are slightly differ- 
ent, because the two eyes look at the object from two different points of view. 
With the right eye we can see more of the side of the body directed towards it, 
and the same is the case with the left eye. Fig. 700 shows the appearance of 
blocks of wood as viewed by the right and left eyes respectively. Notwith- 
standing this inequality, the two images are united. How two different images 
are combined is best understood by analyzing the stereoscopic images. 
Let, in fig. 701, L and R represent two such images as are obtained with the left and right 
eyes. These images, when seen with a stereoscope, look like a truncated pyramid, which pro- Sec. 402.] 
STEREOSCOPIC VISION. 
999 
jects towards the eye of the observer, as the points indicated by the same signs cover each other. 
On measuring the distance of the points, which coincide or cover each other in both figures, we 
find that the distances A, a, B, b, C, c, D, d are equally great, and at the same time are the 
widest of all the points of both figures ; the distances E, e, F, f, G,g, H, h are also equal, but are 
smaller than the former. On looking at the coinciding lines (A, E, a, e, and B, F, b,f), we 
observe that all the points of this line which lie nearer to A a and B b are further apart than 
those lying nearer E e and F f. 
Comparing these results with the stereoscopic image, we have the following 
laws for stereoscopic vision : i. All those points of two stereoscopic images, 
and of course of two retinal images of an object, which in both images are 
equally distant from each other, appear on the same plane. 2. All points which 
are nearer to each other, compared with the distance of other points, appear to 
be nearer to the observer. 3. Conversely, all points 
which lie further apart from each other appear per- 
in the background. 
The cause of this phenomenon lies in the fact 
that, “ in vision with both eyes we constantly refer 
the position of the individual images in the direc- 
tion of the visual axis to where they both intersect.” 
Proofs.—The following stereoscopic experiment proves this 
(fig. 703) : Take both images of two pairs of points (a, b, 
and a, p), which are at unequal distances from each other on 
the surface of the paper. By means of small stereoscopic 
prisms cause them to coincide, then the combined point, A of a, 
and a appears at a distance on the plane of the paper, while the other point, B, produced by the 
superposition of b and /?, floats in the air before the observer. Fig. 703 shows how this occurs. 
The following experiment shows the same result: Draw two figures, which are to be superposed 
similar to the lines B A, A E, b a, and a e, in fig. 701. In the lines B A, and b a, all the points 
which are to be superposed lie equally distant from each other, while, on the contrary, all the 
points in A E, and a e, which lie nearer E and e, are constantly nearer to each other. When 
looked at with a stereoscope, the superposed verticals, A B, and a b, lie in the plane of the paper, 
while the superposed lines, A E, and a e, project obliquely towards the observer from the plane of 
the paper. From these two fundamental experiments we may analyze all pairs of stereoscopic 
pictures. Thus, in fig. 701, if we exchange the two pictures, so that R lies in the place of L, 
then we must obtain the impression of a truncated hollow pyramid. 
Two stereoscopic pictures, which are so constructed that the one contains the body from the 
front and above, and the other it from the front and below (suppose in fig. 702 the lines A B, and 
a b, were the ground lines), can never be superposed by means of the stereoscope. 
This process has been explained in another way. Of the two figures, R and 
L (fig. 701), only A B C D, and abed, fall upon identical points of the retina, 
hence these alone can be superposed ; or, when there is a different convergence 
of the visual axis, only E F G H, and e f g h, can be superposed, for the same 
reason. Suppose the square ground surfaces of the figures are first superposed, 
in order to explain the stereoscopic impression, it is further assumed that both 
eyes, after superposition of the ground squares, are rapidly moved towards the 
apex of the pyramid. As the axis of the eyes must thereby converge more 
and more, the apex of the pyramid appears to project, as all points which re- 
quire the convergence of the eyes for their vision appear to us to be nearer 
(see p. 1000). Thus, all corresponding parts of both figures would be brought, 
one after the other, upon identical points of the retina by the movements of the 
eyes (.Briicke). 
It has been urged against this view that the duration of an electrical spark 
suffices for stereoscopic vision (Dove)—a time which is quite insufficient for the 
movements of the eyes. Although this may be true for many figures, yet in the 
correct combination of complex or extraordinary figures, these movements of 
the visual axes are not excluded, and in many individuals they are distinctly 
Fig. 701. 
Two stereoscopic drawings. 1000 
STEREOSCOPES. 
[Sec. 402. 
advantageous. Not only the actual movements necessary for this act, but the 
sensations derived from the muscles are also-concerned. 
When two figures are momentarily combined to form a stereoscopic picture, 
there being no movement of the eyes, clearly many points in the stereoscopic 
pictures are superposed which, strictly speaking, do not fall upon identical 
points of the retina. Hence we cannot characterize the identical points of the 
retina as coinciding mathematically; but from a physiological point of view 
we must regard such points as identical, which, as a rule, by simultaneous 
stimulation, give rise to a single image. The mind obviously plays a part in 
this combination of images. There is a certain psychical tendency to fuse the 
double images on the retinae into one image, in accordance with the fact that 
we, from experience, recognize the existence of a single object. If the 
differences between two stereoscopic pictures be too great, so that parts of the 
Fig. 702. 
F'g- 7°3- 
Wheatstone’s stereoscope. 
Scheme of Brewster's stereoscope 
retina too wide apart are excited thereby, or when new lines are present in a 
picture, and do not admit of a stereoscopic effect, or disturb the combination, 
then the stereoscopic effect ceases. 
The stereoscope is an instrument by means of which two somewhat similar pictures drawn 
in perspective may be superposed so that they appear single. Wheatstone (1838) obtained this 
result by means of two mirrors placed at an angle (fig. 702); Brewster (1843) by two prisms 
(fig. 703). The construction and mode of action are obvious from the illustrations. 
Some pairs of two such pictures may be combined, without a stereoscope, by directing the 
visual axis of each eye to the picture held opposite to it. 
Two completely identical pictures, i. e., in which all corresponding points have exactly the same 
relation to each other, as the same sides of two copies of a book, appear quite flat under the 
stereoscope; as soon, however, as in one of them one or more points alters its relation to the cor- 
responding points, this point either projects or recedes from the plane. 
Telestereoscope.—When objects placed at a great distance are looked at, e. g., the most 
distant part of a landscape, they appear to us to be flat, as in a picture, and do not stand out, 
because the slight differences of position of our eyes in the head are not to be compared with 
the great distance. In order to obtain a stereoscopic view of such objects, v. Helmholtz con- Sec. 402.] 
ESTIMATION OF SIZE. 
structed the telestereoscope (fig. 704), an apparatus which by means of two parallel mirrors, 
places, as it were, the point of view of both eyes wider apart. Of the mirrors, L and R each pro- 
jects its image of the landscape upon l and r, to which both eyes, 
O, o, are directed. According to the distance between L and R, 
the eyes, O, 0, as it were, are displaced to 01S ov The distant land- 
scape appears like a stereoscopic view. In order to see distant 
parts more clearly and nearer, a double telescope or opera-glass 
may be placed in front of the eyes. 
Take two corresponding stereoscopic pictures, with the surfaces 
black in one case and light in the other. Draw two truncated pyra- 
mids, like fig. 701, make one figure exactly like L, i. <?., with a 
white surface and black lines, and the other with white lines and 
Fig. 704. 
Fig. 705. 
Telestereoscope of v. Helmholtz, 
Wheatstone’s pseudoscope. 
a black surface, then under the stereoscope such objects glance. The cause of the glancing 
con'dition is that the glancing body at a certain distance reflects bright light into one eye and not 
into the other, because a ray reflected at an angle cannot enter both eyes simultaneously (Dove). 
Wheatstone’s Pseudoscope consists of two right-angled prisms (fig. 705, A and B) enclosed 
in a tube, through which we can look in a direction parallel with the surfaces of the hypothenuses. 
If a spherical surface be looked at with this instrument, the image formed in each eye is inverted 
laterally. The right eye sees the view usually obtained by the left eye and conversely; the 
shadow which the body in the light throws upon a light ground is reversed. Hence the ball 
appears hollow. 
Struggle of the Fields of Vision.—The stereoscope is also useful for the following pur- 
pose : In vision with both eyes, both eyes are almost never active simultaneously and to the 
same extent; both undergo variations, so that first the impression on the one retina and then that 
on the other is stronger. If two different surfaces be placed in a stereoscope, then, especially 
when they are luminous, these two alternate in the general field of vision, according as one or 
other eye is active Take two surfaces with lines ruled on them, so that when the 
surfaces are superposed the lines will cross each other, then either the one or the other system of 
lines is more prominent (Panum). The same is true with colored stereoscopic figures, so that 
there is a contest or struggle of the colored fields of vision. 
403. ESTIMATION OF SIZE AND DISTANCE.—Size.—We 
estimate the size of an object—apart from all other factors—from the size of 
the retinal image; thus the moon is estimated to be larger than the stars. 
If, while looking at a distant landscape,'a fly should suddenly pass across our field 
of vision, near to our eye, then the image of the fly, owing to the relatively great 
size of the retinal image, may give one the impression of an object as large as 
a bird. If, owing to defective accommodation, the image gives rise to diffusion 
circles, the size may appear to be even greater. But objects of very unequal 
size give equally large retinal images, especially if they are placed at such a 
distance that they form the same visual angle (fig. 658); so that in estimating 
the actual size of an object, as opposed to the apparent size determined 
by the visual angle, the estimate of distance is of the greatest importance. 
As to the distance of an object, we obtain some information from the 
feeling of accommodation, as a greater effort of the muscle of accommoda- 
tion is required for exact vision of a near object than for seeing a distant 1002 
ESTIMATION OF DISTANCES. 
[Sec. 403. 
one. But, as with two objects at unequal distances giving retinal images of the 
same size, we know from experience that that object is smaller which is near, 
then that object is estimated to be the smaller for which, during vision, we must 
accommodate more strongly. 
In this way we explain the following: A person beginning to use a microscope always ob- 
serves with his eyes accommodated for a near object, while one used to the microscope looks 
through it without accommodating. Hence beginners always estimate microscopic objects as 
too small, and on making a drawing of them it is too small. If we produce an after-image in 
one eye, it at once appears smaller on accommodating for a near object, and again becomes 
larger during negative accommodatiou. If we look with one eye at a small body placed as near 
as possible to the eye, then a body lying behind it, but seen only indirectly, appears smaller. 
Angle of Convergence of Visual Axes.—In estimating the size of an 
object, and taking into account our estimate of its distance, we also obtain much 
more important information from the degree of convergence of the visual 
axes. We refer the position of an object viewed with both eyes, to the 
point where both visual axes intersect. The angle formed by the two visual 
axes at this point is called the “ angle of convergence of the visual axes ” 
(“ Gesichtswinkel ”). The larger, therefore, the visual angle, the size of the 
retinal image remaining the same—we judge the object to be nearer. The 
nearer the object is, it may be the smaller, in order to form a “visual 
angle ” of the same size, such as a distant large object would give. Hence, 
we conclude, that with the same apparent size 
(equally large visual angle, or retinal images 
of the same size) we judge that object to be 
smallest which gives the greatest convergence 
of the visual axes during binocular vision. 
As to the muscular exertion necessary for 
this purpose, we obtain information from the 
muscular sense of the ocular muscles. 
Experiments and Proofs.—The chess-board 
phenomenon of H. Meyer—i. If we look at a uni- 
form chess-board-like pattern (tapestry or carpet), then, 
when the visual axes are directed directly forwards, the 
spaces on the pattern appear of a certain size. If, now, 
we look at a nearer object, we may cause the visual 
axes to cross, when the pattern apparently moves 
towards the plane of the fixed point, so that the crossed 
double images are superposed, and the pattern at once 
appears smaller. 
2. Rollett looks at an object through two thick prisms 
of glass placed at an angle. The plates are at one time 
so placed that the apex of the angle is directed towards 
the observer (fig. 706, II), at another in the reverse posi- 
tion (I). If both eyes,/-and i, are to see the object a, in I, then as the glass plates so displace 
the rays, a, c, and a, g, as to make them parallel with the direction of these rays, viz., e,f, and h, 
i, then the eyes must converge more than when they are turned directly towards a. Hence the 
object appears nearer and smaller, as at a. In II, the rays, bv k, and bx o, from the nearer object 
blt fall upon the glass plates. In order to see bv the eyes (n and q) must diverge more, so that 
b appears more distant and larger. 
3. In looking through Wheatstone's reflecting stereoscope (fig. 702), it is obvious that the more 
the two images approach the observer, the more must the observer converge his visual axes, be- 
cause the angles of incidence and reflection are greater. Hence the compound picture now 
appears to him to be smaller. If the centre of the image, R, recedes to Rlf then of course the 
angle, Sn, rp, is equal to Slt rRlt and the same on the left side. 
4. In using the telestereoscope, the two eyes are, as it were, separated from each other, then of 
course in looking at objects at a certain distance the convergence of the visual axes must be 
greater than in normal vision. Hence, objects in a landscape appear as in a small model. But 
Fig. 706. 
Rollett’s glass plate apparatus. Sec. 403.] 
THE EYELIDS. 
1003 
as we are accustomed to infer that such small objects are at a great distance, hence the objects 
themselves appear to recede in the distance. 
Estimation of Distance.—When the retinal images are of the same size, 
we estimate the distance to be greater the less the effort of accommodation, 
and conversely. In binocular vision, when the retinal images are of the same 
size, we infer that that object is most distant for which the optic axes are least 
converged, and conversely. Thus, the estimation of size and distance go hand 
in hand, in great part at least, and the correct estimation of the distance also 
gives us a correct estimate of the size of objects (Descartes). A further aid to 
the estimation of distance is the observation of the apparent displacement of ob- 
jects, on moving our head or body. In the latter, especially, lateral objects 
appear to change their position toward the background, the nearer they are to 
us. Hence, when travelling in a train, in which case the change of position of 
the objects occurs very rapidly, the objects themselves are regarded as nearer, 
and also smaller (Dove). Lastly, those objects appear to us to be nearest which 
are most distinct in the field of vision. 
Example.—A light in a dark landscape, and a dazzling crown of snow on a hill, appear to 
be near to us; looked at from the top of a high mountain, the silver glancing curved course of a 
river not unfrequently appears as if it were raised from the plane. 
False Estimates of Size and Direction.—i. A line divided by intermediate points ap- 
pears longer than one not so divided. Hence the heavens do not appear to us as a hollow sphere, 
but as curved like an ellipse ; and for the last reason the disc of the setting sun is estimated to be 
larger than the sun when it is in the zenith. 2.,If we move a circle slowly to and fro behind a 
slit, it appears as a horizontal ellipse; if we move it rapidly, it appears as a vertical ellipse. 3. 
If a very fine line be drawn obliquely across a vertical thick black line, then the direction of the 
fine line beyond the thick one appears to be different from its original direction. 
4. Zollner’s Lines.—Draw three parallel horizontal lines 1 centimetre apart, and through 
the upper and lower ones draw short oblique parallel lines in the direction from above and the 
left to below and the right; 
through the middle line draw 
similar oblique lines, but in 
the opposite direction, then the 
three horizontal lines no longer 
appear to be parallel. [Fig. 
707 shows a modification of 
this. The lines are actually 
parallel,although some of them 
appear to converge and others 
to diverge.] If we look in a 
dark room at a bright vertical 
line, and then bend the head 
towards the shoulder, the line 
appears to be bent in the oppo- 
site direction (Aubert). 
[5. The length of a line ap- 
pears to vary according to the 
angle and direction of certain 
other lines in relation to it 
(fig. 708). The length of 
the vertical line on the left is the same as that on the right, yet the latter is judged to be the 
longer.] 
404. PROTECTIVE ORGANS OF THE EYE.—I. The eyelids 
are represented in section in fig. 709. The tarsus is in reality not a cartilage, 
but merely a rigid plate of connective-tissue, in which the Meibomian glands 
are imbedded; acinous sebaceous glands moisten the edges of the eyelids with 
fatty matter. At the basal margin of the tarsus, especially of the' upper one, 
close to the reflection of the conjunctiva, open the acino-tubular- glands of 
Krause. The conjunctiva covers the anterior surface of the eyeball as far as the 
Fig. 707. 
Fig. 708. 
Zollner’s lines. 
To show a false estimate of size. 1004 
THE TEARS. 
[Sec. 404. 
margin of the cornea, over which the epithelium alone is continued. On the 
posterior surface of the eyelid, the 
conjunctiva is partly provided 
with papillae. It is covered by 
stratified squamous epithelium. 
Coiled glands occur in rumi- 
nants just outside the margin of 
the cornea, while outside this, 
towards the outer angle of the 
eye in the pig, there are simple 
glandular sacs. Waldeyer de- 
scribes modified sweat-glands in 
the tarsal margins in man. Small 
lymphatic sacs in the conjunctiva 
are called trachoma glands. 
Krause found end-bulbs in the 
conjunctiva bulbi (§ 424). The 
blood-vessels in the conjunctiva 
communicate with the juice- 
canals in the cornea and sclerotic 
(p. 934). The secretion moist- 
ening the conjunctiva, besides 
some mucus, consists of tears, 
which may be as abundant as 
that formed in the lachrymal 
glands. 
Closure of the eyelids is ef- 
fected by the orbicularis palpe- 
brarum (facial nerve, § 349), 
whereby the upper lid falls in 
virtue of its own weight. This 
muscle contracts—(1) volun- 
tarily ; (2) involuntarily (single 
contractions); ( 3 ) reflexly by 
stimulation of all the sensory 
fibres of the trigeminus distributed 
to the eyeball and its immediate 
neighborhood (§ 347), also by in- 
tense stimulation of the retina by 
light; (4) continued involuntary 
closure occurs during sleep. 
Opening of the eyelids is 
brought about by the passive 
descent of the lower one, and the 
active elevation of the upper eye- 
lid by the levator palpebrae supe- 
rioris (§ 345). The smooth mus- 
cular fibres of the eyelids also aid 
(p. 1005). In looking down- 
wards, the lower eyelid is pulled 
downwards by bands of connec- 
tive-tissue which run from the 
inferior rectus to the inferior tarsal cartilage {Schwalbe). 
II. The lachrymal apparatus consists of the lachrymal elands, which 
Fig. 709. 
Vertical section through the upper eyelid. A, cutis, 
1 epidermis; 2, corium; B and 3, subcutaneous 
connective-tissue; C and 7, orbicularis muscle; D, 
loose sub-muscular connective tissue; E, insertion 
of H. Muller’s muscle; F, tarsus; G, conjunctiva; 
/, inner, K, outer edge of the lid; 4, pigment 
cells; 5, sweat-glands; 6, hair follicles; 8 and 23, 
sections of nerves; 9, arteries; 10, veins; 11, cilia; 
12, modified sweat-glands; 13, circular muscle of 
Riolan; 14, Meibomian gland; 15, section of an 
acinus of the same; 16, posterior tarsal glands; 
18 and 19, tissue of the tarsus; 20, pretarsal or 
sub-muscular connective-tissue; 21 and 22, con- 
junctiva, with its epithelium; 24, fat; 25, loosely 
woven posterior end of the tarsus; 26, section of a 
palpebral artery. Sec. 404.] 
THE TEARS. 
1005 
in structure closely resemble the parotid, their acini being lined by low cylin- 
drical granular epithelium. Four to five larger, and eight to ten smaller ex- 
cretory ducts conduct the tears above the outer angle of the upper lid into 
the fornix conjunctiva. The tear ducts, beginning at the puncta lachrymalis, 
are composed of connective- and elastic-tissue, and are lined by stratified squa- 
mous epithelium. Striped muscle accompanies the duct, and by its contraction 
keeps the duct open. Toldt found no sphincter surrounding the puncta lachry- 
malia, while Gerlach found an incomplete circular musculature. The connec- 
tive-tissue covering of the tear sac and canal is united with the adjoining peri- 
osteum. The thin mucous membrane, which contains much adenoid tissue 
and lymph-cells, is lined by a single layer of ciliated cylindrical epithelium, 
which below passes into the stratified form. The opening of the duct is often 
provided with a valve-like fold (Hasner’s valve). 
The conduction of the tears occurs between the lids and the bulb by 
means of capillarity, the closure of the eyelids aiding the process. The Mei- 
bomian secretion prevents the overflow of the tears [just as greasing the edge of 
a glass vessel prevents the water in it from overflowing]. The tears are con- 
ducted from the puncta through the duct, chiefly by a siphon action. Hor- 
ner’s muscle [also known to Duvernoy, 1678] likewise aids, as every time the 
eyelids are closed it pulls upon the posterior wall of the sac, and thus dilates 
the latter, so that it aspirates tears into it {Henke). 
E. H. Weber and Hasner ascribe the aspiration of the tears to the diminution of the amount 
of air in the nasal cavities during inspiration. Arlt asserts that the tear sac is compressed by the 
contraction of the orbicularis muscle, so that the tears must be forced towards the nose. Lastly, 
Stellwag supposes that when the eyelids are closed the tears are simply pressed into the puncta, 
while Gad denies that there is any kind of pumping mechanism in the nasal canal. Landois 
points out that the tear ducts are surrounded by a plexus of veins, which according to their state 
of distention may influence the size of these tubes. 
The secretion of tears takes place only by direct stimulation of the 
lachrymal nerve (§ 347, I, 2), subcutaneous malar (§ 347, II, 2), and cervical 
sympathetic (§ 356, A, 6), which have been called secretory nerves. Secre- 
tion may also be excited rejlexly (§ 347, I, 2) by stimulation of the nasal 
mucous membrane only on the same side {Herzenstein). The ordinary secretion 
in the waking condition is really a reflex secretion produced by the stimulation 
of the anterior surface of the bulb by the air, or by the evaporation of tears. 
A very bright light also causes a reflex secretion of tears, the optic being the 
afferent nerve. The centre in the rabbit does not extend forward beyond the 
origin of the fifth nerve, but it extends downwards to the fifth vertebra {Eck- 
hard). During sleep all these factors are absent, and there is no secretion. 
Histological changes.—Reichel found that in the active gland (after in- 
jection of pilocarpin), the secretory cells became granular, turbid, and smaller, 
while the outlines of the cells became less distinct, and the nuclei spheroidal. 
In the resting gland, the cells are bright and slightly granular with irregular 
nuclei. Intense stimulation by light acting on the optic nerve causes a reflex 
secretion of tears. The flow of tears accompanying certain violent emotions, 
and even hearty laughing, is still unexplained. During coughing and vomiting 
the secretion of tears is increased partly reflexly, and partly by the outflow 
being prevented by the expiratory pressure. 
Function of Tears.—The tears moisten the bulb, protect it from drying, 
and float away small particles, being aided in this by the closure of the eyelids. 
Atropin diminishes the tears (Mogaard). 
Composition of Tears.—The tears are alkaline, saline to taste, and repre- 
sent a “ serous ” secretion. Water 98.1 to 99; 1.46 organic substances (0.1 
albumin and mucin, 0.1 epithelium) ; 0.4 to 0.8 salts (especially NaCl). 1006 
COMPARISON OF VISUAL ORGANS. 
[Sec. 405. 
[Action of Drugs.—Essential volatile oils and eserin increase the secretion of tears, atropin 
arrests it, while eserin antagonizes the effect of atropin and causes an increased secretion.] 
405. COMPARATIVE— HISTORICAL.—Comparative.—The simplest form of 
visual apparatus is represented by aggregations of pigment-cells in the outer coverings of the 
body, which are in connection with the termination of afferent nerves. The pigment absorbs 
the rays of light, and in virtue of the light-ether discharges kinetic energy, which excites the 
terminations of the nervous apparatus. Collections of pigment-cells, with nerve-fibres attached, 
and provided with a clear refractive body, occur on the margin of the bell of the higher medusae, 
while the lower forms have only aggregations of pigment on the bases of their tentacles.. Also 
in many lower worms there are pigment spots near the brain. In others, the pigment lies as a 
covering round the terminations of the nerves, which occur as “crystalline rods” or “crystalline 
spheres.” In parasitic worms the visual apparatus is absent. In star-fishes, the eyes are at the 
tips of the arms, and consist of a spherical crystal organ surrounded with pigment, with a nerve 
going to it. In all other echinodermata there are only accumulations of pigment. Amongst the 
annulosa there are several grades of visual apparatus—(1) Without a cornea, there may be 
only one crystal sphere (nervous end-organ) near the brain, as in the young of the crab ; or there 
may be several crystal spheres forming a compound eye, as in the lower crabs. (2) With a 
cornea, consisting of a lenticular body formed from the chitin of the outer integument, the eye 
itself may be simple, merely consisting of one crystal rod, or it may be compound. The com- 
pound eye consists of only one large lenticular cornea, common to all the crystal rods, as in the 
spiders; or each crystal rod has a special lenticular cornea for itself. The numerous rods sur- 
rounded by pigment are closely packed together, and are arranged upon a curved surface, so 
that their free ends also form a part of a sphere. The chitinous investment of the head is 
facetted and forms a small corneal lens on the free end of each rod. According to one view, 
each facette, with the lens and the crystal sphere, is a special eye, and just as man has two eyes 
so insects have several hundred. Each eye sees the picture of the outer world in toto. This 
view is supported by the following experiment of van Leeuwenhoek: If the cornea be sliced 
off, each facette thereof gives a special image of an object. If a cross be made on the mirror of 
a microscope, while a piece of the facetted cornea is placed as an object upon the stage, then we 
see an image of the cross in each facette of the cornea. Thus for each rod (crystal sphere) there 
would be a special image. Each corneal facette, however, forms only a part of the image of the 
outer world, so that we must regard the image as composed like a mosaic. Amongst mollusca, 
the fixed brachiopoda have two pigment spots near the brain, but only in their larval condition J, 
while the mussel has, under similar conditions, pigment spots with a refractive body. The adult 
mussel, however, has pigment spots (ocelli) only in the margin of 
the mantel, but some molluscs have stalked and highly developed 
eyes. Some of the lower snails have no eyes, some have pigment 
spots on the head, while the garden snail has stalked eyes pro- 
vided with a cornea, an optic nerve with retina and pigment,' and 
even a lens and vitreous body. Amongst cephalopoda, the nautilus 
has no cornea or lens, so that the sea-water flows freely into the orbits. 
Others have a lens and no cornea, while some have an opening in 
the cornea (Loligo, Sepia, Octopus). All the other parts of the eye 
are well developed. Amongst vertebrata, Amphioxus has no eyes. 
They exist in a degenerated condition in Proteus and the mammal 
Spalax. In many fishes, amphibians, and reptiles, the eye is cov- 
ered by a piece of transparent skin. [Pineal or Epiphysial Eye.— 
Some lizards, e.g., Hatteria, have a rudimentary median eye in the 
median line of the head, and lodged in the parietal foramen. It is 
developed from the pineal body, and its lens is formed from the optic cup, so that light falls 
upon the retina without penetrating the fibres of the optic nerve. Thus, it is an invertebrate 
type of eye, where the retina and lens are developed from epidermal structures, while in the 
vertebrate eye the retina is developed from the cerebrum (fig. 710).] Some hag-fishes, the 
crocodile, and birds have eyelids, and a nictitating membrane at the inner angle of the eye. 
Connected with it is the Harderian gland. In mammals the nictitating membrane is repre- 
sented only by the plica semilunaris. There is no lachrymal apparatus in fishes. The tears of 
snakes remain under the watch-glass-like cutis with which the eyes are covered. The sclerotic 
often contains cartilage which may ossify. A vascular organ, the processus falciformis, 
passes from the middle of the choroid into the interior of the vitreous body in osseous fishes, its 
anterior extremity being termed the campanula Halleri. Similarly, there is the pecten in birds, 
but it is provided with muscular fibres. In birds the cornea is surrounded by a bony ring. The 
whale has an enormously thick sclerotic. In aquatic animals the lens is nearly spherical. 
The muscles of the iris and choroid are transversely striped in birds and reptiles. The retinal 
rods in all vertebrates are directed from before backwards, while the analogous elements (crystal 
rods and spheres) in invertebrata are directed from behind forward. 
Fig. 710. 
Section of the pineal eye 
of a lizard. Sec. 405.] 
HISTORICAL REVIEW. 
Historical.—The Hippocratic School were acquainted with the optic nerve and lens. Aris- 
totle (384 B.c.) mentions that section of the optic nerve causes blindness—he was acquainted 
with after-images, short and long sight. Herophilus (307 B.c.) discovered the retina, and the 
ciliary processes received their name in his school. Galen (131-203 A.D.) described the six 
muscles of the eyeball, the puncta lachrymalia, and tear duct. Aerengar (1521) was aware of 
the fatty matter at the edge of the eyelids. Stephanus (1545) and Casseri (1609) described the 
Meibomian glands, which were afterwards redescribed by Meibom (1666). Fallopius described 
the vitreous membrane and the ciliary ligament. Plater (1583) mentions that the posterior 
surface of the lens is more curved. Aldrovandi observed the remainder of the pupillary mem- 
brane (1599). Observations were made at the time of Vesalius (1540) on the refractive action 
of the lens. Leonardo da Vinci compared the eye to a camera obscura. Maurolykos compared 
the action of the lens to that of a lens of glass, but it was Kepler (1611) who first showed the 
true refractive index of the lens and the formation of the retinal image, but he thought that 
during accommodation the retina moved forward and backward. The Jesuit, Scheiner (f 1650), 
mentions, however, that the lens becomes more convex by the ciliary processes, and he assumed 
the existence of muscular fibres in the uvea. He referred long and short sight to the curvature 
of the lens, and he first showed the retinal image in an excised eye. With regard to the use of 
spectacles there is a reference in Pliny. It is said that at the beginning of the 14th century 
the Florentine, Sal vino d’Armato degli Armati di Fir (f 1317), and the monk, Alessandro de 
Spina (f 1313), invented spectacles. Kepler (1611) and Descartes (1637) described their action. 
Mayo (f 1852) described the 3d nerve as the constrictor nerve of the pupil. Zinn contributed 
considerably to our knowledge of the structure of the eye. Ruysch described muscular fibres 
in the iris, and Monro described the sphincter of the pupil (1794). Jacob described the 
bacillary layer of the retina—Soemmering (1791) the yellow spot. Brewster and Chossat 
(1819) tested the refractive indices of the optical media. Purkinje (1819) studied subjective 
vision. . , Hearing. 
406. THE ORGAN OF HEARING.—Stimulation of the Audi- 
tory Nerve.—The normal manner in which the auditory nerve is excited is 
by means of sonorous vibrations, which set in motion the end-organs of 
the acoustic nerve, lying in the endolymph of the labyrinth of the inner ear, 
on the membranous 
expansions of the 
cochlek and in the 
semicircular canals. 
Hence, the sonorous 
vibrations are first 
transmitted to the 
fluid in the labyrinth, 
and this, in turn, is 
thrown into waves, 
which set the end 
organs into vibration. 
Thus, the excitement 
of the auditory nerves 
is brought about by 
the mechanical stimu- 
lation of the end-or- 
gans of the auditory 
nerve due to the wave- 
motion of the lymph of 
the labyrinth. 
The fluid or lymph 
of the labyrinth is 
surrounded by the ex- 
ceedingly hard osse- 
ous mass of the tem- 
poral bone (fig. 711). 
Only at one small 
roundish and slightly 
triangular area, the 
fenestra rotunda (r), the fluid is bounded by a delicate yielding membrane, 
which is in contact with the air in the middle ear or tympanum (P). Not far 
from the fenestra rotunda is the fenestra ovalis (o), in which the base of the 
stapes (j) is fixed by means of a yielding membranous ring. The outer surface 
of this also is in contact with the air in the middle ear. As the perilymph of 
the inner ear is in contact at these two places with a yielding boundary, it is 
clear that the lymph itself may exhibit oscillatory movements, as it must follow 
the movements of the yielding boundaries. 
The sonorous vibrations may set the perilymph in vibration in three different 
ways:— 
1. Conduction through the Bones of the Head.—This occurs especi- 
Fig. 711. 
Scheme of the organ of hearing. AG, external auditory meatus; 
T, tympanic membrane; K, malleus with its head [A), short 
process (&f), and handle (ni); a, incus, its short process (x), and 
its long process united to the stapes (5) by means of the Sylvian 
ossicle (z); P, middle ear; o, fenestra ovalis; r, fenestra rotunda; 
x, beginning of the lamina spiralis of the cochlea; pt, scala 
tympani, and vt, scala vestibuli; V, vestibule; S, succule; U, 
utricle; H, semi-circular canals; TE, Eustachian tube. The 
long arrow indicates the line of traction of the tensor tympani; 
the short curved one, that of the stapedius. Sec. 406.] 
CONDUCTION OF SOUND TO THE EAR. 
1009 
ally when the vibrating solid body is applied directly to some part of the head, 
e. g., a tuning-fork placed on the head, the sound being propagated most in- 
tensely in the direction of the prolongation of the handle of the instrument— 
also when the sound is conducted to the head by means of fluid, as when the 
head is ducked under water. Vibrations of the air, however, are practically 
not transferred directly to the bones of the head, as is shown by the fact that 
we are deaf when the ears are stopped. 
The soft parts of the head, which lie immediately upon bone, conduct sound best, and of the 
projecting part, the best conductor is the cartilaginous portion of the external ear. But even 
under the most favorable circumstances, conduction through the bones of the head is far less 
effective than the conduction of the sound-waves through the external auditory meatus. If a 
tuning-fork be made to vibrate between the teeih until we no longer hear it, its tone may still 
be heard on bringing it near the ear (Rinne). The conduction thiough the bones is favored when 
the oscillations are not transferred from the bones to the tympanic membrane, and are thus trans- 
ferred to the air, in the outer ear. Hence, we hear the sound of a tuning-fork applied to the 
head better when the ears are stopped, as this prevents the propagation of the sound-waves 
through the air in the outer ear. If, in a deaf person, the conduction is still normal through the 
cranial bones, then the cause of the deafness is not in the, nervous part of the ear, but in the 
external sound-conducting part of the apparatus. 
2. Normal hearing takes place through the external auditory meatus. 
The enormous vibrations of the air first set the tympanic membrane in vibra- 
tion (fig. 711, T); this moves the malleus (h), whose long process is inserted 
into it; the malleus moves the incus (a), and this the stapes (s), which trans- 
fers the movements of its plate to the perilymph of the labyrinth. 
3. Direct Conduction to the Fenestra.—In man, in consequence of occasional disease of 
the middle ear, whereby the tympanic membrane and auditory ossicles may be destroyed, the 
auditory apparatus may be excited, although only in a very feeble manner, by the vibrations of 
the air being directly transferred to the membrane of the fenestra rotunda (r), and the parts 
closing the fenestra ovalis (0). The membrane of the fenestra rotunda may vibrate alone, even 
when the oval window is closed with a rigid body ( Weber-Liet). 
407. PHYSICAL INTRODUCTION.—Sound is produced by the 
vibration of elastic bodies capable of vibration. Alternate condensation 
and rarefaction of the surrounding air are thus produced ; or, in other words, 
sound-waves in which the particles vibrate longitudinally or in the direction 
of the propagation of the sound are excited. Around the point of origin of 
the sound, these condensations and rarefactions occur in equal concentric 
circles, which conduct the sound vibrations to our outer ear. The vibrations 
of the sounding body are so-called “stationary vibrations,” i. e., all the par- 
ticles of the vibrating body are always in the same phase of movement, in that 
they pass into movement simultaneously, they reach the maximum of movement 
simultaneously, e. g., in the particles of a sounding vibrating metal rod. 
Sound is produced by the stationary vibrations of elastic bodies; it is pro- 
pagated by progressive wave-motion of elastic media, generally the air. The 
wave-length of a tone, i. e., the distance of one maximum of condensation to 
the next one in the air, is proportional to the duration of the vibration of the 
body whose vibrations produce the sound-waves. 
If y is the wave-length of a tone, t in seconds the duration of a vibration of the body pro- 
ducing the wave, then y = n t, where n — 340.88 metres, which is the rate per second of pro- 
pagation of sound-waves in the air. The rapidity of the transmission of sound-waves in water = 
1435 metres per second, i. e., nearly four times as rapid as in air; while, in solids capable of 
vibration, it is propagated from seven to eighteen times faster than in the air. Sound-waves are 
conducted best through the same medium; when they have to pass through several media they 
are always weakened. 
Reflection of the sound-waves occurs when they impinge upon a solid obstacle, in which 
case the angle of reflection is always equal to the angle of incidence. 
Wave Movements.—We distinguish—I. Progressive wave movements which occur in 
two forms—(1) As longitudinal waves, in which the individual particles of the vibrating body 1010 
EXTERNAL EAR AND MEATUS. 
[Sec. 407. 
vibrate around their centre of gravity in the direction of the propagation of the wave; examples 
are the waves in water and air. This movement causes an accumulation of the particles at 
certain places, e.g., on the crests of the waves in water-waves, while at other places they are 
diminished. This kind of wave is called a wave of condensation and rarefaction. (2) If, 
however, each particle in the progressive wave moves vertically up and down, i. e., transversely 
to the direction of the propagation of the wave, then we have the simple transverse waves, or 
progressive waves, in which there is no condensation or rarefaction in the direction of propaga- 
tion, as each particle is merely displaced laterally. An example of this is the progressive waves 
in a rope. 
II. Stationary Flexion Waves.—When all the particles of an elastic vibrating body so 
oscillate that all of them are always in the same phase of movement as the limbs of a vibrating 
tuning-fork or a plucked string, then this kind of movement is described as stationary flexion 
waves. As bodies whose expansion in the direction of oscillation is very slight, vibrate to 
and fro in the stationary flexion wave, so we see that the small parts of the auditory 
apparatus (tympanic membrane, ossicles, lymph of the labyrinth) oscillate in stationary flexion 
waves. 
408. EAR MUSCLES—EXTERNAL AUDITORY MEATUS.— 
When the external ear is absent, little or no impairment of the hearing is 
observed ; hence, the physiological functions of these organs are but slight. 
Boerhaave thought that the elevations and 
depressions of the outer ear might be con- 
nected with the reflection of the sound- 
waves. Numerous sound waves, however, 
must be again reflected outwards ; and those 
waves which reach the deep part of the 
concha are said to be reflected towards the 
tragus, to be reflected by it into the external 
auditory meatus. According to Schneider, 
when the depressions in the ear are filled up 
with wax, hearing is impaired ; other ob- 
servers, however, have found the hearing to 
be unaffected. Mach points out that the di- 
mensions of the external ear are proportion- 
ally too small to act as reflecting organs for 
the wave-lengths of noises. 
Muscles of the External Ear.—(1) The whole 
ear is moved by the retrahentes, attrahens, and atto- 
lens. (2) The form of the ear may be altered by the 
tragicus, antitragicus, helicis major and minor inter- 
nally ; and by the transversus and obliquus auriculae 
externally. Persons who can move their ears do not 
find that the hearing is influenced during the move- 
ment. The Mm. helicis major and minor are re- 
garded as elevators of the helix, the transversus and 
obliquus auriculae as dilators of the concha; the tragicus and antitragicus as constrictors of the 
meatus. In animals, the external ear and the action of its muscles have a marked effect upon 
hearing. The muscles point the ear in the direction of the sound, while other muscles contract 
or dilate the space within the external ear. In many diving animals, the meatus can be closed 
by a kind of valve. The external auricle of man is a typically formed organ, but its function 
has been largely lost. 
The external meatus is 3 to 3.25 cm. long to 1% inch], 8 to 9 mm. 
high, and 6 to 8 mm. broad at its outer opening (fig. 712). It is the con- 
ductor of the sound-waves to the tympanic membrane, so that almost all the 
sound-waves first impinge upon its wall, and are then reflected towards the 
tympanic membrane. To see well down into the meatus, we must pull the 
auricle upwards and backwards. Occlusion of the meatus, especially by a plug 
of inspissated wax (§ 287) of course interferes with the hearing, [and when it 
presses on the membrana tympani may give rise to severe vertigo]. 
Fig. 712. 
The auricle, external auditory meatus, 
and the tympanic cavity. M, osseous 
spaces in the temporal bone; Pc, car- 
tilaginous part of the meatus; L, 
membranous union between both; F, 
auricular surface for the condyle of the 
lower jaw. Sec. 409.] 
TYMPANIC MEMBRANE. 
409. TYMPANIC MEMBRANE.—The tympanic membrane, 
which is tolerably laxly fixed in a special osseous cleft, with a thickened mar- 
gin, is an elastic, unyielding, and almost non-extensible membrane of about 
o. i mm. in thickness, and with a superficial area of 50 square millimetres 
(fig- 7i5)- It is ellip- 
tical in form, its greater 
diameter being 9.5 to 
10 mm. and its lesser 8 
mm., and it is fixed in 
the floor of the exter- 
nal meatus obliquely, at 
an angle of 40°, being 
directed from above and 
outwards, downwards 
and inwards. Both 
tympanic membranes 
converge anteriorly, so 
that if both were pro- 
longed they would meet 
to form an angle of 
130° to 135°. The 
oblique position en- 
ables a larger surface to 
be presented than would 
be obtained if it were 
stretched vertically, so 
that more sound-waves 
can fall vertically upon 
it. The membrane is 
not stretched flat, but a 
little under its centre 
(umbilicus) it is drawn 
slightly inwards by the 
handle of the malleus, 
which is attached to it ; while the short process of the malleus slightly bulges 
out the membrane near its upper margin (figs. 711, 718). 
Structure.—The tympanic membrane consists of three layers: (1) The membrana 
propria is a fibrous membrane with radial fibres on its outer surface, and circularly arranged 
fibres on its inner aspect. (2) The surface directed towards the meatus is covered with a thin 
and semi-transparent part of the cutis. (3) The side towards the tympanum is covered with a 
delicate mucous membrane, with simple squamous epithelium. Numerous nerves and 
lymph-vessels, as well as inner and outer blood-vessels occur in the membrane. 
[The middle layer, or substantia propria, is fixed to a ring of bone, which 
is deficient above. This deficiency, however, is filled up by a layer composed 
of the mucous and cutaneous layers called the membrana flaccida, or Shrap- 
nell’s membrane.l 
[Examination of the Tympanic Membrane.—When examining the outer ear and mem- 
brana tympani, pull the auricle upwards and backwards. The membrana tympani is examined 
by means of an ear speculum (fig. 716). The speculum is placed in the ear, and light is re- 
flected into it by means of a concave mirror, perforated in the centre, and having a focal distance 
of four or five inches. It is convenient to have the mirror fixed to a band placed round the 
head as in the case of the laryngoscopic reflector (fig. 437). It is important to remember that 
the membrane is placed obliquely, so that the posterior and upper parts are nearer the surface. 
The membrane in health is grayish in color and transparent, so that the handle of the malleus 
is seen running from above downwards and backwards, while at the anterior and inferior part 
there is a cone of light with its apex directed inwards.] 
Fig- 713- 
Fig. 713.—Tympanic membrane with the auditory ossicles (left) seen 
from within. Ci, incus; Cm, malleus; Ch, chorda tympani; 
Ty pouch-like depression. Fig. 714.—Tympanic membrane and 
the auditory ossicles (left) seen from within, i. e., from the tym- 
panic cavity. M, manubrium or handle of the malleus; T, in- 
sertion of the tensor tympani; h, head; IF, long process of the 
malleus; a, incus, with the short (K) and. the long (/) process; 
S, plate of the stapes; Ax, Ax, is the common axis of rotation 
of the auditory ossicles; S, the pinion-wheel arrangement be- 
tween the malleus and incus. Fig. 7x5.—Tympanic membrane 
of a new-born child seen from without, with the handle of the 
malleus visible on it. At, tympanic ring with its anterior (7') and 
posterior (h) ends. 
Fig. 7*5- 
Fig. 714. MEMBRANA TYMPANI. 
[Sec. 409. 
[Siegle’s Ear Speculum.—“ For further determining the presence of adhesions of the 
membrane and the mobility of the malleus, the pneumatic speculum, first introduced by Siegle, is 
very valuable. It consists (vide fig. 716) of an ordinary vulcanite speculum (a), which screws 
into a vulcanite box (c) covered with a glass lens (h), which is also screwed on. By placing a 
little piece of india-rubber tubing on the tubular part, it fits air-tight into the meatus. The box 
has an india-rubber tube and a mouth-piece (d) connected with it, which is placed in the mouth 
of the surgeon ; suction is applied to the end of the tube, and the air drawn from the meatus, 
thus acting on the membrane, with a good light thrown on it through the speculum ; the former 
is seen magnified, and any adhesions and inequalities which may exist are disclosed.”—Mac- 
naught on Jones.'] 
Function of the Tympanic Membrane.—The tympanic membrane 
catches up the sound-waves which penetrate into the external meatus, and is 
set into vibration by 
them, the vibrations 
corresponding in 
number and ampli- 
tude to the vibrating 
movements of the air. 
Politzer connected 
the auditory ossicles 
fixed to the tym- 
panic membrane of 
a duck with a record- 
ing apparatus, and 
could thus register 
the vibrations pro- 
duced by sounding 
any particular tone. 
Owing to its small 
dimensions, the tym- 
panic membrane can 
vibrate in toto, to and 
fro in the direction of the sound-waves corresponding to the condensations and 
rarefactions of the vibrating air, and therefore executes tratisverse vibrations, 
for which it is specially adapted, owing to the relatively slight resistance. 
Fundamental Note.—Stretched strings and membranes are generally only 
thrown into actual and considerable sympathetic vibration when they are affec- 
ted by tones which correspond with their own fundamental tone, or whose 
number of vibrations is some multiple of the number of vibrations of the same, 
as the octave. When other tones act on them, they exhibit only inconsider- 
able sympathetic vibration. If a membrane be stretched over a funnel or 
cylinder, and if a nodule of sealing wax attached to a silk thread be made just 
to touch the centre of the membrane, then the sealing wax remains nearly at 
rest when tones or sounds are made in the neighborhood; as soon, however, as 
the fundamental or proper tone of this arrangement is sounded, the nodule is 
propelled by the strong vibrations of the membrane. 
If we apply this to the tympanic membrane, then it also should exhibit very 
great vibrations when its own fundamental note is sounded, but only slight 
vibrations when other tones are produced. This, however, would produce 
great inequality in the audible sounds. There is an arrangement of the mem- 
brane whereby this is prevented. (1) Great resistance is offered to the vibra- 
tions of the tympanic membrane, owing to its union with the auditory ossicles. 
These act as a damping apparatus, which provides, as in damped mem- 
branes generally, that the tympanic membrane shall not exhibit excessive sym- 
pathetic vibrations for its own fundamental note. But the damping also makes 
Various forms of ear specula. A, ordinary form ; B, Siegle’s 
ear pneumatic speculum. 
Fig. 716. Sec. 409.] 
AUDITORY OSSICLES. 
the sympathetic vibrations less for all the other tones. In this way, all vibra- 
tions of the tympanic membrane are modified ; especially, however, is the ex- 
cessive vibration diminished during the sounding of its fundamental tone. 
The membrane is at the same time rendered more capable of responding to the 
vibrations of different wave-lengths. The damping also prevents after-vibra- 
tions. (2) Corresponding to the small mass of the tympanic membrane, its 
sympathetic vibrations must also be small. Nevertheless, these slight elonga- 
tions are quite sufficient to convey the sonorous movements to the most delicate 
end-organs of the auditory nerve; in fact, there are arrangements in the tym- 
panum which still further diminish the vibrations of the tym- 
panic membrane. 
As v. Helmholtz has shown, the strong sympathetic vibrations of the tym- 
panic membrane are not completely set aside by this damping arrangement. 
The painful sensations produced by some tones are, perhaps, due to the sympa- 
thetic vibration of the membrana tympani. According to Kessel, certain parts 
of the membrane vibrate to certain tones; the shortest radial fibres at the 
upper part of the anterior and upper segment vibrate with the highest tones, 
the longest fibres at the posterior segment with the deepest tones. At the upper 
part of the posterior segment noises are transmitted. 
According to Pick, the tympanic membrane, besides possessing the property 
of taking up all vibrations with nearly equal intensity, has also the properties 
of a resonance apparatus; i. e., it causes a summation of the energy of suc- 
cessive vibrations. This is due to the funnel shape of the membrane, and to 
the radial, rigid insertion of the handle of the malleus. 
Pathological.—Thickenings or inequalities of the tympanic membrane 
interfere with the acuteness of hearing, owing to the diminished capacity for 
vibration thereby produced. Holes in and loss of its substance act similarly. 
In extensive destruction, an artificial tympanum is placed in the external 
meatus, and its vibrations, to a certain extent, replace those of the lost membrane (Toynbee). 
[Fig. 717 shows an artificial tympanic membrane.] 
410. AUDITORY OSSICLES AND THEIR MUSCLES.—The 
auditory ossicles have a double function.—(1) By means of the “chain” 
which they form, they transfer the vibrations of the tympanic membrane to the 
perilymph of the labyrinth. (2) They also afford points of attachment for the 
muscles of the middle ear, which can alter the tension of the membrana tym- 
pani, and the pressure on the lymph of the labyrinth. 
Mechanism.—The form and position of the ossicles are given in figures 718 
and 719. They form a jointed chain which connects the tympanic membrane, 
M, by means of the malleus, h, incus, a, and stapes, S, with the perilymph of 
the labyrinth. The mode of movement of the ossicles is of special im- 
portance. The handle of the malleus is firmly united to the fibres of the tym- 
panic membrane (fig. 719, n). Besides this, the malleus is fixed by ligaments 
which prescribe the direction of its movements. Two ligaments—the lig. 
mallei anticum (passing from the processus Folianus) and the posticum (from 
a small crest on the neck)—together form a common axial band (v. Helmholtz), 
which acts in the direction from behind forwards, i. e., parallel to the surface 
of the tympanic membrane. The neck of the malleus lies between the inser- 
tions of both ligaments. The united ligament determines the “ axis of rota- 
tion ” of the movement of the malleus. 
When the handle of the malleus is drawn inwards, of course its head moves 
in the opposite direction, or outwards. The incus, a, is only partially fixed by 
a ligament, which attaches its short process to the wall of the tympanic cavity, 
in front of the entrance to the mastoid cells, k. The not very tense articula- 
tion joining it to the head of the malleus, h, which lies with its saddle-shaped 
articular surface in the hollow of the incus, is important. The lower margin 
of the incus (fig. 719, S) acts like a tooth of a cog-wheel. Thus, when the 
handle of the malleus moves inwards to a tympanic cavity, the incus, and its 
Toynbee’s arti- 
ficial membrana 
tympani. 
Fig. 717. 1014 
AUDITORY OSSICLES. 
[Sec. 410. 
long process, b, which is parallel to the handle of the malleus, also pass inwards. 
The incus forms almost a right angle with the stapes, S, through the interven- 
tion of the Sylvian ossicle, s. If, however, as by condensation of the air in the 
tympanum, the membrana tympani and the handle of the malleus move out- 
wards, the long process of the incus does not make a similar movement, as the 
malleus moves away from this margin of the incus. Hence the stapes is not 
liable to be torn from its socket. The malleus and incus form an angular 
lever, which moves round a common axis (fig. 718 and fig. 719, Ax, Ax). In 
the inward movement, the malleus follows the incus, as if both formed one 
piece. The common axis (fig. 714) is not, however, the axial ligament of the 
malleus, but it is formed anteriorly by the processus Folianus, IF, directed 
forwards, and posteriorly by the short process of the incus directed backwards. 
The rotation of both ossicles around this axis occurs in a plane vertical to the 
plane of the membrana tym- 
pani. During the rotation, of 
course the parts above this axis 
(head of the malleus and upper 
part of the body of the incus) 
take a direction opposite to the 
parts lying below it (the handle 
of the malleus and the long 
process of the incus), as is indi- 
Fig. 718. 
Fig. 719. 
Fig. 718.—The auditory ossicles (right). C.m, head ; C, neck ; Pbr, short process; Prl, long 
process; M, handle of the malleus; Ci, body; G, articular surface ; h, short, and v, long 
process of the incus; O.S, so-called lenticular ossicle; C.s, head; a, anterior, and p, pos- 
terior limb, /*, plate of the stapes. Fig. 719.—Tympanum and auditory ossicles (left) mag- 
nified. A.G., external meatus; M, membrana tympani, which is attached to the handle of 
the malleus, n, and near it the short process,// h, head of the malleus; a, incus; k, its 
short process with its ligament; /, long process; s, Sylvian ossicle; S, stapes; Ax, Ax, 
is the axis of rotation of the ossicles; it is shown in perspective, and must be imagined to 
penetrate the plane of the paper; /, line of traction of the tensor tympani. The other 
arrows indicate the movement of the ossicles when the tensor contracts. 
cated in fig. 719 by the direction of the arrows. The movement of the handle 
of the malleus must follow that of the membrana tympani, and vice versa, 
while the movement of the stapes is connected with the movement of the long 
process of the incus. As the long process of the incus is only two-thirds of the 
length of the handle of the malleus (figs. 711, 715, 719), of course the excur- 
sion of the tip of the former, and with it of the stapes, must be correspondingly 
less than the movement of the tip of the handle of the malleus, while, on the 
other hand, the force of the movement of the tip of the handle of the malleus, 
corresponding to the diminution of the excursion, will be increased. 
Mode of Vibration.—Thus, the movement of the membrana tympani Sec. 410.] 
MUSCLES OF THE TYMPANUM. 
inwards causes a less extensive but a more powerful movement of the foot of the 
stapes against the perilymph of the labyrinth. V. Helmholtz and Politzer cal- 
culated the extent of the movement to be 0.07 mm. The mode in which the 
vibrations of the membrana tvmpani are conveyed to the lymph of the laby- 
rinth, through the chain of ossicles, is quite analogous to the mechanism of 
these parts already described. Long delicate glass threads were fixed to these 
ossicles, and their movements were thus graphically recorded on a smoked sur- 
face (.Politzer, Hensen). Or, strongly refractive particles were so fixed to the 
ossicles that the beam of light reflected from them could be examined by means 
of a microscope {Buck, v. Helmholtz). All the experiments showed that the 
transference of the sound-waves is accomplished by means of the mechanism of 
the angular lever, composed of the auditory ossicles already described. As 
the vibrations of the membrana tympani are conveyed to the handle of the 
malleus, they are weakened to about one-fourth of their original strength 
{Politzer). [The membrana tympani is many (30) times larger than the fenestra 
ovalis, and the relation in size might be represented by a funnel. The arm of 
the malleal end of the lever where the power acts is mm. long, while the 
short or stapedial arm is mm., so that the latter moves less than the former, 
but what is lost in extent is gained in force.] 
[Methods.—Politzer attached small, very light levers to each of the ossicles, and inscribed 
their movements on a revolving cylinder. An organ-pipe was sounded, and when the levers 
were of the same length, the malleus made the greatest excursion and the stapes the least. 
Buck attached starch grains to the ossicles, illuminated them, and observed the movements of 
the refractive starch granules by means of a microscope provided with a micrometer.] 
The ossicles move en masse, and not in the way of propagating molecular 
vibrations. As the excursions of the ossicles during sonorous vibrations are, 
however, only nominal, there is practically no change in the position of the 
joints with each vibration. The latter will only occur when extensive move- 
ments take place by means of the muscles. 
The muscles of the auditory ossicles alter the position and tension of the 
membrana tympani, as well as the pressure of the lymph of the labyrinth. The 
tensor tympani,which lies in an osseous groove 
above the Eustachian tube, has its tendon de- 
flected round an osseous projection [processus 
cochleariformis], which lies external to it, almost 
at right angles to the groove above it, and is 
inserted immediately above the axis of rotation 
of the malleus (fig. 714, M). When the muscle 
contracts in the direction of the arrow, t, then 
the handle of the malleus {n) pulls the membrana 
tympani (M) inwards and tightens it (fig. 719). 
This also causes a movement of the incus and 
stapes (S) which must be pressed more deeply 
into the fenestra ovalis as already described. 
When the muscle relaxes, then, owing to the elas- 
ticity of the rotated axial ligament and the tense 
membrana tympani itself, the position of equili- 
brium is again restored. The motor nerve of this muscle arises from the 
trigeminus, and passes through the otic ganglion (§ 347, III, 6). C. Ludwig 
and Politzer observed that stimulation of the fifth nerve within the cranium 
[dog] caused the above-mentioned movement. 
U se of the Tension.—The tension of the membrana tympani caused by 
the tensor tympani has a double function {Joh. Miiller)—1. The tense mem- 
brane offers very great resistance to sympathetic vibrations when the sound-waves 
Fig. 720. 
Tensor tympani—the Eustachian 
tube (left). 1016 
MUSCLES OF THE TYMPANUM. 
[Sec. 410. 
are very intense, as it is a physical fact that stretched membranes are more dif- 
ficult to throw into sympathetic vibrations the tenser they are. Thus, the ten- 
sion so far protects the auditory organ, as it prevents too intense vibrations 
affecting the membrana tympani from reaching the terminations of the nerves. 
2. The tension of the membrana tympani must vary according to the degree of 
contraction of the tensor. Thus, the membrana for the time being has a differ- 
ent fundamental tone, and is thereby capable of vibrating to the correspond- 
ingly higher tone, it, as it were, being in a certain sense accommodated for. 
Comparison with Iris.—The membrana tympani has been compared with the iris. Both 
membranes prevent, by contraction—narrowing of the pupil and tension of the membrana tym- 
pani—the too intense action of the specific stimulus from causing too great stimulation, and both 
adapt the sensory apparatus, for the action of moderate or weak stimuli. This movement in 
both membranes is brought about rejlexly, in the ear through the N. acusticus, which causes a 
reflex stimulation of the motor fibres for the tensor tympani. 
Effect of Tension.—That increased tension of the membrana tympani renders it less sensi- 
tive to sound-waves is easily proved, thus: Close the mouth and nose, and make either a forced 
expiration, so that the air is forced into the Eustachian tube, which bulges out the membrana 
tympani, or inspire forcibly, whereby the air in the tympanum is diminished, so that the mem- 
brana bulges inwards. In both cases, hearing is interfered with, as long as the increased tension 
lasts. If a funnel with a small lateral opening, and whose wide end is covered by a membrane, 
be placed in the external meatus, hearing becomes less distinct when the membrane is stretched 
(Joh. Muller). If air be blown into the external auditory meatus, both tensores tympani 
contract, and in consequence of this the hearing of the other ear is temporarily affected (Gelle). 
Normally, the tensor tympani is excited rejlexly. The muscle is not directly and by itself sub- 
ject to the control of the will. According to L. Fick, the following phenomenon is due to an 
“ associated movement ” of the tensor: When he pressed his jaws firmly against each other, he 
heard in his ear a piping, singing tone, while a capillary tube, which was fixed air-tight into the 
meatus, had a drop of water which was in it rapidly drawn inwards. During this experiment, a 
person with normal hearing hears all musical tones as if they were louder, while all the highest 
non-musical tones are enfeebled [Lucae). When yawning, v. Helmholtz and Politzer found 
that hearing was enfeebled for certain tones. 
Contraction of the Tensor.—Hensen showed that the contraction of the 
tensor tympani during hearing is not a continued contraction, but what might 
be termed a “ twitch.” A twitch takes place at the beginning of the act of 
hearing, which favors the perception of the sound, as the membrana tympani 
thus set in motion vibrates more readily to higher tones than when it is at rest. 
On exposing the tympanum in cats and dogs, it was found that this contraction 
or twitch occurs only at the beginning of the sound, and that it soon ceases, 
although the sound may continue. 
Action of the Stapedius.—The muscle arises within the eminentia pyra- 
midalis, and is inserted into the head of the stapes and Sylvian ossicle (fig. 
721); when it draws upon the head of the stapes, as indi- 
cated in fig. 711, by the small curved arrow, it must place 
the bone obliquely, whereby the posterior end of the plate 
of the stapes is pressed somewhat deeper inwards into the 
fenestra ovalis, while the anterior is, as it were, displaced 
somewhat outwards. The stapes is thereby more fixed, as 
the fibrous mass [angular ligament] which surrounds the 
fenestra ovalis and keeps the stapes in its place becomes 
more tense. The activity of this muscle, therefore, pre- 
vents too intense shocks, which may be communicated from 
the incus to the stapes, from being conveyed to the peri- 
lymph. It is supplied by the facial nerve (§ 349, 3). 
The stapedius in many persons executes an associated movement, when the eyelids are forcibly 
closed (§ 349). Some persons can cause it to contract rejlexly by scratching the skin in front of 
the meatus, or by gently stroking the outer margin of the orbit (Henle). It seems to be excited 
reflexly in many diseases of the ear when the tympanum is being syringed. 
Other Views.—According to Lucae, when the stapes is displaced obliquely, its head forces the 
Fig. 721. 
Right stapedius 
muscle. Sec. 410]. 
EUSTACHIAN TUBE. 
long process of the incus, and also the membrana tympani, outivards, so that it is regarded as an 
antagonist of the tensor tympani. Politzer observed that the pressure within the labyrinth fell 
when he stimulated the muscle. According to Toynbee, the stapedius acts as a lever and moves 
the stapes slightly out of the fenestra ovalis, thus making it more free to move, so that it is more 
capable of vibrating. Henle supposes that the stapedius is more concerned in fixing than in mov- 
ing the stapes, and that it comes into action when there is danger of too great movement being 
communicated to the stapes from the incus. Landois agrees with this opinion, and compares the 
stapedius with the orbicularis palpebrarum, both being protective muscles. 
Pathological.—Immobility of the auditory ossicles, either by adhesions or anchyloses, causing 
diminished vibrations, interferes with hearing; while the same result occurs when the stapes is 
firmly anchylosed into the fenestra ovalis. The tendon of the tensor tympani has been divided 
in cases of contracture of the muscles. For paralysis of the tensor, see \ 347, and for the 
stapedius, \ 349. 
411. EUSTACHIAN TUBE—TYMPANUM.—The Eustachian 
tube [4 centimetres in length in.), 2-3 mm. in width (fig. 722)] is the ven- 
tilating tube of the tympanic cavity. It keeps the tension of the air within 
the tympanum the same as that within the pharynx and 
outer air (figs. 7x1, 720). Only when the tension of 
the air is the same outside and inside the tympanum, is 
the normal vibration of the membrana tympani possible. 
The tube is generally closed, as the surfaces of the mu- 
cous membrane lining it come into apposition. During 
swallowing, however, the tube is opened, owing to 
the traction of the fibres of the tensor veli palatini 
[spheno-salpingo-staphylinus sive abductor tubse (v. 
Troltscfi), sive dilator tubae (Riidinger)~\ inserted into 
the membrano-cartilaginous part of the tube (Toynbee, 
Politzer). (Compare § 139, 2.) When the tube is 
closed, the vibrations of the membrana tympani are 
transferred in a more undiminished condition to the 
auditory ossicles than when it is open, whereby part of 
the vibrating air is forced through the tube (.Mach and 
Kessel). If, however, the tympanic cavity is closed 
permanently, the air within it becomes so rarefied (§ 139) 
that the membrana tympani, owing to the abnormally low tension, becomes 
drawn inwards, thus causing difficulty of hearing. As the tube is lined by 
ciliated epithelium it carries outwards to the pharynx the secretions of the 
tympanum (§ 291). 
[Functions of the Eustachian Tube.—It permits the air in the tympa- 
num to be changed, it acts as an outlet for secretions, maintains the equilibrium 
between the air in the tympanum and that in the external auditory meatus, and 
it prevents the rarefaction of the air in the tympanum produced by successive 
acts of swallowing.] 
Noise in the Tube,—A sharp hissing noise is heard in the tube during swallowing, when 
we swallow slowly and at the same time contract the tensor tympani, due to the separation of 
the adhesive surfaces of its lining membrane. Another person may hear this noise by using a 
stethoscope or his ear. 
In Valsalva’s experiment ($ 60), as soon as the pressure of the air reaches 10 to 40 mm. 
Hg, air enters the tube. The sound is heard first, and then we feel the increased tension of the 
tympanic membrane, owing to the entrance of air into the tympanum. During forced inspiration, 
when the nose and mouth are closed, air is sucked out, while the tympanum is ultimately drawn 
inwards. , 
The M. levator veli palatini, as it passes under the base of the opening of the tube into the 
pharynx, forms the levator-eminence or cushion (fig. 432, W). Hence, when this muscle con- 
tracts and its belly thickens, as at the commencement of the act of deglutition and during phona- 
tion, the lower wall of the pharyngeal opening is raised, and the opening thereby narrowed 
{Luces). The contraction of the tensor, occurring during the latter part of the act of deglutition, 
dilates the tube. 
Schematic section of the 
Eustachian tube, m 
and /, lateral median 
plate; K, edge of the 
tube; V, levator, and t, 
tensor palate; L, lumen 
of tube. 
Fig. 722. 1018 
TYMPANUM. 
[Sec. 411. 
Other Views.—According to Riidinger, the tube is always open, although only by a very 
narrow passage in the upper part of the canal, while the canal is dilated during swallowing. 
According to Cleland, the tube is generally open, and is closed during swallowing. 
[Practical Importance.—The tympanic cavity forms an osseous box, and 
therefore a protective organ for the auditory ossicles and their muscles, while 
the increased air space, obtained by its communication with the mastoid cells, 
permits free vibration of the membrana tympani. The six sides of the tympa- 
num have important practical relations. It is about half an inch in height, 
and one or two lines in breadth, i. e., from without inwards. Its roof is sepa- 
rated from the cavity of the brain by a very thin piece of bone, which is some- 
times defective, so that encephalitis may follow an abscess of the middle ear. 
The outer wall is formed by the membrana tympani, while on the inner wall 
are the fenestra ovalis and rotunda, the ridge of the aqueductus Fallopii, the 
Fig. 723.—Bellows attached to an Eustachian catheter (Macnaughton Jones). Fig. 724.— 
Vertical section of the head, showing the Eustachian catheter in position. 
F'g. 723- 
Fig. 724. 
promontory, and the pyramid. The floor consists of a thin plate of bone, 
which roofs in the jugular fossa and separates it from the jugular vein. Frac- 
tures of the base of the skull may rupture the carotid artery or internal jugular 
vein ; hence, hemorrhage from the ears is a bad symptom in these cases. Caries 
of the ear may extend to other organs. The anterior wall is in close relation 
with the carotid artery, while the posterior communicates with the mastoid cells, 
so that fluids from the middle ear sometimes escape through the mastoid cells.] 
That the air in the tympanum can communicate its vibrations to the membrane of the fenestra 
rotunda is true (p. 1009, 3), but 7tormally this is so slight, when compared with the conduction 
through the auditory ossicles, that it scarcely need be taken into account. 
Structure.—The tube and tympanum are lined by a common mucous membrane, covered by 
ciliated epithelium, while the membrana is lined by a layer of squamous epithelium. Mucous 
glands were found by Troltsch and Wendt in the mucous membrane. [The epithelium covering 
the ossicles and tensor tympani is not ciliated.] Sec. 411.] 
LABYRINTH. 
Pathological.—The tube is often occluded, owing to chronic catarrh and narrowing from 
cicatrices, hypertrophy of the mucous membrane, or the presence of tumors. The deafness 
thereby produced may often be cured by catheterizing the tube from the nose (fig. 724). Effusions 
into or suppuration within the tympanum of course paralyze the sound-conducting mechanism, 
while inflammation often causes subsequent affections of the plexus tympanicus. If the temporal 
bone be destroyed by progressive caries within the tympanum, inflammation of the neighboring 
cerebral structures may occur and cause death. 
[Methods.—Not unfrequently the aurist is called upon to dilate the Eustachian tube, which 
in certain cases requires the use of a Eustachian catheter introduced into the tube along the 
floor of the nose (fig. 724). At other times he requires to fill the tympanic cavity with air, 
which is easily done by means of a Politzer’s bag or inflating bellows (fig. 723). The nozzle is 
introduced into one nostril, while the other nostril is closed, and the patient is directed to swallow, 
while at the same moment the surgeon compresses the bag, and the patient’s mouth being closed, 
air is forced through the open Eustachian tube into the middle ear.] 
[Politzer’s ear-manometer (fig. 725) consists of a U-shaped small glass tube fixed in an 
india-rubber cork, so that the latter can be hermetically fixed in the meatus. A drop of colored 
fluid is placed in the tube. During the first part of the act of swal- 
lowing—the nostrils and mouth being closed—the fluid rises slightly, 
but in the second part of the act it falls decidedly, owing to the rare- 
faction of the air in the tympanum.] 
412. CONDUCTION OF SOUND IN THE 
LABYRINTH.—The vibrations of the foot of the 
stapes in the fenestra ovalis give rise to waves in the 
perilymph within the inner ear or labyrinth. These 
waves are so-called 11 flexion-waves," i. e., the perilymph 
moves in mass before the impulse of the base of the stapes. This is only pos- 
sible from the existence of a yielding membrane—that filling the fenestra 
rotunda, and sometimes called the me7nbrana secundari, which during rest 
bulges inwards to the scala tympani, and can be bulged outwards towards the tym- 
panic cavity by the impulse communicated to it by the movement of the peri- 
lymph (fig. 711, r). The flexion waves must correspond in number and 
intensity to the vibrations of the auditory ossicles, and must also excite the 
free terminations of the auditory nerve, which float free in 
the endolymph. 
As the endolymph of the saccule and utricle lying in the 
vestibule receives the first impulse, and as these communi- 
cate anteriorly with the cochlea, and posteriorly with the 
semicircular canals, consequently the motion of the peri- 
lymph must be propagated through these canals. To reach 
the cochlea, the movement passes from the saccule (lying 
in the fovea hemispherica) along the scala vestibuli to the 
helicotrema, where it passes into the scala tympani, where 
it reaches the membrane of the fenestra rotunda, and 
causes it to bulge outwards. From the tdricle (lying in 
the fovea hemielliptica), in a similar manner the movement 
is propagated through the semicircular canals. Politzer 
observed that the endolymph in the superior semicircular 
canal rose when he caused contraction of the tensor 
tympani by stimulating the trigeminus, just as the base of 
the stapes must be forced against the perilymph with every vibration of the 
membrana tympani. 
[Practical.—It is well to view the organ of hearing as consisting of two 
mechanisms :— 
1. The sound-conducting apparatus. 
2. The sound-perceiving apparatus. 
The former includes the outer ear, with its auricle and external meatus; the 
middle ear and the parts which bound it, or open into it. The latter consists 
Politzer’s ear-mano- 
meter. 
Fig- 725- 
Fig. 726. 
External appearance 
of the osseous laby- 
rinth, fenestra ova- 
lis, cochlea to the 
left, and (f) the 
upper, (A) horizon- 
tal, and (j) posterior 
semicircular canal 
(left). 1020 
THE COCHLEA. 
[Sec. 412. 
of the inner ear with the expansion of the auditory nerve in the labyrinth, the 
nerve itself, and the sound-perceiving and interpreting centre or centres in the 
brain (§ 376, 2).] 
[Testing the Sound-conduction.—In any case of deafness it is essential 
to estimate the degree of deafness by the methods stated at § 406, and it is 
well to do so both for such sounds as those of a watch and conversation. We 
have next to determine whether the sound-conducting or the sound-perceiving 
apparatus is affected. If a person is deaf to sounds transmitted through the 
air, on applying a sounding tuning-fork (fig. 727), to the middle line of the 
head or teeth, if it be heard distinctly, then the sound-perceiving apparatus is 
intact, and we have to look for the cause of deafness in the outer or middle 
ear. In a healthy person, the sound of the tuning-fork is heard of equal 
intensity in both ears. In this case the sound is conducted directly to the 
labyrinth by the cranial bones. In cases of disease of the sound-conducting 
mechanism, the sound pf the tuning-fork is heard loudest in the 
deafer ear. Ed. Weber pointed out that, if one ear be stopped 
and a vibrating tuning-fork placed on the head, the sound is re- 
ferred to the plugged ear, where it is heard loudest. It is assumed 
that when the ear is plugged, the sound-waves transmitted by the 
cranial bones are prevented from escaping (Mach). If, on the 
contrary, the sound be heard loudest in the good ear, then in all 
probability there is some affection of the sound-perceiving appa- 
ratus or labyrinth, although there are exceptions to this statement, 
especially in elderly people. Another plan is to connect two 
telephones with an induction machine, provided with a vibrating 
Neef s hammer. The sounds of the vibrations of the latter are 
reproduced in the telephones, and if they be placed to the ears, 
then the healthy ears hear only one sound, which is referred to the 
middle line, and usually to the back of the head. In diseased 
conditions this is altered—it is referred to one side or the other.] 
413. LABYRINTH AND AUDITORY NERVE.— 
Scheme.—The vestibule (fig. 728, III) contains two separate 
sacs; one of them, the saccule, (round sac or S. hemisphseri- 
cus), communicates with the ductus cochlearis, Cc of the 
cochlea; the other, the utricle, U (elliptical sac, or sacculus 
hemiellipticus), communicates with the semicircular canals, Cs, Cs. 
The cochlea consists of 2y2 turns of a tube disposed round a 
central column or modiolus. The tube is divided into two com- 
partments by a horizontal septum, partly osseous and partly mem- 
branous, the lamina spiralis ossea and membranacea (fig. 
732, fig. 728, I). The lower compartment is the scala tym- 
pani and is separated from the cavity of the tympanum by the 
membrane of the fenestra rotunda. 
• The upper compartment is the scala vestibuli, which com- 
municates with the vestibule of the labyrinth (fig. 728, I). These 
two compartments communicate directly by a small opening at the apex of the 
cochlea, a sickle-shaped edge [“hamulus”] of the lamina spiralis bounding 
the helicotrema (fig. 711). The scala vestibuli is divided by Reissner’s 
membrane (fig. 728, I), which arises near the outer part of the lamina spiralis 
ossea, and runs obliquely outwards, to the wall of the cochlea so as to cut off a 
small triangular canal, the ductus or canalis cochlearis, or scala media, 
Cc, whose floor is formed for the most part by the lamina spiralis membranacea, 
and on which the end-organ of the auditory nerve—Corti’s organ—is placed. 
The lower end of the canalis cochlearis is blind, III, and divided towards the 
Fig. 727. 
Aural 
tuning-fork. Sec. 413.] 
THE COCHLEA. 
1021 
saccule, with which it communicates by means of the small canalis reuniens, 
Cr (.Hensen). The utricle (fig. 728, III, U) communicates with the three 
semicircular canals Cs, Cs—each by means of an ampulla, within which lie 
Fig. 728. 
I, transverse section of a turn of the cochlea; II, A, ampulla of a semicircular canal with the 
crista acustica; a, p, auditory cells; p, provided with a fine hair; T, otoliths; III, 
scheme of the human labyrinth; IV, scheme of a bird’s labyrinth; V, scheme of a fish’s 
labyrinth. 
the terminations of the ampullary nerves, but as the posterior and the superior 
canals unite, there is only one common ampulla for them. The membranous 
The interior of the right labyrinth with its membranous canals and nerves. In fig. 729 the 
outer wall of the bony labyrinth is removed to show the membranous parts within—1, 
commencement of the spiral tube of the cochlea; 2, posterior semicircular canal, partly 
opened; 3, horizontal; 4, superior canal; 5, utricle; 6, saccule; 7, lamina spiralis, 7 
scala tympani; 8, ampulla of the superior membranous canal; 9, of the horizontal; 10, of 
the posterior canal. Fig. 730 shows the membranous labyrinth and nerves detached—1, 
facial nerve in the internal auditory meatus; 2, anterior division of the auditory nerve 
giving branches to 5, 8, and 9, the utricle and the ampullae of the superior and horizontal 
canals; 3, posterior division of the auditory nerve, giving branches to the saccule, 6, and 
posterior ampulla, 10, and cochlea, 4; 7, united part of the posterior and superior canals; 
11, posterior extremity of the horizontal canal. 
Fig. 729. 
Fig. 730. 
semicircular canals lie within the osseous canals, perilymph lying between the 
two. Perilymph also fills the scala vestibuli and s. tympani, so that all the 1022 
CRISTA AND MACULA ACUSTICA. 
[Sec. 413. 
spaces within the labyrinth are filled by fluid, while the spaces themselves are 
lined by short cylindrical epithelium. 
The system of spaces, filled by endolymph, is the only part containing the 
nervous end-organs for hearing. All these spaces communicate with each 
other; the semicircular canals directly with the utricle, the ductus cochlearis 
with the saccule through the canalis reuniens; and lastly, the saccule and 
utricle through the “ saccus endolymphaticus,” which springs by an 
isolated limb from each sac ; the limbs then unite as in the letter Y, and pass 
through the osseous aqueductus vestibuli to end blindly in the dura mater of 
the brain (fig. 728, III, R). The aqueductus cochlea is another narrow passage, 
which begins in thescala tympani, immediately in front of the fenestra rotunda, 
and opens close to the fossa jugularis. It forms a direct means of communica- 
tion between the perilymph of the cochlea and the subarachnoid space. 
Semicircular Canals and Vestibular Sacs.—The membranous semi- 
circular canals do not fill the corresponding osseous canals completely, but are 
separated from them by a pretty wide space, which is filled with perilymph 
(fig. 729). At the concave margin they are fixed by connective-tissue to the 
osseous walls. The ampullae, however, completely fill the corresponding osse- 
ous dilatations. The canals and ampullae consist externally of an outer, vascu- 
lar, connective-tissue layer, on which there rests a well-marked hyaline layer, 
bearing a single layer of flattened epithelium. 
Crista Acustica.—The vestibular branch of the auditory nerve sends a 
branch to each ampulla and to the saccule and utricle (fig. 730). In the 
ampullae (fig. 728, II, A) the nerve (c) terminates in connection with the 
crista acustica, which is a yellow elevation pro- 
jecting into the equator of the ampulla. The medul- 
lated nerve-fibres, n, form a plexus in the connective- 
tissue layer, lose their myelin as they pass to the 
hyaline basement membrane, and each ends in a cell 
provided with a rigid hair (<?,/), 90 n in length, so 
that the crista is largely covered with these hair- 
cells, but between them are supporting cells like 
cylindrical epithelium (a), and not unfrequently con- 
taining granules of yellow pigment. The hairs or 
“ auditory hairs ” (M. Schultze) are composed of 
many fine fibres (Retzius). An excessively fine mem- 
brane (membrana tectoria) covers the hairs 
(Pritchard, Lang). 
Maculae Acusticae.—The nerve-terminations in 
the maculae acusticae of the saccule and utricle are 
exactly the same as in the ampullae, only the free 
surface of their membrana tectoria is sprinkled with 
small, white, chalk-like crystals or otoliths (fig. 728, 
II, T), composed of calcic carbonate, which are 
sometimes amorphous and partly in the form of 
arragonite, lying fixed in the viscid endolymph. 
The non-medullated axis-cylinders of the saccular 
nerves enter directly into the substance of the hair-cells. The terminations of 
the nerves have been investigated, chiefly in fishes, in the rays. 
[Fig. 731 is a vertical section of a macula acustica of the rabbit. The 
medullated nerves (n) lose their myelin at the external limiting membrane, 
become non-medullated, pierce this membrane, and form a basal plexus (pb) 
between (/) the epithelial cells, and finally terminate in the sensory ciliated 
cells (p). The epithelium itself consists of basal cells ('cb), fusiform or sup- 
Vertical section of the macula 
acustica of rabbit. 
Fig. 73i- Sec. 413.] 
MEMBRANA RETICULARIS. 
1023 
porting cells (/), and the ciliated neuro-epithelium (/), each cell being pro- 
vided with a cilium, which perforates the external limiting membrane (a). 
There is thus a remarkable likeness to the olfactory epithelium.] 
Cochlea.—The terminations of the cochlear branch of the auditory nerve 
lie in connection with Corti’s organ, which is placed in the canalis or ductus 
cochlearis (fig. 728, I, Cc, and III, Cc, and fig. 732), the small triangular 
chamber [or scala media], cut off from the scala vestibuli by the membrane of 
Reissner. Corti’s organ is placed on the lamina spiralis membranacea, and 
consists of a supporting apparatus composed of the so-called Corti’s arches, 
each of which consist of two Corti’s rods (zy), which lie upon each other 
like the beams of a house. But every two rods do not form an arch, as there 
are always three inner to two outer rods (Claudius). There are about 4500 
outer rods ( Waldeyer). 
The ductus cochlearis becomes larger towards the apex of the cochlea, and 
the rods also become longer; the inner ones are 30 //. long in the first turn, 
Fig- 732- 
Scheme of the ductus cochlearis and the organ of Corti. N, cochlear nerve; K, inner, and P, 
outer hair cells; n, nerve-fibrils terminating in P; a, a, supporting cells; d, cells in the 
sulcus spiralis; z, inner rod of Corti; Mb. Corti, membrane of Corti, or the membrana tec- 
toria; 0, the membrana reticularis; H, G, cells filling up the space near the outer wall. 
and 34 // in the upper, the outer rods 47 /a and 69 /a respectively. The span 
of the arches also increases (Hensen). [The arches leave a triangular tunnel 
beneath them.] The proper end-organs of the cochlear nerve are the cylindri- 
cal “hair-cells” (Kd Hiker) previously observed by Corti, which are from 
16,400 to 20,000 in number (.Hensen, Waldeyer). There is one row of inner 
cells (/), which rests on a layer of small granular cells (K) (.Bottcher, Wal- 
deyer) ; the outer cells (a, a) number 12,000 in man (.Retzius), and rest upon 
the basement membrane, being disposed in three or even four rows. Between 
the outer hair-cells there are other cellular structures, which are either regarded 
as special cells (Deiter’s cells), or are regarded merely as processes of the 
hair-cells (.Lavdowsky). [The cochlear branch of the auditory nerve enters 
the modiolus, and runs upwards in the osseous channels there provided for it, 1024 
AUDITORY PERCEPTIONS. 
[Sec. 413. 
and as it does so gives branches to the lamina spiralis, where they run between 
the osseous plates which form the lamina.] The fibres (N) come out of the 
lamina spiralis after traversing the ganglionic cells in their course (figs. 728, 
732, I, G), and end by fine varicose fibrils in the hair-cells (fig. 732) ( Wal- 
deyer, Gottstein, Lavdowsky, Retzius). 
Membrana Reticularis.—Corti’s rods and the hair-cells are covered by a 
special membrane {o), the membrana reticularis of Kolliker. The upper 
ends of the hair-cells, however, project through holes in this membrane, which 
consists of a kind of a cement-substance holding these parts together (Lavdow- 
sky). [Springing from the outer end of the lamina spiralis, or crista spiralis, is 
the membrana tectoria, sometimes called the membrane of Corti. It is a 
well-defined structure, often fibrillated in appearance, and extends outwards 
over the organ of Corti.] Waldeyer regards it as a damping apparatus for 
this organ (fig. 732, Mb. Corti). 
[Basilar Membrane.—Its breadth increases from the base to the apex of 
the cochlea. This fact is important in connection with the. theory of the per- 
ception of tone. It is supposed that high notes are appreciated by structures 
in connection with the former, and low notes by the upper parts of the basilar 
membrane. In one case, recorded by Moos and Steinbrugge, a patient heard 
low notes only in the right ear, and after death it was found that the auditory 
nerve in the first turn of the cochlea was atrophied.] 
Intra-Labyrinthine Pressure.—The lymph within the labyrinth is under a certain pressure, 
every diminution of the pressure of the air in the tympanum is accompanied by a corresponding 
diminution of the intra-labyrinthine pressure, while conversely every increase of pressure is 
accompanied by an increase of the lymph-pressure (F. Bezold). 
The perilymph of the inner ear flows away chiefly through the aqueductus 
cochleae, in the circumference of the foramen jugulare, into the peripheral 
lymphatic system, which also takes up the cerebro-spinal fluid of the subarach- 
noid space, while a small part drains away to the sub-dural space through the 
internal auditory meatus. The endolymph flows through the arachnoid sheath 
of the N. acusticus into the subarachnoid space (C. Hasse). 
[Composition of Ear Fluids.—Perilymph and endolymph are alkaline, and contain 
salts in about the same proportion as transudations. Perilymph contains 2.1 per cent, of solids, 
containing a trace of albumin, .and more mucin and common salt. The endolymph is less 
viscid, and contains 1.5 per cent, of solids, and less mucin. Otoliths consist of 74.5-79 per 
cent, of inorganic matter, chiefly calcium carbonate. The organic matter is said to resemble 
mucin.] 
414. AUDITORY PERCEPTIONS.—Every normal ear is able to dis- 
tinguish musical tones and noises. Physical experiments prove that tones 
are produced when a vibrating elastic body executes periodic movements, i. e., 
when the sounding body executes the same movement in equal intervals of 
time, as the vibrations of a string which has been plucked. A noise is pro- 
duced by non-periodic movements, i.e., when the sounding body executes 
unequal movements in equal intervals of time. [The non-periodic movements 
clash together on the ear, and produce dissonance, as when we strike the key- 
board of a piano at random.] This is readily proved by means of the siren. 
Suppose that there are forty holes in the rotatory disc of this instrument, placed 
at exactly the same distance from each other—on rotating the disc and direct- 
ing a current of air against it, obviously with every rotation the air will be 
rarefied and condensed exactly forty times. Every two condensations and 
rarefactions are separated from each other by an equal interval of time. This 
arrangement yields a characteristic musical tone or note. If a similar disc with 
holes perforated in it at unequal distances be used, on air being forced against 
it, a whirring non-musical noise is produced, because the movements of the Sec. 414.] 
PERCEPTION OF PITCH. 
1025 
sounding body (the condensations and rarefactions of the air) are non-periodic. 
[The double siren of v. Helmholtz is an improved instrument for showing the 
same facts.] 
The normal ear also distinguishes in every tone three distinct fac- 
tors :— 
[(1) Intensity or force ; 
(2) Pitch; 
(3) Quality, timbre or “ klang. ”] 
1. The intensity of a tone depends upon the greater or lesser amplitude 
of the vibrations of the sounding body. It is well known that a vibrating 
string emits a feebler sound when its excursions are smaller. (The intensity of a 
sound corresponds to the degree of illumination or brightness in the case of the 
eye.) ... 
2. The pitch depends upon the number of vibrations which occur in a 
given time [or the length of time occupied by a single vibration]. This is 
proved by means of the siren. If the rotating disc have a series of forty holes 
at equal intervals, and another series of eighty equidistant from each other, on 
blowing a stream of air against the rotating disc we hear two sounds of unequal 
pitch, one being the octave of the other. (The perception of pitch corresponds 
to the sensation of color in the case of the eye.) 
3. The quality or timbre (“ Klangfarbe"') is peculiar to different sonorous 
bodies. [It is the peculiarity of a musical tone by which we are enabled to 
distinguish it as coming from a particular instrument, or from the human voice. 
Thus, the same note struck on a piano and sounded on a violin differs in quality 
or timbre.] It depends upon the peculiar form of the vibration, or the form of 
the wave of the sonorous body. (There is no analogous sensation in the case of 
light.) 
I. Perception of Pitch.—By means of the organ of hearing, we can determine that different 
tones have a different pitch. In the so-called musical scale, or gamut, this difference is very 
marked to a normal ear. But in the scale there are again four tones, which, when they are 
sounded together, cause in a normal ear the sensation of an agreeable sound, which once heard 
can readily be reproduced. This is the tone of the so-called accord, Triad, or Common Chord, 
consisting of the 1st, 3d and 5th tones of the scale, to which the eighth tone or octave is added. 
We have next to determine the pitch of the tones of the chord, and then that of the other 
tones of the scale. The siren is used for the fundamental experiment, from which the others 
can easily be calculated. Four concentric circles are drawn upon the rotatory disc of the 
siren ; the inner circle contains 40 holes, the second 50, the third 60, and the outer 80—all the 
holes being at equal distances from each other. If the disc be rotated, and air forced against 
each series of holes in turn, we distinguish successively the four tones of the accord (major 
chord with its octave) ; when all the four series are blown upon simultaneously, we hear in com- 
plete purity the major chord itself. The relative nianber of the holes in the four series indicates 
in the simplest manner the relative pitch of the tones of the major chord. While one revolution 
of the disc is necessary to produce the fundamental ground-tone (key-note or tonic) with 40 
condensations and rarefactions of the air—in order to produce the octave, we must have 
double the number of condensations and rarefactions during one revolution in the same time. 
Thus, the relation of the number of vibrations of the Ground-tone or Tonic to the Octave next 
above it, is 1 : 2. In the second series we have 50 holes, which causes the pitch of the third ; 
hence, the relation of the Ground-tone to the Third in this case is 40 : 50, or 1 : iX = b *• e•> 
for every vibration of the Ground-tone there are | vibrations in the Third. In the third series are 
60 holes, which, when blown upon, yield the fifth; hence, the ratio of the Ground-tone to the 
Fifth in our disc is 40 : 60, or I : ij) = |. In the same way we can estimate the pitch of the 
Fourth tone, and we find that the number of vibrations of the First, Third, Fifth, and Octave are 
to each other as 1 : f : § : 2. 
The minor chord is quite as characteristic to a normal ear as the major. It is distinguished 
essentially from the latter by its Third being half a tone lower. We can easily imitate it by 
the siren, as the Minor Third consists of a number of vibrations which stand to the Ground-tone 
as 6 : 5, i. e., if 5 vibrations occur in a given time in the Ground-tone, then 6 occur in the Minor 
Third; its vibration number, therefore, is f. 
From these relations of the Major and Minor common chords, we may calculate the relative 1026 
AUDIBLE TONES. 
[Sec. 414. 
tones in the scale, and we must remember that the Octave of a tone always yields the fullest 
and most complete harmony. It is evident that as the Major Third, and Minor Third, and the 
Fifth harmonize with the fundamental Ground-tone or key-note, they must also harmonize with 
the Octave of the key-note. We obtain from the Major Third with the number of vibrations 
the Minor Sixth jj, from the Minor Third with -|, the Major Sixth = (T = ) |; from the Fifth 
with |, the Fourth = J. These relations are known as the “ Inversions of the intervals.” These 
relations of the tones are, collectively, the consonant intervals of the scale. The dissonant 
stages, or discords, of the scale can be obtained as follows: Suppose that we have the Ground- 
tone or key-note C, with the number of vibrations = I, the Third E = J, the Fifth G = f, and 
the Octave = 2, we then derive from the Fifth or Dominant G a Major chord—this is G, B, D1. 
The relative number of vibrations of these 3 tones is the same as in the Major chord of C1, C, E, 
G. Hence, the number of vibrations of G : B is as C : E. When we substitute the values we 
obtain | : B — 1 : f—i. e., B = l85. But D1 : B = G : E; so that D : = | : f, i. e., Dl = 
Y, or an octave lower, we have D = |. Deduce from F (subdominant) a Major chord, F, A, 
C1. The relation of A : C1 = E : G, or A : 2 = J i. e., A = Lastly, F : A = C : E, or 
F : f = I : f, f. <?., F = f. So that all the tones of the scale have the following number of 
vibrations : I, C = I ; II, D = f ; III, E = |; IV, F = f; V, G = § ; VI, A — 8 ; 
VII, B = y ; VIII, C1 = 2. 
Conventional Estimate of Pitch.—Conventionally, the pitch or concert-pitch of the note 
a, is taken at 440 vibrations in the second (Scheibler, 1834), although in France it is taken at 
435 vibrations per second. From this we can estimate the absolute number of vibrations for the 
tones of the scale : C = 33, D = 37.125, E = 41.25, F = 44, G = 49.5, A = 55, B =61.875 
vibrations. The number of vibrations of the next highest octave is found at once by multiplying 
these numbers by 2. 
Musical Notes.—The lowest notes used in music are the double-bass, E, with 41.25 vibra- 
tions, pianoforte C with 33, grand piano Al with 27.5, and organ Cl with 16.5. The highest 
notes in music are the pianoforte cv with 4224, and dvon the piccolo-flute, with 4752 vibrations 
per second. 
Limits of Auditory Perception.—According to Preyer, the limit of 
the perception of the lowest audible tone lies between 16 and 23 vibrations per 
second, and eviii with 40,960 vibrations as the highest audible tone; so that this 
embraces about ii|- octaves. 
[Audibility of Shrill Notes.—This varies very greatly in different persons (Wollaston). 
There is a remarkable falling off of the power as age advances (Gallon). For testing this Galton 
uses a small whistle made of a brass tube, with a diameter of less than Tyh of an 
inch (fig. 733). A plug is fitted at the lower end to lengthen or shorten the tube, 
whereby the pitch of the note is altered. Amongst animals Galton finds none 
superior to cats in the power of hearing shrill sounds, and he attributes this “<o 
differentiation by natural selection amongst these animals until they have the power 
of hearing all the high notes made by mice and other little creatures they have to 
catch.”] 
Variations in Auditory Perception.—It is rare to find that tones produced by 
more than 35,000 vibrations per second are heard. When the tensor tympani is 
contracted, the perception may be increased for tones 3000 to 5000 vibrations higher, 
but rarely more. Pathologically, the perception for high notes may be abnormally 
acute—(1) When the tension of the sound-conducting apparatus generally is in- 
creased. (2) By elimination of the sound-conducting apparatus of the middle ear, 
which offers greater or less resistance to the propagation of very high notes, as per- 
foration of the membrana tympani, or loss of the incus and malleus. In these cases, 
the stapes is directly set in vibration by the sound-waves, when tones up to 80,000 
vibrations have been perceived. Diminished tension of the sound-conducting appa- 
ratus causes diminution of the perception for high tones [Blake). 
A smaller number of vibrations than 16 per second (as in the organ) are no longer heard as a 
tone, but as single dull impulses. The tones that are produced beyond the highest audible note, 
as by stroking small tuning-forks with a violin bow, are also no longer heard as tones, but 
they cause a painful cutting kind of impression in the ear. In the musical scale the range is, 
approximately, from C of the first octave with 16.5 vibrations to E, the eighth octave. 
Comparison of Ear and Eye.—In comparing the perception of the eye with that of the ear, 
we see at once that the range of accommodation of the ear is much greater. Red has 456 
billions of vibrations per second, while the visible violet has but 667, so that the eye only takes 
cognizance of vibrations which do not form even one octave. 
Lowest Audible Tone.—As to the smallest number of successive vibra- 
tions which the ear can perceive as a sensation of tone, Savart and Pfaundler 
Fig. 733- 
Galton’s 
Whistle. Sec. 414.] 
QUALITY OF SOUNDS AND VOWELS. 
1027 
considered that two would suffice. If, however, we exclude in our experiments 
the possibility of the occurrence of overtones, 4 to 8 (Mach) or even 16 to 20 
vibrations (FAuerbach, Kohlrausch) are necessary to produce a characteristic 
tone. 
When tones succeed each other rapidly, they are still perceived as distinct, 
when at least o. 1 second intervenes between two successive tones (v. Helm- 
holtz) ; if they follow each other more rapidly, they fuse with each other, 
although a short-time interval is sufficient for many musical tones. 
By the term, “fineness of the ear," or as we say, a “good ear,” is meant 
the capacity of distinguishing from each other, as different, two tones of nearly 
the same number of vibrations. This power can be greatly increased by prac- 
tice, so that musicians can distinguish tones that differ in pitch by only or 
even of their vibrations. 
With regard to the time-sense, it is found that beats are more precisely 
perceived by the ear than by the other sense organs (Horing, Mach). 
Pathological.—According to Lucae, there are some ears that are better adapted for hearing 
tow notes and others for high notes. Both conditions are disadvantageous for hearing speech. 
Those who hear low notes best hear the highest consonants imperfectly. The low notes are 
heard abnormally loud in rheumatic facial paralysis, while the high tones are heard abnormally 
loud in cases of loss of the membrana tympani, incus, and malleus. The stapedius is in full 
action, whereby the highest tones are heard louder at the expense of the lower notes. Many 
persons with normal hearing hear a tone higher with one ear than with the other. This con- 
dition is called diplacusis binauralis. In rare cases, sudden loss of the perception of certain 
tones has been observed, e. g., the bass-deafness of Moos. In a case described by Magnus, 
the tones dl, bl, were not heard ($ 316). 
II. Perception of the Intensity of Tone.—The intensity of a tone depends upon the ampli- 
tude of the vibrations of the sounding body. The intensity of the tone is proportional to the 
square of the amplitude of vibration of the sounding body, i. e., with 2, 3, or 4 times the ampli- 
tude the intensity of the tone is 4, 9, 16 times as strong. As sonorous vibrations are communi- 
cated to our ears by the wave-movements of the air, it is evident that the tones must become less 
and less intense the further we are from the source of the sound. The intensity of the sound is 
inversely proportional to the square of the distance of the source of the sound from the ear. 
Tests.—1. Place a watch horizontally near the ear, and test how close it may be brought to 
the ear, and also how far it may be removed, and still its sounds be heard. Measure the dis- 
tance. 2. Itard uses a small hammer suspended like a pendulum, and allowed to fall upon a 
hard surface. 3. Balls of different weights are allowed to fall from varying heights upon a plate. 
In this case the intensity of the sound is proportional to the product of the weight of the ball 
into the height it falls. 
As to the limits of the perception of the intensity of a tone, it is found that a spherule weigh- 
ing 1 milligram, and falling from a height of 1 mm. upon a glass plate, is heard at a distance of 
5 centimetres (Schafhault). 
415. PERCEPTION OF QUALITY—VOWELS.—By the term 
quality (“ Klangfarbe”), musical color or timbre, is understood a peculiar 
character of the tone, by which it can be distinguished apart from its pitch and 
intensity. Thus, a flute, horn, violin, and the human voice may all sound the 
same note with equal intensity, and yet all the four are distinguished at once 
by their specific quality. Wherein lies the essence (“ Wesen ”) of tone-color? 
The investigations of v. Helmholtz have proved that, amongst mechanisms 
which produce tones, only those that produce pendulum-like vibrations, i. e., 
the to-and-fro vibrations of a metallic rod with one end fixed, and tuning- 
forks, execute simple pendulum-like vibrations. This can be shown by making 
a tuning-fork write off its vibrations on a recording surface, when a completely 
uniform wave-line, with equal elevations and depressions is noted. The term 
“ tone” is restricted to those sounds, hardly ever occurring in nature, which 
are due to simple pendulum-like vibrations. 
Other investigations have shown that the tones of musical instruments and. of the human 
voice, all of which have a characteristic quality of their own, are composed of many single 
simple tones. Amongst these one is characterized by its intensity, and at the same time it de- 1028 
ANALYSIS OF VOWELS. 
[Sec. 415. 
termines the pitch of the whole compound musical “ tone-picture.” This is called the funda- 
mental tone or key-note. The other weaker tones which, as it were, spring from and are 
mingled with this, vary in different instruments both in intensity and number. They are “ upper 
tones,” and their vibrations are always some multiple—2, 3, 4, 5 .... times—of the funda- 
mental tone or key-note. In general, we say that all those outbursts of sound which embrace 
numerous strong upper tones, especially of high pitch, in addition to the fundamental tone, are 
characterized by a sharp, piercing, and rough quality, such as emanates from a trumpet or 
clarionet, and that conversely the quality is characterized by mildness and softness when the 
overtones are few, feeble, and low, e.g., such as are produced by the flute. It requires a well- 
trained musical ear to distinguish, in an instrumental burst, the overtones apart from the funda- 
mental tone. But this is very easily done with the aid of resonators (fig. 735). These consist 
of spherical or funnel-shaped hollow bodies, made of brass or some other substance, which, by 
means of a short tube, can be placed in the outer ear. If a resonator be placed in the ear, we 
can hear the feeblest overtone of the same number of vibrations as the fundamental tone. Thus, 
musical instruments are distinguished by the number, intensity, and pitch of the overtones which 
they produce. A vibrating metallic rod and a tuning-fork have no overtones; they only give 
the fundamental tone. As already mentioned, the term simple tone is applied to sounds due to 
simple pendulum-like vibrations, while a sound composed of a fundamental tone and overtones 
is called a “ klang” or compound musical tone. 
Vibration Curve of a Musical Tone.—When we remember that a musical tone or klang 
consists of a fundamental tone, and a number 
of overtones of a certain intensity, which de- 
termine its quality, then we ought to be able 
to construct geometrically the vibration curve 
of the musical tone. Let A represent the 
vibration curve of the fundamental tone, and 
B that of the first moderately weak overtone 
(fig- 734)- The combination of these two 
curves is obtained simply by computing the 
height of the ordinates, whereby the ordinates 
of the overtone curve, lying above the abscissa 
or horizontal line, are added to the funda- 
mental tone curve, while those of the ordinates 
below the line are subtracted from it. Thus 
we obtain the curve C, which is not a simple 
pendulum-like curve, but one which corre- 
sponds to an unsteady movement. A new 
curve of the second overtone may be added to 
C, and so on. The result of all these combina- 
tions is that the vibration curves corresponding 
to the compound musical tones are unsteady pe- 
riodic curves. All these curves must, of course, 
vary with the number and pitch of the com- 
pounded overtone curves. 
Displacement of the Phases.—The form 
of the vibration of one and the same musical 
tone may vary very greatly if, in compounding the curves A and B, the curve B is only slightly 
displaced laterally. If B is displaced so that the hollow of the wave r falls under A, the ad- 
dition of both curves yields the curve r, r, r, with small elevations and broad valleys. If B be 
displaced still further, until the elevation of the wave, h, coincides with A, we obtain still another 
form, so that by displacement of the phases of the wave-motions of the compounded simple pen- 
dulum-like vibrations, we obtain numerous different forms of the same musical tone. The dis- 
placement of the phases, however, has no effect on the ear. 
The general result of these observations, and those of Fourier, is that the quality of a musical 
tone depends upon the characteristic form of the vibratory movement. 
Analysis of Vowels.—The human voice represents a reed instrument with vibrating elastic 
membranes, the vocal cords (§ 312). In uttering the various vowels the mouth assumes a char- 
acteristic form, so that its cavity has a certain fundamental tone peculiar to itself. Thus, to the 
fundamental tone of a certain pitch produced within the larynx, there are added certain over- 
tones which communicate to the laryngeal tone the vocal or vowel quality. Hence, a vowel is 
the timbre or quality of a musical tone which is produced in the larynx. The quality depends 
upon the number, intensity, and pitch of the overtones, and the latter, again, depend on the con- 
figuration of the “ vocal cavity” in uttering the different vowels (§ 317). 
Suppose a person to sing the vowels one after the other on a special note, e.g., b b, we can, 
with the aid of resonators, determine the overtones, and in what intensity they are mixed with 
Carves of a musical tone obtained by com- 
pounding the curve of a fundamental tone 
with that of its overtones. 
F'g- 734- Sec. 415.] 
ANALYSIS OF VOWELS. 
the fundamental tone, b b, to give the characteristic quality. According to v. Helmholtz, when 
Koenig’s manometric capsule (A) and mirror (M) {Koenig). 
Fig- 735- 
Fig. 736. 
Flame-pictures of the vowels ou, o, and A (Koenig). 
we sound the vowels on b b, for each of the three vowels, one overtone is specially character- 
istic for A—bn b; for O-b1 b; for U-t. The other vowels and the diphthongs have each (wo 1030 
ANALYSIS OF VOWELS. 
[Sec. 415. 
specially characteristic overtones, because in these cases the mouth is so shaped that the posterior 
larger cavity, and also the anterior narrower part, each yields a special tone ($ 316, I and E). 
These two overtones are for E-Bl11 b and f 1; for I-div and f; for A-gHI and d11; for O-c111 # 
and f I; for U-g111 and f. These, however, are only the special upper tones. There are many 
more upper tones, but they are not so prominent. 
Artificial Vowels.—Just as it is possible to analyze a vowel into its fundamental tone and 
its upper tones, it is possible to compound tones to produce the vowels by simultaneously sound- 
ing the fundamental tone and the corresponding upper tones. (1) A vowel is produced simply 
by singing loudly a vowel, e.g., A, upon a certain note against the free strings of an open piano, 
whilst by the pedal the damper is kept raised. As soon as we stop singing, the characteristic 
vowel is sounded by the strings of the piano. The voice sets into sympathetic vibration all 
those strings whose overtones (in addition to the fundamental tone) occur in the vocal compound 
tone, so that they vibrate for a time after the voice ceases (v. Helmholtz). (2) The vowel ap- 
paratus devised by v. Helmholtz consists of numerous tuning-forks, which are kept vibrating by 
means of electro-magnets. The lowest tuning-fork gives the fundamental tone, B b, and the 
others the overtones. A resonator is placed in front of each tuning-fork, and the distance 
between the two can be varied at pleasure. The resonators can be opened and closed by a lid 
passing in front of their openings. When the resonator is closed, we cannot hear the tone 
emitted by the tuning-fork placed in front of it; but when one or more resonators are opened 
the tone is heard distinctly, and it is louder the more the resonator is opened. By means of a 
series of keys, like the keys of a pianoforte, we can rapidly open and close the resonators at will, 
and thus combine various overtones with the fundamental tone so as to produce vowels with 
different qualities. V. Helmholtz makes the following compositions: U = B b with b b weak 
and f1 ; O = damped B b with b1 b strong and weaker b b, f'1, d11 ; A = b b (fundamental tone) 
with moderately strong b1 b and fH, and strong b" b and dm; A = b b (fundamental tone) 
with bl b and f11 somewhat stronger than for A, d strong, b11 b weaker, d111 and fMI as strong as 
possible ; E = b b (as fundamental tone) moderately strong, with b1 b and f' moderate also, and 
fill1, a111 b, and b111 b, as strong as possible; I could not be produced. 
In Appunn’s apparatus, the fundamental tone and the overtones are produced by means of 
organ pipes, whose notes can be combined to produce the vowels, but it is not so good as the 
tuning forks, since the organ pipes do not yield simple tones, but nevertheless some of the vowels 
can be admirably reproduced with this apparatus. 
Edison’s Phonograph.—If we utter the vowels against a delicate membrane stretched over 
the end of a hollow cylinder, and if a writing style be fixed to the centre of the membrane, and 
the style be so arranged that it can write or record its movements on a piece of soft tinfoil 
arranged on a revolving apparatus, then the vowel curve is stamped as it were upon the tinfoil. 
If the style now be made to touch the tinfoil while the latter is moved, then the style is moved— 
it moves the membrane, and we hear distinctly by resonance the vowel sound reproduced. 
[Koenig’s Manometric Flames.—By means of this apparatus the quality of the vowel 
sounds is easily shown. It consists of a small wooden capsule, A, divided into two compartments 
by a piece of thin sheet india-rubber. Ordinary gas passes into the chamber on one side of the 
membrane, through the stop cock, and it is lighted at a small burner. To the other compart- 
ment is attached a wide tube with a mouthpiece. The whole is fixed on a stand, and near it is 
placed a four sided rotating mirror, M, as suggested by Wheatstone (fig. 735). On speaking or 
singing a vowel into the mouthpiece, and rotating the mirror, a toothed or zigzag flame-picture 
is obtained in the mirror. The form of the flame-picture is characteristic for each vowel, and 
varies of course with the pitch.] [Fig. 736 shows the form of the flame-picture obtained in the 
rotating mirror when the vowels, ou, o, A, are sung at a pitch of ul1, solv and utT This series 
shows how they differ in quality.] 
[Koenig has also invented the apparatus for analyzing any compound tone whose funda- 
mental tone is UT2 (fig. 737). It consists of a series of resonators, from ut2 to UT5, fixed in an 
iron frame. Each resonator is connected with its special flame, which is pictured in a long 
narrow, square rotating mirror. If a tuning-fork ut2 be sounded, only the flame UT2 is affected, 
and so on with each tuning-fork of the harmonic series. Suppose a compound note containing 
the fundamental tone ut2, and its harmonics be sounded, then the flame of UT2, and those of the 
other harmonics in the note, are also affected, so that the tone can be analyzed optically. The 
same may be done with the vowels.] 
416. LABYRINTH DURING HEARING.—If we ask what role the 
ear plays in the perception of the quality of sounds, then we must assume 
that, just as with the help of resonators a musical note can be resolved into its 
fundamental tone and overtones, so the ear is capable of performing such an 
analysis. The ear resolves the complicated wave-forms of musical tones into 
their components. These components it perceives as tones harmonious with Sec. 416.] 
LABYRINTH DURING HEARING. 
1031 
each other; with marked attention each is perceived singly, so that the ear dis- 
tinguishes as different tone-colors only different combinations of these simple 
tone-sensations. The resolution of complex vibrations, due to quality, into 
simple pendulum-like vibrations is a characteristic function of the ear. What 
apparatus in the ear is capable of doing this? If we sing vigorously—e.g., 
the musical vowel A on a definite note, say b b—against the strings of an open 
pianoforte while 
the damper is 
raised, then we 
cause all those 
strings, and only 
those, to vibrate 
sympathetically, 
which are con- 
tained in the 
vowel so sung. 
We must, there- 
fore, assume that 
an analogous 
sympathetic ap- 
paratus occurs 
in the ear, which 
is tuned, as it 
were, for differ- 
ent pitches, and 
which will vi- 
brate sympathet- 
ically like the 
strings of a 
pianoforte. “It 
we could so con- 
nect every string 
of a piano with 
a nerve-fibre that 
the nerve-fibre 
would be excited 
and perceived as 
often as the 
string vibrated, 
then, as is actu- 
ally the case in the ear, every musical note which affected the instrument would 
excite a series of sensations exactly corresponding to the pendulum-like vibra- 
tions into which the original movements of the air can be resolved; and thus 
the existence of each individual overtone would be exactly perceived, as is 
actually the case with the ear. The perception of tones of different pitch 
would under these circumstances depend upon different nerve-fibres, and hence 
would occur quite independently of each other. Microscopic investigation 
shows that there are somewhat similar structures in the ear. The free ends of 
all the nerve-fibres are connected with small elastic particles which we must 
assume are set into sympathetic vibration by the sound-waves” ([v. Helmholtz). 
Resolution by the Cochlea.—Formerly v. Helmholtz considered the 
rods of Corti to be the apparatus that vibrated and stimulated the terminations 
of the nerves. But, as birds and amphibians, which certainly can dis- 
tinguish musical notes, have no rods (Hasse), the stretched radial fibres of the 
Fig. 737- 
Koenig’s apparatus for analyzing a compound tone with the fundamental 
tone ut2. 1032 
PERCEPTION OF SOUNDS. 
[Sec. 416. 
membrana basilaris, on which the organ of Corti is placed, and which are 
shortest in the first turn of the cochlea, becoming longer towards the apex of 
the cochlea, are now regarded as the vibrating threads (Hensen). Thus, a 
string-like fibre of the membrana basilaris, which is capable of vibrating, cor- 
responds to every possible simple tone. According to Hensen, the hairs of the 
labyrinth, which are of unequal length, may serve this purpose. Destruction of 
the apex of the cochlea causes deafness to deeper tones (3 agin sky). 
[Hensen’s Experiments.—That the hairs in connection with the hair- 
cells vibrate to a particular note is also rendered probable by the experiments 
of Hensen on the crustacean Mysis. He found that certain of the minute 
hairs (auditory hairs) in the auditory organ of this animal, situate at the base 
of the antennae, vibrated when certain tones were sounded on a keyed horn. 
The movements of the hairs were observed by a low-power microscope. In 
mammals, however, there is a difficulty, as the hairs attached to the cells appear 
to be all about the same length. We must not forget that the perception of 
sound is a mental act.] 
This assumption also explains the perception of noises. 
Of noises in the strictly physical sense, it is assumed that they, like single 
impulses, are perceived by the aid of the saccules and the ampullae. 
It is assumed that the saccules and the ampullae are concerned in the 
general perception of hearing, i. <?., of shocks communicated to the auditory 
nerve (by impulses and noises); while by the cochlea we estimate the pitch 
and depth of the vibrations, and musical character of the vibrations produced 
by tones. The relation of the semi-circular canals to the equilibrium of 
the body is referred to in § 350. 
417. SIMULTANEOUS ACTION OF TWO TONES—HAR- 
MONY—BEATS—DISCORDS—DIFFERENTIAL TONES.— 
When two tones of different pitch fall upon the ear simultaneously, they cause 
different sensations according to the difference in pitch. 
1. Consonance.—If the number of vibrations of the two tones is in the 
ratio of simple multiples, as 1 : 2 : 3 : 4, so that when the low notes make one 
vibration the higher one makes 2 : 3 or 4 . . . . then we experience a sensa- 
tion of complete harmony or concord. 
2. Interference.—If, however, the two tones do not stand to each other in 
the relation of simple multiples, then when both tones are sounded simulta- 
neously inte7-ference takes place. The hollows of the one sound-wave can no 
longer coincide with the hollows of the other, and the crests with the crests, 
but, corresponding to the difference of number of vibrations of both curves, 
sometimes a wave-crest must coincide with a wave-hollow. Hence, when wave- 
crest meets wave-crest, there must be an increase in the strength of the tone, 
and when a hollow coincides with a crest, the sound must be weakened. Thus 
w6 obtain the impression of those variations in tone intensity which have been 
called “beats.” 
The number of vibrations is of course always equal to the difference of the number of vibra- 
tions of both tones. The beats are perceived most distinctly when two organ tones of low pitch 
are sounded together in unison, but slightly out of tune. Suppose we take two organ pipes with 
33 vibrations per second, and so alter one pipe that it gives 34 vibrations per second, then one 
distinct beat will be heard every second. The beats are heard more frequently the greater the 
difference between the number of vibrations of the two tones. 
Successive Beats.—The beats, however, produce very different impres- 
sions upon the ear according to the rapidity with which they succeed each other. 
1. Isolated Beats.—When they occur at long intervals, we may perceive 
them as completely isolated, but single intensifications of the sound with sub- 
sequent enfeeblement, so that they give rise to the impression of isolated beats. Sec. 417.J 
BEATS AND TONES. 
1033 
2. Dissonance.—When the beats occur more rapidly they cause a continuous 
disagreeable whirring impression which is spoken of as dissonance, or an inhar- 
monious sensation. The greatest degree of unpleasant painful dissonance occurs 
when there are 33 beats per second. 
3. Harmony.—If the beats take place more rapidly than 33 times per 
second, the sensation of dissonance gradually diminishes, and it does so the 
more rapidly the beats occur. The sensation passes gradually from moderately 
inharmonious relations (which in music have to be resolved by certain laws) 
towards consonance or harmony. The tone relations are successively the 
Second, Seventh, Minor Third, Minor Sixth, Major Third, Major Sixth, Fourth, 
and Fifth. 
4. Effect of the Musical Tones (“Klange").—Two musical “klangs,” 
or compound tones, falling on the ear simultaneously, produce a result similar 
to that of two simple tones; but in this case we have to deal not only with the 
two fundamental tones, but also with the overtones. Hence the degree of dis- 
sonance of two musical tones is the more pronounced the more the fundamental 
tones and the overtones (and the “differential” tones) produce beats which 
number about 33 per second. 
5. Differential Tones.—Lastly two “klangs,” or two simple musical 
tones sounding simultaneously, may give rise to new tones when they are 
uniformly and simultaneously sounding in corresponding intensity. We can 
hear, if we listen attentively, a third new tone, whose number of vibrations 
corresponds to the difference between the two primary tones, and hence it is 
called a “ differential tone." 
Summational Tones.—It was formerly supposed that new tones could arise from the sum- 
mation or addition of their number of vibrations, but it has been shown that these tones are in 
reality differential tones of a high order (Appunn, Preyer). 
418. PERCEPTION OF SOUND—OBJECTIVE AND SUB- 
JECTIVE AUDITION—AFTER-SENSATION.—Objective and 
Auditory Perceptions.—When the stimulation of the terminations of the 
nerves of the labyrinth is referred to the outer world, then we have objective 
auditory perceptions. Such stimulations are only referred to the outer world as 
are conveyed to the membrana tympani by vibrations of the air, as is shown by 
the fact that if the head be immersed in water, and the auditory meatuses be 
filled thereby, we hear all the vibrations as if they occurred within our head 
itself (Ed. Weber), and the same is the case with our own voice, as well as 
with the sound-waves conducted through the bones of the head, when both ears 
are firmly plugged. 
Perception of Direction.—As to the perception of the direction whence 
sound comes, we obtain some information from the relation of both meatuses 
to the source of the sound, especially if we turn the head in the supposed 
direction of the sound. We distinguish more easily the direction from which 
noises mixed with musical tones come than that of tones (Rayleigh). When 
both ears are stimulated equally, we refer the source of the sound to the middle 
line anteriorly, but when one ear is stimulated more strongly than the other, 
we refer the source of the sound more to one side (Kessel). The position of 
the ear-muscles, which perhaps act like an ear-funnel, is important. According 
to Ed. Weber, it is more difficult to determine the direction of sound when 
the ears are firmly fixed to the side of the head. Further, if we place the 
hollow of both hands in front of the ear, so as to form an open cavity behind 
them, we are apt to suppose that a sounding body placed in front is behind us. 
The semicircular canals are said also to be concerned, as sound coming from a 
certain direction must always excite one canal more than the others. Thus, 
the left horizontal canal is most stimulated by horizontal sound-waves coming 1034 
PERCEPTION OF DIRECTION. 
[Sec. 418. 
from the left (Preyer). Other observers assert that the membrana tympani 
localizes the sound, as only certain parts of it are affected by the sound-waves. 
The distance of a sound is judged of partly by the intensity or loudness of 
the sound, such as we have learned to estimate from sound at a known distance. 
But still we are subject to many misconceptions in this respect. 
Amongst subjective auditory sensations are the after-vibrations, & specially of intense and 
continued musical tones; the tinnitus aurium (p. 762), which often accompanies abnormal 
movements of the blood in the ear, may be due to a mechanical stimulation of the auditory 
fibres, perhaps by the blood stream {Brenner). 
[Drugs.—Cannabis indica seems to act on the hearing centre, giving rise to subjective sounds ; 
the hearing is rendered more acute by strychnin; while quinine and sodic salicylate in large 
doses cause ringing in the ears (Brunton).~\ 
Entotical perceptions, which are due to causes wfithin the ear itself, are such as hearing the 
pulse-beats in the surrounding arteries, and the rushing sound of the blood, which is especially 
strong when there is increased resonance of the ear (as when the meatus or tympanum is closed, 
or when fluid accumulates in the latter), during increased cardiac action, or in hyperaesthesia 
of the auditory nerve {Brenner). Sometimes there is a cracking noise in the maxillary 
articulation, the noise produced by traction of the muscles on the Eustachian tube (§ 411), and 
when air is forced into the latter, or when the membrana tympani is forced outwards or 
inwards (§ 350). 
Fatigue.—The ear after a time becomes fatigued, either for one tone or for a series of tones 
which have acted on it, while the perceptive activity is not affected for other tones. Complete 
recovery, however, takes place in a few seconds {Urbant sc kitsch). 
Auditory After-Sensations.—(1) Those that correspond to positive after-sensations, where 
the after-sensation is so closely connected with the original tone that both appear to be contin- 
uous. (2) There are some after-sensations, where a pause intervenes beeween the end of the 
objective and the beginning of the subjective tone (Urbantschitsch). (3) There seems also to 
be a form corresponding to negative after-images. 
In some persons, the perception of a tone is accompanied by the occurrence of subjective 
colors, of the sensation of light, e.g., the sound of a trumpet, accompanied by the sensation of 
yellow. More seldom visual sensations of this kind are observed when the nerves of taste, 
smell, or touch are excited {Nussbaumer, Lehmann, and Bleuler). It is more common to find 
that an intense sharp sound is accompanied by an associated sensation of the sensory nerves. 
Thus many people experience a cold shudder when a slate pencil is drawn in a peculiar manner 
across a slate. 
[Color Associations.—Color is in some persons instantaneously associated with sound, and 
Gabon remarks that it is rather common in children, although in an ill-developed degree, and 
the tendency seems to be very hereditary. Sometimes a particular color is associated with a 
particular letter, vowel sounds particularly evoking colors. Galton has given colored represen- 
tations of these color associations, and he points out their relation to what he calls number- 
forms, or the association of certain forms with certain numbers.] 
An auditory impulse communicated to one ear at the same time often causes an increase in the 
auiitory function of the other ear, in consequence of the stimulation of the auditory centres of 
both sides {Urbantschitsch, Eitelberg). 
Other Stimuli.—The auditory apparatus, besides being excited by sound-waves, is also 
affected by heterologous stimuli. It is estimated mechanically by a sudden blow on the ear. 
The effect of electricity and pathological conditions are referred to in § 350. 
419. COMPARATIVE—HISTORICAL.—The lowest fishes, the cyclostomata (Petro- 
myzon), have a saccule provided with auditory hairs containing otoliths, and communicating 
with two semicircular canals, while the myxinoids have only one semicircular canal. Most of 
the other fishes, however, have a utricle communicating with three semicircular canals. In the 
carp, prolongations of the labyrinth communicate with the swimming-bladder. In amphibia, 
the structure of the labyrinth is somewhat like that in fishes, but the cochlea is not typically 
developed. Most amphibia, except the frog, are devoid of a membrana tympani. Only the 
fenestra ovalis (not the rotunda) exists, and it is connected in the frog by three ossicles with the 
freely-exposed membrana tympani. Amongst reptiles the appendix to the saccule correspond- 
ing to the cochlea begins to be prominent. In the tortoise it is saccular, but in the crocodile 
it is longer, and somewhat curved and dilated at the end. In all reptiles the fenestra rotunda 
is developed, whereby the cochlea is connected with the labyrinth. In crocodiles and birds, 
the cochlea is divided into a scala vestibuli and S. tympani. Snakes are devoid of a tympanic 
cavity. In birds both saccules (fig. 728, IV, U S) are united {Hasse), the canal of the cochlea 
(U C), which is connected by means of a fine tube (C) with the saccule, is larger, and shows 
indications of a spiral arrangement, and has a flask-like blind end, the lagena (L). The Sec. 419-] 
THE SENSE OF SMELL. 
1035 
auditory ossicles in reptiles and birds are reduced to one column-like rod, corresponding to the 
stapes, and called the colummella. The lowest mammals (Echidna) have structures very 
like those of birds, while the higher mammals have the same type as in man (fig. 728, III). 
The Eustachian tube is always open in the whale. 
Amongst invertebrata, the auditory organ is very simple in medusae and mollusca. It is 
merely a bladder filled with fluid, with the auditory nerves provided with the ganglia in its 
walls. Hair-cells occur in the interior, provided with one or more otoliths. Hensen observed 
that in some of the annulosa, when sound was conducted into the water, some of the auditory 
bristles vibrated, being adapted for special tones. In cephalopoda, we distinguish the first differ- 
entiation into a membranous and cartilaginous labyrinth. 
Historical.—Empedocles (473 b. c.) referred auditory impressions to the cochlea. The 
Hippocratic School was acquainted with the tympanum, and Aristotle (384 B. c.) with the 
Eustachian tube. Vesalius (1561) described the tensor tympani; Cardanus (1560) the conduc- 
tion through the bones of the head; while Fallopius (1561) described the vestibule, the semi- 
circular canals, chorda tympani, the two fenestrse, the cochlea, and the aqueduct. Eustachius 
(j- 1570) described the modiolus, the lamina spiralis of the cochlea, the Eustachian tube, as well 
as the muscles of the ear; Plater the ampullae (1583) ; Casseri (1600) the lamina spiralis mem- 
branacea. Sylvius (1667) discovered the ossicle called by his name ; Vesling (1641) the stape- 
dius. Mersenne (1618) was acquainted with overtones; Gassendus (1658) experimented on the 
conduction of sound. Acoustics were greatly advanced by the work of Chladni (1802). The 
most recent and largest work on the ear in vertebrates is by G. Retzius (1881-84). 
The Sense of Smell. 
420. STRUCTURE OF THE ORGAN OF SMELL.—Regio 
Olfactoria.—The area of the distribution of the olfactory nerve is the regio 
olfactoria, which embraces the upper part of the septum, the upper turbinated 
bone and part of the middle (Cm) turbinated bone (fig. 738, Cs). All the 
remainder of the nasal cavity is called the regio respiratoria. These two re- 
gions are distinguished as follows : (1) The regio olfactoria has a thicker mucous 
membrane. (2) It is covered by a single layer of cylindrical epithelium, the 
cells being often branched at their lower ends, and contain a yellow or brownish- 
red pigment (figs. 739, 740, E). (3) It is colored by this pigment, and is 
thereby distinguished from the uncolored regio respiratoria, which is covered by 
ciliated epithelium. (4) It contains peculiar tubular glands (Bowman’s 
glands), described as “ mixed glands” by Paulsen (§ 142), while the rest of 
the mucous membrane contains numerous acinous serous glands (.Heidenhain) ; 
but in man the latter are said to be mixed glands (Stohr) (fig. 739). Lymph- 
follicles lie in the mucous membrane, and from them numerous leucocytes 
pass on to the free surface (Stohr). (5) Lastly, the regio olfactoria embraces 
the end-organs of the olfactory nerve. The long narrow olfactory cells (fig. 
740, N) are distributed between the ordinary cylindrical epithelium (E) cov- 
ering the regio olfactoria. The body of the cell is spindle-shaped, with a 
large nucleus containing nucleoli, and it sends upwards between the cylindrical 
cells a narrow (0.9 to 1.8 /*) smooth rod, quite up to the free surface of the 
mucous membrane. In the frog (n) the free end carries delicate projecting 
hairs or bristles. In the deeper part of the mucous membrane, the olfactory 
cells pass into, and become continuous with, varicose fine nerve-fibres, which 
pass into the olfactory nerve (§ 321, I, 1). According to C. K. Hoffman and 
Exner, after section of the olfactory nerve, the specific olfactory end-organs 
become changed into cylindrical epithelium (frog), and in warm-blooded 
animals they undergo fatty degeneration, even on the 15 th day. V. Brunn 
found a homogeneous limiting membrane, which had holes in it for transmitting 
the processes of the olfactory cells only. 
[The respiratory part of the nasal mucous membrane is lined by ciliated THE SENSE OF SMELL. 
[Sec. 420. 
epithelium stratified like that in the trachea and resting on a basement mem- 
brane. Below this there are many lymph-corpuscles and aggregations of 
adenoid tissue.] 
[The organ of Jacobson is present in all mammals, and consists of two narrow tubes pro- 
tected by cartilage, and placed in the lower and anterior part of the nasal septum. Each tube 
terminates blindly behind, but anteriorly it opens into the nasal furrow or into the naso-palatine 
canal (dog). The wall next the middle line is covered by olfactory epithelium, and receives 
olfactory nerves (rabbit, guinea-pig), and it contains glands similar to those of the olfactory 
region; the outer wall is covered by columnar epithelium, ciliated in some animals (A7<?f«).] 
[The olfactory non-medullated nerves arise from the olfactory bulb, which 
is a grayish-yellow small rounded mass lying on the orbital surface of the 
frontal lobe and upon the cribriform plate of the ethmoid bone (fig. 741). It 
is connected to the brain behind by the tractus olfactorius, which is tri- 
angular in cross-section and runs backwards to the substantia perforata anterior. 
Epithe- 
lium. 
Mucous 
mem- 
brane. 
Fig- 738- 
Fig- 739- 
Fig- 738 —Nasal and pharyngo-nasal cavities. Z, levator elevation; P.s.p., plica salpingo- 
palatina; Cs, Cm, Ci, the three turbinated bones. Fig. 739.—Vertical section of the 
olfactory region (rabbit), X disc; zo, zone of oval, and zr of spherical nuclei; b, 
basal cells; dr, part of a Bowman’s gland; n, branch of the olfactory nerve. 
Its roots have been described already (§ 343, I), but some of its fibres can be 
traced into the uncinate gyrus of the temporal lobe to the nucleus amygdaleus 
and cornu ammonis, while some fibres cross to the opposite side at the anterior 
border of the anterior commissure.] 
[The olfactory tract and bulb were originally a protrusion of the cerebral substance, and con- 
tained within them a narrow cavity continuous with the middle cornu of the lateral ventricle. 
Both the bulb and tract contain gray and white matter, and in the former are many corpora 
amylacea.] 
[In a sagittal section of the tract and bulb in the dog (fig. 742) we see that the bulb (<5) 
covers the tract (/) like a hood, while in the interior is seen the narrow canal. The olfactory 
tract is triangular in cross-section with rounded edges and slightly concave sides. At its basal 
part and covering the lateral angles are numerous fine medullated fibres, and there are also Sec. 420.] 
OLFACTORY BULB. 
1037 
medullated nerve-fibres on its dorsal aspect. The more central parts of the tract contain con- 
nective-tissue and some small nerve-cells.] 
[The olfactory bulb consists of many layers, as seen on vertical section. 
Most superficially it is covered by a layer of pia mater, and under it are 
numerous bundles of the fibres of the olfactory nerve—the nerve-fibre layer 
(fig- 743> D). The second layer, stratum glomerulosum (fig. 743, E), contains 
peculiar globular masses, closely packed together, and passing into them are 
nerve-fibres from the first layer. In these glomeruli the nerve fibrils come into 
Fig. 740. 
N, olfactory cells (human); 
n, from the frog; E, 
epithelium of the regio 
olfactoria. 
Part of the base of the brain, showing the Pp, pes 
pedunculi; Cm, corpus mammillare ; Tbc, tu- 
ber cinereum ; T II, and II, optic tract and 
nerve ; ch, chiasma ; T, temporal lobe; U, un- 
cus; Am, nucleus amygdaleus; Spa, anterior 
perforated spot; Lt, lamina terminalis ; Coa, 
position of anterior commissure ; F, frontal 
lobe; Bol, olfactory bulb ; Trot, olfactory tract. 
Fig. 741. 
Fig. 742. 
Sagittal section of the olfactory bulb of a 
dog; b, olfactory bulb; t, olfactory tract; 
v, ventricle of the bulb. X 4. 
relation with fibrils, the branches of nerve-cells. The third layer is the stratum 
gelatinosum (fig. 743), consisting of a finely granular ground-substance in which 
are scattered some branched cells, and through it there pass branches of nerve- 
fibres and nerve-cells. The fourth or nerve-cell layer (fig. 743, C) consists 
partly of a single layer of large branched nerve-cells which give off an axis- 
cylinder process centrally and protoplasmic processes peripherally. The latter 1038 
OLFACTORY SENSATIONS. 
[Sec. 420. 
enter the glomeruli. The next layer—stratum granulosum—consists of bundles 
of nerve-fibres with numerous granules intercalated amongst them. The inner- 
most or sixth layer contains 
medullated nerve-fibres. The 
similarity between the ele- 
ments contained in the olfac- 
tory bulb and those in the 
retina has been pointed out 
by many observers.] 
421. OLFACTORY 
SENSATIONS. —Olfac- 
tory sensations are produced 
by the action of gaseous, 
odorous substances being 
brought into direct contact 
with the olfactory cells dur- 
ing the act of inspiration. 
The current of air is divided 
by the anterior projection of 
the lowest turbinated bone, 
so that a part above the latter 
is conducted to the regio 
olfactoria. During inspira- 
tion, the air streams along 
close to the septum, while 
little of it passes through the 
nasal passages, especially the 
superior (.Paulsen and Ex- 
ner). [The expired air takes 
almost the same course as 
the inspired air.] Odorous 
bodies taken into the mouth 
and then expired through the 
posterior nares are said not 
to be smelt {Bidder). [This 
is certainly not true, as has 
been proved by Aronsohn.] 
[It is usually stated that only 
odorous particles suspended in air 
excite the sensation of smell. This 
is certainly not the whole truth— 
otherwise, how do aquatic animals, 
like fish, smell ? Moreover the 
mucous membrane is always moist, 
and in some cases where there is 
a profuse secretion from the olfac- 
tory mucous membrane, there is no 
impairment of the sense of smell.] 
The first moment of con- 
tact between the odorous 
body and the olfactory mu- 
cous membrane appears to be the time when the sensation takes place, as, when 
we wish to obtain a more exact perception, we sniff several times i. e., a 
series of rapid inspirations are taken, the mouth being kept closed. During 
sniffing, the air within the nasal cavities is rarefied, and as air rushes in to 
Antero-posterior section of the olfactory bulb and nasal 
mucous membrane of a new-born mouse. A, olfactory 
epithelium situated below the lamina cribrosa ; a, bipolar 
cells, and b, sustentacular cells. B, substantia propria 
of the mucosa with numerous nerve-fibres. C, ethmoidal 
cartilage ; D, layer of olfactory nerve-fibres; E, layer of 
olfactory glomeruli; F, inferior molecular layer ; G, layer 
of multipolar nerve-cells; H, superior molecular layer; I, 
granular layer; c, cartilage; e, olfactory nerves; f ramifi- 
cations of the olfactory fibrils in the glomeruli; g, central 
axis-cylinder process of a cell; h, multipolar nerve-cell; i, 
granules; j, epithelial cells; m, terminal filament of an 
epithelial cell; 0, large cell (Cayal). 
Fig- 743- Sec. 421.] 
OLFACTORY SENSATIONS. 
equilibrate the pressure, the air, laden with odorous particles, streams over the 
olfactory region. Odorous fluids are said not to give rise to the sensation of 
smell when they are brought into direct contact with the olfactory mucous 
membrane, as by pouring eau de Cologne into the nostrils (Tourtual, 1827 ; R. 
H. Weber, 1847). [Aronsohn has, however, shown that these experiments are 
not accurate, for one can smell eau de Cologne, clove oil, etc., when a mixture 
of these bodies with .75 per cent. NaCl is applied to the olfactory mucous 
membrane; the most suitable medium is .73 per cent. NaCl and its temperature 
40-43° C.] Even water alone temporarily affects the cells. We know practically 
nothing about the nature of the action of odorous bodies, but many odorous 
vapors have a considerable power of absorbing heat (Tyndall). [Odorous 
bodies diminish the number of respirations ( GourewitscJi).\ 
The intensity of the sensation depends on—1. The size of the olfactory 
surface, as animals with a very keen sense of smell are found to have complex 
turbinated bones covered by the olfactory mucous membrane. 2. The con- 
centration of the odorous mixture of the air. Still, some substances may be 
attenuated enormously (<?. g., musk to the two-millionth of a milligram), and 
still be smelt. 3. The frequency of the conduction of the vapor to the 
olfactory cells (sniffing). 
[The acuteness of the sense of smell is greatly improved by practice. A 
boy named James Mitchell, who was deaf, dumb, and blind, used his sense of 
smell, like a dog, to distinguish persons and things.] 
[As in the case of sight and hearing, it has been sought to connect the quality of taste and 
smell with the kind of vibrating stimulus. Ramsay showed that many facts pointed to the 
dependence of smell upon the vibratory motion of odorous particles; thus, many gases and 
vapors of low specific gravity—i.e., with a very rapid vibration of their molecules—are perfectly 
odorless, while such substances as the alcohols and fatty acids, alike in chemical and physical 
properties, can excite generic smells, the higher members of the group being more powerful in 
this respect than the lower ones. Taking the elements as arranged in a “ Natural Classification ” 
by Mendelejeff, Haycraft has shown that elements in the same group are capable of producing 
similar or related tastes, and the same seems to be true for smell (Haycraft).] 
We can smell the following substances in the following proportions: Bromine -joggo’ suh 
phuretted hydrogen jxmsWtt milligram in 1 c.cm. of air ( Valentin); also ifggggg 0 °f a milli- 
gram of chlorphenol, and °f a milligram of mercaptan (E. Fischer and Penzoldt). 
[Althaus found that electrical stimulation of the olfactory mucous membrane gave rise to 
the sensation of the smell of phosphorus, and Aronsohn found that he smelt on making the cur- 
rent when the cathode—and on breaking the current when the anode—was in the nose.] 
The variations are referred to in \ 343. If the two nostrils are filled with different odorous 
substances there is no mixture of the odors, but we smell sometimes the one and sometimes the 
other ( Valentin). [Some substances appear to affect some regions of the olfactory membrane, 
while others affect other parts.] The sense of smell, however, is very soon blunted, or even 
paralyzed. [It can be blunted or fatigued in a few minutes; but after it is completely fatigued 
it can recover in a minute.] Morphia, when mixed with a little sugar and taken as snuff, 
paralyzes the olfactory apparatus, while strychnin makes it more sensitive (Lichtenfels and 
Frohlich). 
The sensory nerves of the nasal mucous membrane (§ 347, II) [i.e., those 
supplied from the fifth cranial nerve] are stimulated by irritating vapors, and 
may even cause pain, e.g., ammonia and acetic acid. In a very diluted condi- 
tion they may even act on the olfactory nerves. The nose is useful as a sentinel 
for guarding against the introduction of disagreeable odors and foods. The 
sense of smell is aided by the sense of taste, and conversely. 
[Flavor depends on the sense of smell, and, to test it, use substances, solid 
or fluid, with an aroma or bouquet, such as wine or roast beef. 
[Method of Testing.—In doing so, avoid the use of pungent substances like ammonia, 
which excite the fifth nerve. Use some of the essential volatile oils, such as cloves, bergamot, 
and the foetid gum resins, or musk and camphor. Electrical stimuli are not suitable. Action 
of Drugs, § 343.] 
Comparative.—In the lowest vertebrata, pits, or depressions provided with an olfactory 
nerve, represent the simplest olfactory organ. Amphioxus and the cyclostomata have only one 1040 
papilla: of the tongue. 
[Sec. 421. 
olfactory pit; all other vertebrates have two. In some animals (frog) the nose communicates 
with the mouth by ducts. The olfactory nerve is absent in the whale. 
Historical.—Rufus Ephesius (97 A. D.) described the passage of the olfactory nerve through 
the ethmoid bone. Rudius (1600) dissected the body of a man with congenital anosmia, in 
whom the olfactory nerves were absent. Magendie originally supposed that the nasal branch of 
the fifth was the nerve of smell, a view successfully combated by Eschricht.] 
The Sense of Taste. 
422. STRUCTURE OF THE GUSTATORY ORGANS.—Gus- 
tatory Region.—There is considerable difference of opinion as to what re- 
gions of the mouth are endowed with taste : (1) The root of the tongue in the 
neighborhood of the circumvallate papillae, the area of distribution of the 
glosso-pharyngeal nerve, is undoubtedly endowed with taste (§ 351). The fili- 
form papillae and about 20 per cent, of the fungiform do not administer to taste 
( Oehrwali). (2) The tip and margins of the tongue are gustatory by means of the 
Epithelium 
Epithelium 
Tunica 
propria. 
Tunica 
propria. 
Fig. 744. 
Fig- 745- 
Fig. 744.—Longitudinal section of the dorsum of the human tongue. I, section of two filiform 
papillae, with secondary papillae (2); 3, double, 4, single process of epithelium with loose 
epithelial scales. X 30. Fig. 745 —Longitudinal section of the human tongue. I, secondary 
papillae on 2, the fungiform papilla; 3, base of 2; 4, small filiform papilla. X 30. 
fungiform papillae, but there are very considerable variations. (3) The lateral 
part of the soft palate and the glosso-palatine arch are endowed with taste from 
the glosso-pharyngeal nerve. (4) It is uncertain whether the hard palate and 
the entrance to the larynx are endowed with taste (Drielsma). The middle of 
the tongue is not gustatory. 
[Tongue—Mucous Membrane.—The structure of the tongue, as a 
muscular organ covered with mucous membrane, has already been described 
(§ 155). The dorsal surface of the tongue, in front of the blind foramen, is 
beset with elevations of the mucous membrane, which extend to its tip and 
borders. These elevations, or papillae, are of three kinds : filiform, fungi- 
form, and circumvallate. They consist of elevations of the mucous mem- 
brane, visible to the naked eye, and covered by stratified squamous epithelium, 
while the central core of connective tissue contains blood- and lymph-vessels 
and nerves. The filiform papillae occur over the whole tongue, and are 
smallest and most numerous. They are conical eminences, covered by stratified 
squamous epithelium, and often beset with secondary papillae (fig. 744). The 
fungiform papillae occur chiefly over the middle and front part of the 
tongue, and are not so numerous as the last. They are club-shaped, with a 
narrow base, and broad, expanded, rounded head. They also have secondary Sec. 422.] 
PAPILL.E OF THE TONGUE. 
1041 
papillae. They are generally brighter red than the others (fig. 745). The 
circumvallate papillae, 8 to 12 in number, diverge from the foramen 
caecum at the back part of the tongue in two rows in the form of a wide V, 
Fig. 746. 
I. Transverse section of a circumvallate papilla; W, the papilla; vv vv the wall in section, 
R, R, the circular slit or fossa; K, K, the taste-bulbs in position; N, N, the nerves. 
II. Isolated taste-bulb; D, supporting or protective cells; K, lower end ; E, free end,open, 
with the projecting apices of the taste-cells. III. Isolated protective cell (d) with a taste 
cell (e). 
the open angle of the V being directed forwards. They are large, with a broad 
expanded top, and are lodged in a depression of the mucous membrane, being 
surrounded by a wall of mucous 
membrane, and separated from 
it by a circular trench, into the 
base of which gland-ducts often 
open. They have numerous sec- 
ondary papillae, and in them are 
taste-buds, fig. 746, I.] 
Taste-bulbs.—The end- 
organs of the gustatory nerves 
are the taste-bulbs or taste-buds 
discovered by Schwalbe and 
Loven (1867). They occur on 
the lateral surfaces of the cir- 
cumvallate papillae (fig. 746, I), 
and upon the opposite side, K, 
of the fossa or capillary slit, 
R, R, which surrounds the cen- 
tral eminence or papilla; they 
occur more rarely on the surface. 
They also occur in the fungiform 
papillae, in the papillae of the 
soft palate and uvula (A. Hoff- 
mann), on the under surface of 
the epiglottis, the upper part of 
the posterior surface of the epi- 
glottis, and the inner side of the 
arytenoid cartilages (Verson, Davis), and on the vocal cords (Simanowsky). 
Many buds or bulbs disappear in old age. 
Epithelium 
Tunica 
propria. 
Fig. 747 
Vertical section of two septa of the papilla foliata 
(rabbit). X 80. Each septum, /, has secondary 
septa, l'; g, taste-buds ; n, medullated nerve; d, 
serous gland, and part of its duct, a; M, muscular 
fibres of the tongue. 1042 
GUSTATORY SENSATIONS. 
[Sec. 422. 
[In the rabbit and some other animals, there is a folded laminated organ on 
each side of the posterior part of the tongue, called the papilla foliata; the 
folds have on each side of them numerous taste-buds (fig. 746).] 
Structure of the Taste-bulbs.—They are 81 high and 33 // thick, barrel- 
shaped and embedded in the thick stratified squamous epithelium of the tongue. 
Each bulb consists of a series of lancet-shaped, bent, nucleated, outer support- 
ing or protective cells, arranged like the staves of a barrel (fig. 746, II, D, 
isolated in III, a), They are so arranged as to leave a small opening, or the 
“ gustatory pore,” at the free end of the bulb. Surrounded by these cells, 
and lying in the axis of the bud, are 1 to 10 gustatory cells (II, E, some of 
which are provided with a delicate process (III, e) at their free ends while their 
lower fixed ends send out basal processes, which become continuous with the 
terminations of the nerves of taste, which have become non-medullated. After 
section of the glosso-pharyngeal nerve, the taste-buds degenerate, while the pro- 
tective cells become changed into ordinary epithelial cells within four months 
(v. Vintschgau and Honigschmied). Very similar structures were found by 
Leydig in the skin of fresh-water fishes. The glands of the tongue and their 
secretory fibres from the 9th cranial nerve are referred to in § 141 (Drasch). 
423. GUSTATORY SENSATIONS.—Varieties.—There are four 
different gustatory qualities, the sensations of— 
1. Sweet. 
2. Bitter. 
3. Acid. 
4. Saline. 
Acid and saline substances at the same time also stimulate the sensory nerves of 
the tongue, but when greatly diluted, they only excite the end-organs of the 
specific nerves of taste. Perhaps there are special nerve-fibres for each different 
gustatory quality (v. Vintschgau). 
Conditions.—Sapid substances, in order that they may be tasted, require 
the following conditions: They must be dissolved in the fluid of the mouth, 
especially substances that are solid or gaseous. The intensity of the gustatory 
sensation depends on : 1. The size of the surface acted on. Sensation is favored 
by rubbing in the substance between the papillae; in fact, this is illustrated in 
the rubbing movements of the tongue during mastication (§ 354). 2. The con- 
centration of the sapid substance is of great importance. Valentin found that 
the following series of substances ceased to be tasted in the order here stated, 
as they were gradually diluted—syrup, sugar, common salt, aloes, quinine, sul- 
phuric acid. Quinine can be diluted 20 times more than common salt and still 
be tasted (Camerer). 3. The ti?ne which elapses between the application of 
the sapid substance and the production of the sensation varies with different 
substances. Saline substances are tasted most rapidly (after 0.17 second, accord- 
ing to v. Vintschgau), then sweet, acid, and bitter (quinine after 0.258 second, 
v. Vintschgau). This even occurs with a mixture of these substances (Schirmer). 
The last-named substances produce the most persistent “ after-taste.” 4. 
The delicacy of the sense of taste is partly congenital, but it can be greatly im- 
proved by practice. If a person continues to taste the same sapid substance, 
ora nearly related one, or even any very intensely sapid substance, the gustatory 
sense is soon affected, and it becomes impossible to give a correct judgment as 
to the taste of the sapid body. 5. Taste is greatly aided by the sense of smell, 
and in fact we often confound taste with smell; thus, ether, chloroform, musk, 
and assafoetida only affect the organ of smell. [The combined action of taste 
and smell in some cases gives rise to flavor (p. 1039).] The eye even may 
aid the determination, as in the experiment where in rapidly tasting red and 
white wine one after the other, when the eyes are covered, we soon become 
unable to distinguish between the one and the other. 6. The most advantage- 
ous temperature for taste is between io° to 350 C. ; hot and cold water tem- 
porarily paralyze taste. Sec. 423.] 
GUSTATORY SENSATIONS. 
1043 
[Oehrwall and others, by applying to the back of the tongue different solu- 
tions by means of a fine brush, found that certain filiform papillae reacted only 
to sugar, and not to tartaric acid, some which reacted to the application of 
quinine, but not to tartaric acid, and others which reacted to quinine, but not 
to sugar. By means of electrical stimulation bitter, saline, or sweet tastes could 
be produced. With the constant current the purest sensation occurred at the 
anode.] 
[The peculiar “ metallic taste ” which accompanies diffuse electrical stimu- 
lation of the gustatory mucous membrane is a mixed sensation due to bitter, 
saline, and sensory impressions. Continued stimulation excites fatigue of cer- 
tain tastes. These results may be explained by supposing that there are specific 
end-organs administering to the several varieties of taste, and which are dis- 
tributed in different proportions in the different papillae.] 
Ice placed on the tongue suppresses, sometimes entirely, the whole gustatory apparatus; cocain 
alone, bitter tastes, and water containing 2 per cent, of H2S04, excite afterwards a sweet taste 
{Aducco and Mosso). 
Electrical Current.—The constant current, when applied to the tongue, excites, both dur- 
ing its passage and when it is opened or closed, a sensation of acidity at the -f- pole, and at the 
— pole an alkaline taste, or, more correctly, a harsh burning sensation (Sulzer, 1752). This is 
not due to the action of the electrolytes of the fluid in the mouth, for even when the tongue is 
moistened with an acid fluid the alkaline sensation is experienced at the — pole ( Vol(a). We 
cannot, however, set aside the supposition that perhaps electrolytes, or decomposition products, 
may be formed in the parts and excite the gustatory fibres. Rapidly interrupted currents do 
not excite taste (Griinhagen). V. Vintschgau, who has only incomplete taste on the tip of the 
tongue, finds that when the tip of the tongue is traversed by an electrical current, there is never 
a gustatory sensation, but always a distinct tactile one. In experiments on Honigschmied, who 
is possessed of normal taste in the tip of the tongue, there was often a metallic or acid taste at 
the -f pole on the tip of the tongue, while at the — pole taste was often absent, and when it was 
present it was almost always alkaline, and acid only exceptionally. After interrupting the cur- 
rent there was a metallic after-taste with both directions of the current. 
[Testing Taste.—Direct the person to put out his tongue and close his 
eyes, and after drying the tongue apply the sapid substance by means of a 
glass rod or a small brush. Try to confine the stimulus as much as possible to 
one place, and after each experiment rinse the mouth with water. A wine- 
taster chews an olive to “ clean the palate,” as he says. For testing bitter taste 
use a solution of quinine or quassia; for sweet, sugar [or the intensely sweet 
substance “saccharine” obtained from coal tar]; saline, common salt; and 
acid, dilute citric or acetic acid. The galvanic current may also be used.] 
Pathological.—Diseases of the tongue, as well as dryness of the mouth, caused by interfer- 
ence with the salivary secretion, interfere with the sense of taste. Subjective gustatory im- 
pressions are common amongst the insane, and are due to some central cause, perhaps to irrita- 
tion of the centre for taste (§ 378, IV, 3). After poisoning with santonin, a bitter taste is ex- 
perienced, while after the subcutaneous injection of morphia, there is a bitter and acid taste. 
The terms hypergeusia, hypogeusia, and ageusia are applied to the increase, diminution, 
and abolition of the sense of taste. Many tactile impressions on the tongue are frequently con- 
founded with gustatory sensations, e.g., the so-called biting, cooling, prickling, sandy, mealy, 
astringent, and harsh tastes. 
Comparative.—About 1760 taste-bulbs occur on the circumvallate papillae of the ox. The 
term papilla foliata is applied to a large folded gustatory organ placed laterally on the side of 
the tongue (fig. 747), especially of the rabbit (Rapp, 1832), which in man is represented by analo- 
gous organs, composed of longitudinal folds, lying in the fimbriae linguae on each side of the pos- 
terior part of the tongue (.Krause v. Wyss). Taste-bulbs are absent in reptiles and birds. They 
are numerous in the gill-slits of the tadpole (F. E. Schultze), while the tongue of the frog is 
covered with epithelium resembling gustatory cells {Billroth, Axel Key). The goblet-shaped 
organs in the skin of fishes and tadpoles have a structure similar to the taste-bulbs, and may 
perhaps have the same function. There are taste-bulbs in the mouth of the carp and ray. 
Historical.—Bellini regarded the papillae as the organs of taste (1711). Richerand, Mayo, 
and Fodera thought that the lingual was the only nerve of taste, but Magendie proved that, after 
it was divided, the posterior part of the tongue was still endowed with taste. Panizza (1834) 
described the glosso-pharyngeal as the nerve of taste, the gustatory as the nerve of touch, and 
the hypoglossal as the motor nerve of the tongue. 1044 
TERMINATIONS OF SENSORY NERVES. 
[Sec. 424. 
The Sense of Touch. 
424. TERMINATIONS OF SENSORY NERVES.—i. The touch- 
corpuscles of Wagner and Meissner lie in the papillae of the cutis vera 
(§ 283), and are most numerous in the palm of the hand and the sole of the 
foot, especially in the fingers and toes, there being about 21 to every square 
millimetre of skin, or 108 to 400 of the papillae containing blood-vessels. They 
are less abundant on the back of the hand and foot, mamma, lips, and tip of 
the tongue, rare on the glans clitoridis, and occur singly and scattered on the 
volar side of the fore-arm, even in the anthropoid apes. They are oval or 
elliptical bodies, 40-200 ;j. long in.], and 60-70 11 broad to in.], 
and are covered externally by layers of connective-tissue arranged transversely 
in layers, and within is a granular mass with elongated striped nuclei (figs. 748, 
749, e). One to three medullated nerve-fibres pass to the lower end of each 
corpuscle, and surround it in a spiral manner two or three times; the fibres 
then lose their myelin, and, after dividing into 4 to 6 fibrils, branch within the 
corpuscle. The exact mode of termination of the fibrils is not known. Some 
observers suppose that the transverse fibrillation is due to the coils or windings 
of the nerve-fibrils; while according to others, the inner part consists of 
numerous flattened cells ly- 
ing one over the other, be- 
tween which the pale ter- 
minal fibres end either in 
swellings or with disc-like 
expansions, such as occur in 
Merkel’s corpuscles. 
Fig. 748. 
Fig. 749. 
Fig. 748.—Vertical section of the skin of the palm of the hand, a, blood-vessels; b, papilla of 
the cutis vera; c, capillary; d, nerve-fibre passing to a touch-corpuscle; f nerve-fibre 
divided transversely; e, Wagner's touch-corpuscle; g, cells of the Malpighian layer of the 
skin. Fig. 749.—Wagner’s touch-corpuscle from the palm, treated with gold chloride; n, 
nerve-fibres; a, a, groups of glomeruli. 
[These do not contain a soft core such as exists in Pacini’s corpuscles. The corpuscles appear 
to consist of connective-tissue with imperfect septa passing into the interior from the fibrous 
capsule. After the nerve-fibre enters it loses its myelin, and then branches, while the branches 
anastomose and follow a spiral course within the corpuscle, finally to terminate at slight enlarge- 
ments. According to Thin, there are simple and compound corpuscles, depending on the number 
of nerve-fibres entering them.] Sec. 424.] 
TERMINATIONS OF SENSORY NERVES. 
1045 
Kollmann describes three special tactile areas in the hand : (i) The tips of the fingers with 
24 touch-corpuscles in a length of 10 mm.; (2) the three eminences lying on the palm behind 
the slits between the fingers, with 54-2.7 touch-corpuscles in the same length; and (3) the 
ball of the thumb and little finger with 3.1-3.5 touch-corpuscles. The first two areas also con- 
tain many of the corpuscles of Vater or Pacini, while in the latter these corpuscles are fewer and 
scattered. In the other parts of the hand the nervous end-organs are much less developed. 
2. Vater’s (1741) or Pacini’s corpuscles are oval bodies (fig. 750), 
1-2 mm. long, lying in the subcutaneous tissue on the nerves of the fingers 
and toes (600-1400), in the neighborhood of joints and muscles, the sympa- 
thetic abdominal plexuses, near the aorta and coccygeal gland, on the dorsum 
of the penis and clitoris, and in the mesocolon [and mesentery] of the cat. 
[They also occur in the course of the intercostal and periosteal nerves, and 
Stirling has seen them in the capsule of lymphatic glands. They are attached 
to the nerves of the hand and feet, and are so large as to be visible to the 
naked eye, both in these regions and between the layers of the mesentery of 
the cat. They are whitish or somewhat transparent, with a white line in the 
centre (cat); in man, they are y to y inch long, and to inch broad, 
and are attached by a stalk or pedicle (fig. 750, a) to the nerve.] They consist 
of numerous nucleated connective-tissue capsules 
or lamellae lined by endothelium, separated from 
each other by fluid, and lying one within the other 
like the coats of an onion, while in the axis is a 
central core. A medullated nerve-fibre passes 
to each, where its sheath of Schwann unites with 
the capsule. It loses its myelin, and passes into 
the interior as an axial cylinder (fig. 750, <?), 
where it either ends in a small knob or may divide 
dichotomously (fig. 750, /), each branch termi- 
nating in a small pear-shaped enlargement. [Each 
large corpuscle is covered by 40-50 lamellae, or 
tunics, which are thinner and closer to each other 
(fig. 750, el) internally than in the outer part, 
where they are thicker and wider apart. The 
lamellae are like the laminae in the lamellated 
Fig. 750.—Vater’s or Pacini’s corpuscle, a, stalk; b, nerve-fibre entering it; c, d, connective- 
tissue envelope; e, axis-cylinder, with its end divided at f. Fig. 751-—End-bulb from 
human conjunctiva, a, nucleated capsule; b, core; c, fibre entering and branching, ter- 
minating in core at d. Fig. 752.—Tactile corpuscles (clitoris of rabbit). 
Fig. 750. 
Fig- 751- 
Fig. 752. 
sheath of a nerve, and are composed of an elastic basis mixed with white fibres 1046 
[Sec. 424. 
TERMINATIONS OF SENSORY NERVES. 
of connective-tissue, while the inner surface of each lamellae is lined by a single 
continuous layer of endothelium continuous with that of the perineurium. It 
is easily stained with silver nitrate. The efferent nerve-fibre is covered 
with a thick sheath of lamellated connective-tissue (sheath of Henle), which 
becomes blended with the outer lamellae of the corpuscle. The medullated 
nerve is sometimes accompanied by a blood-vessel, and pierces the various 
tunics, retaining its myelin until it reaches the core, where it terminates as 
already described.] 
3. Krause’s end-bulbs very probably occur as a regular mode of nerve- 
termination in the cutis and mucous membranes of all mammals (fig. 751). 
They are elongated, oval, or round bodies, 0.075 t0 °-I4 mm- long, and have 
been found in the deeper layers of the conjunctiva bulbi, floor of the mouth, 
margins of the lips, nasal mucous membrane, epiglottis, fungiform and cir- 
cumvallate papillae, glans penis and clitoris, volar surface of the toes of the 
guinea-pig, ear and body of the mouse, and in the wing of the bat. [In the 
calf the “cylindrical end-bulbs” are oval, with a nerve-fibre terminating 
within them. The sheath of Henle becomes continuous with the nucleated 
capsule, while the axial cylinder, devoid of its myelin, is continued into the 
soft core. In man the end-bulbs are “spheroidal,” and consist of a nucleated 
Fig. 754- 
Tactile corpuscles from the duck’s tongue. 
A, composed of three cells with two 
interposed discs, with axis-cylinder, », 
passing into them. B, two tactile cells 
and one disc. 
Vertical section of the epithelium of the cornea 
nerve endings in the cornea. 
Fig- 753- 
connective-tissue capsule continuous with Henle’s sheath of the nerve, and 
enclosing many cells, amongst which the axis-cylinder which enters the bulb 
branches and terminates.] The spheroidal end-bulbs occur in man, in the 
nasal mucous membrane, conjunctiva, mouth, epiglottis, and the mucous folds 
of the rectum. According to Waldeyer and Longworth, the nerve-fibrils 
terminate in the cells within the capsule. These cells are said to be comparable 
to Merkel’s tactile cells ( Waldeyer). 
The genital corpuscles of Krause, which occur in the skin and mucous 
membrane of the glans penis, clitoris, and vagina, appear to be end-bulbs more 
or less fused together (fig. 752). 
The articulation nerve-corpuscles occur in the synovial mucous mem- 
brane of the joints of the fingers. They are larger than the end-bulbs, and 
have numerous oval nuclei externally, while one to four nerve-fibres enter 
them. 
4. Tactile or touch-corpuscles of Merkel, sometimes also called the 
corpuscles of Grandry, occur in the beak and tongue of the duck and 
goose, in the epidermis of man and mammals, and in the outer root-sheath of 
tactile hairs or feelers (fig. 754). They are small bodies composed of a capsule 
enclosing two, three, or more large, granular, somewhat flattened, nucleated 
and nucleolated cells, piled one on the other in a vertical row, like a row of 
cheeses. Each corpuscle receives at one side a medullated nerve-fibre, which Sec. 424.] 
TERMINATIONS OF SENSORY NERVES. 
1047 
loses its myelin, and branches, to terminate, according to some observers 
(Mer&el), in the cells themselves, and according to others (.Ranvier, Izqui- 
erdo, Hesse), in the protoplasmic transparent substance or disc lying between 
the cells. [This intercellular disc is the “ disc tactil ” of Ranvier, or the 
“Tastplatte" of Hesse.] When there is a great aggregation of these cells, 
large structures are formed, which appear to form a kind of transition between 
these and touch-corpuscles. [According to Klein, the terminal fibrils end neither 
in the touch-cells nor tactile disc, but in minute swellings in the interstitial sub- 
stance between the touch-cells, in a manner very similar to that occurring in 
the end-bulbs.] 
[According to Merkel, tactile cells, either isolated or in groups, but in the latter case never 
forming an independent end-organ, occur in the deeper layers of the epidermis of man and 
mammals and also in the papillae. They consist of round or flask-shaped cells, with the lower 
pointed neck of the flask continuous with the axis-cylinder of a nerve-fibre. They are regarded 
by Merkel as the simplest form of a tactile end-organ, but their existence is doubted by some 
observers.] 
Amongst animals there are many other forms of sensory end-organs. 
[Herbst’s corpuscles occur in the mucous membrane of the tongue of the 
duck, and resemble small Vater’s corpuscles, but their lamellae are thinner and 
nearer each other, while the axis-cylinder within the central core is bordered 
on each side by a row of nuclei.] In the nose of the mole there is a peculiar 
end-organ (Eimer), while there are “end-capsules ” in the penis of the hedge- 
hog and the tongue of the elephant, and “ nerve-rings ” in the ears of the 
mouse. 
5. [Other Modes of Ending of Sensory Nerves.—Some sensory 
nerves terminate not by means of special end-organs, but their axis-cylinder 
splits up into fibrils to form a nervous network, from which fine fibrils 
are given off to terminate in the tissue in 
which the nerve ends. These fibrils, as in 
the cornea (§ 384), terminate by means of 
free ends between the epithelium on the 
anterior surface of the cornea (fig. 753) and 
some observers state that the free ends are 
provided with small enlargements (“boutons terminals”) (fig. 755, a). 
These enlargements or “tactile cells” occur in the nose of the guinea-pig 
and mole. A similar mode of termination occurs between the cells of the 
epidermis in man and mammals (fig. 357.)] 
Fig- 755- 
Bouchon epidermique from the nose of a guinea-pig, 
after the action of gold chloride. n, nerve-fibre; 
a, tactile cells; m, tactile discs; c, epithelial cells. 
Termination of nerve-fibres, (a) in a 
hair-follicle, (r) sebaceous gland. 
Fig- 756- CUTANEOUS SENSATIONS. 
[Sec. 424. 
[6. In Hair-follicles.—A medullated nerve-fibre passes to a hair-follicle 
immediately below the entrance of the duct of the sebaceous gland, where it 
loses its myelin and divides, giving rise to circular and longitudinal fibres. The 
longitudinal fibres, which are always inside the circular fibres, run towards the 
surface of the skin in the folds of the vitreous lamina, and end about the same 
level in flattened expansions, which, however, are best seen in a transverse 
section of a hair-follicle (Ranvier).] 
7. Tendons, especially at their junction with muscles, have special end-organs [Sachs, Rol- 
lett, Golgi), which assume various forms; it may be a network of primitive nerve-fibrils (fig. 
383), or flattened end-flakes or plates in the sterno-radial muscle of the frog, or elongated oval 
end bulbs, not unlike the end-bulbs of the conjunctiva, or small simple Pacinian corpuscles. 
Prus found ganglion cells more frequently in the subcutaneous tissue than in the corium, and 
they appeared to have some relation to the blood-vessels and sweat-glands. 
425. SENSORY AND TACTILE SENSATIONS.—In the sensory 
nerve-trunks there are two functionally different kinds of nerve-fibres: (1) 
Those which administer to painful impressions, which are sensory nerves in the 
narrower sense of the word ; and (2) those which administer to tactile impres- 
sions and may therefore be called tactile nerves. The sensations of temper- 
ature and pressure are also reckoned as belonging to the tactile group. It 
is extremely probable that the sensory and tactile nerves have different end- 
organs and fibres, and that they have also special perceptive nerve-centres in 
the brain, although this is not definitely proved. This view, however, is sup- 
ported by the following facts :— 
1. That sensory and tactile impressions cannot be discharged at the same 
time from all the parts which are endowed with sensibility. Tactile sensations, 
including pressure and temperature, are only discharged from the coverings of 
the skin, the mouth, the entrance to the floor of the nose, the pharynx, the 
lower end of the rectum and genito-urinary orifices; feeble indistinct sensa- 
tions of temperature are felt in the cesophagus. Tactile sensations are absent 
from all internal viscera, as has been proved in man in cases of gastric, intes- 
tinal, and urinary fistulas. Pain alone can be discharged from these organs. 2. 
The conduction channels of the tactile and sensory nerves lie in different parts 
of the spinal cord (§ 364, 1 and 5). This renders probable the assumption 
that their central and peripheral ends also are different. 3. Very probably the 
reflex acts discharged by both kinds of nerve-fibres—the tactile and pathic— 
are controlled, or even inhibited, by special central nerve-organs (§ 361). 4. 
Under pathological conditions, and under the action of narcotics, the one sen- 
sation may be suppressed while the other is retained (§ 364, 5). 
Sensory Stimuli.—In order to discharge a painful impression from sensory 
nerves, relatively strong stimuli are required. The stimuli may be mechanical, 
chemical, electrical, thermal, and somatic, the last being due to inflammation 
or anomalies of nutrition and the like. 
Peripheral Reference of the Sensations.—These nerves are excitable 
along their entire course, and so is their central termination, so that pain may be 
produced by stimulating them in any part of their course, but this pain, according 
to the “law of peripheral perception,” is always referred to the periphery. 
The tactile nerves can only discharge a tactile impression or sensation of 
contact when moderately strong mechanical pressure is exerted, while thermal 
stimuli are required to produce a temperature sensation, and in both cases the 
results are obtained only when the appropriate stimuli are applied to the end- 
organs. If pressure or cold be applied to the course of a nerve-trunk, e.g., to 
the ulna at the inner surface of the elbow-joint, we are conscious of painful 
sensations, but never of those of temperature, referable to the peripheral ter- 
minations of the nerves in the inner fingers. All strong stimuli disturb normal 
tactile sensations by over-stimulation, and hence cause pain. Sec. 425. 
SENSE OF LOCALITY. 
1049 
The law of the specific energy of nerves leads us to assume that the cuta- 
neous nerves contain different kinds of nerve-fibres with different kinds of end- 
organs, which subserve different kinds of impressions, e.g., pressure, tempera- 
ture, and pain. Blix and Goldscheider have found such differences. Electrical 
stimulation causes different sensations according to the part of the skin where 
it is applied; at one spot, pain only is produced, at another a sensation of cold, 
at a third a sensation of heat, and at a fourth a sensation of pressure. At every 
temperature point or spot, there is insensibility for pain or pressure. The 
“ pressure-points ” or pressure-spots lie much closer together, and are more 
numerous than the temperature-points. There are special “pain-spots” 
and even “tickling-spots.” These spots are arranged in a linear chain, 
which usually radiates from the hair-follicles. The “tickling-spots ” coincide 
with the pressure and pain-spots. The feeling of, tickling corresponds to the 
feeblest stimulation of a nerve-fibre, and pain to the strongest. The pain-spots 
can be isolated by means of a needle, or electrically, especially in the cutaneous 
furrows, in which the pressure-sense is absent. 
Goldscheider removed from his own body small pieces of skin, in which he had previously 
ascertained the presence of these “ spots,” and then investigated the excised skin microscopic- 
ally. At each such spot he found a rich supply of nerves; at the pressure spots, there were no 
touch-corpuscles. 
[By means of the skin, impressions are supplied also to the brain, whereby we become con- 
scious of the amount and direction of a body moved in contact with the skin. Indeed, the dis- 
criminative sensibility is more acute for motion than for touch ; but the liability to error in judging 
of the distance and direction is great {Hall).'] 
[Very complex sensations are obtained by means of the combined action of the skin and 
muscles, e.g., those known as “ feelings of double contact.” These sensations are of the 
greatest advantage in acquiring the use of instruments and tools. If we touch an object with a 
rod, we seem to feel the object at the point of the rod, and not in the hand where the cutaneous 
nerves are actually stimulated. With a walking-stick, we feel the ground at the end of the stick. 
Touch the tips of the hair, or a tooth, and the sensation is referred to the tips of the hair in the 
one case, and the crown of the tooth in the other (Ladd).] 
426. SENSE OF LOCALITY. —We are not only able to distinguish 
differences of pressure or temperature by our sensory nerves, but we are able to 
distinguish the part which has been touched. This capacity is spoken of as the 
sense of space and locality. 
Methods of Testing.—1. Place the two blunted points of a pair of compasses (fig. 757) 
upon the part of the skin to be investigated, and determine the smallest distance at which the 
two points are felt only as one impression. Sieveking’s aesthesiometer 
may be used instead (fig. 758); one of the points is movable along a 
graduated rod, while the other is fixed. 2. The distance between the 
points of the instrument being kept the same, touch several parts of the 
skin, and ask if the person feels the impression of the points coming 
nearer to or going wider apart. 3. Touch a part of the skin with a blunt 
instrument, and observe if the spot touched is correctly indicated by the 
patient. 4. Separate the points of two pairs of compasses unequally, and 
place their points upon different parts of the skin, and ask the person to 
state when the points of both appear to be equally apart. A distance of 4 
lines on the forehead appears to be equal to a distance of 2.4 lines on the 
upper lip. This is Fechner’s ‘‘method of equivalents.” 
The following results have been obtained. The sense of 
locality of a part of the skin is more acute under the follow- 
ing conditions :— 
1. The greater the number of tactile nerves in the corre- 
sponding part of the skin. 
2. The greater the mobility of the part, so that it increases 
in the extremities towards the fingers and toes. The sense 
of locality is always very acute in parts of the body that are very rapidly moved 
( Vierordt). 
F'g- 757- 
/Esthesiometer. SENSE OF LOCALITY. 
[Sec. 426. 
1050 
3. The sensibility of the limbs is finer in the transverse axis than in the long 
axis of the limb, to the extent of yith on the flexor surface of the upper limb, 
and on the extensor surface. 
4. The mode of application of the points of the aesthesiometer : {a) Accord- 
ing as they are applied one after the other, instead of simultaneously, or as they 
are considerably warmer or colder than the skin {Klug), a person may dis- 
tinguish a less distance between the points, {b) If we begin with the points 
wide apart and approximate them, then we can distinguish a less distance than 
when we proceed from imperceptible distances to larger ones, {c) If the 
one point is warm and the other cold, on exceeding the next distance we 
feel two impressions, but we cannot rightly judge of their relative positions 
{Czermak). 
5. Exercise greatly improves the sense of locality ; hence the extraordinary 
acuteness of this sense in the blind, and the improvement always occurs on both 
sides of the body {Volkmann). 
[Fr. Galton finds that the reputed increased acuteness of the other senses in the case of the 
blind is not so great as is generally alleged. He tested a large number of boys at an educational 
blind asylum, with the result that the performances of the blind boys were by no means superior 
TLsthesiometer of Sieveking. 
Fig- 758. 
to those of other boys. He points out, however, that “ the guidance of the blind depends 
mainly on the multitude of collateral indications, to which they give much heed, and not in their 
superiority in any one of them.”] 
6. Moistening the skin with indifferent fluids increases the acuteness. If, how- 
ever, the skin between two points, which are still felt as two distinct objects, be 
slightly tickled, or be traversed by an imperceptible electrical current, the im- 
pressions become fused (Suslowa). The sense of locality is rendered more 
acute at the cathode when a constant current is used {Suslowa), and when the 
skin is congested by stimulation {Klinkenberg), and also by slight stretching of 
the skin {Schmey) ; further, by baths of carbonic acid {v. Basch and v. Diet/), 
or warm common salt, and temporarily by the use of caffein {Bump/). 
7. Ancemia, produced by elevating the limbs, or venous hypereemia (by com- 
pressing the veins), blunts the sense, and so does too frequent testing of the 
sense of locality, by producing fatigue. The sense is also blunted by cold 
applied to the skin, the influence of the anode, strong stretching of the skin, 
as over the abdomen during pregnancy, previous exertion of the muscles under 
the part of the skin tested, and some poisons, e.g., atropin, daturin, morphin, 
strychnin, alcohol, potassium bromide, cannabin, and chloral hydrate. Sec. 426 ] 
CUTANEOUS SENSATIONS. 
1051 
Smallest Appreciable Distance.—The following statement gives the 
smallest distance, in millimetres, at which two points of a pair of compasses can 
still be distinguished as double by an adult. The corresponding numbers for 
a boy twelve years of age are given within brackets. 
Millimetres. 
Tip of tongue, 1.1 [X.i] 
Third phalanx of finger, volar 
surface, 2.-2.3 [1.7] 
Red part of the lip, 4.5 [3.9] 
Second phalanx of finger, volar 
surface, 4--4-S [3-9] 
First phalanx of finger, volar 
surface, 5~5-5 
Third phalanx of finger, dorsal 
surface, 6.8 [4.5] 
Tip of nose, 6.8 [4.5] 
Head of metacarpal bone volar, 5.-6.8 [4.5J 
Ball of thumb, 6.5-7. 
Ball of little finger, 5.5-6. 
Centre of palm, 8. -9. 
Dorsum and side of tongue, 
white of the lips, metacarpal 
part of the thumb, 9. [6.8] 
Third phalanx of the great toe, 
plantar surface, 11.3 [6.8] 
Second phalanx of the fingers, 
dorsal surface, 11.3 [9.] 
Back, 11.3 [9.] 
Eyelid, 
Millimetres. 
11 -3 [9-] 
Centre of hard plate, 
13-5 
[ii-3] 
Lower third of the fore-arm, 
volar surface, 
In front of the zygoma, .... 
Plantar surface of the great toe, 
i5- 
15-8 
[11.3] 
15.8 
Q.] 
Inner surface of the lip, . 
20.3 
[13-5] 
Behind the zygoma, 
22.6 
[15.8] 
Forehead, 
22.6 
18.] 
Occiput, 
27.1 
22.6] 
Back of the hand, 
31.6 
'22.6] 
Under the chin, 
33-8 
’22.6] 
Vertex, 
33-8 
'22.6] 
Knee, 
36.1 
>•6] 
Sacrum, gluteal region, .... 
44.6 
■33.8] 
Fore-arm and leg, 
45-i 
33-8] 
Neck, 
54-i 
36.1] 
Back at the fifth dorsal vertebra, 
lower dorsal and lumbar region, 54.1 
Middle of the neck, 67.7 
Upper arm, thigh, and centre of 
the back 67.7 [31.6-40.6] 
Illusions of the sense of locality occur very frequently; the most marked are: (i) A 
uniform movement over a cutaneous surface appears to be quicker in those places which have the 
finest sense of locality. (2) If we merely touch the 
skin with the two points of an sesthesiometer, then 
they feel as if they were wider apart than when the 
two points are moved along the skin (Fechner). (3) 
A sphere, when touched with short rods, feels larger 
than when long rods are used (Tourtual). (4) When 
the fingers of one hand are crossed, a small pebble or 
sphere placed between them feels double (Aristotle’s 
experiment). [When a pebble is rolled between 
the crossed index and middle finger (fig. 759, B), it 
feels as if two balls were present, but with the fingers 
uncrossed single.] (5) When pieces of skin are trans- 
planted, e.g., from the forehead, to form a nose, the 
person operated on feels, often for a long time, the 
new nasal part as if it were his forehead. 
Theoretical.—Numerous experiments were made 
by E. H. Weber, Lotze, Meissner, Czermak, and others 
to explain the phenomena of the sense of space. 
Weber’s theory goes upon the assumption, that one 
and the same nerve-fibre proceeding from the brain to 
the skin can only take up one kind of impression, and 
administer thereto. He called the part of the skin to 
which each single nerve-fibre is distributed a “ circle of sensation.” When two stimuli act 
simultaneously upon the tactile end-organ, then a double sensation is felt, when one or more 
circles of sensation lie between the two points stimulated. This explanation, based upon ana- 
tomical considerations, does not explain how it is that, with practice, the circles of sensation 
become smaller, and also how it is that only one sensation occurs, when both points of the 
instruments are so applied, that both points, although further apart than the diameter of a circle 
of sensation, at one time lie upon two adjoining circles, at another between two others with 
another circle intercalated between them. 
Wundt’s Theory.—In accordance with the conclusions of Lotze, Wundt proceeds from a 
A 
B 
Aristotle’s experiment. 
F'g- 759- 1052 
PRESSURE SENSE. 
[Sec. 426. 
psycho-physiological basis, that every part of the skin with tactile sensibility always conveys to 
the brain the locality of the sensation. Every cutaneous 
area, therefore, gives to the tactile sensation a “ local 
color ” or quality, which is spoken of as the local sign. 
He assumes that this local color diminishes from point 
to point of the skin. This gradation is very sudden in 
those parts of the skin where the sense of space is very 
acute, but occurs very gradually where the sense of 
space is more obtuse. Separate impressions unite into 
a common one, as soon as the gradation of the local 
color becomes imperceptible. By practice and attention 
differences of sensation are experienced, which ordi- 
narily are not observed, so that he explains the diminu- 
tion of the circles of sensation by practice. The circle 
of sensation is an area of the skin, within which the 
local color of the sensation changes so little that two separate impressions fuse into one. 
427. PRESSURE SENSE.—By the sense of pressure we obtain a 
knowledge of the amount of weight or pressure which is being exercised at the 
time on the different parts of the skin. 
A specific end-apparatus arranged in a punctiform manner is connected with 
the pressure sense {fig. 760). These points or spots are called “ pressure - 
spots” or “ pressure-points” (Blix), and are endowed with varying degrees 
of sensibility ; at some places (back, thigh) they are distinguished by a markedly 
pronounced after-sensation. The arrangement of the pressure-spots follows 
the type of the arrangement of the temperature-spots. The pressure-spots have 
usually another direction than that of hot and cold spots ; as a rule, they are 
denser. The minimal distance at which two pressure-spots, when simulta- 
neously stimulated, are felt as double, is—on the back, 4 to 6 mm.; breast, 
0.8 ; abdomen, 1.5 to 2 ; cheek, 0.4 to 0.6 ; upper arm, 0.6 to 0.8 ; fore-arm, 
0.5 ; back of the hand, 0.3 to 0.6; palm, o. 1 to 0.5 ; leg, 0.8 to 2; back of 
foot, 0.8 to 1 ; sole of foot, 0.8 to 1 mm. * 
Methods.—1. Place, on the part of the skin to be investigated, different weights, one after 
the other, and ascertain what perceptions they give rise to, and the sense of the difference of 
pressure to which they give rise. We must be careful to exclude differences of temperature and 
prevent the displacement of the weights—the weights must always be placed on the same spot, 
and the skin should be covered beforehand with a disc, while the muscular sense must be 
eliminated (§ 430). [This is done by supporting the hand or part of the skin which is being 
tested, so that the action of all the muscles is excluded.] 2. A process is attached to a balance 
and made to touch the skin, while by placing weights in the scale-pan or removing them, we 
test what differences in weight the person experimented on is able to distinguish (Dohrn). 3. 
In order to avoid the necessity of changing the weights, A. Eulenburg invented his baraes- 
thesiometer, which is constructed on the same principle as a spiral spring paper-clip or balance. 
There is a small button which rests on the skin and is depressed by the spring. An index 
shows at once the pressure in grams, and the instrument is so arranged that the pressure 
can be very easily varied. 4. Goltz uses a pulsating elastic tube, in which he can produce 
waves of different height. He tested how high the latter must be before they are experienced 
as pulse-waves, when the tube is placed upon the skin. In estimating both the pressure sense 
and temperature sense, it is best to proceed on the principle of “the least perceptible 
difference, i. e., the different pressures or temperatures are graduated, either beginning with 
great differences, or proceeding from the smallest difference, and determining the limit at which 
the person can distinguish a difference in the sensation. 
Results.—1. The smallest perceptible pressure, when applied to different parts 
of the skin, varies very greatly according to the locality. The greatest acuteness 
of sensibility is on the forehead, temples, and the back of the hand and fore- 
arm, which perceive a pressure of 0.002 grm. ; the fingers first feel with a weight 
of 0.005 t0 0.015 grm- } chin, abdomen, and nose with 0.04 to 0.05 grm.; 
the finger nail 1 grm. (Kammler and Aubert). 
The greater the sensibility of the skin, the more rapidly can stimuli succeed each other, and 
Pressure-spots, a, middle of the sole 
of the loot; b, skin of zygoma; c, 
skin of the back. 
Fig. 760. Sec. 427.] 
TEMPERATURE SENSE. 
1053 
still be perceived as single impressions ; 52 stimuli per second may be applied to the volar side 
of the upper arm, 61 on the back of the hand, 70 to the tips of the fingers, and still be felt 
singly (Bloch). 
2. Intermittent variations of pressure, as in Goltz’s tube, are felt more 
acutely by the tips of the fingers than with the forehead. 
3. Differences between two weights are perceived by the tips of the fingers 
when the ratio is 29 : 30 (in the fore-arm as 18.2 : 20), provided the weights 
are not too light or too heavy. In passing from the use of very light to heavy 
weights, the acuteness or fineness of the perception of difference increases at 
once, but with heavier weights, the power of distinguishing differences rapidly 
diminishes again Hering, Biedermanri). This observation is at variance 
with the psycho-physical law of Fechner (§ 383). 
4. A. Eulenburg found the following gradations in the fineness of the pres- 
sure sense : The forehead, lips, dorsum of the cheeks, and temples appreciate 
differences of to (200 : 205 to 300 : 310 grm.). The dorsal surface of the 
last phalanx of the fingers, the fore-arm, hand, ist and 2d phalanx, the volar 
surface of the hand, fore-arm, and upper arm, distinguish differences of to 
(200 : 220 to 220 : 210 grm.). The anterior surface of the leg and thigh are 
similar to the fore-arm. Then follow the dorsum of the foot and toes, the 
sole of the foot, and the posterior surface of the leg and thigh. Dohrn deter- 
mined the smallest additional weight, which, when added to 1 grm. already 
resting on the skin, was appreciated as a difference, and he found that for the 
3d phalanx of the finger it was 0.499 grm.; back of the foot, 0.5 grm. ; 2d 
phalanx, 0.771 grm. ; ist phalanx, 0.02 grm. ; leg, 1 grm.; back of the hand, 
1.156 grm.; palm, x.018 grm.; patella, 1.5 grm.; fore-arm, 1.99 grm.; umbil- 
icus, 3.5 grms.; and the back, 3.8 grms. The small fine hairs of the skin are 
especially sensitive to pressure (Blaschko). 
5. Too long time must not elapse between the application of two successive 
weights, but 100 seconds may elapse when the difference between the weights 
is 4 : 5 (E. H. Weber). 
6. The sensation of an after-pressure is very marked, especially if the 
weight is considerable and has been applied for a length of time. But even 
light weights, when applied, must be separated by an interval of at least to 
g-fg- second, in order to be perceived. When they are applied at shorter inter- 
vals, the sensations become fused. When Valentin pressed the tips of his 
fingers against a wheel provided with blunt teeth he felt the impression of a 
smooth margin, when the teeth were applied to the skin at the intervals above 
mentioned; when the wheel was rotated more slowly, each tooth gave rise to a 
distinct impression. Vibrations of strings are distinguished as such when the 
number of vibrations is 1506 to 1552 per second (v. Wittich and Griinhagen). 
7. It is remarkable that pressure produced by the uniform compression of a 
part of the body, e. g., by dipping a finger or arm in mercury, is not felt as such ; 
the sensation is felt only at the limit of the fluid, on the volar surface of the 
finger, at the limit of the surface of the mercury. 
428. TEMPERATURE SENSE.—The temperature sense makes us 
acquainted with the variations of the heat of the skin. 
A specific end-apparatus arranged in a punctiform manner is connected with 
the temperature sense. 
These “ temperature spots ” are arranged in a linear manner or in chains, 
which are usually slightly curved (figs. 761, 762, 763). They generally radi- 
ate from certain points of the skin, usually the hair-roots. The chain of the 
“ cold-spots” usually does not coincide with those of the “ hot-spots,” 
although the point from which they radiate may be the same. Frequently, 
these punctuated lines are not complete, but they may be indicated by scattered 1054 
TEMPERATURE SENSE. 
[Sec. 428. 
points, between which, not unfrequently, points or spots for other qualities of 
sensation may be intercalated. Near the hairs there are almost always temper- 
ature-spots. In parts of the skin, where the temperature sensibility is slight, 
the temperature-points are present only near the hairs. 
The sensation of cold occurs at once, while the sensation of heat develops 
gradually. Mechanical and electrical stimulation also excite the sensation of 
temperature. A gentle touch of the temperature-spots is not perceived ; these 
points seem to be anaesthetic towards pressure and pain. As a general rule, 
the cold-spots are more abundant over the whole body—there are more of them 
in a given area—while the hot-spots may be quite absent. The hot-spots are, 
as a rule, perceived as double at a greater distance apart than the cold-spots. 
The minimal distance on the forehead is 0.8 mm. for the cold-spots and 4 to 5 
mm. for the warm-spots ; on the breast the corresponding numbers are 2 and 4 
to 5 ; back, 1.5 to 2 and 4 to 6 ; back of hand, 2 to 3 and 3 to 4; palm, 0.8 to 
2 ; thigh and leg, 2 to 3 and 3 to 4 mm. 
To test the hot- and cold-spots, use a hot or cold metallic rod ; at the cold- 
spots when they are lightly touched, only the sensation of cold will be felt, and 
a corresponding effect with a hot rod at the hot-spots. Both spots are insensible 
to objects of the same temperature as the skin. 
C.P 
W.P. 
C.P. 
W.P. 
A 
B 
c 
D 
Fig. 761.—A, cold-spots, B, hot-spots, from the volar surface of the terminal phalanx of the 
index-finger to the margins of the nail. Fig. 762.—C, cold-spots, and D, warm-spots of 
the radial half of the dorsal surface of the wrist. The arrow indicates the direction in 
which the hair points. 
Fig. 761. 
Fig. 762. 
According to E. Hering, what determines the sensation of temperature is 
the temperature of the thermic end-apparatus itself, i. e., its zero-temperature. 
As often as the temperature of a cutaneous area is above its zero-tempera- 
ture, we feel it as warm; in the opposite case, cold. The one or the other sen- 
sation is more marked, the more the one or other temperature varies from the 
zero-temperature. The zero-temperature can undergo changes within consider- 
able limits, owing to external conditions. 
Methods of Testing.—To the surface of the skin objects of the same size and with the same 
thermal conductivity are applied successively at different temperatures: 1. Nothnagel uses small 
wooden cups with a metallic base, and filled with warm and cold water, the temperature being 
registered by a thermometer placed in the cups. [2. Clinically, two test-tubes filled with cold 
and warm water, or two spoons, the one hot and the other cold, may be used.] 
Results.—1. As a general rule, the feeling of cold is produced when a body 
applied to the skin robs it of heat; and, conversely, we have a sensation of 
warmth when heat is communicated to the skin. 
2. The greater the thermal conductivity of the substance touching the skin, 
the more intense is the feeling of heat or cold (§ 218). 
3. At a temperature of i5-5°-35° C., we distinguish distinctly differences of Sec. 428.] 
TEMPERATURE SENSE. 
1055 
temperature of o.2°-o. 160 R. with the tips of the fingers (E. H. Weber). 
Temperatures just below that of the blood (33°-27° C.—Nothnagel) are distin- 
guished most distinctly by the most sensitive parts, even to differences of 0.05° 
C. (.Lindermann). Differences of temperature are less easily made out when 
dealing with temperatures of 33°-39°, as well as between i4°-27° C. A tem- 
perature of 550 C., and also one a few degrees above zero (2.8° C.), cause dis- 
tinct pain in addition to the sensation of temperature. 
4. The sensibility for cold is generally greater than for warmth,—that of the 
left hand is greater than the right (Goldscheider). The different parts of the 
skin also vary in the acuteness of their thermal sense, and in the following 
order: Tip of the tongue, eyelids, cheeks, lips, neck, and body. The percep- 
tible minimum Nothnagel found to be o. 40 on the breast; 0.90 on the back ; 
0.30 back of the hand; o.40 palm; o.20 arm; 0.40 back of the foot; 0.50 
thigh; o.6° leg'; o.4°-o. 20 cheek; o.4°-o.3° C. temple. The thermal sense 
Cold- and hot-spots from the same part of the anterior surface of the fore-arm. a, cold-spots; 
b, hot-spots. The dark parts are the most sensitive, the hatched the medium, the dotted the 
feeble, and the vacant spaces the non-sensitive. 
Fig- 763- 
is less acute in the middle line, e. g., the nose, than on each side of it (£. H. 
Weber). Fig. 763 shows that in one and the same portion of skin, the cold- 
and hot-spots are differently located, i. e., their different topography. 
If the mucous membrane of the mouth be pencilled with a 10 per cent, solution of cocain, 
the sensibility for heat is abolished; the cooling sensation of menthol depends upon its stimula- 
tion of the cold nerves; C02 applied to the skin excites the heat-nerves (Goldscheider). 
5. Differences of temperature are most easily perceived when the same part 
of the skin is affected successively by objects of different temperature. If, 
however, two different temperatures act simultaneously and side by side, the 
impressions are apt to become fused, especially when the two areas are very 
near each other. 
6. Practice improves the temperature sense; congestion of venous blood in 
the skin diminishes it; diminution of the amount of blood in the skin improves 
it (M. Alsberg). When large areas of the skin are touched, the perception of 
differences is more acute than with small areas. Rapid variations of the tem- 1056 
COMMON SENSATION AND PAIN. 
[Sec. 428. 
perature produce more intense sensations than gradual changes of temperature. 
Fatigue occurs soon. 
Illusions are very common: I. The sensations of heat and cold sometimes alternate in a 
paradoxical manner. When the skin is dipped first into water at io° C. we feel cold, and if it 
be then dipped at once into water at i6° C., we have at first a feeling of warmth, but soon again 
of cold. 2. The same temperature applied to a large surface of the skin is estimated to be greater 
than when it is applied to a small area, e. g., the whole hand when placed in water at 29.50 C. 
feels warmer than when a finger is dipped into water at 320 C. 3. Cold weights are judged to 
be heavier than warm ones. 
Pathological.—Tactile sensibility is only seldom increased (hyperpselaphesia), but great 
sensibility to differences of temperature is manifested by areas of the skin whose epidermis is 
partly removed or altered by vesicants or herpes zoster, and the same occurs in some cases of 
locomotor ataxia; while the sense of locality is rendered more acute in the two former cases and 
in erysipelas. An abnormal condition of the sense of locality was described by Brown-Sequard, 
where three points were felt when only two were applied, and two when one was applied to the 
skin. Landois finds that in himself pricking the skin of the sternum over the angle of Ludo- 
vicus is always accompanied by a sensation in the knee. [Some persons, when cold water is 
applied to the scalp, have a sensation referable to the skin of the loins (Stirling).] A remark- 
able variation of the sense of locality occurs in moderate poisoning with morphia, where the 
person feels himself abnormally large or greatly diminished. In degeneration of the posterior 
columns of the cord, Obersteiner observed that the patient was unable to say whether his right or 
left side was touched (“ allochiria ”). Ferrier observed a case where a stimulus applied to the 
right side was referred to the left, and vice versa. # 
Diminution and paralysis of the tactile sense (Hypopselaphesia and Apselaphesia) 
occur either in conjunction with simultaneous injury to the sensory nerves, or alone. It is rare to 
find that one of the qualities of the tactile sense is lost, e.g., either the tactile sense or the sense of 
temperature—a condition which has been called “partial tactile paralysis." Limbs which are 
“ sleeping" feel heat and not cold (Herzen). 
429. COMMON SENSATION—PAIN.—By the term common 
sensation we understand pleasant or unpleasant sensations in those parts of 
our bodies which are endowed with sensibility, and which are not referable to 
external objects, and whose characters are difficult to describe, and cannot be 
compared with other sensations. Each sensation is, as it were, a peculiar one. 
To this belong pain, hunger, thirst, malaise, fatigue, horror, vertigo, tickling, 
well-being, illness, the respiratory feeling of free or impeded breathing. 
Pain may occur wherever sensory nerves are distributed, and it is invariably 
caused by a stronger stimulus than normal being applied to sensory nerves. 
Every kind of stimulation, mechanical, thermal, chemical, electrical as well as 
somatic (inflammation or disturbances of nutrition), may excite pain. The 
last appears to be especially active, as many tissues become extremely painful 
during inflammation (e. g., muscles and bones), while they are comparatively 
insensible to cutting. Pain may be produced by stimulating a sensory nerve 
in any part of its course, from its centre to the periphery, but the sensation is 
invariably referred to the peripheral end of the nerve. This is the law of 
the peripheral reference of sensations. Hence, stimulation of a nerve, 
as in the scar of an amputated limb, may give rise to a sensation of pain which 
is referred to the parts already removed. Too violent stimulation of a sensory 
nerve in its course may render it incapable of conducting impressions, so that 
peripheral impressions are no longer perceived. If a sufficient stimulus to 
produce pain be then applied to the central part of the nerve, such an impres- 
sion is still referred to the peripheral end of the nerve. Thus we explain the 
paradoxical anaesthesia dolorosa. In connection with painful impressions, 
the patient is often unable to localize them exactly. This is most easily done 
when a small injury (prick of a needle) is made on a peripheral part. When, 
however, the stimulation occurs in the course of the nerve, or in the centre, or 
in nerves whose peripheral ends are not accessible, as in the intestines, pain (as 
belly-ache), which cannot easily be localized, is the result. 
Irradiation of Pain.—During violent pain there is not unfrequently Sec. 429.] 
MUSCULAR SENSE. 
1057 
irradiation of the pain (§ 364, 5), whereby localization is impossible. It is rare 
for pain to remain continuous and uniform; more generally there are exacer- 
bations and diminutions of the intensity, and sometimes periodic intensification, 
as in some neuralgias. 
The intensity of the pain depends especially upon the excitability of the 
sensory nerves. There are considerable individual variations in this respect, 
some nerves, e. g., the trigeminus and splanchnic, being very sensitive. The 
larger the number of fibres affected the more severe the pain. The duration is 
also of importance, in as far as the same stimulation, when long continued, 
may become unbearable. We speak of piercing, cutting, boring, burning, 
throbbing, pressing, gnawing, dull, and other kinds of pain, but we are quite 
unacquainted with the conditions on which such different sensations depend. 
Painful impressions are abolished by anaesthetics and narcotics, such as 
ether, chloroform, morphia, etc. (§ 364, 5). 
Methods of Testing.—To test the cutaneous sensibility, we usually employ the constant or 
induced electrical current. Determine first the minimum sensibility, i. e., the strength of the 
current which excites the first trace of sensation, and also the minimum of pain, i. e., the 
feeblest strength of the current which first causes distinct impressions of pain. The electrodes 
consist of thin metallic needles, and are placed 1 to 2 cm. apart. 
Pathological.—When the excitability of the nerves which administer to painful sensations is 
increased, a slight touch of the skin, nay, even a breath of cold air, may excite the most violent 
pain, constituting cutaneous hyperalgia, especially in inflammatory or exanthematic conditions 
of the skin. The term cutaneous paralgia is applied to certain anomalous, disagreeable, or 
painful sensations which are frequently referred to the skin—itching, creeping, formication, 
cold, and burning. In cerebro-spinal meningitis, sometimes a prick in the sole of the foot pro- 
duces a double sensation of pain and a double reflex contraction. Perhaps this condition may 
be explained by supposing that in a part of the nerve the condition is delayed (g 337, 2). In 
neuralgia there is severe pain, occurring in paroxysms, with violent exacerbations and pain 
shooting into other parts (p. 753). Very frequently excessive pain is produced by pressure on 
the nerve where it makes its exit from a foramen or traverses a fascia. 
Valleix’s Points Douloureux (1841).—The skin itself to which the sensory nerve runs, 
especially at first, may be very sensitive ; and when the neuralgia is of long duration the sensi- 
bility may be diminished even to the condition of analgesia ( Turck) ; in the latter case there 
may be pronounced anaesthesia dolorosa (p. 1056). 
Diminution or paralysis of the sense of pain (hypalgia and analgia) may be due to affec- 
tions of the ends of the nerves, or of their course, or central terminations. 
Metalloscopy.—In hysterical patients suffering from hemianaesthesia, it is found that the 
feeling of the paralyzed side is restored, when small metallic plates or larger pieces of different 
metals are applied to the affected parts (Burcq, Charcot). At the same time that the affected 
part recovers its sensibility the opposite limb or side becomes anaesthetic. This condition has 
been spoken of as transference of sensibility. The phenomenon is not due to galvanic currents 
developed by the metals; but it may be, perhaps, explained by the fact that, under physio- 
logical conditions, and in a healthy person, every increase of the sensibility on one side of 
the body, produced by the application of warm metallic plates or bandages, is followed by a 
diminution of the sensibility of the opposite side. Conversely, it is found that when one side 
of the body is rendered less sensitive by the application of cold plates, the homologous part of 
the other side becomes more sensitive (Rumpf). 
430. MUSCULAR SENSE.—Muscular Sensibility.—The sensory 
nerves of the muscles (§ 292) always convey to us impressions as to the activity 
or non-activity of these organs, and in the former case, these impressions 
enable us to judge of the degree of contraction. It also informs us of the 
amount of the contraction to be employed to overcome resistance. Obviously, 
the muscular sense must be largely supported and aided by the sense of pres- 
sure, and conversely. E. H. Weber showed, however, that the muscle sense is 
finer than the pressure sense, as by it we can distinguish weights in the ratio of 
39 : 40, while the pressure sense only enables us to distinguish those in the 
ratio of 29 : 30. In some cases there has been observed total cutaneous in- 
sensibility, while the muscular sense was retained completely. A frog deprived 
of its skin can spring without any apparent disturbance. The muscular sense 1058 
MUSCULAR SENSE. 
[Sec. 430. 
is also greatly aided by the sensibility of the joints, bones, and fasciae. Many 
muscles, e. g., those of respiration, have only slight muscular sensibility, while 
it seems to be absent normally in the heart and non-striped muscle. 
[The muscular sense stands midway between special and common sensations, 
and by it we obtain a knowledge of the condition of our muscles, and to what 
extent they are contracted; also the position of the various parts of our bodies 
and the resistance offered by external objects. Thus, sensations accompanying 
muscular movement are two-fold—(a) the movements in the unopposed mus- 
cles, as the movements of the limbs in space; and (b) those of resistance where 
there is opposition to the movement, as in lifting a weight. In the latter case 
the sensations due to innervation are important, and of course in such cases we 
have also to take into account the sensations obtained from mere pressure upon 
the skin. Our sensations derived from muscular movements depend on the 
direction and duration of the movements. On the sensations thus conveyed to 
the sensorium, we form judgments as to the direction of a point in space, as 
well as of the distance between two points in space. This is very marked in 
the case of the ocular muscles. It is also evident that the muscular sense is 
intimately related to, and often combined with, the exercise of the sensation 
of touch and sight (Sullyij\ 
Methods of Testing.—Weights are wrapped in a towel and suspended to the part to be 
tested. The patient estimates the weight by raising and lowering it. The electro-muscular 
sensibility also may be proved thus : cause the muscles to contract by means of induction shocks, 
and observe the sensation thereby produced. [Direct the patient to place his feet together while 
standing, and then close his eyes. A healthy person can stand quite steady, but in one with the 
muscular sense impaired, as in locomotor ataxia, the patient may move to and fro, or even fall 
($ 346, 3)- Again, a person with his muscular sense impaired may not be able to touch accu- 
rately and at once some part of his body, when his eyes are closed.] 
A healthy person perceives a weight of I gram applied to his upper arm ; when a weight of 
15 grms. is applied, he perceives an addition of 1 gram. If the original weight be 50 grms., he 
will detect the addition of 2 grms; if the original weight be 100 grms., he will detect 3 grms. 
The weight detectable by the individual finger varies. With the leg, when the weight is applied 
at the knee, the individual may detect 30 to 40 grms.; but sometimes only a greater weight. 
Often one can detect a difference of 10 to 20, or 30 to 70 grms. 
Section of a sensory nerve causes disturbance of the fine graduation of move- 
ment (p. 776). Meynert supposes that the cerebral centre for muscular sensi- 
bility lies in the motor cortical centres, the muscles being connected by motor 
and sensory paths with the ganglionic cells in these centres. 
Too severe muscular exercise causes the sensation of fatigue, oppression, and 
weight in the limbs (§ 304). 
Illusions of the Muscular Sense.—A weight held by one limb appears to us to become 
lighter as soon as we contract other muscles of the limb, which, however, are not required to act 
in supporting the weight (Charpentier). If the tip of the tongue be pressed against a gap in the 
dental arch and then be moved to and fro, one has a feeling as if the teeth move with the move- 
ments of the tongue. 
Pathological. — Abnormal increase of the muscular sense is rare {niuscular hyperalgia and 
hyperesthesia), as in anxietas tibiaruni, a painful condition of unrest which leads to a continual 
change in the position of the limbs. In cramp there is intense pain, due to stimulation of the 
sensory nerves of the muscle, and the same is the case in inflammation. Diminution of the 
muscular sensibility occurs in some choreic and ataxic persons (§ 364, 5). In locomotor ataxia 
the muscular sense of the upper extremities may be normal or weakened, while it is usually con- 
siderably diminished in the legs. [The muscular sense is said to be increased in the hypnotic 
condition and in somnambulists.] Reproduction and Development. 
43i- FORMS OF REPRODUCTION.—I. Abiogenesis (Generatio 
sequivoca, sive spontanea, spontaneous generation).—It was formerly- 
assumed that, under certain circumstances, non-living matter derived from the 
decomposition of organic materials became changed spontaneously into living 
beings. While Aristotle ascribed this mode of origin to insects, the recent 
observers who advocate this form of generation restrict its action solely to the 
lowest organisms. Experimental evidence is distinctly against spontaneous 
generation. If organized matter be heated to a very high temperature in sealed 
tubes, and be thus deprived of all living organisms or their spores, there is no 
generation of any organism. Hence, the dictum “ Omne vivum ex ovo ” 
(.Harvey, or, ex vivo). Some highly organized invertebrate animals (Gordius, 
Anguillula, Tardigrada, and Rotatoria) may be dried, and even heated to 140° 
C., and yet regain their vital activities on being moistened (Anabiosis). 
II. Division or fission occurs in many protozoa (amoeba, infusoria). The organism, just as 
is the case with cells, divides, the nucleus when present taking an active part in the process, so 
that two nuclei and two masses of protoplasm forming two organisms are produced. The 
Ophidiasters amongst the echinoderms divide spontaneously, and they are said to throw off an 
arm which may develop into a complete animal. According to Trembley (1744), the hydra may 
be divided into pieces, and each piece gives rise to a new individual [although under normal 
circumstances the hydra gives off buds, and is provided with generative organs]. 
III. Budding or gemmation occurs in a well-marked form among the polyps and in some 
infusorians (Vorticella). A bud is given off by the parent, and gradually comes more and more 
to resemble the latter. The bud either remains permanently attached to the parent, so that a 
complex organism is produced, in which the digestive organs communicate with each other 
directly, or in some cases there may be a “ colony” with a common nervous system, such as the 
polyzoa. In some composite animals (siphonophora) the different polyps perform different func- 
tions. Some have a digestive, others a motor, and a third a generative function, so that there is a 
physiological division of labor. Buds which are given off from the parent are formed internally 
in the rhizopoda. In some animals (polyps, infusoria), which can reproduce themselves by buds 
or division, there is also the formation of male and female elements of generation, so that they 
have a sexual and a non-sexual mode of reproduction. 
IV. Conjugation is a form of reproduction which leads up to the sexual form. It occurs in 
the unicellular Gregarinse. The anterior end of one such organism unites with the posterior 
end of another; both become encysted, and form one passive spherical body. The conjoined 
structures form an amorphous mass, from which numerous globular bodies are formed, and in 
each of which numerous oblong structures—the pseudo-navicelli—are developed. These bodies 
become, or give rise to, an amoeboid structure, which forms a nucleus and an envelope and 
becomes transformed into a gregarina. 
Sexual reproduction requires the formation of the embryo from the con- 
junction of the male and female reproductive elements, the sperm-cell and 
the germ-cell. These products may be formed either in one individual (her- 
maphroditism, as in the flat worms and gasteropods), or in two separate organ- 
isms (male or female). Sexual reproduction embraces the following varieties : — 
V. Metamorphosis is that form of sexual reproduction in which the embryo from an early 
period undergoes a series of marked changes of external form, e.g., the chrysalis stage, and the 
pupa stage, and in none of these stages is reproduction possible. Lastly, the final sexually 
developed form (the imago stage in butterflies) is produced, which forms the sexual products 1060 
REPRODUCTION. 
[Sec. 431. 
whose union gives rise to organisms which repeat the same cycle of changes. Metamorphosis 
occurs extensively amongst the insects; some of them 
have several stages (holo-metabolic), and others have 
few stages (hemi-metabolic). It also occurs in some 
arthropoda, and worms, e.g., trichina; the sexual form 
of the animal occurs in the intestine, the numerous 
larvce wander into the muscles, where they become 
encysted, and form undeveloped sexual organs, consti- 
tuting the pupa stage of the muscular trichina. When 
the encysted form is eaten 
by another animal, the 
sexual organs come into 
activity, a new brood is 
formed, and the cycle is 
repeated. Metamorphosis 
also occurs in the frog and 
in petromyzon. [This 
is really a condition in 
which the embryo under- 
goes marked changes of 
form before it becomes 
sexually mature.] 
VI. Alteration of 
Generations or Meta- 
genesis. — (Steenstrup). 
—In this variety some of 
the members of the cycle 
can produce new beings 
non-sexually, while in the 
final stage reproduction is 
always sexual. From a 
medical point of view, the life-history of the tape-worm or Taenia is most important. The 
segments of the tape-worm are called proglottides (fig. 770), and each segment is herma- 
phrodite with testes, vas deferens, penis, ovary, etc., and numerous ova. The segments 
are evacuated with the faeces. The eggs are fertilized after they are shed (fig. 764), and 
from them is developed an elliptical embryo, provided with six booklets, which is swallowed 
Fig. 764. 
A ripe egg taken from the 
uterus of Tsenia solium. 
«, Albuminous envelope; 
b, remains of the yolk; 
c, covering of the embryo; 
d, embryo with embryonal 
hooklets. 
Fig. 765. 
Encapsuled cysticercus from Taenia 
solium, embedded in a human sarto- 
rius. Natural size. 
Head of Taenia solium (I) and medio-canellata (II), and joints of both (1, 2). 
Fig. 766, 
by another animal, the host. These embryos bore their way into the tissues of the host, where 
they undergo development, forming the encysted stage, Cysticercus (fig. 767), Coenurus, or 
Echinococcus (fig. 768). The encysted capsule may contain one (cysticercus) or many (coenurus) 
sessile heads of the taenia. In order to undergo further development, the cysticercus must be Sec. 431.] 
REPRODUCTION. 
1061 
eaten alive by another animal, when the head or scolex fixes itself by the hooklets and suckers 
to the intestine of its new host (fig. 767), where it begins to bud and produce a series of new 
segments between the head and the last-formed segment, and thus the cycle is repeated. 
The most important flat-worms are : Taenia solium, in man; the Cysticercus cellulosae (fig. 
766), in the pig, when it constitutes the measle in pork; Taenia mediocanellata (fig. 770), 
the encysted stage, in the ox; Taenia coenurus, in the dog’s intestine; the encysted stage, or 
Coenurus cerebralis, in the brain of the sheep, where it gives rise to the condition of “ staggers ” ; 
Taenia echinococcus, in the dog’s intes- 
tine; the embryos or scolices occur in 
the liver of man as “ hydatids.” 
The medusae also exhibit alternation 
of generations, and so do some insects, 
especially the plant lice or aphides. 
Fig. 767. 
Fig. 768. 
Fig. 769. 
Fig. 767.—Cysticerci from Taenia solium removed from their capsule. I, natural size; 2, 
magnified, a, embryo-sac; b, cavity produced by budding of the embryo-sac; 
discs and hooklets. Fig. 768.—Cysticercus of Taenia solium, with its head and segments 
protruded, a, caudal-sac; b, head of the tape-worm, with discs and hooklets (scolex) ; 
c, neck. Fig. 769.—Part of an Echinococcus capsule, with developing buds, a, sheath; 
b, parenchymatous layer; c, germinating capsule filled with scolices. 
VII. Parthenogenesis (Owen, v. Siebold).—In this variety, in addition to sexual reproduc- 
tion, new individuals maybe produced without sexual union. The non-sexually produced brood 
is always of one sex, as in the bees. A beehive contains a queen, the workers, and the drones 
or males. During the nuptial flight the queen is impregnated by the males, and the seminal 
fluid is stored up in the receptaculum seminis of the queen, and it appears that the queen may 
voluntarily permit the contact of this fluid with the ova or withhold it. All fertilized eggs give 
rise to female, and all unfertilized ones to male bees. 
Fig. 770. 
Taenia mediocanellata. Natural size. 
VIII. Sexual reproduction without any intermediate stages occurs in, besides man, mam- 
mals, birds, reptiles, and most fishes. 
432. TESTIS.—SEMINAL FLUID.—[In the testis, or male repro- 
ductive organ, the seminal fluid which contains the male element or spermatozoa 
is formed. The framework of the gland consists of a thick, strong, white 
fibrous covering, the tunica albuginea, composed chiefly of white interlacing [Sec. 432. 
1062 
TESTIS. 
fibrous tissue. Externally, this layer is covered by the visceral layer of the 
serous membrane, or the tunica vaginalis, which invests the testis and epi- 
didymis. The tunica albuginea is prolonged for some distance as a vertical 
septum into the posterior part of the testis, to form the mediastinum testis 
or corpus Highmori. Septa or trabeculae—more or less complete—stretch 
from the under surface of the T. albuginea towards the mediastinum, so that 
the organ is subdivided thereby into a number of compartments or lobules, 
with their bases directed 
outwards and their apices 
towards the mediastinum. 
From these, finer susten- 
tacular fibres pass into the 
compartments to support 
the structures lying in these 
compartments.] 
[Arrangement of Tub- 
ules.—Each compartment 
contains several seminal 
tubules, long, convoluted 
tubules ( in. in diam.), 
which rarely branch except 
at their outer end; they are 
about 2 feet in length and 
exceed 800 in number. 
These tubules run towards 
the mediastinum, those in 
one compartment uniting 
at an acute angle with each 
other, to form a smaller 
number of narrower straight 
tubules—tubuli recti (fig. 
771). These straight tub- 
ules open into a network of 
tubules in the mediastinum 
to form the rete testis, a 
dense network of tubules 
of irregular diameter (fig. 
771). From this network 
there proceed 12 to 15 
wider ducts—the vasa ef- 
ferentia — which after 
emerging from the testis 
are at first straight, but 
soon become convoluted— 
and form a series of conical 
eminences—the coni vas- 
culosi — which together 
form the head of the epi- 
didymis. These tubes gradually unite with each other and form the body 
and globus minor of the epididymis, which, when unravelled, is a tube 
about 20 feet long terminating in the vas deferens (2 feet long), which is the 
excretory duct of the testis.] 
[Structure of a Seminal Tubule.—The seminal tubules consist of a 
thick well-marked basement membrane, composed of flattened nucleated cells 
arranged like membranes (fig. 776). These tubes are lined by several layers of 
T. albuginea. 
Seminal 
tubules 
cut 
across. 
Blood 
vessels. 
Septum. 
Straight 
tubules. 
Rete 
testis. 
Transverse section of the testis (low 
power view). 
Fig. 771. Sec. 432.] 
TESTIS. 
1063 
more or less cubical cells; there is an outer row of such cells next the base- 
ment membrane, and often showing a dividing large nucleus. Internal to these 
are several layers of inner large clear cells, with nuclei often dividing, so that 
they form many daughter cells which lie internal to them and next the lumen. 
From these daughter cells are formed the spermatozoa, and they constitute the 
spermatoblasts. These several layers of cells leave a distinct lumen. The 
tubuli recti are narrow in diameter, and lined by a single layer of squamous 
or flattened epithelium (fig. 772). The rete testis consists merely of channels 
in the fibrous stroma without a distinct membrana propria, but lined by flattened 
epithelium. The vasa efferentia and coni vasculosi have circular smooth 
muscular fibres in their walls, and are lined by a layer of columnar ciliated 
epithelium with striated protoplasm. At the bases of these cells in some parts 
is a layer of smaller granular cells. These tubules form the epididymis, whose 
tubules have the same structure (fig. 773). In the sheep, pigment cells are 
often found in the basement membrane.] 
[The vas deferens is lined by several layers of columnar epithelium resting 
End ot 
convol- 
uted 
tube. 
Blood-vessel. 
Narrow 
part. 
Transverse 
section of a 
tube of epi- 
didymis. 
Tubulus 
rectus. 
Ciliated 
cylindrical 
epithelium. 
Blood-vessel. 
Interstitial 
connective- 
tissue. 
Rete 
testis. 
Fig- 773- 
Fig. 772.—Convoluted seminal tubule opening into a narrow straight tubule. Fig. 773.—Trans- 
verse section of the tubules of the epididymis. 
Fig. 772. 
on a dense layer of fibrous tissue—the mucosa. Outside this is the muscular 
coat, a thick layer of non-striped muscle, composed of a thick inner circular, 
and thick outer longitudinal layer, a thin sub-mucous coat connecting the mus- 
cular and mucous coats together; outside all is the fibrous adventitia.] 
[The interstitial tissue (fig. 771), supporting the seminal tubules, is 
laminated and covered by endothelial plates, with slits or spaces between the 
lamellae, which form the origin of the lymphatics. These lymph-spaces are 
easily injected by the puncture method. In fact, if Berlin blue be forced into 
the testis, the lymphatics of the testis and spermatic cord are readily filled with 
the injection. In some animals (boar), and to a less extent in man, dog, there 
are also fairly large polyhedral interstitial cells, often with a large nucleus 
and sometimes pigmented. They represent the residue of the epithelial cells of 
the Wolffian bodies (.Klein), or according to Waldeyer, they are plasma cells. 
The blood-vessels are numerous, and form a dense plexus outside the base- 
ment membrane of the seminal tubules.] SPERMATOZOA. 
[Sec. 432. 
Chemical Composition.—The seminal fluid, as discharged from the 
urethra, is mixed with the secretion of the glands of the vas deferens, Cowper’s 
glands, and those of the prostate, and with the fluid of the vesiculae seminales. 
Its reaction is neutral or alkaline, and it contains 82 per cent, of water, serum- 
albumin, alkali-albuminate, nuclein, lecithin, cholesterin, fats (protamin ?), 
phosphorized fat, salts (2 per cent.), especially phosphates of the alkalies and 
earths, together with sulphates, carbonates, and chlorides. The odorous body, 
whose nature is unknown, was called “ spermatin ” by Vauquelin. 
Seminal Fluid.—The sticky, whitish-yellow seminal fluid, largely composed of a mixture of 
the secretions of the above-named glands, when exposed to the air, becomes more fluid, and on 
adding water it becomes gelatinous, and from it separate whitish transparent flakes. When long 
exposed, it forms rhomboidal crystals, which, 
according to Schreiner, consist of phosphatic 
salts with an organic base (C2H5N). These 
crystals (fig. 774) are said to be derived from 
the prostatic fluid, and are identical with the 
so-called Charcot’s crystals (fig. 171, c, and 
\ 138). The prostatic fluid is thin, milky, 
amphoteric, or of slightly acid reaction, and is 
possessed of the seminal odor. The phosphoric 
acid necessary for the formation of the crystals 
is obtained from the seminal fluid. A some- 
what similar odor occurs in the albumin of eggs 
not quite fresh. The non-poisonous ptomain, ca- 
daverin (pentamethyldiamin of Ladenburg), 
isolated by Brieger from dead bodies, has a 
similar odor. The secretion of the vesiculae 
seminales of the guinea-pig contains much 
fibrinogen (p. 477). 
The spermatozoa are 50 long, 
and consist of a flattened pear-shaped 
head (fig. 775, 1 and 2, k), which is 
followed by a rod-shaped middle 
piece, m (Schweigger-Seidel), and a 
long tail-like prolongation or cilium,/. The spermatozoon is propelled for- 
wards by the to-and-fro movements of the tail at the rate of 0.05 to 0.5 mm. 
per second; the movement is most rapid immediately after the fluid is shed, 
but it gradually becomes feebler. 
Finer Structure of Spermatozoa.—The observations of Jensen have shown that the middle 
piece and head are still more complex, although this is not the case in human spermatozoa and 
those of the bull (G. Retzius). These consist of a flattened, long, narrow, transparent, proto- 
plasmic mass, with a fibre composed of many delicate threads in both margins. At the tip of the 
tail both fibres unite into one. The fibre of the one margin is generally straight, the other is 
thrown into wave-like folds, or winds in a spiral manner round the other ( W. Krause, Gibbes). 
G. Retzius describes a special terminal filament (fig. 775, e). An axial thread surrounded by an 
envelope of protoplasm, traverses the middle piece and the tail (.Eimer v. Braun). [Leydig 
showed that in the salamander there is a delicate membrane attached to the tail, and Gibbes has 
described a spiral thread attached to the head (newt) and connected with the middle piece by a 
hyaline membrane.] 
Motion of the Spermatozoa.—[After the discharge of the seminal fluid, the spermatozoa 
exhibit spontaneous movements for many hours or days.] The movements are due to the lash- 
ing movements of the tail, which moves in a circle or rotates on its long axis, the impulse to move- 
ment proceeding from the protoplasm of the middle piece and the tail, which seem to be capable 
of moving when they are detached [Eimer). These movements are comparable to those that 
occur in cilia ($ 292), and there are transition forms between ciliary and amoeboid movements, 
as in the Monera. Action of Reagents on Spermatozoa.—Within the testis they do not 
exhibit movement, as the fluid is not sufficiently dilute to permit them to move. Their move- 
ments are specially lively in the normal secretion of the female sexual organs (Bischoff) and they 
move pretty freely, and for a long time, in all normal animal secretions except saliva. Their 
movements are paralyzed by water, alcohol, ether, chloroform, creasote, gum, dextrin, vegetable 
Fig. 774. 
Crystals from spermatic fluid. Sec. 432.] 
SPERMATOZOA. 
mucin, syrup of grape-sugar, or very alkaline or acid uterine or vaginal mucus (Donne), acids 
and metallic salts, and a too high or too low temperature. The narcotics, as long as they are 
chemically indifferent, behave as indifferent fluids, and so do medium solutions of urea, sugar, 
albumin, common salt, glycerin, amygdalin, etc.; but if these be too dilute or too concentrated, 
they alter the amount of water in the spermatozoa and paralyze them. The quiescence produced 
by water may be set aside by dilute alkalies ( Virchow), as with cilia (p. 574). Engelmann finds 
that minute traces of acids, alcohol, and ether excite movements. The spermatozoa of the frog 
may be frozen four times in succession without killing them. They bear a heat of 43-75° C., and 
they will live for 70 days when placed in the abdominal cavity of another frog (Mantegazza). 
Resistance.—Owing to the large amounts of earthy salts which they contain, when dried 
upon a microscopical slide, they still retain their form ) Valentin). Their form is not destroyed 
by nitric, sulphuric, hydrochloric, or boiling acetic acid, or by caustic alkalies; solutions of NaCl 
and saltpetre (10 to 15 per cent.) change them into amorphous masses. Their organic basis 
resembles the semi-solid albumin of epithelium. 
Seminal fluid, besides spermatozoa, also contains seminal cells, a few epithelial cells from the 
seminal passages, numerous lecithin granules, stratified amyloid bodies (inconstant), granular 
yellow pigment, especially in old age, leucocytes, and sperma crystals (Fiirbinger). 
Spermatozoa. I, human ( X 600), the head seen from the side; 2, on edge; k, head ; m, middle 
piece; f, tail; e, terminal filament; 3, from the mouse; 4, bothriocephalus latus ; 5, deer; 
6, mole; 7, green woodpecker; 8, black swan; 9, from a cross between a goldfinch (M) 
and a canary (F); 10, from cobitis. 
Fig- 775- 
Development of Spermatozoa.—The walls of the seminal tubules, n, 
which are made up of spindle-shaped cells, are lined by a nucleated, proto- 
plasmic layer (fig. 776, I, b, and IV, h), from which, according to one view, 
there project into the lumen of the tube long (0.053 mm-) column-like prolon- 
gations (I, c, and II, III, IV), which break up at their free end into several 
round or oval globules (II)—the spermatoblasts (v. Ebner); these consist 
of soft, finely granular protoplasm, and usually have an oval nucleus in their 
lower part. During development, each lobule of the spermatoblast elongates 
into a tail (IV, r), while the deeper part forms the head and middle pieces of 
the future spermatozoSn (IV, k). At this stage the spermatoblast is like a 
greatly enlarged, irregular, cylindrical epithelial cell. When development is 1066 
SPERMATOZOA. 
[Sec. 432. 
complete, the head and middle pieces are detached (III, f), and ultimately the 
remaining part of the spermatoblast undergoes fatty degeneration. Not unfre- 
quently in spermatozoa we may observe a small mass of protoplasm adhering to 
the tail and the middle piece (III, /). Between the spermatoblasts are numer- 
ous round amoeboid cells devoid of an envelope, and connected to each other 
by processes. They seem to secrete the fluid part of the semen, and they may 
therefore be called seminal cells (I, s, II, III, IV, /). A spermatozoon, 
therefore, is a detached independently mobile cilium of an enlarged epithelial 
cell. Some observers adhere to the view that the spermatozoa are, in part at 
least, formed with round cells, by a process of endogenous development. 
[All observers are agreed that the appearance of a seminal tubule differs 
according to the state of activity of the cells lining it, but in the case of a 
tubule with developing spermatozoa, although the appearance seen in transverse 
section of a tubule is on the whole such as is shown in fig. 776, I, still the 
view stated above is not the one which has the largest number of supporters. 
Other observers interpret the appearances differently. According to the other 
view, there is but one kind of gland-cell lining the tubules, and certain of 
these cells or spermatogonia—lying next the periphery—by successive acts 
of division give rise to round cells with dark nuclei, e.g., the daughter cells or 
Fig. 776. 
Semi-diagrammatic spermatogenesis: I, transverse section of a seminal tubule—a, membrane ; 
b, protoplasmic inner lining; c, spermatoblast; s, seminal cells. II, Unripe spermatoblast— 
f rounded clavate lobules; /, seminal cells. IV, spermatoblast, with ripe spermatozoa (b) 
not yet detached ; tail, r; n, wall of the seminal tubule ; h, its protoplasmic layer. Ill, 
spermatoblast with a spermatozoon free, t. 
spermatocytes, which arrange themselves radially towards the lumen of the 
tubule. They are represented by the indifferent cells lying between the so-called 
spermatoblasts in fig. 776, I. The last generation of cells derived from these 
spermatocytes, lying next the lumen of the tube, are called spermatides, and 
these last become the spermatozoa ; in the process the nucleus of each sperma- 
tide becomes the head, a small part of the protoplasm becomes the tail of the 
spermatozoa. The largest part of the protoplasm of the spermatide remains, 
and these residues, as it were, come together and form the large branched 
structure, which on the previously stated view were called spermatoblasts. The 
young spermatozoa lie embedded in the tops of these masses of protoplasm ; 
thus an entirely different explanation is given of the appearances seen in a 
seminal tubule.] 
According to Benda and v. Ebner, the spermatoblasts are formed by the coalescence (copula- 
tion) of a group of seminal cells with the lower part of the foot-plate and stalk of the spermato- Sec. 432.] 
OVARY. 
blasts. Each seminal cell forms from its nucleus the head, and from its protoplasm the tail of 
a spermatozoon. For the complete formation of these parts, there must be a coalescence of the 
seminal cells with the spermatoblasts. 
Shape of Spermatozoa.—The spermatozoa of most animals are like cilia with larger or 
smaller heads. The head is elliptical (mammals), or pear-shaped (mammals), or cylindrical 
(birds, amphibians, fish), or cork-screw (singing birds, paludina), or merely like hairs (insects— 
fig. 775). Immobile seminal cells, quite different from the ordinary forms, occur in myriapoda 
and the oyster. 
433. THE OVARY—OVUM—UTERUS.—[Structure of the 
Ovary.—The ovary consists of a connective-tissue framework, with blood- 
vessels, nerves, lymphatics, and numerous non-striped muscular fibres. The 
ova are embedded in this matrix (fig. 777). The surface of the ovary is cov- 
ered with a layer of columnar epithelium (fig. 778, e), the remains of 
the germ-epithelium. The 
most superficial layer is called 
the albuginea; it does not 
contain any ova. Below it is 
the cortical layer of Schron, 
which contains the smallest 
Graafian follicles inch— 
fig- 777), while deeper down 
are the larger follicles to 
inch). There are 40,000 
to 70,000 follicles in the ovary 
of a female infant. Each ovum 
lies within its follicle or Graa- 
fian vesicle.] 
Structure of an Ovum.— 
The human ovum (C. E. v. 
Baer, 1827) is 0.18 to 0.2 mm. 
[y|y in.] in diameter, and is a 
spherical cellular body with a 
thick, solid, elastic envelope, the zona pellucida, with radiating striae 
(fig. 779). The zona pellucida encloses the cell-contents represented by the 
protoplasmic, granular, contractile vitellus or yolk, which in turn contains 
the eccentrically placed spherical nucleus or germinal vesicle (40-50 p.— 
Purkinje, 1825 ; Coste, 1834). The germinal vesicle contains the nucleolus or 
germinal spot (5-7 p—R. Wagner, 1835). The chemical composition is given 
in § 232. 
Fig. 777. 
Section of a cat’s ovary. The place of attachment or 
hilum is below. On the left is a corpus luteum. 
[Ovum. Cell. 
Zona pellucida corresponds to the Cell-wall. 
Vitellus “ “ Cell-contents. 
Germinal vesicle “ “ Nucleus. 
Germinal spot “ “ Nucleolus.] 
[This arrangement shows the corresponding parts in a cell and the ovum, and 
in fact the ovum represents a typical cell.] 
The zona pellucida (figs. 779, 780, V, Z), to which cells the Graafian follicles are often ad- 
herent, is a cuticular membrane formed secondarily by the follicle (Pfluger). According to Van 
Beneden, it is lined by a thin membrane next the vitellus, and he regards the thin membrane as 
the original cell-membrane of the ovum. The fine radiating striae in the zona are said to be due 
to the existence of numerous canals (Kolliker, v. Sehlen). It is still undecided whether there is 
a special micropyle or hole for the entrance of the spermatozoa. 
A micropyle has been observed in some ova (holothurians, many fishes, mussels). The ova 
of some animals (many insects, e.g., the flea) have porous canals in some part of their zona, 
and these serve both for the entrance of the spermatozoa and for the respiratory exchanges in the 
ovum. 1068 
OVARY. 
[Sec. 433. 
The development of the ova takes place in the following manner: The 
surface of the ovary is 
covered with a layer of 
cylindrical epithelium— 
the so-called “germ- 
epithelium”—and be- 
tween these cells lie 
somewhat spherical 
“primordial ova” 
(fig. 780, I, a, a). The 
epithelium covering the 
surface dips into the 
ovary at various places to 
form “ovarian tubes” 
(fig. 780). These tubes, 
from and in which the 
ova are developed ( Wal- 
deyer), become deeper 
and deeper, and they 
contain, in their interior, 
large single spherical cells 
with a nucleus and a nu- 
cleolus, and other smaller 
and more numerous cells 
lining the tube. The 
large cells are the cells (primordial ova) that are to develop into ova, while 
the smaller cells are the epithelium of the tube, and are direct continuations of 
the cylindrical epithelium on the surface of the ovary. The upper extremities of 
the tubes become closed, 
while the tube itself is 
divided into a number of 
rounded compartments— 
cut off, as it were, by the 
ingrowth of the ovarian 
stroma (I, c). Each com- 
partment so cut off 
usually contains one, or 
at most two, ova (IV, 
0, o), and becomes de- 
veloped into a Graafian 
follicle. The embryonic 
follicle enlarges, and fluid 
appears within it; while 
its lateral small cells be- 
come changed into the 
epithelium lining the 
Graafian follicle itself, or 
those of the membrana 
granulosa. The cells of 
the membrana granulosa 
form an elevation at one part—the discus proligerus—by which the ovum 
is attached to the membrana granulosa. The follicles are at first only 0.03 mm. 
in diameter, but they become larger, especially at puberty. [The smaller ova 
are near the surface of the ovary, the larger ones deeper in its substance (fig. 
778).] When a Graafian follicle with its ovum is about to ripen (IV), it sinks 
Fig. 778. 
Section of an ovary, e,germ-epithelium; I, large-sized follicles; 
2, 2, middle-sized, and 3, 3, smaller-sized follicles; 0, ovum 
within a Graafian follicle ; v, v, blood-vessels of the stroma; 
g, cells of the membrana granulosa. 
Germinal 
spot. 
Cells of discus proligerus. 
Yolk. 
Accessory- 
nucleoli, 
also f. 
'Germinal vesicle 
Zona 
pellucida. 
Fig. 779. 
Ripe ovum of rabbit. Sec. 433.] 
OVARY. 
1069 
or passes downwards into the substance of the ovary, and enlarges at the same 
time by the accumulation of fluid—the liquor folliculi—between the tunica 
and membrana granulosa. It is covered by a vascular outer membrane—the 
theca folliculi—which is lined by the epithelium constituting the membrana 
granulosa (IV, g). When a Graafian follicle is about to burst, it again 
rises to the surface of the ovary, and attains a diameter of 1.0 to 1.5 mm., and 
is now ready to burst and discharge its ovum. [The tissue between the enlarged 
Graafian follicle and the surface of the ovary gradually becomes thinner and 
thinner and less vascular, and at last gives way, when the ovum is discharged 
and caught by the fimbriated extremity of the Fallopian tube embracing the 
ovary, so that the ovum is shed into the Fallopian tube itself.] Only a small 
number of the Graafian follicles undergo development normally, by far the 
I, An ovarian tube in process of development (new-born girl), a, a, young ova between the 
epithelial cells on the surface of the ovary; b, the ovarian tube with ova and epithelial cells; 
<r, a small follicle cut off and enclosing an ovum. II, Open ovarian tube from a bitch. Ill, 
Isolated primordial ovum (human). IV, Older follicle with two ova (0, 0) and the tunica 
granulosa (g) of a bitch. V, Part of the surface of a ripe ovum of a rabbit—z, zona pellu- 
cida; d, vitellus; £, adherent cells of the membrana granulosa. VI, First polar globule 
formed. VII, Formation of the second polar globule (Fol). 
Fig. 780. 
greatest number atrophy and never ripen. (The study of the development of 
the ova and ovary was advanced particularly by Martin Barry, Pfluger, Bill- 
roth, Schron, His, Waldeyer, Kdlliker, Koster, Lindgren, Schulin, Foulis, 
Balfour, and others.) 
According to Waldeyer, the mammalian ovum is not a simple cell, but a compound structure. 
The original primitive ovum is, according to him, formed only of the germinal vesicle and 
germinal spot, with the surrounding membranous clear part of the vitellus (fig. 780, III). The 
remainder of the vitellus ‘is developed by the transformation of granulosa cells, which also form 
the zona pellucida. 1070 
hen’s egg. 
[Sec. 433. 
Holoblastic and Meroblastic Ova.—The ova of frogs and cyclostomata have the same 
type as mammalian ova; they are called holoblastic ova, because all their contents go to form 
cells which take part in the formation of the embryo. In contrast with these, the birds, the mono- 
tremes alone amongst the mammals (Caldwell), the reptiles and the other fishes have mero- 
blastic ova (Reichert). The latter, in addition to the white or formative yolk, which corre- 
sponds to the yolk of the holoblastic eggs, and gives rise to the embryonic cells, contains the 
food-yolk (yellow in birds), which during development is a reserve store of food for the develop- 
ing embryo. 
Hen’s Egg.—The small, white, round, finely granular speck, the cica- 
tricula, blastoderm, or tread, which is 2.5-3.5 mm. broad and 0.28-0.37 
thick, lying upon the surface of the yellow yolk, corresponds to the contents 
of the mammalian ovum, and is, therefore the formative yolk. In the cica- 
tricula lie the germinal vesicle and spot (figs. 780, 783). From the tread, in 
which lie the characteristic white yolk elements, processes pass into the 
yellow yolk. A part passes as an 
exceedingly thin layer round the 
yolk, or cortical protoplasm. 
[The cicatricula in an unincu- 
bated egg is always uppermost 
whatever the position of the egg, 
provided the contents can rotate 
freely, and this is due to the 
lighter specific gravity of that 
part of the yolk in connection 
with the cicatricula (fig. 783). 
In a fecundated egg the cica- 
tricula has a white margin (the 
area opaca), surrounding a clear 
transparent area, the beginning 
of the area pellucida, contain- 
ing an opaque spot in its centre. 
If an egg be boiled very hard, 
and a section made of the yolk, it will be found to consist of alternating layers 
Germinal vesicle 
and spot. 
Blastoderm. 
Its processes. 
Yelk 
Marginal 
protoplasm. 
Vitelline 
membrane. 
Fig. 781. 
Scheme of a meroblastic egg. 
Diagrammatic longitudinal section through an unincu- 
bated hen’s egg. Bl, blastoderm; GD, yellow yolk ; 
WD, white yolk and nucleus of Pander; DM, 
vitelline membrane; EW, “white;” Ch, chalazae; 
S, shell membrane; KS, shell; LR, air-chamber. 
Fig- 783- 
a, White; b, yellow yolk 
granules. 
Fig. 782. 
of white and yellow yolk. The outermost layer is a thin layer of white yolk, 
which is slightly thicker at the margin of the cicatricula. Within the centre Sec. 433.] 
hen’s egg. 
1071 
of the yolk is a flask-shaped mass of white yolk, the neck of the flask being con- 
nected with the white yolk outside. This flask-shaped mass does not become 
so hard on being boiled, and its upper expanded end is known as the “ nu- 
cleus of Pander” (fig. 783). The great mass of the yolk is made up, how- 
ever, of yellow yolk.] 
Microscopically, the yellow yolk consists of soft yellow spheres, of from 23-100 in 
diameter, and they are often polyhedral from mutual pressure (fig. 782, b). [They are very 
delicate and non-nucleated, but filled with fine granules, which are, perhaps, proteid in their 
nature, as they are insoluble in ether and alcohol. They are developed by the proliferation of 
the granulosa cells of the Graafian follicle, which also seem ultimately to form the granulo- 
fibrous double envelope or the vitelline membrane (Eimer). The whole yolk of the hen’s 
egg is regarded by some observers as equivalent to the mammalian ovum plus the corpus luteum. 
Microscopically, the white yolk 
consists of small vesicles (5-75 
fi) containing a refractive sub- 
stance and larger spheres con- 
taining several smaller spherules 
(fig. 782, a). The whole yolk is 
enveloped by the vitelline 
membrane, which is transpa- 
rent, but possesses a fine fibrous 
structure, and it seems to be allied 
to elastic tissue.] 
When the yolk is fully devel- 
oped within the Graafian follicles 
of the hen’s ovarium, the follicle 
bursts and discharges the yolk, 
which passes into the oviduct, 
where in its passage it rotates, 
owing to the direction of the 
folds of the mucous membrane 
of the oviduct. The numerous 
glands of the oviduct secrete the 
albumin, or white of the egg, 
which is deposited in layers 
around the yolk in its passage 
along the duct, and forms at the 
anterior and posterior chalazae. 
[The chalazae are two twisted 
cords composed of twisted layers 
of the outer denser part of the 
albumin. They extend from the 
poles of the yolk not quite to the 
outer part of the albumin (fig. 
783, CA).] [The albumin is in- 
vested by the membrana tes- 
tacea or shell-membrane, 
which is composed of two layers 
—an outer thicker and an inner 
thinner one (fig. 783). Over the 
greater part of the albumin these 
two layers are united, but at the 
broad end of the hen’s egg they 
tend to separate, and air passing 
through the porous shell sepa- 
rates them more and more as the 
fluid of the egg evaporates. This air-space is not found in fresh-laid eggs.] The layers consist 
of spontaneously coagulated keratin-like fibres arranged in a spiral manner around the albumin 
{Lindvall and Hammarsten). [External to this is the test or shell, which consists of an 
organic matrix impregnated with lime salts.] The shell consists of albumin impregnated with 
lime salts, which form a very porous mortar. [The shell is porous, and its inner layer is perfo- 
rated by vertical canals, through which the respiratory exchange of the gases can take place.] 
In the eggs of some birds there is an outer structureless, porous, slimy, or fatty cuticula. The 
shell is secreted in the lower part of the oviduct. The shell is partly used up for the develop- 
Fig. 784. 
Vertical section of the normal uterine mucous membrane, m, 
together with a part of the subjacent muscular layer, mv 
Fig. 785. 
Surface section of fig. 784. 1072 
STRUCTURE OF THE UTERUS. 
[Sec. 433. 
ment of the bones of the chick (Prout, Gruwe), although this is denied by Polt and Preyei-. 
The pigment which often occurs in many layers of the surface of the eggs of some birds appears 
to be a derivative of haemoglobin and biliverdin. 
Chemical Composition.—The yellow yolk is alkaline, and colored yellow owing to the 
presence of lutein, which contains iron. It contains several proteids [including a globulin body 
called vitellin (p. 479)], a body resembling nuclein, lecithin, vitellin, glycerin-phosphoric acid, 
cholesterin, olein, palmitin, dextrose, potassic chloride, iron, earthy phosphates, fluoric and 
silicic acids. The presence of cerebrin, glycogen, and starch is uncertain. [Dareste states that 
starch is present.] 
[The albumin of egg contains—water, 86 per cent.; proteids, 12; fat and extractives, 1.5; 
saline matter, including sodic and potassic chlorides, phosphates, and sulphates, .5 per cent.] 
[The uterus, a thick hollow muscular organ, is covered externally by a 
serous coat, and lined internally by a mucous membrane, while between 
the two is the thick muscular coat, composed of smooth muscular fibres 
arranged in a great number of layers and in different directions. The mucous 
membrane of the body of the uterus in the unimpregnated condition has no 
folds, while the muscularis mucosae is very well developed, and forms a great 
Left broad ligament, Fallopian tube, ovary, and parovarium, a, uterus; b, isthmus of Fallopian 
tube; c, ampulla; g, fimbriated end of the tube, with the parovarium to its right; e, ovary; 
f, ovarian ligament. 
Fig. 786. 
part of the uterine muscular wall. The mucous membrane is lined by a single 
layer of columnar ciliated epithelium. A vertical section shows the mucous 
membrane to contain numerous tubular glands (fig. 784)—the uterine glands— 
which branch towards their lower ends. They have a membrana propria, and 
are lined by a single layer of ciliated epithelium, a small lumen being left in 
the centre. The utricular glands are not formed during intra-uterine life 
(.Turner), nor are there any glands in the human uterus at birth (£7. J. Engel- 
itiann). There are numerous slit-like lymphatic spaces in the mucous membrane 
(Leopold), which communicate with well-marked lymphatic vessels existing in 
this and the other layers of the organ. In the cervix, the mucous membrane 
is folded, representing in the virgin the appearance known as the arbor vitae. 
The external surface of the vaginal part of the neck is covered by stratified 
squamous epithelium, like the vagina.] 
[The Fallopian tubes are really the ducts of the ovaries (fig. 786). They 
consist of a serous, muscular (an external, longitudinal, and an internal cir- Sec. 433.] 
PUBERTY AND MENSTRUATION. 
1073 
cular) layer of non-striped muscle, and a mucous layer thrown into many folds 
and lined by a single layer of ciliated columnar epithelium, but no glands (fig. 
787)0 
434. PUBERTY.—The term puberty is applied to the period at which a 
human being becomes capable of procreating, which occurs from the 13th to 
15th years in the female, and the 14th to 16th in the male. In warm climates, 
puberty may occur in girls even at 8 years of age. Towards the 40th to 50th 
year, the procreative faculty ceases in the female with the cessation of the 
menses; this constitutes the menopause or grand climacteric, whilst in 
man the formation of 
seminal fluid has been 
observed up to old 
age. From the period 
of puberty onwards, 
the sexual appetite 
occurs, and the ripe 
ova are discharged 
from the ovary. [But 
ova are discharged 
even before puberty or 
menstruation has oc- 
curred.] At puberty, 
the internal and ex- 
ternal generative or- 
gans and their annexes 
become more vascular 
and undergo develop- 
ment ; the pelvis of 
the female assumes the 
characteristic female 
shape. For the changes in the mammae see § 330. At the same time hair is 
developed on the pubes and axilla, and in the male on the face, while the 
sebaceous glands become larger and more active. 
Other changes occur, especially in the larynx. In the boy the larynx elongates in its 
antero-posterior diameter, the thyroid, or Adam’s apple, becomes more prominent, while the 
vocal cords lengthen, so that the voice is hoarse, or husky, or “ breaks,” the voice being lowered 
at least an octave. In the female the larynx becomes longer, while the compass of the voice is 
increased. The vital capacity ($ 108), corresponding to the increase in the size of the chest, 
undergoes a considerable increase; the whole form and expression assume the characteristic 
sexual appearance, while the psychical energies also receive an impulse. 
435. MENSTRUATION.—External Signs .—At regular intervals of 
time, of days in a mature female, there is a rupture of one or more 
ripe Graafian follicles, while at the same time there is a discharge of blood 
from the external genitals. This is known as the process of menstruation (or 
menses, catamenia, or periods). Most women menstruate during the first quar- 
ter of the moon, and only a few at new and full moon (Strohl). In mammals, 
the analogous condition is spoken of as the period of heat [or the “rut” in 
deer]. There is a slightly bloody discharge from the external genitals in car- 
nivora, the mare, and cow (.Aristotle), while apes in their wild condition have 
a well-marked menstrual discharge (.Neubert). [Observations on cases where 
abdominal section has been performed have shown that the Graafian follicles 
mature and burst at any time (Lawson Tait, Leopold^.~\ 
The onset of menstruation is usually heralded by constitutional and local phenomenon— 
there is an increased feeling of congestion in the internal generative organs, pain in the back 
68 
Connective- 
tissue. 
Ciliated 
epithelium. 
Circular 
muscular 
fibres. 
Muscular 
fibres cut 
across. 
Fig. 787. 
Transverse section of the Fallopian tube. MENSTRUATION. 
[Sec. 435. 
and loins, tension in the region of the uterus and ovaries, which are sensitive to pressure, fatigue 
in the limbs, alternate feeling of heat and cold, and even a slight increase of the temperature of 
the skin (Kersch). There may be retardation of the process of digestion and variations in the 
evacuation of the fseces and urine, and in the secretion of sweat. The discharge is slimy at first, 
and then becomes bloody, lasting three to four days; the blood is venous, and shows little ten- 
dency to coagulate, provided it is mixed with much alkaline mucus from the genital passages; 
but, if the hemorrhage be free, the blood may be clotted. The quantity of blood is ioo to 200 
grms. [The blood contains many white blood-corpuscles and epithelial cells.] After cessation 
of the discharge of blood there is a moderate amount of mucus given off. 
The characteristic internal phenomena which accompany menstruation are : 
(1) The changes in the uterine mucous membrane; and (2) the rupture of the 
Graafian follicle. 
1. Changes in the Uterine Mucous Membrane.—The uterine mucous 
membrane is the chief source of the blood. The ciliated epithelium of the 
congested, swollen, and folded, soft, thick (3 to 6 mm.) mucous membrane is 
shed. The orifices of the numerous mucous glands of the mucous membrane 
are distinct, the glands enlarge, and the cells undergo fatty degeneration, and 
so do the tissue and the blood-vessels lying between the glands. The tissue 
contains more leucocytes than normal. This fatty degeneration and the ex- 
cretion of the degenerated tissue occur, however, only in the superficial layers 
of the mucosa, whose blood-vessels, when torn across, yield the blood. The 
deeper layers remain intact, and from them, after menstruation is over, the 
new mucous membrane is developed 
{Kundrat and G.J.Engelmanri). [Leo- 
pold denies the existence of this fatty de- 
generation. According to Williams, the 
entire mucous membrane is removed at 
each menstrual period, and it is regene- 
rated from the muscular coat (fig. 789). 
The mucous membrane of the cervix 
remains free from these changes.] 
2. Ovulation.—The second import- 
ant internal phenomenon is ovulation, in 
which process the ovary becomes more 
vascular—the ripe follicle is turgid with 
fluid, and in part projects above the sur- 
face of the ovary. The follicle ulti- 
mately bursts, its membranes and the 
epithelium covering of the ovary are 
torn or give way under the pressure, the 
bursting being accompanied by the dis- 
charge of a small amount of blood. At 
the same time the congested, turgid, and 
erected fimbriated extremity of the Fal- 
lopian tube is applied to the ovary, so that 
the discharged ovum, with its adherent 
granulosa cells, and the liquor folliculi, 
are caught by the funnel-shaped ex- 
tremity of the tube (fig. 786). The 
ovum, when discharged, is carried to- 
wards the uterus by the ciliated epithelium (§ 433) of the tube, and perhaps 
also partly by the contraction of its muscular coat. Ducalliez and Kiiss found 
that, by fully injecting the blood-vessels, they could imitate the erection of the 
Fallopian tube. Rougat points out that the non-striped muscle of the broad 
ligaments may cause constriction of the vessels, and thus secure the necessary 
injection of the blood-vessels of the Fallopian tube. 
Fig. 788. 
Fig. 789. 
Fig. 788.—Diagram of the uterus just before 
menstruation. The shaded portion repre- 
sents the mucous membrane. Fig. 789.— 
Uterus when menstruation has just ceased, 
showing the cavity of the body deprived 
of mucous membrane (J. Williams). Sec. 435.] 
CORPUS LUTEUM. 
Pfluger’s Theory of Ovulation.—There are two theories as to the connection between 
ovulation or the discharge of an ovum and the escape of blood from the uterine mucous mem- 
brane. Pfliiger regards the bloody discharge from the superficial layers of the uterine mucous 
membrane as a physiological preparation or “ freshening” of the tissue (in the surgical sense), 
by which it will be prepared to receive the ovum when the latter reaches the uterus, so that 
union can take place between the ovum and the freshly exposed surface of the mucous mem- 
brane, and thus the ovum will receive nourishment from a new surface. 
Reichert’s Theory.—This view is opposed to that of Reichert, Engelmann, Williams, and 
others. According to Reichert’s theory, before an ovum is discharged at all there is a sympa- 
thetic change in the uterine mucous mem- 
brane, whereby it becomes more vascular, 
more spongy, and swollen up The mucous 
membrane so altered is spoken of as the 
membrana decidua tnenstrualis, and from 
its nature it is in a proper condition to re- 
ceive, retain, and nourish a fertilized ovum 
which may come into contact with it. If 
the ovum, however, be not fertilized, and 
escape from the genital passages, then the 
uterine mucous membrane degenerates, and 
blood is shed as above described. Accord- 
ing to this view the hemorrhage from the 
uterine mucous membrane is a sign of the 
non-occurrence of pregnancy ; the mucous 
membrane degenerates because it is not required for this occasion; the menstrual blood is an 
external sign that the ovum has not been impregnated. So that pregnancy, i. <?., the develop- 
ment of the embryo in utero, is to be calculated, not from the last menstruation, but from some 
time between the last menstruation and the period which does not occur. 
In some cases the ovulation and the formation of the decidua menstrualis occur separately, so 
that there may be menstruation without ovulation, and ovulation without menstruation. 
Corpus Luteum.—When a Graafian follicle bursts, it discharges its con- 
tents and collapses; in the interior are the remains of the membrana granulosa 
and a small effusion of 
blood, which soon coagu- 
lates. The small rupture 
soon heals, after the serum 
is absorbed. The vascular 
wall of the follicle swells 
up. Villous prolongations 
or granulations of young 
connective-tissue, rich in 
capillaries and cells, grow 
Stroma of ovary. 
Outer layer of follicle. 
Vessels between outer 
layer and tunica propria. 
Folded and thickened 
tunica propria. 
Fig. 790 
Fresh corpus luteum. 
Corpus 
luteum 
with a 
fibrous 
centre. 
Stroma 
of ovary 
with 
blood- 
vessels. 
Lymph- 
atics. 
Corpus luteum of cow (X iy£). 
Fig. 791. 
Lutein cells from the corpus luteum of cow 
Fig. 792. 
into the interior of the follicle (fig. 791). Colorless blood-corpuscles also 
wander into the interior. At the same time the cells of the granulosa prolife- 
rate and form several layers of cells, which ultimately, after the disappearance 
of a number of blood-vessels, undergo fatty degeneration, lutein and fatty 
matter being formed, and it is this mass which gives the corpus luteum its yel- 
low color (fig. 792). The capsule becomes more and more fused with the PENIS. 
[Sec. 435. 
ovarian stroma. If pregnancy does not take place after the menstruation, then 
the fatty matter is rapidly absorbed, and the effused blood is changed into 
haematoidin (§ 20) and other derivatives of haemoglobin, while there is a 
gradual shrivelling of the whole mass, which is complete in about four weeks, 
only a very small remainder being left. Such a corpus luteum, /.<?., one not 
accompanied by pregnancy, is called a false corpus luteum. If, however, 
pregnancy occurs, then the corpus luteum, instead of shrivelling, grows and 
becomes a large body, especially at the third and fourth month, the walls are 
thicker, the color deeper, so that the corpus luteum at the period of delivery 
may be 6 to 10 mm. in diameter, and its remains may be found in the ovary 
for a very long time thereafter (fig. 791). This form is sometimes spoken of 
as a true corpus luteum. [We cannot draw a sharp distinction between 
these two forms.] Only a very small number of the ova in the ovary undergo 
development and are discharged; by far the greater number degenerate 
(Slavjansky). 
436. PENIS—ERECTION.—Penis.—[The penis is composed of the two long cylindri- 
cal corpora cavernosa, and the corpus spongiosum, which lies between and below them, 
and surrounds the urethra (fig. 793); these are held together by fibrous and muscular sheaths, and 
are composed of erectile tissue.] Our knowledge of the distribution of the blood within the 
penis is chiefly due to C. Langer’s researches. The albuginea of the corpus spongiosum consists 
of tendinous connective-tissue, containing thickly-woven elastic tissue and smooth muscular fibres, 
which together form a solid fibrous enve- 
lope, from which numerous interlacing tra- 
beculae pass into the interior, so that the 
corpus spongiosum comes to resemble a 
sponge. The anastomosing spaces bounded 
by these trabeculae form a series of inter- 
communicating venous spaces or sinuses 
filled with blood and lined by a layer of 
endothelium constituting erectile tissue 
(fig- 794)- The largest sinuses lie in the 
lower and external part of the corpus 
cavernosum, while they are less numerous 
and smaller in the upper part. The small 
arteries arise from the A. profunda penis, 
which runs along the septum, and pass to 
the trabeculae after following a very sinu- 
ous course. At the outer part of the cor- 
pus spongiosum, some of the small arteries 
become directly continuous with the larger 
venous sinuses; some of them, however, terminate in capillaries both in the outer part and 
within the corpus spongiosum, the capillaries ultimately terminating in the venous sinuses. The 
helicine arteries of the penis described by Joh. Muller are merely much twisted arteries. The 
deep veins of the penis arise by fine veinlets within the body of the organ, while the veins pro- 
ceeding from the cavernous spaces pass to the dorsum of the penis to form the vena dorsalis 
penis (fig. 793). As these vessels have to traverse the meshes of the vascular network in the 
cortex of the corpora cavernosa penis, it is evident that, when the network is congested by being 
filled with blood, it must compress the outgoing venous trunks. The corpus cavernosum urethrae 
consists for the most part of an external layer of closely packed anastomosing veins, which sur- 
round the longitudinally directed blood-vessels of the urethra. 
In the dog all the arteries of the penis run at first towards the surface, where they divide into 
penicilli. The veins arise from the capillary loops in the papillae, and they empty their blood 
into the cavernous spaces. Only a small part of the blood passes to the cavernous spaces 
through the internal capillaries and veins, but arterial blood never flows directly into these spaces 
(Af. v. Frey). 
Mechanism of Erection.—Erection is due to the over-filling of the 
blood-vessels of the penis with blood, whereby the volume of the organ is 
increased four or five times, while, at the same time there are also a higher 
temperature, increased blood-pressure (to of that in the carotid—Eckhard), 
with at first a pulsatile movement, increased consistence, and erection of the 
organ. 
Skin. 
Superficial fascia. 
Fibrous coat of c. c. 
Corpus cavernosum. 
Urethra. 
Corpus spongiosum. 
Transverse section across the middle third of the 
body of the penis, n, nerve; a, artery; v, vein. 
Fig- 793- Sec. 436.] 
ERECTION OF THE PENIS. 
Regner de Graaf obtained complete erection of the penis by forcibly injecting its blood-vessels 
(1668). 
The preliminary phenomena consist in a considerable increase of the 
arterial blood-supply, the arteries being dilated and pulsating strongly. The 
arteries are controlled by the nervi erigentes. The nervi erigentes [called 
by Gaskell the pelvic splanchnics (fig. 530)] arise chiefly from the second 
(more rarely the third) sacral nerves (dog), and have ganglionic cells in their 
course (Zoven, Nikolsky). These nerves contain vaso-dilator fibres, which 
can be excited in part re- 
flexly from the sensory 
nerves of the penis, the 
transference centre being 
in the centre for erection 
in the spinal cord (§ 372, 
4). Sensory impressions 
produced by voluntary 
movements of the genital 
apparatus (by the ischio- 
and bulbo-cavernosi and 
cremaster muscles) can also 
discharge this reflex; while 
the thought of sexual im- 
pulses, referable to the 
penis, tends to induce erec- 
tion. The nervi erigentes 
also supply the longitudi- 
nal fibres of the rectum 
(.Fellner). 
The centre for erec- 
tion in the spinal cord 
(§ 362, 2) is, however, 
controlled by the dominat- 
ing vaso-dilator centre in the medulla oblongata (§ 372), and the two centres 
are connected by fibres within the cord; hence, stimulation of the upper part 
of the cord, as by asphyxiated blood (§ 362, 5) or muscarin, may also be 
followed by erection (.Nikolsky). [The seminal fluid is frequently found dis- 
charged in persons who have been hanged.] 
The psychical activity of the cerebrum has a decided influence on the genital 
vaso-dilator nerves. Just as the psychical disturbance which accompanies 
anger or shame is followed by dilatation of the blood-vessels of the head, 
owing to stimulation of the vaso-dilator fibres, so when the attention is directed 
to the sexual centres there is an action upon the nervi erigentes. This action 
of the brain is more comprehensible, since we know that the diameter of the 
blood-vessels is affected by the cortex cerebri (§ 377). The fibres probably 
pass from the cerebrum through the peduncles of the cerebrum and the pons; 
as a matter of fact, if these parts be stimulated, erection may take place 
(§ 362, 4) (Eckhard). 
When the impulse to erection is obtained by the increased supply of arterial 
blood, the full completion of the act is brought about by the activity of the 
following transversely striped muscles : (1) The ischio-cavernosus arises from 
the coccyx, and by its tendinous union surrounds the root of the penis (fig. 
203). When it contracts, it compresses the root of the penis from above and 
laterally, so that the outflow of blood from the penis is hindered. It has no 
action on the dorsal vein of the penis, as this vessel lies in a groove on the 
Erectile tissue. trabeculae of connective-tissue with elastic 
fibres and smooth muscle (c); b, venous spaces. 
Fig. 794. 1078 
EMISSION OF SEMEN. 
[Sec. 436. 
dorsum of the penis, and is therefore protected from compression by the tendon. 
(2) The deep transversus perinei is perforated by the vena profundae penis, 
which come from the corpora cavernosa, so that when it contracts it must 
compress these veins between the tense horizontal fibres (fig. 795, 6). The 
deep veins of the penis join the common pudendal vein and the plexus San- 
torini. (3) Lastly, the bulbo-cavernosus is concerned in the hardening of the 
urethral corpus spongiosum, as it compresses the bulb of the urethra (figs. 795, 
5, 203). All these muscles are partly under the control of the will, whereby 
the erection may be increased. Normally, however, their contraction is excited 
reflexly by stimulation of the sensory nerves of the penis (§ 362, 4). 
The congestion of blood is not complete, else, in pathological cases, continuous erection, as 
in satyriasis, would give rise to gangrene. The accumulation of the blood in the penis is favored 
by the fact that the origins of the veins of the penis lie in the corpus cavernosum, which, when 
it enlarges, must compress them. There are also trabecular smooth muscular fibres, which 
compress the large venous plexus of Santorini. 
That erection is a complex motor act depending on the nervous system, is proved by an 
experiment of Hausmann, who found that section of the nerves of the penis prevented erection 
in a stallion. The imperfect erection which occurs in the female is confiued to the corpora 
cavernosa clitoridis and the bulbi vestibuli. 
During erection, the passage from the 
urethra to the bladder is closed, partly by 
the swelling of the caput gallinaginis, and 
partly by the action of the sphincter 
urethra, which is connected with the deep 
transversus perinei. 
437. EMISSION AND RE- 
CEPTION OFTHE SEMEN. 
—In connection with the emission 
of the seminal fluid we must dis- 
tinguish two different factors: (1) 
its passage from the testicles to the 
vesiculae seminales; (2) the act of 
emission itself. The former is 
caused by the newly secreted fluid 
forcing on that in front of it, by 
the action of the ciliated epithe- 
lium (which lines the epididymis to 
the beginning of the vas deferens), 
and also by the peristaltic movements 
of the smooth muscular fibres of the 
vas deferens. Emission, however, 
requires strong peristaltic contrac- 
tions of the vasa deferentia and the 
vesiculae seminales, which are 
brought about by the reflex stimula- 
tion of the emission centre in the 
spinal cord (§ 362, 5). As soon as 
the seminal fluid reaches the urethra, 
there is a rhythmical contraction of 
the bulbo-cavernosus muscle (pro- 
duced by the mechanical dilatation 
of the urethra), whereby the fluid is forcibly ejected from the urethra. Both 
vasa deferentia and vesiculae do not always eject their contents into the urethra 
simultaneously. With moderate excitement the contents of only one may be 
discharged. The ischio-cavernosus and deep transverse perinei contract at the 
same time as the bulbo-cavernosus, although the former have no effect on the 
Anterior wall of the pelvis with the urogenital 
septum seen from the front. The corpus caver- 
nosum (4) with the urethra (3) is cut across 
below its exit from the pelvis. I, symphysis 
pubis; 2, dorsal vein of the penis; 5, part of 
the bulbo-cavernosus; t, deep transverseus peri- 
nei with its fascia (f); 6, vena profunda penis; 
7, artery and vein of the bulbo-cavernosus. 
Fig- 795- Sec. 437.] 
FERTILIZATION OF THE OVUM. 
1079 
act of ejaculation. In the female also, under normal circumstances, at the 
height of the sexual excitement there is a reflex movement corresponding to 
emission. It consists of a movement analogous to that in man. At first there 
is a reflex peristaltic movement of the Fallopian tube and uterus, proceeding 
from the end of the tube towards the vagina, and produced reflexly by the 
stimulation of the genital nerves. 
Dembo observed that stimulation of the anterior upper wall of the vagina in 
animals caused a gradual contraction of the uterus. By this movement, cor- 
responding to that of the vasa deferentia in man, a certain amount of the 
mucus normally lining the uterus is forced into the vagina. 
This is followed by the rhythmical contraction of the sphincter cunni 
(analogous to the bulbo-cavernosus), also of the ischio-cavernosus, and deep 
transversus perinei. The uterus is erected by the powerful contraction of its 
muscular fibres and round ligaments, while at the same time it descends towards 
the vagina, its cavity is more and more diminished, and its mucous contents are 
forced out. When the uterus relaxes after the stage of excitement, it aspirates 
into its cavity the seminal fluid injected into the vestibule (Aristotle, Bischoff'). 
But the suction of the greatly excited uterus is not necessary for the reception of the semen 
[Aristotle). The spermatozoa may wriggle by their own movements from the vagina into the 
orifice of the uterus (Kristeller). The cases of pregnancy where from some pathological causes 
(partial closure of the vagina or vulva) the penis has not passed into the vagina during coition, 
prove that the spermatozoa can tranverse the whole length of the vagina, and pass into the 
uterus. 
438. FERTILIZATION OF THE OVUM.—The ovum is fer- 
tilized by one spermatozoon passing into it. 
Swammerdam (f 1685) proved that contact of the semen with the ovum was necessary for 
fertilization. Spallanzani (1768) proved that the fertilizing agent was the spermatozoa, and not 
the clear filtered fluid part of the semen, and that the spermatozoa, even after being enormously 
diluted, were still capable of action. Martin Barry (1850) was the first to observe the entrance 
of a spermatozoon into the ovum of the rabbit. This occurs pretty rapidly, by a boring move- 
ment through the vitelline membrane yLeuckart). The entrance is effected either through the 
porous canals or the micropyle (Keber, p. 1067). 
The sticky surface of the ovum enables the spermatozoon to adhere to it. At the place 
where the head of the spermatozoon touches the yolk, there is formed to it an eleva- 
tion of the yolk. As soon as a spermatozoon has penetrated into the yolk, the other sperma- 
tozoa are prevented from entering the ovum, owing to the formation of a membrane on the sur- 
face of the yolk (Selenka). Thermal and chemical stimuli, and mechanical vibrations of unfer- 
tilized ova cause ova to lose their power of preventing more than one spermatozoa from entering 
an ovum (.Hertwig). 
Place of Fertilization.—The place where fertilization occurs is either the 
ovary, as indicated by the occurrence of abdominal pregnancy, or the Fallopian 
tube, and the numerous recesses in the latter afford a good temporary nidus for 
the spermatozoa. This view is supported by the occurrence of tubal pregnancy. 
Thus, the spermatozoa must be able to pass through the Fallopian tube to the 
ovary, which is probably brought about chiefly by the movements proper to the 
spermatozoa themselves. It is uncertain whether the peristaltic movements of 
the uterus and Fallopian tube are concerned in this process ; certainly ciliary 
movement is not concerned, as the cilia of the Fallopian tube act from above 
downwards. When once the ovum has passed unfertilized into the uterus, it is 
not fertilized in the uterus. It is assumed that the ovum reaches the uterus 
within 2 to 3 weeks (in the bitch, 8 to 14 days). 
Twins occur in 1 in 87 pregnancies, but oftener in warm climates; trip- 
lets, 1 : 7600 ; four at a birth, 1 : 330,000. More than six at a time have not 
been observed. The average number of pregnancies in a woman is 4^. 
Superfecundation.—By this term is understood the fertilization of two ova at the same 
menstruation, by two different acts of coition. Thus, a mare may throw a foal and a mule, 1080 
MATURATION OF THE OVUM. 
[Sec. 438. 
after being covered first by a stallion and then by an ass. A white and black child have been 
born as twins by a woman. 
Superfcetation is when a second impregnation takes place at a later period of pregnancy, as 
in the second or third month. This, however, is only possible in a double uterus, or when 
menstruation persists until the time of the second impregnation. It is said to occur frequently in 
the hare. 
Hybrids are produced when there is a cross between different species (horse, ass, zebra—dog, 
jackal, wolf—goat, ibex—goat, sheep—species of llama—camel, dromedary—tiger, lion—species 
of pheasant—goose, swan—carp, crucian—species of butterflies). Most hybrids are sterile, 
especially as regards the formation of properly formed spermatozoa; while the hybrid females 
are for the most part fertile with the male of both parents, e. g., the mule; but the characters 
of the offspring tend to return to those of the species of the parents. Very few hybrids are 
fertile when crossed by hybrids. In many species of frogs the absence of hybrids is accounted 
for by the mechanical obstacles to fertilization of the ova. 
Tubal Migration of the Ovum.—Under exceptional circumstances, the 
ovum discharged from a ruptured Graafian follicle passes into the Fallopian tube 
of the other side, as is proved by the occurrence of tubal pregnancy and preg- 
nancy of an abnormal rudimentary horn of the uterus, in which case the true 
corpus luteum is found on the other side of the ovary. This is spoken of as 
“external migration” (Kussmaul, Leopold). This observation coincides 
with experiment, as granular fluids, e. g., China-ink, when injected into the 
peritoneal cavity, pass into both Fallopian tubes, and are carried by the ciliated 
Fig. 796.—Formation of polar globules in a star-fish (Asterias glacialis). A, ripe ovum, with 
eccentric germinal vesicle and spot; B-E, gradual metamorphosis of germinal vesicle and 
spot, as seen in the living egg, into two asters; F, formation of first polar globule, and 
withdrawal of the remaining part of the nuclear spindle within the ovum ; G, surface view 
of living ovum with view of first polar globule; H, formation of second polar globule , 1, 
a later stage, showing the remaining internal part of the spindle in the form of two clear 
vesicles ; K, ovum with two polar globules and radial striae around the female pronucleus; 
L, extrusion of polar globule. (Gedeles: A-K, after Fol; L, after O. Herlwig). Fig. 
797.—Egg of Scorpaena scrofa. The germinal vesicle is extruding a polar globule, and 
withdrawing towards the centre of tbe ovum. Near it is the male pronucleus. 
Fig. 796. 
Fig. 797. 
epithelium to the uterus (.Pinner). In animals with a double uterus with two 
orifices, the ova may migrate through the os of the one into the other uterus, a 
condition which is spoken off as “ internal migration.” 
439. IMPREGNATION—CLEAVAGE—LAYERS OF THE 
EMBRYO.—Maturation of the Ovum.—In birds and mammals, im- 
portant changes occur in the ovum before impregnation. The germinal 
vesicle comes to the surface and disappears from view, while the germinal spot 
also disappears. In place of the germinal vesicle, a spindle-shaped body 
appears. The granular elements of the protoplasmic vitellus arrange them- 
selves around each of the two poles of the spindle, in the form of a star, the 
double-star, or diaster of Fol—nuclear spindle (figs. 796, 797). When this 
takes place, th z. peripheral pole of the nucleus or altered germinal vesicle, along 
with some of the cellular substance of the ovum, protrudes upon the surface of Sec. 439.] 
MATURATION OF THE OVUM. 
1081 
the vitellus, where they are nipped off from the ovum in the form of small cor- 
puscles, just like an excretory product (fig. 798). These bodies, which are not 
made use of in the further development and growth of the ovum, are called 
polar or directing globules (.Fol, Biitschli, O. Hertwig), although the elimi- 
nation of small bodies from the yolk was known to Dumortier [1837], Bischoff, 
P. J. van Beneden, Fritz Muller [1848], Rathke, and others. The remaining 
part of the germinal vesicle stays within the vitellus and travels back towards 
the centre of the ovum, to form the female pronucleus (O. Hertwig, Fol, 
Selenka, E. van Beneden). [Before, how- 
ever, the altered germinal vesicle travels 
downwards again into the substance of the 
ovum, it divides again as before, and from 
it is given off the second polar globule, and 
then the remainder of the germinal vesicle 
forms the female pronucleus (fig. 796). At 
the same time the vitellus shrinks some- 
what within the vitelline membrane.] 
Impregnation.—As a rule, only one 
spermatozoon penetrates the ovum, and as 
it does so, it moves towards the female 
pronucleus, while its head becomes sur- 
rounded with a star; it then loses its head 
and cilium, or tail, the latter only serving 
as a motor organ, while the remaining middle piece wells up to form a 
second new nucleus, the male pronucleus (Ah/, Selenka), or sperm nucleus 
(•.Hertwig). According to Flemming, it is the anterior part of the head, and 
Fig. 798. 
Egg of a star-fish (Asteracanthion) with 
two extruded polar globules. Male 
and female pronuclei near each other. 
Fig. 799. 
Segmentation of a rabbit’s ovum, a, two-celled stage; b, four-celled stage; c, eight-celled stage; 
de, many blastomeres, showing the more rapid division of the out-layer cells, and the gradual 
enclosure of the inner-layer cells; ect, outer-layer cells; ent, inner-layer cells; pgl, polar 
globules; zp, zona pellucida. 
according to Rein and Eberth, it is the head which is so changed. Thereafter, 
the male and female pronucleus unite, undergoing amoeboid movements at the 
same time, to form the new nucleus of the fertilized ovum. The female pro- 
nucleus receives the male pronucleus in a little depression on its surface. There- 
after the yolk assumes a radiate appearance (.Rein). [The union of the repre- 1082 
CLEAVAGE OF THE YOLK. 
[Sec. 439. 
sentatives of the male and female elements forms the first embryonic segmenta- 
tion sphere or blastosphere, which divides into two cells, and these again 
into four, and so-on (fig. 799).] 
In Echinoderms, O. Hertwigand Fol observed that several embryos were formed when, under 
abnormal conditions, several spermatozoa penetrated an ovum. The male pronuclei, formed 
from the several spermatozoa, then fused each with a fragment of the female pronucleus. 
Under similar circumstances, Born observed in amphibians abnormal cleavage, but no further 
development. 
Cleavage of the Yolk.—In an ovum so fertilized the yolk contracts some- 
what around the newly-formed nucleus, so that it becomes slightly separated 
from the vitelline membrane, and for the first time the nucleus and the yolk 
divides into two nucleated spheres. This process is spoken of as a complete 
cleavage or fission (fig. 799). Each of these two cells again divides into 
two, and the process is repeated, so 
that 4, 8, 16, 32, and so on, spheres 
are formed (fig. 800). This consti- 
tutes the cleavage of the yolk, and the 
process goes on until the whole yolk is 
subdivided into numerous small, nu- 
cleated spheres, the “ mulberry 
mass” or “segmentation 
spheres” or “morula,” or the 
protoplasmic primordial spheres (20 to 
25 /x) which are devoid of an envelope. [Each cell divides by a process of 
mitosis. According to Van Beneden, the segmentation begins in 1-2 hours after 
the union of the pronuclei, and the process is complete in about 75 hours. 
These primitive cells, from which all the tissues of the future embryo are formed, 
are called blastomeres.] 
Variation of Lines of Cleavage.—According to the observations of Pfliiger, the ova of the 
frog can be made to undergo cleavage in very different directions, according to the angle 
between the axis of the egg and the line of gravitation. This of course we can alter as we 
Fig. 800. 
Cleavage of the yolk of the egg of Anchylo- 
stomum duodenale. 
Fig. 8oi.—Blastodermic vesicle of a rabbit, ect, ectoderm, or outer layer of cells; ent, inner 
layer of cells. Fig. 802.—Pr, primitive streak; P, medullary groove; U, first proto- 
vertebra 
Fig. 801. 
Fig. 802. 
please, by placing the eggs at any angle to the line of gravitation. By the axis of the ovum is 
meant a line connecting the centre of the black surface and the middle of the white part, which, 
in the fertilized ovum, is always vertical. In such cases of abnormal cleavage the deposition of 
the organs takes place from other constituents of the egg than those from which they are formed 
under normal conditions. Under normal circumstances, according to Roux, the first line of 
cleavage in the frog is in the same direction as the central nervous system. The second inter- Sec. 439*] 
BLASTODERM. 
sects the first at a right angle, so as to divide the mass of ovum into two unequal parts, the 
larger of which forms the anterior part of the embryo. 
Blastoderm.—During this time the ovum is enlarging by absorption of 
fluid into its interior. All the cells, from mutual pressure against each other, 
become polyhedral, and are so arranged as to form a cellular envelope or blad- 
der, the blastoderm, or germinal membrane, which lies on the internal 
surface of the vitelline membrane (De Graaf, v. Baer, Bischojf, Coste). A 
small part of the cells not used in the formation of the blastoderm is found on 
some part of the latter. [In the ovum of the bird, where there is only partial 
segmentation, the blastoderm is a small round body resting on the surface of 
the yolk, under the vitelline membrane, so that it does not completely surround 
the yolk, or a hollow cavity, as in mammals. In mammals, this cavity is called 
the segmentation cavity.] The hollow sphere, composed of cells, is called 
the blastodermic vesicle or blastula (Hceckel, Reichert) (fig. 803), and in 
the human embryo it is formed at the 10th to 12th day, in the rabbit at the 4th, 
the guinea-pig at the 
the cat 7th, dog 
nth, fox 14th, rumi- 
nantia at the 10th to 
12th day, and the 
deer at the 60th day. 
The blastula of am- 
phioxus is represented 
diagrammatically i n 
fig. 803, 1, as a single 
layer of cells enclos- 
ing a spherical cavity. 
The blastula under- 
goes changes whereby 
two cellular layers are 
formed, by the invagi- 
nation of a part of the 
surface (fig. 803, 2), 
which goes on until it 
touches the inner sur- 
face of the part of the 
layer lying opposite to 
it (fig. 803, 3, 4). In 
this stage it is called gastrula (.Hceckel), the outer layer is the ectoderm or 
epiblast, the inner the endoderm or hypoblast, the opening is the blasto- 
pore, and the cavity the primitive intestine. In vertebrates the blastopore 
closes completely. 
The formation of the hypoblast (fig. 803, 6, Zi) is shown clearly by the in- 
vagination in the region of the blastopore in the ovum of the lamprey or 
petromyzon, and shown diagrammatically in fig. 803, 5, 6, 7, where one can see 
how, from the blastopore (u) invagination takes place until the epiblast (e), and 
hypoblast (/z), are arranged the one over the other, and below the hypoblast is 
the primitive intestinal cavity. 
It is assumed that the first stages in the embryo exhibit similar appearances 
and transformation in the vertebrata. According to Van Beneden, the ovum 
after complete segmentation consists of two layers, the epiblast (fig. 804, I, e), 
which lies next the zona pellucida, z, and the hypoblast (h). The blastopore 
or primitive mouth leads to the cavity of the ovum. When the blastoderm 
grows to 2 mm. (rabbit), whereby the vitelline membrane is distended to a 
Fig. 803. 
1-4, Formation of the hypoblast by invagination of the blastula 
and the gastrula (4) thereby produced in Amphioxus. 5, The 
beginning, and 6, the continuation of the formation of the hypo- 
blast by invagination in Petromyzon. u, blastopore; e, epiblast; 
h, hypoblast in vertical section. 7, The ovum at this stage seen 
from the side; r, neural groove. BLASTODERM. 
[Sec. 439. 
very thin, delicate membrane, then at one part of it there appears the ger- 
minal area, the area germinativa, or the embryonal shield (Coste, Kollikef). 
Minute investigation discovers at its margin a small elongated spot (u), from 
I. Ovum of rabbit. Z, zona pellucida; e, epiblast; h, hypoblast; u, blastopore. II. Ovum 
of rabbit with the clear embryonal area; at u is the first formation of the primitive streak. 
III. Ebr, Position of the embryo at a slightly older stage; pr, primitive streak. IV, more 
advanced still (7th day). Above the primitive streak (pr) is the first indication of the 
neural groove. 
Fig. 804. 
which the duplication of the blastoderm proceeds, and which is regarded as the 
blastopore. From the blastopore the hypoblast continues to grow in the area 
of the embryonal area, so that the blastoderm ultimately forms a completely 
Fig. 805. 
A, Blastoderm of a hen’s egg at the first hour of incubation, df, area opaca; hf, area pel- 
lucida; Es, position of embryo; u, position from which the hypoblast becomes in- 
vaginated, or where the blastopore has a sickle-shaped form (s). B, preparation slightly 
more advanced; pr, primitive streak. E, Longitudinal section of a blastoderm at this 
stage; u, blastopore; e, epiblast; /&, hypoblast, and below the latter the primitive intes- 
tine e. C, pr, primitive streak, and the first appearance of the amnion, af. D, embryonal 
shield with the neural groove, rf, formed in front of the primitive streak,pr (18 hours). F, 
hen’s blastoderm at 33 hours; pr, primitive streak gradually disappearing; df, opaque, and 
hf, clear area; hb„ hb/n hb///t the primary cerebral vessels; us, protovertebrae; ch, chorda 
dorsalis. 
closed sac with double walls. The position of the blastopore (II, u) becomes 
later the primitive streak (III pr). 
The primitive streak, like the blastopore in vertebrata, is a temporary structure. 
The embryonal area soon becomes more pear-shaped, and afterwards biscuit- 
shaped. The parts of the embryonal area adjoining the blastoderm become Sec. 439.] 
PRIMITIVE STREAK AND GROOVE. 
1085 
more transparent, so that there is a clear area—area pellucida—in the centre, 
which is surrounded by a darker area—area opaca. At the same time the sur- 
face of the zona pellucida develops numerous small, hollow, structureless villi, 
and is called the primitive chorion (fig. 811, I and vii). 
In mesoblastic ova, e. g., birds, there is only partial cleavage of the yolk. 
The cells so produced unite to form the blastoderm, which consists of two 
layers, the epiblast and hypoblast. In the blastoderm of the fowl a structure 
corresponding to the blastopore has been discovered (fig. 805, A, u). At first 
it is short, but it gradually elongates, and is continued or becomes the primitive 
streak (B, C). In birds also the hypoblast seems to be formed by invagina- 
tion, and is shown in fig. 805, E, which represents a sagittal section of a blas- 
toderm. From the blastopore (u) the hypoblast is pushed under the epi- 
blast, and both membranes rest on the cavity of the primitive intestinal canal 
(F) which is filled with fluid. 
At the posterior part, or narrow end of the embryonic shield, the primitive 
streak (fig. 802, I, Pr) appears at first as an elongated opaque circular thick- 
ening, and later as a longer streak or groove, the primitive groove. [The 
opacity is due to the fact that there are several layers of cells in this region 
(fig. 806). In a transverse section through the primitive streak, three layers of 
Transverse section of the primitive streak of a fowl’s blastoderm, ep, epiblast; hy, hypoblast; 
m, mesoblast; pv, primitive groove; yh, yolk of germinal wall. 
Fig. 806. 
cells are seen. They form part of the middle layer or mesoblast, and are 
originally derived from 
the hypoblast. These cells 
fuse with those of the epi- 
blast. The remainder of 
the hypoblastic cells retain 
their stellate character.] 
At the same time a new 
layer of cells is developed 
between the epiblast and 
hypoblast, the mesoderm 
or mesoblast (fig. 806, 
I), which soon extends 
over the embryonal area, 
and into the blastoderm. 
[There has been much dis- 
cussion as to the origin of the mesoblast, but in vertebrates it seems to be 
originally developed from the hypoblast. Fig. 807 shows a portion of the 
Fig. 807. 
Transverse section of an embryo newt, a, mesenteron; ax. 
hy, axial hypoblast, forming the notochord; be, coelom or 
body-cavity; ep, epiblast; hy, digestive hypoblast; so.m, 
somatic mesoblast; sp.m, splanchnic mesoblast; n.p, 
neural plate. 1086 
LAYERS OF THE BLASTODERM. 
[Sec. 439. 
hypoblast in its axial part, in process of forming the notochord, which is 
described as mesoblastic.] Blood-vessels are formed within the mesoblast, and 
are distributed over the blastoderm to form the area vasculosa. 
Medullary Groove.—A longitudinal groove, the medullary groove, is 
formed at the anterior part of the embryonal shield, but it gradually extends 
posteriorly, embracing the anterior part of the primitive streak with its divided 
posterior end, while the primitive streak itself gradually becomes relatively and 
absolutely smaller and less distinct, until it disappears altogether (fig. 802, I, 
and II, Pr). 
The position of the embryo is indicated by the central part becoming more 
transparent,—the area pellucida,—which is surrounded by a more opaque 
part—the area opaca. [The area opaca rests directly upon the white yolk in 
the fowl, and it takes no share in the formation of the embryo, but gives rise to 
structures which are temporary, and are connected with the nutrition of the 
embryo. The embryo is formed in the area pellucida alone.] 
From the epiblast \neuro-epidermal layer'] are developed the central nervous 
system and epidermal tissues, including the epithelium of the sense-organs. 
From the mesoblast are formed most of the organs of the body [including 
the vascular, muscu- 
lar, and skeletal sys- 
tems, and according 
to some, the connec- 
tive-tissue. It also 
gives rise to the gen- 
erative glands and ex- 
cretory organs]. 
From the hypo- 
blast epithelio-glandu 
lar layer [which is the 
secretory layer], arise 
the intestinal epithe- 
lium, and that of the 
glands which open into the intestine. The notochord is also formed from its 
axial portion. [The mouth and anus, being formed by an inpushing of the 
epiblast, are lined by epiblast, and are sometimes called the stomodaeum 
and proctodaeum respectively.] 
[Structure of the Blastoderm (fig. 808).—Originally it is composed of 
only two layers, and in a vertical section of it the epiblast consists of a single 
row of nucleated granular cells, arranged side by side, with their long axes 
placed vertically. The hypoblast consists of larger cells than the foregoing, 
although they vary in size. They are spherical and very granular, so that no 
nucleus is visible in them. The cells form a kind of network, and occur in 
more than one layer, especially at the periphery. It rests on white yolk, and 
under it are large spherical refractive cells, spoken of as formative cells (r).] 
The cells of the epiblast, and especially those of the hypoblast, nourish themselves by the di- 
rect absorption and incorporation of the constituents of the yolk into themselves. The amoeboid 
movements of these cells play a part in the process of absorption. The absorbed particles are 
changed, or, as it were, digested within the cells, and the product used in the processes of growth 
and development (.Kollmann). 
Division of Cells.—Although a cell is defined as a “nucleated mass of 
living protoplasm,” recent researches have shown that, from a histological as 
well as from a chemical point of view, a cell is really a very complex structure. 
The apparently homogeneous cell-substance is traversed by a fine plexus of 
fibrils, with a homogeneous substance in its meshes, while a similar network 
of fibrils exists within the nucleus itself (fig. 809).] 
Fig. 808. 
Vertical section of part of the unincubated blastoderm of a hen. 
a, epiblast; b, hypoblast; c, formative cells resting on white 
yolk; f archenteron. Sec. 439.] 
DIVISION OF CELLS. 
1087 
{The nucleus of a typical resting cell is a spherical vesicle, consisting of the 
following parts :— 
(1) An outer investing nuclear membrane. 
(2) A plexus of fibrils in its substance or chromatin network. 
(3) Nucleoli. 
(4) A semi-liquid substance in the meshes of the network. 
The plexus of fibrils has also been called—“the nuclear network of 
fibrils ” “ chromatin,” “ nucleoplasm,” “ karyoplasma,” and “ karyo- 
miton.” The network stains readily with pigments, hence the name “ chro- 
matin ” given to it by Flemming. It seems to be identical with nuclein, and 
the nodal points of the network give a dotted or granular appearance to the 
nucleus, especially when it is examined with a lofv power. In the meshes of 
the network lie nucleoli, which seem to differ in constitution, and perhaps in 
function. According to Flemming, there are principal and accessory nucleoli 
in some nuclei. In Carnoy’s nomenclature the several parts are spoken of as a 
fine reticulum of fibrils, enclosing in its meshes a fluid—the enchylema—which 
contains various particles in suspension. Under the term “ chromatin ” is in- 
cluded the network and the nucleoli. The nuclear fluid or matrix or substance 
lying in the meshes of the nucleus has 
been called “ interfibrillar substance ” 
and achromatin, because it does not 
stain readily with dyes. Part of the 
achromatin forms the “ nuclear spin- 
dle ” in the process of mitosis. It is 
to be noted that the names “ chroma- 
tin ” and “achromatin” depend on 
the histological and not on the chemi- 
cal characters of these structures.] 
[Direct Cell-Division.—A cell 
may divide directly, as it were, by 
simple cleavage, and in the process 
the nucleus usually divides before the 
cell protoplasm. This is the process 
of amitosis. The nucleus becomes 
constricted in the centre, has an hour- 
glass shape, and soon divides into 
two.] 
[Indirect Cell-Division. — Re- 
cent observations, confirmed by a great 
number of investigators, conclusively 
prove that the process of division in 
cells is a very complicated one, the 
changes in the nucleus being very re- 
markable. The terms karyokinesis, 
mitosis, or indirect division have been applied to this process. Fig. 810 
shows the successive changes that take place in the nucleus. Suppose a nucleus 
to be in the resting stage; when division is about to take place, the chroma- 
tin or intranuclear network (A, B) passes into a convolution of fibrils, 
while the nuclear envelope becomes less distinct, the fibrils at the same time 
becoming thicker and forming loops, which gradually arrange themselves 
around a centre (C and D) in the form of a wreath, rosette, or spirem(C). 
Each loop then splits longitudinally, and at the same time the achromatic 
spindle or nuclear spindle appears, so that the nucleus exhibits two poles 
corresponding to the poles of the spindle. The chromatin threads pass towards 
Fig. 809. 
Fig. 809.—Typical nucleated cell of the intesti- 
nal epithelium of a flesh-maggot, me, mem- 
brane of cell; mn, membrane of nucleus; pc, 
cellular protoplasm, with the radiating reticti- 
lum, and the enchylema enclosed in its meshes; 
pn, plasma of nucleus; bn, nuclear filament 
showing numerous twists. 1088 
MITOSIS. 
[Sec. 439. 
the centre of the nucleus, where they are grouped at its equator and form the 
equatorial stage or monaster (D). The threads or loops produced by division 
of the original loops now tend to pass towards the two poles of the nucleus, i. <?., 
towards the two poles of the nuclear spindle, forming the pithode or barrel 
stage (E). This stage has been called by Waldeyer metakinesis. The two 
groups of loops then separate still further, and arrange themselves so as to form 
a diaster, or double star, or daughter stars, the two groups being separated 
by a substance called the equatorial plate. Each of the groups of fibrils be- 
comes more elongated, and forms a nuclear spindle, which indicates the position 
of a new nucleus. The protoplasm separates into two parts. In each of these 
parts the chromatin rearranges itself into an irregular coil, and the whole is 
called dispirem (G), and when division is complete, the chromatin filaments 
assume the form seen in a resting nucleus. This whole complex process may be 
accomplished in 1 to 4 hours. The separate groups of fibrils again become 
convoluted, each group gets a nuclear membrane, while the cell protoplasm 
divides, and two daughter nuclei are obtained from the original cell.] 
Fig. 810. 
Mitosis. A, nuclear reticulum, resting state; B, preparing for division; C, wreath stage, with 
appearance of nuclear spindle; D, monaster stage; E, barrel stage with the nuclear 
spindle; F, diaster stage; G, daughter wreath stage; H, daughter cells, passing to resting 
stage. 
[The following scheme represents some of the more important changes : — 
Mother Nucleus. 
1. Network. 
2. Convolution. 
3. Wreath or Spirem. 
4. Aster. 
Daughter Nuclei. 
5. Diaster. 
6. Dispirem. 
7. Convolution. 
8. Network. 
Equatorial grouping of chromatin and nuclear spindle.] 
440. STRUCTURES FORMED FROM THE EPIBLAST.— 
Laminae Dorsales.—The medullary groove upon the epiblast (also called 
outer, serous, sensorial, corneal, or animal layer) becomes deeper (fig. 8n, II). 
The two longitudinal elevations or laminae dorsales consist of a thickening 
of the epiblast, and grow up over the medullary groove, thus forming the 
neural groove. Ultimately, however, the laminae dorsales meet each other 
and coalesce by their free edges in the middle line posteriorly. Thus, the open 
groove is gradually changed into a closed tube—the medullary or neural 
tube (fig. 8n, III). The cells next the lumen of the tube ultimately become 
the ciliated epithelium lining the central canal of the spinal cord, while the 
other cells of the nipped-off portion of the epiblast form the ganglionic part of 
the central nervous system and its processes. Sec. 440.] 
STRUCTURES FORMED FROM THE EPIBLAST. 
1089 
Fig. 811. 
I, The three layers of the blastoderm of a mammalian ovum—Z, zona pellucida ; E, epiblast; 
m,mesoblast; <?, hypoblast. II, Section of an embryo, with six protovertebrse at the istday 
—M, medullary groove; h, somatopleure; U, protovertebra; c, chorda dorsalis; S, the 
lateral plates divided into two ; e, hypoblast. Ill, Section of an embryo chick at the 2d 
day in the region behind the heart—M, medullary groove; pouter part of somatopleure ; 
u, protovertebra ; c, chorda; tv, Wolffian duct; K, coelom; x, inner part of somatopleure; 
y, inner part of splanchnopleure ; A, amniotic fold; a, aorta ; e, hypoblast. IV, Scheme 
of a longitudinal section of an early embryo. V, Scheme of the formation of the head- and 
tail-folds—r, head-fold ; D, anterior extremity of the future intestinal tract; S, tail-fold, 
first rudiment of the cavity of the rectum. VI, Scheme of a longitudinal section through 
an embryo after the formation of the head- and tail-folds—A o, omphalo-mesenteric arteries; 
Vo, omphalo mesenteric veins; a, position of the allantois; A, amniotic fold. VII, Scheme 
of a longitudinal section through a human ovum—Z, zona pellucida; S, serous cavity; r, 
union of the amniotic folds; A, cavity of the amnion ; a, allantois; N, umbilical vesicle ; m, 
mesoblast; h, heart; U, primitive intestine. VIII, Schematic transverse section of the 
pregnant uterus during the formation of the placenta ; U, muscular wall of the uterus; p, 
uterine mucous membrane, or decidua vera; b, maternal part of the placenta, or decidua 1090 
CEREBRAL VESICLES. 
[Sec. 440. 
serotina; r, decidua reflexa ; ch, chorion ; A, amnion; n, umbilical cord ; a, allantois, with 
the urachus; N, umbilical vesicle, with D, the omphalo-mesenteric duct; tt, openings of 
the Fallopian tubes; G, canal of the cervix uteri. IX, Scheme of a human embryo, with 
the visceral arches still persistent—A, amnion ; V, fore-brain; M, mid brain ; H, hind-brain ; 
N, after-brain ; U, primitive vertebrae ; a, eye; p, nasal pits; S, frontal process ; y, internal 
nasal process; n, external nasal process; r, superior maxillary process of the 1st visceral 
arch ; I, 2, 3, and 4, the four visceral arches, with the visceral clefts between them; 0, audi- 
tory vesicle ; h, heart, with e, primitive aorta, which divides into five aortic arches; f, de- 
scending aorta; om, omphalo-mesenteric artery ; b, the omphalo-mesenteric arteries on the 
umbilical vesicle ; c, omphalo-mesenteric vein ; L, liver, with venae advehentes and reve- 
hentes ; D, intestine ; i, inferior cava ; T, coccyx ; all, allantois, with z, one umbilical artery, 
and x, an umbilical vein. 
Primary Cerebral Vesicles.—[The laminae dorsales unite first in the region 
of the neck of the embryo, and soon this is followed by the union of those over 
the future head.] The medullary tube is not of uniform diameter, for at the 
anterior end it becomes dilated and mapped out by constrictions into the pri- 
mary vesicles of the brain, which at first are arranged, one behind the other, in 
the following order, each one being smaller than the one in front of it: the 
fore-brain (representing 
the structures from which 
the cerebral hemispheres 
are developed); the mid- 
brain (corpora quadrige- 
mina) ; the hind - brain 
(cerebellum); and the af- 
ter-brain (medulla oblon- 
gata) ; which is gradually 
continued into the spinal 
cord (fig. 811, IV and V). 
The posterior part of the 
medullary tube has a dilata- 
tion at the lumbar enlarge- 
ment. In birds, the medul- 
lary groove remains open in 
this situation to form a 
lozenge-shaped dilatation, 
the sinus rhomboidalis. 
While the neural tube is 
being formed, the primitive 
streak gradually diminishes, 
and at last disappears en- 
tirely (fig. 805, F). 
Cranial Flexures.— 
The anterior part of the 
medullary tube curves on 
itself, especially at the junc- 
tion of the spinal cord and 
oblongata, between the mid- 
brain and hind-brain, and 
again almost at right angles 
between the fore-brain and 
mid-brain. [Thus, a dis- 
placement of the primary 
vesicles is produced, and the 
head of the future embryo is mapped At first all the cerebral vesicles are 
devoid of convolutions and sulci. On each side of the fore-brain there grows 
Embryo fowl of the 2d day, x S°- Ao, area opaca; Ap, 
area pellucida; Hh, hind-brain ; Mh, mid-brain; V/i, 
fore-brain ; om, omphalo-mesenteric veins ; omr, point 
where the closure of the neural groove is travelling back- 
wards, and to the protovertebrae; Vw, muscle-plates; Rf 
posterior part of widely-open neural groove; Rw, neural 
ridge ; vAf, anterior amniotic fold. 
Fig. 812. Sec. 440.] 
HYPOBLAST AND MESOBLAST. 
1091 
out a stalked hollow vesicle (fig. 811, VI), the primary optic vesicle. The 
remainder of the epiblast forms the epidermal covering of the body. At an 
early period we can distinguish the stratum corneum and the Malpighian layer 
of the skin (§ 283) : from the former are developed the hairs, nails, feathers, etc. 
Partial Cleavage.—Only a partial cleavage takes place in the eggs of birds and in mero- 
blastic ova, i. e., only the zvhile yolk in the neighborhood of the cicatricula divides into nume- 
rous segmentation spheres (Coste, 1848). The cells arrange themselves in two layers lying one 
over the other. The upper layer or epiblast is the larger, and contains small pale cells; the 
lower layer, or hypoblast, which at first is not a continuous layer, ultimately forms a continuous 
layer, but its periphery is smaller than the upper layer, while its cells are larger and more 
granular. 
Between the epiblast and hypoblast there is formed, from the primitive streak, as a product 
of cell proliferation, the mesoblast, which is said by Kolliker to be due to the division of the 
cells of the epiblast. It gradually extends in a peripheral direction between the two other 
layers. All the three layers grow at their periphery. In the mesoblast blood-vessels are de- 
veloped. All the three layers, as they grow, come ultimately to enclose the yolk, so that their 
margins come together at the opposite pole of the yolk. 
Fig. 813. 
Transverse section of an embryo duck, am, amnion ; ao, aorta; ca.v, cardinal vein; ch, noto- 
chord; hy, hypoblast; ms, muscle-plate; so, somatopleure; sp, splanchnopleure; sp.c, 
spinal-cord ; sp.g, spinal ganglion ; si, segmental tube; wd, Wolffian (segmental) duct. 
44i. STRUCTURES FORMED FROM THE HYPOBLAST 
AND MESOBLAST.—The hypoblast forms, immediately under the me- 
dullary groove, a cylindrical cellular cord, the chorda dorsalis, or noto- 
chord, which is thicker at the tail than at the cephalic end (fig. 811, II, III, c). 
It is present in all vertebrata, and also in the larval form of the ascidians, but 
in the latter it disappears in the adult form (Kowalewsky). In man it is rela- 
tively small. It forms the basis of the bodies of the vertebrae, and around it, 
as a central core, the substance of the bodies of the vertebrae is deposited, so 
that they are strung on it, as it were, like beads on a string. After it is formed, 
it becomes surrounded by a double sheath-like covering (Gegenbaur, Kolliker). 
The hypoblast does not undergo any further change at this time; it applies 
itself to the inner layer of the mesoblast, as a single layer of cells, to form the 
splanchnopleure. 1092 
PROTO VERTEBRAE. 
[Sec. 441. 
Protovertebrae.—The cells of the mesoblast, on each side of the chorda, 
arrange themselves into cubical masses, always disposed in pairs behind each 
other, the protovertebrae (fig. 8n, U and u, 812, U, w). The first pair 
correspond to the atlas. At a later period each protovertebra shows a marginal 
cellular area and a nuclear area (fig. 811). Only part of it goes to form a 
future vertebra. The part of the mesoblast lying external to the protovertebrae, 
the lateral plates (fig. 811, II, s'), splits into two layers, an upper one and a 
lower one, which, however, are united by a median plate at the protoverte- 
brae. The space between the two layers of the mesoblast is called the pleuro- 
peritoneal cavity, or the coelom of Haeckel (fig. 811, III, K). The upper 
layer of the lateral plate becomes united to the epiblast, and forms the cutaneo- 
muscular plate of German authors, or the somatopleure (fig. 811, III, x; 
fig. 813, so), while 
the inner one unites 
with the hypoblast 
to form the intesti- 
nal plate of German 
authors, or the 
splanchnopleure 
(fig. 811, III, y; 
fig. 813, sf). On 
the surfaces of these 
plates, which are 
directed towards 
each other, the en- 
dothelium lining 
the pleuro-perito- 
neal cavity is developed. On the surface of the median plate, directed towards 
the coelom, some cylindrical cells, the “germ epithelium” of Waldeyer, 
remain, which form the ovarian tubes and the ova (§ 438). 
According to Remak, the skin, the muscles of the trunk, and the blood-vessels, and according 
to His, only the musculature of the trunk, are derived from the somatopleure. Both observers 
agree that the splanchnopleure furnishes the musculature of the intestinal tract. 
Parablastic and Archiblastic Cells.—According to His, the blood-ves- 
sels, blood, and connective-tissue are not developed from true mesoblastic cells, 
but he asserts that for this purpose certain cells wander in from the margins of 
the blastoderm between the epiblast and hypoblast, these cells being derived 
from outside the position of the embryo, from the elements of the white yolk. 
His calls these structures parablastic, in opposition to the archiblastic, which 
belong to the three layers of the embryo. Waldeyer also adheres to the para- 
blastic structure of blood and connective-tissue, but he assumes that the mate- 
rial from which the latter is formed is continuous protoplasm, and of equal value 
with the elements of the blastoderm. 
[Formation of Mesoblast.—According to Hertwig in the lower verte- 
brates, the chorda and both walls of the coelom are derived by protrusion from 
the hypoblast, as is shown schematically in fig. 814. In I is the beginning of 
the median protrusion (for the chorda) and the two lateral ones (for the walls 
of the coelom, but still communicating freely with the hypoblast. In II the 
part where the protrusion occurs is narrowed. In III the chorda is separated 
and appears in transverse section as a round body. In the same way the walls 
of the coelom have separated, and show two plates or layers—the somato- 
pleure, and splanchnopleure, and between both is the pleuro-peritoneal cavity. 
[ The following table modified from Quain shows the structures developed 
from each of the4hree blastodermic layers (p. 1086): — 
I. 
III. 
Fig. 814. 
Scheme of the formation of the chorda and coelom by invagination 
from the hypoblast, after Hertwig. Sec. 441.] 
STRUCTURES FORMED FROM THE BLASTODERM. 
From the Epiblast. 
The central nervous system (brain and spinal cord): the peripheral and sympathetic nerves. 
The epithelium of the organs of special sense. 
The epidermis and its appendages, hairs and nails. 
The epithelium of all the glands opening on the surface of the skin (mammary, sweat and 
sebaceous glands). 
The muscular fibres of the sweat-glands. 
' The epithelium of the mouth (except that covering the tongue and the adjacent posterior part 
of the floor of the mouth, which is derived from the hypoblast) and that of the glands opening 
into it. The enamel of the teeth. 
The epithelium of the nasal passages, of the adjacent upper part of pharynx and of all the 
cavities and glands opening into the nasal passages. 
From the Mesoblast. 
The urinary and generative organs (except the epithelium, bladder and urethra). 
All the voluntary and involuntary muscles of the body (except the muscular fibres of the 
sweat-glands). . 
The whole of the vascular and lymphatic system including the serous membranes and spleen. 
The skeleton and all the connective-tissue structures of the body. 
From the FIypoblast. 
The epithelium of the alimentary canal from the back of the mouth to the anus and that of all 
the glands which open into this part of the alimentary tube. 
The epithelium of the Eustachian tube and tympanum. 
The epithelium of the bronchial tubes and air-sacs of the lungs. 
The epithelium lining the vesicles of the thyroid body. 
The epithelium nests of the thymus. 
The epithelium of the urinary bladder and urethra.] 
442. FORMATION OF EMBRYO, HEART, PRIMITIVE 
CIRCULATION.—Head- and Tail-Folds.—Up to this time the em- 
bryo lies with its three layers in the plane of the layers themselves. The 
cephalic end of the future embryo is first raised above the level of this plane 
(fig. 811, V). In front of, and under the head, there is an inflection or tuck- 
ing in of the layers, which is spoken of as the head-fold (V, r). [It gradu- 
ally travels backwards, so that the embryo is raised above the level of its sur- 
roundings.] The raised cephalic end is hollow, and it communicates with the 
space in the interior of the umbilical vesicle. The cavity in the head is spoken 
of as the head-gut or fore-gut (fig. 811, V, D). The formation of the fore- 
gut, by the elevation of the head from the plane of the three layers, occurs on 
the second day in the chick, and in the dog on the 22d day. The tail-fold is 
formed in precisely the same way, in the chick on the third day, and in the 
dog on the 22d day. The tail-fold, S, also is hollow, and the space within it 
is the hind-gut, d. Thus, the body of the embryo is supported or rests on a 
hollow stalk, which at first is wide, and communicates with the cavity of the 
umbilical vesicle. This duct or communication is called the omphalo- 
mesenteric duct, or the vitello-intestinal or vitelline duct. The sac- 
cular vesicle attached to it in mammals is called the umbilical vesicle (fig. 
811, VII, N), while the analogous much larger sac in birds, which contains the 
yellow nutritive yolk, is called the yolk-sac. The omphalo-mesenteric or 
vitelline duct in course of time becomes narrower, and is ultimately obliterated 
in the chick on the fifth day. The point where it is continuous with the ab- 
dominal wall is the abdominal umbilicus, and where it is inserted into the prim- 
itive intestine, the intestinal umbilicus. 
[Sometimes part of the vitelline duct remains attached to the intestine, and may prove danger- 
ous by becoming so displaced as to constrict a loop of intestine, and thus cause strangulation of 
the gut.] 
Heart.—Before this process of constriction is complete, some cells are 
mapped off from that part of the splanchnopleure which lies immediately under 1094 
PRIMITIVE CIRCULATION. 
[Sec. 442. 
the head-gut; this indicates the positioti of the heart, which appears in the chick 
at the end of the first day, as a small, bright red, rhythmically contracting 
point, the punctuni saliens, or the orf/j-rj xcvou/xivrj of Aristotle. In mammals it 
appears much later. 
The heart (fig. 811, VI) begins first as a mass of cells, some of which in the 
centre disappear to form a central cavity, so that the whole looks like a pale 
hollow bud (originally a pair) of the splanchnopleure. The central cavity soon- 
dilates; it grows, and becomes suspended in the coelom by a duplicature like 
a mesentery (meso-cardium), while the space which it occupies is spoken of as 
the fovea cardica. The heart now assumes an elongated tubular form, with its 
aortic portion directed forwards, and its venous end backward ; it then under- 
goes a slight/"-shaped curve (fig. 826, 1). From the middle of the 2d day, the 
heart begins to beat in the chick, at the rate of about 40 beats per minute. [It 
is very important to note that at first, although the heart beats rhythmically, it 
does not contain any nerve-cells.] 
From the anterior end of the heart, there proceeds from the bulbus aortse, 
the aorta which passes forward and divides into two primitive aortae, which 
then curve and pass backwards under the cerebral vesicles, and run in front of 
the protovertebrae. Opposite the omphalo-mesenteric duct, each primitive 
aorta in the chick sends off one, in mammals several (dog, 4 to 5), omphalo- 
mesenteric arteries (fig. 811, VI, A, o'), which spread out to form a vascular 
network within the mesoblast of the umbilical vesicle. From this network there 
arise the omphalo-mesenteric veins, which run backwards on the vitelline duct, 
and end by two trunks in the venous end of the tubular heart. In the chick, 
these veins arise from the sinus terminalis of the future vena terminalis of the 
area vasculosa. Thus, the first or primitive circulation is a closed system, 
and functionally it is concerned in carrying nutriment and oxygen to the em- 
bryo. In the bird, the latter is supplied through the porous shell, and the 
former is supplied up to the end of incubation by the yolk. In mammals, both 
are supplied by the blood-vessels of the uterine mucous membrane to the ovum. 
In birds, owing to the absorption of the contents of the yolk-sac, the vascular 
area steadily diminishes, until ultimately, towards the end of the period of 
incubation, the shrivelled yolk-sac slips into the abdominal cavity. In mam- 
mals, the circulation on the umbilical vesicle, i. e., through the omphalo-mesen- 
teric vessels, soon diminishes, while the umbilical vesicle itself shrivels to a, 
small appendix, and the second circulation is formed to replace the omphalo- 
mesenteric system. The first blood-vessels are formed in the chick, in the 
area vasculosa, outside the position of the embryo, at the last quarter of the 
first day, before any part of the heart is visible. The blood-vessels begin in 
vaso-formative cells [constituting the “ blood-islands ” of Pander]. At first 
they are solid, but they soon become hollow (§ 7, A). 
A narrow-meshed plexus of lyi?iphcitics is formed in the area vasculosa of the chick {His), and 
it communicates with the amniotic cavity {A. Budge). 
443. FORMATION OF THE BODY.—Body-Wall.—(1) The 
coelom, or pleuro-peritoneal cavity, becomes larger and larger, while at 
the same time the difference between the body-wall and the wall of the intes- 
tine becomes more pronounced. The latter becomes more separated from the 
protovertebrae, as the middle plate begins to be elongated to form a mesentery. 
The body-wall, or somatopleure, composed of the epiblast and the outer layer 
of the cleft mesoblast, becomes thickened by the ingrowth into it of the mus- 
cular layer from the muscle-plate, and the position of the bones and the spinal 
nerves from the protovertebras. These grow between the epiblast and the outer 
layer of the mesoblast (Remak). [The somatopleure, or parietal lamina, Sec. 443.] 
FORMATION OF VERTEBRAL COLUMN. 
1095 
from each side grows forward and towards the middle line, where they meet to 
form the body-wall, while at the same time the splanchnopleure, or visceral 
lamina, on each side also grow and meet in the middle line, and when they do 
so, they enclose the intestine. Thus, there is one tube within the other, and 
the space between is the pleuro-peritoneal cavity.] 
(2) Vertebral Column.—A dorsally placed structure, called the muscle- 
plate (fig. 813, ms.), is differentiated from each of the protovertebrae: the 
remainder of the protovertebra, the protovertebra proper, coalesces with that 
on the other side, so that both completely surround the chorda, to form the 
membrana reuniens inferior, in the chick on the 3d, and in the rabbit on 
the 10th day, while, at the same time, they close over the medullary tube dor- 
sally, in the chick at the 4th day, to form the membrana reuniens superior 
(.Reichert). Thus, there is a union of the masses of the protovertebrae in front 
of the medullary tube, which encloses the chorda, and represents the basis of 
the bodies of all the vertebrae, whilst the membrana reuniens superior, pushed 
between the muscle-plates and the epiblast on the one hand and the medullary 
tube on the other, represents the position of the entire vertebral lamince as well 
as the intervertebral ligaments between them. The vertebral column at this 
membranous stage is in the same condition as the vertebral column of the 
cyclostomata (Petromyzon). 
Spina Bifida.— In some rare cases the membrana reuniens superior is not developed, so that 
the medullary tube is covered only by the epiblast (epidermis), either throughout its entire extent, 
or at certain parts. This constitutes the condition of spina bifida, or, when it occurs in the 
head, hemicephalia. 
Lastly, parts of the somatopleures also grow towards the middle line of the 
back, and insinuate themselves between the muscle-plate and the epiblast; thus, 
the dorsal skin is formed (Remak). 
In the membranous vertebral column, there are formed the several cartilagi- 
nous vertebrae, the one behind the other, in man at the 6th to 7th week, although 
at first they do not form closed vertebral arches; the latter are closed in man 
about the 4th month. Each cartilaginous vertebra, however, is not formed from 
a pair of protovertebrae, i. e., the 6th cervical vertebra, from the 6th pair of 
protovertebrae, but there is a new subdivision of the vertebral column, so that 
the lower half of the preceding protovertebra and the upper half of the suc- 
ceeding protovertebra unite to form the final vertebra. While the bodies are 
becoming cartilaginous the chorda becomes smaller, but it still remains larger 
in the intervertebral discs. The body of the first vertebra or atlas unites with 
that of the axis to form its odontoid process, and in addition it forms the arcus 
anterior atlantis and the transverse ligament (.Hasse). The chorda can be fol- 
lowed upwards through the ligamentum suspensorium dentis as far as the 
posterior part of the sphenoid bone. 
The histogenetic formation of cartilage from the indifferent formative cells takes place by 
division and growth of the cells, until they ultimately form clear nucleated sacs. The cement 
substance is probably formed by the outer parts of the cells (parietal substance) uniting and 
secreting the intercellular substance. It is supposed by some that the latter contains fine canals, 
which connect the protoplasm of the adjoining cells. 
Visceral Clefts and Arches.—Each side of the cervical region contains 
four slit-like openings—the visceral clefts or branchial openings (Rathke); 
in the chick, the upper three are formed at the third, and the fourth on the 4th 
day. Above the slits are thickenings of the lateral wall, which constitute the 
visceral or branchial arches (fig. 819). The clefts are formed by a perfo- 
ration from the fore-gut, but this, perhaps, does not always occur in the chick, 
mammal, and man (d/'/s), and they are lined by the cells of the hypoblast. On 
each side in each visceral arch, i. e., above and below each cleft, there runs an 1096 
AMNION AND ALLANTOIS. 
[Sec. 443. 
aortic arch, five on each side (fig. 811, IX). These aortic arches persist in 
fishes. In man, all the slits close, except the uppermost one, from which the 
auditory meatus, the tympanic cavity, and the Eustachian tube are developed. 
The four visceral arches are for the most part made use of later for other 
formations (p. 1x04). 
Primitive Mouth and Anus.—Immediately under the fore-brain, in the 
middle line, is a thin spot, where there is at first a small depression, and ulti- 
mately a rupture, forming the primitive oral aperture, which represents 
both the mouth and the nose. Similarly, there is a depression at the caudal 
end, and the depression ultimately deepens, thus communicating with the hind- 
gut to form the anus. When the latter part of the process is incomplete, there 
is atresia ani, or imperforate anus. Several processes are given off from the 
primitive intestine, including the hypoblast and its muscular layers, to form the 
lungs, the liver, the pancreas, the caecum (in birds), and the allantois. 
The extremities appear at the sides of the body as short unjointed stumps 
or projections at the 3d or 4th week in the human embryo. 
444. AMNION AND ALLANTOIS.—Amnion.—During the eleva- 
tion of the embryo from its surroundings, immediately in front of the head (at 
the end of the 2d day in the chick), there rises up a fold consisting of the epi- 
blast and the outer layer of the mesoblast, which gradually extends to form a 
sort of hood over the cephalic end of the embryo (fig. 811, VI, A). In the 
same way, but somewhat later, a fold rises at the caudal end, and between both 
along the lateral borders similar elevations occur, the lateral folds (fig. 811, 
III, A). All these folds grow over the back of the embryo to meet over the 
middle line posteriorly, where they unite at the 3d day, in the chick, to form 
the amniotic sac. Thus, a cavity which becomes filled with fluid—the am- 
niotic fluid—is developed around the embryo [so that the embryo really floats 
in the fluid of the amniotic sac]. In mammals also the amnion is developed 
very early, just as in birds (fig. 811, VII, A). From the middle of pregnancy 
onwards, the amnion is applied directly to the chorion, and united to it by a 
gelatinous layer of tissue, the tunica media of Bischoff. 
Amniotic Fluid.—The amnion, and the allantois as well, are formed only 
in mammals, birds, and reptiles, which have hence been called amniota, while 
the lower vertebrates, which are devoid of an amnion, are called anamnia. 
Amniotic fluid. Composition—The amniotic fluid is a clear, serous, alkaline fluid, spe- 
cific gravity 1007 to 1011, containing, besides epithelium, lanugo hairs, \ to 2 per cent, of fixed 
solids. Amongst the latter are albumin (j to i per cent.), mucin, globulin, a vitellin-like body, 
some grape sugar, urea, ammonium carbonate, very probably derived from the decomposition of 
urea, sometimes lactic acid and kreatinin, calcic sulphate and phosphate, and common salt. 
About the middle of pregnancy, it amounts to about 1-1.5 kilo. [2.2-3.3 lbs.], and at the end 
about 0.5 kilo. The amniotic fluid is of foetal origin, as is shown by its occurrence in birds, and 
is, perhaps, a transudation through the foetal membranes. In mammals, the urine of the foetus 
forms part of it during the second half of pregnancy (Gusserow). In the pathological condition 
of hydramnion, the blood vessels of the uterine mucous membrane secrete a watery fluid. The 
fluid preserves the foetus, and also the vessels of the foetal membranes, from mechanical injuries; 
it permits the limbs to move freely, and protects them from growing together; and, lastly, it is 
important for dilating the os uteri during labor. The amnion is capable of contraction at the 7th 
day in the chick; and this is due to the smooth muscular fibres which are developed in the 
cutaneous plate in its mesoblastic portion, but nerves have not been found. 
Allantois.—From the anterior surface of the caudal end of the embryo 
there grows out a small double projection, which becomes hollowed out to form 
a sac projecting into the cavity of the coelom or pleuro-peritoneal cavity (fig. 
811) ; it constitutes the allantois and is formed in the chick before the 5th 
day, and in man during the 2d week. Being a true projection from the hind- 
gut, the allantois has two layers, one from the hypoblast, and the other from Sec. 444.] 
ALLANTOIS. 
1097 
the muscular layer, so that it is an offshoot from the splanchnopleure. From 
both sides, there pass on to the allantois the umbilical arteries from the 
hypogastric arteries, and they ramify on the surface of the sac. The allantois 
grows, like a urinary bladder gradually being distended, in front of the hind- 
gut in the pleuro-peritoneal cavity towards the umbilicus ; and lastly, it grows 
out of the umbilicus, and projects beyond it alongside the omphalo mesenteric 
or vitelline duct, its vessel growing with it (fig. 8n, VII, a); but, after this 
stage, it behaves differently in birds and mammals. 
In birds, after the allantois passes out of the umbilicus, it undergoes great development, so 
that within a short time it lines the whole of the interior of the shell as a highly vascular and 
saccular membrane. Its arteries are at first branches of the primitive aortse, but with the 
development of the posterior extremities they appear as branches of the hypogastric arteries. 
Two allantoidal, or umbilical veins. proceed from the numerous capillaries of the allantois. 
They pass backward through the umbilicus, and at first unite with the omphalo-mesenteric 
veins to join the venous end of the heart. In birds this circulation on the allantois, or second 
circulation, is respiratory in function, as its vessels serve for the exchange of gases through the 
porous shell. The circulation gradually assumes the respiratory functions of the umbilical 
vesicle, as the latter gradually becomes smaller and smaller, and ceases to be a sufficient 
respiratory organ. Towards the end of the period of incubation the chick may breathe and cry 
within the shell (Aristotle)—a proof that the respiratory function of the allantois is partly taken 
over by the lungs. The allantois is also the excretory organ of the urinary constituents. 
Into its cavity in mammals the ducts of the primitive kidneys, or the Wolffian ducts, open, but 
in birds and reptiles, which possess a cloaca, these open into the posterior wall of the cloaca. 
The primitive kidneys, or Wolffian bodies, consist of many glomeruli, and empty their secre- 
tion through the Wolffian ducts into the allantois (in birds into the cloaca), and the secretion 
passes through the allantois, per the umbilicus, into the peripheral part of the urinary sac. 
Remak found ammonium and sodium urate, allantoin, grape-sugar, and salts in the contents of 
the allantois. From the 8th day onwards, the allantois of the chick is contractile ( Vulpian), 
owing to the presence of smooth fibres derived from the splanchnopleure. Lymphatics accom- 
pany the branches of the arteries (A. Budge). 
Allantois in Mammals.—In mammals and man, the relation of the 
allantois is somewhat different. The first part or its origin forms the urinary 
bladder, and from the vertex of the latter there proceeds through the umbili- 
cus a tube, the urachus, which is open at first (fig. 811, VIII, a). The 
blind part of the sac of the allantois outside the abdomen is in some animals 
filled with a fluid like urine. In man, however, this sac disappears during the 
2d month, so that there remains only the vessels which lie in the muscular part 
of the allantois. In some animals, however, the allantois grows larger, does 
not shrivel, but obtains through the urachus from the bladder an alkaline tur- 
bid fluid, which contains some albumin, sugar, urea, and allantoin. The rela- 
tions of the umbilical vessels will be described in connection with the foetal 
membranes. 
445. FCETAL MEMBRANES, PLACENTA, FCETAL CIR- 
CULATION.—Decidua.—When a fecundated ovum reaches the uterus, it 
becomes surrounded by a special covering, which William Hunter (1775) 
described as the membrana decidua, because it was shed at birth. We dis- 
tinguish the decidua vera (fig. 811, VIII, p), which is merely the thickened, 
very vascular, softened, more spongy, and somewhat altered mucous membrane 
of the uterus. [Sometimes in a diseased condition, as in dysmenorrhoea, the 
superficial layer of the uterine mucous membrane is somewhat thrown off nearly 
en masse in a triangular form (fig. 815). This serves to show the shape of the 
decidua, which is that of the uterus]. When the ovum reaches the uterus, it is 
caught in a crypt or fold of the decidua, and from the latter there grow up 
elevations around the ovum; but these elevations are thin, and soon meet over 
the back of the ovum to form the decidua reflexa (fig. 811, VIII, r). At 
the 2d to 3d month there is still a space in the uterus outside the reflexa; in 
the 4th month the whole cavity is filled by the ovum. At one part the ovum CHORION. 
[Sec. 445. 
lies directly upon the d. vera [and that part is spoken of as the decidua 
serotina], but by far the greatest part of the surface of the ovum is in con- 
tact with the reflexa. In the region of the d. serotina the placenta is 
ultimately formed. 
Structure of the Decidua Vera.—The d. vera at the 3d month is 4 to 7 mm. thick, and 
at the 4th only 1 to 3 mm., and it no longer has any epithelium, but it is very vascular and 
is possessed of lymphatics around the glands and blood-vessels (Leopold), and in its loose sub- 
stance are large round cells (decidua cells—Kdlliker), which in the deeper parts become changed 
into fibre cells—there are also lymphoid cells. The uterine glands, which become greatly 
developed at the commencement of pregnancy, at the 3d to the 4th month form non-cellular, 
wide, bulging tubes, which become indistinct in the later months, and in which the epithelium 
disappears more and more. The d. reflexa, much thinner than the vera from the middle of 
pregnancy, is devoid of epithelium, and is without vessels and glands. Towards the end of 
pregnancy the two deciduae unite with each other. 
The ovum, covered at first with small hollow villi, is surrounded by the 
decidua. From the formation of the amnion it follows that, after it is closed, 
a completely closed sac passes away from the embryo to lie next the primitive 
chorion. This membrane is the “ serous covering” of v. Baer (fig. 811, VII, 
s), or the false amnion. It becomes closely applied to the inner surface of 
the chorion, and extends even into its villi. The allantois proceeding from the 
umbilicus comes to lie directly in contact with the foetal membrane ; its sac 
disappears about the 2d month in man, but its vascular layer grows rapidly 
and lines the whole of the inner surface of the chorion, where it is found on 
the 18th day (Coste). From the 4th week the blood-vessels, along with a 
covering of connective-tissue, brari'ch and penetrate into the hollow cavities of 
the villi and completely fill them. At this time the primitive chorion disap- 
pears. Thus we have a stage of general vascularization of the chorion. In the 
place of the derivative of the zona pellucida we have the vascular villi of the 
allantois, which are covered by the epiblastic cells derived from the false 
amnion. This stage lasts only until the 3d month, when the chorionic villi 
disappear all over that part 
of the surface of the ovum 
which is in contact with the 
decidua reflexa. On the other 
hand, the villi of the chori- 
on, where they lie in direct 
contact with the decidua 
serotina, become larger and 
more branched. Thus, there 
is distinguished the chorion 
lseve and c. frondosum. 
The chorion lasve, which con- 
sists of a connective-tissue matrix 
covered externally by several layers 
of cells, has a few isolated villi at 
wide intervals. Between the chor- 
ion and the amnion is a gelatinous 
substance (membrana intermedia) 
or undeveloped connective-tissue. 
Placenta.—The large 
villi of the chorion frondo- 
sum penetrate into the tissue 
of the decidua serotina of the uterine mucous membrane. [It was formerly 
supposed that the chorionic villi entered the mouths of the uterine glands, but 
the researches of Ercolani and Turner have shown that, although the uterine 
glands enlarge during the early months of utero-gestation, the villi do not enter 
Fig. 815. 
A dysmenorrheal membrane laid open. Sec. 445.] 
PLACENTA. 
the glands. The villi enter the crypts of the uterine mucous membrane. The 
glands of the inner layer of the decidua serotina soon disappear.] As the villi 
grow into the decidua serotina, they push against the walls of the large blood- 
vessels, which are similar to capillaries in structure, so that the villi come to be 
bathed by the blood of the mother in the uterine sinuses, or they float in the 
colossal decidual capillaries (fig. 8n, VII, &). The villi do not float naked in 
the maternal blood, but they are covered by a layer of cells derived from the 
decidua. Some villi, with bulbous ends, unite firmly with the tissue of the 
uterine part of the placenta to form a firm bond of connection. [The placenta 
is formed by the mutual intergrowth of the chorionic villi and the decidua 
serotina.] Thus, it consists of a foetal part, including all the villi and a 
maternal or uterine part, which is the very vascular decidua serotina. At 
the time of birth both parts are so firmly united that they cannot be separated. 
Around the margin of the placenta is a large venous vessel, the tnarginal sinus 
of the placenta. [Freidlander found the uterine sinuses below the placental 
site blocked by giant cells after the 8th month of pregnancy. Leopold confirms 
this, and found the same in the serotinal veins.] 
Functions.—Tne placenta is the nutritive, excretory, and respiratory 
organ of the foetus (§ 368) ; the latter receives its necessary pabulum by endos- 
mosis from the maternal sinuses through the coverings and vascular wall of the 
villi in which the foetal 
blood circulates. [The pla- 
centaalso contains glycogen.'] 
[Structure.—A piece of fresh 
placenta teased in normal saline 
solution shows the villi provided 
with lateral offshoots, and consist- 
ing of a connective-tissue frame- 
work, containing a capillary net- 
work with arteries and veins, 
while the villi themselves are 
covered by a layer of somewhat 
cubical epithelium (fig. 816).] 
Uterine .Milk.— Be- 
tween the villi of the pla- 
centa there is a clear fluid, 
which contains numerous 
small, albuminous globules, 
and this fluid, which is abun- 
dant in the cow, is spoken 
of as the uterine milk. It 
seems to be formed by the 
breaking up of the decidual 
cells. It has been supposed 
to be nutritive in function. 
[The maternal placenta, therefore, seems to be a secreting structure, while the 
foetal part has an absorbing function. The uterine milk has been analyzed by 
Gamgee,who found that it contained fatty, albuminous, and saline constituents, 
while sugar and casein were absent.] 
The investigations of Walter show that after poisoning pregnant animals with strychnin, mor- 
phia, veratrin, curare, and ergotin, these substances are not found in the foetus, although many 
other chemical substances pass into it. 
[Savory found that strychnin injected into a foetus in utero caused tetanic convulsions in the 
mother (bitch), while syphilis may be communicated from the father to the mother through the 
medium of the foetus (Hutchinson). A. Harvey’s record of observations on the crossing of 
breeds of animals—chiefly of horses and allied species—show that materials can pass from the 
foetus to the mother.] 
Human placental villi. Blood-vessels black. 
Fig. 816. UMBILICAL CORD. 
[Sec. 445 
On looking at a placenta, it is seen that its villi are distributed on large areas separated from 
each other by depressions. This complex arrangement might be compared with the cotyledons 
of some animals. 
The position of the placenta is, as a rule, on the anterior or posterior wall of the uterus, 
more rarely on the fundus uteri, or laterally from the opening of the Fallopian tube, or over the 
internal orifice of the cervix, the last constituting the condition of placenta praevia, which is 
a very dangerous form of placental insertion, as the placenta has to be ruptured before birth can 
take place, so that the mother often dies from hemorrhage. The umbilical cord may be inserted 
in the centre of the placenta (insertio centralis, or more towards the margin (ins. marginalis) 
or the cord may be fixed to the chorion laeve. Sometimes, though rarely, there are small subsidi- 
ary placentae (pi. succenturiata), in addition to the large one. When the placenta consists of 
two halves, it is called duplex or bipartite, a condition said by Hyrtl to be constant in the apes of 
the old world. 
Structure of the Umbilical Cord.—The umbilical cord (48 to 60 cm. 
[20 to 24 inches] long, u to 13 mm. thick) is covered by a sheath from the 
Section of the uterine wall with the placenta adhering to it, from a woman 30 weeks pregnant. 
a, root and insertion of the umbilical cord; b, amniotic covering of the placenta and cord ; 
c, chorion; dd, foetal part of the placenta; ee, uterine wall; ff, complex of placental villi 
forming the foetal placenta ; gg, decidua; hh, processes of the decidua penetrating into the 
foetal placenta; ii, branches of an uterine artery; ip, an artery entering the placenta; kkkk, 
uterine veins. 
Fig. 817. 
amnion. The blood-vessels make about forty spiral turns, and they begin to 
appear about the 2d month. [The cause of the twisting is not well under- 
stood, but Virchow has shown that capillaries pass from the skin for a short dis- 
tance on the cord, and they do so unequally, and it may be that this may aid in 
the production of the torsion.] It contains two strongly muscular and contrac- 
tile arteries, and one umbilical vein. The two arteries anastomose in the 
placenta (Hyrtl). In addition, the cord contains the continuation of the 
urachus, the hypoblastic portion of the allantois (fig. 811, VIII, a), which re- 
mains until the 2d month, but afterwards is much shrivelled. The omphalo- 
mesenteric duct of the umbilical vesicle (N) is reduced to a thread-like stalk 
(fig. 811, VIII, D). Wharton’s jelly surrounds the umbilical blood-vessels. 
Wharton’s jelly is a gelatinous-like connective-tissue, consisting of branched 
corpuscles, lymphoid cells, some connective-tissue fibrils, and even elastic Sec. 445.] 
FCETAL CIRCULATION. 
fibres. It yields mucin. It is traversed by numerous juice-canals lined by 
endothelial cells, but other blood- and lymphatic-vessels are absent. Nerves 
occur 3-8-11 cm. from the umbilicus (.Schott). 
The foetal circulation, which is established after the development of the 
allantois, has the following course (fig. 818): The blood of the foetus passes 
from the hypogastric arteries through the two umbilical arteries, through the 
umbilical cord to the placenta, where the arteries split up into capillaries. The 
blood is returned from the placenta by the umbilical vein, although the color 
of the blood cannot be distinguished from the venous or impure blood in the 
umbilical arteries. The umbilical vein (fig. 829, 2, u) returns to the umbili- 
cus, passes upwards under the margin of the liver, gives a branch to the vena 
portae (a), and runs as the ductus venosus into the inferior vena cava, which 
carries the blood into the right auricle. Directed by the Eustachian valve and 
the tubercle of Lower (fig. 826, 6, tL), the great mass of the blood passes 
through the foramen ovale into the left auricle, owing to the presence of the 
valve of the foramen ovale. From the left auricle it passes into the left ven- 
tricle, aorta, and hypogastric arteries, to the umbilical arteries. The blood of 
the superior vena cava of the foetus passes from the right auricle into the right 
ventricle (fig. 826, 6, Cs). From the right ventricle it passes into the pulmo- 
nary artery (fig. 826, 7, p), and through the ductus arteriosus of Botalli 
(B~) into the aorta. There are, 
therefore, two streams of blood in 
the right auricle which cross each 
other, the descending one from the 
head through the superior vena cava, 
passing in front of the transverse one 
from the inferior vena cava to the 
foramen ovale.] Only a small 
amount of the blood passes through 
the as yet small branches of the pul- 
monary artery to the lungs (fig. 826, 
7,1, 2). The course of the blood 
makes it evident that the head and 
upper limbs of the foetus are nour- 
ished by purer blood than the re- 
mainder of the trunk, which is sup- 
plied with blood mixed with the 
blood of the superior vena cava. 
After birth, the umbilical arteries 
are obliterated, and become the lat- 
eral ligaments of the bladder, while 
their lower parts remain as the superior 
vesical arteries. The umbilical vein 
is obliterated, and remains as the 
ligamentum teres, or round ligament 
of the liver, and so is the ductus 
venosus Arantii. Lastly, the fora- 
men ovale is closed, and the ductus 
arteriosus is obliterated, the latter 
forming the lig. arteriosus. 
The condition of the membranes where 
there are more foetuses than one: (1) With 
twins there are two completely separated ova, 
with two placentae and two deciduae reflexae. (2) Two completely separated ova may have 
Course of the foetal circulation. 
Fig. 818. CHRONOLOGY OF DEVELOPMENT. 
[Sec. 445. 
only one reflexa, whereby the placentae grow together, while their blood-vessels remain distinct. 
The chorion is actually double, but cannot be separated into two lamellae at the point of union. 
(3) One reflexa, one chorion, one placenta, two umbilical cords, and two amnia. The vessels 
anastomose in the placenta. In this case there is one ovum with a double yolk, or with two 
germinal vesicles in one yolk. (4) As in (3), but only one amnion, caused by the formation of 
two embryos in the same blastoderm of the same germinal vesicle. 
Formation of the Fcetal Membranes.—The oldest mammals have no placenta or umbilical 
vessels; these are the Mammalia implacentalia, including the monotremata and marsupials. 
The second group includes the Mammalia placentalia. Amongst these (a) the non-decid- 
uata possess only chorionic villi supplied by the umbilical vessels, which project into the depres- 
sions of the uterine mucous membrane, and from which they are pulled cut at birth (PI. diffusa, 
e.g., pachydermata, cetacea, solidungula, camelidae). In the ruminants, the villi are arranged 
in groups or cotyledons, which grow into the uterine mucous membrane, from which they are 
pulled out at birth, (b) In the deciduata, there is such a firm union between the chorionic 
villi with the uterine mucous membrane, that the uterine part of the placenta comes away with 
the fcetal part at birth. In this case the placenta is either zonary (carnivora, pinnipedia, 
elephant) or discoid (apes, insectivora, edentata, rodentia). 
446. CHRONOLOGY OF HUMAN DEVELOPMENT.—Development during 
the 1st Month.—At the I2th-I3th day the ovum is saccular (5.5 mm. and 3.3 mm. in diam- 
eter) ; there is simply the blastodermic vesicle, with the blastoderm at one part, consisting of 
two layers; the zona pellucida beset with small villi (Reichert). At the I5th-i6th day the 
ovum (5-6 mm.) is covered with simple cylindrical villi. The zona pellucida consists of 
embryonic connective-tissue covered with a layer of flattened epithelium. The primitive 
groove and the laminae dorsales appear. Then follows the stage when the allantois is first 
formed. At the 15th—18th day Coste investigated an ovum. It was 13.2 mm. long, with small 
branched villi; the embryo itself was 2.2 mm. long, of a curved form, and with a moderately 
enlarged cephalic end. The amnion, umbilical vesicle with a wide vitelline duct, and the allan- 
tois were developed, the last already united to the false amnion. The S-shaped heart lies in the 
cardiac cavity, shows a cavity and a bulbous aortas, but neither auricles nor ventricles. The visce- 
ral arches and clefts are indicated, but they are not perforated. The omphalo-mesenteric vessels 
forming the first circulation on the umbilical vesicle are developed, the duct (vitelline) is still quite 
open, and two primitive aorta run in front of the protovertebrae. The allantois attached to the fcetal 
membranes is provided with blood-vessels. The two omphalo-mesenteric veins unite with the 
two umbilical veins, and pass to the venous end of the heart. The mouth is in process of for- 
mation. The limbs and sense-organs absent; the Wolffian bodies probably present. 
At the 20th day all the visceral arches are formed, and the clefts are perforated. The 
mid-brain forms the highest part of the brain, while the two auricles appear in the heart. The 
connection with the umbilical vesicle is still moderately wide. The embryo is 2.6-3.3-4 mm. 
long, while the head is turned to one side (His). At a slightly later period the temporal 
and cervical flexures take place, and the hemispheres appear more prominently; the vitelline 
duct is narrowed, the position of the liver is indicated, while the limbs are still absent {His). 
At the 21st day the ovum is 13 mm. long and the embryo 4-4.5 mm.; the umbilical vesicle 
2.2 mm., and the intestine almost closed. Three branchial clefts, Wolffian bodies laid down, 
and the first appearance of the limbs ; three cerebral vesicles, auditory capsules present (R. 
Wagner). Coste also observed, in addition, the nasal pits, eye, the opening for the mouth, with 
the frontal and superior maxillary processes, the heart with two ventricles and two auricles. 
End of the 1st Month.—The embryos of 25-28 days are characterized by the distinctly 
stalked condition of the umbilical vesicle and the distinct presence of limbs. Size of the ovum, 
17.5 mm.; embryo, 8-11 mm.; umbilical vesicle, 4.5 mm., with blood-vessels. 
2d Month.—The embryos of 28-35 days are m°re elongated, and all the branchial clefts are 
closed except the first. The allantois has now only three vessels, as the right umbilical vein is 
obliterated. At the 5th week the nasal pits are united with the angle of the mouth by furrows, 
which close to form canals at the 6th week {Toldt). At 35-42 days the embryo is 1.3-1.1 
cm. long, the nasal and oral orifices are separated, the face is flat the limbs show three divisions, 
the toes are not so sharply defined as the fingers. The outer ear appears as a low projection at 
the 7th week. The Wolffian bodies are much reduced in size. Length of body at 7th to 8th 
week, 1.6-2.1 cm. 
End of the 2d Month. —Ovum, cm.; villi, 1.3 mm. long; the circulation on the 
umbilical vesicle has diappeared; embryo, 26 mm. long, and weighs 4 grams. Eyelids and 
nose present; umbilical cord 8 mm. long, abdominal cavity closed, ossification beginning in the 
lower jaw, clavicle, ribs, bodies of the vertebrae ; sex indistinct; kidneys laid down. 
3d Month.—Ovum as large as a goose’s egg; beginning of the placenta; embryo 7-9 cm., 
weighing 11 grams, and is now spoken of as a foetus. External ear well formed; umbilical 
cord 7 cm. long. Beginning of the difference between the sexes in the external genitals, umbilicus 
in the lower fourth of the linea alba. Sec. 446.] 
CHRONOLOGY OF DEVELOPMENT. 
4th Month.—Foetus 17 cm. long, weighing 57 grams, sex distinct; hair and nails beginning 
to be formed, placenta weighs 80 grams, umbilical cord 19 cm. long, umbilicus above the lowest 
third of the linea alba; contractions or movements of the limbs; meconium in the intestine; 
skin with blood-vessels shining through it, eyelids closed. 
5th Month.—Foetus, length of body, 9.7-14.7 cm., total length 18 to 28 cm., weighing 284 
grams; hair on the head and lanugo distinct; skin still somewhat red and thin, and covered 
with vernix caseosa (§ 287, 2), is less transparent; weight of placenta, 178 grams; umbilical 
cord, 31 cm. long. 
6th Month.—Foetus, length of body, 9.7-14.7, total length, 18-28 cm., weighing 638 grams; 
lanugo more abundant; vernix more abundant; testicles in the abdomen ; pupillary membrane 
and eyelashes present; meconium in the large intestine. 
7th Month.— Foetus, length of body, 18-22.8, total length, 35-38 cm., weighing 1218 grams, 
the descent of the testicles begins—one. testicle in the inguinal canal—the eyes open, the pupil- 
lary membrane often absorbed at its centre in the 28th week. In the brain other fissures are 
formed besides the primary ones. The foetus is capable of living independently. At the begin- 
ning of this month there is a centre of ossification in the os calcis. 
8th Month.—Foetus, length of body, 24-27 8, total length 42 cm., weighing 1.5 to 2 kilos. 
(3.3 to 4.4 lbs.), hair of the head abundant, 1.3 cm. long, nails with a small margin, umbilicus 
below the middle of the linea alba, one testicle in the scrotum. 
9th Month.—Foetus, length of body, 30-37, total length, 47-67 cm., weighing 2234 grams, 
and is not distinguishable from the child at the full period. 
Fcetus at the Full Period.—Length of body, 51 cm. [20 inches], weight, kilos. 
[7 lbs.], lanugo present only on the shoulders, skin white. The nails of the fingers project be- 
yond the tips of the fingers, umbilicus slightly below the middle of the linea alba. The centre 
of ossification in the lower epiphysis of the femur is 4 to 8 mm. broad. 
Days. 
Days. 
Weeks. 
Weeks. 
Coluber, . 
. 12 
Rabbit, 
Dog, . . . 
) 
Sheep, . . 
21 
Hen, 
: }21 
Hare, . . 
. } 32 
Fox, . . . 
f 9 
Goat, . . . 
22 
Duck, . . 
Weeks. 
Foumart. . . 
i 
Roe, 
• 24 
Goose, . . 
. 29 
Rat, . . . 
5 
Badger, . . 
}IG 
Bear, . . . 
Stork, . . 
. 42 
Guinea-pig, 
7 
Wolf, . . . 
Small apes, 
. 
Cassowary, 
.. 65 
Cat, . . . 
:}8 
Lion, . . . 
14 
Deer, . . . 
. 36-40 
Mouse, . . 
. 24 
Marten, 
Pig, .... 
17 
Woman, . . 
. 40 
Period of Gestation or Incubation (Schenk). 
Horse, Camel, 13 months; Rhinoceros, 18 months; and Elephant, 24 months. 
Limitation of the supply of O to eggs, during incubation, leads to the formation of dwarf 
chicks. 
The movements of the foetus can be detected through the abdominal parietes of the mother. 
They consist in extensor movements of the trunk, movements of the limbs, and toward the end 
of pregnancy a regular rhythmical movement of the respiratory muscles (.Ahlfeld) which lasts 
for some time. Besides these the foetus makes movements of sucking and swallowing. 
447. FORMATION OF THE OSSEOUS SYSTEM.—Vertebral Column.— 
The ossification of the vertebrae begins at the 8th to the 9th week, and first of all there is 
a centre in each vertebral arch, then a centre is formed in the body behind the chorda, 
which, however, is composed of two closely apposed centres. At the 5th month the osseous 
matter has reached the surface, the chorda within the body of the vertebra is compressed; the 
three parts unite in the 1st year. The atlas has one centre in the anterior arch and two in the 
posterior; they unite at the 3d year. The epistropheus has a centre at the 1st year. The three 
points of the sacral vertebrae unite or anchylose between the 2d and the 6th year, and all the 
vertebrae (sacral) become united to form one body between the 18th and 25th years. Each of 
the four coccygeal vertebrae has a centre from the 1st to 10th year. The vertebrae in later 
years produce 1 to 2 centres in each process ; 1 to 2 centres in each transverse process; 1 in the 
mamillary process of the lumbar vertebrae; and 1 in each articular process (8 to 15 years). Of 
the upper and under surfaces of the body of a vertebrae each forms an epiphysial thin osseous 
plate, which may still be visible at the 20th year. Groups of the cells of the chorda are still to 
be found within the intervertebral discs. As long as the coccygeal vertebrae, the odontoid pro- 
cess, and the base of the skull are cartilaginous, they still contain the remains of the chorda 
(Jf. Muller). The coccygeal vertebrae form the tail, and they originally project in man like a 
tail (fig. 811, IX, T), which is ultimately covered over by the growth of the soft parts [His). 
The ribs bud out from the protovertebrae, and are represented on each vertebrae. The thoracic 
ribs become cartilaginous in the 2d month and grow forwards into the wall of the chest, whereby 
the seven upper ones are united by a median portion (Rathke), which represents the position of 
one-half of the sternum, and when the two halves meet in the middle line the sternum is DEVELOPMENT OF THE OSSEOUS SYSTEM. 
[Sec. 447. 
formed. When this does not occur we have the condition of the cleft sternum. At the 6th 
month there is a centre of ossification in the manubrium, then 4 to 13 in pairs in the body, and 
1 in the ensiform process. Each rib has a centre of ossification in its body at the 2d month, 
and at the 8th to 14th one in the tubercle and another in the head. These anchylose at the 
14th to 25th year. Sometimes cervical ribs are present in man, and they are largely developed 
in birds. 
The skull.—The chorda extends forwards into the axial part of the base to the sphenoid bone. 
The skull at first is membranous, or the primordial cranium ; at the 2d month the basal 
portion becomes cartilaginous, including the occipital bone, except the upper half, the anterior 
and posterior part and wings of the sphenoid bone, the petrous part and mastoid process of the 
temporal bone, the ethmoid with the nasal septum, and the cartilaginous part of the nose. The 
other parts of the skull remain membranous, so that there is a cartilaginous and membranous 
primordial cranium. . 
I. The occipital bone has a centre of ossification in the basilar part at the 3d month, and 
one in the condyloid part and another in the fossa cerebelli, while there are two centres in the 
membranous cerebral fossae. The four centres of the body unite during intra uterine life. All 
the other parts unite at the 1st to 2d year. 
II. The post-sphenoid.—From the 3d month it has two centres in the sella turcica, two in 
the sulcus caroticus, two in both great wings, which also form the lamina externa of the ptery- 
goid process, while the non-cartilaginous and previously formed inner lamina arises from the 
superior maxillary process of the first branchial arch. During the first half of foetal life these 
centres unite as far as the great wings ; the dorsum sells and the clinoid process, as far as the 
synchondrosis spheno-occipitalis, are still cartilaginous, but they ossify at the 13th year. 
III. The pre-sphenoid at the 8th month has two centres in the small wings and two in the 
body. At the 6th month they unite, but cartilage is still found within them even at the 13th 
year. 
IV. The ethmoid has a centre in the labyrinth at the 5th month, then in the first year a 
centre in the central lamina. They unite about the 5th or 6th year. 
V. Amongst the membrane bones are the inner lamina of the pterygoid process (one cen- 
tre), the upper half of the tabular plate of the occipital (two points), the parietal bone (one centre 
in the parietal eminence), the fro.ntal bone (one double centre in the frontal eminence), three small 
centres in the nasal spine, spina trochlearis and zygomatic process, nasal (one centre), the edges 
of the parietal bones (one centre), the tympanic ring (one centre), the lachrymal, vomer, and 
intermaxillary bone. 
The facial bones are intimately related to the transformations of the branchial arches and 
branchial clefts (fig. 819). The median end of the first branchial arch projects inwards from 
each side towards the large oral aperture. It has two 
processes, the superior maxillary process which grows 
more laterally towards the side of the mouth, and the 
inferior maxillary process, which surrounds the lower 
margin of the mouth (fig. 811, IX). From above down- 
wards there grows as an elongation of the basis cranii 
the frontal process (j), a broad process with a point (y) 
at its lower and outer angle, the inner nasal process. 
The frontal and the superior maxillary processes (r) unite 
with each other in such a wav that the former projects 
bet ween the two latter. At the same time there is anchy- 
losed with the superior maxillary process the small ex- 
ternal nasal process («), a prolongation of the lateral 
part of the skull, and lying above the superior maxillary 
process. Between the latter and the outer nasal process 
is a slit leading to the eye (a). Thus the mouth is cut 
off from the nasal apertures which lie above it. But the 
separation is continued also within the mouth; the 
superior maxillary process produces the upper jaw, the 
nasal process, and the intermaxillary process (Goethe')— 
the latter is present in man, but is united to the upper 
jaw. The intermaxillary bone, which in many animals 
remains as a separate bone (os incisivum), carries the 
incisor teeth (fig. 822. A). At the 9th week the hard 
palate is closed, and on it rests the septum of the nose, 
descending vertically from the frontal process. The lower 
jaw is formed from the inferior maxillary process. At 
the circumference of the oral aperture the lips and the 
alveolar walls are formed. The tongue (fig. 822, A z) 
is formed behind the point of the union of the second 
Head of embryo rabbit of io days 
(X 12). a, eye; at, atrium or 
primitive auricle of heart; b, aortic 
bulb ; K/, K//, K///, first (mandi- 
bular), second (hyoid), third (1st 
branchial) visceral arch ; m, mouth ; 
.r, superior, and u, inferior maxillary 
process; s, mid-brain ; v, part of 
head and fore-brain ; v, ventricle of 
heart. 
Fig. 819. Sec. 447.] 
BRANCHIAL ARCHES. 
1105 
and third branchial arches [His) while, according to Born, it is formed by an intermediate 
part between the inferior maxillary processes. 
Arrested Facial Development.—These transformations may be interrupted. (1) If the 
frontal process remains separate from the superior maxillary processes, then the mouth is not 
separated from the nose. This separation may occur only in the soft parts, constituting hare-lip 
(fig. 820); or it may involve the hard palate, constituting cleft palate. The hare-lip or cleft 
palate may occur on both sides. In cleft palate the fissure usually occurs between the incisor 
teeth. In cases of cleft palate there are often supernumerary incisor teeth. 
Fig. 820.—Harelip on the left side. Fig. 821.—Inner view of the lower jaw of an embryo pig 
3 inches long (x 3/4)- m&> Meckel’s cartilage; d, dentary bone; cr, coronoid process; ar, 
articular process (condyle); ag, angular process; ml, malleus; mb, manubrium. 
Fig. 820. 
Fig. 821. 
(2) When there is non-union between the inner and outer nasal process on the one side and 
the superior maxillary process of the other there is an oblique facial cleft—oro-orbital cleft— 
(fig. 822, D). 
(3) The oral cleft (Makrostomia) may be enormously large laterally and may almost reach 
the ear (fig. 822, B, m). 
(4) Extremely seldom is there a fistula of the upper lip. 
From the posterior part of the first branchial arch are formed the malleus (ossified at the 4th 
month), and Meckel’s cartilage (fig. 821), which proceeds from the latter behind the tympanic 
Fig. 822. 
Scheme of formation of the face and arrest of its development. A, First appearance of the 
face; I, II, III, IV, the four visceral arches; f. frontal process; I, inner, and 2, outer 
nasal processes; 3, superior maxillary process; u, inferior maxillary process; b, c, first and 
second visceral clefts; a, eye; z, tongue. B, Normal union of the embryonic parts ; Z, 
intermaxillary bone; N', nasal orifice; O, nasal tear duct; U, lower jaw [in, abnormal 
dilation of the mouth, constituting makrostomia]. C, Arrest of the development, constitu- 
ting oro-nasal cleft. D, Arrest of development showing an “ oblique facial cleft ” (Q). 
ring as a long cartilaginous process, extending along the inner side of the lower jaw, almost to 
its middle. It disappears after the 6th month; still its posterior part forms the internal lateral 
ligament of the maxillary articulation. Near where it leaves the malleus is the processus Folii 
(Baumuller). A part of its median end ossifies, and unites with the lower jaw. The lower jaw 
is laid down in membrane from the first branchial arch, while the angle and condyle are formed 
from a cartilaginous process. The union of both bones to form the chin occurs at the first year. 
From the superior maxillary process are formed the inner lamella of the pterygoid process, the [Sec. 447. 
DEVELOPMENT OF THE FORE LIMB. 
palatine process of the upper jaw, and the palatine bone at the end of the 2d month, and lastly 
the malar bone. 
The second arch [hyoid], arising from the temporal bone, and running parallel with the 
first arch, gives rise to the stapes (although, according to Salensky, this is derived from the first 
arch), the eminentia pyramidalis, with the stapedius muscle, the incus, the styloid process of the 
temporal bone, the (formerly cartilaginous) stylo-hyoid ligament, the smaller cornu of the hyoid 
bone, and lastly the glosso-palatine arch (His). 
The third arch (thyro-hyoid') forms the greater cornu and body of the hyoid bone and the 
pharyngo-palatine arch (His). 
The fourth arch gives rise to the thyroid cartilage (His). 
Branchial Clefts.—The first branchial or visceral cleft is represented by the external audi- 
tory meatus, the tympanic cavity, and the Eustachian tube; all the other clefts close. Should 
one or other of the clefts remain open, a condition that is sometimes hereditary in some families, 
a cervical fistula results, and it may be formed either from without or within. Sometimes 
only a blind diverticulum remains. Branchiogenic tumors and cysts depend upon the branchial 
arches (/?. Volkniann). 
[Relation of Branchial Clefts to Nerves.—It is important to note that the clefts in front 
of the mouth (pre-oral), and those behind it (post-oral), have a relation to certain nerves. 
The lachrymal slit between the frontal and nasal processes is supplied by the first division of 
the trigeminus. The nasal slit between the superior maxillary process and the nasal process is 
supplied by the bifurcation of the third nerve. The oral cleft, between the superior maxillary 
processes and the mandibular arch, is supplied by the second and third divisions of the trige- 
minus. The first post-oral or tympanic-Eustachian cleft, between the mandibular arch (ist) 
and the hyoid arch, is supplied by the portio-dura. The next cleft is supplied by the glosso- 
pharyngeal, and the succeeding clefts by branches of the vagus.~\ 
The thymus and thyroid glands are formed as paired diverticula from the epithelium cov- 
ering the branchial arches. The epithelium of the last two clefts does not disappear (pig), but 
proliferates and pushes inwards cylindrical processes, which develop into two epithelial vesicles, 
the paired commencement of the thyroid glands. These vesicles have at first a central slit, 
which communicates with the pharynx ( Wolfler). According to His, the thyroid gland appears 
as an epithelial vesicle in the region of the 2d pair of visceral arches in front of the tongue— 
in man at the 4th week. Solid buds, which ultimately become hollow, are given off from the 
cavity in the centre of the embryonic thyroid gland. The two glands ultimately unite together. 
The only epithelial part of the thymus which remains is the so-called concentric corpuscles 
(p. 178). According to Born, this gland is a diverticulum from the 3d cleft, while His ascribes 
its origin to the 4th and 5th aortic arches in man at the 4th week. The carotid gland is of 
epithelial origin, being a variety of the thyroid (Stieda). 
The Extremities.—The origin and course of the nerves of the brachial plexus (§ 355) show 
that the upper extremity was originally placed much nearer to the cranium, while the position 
of the posterior extremity corresponds to the last lumbar and the 3d or 4th sacral veretebrse 
(His). 
The clavicle, according to Bruch, is not a membrane bone, but is formed in cartilage like 
the furculum of birds (Gegenbaur). At the 2d month it is four times as large as the upper 
limb ; it is the first bone to ossify at the 7th week. At puberty a sternal epiphysis is formed. 
Episternal bones must be referred to the clavicles (Gotte). Ruge regards pieces of cartilages 
existing between the clavicle and the sternum as the analogues of the episternum of animals. 
The clavicle is absent in many mammals (carnivora); it is very large in flying animals, and in 
the rabbit is half membranous. The furculum of birds represents the united clavicles. 
The scapula at first is united with the clavicle (Rathke, Gotte), and at the end of the 2d 
month it has a median centre of ossification, which rapidly extends. Morphologically, the 
accessory centre in the coracoid process is interesting; the latter also forms the upper part of 
the articular surface. In birds the corresponding structure forms the coracoid bone, and is 
united with the sternum; while in man only a membranous band stretches from the tip of the 
coracoid process to the sternum. The long, basal, osseous strip corresponds to the supra- 
scapular bone of many animals. The other centres of ossification are—one in the lower angle, 
two or three in the acromion, one in the articular surface, and an inconstant one in the spine. 
Complete consolidation occurs at puberty. 
The humerus ossifies at the 8th to the 9th week in its shaft. The other centres are—one in 
the upper epiphysis, and one in the capitellum (ist year); one in the great tuberosity and one 
in the small tuberosity (2d year) ; two in the condyles (5th to 10th year); one in the trochlea 
(12th year). The epiphyses unite with the shaft at the 16th to 20th year. 
The radius ossifies in the shaft at the 3d month. The other centres are—one in the lower 
epiphysis (5th year), one in the upper (6th year), and an inconstant one in the tuberosity, and 
one in the styloid process. They unite at puberty. 
The ulna also ossifies in the shaft at the 3d month. There is a centre in the lower end Sec. 447.] 
DEVELOPMENT OF THE HIND LIMB. 
(6th year), two in the olecranon (nth to 14th year), and an inconstant one in the coronoid 
process, and one in the styloid process. They consolidate at puberty. 
The carpus is arranged in mammals in two rows. The first row contains three bones—the 
radial, intermediate, and ulnar bones. In man these are represented by the scaphoid, semi- 
lunar, and cuneiform bones; the pisiform is only a sesamoid bone in the tendon of the 
flexor carpi ulnaris. The second row really consists of as many bones as there are digits (e.g., 
salamander). In man the common position of the 4th and 5th fingers is represented by the 
unciform bone. Morphologically, it is interesting to observe that an os centrale, corresponding 
to the os carpale centrale of reptiles, amphibians, and some mammals, is formed at first, but 
disappears at the 3d month, or unites with the scaphoid. Only in very rare cases is it 
persistent. All the carpal bones are cartilaginous at birth. They ossify as follows: Os mag- 
num, unciform (1st year), cuneiform (3d year), trapezium, semilunar (5th year), scaphoid (6th 
year), trapezoid (7th year), and pisiform (12th year). 
The metacarpal bones have a centre in their diaphyses at the end of the 3d month, and so 
have the phalanges. All the phalanges and the first bone of the thumb have their cartilaginous 
epiphyses at the central end, and the other metacarpal bones at the peripheral end, so that the 
first bone is to be regarded as a phalanx. The epiphyses of the metacarpal bones ossify at the 
2d, and those of the phalanges at the 3d year. They consolidate at puberty. 
The innominate bone, when cartilaginous, consists of two parts—the pubis and the ischium 
{Rosenberg). Ossification begins with three centres—one in the ilium (3d to 4th month), one 
in the descending ramus of the ischium 
(4th to 5th month), one in the horizontal 
ramus of the pubis (5th to 7th month). 
Between the 6th to the 14th year, three 
centres are formed where the bodies of the 
three bones meet in the acetabulum, 
another in the superficies auricularis, and 
one in the symphysis. Other accessory 
centres are : One in the anterior inferior 
spine, the crests of the ilium, the tuberosity 
and the spine of the ischium, the tubercu- 
lum pubis, eminentia ilio-pectinea, and floor 
of the acetabulum. At first the descend- 
ing ramus of the pubis and the ascend- 
ing ramus of the ischium unite at the 7th to 
8th year; the Y-shaped suture in the ace- 
tabulum remains until puberty (fig. 823). 
The femur has its middle centre at the 
end of the 2d month. At birth, there is a 
centre in the lower epiphysis; slightly later 
in the head. In addition, there is one in 
the great trochanter (3d to Iith year), one 
in the lesser trochanter (13th to 14th year), 
two in the condyles (4th to 8th year); all 
unite about the time of puberty. The pa- 
tella is a sesamoid bone in the tendon of 
the quadriceps femoris. It is cartilaginous 
at the 2d month, and ossifies from the 1st 
to the 3d year. 
The tarsus generally resembles the car- 
pus. The os calcis ossifies at the beginning 
of the 7th month, the astragalus at the beginning of the 8th month, the cuboid at the end of 
the 10th month, the scaphoid (1st to 5th year), the I and II cuneiform (3d year), and the 
III cuneiform (4th year). An accessory centre is formed in the heel of the calcaneum at the 
5 th to 10th year, which consolidates at puberty. 
The metatarsal bones are formed like the metacarpals, only later. 
[Histogenesis of Bone.—The great majority of our bones are laid down in cartilage, or are 
preceded by a cartilaginous stage, including the bones of the limbs, backbone, base of the skull, 
sternum, and ribs. These consist of solid masses of hyaline cartilage, covered by a membrane, 
which is identical with and ultimately becomes the periosteum. The formation of bone, when 
preceded by cartilage, is called endochondral bone. Some bones, such as the tabular bones 
of the vault of the cranium, the facial bones, and part of the lower jaw, are not preceded by car- 
tilage. In the latter there is merely a membrane present, while from and in it the future bone is 
formed. It becomes the future periosteum as well. This is called the intra-membranous or 
periosteal mode of formation.] 
Centres of ossification of the innominate bone. 
Fig. 823. GROWTH OF BONE. 
[Sec. 447. 
[Endochondral Formation of Bone.—(1) The cartilage has the shape of the future bone 
only in miniature, and it is covered with periosteum. In the cartilage an opaque spot or centre 
of ossification appears, due to the deposition of lime-salts in its matrix. The cartilage cells pro- 
liferate in this area, but the first bone is formed under the periosteum in the shaft, so that an os- 
seous case like a muff surrounds the cartilage. This bone is formed by the sub-periosteal osteo- 
blasts. (2) Blood-vessels, accompanied by osteoblasts and connective-tissue, grow into the 
cartilage from the osteogenic layer of the periosteum (periosteal processes of Virchow), so that 
the cartilage becomes channelled and vascular. As these channels extend they open into the 
already enlarged cartilage lacunae, absorption of the matrix taking place, while other parts of the 
cartilaginous matrix become calcified. Thus a series of cavities, bounded by calcified cartilage 
—the primary medullary cavities—are formed. They contain the primary or cartilage mar- 
rozv, consisting of blood-vessels, osteoblasts, and osteoclasts, carried in from the osteogenic 
layer of the periosteum, and of course the cartilage cells that have been liberated from their lacu- 
nte. (3) The osteoblasts are now in the interior of the cartilage, where they dispose themselves 
on the calcified cartilage, and secrete or form around them an osseous matrix, thus enclosing the 
Fig. 824.—I, Tibia of a dog. A silver plate (d) was inserted under the periosteum, and on the 
dog being killed after some weeks it was found embedded in the bony shaft at d II. Ill 
shows a similar bone, where two plates of silver were placed under the periosteum at differ- 
ent times, and after several weeks the one, d, was found deeper in the bone than the other. 
Fig. 825.—Ivory pegs (2 and 3) inserted into the shaft of a growing tibia of a dog. The 
pegs are still the same distance apart in the adult tibia (<r), while the pegs 1, 4, inserted in 
the epiphysis are widely separated in B and C from 2 and 3. 
Fig. 824. 
Fig. 825. 
calcified cartilage, while the osteoblasts themselves become embedded in the products of their 
own activity and remain as bone-corpuscles. Bone therefore is at first spongy bone, and as 
the primary medullary spaces gradually become filled up by new osseous matter it becomes denser, 
while the calcified cartilage is gradually absorbed. It is to be remembered that, pari passu with 
the deposition of the new bone, bone and cartilage are being absorbed by the osteoclasts (fig. 
422).] 
Chemical Composition of Bone.—Dry Bone contains of organic matter or ossein, 
from which gelatin can be extracted by prolonged boiling; and about % mineral matter, which 
consists of neutral calcic phosphate, 57 per cent.; calcic carbonate, 7 per cent.; magnesic phos- 
phate, 1 to 2 per cent.; calcic fluoride, 1 per cent., with traces of chlorine ; and water about 23 
per cent. The marrow contains fluid fat, albumin, hypoxanthin, cholesterin, and extractives. 
The red marrow contains more iron, corresponding to its larger proportion of haemoglobin (Nasse). 
[The medullary cavity of a long bone is occupied by yellow marrow, which contains about Sec. 447.] 
FORMATION OF THE HEART. 
g6 per cent, of fat. The red marrow occurs in the ends of long bones, in the fiat bones of the 
skull, and in some short bones. It contains very little fat, and is really lymphoid in its charac- 
ters, being, in fact, a blood-forming tissue (\ 7, C).] 
Growth of Bones.—Long bones grow in thickness by the deposition of new bone from the 
periosteum, the osteoblasts becoming embedded in the osseous matrix to form the bone-corpuscles. 
This is proved by inserting a silver plate under the periosteum; after a time bone is formed 
between the plate and the periosteum, and so the plate comes to lie in the shaft of the bone (fig. 
824, d). Some of the fibres of the connective tissue, which are caught up, as it were, in the 
process, remain as Sharpey’s fibres, which are calcified fibres of white fibrous tissue, bolting 
together the peripheric lamelke. [Muller and Schafer have shown that there also fibres in the 
peripheric lamellae, comparable to yellow elastic fibres; they branch, stain deeply with magenta, 
and are best developed in the bones of birds.] 
[At the same time that bone is being deposited on the surface, it is being absorbed in the mar- 
row cavity by the action of the osteoclasts, so that a metallic ring placed round a bone in a 
young animal ultimately comes to lie in the medullary cavity (Duhamel). The growth in 
length takes place by the continual growth and ossification of the epiphysial cartilage. The 
cartilage is gradually absorbed from below, but it proliferates at the same time, so that what is 
lost in one direction is more than made up in the other (J. Httnter). 
[The growth in length is shown by placing ivory pegs into a growing bone at a measured dis- 
tance apart from each other, say 1 and 4 in the epiphysis and 2 and 3 in the shaft (fig. 825). 
The animals are allowed to live for some months, and then killed, when it is found that the dis- 
tance between the pegs in the shaft is unchanged (fig. 825, B and C), while the distance between 
the pegs in the epiphysis and those in the shaft is greatly increased, showing that the bone has 
grown in length by something intervening between the shaft and epiphysis. This is the epi- 
physial cartilage.] 
When the growth of bone is at an end, the epiphysis becomes united to the diaphysis, the 
epiphysial cartilage itself becoming ossified. It is not definitely proved whether there is an 
interstitial expansion or growth of the true osseous substance itself, as maintained by Wolff 
(i 244,9)- 
[Howship’s Lacunae.—The osteoclasts or myeloplaxes are large multinuclear giant-cells, 
which erode bone. They can be seen in great numbers lying in small depressions corresponding 
to them—Howship’s lacunae—on the fang of a temporary tooth, when it is being absorbed. 
They are readily seen in a microscopical section of spongy bones with the soft parts preserved.] 
The form of a bone is influenced by external conditions. The bones are stronger the greater 
the activity of the muscles acting on them. If pressure acting normally upon a bone be removed, 
the bone develops in the direction of least resistance, and becomes thicker in that direction. 
Bone develops more slowly on the side of the greatest external pressure, and it is curved by 
unilateral pressure (Lesshaft). 
448. DEVELOPMENT OF THE VASCULAR SYSTEM.—Heart.—[The heart 
appears as a solid mass of cells in the splanchnopleure, at the front end of the embiyo, immedi- 
ately under the “fore-gut.” Very soon a cavity appears in this mass of cells; some of the 
latter float free in the fluid, while the cellular wall begins to pulsate rhythmically. This hollow 
cellular structure elongates into a tube, which very soon assume a shape somewhat like an S 
(fig. 826, 1)] and there are indications of its being subdived into (a) an upper aortic part with 
the bulbus arteriosus ; (b) a middle or ventricular part; and (v), a lower venous or auric- 
ular part. The heart then curves on itself in the form of a horse-shoe (2), so that the venous 
end (A) comes to lie above and slightly behind the arterial end. On the right and left side, 
respectively, of the venous part is a blind hollow outgrowth, which forms the large auricle on 
each side (3 0, 0,]. The flexure of the body of the heart corresponding to the great curvature 
(2, V), is divided into two large compartments (3), the division being indicated by a slight de- 
pression on the surface. The large truncus venosus (4, v), which joins with the middle of the 
posterior wall of the auricular part, is composed of the superior and inferior venae cavae. This 
common trunk is absorbed at a later period into the enlarging auricle, and thus arise the separate 
terminations of the superior and inferior venae cavae. In man, the heart soon comes to lie in a 
special cavity, which in part is bounded by a portion of the diaphragm (//is). At the 4th to 5th 
week, the heart begins to be divided into a right and a left half. Corresponding to the position 
of the vertical ventricular furrow, a septum grows upwards vertically in the anterior of the heart, 
and divides the ventricular part into a right and left ventricle (5, R, L). There is a constriction 
in the heart, between the auricular and ventricular portions, forming the canalis auricularis. 
It contains a communication between the auricle and both ventricles, lying between an anterior 
and posterior projecting lip of endothelium, from which the auriculo-ventricular valves are 
formed (F. Schmidt). The ventricular septum grows upwards towards the canalis auricularis, 
and is complete at the 8th week. Thus, the large undivided auricle communicates with the 
corresponding ventricle by a right and left auriculo-ventricular opening (5). At the same time 
two septa (4,/a) appear in the interior of the truncus arteriosus (4,/), which ultimately 1110 
DEVELOPMENT OF THE ARTERIES. 
[Sec. 448. 
meet, and thus divide this tube into two tubes (5, ap), the latter forming the aorta and pulmo- 
nary artery, and are disposed towards each other like the tubes in a double-barrelled gun. The 
septum grows downwards until it meets the ventricular septum (5), so that the right ventricle 
comes to be connected with the pulmonary artery, and the left with the aorta. The division of 
the truncus arteriosus, however, takes place only in the first part of its course. The division 
does not take place above, so that the pulmonary artery and aorta unite in one common trunk 
above. This communication between the pulmonary artery and the aorta is the ductus 
arteriosus Botalli (7, B). 
In the auricle a septum grows from the front and behind, ending internally with a concave 
margin. The vena cava superior (6, C!r) terminates to the right of this fold, so that its blood 
will tend to go towards the right ventricle, in the direction of the arrow in 6, x. The cava 
inferior, on the other hand (6, Ci), opens directly opposite the fold. On the left of its orifice the 
Fig. 826. 
Development of the heart. I, Early appearance of the heart—a, aortic part, with the bulbus,b; 
v, venous end. 2, Horse-shoe shaped curving of the heart—a, aortic end, with the 
bulbus, b; V, ventricle; A, auricular part. 3, formation of the auricular appendages, 
0, ov and the external furrow in the ventricle. 4, Commencing division of the aorta, 
p, into two tubes, a. 5, View from behind of the opened auricle, v, v, into the Z, and 
R, ventricles, and between the two latter the projecting ventricular septum, while the aorta 
(a) and pulmonary artery (/) open into their respective ventricles. 6, Relation of the 
orifices of the superior (Cs) and inferior vena cava (Ci) to the auricle (schematic view from 
above)—x, direction of the blood of the superior vena cava into the right auricle; y, that 
of the inferior cava to the left auricle; /Z, tubercle of Lower. 7, Heart of the ripe foetus— 
R, right, Z, left ventricle; a, aorta, with the innominate, c, c, carotid, c, and left subclavian 
artery, s; B, ductus arteriosus; p, pulmonary artery, with the small branches 1 and 2, to 
the lungs. 
valve of the foramen ovale is formed by a fold growing towards the auricular fold, so that the 
blood-current from the inferior vena cava goes only to the left, in the direction of the arrow, y; 
on the right of the orifice of the cava, and opposite the fold, is the Eustachian valve, which, 
in conjunction with the tubercle of Lower (tL), directs the stream from the inferior vena cava to 
the left into the left auricle, through the pervious foramen ovale. Compare the foetal circula- 
tion (| 445). After birth, the valve of the foramen ovale closes that aperture, while the 
ductus arteriosus also becomes impervious, so that the blood of the pulmonary artery is forced to 
go through the pulmonary branches proceeding to the expanding lungs. Sometimes the foramen 
ovale remains pervious, giving rise to serious symptoms after a time, and constituting morbus 
ceruleus. 
Arteries.—With the formation of the branchial arches and clefts, the number of aortic arches Sec. 448.] 
DEVELOPMENT OF THE VEINS. 
on each side becomes increased from 1 to 5 (fig. 827), which run above and below each branchial 
cleft in a branchial arch, and then all reunite behind in a common descending trunk (2, ad) 
(Rathke). These blood-vessels remain only in animals that breathe by gills (fig. 146). In man, 
the upper two arches disappear completely (3). When the truncus arteriosus divides into the 
The aortic arches. I. The first position of the I, 2, and 3 arches. 2. 5 aortic arches; ta, com- 
mon aortic trunk ; ad, descending aorta. 3. Disappearance of the upper two arches on each 
side—S, subclavian artery; v, vertebral artery; ax, axillary artery. 4. Transition to the 
final stage—P, pulmonary artery; A, aorta; dB, ductus arteriosus (Botalli); S, right sub- 
clavian, united with the right common carotid, which divides into the internal (Ci) and 
external carotid (Ce); ax, axillary; v, vertebral artery. 
Fig. 827. 
pulmonary artery and the aorta (4, P, A), the lowest arch on the left side, with its origin, forms 
the pulmonary artery (4), and it springs from the right side of the heart. Of these the left 
lowest arch forms the ductus arteriosus (dB), and from the commencement of the latter pro- 
ceed the pulmonary branches of the pulmonary artery. Of the remaining arches which are 
united with the aorta, the left middle one (i. e., the fourth left) forms the permanent aortic arch 
into which the ductus arteriosus opens, while the right one (fourth) forms the subclavian artery; 
the third arch forms on each side the origin of the carotids {Ci, Ce). The arteries of the first and 
second circulations have been referred to already (§ 442). When the umbilical vesicle, with 
its primary circulation, diminishes, only one omphalo-mesenteric artery is present, which gives a 
branch to the intestine. At a later period, the omphalo-mesenteric arteries atrophy, while the 
artery to the intestine—the superior 
mesenteric—becomes the largest of all, 
it being originally derived from one of 
the omphalo-mesenteric arteries. 
Veins of the Body.—The veins 
first formed in the body of the em- 
bryo itself are the two cardinal 
veins; on each side an anterior (fig. 
828, I, cs), and a posterior {ci), which 
proceed towards the heart and unite on 
each side to form a large trunk, the 
duct of Cuvier {PC), which passes 
into the venous part of the heart. The 
anterior cardinal veins give off the sub- 
clavian veins (bb) and the common 
jugular veins, which divide into the 
external (/<?) and internal (ft) jugular 
veins. In addition, there is a trans- 
verse anastomosing branch passing 
obliquely from the left (where it di- 
vides) to the right, which joins their 
trunk lower down. In the final ar- 
rangement (II) this anastomosis (As) 
becomes very large to form the left 
innominate vein, while with the 
growth of the arms the subclavian 
veins increase (bb); and lastly, the 
calibre of the jugular vein changes, 
the internal jugular (ft) becoming very 
large, and the external jugular (/<?) 
smaller. In some animals, e. g., the dog and rabbit, the large embryonic size is retained. The 
Fig. 828. 
I, First appearance of the veins of the embryo. II, 
Their transformations to form the final arrangement. THE PORTAL SYSTEM. 
[Sec. 448. 
part of the left superior cardinal vein, from the anastomosis downwards to the left duct of 
Cuvier, disappears. The posterior cardinal veins divide in the pelvis into the hypogastric 
(I, k) and external iliac (/,/)• The inferior cava at first is very small (I, Vc), divides at the 
entrance to the pelvis, and on each side goes into the point of division of the cardinal veins. 
There is also a transverse ascending anastomosis between the right and left cardinal veins. For 
the final arrangement, the cava inferior (II, Ci) dilates, and with it the hypogastric and exter- 
nal iliac vein on each side. The right cardinal vein remains very small (Vena azygos, Az), 
and also the lower part from the left one to the transverse anastomosis. The latter itself also 
remains very small ( Vena hemiazygos, Hz). On the other hand, the upper part above the anas- 
tomosis to the duct of Cuvier disappears. Lastly, the common large venous trunk is so absorbed 
into the wall of the auricle ( V) that both venae cavae have each a separate orifice (p. 1101). 
The embryonic condition of the veins persists in fishes (fig. 146, I). 
Veins of the First and Second Circulation, and Portal System.—The two omphalo- 
mesenteric veins (om, omopen into the posterior or venous end of the tubular heart (fig. 829, 
iH). The right vein, however, disappears very soon. As soon as the allantois is formed, the 
two umbilical veins join the truncus venosus (1, u, zz,). At first the omphalo-mesenteric veins 
are larger than the umbilical veins ; at a later period this is reversed, and the right umbilical 
vein disappears. As soon as veins are formed within the body proper of the embryo, the 
inferior cava also opens into the truncus venosus (2, Ci). Gradually the umbilical vein (2, zzj) 
becomes the chief trunk, while the small omphalo-mesenteric (2, omx) carries little blood. 
Portal System.—The umbilical and omphalo-mesenteric veins pass in part directly under 
Development of the veins and portal system. H, heart; R, Z, right and left side of the body; 
om, right omphalo-mesenteric vein; omr, left; u, right umbilical vein; u, left; Ci, vena 
cava inferior; a, venae advehentes ; r, venae revehentes ; D, intestine; m, mesenteric vein; 
4, /, splenic vein; 2, /, liver. 
Fig. 829. 
the liver to reach the heart. They send branches—carrying arterial blood—to the liver, and the 
latter grows round these vessels. These branches are the venae advehentes (2 and 3,<r). The 
blood circulating through the liver from the venae advehentes is returned by other veins, the 
venae revehentes (2 and 3, r), which reunite at the blunt margin of the liver with the chief 
trunk of the umbilical vein. The umbilical vein (3, ux) and the omphalo-mesenteric vein (3, 
omx) anastomose in the liver. When the intestine develops (3, D), the mesenteric vein (m) 
opens into the omphalo-mesenteric vein, and the splenic vein as well (4, /), when the spleen is 
formed. At a later period, when the omphalo-mesenteric vein (4, disappears, the vein 
from the intestine now becomes the common trunk of the previously united vessels. It unites in 
the liver with the umbilical vein to form the trunk of the vena portae. When, after birth, the 
umbilical vein disappears (4, «j), the mesenteric alone remains as the portal vein. As the 
ductus venosus is obliterated, the portal vein must send its blood through the liver, and thus 
the portal circulation is completed. 
449. FORMATION OF THE INTESTINAL CANAL.—The primitive intestine, 
or gut, consists of a straight tube proceeding from the head to the tail. The vitelline duct is in- 
serted at that point, which at a later period corresponds to the lower part of the ileum. At the 
4th week the tube makes a slight bend towards the umbilicus (fig. 830,1). As already mentioned, 
the vitelline duct is obliterated, remaining only for a time as a thread attached to the intestine, 
being still visible at the 3d month. Sometimes it remains as a short blind tube communicating 
with the intestine. This is the so-called “ true intestinal diverticulum ” ; occasionally a cord— 
the obliterated omphalo-mesenteric vessels—passes from it to the umbilicus. In very rare cases, Sec. 449.] 
DEVELOPMENT OF THE INTESTINE. 
1113 
the duct may remain open as far as the umbilicus, forming a congenital fistula of the ileum, or it 
may give rise to cystic formations (M. Roth). In a human foetus at the 4th week, His distin- 
guished the cavity of the mouth, pharynx, oesophagus, stomach, duodenum, mesenterial intestine, 
and the hind-gut, with the cloaca. The intestine then forms the first coil (fig. 830, II) by rotat- 
ing on itself at the intestinal umbilicus, so that the lower part of the intestine lying next the 
Fig. 830. 
Fig. 831. 
Fig. 830.—Development of the intestine, v, stomach; 0, insertion of the vitelline duct; t, small 
intestine; c, colon; r, rectum. Fig. 831.—Formation of the lungs. A, Diverticula of 
the lungs as double sacs—k, mesoblastic layer; /, hypoblastic layer; m, stomach; s, 
oesophagus. B, Further branching of the lungs—t, trachea; b, e, bronchi; f, projecting 
vesicles. 
knee-like bend comes to lie above, while the upper part lies below. From the lower part of this 
loop there proceed the coils of the small intestine (III, t)> which gradually grow longer. From 
the upper limb of the loop, which also elongates, the large intestine is formed; first the de- 
scending colon, then by elongation the transverse colon, and lastly the ascending colon. 
Glands.—By diverticula, or protrusions from the intestine, the various glands are formed. 
The cells of the hypoblast pro- 
liferate and take part in the pro- 
cess, as they form the secretory 
cells of the glands, while the 
mesoblastic part of the splanch- 
nopleure forms the membranes 
of the glands, giving them their 
shape. The diverticula are as 
follows:— 
1. The salivary glands, 
which grow out from the oral 
cavity at first as simple solid 
buds, but afterwards become hol- 
low and branched. [The sali- 
vary glands are developed from 
the epiblast lining the mouth 
(stomodaeum).] 
2. The lungs, which arise as 
two separate hollow buds (fig. 
831, A, /), and ultimately have 
only one common duct, are pro- 
trusions from the oesophagus. 
The upper part of the united 
tracheal tube forms the larynx. 
The epiglottis and the thyroid 
cartilage originate from the part 
which forms the tongue (Gang- 
hofner). The two hollow spheres 
grow and ramify like branched 
tubular glands with hollow pro- 
cesses (B,/). In the first period 
of development there is no essen- 
tial difference between the epithelium of the bronchi and that of the primitive air-vesicles (Stieda). 
Fig. 832. 
Formation of the omentum. I and II, hg, gastro-hepatic liga- 
ment ; ?n, great, n, lesser curvature of the stomach ; s, pos- 
terior, and i, anterior fold or plate of the omentum; me, 
mesocolon; c, colon. Ill, L, liver; t, small intestine; b, 
mesenterypancreas; d, duodenum; r,rectum ; N, great 
omentum. 1114 
URINARY APPARATUS. 
[Sec. 449. 
The spleen and suprarenal capsules, however, are not developed in this way. The former 
arises in a fold of the mesogastrium at the 2d month (Mis); the latter are originally larger than 
the kidneys. 
3. The pancreas arises in the same way as the salivary glands, but is not visible at the 4th 
week (His). 
4. The liver begins very early, and appears as a diverticulum, with two hollow primitive 
hepatic ducts, which branch and form bile-ducts. At their periphery they penetrate between 
the solid masses of cells—the liver-cells—which are derived from the hypoblast. At the 2d 
month the liver is a large organ, and secretes at the 3d month ($ 182). 
5. In birds two small blind sacs are formed from the hind-gut. 
6. The foetal respiratory organ, the allantois, is treated of specially (g 444). 
Peritoneum and Mesentery.—The inner surface of the ccelom, or body cavity, the surface 
of the intestine, and its mesentery are covered by a serous coat—the peritoneum. At first the 
simple intestine is contained in a fold, or duplicature of the peritoneum; on the stomach, which 
is merely at first a spindle shaped dilatation of the tube placed vertically, it is called mesogas- 
trium. Afterwards, the stomach turns on its side, so that the left surface is directed forwards 
and the right backwards. Thus, the insertion of the mesogastrium, which originally was 
Development of the internal generative organs. I, Undifferentiated condition—D, reproductive 
gland, lying on the tubules of the Wolffian body; W, Wolffian duct; M, Mullerian duct; 
S, uro genital sinus. II, Transformations in the female—F, fimbria, with the hydatid, hx; 
T, Fallopian tube; U, uterus; S, uro-genital sinus; O, ovary; P, parovarium. Ill, Trans- 
formations in the male—H, testis; E, epididymis, with the a, vas aberrans; 
V, vas deferens; S, uro-genital sinus; u, male uterus. 4, d, hind-gut; a, allantois; 
u, urachus; K, cloaca. 5, M, rectum; m, perineum; b, position of the bladder; S, uro- 
genital sinus. 
Fig- 833- 
directed backwards (to the vertebral column), is directed to the left; the line of insertion 
forming the region of the great curvature, which becomes still more curved. From the great 
curvature, the mesogastrium becomes elongated like a pouch (fig. 832, I and II, s, i), constitut- 
ing the omental sac, which extends so far downwards as to pass over the transverse colon and 
the loops of the small intestine (fig. 832, III, A"). As the mesogastrium originally consists of 
two plates, of course the omentum must consist of four plates. At the 4th month, the posterior 
surface of the omental sac unites with the surface of the transverse colon (Joh. Muller). 
450. URINARY AND GENERATIVE ORGANS.—Urinary Apparatus.—The 
first indication of this apparatus occurs in the chick at the 2d day and in the rabbit at the 9th, as 
the at first solid ducts of the primitive kidneys or Wolffian ducts (fig. 833, X, W), which are 
formed from some cells mapped off from the lateral plate above and to the side of the protover- 
tebrae, and extending from the fifth to the last vertebra. The ducts are solid at first, but soon 
become hollow, and from their cavities there extend laterally a series of small tubes, which in 
the chick communicate freely with the peritoneal cavity (Kolliker). Into one end of each of 
these tubes grows a tuft of blood-vessels forming a structure resembling the glomeruli of the 
kidney. The tubes elongate, form convolutions, and increase in number. The upper end of 
the Wolffian duct is closed at first, its lower end, which lies in a projecting fold—the plica uro- 
genitalis of Waldeyer—in the peritoneal cavity, opens into the uro-genital sinus. Close above Sec. 450.] 
MULLERIAN DUCTS. 
the orifice of the Wolffian duct appeirs the ureter as the duct of the kidney. The duct 
elongates, and branches at its upper end. Each canal at its end is like a stalked caoutchouc sac 
( Toldt), and into it there grow the already formed glomeruli. The duct of the kidney opens 
independently into the uro-genital sinus, and forms the ureter. The part where the branching 
of the duct stops forms the pelvis of the kidney, and the branches themselves the renal tubules. 
Toldt found Malpighian corpuscles in the human kidney at the 2d month, and Henle’s loops at 
the 4th. The first appearance of the urinary bladder is at the 4th week (His), and is more 
distinct at the 2d month, as the dilated first part of the allantois (fig. 833). The upper part of 
the allantois remains as the obliterated urachus, in the middle vesicle ligament. 
Internal Reproductive Organs.—In front of and internal to the Wolffian bodies there 
arises in the mesoblast the elongated reproductive gland, germ-ridge, or mass of germ-epithe- 
lium (fig. 833, I, D), which in both sexes is originally alike (fig. 834, K, E). In addition, there 
is formed a canal or duct parallel to the Wolffian duct (W), which also opens into the uro-genital 
sinus; this is Muller’s duct (M). The elevation 
of the future reproductive gland is covered origin- 
ally by germ-epithelium ( Waldeyer). The upper 
end of the Mullerian duct opens free into the ab- 
dominal cavity, while the lower ends of both 
ducts unite for a distance. Some of the germinal 
cells covering the surface of the future ovary en- 
large to form ova, and sink into the stroma to form 
ova embedded in their Graafian follicles ($ 433) 
(fig. 834). In the female, the Mullerian ducts 
form the Fallopian tube (II, T), and the lower 
united ends the uterus. 
In the male, the germ-epithelium is not so tall. 
According to Waldeyer, there are two kinds of 
tubes in the Wolffian bodies, and some of these 
penetrate the position of the reproductive gland. 
These tubes, which are connected with the Wolff- 
ian ducts, become the seminiferous tubules (v. 
IVittich), and the Wolffian duct itself becomes 
the vas deferens, with the vesiculae seminales. Ac- 
cording to some other observers, however, tubes 
which become the seminiferous tubules are devel- 
oped within the reproductive gland itself, and 
these tubes lined with their germ-epithelium 
ultimately form a connection with the Wolffian 
ducts. 
The Mullerian ducts, which are really the 
ducts of the reproductive glands, disappear in 
man, all except the lowest part, which becomes 
the male uterus or vesicula prostatica (III, u)— 
the homologue of the uterus. The upper tubules 
of the Wolffian body unite at the 3d month with 
the reproductive gland (which has now become 
the body of the testis), and become the coni vas- 
culosi of the epididymis, which are lined by cili- 
ated epithelium (E); the remainder of the Wolff- 
ian body disappears. Some detached tubules 
form the vasa aberrantia (a) of the testicle (Kobelt). 
The hydatid of Morgagni (h), at the head of the 
epididymis, according to Luschka and others, is a 
part of the epididymis—Fleischl regards it as the 
rudiment of the male ovary. The organ of 
Giraldes is part of the Wolffian body. 
Wolffian duct itself becomes the vas deferens (V) from which the vesiculae seminales are de- 
veloped. The two Wolffian and two Mullerian ducts, as they enter the pelvis, unite to form a 
common cord—the genital cord. 
In the female, the tubes of the Wolffian bodies disappear, all except a few tubules, lined with 
ciliated epithelium, constituting the parovarium, or organ of Rosenmtiller (fig. 786), and a part 
analogous to the organ of Giraldes in the broad ligament of the uterus (Waldeyer) (fig. 833, P). 
The same is the case with the Wolffian ducts. In some animals (ruminants, pig, cat, and fox) 
they remain permanently as the ducts of Gaertner. 
The Mullerian duct is expanded at its upper end to form the fimbriae of the Fallopian tube, 
Fig. 834. 
Section of mammalian ovary, showing 
development of ova, and their follicles. 
Ei, Ripe ovum; G, follicular cells of 
germinal epithelium; g, blood-vessels; 
K, germinal vesicle and spot; KE, 
germinal epithelium; Lf liquor folli- 
culi; Mg, membrana granulosa; Mp, 
zona pellucida; PS, ingrowths from 
germinal epithelium, ovarian tubes, by 
means of which some of the nests retain 
their connection with the epithelium; 
S, cavity which appears within the 
Graafian follicle; So, stroma of ovary; 
Tf, Theca folliculi or ovi-capsule; U, 
primitive ova. 1116 
GENERATIVE ORGANS. 
[Sec. 450. 
and it is often provided with a hydatid (h1). That part of the uro-genital sinus into which the 
four ducts open grows above into a hollow sphere, which forms the vagina (Rathke). According 
to Thiersch and Leuckart, however, the two Mullerian ducts unite at their lower ends to form 
the united uterus (U) and vagina, while their free upper ends form the Fallopian tubes (T). The 
Mullerian ducts at first open into the posterior part of the urinary bladder below the ureters 
(uro-genital sinus, S), while ultimately this part of the bladder becomes so elongated pos- 
teriorly that the vagina (the united Mullerian ducts) and the urethra are united below and deeply 
within the vestibule of the vagina. At the 3d to the 4th month, the uterus and vagina are 
not separate from each other, but at the 5th to the 6th month the uterus is defined from the 
vagina. 
The testicles lie originally in the lumbar region of the abdominal cavity (fig. 835, V, /), and 
are carried by a fold of the peritoneum—the mesorchium (m). From the hilum of the testicle 
a cord, the gubernaculum testis, runs through the inguinal canal into the base of the scrotum. 
At the same time a septum-like process is developed independently from the peritoneum to the 
base of the scrotum (pv). The testicle passes through the inguinal canal into the scrotum, but 
the mechanism and the cause of the descent are not accurately ascertained.—[Descent of testis, 
l 446.] 
The ovaries also descend somewhat. The round ligament of the uterus corresponds to the 
gubernaculum testis. A process of the peritoneum passes in the female into the inguinal canal 
as Nuck’s canal. It is rare to find the ovaries descending into the labia majora. 
[The origin of the urinary and generative organs is undoubtedly associated with the develop- 
ment of the Wolffian bodies. The researches of Semper and Balfour on elasmobranch fishes 
show that the process is a very complex one. There is a mass of cells on each side of the ver- 
tebral column, which is divided into three parts, the first called the pronephros, or head-kidney 
of Balfour and Sedgwick, the middle one, the mesonephros or Wolffian body, and the posterior 
one or metanephros, which is formed after the other two, gives origin to the permanent kidney 
in the amniota. The MUllerian duct is connected with the pronephros, the Wolffian duct with 
the mesonephros, and the ureter with the metanephros.] 
[The following table, modified from Quain, shows the destiny of these structures:— 
MUllerian Ducts (Ducts of the Pronephros). 
Female. 
Fallopian tubes. 
Hydatid. 
Uterus and vagina. 
Male. 
Hydatid of Morgagni. 
Male uterus. 
Wolffian Bodies (Mesonephros). 
Parovarium. Vasa efferentia, Coni vasculosi, 
Paroophoron. Organ of Giraldes, Vasa aberrantia. 
Round ligament of the uterus. Gubernaculum testis. 
Wolffian Ducts. 
Chief tube of parovarium. Convoluted tube of epididymis. 
Ducts of Gaertner. Vas deferens and vesiculae seminales. 
Metanephros. 
Kidney. Ureter.] 
The external genitals are at first not distinguishable in the two sexes (fig. 835, I). At the 
14th week there is merely an orifice at the posterior extremity of the trunk, representing both the 
anus and the opening of the urachus, and forming a cloaca (fig. 833, 4, K). In front of this an 
elevation—the genital eminence—appears about the 6th week, and on each side of the orifice 
a large cutaneous elevation (fig. 835, II, w). At the end of the 2d month, there is a groove on 
the under surface of the genital eminence, leading back to the cloaca, and with distinct walls 
bounding it (II, r). At the middle of the 3d month, the cloacal opening is divided by the 
growth of the perineum, between the urachus (now become the urinary bladder) (fig. 833, 5, b) 
and the rectum (M). 
In the male, the genital eminence enlarges, its groove deepens from the opening of the 
bladder onwards to the apex of the elevation at the 10th week. The two edges unite to enclose 
the groove, which becomes the urethra. When this does not take place, hypospadias occurs. 
At the 4th month the glans, and at the 6th the prepuce, are formed. The large cutaneous folds 
meet in the middle line or raphe to form the scrotum. 
In the female the undifferentiated condition remains to a certain extent permanent. The 
small genital eminence remains as the clitoris, the margins of its furrow become the nymphae, Sec. 450.] 
GENERATIVE ORGANS. 
1117 
the cutaneous elevations remain separate to form the labia majora. The uro-genital sinus 
remains short as the vestibule of the vagina, while in man, by the closing of the genital groove, 
it has a long additional tube, the urethra. [The accompanying illustrations, after Schroeder, 
show the changes of the external organs of generation in the female. In the early period (6th 
week), the hind-gut (fig. 836, R), allantois (ALL), and the Miillerian ducts (M) communicate, 
but not with the exterior. About the 10th week a depression or inflection of the skin—genital 
cleft—takes place, until it meets the hind gut and allantois, whereby the cloaca (fig. 837, CL) 
Development of the external genitals. / and II.—Genital eminence; r, genital groove; s, 
coccyx; w, cutaneous elevations. IV.—P, penis; R, raphe penis; S, scrotum. III.— 
c, clitoris; /, labia minora; Z, labia majora; a, anus; V. and VI.—Descent of the 
testicle; /, testis; /«, mesorchium ; pv, processus vaginalis of the peritoneum; M, abdomi- 
nal wall; S, scrotum. 
Fig- 835. 
is formed. The cloaca is then divided into an anterior part, the uro-genital sinus, into which 
the Mullerian ducts open, and a posterior part, the anus. There is a downward growth of the 
tissue between the hind-gut and the allantois to form the perineum (fig. 838). The uro-genital 
sinus then contracts at its upper part to form the short urethra, its lower part remaining as the 
vestibule (fig. 839, SV), while the vagina has been formed by the union of the lower parts of 
the two Mullerian ducts. The bladder (B) is the expanded lower end of the stalk of the 
allantois.] 
Fig. 836. 
Fig- 837. 
Fig. 838. 
Fig. 839. 
Fig. 836.—R, rectum continuous with the allantois (ALL—Bladder); M, duct of Muller 
(vagina); A, depression of skin below genital eminence, growing inwards to form the 
vulva. Fig. 837.—The depression has become continuous with the rectum and allantois to 
form the cloaca (CL). Fig. 838.—The cloaca is becoming divided into uro-genital sinus 
(SU) and anus by the downward growth of the perineal septum. The ducts of Muller are 
united to form the vagina (V). Fig. 839.—Perineum completely formed. 
The causes of the difference of sex are by no means well known. From a statistical 
analysis of 80,000 cases, the influence of the age of the parents has been shown by Kofacker 
and Sadler. If the husband is younger than the wife, there are as many boys as girls; if both 
are of the same age, there are 1029 boys to 1000 girls; if the husband is older, 1057 boys to 
1000 girls. In insects food has a most important influence. Pfiiiger’s investigations on frogs 
show that all external conditions during development are without effect on the determination of 
the sex, so that the latter would seem to be determined before impregnation. 1118 
DEVELOPMENT OF THE NERVOUS SYSTEM. 
[Sec. 451. 
451- FORMATION OF THE CENTRAL NERVOUS SYSTEM.—Fore-brain. 
—At each side of the fore-brain, or anterior cerebral vesicle, which is covered externally by 
epiblast and internally by the ependyma, there grows out a large stalked hollow vesicle, the 
rudiment of the cerebral hemispheres. The relatively wide opening in the stalk, or com- 
munication, ultimately becomes very small, and is the foramen of Monro. The middle par 
between the two cerebral vesicles remains small and is the ’tween or interbrain with the 3d 
ventricle in its interior. It elongates at the second month towards the base of the brain as a 
funnel-shaped projection, to form the tuber cinereum with the infundibulum. The thalami 
optici, projecting and enlarging from the sides of the 3d ventricle, narrow the foramen of 
Monro to a semi-lunar slit. At the base of the brain are formed, in the 2d month, the corpora 
albicantia, at the 3d the chiasma; while within the 3d ventricle the commissures are formed. 
The hypophysis, belonging to the mid-brain, is a diverticulum of the nasal mucous membrane, 
extending through the base of the skull towards the hollow infundibulum, which grows to meet 
it (fig. 631, T). There is, as it were, a tendency to the union of the cavity of the fore-gut with 
the medullary tube. In the amphioxus (.Kowalewsky), goose (Gasser), and lizard (Strahl) the 
medullary tube communicated originally with the hind-gut by the canalis myelo-entericus. The 
choroid plexus, which grows into the ventricles of the hemispheres through the foramen of 
Monro, is a vascular development of the ependyma. At the 4th month, the conarium (pineal 
gland) is formed, and at this time the corpora quadrigemina cover the hemispheres. The 
corpora striata begin to be developed in the cerebral (lateral) ventricle at the 2d month, 
while the cornu ammonis is formed at the 4th month. [The external walls and floor of the 
primitively simple central hemispheres become much thickened, the thickenings in the floor 
constitute the corpora striata, which protrude into the lateral ventricles, their position being indi- 
cated on the surface of the brain by the Sylvian fissure. As they extend backwards they become 
connected with the optic thalami (fig. 840, st, th). The corpora striata are connected together 
by the anterior commissure. From the inner wall of each hemisphere there grow into each 
lateral ventricle two projections; the upper one forms the hippocampus major or cornu 
ammonis (%• 840, k), while the lower one becomes folded, remains thin, receives numerous 
blood-vessels from the falx cere- 
bri, and forms the choroid 
plexus (fig. 840, //).] At the 
3d month, the Sylvian fissure is 
formed, and the basis of the island 
of Reil. The permanent cerebral 
convolutions are formed from the 
7th month onwards. 
The mid-brain, or middle 
cerebral vesicle, is gradually cov- 
ered over by the backward 
growth of the hemispheres; its 
cavity forms the aqueduct of 
Sylvius (fig. 841). Depressions 
appear on the surface of the 
vesicle to divide it into four, the 
corpora quadrigemina, in birds 
into two, the corpora bigemina 
(fig. 841, bg), the longitudinal 
depression being formed at the 
3d, and the transverse one at the 
7th month. The cerebral ped- 
uncle is formed by a thickening 
in the base of this vesicle. 
In the hind-brain are found 
the cerebellar hemispheres, which 
grow backwards to meet in the 
middle line. The vermis is 
formed at the 7th month. The 
cerebellum covers in the part of 
the medullary tube lying below 
it, which is not closed, as far as 
the calamus. The pons arises 
in the floor of the hind-brain at 
the 3d month. 
The spindle-shaped narrow 
after-brain forms the medulla 
oblongata, with the opening of the medullary tube in its upper part. 
Fig. 840. 
Transverse section of the brain of an embryo sheep 2.7 cm. 
long; x IO> a> cartilage of orbito-sphenoid; c, pedun- 
cular fibres; ch, optic chiasma ; /, median cerebral fissure; 
h, cerebral hemispheres, with a convolution upon their 
inner wall, projecting into the latter ventricle, l; m, fora- 
men of Monro; 0, optic nerve; p, pharynx; pi, lateral 
plexus; s, termination of the median fissure, which forms 
the roof of the third ventricle; sa, body of the anterior 
sphenoid; st, corpus striatum; t, third ventricle; th, ante- 
rior deep portion of the optic thalamus (Kblliker). Sec. 451.] 
NEUROBLASTS AND SPONGIOBLASTS. 
The following table, from Quain, shows the destiny of each cerebral vesicle:— 
1. Prosencephalon, . • , 
(fore-brain) 
2. Thalamencephalon, . . 
(inter or ’tween brain) 
Cerebral hemispheres, corpora striata, 
corpus callosum, fornix, lateral 
ventricles, olfactory bulb. 
I. Anterior Primary 
Vesicle, . . . 
Thalami optici, pineal gland, pitui- 
tary body, crura cerebri, aqueduct 
of Sylvius, optic nerve. 
II. Middle Primary 
Vesicle, . . . 
f 3. Mesencephalon, . . . 
( (mid-brain) 
Corpora quadrigemma, crura cerebri, 
aqueduct of Sylvius, optic nerve 
(secondarily). 
III. Posterior Primary 
Vesicle, . . . 
4. Epencephalon, . . . . 
(hind-brain) 
5. Metencephalon, . . . 
(after-brain) 
Cerebellum, pons, anterior part of 
the fourth ventricle. 
Medulla oblongata, fourth ventricle, 
auditory nerve. 
Spinal Cord.—The spinal cord is developed from the medullary tube behind the medulla 
oblongata, first the gray matter around the canal, while the white matter is added afterwards 
outside this. The ganglionic cells increase by division in amphibians (Lominsky). At first the 
spinal cord reaches to the coccyx. In the adult, the spinal cord reaches only to the 1st or 2d 
lumbar vertebrae, so that it does not elongate so much as the vertebral canal. It is a question 
how far this want of harmony in the development of these two structures may lead to disturbances 
of sensibility or paralysis of the lower limbs in children. The first muscles are formed in the 
back at the 2d month; at the 4th month 
they are red. The spinal ganglia are 
formed from a special strip of epiblastic 
cells. They are seen at the 4th week, and 
so are the anterior spinal roots and some of 
the trunks of the spinal nerves, while 
the posterior roots are still absent. At 
this period the ganglia of the 5th, 7th, 
8th, 9th, and 10th nerves and part of 
their origins are present, while the 1st, 
2d, 3d, and 12th nerves and the sympa- 
thetic are not yet differentiated {His). 
The motor spinal nerves grow out 
from the ganglia cells of the spinal cord, 
i.ir., from neuroblasts {His), and pene- 
trate into the peripheral parts of the 
body {His). At first they are devoid of 
myelin. The cells of the spinal ganglia 
are the parts from which the sensory 
nerves are developed. The nerve-fibres 
grow into the spinal cord, and there is 
also a peripheral prolongation towards 
the skin. 
[Neuroblasts and Spongioblasts. 
—When the laminae dorsales close in the 
medullary canal (p. 1090) and convert it 
into the neural canal, they nip off a 
small part of the epiblast from which is 
ultimately formed the cerebro-spinal axis. 
At first the tubular layer consists of one layer of neuro-epithelium; but at a very early stage two 
kinds of cells are found, one the “germinal cells ” and the other the “ spongioblasts ” or 
supporting cells {His). The germinal cells lie near the central canal between the inner ends 
of the spongioblasts (fig. 842), where they form an interrupted row. Each cell has a clear pro- 
toplasmic body and the nuclei show mitotic figures. The spongioblasts are columnar palisade- 
like cells with a radiate arrangement and with oval nuclei lying at some distance from the central 
canal. The outer ends of these eells give off processes which unite with processes from similar 
spongioblasts, and this forms the myelo-spongium. From the germinal cells are derived by 
mitosis the neuroblasts (fig. 843), which are pyriform-shaped cells with at first only one 
process, the axis-cylinder process, which gradually grows out into the anterior nerve-root, so 
that the fibres of the anterior roots are processes of the neuroblasts, which become the multi- 
polar nerve-cells of the cord. The lateral protoplasmic processes are developed after the axis- 
cylinder process. The fibres of the posterior root are not developed from their neuroblasts ; 
they are outgrowths of the nerve-cells in the spinal ganglia.] 
Diagram of an embryonic fowl’s brain, ac, anterior 
commissure; anv, anterior medullary velum, and 
below it the aqueduct of Sylvius and the cerebral 
peduncles; ba, basilar artery ; bg, corpora bige- 
mina ; cat, internal carotid artery ; cbl, cerebellum ; 
ch3, chA, choroid plexuses of the third and fourth 
ventricles; h, cerebral hemispheres; inf, infundi- 
bulum ; It, lamina terminalis; li, lateral ventricle ; 
obi, medulla oblongata; olf, olfactory lobe and 
nerve; opc, optic commissure; pin, pineal gland; 
pit, pituitary body; ps, pons Varolii; r, floor of 
fourth ventricle; st, corpus striatum; v3, third 
ventricle ; zA, fourth ventricle (Quain after Mihal- 
kovics). 
Fig. 841. DEVELOPMENT OF THE EYE. 
[Sec. 451. 
[Development of the Sympathetic Nervous System.—One set of observers (Balfour) 
hold that it is epiblastic in its origin, and another set (Onodi) regard it as mesoblastic. Paterson 
finds that it is of mesoblastic origin, and that it arises on either side of the body as a solid unseg- 
mented rod of cells lying close to the aorta, and at first it has no connections with the cord. It 
is subsequently connected to the cord by the ingrowth into it of the splanchnic branches of the 
spinal nerves, and after this connection is made it assumes a segmental appearance.] 
452. THE SENSE ORGANS.—Eye.—The primary optic vesicle grows out from the 
fore-brain towards the outer covering of the head or epiblast, and soon becomes folded in on 
itself (4th week), so that the stalked optic vesicle is shaped like an egg-cup (fig. 844, I). The 
cavity in the interior of this cup is called the secondary optic vesicle. The inflected part 
becomes the retina (IV, r), while the posterior part becomes the choroidal epithelium (IV, p). 
The stalk becomes the optic nerve. At the under surface of the depression there is a slit—the 
choroidal fissure—which permits some of the mesoblast to gain access to the interior of the 
eye. This slit forms the coloboma (II); it is prolonged backward on the stalk, and contains 
the central artery of the retina. The margins of the coloboma afterwards unite completely with 
each other, but in some rare conditions this does not take place, in which case we have to deal 
with a coloboma of the choroid or retina, as the case may be. In the bird the embryonic 
coloboma slit does not close up, but a vascular process of the mesoblast dips into it, and passes 
into the eye to form the pecten ($ 405). The same is the case in fishes, where there is a large 
vascular process of the meso- and epiblast, forming the processus falciformis ($ 405). 
The depression or inflection of the optic vesicle is due to the downgrowth into it of a 
thickening of the epiblast (I, L). It is hollow, and as it grows inwards ultimately becomes 
spherical and separated from the epiblast to form the crystalline lens, so that the lens is epi- 
blastic in its origin, while the capsule of the 
lens is a cuticular structure formed from the 
epiblast. That part of the epiblast which 
covers the vesicle in front of the lens ulti- 
mately becomes the stratified epithelium of 
the cornea. The layer of pigment of the 
invaginated optic vesicle is applied to the 
ciliary body, and the posterior surface of the 
iris, when the latter is formed. The cornea 
is formed at the 6th week. The substance 
of the choroid, sclerotic, and cornea is formed 
around the position of the eye from the 
mesoblast (m). The capsule of the lens is 
at first completely surrounded by a vascular 
Fig. 842. 
Fig. 843. 
Fig. 842.—A group of spongioblasts, sp; g, germinal cells; tr, transition cells between germ- 
cells and neuroblasts. Fig. 843.—Transverse section of half of the spinal cord of a trout- 
embryo; cc, central canal; tnli, membrana limitans interna; g, germinal cell; sp, spongio- 
blast ; nb, neuroblast; wc, white columns. 
membrane—the membrana capsulo-pupillaris. Afterwards, the lens passes more posteriorly 
into the eye—the anterior part of the capsulo-pupillary membrane, however, remains in the Sec. 452.] 
DEVELOPMENT OF SENSE-ORGANS. 
anterior part of the eye, while towards it grows the margin of the iris (7th week), so that the 
pupil is closed by this part of the vascular capsule, membrana pupillaris. The blood-vessels of 
the iris are continuous with those of the pupillary membrane; those of the posterior capsule of 
the lens give off the hyaloid artery, a continuation of the central artery of the retina; its veins 
pass into those of the iris and choroid. The vitreous humor at the 4th week is represented by a 
cellular mass between the lens and the retina. The pupillary membrane disappears at the 7th 
month. It may remain throughout life (V). 
Development of the eye. I, Inflexion of the sac of the lens (L) into the primary optic vesicle 
(P)—e, epidermis; m, mesoblast. II, The inflexion seen from below—«, optic nerve; e, 
the outer, i, the inner layer of the inflected vesicle; L, lens. Ill, Longitudinal section 
of II. IV, Further development—e, corneal epithelium; c, cornea; m, membrana 
capsulo-pupillaris; L, lens; a, central artery of the retina; s, sclerotic; ch, chonid; p, 
pigment layer of the retina; r, retina. V, Persistent remains of the pupillary membrane. 
Organ of Smell.—On the under surface and lateral limit of the fore-brain, the epiblast 
forms a groove or pit with thickened epithelium, which forms a depression towards the brain, 
but always remains as a pit or depression; this is the olfactory or nasal pit, to which the 
olfactory nerve afterwards sends its branches. For the formation of the nose see p. 1104. 
Organ of Hearing.—On both sides of the after-brain or posterior brain vesicle, above the 
first visceral or hyoid arch, there is a depression or pit formed in the epiblast, which gradually 
Fig. 844. 
Fig. 845. 
Early stages in the development of the vertebrate ear. A-D, early stages in the chick (fteissner). 
E, transverse section through the auditory pit of a 50 hours’ chick (Marshall). F, trans- 
verse section through the hind-brain of a foetal sheep. acv, anterior cardinal (jugular) 
vein; ao, aortic arch; dc, ductus cochlearis; rv, recessus (aqueductus) vestibuli; v, vesti- 
bulum; vs, vertical semicircular canal; viii, auditory nerve; rich, notochord. 
extends deeper towards the brain—this is the labyrinth pit or auditory sac, which soon be- 
comes flask-shape i (fig. 845, A, B). 
[The stalk, which originally connected the cavity of the sac with the surface, persists as the 
aqueductus vestibuli; and its blind swollen distal extremity as the saccus endolymphaticus, 
or recessus vestibuli (Haddon, fig. 845, r, z/).] The pit is ultimately completely cut off from BIRTH. 
[Sec. 453. 
the epiblast, just like the lens, and is now called the vesicle of the labyrinth or primary 
auditory vesicle. Its related portion forms the utricle, from which, at the 2d month, the 
semicircular canals and the cochlea are developed (fig. 845, D). The union with the brain 
occurs later, along with the development of the auditory nerve. The first visceral cleft remains 
as an irregular passage from the Eustachian tube to the external auditory meatus. The outer 
ear appears at the 7th week. 
Organ of Taste.—The gustatory papillae are developed in the later period of intra-uterine 
life, and several days before birth the taste-buds appear (Fr. Hermann). 
453. BIRTH .—With the growth of the ovum, the uterus becomes more 
distended, its walls more muscular and more vascular, although the uterine 
walls are not thicker at the end of pregnancy. Toward the end of gestation 
the cervical canal is intact until labor begins, or at any rate it is but slightly 
opened up at its upper part. After a period of 280 days of gestation, “ labor” 
begins, whereby the contents of the uterus are discharged. The labor pains 
occur rhythmically and periodically, being separated from each other by inter- 
vals free from pain. Each pain begins gradually, reaches a maximum, and 
then slowly declines. With each pain the heat of the uterus increases (§ 303), 
while the heart-beat of the foetus becomes slower and feebler, which is due to 
stimulation of the vagus in the medulla oblongata (§ 369, 3). 
[At the full time the membranes and placenta line the uterus. The mem- 
branes consist, from within outwards, of amnion, chorion, decidua reflexa, and 
decidua vera. The fundi of the uterine glands persist in the deep part of the 
decidua vera, and thus form a spongy layer, the part above this being the com- 
pact layer in the deep part of the placenta, e. g., near the uterine wall; we have 
also the fundi of the uterine gland persisting in the decidua serotina. When 
the placenta and membranes are expelled after birth, the line of separation 
takes place in the part of the membranes and placenta where the fundi of the 
glands persist. After labor is completely finished, the uterus is lined by the 
remains of the spongy layer of the decidua vera and serotina, e.g., is lined by 
a layer which contains the fundi of the uterine glands. The new mucous mem- 
brane is regenerated by the growth of the epithelium and connective-tissue 
is this part. The membranes expelled are made up of amnion, chorion, 
deciduae reflexae, and the compact layer of the decidua vera.] 
The uterine movements during labor proceed in a peristaltic manner from 
the Fallopian tube to the cervix, and occupy 20 to 30 seconds. In the curve 
registered by these movements there is usually a more steep ascent than descent. 
[Power in Ordinary Labor.—Sometimes the ovum is expelled whole, the membranes con- 
taining the liquor amnii -remaining unruptured. Poppel has pointed out that the force which 
ruptures the bag of membranes is sufficient to complete delivery, so that, as Matthews Duncan 
remarks, the strength of the membranes gives us a means of ascertaining the power of labor in 
the easiest class of natural labors. Matthews Duncan, from experiments on the pressure required 
to rupture the membranes, concludes that the great majority of labors are completed by a pro- 
pelling force not exceeding 40 lbs.] 
Polaillon estimates the pressure exerted by the uterus upon the foetus at each pain to be 154 
kilos. [338.8 lbs.], so that, according to this calculation, the uterus at each pain performs 8820 
kilogrammetres of work ($ 301). [This estimate is certainly far too high.] 
After-Birth.—After the foetus is expelled, the placenta remains behind; but it is soon 
expelled by the contractions of the uterus. During the contraction of the uterus to expel the 
placenta, a not inconsiderable amount of the placental blood is forced into the child ($ 40). [It 
is more probable that the child aspirates the blood from the foetus portion of the placenta. 
This can be seen in late ligature of the cord. The child may thus gain two ounces of blood.] 
After a time the placenta, the membranes, and the decidua—constituting the after-birth—are 
expelled. 
[Nerves of Uterus.—The uterus receives its motor fibres for both coats from the sympa- 
thetic chain, chiefly from about the 4th to the 6th lumbar ganglia. Most of the fibres run to the 
lower inferior mesenteric ganglia and are connected with nerve-cells there (Langley).] 
Influence of Nerves on the Uterus.—1. Stimulation of the hypogastric plexus causes con- 
traction of the uterus. The fibres arise from the spinal cord, from the last dorsal, and upper Sec. 453.] 
AFTER-BIRTH. 
1123 
three or four lumbar nerves, run into the sympathetic and then reach the hypogastric plexus 
(Frankenhauser). 2. Stimulation of the nervi erigentes, which are derived from the sacral 
plexus, causes movement (v. Bnsch and Hofmann). 3. Stimulation of the lumbar and sacral 
parts of the cord causes powerful movements (Spiegelberg). There is a centre for the act of 
parturition in the lumbar region of the cord (§ 362, 6). The uterus, like the intestine, probably 
contains independent or parenchymatous nerve-centres (Horner), which can be excited by sus- 
pension of the respiration, and by anaemia (by compressing the aorta, or rapid hemorrhage). 
Decrease of the bodily temperature diminishes, while an increase of the temperature increases the 
movement, which, however, ceases during high fever (Fromme). The experiments made by 
Rein upon bitches show that, if all the nerves going to the uterus be divided, practically all the 
functions connected with conception, pregnancy, and parturition can take place, even although 
the uterus is separated from all its cerebro-spinal connections. Hence, we must look to the 
presence of some automatic ganglia in the uterus itself. According to Dembo, there is a 
centre in the anterior wall of the vagina of the rabbit. According to Jastreboff, the vagina of 
the rabbit contracts rhythmically. Sclerotic acid greatly excites the uterine contractions (v. 
Swiecicki), so does ansemia (Kronecker and Jastreboff). 4. The uterus contracts reflexly on 
stimulating the central end of the sciatic nerve (v. Basch and Hofmann), the central end of the 
branchial plexus (Schlesinger), and the nipple (Scanzoni). 5. The uterus is supplied by vaso- 
motor nerves (hyipog&slric plexus), which come from the splanchnic; and also by vaso-dilalor 
fibres, the latter through the nervi erigentes. The vaso-jnotor nerves are affected reflexly by 
stimulation of the sciatic nerve (v. Busch and Hofmann). 
[In the rabbit the vagina and uterine cornua exhibit regular movements of a “peristaltic” 
nature. These exist apart from any extraneous stimulus, and are probably a vital property of 
the tissue. They can be demonstrated in animals a few weeks old, and have been recorded 
continuously for many hours. Frequently they are more vigorous six hours after than at the 
beginning, showing that they are not due to the irritation of the operation necessary to demon- 
strate them. 
Their rate and extent vary. In young animals they are frequent (1 to 4 per minute) but irreg- 
ular in character. In nulliparous adults they are less frequent and somewhat more regular. 
During pregnancy they increase greatly in extent, and their rate becomes 1 in 120 to 130 seconds. 
These characters are retained after pregnancy for many months at least. They are diminished or 
abolished by chloroform narcosis, are scarcely affected by ether. Water at ioo° to 120° F. produces 
a persistent contraction accompanied by blanching of the tissue. Similar effects are produced by 
dilute acetic acid (Milne Murray).] 
Lochia.—After birth the whole mucous membrane (decidua) is shed ; its 
inner surface, therefore, represents a large wounded surface, on which a new 
mucous membrane is developed. The discharge given off after birth constitutes 
the lochia. 
Involution of the Uterus.—After birth the thick muscular mass decreases 
in size, some of its fibres undergoing fatty degeneration. Within the lumen of 
the blood-vessels of the uterus itself there begins in the interna of these vessels a 
proliferation of the connective-tissue elements, whereby within a few months the 
blood-vessels so affected become completely occluded. The smooth muscular 
fibres of the middle coat of the arteries undergo fatty degeneration. The rela- 
tively large vascular spaces in the region of the placenta are filled by blood-clots, 
which are ultimately traversed by outgrowths of the connective-tissue of the 
vascular walls. 
Milk-Fever.—After birth there is a peculiar action on the vaso-motor sys- 
tem, constituting milk-fever, while at the 2d to 3d day there is a more copious 
supply of blood to the mammary gland for the secretion of milk (§ 231). 
[After birth the pulse becomes slow and remains so in a normal puerperium. 
The so-called milk-fever is not found in cases where strict cleanliness is observed 
during the labor and puerperium.] For the cause of the first respiration in the 
child, see p. 847. 
454. COMPARATIVE.—HISTORICAL.—A sketch of the development of man must 
necessarily have some reference to the general scheme of development in the Animal Kingdom. 
The question as to how the numerous forms of animal life at present existing on the globe have 
arisen has been answered in several ways. It has been asserted that each species has retained 
its characters unchanged from the beginning, so that we speak of the “ constancy of species.” 
This view, developed by Linnaeus, Cuvier, Agassiz, and others, is opposed by that supported by 1124 
COMPARATIVE DEVELOPMENT. 
[Sec. 454. 
Lamarck, 1809, or the doctrine of the “ Unity of the Animal Kingdom,” corresponding to the 
ancient view of Empedocles, that all species of animals were derived by variations from a few 
fundamental forms ; that at first there were only a few lower forms from which the numerous 
species were developed—a view supported by Geoffroy St. Hilaire and Goethe. After a long 
period this view was restated and elucidated in the most brilliant and most fruitful manner by 
Charles Darwin in his “ Origin of Species ” (1859) and other works. He attempted to show how 
modifications may be brought about by uniform and varying conditions acting for a long time. 
Amongst created beings each one struggles with its neighbor, so that there is a real “ struggle 
for existence.” Many qualities, such as vigor, rapidity, color, reproductive activity, etc., are 
hereditary, so that in this way by “ natural selection ” there may be a gradual improvement 
and therewith a gradual change of the species. In addition, organisms can, within certain limits, 
accommodate themselves to their surroundings or environment. Thus certain useful organs or 
parts may undergo development while inactive or useless parts may undergo retrogression, and 
form “ rudimentary organs.” This process of “ natural selection,” causing gradual changes in 
the form of organisms, finds its counterpart in “ artificial selection ” amongst plants and 
animals. Breeders of animals, for example, by selecting the proper crosses, can within a rela- 
tively short time produce very material alterations in the form and characters of the animals 
which they breed, the changes being more pronounced than many of those that separate well-de- 
fined species. But, just as with artificial selection, there is sometimes a sudden “ reversion ” to 
a former type, so in the development.of species by natural selection there is sometimes a condi- 
tion of atavism. Obviously, a wide distribution of one species in different climates must increase 
the liability to change, as very different conditions of environment come into play. Thus, the 
migration of organisms may gradually lead to a change of species. 
Biological Law.—Without discussing the development of different organisms, we may refer 
to the ‘•'•fundamental biological law ” of Haeckel, viz., “ that the ontogeny is a short repetition 
of the phylogeny,” [ontogeny being the history of the development of single beings, or of the 
individual from the ovum onwards, while phylogeny is the history of the development of a 
whole stock of organisms, from the lowest forms of the series upwards] (p. xxvii). When applied 
to man, this law asserts that the individual stages in the course of the development of the human 
embryo, e.g., its existence as a unicellular ovum, as a group of cells after complete cleavage, as a 
blastodermic vesicle, as an organism without a body-cavity, etc.; that these stages of development 
indicate or represent so many animal forms, through which the human species in the course of 
untold ages has been giadually evolved. The individual stages which the human race has passed 
in this process of evolution are rapidly rehearsed in its embryonic development. This conception 
has not passed without challenge. In any case, the comparison of the human development and 
its individual organs with the corresponding perfect organs of lower vertebrates is of great im- 
portance. Thus, a mammal during the development of its organs is originally possessed of the 
tubular heart, the branchial clefts, the undeveloped brain, the cartilaginous chorda dorsalis, 
and many arrangements of the vascular system, etc., which are permanent throughout the life of 
the lowest vertebrates. These incomplete stages are perfect in the ascending classes of verte- 
brates. Still, there are many difficulties to contend with in establishing both the evolution hypo- 
thesis of Darwin and the biological law of Haeckel. 
Historical.—Although the impetus to the study of the history of development has been most 
stimulated in recent times, the ancient philosophers held distinct but very varied views on the 
question of development. Passing over the views of Pythagoras (550 B.c.) and Anaxagoras (500 
b.c.), Empedocles (473 B.c.) taught that the embryo was nourished through the umbilicus ; while 
he named the chorion and amnion. Hippocrates observed incubated eggs from day to day, 
noticed that the allantois protruded through the umbilicus, and observed that the chick escaped 
from the egg on the 20th day. He taught that a 7 month’s foetus was viable, and explained the 
possibility of superfoetation from the horns of the uterus. The writings of Aristotle (born 384 
B.c.) contain many references to development, and many of them are already referred to in the 
text. He taught that the embryo receives its vascular supply through the umbilical vessels, and 
that the placenta sucked the blood from the vascular uterus like the rootlets of a tree absorbing 
moisture. He distinguished the polycotyledonary from the diffuse placenta; and he referred the 
former to animals without a complete row of teeth in both jaws. In the incubated egg of the 
chick he distinguished the blood-vessels of the umbilical vesicle, which carried food from the 
cavity of the latter and also the allantois. He also observed that the head of the chick lay on 
its right leg, and that the umbilical sac was ultimately absorbed into the body. The formation 
of double monsters he ascribed to the union of two germs or two embryos lying near each other. 
During generation the female produces the matter, the male the principle which gives it form and 
motion. There are also numerous references to reproduction in the lower animals. Erasistratus 
(304 B.c.) described the embryo as arising by new formations in the ovum—Epigenesis,—while 
his contemporary, Herophilus, found that the pregnant uterus was closed. He was aware of the 
glandular nature of the prostate, and named the vesiculse seminalis and the epididymis. Galen 
(131-203 A.D.) was acquainted with the existence of the foramen ovale, and the course of the Sec. 454.] 
HISTORICAL VIEWS ON DEVELOPMENT. 
blood in the foetus through it, and through the ductus arteriosus. He was also aware of the 
physiological relation between the breast and the blood-vessels of the uterus, and he described how 
the uterus contracted on pressure being applied to it. In the Talmud it is stated that an animal 
with its uterus extirpated may live, that the pubes separates during birth, and there is a record of 
a case of Caesarean section, the child being saved. Sylvius described the value of the foramen 
ovale ; Vesalius (1540) the ovarian follicles; Eustachius (f 1570) the ductus arteriosus (Botalli) 
and the branches of the umbilical vein to the liver. Arantius investigated the duct which bears 
his name, and he asserted that the umbilical arteries do not anastomose with the maternal vessels 
in the placenta. In Libavius (1597) it is stated that the child may cry in utero. Riolan (1618) 
was aware of the existence of the corpus Highmoriauum testis. Pavius (1657) investigated the 
position of the testes in the lumbar region of the foetus. Harvey (1633) stated the fundamental 
axiom, “ Omne vivum ex ovo.” Fabricius ab Aquapendente (1600) collected the materials 
known for the history of the development of the chick. Regner de Graaf described more care- 
fully the follicles which bear his name, and he found a mammalian ovum in the Fallopian tube. 
Swammerdam (f 1685) discovered metamorphosis, and he dissected a butterfly from the chrysalis 
before the Grand Duke of Tuscany. He described the cleavage of the frog’s egg. Malpighi 
(f 1694) gave a good description of the development of the chick with illustrations. Hartsoecker 
(1730) asserted that the spermatozoa pass into the ovum. The first half of the 18th century was 
occupied with a discussion as to whether the ovum or the sperm was the more important for the 
new formation (the Ovulists and Spermatists) ; and also as to whether the foetus was formed or 
developed within the ovum (Epigenesis), or if it merely increased in growth. The question of 
spontaneous generation has been frequently investigated since the time of Needham in 1745. 
New Epoch.—A new epoch began with Caspar Fried. Wolff (1759), who was the first to 
teach that the embryo was formed from layers, and that the tissues were composed of smaller 
parts (corresponding to the cells of the present period). He observed exactly the formation of 
the intestine. William Hunter (1775) described the membranes of the pregnant uterus. Soem- 
mering (1799) described the formation of the external human configuration, and Oken and 
Kieser that of the intestines. Oken and Goethe taught that the skull was composed of vertebrae. 
Tiedemann described the formation of the brain, and Meckel that of monsters. The basis for 
the study of the development of an animal from the layers of the embryo was laid by the re- 
searches of Pander (1817), Carl Ernst v. Baer (1828-1834), Remak, and many other observers; 
and Schwann was the first to trace the development of all the tissues from the ovum. [Schleiden 
enunciated the cell-theory with reference to the minute structure of vegetable tissues, while 
Schwann applied the theory to the structure of animal tissues. Amongst those whose names are 
most prominent in connection with the evolution of this theory are Martin Barry, von Mohl, Ley- 
dig, Remak, Goodsir, Virchow, Beale, Max Schultze, Briicke, and a host of recent observers.] APPENDIX A. 
General Bibliography. 
SYSTEMATIC WORKS AND TEXT-BOOKS.—A. v. Haller, Elementa physiologic 
corporis humani, 1757-1766, 8 vols., Auctarium, 1780.—F. Magendie, Precis 61ementaire de 
physiologie, 1816, 2d ed., 1825.—Johannes Muller, Handbuch der Physiologie des Menschen, 
2d ed., 1858-1861 (translated by W. Baly).—Donders, Phys. d. Mensch., pt. i. Leip., 1856.— 
C. Ludwig, Lehrbuch der Physiologie des Menschen, 2d ed., 1858 1861.—Otto Funke, Lehr- 
buch der Physiologie, 7th ed., by A. Griinhagen, 1884.—G. Valentin, Lehrbuch der Physiolo- 
gie, 1884 (translated by Brinton, 1853).—Moleschott, Phys. d. Nahrungsmittel, 2d ed., Giessen, 
1859.—F. A. Longet, Traite de physiologie, 2d ed., 1860-1861.—Joh. Ranke, Grundziige der 
Physiologie, 4th ed., 1881.—E. Briicke, Vorlesungen liber Physiologie, 3d ed., 1885.— L. Her- 
mann, Grundriss der Physiologie, 9th ed., 1888 (translated and enlarged by A. Gamgee, 2d 
English ed., 1878).—W. Wundt, Lehrbuch der Physiologie, 4th ed., 1878, and Grundziige d. 
physiol. Psycholog., 3d ed., Leip., 1887.—M. Foster, Text-book of Physiology, 5th ed.—H. 
Milne-Edwards, Legons sur la physiologie et l’anatomie comparee, 14 vols., 1857-1880.— 
G. Colin, Traite de physiologie comparee des animaux, Paris, 1871-1873.—Bernard, Leg. de 
Pathol, exper., Paris, 1872.—Marshall, Phys. (Diagrams and Text), 1875.—Strieker, Vorles. 
ii. allg. u. exp. Path., Wien, 1878.—Munk, Physiologie d. Menschen u. d. Saugethiere, Berlin, 
2d ed., 1888.—Schmidt-Mulheim, Grundriss d. spec. Physiologie d. Haussaugethiere, Leipzig, 
1879. —Vierordt, Grundriss d. Physiologie d. Menschen, 5th ed., Tiibingen, 1857.—Todd and 
Bowman’s Cyclopaedia of Anat. and Phys. —Hermann, Expt. Toxicologie, 1874.—W. 
Rutherford, A Text-book of Physiology, pt. i, Edinburgh, 1880.—W. B. Carpenter, Princip. 
of Phys., 8th ed., edited by Power, London, 1876.—J. Beclard, Traite elem. de Phys., Paris, 
1880. —Cohnheim, Vorlesungen ii. allgem. Pathologie, Berlin, 1880.—Huxley’s Elements, 
1885.—H. Beaunis, Nouveaux elements de Physiologie humaine, 3d ed., 1888.—Flint, Text- 
book, New York, 1876; and Phys. of Man, 1866-1873.—Kirkes, Handbook of Physiology, 
12th ed., 1888.—Dalton, Text-book, 1882.—J. G. M’Kendrick, Text-book of Physiology, 
Glasgow, 1890.—Samuel, Handb. d. allg. Path., Stutt., 1879.—The works of Herbert Spen- 
cer and G. H. Lewes.—E. D. Mapother, Manual of Physiology, 3d ed., rewritten by J. F. 
Knott, Dublin, 1882.—A. Fick, Compendium d. Phys., 1891.—Steiner, Physiologie, 4th ed.? 
Leipzig, 1888.—Nuel and Fredericq, Elem. de Phys., 2d ed., Gand, 1889.—Preyer, Ele- 
mente der allgemeinen Physiologie, 1883.—T. Lauder-Brunton, Pharmacology, Therapeutics, 
and Materia Medica, 1887.—H. Power, Elements of Physiol., London, 1884.—Wundt, Phys. 
med., 1878.—Daniell, Text-book of the Principles of Physics, 1884.—Fick, Med. Physik, 2d 
ed., 1884.—M’Gregor Robertson, Physiological Physics, London, 1885.— Draper, Med. 
Physics, 1885.—Yeo, Manual of Physiology, 2d ed., London, 1887.—L. v. Thanhoffer, 
Grundziige d. vergl. Physiologie u. Histologie, Stuttgart, 1885.—Ziegler, Text-book of Path. 
Anat. (trans. by D. Macalister), 1883-1884.—P. H. Pye-Smith, Syllabus of Lectures on 
Physiology, London, 1885.—Chapman, Treatise on Human Phys., Philad., 1887.—Klein, 
Micro-organisms and Disease, 1884.— Magnin and Steinberg, Bacteria, 1884.—Woodhead 
and Hare, Mycology, 1885.—Crookshank, Bacteriology, 1886.—Fluege, Micro-organisms 
(Eng. trans.), 1890.—Davis, Text book of Biol., London, 1888.—Vines, Physiology of Plants. 
—Albertoni and Stefani, Manuale di Fisiol. umana, 1888.—Viault and Joylet, Traite de 
Physiologie, 1889. — Munk, Physiologie, 1890.—Ellenberger, Lehrb. d. vergleich. Histol. u. 
Physiol, d. Hausthiere, Berlin, 1887.—Landois and Stirling, Text book, 4th ed., 1891. 
YEARLY REPORTS, BIBLIOGRAPHICAL WORKS.—1834-1837 : “ Jahresberichte 
iiber die Fortschritte der Physiologie,” by Joh. Muller, in his Archiv.—1838-1846 : by Th. L. 
Bischoff, ebenda.—1836-1843: in “Repertorium fiir Anatomie und Physiologie,” by G. GENERAL BIBLIOGRAPHY. 
1127 
Valentin, 8 vols.—1856-1871 : in “ Zeitschrift fiir rationelle Medicin,” by G. Meissner, and 
continued since 1872 under the title—“ Jahresberichte iiber die Fortschritte der Anatomie und 
Physiologie,” by F. Hofmann, and G. Schwalbe, Leipzig.—1841-1865: Jahresbericht iiber 
die Fortschritte der gesammten Medicin, by Canstatt, continued by Virchow and Hirsch.— 
1822-1849: Froriep’s Notizen 101 vols. (References and Bibliography).—Centralblatt fur die 
medicinischen Wissenschaften, Berlin; yearly since 1863.—Biologisches Centralblatt, Erlangen, 
since 1881.—1817-1818: Isis, by Oken.—Catalogue of Scientific Papers compiled and pub- 
lished by the Royal Society of London, 1800-1873, 8 vols.—Engelmann, 1700-1846. Biblio- 
theca historico-naturalis (Titles of Books on Comparative Physiology).—Jahrbuch der gesammten 
Medicin, by Schmidt, since 1826.—Bibliotheca anatomica qua scnpta ad anatomen et physio- 
logiam facientia a rerum initus recensentur auctore Alberto von Haller, 2 vols. (important for 
the older literature up to 1776).-—Yearly Reports on Physiology, in Journal of Anat. and Phys., 
by Rutherford, Gamgee, and Stirling; also Monthly Reports in London Med. Record, since 
its commencement in 1873.—Index medicus.—Neurologisches Centralblatt.—Med. Bibliographic 
by A. Wurzburg, since 1886.—Fortschritt d. Med. 
HISTORICAL.—Kurt Sprengel, Versuch einer pragmatischen Geschichte der Arzneykunde, 
3d ed., 1821.—W. Hamilton, Hist, of Med. Surg. and Anat., 1831.—Bostock’s Syst. of 
Phys., 3d ed., 1836.—J. C. Poggendorf, Geschichte der exacten Wissenschaft, 1863.—J. Good- 
sir, Titles of Papers on Anat. and Phys., 1849-1852, Edin., 1853.—Meyer, Gesch. d. Botanik, 
Konigs., 1854-1857.—H. Haeser, Lehrbuch der Geschichte der Medicin, Jena, 1875.—Julius 
Sachs, Geschichte der Botanik seit 16. Jahrb. bis i860; 1875.—Bouchut, Hist, de la med., 
Paris, 1873.— Fournie, Applic. de la scien. a la med., Paris, 1873.—Willis’s William Harvey, 
1878; and his Servetus and Calvin, London, 1877. Biographisches Lexikon, Vienna, 1884.— 
Burdon-Sanderson, Biological Memoirs, vols. 1, II. 
ENCYCLOPEDIAS.—R. Wagner, Handworterbuch der Physiologie, 4 vols., 1842-1853— 
R. B. Todd, The Cyclopaedia of Anatomy and Physiology, 1836-1852.—Pierer and N. 
Choulant, Anatomisch-physiologisches Realworterbuch, 8 vols., 1816-1829.—L. Hermann, 
Handbuch der Physiologie, 1879-1884.—Real-Encyclop. d. gesam. Med., edited by Eulenberg. 
Wien, 1888. 
PRACTICAL WORK IN THE LABORATORY.—R. Gscheidlen, Physiologische 
Methodik, 1876 (not yet completed).—E. Cyon, Methodik der physiologischen Experimente u. 
Vivisektionen, with Atlas, 1876 (only one part issued).—Ott, The Actions of Medicines, Phil., 
1878.—Claude Bernard and Huette, Precis iconographique de mddecine operatoire et d’anat- 
omie chirurgicale, with 113 plates, 1873 I also Leqons de physiologie operatoire (edited by Duval), 
Paris, 1879.—Sanderson, Foster, Klein, and Brunton, Handbook for the Physiological 
Laboratory (Text and Atlas). The French edition contains additional matter—Rutherford, 
Outlines of Pract. Hist., 1876.—Meade-Smith, Trans, of Hermann’s Toxicol.—J. Burdon- 
Sanderson, Practical Exercises in Physiology, London, 1882.—Foster and Langley, Pract. 
Phys., London.—B. Stewart and Gee, Pract. Physics.—Vierordt, Anat. Physiol, u. Physik. 
Daten u. Tabellen, Jena, 1888.—Muller-Pouillet, Lehrb. d. Physik, 8th ed.. Braunschweig.— 
Wiillner, Lehrb. d. exp. Physik.—Livon, Manuel de Vivisect., Paris, 1882.—Harris and 
Power, Manual for the Phys. Lab., 5th ed., 1S88.—Straus-Durckheim, Anat. descrip, comp, 
du. chat., Paris, 1845.—W. Krause, Die Anatomie des Kaninchens, Leipzig, 2d ed., 1883.— 
A. Ecker, Die Anatomie des Frosches, 1864-1882, 2d ed., pt. i., 1888.—Biolog. Memoirs, 
edited by Burdon-Sanderson.—Stirling, Outlines of Pract. Physiol., 2d ed., Lond., 1890. 
SPECIAL LABORATORY REPORTS.—Ludwig and his pupils, Arbeiten aus der physio- 
logischen Anstalt zu Leipzig, since 1866.—Burdon-Sanderson and Schafer, Collected pa- 
pers from the Physiological Laboratory of University College, London, 1876-1885.—Gamgee, 
Studies from the Physiological Laboratory of Owens College, Manchester, 1877-78, Traube, 
Beitr. z. Path. u. Phys., Berlin, 1871.—J. Czermak, Gesammelte Schriften, 1879.—Marey, 
Physiologie experimentale, Travaux du laboratoire, Paris, 1875.—L. Ranvier, Laboratoire 
d’histologie du College de France, Paris, since 1875.—Loven, Physiol. Mittheil., Stockholm, 
1882-84.—W. Kiihne, Untersuchungen des physiologischen Instituts der Universitat Heidel- 
berg, since 1887.—R. Heidenhain, Studien des physiologischen Instituts zu Breslau, 1861-68. 
—Strieker, Studien aus dem Institute fiir experimentelie Pathologie, Vienna.—John Reid, 
Physiological and Anatomical Researches, Edinburgh, 1848. Rollett’s Untersuch. a. d. Inst, 
zu Gratz, since 1870.-—Schenk, Mitth. a. d. embryol. Inst. z. Wien, 1877-.—Preyer, Sammlung 
phys. Abhandl., Jena, 1877-.—Von Wittich, Mitth. a. d. Konigsb. Phys. Lab., 1878.— 
Rossbachj Pharmacol. Unters. Wiirzb., 1873-. —Fick, Arb. a. d. Wiirzburger Hochschule, 
Wurzburg, 1872.—Hoppe-Seyler, Med.-chem. Unters., Travaux de 
Lab. de Phys. de la Faculte de Med., Paris, 1885. Marshall, Studies from the Biol. Lab. of GENERAL BIBLIOGRAPHY. 
Owens College, pts. i, ii, 1886-1890.—Fredericq, Travaux de Physiologie, 1885-1890.— 
Tigerstedt, Mitth. v. d. phys. Lab. in Stockholm, 1888.—Stirling, Studies from the Physio- 
logical Lab. of Owens College, 1891. 
JOURNALS, PERIODICALS.—Archiv fur die Physiologie, by J. C. Reil and Autenrieth, 
12 vols., Halle, 1796-1815. Continued as—Deutsches Archiv fiir die Physiologie, by J. F. 
Meckel, 8 vols., Halle, 1815-1823. Continued as—Archiv fur Anatomie and Physiologie, by 
J. F. Meckel, 6 vols., Leipzig, 1826-1832. Continued as—Archiv fiir Anatomie und wissen- 
schaftliche Medicin, by Johannes Muller, 25 vols., Berlin, 1834—1858. Continued under the 
same title by—C. B. Reichert and E. du Bois-Reymond, 1859-1876. When it was divided 
into—Zeitschrift fiir Anatomie und Entwickelungsgeschichte, by W. His and Braune, and 
Archiv fiir Physiologie, by E. du Bois-Reymond, until 1877. Is continued as—Archiv fiir 
Anatomie und Physiologie by W. His, W. Braune, and E. du Bois-Reymond.—Archiv 
fiir die gesammte Physiologie des Menschen und der Thiere, by E. F. W. Pfliiger, Bonn., 
since 1868.—Zeitschrift fiir Biologie, edited from 1865 by Buhl, Pettenkofer, Voit, and Radl- 
kofer; from 1875 by the first three, and since 1880 by Pettenkofer and Voit, presently by 
Voit and Kiihne.—Journal de Physiologie experimentale et pathologique, by F. Magendie, 
11 vols., Paris, 1821—1831.—Zeitschrift fiir die organische Physik, by C. F. Heusinger, 4 
vols., Eisenach, 1827-1828.—Zeitschrift fiir Physiologie, by F. Tiedemann and Treviranus, 
5 vols., 1824-1833.—Journal de l’anatomie et de la physiologie normales et pathologiques de 
l’homme et des animaux, by Ch. Robin and Pouchet, since 1864.—Archives de physiologie 
normale et pathologique, by Brown-Sequard, Charcot, Vulpian, Paris, since 1868.—Journal 
of Anatomy and Physiology, edited by Humphry, Turner, and M’Kendrick, since 1867.— 
Journal of Physiology, edited by M. Foster, since 1878.—Archives Italiennes de Biologie, by 
C. Emery and A. Mosso, since 1881—Annales des sciences naturelles, Paris, since 1824.— 
Archives de Zoologie experimentale et generale, by Lacaze-Duthiers, Paris, since 1872.— 
Archives de Biologie, by Ed. van Beneden and Ch. van Bambeke, since 1880.—Physiolog. 
Centralblatt, by Exner and Gad, since 1887.—Zeitschrift fiir wissenschaftliche Zoologie, by 
C. T. von Siebold and A. von Kolliker, Leipzig, since 1849.—Archiv fiir pathologische An- 
atomie und Physiologie und fiir klinische Medicin, by R. Virchow, Berlin, since 1847.—Zeit. 
f. wissensch. Mikroscop., Behrens, Braunschweig.—Archiv fiir Naturgeschichte, by Wieg- 
mann ; continued by Erichsen and Troschel, Berlin, since 1835.—Untersuchungen zur Natur- 
lehre des Menschen und der Thiere, by Jac. Moleschott, since 1857.—Zeitschrift fiir rationelle 
Medicin, Henle, Pfeufer, and Meissner.—Sitzungsberichte der Akademie der Wissenschaften 
(Math. Nat.-Wiss. Classe), Vienna.—Philosophical Transactions, London.—Proceedings of the 
Royal Society, London.—Transactions of the Royal Society, Edinburgh.—Proceedings of the 
Royal Society, Edinburgh.—Quarterly Microscopical Journal, London.—Monthly Microscopical 
Journal, London.—Journal of the Royal Microscopical Society, London.—Comptes rendus, 
Paris —Anatomisches Anzeiger.—Index Medicus.—Cohn, Beitrage,zur Physiologie der Pflanzen, 
Breslau, 1872.—The Philosophical Magazine, Edinburgh, London, and Cambridge.—Boston 
Medical and Surgical Journal.—Verhandlungen der physikal.-medicinischen Gesellschaft zu 
Wurzburg.—Archives of Medicine, edited by L. Beale, London, 1856.—Annals and Magazine 
of Natural History.—Annales (Memoires) Archives du Museum d’histoire naturelle, Paris.— 
Jenaische Zeitschrift fur Naturwissenschaft.—Memoires de l’Academie des Sciences de l’lnstitut 
de France, Paris.—Morphologisches Jahrbuch, by C. Gegenbaur, since 1876.—Nova Acta 
Academiae Leopoldino-Carolinse.—Zoologischer Anzeiger, by V. Carus, since 1878.—Abhand- 
lungen and Monatsberichte der k. preussischen Akademie der Wissenschaft zu Berlin.—Archiv 
fiir experimentelle Pathologie und Pharmakologie, by Naunyn and Schreiber, Leipzig, since 
1873.—Deutsches Archiv fiir klin. Medicin, by v. Ziemssen and Zenker, Leipzig.—Journal 
de Pharmacie et de Chimie, Paris.—Archiv fiir Psychiatrie und Nervenkrankheiten, by Gudden 
and others, Berlin, since 1868. Archiv fiir wissenschaftliche und praktische Thierheilkunde, by 
Roloff, Berlin, 1874.—Archives generates de medeclne, Paris.—Brain, since 1879, edited by 
de Watteville.—Archives de Neurologic, by Charcot, Paris, 1875.—Zeit. f. Hygiene, by Koch 
and Fliigge, Scandanav. Archiv.—The various Medical Journals, including the Lancet and 
British Medical Journal, Edinburgh, Medical Journal, London Medical Record, New York Med. 
Record, Practitioner, Medical Chronicle.—Arch, for Otology, N. Y.—Arch, for Ophthal., N. Y. 
—Internat. Jour, of Med. Sciences, Edin.—Revue de Med., Paris.—Zeit. f. Klin. Med., Berlin. 
—Intern. Monatssch. f. Anat. u. Physiol.—Asclepiad.—Nature. 
HISTOLOGY.—Henle, Handbuch der systematischen Anatomie des Menschen, 3d ed., 
1866-1883.—Rutherford, Outlines of Pract. Histol., 1876.—W. Krause, Allgemeine und 
Mikroskopische Anatomie, Hanover, 1876.—F. Leydig, I.ehrbuch der Histologie der Menschen 
und der Thiere, Hamm, 1857; and his Untersuchungen, 1883; and his Zelle u. Gewebe, Bonn, 
1885.—V. Mihalkovics, General Anatomy (Hungarian), 1881.—L. Ranvier, Traite technique 
d’histologie, 2d ed., Paris.—G. Schwalbe, Lehrbuch der Neurologie, Erlangen, 1881 ; Lehrb. d. 
Anat. d. Stnnesorgane.—S. Strieker, Handbook of Histology (translated by the New Sydenham GENERAL BIBLIOGRAPHY. 
Society), 1871-1873.—Archiv fiir mikroskopische Anatomie, Bonn; edited formerly by Max 
Schultze, and presently by Waldeyer and La Valette.— Quarterly Microscopical Journal 
London.—Monthly Microscopical Journal, London.—Journal of the Royal Microscopical Society, 
London.—Schwann, Mikrosk. Untersuch., 1838 (translated by the Sydenham Society, 1847). 
W. Kiihne, Das Protoplasma, Leipzig, 1864.—Max Schultze, Das Protoplasma, Leipzig, 
1863.—R. Virchow, Die Cellular Pathologie (translated by Chance), i860.—L. Beale, The 
Structure of the Elementary Tissues, London, 1881.—A. Kolliker, a Manual of Human Micro- 
scopic Anatomy, London, i860; Lehrb. d. Histologie, 6th ed. pt. i, 1889; and his leones 
Histolog., Leip., 1864.—J. Goodsir, Anatomical and Pathological Observations, edited by W. 
Turner, Edinburgh.—Quain’s Anatomy, 10th ed., edited by Schafer and Thane, London, 
1891.—Rindfleisch, A Manual of Pathological Anatomy (translated by R. Baxter), London, 
1873.—C. Toldt, Lehrbuch der Gewebelehre, Stuttgart, 3d ed., 1888—E. Klein and E. Noble- 
Smith, Atlas of Histology, London, 1872.—H .Frey, Handbuch der Histologie und Histochemie 
des Menschen, Leipzig, 1876, Grundziige, 1885, and das Mikroskop., 8th ed., 1886.—Fol, Lehr. d. 
vergleich. mikros. Anatomie, Leip., 1885.—Behrens, Tabellen z. Gebrauch b. mik. Arbeiten, 
Braunschweig, 1887.—Fearnley, Pract. Histol., 1887.—Brass, Kurzes Lehrb. d. Histol., 
Leip., 1888.—Beale, How to Work with the Micros., Lond., 1880.—W. Stirling, Histological 
Memoranda, Aberdeen, 1880.—E. A. Schafer, Practical Histol., 1877; and Essentials of Histol. 
1887. —W. Stirling, Text-book of Practical Histology, London, 1881.—Heitzmann, Microsc. 
Morphology, 1882.—Purser, Man. of Hist., Dublin.—E. Klein, Elements of Hist., London, 
1883.—W. Flemming, Zellsubst. u. Zelltheil., Leipzig, 1882.— Cadiat, Traite d’anat. gen., 
Paris, 1879.—Bizzozero, Hand. d. klin. Mikroskop., Erlang., 2d ed., 1888.—Carnoy, Gilson 
and Denys, Biol. Cellul., Louvain, 1884-88.—Friedlander, Mik. Technik., 3d ed., Berlin, 
1888. —Gierke, Farberei z. mik. Zwecken., Braun., 1885.—Frommann, Unters. u. thier. u. 
pflanz. Zellen, Jena, 1884.—Wiedersheim, Lehrb. d. vergl. Anat., Jena, 1888.—S. L. Schenk, 
Grundriss der Histologie d. Menschen, Vienna, 1885.—Orth, Cursus d. norm. Histol., 4th ed., 
1886. —S. Mayer, Histolog. Taschenbuch. Prag., 1887.—Stohr, Lehrb. d. Histol., 4th ed., 
Jena, 1891.—Lee and Henneguy, Traite de metli. de l’anat., Paris, 1888.—Renaut, Histologie, 
1890. —Bohm and Oppel, Taschenbuch d. Mikrokop., Technik, Miinchen, 1890.—W. Stirling, 
Outlines of Practical Histology, 1890.—Fusari and Monti, Compendio di Istologia, Torino, 
1891. 
PHYSIOLOGICAL CHEMISTRY.—Hoppe-Seyler, Physiologische Chemie, Berlin, 1877— 
1879.—Lehmann, Lehrb. d. phys. Chem. 3d ed., Leipzig, 1853; and Handbuch, 1859.—J. 
Konig, Chemie der menschlichen Nahrung und Genussmittel, 2d ed., Berlin, 1883.—Leo. 
Liebermann, Grundziige der Chemie des Menschen, Stuttgart, 1880.—Robin and Verdeil, 
Traite de chim. anat. et phys. (with Atlas), Paris, 1853.—J. Moleschott, Physiologie der 
Nahrungsmittel, 2d ed., Giessen, 1859.—E. Smith, Foods, 1873.—A. Wynter Blyth, Foods, 
1887. —Gorup-Besanez, Anleitung zur Zoo-chemischen Analyse, 1871.—Gautier, Chimie 
appliqu6 a la Physiologie, 1874.—Lehmann’s Phys. Chem. (translated by Cavendish Soc.., 
1851-1854), with Atlas of O. Funke’s plates.—Kingzett, Animal Chem., 1878.—Thudichum, 
Ann. of Chem. Med., 1879.—A. Gamgee, Physiological Chemistry of the Animal Body, vol. 
i, 1880.—Hoppe-Seyler, Medicinische-Chemische Untersuchungen, Berlin.—Zeitschrift fiir 
physiologische Chemie, by Hoppe-Seyler, Strassburg, since 1877.—Watt’s Dictionary of 
Chemistry, second supplement, London, 1875.—Ralfe, Clinical Chemistry, London, 1880; and 
Clinical Chem., 1883.—Wurtz, Traite de chim. biol., Paris, 1880.—T. C. Charles, Physiological 
and Pathological Chemistry, London, 1884.—Parkes’ Hygiene, 7th ed.—Fliigge, Lehrb. d. 
hygien. Untersuchung., Leip., 1881.—Maly’s Jahresb. ii. Thierchemie since 1870.—Landolt, 
Das opt. Drehungsvermog. org. Subst., Braun., 1879.—Articles in Hermann’s Handbuch d. 
Physiologie, 1879-1884, and the various Text-Books on Organic Chemistry.—Roscoe and 
Schorlemmer, (Organic) Chem., 1884.—Nowak, Lehrbuch d. Hygiene, Wien.—Beilstein, 
Handb. d. org. Chem., Hamb. and Leip., 2d ed., 1885.—Ladenburg, Handb. d. Chemie, 
Breslau, 1883.—Rosenthal, Vorles. ii. offent. u. priv. Gesundheitspflege, Erlangen, 1887.— 
Kossel, Leitfaden f. med.-chem. Curse, 2d ed., Berlin, 1888.—Bunge, Phys. and Path. Chem. 
trans. by Woolbridge, 1890.—Rohmann, Anleitung z. chem. Arbeit. Berlin, 1890.—V. Jakscht 
Clinical Diagnosis, trans. by Cagnev, 1890.—Halliburton, Chemical Physiology and Pathology, 
1891.—Hammarsten, Lehrb. d. Physiol. Chem., 2d ed., Wiesbaden, 1891. COMPARISON OF METRICAL WITH COMMON MEASURES. 
1130 
COMPARISON OF THE METRICAL WITH THE COMMON MEASURES. 
By Dr. Warren De La Rue. 
APPENDIX B. 
MEASURES OF LENGTH. 
In English Inches. 
In English Feet 
=12 Inches. 
In English Yards 
=3 Feet. 
Millimetre 
0.03937 
0.0032809 
0.0010936 
Centimetre 
0-39371 
0.0328090 
0.0109363 
Decimetre 
3 93708 
0.3280899 
0-1093633 
Metre 
39-37079 
3.2808992 
1.0936331 
Decametre 
393.70790 
32.8089920 
10.9363310 
Hectometre 
3937 07900 
328.0899200 
109 3633too 
Kilometre 
39379-79000 
3280.8992000 
1093.6331000 
Myriometre 
3937°7 90000 
32808.9920000 
10936.3310000 
i Inch = 2.539954 Centimetres. | 
1 Foot = 3.0479449 
Decimetres. | 
i Yard = 0.91438348 
MEASURES OF CAPACITY. 
In Cubic inches. 
In Cubic Feet=i,728 
Cubic inches. 
In Pints=34.65923 
Cubic Inches. 
Millilitre or cubic centimetre .... 
0.061027 
0.0000353 
0.001761 
Centilitre or io cubic centimetres . . 
O.6IO27I 
0.0003532 
O.OI7608 
Decilitre or ioo cubic centimetres . 
6.102705 
o-ooSSS1? 
0.176077 
Litre or cubic decimetre 
61.027052 
0.0353166 
1.760773 
1 lecalitre or centistere 
610.270515 
o.353t658 
17.607734 
Hectolitre or decistere 
6102.705152 
3-53i658i 
176.077341 
Kilolitre or stere, or cubic metre . . 
61027.051519 
35.3165807 
1760.773414 
Myriolitre or decastere 
610270.515194 
353-^58074 
17607.734140 
i Cubic Inch = 16.3861759 Cubic Centimetres. | 1 Cubic Foot = 28.3153119 Cubic Decimetres. 
The unit of volume is 1 Cubic Centimetre. 
MEASURES OF WEIGHT. 
In English Grains. 
In Troy Ounces 
=480 Grains. 
In Avoirdupois lbs. 
=7,000 Grains. 
Milligramme . 
* 
°-OI5432 
0.000032 
0.0000022 
Centigramme 
0.154323 
0.000322 
0.0000220 
Decigramme 
I.543235 
0.003215 
0.0002205 
Gramme 
I5.432349 
0.032151 
0.0022046 
Decagramme 
154.323488 
0 321507 
0.0220462 
Hectogramme 
1543.234880 
3215073 
0.2204621 
Kilogramme 
15432.348800 
32.150727 
2 2046213 
Myriogramme 
154323.488000 
321.5O7267 
22.0462126 
The unit op mass in the metrical system is 1 Gramme, which is the mass or weight of 1 Cubic Centimetre 
(1 c.c.) of water at 40 C., i.e., at its temperature of maximum density. 
CORRESPONDING DEGREES IN THE FAHRENHEIT AND CENTIGRADE SCALES. 
Wolli5olfl4P<,llulPo 1 
: i ::::::::::::::::: : 
f 
00 Or OJ M VO Cj to 0 COUl w nb O'ONli M Q " 
is:::::::!:::::::::: n 
1 
to O oooi oj Hbvj i to b ooui u> w vb 4- to b 
WoV. 8o% Vo Vo Vo °o Vo °o ? 
!| • : : r 5 : :' 
biooo»-t-'J'b«oju>oobM-Wvi'b"Ovij. % 
ON tO 004- O b\ to *004- O b io *004- O b> to 004- o 
: : 
Os tO 004- O O* tO *004- O ON *10 004- O b> tO *004- O ? 
II 1 1 M M 1 1 „ p 
°o°o <o**o Mo °o °o <o4o Ko *0 °o*0 *o"fb °o *0 s 
: i : ' 
O 4- to 004- O ON to *004- O On to 004- O bto CO 4- o pt 
To turn C° into F°, multiply by q, divide by 5, and add 320. 
To turn F° into C°, deduct 32, multiply by 5, and divide by 9, INDEX. 
Abdominal muscles in respi- 
ration, 208 
Abdominal reflex, 812 
Abducens, 754 
Aberration, chromatic, 962 
“ spherical, 962 
Abiogenesis, 1059 
Absolute blindness, 896 
Absorption by fluids, 46 
“ by solids, 46 
“ influence of nervous 
system, 379 
“ organs of, 362 
Absorption of— 
carbohydrates, 374 
coloring matter, 376 
digested food, 370 
effusions, 399 
fats, 376 
fat soaps, 375 
fatty acids, 378 
forces of, 370 
grape-sugar, 374 
inorganic substances, 372 
nutrient enemata, 379 
oxygen by blood, 226 
particles, 376 
peptones, 374 
solutions, 372 
sugars, 374 
unchanged proteids, 375 
Absorption jaundice, 341 
“ spectra, 25 
Accelerans nerve, 851 
“ in frog, 854 
Accommodation of eye, 953 
“ defective, 960 
“ force of, 960 
“ for tempera- 
ture, 422 
“ line of, 957 
“ nerves of, 955 
“ phosphene, 971 
“ range of, 958 
“ range to force 
of, 961 
“ spot, 970 
“ time for, 957 
Accord, 1025 
Acetic acid, 485 
Aceton, 517, 530 
Acetylene, 30 
Achromatin, 1087 
Achromatopsy, 986 
Achroodextrin, 261 
Acid-albumin, 477 
Acid-haematin, 30 
Acids, free, 473 
Acoustic— 
“ formula, 759 
“ hyperalgia, 759 
“ “ nerve, 759 
“ tetanus, 698 
Acquired movements, 893, 903 
Acrylic acid series, 485 
Action currents, 703, 715 
“ from heart, 707 
“ of muscle and nerve, 705 
Active insufficiency, 641 
Acute decubitus, 735 
Adamkiewicz’s reaction, 475 
Addison’s disease, 181, 735 
Adelomorphous cells, 292 
Adenin, 489 
Adenoid tissue, 389 
Adequate stimuli, 931 
Adipocere, 462 
Adipose tissue, 460 
Adventitia, 109 
214 
Aerobes, 349 
Airoplethysmograph, 200 
/Esthesiometer, 1049 
.Esthesodic substance, 815 
Afferent nerves, 736 
After-birth, 1122 
After-images, 988 
After-pressure, 1053 
After-sensation, 932 
After-taste, 1042 
Ageusia, 1043 
Agminated glands, 369 
Agoraphobia, 762 
Agrammatism, 906 
Agraphia, 906 
Ague cake, 177 
Air, atmospheric, 219 
“ collection of, 219 
“ composition of, 220 
“ expired, 219, 220 
“ impurities in, 236 
Air-cells of lung, 189 
Air-sacs, 242 
Air-vesicles, exchange of gases 
in, 225 
Albumin in urine, 521 
“ tests for, 522 
Albuminates, 477 
Albuminimeter, 523 
Albuminoids, 480 
Albumin of egg, 45, 476 
Albuminous bodies, 473 
Albumins, 476 
Albuminuria, 521 
Albumoses, 302, 303 
“ on blood, 37 
Alcohol, 447, 448 
“ action of, in digestion, 
357 
“ on temperature, 427 
Alcoholic drinks, 447 
Alcohols, 487 
Alcool au tiers, 10 
Aleurone grains, 479 
Alexia, 908 
Alimentary principles, 243 
Alkali-albumin, 477 
Alkali-hsematin, 30 
Alkaline fermentation, 520 
Alkaloids, 447 
Allantoin, 489, 514 
Allantois, 1096 
Allochiria, 1055 
Allorhythmia, 127 
Alloxan, 510 
Almen’s test, 526 
Alteration theory, 714 
Alternate hemiplegia, 830 
“ paralysis, 830, 917 
Alternation of generations, 1060 
Alveoli of lung, 189 
Alvergniat’s gas-pump, 49 
Amaurosis, 741 
Amblyopia, 741 
American crow-bar case, 867 
Amides, 489 
Amido-acids, 489 
Amido-acetic acid, 489 
Amido-caproic acid, 313 
Amimia, 906 
Amines, 489 
Amitosis, 1087 
Ammonia derivatives, 489 
Ammoniaemia, 548 
Amnesia, 906 
Amnesic aphasia, 906 
Amnion, 1096 
Amniota, 1096 
Amniotic fluid, 1096 
“ sac, 1096 
Amoeboid movements, 16, 17 
Ampere, 688 1132 
INDEX. 
Ampere’s rule, 689 
Amphiarthroses, 638 
Ampho-peptone, 302 
Amphoric sounds, 213 
Ampullae of semicircular ca- 
nals, 1022 
Amygdalin, 399 
Amyloid substance, 479 
Amylopsin, 312 
Amylum, 488 
Anabiosis, 1059 
Anacrotism, 129 
Anaemia, 57, 58 
“ metabolism in, 58 
Anaerobes, 349 
Anaesthesia dolorosa, 1056 
Anaesthetic leprosy, 735 
Anaesthetics, 1057 
Anabolic nerves, 736 
Anabolism, 429 
Anakusis, 760 
Analgesia, 818 
Analgia, 1057 
Anamnia, 1096 
Anapnograph, 200 
Anarthria, 906 
Anasarca, 399 
Andral and Gavarret’s appara- 
tus, 218 
Anelectrotonus, 716 
Aneurism, 134, 135 
Angiograph, 118 
Angiometer, 128 
Angioneuroses, 863 
Angle of convergence, 1002 
Angular gyrus, 896 
Anidrosis, 570 
Animals, characters of, xlii 
Animal— 
“ heat, 402 
“ magnetism, 873 
“ starch, 325 
Anions, 690 
Anisotropous substance, 579 
Ankle clonus, 813 
Anode, 690 
Anosmia, 738 
Antagonistic muscles, 641 
Anlhracometer, 217 
Anthracosis, 193 
Anti-albumin, 303 
Antiar, 100 
Anti-emetics, 283 
Antihydrotics, 568 
Antipeptone, 302, 478 
Antiperistalsis, 284 
Antipyretics, 424 
Antisialics, 257 
Aortic valves, 63 
“ insufficiency of, 
129 
Aperistalsis, 287 
Apex-beat, 71 
Apex-preparation, 97 
Aphakia, 944 
Aphasia, 906, 907 
Aphonia, 663 
Apnoea, 839 
Appreciable distance, smallest, 
1051 
Appunn’s apparatus, 1029 
Apselaphasia, 1056 
Aphthongia, 664 
Aqueous humor, 945 
Arachnoid mater, 925 
Archiblastic cells, 1092 
Area opaca, 1085 
“ pellucida, 1070, 1085 
“ vasculosa, 1086 
Argyll Robertson pupil, 965 
Arhythmia cordis, 66 
Aristotle’s experiment, 1051 
Aromatic acids, 486 
“ ethereal compounds, 
5 r9 
“ oxyacids, 489 
Arrector pili muscle, 562 
Arrest of heart’s action, 147 
Arterial blood, 54 
Arterial tension, 124 
Arteries, 108 
“ blood-pressure in, 143 
“ central, 879 
“ development of, 1110 
“ division of, 114 
“ emptiness of, 855 
ligature of, 114 
“ physical properties of, 
”3 
“ rhythmical contraction 
of, 860 
“ sounds in, 162 
“ structure of, 108 
“ termination in veins, 
159 
Arteriogram, 119 
Arthrodial joints, 638 
Articular cartilage, 637 
Articulation nerve-corpuscles, 
1046 
“ positions, 662 
Artificial cold-blooded condi- 
tion, 427 
“ eye, 952, 973 
“ digestion, 358 
“ gastric digestion, 304 
“ gastric juice, 301 
“ katalepsy, 873 
“ respiration, 235 
“ Marshall Hall’s me- 
thod, 235 
“ Sylvester’s method, 
235 
“ selection, 1124 
“ vowels, 1030 
Ascites, 399 
Aspartic acid, 489 
Asphyxia, 232, 235, 840 
“ artificial respiration 
in, 235 
“ recovery from, 235 
“ spasm, 866 
Aspirates, 662 
Aspiration of heart, 150 
“ thoracic, 150 
“ ventricles, 67 
Assimilation, 429 
Associated movement, 996 
Astatic needles, 690 
Asteatosis, 571 
Asthma nervosum, 770 
“ dyspepticum, 771 
Astigmatism, 963 
“ correction of, 963 
“ test for, 963 
Atavism, 1124 
Atax aphasia, 906 
Ataxia, 776, 893, 904 
Ataxic aphasia, 906 
“ tabes dorsalis, 818 
Atelectasis, 215 
Atmospheric pressure, 240 
“ diminution of, 240 
“ increase of, 241 
Atresia ani, 1096 
Atrophy, 643 
“ of the face, 754 
Atropin, 604 
“ on eye, 966 
“ on salivary glands, 254 
“ on smooth muscle, 604 
Attention, time for, 872 
Audibility of notes, 1026 
Audible tones, 1026 
Auditory after-sensations, 1034 
“ area, 897 
“ aurae, 898 
“ centre, 910 
“ delusions, 760 
“ hairs, 1022 
“ meatus, 1010 
“ nerve, 1008 
“ ossicles, 1013 
“ paths, 898 
“ perceptions, 1024, 
1033 
“ limits of, 1026 
“ variations of, 1026 
“ vesicle, 1122 
Auerbach’s plexus, 280, 287 
Augmentor nerves, 854 
Auricles of heart, 59,61, 66—68 
“ development of, 1109 
Auriculo-ventricular valves, 63 
Auscultation of heart, 89. 
“ of lungs, 209-214 
Automatic excitement, 785 
Autonomy, 873 
Auxocardia, 102 
Avidity, 299 
Axis of vision, 977 
Bacillus, 58, 349, 355 
“ acidi lactici, 350 
“ anthracis, 57 
“ butyricus, 350 
“ subtilis, 351 INDEX. 
1133 
Bacillus, synxanthus, 440 
“ tubercle and others, 
237 
Bacteria, 58, 353 
Bacterium, 58, 349 
“ aceti, 350 
“ coli, 356 
“ fcetidum, 571 
“ lactis, 355 
Ball and socket joints, 638 
Banting cure, 463 
Barsesthesiometer, 1052 
Basal ganglia, 911 
Basedow’s disease, 180, 863 
Bases, 473 
Basilar membrane, 1024 
Bass-deafness, 1027 
Batteries, galvanic, 687 
“ bichromate, 692 
“ Bunsen’s, 692 
“ Daniell’s, 692 
“ Grennet's, 692 
“ Grove’s, 691 
“ Leclanche’s, 693 
“ Noe-Dorffel, 693 
“ Smee’s, 692 
“ storage, 693 
Beats, 1032 
“ isolated, 1032 
“ successive, 1032 
Bed-sores, 735 
Beef tea, 443 
Beer, 449 
Bell’s law, 774 
“ deductions from, 775 
“ paralysis, 758 
Benzoic acid, 513 
Bert’s experiment, 726 
Bidder’s ganglion, 92 
Bilateral movements, 892 
Bile, 333 
“ acids, 333 
“ cholesterin in, 336 
“ constitutents of, 333, 337 
“ crystallized, 334 
“ ducts, 323 
“ *• ligature of, 325 
“ effects of drugs on, 341 
“ electrolysis of, 336 
“ excretion of, 340 
“ fate of, 344 
“ functions of, 342 
“ brases of» 337 
“ in urine, 526 
“ of invertebrates, 336 
“ passage of drugs into, 340 
“ pigments, 335 
“ Platner’s, 334 
“ pressure, 340 
“ reab-orption of, 340 
“ secretion of, 337 
“ secretory pressure of, 340 
“ specific constituents, 338 
“ spectrum of, 336 
“ substances passing into, 
340 
Bile, test for, 334, 335 
Bilharzia, 58 
Biliary fistula, 339 
Bilicyanin, 335 
Bilifuscin, 335 
Bilious vomit, 344 
Biliprasin, 335 
Bilirubin, 32, 335 
Biliverdin, 335 
Binocular vision, 996 
Biological law, 1124 
Biology, xxxv 
Biot’s respiration, 203 
Birth, 1122 
Biuret reaction, 475 
Blastoderm, 1070, 1083 
“ structure of, 1086 
Blastodermic vesicle, 1083 
Blastomeres, 1082 
Blastopore, 1083 
Blastosphere, 1082 
Blastula, 1083 
Blepharospasm, 759 
Blind spot, 974 
Blood, 1 
“ abnormal conditions, 56 
“ action of reagents, 9 
“ analysis, 33 
“ arterial, 54 
“ carbon dioxide in, 53 
“ change by respiration, 
226 
“ circulation of, 105 
“ clot, 35 
“ coagulated, 20 
“ coagulation, 35 
“ color, 1 
“ coloring matter, 21 
“ composition of, 34 
“ current, 136 
“ defibrinated, 36 
“ distribution of, 166 
“ electrical condition of, 
731 
“ elementary granules, 20 
“ extractives, 46 
“ fats in, 45 
“ fibrin in, 20, 35, 57 
“ gases in, 46 
“ glands, 170 
“ heterogeneous, 169 
“ in urine, 524 
“ islands, 11, 1094 
“ lake-colored, 9 
“ loss of, 57 
“ microscopic examina- 
tion, 3 
“ nitrogen in, 54 
“ odor, 2 
“ of hepatic vein, 54 
“ of renal vein, 55 
“ of splenic vein, 54 
“ organisms in, 58 
“ oxygen in, 51 
“ ozone in,52 
“ plasma, 3, 34 
Blood, portal vein, 54 
“ pressure, 139 
“ proteids of, 44 
“ quantity, 55, 57 
“ reaction, I 
“ salts of, 46 
“ serum, 36,45 
“ solvents, 10 
“ specific gravity, 2 
“ sugar in, 46 
“ taste, 2 
‘ ‘ temperature, 3 
“ tests, 31 
“ transfusion of, 56, 168 
“ transparent, 9 
“ velocity of, 156 
“ venous, 54 
“ water in, 46 
Blood-channels, intercellular, 
112 
Blood-corpuscles— 
“ abnormal forms, 21 
“ action of reagents on, 6, 
7. 8, 17 
“ amoeboid movements, 
16 
“ amphibian, 10 
“ animal, 10 
“ carbon dioxide in, 53 
“ chemical composition, 
21-34 
“ circulation, 159, 160 
“ color, 4, 6 
“ colorless, 15-18 
“ composition, 34 
“ conservation of, 8 
“ constituents of, 33 
“ counting, 4 
“ crenation, 6 
“ decay, 14 
“ diapedesis, 18, 161 
“ effects of reagents, 6, 17 
“ elliptical, 11 
“ form, 3, 7 
“ Gowers’ method, 5 
“ histology of, 6 
“ human, red, 3 
“ white, 15, 34 
“ intracellular origin, 13 
“ invertebrate, 11 
“ isotonic point, 8 
“ microscopic examina 
tion, 3, 6 
“ nucleated, 20 
“ number, 4, 20 
“ of newt, 16 
“ origin, II, 12, 13, 14 
“ oxygen in, 51 
“ parasites of, 21 
“ pathological changes, 20 
“ proteids of, 32 
“ red, 3 
“ rouleaux of, 6 
“ size, 3, 21 
“ solvents, 10 
“ staining reagents, 8 1134 
INDEX. 
Blood-corpuscles— 
“ stroma, 6, 9, 32 
“ transfusion of, 56, 168 
“ transparency, 4 
“ vertebrate, 10 
“ weight, 4 
“ white, 15 
Blood-current, 136, 153 
“ in capillaries, 138, 159 
“ in small vessels, 159 
“ in veins, 162 
“ velocity of, 153, 156 
Blood-gases, 46-54 
“ estimation of O, C02, 
and N, 50-54 
“ extraction, 47 
“ gas-pumps for, 47-50 
“ quantity, 55 
Blood-glands, 170 
Blood-islands, 11, 1094 
Blood-plasma, 3, 34, 35 
Blood-plates, 19 
Blood-pressure, 139 
“ arterial, 143 
“ capillary, 149 
“ depressor nerve, 144 
“ effect of vagus, 147 
“ estimation of, 139 
“ how influenced, 143 
“ in pulmonary artery, 
151 
“ in veins, 150 
“ relation to pulse-rate, 
148 
“ respiratory undulations, 
144, 167 
“ tracing, 140 
“ Traube-Hering curves, 
146 
“ variations in animals, 
147 
Blood-vessels, 108 
“ cohesion of, 114 
“ drugs on, 112 
“ elasticity of, 113 
“ lymphatics, 112 
“ pathology of, 114 
“ properties of, 112, 113 
“ structure of, 107 
Blue pus, 571 
“ sweat, 571 
Body, vibrations of, 135 
Body-wall, formation of, 1094 
Bone, 634 
“ chemical composition of, 
634,1108 
“ callus of, 469 
“ effect of madder on, 469 
“ formation of, 1108 
“ fracture of, 469 
“ growth of, 1109 
“ red marrow, 14 
“ structure of, 634 
Bones, mechanism of, 634 
Bottger’s test, 262 
Boutons terminals, 1047 
Bowman’s tubes, 935 
“ glands, 1035 
Box pulse-measurer, 115 
Boyle’s law, 46 
Bradyphasia, 906 
Brain, 821 
arteries of, 927-929 
“ blood-vessels 
“ development of, 1118 
“ general scheme of, 821 
“ impulses, course of, 800 
“ in invertebrata, 930 
“ membranes of, 925 
“ motor areas or regions 
of, 882 
“ movements of, 926 
“ of dog, 886 
“ pressure on, 929 
“ protective apparatus of, 
925 
“ psychical functions of, 
867 
“ pulse in, 135 
“ pyramidal tracts of, 800, 
804 
“ schema of, 821 
“ topography of, 910 
“ weight of, 821, 871 
Branchial arches, 1095 
“ clefts, 1095, 1106 
Brandy, 449 
Bread, 445 
Break induction shock, 697 
Brenner’s formula, 759 
Broca’s convolution, 905 
Bromidrosis, 571 
Bronchi, contraction of, 194 
“ structure of, 187 
“ terminal, 188 
Bronchial arteries, 191 
Bronchial breathing, 212 
“ fremitus, 213 
Bronchiole, 187-190 
Bronchophony, 214 
Bronchus extra-pulmonary, 187 
“ intra-pulmonary, 187 
“ small, 188 
Bronzed skin, 181, 735 
Brownian movement, 259, 260 
Bruit, 163 
“ de diable, 163 
Brunner’s glands, 345, 367 
Buchanan’s experiments, 39 
Budding, 1059 
Buffy coat, 36 
Bulb, 830 
Bulbar paralysis, 837 
Bulbus arteriosus, 1109 
Butter, 436 
Butyric acid, 350, 485 
Cachexia struma priva, 179 
Caffein, 447 
Calabar bean on eye, 742 
Calcium phosphate, 472 
Calculi, biliary, 335, 336, 358 
“ salivary, 258 
“ urinary, 534 
Callus, 469 
Calorie, 411 
Calorimeter, 402 
Calorimetry, 411 
Canal of cochlea, 1020 
“ hyaloid, 945 
“ Nuck, 1116 
“ of spinal cord, 786 
“ of Stilling, 945 
“ Petit, 944 
“ Schlemm, 936 
“ semi-circular, 1021 
Canalis auricularis, 1109 
“ cochlearis, 1020 
“ reuniens, 1021 
Cane sugar, 488 
Capillaries, no, 113 
“ action of silver ni- 
trate on, 110 
“ arrangement of, 159 
“ blood - current in, 
159 
“ circulation, 159 
“ contractility of, 112, 
113 
“ current in, 138 
“ development of, 12 
“ flow in, 107 
“ form and arrange- 
ment of, 159 
‘‘ functions, 114 
“ pressure in, 149 
“ stigmata of, 110 
“ velocity of blood in, 
*56 
Capillary blood-pressure, 149 
“ electrometer, 702 
Capsule, external, 914 
“ Glisson’s, 319 
“ internal, 914, 915 
“ of Tenon, 945 
Carbohydrates, 487 
“ absorption of, 
374- 
“ fermentation of, 
350 
Carbolic acid urine, 515 
Carbon dioxide, conditions af- 
fecting, 222,223, 224 
“ elimination of,by blood, 
226 
“ estimation of, 50, 217 
“ excretion of, 222 
“ in air, 219, 236, 237 
“ in blood, 53 
“ in expired air, 220 
“ where formed, 229 
Carbonic oxide-haemoglobin, 28 
“ oxide, 30 
“ poisoning by, 29 
Cardiac contraction, 101 
“ cycle, 66 
“ dullness, 89 INDEX. 
1135 
Cardiac ganglia, 91 
“ hypertrophy, 69 
“ impulse, 71 
“ “ cause of, 73 
“ “ pathological, 
82 
“ movements, 66-82 
“ murmurs, 87 
“ nerves, 91 
“ nutritive fluids, 93 
“ plexus, 91 
“ poisons, 100 
“ revolution, 30 
“ sounds, 79 
Cardinal points, 950 
Cardiogram, 71 
Cardiograph, 71 
Cardio-inhibitory centre, 848 
“ nerves, 848 
Cardio-pneumatic movement, 
102 
Caricin, 315 
Carnin, 442 
Carotid gland, 182 
Cartilage, 481 
“ articular, 637 
“ formation of, X095 
Casein, 437, 477 
Caseinogen, 437, 477 
Caseoses, 440 
Catacrotic pulse, 119 
Cataphoric action, 695 
Cataract, 943 
Cathartics, 291 
Cathelectrotonus, 716 
Catheterizing the lungs, 225 
Cathode, 690 
Caudate nucleus, 911 
Cavernous spaces, 112 
Cell-albumin, 476 
Cells, 1086 
“ division of, 1086, 1088 
Cellulose, 488 
“ digestion of, 350 
Cement, 267 
“ action of silver ni- 
trate on, 110 
“ substance, no 
Central arteries, 880 
Centre, 785 
“ accelerans, 851 
“ ano-spinal, 814 
“ auditory, 897 
“ cardio-inhibitory, 848 
“ cilio spinal, 814 
“ closure of eyelids, 835 
“ coughing 836 
“ dilator of pupil, 814, 
836 
“ ejaculation, 815 
“ erection, 814 
“ eyelids, 835 
“ for coughing, 836 
“ for defsecation, 814 
“ for mastication and 
sucking, 836 
Centre, for saliva, 836 
“ gustatory, 898, 911 
“ heat-regulating, 865 
“ micturition, 814 
“ olfactory, 898, 911 
“ parturition, 815 
“ respiratory, 837 
“ secretion of saliva, 836 
“ sensory, 895 
“ sneezing, 836 
“ spasm, 866 
“ speech, 905 
“ subordinate spinal, 862 
“ sucking, 836 
“ swallowing, 836 
“ sweat, 815, 866 
“ vaso-dilator, 864 
“ vaso-motor, spinal, 815, 
854 
‘‘ vesico-spin al, 814 
“ visual, 896 
“ vomiting, 836 
“ of gravity, 644 
Centrifugal nerves, 734 
Centripetal nerves, 736 
Centro-acinar cells, 309 
Centrum ovale, 821 
Cereals, 444. 
Cerebellar ataxy, 924 
Cerebellum, 922 
action of electricity on, 924 
connections of, 824 
function of, 922 
pathology of, 924 
removal of, 923 
structure of, 921 
Cerebral arteries, 879 
“ epilepsy, 887 
“ fissures, dog, 886 
“ inspiratory centre,838 
“ motor centres, 874 
“ sensory centres, 895 
“ vesicles, 1090 
Cerebrin, 484, 675 
Cerebro-spinal fluid, 925 
Cerebrum, 821 
“ blood-vessels of, 878 
“ commissural fibres 
of, 882 
“ convolutions of, 880 
“ dog’s, 885 
“ effects of stimulation 
of, 900 
“ epilepsy of, 887 
excision of centres, 
%3 
“ Flourens’ doctrine, 
867 
“ functions of, 867 
“ Goltz’s theory of,900 
gyriof, 871 
“ imperfect develop- 
ment of, 867 
“ lobes of, 880 
motor areas of, 882, 
901 
Cerebrum, movements of, 926 
“ nerve-fibres in, 878 
“ protective apparatus, 
925 
“ removal of, 868 
“ sensory centres, 895, 
908 
“ structure of, 874 
“ sulci of, 871 
“ thermal centres of, 
899, 908 
“ topography of, 901 
Cerumen, 566 
Ceruminous glands, 564 
Cervical sympathetic, section of, 
747 
“ stimulation of, 747 
Chalazae, 1071 
Charcot’s crystals, 240 
“ disease, 735 
Cheese, 441 
Chemical affinity, xl 
“ constituents of body, 
471 
Chess-board phenomenon,1002 
Chest, dimensions of, 208 
Cheyne-Stokes’ phenomenon, 
202 
Chiasma, 738 
Chitin, 484 
Chloral, 858 
Chlorophane, 943 
Chlorosis, 20 
Chocolate, 447 
Cholsemia, 341 
Cholalic acid, 334 
Cholasma, 568 
Cholesteraemia, 342 
Cholesterin, 336 
Choletelin, 335 
Cholin, 675 
Chololiaematin, 336 
Choloidinic acid, 334 
Choluria, 526 
Chondrin, 481 
Chondrigen, 481 
Chorda dorsalis, 1091 
“ saliva, 253 
“ tympani, 253, 755, 
864 
Chordae tendineae, 68 
Chorion, 1085 
“ frondosum, 1098 
“ laeve, 1098 
“ primitive, 1085 
Choroid, 936 
“ vessels of, 938 
Choroidal fissure, 1120 
Christison’s formula, 500 
Chromatic aberration, 962 
Chromatin, 1087 
Chromatophores, 572 
Chromatopsia, 741 
Chromidroses, 571 
Chromophanes, 484, 943 
Chronograph, 613 INDEX. 
Chronology of human develop- 
ment, 1102 
Chyle, 381, 392 
“ movement of, 396 
“ quantity of, 394 
“ vessels, 379 
Chylous urine, 533 
Chyme, 301 
Cicatricula, 1070 
Cilia, 573 
“ conditions for movement, 
574 
“ effect of reagents on, 
574 
“ functions of, 575 
Ciliary ganglion, 746 
“ motion, 573 
“ “ force of, 575 
“ muscle, 937 
“ nerves, 746 
Ciliated epithelium, 573 
Cilio-spinal centre, 814 
Circle of sensation, 1051 
“ of Willis, 927, 928 
Circulating albumin, 457 
Circulation, blood, 59 
“ capillary, 156 
“ duration of, 158 
“ first, 1094 
“ foetal, 1101 
“ portal, 59 
“ pulmonary, 59 
“ schemata of, 138 
“ second, 1094 
“ systemic, 59 
Circumpolarization, 264 
Circumvallate papillae, 1041 
Clang, 1025 
Clarke’s column, 791, 801 
Clasmatocytes, 385 
Clasmatocytosis, 385 
Claustrum, 914 
Cleavage of yolk, 1082 
“ lines of, 1082 
“ partial, 1059 
Cleft sternum, 79 
“ palate, 1105, 1106 
Clerk Maxwell’s experiment, 
970 
Climacteric, 1073 
Clitoris, 1116 
Closing, continued contraction, 
721 
“ shock, 697 
Clothing, 419 
Coagulable fluids, 39 
Coagulated proteids, 478 
Coagulation experiments, 42 
Coagulation of blood, 35 
“ accelerated, 38 
“ amount of salts, 42 
“ Briicke’s experi- 
ments, 40 
“ Buchanan’s re- 
searches, 39 
“ delayed, 37 
Coagulation of blood, effect of 
albumoses, 37 
“ Hewson’s experi- 
ments, 39 
“ phenomena, 36 
“ rapidity of, 38 
“ Schmidt’s experi- 
ments, 40 
“ theories of, 40, 42 
“ time for, 36 
Coca, 447 
Cocaine, 966 
Coccygeal gland, 182, 572 
Cochlea, 1020, 1023 
“ resolution by, 1031 
Coelom, 1094 
Coenurus cerebralis, 1061 
Coffee, 447 
Cog-wheel sound, 213 
Coldblooded animals, 405 
Cold on the body, 426 
“ uses of, 428 
Cold-spots, 1053 
Collagen, 481 
Colloids, 371 
Coloboma, 1120 
Color associations, 1034 
Color-blindness, 986 
“ acquired, 986 
“ testing, 987 
Color sensation, 982 
“ Hering’s theory, 984 
“ Young-Helmholtz 
theory, 984 
Colored shadows, 990 
Coloring matters, 484 
Colorless corpuscles, 15-19 
Color top, 988 
“ . vision, 984 
“ theories of, 984 
Colors, complementary, 982 
“ contrast, 982 
“ geometrical cone, 984 
“ methods of mixing, 
982 
“ mixed, 982 
“ perception of, 981 
“ saturated, 983 
“ simple, 982 
Colostrum, 439 
Columella, 1035 
Columns of the cord, 786 
Coma, diabetic, 332 
Comedo, 571 
Common sensation, 1056 
Commutator, 723 
Comparative—absorption, 401 
circulation, 182 
digestion, 359 
hearing, 1034 
kidney and urine, 556 
metabolism, 490 
motor apparatus, 648 
nerve centres, 930 
nerves and electro-physi- 
ology, 731 
Comparative— 
peripheral nerves, 783, 784 
reproduction and develop 
ment, 1123, 1124 
respiration, 231, 242 
skin, 572 
smell, 1039 
taste, 1043 
temperature, 428 
vision, 1006 
voice and speech, 664 
Compensation of a current, 
702 
Complemental air, 197 
“ space, 210 
Complementary colors, 982 
Compound eye, 1006 
Compressed air, 131 
Conarium, 1118 
Concretions, 355 
Condensed milk, 440 
Condiments, 449 
Conducting path in spinal cord, 
799, 817 
“ “ nutritive cen- 
tres of, 802 
Conduction in animal tissues, 
688 
Conductivity, 724 
Conglutin, 479 
Congo red, 295 
Conjugate deviation, 742, 903, 
995 
Conjugated sulphuric acid, 516 
Conjugation, 1059 
Connective-tissue, 382 
“ chemistry of, 469 
“ spaces, 382 
“ structure of, 383 
Consonance, 1032 
Consonants, 660, 662 
Constant current, action of, 614 
“ in therapeutics, 726 
Constant batteries, 691 
Bunsen’s, 692 
Daniell’s, 692 
Grennet, 692 
Grove’s, 691 
Leclanche’s, 693 
Smee’s, 692 
Constipation, 358 
Contraction, cardiac, 101 
“ fibrillar, 605 
“ initial, 619 
“ muscular, 6o8(see 
Myogram). 
“ remainder, 612 
“ rhythmical, 603 
“ secondary, 708 
“ without metals, 
704 
Contracture, 903 
Contrast, 989 
“ colors, 982 
Converging lenses, 947 
Cornea, 933 INDEX. 
1137 
Cornu ammonis, 876 
Corona radiata, 9x6 
Coronary arteries, 65 
“ effects of ligature of, 
65 
“ plexus, 91 
Corpora quadrigemina, 917 
Corpulence, 463 
Corpus callosum, 911 
“ luteum, 1076 
“ spongiosum, 1076 
“ striatum, 911 
Corresponding points, 996 
Cortical blindness, 896 
Corti’s organ, 1020, 1023 
“ rods, 1023 
Cotyledons of the placenta, 
1070 
Coughing, 216, 765 
“ centre for, 836 
Cracked pot sound, 211 
Cramp, 1058 
Cranial flexures, 1090 
“ nerves, 737 
Cranioscopy, 868 
Crassamentum, 35 
Creamometer, 439 
Cremasteric reflex, 812 
Crepitation, 213 
Crista acustica, 1022 
Croaking experiment, 808- 
Crop, 359 
Crossed heads, 841 
Crossed reflexes, 808 
Crura cerebri, 916 
Crust a, 916 
“ petrosr, 267 
“ phlogistica, 36 
Crying, 217 
Crystallin, 476, 943 
Crystalline lens, 943 
“ development of, 
1088 
“ spheres, 1006 
Crystallized bile, 334 
Crystalloids, 371 
Cubic space, 237 
Curare, action of, 600, 601, 604, 
857 
“ on motor nerves, 600, 
604 
Current, velocity of, 105 
Cutaneous respiration, 228, 
565 
“ sensibility, 1049 
“ trophic affections, 
735 
Cuticular membrane, 268 
Cyanogen, 30 
Cyanuric acid, 489 
Cylindrical lenses, 962 
Cynuric acid, 514 
Cyrtometer, 209 
Cysticercus, 1061 
Cystin, 489, 530 
Cytozoon, 8 
Daily gains, 429 
“ losses, 429 
“ quantity of gases res- 
pired, 221 
Daltonism, 986 
Damping apparatus, 1012 
Darby’s fluid meat, 304 
Death of a nerve, 686 
Debove’s membrane, 187 
Decidua reflexa, 1097 
“ serotina, 1098 
“ vera, 1098 
Decubitus acutus, 920 
Decussation of pyramids, 832 
Deep reflexes, 812 
Defaecation, 284 
“ centre for, 814 
Defibrinated blood, 36 
Degeneration, fatty, 329, 464, 
684 
“ in spinal cord, 
799 
“ traumatic, 684 
Deglutition, 273 
“ action on other 
centres, 278 
“ apnoea, 840 
li Kronecker’s expe- 
riments on, 275 
“ nerves of, 277 
“ nervous mechan- 
ism, 277 
“ stages of, 274 
“ time relations, 276 
Deiter’s cells, 795 
Delomorphous cells, 292 
Demarcation currents, 703, 
714 
Demilunes, 249 
Demodex folliculorum, 566 
Denis’s plasmine, 39 
Dentine, 267 
Dentition, 270 
Depressor fibres, 859 
“ nerve, 766, 859 
Derived albumins, 477 
Deutero-albumose, 478 
Dextrin, 488 
Dextrose, 487 
Diabetes insipidus, 527 
“ mellitus, 57, 330, 527 
Diabetic coma, 332 
Dialysis, 372 
Diapedesis, 18, 161 
Diaphanometer, 440 
Diaphoretics, 567 
Diaphragm, action of, 205 
“ movements of, 199 
Diarrhoea, 359 
Diastatic action, 260, 262, 312, 
347- 483 
Diastole, 66 
Diazo-reaction, 530 
Dichroism, 22 
Dicrotic pulse, 125 
“ wave, 121 
Diet, 451 
“ adequate, 454 
“ conditions for, 452 
*• effect of age on, 455 
“ effect of work on, 455 
“ fat, 459 
“ flesh, 458 
“ flesh and fat, 460 
“ mixed, 459 
*• of carbohydrates, 459 
“ quality of, 451 
“ quantity, 451 
Dietaries, 455 
Difference theory, 714 
Differential rheotome, 709 
“ tones, 1033 
Diffraction spectrum, 607 
Diffusion, 370 
“ circles, 953 
“ of gases, 47 
“ in lungs, 225 
Digestion, 243 
“ artificial, 358 
“ comparative, 359 
“ during fever, 358 
“ historical, 360 
“ in plants, 360 
Digestive apparatus, 265 
Dilatation of pupil, centre for, 
814, 836 
Dilator pupilbe muscle, 964 
Dilemma, 872 
Diopter, 962 
Dioptric, 962 
“ observations, 946 
Diphthongia, 663 
Diphthongs, 661 
Diplacusis, 1027 
Diplopia, 996 
Direct cell-division, 1087 
*‘ cerebell ar tract, 80 X, 804 
“ vision, 977 
Directing globules, 1081 
Direction of sound perception, 
1033 
Discharging forces, 599 
Disc tactil, 1047 
Discus proligerus, 1068 
Disdiaclasts, 590 
Displacement of the phases, 
1028 
Dissociation, 228 
Dissonance, 1033 
Distance, estimation of, 1003 
“ false estimate of, 1003 
“ smallest appreciable, 
1051 
Diuretics, 537 
Division of animals, 1059 
“ cells, xo86, 1092 
Double conduction in nerve, 
724 
“ contact, feeling of, 1049 
“ images, neglect of, 998 
“ vision, 996 
Dreams, 872 1138 
INDEX. 
Drepanidium, 8 
Dromograph, 155 
Dropsy, 399 
Drowning, 235 
Duct of Cuvier, 11II 
“ Gaertner, 1115 
Ductus arteriosus, 1101 
“ cochlearis, 1020 
“ venosus, 1101, 1112 
Dura mater, 925 
Dust particles, 236 
Dys-albumose, 302 
Dyschromatopsy, 986 
Dyslysin, 334 
Dysperistalsis, 288 
Dyspnoea, 202, 232, 841 
“ causes of, 841 
Ear, 1008 
“ action of drugs on, 1034 
conduction to, 1008,1019 
“ development of, 1121 
“ external, 1010 
“ external meatus, 1010 
“ fatigue of, 1034 
“ fineness of, 1027 
“ fluids of, 1024 
in animals, 1034 
labyrinth of, 1020 
“ manometer, 1019 
“ muscles of, 1010 
• ossicles of, 1013 
“ speculum, 1011, 1012 
“ tympanic membrane,1011 
Earthy phosphates, 518 
Ebner’s glands, 244 
Eccentric hypertrophy, 69 
Echo speech, 873 
Ectoderm, 1083 
Ectopia cordis, 75, 79 
Efferent nerves, 734 
Effusions, 399 
Egg albumin, 45, 476 
Eggs, 441 
Ehrlich’s reaction, 530 
Ejaculation, centre for, 815 
Elastic after-effect, 625 
“ fibres, 385 
“ pulse elevations, 124 
“ tension of lungs, 151, 
196 
“ tubes, 108 
“ tubes, flow in, 107, 158 
Elasticity of blood-vessels, 113 
“ lens, 955 
“ muscle, 624 
“ uses of, 626 
Elastin, 481 
Electrical charge of body, 731 
“ currents of eye, 710 
*• “ glands, 705 
“ heart, 707 
“ “ membranes, 
711 
*• “ muscle, 702 
Electrical currents, nerve, 702, 
725 
“ “ skin, 705 
“ fishes, 731 
“ history, 733 
“ nerves, 736 
“ organs, 731, 732 
“ phenomena in plants, 
716 
stimulation of eye,970 
“ variation during cer- 
ebral action, 894 
Electricity, therapeutical uses, 
726 
Electrodes, non-polarizable,694 
“ other forms, 726 
Electrolysis, 690 
“ of animal tissues, 
474 
Electrometer, 702 
Electro-motive force, 687 
Electro-physiology, 687 
Electro-therapeutics, 726 
Electro-tonic alteration of ex- 
citability, 716 
“ currents, 711 
“ phenomena in 
conduction, 712 
Electrotonus, 711 
“ in inhibitory 
nerves, 718 
“ in motor nerves, 
717 
“ in muscle, 718 
in sensory nerves, 
718 
“ muscle - current 
during, 712 
Eleidin, 558 
Elementary granules of blood, 
20 
Embolism, 39 
Embrace experiment, 808 
Embryo, formation of, 1093 
Emetics, 282 
Emmetropic eye, 958 
Emotions, expression of, 664 
Emptiness of arteries, 855 
Emulsification, 315 
Emulsin, 399 
Emulsion, 315 
Emydin, 479 
Enamel, 267, 268 
Enamel-organ, 269 
Enchylema, 1087 
End-bulbs, 1046 
“ organs, 931 
“ plate, 582 
Endocardial pressure, 69, 79 
Endocardium, 63 
Endochondral bone, 1108 
Endoderm, 1083 
Endolymph, 1021, 1024 
Endomysium, 576 
Endoneurium, 672 
Endosmometer, 371 
Endosmosis, 370 
Endosmotic equivalent, 371 
Enemata, 379 
Energy, conservation of, xli 
“ potential, xli 
Engelmann’s experiment. 721 
Entoptical phenomena, 968 
“ pulse, 134, 969 • 
Entotic perceptions, 1034 
Enuresis nocturna, 556 
Enzyme, 260 
Eparterial bronchi, 187 
Ependyma, 795 
Epiblast, 1083, 1086 
“ structures formed 
from, 1088, 1093 
Epicardium, 60 
Epidermal appendages, 467 
Epididymis, 1062 
Epidural space, 926 
Epigenesis, 1124 
Epiglottis, 275 
“ injury to, 275 
Epilepsy, 866 
Epileptic zone, 866 
Epineurium, 671 
Epiphysial cartilage, 1109 
“ eye, 1006 
Epiphysis cerebri, 920 
Epithelium ciliated, 573 
Eponychium, 561 
Equator, 711 
Equilibration, 760 
Equilibrium, 818 
Erectile hairs, 564 
“ tissue, 1076 
Erection, centre for, 814 
“ mechanism of, 1076 
“ of penis, 1076 
Erect vision, 953 
Ergograph, 632 
Ergostat, 624 
Errhines, 217 
Erythroblasts, 13 
Erythrochloropy, 986 
Erythro-dextrin, 261 
“ granulose, 488 
Eshbach’s method, 523 
Eserine, 966 
Ether, xxxvi 
Eudiometer, 50 
Eucalin, 488 
Euperistalsis, 287 
Eupnoea, 840 
Eustachian catheter, 1019 
“ tube, 1017 
“ valve, 1110 
Excised eye, 967 
Excitability, action of drugs 
on, 816 
“ of muscle, 599, 
600 
Excitable points of a nerve,686 
Excito-motor nerves, 736 
Excretin, 352 
Excretion of faecal matter, 284 
citability, 716 INDEX. 
1139 
Excretory organs, 491 
Exophthalmos, 781, 863 
Expectorants, 238 
Experimentum mirabile, 874 
Expiration, 196, 200 
“ forced, 204 
“ mechanism of, 207 
“ ordinary, 207 
Expiratory muscles, 205 
Explosives, 663 
Extensor tetanus, 807 
External capsule, 914 
“ genitals, development 
of, 1116 
“ secondary resistance, 
695 
Extra-current, 696 
Extrapolar region, 717 
Extremities, development of, 
1096 
Exudation, 400 
Eye, 933-1007 
“ accommodation of, 953 
“ artificial, 952, 974 
“ astigmatism, 962 
“ chromatic aberration of, 
962 
“ compound, 1006 
“ development of, 1120 
“ effect of electrical cur- 
rents, 970 
“ emmetropic, 958 
“ entoptical phenomena,968 
“ epiphysial, 1006 
“ excised, 967 
“ fundus of, 973 
“ hypermetropic, 959 
“ illumination of, 970 
“ movements of, 991 
“ muscles of, 994 
“ myopic, 959 
“ pineal, 1006 
“ presbyopic, 960 
protective organs, 1003 
“ refractive power of, 958 
“ structure of, 933 
Eyeball, axes of, 991, 992 
“ movements of, 991 
“ muscles of, 994 
“ planes of, 992 
positions of, 992 
“ protective apparatus, 
1003, 1004 
“ protrusion of, 991 
“ retraction of, 991 
“ simultaneous move- 
ments of, 996 
Eye-currents, 710 
Eyelids, 1003 
Eyes in lower animals, 1006 
Facial bones, development of, 
1104 
“ development, arrested, 
1103 
Facial nerve, 754 
Faecal matter, 354 
“ “ excretion of, 284 
Faeces, 354 
Fainting, 70 
Fallopian tubes, 1074 
Fall-rheotome, 714 
Falsetto voice, 659 
Faradic current, 697 
“ electricity, 697 
Faradization in paralysis, 728 
in therapeutics, 726 
Far point, 958, 960 
Fascia lymphatics of, 397 
Fatigue of muscle, 613, 630 
“ stuffs, 630 
Fat-cells, 461 
Fats, 485 
“ absorption of, 377 
“ fate of, 378 
“ fermentation of, 351 
“ metabolism of, 459 
“ origin of, 460 
Fat-soaps, absorption of, 375 
Fat-splitting ferment, 315 
Fatty acids, 378, 484 
“ degeneration, 329, 464 
“ infiltration, 329 
Febrifuges, 424 
Fechner’s law, 932 
Fehling’s solution, 263, 529 
Female pronucleus, 1081 
Fermentation, 448 
“ in intestine, 348 
“ test, 264 
Ferments, 482-484 
“ fate of, 348 
“ organic, 483 
“ organized, 483 
“ unorganized, 483 
Fertilization of ovum, 1079 
Fever, 423 
“ after transfusion, 168 
Fibres of Tomes, 268 
Fibrillar contraction, 605 
“ “ of heart, 99 
Fibrin, 20, 3s, 478 
“ formation of, 44 
“ properties, 36 
Fibrin factors, 41 
“ sources of, 43 
Fibrin-ferment, 40, 41 
Fibrinogen, 40, 477 
Fibrinoplastin, 40 
Fibroin, 480 
Field of vision. 953 
“ contest of, 1001 
Filaria sanguinis, 533 
Filiform papillse, 1040 
Fillet, 916 
Filtration, 372 
First respiration, discharge of, 
847 
“ effects of, on thorax,215 
Fish extract, 443 
Fission, 1059 
Fistula, biliary, 339 
“ gastric, 301 
intestinal, 346 
pancreatic, 311 
“ pyloric, 298 
“ Thiry’s 346 
*■ Vella’s, 346 
Flame spectra, 25 
Flavor. 452, 1039, 1042 
Fleischl’s htemometer, 24 
Flesh, 442 
Flight, 649 
Floor-space, 237 
Flourens’ doctrine, 867 
Fluid vein, 163 
Fluids, flow of, in tubes, 105 
“ introduction of, 265 
Fluorescence, 981 
“ in eyeball, 953 
Fluorescin, 946 
Focal distance, 947 
“ line, 957 
“ point, 948 
Foetal circulation, noi 
“ membranes, 1097 
“ “ formation of, 
1102 
Foetus, 1102 
“ movements of, 1103 
Follicles, solitary, 368 
Fontana’s markings, 676 
Fontanelle, pulse in, 134 
Fontanelles, 135 
Foods, introduction of, 265 
“ isodynamic, 402 
“ plastic, 451 
“ quantity, 453, 455 
“ respiratory, 451 
“ utilization of, 446 
“ vegetable, 444 
Food-stuffs, 243 
“ amount of, 454 
Foramen ovale, 1101, 1110 
“ of Magendie, 925 
! Force of accommodation, 960 
Forced movements, 919 
Forces, xxxvii 
Fore-gut, 1093 
Formatio reticularis, 833 
Formative cells, 1086 
Fovea cardica, 1094 
“ centralis, 941, 977 
I Fractional heat coagulation, 45 
Fraunhofer’s line, 25 
Free acid, formation of, 299 
“ acids, 473 
Fremitus, 213 
1 Friction sounds, 87 
Frog current, 705 
“ heart manometer, 96 
Frommann’s lines, 669, 671 
Frost, action of, 426 
Fruits, 446 
Functional substitution, 868 
Fundamental n te, 1012 
“ tone, 1028 INDEX. 
Fundus glands, 292 
Fungi, 349 
Fungiform papillae, 1040 
Gaertner, ducts of, 1115 
Galactorrhoea, 435 
Galactose, 487 
Gall-bladder, 318 
Gallop, 648 
Gall-stones, 358 
Galton’s whistle, 1026 
Galvanic battery, 687 
“ excitability, 729 
“ polarization, 691 
Galvano-cautery, 731 
Galvanometer, 689 
“ reflecting, 694 
“ thermo-electric, 
397 
Galvano-puncture, 731 
“ tonus, 680 
Gamgee’s method, 41 
Ganglionic arteries, 879 
Gangrene, 736 
Gargling, 217 
Gaseous exchanges, 222 
Gases, absorption of, 46 
“ diffusion of, 47 
“ dissociation of, 227 
“ extraction of, 47- 
“ in blood, 46 
“ “ in arterial blood, 51 
*• “ in body, 472 
*• “ estimation, 47, 49 
“ “ ozone. 52 
“ “ total gases, 51 
in lymph, 230 
“ in stomach, 308 
indifferent, 236 
“ irrespirable, 236 
“ narcotic, 236 
“ poisonous, 236 
“ respired, 196 
Gaskell’s clamp, 95 
Gas-pumps, 48, 49, 50 
“ Alvergniat’s, 50 
“ Pfliiger’s, 48 
Gasserian ganglion, 745 
Gas-sphvgmoscope, 119 
Gastric digestion, 301 
“ artificial, 305 
“ comparative, 307 
“ conditions affecting, 304 
“ fistula, 301 
“ pathological variations, 
356 
products of, 303 
Gastric juice, 294 
“ action of drugs on, 300 
“ action on foods, 305 
“ “ milk, 305 
“ “ proteids, 301 
“ tissues, 301,306 
“ actions of, 301 
Gastric juice, methods of ob- 
taining, 300 
“ secretion of, 296, 299 
Gastrula, 1083 
Gaule’s experiment, 8 
Gelatin, 481 
“ peptone, 307, 481 
“ v. albumin, 459 
Gemmation, 1059 
Genital cleft, 1117 
“ cord, 1115 
“ corpuscles, 1046 
“ eminence, 1116 
Genu valgum, 642 
“ varum, 642 
Geometrical color-cone, 983 
Germ cell, 1059 
Germ-epithelium, 1067, 1092 
Germinal area, 1084 
“ membrane. 1083 
Germinating cells, 386 
Germs in air, 237 
Gestation, period of, 1103 
Giddiness, 761 
Gills, 242 
Ginglymus, 637 
Giraldes, organ of, 1115 
Girdle sensation, 819 
Gizzard, 280 
Glance, 1001 
Glands, albuminous, 243 
“ Blandin’s, 244 
“ Bowman’s, 1035 
“ Brunner’s, 294, 345, 
367 
“ buccal, 243, 244 
“ cardiac, 292 
“ carotid, 92, 182 
“ ceruminous, 564, 566 
“ changes in,250 
“ classification of, 246 
“ coccygeal, 181, 572 
“ development of, 1113 
*• Ebner’s, 244 
“ fundus, 292 
“ gastric, 290 
“ Harderian, 1006 
“ lachrymal, 1004 
“ Lieberkiihn’s, 346, 366 
“ lingual, 244 
“ lymph, 387 
“ mammary, 433 
“ Meibomian, 566, 1003 
“ mixed, 244,1033 
“ Moll’s, 564 
“ mouth, 243 
“ muco-salivary, 244 
“ mucous, 244 
“ Nuhn’s, 244 
“ parotid, 256 
“ peptic, 292 
“ Peyer’s, 369 
“ pyloric, 293 
“ retro lingual, 249 
“ salivary, 243, 247 
“ sebaceous, 564 
Glands, secretory, 246 
“ serous, 243 
li solitary, 370 
“ sub lingual, 256 
sub-maxillary, 247, 252 
sweat, 564 
“ tongue, 244 
“ uterine. 1072 
“ Weber’s, 244 
Glandular nerves, 255 
Glaucoma, 748 
Glia cells, 795, 799 
Gliadin, 479 
Glisson’s capsule, 319 
Globin, 477 
Globulins, 476 
Globuloses, 302 
Globus pallidus, 914 
Glomerulus, 493 
Glosso-pbaryngeal nerve, 762 
Glossoplegia, 772 
Glossy skin, 73; 
Glottis, 652 
Glucose, 330, 487, 527 
“ tests lor, 263, 528 
Glucoses, 487 
Glucoddes, 484 
Glutamic acid, 489 
Gluteal reflex, 812 
Gluten, 479 
Glycerine, 485 
“ method, 262 
Glycerin-phosphoric acid, 486 
Glycero phosphate of neurin, 
33 
Glycin, 489 
Glycocholic acid, 333 
Glycogen, 325, 488 
“ effects of food, 317 
‘ • of muscle, 328 
“ preparation, 325 
“ quantity, 327 
Glycogenic function, 327 
Glycogeny, 327 
Glycuronic acid. 489 
Glycolic acid, 486 
Glycosuria, 330, 527 
Gmelin-Heintz’ reaction, 335 
Gmelin’s test, 335 
Goblet cells, 364 
Goitre, 179 
Golgi’s method, 878 
Goll’s column, 803 
Goltz’s balancing experiments, 
869 
“ croaking experiment, 
808 
“ embrace experiment, 
. 808 
“ oesophagus experiments, 
279 
“ view of cerebral action, 
900 
Gorham’s pupil photometer, 967 
Gout, 57 
Gower’s tract, 805 INDEX. 
1141 
Graafian follicle, 1069 
Gracilis experiment, 725 
Grandry’s corpuscles, 1046 
Granules, elementary, 20 
Granulose, 261 
Grape-sugar, 330, 488, 527 
“ absorption of, 374 
“ estimation of, 264 
“ injectedintoblood, 
. 332. 
“ in urine, 527 
“ tests for, 263, 528 
“ volumetric analy- 
sis, 529 
Gravitation, xxxvii 
Great auricular nerve, 859 
Green-blindness, 986 
Green vegetables, 446 
Grove’s cell, 691 
Growth, 471 
Guanidin, 614 
Guanin, 4S9, 576 
Guarana, 447 
Gubernaculum testis, 1116 
Gudden’s method, 799 
Gum, 488 
Gustatory cells, 1042 
“ centre, 898, 909 
“ fibres, 756 
“ region, 1040 
“ sensations, 1042 
“ “ subjective, 
1043 
Gymnastics, 642 
Gymnotus, 731 
Gyri, 821 
Haemacytometer, 5 
Haemadynamometer, 139 
Haematachometer, 155 
Haematin, 30 
“ acid, 30 
“ alkali, 30 
“ iron free, 3i 
Haematoblasts, 20 
Haematohidrosis, 571 
Haematoidin, 32 
Haematoma aurium, 736 
Haematoporphyrin, 31 
Haematuria, 524 
Haemautography, 119 
Haemin and its tests, 31 
Haemochromogen, 30 
Haemocyanin, 11, 45 
Haemocytolysis, 7 
Haemocytolrypsis, 7 
Haemodromometer, 153 
Haemodynamometer, 139 
Haemoglobin, 6, 21, 484 
“ amount of, 24 
“ analysis, 21 
“ animal, 24 
“ carbonic oxide, 
28 
“ colorless, pro- 
teid, 32 
Haemoglobin, composition, 21 
“ compounds of, 26, 
30 
“ crystals, 21 
“ decomposition of, 
3° 
“ estimation of, 23 
“ nitrates on, 28 
“ nitric oxide, 30 
“ oxygen com-! 
pound, 26 
“ pathological, 24 
“ preparation, 22 
“ proteids of, 32 
“ reduced, 27 
“ spectrum, 27 
Haemoglobinometer, 23 
Haemoglobinuria, 169, 525 
Haemometer, 24 
Haemophilia, 37 
Haemorrhage, 57, 58 
“ death by, 57 
“ effect on, 855 
Haemorrhagic diathesis, 37 
Haidinger’s brushes, 970 
Hair, 561 
“ cells, 1023 
“ development of, 563 
“ follicles, 561 
“ “ nerves in, 1048 
Halisterisis, 643 
Hall’s, Marshall, respiratory 
method, 235 
Hallucinations, visual, 741 
Hammarsten on blood-coagu- 
lation, 42 
Harderian gland, 1006 
Hare-lip, 1105 
Harmony, 1033 
Harrison’s groove, 201 
Hassall’s corpuscles, 177 
Hawking, 216 
Hayem’s fluid, 8 
Hay’s test, 335 
Head-fold, 1093 
Head-gut, 1093 
Hearing, 1008 
Heart, 60 
“ accelerated action, 79 
“ acids on, 98 
“ action of fluids on, 96 
“ action of gases, 89 
“ action of poisons on, 98, 
100, 101 
“ amphibian, 182 
“ apex, 97 
“ apex-beat, 71 
“ arrangement of fibres, 
60 
“ aspiration of, 150 
“ auricle fibres, 60 
“ auricular systole, 67 
“ automatic centres, 92 
“ “ regulation, 64 
“ birds’, 182 
“ blood-vessels of, 64, 65 
Heart, changes in shape, 76 
“ chemical stimuli on, 100 
“ chordae tendinese, 68 
“ contraction, nature of, 
101 
“ defective sounds, 85 
“ development of, 1109 
“ diastole, 66 
“ direct stimulation of, 
98 
“ drugs on, 98 
“ effect of cutting, 94 
“ “ ligature, 94 
“ electrical stimuli on, 99 
“ endocardium, 63 
“ examination of, 89 
“ fibrillar contraction, 99 
“ fish, 182 
“ fluids on, 96 
“ formation of, 1093 
“ frog’s, 60, 91 
“ ganglia of, 91 
“ gases on, 100 
“ heat and cold on, 98 
“ hypertrophy of, 69, 70 
“ impulse and cause, 71, 
73 
“ innervation of, 90 
“ in invertebrata, 182 
“ intracardiac ganglia, 91 
“ limits of, 89 
“ mammalian, 182 
“ manometer, 96 
“ movements of, 66 
“ “ persistence 
of, 88 
“ murmurs, 88 
“ muscular fibres, 60 
“ myocardium, 63 
“ nerves, 92 
“ nutritive fluids, 93 
“ palpitation of, 70 
“ pathological impulses, 
82 
“ pause of, 66, 69 
“ pericardium, 63 
“ physical examination of, 
89 
“ poisons on, 100 
“ position of valves, 87 
“ Purkinje’s fibres, 64 
“ refractory period, 93 
“ regulation of, 64 
“ reptilian, 182 
“ respiratory pressure on, 
103 
“ section of, 95 
“ sounds of, 84 
“ Stannius’s experiment, 
94 
“ staircase beats of, 95, 
100 
“ systole, 66 
time for movements of, 
77 
“ valves of, 63 INDEX. 
Heart, ventricular aspiration, 
67 
“ ventricular fibres, 62 
“ veratrin on, 98 
“ weight, 64 
“ work of, 158 
Heat, xxxix, 402 
“ balance of, 420 
“ calorimeter, 411 
“ capacity, 411 
“ centres, 416, 417 
“ conductivity, 413 
“ dyspnoea, 202, 841 
“ employment of, 425 
“ estimation of, 411 
“ excretion of,418 
“ formation in muscle, 627 
“ income and expenditure, 
420 
“ in inflamed parts, 428 
“ in muscle, 627 
“ latent, 402 
“ production, 404, 421, 899 
“ regulating centre, 865 
“ regulation of loss, 417 
“ “ of production, 
416 
“ relation to work, 421 
“ sources of, 402, 404 
“ specific, 411 
“ stiffening, 598 
“ storage of, 423 
“ units, xxxix, 403, 411 
“ variations in production, 
42X 
Helicotrema, 1020 
Heller’s test, 263, 522 
“ blood-test, 526 
Helmholtz’s modification, 697 
Hemeralopia, 741 
Hemialbumin, 303 
Hemialbumose, 301, 302, 478 
Hemiansesthesia, 909 
Hemianopia, 739 
Hemianopsia, 740 
Hemicrama, 863 
Hemiopia, 740 
Hemipeptone, 302, 478 
Hemiplegia, 901 
Hemisystole, 83 
Henle’s loop, 493 
“ sheath, 662 
Hen’s egg, 1070 
Hensen’s experiments on the 
cochlea, 1031. 
Hepatic zones, 320 
Hepatogenic icterus, 341 
Herbst’s corpuscles, 1047 
Hering’s theory of color, 984 
Hermann’s theory of tissue 
currents, 714 
Hermaphroditism, 1059 
Herpes, 754 
Hetero-albumose, 302, 478 
“ -xanthin, 511 
Heterologous stimuli, 931 
Hewson’s experiment, 39 
Hiccough,217 
Hippocampus, 876 
Hippuric acid, 512 
“ “ formation of, 
5*3, 543 
Hippus, 742 
Histo-haematin, 181 
Historical— 
absorption, 401 
circulation, 183 
digestion, 360 
hearing, 1035 
kidney and urine, 556 
metabolism, 490 
nerves and electro-physi- 
ology. 733 
nerve-centres, 930 
peripheral nerves, 784 
reproduction and develop- 
ment, 1059 
respiration, 242 
skin, 572 
smell, 1040 
taste, 1043 
temperature, 428 
vision, 1007 
voice and speech, 665 
Hoarseness, 664 
Holoblastic ova, 1070 
Homoiothermal animals, 405 
Homologous stimuli, 931 
Hooke’s law, 625 
Horopter, 997 
Hot-spots, 1053 
Howship’s lacunae, 1109 
Humor, aqueous, 946 
Hunger, 456 
Hyalin, 484 
Hyaloid canal, 945 
Hybernation, 202, 427 
Hybrids, 1080 
Hydatids, 1061 
Hydraemia, 58 
Hydramnion, 1096 
Hydrobilirubin, 336 
Hydrocele, 399 
Hydrocephalus, 399 
Hydrochloric aci 1, 295 
“ tests for, 295 
“ where formed, 
298 
Hydrocyanic acid, 29 
Hydroh t c ferments, 482 
IlydionephroMs, 556 
Hydroparacumaric acid, 489 
Hydroquinon, 516 
Hydro-tatic test, 195 
Hydrothorax, 399 
Hydroxy-benzol, 516 
Hyo-cholalic acid, 334 
Hypakusis, 760 
Hypalgia, 1057 
Hyparierial bronchi, 187 
Hyperaesthesia, 816 
“ optica, 741 
Hyperakusis, 759 
Hyperalgia, 1057 
Hyperdicrotism, 125 
Hypergeusia, 1043 
Hyperglobulie, 56 
Hyperidrosis, 570 
Hyperkinesia, 817 
Hypermetropia, 959 
Hyperoptic, 959 
Hyperosmia, 738 
Hyperpnoea, 233 
Hyperpselaphesia, 1056 
Hypertrophy of heart, 69, 70 
“ of muscle, 643 
Hypnotics, 873 
Hypnotism, 873 
Hypoblast, 1083 
“ structures formed 
from, 1091, 1093 
Hypogeusia, 1043 
Hypoglossal nerve, 772 
Hypophysis cerebri, 182, 920, 
'1118 
Hypopselaphesia, 1056 
Hyposmia, 738 
Hypospadias, 1116 
Hypoxanthin, 489 
Ichthidin, 479 
Ichthulin, 479 
Icterus neonatorum, 341 
Identical points, 996 
Idio-muscular contraction, 605 
Ileo-colic valve, 283 
Ileus, 284 
Illumination of eye, 970 
Illusion. 932 
Illusions of motion, 988 
Images, formation of, 947 
Imbibition currents, 715 
Impeded distole, 70 
Impregnation, 1081 
Impulse, cardiac, 71, 73 
Impulses in brain, course of, 
826 
Impurities in air, 236 
Inanition, 457 
Incisures, 670 
Income, 454 
Inco-oidinated movements, 776 
Indicati, 515 
Indifferent point, 716 
Indigo, 515 
“ blue, 515 
“ carmine test, 528 
Indigogen, 515 
Indirect cell-division, 1087 
“ vision, 977 
Indol, 313, 352, 489 
Induced currents, 696, 697 
Induction, 696 
Inductorium, 699 
Inf rior maxillary nerve, 750 
Inflammation, 161 
Inhibition, nature of, 811 INDEX. 
1143 
Inhibition of reflexes, 809 
Inhibitory action of brain, 900 
“ centres, 810 
“ nerves, 736, 779 
“ for heart, 848 
“ for intestine, 289 
“ for respiration, 845 
Inion, 911 
Initial contraction, 619 
Inorganic constituents of body, 
471 
Inosinic acid, 489 
Inosit, 488 
Insectivorous plants, 360 
Inspiration, 195, 200 
“ centre for, 838 
“ forced, 203 
“ muscles of, 203 
“ ordinary, 203 
Insufficiency of aortic valves, 
129 
Intelligence, degree of, 871 
Intensity of a tone, 1025 
“ perception of, 1025 
Intercellular blood-channels, 
112 
Intercentral nerves, 737 
Intercostal muscles, 206 
Interference, 1032 
Interglobular spaces, 268 
Interlobular vein, 319 
Intermedio-lateral tract, 791 
Internal capsule, 914 
“ polarization, 695 
“ reproductive organs, 
UI5 
“ respiration, 185, 228 
Intestinal fistula, 346 
“ gases, 348 
“ juice, 345, 347 
“ “ actions of, 347 
“ “ nerves on, 348 
“ movements, 282 
“ “ conditions in- 
fluencing, 287 
“ “ influence of 
drugs, 289 
“ “ influence of 
nerves, 289 
“ “ paresis, 288 
Intestine, 283 
“ artificial circulation, 
289 
“ comparative length 
of, 283 
“ development of, 
1113 
“ fermentation pro- 
cesses in, 348 
“ fungi of, 349 
“ large, 353, 37° 
“ length of, 345 
“ micro-organisms in, 
353 
“ reaction of, 353 
“ small, 362 
Intracardiac nerves, 91 
“ pressure, 99 
Intralabyrintbme pressure, 1024 
Intralobular vein, 319 
Intranuclear network, 1087 
Intraocular pre.-sure, 945, 967 
“ tension, 748 
Intrathoracic pressure, 214 
Intravascular hemorrhage, 861 
Inulin, 488 
Inunction, 571 
Invert sugar, 487 
Inverted image. 946 
Invertin, 347, 351 
Ions, 690 
Iris, 937 
“ action of poisons on, 966 
“ blood-vessels of, 937 
“ functions of, 964 
“ movements of, 965 
“ muscles of, 964 
“ nerves of, 964 
Iron free haematin, 31 
Irradiation, 989 
“ of pain, 1056 
Ischuria, 556 
Island of Reil, 880 
Isodynamic foods, 403 
Isolated beats, 1032 
Isometrical muscular acts, 619 
Isotropous, 579 
Jacksonian epilepsy, 905 
Jacobson’s organ, 1036 
Jaeger’s types, 960 
Jaundice, 340 
Jaw jerk, 813 
Joints, 637 
“ arthrodial, 638 
“ ball and socket, 638 
“ ginglymus, 637 
“ mechanism of, 637 
“ rigid, 638 
“ screw-hinge, 637 
“ spiral, 637 
Jugular vein pulse, 165 
Juice canals, 382 
Karyokinesis, 1087 
Karyomiton, 1087 
Karyomitosis, 1087 
Karyoplasma, 1087 
Katabolic metabolism, 429 
“ nerves, 736 
Katalepsy, 873 
Rations, 690 
Keratin, 480 
Keratitis, 758 
Keys, 700 
“ capillary contact, 701 
“ friction, 700 
“ plug> 701 
Kidney, 492 
Kidney, blood-vessels of, 497 
543 
“ chemistry of, 543 
“ conditions affecting, 
544 
“ extirpation of, 541 
“ perfusion of blood, 
548 
“ reabsorption in, 541 
“ secretion by, 535 
“ structure of, 493 
“ vaso- motor nerves, 
547 
“ volume of, 546 
Kinesodic substance, 815 
Kinetic energy, 402 
“ theory, 761 
Klang, 1025 
Knee-jerk, 813 
“ phenomenon, 813 
‘‘ reflex, 813 
Koenig’s manometric flames, 
1030 
Koumiss, 440 
Krause’s end bulbs, 1046 
Kreatin, 489 
Kreatinin, 489, 511 
“ properties, 511 
“ quantity, 511 
'• test, 511 
Kreatinin-zinc-chloride, 511 
Kresol, 489 
Kryptophanic acid, 517 
Kiihne’s artificial eye, 952 
“ experiments, 705 
“ gracilis experiment, 
725 
“ pancreas powder, 314 
“ sartorius experiment, 
725 
Kymograph, 139 
“ kick's, 141 
“ Heiing’s, 142 
“ Ludwig’s, 139 
Kyphosis, 642 
Labials, 663 
Labor, power of, 1122 
Labyrinth of ear, 760, 1020 
“ during hearing, 
1030 
Lachrymal appataius, 1004 
“ glai.ds, 1004 
Lact-album in, 437,476 
Lacteals, 365, 351 
Lactic acid, 466 
“ feiment, 306 
“ test for, 295 
Lactometer, 440 
Laetoprotein, 437 
Lactoscope, 440 
Lactose, 487 
Laevulose, 487 
Lagophthalmus, 758 
Lambert s method, 982 INDEX. 
Lieberkiihn’s jelly, 477 
Liebermann’s reaction, 475 
Liebig’s extract, 443 
Life, xliv 
Limbic lobe, 899 
Limb plexuses, 777 
Liminal intensity, 931 
Line of accommodation, 957 
Lines of separation, 996 
Ling’s system, 642 
Lingual nerve, 750 
Lipaemia, 57 
Lipochromes, 484 
Liquor sanguinis, 3, 34 
Lissauer's zone, 805 
Listing’s reduced eye, 951 
“ law, 993 
Liver, 318 
“ action of drugs on, 322 
“ bile-ducts, 322 
“ change in cells, 321 
“ chemical composition of, 
325 
“ cirrhosis of, 325 
“ development of, 1114 
“ diastatic ferment of, 328 
“ excision of, 325 
“ fat in, 329 
“ fatty degeneration of, 329 
“ functions of, 332 
“ glycogen in, 325 
“ glycogenic function, 327 
“ influence on metabolism, 
339 
“ invert ferment in, 329 
“ pathology of, 325 
“ portal vein, 318 
“ pulse in, 165 
“ regeneration of, 325 
“ structure of, 318 
Lobes of brain, 880 
Locality, sense of, 1049 
“ illusions of, 1051 
Local sign, 1052 
Lochia, 1123 
Locomotor ataxia, 818 
Long sight, 960 
Lordosis, 642 
Loss by skin, 228 
“ of weight, 457 
Lowe’s ring, 970 
Ludwig’s diaphragm experi- 
ment, 397 
Lungs, 185 
“ air-cells of, 189 
“ anatomical limits, 209 
“ atelectatic condition, 
215 
“ auscultation of, 201 
“ before birth, 215 
“ blood-vessels, T90 
“ chemistry of, 195 
“ color, 195 
“ contraction of, 194 
“ development of, 1113 
“ elastic tension of, 196 
Lungs, examination of, 201 
“ excision of, 195 
“ limits of, 209 
“ lymphatics of, 192 
“ nerves of, 194 
“ percussion of, 201, 209, 
211 
“ physical properties, 195 
“ pleura of, 191 
“ structure of, 185 
“ tonus, 194 
Lunule, 560 
Lutein, 484, 1075 
Luxus consumption, 450 
Lymph, 391 
“ chemistry of, 391 
“ follicles, 387 
“ glands, 387 
“ gases of, 230, 383 
“ hearts, 398 
“ movement of, 396 
“ of serous cavities, 393 
“ origin of, 395 
“ quantity of, 394 
“ spaces, 382 
Lymphatics, 379 
“ of eye, 945 
“ origin of, 382, 385 
“ structure of, 387 
Lymph-corpuscles, 391 
“ origin and decay of, 395 
396 
Macrocytes, 21 
Macropia, 742 
Macula lutea, 941 
Maculae acusticae, 1022 
Madder, feeding with, 469 
Magnetization of iron, 697 
Magneto-induction, 698, 700 
Major-chord, 1025 
Make induction shock, 697 
Makrostomia, 1105 
Malapterurus, 732 
Malt, 449 
Maltose, 261, 488 
Mammalia implacentalia, 1102 
“ placentalia, 1102 
Mammary glands, 433 
“ changes in cells, 434 
“ development of, 435 
“ structure of, 435 
Manometer, 139 
“ for ear, 1019 
“ hog, 96 
“ maximum, 69, 80 
“ minimum, 69, 80 
Manometric flames, 1030 
Marey’s sphygmograph, 115 
“ tambour, 79 
Margarin, 560 
Marginal convolution, 880 
Mariotte's experiment, 975 
“ law, 46 
Marrow of bone, 15 
Laminae dorsal es, 1088 
Lamina spiralis, 1020 
Language, 906 
Lanoline, 566 
Lanugo, 561, 563 
Lapping, 265 
Lardacein, 479 
Large intestine, 353 
“ absorption in, 
353 
Laryngoscope, 656 
Larynx, 651 
“ arrangement of, 650 
“ cartilages of, 650,651 
“ during respiration, 
657 
“ experiments on, 658 
“ illumination of, 656 
“ motor representation, 
890 
“ mucous membrane of, 
655 
“ muscles of, 652 
“ nerves of, 654 
“ picture of, 657 
“ sound produced in, 
658 
“ vocal cords, 652 
Latent heat, 402 
“ period, 609 
Lateral plates, 1092 
Laughing, 217 
Law of conservation of energy, 
xli 
“ contraction, 719 
“ isolated conduction, 725 
“ peripheral perception, 
1048 
“ specific energy, 931 
Leaping, 647 
Least perceptible difference, 
1057 
Lecithin, 675 
Leech extract, 38 
Legumin, 445, 479 
Leguminous seeds, 445 
Lens, chemistry of, 943 
“ crystalline, 943 
“ development of, 1120 
“ of eyeball, 943 
“ shadows, 969 
Lenticular nucleus, 911 
Leptothrix epidermalis, 571 
“ buccalis, 260 
Leucic acid, 486 
Leucin, 313, 489, 530 
Leucoblasts, 13 
Leucocytes, 382, 389 
“ formation of, 391 
Leucoderma, 735 
Leucomaines, 304 
Leukaemia, 21 
Levers, 640 
Lichenin,488 
Lieben’s test, 517 
Lieberkiihn’s glands, 345 INDEX. 
1145 
Massage, 642 
Mastication, 266 
“ muscles of, 266 
“ nerves of, 266 
Mate, 447 
Matter, xxxvi 
Maturation of ovum, 1080 
Meat soup, 443 
Meckel’s cartilage, 1105 
“ ganglion, 749 
Meconium, 344 
Medulla oblongata, 830 
functions of, 835 
gray matter of, 833 
reflex centres in, 835 
structure of, 830 
Medullary groove, 1086 
“ tube, 1090 
Meibomian glands, 1003 
Meiocardia, 102 
Meissner’s plexus, 279, 287, 
37 o 
“ touch corpuscles, 
1044 
Melanaemia, 21 
Melanin, 484 
Mellitsemia, 57 
Mellituria, 57 
Membrane capsulo-pupillaris, 
1120 
“ decidua, 1097 
“ flaccida, 1011 
“ reticularis, 1024 
“ reuniens, 1095 
“ secundaria, 1019 
“ tectoria, 1024 
“ tympani, 1011 
Membrane bones, 1104 
Membranes of brain, 925 
Meniere’s disease, 761 
Menopause, 1073 
Menstruation, 1073 
Mercurial manometer, 140 
Merkel’s cells, 1047 
“ corpuscles, 1046 
Meroblastic ova, 1070 
Mesentery, development of, 
1114 
Mesoblast, 1085, 1093 
Mesoderm, 1085 
Mesonephros, 1116 
Metabolism, 429 
“ during inanition, 
457 
“ equilibrium of, 449 
“ in anaemia, 58 
“ influence of work 
on, 455 
“ of tissues, 464 
“ on flesh diet, 458 
“ peptones, 459 
“ proteids, 458 
Metagenesis, 1060 
Metakresol, 516 
Metakinesis, 1088 
Metallic taste, 1043 
Metallic tinkling, 213 
Metalloscopy, 1057 
Metamorphosis, 1059 
Metanephros, 1116 
Metastatic thermometer, 406 
Meteorism, 288 
Methsemoglobin, 28 
Method of equivalents, 1049 
Methylamine, 489 
Methylene-blue, 674 
Methyl-violet test, 295 
Meynert’s projecting systems, 
822 
“ theory, 871 
Microcephalia, 867 
Micrococcus, 58 
“ ureae, 520 
Microcytes, 21 
Micropyle, 1067 
Micro-organisms in air, 237 
Microscope, 159 
Micro-spectroscope, 25 
Micturition, 553, 556 
“ centre for, 814 
Migration of ovum, 1080 
Milk, 434, 435 
“ acids on, 306 
“ action of drugs on, 440 
“ coagulation of, 437 
“ colostrum, 436 
“ composition of, 438 
“ curdling ferment, 296, 
299, 306 
“ digestion of, 305 
“ fever, 435, 1123 
“ globules of, 436 
“ how formed, 440 
“ peptonized, 318 
“ plasma, 437 
“ preparations of, 440 
“ proteids of, 437 
“ rennin on, 306 
“ substitutes for, 439 
“ sugar, 487 
“ tests for, 439 
Millon’s reagent, 475 
Mimetic spasm, 759 
Mimicry, 664 
Minor chord, 1025 
Mitosis, 14, 1087 
Mitral insufficiency, 82 
“ stenosis, 82 
Mixed colors, 982 
“ glands, 244 
Modiolus, X020 
Molecular basis of chyle, 392 
Molecules, xxxvi 
Molisch’s test, 263 
Monochromatic aberration, 962 
Monoplegia, 904 
Monospasm, 905 
Monotonia, 663 
Moore and Heller’s test, 263 
Morbus ceruleus, 1110 
Moreau’s experiment, 348 
Mormyrus, 731 
Morphology, xxxvi 
Morula, 1082 
Motion, illusions of, 988 
Motor areas of cerebrum, 882 
“ “ removal of, 892 
“ centres, dog, 882, 886 
“ excision of, 894 
“ ganglionic cells, 791 
“ in man, 891 
“ in monkey, 887 
“ nerves, 734 
“ paths, 825 
“ points on the surface, 
727, 729 
Mouth, 243 
“ glands of, 243 
Mouvements de manage, 919 
Movements of the eye, 991 
“ acquired, 893 
“ forced, 920 
“ inco-ordinated, 776 
Mucedin, 479 
Mucigen, 364 
Mucin, 480 
Mucous glands, 244 
Mucous membrane currents, 
705 
Mucous tissue, 945 
Mucus, 238, 524 
“ effect of drugs on, 238 
“ formation of, 238, 333 
Mulberry mass, 1082 
Mulder and Neubauer’s test, 
263 
Muller’s ducts, 1115 
“ experiment, 104 
“ fibres, 940 
“ valves, 219 
Multiplicator, 689 
Murexide test, 510 
Murmurs, cardiac, 87 
“ venous, 163 
Muscae volitantes, 969 
Muscarin, 851 
“ on heart, 98, 100 
Muscle, 576 
“ action of acids, 598 
“ action of stimuli on, 
603 
“ action of successive 
stimuli, 616 
“ action of veratrin, 614 
“ “ water, 598 
“ active changes in, 605 
“ arrangement of, 639 
“ atrophic proliferation 
of, 643 
“ atrophy of, 643 
“ blood-vessels of, 581 
“ cardiac, 60, 585 
“ changes during con- 
traction, 605 
“ chemical composition, 
589 
“ contraction, simple, 608 
“ curare on, 600 INDEX. 
Muscle current, 694 
“ cuive of, 607 
“ degenerations of, 643 
“ development of, 585 
“ effect of acids on, 598 
“ effect of cold on, 600 
“ effect of distilled water 
on,598 
“ effect of exercise on, 
642 
“ effect of heat on, 598 
“ elasticity of, 624 
“ electric currents of, 702 
“ excitability of, 600 
“ extractives of, 592, 594 
“ fatigue of, 615, 630 
“ ferments, 591 
“ fibrillae, 578 
“ formation of heat in,627 
“ gases in, 593 
“ glycogen in, 594, 596 
“ heart, 585 
“ hypertrophy of, 643 
“ involuntary, 576 
“ lymphatics of, 581 
“ metabolism in, 592 
“ myosin of, 590 
“ nerves of, 582 
“ nutrition of, 643 
“ of heart, 60, 585 
“ perimysium of, 576 
“ physical properties of, 
589 
“ plasma of, 590 
“ plate, 1095 
“ polarized light on, 589 
“ press, 708 
“ Purkinje’s fibres, 585 
“ reaction, 590, 593 
“ recovery of, 632 
“ red and pale, 585 
“ relation to tendons, 581 
“ rhythmical contraction, 
603 
“ rigor mortis of, 596 
“ rods, 580 
“ sensibility, 580, 627 
“ sensory nerves, 585 
“ serum of, 591 
“ smooth, 586 
“ sound of, 628 
“ spectrum of, 585 
“ spindles, 587 
“ staircase of, 618 
“ stimuli of, 603 
“ structure of, 576 
“ tetanus, 617 
“ tonicity of, 627, 815 
“ uses of, 639 
“ volume of, 605 
“ voluntary, 576 
“ work of, 622 
Muscle-albumin, 476 
Muscle-current— 
“ arrangement for, 
694 
Muscle-current theories, 713 
Muscles, diaphragm, 205 
“ intercostal, 206 
“ of eyeball, 994 
“ of respiration, 203 
Muscular contraction (see Myo- 
gram), 607 
“ action of successive 
stimuli, 616 
“ methods, 607 
“ rapidity of, 615 
“ rapidity of transmis- 
sion, 620 
Muscular energy, 595 
“ exercise, 223 
“ sense, 1057 
“ “ illusions of, 
1058 
“ tissue, 576 
“ work, 622 
“ “ laws of, 622 
“ “ relation to urea, 
594 
Musical notes, 1026 
“ effect of, 1033 
“ vibration curve of, 1028 
Mutes, 662 
Mydriasis, 742 
Mydriatics, 966 
Myelin forms, 669 
Myelospongium, 1119 
Myo-cardiograph, 72 
Myocardium, 60 
Myogram, 607, 609 
“ effect of constant 
current on, 614 
“ effect of fatigue on, 
613 
“ effect of poisons on, 
614 
“ effect of veratrin on, 
614 
“ effect of weights on, 
613 
“ method of studying, 
607 
“ stages of, 609, 610 
Myographs, 607 
“ analysis of, 607, 608 
Myohsematin, 585 
Myopia, 959 
Myoryctes Weismanni, 589 
Myosin, 590 
“ ferment, 591 
Myosinogen, 477 
Myosis, 742 
Myotics, 966 
Myxcedema, 179, 735 
Nails, 560 
Narcotics, 1057 
Nasal breathing, 215 
“ timbre, 660 
Nasmyth’s membrane, 268 
Native albumins, 476 
Natural selection, 1124 
Near point, 958 
Neef’s hammer, 700 
Negative accommodation, 954 
“ after-images, 988 
“ pressure, 372 
“ variation, 705 
“ “ in cord, 709 
“ “ in nerve, 
709 
“ “ velocity of, 
709 
Nephrozymose, 517 
Nerve-cells, 666 
“ bipolar. 673 
multipolar, 672 
“ of cerebrum, 874 
“ Purkinje’s, 921 
“ size of, 794 
“ unipolar, 674 
“ with capsules, 674 
“ with spiral fibres, 674 
Nerve centres, general func- 
tions, 785 
Nerve current, 702 
“ arrangement for, 694 
Nerve-fibres, 666 
“ action of nitrate of silver 
on,671 
“ axis cylinders of, 668 
“ chemical composition of, 
674 
“ classification of, 734 
“ constant current in, 679 
“ death of, 686 
“ degeneration of. 683 
“ development of, 672 
“ division of, 671 
“ effect of a constant cur- 
rent on,679 
“ electrical current of, 702 
“ “ stimuli, 679 
“ excitability of, 676 
“ fatigue of, 683 
“ Frommann’s lines, 669 
“ incisures of, 670 
“ mechanical properties of, 
676 
“ medullated, 666, 669 
“ metabolism of, 676 
“ fibres, myelin of, 669 
“ neurilemma, 670 
“ neuro-keratin sheath, 
671 
“ non-medullated, 666 
“ nutrition of, 682 
“ Ranvier’s nodes, 670 
“ reaction of, 675 
“ recovery of, 683 
“ regeneration of, 684 
“ Remak’s, 666 
“ rigor, 675 
“ sheaths of, 671 
“ size of, 671, 794 
“ stimuli of, 676 
“ structure of, 666 INDEX. 
Nerve-fibres, suture of, 685 
“ terminations of, 1044 
“ to glands, 252 
“ transplantation of, 685 
“ traumatic degeneration 
of, 684 
“ trophic centres for, 685 
“ unequal excitability of, 
680 
“ union of, 685 
“ unipolar stimulation, 681 
Nerve-impulse, rate of, 722 
“ method of measuring, 
723 
“ modifying conditions, 
722 
Nerve-motion, 678 
Nerve-muscle preparation, 704 
Nerves, 734 
“ afferent, 736 
“ anabolic, 736 
“ centrifugal, 734 
“ centripetal, 736 
“ classification of, 734 
“ cranial, 737 
“ development of, 1120 
“ double conduction in, 
724 
“ efferent, 734 
“ electrical, 736 
“ excito-motor, 736 
“ inhibitory, 736 
“ intercentral, 737 
“ isolated conduction, 725 
“ katabolic, 736 
“ motor, 734 
“ peripheral, 734 
“ reflex, 736 
“ secretory, 734 
“ sensory, 736 
“ special sense, 736 
“ spinal, 772 
“ thermic, 736 
“ trophic. 734 
“ union of, 684 
“ vaso dilator, 863 
“ vaso motor, 854, 856 
“ visceral, 736 
Nerve-stretching, 677 
Nervi erigentes, 864, 1077 
“ nervorum, 672 
Nervous impulse, 722 
“ transmission of, 722 
“ velocity of, 723 
Nervous sy.-tem — 
“ formation of, 1118 
Nervus abducens, 755 
“ accelerans, 851 
“ accessorius, 771 
“ acusticus, 759 
“ depressor, 766 
“ facialis, 755 
“ glosso-pnaryngeus, 762 
“ hypoglossus, 772 
“ oculomotorius, 741 
“ olfactorius, 737 
| Nervus opticus. 738 
“ sympathicus, 777 
“ trigeminus, 744 
“ trochlearis, 743 
“ vagus, 763 
| Neubauer’s test, 263 
Neumann’s corpuscles, 20 
I Neuralgia, 1057 
j Neural groove, ic88 
“ tube, 1088 
Neurasthenia gastrica, 357 
Neuroblasts, 1119 
Neuro-epithelium, 941 
Neuroglia, 795 
Neuro-keratin, 674 
“ sheath, 671 
Neuro muscular cells, 603 
1 Neutral fats, 485 
| New-born child, digestion of, 
300 
“ pulse, 126 
“ size, 470 
“ temperature, 414 
“ urine of, 500 
“ weight, 471 
[ Nicotin on sub-maxillary gang- 
lion, 752 
: Nictitating membrane, 1006 
Nitrites, 28 
| “ on pulse, 124 
Nitrogen estimation, 50 
“ in air, 219 
“ in blood, 54 
“ given off, 450 
| Noeud vital, 838 
j Noises, 1024 
Non-polarizable electrodes, 691, 
694 
Nose, development of, 1121 
“ structure, 1035 
Notochord, 1091 
Nuclear spindle, 1080, 1087 
Nuclein, 480 
Nucleo-albumins, 482 
Nucleo-plasm, 1087, 
Nucleus, structure of, 1087 
“ of Pander, 1071 
Number-forms, 1034 
Nussbaum’s experiments, 540 
Nutrient enemata, 379 
Nyctalopia, 714 
Nystagmus, 919 
Oatmeal, 445 
Oblique illumination, 973 
Octave, 1025 
Ocular muscles, 994 
Oculomotorius, 741 
Odontoblasts, 268 
(Edema, 399 
“ cachectic, 400 
“ pulmonary, 216 
(Esophagus, 279 
Ohm’s law, 688 
1 Oleic acid, 486 
Olfactory bulb, 1036 
“ cells, 1035 
“ centre, *<98 
“ nerve, 737 
“ path, 898 
“ sensations, 1038 
“ tract, 1036 
Oligaemia, 57 
Oligocythaemia, 58 
Olivary body, 830 
Omphalo-mestnteric duct,1093 
“ “ vessels, 
1094 
Oncograph, 175 
Oncometer, 175 
“ for kidneys, 546 
Onomatopoesy, 664 
Ontogeny, 1124 
Opening shock, 697 
Ophthalmia neuio paralytica, 
748 
“ intermittens, 748 
“ sympathetic, 748 
Ophthalmic nerve, 745 
Ophthalmometer, 952 
Ophthalmoscope, 970 
Ophthalmotrope, 995 
Opisthotonos, 807 
Optic chiasma, 738 
“ nerve, 738, 969 
“ radiation, 738, 916 
“ thalamus, 912 
“ tract, 738 
“ vesicle, 1091 
Optical cardinal points, 949 
Optogram, 980 
Optometer, 960 
Ordinates, 141 
Organic acids, 484 
“ albumin, 458 
“ compounds, 473 
“ reflexes, 812 
Organisms in blood, 58 
Organ of Jacobson, 1036 
Ortho-kresol, 516 
Orthopncea, 202 
Orthoscope, 973 
Osmasome, 443 
Ossein, 481 
Osseous system, formation of, 
1103 
Osteoblasts, 1108 
Osteoclasts, 1108, 1109 
Osteomalacia, 642 
Otic ganglion, 751 
Otoliths, 1022, 1024 
Outlying cells of cord, 792 
Ova holoblastic, 1070 
“ meroblastic, 1070 
“ primordial, 1068 
Ovarian tubes, 1068 
Ovaries, formation of, 1116 
Ovary, 1067 
Overcrowding, 237 
Over-maximal stimulation, 680 
Ovulation, 1074 INDEX. 
Ovulation, theories of, 1075 
Ovum, 1067 
“ development of, 1068 
“ discharge of, 1075 
“ fertilization of, 1079 
“ impregnation of, 1080 
“ maturation of, 1080 
“ structure of, 1067 
“ tubal migration of, 1080 
Oxalic acid, 486, 512 
“ series, 486 
Oxaluria, 512, 
Oxaluric acid, 512 
Oxidation in blood, 230 
“ tissues, 229 
Oxy-acids, 516 
Oxyakoia, 758 
Oxygen in blood, 51 
“ estimation of, 50, 218 
“ forms of, 53 
Oxyhsemoglobin, 25, 51 
Ozone in blood, 52 
Pacchionian bodies, 926 
Pacini’s corpuscles, 1045 
“ fluid, 8 
Pain, 1056 
“ irradiation of, 1056 
“ spots, 1049 
Painful impressions, conduction 
of, 818 
Palmitic acid, 485 
Palpitation, 70 
Pancreas, 308 
“ action of, 312 
“ “ on fat,-3x5 
“ artificial digestion, 
314 
“ changes in cells, 309 
“ chemistry of, 310 
“ comparative, 312 
“ development of,1114 
“ diastatic action, 312 
“ effect of nerves and 
drugs on, 316 
“ excision of, 316 
“ extracts of, 315 
“ fistula of, 311 
“ juice of, 310 
“ milk-curdling fer- 
• ment, 316 
“ paralytic secretion, 
316 
“ powder, 314 
“ proteolytic action, 
312 
“ putrefactive phen- 
omena, 313 
“ -salt, 316 
“ secretion of, 316 
“ structure of, 308 
Panophthalmia, 747 
Pansphygmograph, 71, 117 
Papain, 315 
Papilla foliata, 1042 
Papillae of tongue, 1040 
Papillary muscles, 72 
Parablastic cells, 1092 
Paradoxical contraction, 712 
Paraglobulin, 41, 44, 477 
Para haemoglobin, 28 
Parakresol, 516 
Paralgia, 1057 
Paralytic secretion of saliva, 
255 
“ pancreatic juice, 316 
Paramylum, 488 
Para-oxyphenylacetic acid, 489 
Para-peptone, 301 
Para-peptones, 303 
Paraphasia, 906 
Paraxanthin, 489 
Parelectronomy, 713 
Paridrosis, 571 
Paroophoron, 1116 
Parotid gland, 256 
Parovarium, 1115 
Parthenogenesis, 1061 
Partial cleavage of yolk, 1091 
“ pressure, 47 
“ reflexes, 806 
Particles, xxxvi 
“ absorption of, 376 
Parturition, centre for, 815 
Passive insufficiency, 641 
Patellar reflex, 813 
Pavy’s test, 263 
Pecten, 1006 
Pectoral fremitus, 213 
Pedunculi cerebri, 916 
Penis, 1076 
“ erection of, 1076 
Pepsin, 294, 301 
“ where formed, 297 
Pepsinogen, 297 
Peptic glands, 292 
“ changes in, 298 
Peptic products, absorption of, 
300 
Peptogenic substances, 300 
Peptone, 302, 303, 478 
“ -forming ferment, 296 
“ injection of, 37, 375 
“ metabolism of, 459 
“ tests for, 303 
Peptones, absorption of, 374 
“ on blood, 37 
Peptonized foods, 317 
“ gruel, 318 
“ milk, 318 
Peptonizing powders, 318 
Peptonuria, 524 
Percussion-hammer, 209 
Percussion of heart, 89 
“ lungs, 209 
“ sounds, 211 
“ wave, 120 
Perforating ulcer of the foot, 
736 
Pericardium, 63 
“ fluid of, 63 
Perilymph, 1021, 1024 
Perimeters, 978 
Perimetric chart, 979 
Perimetry, 978 
Perimysium, 60, 576 
Perineurium, 672 
Periodontal membrane, 269 
Periosteum, 634 
Peripheral end-organ, 734 
Peristalsis, 283 
Peristaltic movements, 273 
“ action of blood on, 
287 
“ action of nerves on, 
289 
Peritoneum, development of, 
1114 
Perivascular spaces, 385 
Pernicious anaemia, 21 
Pes cerebri, 916 
Pettenkofer’s test, 334 
Pettenkofer’s apparatus, 220 
Peyer's glands, 369 
“ patches, 369 
Pfliiger’s gas-pump, 47 
“ law, 716, 718 
“ law of reflexes, 808 
Phagocytes, 19 
Phakoscope, 956 
Phanakistoscope, 988 
Pharyngeal plexus, 764 
Pharynx, 273 
Phases, displacement of, 1028 
Phenol, 352, 487, 489, 515 
Phenol-sulphuric acid, 515 
Phenol-hydrazin test, 264, 528 
Phlebogram, 164 
Phloridzin-glycosuria, 331 
Phloro-glucin-vanillin, 295 
Phonation, 654 
Phonograph, 1030 
Phonometry, 212 
Phosphenes, 969 
Phosphoric acid, 518 
Photo-haematachometer, 155 
Photophobia, 759 
Photopsia, 741 
Phrenic nerve, 205 
Phrenograph, 199 
Phrenological doctrine, 868 
Phylogeny, 1124 
Physostigmin, 966 
Phytalbumose, 479 
Phytomycetes, 532 
Pia mater, 786 
Picric acid test, 523, 528 
Picro-saccharimeter, 529 
Pigment cells, 574, 575 
Pinces myographiques, 620 
Pineal eye, 1006 
“ gland,920 
Piotrowski’s reaction, 475 
Pitch, 1025 
Pituitary body, 182, 920 
Placenta, 1097, 1098 
preevia, 1100 
Placental limit, 163 INDEX. 
Planes of separation, 992 
Plantar reflex, 812 
Plants, characters of, xliii 
“ digestion by, 360 
“ electrical currents in, 
716 
Plasma cells, 384 
“ fibrin, 44 
“ invertebrate, 45 
“ of blood, 3, 34 
“ of lymph, 391 
“ of milk, 437 
“ of muscle, 590 
“ proteids of, 44 
Plasmine, 40 
Plattner’s bile, 334 
Plethora, 56 
Plethysmography, 166 
Pleura, 191 
“ absorption by, 194 
Pleural friction, 213 
Pleuro-peritoneal cavity, 1092 
Pleximeter, 209 
Plexus myentericus, 287 
Plexuses, 773 
“ limb, 773 
Pneumatic cabinet, 131 
Pneumatogram, 201 
Pneumatometer, 215 * 
Pneumograph, 199 
“ cardiac, 102 
Pneumonia after section of vagi, 
768 
Pneumothorax, 196 
Poikilothermal animals, 405 
Points douloureux, 1057 
Poiseuille’s space, 160 
Poisons on heart, IOO 
Polar globules, 1081 
Polarization, galvanic, 691 
“ internal, 695 
“ of electrodes, 691 
“ of nerve, 712 
Polarizing after-currents, 712 
Politzer’s ear-bag, 1019 
Polyaemia, 56 
“ apocoptica, 56 
“ aquosa, 56 
“ hyperalbuminosa, 56 
“ polycythaemica, 56 
“ serosa, 56 
Polygraphs, 72 
Polyopia monocularis, 964 
Pons varolii, 917 
Porret’s phenomenon, 589 
Portal canals, 319 
“ circulation, 59 
“ system, development of, 
1112 
“ vein in liver, 318 
“ “ ligature of, 151 
“ “ tonus of, 863 
Positive accommodation, 954 
“ after-images, 988 
Posterior longitudinal bundle, 
916 
Potash salts, 472 
Potassium chloride, 472 
“ sulphocyanide, 516 
Potatoes, 445 
Precordial pulsation, 71 
Presbyopia, 960 
Preserved vegetables, 446 
Pressor fibres, 857 
Pressure, arterial, 143 
“ atmospheric, 240 
“ intra - labyrinthine, 
1024 
“ of blood, 139 
“ phosphenes, 969 
“ points, 1052 
“ respiratory, 214 
“ sensation of, 1048, 
1056 
“ sense, 1052 
Presystolic sound, 87 
Prickle cells, 558 
Primary cerebral vesicles, 1090 
Primitive anus, 1096 
“ aortse, 1094 
“ chorion, 1085 
“ circulation, 1094 
“ groove, 1085 
“ kidneys, 1114 
“ mouth, 1096 
“ streak, 1085 
Primordial cranium, 1104 
“ ova, 1068 
Principal focus, 947 
Proctodseum, 1086 
Proglottides, 1060 
Progressive muscular atrophy, 
735 
Projection systems, 822 
Pronephros, 1116 
Pronucleus, male, 1081 
“ female, 1081 
Propepsin, 297 
Propeptone, 301 
Prostatic fluid, 1064 
Protagon, 484, 674 
Protective apparatus of brain, 
925 
Proteids, 473 
“ animal, 476 
“ coagulated, 478 
“ coagulation of, 476 
“ constitution of, 476 
“ electrolysis of, 474 
“ fermentation of, 351 
“ gastric digestion of, 
3or 
“ metabolism of, 458 
“ pancreatic digestion 
of, 3*4 
“ poisonous, 480 
“ reactions of, 474 
“ tests for, 475 
“ vegetable, 479 
Proteolytic ferments, 482 
Proteoses, 302, 477 
Protistae, xxxv, xliv 
Proto-albumose, 302, 478 
Protovertebrse, 1092 
Pseudo-hypertrophic paralysis, 
735 
Pseudo-motor action, 756 
Pseudoscope, 1001 
Pseudo stomata, 190 
Psychical activities, 867 
“ blindness, 896 
“ deafness, 897 
“ processes, time of 
.871 
Psycho-physical law, 931 
Ptomaines, 304 
Ptosis, 742 
Ptyalin, 262 
Ptyalism, 260, 262 
Puberty, 1073 
Puerile breathing, 213 
Pulmonary artery, 190 
“ “ nerve plex- 
uses, 194 
“ “ pressure in, 
I5i 
“ nervous system on, 
153 
“ veins, 191 
“ vessels, 190 
“ oedema, 216 
Pulmonic circulation, 59 
“ capacity of, 139 
Pulp of tooth, 269 
“ of spleen, 171 
Pulsatile phenomena, 134 
Pulse, 115 
“ anacrotic, 128, 129 
“ brain, 135 
“ capillary, 138 
“ catacrotic, 119 
“ characters of, 126 
“ conditions affecting, 126 
“ curve, 119 
“ dicrotic, 125 
“ dicrotic wave, 121 
“ ent optical, 134 
“ hard, 123 
“ hyperdicrotic, 125 
“ in animals, 127 
“ in jugular vein, 165 
“ in liver, 165 
“ influence of pressure on, 
132 
“ influence of respiration 
on,130 
“ instruments for investi- 
gating, 115 
“ methods of investigating, 
”5 
“ monocrotic, 125 
“ Muller’s experiment on, 
*3* 
“ of various arteries, 128 
“ paradoxical, 132 
“ pathological, 135 
“ rate, 126, 148 
“ recurrent, 129 INDEX. 
Pulse, retinal, 165 
“ soft, 123 
“ sphygmogram, 119 
“ tracing, 119 
“ tricotism, 128 
“ trigeminal, 127 
“ Valsalva’s experiment 
on,131 
“ variations in, 126 
“ venous, 164 
“ waves, 133 
“ “ velocity of, 133 
Pulses, 445 
Pulsus alternans, 127 
“ bigeminus, 127 
“ caprizans, 125 
“ dicrotus, 121 
“ intercurrens, 127 
“ myurus, 127 
“ paradoxus, 132 
“ quadrigeminus, 127 
“ trigeminus, 127 
Pumping mechanisms, 397 
Punctum proximum, 958 
“ remotum, 958 
Pupil, 956, 957 
“ action of drugs on, 966 
“ Argyll Robertson, 965 
“ functions of, 964 
“ movements of, 965 
“ photometer, 967 
“ size of, 967 
Pupilometer, 967 
Purgatives, 289, 290 
Purkinje, cells of, 922 
“ fibres of, 64 
“ figure, 969 
“ Sanson’s images, 955 
Pus-corpuscles, 161 
Putrefaction, pancreatic, 313 
Putrefactive processes, 353 
Pyloric glands, 296 
“ changes in, 298 
“ fistula, 298 
Pyramidal cells, 876 
“ paths, degeneration 
of, 903 
“ tracts, 800, 804 
“ “ degeneration 
of. 903, 
Pyrocatechin, 487, 489, 516 
Pyuria, 531 
Quality of a tone, 1025, 1027 
“ perception of, 1027 
Quantity of blood, 55 
“ of food, 451 
“ of gases, 221 
Radiation from skin, 418 
Raia batis, 732 
Rales, 213 
“ moist, 213 
Ramus communicans, 778 
Range of accommodation, 961 
Ranvier’s nodes, 670 
Raynaud’s disease, 736 
Reaction impulse, 74 
“ of degeneration, 683 
729, 730 
“ time, 872 
Recoil wave, 121 
Rectum, 289 
Recurrent pulse, 129 
“ sensibility, 774 
Red marrow, 13 
Red-blindness, 986 
Reduced alkali-hsematin, 30 
“ eye of Listing, 951 
“ haemoglobin, 27 
Reducing agents, 52 
Reductions in intestine, 353 
Reflex action, 805, 806 
“ influence of drugs on, 
810 
“ inhibition of, 809 
“ in mammals, 808 
“ movements, 805 
“ PfKiger’s law of, 808 
“ theory of, 811 
“ nerves, 736 
“ spasms, 806 
“ tactile, 818 
“ time, 809 
“ tonus, 815 
Reflexes, co-ordinated, 808 
“ crossed, 808 
“ deep, 812 
“ organic, 812, 814 
“ spinal, 805, 812 
“ superficial, 812 
“ tendon, 812 
“ varieties of, 806 
Refracted ray, 948 
Refraction, anomalies of, 958 
Refractive indices, 948 
Regeneration of tissues, 466 
“ of nerve, 684 
Regio olfactoria, 1035 
“ respiratoria, 1035 
Regnault and Reiset’s appa- 
ratus, 219 
Regulation of respiration, 847 
Reissner’s membrane, 1020 
Relative proportions of diet, 
45 2 
Remak’s ganglion, 92 
Renal plexus, 544 
Rennet, 296, 299, 306, 438 
Rennin, 296, 299, 306, 438 
Reproduction, forms of, 1059 
Reproductive organs, develop- 
ment of, 1115 
Requisites in a proper diet, 451 
Reserve air, 196 
“ pleural space, 210 
Residual air, 196 
Resistance in tubes, 105, 106 
Resonants, 662 
Resonators, 649, 1028 
Resorcin, 516 
Respiration, 185 
Respiration, abdominal type, 
200 
“ amphoric, 216 
“ apparatus, 218, 
219 
“ appendix to, 215 
“ artificial, 235 
“ Biot’s, 203 
“ bronchial, 212 
“ centre for, 837 
“ chemistry of, 217 
“ Cheyne - Stokes’, 
202 
“ cog-wheel, 213 
“ comparative, 222, 
231 
“ costal, 200 
“ cutaneous, 228, 
565 
“ diaphragmatic 
type, 200 
“ effect of first, 215 
“ “ of, on blood, 
226 
“ expiration, 195, 
204 
“ first, 847 
“ forced, 200, 214 
“ gases, 196, 221 
“ in a closed space, 
232 
“ in animals, 198 
“ in limited space, 
232 
“ inspiration, 195, 
203 
“ internal, 228 
“ mechanism, 195 
“ modified acts, 216 
“ muscles of, 203 
“ nasal, 215 
“ number of, 197 
“ of foreign gases, 
236 
“ pathological, 213 
“ periodic, 203 
“ pressure during, 
214 
“ quotient, 221, 231 
“ sounds of, 212 
“ time occupied by, 
199 
“ type of, 200 
“ vesicular, 212 
Respiratory apparatus, 218, 
219 
“ action of blood ,839 
“ action of drugs 
on, 848 
“ Andral and Ga- 
varret, 219 
“ centre, 837 
“ effect of muscular 
work, 840 
“ effect of nerves, 
841 INDEX. 
Respiratory effect of section of j 
vagi, 838, 842 
“ excitants, 224 
“ apparatus, mechan- 
ism of, 195 
“ v. Pettenkofer, 220 
“ position, 837 
“ pressure on heart, 
io3 
“ quotient, 221, 231 
“ Regnault and Rei- 
set, 219 
“ Scharling, 219 
“ undulations, 144 
Restiform body, 830 
Resuscitation, 236 
Rete mirabile, 59 
Retina, 939 
action of light on, 965 
“ activity in vision, 974 | 
“ blood-vessels of, 941 
“ capillaries, movements 
in, 969 
“ chemistry of, 943 
“ epithelium of, 942 
“ formation of image on, 
951 
“ rods and cones of, 942, 
976 ' 
“ stimulation of, 980,987 | 
“ structure of, 939 
“ visual purple of, 942 
“ currents, 710 
Retinal image, formation of, 951 
“ pulse, 165 
“ size of, 952 
Retinoscopy, 973 
Retro-lingual gland, 249 
Reversion, 1124 
Rheocord, 688 
Rheometer, 154 
Rheophores, 726 
Rheoscopic limb, 704 
Rheostat, 689 
Rheotome, 709, 711 
Rhinoscopy, 658 
Rhodophane, 943 
Rhodopsin, 942, 943 
Rhonchi, 213 
Ribs, elevation, 206 
Rickets, 642 
Rigid tubes, 108 
Rigor mortis, 596, 599 
Ritter’s law of contraction, 718 
“ opening tetanus, 719,722 
Ritter-Valli law, 686 
Rods and cones, 942, 976 
“ movements of, 980 
Rods of Corti, 1023 
Rosenthal’s modification, 602 
Rotatory disc for colors, 982 
Rudimentary organs, 1124 
Rumination, 360 
Running, 647, 
Saccharimeter, 264 
Saccharomycetes, 448 
Saccharose, 488 
Saccule, 1020 
Saccus endolymphaticus, 1022 
Saftcanalchen 192 
Saline cathartics, 291 
Saliva, action of nerves on, 252 
“ action of drugs on, 254 
“ action on starch, 261 
“ actions of, 260 
“ chorda, 253 
“ composition of, 259 
“ effect of tea, 263 
“ functions of, 261 
“ mixed, 259 
“ of infants, 260 
“ organisms in, 260 
“ paralytic secretion, 233 
“ parotid, 258 
“ pathological, 257, 356 
“ ptyalin, 258, 260 
“ reflex secretion of, 256 
“ secretion of, 252 
“ sublingual, 259 
“ submaxillary, 258 
“ sympathetic, 253 
“ theory of secretion, 258 
Salivary calculi, 258 
“ corpuscles, 259 
“ glands, 247 
“ “ atropin on, 254 
“ “ development of, 
1113 
“ “ extirpation of, 
. 255 
“ “ histological 
changes in, 250 
“ “ nerve of, 251 
Salted plasma, 35 
Salts, 472 
“ absorption of, 372 
“ in body, 472 
“ injected into blood, 55 
Sanson-Purkinje’s images, 955 
Santonin, 987 
Sapidity, 452 
Saponification, 315 
Sarcina ventriculi, 358 
Sarcoglia, 583 
Sarcolactic acid, 486 
Sarcolemma, 578 
Sarcolytes, 178, 585 
Sarcoplasts, 178, 585 
Sarcous elements, 577 
Sarkin, 489 
Sarkosin, 489 
Saviotti’s canals, 310 
Scala tympani, 1020 
“ vestibuli, 1020 
Scharling’s apparatus, 219 
Scheiner’s experiment, 958 
Schemata of circulation, 138 
Schiff’s test, 510 
Schizomycetes, 58 
Schmidt’s researches on blood, 
40 
Schreger’s lines, 268 
Schwann’s sheath, 670 
Sclerotic, 936 
Scolex, 1061 
Scoliosis, 642 
Scotoma, 979 
Screw-hinge joint, 637 
Scrotum, formation of, 1116 
Scurvy, 57 
Scyllit, 488 
Sebaceous glands, 564. 
“ secretion, 566 
Seborrhoea, 571 
Secondary circulation, 1094 
“ contraction, 708 
“ “ from a nerve, 712 
“ decompositions, 691 
“ degeneration, 799 
“ optic vesicle, 1120 
“ tetanus, 708 
Secretion current, 711 
glands, 246 
Secretory nerves, 734 
“ pressure, 255 
Sectional area, 154 
Segmentation spheres, 5, 1082 
Self-stimulation of muscle, 704 
Semen, composition of, 1064 
“ emission of, 1078 
“ reception of, 1078 
Semi-circular canals, 760, 1022 
‘‘ effects of section 
of, 761 
“ kinetic theory, 
761 
“ statical theory, 
760 
Sensation, 931 
Sense organs, 931 
“ development of, 1120 
Sensory cerebral centres, 895 
“ crossway, 828 
“ decussation in cord, 
S29 
“ paths to brain, 826 
“ sensations, 1048 
Serin, 489 
Serosity, 393 
Serous cavities, 386 
“ glands, 243 
Serum, extraction of, 46 
“ fats of, 45, 46 
“ of blood, 36 
“ poisonous, 46 
“ proteids of, 45 
Serum-albumin, 45, 476 
Serum-casein, 44 
Serum-globulin, 40, 44, 477 
Setschenow’s inhibitory centre, 
810 
Sex, cause of difference of, 1117 
Sexual reproduction, 1059 
Shadows, lens, 969 
“ colored, 990 
Sharpey’s fibres, 1109 
Short-sightedness, 959 
Shunt, 695 
Sialogogues, 257 
Siegle’s speculum, 1012 INDEX. 
Sighing, 217 
Silver lines, no 
“ nitrate, no 
Simple colors, 982 
Simultaneous contrast, 989 
Sinuses, x 11 
Sitting, 645 
Size, 470 
“ estimation of, 1001 
“ increase in, 470 
“ false estimate of, 1003 
Skate, 732 
Skatol, 313, 352,489, 516 
Skin, 557 
“ absorption by, 571 
“ coriumof, 558 
“ comparative, 572 
“ currents of, 705 
“ epidermis, 557 
“ functions of, 565 
“ galvanic conduction of, 
571 
“ glands of, 564 
“ historical, 572 
“ loss by, 228 
“ pigments, 568 
“ ■ protective covering, 565 
“ respiration by, 565 
“ structure of, 5 1,7 
“ varnishing the, 556 
Skull, formation of, 1104 
Sleep, 872, 873 
Small intestine, 362 
“ absorption by, 
370 
“ blood-vessels of, 
369 
“ structure of, 
362 
Smegma, 556 
Smell, sense of, 1035 
Smooth muscle, 586 
Sneezing, 216 
Snellen’s types, 960 
Sniffing, 1038 
Snoring, 217 
Soaps injected into blood, 376 
Sodium chloride, 472 
“ carbonate, 472 
“ phosphate, 472 
“ salts, 472 
Solar plexus, 782 
Solitary follicles, 368 
Soluble albumin, 476 
Somatopleure, 1092 
Somnambulism, 871 
Sorbin, 488 
Sound,1009 
“ cardiac, 79 
“ conduction to ear, 1019 
“ direction of, 1033 
“ distance of, 1034 
“ perception of, 1033 
“ reflection of, 1009 
Sounds, cardiac, 84 
“ causes, 84 
“ cracked pot, 211 
Sounds, respiratory, 213 
“ tympanitic, 211 
“ variations, 87 
“ vesicular, 212 
Soup, 443 
Spasm centre, 866 
Spasmus nictitans, 759 
Speech, comparative, 664 
“ historical, 665 
Specific energy, 980 
“ heat, 411 
Spectacles, 961, 1007 
Spectra, absorption, 25 
“ flame, 25 
Spectroscope, 25 
Spectrum mucro-lacrimale, 968 
“ ofbile, 336 
“ of blood, 26 
“ of muscle, 585 
Speculum for ear, 1011 
Speech,660 
“ centre for, 905 
“ conditions for, 906 
“ motor tract for, 905 
“ pathological variations, 
663 
Spermatin, 1064 
Spermatozoa, 1064 
Spermatoblasts, 1065 
Spermatogonia, 1066 
Sperm-cells, 1059 
Spheno-palatine ganglion, 749 
Spherical aberration, 962 
Sphincters, 639 
Sphincter ani, 284 
“ pupillse, 937 
“ urethrae, 552 
Sphygmogram, 119 
Sphygmograph, 115 
“ Dudgeon’s, 116 
“ Ludwig’s, 117 
“ Marey’s, 115 
Sphygmomanometer, 142 
Sphygmometer, 115 
Sphygmoscope, 119 
Sphygmotonometer, 113 
Spina bifida, 925, 1095 
Spinal accessory nerve, 771 
“ action of blood and 
drugs on, 816 
“ ascending tracts, 803 
“ anterior root of spinal 
nerve, 792 
“ blood-vessels of, 796 
“ Cayal on, 797 
“ central ependyma, 795 
“ centres in, 814 
“ column of Clarke, 790, 
791, 801 
•“ conducting paths in, 799, 
802, 817 
“ conducting system of, 
799 
Spinal cord, 786 
“ degenerations in, 799, 
802 
“ development of, 1119 
Spinal cord, development of 
tracts, 805 
“ direct cerebellar tract, 
801, 804 
“ excitability of, 815 
“ functions of, 799 
“ ganglion, 772, 773 
“ gelatinous substance of 
Rolando, 796 
“ Golgi on, 797 
“ Gowers’ tract, 805 
“ gray matter of, 792 
“ intermedio-lateral tract, 
791 
“ Lissauer’s zone, 805 
“ membranes of, 786 
“ motor-cells, 791 
“ nerve-cells of, 790 
“ nerve-roots, functions of, 
774, 776 
“ nerves, 772 
“ neuroglia of, 795 
“ outlying cells of, 792 
“ posterior root of spinal 
nerve, 793 
“ pyramidal tracts of, 799 
“ reflexes, 805 
“ regeneration of, 866 
“ secondary degeneration 
of, 802 
“ segment of, 806, 828 
“ sensory decussation ih, 
829 
“ structure of, 786 
“ time of development,805 
“ transverse section of, 
819 
“ trophic centres in, 802 
“ unilateral section of, 820 
“ vaso motor centres in, 
862 
“ WoroschilofF’s observa- 
tions, 789 
Spinal ganglia, development of, 
1119 
Spinal nerves, 772 
“ anterior roots of, 772, 
776 
“ experiments on, 683 
“ posterior roots of, 772, 
. . 777 
Spiral joints, 638 
Spirillum, 58 
Spirochasta, 58, 349 
Spirometer, 197 
Splanchnic area, 861 
“ nerve, 289 
Splanchnopleure, 1092 
Spleen, 170 
“ action of drugs on, 177 
“ chemical composition, 
173 
“ contraction of, 174 
“ extirpation of, 173 
“ functions of, 173 
“ influence of nerves on, 
171 INDEX. 
1153 
Spleen oncograph, 175 
“ regeneration of, 174 
“ structure, 170 
“ tumors of, 177 
Splenic reagents, 174 
Spongin, 481 
Spongioblasts, 1119 
Spontaneous generation, 1059 
Spores, 349 
Spring kymograph, 141 
“ myograph, 608 
Springing, 647 
Sputum, 238 
“ abnormal, 240 
“ normal, 239 
Squinting, 742 
Staircase, 618 
“ pulsations, 95, 100 
Stammering, 664 
Standing, 643 
Stannius’s experiment, 94 
Stapedius, 1016 
Starch, 488 
“ and saliva, 261 
Starvation, 456 
Stasis, 161 
Statical theory of Goltz, 760 
Stationary waves, 1010 
Steapsin, 315 
Stenopaic spectacles, 962 
Stenosal murmur, 163 
Stenosis, 82 
Stenson’s experiment, 597 
Stercobilin, 355 
Stercorin, 355 
Stereoscope, 999, 1000 
Stereoscopic vision, 998 
Sternutatories, 217 
Stethographs, 199 
Stethoscope, 212 
Stigmata, 110 
Stilling, canal of, 945 
Stimuli, 599, 603, 604 
“ adequate, 931 
“ heterologous, 931 
“ homologous, 931 
“ muscular, 603 
Stoffwechsel, xliv 
Stomach, 280 
“ action of drugs, 300 
“ cancer of, 357 
“ catarrh of, 357 
“ changes in glands,296 
“ exclusion of, 305 
“ formation of acid, 29S 
“ formation of pepsin, 
297 
“ gases in, 308 
“ glands of, 293 
movements of, 280 
“ nerves of, 280 
“ non-digestion of, 307 
“ structure of, 291 
Stomata, 110, 386 
Stomodseum, 1086 
Storage albumin, 451 
Strabismus, 919 
Strangury, 556 
Strassburg’s test, 527 
Striae medullarcs, 914 
Strobic discs, 988 
Stroma-fibrin, 44 
Stroma of blood-corpuscles, 33 
Stromuhr, 154 
Struggle of fields of vision, 1001 
“ for existence, 1124 
Struma, 863 
Strychnin, action of, 807 
Stuttering, 664 
Subarachnoid space, 925 
“ fluid, 925 
Subcutaneous injection, 399 
Subdural space, 925 
Subjective auditory perceptions, 
io33 
“ sensations, 932 
Sublingual gland, 256 
Submaxillary ganglion, 252,751 
“ atropin on, 254 
“ nicotin on, 752 
“ gland, 247 
“ saliva, 252 
Substantia gelatinosa, 789 
Successive beats, 1032 
“ contrast, 991 
“ light-induction, 991 
Succinic acid, 517 
Succus entericus, 345 
“ action of drugs on, 347 
Succussion, 213 
Suction, 265 
Sudorifics, 568 
Sugars, 262, 263, 487 
“ absorption of. 374 
“ estimation of, 264, 528 
“ injected into blood, 374 
“ in urine, 527 
“ tests for, 263, 528 
Sulphindigotate of soda, 538 
Summation of stimuli, 618,807 
Summational tones, 1033 
Superfecundation, 1079 
Superficial reflexes, 812 
Superfoetation, 1080 
Superior cardiac nerve, 859 
“ maxillary nerve, 749 
Supplemental air, 196 
Supra-renal capsules, 180 
Surditas verbalis, 910 
Sutures, 638 
Swallowing fluids, 849 
Sweat, 567 
“ chemical composition, 
567 
“ conditions influencing 
. secretion, 568 
“ excretion of substances 
by, 568 
“ glands, 564 
“ influence of nerves, 568 
“ insensible, 567 
“ nerves, 569 
“ pathological variations 
of, 570 
Sweat centre, 866 
“ spinal, 866 
Swimming, 648 
Sylvester’s respiration method, 
235 
Sympathetic ganglion, 777, 779 
“ nerve, 777 
“ “ abdominal, 
782 
“ “ cervical, 780 
“ “ functions of, 
780 
“ “ nicotin on, 
782 
“ “ section of, 
781 
“ “ thoracic,782 
“ nervous system, 
development of, 
1120 
“ ophthalmia, 748 
Symphyses, 638 
Synchondroses, 638 
Syncope, 70 
Syndesmoses, 638 
Synergetic muscles, 641 
Synovia, 637 
Synovial membrane, 637 
Syntonin, 301, 477 
Syrinx, 664 
Systemic circulation, 59 
“ capacity of, 139 
Systole, cardiac, 66, 76 
Tabes, 818 
Taches cerebrales, 863 
Tactile areas, 909 
“ corpuscles of Merkel, 
1046 
“ reflexes, 817 
“ sensations, 1046 
“ “ conduction of, 817 
Tsenia, 1060 
Tail-fold, 1093 
Talipes calcaneus, 642 
“ equinus, 642 
“ varus, 642 
Tambour, Marey’s, 79, 117 
Tanret’s reagent, 523 
Tapetum, 942, 973 
Tapeworm, 1060 
Tapping experiment, 849 
Taste, centre for, 898 
“ organ of, 1040 
“ sense of, 1040 
“ testing, 1043 
Taste-bulbs, 1041 
Taurin, 489 
Taurocholic acid, 333 
Tea, 447 
“ effect of, 263 
Tears, 1005 
Teeth, 267 
“ chemistry of, 269 
“ development of, 269 
“ drugs on, 271 
“ eruption of, 270, 271 1154 
INDEX. 
Teeth, sensibility of, 266 
“ structure of, 267 
Tegmentum, 916 
Teichmann’s crystals, 31 
Telestereoscope, 1000 
Telolemma, 584 
Temperature of animals, 409 
“ accommodation 
for, 422 
“ artificial increase 
of, 425 
“ blood, 409 
“ conditions affect- 
ing, 410 
“ estimation of, 406 
“ febrile, 424 
“ how influenced, 
409 
“ increase of, 425 
“ lowering of, 427 
“ post-mortem, 426 
“ regulation of, 416 
“ skin, 409 
“ spots, 1053 
' “ topography of,409 
“ variations of, 413 
Temperature-sense, 1048, 1053 
“ illusions of,1055 
Tendon, 581 
“ nerves of, 588, 1048 
“ reactions, 813 
“ reflexes, 812 
“ structure of, 587 
Tensor choroideae, 957 
“ tympani, 1015 
Terminal ar eries, 159 
Terminations of sensory nerves 
at the periphery, 1044 
Testicle, descent of, 1116 
Testis, 1061 
Tetanomotor, 677 
Tetanus, 617, 680 
“ number of stimuli, 618 
Tetronerythrin, 45, 484 
Theobromin, 447 
Thermal centres, 899, 908 
“ conductivity, 413 
“ nerves, 7 36 
Thermo-electric methods, 408 
“ needles, 408 
Thermogenesis, 404 
Thermolysis! 418 
Thermometers, 406 
“ clinical, 406 
“ maximal and 
minimal, 406 
“ metastatic, 406 
“ outflow, 408 
Thirst, 451 
Thiry’s fistula, 346 
Thomsen’s disease, 616 
Thoracometer, 209 
Thrombosis, 39 
Thrombus. 39 
Thymus gland, 177 
“ development of, 178, 
1106 
Thyroid gland, 178 
“ development of, 1106 
“ excision of, 179 
Tidal air, 196 
“ wave, 120 
Timbre, 660, 1025 
Time in psychical processes, 
87r 
Time-sense, 1027 
Tinnitus, 759 
“ aurium, 762, 1034 
Tissue formers, 451 
“ metabolism of, 464 
“ regeneration of, 466 
“ transplantation of, 469 
Tissues, reduction by, 230 
Titration for sugar, 264 
Tizzoni’s reaction, 329 
Tobin’s tubes, 238 
Tomes, fibres of, 268 
Tone-inductorium, 619 
Tones, 1024 
Tone-sense, 1027 
Tongue, 271 
“ glands of, 244 
“ movements of, 271 
“ nerves of, 272 
“ papillae of, 1040 
“ structure of, 1040 
“ taste-bulbs of, 1041 
Tonicity of muscle, 627 
Tonometer, 96 
Tonsils, 245 
Tonus, 815 
Tooth, 267 
Topography; cerebral, 901, 911 
Toricelli’s theorem, 105 
Torpedo, 731 
T orticollis paralyticus, 772 
Touch corpuscles, 1044 
“ sense of, 1044 
Toynbee’s membrana tympani, 
1013 
Trachea, 185 
Tracheae, 242 
Transfusion of blood, 56, 168 
“ of other fluids, 170 
Transition resistance, 690 
Transitional epithelium, 550 
Transplantation of tissues, 469 
*• of nerve-fibres, 
685 
Transudations, 400 
Trapez.ius, spasm of, 771 
Traube-Hering curves, 146 
Traumatic degeneration of 
nerves, 684 
“ pneumonia, 768 
Tread, 1070 
Treppe, 618 
Trichina, 1060 
Trigeminus, 744 
“ ganglia of, 745- 
. 749- 75U 752 
“ inferior maxillary 
branch, 750 
“ neuralgia of, 753 
Trigeminus, ophthalmic branch 
745 . 
“ paralysis of, 753 
“ pathological, 753 
“ section of, 747 
“ superior maxillary 
branch, 749 
“ trophic functions 
of, 748 
Trimethylamine, >489 
Triple phosphate, 521 
Trismus, 753 
Trochlearis, 743 
Trommer’s test, 263 
Tropseolin, 295 
Trophic affections, 734 
“ centres, 685 
“ fibres, 685 
“ nerves, 734 
Trophoneuroses, 735 
Trotting, 648 
Truncus arteriosus, 1109 
Trypsin, 313 
Trypsinogen, 3x3 
Tryptone, 312 
Tubal migration of ovum, 1080 
Tube casts, 532 
Tubes, capillary, 107 
“ division of, 107 
“ elastic, 107, 108 
“ movements of fluids in, 
107, 108 
“ rigid, 108 
Tubular breathing, 213 
Tumultus sermonis,9o6 
Tunicin, 489 
Tuning-fork, 1020 
Turacin, 484 
Turck’s method, 811 
Twins, 1079 
Twitch, 608 
Tympanic membrane, 1011 
“ artificial, 1013 
Tympanitic sound, 211 
Tympanum, 1017 
Tyrosin, 314, 489, 531 
Ulcer of foot, perforating, 736 
Umbilical arteries, 1097 
“ cord, 1100 
“ veins, 1097 
“ vesicle, 1093 
Unchanged proteids, 375 
Unison of motor and sensory 
nerves, 726 
Unipolar induction, 698 
“ stimulation, 681 
Upper tones, 1028 
Urachus, 1097, X115 
Uraemia, 548 
Urates, 509 
Urea, 502 
“ antecedents of, 505, 542 
“ compounds of, 505 
“ decomposition of, 503 
“ excreted during starving, 
457 INDEX. 
1155 
Urea ferment, 521 
“ formation of, 504, 541 
“ muscular exercise, 504 
“ nitrate of, 505 
“ occurrence of, 504 
“ oxalate of, 505 
“ pathological, 504 
“ phosphate of, 505 
“ preparation of, 505 
“ properties of, 502, 503 
“ qualitative estimation of, 
506 
“ quantitative estimation 
of, 506 
“ quantity of, 503 
“ relation of, to muscular 
work, 504 
Ureameter, 506 
Ureter, ligature of, 540 
“ pressure in, 538 
“ structure and functions 
of, 549 
Uric acid, 489, 507 
“ diathesis, 549 
“ estimation of, 5x0 
“ formation of, 510, 543 
“ occurrence, 508 
“ properties of, 507 
“ qualitative estimation, 510 
“ quantitative estimation of, 
51° 
“ quantity, 509 
“ solubility, 508 
“ tests for, 510 
Urinary bladder, 551 
“ development 
of, 1115 
“ formation of, 
i"5 
“ calculi, 534 
“ closure of, 552 
“ constituents, formation 
of, 541 
“ deposits, 531 
“ organs, 491 
“ pressure in, 555 
Urine, 499 
“ absorption of, 555 
“ accumulation of, 553 
“ aceton in, 530 
“ acid fermentation, 520 
“ acidity, 502 
“ albumin in, 521 
“ alkaline fermentation, 
520_ 
“ alkaloids in, 549 
“ amount of solids, 500, 
5°i 
4‘ aromatic ethereal com- 
pounds, 519 
“ bile in, 526 
“ blood in, 524 
•“ calculi, 534 
“ changes of, in bladder, 
555 
41 characters of, 499 
Urine, chlorides in, 517 
“ color, 501 
“ coloring matters of, 514 
“ comparative, 556 
“ consistence, 502 
“ cystin in, 530 
“ deposits in, 531 
“ dextrin in, 530 
“ effect of blood-pressure 
on,536 
“ egg-albumin in, 524 
“ electrical condition of, 
731. 
“ excretion of pigments 
by. 539 
“ fermentations of, 520 
“ ferments in, 517 
“ fluorescence, 501 
“ fungi in, 532 
“ gases in, 520 
“ haemoglobin in, 524 
“ hemi-albumose, 524 
“ hippuric acid in, 512 
“ historical, 556 
incontinence of, 556 
“ influence of nerves on, 
544 
“ inorganic constituents, 
517. 
“ inosit in, 530 
“ kreatinin in, 511 
“ leucin in, 530 
“ milk-sugar in, 530 
“ movement of, 550 
“ mucin in, 524 
“ mucus in, 501, 524 
“ nitrogen in, 507 
“ odor, 502 
“ organic bodies in, 502 
“ organisms in, 531 
“ oxalic acid in, 512 
“ passage of, 553 
“ passage of substances 
into, 544 
“ peptone in, 524 
“ phenol in, 515 
“ phosphoric acid in, 518 
“ physical characters of, 
.499 
“ pigments of, 514 
“ propeptone in, 524 
“ proteids in, 523 
“ quantity, 499 
“ reaction, 502 
“ reducing substances in, 
517 
“ retention of, 556 
“ sarkin in, 512 
“ secretion of, 535 
“ serum-glebulm in, 524 
“ silicic acid in, 519 
“ sodium chloride in, 519 
“ solids of, 500 
“ specific gravity, 500 
“ spontaneous changes in, 
520 
Urine, sugar in, 527 
“ sulphuric acid in, 519 
“ taste of, 502 
“ test for albumin in, 522 
“ tube casts in, 532 
“ tyrosin in, 531 
“ urates, 507 
“ urea in, 502 
“ uric acid in, 507 
“ xanthin in, 511 
Urinometer, 500 
Urobilin, 31, 543 
Urochrome, 514 
Uroerythrin, 514 
Uro-genital sinus, 1117 
Uromelanin, 514 
Urorubin, 514 
Urostealith, 534 
Uterine milk, 1099 
Uterus, 1072 
“ changes in, 1074 
“ development of, it 14 
“ involution of, 1123 
“ nerves of, 1122 
Utilization of food, 446 
Utricle, 1020 
Uvea, 936 
Vagi to heart, 92 
Vago-sympathetic nerve, 782 
Vagotomy, 842 
Vagus, 763 
“ action on intestines, 769 
“ branches of, 763 
“ cardiac branches, 767 
“ depressor nerve of, 144, 
766 
“ effect on larynx, 765 
“ effects of section, 768 
“ on heart, 147 
“ pathological, 770 
“ pneumonia after section, 
768 
“ pulmonary branches, 
768 
“ reflex effects of, 769 
“ stimulation of, 850 
“ unequal excitability of 
its branches, 770 
Valleix’s points douloureaux, 
1057 
Valsalva’s experiment, 103, 131 
Valve, ileo-colic, 283 
pyloric, 280 
Valves of heart, 63 
“ disease of, 82 
“ injury to, 70 » 
“ of veins, 111 
“ sounds of, 164 
Valvulae conniventes, 363 
Varicose fibres, 668 
“ veins, 150 
Varnishing the skin, 428 
Vas deferens, 1063 
Vasa vasorum, 112 INDEX. 
Vascular system, development 
of, 1109 
Vaso-dilator centre, 863 
“ nerves, 779, 863 
Vaso-formative cells, 12 
Vaso-inhibitory nerves, 863 
Vaso-motor centre, 854 
“ destruction of, 856 
“ effect of haemor- 
rhage, 855 
“ “ on heart, 861 
“ position of, 855 
“ spinal, 862 
“ stimulation of, 855 
857 
“ nerves, 854 
“ “ course of, 
856 
Vater’s corpuscles, 1045 
Vegetable albumin, 479 
“ casein, 479 
“ foods, 444 
“ proteids, 478 
Vegetables preserved, 446 
Veins, 111 
“ blood flow in, 162 . 
“ cardinal, mi 
“ development of, 1111 
“ ligature of, 151 
“ movement of blood in, 
162 
“ murmurs in, 163 
“ pressure in, 150 
“ pulse in, 164, 165 
“ structure of, III 
“ tonus of, 856 
“ valves in, 111 
“ valvular sounds in, 164 
“ varicose, 150 
“ velocity of blood in, 162 
Vella’s fistula, 346 
Velocity of blood-stream, 137 
Vena azygos, 1112 
Venae advehentes, 1112 
“ revehentes, 1112 
Venous blood, 54 
Ventilation, 237, 238 
Ventricles, 62, 78 
“ aspiration of, 67 
“ brain, 925 
“ capacity of, 138,157 
“ fibres of, 62 
“ impulse of, 73 
“ negative pressure 
in, 69 
“ systole of, 66, 76 
Veratrin, 614 
“ on heart, 98 
“ on muscle, 614 
Vernix caseosa, 566 
Vertebrae, mobility of, 644 
Vertebral column, formation 
of, 1095, 1103 
Vertigo, aural and others, 762 
“ ophthalmic, 762 
Vestibular sacs, 1022 
Vibrations of body, 135 
Vibratives, 662 
Vibrio, 58 
Villus, 363 
“ intestinal, 363 
“ absorption by, 376 
“ chorionic, 1098 
“ contractility of, 366 
“ placental, 1099 
Violet-blindness, 986 
Visceral arches, 1097 
“ clefts, 1097 
Viscero-motor nerves, 779 
Vision, binocular, 996 
“ stereoscopic, 998 
Visual angle, 952 
“ apparatus, 933 
“ area, 896 
“ paths, 897 
“ purple, 484, 942, 980 
Vital capacity, 197 
Vitellin, 476 
Vitelline duct, 1093, 1112 
Vitellus, 1067 
Vitreous humor, 944 
Vocal cords, 649 
“ conditions influencing 
the, 653, 658 
“ resonance, 214 
Voice, 649 
“ falsetto, 659 
“ in animals, 664 
“ pathological variations 
of, 663 
“ physics of, 649 
“ pitch of, 649 
“ production of, 659 
“ range of, 6SQ 
Volt, 688 
Volta’s alternative, 722 
Volume pulse, 167 
Volumetric method, 506 
Vomiting, 281 
“ centre for, 282, 836 
Vowels, 660, 1028 
“ analysis of, 1028 
“ artificial, 1030 
“ formation of, 660, 661 
“ Koenig’s apparatus for, 
1032 
Wagner’s touch corpuscles, 
1044 
Waking, 872 
Walking, 645 
Wallerian law of degeneration, 
683 
Wandering cells, 382 
Warm-blooded animals, 405 
Washed, blood-clot, 39- 
Waste products, elimination of, 
491 
Water, 431, 471 
“ absorbed by skin, 571 
“ absorption of, 372 
“ exhaled by skin, 228 
Water, exhaled from lungs, 220 
“ hardness of, 432 
“ impurities, 432, 433 
“ in urine, 501 
“ vapor of, in air, 220 
Watery vapor, estimation of, 
219 
Wave, pulse, 120 
“ propagation of, 133 
Wave-motion, 107 
Wave-movements, 1009 
Waves, in elastic tubes, 133 
Weber’s glands, 244 
“ law, 932 
“ paradox, 626 
Weigert’s method, 671 
Weight, increase of, 470 
“ loss of, 457 
Weyl’s test, 511 
Wharton’s jelly, 1100 
Whispering, 660 
White blood-corpuscles, 15 
“ chemical composition, 
34 
“ diapedesis of, 160 
“ effects of drugs, 18 
“ “ reagents, 17 
“ number, 17 
“ relation to aniline pig- 
ments, 18 
White of egg, 473 
Wine, 449 
Wittich’s glycerin method, 262 
Wolffian bodies, 1115 
“ ducts, 1114 
Word-blindness, 908 
Word-deafness, 909 
Work, 622 
“ of heart, 158 
“ unit of, xxxviii 
Xanthin, 489 
Xanthokyanopy, 986 
Xanthophane, 943 
Xanthoproteic reaction, 474 
Xerosis, 748 
Yawning, 217 
Yeast, 448, 483 
Yolk, 1067, 1070 
“ cleavage of, 1082 
“ plates, 479 
“ sac, 1093 
Yellow-spot, 970 
Young-Helmholtz theory, 984 
Zero-temperature, 1054 
Zimmermann, particles of, 20 
Zinn, zonule of, 944 
Zoetrope, 988 
Zollner’s lines, 1003 
Zona pellucida, 1067 
Zonule of Zinn, 944 
Zoogloea, 349 
Zymogen, 297 SEPTEMBER, 1891. 
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TUSON. Veterinary Pharmacopoeia. Including the Outlines of Materia Medica 
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TYSON. Bright’s Disease and Diabetes. With Especial Reference to Pathology 
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WALSHAM. Manual of Practical Surgery. For Students and Physicians. By 
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WALSHAM'S PRACTICAL SURGERY. A Manual for Students and Physicians. By Wm, J. 
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geon to Metropolitan Free Hospital, London, etc. 236 Illust. 656 pp. 
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“ While evidently intended to be a text-book for students, and therefore small in size and compactly written, is neverthe- 
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with advanced ideas.’’ 
PARVIN’S-WINCKEL’S DISEASES OF WOMEN. Second Edition. A Treatise on the Dis- 
eases of Women. Including the Diseases of the Bladder and Urethra. By Dr. F. Winckel, Professor 
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son Medical College. Illustrated by 150 fine Engravings on Wood, most of which are new. 760 pp. 
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Examiner in Midwifery to the Conjoint Examining Board of England. 227 Illustrations. 753 pages. 
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Front The Archives 0/Gyncecology, New York. 
“ The illustrations are mostly new and well executed, and we heartily commend this book as far superior to any manual 
upon this subject.” 
YEO’S MANUAL OF PHYSIOLOGY. Fifth Edition. A New Text-book for Students. By 
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tions and a Glossary. 758 pages. Cloth, $3.00; Leather, $3.50 
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cular of the University Medical College.” 
GOODHARTAND STARR, DISEASES OF CHILDREN. Second Edition. By J. F. Goodhart, 
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Second American from third English Edition. Revised and Edited by Louis Starr, m.d., Clinical 
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Children’s Hospital, Phila. With many new Prescriptions and Directions for making Artificial Human 
Milk, for the Artificial Digestion of Milk, etc. 760 pages. Cloth, $3.00; Leather, $3.50 
From The New York Medical Record. 
“ As it is said of some men, so it might be said ot some books, that they are ‘ born to greatness.* This new volume has 
we believe, a mission, particularly in the hands of the young members of the profession. In these days of prolixity in medical 
literature, it is refreshing to meet with an author who knows both what to say and when he has said it.” 
WARING’S PRACTICAL THERAPEUTICS. Fourth Edition. A Manual of Practical Thera- 
peutics, considered with reference to Articles of the Materia Medica. Containing, also, an Index of 
Diseases, with a list of Medicines applicable as Remedies, and a full Index of the Medicines and 
Preparations noticed in the work. By Edward John Waring, m.d., f.r.c.p., f.l.s., etc. 4th 
Edition. Rewritten and Revised. Edited by Dudley W. Buxton, m.d., Asst, to the Prof, of Medicine 
at University College Hospital; Member of the Royal College of Physicians of London. 666 pages. 
Cloth, $3.00; Leather, $3.50 
From The Kansas City Medical Record. 
“ As a work of reference it excels, on account of the several complete indexes added to this edition. It was deservedly 
popular in former editions, and will be more so in the one before us, on account of the careful arrangement of the subjects.” 
REESE’S MEDICAL JURISPRUDENCE AND TOXICOLOGY. Third Edition. By John 
J. Reese, m.d., Professor of Medical Jurisprudence and Toxicology in the University of Pennsylvania ; 
late President of the Medical Jurisprudence Society of Philadelphia; Physician to St. Joseph’s Hospital; 
Member of the College of Physicians of Phila.; Corresponding Member of the New York Medico-Legal 
Society, etc. Third Edition. Revised and Enlarged. 666 pages. Cloth, $3.00; Leather, $3.50 
Front The American Journal of Medical Sciences.—“ This admirable text-book.” 
From Cincinnati Lancet and Clinic. 
“ We lay this volume aside, after a careful perusal of its pages, with the profound impression that it should be in the hands 
of every doctor and lawyer. It fully meets the wants of all students. . . . He has succeeded in admirably condensing into 
a handy volume all the essential points.” 
THE MOST PRACTICAL SERIES OF TEXT-BOOKS. PHYSIOLOGY. 
Landois. A Text-Book of Human Physiology. Third 
Edition. 692 Illustrations. 1889. 
INCLUDING HISTOLOGY AND MICROSCOPICAL ANATOMY, 
with special reference to the requirements of Practi- 
cal Medicine. By Dr. L. Landois, Professor of 
Physiology and Director of the Physiological Insti- 
tute in the University of Greifswald. Third Ameri- 
can, translated from the Sixth German Edition, with 
additions, by Wm. Stirling, m.d., d.Sc., Bracken- 
bury Professor of Physiology and Histology in Owens 
College, Manchester; Examiner in Physiology in 
University of Oxford. With 692 Illustrations. En- 
larged, Revised and Improved. Royal Octavo. 
One Volume. Cloth, $6.50; Leather, $7.50 
*** The practical value of this book to the physician 
can scarcely be over-estimated. It is not a text-book as 
the term is generally understood, but a treatise on Phy- 
siology in its relations to practical medicine, and in- 
cludes much clinical information. 
“ It is the most complete and satisfactory text-book on physiology 
extant. The translator and publisher have each done something to 
increase the value of the volume. Dr. Stirling has added numerous 
useful annotations and a large number of new plates. ... We 
wish that every medical student and physician could be drilled on 
these volumes.”—The A. Y. Medical Record. 
SPECIMEN OF ILLUSTRATIONS. 
Yeo’s Manual of Physiology. Fifth Edition. 1891. 
A TEXT-BOOK FOR STUDENTS OF MEDICINE. By 
Gerald F. Yeo, m.d., f.r.c.s., Professor of 
Physiology in King’s College, London, Fifth 
Edition. With New Illustrations. 321 Wood 
Engravings and a Glossary. Crown Octavo. 
Being No. 4, New Series of Manuals. 
Cloth, $3.00; Leather, $3.50 
This volume was specially prepared to furnish 
a new text-book of Physiology, elementary so far as 
to avoid theories which have not borne the test of 
time and such details of methods as are unnecessary 
for students. While endeavoring to save the student 
from doubtful and erroneous doctrines, great care has 
been taken not to omit any important facts that are 
necessary to an acquirement of a clear idea of the 
principles of Physiology. Such subjects as are useful 
in the practice of medicine and surgery are treated 
more fully than those which are essential only to an 
abstract physiological knowledge. A book in every 
way suited for student’s use. 
“ Dr. Yeo’s manual has reached the position of being, we 
believe, the best by far of the smaller text-books on Physiology.” 
— Therapeutic Gazette. 
SPECIMEN OF ILLUSTRATIONS. PRACTICE OF MEDICINE. 
Taylor. Practice of Medicine. 1890. 
a manual of the practice of medicine. By Frederick Taylor, m. d., Physician 
to, and Lecturer on Medicine at, Guy’s Hospital, London; Physician to the Evelina 
Hospital for Sick Children ; Examiner in Materia Medica and Pharmaceutical Chem- 
istry, at the University of London. Cloth, $4.00; Leather, $5.00 
“ By consulting the most recent works, especially those of Fagge, Striimpell, Payne, 
Ziegler, Gowers, M. Mackenzie, Douglas Powell, Ralfe, H. Morris and Crocker, to 
whom I must express my indebtedness, I have sought to bring this book fully up to the 
modern state of knowledge. I have not, however, devoted much space to the discussion 
of theories, finding that the facts of medicine are amply sufficient to fill, and more than 
fill, a volume such as this, and being convinced that these facts require to be seized and 
held fast by the beginners in medicine, not only for the sake of diagnosis and treatment, 
but also for the right estimation of the various theories which are advanced. With a 
brief statement, therefore, of such views I have in most cases been content.” 
“ It is an entirely original work, by one accustomed to teach his subject both didactically and clinically, 
who knows and understands how to present to the reader both the essential elements and the endless details 
of the science and art of medicine. How well Dr. Frederick Taylor has performed his task, may be learned 
almost ad aperturam. . . . The author has taken great pains to embody in this work the latest advances 
in our knowledge of the nature and treatment of disease. We find, for example, accounts of actinomycosis 
and the use of suspension, and even of the epidemic of Russian influenza which swept over Europe last 
winter. 
“ We have noted with particular care, and we will say with particular approval, the extremely sensible 
remarks which Dr. Taylor has given us under the head of treatment. In some respects the sections on treat- 
ment must have been the most difficult part to write of a short treatise on the practice of medicine. Manifestly 
the first and the chief end to be attained, is the inculcation of sound therapeutical principles. But in the 
second place, the students and young practitioner must have something concrete supplied to them, in the 
shape of details to which they can refer, when they are either following the practice of their teachers or find 
themselves face to face with patients of their own. Dr. Taylor has succeeded admirably in fulfilling both 
these indications, if we may borrow what is itself a therapeutical phrase.”—The Practitioner, London, Sep- 
tember, 1890. 
“ Sedatives, Dr. Taylor further says, in speaking of capillary bronchitis, must be given with the greatest 
caution, or entirely avoided, for the reasons given. In referring to the treatment of chronic bronchitis the 
author recommends, among other good agents, turpentine, copaiba, and the more modem drug—terebene. 
This will, on examination, be found to abound in very many such practical observations, making the manual 
of great service to the physician.”—Medical Bulletin, Philadelphia, January, 1891. 
“ Dr. Taylor has given us a very valuable work. We are pleased to miss the long and interminable 
dissertations on etiology and pathological anatomy, these subjects being clearly and briefly stated. On the 
other hand, the pages of the book are mostly taken up with the subjects of symptoms, diagnosis, prognosis and 
treatment, all of the utmost importance in actual practice. The work is up to date in all essential particulars of 
medical advance. This is one of the books to buy for this season.”—Medical World, Phila., December, 1890. 
“ We have already spoken in warm praise of the book, and have only to add that it is just the one to put 
in the hands of a student who wishes to read up a subject while he is listening to lectures on practice; it is 
full enough to be clear, without being full enough to confuse.”—Medical and Surgical Reporter, Philadel- 
phia, January, 1891. 
“ The book is just such a one as may lead the student to regard the mastery of medical science as an easy 
task, the subtle and obscure points having been placed in the background. It seems to us that in this the author 
has acted well. We know of no work that, while being satisfactorily full, addresses itself more readily to the 
understanding than does this. When this is mastered, the student will feel encouraged for greater tasks, 
instead of being disheartened and having his ardor disappointed at the very threshold of his studies.”— 
American Practitioner and News, January 3d, 1891. 
“ So far as we are informed, this is the first instance in which Dr. Taylor has come before the Medical 
World as an author. His reputation as a teacher and practitioner has, for some time, been an enviable and 
extensive one. Many candidates for degrees, and many now in the ranks of the profession, can testify to his 
knowledge of medicine and his efficiency in his practice. His literary effort now just being presented deserves 
respect and fair examination on account of the author’s record and position, irrespective of its intrinsic worth. 
But the book, we are convinced, has merits that will gain for it recognition, even if its author were unknown 
or nameless. It is a handbook on the practice of medicine, from which theory and superfluity have been 
eliminated, and facts of practical utility alone recognized.”—Pacific Medical Journal, San Francisco, Feb- 
ruary, 2d, 1891. 
“ On the whole, we think it would be difficult to find another work on the same subject, which contained 
in a similar space so much information. Dr. Taylor’s style of writing, too, is clear and readable, and we feel 
sure that his book will be widely read and appreciated.”—The Dublin Journal of Medical Science. NEW AND REVISED EDITIONS. 
? QUIZ-COMPENDS. ? 
A SERIES OF PRACTICAL MANUALS FOR THE PHYSICIAN AND STUDENT. 
Compiled in accordance with the latest teachings of prominent lecturers 
and the most popular Text-books. 
Bound in Cloth, each $1.00. Interleaved, for the Addition of Notes, $1.25. 
They form a most complete, practical and exhaustive set of manuals, containing information nowhere else 
collected in such a practical shape. Thoroughly up to the times in every respect, containing many new pre- 
scriptions and formulae, and over 300 illustrations, many of which have been drawn and engraved specially for 
this series. The authors have had large experience as quiz-masters and attaches of colleges, with exceptional 
opportunities for noting the most recent advances and methods. The arrangement of the subjects, illustrations, 
types, etc., are all of the most approved form. They are constantly being revised, so as to include the latest 
and best teachings, and can be used by students of any college of medicine, dentistry and pharmacy. 
No. 1. Human Anatomy. Fifth Edition (1891), including Visceral Anatomy, formerly pub- 
lished separately. 16 Lithograph Plates, Tables, and 117 Illustrations. By Samuel O. L. 
Potter, m.a., m.d., late A. A. Surgeon, U. S. Army. Professor of Practice, Cooper Med. College, 
San Francisco. 
Nos. 2 and 3. Practice of Medicine. Fourth Edition, Enlarged (1890). By Daniel E. Hughes, 
m.d., late Demonstrator of Clinical Medicine in Jefferson Med. College, Phila.; Physician-in-Chief, Phila- 
delphia Hospital. In two parts. 
Part I.—Continued, Eruptive and Periodical Fevers, Diseases of the Stomach, Intestines, Peritoneum, Biliary Passages, 
Liver, Kidneys, etc. (including Tests for Urine), General Diseases, etc. 
Part II.—Diseases of the Respiratory System (including Physical Diagnosis), Circulatory System and Nervous System; 
Diseases of the Blood, etc. 
*** These little books can be regarded as a full set of notes upon the Practice of Medicine, containing the Synonyms, 
Definitions, Causes, Symptoms, Prognosis, Diagnosis, Treatment, etc., of each disease, and including a number of prescrip- 
tions hitherto unpublished. 
No. 4. Physiology, including Embryology. Sixth Edition (1891). By Albert P. Brubaker, m.d., 
Prof, of Physiology, Penn’a College of Dental Surgery; Demonstrator of Physiology in Jefferson Med. 
College, Phila. Revised, Enlarged and Illustrated. In Press. 
No. 5. Obstetrics. Illustrated. Fourth Edition (1889). For Physicians and Students. By Henry' 
G. Landis, m.d., Prof, of Obstetrics and Diseases of Women, in Starling Medical College, Columbus. 
Revised Edition. New Illustrations. 
No. 6. Materia Medica, Therapeutics and Prescription Writing. Fifth Revised Edition (1891). 
With especial Reference to the Physiological Action of Drugs, and a complete article on Prescription 
Writing. Based on the Last Revision (Sixth) of the U. S. Pharmacopoeia, and including many unofficinal 
remedies. By Samuel O. L. Potter, m.a., m.d., late A. A. Surg. U. S. Army; Prof, of Practice,. 
Cooper Med. College, San Francisco. 5th Edition. Improved and Enlarged. 
No. 7. Gynaecology. (1891.) A Compend of Diseases of Women. By Henry Morris, m.d., Demon- 
strator of Obstetrics, Jefferson Medical College, Philadelphia. Many Illustrations. 
No. 8. Diseases of the Eye and Refraction. Second Edition (1888). Including Treatment and 
Surgery. By L. Webster Fox, m.d., Chief Clinical Assistant Opthalmological Dept., Jefferson Medical 
College, etc., and Geo. M. Gould, m.d. 71 Illustrations, 39 Formulae. 
No. g. Surgery, Minor Surgery and Bandaging. Illustrated. Fourth Edition (1890). Including 
Fractures, Wounds, Dislocations, Sprains, Amputations and other operations; Inflammation, Suppuration, 
Ulcers, Syphilis, Tumors, Shock, etc. Diseases of the Spine, Ear, Bladder, Testicles, Anus, and other 
Surgical Diseases. By Orville Horwitz, a.m., m.d., Demonstrator of Surgery, Jefferson Medical 
College. 84 Formulae and 136 Illustrations. 
No. 10. Medical Chemistry. Third Edition (1890). Inorganic and Organic, including Urine Analysis, 
For Medical and Dental Students. By Henry Leffmann, m.d., Prof, of Chemistry in Penn’a College 
of Dental Surgery, Phila. Third Edition. Revised and Enlarged. 
No. 11. Pharmacy. Third Edition (1890). Based upon “ Remington’s Text-Book of Pharmacy.” By 
F. E. Stewart, m.d., ph.g., Professor of Pharmacy, Powers College of Pharmacy; late Quiz-Master at 
Philadelphia College of Pharmacy. Third Edition. Revised. 
No. 12. Veterinary Anatomy and Physiology. Illustrated. (1890.) By Wm. R. Ballou, m.d., Prof. 
of Equine Anatomy, New York College of Veterinary Surgeons, etc. 29 Illustrations. 
No. 13. Dental Pathology and Dental Medicine. (1890.) Containing all the most noteworthy points 
of interest to the Dental Student. By Geo. W. Warren, d.d.s., Clinical Chief, Penn’a College of 
Dental Surgery, Philadelphia. Ulus. 
No. 14. Diseases of Children. (1890.) By Marcus P. Hatfield, Professor of Diseases of Children, 
Chicago Medical College. With Colored Plate. 
These books are constantly revised to keep up with the latest teachings and discoveries. 
From The Southern Clinic.—“ We know of no series of books issued by any house that so 
fully meets our approval as these ? Quiz- Compends ? They are well arranged, full and concise, 
and are really the best line of text-books that could be found for either student or practitioner.” NERVOUS AND MENTAL DISEASES. 
Gowers’ Diseases of the Nervous System. Second Edi- 
tion. 1891. 
A COMPLETE MANUAL OF THE DISEASES OF THE NERVOUS SYSTEM. By WlLLIAM R. 
Gowers, m.d., f.r.c.p., Lond., Prof. Clinical Medicine, University College, London; 
Physician to National Hospital for the Paralyzed and Epileptic; late Physician 
University College, London, etc. With about 375 Illustrations, including over 600 
Different Figures. In Two Handsome Octavo Volumes. 1600 pages. 
Vol. I, Nearly Ready. Vol. II, Ready September. 
*** The first American edition of this book, which was published in one rather 
unwieldy volume, was completely exhausted within eighteen months. In printing the 
second, it has been thought best to follow the style adopted by the English publishers, 
and issue it in two volumes. In this form it will be much handier for reading and refer- 
ence. Dr. Gowers has devoted a great deal of time and work in the revising; many 
sections have been rewritten, and the new matter will amount to about 100 pages, includ- 
ing an important chapter on Multiple Neuritis, of which no good account exists, and a 
number of new illustrations. 
A large number of the illustrations are original, having been made from special draw- 
ings or from photographs of cases; they not only serve to illustrate the text, but will be 
found of great value in the diagnosing of obscure cases. 
PRESS NOTICES OF FIRST EDITION. 
“ It may be said, without reserve, that this work is the most clear, concise and complete text-book upon 
diseases of the nervous system in any language. And when the large number of such works which has 
appeared in Germany, France and England within the past ten years is considered, this implies high praise.” 
— The American Journal of Medical Science. 
“ Taken as a whole, it promises to be the most useful work on diseases of the nervous system which we 
possess.”—The Dublin Journal of Medical Sciences. 
“ The student and practitioner will find in it a true friend, guide and helper in his studies of the diseases 
of the nervous system. It is a most complete manual, presenting a thorough reflex of the present state of 
knowledge of the diseases of the nervous system. The care and thought that have been bestowed on its pro- 
duction are evident on every page. In the presence of such ability, learning and originality, criticism can only 
take a favorable direction. The style and manner are accurate, studied and adequate—never diffuse. The 
illustrations call for special notice. They are numerous, new and original. No better manual on nervous 
diseases has been presented to the medical profession.”—The London Lancet. 
“ Gowers’ manual is herewith recommended to the general and to the special student. It is not too 
detailed for the former, while for the specialist it is explicit enough as a first-class book of reference. It is, on 
the whole, an admirable treatise.”—The Jownal of Nervous and Mental Diseases, New York. 
BY THE SAME AUTHOR. 
Diseases of the Brain. Lectures on Diagnosis of Diseases of the Brain, delivered at 
University College Hospital. Second Edition. Illustrated. 8vo. Cloth, $2.00 
SPECIMEN OF ILLUSTRATIONS—FLEXOR CONTRACTION OF LEGS IN MYELITIS OF THE DORSAL REGION. Now Ready, for 1892. 41st Year. 
The Physician’s Visiting List. 
(LINDSAY & BLAKISTON’S.) 
CONTENTS. 
Almanac for 1892 and 1893; Table of Signs to be used in keeping accounts; Marshall Hall’s Ready 
Method in Asphyxia; Poisons and Antidotes, revised for 1892; The Metric or French Decimal System of 
Weights and Measures; Dose Table,revised and rewritten for 1892; List of New Remedies for 1892; Aids 
to Diagnosis and Treatment of Diseases of the Eye; Diagram Showing Eruption of Milk Teeth, Dr. Louis 
Starr; Posological Table; Disinfectants and Disinfecting; Examination of Urine, Dr. J. Daland, based 
upon Tyson's “ Practical Examination of Urine ”; Incompatibility, Dr. S. O. L. Potter ; A New Complete 
Table for Calculating the Period of Utero-Gestation; Sylvester’s Method for Artificial Respiration, Illustrated; 
Diagram of the Chest; Blank Leaves, suitably ruled, for Visiting Lists, Monthly Memoranda, Addresses of 
Patients and others; Addresses of Nurses, their references, etc.; Accounts asked for; Memoranda of Wants; 
Obstetric and Vaccination Engagements; Record of Births and Deaths; Cash Account, etc.; Special Pencil 
with Rubber Tip. 
This Visiting List is published in November of each year. 
SIZES AND PRICES. 
For 25 Patients weekly. 
50 
REGULAR EDITION. 
Tucks, pockets and Pencil, 
75 
too 
2 Vols. 
2 Vols 
Jan. to June 
July to Dec. 
Jan. to June 
July to Dec. 
For 25 Patients weekly 
5° “ 
1 2 Vols -Han-t0 !unel “ 
50 
51.00 
1.25 
1.50 
2.00 
2.50 
3-°o 
INTERLEAVED EDITION. 
Interleaved, tucks and Pencil, 
f Ja 
' (July to Dec. J 
SPECIAL SIZES AND 
1.25 
1.50 
PERPETUAL EDITION, without Dates. 
No. 1. Containing space for over 1300 names, with 
blank page opposite each Visiting List page. 
Bound in Red Leather cover, with pocket and 
Pencil, $1.25 
No. 2. Containing space for 2600 names, with blank 
page opposite each Visiting List page. Bound 
like No. 1, with Pocket and Pencil, • . 1.50 
MONTHLY EDITION, without Dates. 
No. 1. Bound, Seal leather, without Flap or Pencil, 
gilt edges, 
No. 2. Bound, Seal leather, with Tucks, Pencil, etc., 
gilt edges, 1.00 
75 
3.00 
BINDINGS MADE TO ORDER 
PRESS NOTICES OF EDITION FOR 1891 
“ Nothing can seem better fitted to meet the purpose for 
which they are designed than these Visiting Lists of 
Messrs. Blakiston, and the forty years of patronage they 
have enjoyed must have convinced public and publisher 
alike of their value. We not only have the convenient 
arrangement for keeping visiting accounts, but a fund of 
useful information of all kinds, embracing dose tables, 
weights and measures, posological tables, disinfectants, 
urinary analysis, poisons and antidotes, etc., all arranged 
for ready reference in a well bound leather book that can 
at all times be carried in the coat pocket. These books 
are complete, comprehensive, and convenient.”—The 
Physician and Surgeon, Ann Arbor, Mich. 
“ It has long been known to the profession, and needs no 
further notice than to say that it maintains the standard 
of excellence acquired by its predecessors.”—New Orleans 
RIedical and Surgical Journal. 
“This oldest and best known of the Visiting Lists 
comes with the new year unchanged in form, and with 
such alterations in contents only as were called for by 
recent therapeutic advance. In compactness, neatness, 
and completeness it is a marvel.”—American Practitioner 
and News, Louisville. 
“ This is the thirty-ninth year of the publication of this 
neat, compact, and universally-acknowledged-to-be the 
best of its kind published. It has stood the test of time 
and finds ready sale from a simple announcement that it is 
ready ’ ’— The Medical Brief, St. Louis. 
“ The best endorsement I can give of my appreciation 
of the Lindsay & Blakiston Visiting List is, that I have 
been using it from its first issue and find it is the best in 
use.”—O. F. Potter, M.D., St. Louis. 
“ This is the eleventh year that we are using this Visit- 
ing List in our practice, and we can truly say that we 
could not wish for anything better. It has saved us many 
times its cost, and, besides, has furnished a permanent and 
pleasing record of our daily work during the years that 
nave passed.”—Canada Medical Record. 
Dear Sirs :—We received the Visiting List for 1891. It is 
the finest of all. We had five (5) sent us, from the same 
number of firms, and must acknowledge it is the smallest, 
neatest and most compact, as any physician can place it in 
his side pocket with ease, while, if you have noticed or 
seen the others, they will require the tailor to enlarge the 
coat pocket. Very truly yours, 
N. W. Medical Journal, 
Minneapolis, Minn. 
“ The fact that this Visiting List has been published an- 
nually for forty years is sufficient guarantee of its excellence 
and popularity. In addition to the visiting list proper, it 
contains easily-accessible suggestions upon many of the 
emergencies that may arise in a physician’s practice, and 
when he is too far from home to learn from his text-books 
the antidote for a poison that may have been swallowed, 
or the proper method of resuscitating a half-drowned per- 
son. True, he should know these things, but who does not 
occasionally forget, when he most wishes to remember ? 
There are also dose-tables, tables of the metric system, a 
list of new remedies for 1890, rules for examining urine, a 
table for calculating the period of pregnancy, and other 
equally useful information. The arrangement for entering 
patients, visits, consultations, etc., is exceeding simple, 
and the whole makes a thin, compact, and easily-carried 
volume.”—Medical News, Philada., January jd, i8gz. 
Blakiston, Son & Co. wish to announce that the edition for 1892 contains several 
improvements that will, without making any radical changes, greatly enhance its usefulness, 
compactness and durability. SURGERY. 
A COMPLETE PRACTICAL TREATISE, 
WITH SPECIAL REFERENCE TO TREATMENT. 
BY C. W. MANSELL MOU LLIN, M.A., M.D.. OXON., 
FELLOW OF THE ROYAL COLLEGE OF SURGEONS; SURGEON AND LECTURER ON PHYSIOLOGY TO THE LONDON HOSPITAL, ETC. 
ASSISTED BY VARIOUS WRITERS ON SPECIAL SUBJECTS. 
FIVE HUNDRED ILLUSTRATIONS. 
200 OF WHICH ARE ORIGINAL WITH THIS WORK. 
ROYAL OCTAVO. 1190 PAGES. 
Royal 8vo. Handsome Cloth, $7.00; Leather, Raised Bands, $8.00. 
Extract from the Preface.—“ Modem Surgery has advanced with such rapid strides, and in so many 
different directions, that it is almost impossible within the space of a single volume to give more than an 
epitome of its main principles. I have therefore touched but lightly upon controversial matters, and have 
endeavored to make this book a practical one, in the hope that it may be of greater service to students and 
general practitioners. With thi§ object, I have given special attention to the question of Treatment; and I 
have included under the head of each organ a brief description of the malformations to which it is liable, and 
the various operations that may be performed under it, instead of relegating them to chapters by themselves. 
The General Pathology of Surgical Diseases is dealt with in Part I; that of Injuries in Part II. In Part III, 
the Diseases and Injuries of Special Structures and Organs are considered more fully. Throughout, I have 
endeavored to enforce the idea that the chief aim and object of Surgery at the present day is, to assist the 
tissues in every possible way in their straggle against disease. 
“ Of the five hundred illustrations, nearly two hundred were (with four exceptions) drawn from original 
specimens by my brother, Dr. J. A. Mansell Moulin (to whom I am also indebted for the article on Diseases 
of the Female Generative Organs), or myself. 
“ I have to express my thanks to Mr. J. Hutchinson, junior, for his chapters on Diseases of the Skin and 
Eye; to Mr. T. Mark Hovell, for that on Diseases of the Ear and Larynx; and to Mr. F. S. Eve, for that 
on Tumors.” 
OUTLINE OF CONTENTS. 
I. 
II. 
1. 
I. 
II. 
hi. 
IV. 
V. 
VI. 
VII. 
VIII. 
IX. 
X. 
XI. 
XII. 
XIII. 
XIV. 
PART I.—GENERAL PATHOLOGY OF SURGICAL DISEASES. 
Injury and Repair. I III & IV. Diseases due to Infective Organisms. 
Diseases due to Non-infective Organisms. | V. Tumors. 
PART II.—GENERAL PATHOLOGY OF INJURIES. 
The General Effects of Injury. | II. The'Local Effects of Injury. 
PART III.—DISEASES AND INJURIES OF SPECIAL STRUCTURES, 
Diseases of the Skin. 
Injuries and Diseases of Blood-vessels. 
Injuries and Diseases of Lymphatics. 
Injuries and Diseases of Nerves. 
Injuries and Diseases of Muscles, Tendons, etc. 
Injuries and Diseases of Bones and Joints. 
Injuries and Diseases of the Head. 
Injuries and Diseases of the Back. 
Injuries and Diseases of the Eye. 
Injuries and Diseases of the Face and Nose. 
Injuries and Diseases of the Mouth and Jaws. 
Injuries and Diseases of the Tongue, Salivary 
Glands and .Tonsils. 
Diseases of the Ear and Larynx. 
Injuries and Diseases of the Neck and Throat. 
XV. Diseases of the Thyroid. 
XVI. Injuries and Diseases of the Pharynx and 
CEsophagus. 
XVII. Injuries and Diseases of the Chest. 
XVIII. Injuries and Diseases of the Abdomen. 
XIX. Injuries and Diseases of the Rectum. 
XX. Injuries and Diseases of the Kidney. 
XXI. Injuries and Diseases of the Bladder. 
XXII. Diseases of the Prostate. 
XXIII. Injuries and Diseases of the Urethra. 
XXIV. Injuries and Diseases of the Male Organs. 
XXV. Diseases of the Female Generative Organs. 
XXVI. Diseases of the Breast. 
XXVII. Amputations. 
XXVIII. Anaesthetics. 
SAMPLE PAGES SENT FREE UPON APPLICATION.