••-.#•* ,» ''£* --■-.ft-- "'4* *?'■■•■'v.. ■ Si m; $2'X NATIONAL LIBRARY OF MEDICINE Washington Founded 1836 U. S. Department of Health, Education, and Welfare Public Health Service ■*-,■' A NEW DICTIONARY OF MEDICAL SCIENCE AND LITERATURE. A NEW EDITION Completely Revised, with Numerous Additions and Improvements, OF DUNGLISON'S DICTIONARY OF MEDICAL SCIENCE AND LITERATURE: CONTAINING A concise account of the various Subjects and Terms, with a vocabulary of Syno- nymes in different languages, and formulae for various Officinal and Empirical Preparations, &c. IN ONE ROYAL 8vo. VOLUME. " The present undertaking was suggested by the frequent complaints made by the author's pupils, that they were unable to meet with information on numerous topics of professional inquiry,—especially of recent introduction,—in the medical dictionaries accessible to them. " It may, indeed, be correctly affirmed, that we have no dictionary of medical subjects and terms which can be looked upon as adapted to the state of the science. In proof of this the author need but to remark, that he has found occasion* to add several thou- sand medical terms, which are not to be met with in the only medical lexicon at this time in circulation in the country. " The present edition will be found to contain many hundred terms more than the first, and to have experienced numerous additions and modifications. " The author's object has not been to make the work a mere lexicon or dictionary of terms, but to afford, under each, a condensed view of its various medical relations, and thus to render the work an epitome of the existing condition of medical science. " To execute such a work requires great erudition, unwearied industry, and exten- sive research; and we know no one who could bring to the task higher qualifications of this description than Professor Dunglison.—American Medical Journal. GENERAL THERAPEUTICS; OR, PRINCIPLES OF MEDICAL PRACTICE. With Tables of the Chief Remedial Agents and their Preparations, and of the Different Poisons and their Antidotes. By ROBLEY DUNGLISON, M. D., &c. &c. One volume, large 8vo. THE PRINCIPLES AND PRACTICE OF MEDICINE; BY PROFESSOR DUNGLISON. Is now in press, and will be issued early in November next. HUMAN PHYSIOLOGY; ILLUSTRATED BY ENGRAVINGS. . ■ .c s/^iv.w' BY ROBLEY DUNGLISON, M.D. PROFESSOR OF THE INSTITUTES OF MEDICINE AND MEDICAL JURISPRUDENCE IN JEFFERSON MEDICAL COLLEGE, PHILADELPHIA } ONE OF THE SECRETARIES TO THE AMERICAN PHILOSOPHICAL SOCIETY, ETC. ETC. ISAAC TT MEASE " Vastissimi studii primas quasi lineas circumscripsi."—Haller. iFourtf) IBliftfon, WITH NUMEROUS ADDITIONS AND MODIFICATIONS. IN TWO VOLUMES. VOL. II. PHILADELPHIA: LEA AND BLANCHARD. 1841. QT c.J NATIONAL LIBRARY OF MEDICINE WASHINGTON, D. C. Entered, according to the Act of Congress, in the year 1841, by Robley Dunglison, in the Clerk's Office of the District Court for the Eastern District of Pennsylvania. C. Sherman & Co. Printers, 19 St. James Street. CONTENTS OF VOL. II. BOOK II. Chap. II. Absorption - - - • ~ "if Digestive Absorption ... - - 14 a. Absorption of Chyle or Chylosis - ' ' }i 1. Anatomy of tne Chyliferous Apparatus - - 14 2. Chyle......20 3. Physiology of Chylosis - ~j> 6. Absorption of Drinks 30 Of the Absorption of Lymph ... - 38 1. Anatomy of the Lymphatic Apparatus - - , 38 2. Lymph......43 3. Physiology of Lymphosis " " " " £n Venous Absorption .... - 50 1. Anatomy of the Venous System 50 2. Blood "......°5 3. Physiology of Venous Absorption ' ' ' In Internal Absorption ----- 80 Accidental Absorption " " " " " ci a. Cutaneous Absorption .... ^4 b. Other Accidental Absorptions - - 88 Chap. III. Respiration ----- 89 1. Anatomy of the Respiratory Organs - - 90 2. Of Atmospheric Air - - - - - 97 3. Physiology of Respiration - 101 a. Mechanical Phenomena of Respiration - - 101 1. Inspiration ------ 103 2. Expiration - - - - . " 107 3. Respiratory Phenomena concerned in certain Func- tions : Jio 4. Respiratory Phenomena connected with Expression 113 6. Chemical Phenomena of Respiration - - 117 c. Cutaneous Respiration, &c. - - , - 133 d. Effects of Section of the Cerebral Nerves on Respira tion ... e. The Respiration of Animals - Chap. IV. Circulation - 1. Anatomy of the Circulatory Organs a. Heart - - - 6. Arteries - c. Intermediate or Capillary System d. Veins - - - 2. Physiology of the Circulation a. Circulation in the Heart 6. Circulation in the Arteries c. Circulation through the Capillaries - • - 177 d. Circulation in the Veins |^ e. Forces that Propel the Blood - - - * iqq /. Accelerating and Retarding Forces - - iyd 134 137 139 142 142 149 152 155 155 158 172 X CONTENTS. g. The Pulse......198 h. Uses of the Circulation ..... 202 i. Transfusion and Infusion .... 204 3. Circulatory Apparatus in Animals ... 205 Chap. V. Nutrition - - - - - - - 208 VI. Calorification ...... 216 VII. Secretion.......248 1. Anatomy of the Secretory Apparatus - 248 2. Physiology of Secretion ----- 251 Of the Exhalations......260 1. Internal Exhalations ..... 260 a. The Serous Exhalation .... 260 b. Serous Exhalation of the Cellular Membrane - - 261 c. Adipous Exhalation of the Cellular Membrane - 261 d. Exhalation of the Marrow - - - ' - 265 e. Synovial Exhalation .... 266 / Exhalation of the Colouring Matter of the Skin and other parts ------ 267 g. Areolar Exhalation .... 268 2. External Exhalations - - - - - 268 a. Cutaneous Exhalation or Transpiration - - 268 b. Pulmonary Transpiration .... 278 c. Exhalation of the Mucous Membranes - - 281 Follicular Secretions ----- 281 a. Mucous Follicular Secretion ... 281 b. Follicular Secretion of the Skin ... 282 Glandular Secretions - 283 a. Secretion of the Tears ..... 283 6. Secretion of the Saliva .... 283 c. Secretion of the Pancreatic Juice ... 285 d. Secretion of the Bile .... 287 e. Secretion of Urine - 298 /. Connexion between the Stomach and the Kidneys - 311 Glandiform Ganglions - 313 a. The Spleen --.... 313 BOOK III. Reproductive Fui Chap. I. Generation ... 1. Generative Apparatus - a. Genital Organs of the Male 1. Sperm ... b. Genital Organs of the Female 1. Menstruation c. Sexual Ambiguity 2. Physiology of Generation a. Copulation b. Fecundation - ' - c Theories of Generation - d. Conception - e. Superforation /. Pregnancy - - g. Signs of Pregnancy h. Duration of Pregnancy i. Parturition j. Lactation ... Chap. II. Fatal Existence.—Embryology 1. Anatomy of the Foetus - - 320 328 - 328 337 - 342 351 - 358 362 - 363 367 - 387 405 - 413 415 - 423 428 - 431 436 - 443 443 CONTENTS. xi a. Dependencies of the Foetus .... 453 b. Developement of the Foetus - - - . 467 c. Peculiarities of the Foetus .... 476 2. Physiology of the Foetus .... 482 a. Animal Functions ..... 482 6. Functions of Nutrition .... 484 c. Functions of Reproduction .... 508 BOOK IV. Chap. I. Ages........509 1. Infancy......509 a. First period of Infancy ----- 509 6. Second period of Infancy or first Dentition - - 514 c. Third period of Infancy ----- 518 2. Childhood......518 3. Adolescence ...... 523 4. Virility or Manhood ----- 526 5. Old Age.......527 Chap. II. Sleep ------- 531 1. Dreams ------- 537 2. Waking Dreams ----- 544 3. Revery ------- 550 Chap. III. Correlation of Functions .... 551 1. Mechanical Correlations - - - - - 552 2. Functional Correlations .... 552 3. Sympathy - - - - - - 557 a. Sympathy of Continuity .... 558 b. Sympathy of Contiguity .... 559 c. Remote Sympathies .... 561 d. Imagination ------ 561 e. Superstitions connected with Sympathy - - 563 f. Agents by which Sympathy is accomplished - - 565 Chap. IV. Individual Differences amongst Mankind - - 567 1. Temperaments ------ 567 a. Sanguine Temperament ... - 568 b. Bilious or Choleric Temperament ... 569 c. Melancholic or Atrabilious Temperament - - 570 d. Phlegmatic, Lymphatic or Pituitous Temperament - 570 e. Nervous Temperament .... 570 2. Idiosyncrasy - - - - - - 572 3. Of Natural and Acquired Differences - - - 574 1. Natural Differences .... - 574 a. Peculiarities of the Female ... 574 2. Acquired Differences ----- 578 1. Habit......578 2. Association ------ 592 3. Imitation - - - - - - 583 4. Varieties of Mankind .... 585 1. Division of the Races - - - - 587 a. Caucasian Race ----- 588 b. Ethiopian Race ... - 590 c. Mongolian Race ... - 591 d. American Race ... - 592 2. Origin of the Different Races - - - 594 Chap.V. Of Life.......603 1. Instinct ------- 610 2. Vital Properties ..... 618 3. Life of the Blood......623 Xll CONTENTS. Chap. VI. Of Death - . ... . . 628 . 1. Death from Old Age ..... 629 2. Accidental Death - 632 a. Death beginning in the Heart - 632 b. Death beginning in the Brain - - . 632 c. Death beginning in the Lungs - - - - 633 HUMAN PHYSIOLOGY. BOOK II. CHAPTER II. ABSORPTION. In the consideration of the preceding functions, we have seen the alimentary matter subjected to various actions and alterations; and, at length, in the small intestine, possessed of the necessary physical constitution for the chyle to be separated from it. Into the mode in which this separation,—which we shall find is not simply a secerning action, but one of elaboration and of a vital character,— is effected, we have now to inquire. It belongs to the function of absorption, and its object is to convey the nutritive fluid, formed from the food, into the current of the circulation. Absorption is not, how- ever, confined to the formation of this fluid. Liquids can pass into the blood directly through the coats of the containing vessel, with- out having been subjected to any elaboration; and the different con- stituents of the organs are constantly subjected to the absorbing action of vessels, by which their decomposition is effected, and their elements are conveyed into the blood; whilst antagonizing vessels, called exhalants, deposit fresh particles in the place of those that are removed. Yet these various substances,—bone, muscle, hair, nail, as the case may be,—are never found, in their compound state, in the blood; and the inference, consequently, is, that at the very radi- cles of these absorbents and exhalants, the substance, on which ab- sorption or exhalation has to be effected, is reduced to its primary constituents, and this by an action, to which we know nothing simi- lar in physics or chemistry: hence, it has been inferred, the opera- tion is one of the acts of vitality. All the various absorptions may be classed under two heads:— the external and the internal; the former including those, that take place on extraneous matters from the surface of the body or from its prolongation—the mucous membranes; and the latter, those that ' are effected internally, on matters proceeding from the body itself, by removing parts already deposited. VOL. II. 2 14 ABSORPTION. By some physiologists, the action of the air in respiration has been referred to the former of these; and the whole function of absorp- tion has been defined;—the aggregate of actions, by which nutritive substances—external and internal—are converted into fluids, which serve as the basis of arterial blood. The function of respiration will be investigated separately. Our attention will, at present, be directed to the other varieties, and first of all, to that which occurs in the digestive tube. DIGESTIVE ABSORPTION. The absorption, effected in the organs of digestion, is of two kinds; according as it concerns liquids of a certain degree of tenuity, or solid food. The former, it has been remarked, are sub- jected to no digestive action, but disappear chiefly from the sto- mach, and the remainder from the small intestine; whilst the latter undergo conversion, before they are fitted to be taken up from the intestinal canal. a. Absorption of Chyle or Chylosis. 1. anatomy of the chyliferous apparatus. In the lower animals, absorption is effected over the whole sur- face of the body, both as regards ihe materials necessary for the nutrition of the body, and the supply of air. No distinct organs for the performance of these functions are perceptible. In the upper classes of animals, however, we find an apparatus, manifestly in- tended for the absorption of chyle, and constituting a vascular com- munication between the small intestine and the left subclavian. Along this channel, the chyle passes, to be emptied into that venous trunk. The chyliferous apparatus consists of the chyliferous vessels, mesenteric glands, and thoracic duct. The chyliferous vessels or lacteals, arise from the inner surface of the small intestine; in the villi, which are at the surface of, and between, the valvulae conni- ventes. Their origin is, however, imperceptible, even by the aid of the microscope; and, accordingly, the nature of their arrange- ment has given occasion to much diversity of sentiment amongst anatomists. Lieberkiihn1 affirms that, by the microscope, it may be shown, that each villus terminates in an ampullula or oval vesicle, which has its apex perforated by lateral orifices, through which the chyle enters. The doctrine of open mouths of lacteals and lympha- tics has been embraced by Hewson,b Sheldon,6 Cruikshank,d Hedwig,6 and Bleuland,f and by many of the anatomists and physiologists of the a Dissert, de Fabric. Villor. Intest. passim. Lugd. Bat 1745. b Experimental Inquiries; edited by M. Falconer, Lond. 1774, 1777, and 1780 c The History of the Absorbent System, &c. p. 1, Lond. 1784. <> Anatomy of the Absorbing Vessels, 2d edit. Lond. 1790. e Disquisit. Ampull. Lieberkuhnii, Lips. 1797. { Exper. Anatom. 1784; and Descript. Vasculor. in Intestinor. Tenuium Tunicis Ultraj. 1797. CHYLIFEROUS APPARATUS. 15 present day ; but, on the other hand, it has been contested by Mas- cagni1 and others; whilst Rudolphi,b Meckel,0 and numerous others'1 believe, that the lacteals have not free orifices in the cavity of the intestine; but that in the villi, in which absorption is effected, a spongy, or sort of gelatinous tissue exists, which accomplishes ab- sorption, and, being continuous with the chyliferous vessels, con- veys the product of absorption into them. Bichat conceived them to commence by a kind of sucker or absorbing mouth, the action of which he compared to that of the puncta lachrymalia or of a leech or cupping-glass; and lastly,—from the observation, often made, that different coloured fluids, with which the lymphatics have been injected, have never spread themselves, either in the cel- lular tissue, or in the parenchyma of the viscera,—Mojon,e of Genoa, believes, that the lymphatics have no patulous orifice, and that they take their origin from a cellular filament, which progressively Chyliferous Vessels. becomes a villosity, an areolar spongiole, a capillary, and, at length, a lymphatic trunk ;—the absorbent action of these vessels being a kind of imbibition. Lastly, Mullerf affirms, that he has never per- ceived any opening at the extremity of the villi; in his earlier examinations, he was unable to see appearances of foramina on any part of their surface, but he has lately observed, in portions of ihe intestines of the sheep and the ox, which had been exposed for some time to the action of water, that, over the whole surface of 1 Vasorum Lymphaticorum Corporis Humani Historia. &c. Senis, 1787; and Pro- dromo d'un Opera sul Sistemo de Vasi Linfatice, Siena, 1784. b Anatomisch. Physiologisehe Abhandlung, Berlin, 1802. c Handbuch, u. s. w. translated by Jouidan and Breschet, p. 179, Paris, 1805. a F. Arnold, Lehrbuch der Physiologic des Menschen, Zurich, 1836-7; and Brit, and For. Med. Rev. Oct. 1839, p. 479. e Journal de la Societe des Sciences Physiques, &c. Nov. 1833. f Handbuch der Physiologic, u. s. vv. and Baly's translation, p. 269, Lond. 1838. 16 ABSORPTION. the villi indistinct depressions were scattered, which might be re- garded as oblique openings. He adds, however, that he makes this observation, with great hesitation and distrust." Chyliferous Apparatus. A A. A portion of the jejunum, b. b, b. b. Superficial lacteals. r„ c, c. Mesentery, ddd First row of mesenteric glands, e, e, e. Second row. /,/. Receptaculuin chyli. s. Thoracic duct A Aorta, j, i. Lymphatics. " All these are mere speculations, too often entirely gratuitous- and it must be admitted, that we know nothing definite^ regarding the extreme radicles of the chyliferous vessels. When they be- come perceptible to the eye, they are observed, as in Fig/109, communicating frequently with each other; and forming a minute network, first between the muscular and mucous membranes, and afterwards between the muscular and peritoneal, until thev termi- • See, also, on this subject, Le Systeme Lymphatique, par M. G. Breschet Paris 1836; Mr. Lane, art. Lymphatic and Lacteal System, Cyclop. Anat. and Physiol P* xxi. April, 1841. * ' " CHYLIFEROUS APPARATUS. 17 nate in larger trunks a, a, a, a. When they attain the point at which the peritoneal coat quits the intestine, they leave it also; and creep for an inch or two in the substance of the mesentery; and then enter a first row of mesenteric glands. From these they issue, of a greater size and in less number; pro- ceed still farther along the mesentery, and reach a second row, into which they likewise enter. From these, again, they issue, larger and less numerous, anastomosing with each other; and proceeding towards the lumbar portion of the spine, where they terminate in a common reservoir,—the reservoir of Pecquet, the receptaculum or cisterna chyli, (Fig. 110)—which is the commencement of the tho- racic duct. This reservoir is situate about the third lumbar vertebra; behind the right pillar of the diaphragm, and the right renal vessels. The chyliferous vessels generally follow the course of the arteries; but sometimes proceed in the spaces between them. They exist in the lower part of the duodenum, through the whole of the jejunum, and in the upper part of the ileum. M. Voisina affirms, that all, or at least the major part, of the chyliferous vessels pass through the substance of the liver, before they empty their contents into the tho- racic duct. After proceeding a certain distance, they anastomose, he says, with each other, enlarge in size, and are collected together so as to form a kind of plexus below the lobe of Spigelius, towards which they converge. From this point, they penetrate the substance of the liver, through which they ramify, with great minuteness, and finally empty themselves into the receptaculum chyli. To prove, that the chyliferous vessels do pass through the liver, in their course to the thoracic duct, he put a ligature around the duct below the diaphragm, in a dog which had eaten largely, and when digestion was in full activity. The chyliferous vessels were observed to swell, and their whitish colour was distinctly perceived. They could, under these circumstances, be traced without much difficulty, from the interior of the intestinal canal, through the mesenteric glands, as far as their entrance into the liver. The chyliferous vessels are composed of two coats; the outer of a fibrous and firm character; the inner very thin, and generally con- sidered to form, by its duplicatures, what are called valves. These valves are of a semilunar form, arranged in pairs, and with the convex side turned towards the intestine. Their arrangement has appeared to be well adapted for permitting the chyle to flow from the intestine to the thoracic duct, and for preventing its retrograde course; but Magendieb affirms, that their existence is by no means constant. These reputed valves are considered by Mojonc to be true sphincters. By placing the lymphatic vessels on a glass plate, and opening them through their entire length, he observed by the micro- scope, that the sphincters are formed'by circular fibres, which, by diminishing the size of the vessel at different points, give rise to the a Nouvel Apercu sur la Physiologie du Foie, &c. Paris, 1833. b Precis Elementaire, 2de edit. ii. 177, Paris, 1825. e Op. citat. and Amer. Journal, &c. for Aug. 1834, p. 465. 2* 13 ABSORPTION. nodosities observed at its exterior. If the ends of a varicose lym- phatic be drawn in a contrary direction, these nodosities disappear, as well as the supposititious valves. Mojon observed, moreover, that the fibrous membrane of the lymphatics has longitudinal, as well as oblique filaments passing from one contraction to another. These longitudinal fibres have their two extremities attached to the transverse fibres, which, according to him, constitute the sphincters or contractors of the lymphatics. He explains the difficulty often experienced in attempting to inject the lymphatic vessels in a direc- tion contrary to the course of the lymph, by the circumstance, that the little pouches, formed by the sphincters, and the relaxation or distension of their parietes, on filling them with the injected matter, diminish the calibre of the tube, and may even close it entirely. Some anatomists describe an external coat, which is formed of con- densed cellular tissue, and unites the chyliferous vessels to the neigh- bouring parts. The mesenteric glands or ganglions are small, irregularly lenti- cular, organs; varying in size from the sixth of an inch, to an inch; nearly one hundred in number, and situate between the two laminas of the mesentery. In them, the lymphatic vessels of the abdomen terminate, and the chyliferous vessels traverse them, in their course from the small intestine to the thoracic duct. Their substance is of a pale rosy colour; and their consistence moderate. By pressure, a transparent and inodorous fluid can be forced from them ; which has never been examined chemically.a Anatomists differ with regard to their structure. According to some, they consist of a pellet of chyliferous vessels, folded a thousand times upon each other; sub- dividing and anastomosing almost ad infinitum; united by cellular tissue, and receiving a number of blood-vessels. In the opinion of others, again, cells exist in their interior, into which the afferent chyliferous vessels open; and whence the efferent set out. These are filled with a milky fluid, carried thither by the lacteals or exhaled by the blood-vessels.b Notwithstanding the labours of Nuck,c Hew- son, Abernethy, Mascagni, Cruikshank, Haller,'1 Beclard,6 and other distinguished anatomists, the texture of these, as well as of the lym- phatic glands or ganglions in general, is not demonstrated. All that we know is, that the chyliferous and sanguiferous vessels become extremely minute in their substance; and that the communication between the afferent and efferent vessels, through them, is very easy; as mercurial injections pass readily from the one to the other. The thoracic duct, g, Fig. 110, is formed by the junction of the chyliferous trunks with the lymphatic trunks from the lower extre- mities. The receptaculum chyli, already described, forms its com- mencement. After getting from under the diaphragm, the duct proceeds, in company with the aorta, along the right side of the b Sefop d? p'swa'' ^ BreSChCt' ^/f T W^68' Paris, 1836. iviuner, op. cu. p. ttz. c Adenoloeia, Lug-d Bat IfiQfi - Element. Physiol, ii. 3. . Addit. &tojj^ Jg ™* ^ CHYLIFEROUS APPARATUS. J 9 spine, until it reaches the fifth dorsal vertebra; where it crosses over to the left side of the spine, behind the oesophagus. It then ascends behind the left carotid artery; runs up to the interstice between the first and second vertebrae of the chest; where, after receiving the lymphatics, which come from the left arm and left side of the head and neck, it suddenly turns downwards, and termi- nates at the angle, formed by the meeting of the subclavian and internal jugular veins of the left side. To observe the chyliferous apparatus to the greatest advantage, it should be examined in an individual recently executed, or killed suddenly, two or three hours after having eaten; or in an animal, destroyed for the purpose of experiment, under the same circum- stances. The lacteals are then filled with chyle, and may>be readily recognised, especially if the thoracic duct has been previously tied. These vessels were unknown to the ancients. The honour of their discovery is due to Gaspard Aselli,a of Cremona, who, in 1622, at the solicitation of some friends, undertook the dissection of a living dog, which had just eaten, in order to demonstrate the recurrent nerves. On opening the abdomen, he perceived a multitude of white, very delicate filaments, crossing the mesentery in all direc- tions. At first, he took them to be nerves; but having accidentally cut one, he saw a quantity of a white liquor exude, analogous to cream. Aselli also noticed the valves, but he fell into an impor- tant error regarding the destination of the vessels;—making them collect in the pancreas, and from thence proceed to the liver. In 1628, the human lacteals were discovered. Gassendib had no sooner heard of the discovery of Aselli than he spoke of it to his friend Nicholas-Claude-Fabrice de Peiresc, senator of Aix; who seems to have been a most zealous propagator of scientific know- ledge. He immediately bought several copies of the work of Aselli, which had only appeared the year previously, and distributed them amongst his friends of the profession. Many experiments were made upon animals, but the great desire of De Peiresc was, that the lacteals should be found in the human body. Through his interest, a malefactor, condemned to death, was giv^n up, a short time before his execution, to the anatomists of Aix; who made him eat copi- ously; and, an hour and a half after execution, opened the body, in which, to the great satisfaction of De Peiresc, the vessels of Aselli were perceived, in the clearest manner. Afterwards, in 1634, John Weslingc gave the first graphic representation of the chyliferous ves- sels of the human body; and he subsequently indicated, more clearly than his predecessors, the thoracic duct and the lymphatics. Prior to the discovery of the chyliferous and lymphatic vessels, the veins, which arise in immense numbers from the intestines, and, by their union with other veins, form the vena porta, were esteemed the agents of absorption; and, even at the present day, they are consi- => De Lactibus seu Lacteis Venis, &e. Mediol. 1627; also, in Collect. Oper. Spigelii, edit. Van der Linden; and in Manget. Theatr. Anatom. b Vita Peirescii, in Op. omnia, v. 300. c Syntagm. Anatom. viii. 170. 20 ABSORPTION. dered, by some physiologists, to participate with the chyliferous vessels in the function;—with what propriety we shall inquire here- after.8 2. CHYLE. The chyle, as it circulates in the chyliferous vessels, has only been submitted to examination in comparatively recent times. The best mode of obtaining it is to feed an animal, and, when digestion is in full progress, to strangle it, or divide the spinal marrow beneath the occiput. The thorax must then be opened, through its whole length; and a ligature be passed round the aorta, oesophagus, and thoracic duct, as near the neck as possible. If the ribs of the left side be now turned back or broken, the thoracic duct is observed, lying against the oesophagus. By detaching the upper part, and cutting into it, the chyle flows out. A small quantity only is thus obtained; but, if the intestinal canal and chyliferous vessels be re- peatedly pressed upon, the flow may be sometimes kept up for a quarter of an hour. It is obviously impossible, in this way, to obtain the chyle pure; inasmuch as the lymphatics, from various parts of the body, are constantly pouring their fluid into the thoracic duct. From the concurrent testimony of various experimenters, the chyle is a liquid of a milky-white appearance; limpid and transpa- rent in herbivorous animals, but opaque in the carnivorous; neither viscid nor glutinous to the touch; of a consistence, varying some- what according to the nature of the food; of a spermatic smell; sweet taste, not dependent on that of the food; neither acid nor alkaline; and of a specific gravity, greater than that of distilled water, but less than that of the blood. Magendie,b Tiedemann and Gmelin,c and Muller,d however, state it to possess a saline taste; to be clammy on the tongue; and sensibly alkaline. The chemical character of the chyle has been examined by Em- mert,e Vauquelin,f Marcet,8 and Prout;h and is found to resemble that of the blood greatly. In a few minutes after its removal from the thoracic duct, it becomes solid; and, after a time, separates, like the blood, into two parts, a coagulum and a liquid. The coagu- lum is an opaque white substance; of a slightly pink hue; insoluble in water; but readily soluble in the alkalies, and alkaline carbonates. * See a history of these discoveries, by Dr. Meigs, in Philadelphia Journal, No. 2 New Series; Sprengel, Hist, de la Medecine, traduit par Jourdan, iv. 201, Paris 1815 • Chqulant, art. Lymphatisches System, in Pierer's Anat. Phys. Real. Worterb. iv. 895 Leipz. 1821. And Breschet, Le Systeme Lymphatique Considere sous les Rapports Anatomiques, Physiologiques, &c, Paris, 1836. >> Precis, &c. ii. 172. c Die Verdauung nach Versuchen, i. 353, Heidelb. 1826; or French translation by Jourdan, Paris, 1827. d Elements of Physiology, by Baly, p. 258, Lond. 1838. e Annales de Chimie, torn. lxxx. p. 81. 1 Ibid, lxxxi. 113; and Annals of Philosophy, ii. 220. s Med. Chirurg. Transactions, vol. vi. 618, Lond. 1815. h Thomson's Annals of Philosophy, xiii. 121, and 263. CHYLE. 21 Vauquelin regards it as fibrine in an imperfect state, or as inter- mediate between that principle and albumen; but Brande1 thinks it more closely allied to the caseous matter of milk than to fibrine. The analyses of Marcet and Prout agree, for the most part, with that of Vauquelin. Dr. Prout has detailed the changes, which the ohyle experiences in its passage along the chyliferous apparatus. In each successive stage, its resemblance to the blood was found to be increased. Another point of analogy with the blood is the fact, observed by Bauer,b and subsequently by Prevost and Dumasc— that the chyle, when examined by the microscope, contains the same globules as the blood ; differing from the latter only in their being but half the size, and devoid of the envelope of colouring matter. Although the chyle has essentially the same constituents, whatever may be the food taken, and separates equally into the clot and the serous portion, the character of the aliment may have an effect upon the relative quantity of those constituents, and thus exert an influence on its composition. That it scarcely ever con- tains adventitious substances we shall see hereafter; but it is ob- vious, that if an animal be fed on diet contrary to its nature, the due proportion of perfect chyle may not be formed; and that, in the same way, different alimentary articles may be very differently adapted for its formation. Leuret and Lassaigne,*1 indeed, affirm, that in their experiments they found the chyle to differ more accord- ing to the nature of the food than to the animal species; but that, contrary to their expectation, the quantity of fibrine, existing in the chyle, bore no relation to the more or less azoted character of the aliment. They assign it, as constituents, fibrine, albumen, fatty matter, soda, chloruret of sodium, and phosphate of lime. The chief object of Marcet's experiments was to compare the chyle from vegetable, with that from animal food, in the same ani- mal. The experiments, made on dogs, led him to the following re- sults. The specific gravity of the serous portion of the chyle is from 1.012 to 1.021, whether it be formed from animal or vegetable diet. Vegetable chyle, when subjected to analysis, furnishes three times more carbon than animal chyle. The latter is highly disposed to become putrid; and this change generally commences in three or four days; whilst vegetable chyle may be kept for several weeks, and even for months, without becoming putrid.*5 Putrefaction attacks rather the coagulum of the chyle than its serous portion. The chyle from animal, food is always milky; and, if kept at rest, an unctuous matter separates from it, similar to cream, which swims on the surface. The coagulum is opaque, and has a rosy tint. On the other hand, the chyle from vegetable food is almost * Phil. Transact, for 1812. b Sir E. Home, Op. cit. iii. 25. "= Biblioth. Universale de Geneve, p. 221, Juillet, 1821. J Recherches sur la Digestion, Paris, 1825. e Thenard has properly remarked, that the difference, in the time of putrefaction of these two substances appears very extraordinary. It is, indeed, inexplicable. Traite de Chimie Elementaire, &c. 5eme edit. Paris, 1827. 22 ABSORPTION. always transparent, or nearly so, like ordinary serum. Its coagulum is almost colourless, and resembles an oyster; and its surface is not covered with the substance analogous to cream. Magendie,a too, remarks, that the proportion of the three substances, into which the chyle separates, when left at rest;—namely, the fatty substance on the surface, the clot and the serum, varies greatly, according to the nature of the food; that the chyle, proceeding from sugar, for example, has very little fibrine; whilst that from flesh has more; and that the fatty matter is extremely abundant when the food con- tains fat or oil; whilst scarcely any is found if the food contains no oleaginous matter. Lastly,—the attention of Proutb has been directed to the sarhe comparison. He found, on the whole, less difference between the two kinds of chyle than had been noticed by Marcet. In his experiments, the serum of chyle was rendered turbid by heat, and a few flakes of albumen were deposited; but, when boiled, after admixture with acetic acid, a copious precipita- tion ensued. To this substance, which thus differs slightly from albumen, Dr. Prout gave the inexpressive name of incipient albu- men. The following is a comparative analysis, by him, of the chyle of two dogs, one of which was fed on animal, and the other on vegetable substances. Vegetable Food. Animal Food Water .... 93.6 89.2 Fibrine .... 0.6 0.8 Incipient albumen - 4.6 4.7 Albumen, with a red colouring matter 0.4 4.6 Sugar of milk a trace Oily matter .... a trace a trace Saline matters 0.8 0.7 100.0 1000.0 The difference between the chyle from food of such opposite character, as indicated by these experiments, is insignificant, and indicative of the great uniformity in the action of the agents of this absorption. More recent researches by Messrs. Macaire and Mar- cet,0 tend, indeed, to establish the fact, that both the chyle and the blood of herbivorous and of carnivorous quadrupeds are identical in their composition, in as far, at least, as regards their ultimate analysis. They found the same proportion of azote in the chyle, whatever kind of food the animal habitually consumed; and this was the case with the blood, whether of the carnivoraor herbivora ; but it contained more azote than the chyle. All these investigations into the nature of the chyle exhibit the inaccuracy of the view of Roose,d that the chyle and the milk are identical. 1 Op. citat. p. 174. >> Annals of Philosophy, xiii. 22, and Bridgewater Treatise, Amer. Edit p. 27-^ Philad. 1834. ' • r* ~i c Memoir, de la Societe de Physique et de l'Histoire Naturelle de Geneve v. 389 i Weber's Hildebrandt's Handbuch der Anatomie, i. 102, Braunschweig,'1830. CHYLE. 23 With regard to the precise quantity of chyle, that may be formed after a meal, we know nothing definite. When digestion is not going on, there can of course be none formed except from the digestion of the secretions from the digestive tube itself; and, after an absti- nence of twenty-four hours, the contents of the thoracic duct will be chiefly lymph. During digestion, the quantity of chyle formed will bear some relation to the quantity of food taken, the nutritive qualities of the food, and the digestive powers of the individual. Magendie,* from an experiment made on a dog, estimated, that at least half an ounce of chyle was conveyed into the mass of blood, in that animal, in five minutes; and the flow was kept up, but much more slowly, as long as the formation of chyle continued.11 3. PHYSIOLOGY OF CHYLOSIS. The facts just referred to—regarding the anatomical arrange- ment of the chyliferous radicles and mesenteric glands,—will suffi- ciently account for the obscurity of our views on many points of chylosis. The impracticability of detecting the mouths or extremities of the chyliferous radicles has been the source of different hypotheses; and, according as the view of open mouths or of the spongy gela- tinous tissue has been embraced, the chyle has been supposed to enter immediately into the vessels, or to be received through the medium of this tissue; or, again, to pass through the parietes of the vessels by imbibition. Let it be borne in mind, however, that not only the action of absorption, but the vessels themselves, are seen only by the "mind's eye;" and that the chyle does not seem to exist any where but in the chyliferous vessels. In the small intes- tine, we see a chymous mass, possessing all the properties we have described, but containing nothing resembling true chyle; whilst, in the smallest lacteal, which we can detect, it always possesses the same essential properties. Between this imperceptible portion of the vessel, then, and its commencement,—including the latter,—the elaboration must have been effected. Leuret and Lassaigne,c in- deed, affirm, that they have detected chyle in the chymous mass within the intestine, by the aid of the microscope. They state that globules appeared in it similar to those that are contained in the chyle, and that their dissemination amongst so many foreign matters alone prevents their union in perceptible fibrils. These globules they regard as true chyle,—for the reason, that they observed similar globules in the artificial digestions they attempted; and, on the other hand, never detected them in the digestive secretions. In their view, consequently, chyliferous absorption would be confined to the separation of the chyle, ready formed in the intestine, from 1 Op. citat. ii. p. 183. b See, on the character of the chyle, Mr. Ancell, Lectures on the Physiology and Pathology of the Blood, in London Lancet, Oct. 26, 1839, p. 150; and Mr. Lane, art. Lymphatic and Lacteal System, Cyclop, of Anat. and Phys., April, 1841. c Recherches Physiologiques et Chimiques, pour Servir & PHistoire de la Digestion, p. 60, Paris, 1825. 24 ABSORPTION. the excrementitious matters united with it. We have already more than once referred to the caution, which it is necessary to adopt, regarding minute microscopic researches; and to the difference, presented to the observer by glasses of different magnifying powers. We must have stronger evidence than this to set aside the over- whelming testimony in favour of an action of selection and elabo- ration by the absorbents of all organized bodies—vegetable as well as animal. The nutriment of the vegetable may exist in the soil and the air around it; but it is subjected to a vital agency the mo- ment it is laid hold of, and is decomposed to be again united, so as to form the sap. How else can we understand the conversion of the animal matters in the manure into the substance of the vegeta- ble? A like action is doubtless exerted by the chyliferous radicles;* and hence all the modes of explaining this part of the function, under the supposition of their being passive, mechanical tubes, are in- adequate. Boerhaaveb affirmed, that the peristaltic motion of the intestines has a considerable influence in forcing the chyle into the mouths of the vessels; whilst Dr. Younge is disposed to ascribe the whole effect to capillary attraction; and he cites the lachrymal duct as an analogous case, the contents of which, he conceives,— and we think with propriety,—are entirely propelled by capillary attraction. The objections to these views, as regards the chyliferous vessels, are sufficiently obvious. The chyle must, according to them, exist in the intestines; and, if the view of Boerhaave were correct, we ought to be able to obtain it from the chyme by pressure. As the chyle is not present, ready formed, in the intestine, the explanations by imbibition and by capillary attraction are equally inadmissible. There is no analogy between the cases of the lachrymal duct and the chyliferous vessels. In another part of this work, (vol. i. p. 213,) we have affirmed, that the passage of the tears, through the puncta lachrymalia, and along the lachrymal ducts, is one of the few cases in which capillary attraction can, with propriety, be invoked, for the explanation of functions executed by the human frame. In that case there is no conversion of the fluid. It is the same on the con- junctiva as in the lachrymal duct, but, in the case of the chyliferous vessels, a new fluid is formed; there must, therefore, have been an action of selection exerted; and this very action would be the means of the entrance of the new fluid into the mouths of the lacteals. If, therefore, we admit, in any manner, the doctrine of capillarv tubes, it can only be, when taken in conjunction with that of the' elabo- rating agency. "As far as we are able to judge," says Bostock.d "when particles, possessed of the same physical properties, are pre- sented to their mouths (the lacteals), some are taken up, while others are rejected; and if this be the case, we must conceive, in the first place, that a specific attraction exists between the vessel and the a F. Arnold, Lehrbuch der Physiologie des Menschen, Zurich, 1836-7 • and Brit and For. Med. Review, Oct. 1839, p. 479. b Proelect. Academ. in, prop. Instit. Rei Med. § 103. c Medical Literature, p. 42, Lond. 1813. d Physiol., edit. cit. 622, Lond. 1836. CHYLOSIS. 25 particles, and that a certain vital action must, at the same time, be exercised by the vessel connected with, or depending upon, its con- tractile power, which may enable the particles to be received within the vessel, after they have been directed towards it. This contrac- tile power m;iy be presumed to consist in an alternation of contrac- tion and relaxation, such as is supposed to belong to all vessels that are intended for the propulsion of fluids, and which the absorbents would seem to possess in an eminent degree." This is all specious: but it is not the less hypothetical. By other physiologists, absorption is presumed to be effected, by virtue of the peculiar' sensibility or insensible organic contractility or irritability of the mouths of the absorbents; but these terms, as Magendiea has remarked, are the mere expression of our igno- rance, regarding the nature of the phenomenon. The separation of the chyle is, doubtless, a chemical process; seeing that there must be both an action of decomposition and of recomposition; but it is not regulated, apparently, by the same laws as those that govern inorganic chemistry. It has already been said, that the chyle always possesses the same essential properties; that it may vary slightly according to the food, and the digestive powers of the individual, but that it rarely if ever contains any adventitious substance,—the function of the chyliferous vessels being restricted to the formation of chyle. The facts and arguments, in favour of this view of the subject, will be given here- after. The course of the chyle is, as we have described, along the chyli- ferous vessels, and through the mesenteric glands into the recepta- culum chyli or commencement of the thoracic duct; along which it passes into the subclavian vein. The chief causes of its progres- sion, are,—first of all, the inappreciable action, by which the chyli- ferous vessels form and receive the chyle into them. This formation being continuous, the fresh portions must propel those already in the vessels towards the mesenteric glands, in the same way as the ascent of sap in plants, during the spring, appears to depend solely on the constant absorbing action of the roots.b It is probable, too, that the vessels themselves are contractile :c such was the opinion of Sheldon/ Schneider, and Cruikshank.8 Mojonf considers, that when the longitudinal fibres, which he has observed in the lym- phatics, contract, they draw one sphincter nearer to another, whilst the oblique fibres diminish the diameter. All these fibres, taking their point d'appui in the circular fibres, dilate the superior sphincters by drawing the ci cumference downwards. By this method, the fluid that enters a lymphatic irritates the vessel, which contracts upon itself, diminishes its cavity, and sends on the fluid through the open sphinctei. A kind of peristaltic action, he conceives, exists in * Precis, cStc. ii. 179. b Breschet, Le Systeme Lymphatiqne, Paris, 1836. c Mnller's Hindbuch, u. s. w. and Baly's translation, i. 284, Lond. 1838. d History of the Absorbent System, p. 28, Lond. 1784. e Op. citat. c. 12. 1 Journ. de la Societe des Sciences Physiques, &c. Nov. 1833. VOL. II. 3 26 ABSORPTION. the lymphatics similar to that of the intestines, which may be ob- served very distinctly, he says, in the lacteal vessels of the mesen- terv of animals, if opened two or three hours after they have been well fed. Moreover, that the lacteals and lymphatics are possessed of a power of contraction, is corroborated by the following reasons. First. They are small; and tonic contractions are generally ad- mitted in all the capillary vessels. Secondly. The ganglions or glands, which cut them at intervals, would destroy the impulse given by the first action of the radicles; and hence require some contraction in the vessels to transport the chyle from one row of these ganglions to another. Thirdly. If a chyliferous vessel be .opened in a living animal, the chyle spirts out, which could not be effected simply by the absorbent action of the chyliferous radicles; and, fourthly;"in a state of abstinence, these vessels are found empty; proving, that notwithstanding there has been an interruption to the action of chylous absorption, the whole of the chyle has been pro- pelled into the receptaculum chyli. It is obvious, however, that most of these reasons would apply as well to the elasticity as to the muscularity of the outer coat of these vessels.1 A more forcible argument is derived from an experiment by Lauth.b He killed a dog, towards the termination of.digestion; and immediately opened its abdomen, when he found the intestines marbled, and the chyli- ferous vessels filled with chyle. Under the stimulation of the air, these vessels began to contract, and, in a few minutes, were no longer perceptible. The result he found to be the same, whenever the dissection was made within twenty-four hours after death: but, at the end of this time, the irritability of the chyliferous vessels was extinct; and they remained distended with chyle, notwithstanding the admission of air. These experiments lead to a deduction which seems, in the absence of less direct proof, scarcely doubtful;—that the chyliferous vessels possess a contractile action, bv the aid of which the chyle is propelled along the vessels. In addition to these propelling causes, the pulsation of the arteries in the neighbourhood of the chyliferous vessels; and the pressure of the abdominal mus- cles in respiration have been invoked. The former has probably less effect than the latter. It is not, indeed, easy to see how the former can be possessed of any. Of the agency of the latter we have experirnental evidence. If the thoracic duct be exposed in the neck of a living animal, and the course of the chyle be observed, it will be found accelerated at the time of inspiration, when the de- pressed diaphragm forces down the viscera; or when the abdomen of the animal is compressed by the hands. We shall find, too here- after, that the mode in which the thoracic duct opens into the sub- clavian exerts considerable effect on the progress of the chvle in its vessels. We have reason to believe that the course of the chvle is slow. It has been already stated, that in an experiment on a do», which * Adelon, Physiologie, <&c. iii. 31. b Essai sur les Vaisseaux Lymphat. Strasb. 1824. CHYLOSIS. 27 had eaten animal food at discretion, Magendiea found half an ounce of chyle discharged from an opening in the thoracic duct in five minutes. Still, as he judiciously remarks, the velocity will be partly dependent upon the quantity of chyle formed. If much enters the thoracic duct, it will probably proceed faster than under opposite circumstances. In the commencement of the thoracic duct the chyle becomes mixed with lymph. Under the head of lymphatic absorption we shall show how they proceed logether into the subclavian, and the effect produced by the circumstances under which the thoracic duct opens into that venous trunk. It has been a subject of inquiry,—and unfortunately a fruitless one with physiologists,—whether the chyle varies materially in different parts of its course, and what is the precise modification, impressed upon it by the action of the mesenteric glands. The experiments of Reuss, Emmert,b and others, seem to show, that when taken from the intestinal side of the mesenteric glands, it is of a yellowish-white colour, does not become red on being exposed to the air, and coa- gulates but imperfectly, depositing only a small, yellowish pellicle; whilst that, obtained from the other side of the glands, and near the thoracic duct, is of a reddish colour, coagulates entirely, and depo- sits a clot of scarlet-red colour. Vauquelin,0 too, affirms, that it acquires a rosy tint as it advances in the apparatus; and that the fibrine becomes gradually more abundant. These circumstances have given rise to the belief, that the chyle, as it proceeds, becomes more and more animalized, or transformed into the nature of the being to be nourished. This effect has generally been ascribed to the mesenteric glands; and it has been presumed by some to be pro- duced by the exhalation of a fluid into their cells, from the numerous blood-vessels with which they are furnished. Others, again, consider that the veins of the glands remove from the chyle every thing that is noxious, or purify it. From the circumstance, that the rosy colour of the chyle is more marked on the thoracic, than on the intestinal side of the glands ; that the fluid is richer in fibrine after having passed through those glands; and that the rosy colour and fibrine are less, when the animal has taken a larger proportion of food, MM. Tiedemann and Gmelind infer, that it is to the action of the glands, that the chyle owes those important changes in its nature; —the fluid, in its passage through them, obtaining, from the blood circulating in them, the new elements, which animalize it. These are the chief views, that have been entertained, regarding the use of the mesenteric glands. They are equally gratuitous with the notion, indulged by some, that they act as so many hearts, for the propulsion of the chyle towards the subclavian vein. We are, in truth, totally ignorant of their uses. » Precis, &c. ii. 183. b Reil's Archiv. viii. s. 2; and Annales de Chimie, Ixxx. 81. c Annales de Chimie, lxxxi. 113 ; and Annals of Philosophy, ii. 220. d Die Verdauung nach Versuchen, u. s. w., and Jourdan's translat. Paris, 1827. 28 ABSORPTION. In another place, the various hypotheses that have been indulged, regarding the spleen, will be noticed. It is proper, howe"ver, to refer to one, that has been recently proposed by MM. Tiedemann and Gmelin, but which is perhaps little less solid than its precursors. They consider the organ as a dependent ganglion of the absorbent system, which prepares a fluid, destined to be mixed with the chyle to effect its animalization. They assert that the chyle hardly coagu- lates, if at all, before it has passed through the mesenteric glands; but, after this, fibrine begins to appear, and is much more abundant after the addition of the lymph from the spleen, which contains a very large quantity of fibrine. Before passing the mesenteric glands, the "chyle contains no red particles; but it does so immediately after- wards, and more particularly after it is mixed with the lymph from the spleen, which abounds with them, and with fibrine. M. Voisin,1 who, as we have seen, considers that the chyliferous vessels ramify in the substance of the liver, thinks, that by the action of the liver, a species of purification is produced in the chyle, by which the lat- ter is better fitted to mingle with and form part of the blood. Prior to the discovery of the chyliferous vessels, the mesenteric veins were regarded as the agents of chylous absorption; and as these veins terminate in the vena porta, which is distributed to the liver, this last organ was considered the first organ of sanguifica- tion ; and to impress upon the chyle a first elaboration. In this view, the great size of the organ, compared with the small quantity of bile it furnishes, and the exception, which the mesenteric veins and vena porta present to the rest of the venous system, were accounted for,—as well as the large size of the liver in the fcetus, although not effecting any biliary secretion, and the fact of its receiving immediately the nutritive fluid from the placenta. This idea of the agency of the mesenteric veins is now nearly ex- ploded, but not altogether so. There are yet physiologists, and of no little eminence, who regard them as participators in the func- tion of chylosis with the chyliferous vessels themselves. Some of the arguments, used by these gentlemen, are:—First. The mesenteric veins form as much an integrant part of the villi of the intestine as the chyliferous vessels ; and they have, also, free orifices, in the cavity of the intestine. Lieberkiihn,b by throwing an injection into the vena porta, observed the fluid ooze out at the villi of the intestine ; and Ribesc obtained the same result by in- jecting spirit of turpentine coloured black. It is manifest, how- ever, that these experiments are insufficient to establish the fact of open mouths. Situate, as those vessels are, in an extremely loose tissue, which affords them but little support, the slightest iniectino- force might be expected to be sufficient to rupture their sides! Secondly. Chyle has often been found in the mesenteric veins. a Nouvel Apercu sur la Physiologie du Foie, &e. Paris, 1833 b Dissert, de Fabric. Villor. Intestin. Lugfd. Bat. 1745. ' c Memoir, de la Societe Medicale d'Emulation, viii. 621, CHYLOSIS. 2(J Swammerdam asserts, that, having placed a ligature round the mesenteric veins of a living animal, whilst digestion was going on, he saw whitish, chylous striae in the blood of those veins; and Tiedemann and Gmelin affirm, that they have often, in their experi- ments, observed the same appearance.3 If the fact of the identity of these striae with chyle were well established, we should have to bend to the weight of evidence. This is not, however, the case. These gentlemen afford us no other reason for the belief, than the colour of the striae. The arguments against the mesenteric veins having the power of forming chyle we think irresistible. A separate apparatus exists, manifestly for this purpose, which scarcely ever con- tains any thing but chyle; and consequently, it would seem unneces- sary, that the mesenteric veins should participate in the function, espe- cially as the fluid, which circulates in them, is most heterogeneous; and, as we shall see, a compound of various adventitious and other absorptions. Granting, however, that these stria? are truly chyle, it would, it is affirmed, by no means, follow absolutely, that it should be formed by the mesenteric veins. It is possible, that a communi- cation may exist between the chyliferous vessels and these veins. Wallaeus1' asserts, that having placed a ligature on the lymphatic trunks of the intestine, chyle passed into the vena portae. Rosen, Meckel,0 and Lobstein, affirm that by the use of injections they also detected this inosculation. Lippid states, that the chyliferous vessels have numerous anastomoses with the veins, not only in their course along the mesentery before they enter the mesenteric glands; but also in the glands themselves. Tiedemann and Gmelin concur in the existence of this last anastomosis, and Leuret and Lassaigne found that a ligature applied round the vena portae occasioned the reflux of blood into the thoracic duct. A. Meckel, E. H. Weber, Rudolphi and J. Muller doubt, however, the existence of an actual open communication between the lymphatics and minute veins in the glands. Meckel states, as a reason for his questioning a real communication, that when the seminal duct of the epididymis of the dog is injected, the veins also are filled; and Muller6 observes, that when glands are injected from their excretory duct, the small veins of the gland also frequently become filled with the mercury; and the cases in which this occurred to him were always those in which the ducts had not been well filled,—their acini not distended. Thirdly. That the ligature of the thoracic duct has not always induced death, or has not induced it speedily; and, consequently, that the tho- racic duct is not the only route, by which the chyle can pass to be * Elemens de Physiologie, 13eme edit., par Berard aine, § xxxvii. p. 90, Bruxelles, 1837. b Medica Omnia, &c. ad Chyli et Sanguinis Circul. Lond. 1660. c Diss. Epist. ad Haller. de Vasis Lymph. &c. Berol. 1757 ; Nov. Exper de Finibus Vcnarum et Vas. Lymph. Berol. 1772; and Manuel d'Anitomie, &c., French edit. by Jourdin, i. 17!). d Illustrazioni Fisiologiche e Patologiche del Sistema Limfatico-Chilifero, Firenze, 1825. e Handbuch, u. s. w.; and Baly's translation, p. 273, Lond. 1838. 3* 30 ABSORPTION inservient to nutrition. In an experiment of this kind by Duverney, the dog did not die for fifteen days. Flandrin repeated if on twelve horses, which appeared to eat as usual, and to keep their flesh. On killing them and opening them a fortnight afterwards, he satisfied himself, that the thoracic duct was not double. Sir Astley Cooper likewise performed the experiment on several dogs: the majority lived longer lhan a fortnight, and none died in the two first days; although, on dissection, the duct was found ruptured and the chyle effused into the abdomen. The experiments of Dupuytren have satisfactorily accounted for these different results. He tied the thoracic duct in several horses. Some died in five or six days, whilst others continued apparently in perfect health. In those, that died in consequence of the ligature, it was impossible to send any injection from the lower part of the duct into the subclavian vein. It was, therefore, presumable, that the chyle had ceased to be poured into the blood, immediately after the duct was tied. On the other hand, in those, that remained apparently unaffected, it was always easy to send mercurial or other injections from the abdominal por- tion of the duct into the subclavian. The injections followed the duct until near the ligature; when they turned off, entering into large lymphatic vessels, which opened into the subclavian vein, so that, in these cases, the ligature of the thoracic duct had not pre- vented the chyle from passing into the venous system; and, thus, we can understand why the animals should not have perished." From every consideration, then, it appears that the chyliferous vessels are the sole organs concerned in chylosis; and we shall see presently, that they refuse the admission of other substances, which must, consequently, reach the circulation through a different channel.b b. Absorption of Drinks. It has been stated, that a wide distinction exists between the gas- tric and intestinal operations that are necessary in the case of solid food and liquids. Whilst the former is converted into chyme and passes into the small intestine, 10 have its chylous parts sepa- rated from it; the latter, according to their constitution, may either be wholly absorbed or be divided into two portions—if they be animal or vegetable infusions,—the animal or vegetable substance being subjected to chymification, whilst the watery portion, with its saline accompaniments,—if any such exist,—is absorbed from the stomach or small intestine. The chyliferous vessels, we have seen, are the agents-and the exclusive agents of the absorption of the chyle or nutritive product from the digestion of solids: what then, are the agents of the ab- a Richerand's Elemens de Physiologie, edit. cit. p. 90. b Chaussier et Adelon, art. Lymphatique, in Diet, des Sciences Medicales- Adelon Physiologie de I'Homme, 2de edit. iii. 43, Paris, 1829; and art. Cliylifbres in Diet, de Modecine, 2de edit., Paris, 1832. OF DRINKS. 31 sorption of liquids? There are but two sets of vessels, on which we can rest for a moment. These are the lacteals or lymphatics of the digestive tube; and the veins of the same canal. But, it has been seen, the chyliferous vessels refuse the admission into their interior of every thing but chyle. It would necessarily follow, then, that the absorption of liquids must be a function of the veins. Such is the conclusion of many distinguished physiologists, and on inferences that are logical. The view is not, however, universally, or perhaps generally, admitted; some assigning the function exclusively to the lacteals; others sharing it between them and the veins. But let us inquire into the facts and arguments, adduced in support of these different opinions. The advocates for the exclusive agency of the chyliferous system affirm, First, That whatever is the vascular system, which effects the absorption of drinks, it must communicate freely with the cavity of the intestine; and that the chyliferous system does this. Secondly, That this system of vessels is the agent of chylous absorption:—a presumption, that it is also the agent of the absorption of drinks. Thirdly, That every physiologist, who has examined the chyle, has described its consistence to be in an inverse ratio with the quantity of drink taken; and, lastly, that when coloured and odorous substances have been conveyed into the in- testine, they have been found in the chyliferous vessels and not in the mesenteric veins. The experiments, however, adduced in favour of this last position are so few and inadequate, that it is surprising they could have, for a time, so completely overturned the old theory. This effect was greatly aided by the zeal and ability of the Hunters, and of the Windmill Street School in general, who were the chief improvers of our knowledge regarding the anatomy of the lym- phatic system. John Hunter,"—who was one of the first, that posi- tively denied absorption by the veins and admitted that of the lymphatics,—instituted the following ingenious and imposing expe- riment. He opened the abdomen of a living dog; laid hold of a portion of intestine, and pressed out the matters it contained with the hand. He then injected warm milk into it, which he retained by means of ligatures. The veins, belonging to the portion of in- testine, were emptied of their blood by puncturing their trunks; and were prevented from receiving fresh blood, by the application of ligatures to the corresponding arteries. Tbe intestine was then returned into the cavity of the abdomen; and, in the course of half an hour, was again withdrawn and scrupulously examined; when the veins were found still empty, whilst the chyliferous vessels were full of a white fluid. Hunter subsequently repeated the experiment with odorous and coloured substances, but without ever being able to detect them in the mesenteric veins. It may be remarked, also, that Musgrave,b Lister,0 Blumenbach,d Seiler and Ficinus assert,6 a Observations on certain parts of the Animal Economy, by John Hunter, F. R. S., with notes by Richard Owen, F. R.S., Bell's Library Edit. p. 307, Philad. 1840. b Pliilosoph. Transact, for 1701, p. 996. c Philosoph. Transact. 1701, p. 819. d Instit. Physiol. § 422. e Journal Complement, xviii. 327. 32 ABSORPTION that they have detected substances in the chyle of the thoracic duct, which had been thrown into the intestines of animals. The experiments of Hunter, however, are those, on which the supporters of this view of the question principally rely. Those physiologists, who believe in absorption of liquids by the mesenteric veins, invoke similar arguments and much more nume- rous experiments. They affirm, that the mesenteric veins, like the chyliferous vessels, have free orifices in the cavity of the intestine, and form constituent portions of the villi; whilst some of them con- ceive even this arrangement to be unnecessary, and that the fluids can readily pass through the coats of the vessels;—that if the chy- liferous system is manifestly an absorbent apparatus, the same may be said of the venous system ;—that if the chyle has appeared to be more fluid after much drink has been taken, Boerhaave affirms, that he has seen the blood of the mesenteric veins more fluid under like circumstances; and, lastly, against the experiments of Hunter, nu- merous others have been adduced, clearly showing, that liquids, injected into the intestine, have been found in the mesenteric veins, whilst they could not be detected in the chyliferous vessels. To the first experiment of Hunter it has been objected ;—that the art of performing physiological experiments was, in his time, imper- fect; and that, in order to deduce any useful inferences from it, we ought to know, whether the animal was fasting at the time it was opened, or whether digestion was going on; that the state of the lymphatics ought to have been examined at the commencement of the experiment, to see whether they were full of chyle, or empty; as well as the milk, to notice whether any changes had super- vened, during ite stay in the intestine: lastly, that the reasons should have been assigned for the belief that the lacteals were filled with milk at the end of the experiment, and not with chyle. The experiment, moreover, has been repeated several times by Flandrin, and by Magendie,*—both of them dexterous experimenters,—yet, in no case, was the milk found in the chyliferous vessels. This first experiment of Hunter cannot, therefore, be looked upon as satisfactory. Some illusion must have occurred,—some source of fallacy,—or, otherwise, a repetition of the experiment should have been attended with like results. We shall find, hereafter, that in another experiment, by that distinguished individual, a source of illusion existed, of which he was unaware, but which was sufficient to account for the appearances he noticed. The experiments of Hunter, with the odorous and coloured sub- stances, have been likewise repeated by many physiologists, and found to be even less conclusive than that with the milk. Flandrin, who was professor in the Veterinary School at Alfort, in France^ thought that, in horses, he could detect an herbaceous odour, in the blood of the mesenteric veins, but not in the chyle. He gave to a horse a mixture of half a pound of honey, and the same quantity of * Precis, &c., edit, citat. ii. 201. OF DRINKS. 33 asafoetida ; and, whilst the smell of the latter was distinctly percep- tible in the venous blood of the stomach and intestine, no trace of it existed in the arterial blood and chyle. Sir Everard Home1 having given the tincture of rhubarb to an animal, around whose thoracic duct he had placed a ligature, found the rhubarb in the bile and in the urine. Magendie gave to dogs, whilst they were digesting, a quantity of alcohol, diluted with water, and solutions of camphor, and other odorous fluids: on examining the chyle, half an hour afterwards, he detected none of those substances, whilst the blood in the mesenteric veins manifestly exhaled the odour, and afforded the substances by distillation. lie gave to a dog four ounces of a decoction of rhubarb; and, to another, six ounces of a solution of the prussiate of potassa in water. Half an hour afterwards, no trace of these substances was detected in the fluid of the thoracic duct, whilst they were contained in the urine. On another dog, he tied the thoracic duct, and then gave it two ounces of a decoction of nux vomica. Death occurred as speedily as in a dog, in which the thoracic duct was pervious. The result was the same, when the decoction was thrown into the rectum, where no proper chyliferous vessels perhaps exist. Having tied the pylorus in dogs, and conveyed fluids into their stomachs, absorption equally took place, and with the same results. Lastly, with M. Delilleb he performed the fol-. lowing experiment on a dog, which had been made to eat a consi- derable quantity of meat previously, in order that the chyliferous vessels might be easily perceived. An incision was made in the abdominal parietes; and a portion of the small intestine drawn out, on which two ligatures were applied, at a short distance from each other. The lymphatics, which arose from this portion of the intes- tine, were very white, and apparent, from the chyle that distended them. Two ligatures were placed around each of these vessels; and the vessels divided between the ligatures. Every precaution was taken, that the portion of the intestine, drawn out of the abdo- men, should have no connexion with the rest of the body by lym- phatic vessels. Five mesenteric arteries and veins communicated with this portion of the intestine. Four of the arteries and as many veins were tied and cut, in the same manner as the lymphatics. The two extremities of the portion of intestine were now divided, and separated entirely from the rest of the small intestine. A portion of small intestine, an inch and a half long, thus remained attached to the body by a mesenteric artery and vein only. These two ves- sels were separated from each other by a distance of four fingers' breadth; and the cellular coat was removed to obviate the objection, that lymphatics might still exist in it. Two ounces of a decoction of nux vomica were now injected into this portion of intestine, and a ligature was applied to prevent the exit of the injected liquid. The intestine, surrounded by fine linen, was replaced in the abdo * Lectures on Comparative Anatomy, i. 221, Lond. 1814. b Precis, &c. ii. 203. 34 ABSORPTION men; and, in six minutes, the effects of the poison were manifested with their ordinary intensity; so that every thing occurred as if the intestine had been in its natural condition. Segalas3 periormed a similar experiment, leaving the intestine, however, communicating with the rest of the body by chyliferous vessels only. On injecting a solution of half a drachm of "the alcoholic extract of nux vomica into the intestine; the poisoning, which, in the experiment of Ma- gendie, took effect in six minutes, had not occurred at the expiration of half an hour; but when one of the veins was untied and the circulation re-established, it supervened immediately. Westrumbb mixed rhubarb, turpentine, indigo, prussiate of potassa and acetate of lead in the food of rabbits, sheep and dogs. They were detected in the veins of the intestines and in the urine, but not in the chyle. The same facts were observed by Mayer,0 when rhubarb, saffron, and prussiate of potassa were introduced into the stomach. MM. Tiedemann and Gmelin likewise observed the absorption of different colouring and odorous substances from the intestinal canal to be effected, exclusively, by the veins. Indigo, madder, rhubarb, cochi- neal, litmus, alkanet, camboge, and verdigris: musk, camphor, alco- hol, spirit of turpentine, Dippel's animal oil, asafoetida and garlic, the salts of lead, mercury, iron and baryta, were found in the venous blood, but never in the chyle. The prussiate of potassa and sulphate of potassa were the only substances, which, in their experi- ments, entered the chyliferous vessels. Such are the chief facts and considerations, on which the believers in the chyliferous absorption and in the venous absorption of drinks rest their respective opinions. The strength, we think, is manifestly with the latter. Let it be borne in mind, that no sufficient experi- ments have been recently made, which encourage the idea, that any thing is contained in the chyliferous vessels except chyle; and that nearly all are in favour of absorption by the mesenteric veins. An exception to this, as regards the chyliferous and lymphatic vessels, seems to exist in the case of certain salts. The prussiate and the sul- phate of po'assa—we have said—were detected in the thoracic duct by MM. Tiedemnnn and Gmelin ; the sulphate of iron and the prus- siate of potassa by Messrs. Harlan, Lawrence and Coatesd of Phila- delphia; and the last of these salts by Dr. Macneven of New York. "I triturated," says Dr. Macneven,6 "one drachm of crystallized hydrocyanate of potassa with fresh butter and crumbs of bread, which being made into a bolus, the same dog swallowed and re- tained. Between three and four hours afterwards, Dr. Anderson bled him largely from the jugular vein. A dose of hydrocyanic acid * Magendie's Journal de Physiologie, torn. ii.; and Precis, &c. ii. 208. b De Phasnomenis, qua} ad Vias sic dictas Lotii clandestinas referuntur Gottinff 1819. ' s' c Ueber das Einsaugungsvermogen der Venen, u. s. w. in Meckel's Archiv. Band. iii. • also, C. Windischmann, in art. Einsaugung, of Encycl. Worterb. x. 299 Berlin 1834' d Philad. Journ. of Med. and Phys. Sciences, vol. ii.; and Harlan's' Medical and Physical Researches, p. 458, Philad. 1835. e New York Med. and Phys. Journ. June, 1822. OF DRINKS. 35 was then administered, of which he died without pain, and the abdo- men was laid open. The lacteals and thoracic duct were seen well filled with milk-white chyle. On scratching the receptaculum, and pressing down on the duct, nearly half a tea-spoonful of chyle was collected. Into this were let fall a couple of drops of the solution of permuriate of iron, and a deep blue was the immediate conse- quence."a J. Mullerb placed a frog with its posterior extremities in a solution of prussiate of potassa which reached nearly as high as the anus, and kept it so for two hours. He then carefully washed the animal, and, having wiped the legs dry, tested the lymph taken from under the skin with a persalt of iron ; the lymph assumed immediately a bright blue colour, while the colour of the serum of the blood was scarcely perceptibly affected by the test. In a second experiment, in which the frog was kept only one hour in the solution, the salt could not be detected in the lymph. These very exceptions are strikingly corroborative of the rule. Of the various salts employed, these alone appear to have been detected in the chyle of the thoracic duct. It is, therefore, legitimately presumable, that they entered adventitiously, and probably by simple mechanical imbibition;—the mode in which venous absorption seems to be effected. The property of imbibition, possessed by animal tissues, has already been the subject of remark. (Vol. I. p. 46.) It was there shown, that they are not all equally penetrable: and that different fluids possess different penetrative powers. This view is confirmed by the experiments of Tiedemann and Gmelin on the subject en- gaging us. Although various substances were placed in the same part of the intestinal canal, they were not all detected in the blood of the same vessels. Indigo and rhubarb, for example, were found in the blood of the vena portae. Camphor, musk, spirit of wine, spirit of turpentine, oil of Dippel, asafcetida, garlic, not in the blood of the intestines, but in that of the spleen and mesentery ; the prus- siates of iron, lead and potassa in that of the veins of the mesen- tery; those of potassa, iron and baryta in that of the spleen; the prussiate of potassa, and the sulphates of potassa, iron, lead and baryta in the vena portae as well as in the urine; whilst madder and camboge appear to have been found in the latter fluid only. The evidence, in favour of the action of the chyliferous vessels being restricted to the absorption of chyle, whilst the intestinal veins take up other matters, is not, however, considered by some to be as decisive as it is by us. Adelon,c for example, concludes, that, as the sectators, on both sides, employ absolutely the same arguments, we are compelled to admit, that the two vascular systems are under exactly similar conditions; and that both, consequently, participate in the function. We have seen, that whatever may be the simi- larity of the arguments, the facts are certainly not equal.d It is a See, also, Ducachet, in New York Med. and Phys. Journal, No. 2, April, 1822. b Hmdbuch der Physiologie, u. s. w. Baly's translation, p. 279, Lond. 1838. c Physiologie de I'Homme, edit. cit. iii. 111. d Bostock's Physiol. 3d edit. p. 607, Lond. 1836. 36 ABSORPTION proper, however, to remark, that all chemical analysis have found great difficulty in detecting inorganic matters when mixed with certain of the compounds of organization ; and this may account for substances not having been detected in the thoracic duct, even when they have been present there. . With regard to the mode in which the absorption of fluids is effected, a difference of opinion has existed, chiefly as regards the question,—whether any vital elaboration is concerned, as in the case of the chyle, or whether the fluid, when it attains the interior of the vessel, is the same as without. The arguments in favour of these different views will be detailed under the head of venous ab- sorption. We may merely observe, at present, that water,—the chief constituent of all drinks,—is an essential component of every circulating fluid; that we have no positive evidence, that any ac- tion of elaboration is exerted upon it; and that the ingenious and satisfactory experiments of Dr. J. K. Mitchell,1 have shown, that it penetrates most, if not all, animal tissues better than any other liquid whatever; and, consequently, passes through them to accu- mulate in any of its own solutions. It is probably in this way,— that is, by imbibition,—that all venous absorptions are effected. But it has been said, if fluids pass so readily through the coats of the veins;—by reason of the extensive mucous surface, with which they come in contact, a large quantity of extraneous and hetero- geneous fluid must enter into the abdominal venous system, when we drink freely; and the composition of the blood be consequently modified; and if it should arrive, in this condition, at the heart, the most serious consequences might result. It has, indeed, been affirmedb by a distinguished member of the profession, in this country, in a more ingenious than forcible argument to support a long-cherished hypothesis, that " it must at least be acknowledged, that no substance, in its active state, does reach the circulation, since it is shown, that a small portion, even of the mildest fluid, as milk or mucilage, oil or pus, cannot be injected into the blood- vessels without occasioning the most fatal consequences." But the effects are greatly dependent upon the mode in which the injection is made. If a scruple of bile be sent forcibly into the crural vein. the animal will generally perish in a few moments. The same occurs, if a small quantity of atmospheric air be rapidly introduced into that vessel. The animal, indeed, according to*Sir Charles Bell,c dies in an instant, when a very little air is blown into the veins; —and there is no suffering nor struggle, nor any stage of transition,' so immediately does the stillness of death take possession of every part of the frame. In this way, according to Beauchene, Larrey, Depuytren, Warren of Boston, Mott and Stevens of New York! Delpech, and others, operations sometimes prove fatal-__the air being drawn in by the divided veins. If, however, the scruple of bile * American Journal of the Medical Sciences, vii. 44, 58. b Prof. Chapman, in Elements of Therapeutics, 6th edit n 47 PhilaH i«ii <= Animal Mechanics, P. ii. p. 42, Lond. 1829. " ' X' OF DRINKS. 37 or the same quantity of atmospheric air be injected into one of the branches of the vena portae, no apparent inconvenience is sustained. Magendie* concludes, from this fact, that the bile and atmospheric air, in their passage through the myriads of small vessels, into which the vena portae divides and subdivides in the substance of the liver, become thoroughly mixed with the blood, and thus arrive at the vital organs in a condition to be unproductive of mischief. This view is rendered the more probable by the fact, that if the same quantity of bile or of air be injected very slowly into the crural vein, no perceptible inconvenience is sustained. Dr. Blundellb injected five drachms into the femoral vein of a very small dog, with only tem- porary inconvenience, and subsequently three drachms of expired air, without much temporary disturbance.0 M. Lepelletierd affirms, that in the amphitheatre of the Ecole Pratique of Paris, in the presence of upwards of two hundred students, he injected thrice into the femoral vein of a dog, of middle size, at a minute's interval, three cubic inches of air, each time, without observing any other effect than struggling, whining, and rapid movements of deglutition, and these symptoms existed only whilst the injection was going on. Since that he has often repeated the experiment with identical results,—" proving," he observes, " that the deadly action of the air is, in this case, mechanical, and that it is possible to prevent the fatal effects by injecting so gradually, that the blood has power to disseminate, and perhaps even to dissolve the gas with sufficient promptitude to prevent its accumulation in the cardiac cavities."6 As liquids are frequently passed off by the urinary organs soon after they have been taken, it has been believed by some,—either that there are vessels, which form a direct communication between the stomach and bladder; or that a transudation takes place through the parietes of the stomach and intestine, and that the fluids pro- ceed through the intermediate cellular tissue to the bladder. Both these views, we shall hereafter show to be devoid of foundation. In those animals, in which the cutis vera is exposed, or the cuticle very thin, nutritive absorption is effected through that envelope. In the polypi, medusae, radiaria, and vermes, absorption is active, and * Precis Elementaire, 2de edit. ii. 433. b Medico-Chirurgical Transactions, for 1818, p. 65. c Sec, also, Nystcn, Rccherches de Physiol, et Chimie Pathologique, Paris, 1811. d Physiologie Medicale et Philosophique, i. 494, Paris, 1831. e See Seiler, in art. Leber, in Pierer's Anat. Phys. Real Worterb. iv. 736, Leipz. 1821; also, B. F. Wing, in Boston Med. and Surg. Journal, May 14, 1834; Poiseuille, in Gazette Medicale de Paris, Oct. 21, 1837; Denot. ibid. Nov. 1837; Amussat and Bouillaud, ibid. Dec. 2, 1837; Gerdy, ibid. Dec. 9, 1837; Velpeau, ibid. Fev. 24, 1838; and Dunglison's Amer. Med. Intelligencer for May 15, and June 1, 1838. In this paper, M. Velpeau examines critically into the different cases of the introduction of air into the veins during operations, that had occurred up to the time he wrote. See, also, M. Bouillaud's Report on Experiments relative to the Introduction of Air into the Veins, by M. Amussat, in Bull, de I'Academ. Royale de Medecine, ii. 12 ; and in Brit, and For. Med. Rev. Oct. 1838, pp. 455 and 517 ; and Dr. J. C. Warren, art. Air, American Cyclopedia of Practical Medicine and Surgery, P. iii. 263, Philad. 1834; Surgical Observations on Tumours, p. 259, Boston, 1837; and in Gazette Medicale de Paris, Dec. 30, 1837. VOL. II. 4 38 ABSORPTION. according to Zeder and Rudolphi,a those entozoa, that live in the midst of animal humours, imbibe them through the skin. A few years ago, Jacobsonb instituted experiments on the absorbing power of the helix of the vine, {Limacon des vignes). A solution of Prussiate of potassa was poured over the body. This was rapidly absorbed, and entered the mass of blood in such quantity, that the animal ac- quired a deep blue colour, when sulphate of iron was throvyn upon it. In the frog, toad, salamander, &c. the cutaneous absorption is so considerable, that occasionally the weight of water, taken in in this way, is equal to that of the whole body. We shall see, hereafter, that the nutrition of the foetus in utero is mainly, perhaps, accom- plished by nutritive-absorption effected through the cutaneous enve- lope. ABSORPTION OF LYMPH, OR LYMPHOSIS. This function is effected by agents, which strongly resemble those concerned in the absorption of chyle. One part of the vascular appa- ratus is, indeed, common to both,—the thoracic duct. We are much less acqainted, however, with the physiology of lymphatic, than of chyliferous, absorption. 1. ANATOMY OF THE LYMPHATIC APPARATUS. The lymphatic apparatus consists of lymphatic vessels, lymphatic glands or ganglia, and thoracic duct. The latter, however, does not form the medium of communication between all the lymphatic vessels and the venous system. 1. Lymphatic vessels.—These vessels exist in almost all parts of the body; and have the shape of cylindrical, transparent, membra- nous tubes, of small size, and anastomosing freely with each other, so as to present, every where, a reticular arrangement. They are never, according to Muller, so small as the arterial and venous ca- pillaries, and are almost without exception visible to the naked eye. G. R. Treviranus asserts, that their walls, like the cellular mem- brane and other tissues, are made up of minute elementary cylin- ders, of a diameter of about 0.001 millemetres to 0.006, placed in a series side by side and end to end, so as to constitute tubes which form networks, and open into larger lymphatic trunks. They are extremely numerous; more so, however, in some parts than in others. It is not certain that they have yet been found in the brain, spinal marrow, eye, internal ear, &c.; but this is no proof that they do not exist there. It may be merely an evidence that they are so minute as to escape observation.0 In their progress towards the venous system, they go on forming fewer and fewer trunks; yet a Entozoorum Histor. i. 252, 275. b Tiedemann, Traite Complet de Physiologie de I'Homme, Fr. Edit. p. 242, Paris, 1831 See, also, Jacobson, in Memoir, de l'Acad. des Sciences de Berlin 1825! c Weber, in Hildebrandt's Anatomie, iii. 94, Braunschweig, 1831; Muller Hand- buch, u. s. w. i. 250, or Baly's translation, p. 264, Lond. 1838; and Breschet Le Svs- teme Lymphatique, &c. Paris, 1836- ' LYMPHOSIS. 39 they always remain small. This uniformity in size is peculiar to them. When an artery sends off a branch, its size is sensibly dimi- nished ; and when a vein receives a branch, it is enlarged; but when a lymphatic ramifies, there is, generally, little change of size, whe- ther the branch given off be large or small. The lymphatics consist of two planes,—the one superficial, the other deep-seated. The former creep under the outer covering.of the organ, or of the skin, and accompany the subcutaneous veins. The latter are seated more deeply in the interstices of the muscles, or even in the tissue of parts, and accompany the nerves and great vessels. These planes anastomose with each other. This arrange- ment occurs not only in the limbs, but in the trunk, and in every viscus. In the trunk,the superficial plane is seated beneath the skin; and the deep-seated between the muscles and the serous membrane that lines the splanchnic cavities. In the viscera, one plane occupies the surface, the other appears to arise from the parenchyma. The two great trunks of the lymphatic system, in which the lymphatic vessels of the various parts of the body terminate, are the thoracic duct, and the great lymphatic trunk of the right side. The course of the thoracic duct has already been described. It is formed of three great vessels;—one, in which all the lymphatics and lacteals of the intestines terminate; and the other two, formed by the union of the lymphatics of the lower half of the body. Occasionally, the duct consists of several trunks, which unite into one before reaching the subclavian vein; but more frequently it is double. In addition to the lymphatics of the lower half of the body, the thoracic duct receives a great part of those of the thorax, and all those from the left half of the upper part of the body. At its termination in the subclavian, there is a valve, so disposed as to allow the lymph to pass into the blood; and to prevent the reflux of the blood into the duct. We shall see, however, that its mode of termination in the venous system possesses other advantages. The other trunk is formed by the absorbents from the right side of the head and neck, and from the right arm. It is very short, being little more than an inch, and sometimes not a quarter of an inch, in length, but of a diameter nearly as great as the thoracic duct. A valve also exists at the mouth of this trunk, which has a similar arrangement and office with that of the left side. The lymphatics have been asserted to be more numerous than the veins: by some, indeed, the proportion has been estimated at four- teen superficial lymphatics to one superficial vein; whence it has been deduced, that the capacity of the lymphatic system is greater than that of the venous. This must, of course, be mere matter of conjecture. The same may be said of the speculations that have been indulged regarding the mode in which the lymphatic radicles arise,—whether by open mouths or by some spongy mediate body. The remarks made, regarding the chylous radicles, apply with equal force to the lymphatic.3 * Sec, also, Windischmann, in art. Einsaugende Gefosse, in Encyclopad. Worterb. u. s. w., x. 287, Berlin, 1834. 40 ABSORPTION. It has been a matter of some interest to determine, whether the lymphatic vessels have not other communications with the venous system than by the two trunks just described; or, whether, soon after their origin, they do not open into the neighbouring veins,— an opinion which has been enunciated by many of those who believe in the doctrine of absorption by the lymphatics exclusively, in .order to explain why absorbed matters are found in the veins. Many of the older, as well as more modern, anatomists have pro- fessed a similar opinion; whilst it has been strenuously combated by Sommering, Rudolphi,a and others. Vieussens affirmed, that, by- means of injections, lymphatic vessels were distinctly seen to origi- nate from the minute arteries, and to terminate in the small veins. Sir William Blizardb asserts, that he twice observed lymphatics terminating directly in the iliac veins. Mr. Bracy Clarke0 found the trunk of the lymphatic system of the horse to have several open- ings into the lumbar veins. Ribes,1' by injecting the supra-hepatic veins, saw the substance of the injection enter the superficial lym- phatics of the liver. Alarde considers the lymphatic and venous systems to communicate at their origins. Vincent Fohmann/that the lymphatic vessels communicate directly with the veins, not only in the capillaries, but in the interior of the lymphatic glands. Lauth,& of Strasbourg,—who went to Heidelberg to learn from Foh- mann his plan of injecting,—announced the same facts in 1824. By this anatomical arrangement, Lauth explains how an injection, sent into the arteries, reaches the lymphatics, without being effused into the cellular tissue; the injection passing from the arteries into the veins, and thence, by a retrograde route, into the lymphatics. Beclard believed, that this communication exists at least in the interior of the lymphatic glands; and he supported his opinion by the fact, that in birds, in which these glands are wanting, and are replaced by plexuses, the lymphatic vessels in these plexuses are distinctly seen to open into the veins. Lippi,h has made these communications the express subject of a work. According to him, the most numerous exist between the lymphatic vessels of the abdomen and the vena cava inferior and all its branches. So nu- merous are they, that every vein receives a lymphatic vessel, and the sum of all those vessels would be sufficient ro form several tho- racic ducts. Opposite the second and third lumbar vertebrae these lymphatic vessels are manifestly divided into two orders:__some ascending, and emptying themselves into the thoracic duct; others 3 Grundriss der Physiologie, u. s. w., Berlin, 1821. b Physiological Observations on the Absorbent System of Vessels, Lond 1787 c Rees's Cyclopedia, art. Anatomy, Veterinary. d Magendie, Precis' &c ii 938 * Du siege et de la nature des maladies, ou nouvelles considerations' toucha'nt la veritable action du Systeme Absorbant, &c., Paris, 1821. f Ueber die Verbindung der Saugadern mit'den venen, Heidelb 18°] nnd TH« Saugadersystem der Wirbelthiere, Heft 1, Heidelb. 1824; Mem. sur* les "co'mmunica tions des vaisseaux lymphatiques avec les veines, Liege, 1832. s Essai sur les Vaisseaux Lymphatiques, Strasbourg, 1824. h Illustrazioni Fisiologiche, &c., Firenz., 1825. LYMPHATIC APPARATUS. 41 descending and opening into the renal vessels and pelves of the kidneys. Lippi admits the same arrangement, as regards the chyli- ferous vessels; and he adopts it to. explain the promptitude with which drinks are evacuated by the urine. Subsequent researches do not seem to have confirmed the statements of Lippi. G. Rossi,a indeed, maintains, that the vessels, which Lippi had taken for lym- phatics, were veins. It would appear, however, that when Rossi was at Paris, he was unable to demonstrate, when requested to do so by Breschet, the very things, which he had previously figured and described, Panizza, too, affirms, that no direct union or con- tinuity between the venous capillaries and the lymphatics has ever been made manifest to the eye, either in the human subject or in the lower animals.b On the whole matter, we are perhaps justified in concluding with Panizza, that anatomy has not hitherto suc- ceeded in determining, with physical certainty, in what relation the sanguiferous and lymphatic systems stand to each other, at their extreme ramifications.0 Magendied conceives the most plausible view regarding the lym- phatics to be:—that they arise by extremely fine roots in the sub- stance of the membranes and cellular tissue, and in the parenchyma of organs, where they appear continuous with the final arterial rami- fications,—as it frequently happens, that an injection, sent into an artery, will pass into the lymphatics of the part to which it is distributed. The structure of the lymphatic vessels is the same as that of the lacteals. They have the same number and character of coats, the same crescentic valves or sphincters, occurring in pairs, and giving them the knotted and irregular appearance, for which they are re- markable ; every contraction indicating the presence of a pair of valves, or sphincter. In man, each lymphatic, before reaching the venous system, passes through a lymphatic gland or ganglion; for- merly called a conglobate gland. These organs are extremely nu- merous ; and in shape, structure, and probably in function, entirely resemble the mesenteric glands. They, therefore, do not demand any distinct notice. They exist more particularly in the axillae, neck, in the neighbourhood of the lower jaw, beneath the skin of the nape of the neck, in the groins, and in the pelvis—in the neigh- bourhood of the great vessels. The connexion between the lym- phatic vessels and those glands is exactly analogous to that be- tween the chyliferous vessels and the mesenteric glands. Chaussier includes, in the lymphatic system, certain organs, whose uses in the economy are not manifest,—the thymus gland, " Omodei's Annali Universali, Jan. 1826. b Osservazioni Antropo-zootomico-fisiologiche, Pavia, 1833; and Breschet's Systeme Lymphatique, Paris, 1836. «■' See, on both sides of this subject, Midler's Handbuch, u. s. w., Baly's translation, p. 273, Lond, 1838; and Weber's Hildebrandt's Handbuch der Anatomie, iii. 113, Braunschweig, 1831. d Precis, &c. ii. 194. 4* 42 ABSORPTION. the thyroid gland, the supra-renal capsules, and perhaps the spleen. These he considers as varieties of the same species, under the name glandiform ganglions. The thymus gland is a body consisting Fig. 111. of distinct lobes, situate at the upper and anterior part of the thorax, behind the ster- num. It belongs more particularly to foetal existence, and will be investigated hereafter. The thyroid gland is, also, a lobular organ, situate at the anterior part of the neck be- neath the skin and some subcutaneous mus- cles, and resting upon the anterior and infe- rior part of the larynx, and the first rings of the trachea. It is formed of lobes, which subdivide into lobules and granula; has a red and sometimes a yellow colour; and presents, internally, cells or vesicles, filled with a fluid, which is viscid and colourless, or yellowish. Collected on the point of a knife (after in- cising the gland) it appears like weak gum, and is almost devoid of the ropiness of white of egg. When put into common rectified spirit it seems only to lose a little water; becomes solid, but not opaque, and decreases but little. The same effects result in the cells when the gland is boiled for a quarter of an hour, and no apparent solution occurs. The thyroid gland has no excretory duct; and, consequently, it is difficult to discover its use. It is larger in the foetus than in the adult, and has, therefore, been supposed to be, in some way, inservient to festal exist- ence. It continues, however, through life,1 receives large arteries, as well as a number of nerves and lymphatics, and hence, it has Lympkaties. been supposed, fills some important office through the whole of existence. This, all conjecture. Mr. Kingb The arrows indicate the°direc- has affirmed, what had been already ima- tion ,,.which the chyle passes. gined by many> ^ ^ ^^ ^^ of the thyroid gland convey its peculiar secretion to the great veins of the body. The thyroid gland is the seat of goitre or bronchocele, the swelled neck, Derbyshire neck, papas, &c as it has been termed in different quarters of the globe,—a singular affection, which is common at the base of lofty mountains in all parts of the a, a, a, a. Lymphatic vessels , proceeding towards the thoracic however, is duct. 6, b. Lymphatic glands Rev.KjSriS8Mpal2ia ArChiV' ^ ^^ "• ^ "•' Heft 1183?; and Brit' «* For. Med. b Guy's Hospital Reports, i. 437, Lond. 1836, and Sir Astley Cooper, ibid. p. 448. LYMPH. 43 world; and, in the cure of which, we have a valuable remedy in iodine. The sorbefacient property of this drug is particularly ex- erted on the thyroid gland and on the mammae; and it affords us an additional instance, to the many already known, of remedial agents, not only exerting their properties upon a particular system, but even upon a small part of such system, without our being able, in the slightest degree, to account for the preference. The iodine sti- mulates the absorbent vessels of the gland to augmented action; and the consequence is, the absorption of the morbid deposit. Lastly, the supra-renal or alrabiliary capsules or glands, are small bodies in the abdomen, without the peritoneum, and above each kidney. The arteries distributed to them are large; and the glands themselves are larger in the foetus than in the adult. They, likewise, remain during life. These bodies consist of small sacs, with thick paren- chymatous parietes: they are lobular and granular,—the internal cavity being filled with a viscid fluid oil, according to Sir Everard Home3 which is reddish in the foetus, yellow in childhood, and brown in old age. With their uses we are totally unacquainted. By the ancients, they were believed to be the secretory organs of the imaginary atrabilis; and hence their name. Sir Everard Home considers that they act like a filter, " by which any oil left in the arterial branches that are near the kidneys may be separated and prevented from making its escape by the tubae uriniferae of these glands." 2. LYMPH. Lymph may be procured in two ways, either by opening a lym- phatic vessel, and collecting the fluid, that issues from it,—but this is an uncertain method,—or by making an animal fast four or five days, and then obtaining the fluid from the thoracic duct. This has been considered pure lymph; but it is obvious that it must be mixed with the product of the digestion of the different secretions from the part of the digestive tube above the origin of the chyliferous vessels. Chyle itself is nothing more than the lymph of the intes- ' tines, containing matter absorbed from the digested food.b The fluid, thus obtained, is of a rosy, slightly opaline tint; of a marked spermatic smell, and saline taste. At times, it is of a decidedly yellowish colour; and, at others, of a madder red; circumstances which may have given occasion to erroneous inferences, in experi- ments made on the absorption of colouring matters. Its specific gravity has been found by some to be 1022.28: by others 1.037.° Its colour is affirmed to be more rosy, in proportion to the length of time the animal has fasted. When examined by the microscope, it * Lect. on Comp. Anat. v. 262, Lond. 1828. b MQller's Handbuch, u. s. w., Baly's translation, P. i. p. 258, Lond. 1838/ <= R. T. Marchand and C. Colberg, Mailer's Archiv. fur Anatomie, No. 2, 1838; and Brit, and For. Med. Rev. Oct. 1838, p. 544. 44 ABSORPTION. exhibits globules like those of the chyle ;a and, like the chyle, bears considerable analogy, in its chemical composition, to the blood. When left at rest, it separates into two portions;—the one a liquid, nearly like the serum of the blood; and the other a coagulum or clot of a deeper rosy hue; in which is a multitude of reddish fila- ments, disposed in an arborescent manner; and, in appearance, very analogous to the vessels, which are distributed in the tissue of the organs. When a portion of coagulated lymph is examined, it seems to consist of two parts;—the one which is solid, formed of numerous cells, containing the other or more liquid part; and if the solid por- tion be separated, the latter coagulates. Mr. Brande0 collected the lymph from the thoracic duct of an animal, which had been kept without food for twenty-four hours. He found its chief constituent to be water; besides which, it contained muriate of soda and albu- men ;—the latter being in such minute quantity, that it coagulated only by the action of galvanism. The lymph of a dog yielded to Chevreul, water 926.4; fibrine, 4.2; albumen, 61.0; muriate of soda, 6.1; carbonate of soda, 1.8; phosphate of lime, phosphate of mag- nesia, and carbonate of lime, 0.5: that of the horse yielded to Las- saigne, water, 192.5; fibrine, 0.33; albumen, 5.73; and chlorides of sodium and potassium, with soda and phosphate of lime, 1.43. Total, 100. More recent experiments by MM. Marchand and Colbergd found its constituents to be,—water, 96.926; fibrine, 0.520; albumen, 9.534; osmazome, (and loss) 0.312; fatty oil and crystalline fat, 0.264; chloride of sodium, chloride of potassium, carbonate and lactate of an alkali, and sulphate of lime, phosphate of lime, and oxide of iron, 1.544. Total, 100.000. It is impossible to estimate the quantity of lymph contained in the body. It would seem, however, that, notwithstanding the great capacity of the lymphatic vessels, there is, under ordinary circum- stances, but little fluid circulating in them. Frequently, when ex- amined, they have appeared to be empty, or pervaded by a mere thread of lymph. Magendiee endeavoured to obtain the whole of the lymph from a dog of large stature. He could collect but an ounce and a half; and it appeared to him that the quantity increased, whenever the animal was kept fasting; but on this point he does not seem to express himself positively. 3. PHYSIOLOGY OF LYMPHOSIS. The term lymphosis has been proposed by Chaussier for the action of elaboration, by which lymph is formed, as chylosis has * See, on the visible motion of the lymph globules in the lymphatics of the tadpole Prof. E. H. Weber, in Midler's Arehiv. Heft ii. 1837; and Brit, and For Med Rev' Oct. 1837, p. 500; and T. M. Ascherson, in Moller's Arehiv. Heft iv 1837 • and' Brit" and For. Med. Rev. July, 1838, p. 219. ' b Muller, op. cit. p. 259. c Turner's Chemistry, 4th Amer. Edit p 567 4 Op. cit. « Op. citat. ii. 192. LYMPHOSIS. 45 been, for the formation of chyle; and hcematosis, for that of the blood. In describing the organs, concerned in this function, the striking similarity—we might almost say—identity, in structure and arrangement between them and the chyliferous organs, will have been apparent. A part, indeed, of the vascular apparatus is com- mon to both; and they manifestly constitute one and the same system. This would be sufficient to induce us to assign them similar functions; and it would require powerful and positive testi- mony to establish an opposite view. At one period, the lymph was considered to be simply the watery portioji of the blood; and the lymphatic vessels were regarded as the mere continuation of the ultimate arterial ramifications. It was affirmed, that the blood, on reaching the final arterial branches, separated into two parts; the red and thicker portion returning to the heart by the veins; and the white, serous portion passing by the lymphatics. The reasons for this belief were, the great resemblance between the lymph and serum of the blood; and the facility with which an injection passes, in the dead body, from the arterial, into the lymphatic capillary vessels. Magendie has revived the ancient doctrine; and, of con- sequence, no longer considers the lymphatics to form part of the absorbent system; but to belong to the circulatory apparatus, and to serve, as we shall see, the office of waste pipes, in case of emer- gency. Without canvassing this subject now, we may assume it for granted, that the lymph, which circulates in the lymphatic ves- sels, is identical in its nature, or as little subject to alteration as the chyle; and that, consequently, whatever may be the materials, that constitute it, an action of elaboration and selection must be exerted in its formation. Many of the tissues of the body do not receive red blood; they must consequently be nourished by white blood. Such must be the case with all the serous membranes, for example. It has been conceived, that the lymphatics are to the white arteries what the veins are to the red. This at least rias been presumed to be one of their offices, which—as in the case of the veins—is not incompatible with their acting as absorbents likewise." Assuming, for the present, that the lymph.is wholly obtained from materials already deposited in the body; the next inquiry is;—into the mode in which their separation and simultaneous absorption are effected. On this topic, we have no additional arguments to employ to those adduced, regarding the function of the chyliferous radicles. In every respect they are identically situate; and to their history we refer for an exposition of how little we know of this part of lymphosis. The causes of the progression of the lymph in the vessels are the same as those that influence the chyle. In addition, how- ever, to those mentioned under chyliferous absorption, there is 3 Prof. S. Jackson, Principles of Medicine, 389, Philad. 1832; Dr. Graves, Lect. on the Lymphatic System; and Dr. Stokes, Lectures on the Theory and Practice of Physic, Dunglison's Amcr. Med. Libr. Edit. p. 313, Philad. 1837. 46 ABSORPTION. Now it is a physical fact, that when a small tube is inserted perpendicularly into the lower side of a horizontal conical pipe, in which the water is flowing from the narrower to the wider portion; and if the small vertical tube be made to dip into a vessel of water, not only will the water of the larger pipe not descend into the vessel; but it will actually draw up the water through the small tube, so as to empty the vessel.1 Instead of supposing the canals in Fig. 112, to be veins and the thoracic duct; let us presume, that they are rigid mechanical tubes; and that the ex- tremity of the tube D, which represents the thoracic duct, dips into the vessel B. As the fluids, proceeding from J to S and from V to S are passing from the narrower portions of conical tubes to wider, it follows, that the fluid will be drawn out of the vessel B, simply by traction, or, by what Venturib terms, the lateral communi- cation of fluids. This would happen in whatever part of the vessel the tube B D terminated. But its insertion at D has another advan- tage. By the mode in which the current, from J towards S, unites with that from V towards S, a certain degree of diminished pres- sure must exist at D; so that the atmospheric pressure, on the surface of the water in the vessel B, will likewise be exerted in propelling it forwards. In the progress, then, of the chyle and lymph, along the thoracic duct, not only may the attraction of the more forcible stream along the veins draw the fluid in the thoracic duct along with it, but, owing to the diminished pressure at the 1 Sir C. Bell, in Animal Mechanics, p. 41, Library of Useful Knowledge, Lond 1829 b Sur la Communication Laterale du Mouvcment dans les Fluides Paris 179*8 LYMPHOSIS. 47 mouth of the duct, atmospheric pressure may have some—although probably but little—influence, in forcing the chyle and lymph from the chyliferous and lymphatic radicles onwards. The lymphatic glands have been looked upon as small hearts for the propulsion of the lymph; and Malpighi accounts for the greater number in the groin in this way;—the lymph having to ascend to the thoracic duct against its own gravity: this appears, also, to have been some- what the opinion of Bichat. There seems, however, to be nothing in their structure, which should lead to this belief; and, if not mus- cular or contractile, it is manifest, that their number must have the effect of retarding rather than of accelerating the flow of the lymph. The most prevalent sentiment is, that they are somehow concerned in the admixture of the lymph; and by many it is conceived, that some kind of elaboration is effected by them ; but, on this topic, we have only conjectures for our guidance. Of their true functions we know nothing definite. On the subject of the moving powers of the lymph, Adelon8 has ■ remarked, that if we admit the lymph to be the serous portion of the blood, and that the lymphatics are vessels of return, as the veins are, the heart might be considered to have the same influence over lymphatic, that it has been presumed to have over venous, cir- culation; and whether we admit this or not, as the thoracic duct opens into the subclavian vein, the influence of the suction power of the organ on the venous blood may affect the progression of the chyle also. It cannot, however, as Mullerb remarks, be the primary cause of the motion of the chyle, for Autenrieth, Tiedemann, and Carus observed, that when a ligature was applied to the thoracic duct, the part of the duct below the ligature became distended even to bursting. We shall see hereafter, that during inspiration, absorption, it is imagined, may be facilitated by the dilatation of the chest, and cause great diminution of pressure on the heart and great vessels. Professor Muller0 discovered, that the frog, and several other amphibious animals are provided with large receptacles for the lymph, situate immediately under the skin, and exhibiting distinct and regular pulsations, like the heart. The use of these lymphatic hearts appears to be to propel the lymph along the lymphatics. In the frog four of these organs have been found ; two posterior situate behind the joint of the hip, and two anterior on each side of the transverse process of the third vertebra, and under the posterior extremity of the scapula. The pulsations of these lymphatic hearts do not cor- respond with those of the sanguiferous heart; nor do those of the right and left sides take place synchronously. They often alternate a Art. Absorption, in Diet, de Medecine, 2de edit. i. 239, Paris, 1832 ; and Physio- logie de I'Homme, edit. cit. iii. 92. b Handbuch, u. s. w.; and Baly's translation, p. 284, Lond. 1838. c Philos. Transact, for 1833, and op. cit. See, also, his observations on the Lym- phatic Hearts of Tortoises, in Milller's Arehiv., Heft i, 1840; and Brit, and For. Med. Review, July, 1840, p. 256. 48 ABSORPTION. in an irregular manner. Prof. E. H. Weber has described those lymphatic* hearts in a larger species of serpent—the python bivi- tatus;a and Dr. Joseph J. Allison, of Philadelphia,11 a young and zealous observer, who was cut off early in his career, has likewise seen them in the tadpole, the frog, the sauna, ophidia, and chelonia. His researches led him to conclude: First. I hat the pulsations of the lymphatic organs vary in different specimens (frogs and tadpoles) from 60 or less to 200"per minute. Secondly. That they vary in the same individual so as sometimes to become double in frequency. Thirdly. That the lymphatic pulsations bear no fixed relation to those of the pulmonary heart or to respiration, the lymphatic hearts beating—on an average with greater frequency. The course of the lymph is by no means rapid. If a lymphatic vessel be divided, in a living individual, the lymph oozes out slowly, and never with a jet. Cruikshank estimated its velocity along the vessels to be four inches per second or twenty feet per minute ; but. it is probably far less rapid. Collard de Martignyc obtained nine grains of lymph, in ten minutes, from the thoracic duct of a rabbit, which had taken no food for twenty-four hours. Having pressed out the lymph from the principal lymphatic trunk of the neck, in a dog, the vessel filled again in seven minutes: in ,a second experi- ment it filled in eight minutes. The data for any correct evaluation of this matter are altogether inadequate, the deranging influence of all such experiments being signal. In man and in living animals, the lymphatics of the limbs, head, and neck rarely contain lymph; their inner surface appearing to be merely lubricated by a very thin fluid. Occasionally, however, the lymph stops in different parts of the vessels; distends them; and gives them an appearance very like that of varicose veins, except as to colour. Sommering states, that he has seen several in this condition on the top of the foot of a female; and Magendie one around the corona glandis of the male. In dogs, cats and other living animals, lymphatics, filled with lymph, are frequently seen at the surface of the liver, gall-bladder, vena cava, vena portae, and at the sides of the spine. Magendie remarks, that he has never met with the thoracic duct empty, even when the lymphatics of the rest of the body were entirely so.d It must be recollected, however, that the thoracic duct must always contain the product of the diges- tion either of food or of the secretions from the alimentary tube. This kind of stagnation of lymph in particular vessels has given occasion to the belief, that the lymph flows with different degrees of velocity in the different parts of the system ; and the notion has entered into the pathological views of different writers,'who have presumed, that something like determinations of lymph can occur, so as to produce lymphatic swellings. Bordeu,e indeed, speaks of cur- a Muller, Op. citat. p. 275. b American Journal of the Medical Sciences, for August, 1838. c Journal de Physiologie, torn. viii. d Precis &c ii 224 e ffiuvres completes, par Richerand, Paris, 1818. LYMPHOSIS. 49 rents of lymph. All the phenomena of the course of the lymph negative such presumption ; and induce us to believe, that its pro- gress is pretty uniform and always slow; and when an accumula- tion, or engorgement, or stagnation occurs in any particular vessel, it is more probably owing to increased secretion by the lymphatic radicles, which communicate with the vessel in question, and the consequently augmented quantity of lymph. The lymph, which proceeds by the thoracic duct, is emptied, along with the chyle, into the subclavian vein. At the confluence, a valve is placed, which does not, however, appear to be essential, as the duct opens so favourably between the two currents from the . jugular and subclavian, that there is no tendency for the blood to reflow into it. It has been suggested, that its use may be, to moderate the instillation of the fluid from the thoracic duct into the venous blood. With regard to the question, whether the lymph be the same at the radicles of the lymphatics as in the thoracic duct, or whether it do not gradually become more and more animalized in its course towards the venous system, and especially in its progress through the lymphatic glands, the remarks made upon the subject, as respects the chyle, apply with equal force to the lymph; and our ignorance is no less profound. The glands of the mesentery, and of the lymphatics in general, seem to be concerned in some of the most serious diseases. Swell- ing of the lymphatic glands of the groin may indicate the existence of a venereal sore on the penis. A wound on the foot will produce tumefaction of the inguinal glands; one on the hand will inflame the glands in the axilla. Whenever, indeed, a lymphatic gland is symptomatically enlarged, the source of irritation will be found at a greater distance from the vein into which the great lymphatic trunks pour their fluid, than the gland is. In plague, one of the essential symptoms is the appearance of swelling of the lymphatic glands of the groin and axilla; hence, it has been termed by some, adeno- adynamic fever (from aSriv, a gland.) In scrofula, the lymphatic system is generally deranged; and, in the doctrine of Broussais, a very active sympathy is affirmed to exist between the glands of the mesentery, and the mucous surface of the stomach and intestines. This discovery, we are told, belongs td*the " physiological doctrine," which has shown, that all gastro-enterites are accompanied by tumefaction of the mesenteric glands: although chyle may be loaded with acrid, irritating, or even poisonous matters, it traverses the glands with impunity, provided it does not inflame the gastroin- testinal mucous surface. " Our attention," Broussaisa adds, " has been for a long time directed to this question, and we have not observed any instance of mesenteric ganglionitis, which had not been preceded by well-evidenced gastro-enteritis." The discovery will not immortalize the " doctrine." We should as naturally look 1 Traite de Physiologie, &c. and Bell and La Roche's translation, 3d Amcr. Edit. p. 362, Philadelphia, 1832. VOL. II. 5 NATIONAL LIBRARY OF MEDICINE WASHINGTON, D. C. 50 ABSORPTION for tumefaction of the mesenteric glands or ganglia, in cases of irri- tation of the intestine, as for enlargement of the glands of the groin when the foot is irritated. . Lastly; the lymph, from whatever source obtained—united with the chyle—is discharged into the venous system. Both these, therefore, go to the composition of the body. They are entirely analogous in properties; but differ materially in quantity;—the nu- tritious fluid, formed from materials obtained from without, being by far the most copious. A due supply of it is required for con- tinued existence; yet the body can exist for a time, even when the supply of nutriment is entirely cut off. Under such circumstances, the necessary proportion of nutritive fluid must be obtained from the decomposition of the tissues; but, from the perpetual drain, which takes place through the various excretions, this soon becomes in- sufficient, and death is the result.1 We have seen, that both chyle and lymph are poured into the venous blood;—itself a compound of the remains of arterial blood, and of various heterogeneous absorptions. As an additional pre- liminary to the investigation of the agents of internal absorption, let us now inquire into the nature and course of the fluid contained in the veins; but so far only as to enable us to understand the func- tion of absorption: the other considerations, relating to the blood, appertain to the function of circulation. VENOUS ABSORPTION. 1. ANATOMY OF THE VENOUS SYSTEM. This system consists of myriads of vessels, called veins, which commence in the very textures of the body, by what are called capillary vessels; and from thence pass to the great central organ of the circulation—the heart; receiving, in their course, the products of the various absorptions not only effected by themselves, but by the chyliferous and lymphatic vessels. The origin of the veins, like that of all capillary vessels, is imper- ceptible. By some, they are regarded as continuous with the capillary arteries; Malpighib and Leeuenhoek0 state this as the result of their microscopic observations on living animals; and it has been inferred, from the facility with which an injection passes from the arteries into the veins. According to others, cells exist between the arterial and the venous capillaries, in which the former deposit their fluid and whence the latter obtain it. Others, again, substitute a spongy tissue for the cells. A question has also been asked,—whether the veins terminate by open mouths; or whether there may not be more delicate vessels, a See Adelon, Physiologie de I'Homme, edit. cit. iii. 68, Paris, 1829 ; art. Absorption, in Diet, de Med. 2de edit. i. 239, Paris, 1832; Copland, in Lond. Med. Repos. for Jan. 1825; Muller's Handbuch u. s. w., or Baly's translation, p. 258, Lond. 1838; Ancell's Lectures on the Blood, London Lancet, Oct. 26, 1839, p. 150; and Mr. Lane art. Lymphatic and Lacteal System, Cyclop, of Anat. and Physiol. April, 1841. b Opera., Lond. 1687. c Opera., Lugd. Bat. 1722. BY THE VEINS. 51 communicating with their radicles, similar to the exhalants, which are presumed to exist at the extremities of the arteries, and which are regarded as the agents of exhalation. All this is, however, conjectural. It has already been observed, that the mesenteric veins have been considered to terminate by open mouths in the villi of the intestines; and the same arrangement, has been conceived to prevail with regard to other veins. Ribes concludes, from the results of injecting the veins, that some of the venous capillaries are imme- diately continuous with the minute arteries, whilst others open into the cells of the laminated tissue, and into the substance of the dif- ferent organs. Fig. 113. Ramifications of the Splenic Artery in the Spleen. When the veins become visible, they appear as an infinite number of tubes, extremely small, and communicating very freely with 52 ABSORPTION. each other; so as to form a very fine net-work. These vessels gradually become larger and less numerous, but still preserve their reticular arrangement; until, ultimately, all the veins of the body empty themselves into the heart, by three trunks,—the vena cava inferior, the vena cava superior, and the coronary vein. The first of these receives the veins from the lower part of the body, and extends from the fourth lumbar vertebra to the right auricle; the second receives all the veins of the upper part of the body; and into it the subclavian opens, into which the chyle and lymph are discharged. It extends from the cartilage of the first rib to the right auricle. The coronary vein belongs to the heart exclusively. Between the superior and inferior cava a communication is formed by means of the vena azygos. Certain organs appear almost wholly composed of venous radi- cles. The spleen is one of these. Fig. 113 represents the ramifica- tions of the splenic artery, in the substance of that organ ; and if we consider, that the splenic vein has corresponding ramifications, the viscus would seem to be almost wholly formed of blood-vessels. The same may be said of the corpus cavernosum of the penis and clitoris, the nipple, urethra, glans penis, &c. If an injection be thrown into one of the veins that issue from these different tissues, they are wholly filled by the injection ; which rarely occurs, if the injection be forced into the artery. Magendie1 affirms, that the communication of the cavernous tissue of the penis with the veins occurs through apertures two or three millimetres—in. 0.117—in diameter. In their course towards the heart, particularly in the extremities, the veins are divided into two planes;—one subcutaneous or super- ficial; the other deep-seated, and accompanying the deep-seated arteries. Numerous anastomoses occur between these, especially when the veins become small, or are more distant from the heart. \\ e find, that their disposition differs according to the organ. In the brain, they constitute, in great part, the pia mater; and enter the ventricles, where they contribute to the formation of the plexus choroides and tela choroidea. Leaving the organ, we find them situate between the lamina? of the dura mater; when they take the name of sinuses. In the spermatic cord, they are extremelv tortuous, anastomose repeatedly, and form the corpus pampini- forme; around the vagina, they constitute the corpus retiforme; in the uterus, the uterine sinuses, &c. The veins have three coats in superposition. The outer coat is cellular, dense, and very diffi- cult to rupture. The middle coat has been termed the proper mem- brane of the veins. The generality of anatomists describe it as composed of longitudinal fibres, which are more distinct in the vena cava inferior than in the vena cava superior; in the superficial veins than in the deep-seated; and in the branches than in the trunks. Magendieb states, that he has never been able to observe a Precis, &c. ii. 2c 8. b Ibid. ii. 242. APPARATUS OF' VENOUS ABSORPTION. 53 the fibres of the middle coat; but that he has always seen a mul- titude of filaments interlacing in all directions; and assuming the appearance of longitudinal fibres, when the vein is folded or wrinkled longitudinally, which is frequently the case in the large veins. It exhibits no signs of muscularity; even when the galvanic stimulus is applied; yet Magendie suspects its chemical nature to be fibrinous. It was remarked, in an early part of this work, (vol. i. p. 36,) that the bases of the cellular and muscular tissue are, respectively, gela- tine, and fibrine; and that the various resisting solids may all be brought to one or other of these tissues. The middle coat of the veins doubtless belongs to the former, and is a variety of the Tissu jaune of the French anatomists. Magendie, merely states its fibri- nous nature to be a suspicion; and, like numerous suspicions, it may be devoid of foundation. Yet we have reason to believe, that it is contractile. Broussaisa affirms, that this action is one of the principal causes of the return of the blood to the heart. He con- ceives, that the alternate movements of contraction and relaxation are altogether similar to those of the heart; but that they are so light as not to have been rendered perceptible by any process in the majority of the veins, although very visible in the vena cava of frogs, where it joins the right auricle. In some experiments by Sarlandiere on the circulation, he observed these movements to be independent of those of the heart. After the heart was removed, the contraction and relaxation of the vein continued, for many minutes, in the cut extremity, and even after the blood had ceased to fiow.b The inner coat is extremely thin and smooth at its inner surface. It is very extensible, and yet presents considerable resistance; bear- ing a very tight ligature without being ruptured. In many of the veins, parabolic folds of the inner coat exist, like those in the lymphatics, and inservient to a similar purpose: the free edge of these valves is directed towards the centre of the cir- culation ; showing that their office is to permit the blood to flow in that direction, and to prevent its retrogression. They do not seem, however, in many cases, well adapted for the purpose; inasmuch as their size is insufficient to obliterate the cavity of the vein. By most anatomists, this arrangement is considered to depend upon primary organization; but Bichat conceives it to be wholly owing to the state of contraction, or dilatation of the veins at the moment of death. Magendie, however, affirms, that he has never seen the distension of the veins exert any influence on the size of the valves; but that their shape is somewhat modified by the state of contrac- tion or dilatation; and this he thinks probably misled Bichat.c Their number varies in different veins. As a general rule, they are more numerous, where the blood proceeds against its gravity, or where the veins are very extensible, and receive but a feeble support » Op. citat., Amer. translation, p. 391. b See, on this subject, the remarks made hereafter, on the circulation in the veins. c Precis, &c, ii. 241. 5* 54 , ABSORPTION. from the circumambient parts, as in the extremities. They are entirely wanting in the veins of the deep-seated viscera; in those of the brain and spinal marrow; of the lungs; in the vena portae and in the veins of the kidneys, bladder and uterus. They exist, how- ever, in the spermatic veins; and, sometimes, in the internal mam- mary, and in the branches of the vena azygos. On the cardiac side of these valves, cavities or sinuses exist, which appear externally in the form of varices. These dilatations enable the refluent blood to catch the free edges of the valves, and thus to depress them, so as to close the cavity of the vessel; serving, in this respect, precisely the same functions as the sinuses of the pulmonary artery and aorta in regard to the semilunar valves. The three coats united form a solid vessel,—according to Bichat devoid of elasticity, but, in the opinion of Magendie,1 elastic in an eminent degree. The elasticity is'certainly much less than that of the arteries. The veins are nourished by vasa vasorum, or by small arteries, which have their accompanying veins. Every vessel, indeed, in the body, if we may judge from analogy, appears to draw its nutriment, not from the blood circulating in it, but from small arterial vessels, hence termed vasa vasorum. This applies not only to the veins, but to the arteries. The heart, for example, is not nourished by the fluid constantly passing through it; but by vessels, which arise from the aorta, and are distributed over its surface, and in its intimate tex- ture. The coronary arteries and their corresponding veins are, con- sequently, the vasa vasorum of the heart. In like manner, the aorta and all its branches, as well as the veins, receive their vasa vaso- rum. There must, however, be a term to this; and if our powers of observation were sufficient, we ought to be able to discover a vessel, which must derive its support or nourishment exclusively from its own stores. The nerves that have been detected on the veins, are branches of the great sympathetic. The capacity of the venous system is generally esteemed to be double that of the arterial. It is obvious, however, that we can only arrive at an approximation, and that not a very close one. The size and number of the veins is generally so much greater than that of the corresponding arteries, that when the vessels of a membranous part are injected, the veins are observed to form a plexus, and, in a great measure, to conceal the arteries: in the intestines, the number is more nearly equal. The difficulty of arriving at any exact conclu- sion, regarding the relative capacities of the two systems, is forcibly indicated by the fact, that, whilst Borelli conceived the preponde- rance in favour of the veins to be as four to one, Sauvages estimated it at nine to four, Haller at sixteen to nine, and Keill at twenty-five to nine." J There is one portion of the venous system, to which allusion has already been made, which is peculiar. We mean the abdominal • Precis, &c. ii. 243. Elementa Physiologic, Lausan. 1757-1766. APPARATUS OF VENOUS ABSORPTION* 55 venous or portal system. All the veins, that return from the digestive organs, situate in the abdomen, unite into a large trunk, called the vena porta. This, instead of passing into a larger vein—into the vena cava, for example—proceeds to the liver, and ramifies, like an artery, in its substance. From the liver, other veins, called supra- hepatic, arise, which empty themselves into the vena cava; and which correspond to the branches of the hepatic artery as well as to those of the vena portce. The portal system is concerned only with the veins of the digestive organs situate in the abdomen; as, the spleen, pancreas, stomach, intestines and omenta. The veins of all the other abdominal organs,—of the kidney, supra-renal capsules, &c. are not connected with it. The first part of the vena porta? is called, by some authors, vena portce abdominalis vel ventralis, to dis- tinguish it from the hepatic portion, which is of great size, and has been called the sinus of the vena porta?. 2. BLOOD. The blood strongly resembles the chyle in its properties;—the great difference consisting in the colour; and the venous blood,and the chyle, and the lymph become equally converted into the same fluid—arterial blood—in the lungs. Venous blood, which chiefly concerns us at present, is contained in all the veins, in the right side of the heart, and in the pulmonary artery;—organs which constitute the apparatus of venous circula- tion. As drawn from the arm, its appearance is familiar to every one. At first, it seems to be entirely homogeneous; but, after resting^ for some time, it separates into different portions. The colour of venous blood is much darker than that of arterial;—so dark, indeed, as to have had the epithet black blood applied to it. Its smell is faint and peculiar; by some compared to a fragrant garlic odour, but it is sui generis; its taste is slightly saline, and also peculiar. It is viscid to the touch; coagulable, and its temperature has been esti- mated at 96° of Fahrenheit; simply, we believe, on the authority of the inventor of that thermometric scale, who marked 96° as blood heat. This is too low by at least three or four degrees. Rudolphi,* and the German writers in general, estimate it at 29° of Reaumur, or " from 98° to 100° of Fahrenheit;" whilst, by the French writers in general, its mean temperature is stated at 31° of Reaumur or 102° of Fahrenheit; Magendie,b who is usually very accurate, fixes the temperature of venous blood at 31° of Reaumur, or 102° of Fahrenheit; and that of arterial blood at 32° of Reaumur, or 104° of Fahrenheit. 100° may perhaps be taken as the average. This was the natural temperature of the stomach in the case related by Dri Beaumont,0 which has been so often referred to in these pages. In many animals, the temperature is considerably higher. In the sheep it is 102° or J03°; but it is most elevated in birds. In the duck it is » Grundriss der Physiologie, i. 143, Berlin, 1821. b Precis, &c. ii. 229. c Experiments, &c. on the Gastric Juice, &c. p. 274, Plattsburg, 1833. 56 ' ABSORPTION. 107°. On this subject, however, further information will be given under the head of Calorification. The specific gravity of the blood is differently estimated by differ- ent writers. Hence it is probable, that it varies in different indivi- duals, and in the same individual at different periods. Compared with water its mean specific gravity has been estimated, by some, to be as 1.0527, by others, as 1.0800, to 1.0000. It is stated, however, to have been found as high as 1.126; and, in disease, as low as 1.022. It has, moreover, been conceived, that the effect of disease is, inva- riably, to make it lighter; and that the more healthy the individual, the greater is the specific gravity of the blood; but our information on this point is vague. That it is not always the same in health is proved by the discrepancy of observers. Boyle estimated it at 1.041; Martine, at 1.045; Jurin, at 1.054; Muschenbroek, at 1.056; Denis, at 1.059; Senac, at 1.082; and Berzelius at from 1.052 to 1.126.a A part of the discrepancy may be owing to the specific gravity not having been always taken at the same temperature. Dr. B. Babington found experimentally, that four degrees of temperature corresponded with a difference of .001 of specific weight: conse- quently, if one author states the specific gravity of blood at about its circulating temperature—say 98° of Fahr.—while another states it at 60° Fahr.—the usual standard—the former will make it .0095 lighter than the latter.b When blood is examined with a microscope of high magnifying powers, it appears to be composed of numerous, minute, red particles or globules, suspended in the serum. These red particles have a different shape and dimension, according to the nature of the ani- mal. In the mammalia, they are circular; and, in birds and cold- blooded animals, elliptical. In all animals, they are affirmed, by some observers, to be flattened, and marked in the centre with a luminous point, of a shape analogous to the general shape of the globule. Recently, indeed, Prof. Giacomonic of Padua, has affirmed, that the red globules, swimming in serum,—which have been described by so many writers on the circulating fluid,—exist only in their imaginations. As in every case which rests on microscopic observation, the greatest discrepancy pre- vails here, not only as regards the shape but the size of the globules. They were first noticed by Malpighi,d and were after- wards more minutely examined by Leeuenhoek,e who at first n*t£rB?a7' in^EdTinb-,M/0laniSnrg- i°,Uma1' XCV- 245; Sir C- Scudamore, Essay on the Blood, p. 36, Lond. 1824; Haller, Elementa Physiologic, ii. 8; and Burdach Die Physiologie als Erfahrungswissenschaft, iv. 15, Leipz. 1832 ' anQ Iiuraacn' b Dr. Babington, in Cyclop. Anat. and Physiol, parts iv. arid v.; and in Medical and burgical Monographs, p. 3, (American Med. Library, for 1837-8 'i Phn-,H IS^S «= De la Nature, de la Vie, et des Maladies du Sang; Memoire lu divanip'rlL Sdentifique de Pise, Oct. 4. 1839, in Encyclop. des Sciences 525^^ Sf!.J <* Opera, Lond. 1687. e Martine, in Edinb. Med. Essays, ii. 74 ; and Phil. Transact, for 1694. VENOUS BLOOD. 57 described them, correctly enough, in general terms; but, subse- quently, became hypothetical, and advanced the phantasy, that the red particles are composed of a series of globular bodies, descend- ing in regular gradations; each of the red particles being supposed to be composed of six particles of serum; a particle of serum of six particles of lymph, &c. Totally devoid of foundation, as the whole notion was, it was implicitly believed for a considerable period, even until the time when Haller wrote. Hewsona described the globules as consisting of a solid centre, surrounded by a vesicle, filled with a fluid; and to be « as flat as a guinea." Hunter,b on the other hand, did not regard them as solid bodies, but as liquids, possessing a central attraction, which determines their shape. Delia Torre0 supposed them to be a kind of disk, or ring, pierced m the centre; whilst Monro conceived them to be circular, flattened bodies, like coins, with a dark spot in the centre, which he thought was not owing to a perforation, as Delia Torre had imagined, but to a depression. Cavallo,4 again, conceived, that all these appear- ances are deceptive, depending upon the peculiar modification ol the rays of light, as affected by the form of the particle; and he concluded, that they are simple spheres. Amici found them of two kinds, both with angular margins; but, in the one, the centre was depressed on both sides; whilst, in the other, it was elevated, lne observations of Dr. Young,e of Sir Everard Home and Mr. Bauer, and of MM. Prevost and Dumas,* accord chiefly with those ol Hewson. All these gentlemen consider the red particles to be com- posed of a central globule, which is transparent and whitish, and ot a red envelope, which is less transparent. Still more recently, however, Dr. Hodgkin and Mr. Listerh have denied that they are spherical, and that they consist of a central nucleus inclosed in a vesicle. They affirm, on the authority of a microscope, which, on comparison, was found equal to a celebrated one, taken a few years ago to Great Britain by Professor Amici,1 that the particles of human blood appear to consist of circular, flattened, transparent cakes, their thickness being about ^th part of their diameter. These, when seen singly, appear to be nearly or quite colourless. Their edges are rounded, and being the thickest part occasion a depression in the middle, which exists on both surfaces. lne view of these gentlemen, consequently, appears to resemble that ot Monro. 1 Experimental Inquiries, part iii. p. 16, Lond. 1777. pi,;w icuft b On the Blood, by Palmer^ reprinted in Bell's Select Med. Lib. p. 63, Philad. 1840. c l'hilos. Trans, for 1765, p. 252. 0„ T , 17qs d An Essay on the Medicinal Properties of Factitious Air, &c. p. 237, Lond. 179S. e Introduct. to Med. Literature, p. 545. _ , f Philosoph. Transact for 1811-18; and Lectures on Comp. Anat. m. 4, Lond. 18?Annales de Chimie, &c. xxiii. 50, 90; and 3^**™^$^ K^JJ* b Philosoph. Magazine and Annals of Philosophy n. 130, Lond. 1827 , and Transla tion of Edwards on Physical Agents-Appendix Lond. 1832 preprinted■*JBeU^s Select Medical Library, Philad. 1838; See, also, Hodgkin, Catalogue of the Prepara- tions in the Anatomical Museum of Guy's Hospital, introd. to sect. xi. P. i. Lond. 1829, ' Edinb. Medical and Surgical Journal, xvi. 120. 58 ABSORPTION. Amidst this discordance, it is difficult to know which view to adopt." The belief in their consisting of circular, flattened, trans- parent bodies, with a depression in the centre, and that they con- sist of an external envelope and of a central nucleus, the former of which is red and gives colour to the blood, appears to have the greatest weight of authority in its favour. The nucleus is devoid of colour, and appears to be independent of the envelope; as, when the latter is destroved, the central portion preserves its original shape. The nucleus is much smaller than the envelope, being, according to Dr. Young, only about one-third the length, and one- half the breadth of the entire particle. According to Sir Everard Home,b the globules, when enveloped in the colouring matter, are TTVoth part of an inch in diameter, requiring 2,890,000 to a square inch ; but. when deprived of their colouring matter, they appear to be y,fVirth part of an inch in diameter, requiring 4,000,000 of glo- bules to a square inch. According to these measurements, the globules, when deprived of their colouring matter, are not quite one- fifth smaller. The views of MM. Prevost and Dumas, who have investigated the subject with extreme care and signal ingenuity, are deserving of great attention. They conceive the blood to consist essentially of serum, in which a quantity of red particles is sus- pended ; that each of these particles consists of an external red vesicle, which incloses, in its centre, a colourless globule; that, during the progress of coagulation, the vesicle bursts, and permits the central globule to escape; that, on losing their envelope, the central globules are attracted together; that they are disposed to arrange themselves in lines and fibres; that these fibres form a net- work, in the meshes of which they mechanically entangle a quantity of both the serum and the colouring matter; that these latter sub- stances may be removed by draining, and by ablution in water; that, when this is done, there remains only pure fibrine; and that, consequently, fibrine consists of an aggregation of the central glo- bules of the red particles, while the general mass, that constitutes the crassamentum or clot, is composed of the entire particle. So far this seems satisfactory; but, we have seen, Dr. Hodo-kin does not recognise the existence of external vesicle or of central globule; and he affirms, contrary to the notion of Sir Everard Home and others, that the particles are disposed to coalesce in their entire state. This is best seen, when the blood is viewed between two slips of glass. Under such circumstances, the follow- ing appearances, according to Dr. Hodgkin, are perceptible. When human blood, or that of any other animal having circular particles, is examined in this manner, considerable agitation is, at first seen to take place among the particles; but, as this subsides, they 'apply themselves to each other by their broad surfaces, and form piles or rouleaux, which are sometimes of considerable length. These rouleaux often again combine amongst themselves,—the end of one * See, on this subject, Paine, Medical and Physiological Commentaries vol i Appendix on the Microscope, p. 899, New York, 1840. ' "' b Lectures on Comparative Anatomy, iii. 4, and v, 100, Lond. 1828, VENOUS BLOOD. 59 being attached to the side of another,—producing at times, very curious ramifications. The generality of physiologists consider the fibrine to be one con- stituent of the blood, and the red particles another. The former is conceived by Mullera to be dissolved in the serum. Microscopical discordances are no less evidenced by the esti- mates, which have been made of the size of the red globules; yet all are adduced on the faith of positive admeasurements. Leaving out of view the older, and, consequently, it might be presumed, less accurate observations, the following table will show their diameter in human blood, on the authority of some of the most eminent microscopic observers of more recent times. Sir E. Home and Bauer, with colouring matter, yy^th part of an inch. Eller, - - - - - - - -j-930- Sir E. Home and Bauer, without colouring > T matter, ... ( won Jurin, - -Muller,..... 1 2006" 1 to 1 2700 7'5(T0* Hodgkin, Lister, and Rudolphi, -Sprengel,..... Cavallo, .... Blumenbach and Senac, - 1 7000 1 tn * 3(nnr l" 3500 1 tn * 70 0 0 tu 40 0 0 1 T7751 Tabor,..... Milne Edwards, .... . 1 760 0 79W Wagner, .... 1 4TJ0 0 Kater, ..... - Z'S'So '° 6"5o"'6r Prevost and Dumas, 1 40 5?" Haller, Wollaston, and Weber, - 1 Young,..... " ff76TFb The blood of different animals is found to differ greatly in the relative quantity of the red. globules it contains, the number seeming to bear a pretty exact ratio with the temperature of the animal. The higher the natural temperature, the greater the proportion of particles; and arterial always contains a much greater proportion than venous blood. It has been already remarked, that innumerable globules have been found in the chyle. These are colourless; and they have been asserted to be of precisely the same magnitude as the nucleus of the red globules of the blood. It is presumed, too, that the globules of the chyle obtain their colour, and their external envelope on which it depends, in the lungs; and that this is the finish given * Annales des Sciences Nat. 2de series, torn. i. p. 342, and Handbuch, u. s. w., or Baly's translation, p. 109, Lond. 1838. b Burdach, Die Physiologie als Erfahrungswissenschafl, iv. 21, Leipz. 1832. See, also, Rudolphi, Grundriss der Physiologie, i. 159, Berlin, 1821; Fontana, Nuove Osser- Vazione sopra i Globelli rossi del Sangue, Lucca, 1766; Spallanzani, Dell'azioni del Cuore nei Vasi Sanguin, Moden. 1768; Haller, Elem. Physiol.; Weber's Hilde- brandt's Handbuch der Anatomie, i. 157, Braunschweig, 1830; and Ancell, Lectures on the Physiology and Pathology of the Blood, in Lond. Lancet, Dec. 7, 1839, p. 380. 60 ABSORPTION. to the process of digestion. The notion is, however, problema- tical. The following table exhibits the diameter of the circular and elliptical globules in different animals, according to MM. Prevost and Dumas.3 ANIMALS WITH CIRCULAR GLOBULES. Animals. Diameter in fractions of a Millimetre.b Callitrichus or green Monkey of Africa, Man, the Dog, Rabbit, Hog, Hedge-hog, Guinea-pig, and Dormouse, The Ass, -------The Cat, gray and white Mouse, field Mouse, Sheep, Bat, Horse, Mule, Ox, -Chamois, Stag, ..... Goat, ------- T-b* Tso* TTTst irloth 2x7th 1 th 277ln ANIMALS WITH ELLIPTICAL GLOBULES. Animals. Osprey, Pigeon, .... Turkey, Duck, ..... Common Fowl, .... Peacock, ...... Goose, Goldfinch, Crow, Sparrow, Titmouse, ...... Land Tortoise, ..... Viper, ^...... Orvet, ....... Coluber of Razomousky, Gray Lizard, ...... Salamandre ceinturee, Crested Salamander, Common Frog, Toad, Frog with red temples, Burbot, Minnow, Eel, .... When blood is drawn from a vessel, and left to itself, it exhales, so long as it is warm, a fetid vapour consisting of water and animal matter, of a nature not known.0 This vapour is what has been called the halitus of the blood,—by Plenck, the gas animate sanguinis, which he conceives to be composed of carbon and hydrogen, and to be inservient to many supposititious uses in the economy. 'The * Op. citat., and Annales des Sciences Naturelles, 1824 & 1825; also, Burdach torn cit. p. 21. ' b A Millimetre is equal to in. 0.03937. c Ancell, Lectures on the Blood, Jan. 18, 1840, p. 608. Diameter. Long. Short. yVh Ti^h TVth — 7TSt — 7yih — 7Vh — lioth — 4-Vh TVth 6-Vh yioth eVh TTjth Ast T^th eVth rirth aVh A* Ath 7Vth rVth Toth VENOUS BLOOD. 61 odour exhaled by the blood would appear to preserve the same general characters under all circumstances/ After a time, the blood coagulates, giving off, at the same time, it has been said, a quantity of carbonic acid gas. This disengagement is not evident, when the blood is suffered to remain exposed to the air, except, perhaps, by the apertures or canals formed by its passage through the clot; but it can be collected by placing the blood under the receiver of an air-pump, and exhausting the air. On this fact, however, observers do not all accord. The experiments of Vogel,b Brande,c Sir E. Home,d and Sir C. Scudamore,6 are in favour of such evolution; and the last gentleman conceives it even to be an essential part of the process; but other distinguished experimenters have not been able to detect it. Neither Dr. John Davy/ nor Dr. Duncan, Jr., nor Dr. Christison, could procure it during the coagu- lation of the blood. Dr. Turner8 suggests that the appearance of the carbonic acid, in the experiments of Vogel, Brande, and Scuda- more, might easily have been occasioned by casual exposure to the atmosphere, previous to the blood being placed under the receiver; but we have no reason for believing, that this source of fallacy was not guarded against, as much by one set of experimenters as by the other. Our knowledge, on this point, is confined then to the fact, that, by some, carbonic acid gas has been found exhaled during the process of coagulation ;—by others, not. Recent experiments, by Stromeyer,1* and by Gmelin, Tiedemann, and Mitscherlich,* would seem to decide, that the blood does not give off any free carbonic acid, but that it holds a certain quantity in a state of combination ; and that this combination is intimate is shown by the fact, mentioned by Miiller,' that blood, artificially impregnated with carbonic acid, yields no appreciable quantity of the gas, when subjected to the air- pump. M. Magnus,14 however, found, in his experiments, that not only venous, but arterial blood, contains carbonic acid, oxygen, and azote, and thart, as regards carbonic acid, arterial blood contains more than venous; and he accounts for the failure of those who have attempted to elicit carbonic acid from venous blood by the air- purnp, to the air in the receiver not having been sufficiently rarefied. a Dr. C. Taddei de Gravina, Annali Universali di Medicina, Febbrajo, 1840; and Brit, and For. Med. Rev. Jan. 1841, p. 227. b Annales de Chimie, t. xciii. c Philosophical Transactions for 1818, p. 181. d Lectures, &c. iii. 8. e Philosophical Transactions for 1820, p. 6; and an Essay on the Blood, p. 107, Lond. 1824. f Phil. Trans, for 1823, p. 506; and Edinb, Med. and Surg. Journ. xxix. 253. Since that time, however, Dr. Davy has succeeded in extricating it both from venous and arterial blood. See his Researches, Physiological and Anatomical, Dunglison's Amer. Med. Lib. Edit. p. 82, Philad. 1840. s Elements of Chemistry, 5th edit, by F. Bache, p. 607, Philad. 1835. h Schweigger's Journal fiir Chemie, u. s. w. lxiv. 105. 1 Tiedemann und Treviranus, Zeitschrifl fiir Physiologie, B. v. H. i.; Geddings's North Amer. Archives for July and August, 1835; and British and Foreign Med. Re- view, No. 9, p. 590, April, 1836. i Op. citat. p. 329. k Annales de Chimie et de Physique, Nov. 1837. VOL. II. 6 62 ABSORPTION. Prof. C. H. Schultz, of Berlin—who believes that the vesicles of the blood, in a perfect state, are composed of a membranous cover- ing, whose interior is filled with an aeriform fluid in the midst of which is found the nucleus*—succeeded in so evident a manner by the following simple method in extracting air from the blood, "that it is impossible to doubt there exists a great quantity of air in the vesicles." He completely filled a bottle with warm blood, flow- ing immediately from the vein of a horse, and hermetically sealed the bottle so that the cork was plunged into the blood, thus abso- lutely preventing the contact of air. The blood, in cooling, dimi- nished in volume, and thus produced a perfect vacuum in the upper part of the bottle; and in proportion as this took place, bubbles of air arose from the blood and filled the vacuum. Chemical analysis of this air demonstrated that it was carbonic acid. In arterial blood, he found oxygen mixed with more or les3 carbonic acid.b The expe- riments of Dr. Stevens,0 and of Dr. Robert E. Rogers,d also exhibit, that carbonic acid is contained in the blood. The latter observer found, when a portion of venous blood was placed in a bag of some membrane, and the bag was immersed in an atmosphere of some gas—as oxygen, hydrogen, or nitrogen—that carbonic acid was pretty freely evolved. During coagulation, the blood separates into two distinct portions; a yellowish liquid, called the serum ; and a red solid, known by the name of the clot, cruor, crassamentum, coagulum, placenta, insula or hepar sanguinis. The proportion of the serum to the crassamentum varies greatly in different animals, and in the same animal at dif- ferent times, according to the state of the system. The latter is more abundant in healthy, vigorous animals, than in those that have been impoverished by depletion, low living, or disease. Sir Charles Scudamore6 found, by taking the mean of twelve experiments, that the crassamentum amounted to 53.307 per cent, in healthy blood. The serum is viscous, transparent, of a slightly yellowish hue, and alkaline, owing to the presence of a little free soda. Its smell and taste resemble those of the blood. Its average specific gravity has been estimated at about 1.027.f But on this point, also, observers differ. Dr. John Davys found it to vary from 1.020 to 1.031. Mar- tine, Muschenbroek, Jurin, and Haller, from 1.022 to 1.037; Berze- lius, from 1.027 to 1.029; Christison,h from 1.029 to 1.031; Lauer,1 a London Lancet, Aug. 10, 1839, p. 713. b ibid. p. 714. c Philos. Transact, for 1834-5, p. 334. See, also, Dr. M. Edwards, in article «' Blood," Cyclopedia of Anat. and Phys. Part iv. p. 404, Lond. 1836. d Amer. Journ. of the Med. Sciences, Aug. 1836, p. 283. e Roget's Outlines of Physiology, by Dunglison, American Edition, 6 385 Philad 1839. 1 Bostock's Physiology, &c. edit. cit. p. 287; and Marcet, in Medico-Chirurv Trans iii. 363. s Researches Physiological and Anatomical, Dunglison's Amer. Med. Lib Edit p. 11, Philad. 1840. h On Granular Degeneration of the Kidneys, p. 61, London, 1839 and Dunsrlison's American Med. Library Edit, Philad. 1839. s 1 Hecker's Annalen, xviii. 393; and Burdach, op. cit iv. 29. VENOUS BLOOD. 63 from 1.009 to 1.011; whilst Thackraha found the extremes to be 1.004 and 1.080. At 158° of Fahrenheit, it coagulates; forming, at the same time, numerous cells, containing a fluid, which oozes out from the coagulum of the serum, and is called the serosity. It con- tains, according to Bostock, about Tyh 0f its weight of animal matter, together with a little muriate of soda. Of this animal mat- ter, a portion is albumen, which may be readily coagulated by means of galvanism; but a small quantity of some other principle is present, which differs from albumen and gelatine, and to which Marcetb o-ave the name muco-extractive matter, and Bostock,0 un- coagulable matter of the blood—as a term expressive of its most characteristic property. Serum preserves its property of coagula- ting, even when largely diluted with water. According to Brande,d it is almost pure liquid albumen, united with soda, which keeps it fluid. Consequently, he affirms, any reagent, which takes away the soda, will produce coagulation; and by the action of caloric, the soda may transform a part of the albumen into mucus. The action of the galvanic pile coagulates the serum, and forms globules in it analogous to those of the blood. From the analysis of serum, by Berzelius,e it appears to consist in 1000 parts;—of water, 903; albumen, 80; substances soluble in alcohol,—as lactate of soda and extractive matter, muriate of soda and potassa, 10; substances soluble in water,—as soda and animal matter, and phosphate of soda, 4; loss, 3. Marcet assigns it the following composition-.—water, 900 parts; albumen, 86.8; muriates of potassa and soda, 6.6; muco-extractive matter, 4; carbonate of soda, 1.65; sulphate of potassa, 0.35, and earthy phosphates, 0.60;— a result, which closely corresponds with that of Berzehus, who states that the extractive matter of Marcet is lactate of soda, united with animal matter. One of the most recent analysis is by M. Lecanu.f According to him, 1000 parts contain,—water, 906 parts; albumen, 78; animal matter, soluble in water and alcohol, 1.09; albumen combined with soda, 2.10; crystallizable fatty mat- ter, 1.20; oily matter, 1; hydrochlorate of soda and potassa, 6; sub'carbonate'and phosphate of soda, and sulphate of potassa, 2.10; phosphate of lime, magnesia and iron, with subcarbonate of lime and magnesia, 0.91; loss, 1.& Occasionally, the serum presents a whitish hue, which has given rise to the opinion that it contains chyle; but it would seem that this is fatty matter, and that it is always present. In the serum of the blood of spirit drinkers, Dr. Traill found a considerable portion of this substance, which has been considered to favour the notion, that the human body may, by » Inquiry into the Nature and Properties of the Blood, &c. Lond. 1819. b Medico-Chirurg. Transact, ii. 364. c Op. cit. p. ^92. d Philosoph. Transact, for 1809, p.373. e Medico-Chirurg. Transactions, iii. 231. t Journal de Pharmacie, xvii.; and Annales de Chimie, &,c, xlvm. 308. b See, also, Boudet, in Journal de Pharmacie, Juin, 1833 ; and Annales de Chimie, Hi. 337.' 64 ABSORPTION. intemperance, become preternaturally combustible; and has been used to account for some of the strange cases of spontaneous combus- tion, or rather of preternatural combustibility, which are on record. Dr. Christison has likewise met with fat mechanically diffused through the serum, like oil in an emulsion. On one occasion, he procured five per cent, of fat from milky serum, and one per cent. from serum which had the aspect of vvhey.a The crassamentum or clot is a solid mass, of a reddish-brown colour, which, when gently washed for some time under a small stream of water, separates into two portions,—colouring matter and fibrine. As soon as the blood is drawn from a vessel, the colouring matter of the red globules leaves the central nucleus free; these then unite, as we have seen, and form a network, containing some of the colouring matter and many whole globules. By washing the clot in cold water, the free colouring matter and the globules can be removed, and the fibrine will alone remain. When freed from the colouring matter, the fibrine is solid, whitish, insipid, inodorous, heavier than water, and without action on vege- table colours; elastic when moist, and becoming brittle by desicca- tion. It yields, on distillation, much carbonate of ammonia, and a bulky coal, the ashes of which contain a considerable quantity of phosphate of lime, a little phosphate of magnesia, carbonate of lime, and carbonate of soda. One hundred parts of fibrine, according to Berzelius, consist of carbon, 53.360; oxygen, 19.685; hydrogen, 7.021; azote, 19.934. Fibrine has been designated by various names. It is the gluten, coagulable lymph, and fibre of the blood of different writers. Its specific gravity is said to be greater than that of the serum; but the difference has not been accurately estimated, and cannot be great. The red particles are manifestly, however, heavier than either, as we find them subsiding during coagulation to the lower surface of the clot, when the blood has flowed freely from the orifice in the vein. Fibrine appears to be the most important constituent of the blood. It exists in animals, in which the red par- ticles are absent, and is the basis of the muscular tissue. Of late, it has been affirmed by Denis, Raspail, and others,b that the only difference between albumen and fibrine is, that the former is held in solution in water by the intervention of certain salts, whilst the latter remains suspended, and becomes solid by the ab- sence of those salts. The colouring matter of the blood, called, by some, cruorine, hematine, hematosine, zno-hematine, hemachroine, globuline, and ru- brine, has been the subject of anxious investigation with the analyti- cal chemist. We have already remarked, that it resides in distinct * Edinb. Med. and Surg. Journal, xvii. 235, and xxxiii. 274. b Raspail, Nouveau Systeme de Chimie Organique, iii. 244; Denis, Essai sur 1'\p. plication de la Chimie, p. 69, and Compte-rendu de l'Academie des Seiences~ No 13* Avril 1839; Polli Annali Universal! di Medicina, April, 1839, p. 25; Berzelius, Traite' de Chimie, vn. 73; Giacomoni, De la Nature, &c, du Sanjr, &c in Fncycl des Sciences Medicales, Avril, 1840, p. 429 ; and Mandl, Archives Generales de'Medecine, Nov. and Dec. 1840. ' VENOUS BLOOD. 65 particles or globules; and, in the opinion of the best observers, in the envelope of those globules. The globules themselves are insoluble in serum, but their colouring principle is dissolved by pure water, acids, alkalies, and alcohol. Raspail3 asserts, that the globules or nuclei are entirely soluble in pure water, but MM. Donne and Boudet, who repeated his experiments, declare that they are wholly insoluble, and Mullerb is of the same opinion. Great uncertainty has always existed regarding the cause of the colour of the globules. As soon as the blood was found to contain iron, the peroxide of which has a red hue, the colour of the red globules was ascribed to the presence of that metal. Fourcroy and Vauquelinc held this opinion, conceiving the iron to be in the state of subphosphate; and they affirmed, that if this salt be dissolved in serum by means of an alkali, the colour of the solution is exactly like that of the blood. Berzelius,4 however, showed, that the sub-phosphate of iron cannot be dissolved in serum by means of an alkali, except in very minute quantity; and that this salt, even when rendered soluble by phosphoric acid, communi- cates a tint quite different from that of the red globules. He found that the ashes of the colouring matter always yield oxide of iron in the proportion of ^th °f the original mass; whence it was in- ferred, that iron is somehow or other concerned in the production of the colour; but the experiments of Berzelius did not indicate the state in which that metal exists in the blood. He could not detect its presence by any of the liquid tests. The views of Berzelius, and the experiments on which they were founded, were not supported by the researches of Mr. Brande.6 He endeavoured to show, that the colour of the blood does not depend upon iron; for he found the indications of the presence of that metal as considerable in the parts of the blood that are devoid of colour as in the globules themselves; and in each it was present in such small quantity, that no effect, as a colouring agent, could be expected from it. He supposed that the tint of the red globules is produced by a peculiar, animal colouring principle, capable of combining with metallic oxides. He succeeded in obtaining a compound of the colouring matter of the blood with the oxide of tin; but its best precipitants are the nitrate of mercury and corrosive sublimate. Woollen cloths, impregnated with either of these compounds, and dipped in an aqueous solution of the colouring matter, acquires a permanent red dye, unchangeable by washing with soap. The conclusions of Brande have been supported by Vauquelin/ but the fact, connected with the presence of iron, seems to have been de- cided by Engelhart,s a young German chemist of distinction, who a Chimie Organique, p. 368, Paris, 1833. b Handbuch der Physiologie, Baly's translation, p. 105, Lond. 1838. c System Chym. ix. 207. d Med. Chirurg. Transactions, iii. 213. c Philosophical Transactions for 1812, p. 90. f Annales de Chimie et de Physique, torn. i. p. 9. s Edinburgh Med. and Surgical Journal, Jan. 1827; and Turner's Chemistry, 5th* Amer. Edit. p. 605, Philad. 1835. 6* 66 ABSORPTION. has demonstrated, that the fibrine and albumen of the blood, when carefully separated from colouring particles, do not contain a trace of iron; whilst he procured iron from the red globules by incinera- tion. He also succeeded in proving the presence of iron in the colouring matter by the liquid tests; for, on transmitting a current of chlorine gas through a solution of red globules, the colour entirely disappeared, white flocks were thrown down, and a transparent solution remained, in which the peroxide of iron was discovered by the usual reagents. The results, obtained by Engelhart, as regards the quantity of iron, correspond with those of Berzelius. These facts have since been confirmed by Rose,a of Berlin; and Wiirzer,b of Marburg, by pursuing Engelhart's method, by liquid tests, has detected the existence of the protoxide of manganese, like- wise. The proportion of iron does not appear to be more than one- half per cent.; yet, as it is contained only in the colouring matter, there is some reason for believing, that it may be concerned in the coloration of the blood, although probably in the form of oxide. The sulpho-cyanic acid has been detected in the saliva; and this acid, when united with the peroxide of iron, forms a colour exactly like that of venous blood ; so that it has been presumed it may be connected with the coloration of the blood, but this is not probable; for Dr. Stevens found, that venous blood is darkened by the sulpho- cyanic acid.c Very recently, M. Lecanud has subjected the hematosine or colour- ing matter to analysis, and found it to be composed of:—loss, repre- senting the weight of the animal matter, 97.742; subcarbonate of soda, alkaline muriates, subcarbonates of lime and magnesia, and phosphates of lime and magnesia, 1.724 ; peroxide of iron, 0.534. The result of his researches induces him to conclude, that the colour- ing matter is a compound of albumen with some colouring substance yet unknown. This substance yielded on analysis :—loss, 98.26; peroxide of iron, 1.74; and M. Lecanu suggests, that it may result from the combination of some animal matter with certain ferrugi- nous compounds, analogous to the cyanides. After all, therefore, our ignorance on this subject is still great; and all that we seem to know is, that the peroxide of iron is con- tained in the colouring matter of the blood. The redness of the fluid is one of its most obvious characteristics; and we are induced to esteem the change effected in the lungs, as regards colour, of emi- nent importance. It is, however, no farther so, than as it indicates the accomplishment of the conversion of venous into arterial blood. That there is nothing essential, connected with the mere coloration, is evinced by the fact, that there are many textures, of extreme deli- a Poggendorf's Annalen, vii. 81; and Annales de Chimie, &c. xxxiv. 268. b Schweigger's Journal, lviii. 481. c See, on this subject, Hermstadt, in Schweigger's Journ. 1832; J. Muller, op. cit. p. 125, and Brandt, art. Blut, in Encyclopad. Worterb. der Medicinisch Wisse'nschaft v. 606, Berlin, 1830. ' c"^"*"" d Annales de Chimie et de Physique, xlv. 5. VENOUS BLOOD. 67 cacy, which do not even receive red blood;—the tunica conjunctiva, and the serous membranes, for example. In the insect, again, the blood is transparent; in the caterpillar, of a greenish hue; and, in the internal vessels of the frog, yellowish. In man, it differs accord- ing to numerous circumstances; and the hue of the skin, which is partly dependent upon these differences, thus becomes an index of the state of individual health or disease. In the morbus cceruleus, cyanopathy or blue disease, the whole surface is coloured blue, espe- cially in those parts where the skin is delicate, as on the lips,— owing to a communication existing between the right and left sides of the heart, so that the blood can pass from one to the other, with- out proceeding through the lungs. The appearance, too, of the jaun- diced is familiar to all. The formation of the clot, and its separation from the serum, are manifestly dependent, upon the fibrine;' which, by assuming the solid state, gives rise to the coagulation of the blood ;—a phenomenon, which has occasioned much fruitless speculation and experiment; yet, if the views of RaspaiP were proved to be correct, it would be sufficiently simple. The alkaline character of the blood, and the production of coagulation by a dilute acid leave no doubt, in his mind, that an alkali is the menstruum of the albumen of the blood. The alkaline matter, he thinks, is soda, but more especially ammonia, of which, he says, authors take no account; but whose different salts are evident under the microscope. Now, "the carbonic acid of the atmospheric air, and the carbonic acid, which forms in the blood by its avidity for oxygen, saturate the menstruum of the albu- men, which is precipitated as a clot. The evaporation of the am- monia, and, above all, the evaporation of the water of the blood, which issues smoking from the vein, likewise set free an additional quantity of dissolved albumen, and the mass coagulates the more quickly as the blood is less aqueous." The process of coagulation is influenced by exposure to the air. Hewson affirmed, that it is promoted by such exposure, but Hunter was of an opposite opinion. If the atmospheric air be excluded,— by filling a bottle completely with recently drawn blood, and closing the orifice with a good stopper,—coagulation is retarded. Yet Sir C. Scudamore mentions the singular fact, that if blood be confined within the exhausted receiver of an air-pump, the coagulation is ac- celerated ; and MM. Gmelin, Tiedemann, and Mitscherlichb found that, under such circumstances, both venous and arterial blood coagulated as perfectly as under ordinary circumstances. The pre- sence of air is certainly not essential to the process. Experiments have also been made on the effect produced by different gases on the process of coagulation; but the results have not been such as to afford much information. It is asserted, for example, by some, that it is promoted by carbonic acid, and certain a Chimie Organique, p. 373. b Tiedemann und Treviranus, Zeitschiift far Physiol. B. v. Heft i. and in op. citat. 68 ABSORPTION. other of the irrespirable gases, and retarded by oxygen: by others, the reverse is affirmed; whilst Davya and M. Schroder van der Kolk* inform us, that they could not perceive any difference in the period of the coagulation of venous blood, when it was exposed to azote, nitrous gas, oxygen, nitrous oxide, carbonic acid, hydrocarbon, or atmospheric air. The time, necessary for coagulation, is affected by temperature. It is promoted by warmth; retarded, but not prevented, by cold. Hewson froze blood, newly drawn from a vein, and afterwards thawed it: it first became fluid, and then coagulated as usual. Hunter made a similar experiment with the like result. It is ob- viously, therefore, not from simple refrigeration that the blood coagulates. Sir C. Scudamore found, that blood, which begins to coagulate in four minutes and a half, in a temperature of 53° Fahr., undergoes the same change in two minutes and a half at 98°; and that, which coagulates in four minutes at 98° Fahr., becomes solid in one minute at 120°. On the contrary, blood, which coagulates firmly in five minutes at 60° Fahr., will remain quite fluid for twenty minutes at the temperature of 40° Fahr., and requires upwards of an hour for complete coagulation. The observations of Gendrin0 were similar. As a general rule, it would seem, from the experi- ments of Hewson,d Schroder van der Kolk,e and Thackrah/ that coagulation takes place most readily at the temperature of the body. During the coagulation of the blood, a quantity of caloric is disen- gaged. Fourcroy8 relates an experiment, in which the thermometer rose no less than 11° during the process; but as certain experiments of Hunter1" appeared to show, that no elevation of temperature oc- curred, the observation of Fourcroy was disregarded. It was, how- ever, confirmed by some experiments of Dr. Gordon,' of Edinburgh, in which the evolution of caloric during coagulation was rendered more manifest by moving the thermometer during the formation of the clot, first into the coagulated, and afterwards into the fluid part of the blood: he found, that by this means he could detect a difference of 6°; which continued to be manifested for twenty minutes after the process had commenced. In repeating the experiment on blood, taken from a person labouring under inflammatory fever, the ther- mometer was found to rise 12°. Sir C. Scudamore afFirms,J that the rate at which blood cools is distinctly slower than it would be, were no caloric evolved; and that he observed the thermometer to a Researches, &c. chiefly concerning nitrous oxide, p. 380, Lond. 1800; and Dr. John Davy, Researches, Physiological and Anatomical, Dunglison's Amer Med Libr Edit. p. 48, Philad. 1840 . b Dissert, sistens Sang. coag. histor. Groning. p. 81, 1820; and Burdach, op. citat. iv. 37. r c Hist, Anatom. des Inflammations, ii. 426, Paris, 1826. J Experiment. Inquiries, i. 19, Lond. 1774. e q cit 4g f Inquiry into the Nature, &c. of the Blood, p. 38, Lond. 1819. s Annales de Chimie, vii. 147.. h A Treatise on the Blood, &c. p 27 Lond 1794 1 Annals of Philosophy, vol. iv. 139. i An Essay on the Blood, p. 68 Lond 18*4 VENOUS BLOOD. 69 rise one degree at the commencement of coagulation. On the other hand, Dr. John Davy,a Mr. Thackrah, and Schroder van der Kolk,b accord with Mr. Hunter in the belief, that the increase of tempera- ture, from this cause, is very slight or null, whilst Raspail asserts that the temperature falls.0 Again we have to deplore the dis- cordance amongst observers; and it will perhaps have struck the render more than once, that such discordance applies as much to topics of direct observation as to those of a theoretical character. The discrepance, regarding anatomical and physical facts, is even more glaring than that which prevails amongst physiologists in account- ing for the corporeal phenomena; a circumstance, which tends to confirm the notion promulgated by one of the most distinguished teachers of his day, (Dr. James Gregory,) 'that " there are more false facts in medicine, (and the remark might be extended to the collateral or accessory sciences,) than false theories." There are certain substances, again, which, when added to the blood, prevent or retard its coagulation. Hewson found, that the sulphate and muriate of soda, and the nitrate of potassa were amongst the most powerful salts in this respect. The muriate of ammonia and a solution of potassa have the same effect. On the contrary, coagulation is promoted by alum, and by the sulphates of zinc and copper.d How these salts act on the fibrine, so as to prevent its particles from coming together, it is not easy to explain. But these are not the only inscrutable circumstances that affect the coagulation of the blood. Many causes of sudden death have been considered to have this effect:—lightning and electricity; a blow upon the stomach; injury of the brain; the bites of venomous ani- mals; certain narcotico-acrid vegetable poisons; also, excessive exercise and violent mental emotions, when they suddenly destroy, &c. Many of these affirmations doubtless rest on insufficient proof. Sir C. Scudamore, for example, asserts that lightning has not this effect. Blood, through which electric discharges were transmitted, coagulated as quickly as that which was not electrified; and, in animals, killed by the discharge of a powerful galvanic battery, the blood in the veins was always found in a solid state. We shall find, hereafter, that these affirmations have been con- sidered evidence that the blood may be killed; and, consequently, that it is possessed of life. All the phenomena, indeed, of coa- gulation, inexplicable in the present state of our knowledge, have been invoked to prove this position. The preservation of the fluid state, whilst circulating in the vessels—although agitation, when it is out of the body, does not prevent its coagulation—has been regarded, of itself, sufficient evidence in favour of the doctrine. Dr. Bostock,6 indeed, asserts, that perhaps the most obvious and consistent view of * Researches, Physiological and Anatomical, Dunglison's Amer. Med. Libr. Edit. p. fi, Philad. 1840. b Milllei's Physiology, Baly's translation, p. 98, Lond. 1838. c Chimie Ortraniqup, p. 361. d Magendie, Lectures on the Blood, in London Lancet, reprinted in Bell's Select Medical Libra iv, Philad. 183.9. e Physiology, 3d edit. p. 271, Lond. 1836. 70 ABSORPTION. the subject is, that fibrine has a natural disposition to assume the solid form, when no circumstance prevents it from exercising this inherent tendency. As it is gradually added to the blood, particle by particle, whilst that fluid is in a state of agitation in the vessels, it has no opportunity, he conceives, of concreting; but when it is suffered to lie at rest, either within or without the vessels, it is then liable to exercise its natural tendency. It is not our intention, at present, to enter into the subject of the vitality of the blood. The general question will be considered in a subsequent part of this work. We may merely observe, that, by the generality of physio- logists, the blood is presumed, either to be endowed with a principle of vitality, or to receive from the organs, with which it comes in con- tact, a vital impression or influence, which, together with the constant motion, counteracts its tendency to coagulation.3 Even Magendie,b —who is unusually and properly chary in having recourse to this method of explaining the notum per ignotius,—affirms, that instead of referring the coagulation of the blood to any physical influence, it should be considered as an essentially vital process; or, in other words, as affording a demonstrative proof, that the blood is endowed with life. Within a few years, Vauquelin has discovered in the blood a considerable quantity of fatty matter, of a soft consistence, which he, at first, considered to be fat; but Chevreul,0 after careful investi- gation, declared it to be identical with the matter of the brain and nerves, and to form the singular compound of an azotedfat. Cho- lesterine has been detected in it by Gmelin,d and by Boudet.6 Prevost and Dumas, Segalas, and others have likewise demonstrated the existence of urea in the blood of animals, from which the kidneys had been removed. Chemical analysis is, indeed, adding daily to our stock of information on this matter; and is exhibiting to us/that many of the substances, which compose the tissues, exist in the very state in the blood, in which we meet with them in the tissues. This is signally shown in the analysis of the blood by M. Lecanu/ who found it to be composed—in 1000 parts—of water, 785.590; albumen, 69.415; fibrine, 3.565; colouring matter, 119.626; crys- tallizable fatty matter, 4.300; oily matter, 2.270; extractive mat- ter, soluble in alcohol and water, 1.920; albumen combined with soda, 2.010; chlorides of sodium and potassium, alkaline phosphate, sulphate, and subcarbonates, 7.304; subcarbonate of lime and mag- nesia, phosphates of lime, magnesia, and iron, peroxide of iron, 1.414; loss, 2.586.* On this analysis, Dr. Prouth has remarked, that gelatine is never found in the blood, or any product of glandular a J. Miiller's Handbuch, u. s. w. Baly's translation, p. 97, Lond 18^8 b Precis, &c. ii. 234. <= Bostock's Physiology, p. 2D4. ' d Chimie iv 116*' e Journ. de Pharmacie, Paris, 1833, and Annales de Chimie Iii 337 1831AnnaleS ^ CHimie ^ ^ PhysiqUe' Xlviii- 308' and Jou™al 'de Pharmacie, Sept, s For an analysis of the Blood by Boudet; see Journal de Pharmacie Tnin U833 citat^lt^'" Treatise'Amer- edit ?• 230, Philad. 1834; see So/J' MouSf'op. VENOUS BLOOD. 71 secretion, and he adds, that a given weight of gelatine contains at least three or four per cent, less carbon than an equal weight of albu- men. Hence, the production of gelatine from albumen, he con- ceives, must be a reducing process. We shall see, under the head of Respiration, what application he makes of these considerations. Dutrochet believed that he had formed muscular fibres from albu- men by the agency of galvanism; and he supposed that the red par- ticles of the blood formed each a pair of plates, the nucleus being negative, the envelope positive:1 but Miillerb has shown, that all the appearances, which he attributed to different electric properties of the blood are explicable by the precipitation of the albumen and fibrine, in consequence of the decomposition of the salts of the serum, and of the oxidation of the copper wire used in the experi- ments,—both the decomposition of the salts and the oxidation of the copper being the usual effects of galvanic action. With the gal- vanometer he was unable to discover any electric current in the blood: he perceived no variation in the needle of the multiplicator, even when he inserted one wire into an artery of a living animal, and the other into a vein. Lastly,—some interesting experiments and considerations on the blood have been published by Dr. Benja- min G. Babington.6 The principal experiment was the following: He drew blood, in a full stream, from the vein of a person labour- ing under acute rheumatism, into a glass vessel filled to the brim. On close inspection, a colourless fluid was immediately perceived around the edge of the surface, and after a rest of four or five minutes, a bluish appearance was observed forming an upper layer on the blood, which was owing to the subsidence of the red parti- cles to a certain distance below the surface, and the consequent existence of a clear liquor between the plane of the red particles and the eye. A spoon, previously moistened with water, was now immersed into the upper layer of liquid, by a gentle depression of one border. The liquid was thus collected quite free from red particles, and was found to be an opalescent, and somewhat viscid solution, perfectly homogeneous in appearance. By repeating the immersion, the fluid was collected in quantity, and transferred to another vessel. That, which Dr. Babington employed, was a bottle, holding about 180 grains, of globular form, with a narrow neck and perforated glass stopper. The solution, with which the globular bottle was filled, though quite homogeneous at the time it was thus collected, was found, after a time, to separate into two parts, viz. into a clot a Sec, also, Bellingeri Experimenta in Electrieitatem Sanguinis, Urina? et Bilis Animalium, Aug. Taurin. 1826—cited by J. Muller, loc. cit; and Burdach, Die Phy- siologie als Erfahrungswissenschaft, iv. 15 und 103, Berlin, 1832. b Handbuch, u. s. w. Baly's translation, p. 133. c Med. Chirurg. Transact, vol. xvi. part 2, Lond. 1831; art. Blood, (Morbid Con- ditions of the) in Cyclop. Anat and Physiol., Lond. 1836—reprinted in Dunglison's American Medical Library and Intelligencer, for April, 1837; and Muller, in his Handbuch, u. s. w. translation, p. 109. See, also, on this subject, the views of Dr. John Davy, in his Researches, Physiological and Anatomical, Dunglison's Amer, Medical Libra, edit., p. 13, Philad. 1840. .72 ABSORPTION. of fibrine, which had the precise form of the bottle into whichi it was received, and a clear serum, possessing all the usua 1 cha ac er of the fluid. From this experiment, Dr. Babington inters, that buffed blood, to which we shall have to refer under another-head consists of only two constituents, the red particles, and a liquid to which he gives the name, liquor sanguinis-ihe plasma of Schultz so called by him, because he esteems it to be the true nutritive and plastic portion of the blood, from which all the organs of the body are formed and nourished. . . It has long been observed, that the blood of inflammation is longer in coagulating than the blood of health, and that the last portion of blood drawn from an animal, coagulates the quickest The imme- diate cause of this buffy coat is thus explained by Dr. Babington. The blood, consisting of liquor sanguinis and insoluble red particles, preserves its fluidity long enough to permit the red particles, which are of greater specific gravity, to subside through the liquor sanguinis. At length, the liquor sanguinis separates, by a general coagulation and contraction, into two parts, and this phenomenon takes places uniformly throughout the liquor. That part of it, through which the red particles had time to fall, furnishes a pure fibrine or buffed crust, whilst the portion, into which the red particles had descended, fur- nishes the coloured clot. This, in extreme cases, may be very loose at the bottom, from the great number of red particles collected there, each of which has supplanted its bulk of fibrine, and consequently diminished its firmness in that part. There is, however, with this limitation, no more fibrine in one part of the blood than another. It is a well known fact, that the shape of the vessel, into which the blood is received, influences the depth of the buff.b The space, left bv the gravitation of the red particles, bears a proportion to the whole perpendicular depth of the blood, so that in a shallow vessel scarcely any buff may appear, whilst the same blood in a deep vessel would have furnished a crust of considerable thickness; but Dr. Babington asserts, that even the quantity of the crassamentum is dependent, within certain limits, on the form of the vessel. If this be shallow, the crassamentum will be abundant; if approaching the cube or sphere in form, it will be scanty. The difference is owing to the greater or less distance of the coagulating particles.of fibrine from a common centre, which causes a more or less powerful adhe- sion and contraction of these particles. This is a matter of practi- cal moment, inasmuch as blood is conceived to be thick or thin, rich or poor, in reference to the quantity of crassamentum; and pathological views are entertained in consequence of conditions, which after all depend not perhaps on the blood itself, but on the vessel into which it is received. To remove an objection, that might be urged against a general conclusion deduced from the experiment cited,—that it was made a See an analysis of Professor Schultz's Views, in Lond. Lancet Aug 1839 d 712 b Dr. J. Davy, op. citat. p. 45 > S- , P- ■ VENOUS BLOOD. 73 upon blood in a diseased state, Dr. Babington received some healthy blood into a tall glass vessel half filled with oil, which enabled the red particles to subside more quickly than would otherwise have been the case. This blood was found to have a layer of liquor sanguinis, which formed a buffy coat, whilst a portion of the same blood, received into a similar vessel, in which there was no oil, had no buff. Hence, it would appear, that healthy blood is similarly constituted as blood disposed to form a buffy coat, the only dif- ference being, that the former coagulates more quickly than the latter. Dr. J. Davy,a however, has observed, that inflammatory blood, in some instances, does not coagulate more slowly than healthy blood, and as from the experiments of J. Mullerb it would appear that the presence of fibrine in the blood favoured the sub- sidence of the red particles, Muller was led to infer, that the forma- tion of the burly coat may arise from the blood containing a larger quantify of fibrine, which the blood of inflammation is known to do: So that the principal causes, he thinks, of the subsidence of the red particles and the formation of the buffy coat in inflammatory blood appear to be—the slow coagulation of the blood and the increased quantity of fibrine.6 Dr. Babington was led to believe, from his experiments, that fibrine and serum do not exist, as such, in circulating blood, but that the liquor sanguinis, when removed from the circulation, and no longer subjected to the laws of life, has then, and not before, the property of separating into fibrine and serum. This separation, which may be regarded as the death of the blood, may under disease, take place within the body, but never, he thinks, con- sistently with healthy action/1 It need scarcely be said, that venous blood must differ somewhat in its character in the different veins. In its passage through the capillary or intermediate circulation, the arterial blood is deprived of several of its elements, but this deprivation is different in different parts of the body. The blood, for example, which returns from the salivary glands, must vary from that which returns from the kid- neys. In the blood of the abdominal veious system, the greatest variation is observed. Professor Schultz* has, of'late, inquired into the chemical and physiological differences between the blood of the vena portoe and that of the arteries and other veins. He found, that it is not reddened by the neutral salts, or by exposure to the atmo- sphere, or to oxygen; that it does not generally coagulate; that it contains 5.23 per cent, less fibrine; proportionably more cruor and a Philosophical Transactions, for 1822. b Op cit it. p. 117; and Migeadie, Licons sur le Sing, &c, or translation in Lond. Lancet, and in Bell's Med. Library edition, p. 77, Phihd. 1839. c Dr. J. Davy, Researches, &c. p. 28. d See, connected with the buffy coat and the life of the blood, the remarks in the latter part of this volume, under the head of Li'e. e Rust, Magazin fur die gesammt. Heilkund. Bde. 44, H. i. See, also, Ancell's Lec- tures'on the Physiology, &c. of the Blood, Feb. 1, 1840, p. 682; and Prof. Schultz, in Lond. Lancet, Aug. 10, 1839, p. 717. VOL. II. 7 74 ABSORPTION. less albumen; and has twice as much fat in its solid parts as that of the arteries and the other veins;—the proportions being as 101- lows: Blood of the vena portse - - 1.66 per cent. ---- of the arteries - "•"" ---- of the other veins - - ".83 The character and quantity of the different constituents of the blood, as well as its coagulation, vary greatly in disease; and the investi- gation is one of the most important in the domain of pathology. Other facts connected with the vital fluid, its quantity, &c, will be consideied, after we have inquired into the changes produced on the venous blood in the lungs, through the agency of respiration. 3. PHYSIOLOGY OF VENOUS ABSORPTION. Whilst the opinion prevailed universally, that the lymphatics are the sole agents of absorption, the fluid, circulating in the veins, was considered to consist entirely of the residue of the arterial blood, after it had passed through the capillary system, and been subjected to the different nutritive processes there effected. We have already seen, however, that the drinks are absorbed by the mesenteric veins; and we shall hereafter find, that various other substances enter the venous system by absorption. It is obvious, therefore, that the venous blood cannot be simply the residue of arterial blood; and we can thus account for the greater capacity of the venous system than of the arterial. The facts, which were referred to, when considering the absorp- tion of fluids from the intestinal canal, may have been sufficient to show, that the veins are capable of absorbing; as the odorous and colouring properties of substances were distinctly found in the me- senteric veins. A question arises, whether any vital elaboration is concerned, as in the case of the chyle, or whether the fluid, when it attains the interior of the vessel, is the same as without? Adelon,b —who, with many of the German physiologists, believes in both venous and lymphatic absorption, and venous and chyliferous ab- sorption,—conceives, that a vital action takes place at the very mouths of the venous radicles, precisely similar to that which is presumed to be exerted at the mouths of the lymphatic and chyli- ferous radicles. In his view, consequently, an action of elaboration is exerted upon the fluid, which becomes, in all cases, converted into venous blood at the very moment of absorption, as chyle and lymph are elaborated under similar circumstances. " ?f: ™.th™ subject Babington op chat; G. O. Rees's Analysis of the Blood and Urine, in Health and Disease Lond 1836; Mr. E. A. Jennings's Report on the Chemistry of the Blood, as illustrating its Pathology, in Transact, of the Provincial Andral and Gavarret, Arehiv. General. Serie 3, torn. viii. p. 501. b Art. Absorption, in Diet, de Medecine, 2de edit i. 239 Piria ioqa , t>, logie deTHomme, 2de edit iii. 113, Paris, 1829. ' ""■ 1832 ; and Physl°- VENOUS (PHYSIOLOGY.) 75 On the other hand, Magendie,1 Fodera,b and others maintain, that the substance soaks through the vessel, when possessed of the necessary tenuity; that this act of imbibition is purely physical, and consists m the introduction of the absorbed materials through the pores of the veins by capillary attraction. In their view, therefore, the fluid within the vessel should be the same as that without. In favour of the vital action of the veins we have none of that evidence, which strikes us in regard to the chyliferous and lym- phatic vessels. In these last we invariably find fluids, identical—in all essential respects—in sensible and chemical characters; and never containing extraneous matter, if we make abstraction of cer- tain sabs, which have been occasionally met with in the thoracic duct. In the veins, on the other hand, the sensible properties of odorous and colouring substances have been apparent. It may, how- ever, be remarked, that the fluid, flowing in the veins, is as identical in composition as the chyle or the lymph. This is true; but it must be recollected, that the greater part of it is the residue of the arterial blood; and that its hue and other sensible properties are such as to disguise any absorbed fluid, not itself possessing strong characteristics. The fact,—now indisputable—that various sub- stances, placed outside the veins, have been detected in the blood within, is not only a proof, that the veins absorb; but that no action of elaboration has been exerted on the absorbed fluid. Of this we have the most convincing proof in some experiments by Magendie.c In exhibiting to his'class the mode in which medicines act upon the system, he showed, on a living animal, the effects of introducing a quantity of water, of the temperature of 104° Fah., into the veins. In performing this experiment, it occurred to-him to notice what would be the effect produced by artificial plethora on the pheno- mena of absorption. Having injected nearly a quart of water into the veins of a dog of middle size, he placed in the cavity of the pleura a small dose of a substance with the effects of which he was fa- miliar, and was struck with the fact, that these effects did not exhibit themselves for several minutes after the ordinary period. He imme- diately repeated the experiment, and with a like result. In seve- ral other experiments, the effects appeared at the ordinary time, but were manifestly feebler than they ought to have been from the dose of the substance employed, and were kept up much longer than usual. In another experiment, having introduced as much water as the animal could bear without perishing,—which was about two quarts, —the effects did not occur at all. After having waited nearly half an hour for their developement, which generally required only about two minutes, he inferred, that if the distension of the blood-vessels was the cause of the defect of absorption, provided the distension were removed, absorption ought to take place. He immediately 1 Precis, &c. 2de edit ii. 271. b Rechcrchcs Experimentalcs sur l'Exhalation et 1'Absorption, Paris, 1823. c Op. chat ii. 273. 76 ABSORPTION. bled the animal largely in the jugular; and to his great satisfaction, found the effects manifesting themselves as the blood flowed. He next tried whether, if the quantity of blood were diminished at the commencement of the experiment, absorption would be more rapid; and the result was as he anticipated. An animal was bled to the extent of about half a pound ; and the effects, which did not ordina- rily occur until after the second minute, appeared before the thir- tieth second. As the results of these experiments seemed to show, that absorption is evidently in an inverse ratio to the degree of vas- cular distension, Magendie inferred, that it is effected physically; is dependent upon capillary attraction; and that it ought to take place as well after death as during life. To prove this, he instituted the following experiments:—He took a portion of the external jugu- lar vein of a dog, about an inch long and devoid of branches. Re- moving carefully the surrounding cellular tissue, he attached to each of its extremities a glass tube, by means of which he kept up a cur- rent of warm water within it. He then placed the vein in a slightly acid liquor, and carefully collected the fluid of the current. During the first few minutes, it exhibited no change; but, in five or six minutes, became sensibly acid. This experiment was repeated on veins taken from the human subject, with the same results ; and not only with veins but with arteries. Similar experiments were next made on living animals. He took a young dog, about six weeks old, whose vessels were thin, and, consequently, best adapted for the success of the experiment, and exposed one of its jugular veins. This he dissected entirely from the surrounding matter, and espe- cially from the cellular tissue and the minute vessels, which ramified upon it, and placed it upon a card, in order that there might be no point of contact between it and the surrounding parts. He then let fall upon its surface and opposite the middle of the card a thick, watery solution of nux vomica,—a substance, which exerts a pow- erful action upon dogs. He took care that no particle of the poison touched any thing but the vein and card, and that the course of the blood, within the vessel, was free. Before the end of three minutes, the effects which he expected, appeared,—at first feebly, but after- wards with so much activity, that he had to prevent fatal results by inflating the lungs. The experiment was repeated on an older animal with the same effects: except that, as might be expected, they were lono-er in exhi- biting themselves, owing to the greater thickness of the^parietes of the veins.3 Satisfied, as regarded the veins, he now directed his attention to the arteries; and with like results. They were, however, slower in appearing than in the case of the veins, owing to the tissue of the arteries being less spongy than that of the veins. It required more Pllilld.^8" JaCkS°n' ^ ait' Abs°Tpti0n' Amer- Cycl°P- ^ Pract. Medicine, VENOUS (PHYSIOLOGY.) 77 than a quarter of an hour for imbibition to be accomplished. In one of the rabbits, which died under the experiment, they had an oppor- tunity of discovering, that the absorption could not have been effected bv any small veins, that had escaped dissection. One of the carotids—the subject vessel of the experiment—was taken from the body ; and the small quantity of blood, adherent to its inner sur- face, was found by Magendie, and his friends who assisted at the experiment, to possess the extreme bitterness which characterizes the nux vomica. These experiments were sufficient to prove the fact of imbibition by the large vessels, both in the dead and in the living state. His at- tention was now directed to the small vessels, which seemed, a priori, favourable to the same action, from their delicacy of organization. He took the heart of a dog, which had died the day before, and injected, into one of the coronary arteries, water at the temperature of 86° of Fah. The water readily returned by the coronary vein into the right auricle, whence it was allowed to flow into a vessel. Half an ounce of water, slightly acidulated, was now placed in the pericardium. At first, the injected fluid did not exhibit any signs of acidity; but, in five or six minutes, the evidences of it were unequi- vocal. From these facts, Magendie" draws the too exclusive deduc- tion, that " all blood-vessels, arterial and venous, dead or living, large or small, possess a physical property, capable of perfectly account- ing for the principal phenomena of absorption." We shall endeavour to show, that it explains only certain varieties of absorption,—those in which the vessel receives the fluid unmodified,—but that it is unable to account for absorptions, in which an action of selection and elaboration is necessary. Mayerb injected prussiate of potassa into the trachea of different animals through a small aperture; and in from two to five minutes the salt was detected in the blood of the left side of the heart. Since these experiments were performed, others have been insti- tuted by M. Segalas0 and Fodera,d from which the latter physio- logist attempts to show, that exhalation is simply transudation of substances from the interior of vessels to the exterior; and that ab- sorption is imbibition, or the passage of fluids from the exterior to the interior. The facts adduced by Fodera in support of his views will be considered under the head of secretion. They chiefly go to show the facility with which substances penetrate the different vas- cular parietes and other tissues of the body ; an action, which he found to be singularly accelerated by the galvanic influence. Some prussiate of potassa was injected into the cavity of the pleura ; and sulphate of iron was introduced into the abdomen of a living animal. » Precis, &c. ii. 283. b Meckel's Arehiv. B. iii., and Windischmann in Encyclop. Worterb. u. s. w. B. x. s. 300, Berlin, 1834. c Magendie's Journal de Physiol, ii. 217. d Recherches Experiment, sur 1'Absorption, &c. Paris, 1824, and Magendie's Jour- nal, &c. iii. 35. 7* 78 ABSORPTION. Under ordinary circumstances, it requires five or six minutes, before the two substances meet bv imbibition through the diaphragm ; but the admixture is instantaneous if the diaphragm be subjected to a slight galvanic current. The same fact is observed, it one of the liquids be placed in the urinary bladder, and the other in the abdo- men ; or the one in the lung, and the other in the cavity ol the pleura. It was further found, that, according to the direction of the current, the union took place in one or other cavity. Dr. Bos- tock,a in commenting on these cases, thinks it must be admitted, that they "go very far to prove that membranes, perhaps, even during life, and certainly after death, before their texture is visibly altered, have the power of permitting the transudation of certain fluids." That such imbibition occurs during life appears to us indisputablv proved. If the clear and decisive experiments of Ma- gendie and'Fodera did not establish it, the additional testimony,— afforded by Lawrence, Coates and Harlan; by Dutrochet, Faust, Mitchell, Rogers, Draper, and others,—would command it. By the different rates of penetrativeness of different fluids, and of per- meability of different tissues, we can explain, why imbibition may occur in .one set of vessels and not in another; and why there may not be the same tendency to transude from the vessel, after the'fluid has entered it by imbibition; indeed, the constant current, established in the interior of the vessel, would be a sufficient reply to this suggestion.b Adelon,c again, affirms, that we ought, under the view of im- bibition, to find imbibed substances in the arteries and lymphatics, also. A sufficient objection to this would be,—the comparative tardiness, with which the former admit of the action; and the selection, and consequently, refusal,, exerted by the latter; but even here we occasionally find evidences of adventitious imbibition ; as in the case of salts, which—as we have seen—have been detected in the thoracic duct, when introduced into the cavity of the abdomen. The two following experiments by Prof. J. K. Mitchell,d which are analogous to numerous others, performed in the investigation of this subject, ratify the fact of imbibition in the living tissues ::—a quantity of a solution of acetate of lead was thrown into the peri- toneal cavity of a young cat; and sulphuretted hydrogen was passed, at the same time, into the rectum. In four minutes, the poisonous gas killed the animal. Instantly on its death, the peritoneal coat of the intestines, and the parietes of the cavity in contact with them, were found lined with a metallic precipitate, which adhered to the surface, and was removable by nitric acid, moderately diluted. It was the characteristic precipitate of sulphuretted hydroo-en, when acting on lead. In another experiment on a cat, a solution of acetate of lead was placed in the thorax, and sulphuretted hydro- gen in the abdomen. Almost immediately after the entrance of the * Physiology, edit. cit. p. 629. »> Bostock, ibid. p. 615. c Physiologie de I'Homme, torn. iii. <• American Journal of the Medical Sciences, vii. 44, Philad, 1830. VENOUS (PHYSIOLOGY.) 19 sulphuretted hydrogen into the abdominal cavity, death ensued. On inspecting the thoracic side of the diaphragm, which was done as quickly as possible, the tendinous part of it exhibited the leaden appearance of the precipitate by sulphuretted hydrogen. The experiment of J. Muller, referred to in a preceding page (p. 35), exhibits the same fact. It may be concluded, then, that all living tissues imbibe the liquid matters which come in contact with them; and that the same oc- curs to solid matters, provided they are soluble in the humours, and especially in the serum of the blood. But although imbibition is doubtless effected by living tissues, too great a disposition has been manifested to refer all the vital phenomena of absorption and ex- halation to it.a Even dead animal membrane has been supposed to exert a positive agency in respect to bodies placed on either side of it. In the first volume of this work (p. 4G), we referred to the phe- nomena of imbibition, and explained how endosmose and exosmose, or, in other words, imbibition and transudation are effected through organic membranes by virtue of their porosity; and a careful exa- mination of those phenomena would lead us to the belief, that the membrane exerts no agency except in the manner suggested by Dutrochet. This is signally manifested in experiments with porous, inorganic substances; and it has been ingeniously and ably shown by Dr. Draper,b of Hampden Sidney College, Virginia, who found that all the phenomena were elicited, when, instead of an organic tissue, fissured glass was employed. Sir David Barry ,c—indifferent memoirs laid before the Academie Royale de Medecine, the Acadimie Royale des Sciences of Paris, and the JMedico-Chirurgical Society of London,—has maintained, that the whole function of external absorption is a physical effect of atmospheric pressure; and " that the circulation, in the absorbing vessels and in the great veins, depends upon this same cause in all animals possessing the power of contracting and dilating a cavity, around that point, to which the centripetal current of their circula- tion is directed." In other words, it is the opinion of this gentle- man, that, at the time of inspiration, a tendency to a vacuum is produced in the chest by its expansion; and as. the atmospheric pressure, externally, thus ceases to be counterbalanced, the pressure without occasions the flow of blood towards the heart along the veins. The consideration of the forces that propel the blood will afford us an opportunity of saying a few words on this view; at present, we shall only observe, that he ascribes absorption,—which he ex- plicitly states to be, in his opinion, extra vital,—to the same cause. In proof of this, he instituted numerous experiments, in which the absorption of poisons from wounds appeared to take place or to * Muller's Handbuch der Physiologie, u. s. w., and Baly's translation, p. 248 and 282. b See his various papers in Amer. Journ. of the Med. Sciences, for Aug. 1836, p. 276 ; Nov. 1837, p. 122 ; May, 1838, p. 23, and August, 1838,—more especially the two last. c Experimental Researches on the Influence of Atmospheric Pressure upon the Cir- culation, &c. Lond. 1826. 80 ABSORPTION. be suspended according as the wounds continued, as he conceived, exposed to atmospheric pressure, or were freed from its influence by the application of a cupping-glass. The same quantity of poi- son, which, under ordinary circumstances, destroyed an animal in a few seconds, was rendered completely innocuous by the exhaust- ed vessel; and what is singular, even when the symptoms had com- menced, the application of the cupping-glass had the effect of speedily and completely removing them;—a fact of essential importance in its therapeutical relations. In commenting on the conclusions of Sir D. Barry, Messrs. Ad- dison and Morgan,1—who maintain the doctrine, that all poisonous agents produce their specific effects upon the brain, and genera] system, through the sentient extremities of nerves, and through the sentient extremities of nerves only; and that, when introduced into the current of the circulation in any way, their effects result from the impression made upon the sensible structure of the blood- vessels, and not from their direct application to the brain itself,— contend, that the soft parts of the body, when covered by an ex- hausted cupping-glass, must necessarily, from the pressure of the edges of the glass, be deprived, for a time, of all connexion, both nervous and vascular, with the surrounding parts;—that the nerves must be partially or altogether paralysed by compression of their trunks, and that, from the same cause, all circulation through the veins and arteries situate within the area of the glass must cease; that the rarefaction of the air within the glass being still farther in- creased by means of the small pump attached to it, the fluids, in the divided extremities of the vessels, are forced into the vacuum, and, with these fluids, either a part or the whole of the poison, which had been introduced; and that, in such a condition of parts, the com- pression, on the one hand, and the removal of the poison from the wound on the other, will sufficiently explain the result of the experi- ment, either according to the views of those who conceive the im- pression to be made on the nerves of the blood-vessel, or of those who conceive that the agent must be carried along with the fluid of the circulation to the part to be impressed. Such would seem to be the main facts, regarding the absorbent action of the veins, which rests on as strong evidence as we pos- sess regarding any of the functions of the body; yet, in the treatise on Animal and Vegetable Physiology, by Dr. Roget,b we find it passed by without a comment! We have still to inquire into the agents of internal, and adventi- tious absorption. INTERNAL ABSORPTION. On this point but few remarks will be necessary after the ex position of the different vascular actions concerned'in absorption. * An Essay on the Operation of Poisonous Agents upon the Livino- T*nA„ t j -i oon b Bridgewater Treatise, Lond. 1834, Amer. Edit. Philad1836 Body>Lond-1829- INTERNAL. 81 The term comprehends interstitial absorption, and the absorption of recrementitiaf, and of excrementitialfluids. The first comprises the agency, by which the different textures of the body are decomposed and conveyed into the mass of blood. It will be considered more at length under the head of Nutrition ; the second, that of the various fluids, effused into cavities; and the third, that which is effected on the excretions in their reservoirs or excretory ducts. All these must be effected by one of the two sets of vessels, pre- viously described;—the lymphatics, or veins, or both. Now we have attempted to show, that an action of selection and elaboration is exerted by lymphatic vessels; whilst we have no evidence of such action in the case of the veins. It. would follow, then, that all those varieties of internal absorption, in which the substance, when re- ceived into the vessel, possesses different characters from those it had when without, must be executed by lymphatics; whilst those, in which no conversion occurs, take place by the veins. In the constant absorption, and corresponding deposition, which is inces- santly going on in the body, the solid parts must be reduced to their elements, and a new compound be formed; inasmuch as we never find bone, muscle, cartilage, membrane, &c, existing in these states in any of the absorbed fluids; and it is probable, therefore, that, at the radicles of the lymphatic vessels, they are all converted into the same fluid—the lymph—in like manner as the heterogeneous sub- stances, existing in the intestinal canal, afford to the lacteals the ele- ments of a fluid, the character of which is always identical. On the other hand, when the recrementitial fluid consists simply of the serum of the blood, more or less diluted, there can be no obstacle to the passage of its aqueous portion immediately through the coats of the veins by imbibition, whilst the more solid part is taken up by the lymphatic vessels. In the case of the excrementitious fluids, there is reason to believe, that absorption simply removes some of their aqueous portions, and this, it is obvious, can be effected directly by the veins, through imbibition. The facts, connected with the ab- sorption of substances from the interior of the intestine, have clearly shown, that the chyliferous vessels alone absorb chyle, and that the drinks and adventitious substances pass into the mesenteric veins. These apply, however, to external absorption only; but similar ex- periments and arguments have been brought forward by the sup- porters of the two opinions, with regard to substances placed on the peritoneal surface of the intestine, and other parts of the body. Whilst some affirm, that they have entered the lymphatics; others have only been able to discover them in the veins. John Hunter, having injected water, coloured with indigo, into the peritoneal cavity of animals, saw the lymphatics, a short time afterwards, filled with a liquid of a blue colour. In animals, which had died of pulmonary or abdominal hemorrhage, Mascagni found the lymphatics of the lungs and peritoneum filled with blood; and he asserts, that, having kept his feet for some hours in water, swelling of the inguinal glands 82 ABSORPTION. supervened, with transudation of a fluid through the gland; coryza, &c. Desgenettes observed the lymphatics of the liver containing a bitter, and those of the kidneys a urinous, lymph. Sommering detected bile in the lymphatics of the liver; and milk in those of the axilla." Dupuytren relates a case, which Magendie conceives to be much more favourable to the doctrine of absorption by the lym- phatic vessels than any of the others. A female, who had an enormous tumour at the upper and inner part of the thigh, with fluctuation, died at the H6:el Dieu, of Paris, in 1810. A few days before her death, inflammation occurred in the subcutaneous cellular tissue, at the inner part of the tumour. The day after dissolution, Dupuytren opened the body. On dividing the integuments, he noticed white points on the lips of the incision. Surprised at the appearance, he carefully dissected away some of the skin, and observed the subcutaneous cellular tissue overrun by whitish lines, some of which were as large as a crow's quill. These were evidently lymphatics, filled with puriform matter. The glands of the groin, with which these lymphatics communicated, were injected with the same matter. The lymphatics were full of the fluid, as far as the lumbar glands; but neither these glands nor the thoracic duct presented any trace of it.b On the other hand, multiplied experiments have been instituted, by throwing coloured and odorous substances into the great cavities of the body; and these have been found always in the veins, and never in the lymphatics. 'To the experiments of Hunter, objections have been urged, simi- lar to those adduced against his experiments to prove the absorption of milk by the lacteals; and some sources of fallacy have been pointed out. The blue colour, which the lymphatics seemed to him to possess, and which was ascribed to the absorption of indigo, was noticed in the experiments of Messrs. Harlan, Lawrence, and Coates;0 but they discovered that this was an optical illusion. What they saw was the faint blue, which transparent substances assume, when placed over dark cavities. Mr. Mayod has also affirmed that the clryliferous lymphatics always assume a bluish tint a short time after death, even when the animal has not taken indigo. The cases of purulent matter, &c, found in the lymphatics, may be accounted for by the morbid action having produced disorganiza- tion of the vessel, so that the fluid could enter the lymphatics directly; and, if once within, its progression can be readily under- stood. Magendiee asserts, that Dupuytren and himself performed more a See Weber's Hildebrandt's Handbuch der Anatomic, iii. 123, and Muller's Hand buch der Physiologie, u. s. w. Baly's translation, p. 277, Lond. 1838. b Magendie, Precis, &c. 2de edit ii. 195, et seq ; and Adelon, art. Absorption Diet de Med. 2de edit i. 239, and Physiologie de I'Homme, 2de edit iii 65 Paris 1829 c Harlan's Physical Researches, p. 459, Philad. 1835. d Outlines of Human Physiology, 3d edit. Lond. 1833, « Op. cit. ii. 211. INTERNAL. 83 than one hundred and fifty experiments, in which they submitted to the absorbent action of serous membranes a number of different fluids, and never found any of them within the lymphatic vessels. The substances, thus introduced into the serous cavities, produced their effects more promptly, in proportion to the rapidity with which they are capable of being absorbed. Opium exerted its narcotic influence, wine produced intoxication, &c, and Magendie found, from numerous experiments, that the ligature of the thoracic duct in no respect diminished the promptitude with which these effects appeared. The partisans of lymphatic absorption, however, affirm that even if these substances are met with in the veins, it by no means follows that absorption has been effected by that order of vessels; for, as we have seen, the lymphatics, they assert, have fre- quent communications with the veins; and, consequently, they may still absorb and convey their products into the venous system. In reply to this, it may be urged, that all the vessels—arterial, venous, and'lymphatic—appear to have Communication with each other; but that there is no reason to believe, that the distinct offices, per- formed by them, are, under ordinary circumstances, interfered with; and, again, where would be the necessity for these interme- diate lvmphatic vessels, seeing that imbibition is so readily effected by the veins'? The axiom—quod fieri potest per pauca, non debet fieri per multa—is here strikingly appropriate. The lymphatics, too, as we have endeavoured to show, exert an action of selection and elaboration on the substances exposed to their agency; but, in the case of venous absorption, we have not the slightest evidence that any such selection exists,—odorous and coloured substances retaining, within the vessel, the properties they had without. Lastly, where would be the use of the distinct, lymphatic circulation open- ing into the thoracic duct, seeing that the absorbed matters might enter the various venous trunks directly through these supposititious, communicating lymphatics; and ought we not occasionally to be able to detect in the lymphatic trunks at least some evidence of those substances, which their fellows are supposed to take up and convey into the veins? These carrier lymphatics have obviously been devised to support the tottering fabric of exclusive lymphatic absorption; undermined, as it has been, by the powerful facts and reasonings that have been adduced in favour of absorption by the veins. From the whole of the preceding history of absorption, we are of opinion, that the chyliferous and lymphatic vessels form only chyle and lymph, refusing all other substances, with the exception of saline matters, which enter probably by imbibition ;a that the veins admit every liquid, which possesses thenccessary tenuity; and that, whilst all the absorptions, which require the substances, acted upon, to be decomposed and transformed, are effected by the chyliferous and lvmphatic vessels; those that are sufficiently thin, and demand no « Milller's Handbuch u. s. w. Baly's translation, p. 278, Lond. 1838. 84 ABSORPTION. alteration, are accomplished directly through the coats of the veins by imbibition; and we shall see, that such is the case with several of the transudations or exhalations.* ACCIDENTAL ABSORPTION. The experiments, to which reference has been made, have shown, that many substances, adventitiously introduced into various cavi- ties, or placed in contact with different tissues, have been rapidly absorbed into the blood, without experiencing any transformation. Within certain limits, the external envelope of the body admits of this function; but by no means to the same extent as its prolonga- tion, which lines the different excretory canals. The absorption of drinks is sufficient evidence of the activity of the function, as regards the gastro-intestinal mucous membrane. The same may be said of the pulmonary mucous membrane. Through it, the oxygen and azote pass to reach the blood in the lungs, as well as the carbonic acid in its way outwards. Aromatic substances, such as spirit of turpentine, breathed for some time, are detected in the urine, proving ihat their aroma has been absorbed; and it is by ab- sorption that contagious miasmata probably produce iheir pestife- rous agency. Dr. Madden,b however, thinks, that the lungs do not absorb watery vapour with the rapidity, or to the extent that has been imagined: whilst Dr. A. Combec hazards the hypothesis, ihat owing apparently to the extensive absorption of aqueous vapour by the lungs, the inhabitants of marshy and humid -districts, as the Dutch, are remarkable for the predominance of the lymphatic system. Not only do the tissues, as we have seen, suffer imbibition by fluids, but by gases also : the experiments of Chaussier, and Mitchell astonish us by the rapidity and singularity of the passage of gases through the various tissues;—the rapidity varying according to the permeability of the tissue, and the penetrative power of the gas. a. Cutaneous Absorption. On the subject of cutaneous absorption, much difference of opinion has prevailed; some asserting it to be possible to such an extent, that life may be preserved, for a time, by nourishing baths. It has also been repeatedly affirmed, that rain has calmed the thirst of shipwrecked mariners who have been, for some time, deprived of water.*1 It is obvious, from what we know of absorption, that, in a Dr. Handyside, in Dublin Journ. of Med. and Chem. Science, for Sept 1835 • and Amer. Journal tor May, 1836, p. 192. b Experiment il Inquiry into the Physiology of Cutaneous Absorption &,c bv W H Madden, M. D p. 64, Edinb. 1838. ' ' * ' m « Principles of Physiology applied to the Preservation of Health, 5th edit, p 72. Edinb. 1836. ' d Madden, ibid. p. 46. CUTANEOUS. 85 the first of these cases, the water only could be absorbed; andreven the possibility of this has been denied by many. Under ordinary circumstances, it can happen to a trifling extent only, if at all; but, in these extraordinary cases, where the system has been long devoid of its usual supplies of moisture, and where we have reason to be- lieve that the energy of absorption is increased, such imbibition may be possible. Sanctorius,a Von Gorter,b Keill,c Mascagni,d Madden,e R. L. Young/ Dill,g and others believe, that this kind of absorption is not only frequent but easy. It has been affirmed, that after bathing the weight of the body has been manifestly augmented; and the last of these individuals has adduced many facts and arguments to support the position. Bichat was under the impression, that, in this way, he imbibed the tainted air of the dissecting-room, in which he passed a large portion of his time. To avoid an objection, that might be urged against this idea,—that the miasmata might have been absorbed by the air-passages, he so contrived his experiment, as, by means of a long tube, to breathe the fresh outer air, and he found, that the evidence, which consisted in the alvine evacuations having the smell of the miasmata of the dissecting room, still con- tinued. It is obvious, however, that such an experiment would hardly admit of satisfactory execution, and it is even doubtful, whe- ther there was any actual relation between the assigned effect and the cause. The testimony of Andral, Boyer, Dumeril, Dupuytren, Serres, Lallemand, Ribes, Lawrence, Parent-Duchatelet, and that afforded by our own observation, are by no means favourable to the unwholesomeness of cadaveric exhalations.11 J. Bradner Stuart' found, after bathing in infusions of madder, rhu- barb, and turmeric, that the urine was tinged with these substances. A garlic plaster affected the breath, when every care was taken, by breathing through a tube connected with the exterior of the apart- ment, that the odour should not be received into the lungs. Dr. Thomas Sewall> found the urine coloured, after bathing the feet in infusion of madder, and the hands in infusions of madder and rhu- barb. Dr. Musseyk proved, that if the body be immersed in a decoc- tion of madder, the substance may be detected in the urine, by using the appropriate alkaline tests. Dr. Barton found, that frogs, confined in dry glass vessels, became enfeebled, diminished in size, a De Static. Medic. Lugd. Bat. 1711. b De Perspirat Insensib. Lugd. Bat. 1736. c Tentamin. Medico-Physic, Lond. 1718. <* Vas. Lymphat Hist. Senis, 1783. e Op. cit p. 58. f De Cutis Inhalatione, Edinb. 1813. s Edinb. Medico-Chir. Transact, ii. 350. See, also, Collard de Martigny, in Archives Generates de Medecine, x. 304, and xi. 73; and Lebkuchner, translated in Archives Generates, vii. 424. h See, on this subject, Parent-Duchatelet, Hygiene Publique, Paris, 1836; and the remarks of the author in his Elements of Hygiene, p. 108, Philad. 1835; and in his American Medical Intelligencer, p. 161, Philad. 1838. ' New York Med. Repos. vol. i. and iii. 1810—11. i Med. and Physical Journ. xxxi. 80, Lond. 1814. k Philad. Medical and Physical Journal, i. 288, Philad. 1808. VOL. II. 8 86 ABSORPTION. and unable to leap; but that, on the introduction of a small quantity of water, thev soon acquired their wonted vigour, became plump, and as lively'as usual in their motions/ Dr. W. F. Edwards* of Paris, is, also, in favour of absorption being carried on by the skin to a considerable extent. To deny cutaneous absorption altogether is impossible. It is a way, in fact, by which we introduce one of our most active reme- dial agents into the system,—and it has not unfrequently happened, where due caution has not been used, that the noxious effects of different mineral and other poisons have been developed by their application to the surface, but it is by no means common or easy, when the cuticle is sound, unless the substance employed possesses unusually penetrating properties. Chaussier found, that to kill an animal, it is sufficient to make sulphuretted hydrogen gas act on the surface of the body, taking care that none gets into the air-pas- sages : the researches of Prof. J. K. Mitchell0 have also shown, that this gas is powerfully penetrant. Unless, however, the substances, in contact with the epidermis, are of such a nature as to attack its chemical composition, there is usually no extensive absorption. It is only of comparatively late years, that physiologists have ventured to deny, that the water of a bath, or the moisture from a damp atmosphere, is taken up under ordinary circumstances; and if, in such cases, the body appears to have increased in weight, it is affirmed, and with some appearance of truth, that this is owing to diminution of the cutaneous transpiration. It is, indeed, probable, that one great use of the epidermis is to prevent the inconveniences to which we should necessarily be liable, were such absorption easy. This is confirmed by the fact, that if the skin be deprived of the epidermis, and the vessels which creep on the outer surface of the true skin, be thus exposed, absorption occurs as rapidly as else- where. Miillerd affirms, that saline solutions applied to the corium penetrate the capillaries in a second of time. To insure this result in inoculation and vaccination, the matter is always placed beneath the cuticle; and, indeed, the small vessels are generally slightly wounded, so that the virus gets immediately into the venous blood. Yet, it is proper to remark, that the lizard, whose skin is scaly, after having lost weight by exposure to the air, recovers its weight and plumpness when placed in contact with water; and if the scaly skin of the lizard permits such absorption, Dr. Edwards thinks it impossible not to attribute this property to the cuticle of man. When the epidermis is removed, and the system is affected by sub- stances placed in contact with the true skin, we have the endermic method of medication. » Klapp's Inaugural Essay on Cuticular Absorption, p. 30, Philad. 1805. b Sur l'lnfluence des Agens Physiques; and Drs. Hodgkin and Fisher's translat. p. 61, and 187, &c, Lond. 1832. v c Amer. Journal of the Med. Sciences, vii. 44 ; and vol. i. p. 48 of this work d Hanod^Uch $er. Physiol°gie, torn. i. and British and Foreign Medical Review for April, 1838, p. 344. CUTANEOUS. 87 Seguina instituted a series of experiments to demonstrate the ab- sorbent or non-absorbent action of the skin. His conclusion was, that water is not absorbed, and that the epidermis is a natural ob- stacle to that action. To discover whether this was the case as regarded other fluids, he experimented on some individuals labouring under venereal affections. These persons immersed their feet and legs in a bath, composed of sixteen pints of water and three drachms of corrosive sublimate, for an hour or two, twice a day. Thirteen, subjected to the treatment for twenty-eight days, gave no signs of absorption; the fourteenth was manifestly affected, but he had itchy excoriations on the legs; and the same was the case with two others. As a general rule, absorption exhibited itself in those only whose epidermis was not in a state of integrity. At the temperature of 74° Fahrenheit, however, the sublimate was occasionally ab- sorbed, but never the water. From other experiments, it appeared evident, that the most irritating substances, and those most disposed to combine with the epidermis, were partly absorbed, whilst others were apparently not. Having weighed a drachm, (seventy-two grains, poids de marc,) of calomel, and the same quantity of camboge, scammony, salt of alembroth and tartar emetic, Seguin placed an individual on his back, washed the skin of the abdomen carefully, and applied to it these substances, at some distance from each other, covering each with a watch-glass, and maintaining the whole in situ by a linen roller. The heat of the room was kept at 65°. Seguin did not leave the patient, in order that the substances should not be displaced: and he protracted the experiment to ten hours and a quarter. The glasses were then removed, and the sub- stances carefully collected and weighed. The calomel was reduced to 71 1-3 grains. The scammony weighed 71 3-9; the camboge, 71; the salt of alembroth, 62 grains,b and the tartar emetic 67 grains.0 It requires, then, in order that matters shall be absorbed by the skin, that they shall be kept in contact with it, so as to pene- trate its pores, or the channels by which the cutaneous transpiration exudes; or else that they shall be forced through the cuticle by friction,—the iatraleptic mode. In this way, the substance comes in contact with the cutaneous veins, and enters them probably by imbibition. Certain it is, that mercury has been detected in the venous blood by Drs. Colson, Christison, Cantu, Autenrieth, Zeller, Schubarth, and others.d Not long after the period that Seguin was engaged in his experi- ments, Dr. Rousseau,6 of Philadelphia, contested the existence of absorption through the epidermis, and attempted to show, in opposi- * Fourcroy, La Medecine EclainSe, &c, torn, iii.; and Annales de Chimie, xc. 185. b Several pimples were excited on the part to which it was applied. c Magendie's Precis, &c, ii. 262. d See the author's General Therapeutics, p. 75, Philad, 1836; Meckel's Archives, lvi. 28; Horn's Arehiv. Nov. 1823, p. 417 ; and Weber's Hildebrandt's Handbuch der Anatomie, i. 100, Braunschweig, 1830. e Experimental Dissert, on Absorption, Philad. 1800, ABSORPTION. tion to the experiments we have detailed, that the pulmonary organs, and not the skin, are the passages by which certain substances enter the system. By cutting off all communication with the lungs, which he "effected by breathing through a tube communicating with the atmosphere on the outside of the chamber, he found, that although the surface of the body was bathed with the juice of garlic, or the spirit of turpentine, none of the qualities of these fluids could be detected, either in the urine, or in the serum of the blood. From subsequent experiments, performed by Dr. Rousseau, assisted by Dr. Samuel B. Smith,1 and many of which Professor Chapmanb witnessed, the following results were deduced. First, That of all the substances employed, madder and rhubarb are those only that affect the urine,—the latter of the two more readily entering the system; and secondly, that the power of absorption is limited to a very small portion of the surface of the body. The only parts, indeed, that seemed to possess it, were the spaces between the middle of the thigh and hip, and between the middle of the arm and shoulder. Topical bathing, with a decoction of rhubarb or madder, and poul- tices of these substances, applied to the back, abdomen, sides, or shoulders, produced no change in the urine; nor did immersion of the feet and hands in a bath of the same materials, for several hours, afford the slightest proof of absorption. From these and other facts, sufficiently discrepant it is true, we are justified in concluding that cuticular absorption, under ordinary circumstances, is not easy, but we can readily conceive, from the facility with which water soaks through animal tissues, that if the animal body be immersed sufficiently long in it, and especially if the vessels have been previously drained, imbibition might take place to a considerable extent. But this would be a physical absorption, and might be effected as well in the dead as the living body. b. Other Accidental Absorptions. Amongst the adventitious absorptions have been classed all those that are exerted upon substances retained in the excretory ducts, or situate in parts not natural to them. The bile, arrested in one of the biliary ducts, affords us, in jaundice, a familiar example of such absorption, and of the positive existence of the bile in the blood-vessels; although the yellow colour has been supposed, by some, to be caused by an altered condition of the red globules and not by the presence of bile in the blood-vessels. This condition of the red globules will account for some of the symp- toms,—as the yellow colour of the skin, and of the urine,__but it does not explain the clayey appearance, which the evacuations present, and which, we think, has been properly ascribed to the absence of the biliary secretion. We have, likewise, examples of ■ Philad. Medical Museum, i. 34, Philad. 1811 ; and Prof. S. Jackson art Absom tion, Amer. Cyclop. Pract Med. i. 114, Philad. 1833. ' bS°rp b Elements of Therapeutics and Materia Medica, 6th edit. i. 65 Philad. 1831 RESPIRATION. 89 this kind of absorption, where blood is effused into the cellular membrane, as in the case of a common sprain, or in those accumu- lations of fluid in various cavities, which are found to disappear by time;—the serous portion being taken up first, with some of the colouring matter, and, ultimately, the fibrine. In the case of an accumulation of the serous fluid, which naturally lubricates cavities, it is precisely of such a character—the aqueous portion at least—as to be imbibed with facility, and probably passes into the veins, in this manner;—the functions of exhalation and absorption consisting, here, mainly of transudation and imbibition. But absorption is not confined to these fluids. It must, of course, be exerted on all morbid deposits; and it is to excite the action of the absorbents, that our remedial means are directed; the agents, belonging to this class, being termed sorbefacients. This absorp- tion—in the case of solids—is of the interstitial kind; and, as the morbid formation has probably to be reduced to its elements, and undergo an action of elaboration, it ought to be referred to lym- phatic agency. To conclude the function of abs6rption. All the products—whe- ther the absorption may have been chyliferous, lymphatic or venous, —are united in the venous system, and form part of the venous blood. This fluid must, consequently, be variable in its composition, in pro- portion to the quantity of heterogeneous materials taken up by the veins, and the activity of the chyliferous and lymphatic absorptions. It is also clear, that, between the parts of the venous system into which the supra-hepatic veins,—loaded with the products of the intestinal absorption of fluids,—enter, and the opening of the tho- racic duct into the subclavian, the blood must differ materially from that which flows in other parts of the system. All, however, undergo admixture in their passage through the heart; and all are converted into arterial blood by the function, which will next engage us,—that of Respiration. CHAPTER III. RESPIRATION. The consideration of the function of absorption has shown us how the different products of nutritive absorption reach the venous blood. By simple admixture with this fluid they do not become converted into a substance, capable of supplying the losses, sus- tained by the frame from the different excretions. Nothing is better established than the fact, that no being, and no part of any being, can continue its functions unless supplied with blood, which has be- 8* 90 RESPIRATION. come arterial, by exposure to air. It is in the lungs, that the absorbed matters undergo their final conversion into that fluid;—by a function, which has been termed hcematosis, and which is the great object of that we have now to investigate—Respiration. This con- version is occasioned by the venous blood of the pulmonary vessels coming in contact with the air in the air-cells of the lungs, during which contact, the blood gives to the air some of its constituents, and, in return, the air parts with its elements to the blood. To comprehend this mysterious process, we must be acquainted with the pulmonary apparatus, as well as with the properties of at- mospheric air, and the mode in which the contact between it and the blood is effected. 1. ANATOMY OF THE RESPIRATORY ORGANS. The thorax or chest contains the lungs, which are the great agents of respiration. It is of a conical shape, the apex of the cone being Fig. 114. formed by the neck, and the base by a muscle, which has already been referred to, more than once, —the diaphragm. The osseous framework, Fig. 114, is formed, posteriorly, of twelve dorsal vertebras; ante- riorly, of the sternum, originally composed of eight or nine pieces; and laterally, of twelve ribs on each side, passing from the ver- tebrae to, or towards, the sternum. Of these, the seven uppermost extend the whole distance from the spine to the breast-bone, and are called the true or sternal ribs; sometimes, the vertebro- sternal. They become larger as they descend, and are situate more obliquely in regard to the spine. The other five, called/a/se or asternal, do not proceed as far as the sternum; but the cartilages of three of them join that of the seventh true rib, whilst the two lowest have no union with those above them, and are therefore called floating ribs. These false ribs become shorter and shorter as they descend; so that the seventh true rib may be regarded as the common base of two cones, formed by the true and false ribs re- spectively. The different bones, constituting the thorax, are so articulated as to admit of motion, and thus to allow of dilatation and contraction of the cavity. The Thorax. a. Sternum or breast-bone. b. b. The spine. c. e. c. e. The ribs. RESPIRATORY ORGANS. 91 The motion of the vertebras on each other has been described under another head. It is not materially concerned in the respira- tory movements. The articulation of the ribs with the spine and sternum demands attention. They are articulated with the spine in two places,—at the capilulum or head, and at the tubercle. In the former of these, the extremity of the ribs, encrusted with cartilage, is received into a depression, similarly encrusted, at the side of the spine. One half of this depression is in the body of the upper vertebra; the other half in the one beneath it; and, consequently, partly in the intervertebral fibro-cartilage between the two. The joint is rendered secure by various ligaments; but it can move readily up and down on the spine. In the first, eleventh, and twelfth ribs, the articulations are with single vertebrae respectively. In the second articulation, the tubercle of the rib, also encrusted with cartilage, is received into a cavity in the transverse process of each corresponding vertebra; and the joint is rendered strong by three distinct ligaments. In the eleventh and twelfth ribs, this articulation is wanting. The articulation of the ribs with the sternum is effected by an intermediate cartilage, which becomes gradually longer, from the first to the tenth rib, as seen in Fig. 114. The end of the cartilage is received into a cavity at the side of the sternum; and the junction is strengthened by an anterior and posterior ligament. This articu- lation does not admit of much motion: but the existence of a synovial membrane shows, that it is destined for some. The cavity of the thorax is completed by muscles. In the inter- vals between the ribs are two planes of muscles, whose fibres pass in inverse directions, and cross each other. These are the intercostal muscles. The diaphragm forms the septum between the thorax and abdo- men. Above, the cavity is open; and through the opening numerous vessels and nerves enter. The muscles, concerned in the respiratory function, are numerous. The most important of these is the diaphragm. It is attached, by its circumference, around the base of the chest; but its centre rises into the thorax; and, during its state of relaxation, forms an arch, the middle of which is opposite the inferior extremity of the sternum. It is tendinous in its centre, and is attached by two fasciculi, called pillars, to the spine,—to the bodies of the two first lumbar vertebras. It has three apertures; one before for the passage of the vena cava inferior; and two behind, between the pillars, for the passage of the oesophagus and aorta. The other great muscles of respiration are the serratus posticus inferior, the seiratus posticus superior, the levatores costarum, the intercostal muscles, the infra-costales and the triangularis sterni or sterno-costalis; but, in an excited condition of respiration, all the muscles, that raise and depress the ribs, directly or indirectly, par- ticipate—as the scaleni, sterno-mastoidei, pecloralis, (major and minor,) serratus major anticus, abdominal muscles, &c. 92 RESPIRATION. In the structure of the lungs, as Magendie8 has remarked, nature has re- solved a mechanical pro- blem of extreme difficul- ty. The problem was,— to establish an immense surface of contact be- tween the blood and the air, in the small space occupied by the lungs. The admirable arrange- ment adopted consists in this,—that each of the minute vessels, in which the pulmonary artery terminates, and the pul- a. The heart. 6.6. The lungs, c. c. The diaphragm. '. . . r monary veins originate, is surrounded on every side by the air. The lungs are two organs of considerable size, situate in the lateral parts of the chest, and sub- divided into lobes and lobules, the shape and number of which cannot be readily determined. They are termed right and left, respectively, according to the side of the cavity of the chest which they occupy. The former consists of three lobes; the latter of two. Each of these exactly fills the corresponding cavity of the pleura; and they are separated from each other by a duplicature of the pleura—(the serous membrane that lines the chest, and is reflected over the lungs;)—and by the heart. The colour of the lungs is generally of a marbled blue; and the exterior is furrowed by figures of a hexa- gonal shape. The appearance is not, however, the same at all ages, and under all circumstances. In infancy, they are of a pale red; in youth, of a darker colour; and in old age, of a livid blue. The elements that compose the lungs are;—the ramifications of the trachea; those of the pulmonary artery and of the pulmonary veins, besides the organic elements, that appertain to every living structure,—arteries, veins, lymphatics, nerves and cellular tissue. The ramifications of the windpipe form the cavity of the or°-an of respiration. The trachea is continuous with the larynx, from which it receives the external air conveyed to it by the mouth and nose. It passes down to the thorax, at the anterior part of the neck, and bifurcates opposite the second dorsal vertebra, forming two laro-e canals, called bronchi or bronchia. One of these goes to each lung; and, after numerous subdivisions, becomes imperceptible: hence, the multitudinous speculations that have been indulged regarding the mode in which the bronchial ramifications terminate. Mal- pighib believed that they form vesicles, at the inner surface of which Fig. 115. Thoracic Viscera. » Precis, &c. ii. 307. b Epist. de Pulmon, i. p. 133. RESPIRATORY ORGANS. 93 the pulmonary artery ramifies. Reisseisen1 describes the vesicles as of a cylindrical, and somewhat rounded figure; and he states, that they do not communicate with each other. Helvetius,b on the other hand, affirmed, that they end in cells, formed by the different constituent elements of the lungs,—the cells having no determinate shape, or regular connexion with each other; whilst Magendie0 asserts, that the minute bronchial division, which arrives at a lobe, does not enter it, but terminates suddenly as soon as it has reached the parenchyma; and, he remarks, that as the bronchus does not penetrate the spongy tissue of the lung, it is not probable that the surface of the cells, with which the air comes in contact, is lined by a prolongation of the mucous coat, which forms the inner mem- brane of the air-passages. Certain it is, that the most attentive examination has failed to detect its presence. The ramifications of the pulmonary artery are another consti- tuent element of the lung. This vessel arises from the right ven- tricle of the heart, and, at a short distance from that organ, divides into two branches; one passing to each lung. Each branch accom- panies the corresponding bronchus in all its divisions; and, at length, becomes capillary and imperceptible. Its termination, also, has given rise to conjecture. Malpighi conceived it to end at the mucous surface of the bronchi, in an extremely delicate network, which he called rete mirabile. This was also the opinion of Reis- seisen. According to others, the pulmonary artery, in its ultimate ramifications, is continuous with two kinds of vessels,—the capillary extremities of the pulmonary veins, and the exhalants engaged in the secretion of the pulmonary transpiration. Bichatd admits, at the extremities of the pulmonary artery, and between that artery and the veins of the same name, vessels of a more delicate charac- ter, which he conceives to be the agents of haematosis, and which he calls the capillary system of the lungs. All that we know is, that the air gets a ready access to the blood in the pulmonary artery; but, with regard to the precise arrangement of the means of such access, we are ignorant. The same may be said of the third con- stituent of the lungs—the pulmonary veins. Their radicles mani- festly communicate freely with those of the pulmonary artery; but they equally escape detection. When we observe them, they are found uniting, to constitute larger and larger veins, until they ulti- mately end in four large trunks, which open into the left auricle of the heart. In addition to these organic constituents, the lung, like other organs, receives arteries, veins, lymphatics, and nerves. It is not nourished by the blood of the pulmonary artery, which is not * Srtmmerinjr und Reisseisen, iiber die Structur die Verrichtung und den Gebrauch der Lungen. Zwey Preissehriften; Berlin, 1808, and F. D. Reisseisen, iiber den Bau der Lungen, u. s. w. Berlin, 1822; also, in Latin, Berl. 1822. See, likewise, Horner, Special and General Anatomy, 5th edit. ii. 136, Philad. 1839. L Memoires de I'Academ. pour 1718, p. 18. c Precis, &c. ii. 309. d Anatomie Descriptive, vol. iv. Paris, 1801. 94 RESPIRATION. adapted for that purpose, seeing that it is venous. The bronchial arteries are its nutritive vessels. They arise from the aorta, and are distributed to the bronchi. Around the bronchi, and near where they dip into the tissue of the lung, lymphatic glands exist, the colour of which is almost black, and with which the few lymphatic vessels, that arise from the superficial and deep-seated parts of the lung, communicate. The efferent vessels of these glands Haller" has traced into the tho- racic duct. The nerves, distributed to the lungs, proceed chiefly from the eighth pair or pneumogastric. A few filaments of the great sym- pathetic are also sent to them. The eighth pair—after having given off the superior laryngeal nerves, and some twigs to the heart—in- terlaces with numerous branches of the great sympathetic, and forms an extensive nervous network, called the anterior pulmonary plexus. After this, the nerve gives off the recurrents, and interlaces a second time with branches of the great sympathetic, forming another network, called the posterior pulmonary plexus. It then proceeds to the stomach, where it terminates. From these two plexuses the nerves proceed, that are distributed to the lungs. These accompany the bronchi, and are spread chiefly on the mu- cous membrane of the air tubes. The lung likewise receives some nerves directly from the three cervical ganglions of the great sym- pathetic, and from the first thoracic ganglion. In addition to these, a distinct system of nerves—the respiratory system described in the first volume of this work—is supposed by Sir Charles Bell to be distributed to the multitude of muscles, which are associated in the respiratory function, in a voluntary or involun- tary manner. This system includes one of the nerves just referred to—the eighth pair,—and the phrenic nerves, which are distributed to the diaphragm. The various nerves composing it, are intimately connected, so that, in forced or hurried respiration, in coughing, sneezing, &c. they are always associated in action.b Lastly, the lungs are constituted, also, of cellular tissue, which has been termed interlobular tissue; but it does not differ from cel- lular tissue in other parts of the body. Such are the constituent elements of the pulmonary tissue; but, with regard to the mode, in which they are combined to form the intimate texture of the lung, we are uninstructed. We find, that the lobes are divided into lobules, and these, again, seem to be sub- divided almost indefinitely, forming an extremely delicate spongy tissue, the areolae of which can only be seen by the aid of the mi- croscope. It is generally thought, that the areolae communicate with each other, and that they are enveloped by the cellular tissue which separates the lobules. Magendie0 inflated a portion of lun^, 1 Elem. Physiologias, viii. 2. b Midler's Handbuch, u.s. w. Baly's translation, p. 348, Lond. 1838 c Precis, &c, ii. 309. RESPIRATORY ORGANS. 95 and dried and cut it in slices, in order that he might examine the deep-seated cells. These appeared to him to be irregular, and to be formed by the final ramifications of the pulmonary artery, and the primary ramifications of the pulmonary veins; the cells of one lobule communicating with each other, but not with those of another lobule. Professor Horner,1 of the University of Pennsylvania, has attempted to exhibit that this communication between the cells is lateral. After filling the pulmonary arteries and the pulmonary veins with minute injection, the ramifications of the bronchi, with the air-cells, were distended to their natural size, by an injection of melted tallow. The latter, being permitted to cool, the lung was cut into slices and dried. The slices were subsequently immersed in spirit of turpentine, and digested, at a moderate heat, for several days. By this process, all the tallow was removed, and the parts, on being dried, appeared to exhibit the air-cells empty, and, seem- ingly, of their natural size and shape. Preparations, thus made, appear to show the air-cells to be generally about the twelfth of a line in diameter, and of a spherical shape, the cells of each lobule communicating freely, like the cells of fine sponge, by lateral aper- tures. The lobules, however, only communicate by branches of the bronchi, and not by contiguous cells. This would seem to nega- tive the presumption of some anatomists and physiologists,—as Blumenbach, Cuvier, &c,—that each air-cell is insulated, commu- nicating only with the minute bronchus, that opens into it; whilst it confirms the views of Haller, Monro (Secundus), Boyer, Spren- gel, Magendie, and others; but it is impossible to decide positively, where all is so minute. Many anatomists, and probably with accu- racy, by the term air-cell, mean simply the ultimate termination of a bronchus. The surface afforded by the air-cells is immense. Halesb sup- posed them to be polyhedral, and about one-hundredth part of an inch in diameter. The surface of the bronchi he estimated at 1035 square inches; and that of the air-cells at 20,000. Keillc estimated the number of cells to be 1,744,186,015; and the surface 21,906 square inches; and Lieberkuhn has valued it at the enormous amount of 1500 square feet !d All that we can derive from these mathematical conjectures is, that the extent of surface is surprising, when we consider the small size of the lungs themselves. Each lung is covered by the pleura,—a serous membrane analo- gous to the peritoneum,—and, in birds, a prolongation of the latter. This membrane is reflected from the adjacent surface of the lung to the pericardium which covers the heart, and is then spread over the interior paries of the half of the thorax to which it belongs; lining the ribs and intercostal muscles, and covering the convex or upper surface of the diaphragm. There are, consequently, two pleurae, a American Journal of the Medical Sciences, for Feb. 1832, p. 538, and Special and General Anatomy, ii. 145, Philad. 1839. b Statical Essays, vi. p. 241. c Tentam, Med. Phys. p. 80. d Blumenbach, in Elliotson's Physiology, p. 197, Lond. 1835. 96 RESPIRATION. Fig. 116. Reflections of the Pleura. Fig. 117. each of which is confined to its own half of the thorax, lining its cavity, and covering the lung. Behind the sternum, however, they are contiguous to each other, and form the partition, called mediasli- num, which extends between the sternum and spine. In Fig. 116, the dotted lines exhibit the boundaries of the two cavities of the pleura, and the middle space be- tween is the mediastinum. Within this septum, the heart, enveloped by the pe- ricardium, is situate, and separates the pleurae considerably from each other. Anatomists generally subdivide the me- diastinum into two regions; one pass- ing from the front of the pericardium to the sternum, called the anterior medias- tinum; the other, from the posterior surface of the pericardium to the dorsal vertebrae,—the posterior mediastinum; and, by some, the part, which is within the circuit of the first ribs, is termed superior mediastinum. The second of these contains the most important organs,—the lower end of the trachea, oesophagus, aorta, vena azygos, thoracic duct, and pneumogas- tric nerves. The portion of the pleura, covering each lung, is called the pleura pulmonalis; that, which lines the thorax, pleura costalis. The mode, in which the two are connected to form one whole, is shown by the dotted line in Fig. 117, representing a section of the chest. It is obvious, that, as in the case of the abdomen, the viscera are not in the cavity of the pleura, but ex- ternal to it; and that there is no com- munication between the serous sac of one side and that of the other. The use of the pleura is to attach the lungs, by their roots, to their respective cavities, and to facilitate their movements. To aid this effect, the membrane is always lubricated by a fluid, exhaled from its surface. The other surface is attached to the lung in such a manner, that air cannot get between it and the parietes of the thorax. Dr. Stokes,1 of Dublin, has described a proper fibrous tunic of the lungs. In a healthy state, this capsule, although possessing great strength, is transparent, a circumstance in which it differs from the fibrous capsules of the pericardium, and which, Dr. Stokes Reflections oftke Pleura. » On Diseases of the Chest, Part i. p. 460, Dublin, 1837; or Dunglison's Ameri- can Medical Library edition, p. 301, Philad. 1837. "ungnson s Amen ATMOSPHERIC AIR. 97 thinks, has probably led to its having been overlooked. It invests the whole of both lungs; covers a portion of the great vessels; and the pericardium seems to be but its continuation,—endowed, in that particular situation, with a greater degree of strength, for purposes that are obvious. It covers the diaphragm where it is more opaque; in connexion with the pleura, it lines the ribs; and, turning, forms the mediastina, which are thus shown to consist of four layers,— two serous and two fibrous. It seems, that Dr. Hart, of Dublin, has, for years, demonstrated this tunic to his class. It was, at one time, the prevalent belief, that air always exists in the cavity of the chest. Galen supported the opinion by the fact, that, having applied a bladder, filled with air, to a wound, which had penetrated the chest, the air was drawn out of the bladder at the time of inspiration. This was also maintained by Hamberger, Hales,1 and numerous others. The case, alluded to by Galen, is insufficient to establish the position, inasmuch as we have no evi- dence, that the wound did not also implicate the pulmonary tissue. Since the time of Haller, who opposed the prevalent doctrine by observation and reasoning, the fact of the absence of air in the cavity of the pleura is generally considered to be entirely established. It is obvious, that its presence there would materially interfere with the dilatation of the lungs, and thus be productive of much inconve- nience; besides, anatomy instructs us, that the lungs lie in pretty close contact with the pleura costalis. When the intercostal mus- cles are dissected off, and the pleura costalis is exposed, the surface of the lungs is seen in contact with that transparent membrane; and, when the pleura is punctured, the air rushes in, and the lungs retire, in proportion as the air is admitted. This occurs in cases of injuries inflicted upon the chest of the living animal. Moreover, if a dead or living body be placed under water, and the pleura be punctured, so as not to implicate the lungs, it has been found by the experiments of Brunn, Sprogel, Caldani, Sir John Floyer, Haller,b and others, that not a bubble of air escapes,—which would neces- sarily be the case, if air were contained in the cavity of the pleura.0 2. ATMOSPHERIC AIR. The globe is surrounded every where, to the height of fifteen or sixteen leagues, by a rare and transparent fluid, called air; the total mass of which constitutes the atmosphere. Atmospheric air, although invisible, can be proved to possess the ordinary properties of matter; and, amongst these, weight. It also partakes of the character of a fluid, adapting itself to the form of the vessel in which it is contained, and pressing equally in all directions. ■ Statical Essays, ii. 81. b Element. Physiol, viii. 2. c Bostock's Physiology, 3d edit. p. 305, Lond. 1836; and Adelon, Physiologie de I'Homme, edit. cit. iii. 144. VOL. II. 9 98 RESPIRATION. As air is possessed of weight, it results, that every body on the earth's surface must be subjected to its pressure; and as it is elastic or capable of yielding to pressure, the part of the atmosphere near the earth's surface must be denser than that above it. As a body, therefore, ascends, the pressure will be diminished; and this ac- counts for the different feelings experienced by those who ascend lofty mountains, or voyage in balloons, into the higher strata of the atmosphere.1 Dr. Edwardsb ascribes part, at least, of the effect produced upon the breathing, at great elevations, to the increased evaporation which takes place from the skin and lungs; and in many aerial voyages great inconvenience has certainly been sustained from this cause. The pressure of the atmosphere at the level of the sea is the result of the whole weight of the atmosphere, and is capable of sustaining a column of water thirty-four feet high, or one of mer- cury of the height of thirty inches,—as in the common barometer. This is equal to about fifteen pounds avoirdupois on every square inch of surface: so that the body of a man of ordinary stature, the surface of which Haller estimates to be fifteen square feet, sustains a pressure of 32,400 pounds. Yet, as the elasticity of the air within the body exactly balances or counteracts the pressure from without, he is not sensible of it. The experiments of Davy, Dalton, Gay Lussac, Humboldt, Des- pretz, and others, have shown, that pure atmospheric air is com- posed essentially of two gases, oxygen and azote, which exist in it in the proportion of 21 of the former to 79 of the latter : Dr. Thomson, whose analysis is the most recent and satisfactory, says 20 of oxygen to 80 of azote or nitrogen; and these proportions have been found to prevail in the air whencesoever taken;—whether from the summit of Mont Blanc, the top of Chimborazo, the sandy plains of Egypt, or from an altitude of 23,000 feet in the air.c Chemical analysis has not been able to detect the presence of any emanation from the soil of the most insalubrious regions, or from the bodies of those labouring under the most contagious diseases,— malignant and material as such emanations unquestionably must be. The uniformity in the proportion of the oxygen to the nitrogen in the atmosphere has led to the conclusion, that as there are many processes, which consume the oxygen, there must be some natural agency, by which a quantity of oxygen is produced equal to that consumed. The only source, however, by which oxygen is known to be supplied, is the process of vegetation. A healthy plant ab- a See the author's Elements of Hygiene, p. 39, Philad. 1835; art. Atmosphere, by the author, in Amer. Cyclop, of Pract Med. iii. 529, Philad. 1836; and Bostock' op cit. p. 414. ' b De l'lnfluence des Agens Physiques, &c. p. 493, Paris, 1824. c Turner's Chemistry, 5th edit by Dr. F.« Bache, Philadelphia, 1835, p. 171; and art. Atmosphere, (Physical and Chemical History,) by Dr. R. M. Patterson in Amer. Cyclopedia of Practical Medicine and Surgery, vol. ii. p. 526, Philad. 1836.' ATMOSPHERIC AIR. gg sorbs carbonic acid during the day; appropriates the carbon to its own necessities, and gives off the oxygen with which it was com- bined. . During the night, an opposite effect is produced. The oxy- gen is then taken from the air, and carbonic acid given off; but the experiments of Davy and Priestley show, that plants, during the twenty-four hours, yield more oxygen than they consume. It is im- possible to look to this as the great cause of equilibrium between the oxygen and azote. Its influence can extend to a small distance only; and yet the uniformity has been found to prevail, as we have seen, in the most elevated regions, and in countries whose arid sands never admit of vegetation. In addition to the oxygen and azote,—the principal constituents of atmospheric air,—another gas exists in very small proportion, but is always present. This is carbonic acid. It was found byDe Saus- sure on Mont Blanc, and by Humboldt in air brought down, by Garnerin, the aeronaut, from the height of several thousand feet. The proportion is estimated by Dalton not to exceed the toW1 orT41oo,h of its bulk. These, then, may be looked upon as the constituents of atmo- spheric air. There are certain substances, however, which are ad- ventitiously present in variable proportions; and which, with the constitution of the atmosphere .as to density and temperature, are the causes of general or local salubrity, or the contrary. Water is one of these. The quantity, according to De Saussure, in a cubic foot of air, charged with moisture, at 65° Fahr., is 11 grains. Its amount in the atmosphere is very variable, owing to the continual change of temperature to which the air is subject; and even when the temperature.is the same, the quantity of vapour is found to vary, as the air is very rarely in a state of saturation. The varying con- dition as to moisture is indicated by the hygrometer. From a com- parison of numerous observations, Gay Lussac affirms, that the mean hygrometric state of the atmosphere is such, that the air holds just one-half the moisture necessary for its saturation. In his celebrated earial voyage, he found the air to contain but one-eighth of the moisture necessary for saturation. This is the greatest degree of dryness ever noticed. It has beenpresumeed, that the hygrometric condition of the atmo- spheric air has more agency in the production of disease than either the barometric or thermometric. It is not easy to say which exerts the greatest influence: probably all are concerned, and when we have a union of particular barometric, thermometric, hygrometric, electric, and other conditions, we have certain epidemics existing, which do not prevail under any other combination. When the air is dry, we feel a degree of elasticity and buoyancy; whilst, if it be saturated with moisture,—especially during the heat of summer,— languor and lassitude, and indisposition to mental or corporeal ex- ertion are excited. In addition to aqueous vapour, numerous emanations from animal and vegetable substances must be generally present, especially in the lower strata of the atmosphere; by which the salubrity of the 100 RESPIRATION. air may be more or less affected. All living bodies, when crowded together, deteriorate the air so much as to render it unfit for the maintenance of the healthy function. If animals be kept crowded together in ill-ventilated apartments, they speedily sicken. The horse becomes attacked with glanders; fowls with pep, and sheep with a disease peculiar to them if they be too closely folded. This is probably a principal cause of the insalubrity of cities compared with the country. In them, the air must necessarily be deteriorated by the impracticability of due ventilation, and this, with the want of due exercise, is a fruitful cause of cachexia—and of tuberculous cachexia; hence, also, it is, that in work-houses and manufactories, diseases dependent on this condition of constitution are prevalent." One of the greatest evidences we possess of the positive insalu- brity of towns is the case of the young. In London, the proportion of those that die annually under five years of age, to the whole number of deaths, is as much as thirty-eight per cent., and under two years, twenty-eight per cent.; in Paris, under two years of age, twenty- five per cent.; and in Philadelphia and Baltimore, rather less than a third. These estimates may be considered approximations; the pro- portions varying somewhat, according to the precise year in which they have been taken. Manifest, however, as is the existence of some deleterious principle, in these cases, it has always escaped the researches of the chemist. Lastly. Air is indispensable to organic existence. No being,— animal or vegetable,—can continue to live without a due supply of it; nor can any other gas be substituted for it. This is proved by the fact, that all organized bodies cease to exist, if placed in vacuo. They require, likewise, renovation of the air, otherwise they die; and if the residual air be examined, it is found to be dimi- nished in quantity, and to have received a gas, which is totally unfit for life,—carbonic acid. The experiments of Hales prove this as regards vegetables; whilst Spallanzani and Vauquelin have con- firmed it in the case of the lower animals. The necessity for the presence of air, and its due renewal,—as regards man and the upper classes of animals,—is sufficiently obvious. Not less necessary is a due supply of air to aquatic animals. They can be readily drowned, when the air in the water is consumed, if prevented from coming to the surface: if the fluid be put under the receiver of an air-pump, and the air be withdrawn, or if the vessel be placed so that the air cannot be renewed, the same changes are found to have been pro- duced in the air; and hence the necessity of making holes ihrouo-h the ice, where small fish-ponds are frozen over, if we are desirous of preserving the fish alive. The necessity for the renewal of air is not, however, alike imperative in all animals. Whilst the mam- a Dr. A. Combe's Principles of Physiology, 5th edit. p. 93, Edinb. 1836* Sir James Clark's Treatise on Pulmonary Consumption, Amer. Edit. Philad. 1^35 • art Lon- gevity, Amer. Quarterly Review, viii. 380, Philad. 1830; art. Atmosphere' in Amer. Cyclop, of Practical Medicine, ii. 541, and Elements of Hygiene, p. 138 Lond. 1835 —the three last by the author; also Traill's Outlines of Medical Jurisprudence 1st American edition, with Notes by the author of this work, Philad. 1841. MECHANICAL PHENOMENA OF RESPIRATION. 101 malia, birds, fishes, &c. speedily expire, when placed under the receiver of an air-pump, if the receiver be exhausted; the frog is but slightly incommoded. It swells up almost to bursting, but retains its position, and when the air is admitted, seems to have sustained no injury. This exception, afforded by the amphibious animal to the ordinary effects,of destructive agents, we have already had occa- sion to refer to more than once; and it is strikingly exemplified in the fact, now indisputable, that the toad has been found alive in the substance of trees and rocks, where no access of air appeared practicable. The influence of air on mankind is most interesting and important in its hygienic relations, and has accordingly been a topic of study since the days of Hippocrates. In other works, it has been investi- gated, at considerable length, by the author.1 3. PHYSIOLOGY OF RESPIRATION. a. Mechanical Phenomena of Respiration. Within certain limits, the function of respiration is under the influ- ence of volition. The muscles, belonging to it, have consequently been termed mixed, as we can at pleasure increase or diminish their action, but cannot arrest it altogether, or for any great length of time. If, by a forced inspiration, we take air into the chest in large quantity, we find it impossible to keep the chest in this condition beyond a certain period. Expiration irresistibly succeeds, and the chest resumes its pristine situation. The same occurs if we expel the air as much as possible from the lungs. The expiratory effort cannot be prolonged indefinitely, and the chest expands in spite of the effort of the will. The most expert divers do not appear capa- ble of suspending the respiratory movements longer than 95 or 100 seconds. Dr. Lefevreb found the average period of the Turkish divers, 76 seconds for each man. These facts have given rise to two curious and deeply interesting topics of inquiry;—the cause of the first inspiration in the new-born infant? and of the regular alternation of inspiration and expiration during the remainder of existence? The first of these questions will fall under consideration when we investigate the physiology of in- fancy; the latter will claim some attention at present. Haller0 attempted to account for the phenomenon by the passage of the blood through the lungs being impeded during expiration,—a reflux of blood into the veins, and a degree of pressure upon the brain being thus induced. Hence, a painful sense of suffocation arises, in consequence of which the muscles of inspiration are called into action by the will, for the purpose of enlarging the chest, and. a Elements of Hygiene, pp. 33 to 305, Philad. 1835; and American Cyclopedia of Practical Medicine and Surgery, art Atmosphere, p. 527, Philad. 1836. b Loudon's Magazine of Nat. Hist. p. 617, Dec. 1836; and Dunglison's Amer. Med. Intelligencer, p. 30, April 15, 1837. c Elementa Physiologia;, viii. 4, 17. 9* 102 RESPIRATION. Fig. 118. in this way, removing the impediment. The same uneasy feelings, however, ensue from inspiration, if too long protracted: the mus- cles cease to act, and, by their relaxation, the opposite state of the chest is induced. Whytt1 conceived that the passage of the blood through the pulmonary vessels is impeded by expiration, and that a sense of anxiety is thus produced. This unpleasant sensation acts as a stimulus upon the nerves of the lungs and the parts connected with them, which arouses the energy of the sentient principle; and this, by acting in a reflex manner, causes contraction of the dia- phragm, enlarges the chest, and removes the painful feeling. The muscles then cease to act, in consequence of the stimulus no longer existing.'' These, and all other methods of accounting for the phenomena, are, however, too pathological. From the first moment of respira- tion the process appears to be accomplished without the slightest difficulty, and to be as much a part of the instinctive extra-uterine actions of the frame, as circulation, digestion, or absorption. It is obviously an internal sensation, after respiration has been once established; and, like all internal sensations, is inexplicable in our existing state of knowledge. The part which developes the impres- sion is probably the lung, through its ganglionic nerves; the pneumogastric nerves convey the impression to the brain or spinal marrow, which calls into action the muscles of inspiration. We say, that the action of impression arises in the lungs, and this, from some internal cause, connected with the office to be filled in the economy: but in so saying we sufficiently ex- hibit our total want of acquaintance with its nature. The movements of inspiration and expiration, which, together, constitute the function of respiration, are entire- ly accomplished by the dilatation and contraction of the thorax. The air enters the chest when the latter is ex- panded; and it is driven out when the chest is restored to its ordinary dimen- sions;—the thorax thus seeming to act like an ordinary pair of bellows with the valve stopped: when the sides are separated, the air enters at the nozzle, and it is forced outrwhen they are brought together. Section of the Thorax and Abdomen. a. The thorax, b. The abdomen. c. The relaxed diaphragm. 1751 An Essay on the Vital and ether Involuntary Motions of Animals, sect. viii. Edinb. "See, also Dr. M. Hall's Lectures on the Nervous System, p. 55, London, 1836; or Amer. Edit. p. 36, Philad. 1836. MECHANICAL PHENOMENA—INSPIRATION. J93 1. INSPIRATION. The augmentation of the capacity of the thorax, which consti- tutes inspiration, may be effected to a greater or less extent, accord- ing to the number of muscles which are thrown into action. The chest may, for example, be dilated by the diaphragm alone. This muscle, as we have seen, in its ordinary relaxed condition is convex towards the chest, as in Figures 118 and 119. When, however, it contracts, it becomes more horizontal; and assumes the position indicated by the dotted line d, Fig. 118, in this manner augmenting the cavity of the chest in a vertical direction. The sides or lateral portions of the diaphragm, which are fleshy and correspond to the lungs, descend more, in this movement, than the central tendinous portion, which is moreover kept immovable by its attachment to the sternum, and its union with the pericardium. In the gentlest of all breathing, the diaphragm appears to be the sole agent of inspiration; and in cases of inflammation of the pleura costalis, or of fractured rib, our endeavours are directed to the prevention of any elevation of the ribs by which the diseased part can be put upon the stretch. Generally, however, as the diaphragm descends, the viscera of the abdomen are compressed; the abdominal muscles assume the posi- tion of the double dotted line/, and the ribs and the breast bone are raised so that the latter is protruded as far as the dotted line e. When the diaphragm acts, and, in addition, the ribs and sternum are raised, the cavity of the chest is still farther augmented. The mechanism, by which the ribs are raised, has been produc- tive of more controversy than the subject merits. Haller1 asserted, that the first rib is immovable, or at least admits of but trifling motion when compared with the others; and he denies that the thorax makes any movement, as a whole, of either elevation or depression; affirming that the ribs are raised successively towards the top of the cavity; and this to a greater extent as they are more distant from the first. Magendie,b on the other hand, denies that they are elevated in this manner; and endeavours to show that they are all raised at the same time; that the first rib, instead of being the least movable, is the most so; and that the disadvantage, which the lower ribs possess in the movement, by their admitting of less motion in their posterior articulations, is compensated by the greater length of these ribs. This compensation he considers to have its advantages; for as the true ribs, with their cartilages and the sternum, usually move together, and the motion of one of these parts almost always induces that of the rest, it would follow, that if the lower ribs were more movable, they could not execute a more extensive movement than they do; whilst the solidity of the thorax would be diminished. By the elevation, then, of the ribs, and the depression of the diaphragm, the chest is augmented, and a deeper inspiration effected than when the diaphragm acts singly. In this elevation of the ribs, we see the advantage of their obliquity as " Elementa Physiologiae, viii. b Precis, &c. 2de edit. ii. 316. 104 RESPIRATION. regards the spine. Had they been horizontal, or inclined obliquely upwards, any elevation would necessarily have contracted the tho- racic cavity, and favoured expiration instead of inspiration. The muscles chiefly concerned in inspiration are the intercostals, and those muscles which arise, either directly or indirectly, from the spine, head, or upper extremities, and" which can, in any manner, elevate the thorax. Amongst these, are the scaleni antici and postici, the levatores costarum, the muscles of the neck, which are attached to the sternum, &c. As no air exists in the cavity of the pleura, it necessarily happens, that, when the capacity of the chest is augmented, the residuary air, contained in the air cells of the lungs after expiration, is rarefied; and, in consequence, the denser air without enters the larynx by the mouth and nose, until the air within the lungs has attained the density, which the residuary air had, prior to inspiration,—not that of the external air, as has been affirmed.1 At the time of inspira- tion, the glottis opens by the relaxation of the arytenoidei muscles, as Legalloisb proved by experiments, performed at the JEcole de Aledecine of Paris. On exposing the glottis of a living animal, the aperture is found to dilate very distinctly at each inspiration, and to contract at each expiration. If the eighth pair of nerves be divided low down in the neck, and the dilator muscles of the glottis, which receive their nerves from the recurrents—branches of the eighth pair—be thus paralysed, the aperture is no longer enlarged during inspiration, whilst the constrictors—the arytenoidei muscles—which receive their nerves from the superior laryngeal,—given off above the point of section—preserve their action, and close the glottis more or less completely. When the air is inspired through the mouth, the velum is raised, so as to allow the air to pass freely to the glottis; and, in forced inspiration, it is so horizontal, as to completelyexpose the pharnyx to view. The physician takes advantage of this, in examining morbid affections of those parts, and can often succeed much better in this way than by pressing down the tongue. On the other hand, when inspiration is effected entirely through the nose, the velum palati is depressed, until it becomes vertical, and no obstacles exist to the free entrance of the air into the larynx. In such case, where diffi- culty of breathing exists, the small muscles of the alas nasi are frequently thrown into violent action, alternately dilating and con- tracting the apertures of the nostrils; and hence this is a common symptom in pulmonary affections. • Mayowc conceived, that the air enters the lungs in inspiration as it would a bladder put into a pair of bellows, and communicating with the external air by the pipe of the instrument. The luno-s however, are not probably so passive as this view would indicate! In cases of hernia of the lungs, the extruded portion has been » Animal Physiology, Library of Useful Knowledge, p. 100 Lond 182Q b CEuvres, p. 177, Paris, 1824. c Tractates Quinqu^. 271 Son. 1674. MECHANICAL PHENOMENA.—INSPIRATION. JQ5 observed to dilate and contract in inspiration and expiration. Reis- seisen believed this to be owing to muscular fibres, which Meckel and himself conceived to perform the whole circuit of the bronchial ramifications. These are not, however, generally admitted by anatomists, and the phenomenon is usually ascribed to the bronchi having in their composition the highly elastic tissue, which is an important constituent of the arteries. Laennec1 affirms, that he has endeavoured, without success, to verify the observations of Reisseisen; but that the manifest existence of circular fibres on branches of a moderate size, and the phenomena, presented by many kinds of asthma, induce him to consider the temporary con- striction and occlusion of the minute bronchial ramifications as a thing well established.b In the trachea, an obvious muscular struc- ture exists in its posterior third, where the cartilages are wanting. There it consists of a thin muscular plane, the fibres of which pass transversely between the interrupted extremities of the cartilaginous rings of the trachea and bronchi. The use of this muscular tissue, as suggested by Dr. Physick,c and, since him, by Cruveilhier and Sir Charles Bell,d is to diminish the calibre of the air tubes in expec- toration ; so that the air having to pass through the contracted portion with greater velocity, its momentum may remove the secre- tions that are adherent to the mucous membrane. The explanation is ingenious and probably just. Magendie6 asserts, that the lung has a constant tendency to return upon itself, and to occupy a smaller space than that which it fills; and, that it consequently exerts a degree of traction on every part of the parietes of the thorax. This traction has but little effect upon the ribs, which cannot yield : but upon the diaphragm it is consider- able. It is, indeed, in his opinion, the cause, why that muscle is always tense, and drawn so as to be vaulted upwards; and when the muscle is depressed during contraction, it is compelled to draw down the lungs towards the base of the chest, so that they are stretched, and, by virtue of their elasticity, have a more powerful tendency to return upon themselves, and to draw the diaphragm upwards. If a puncture be made into the chest in one of the inter- costal spaces the air will enter the chest through the aperture, and the lung will shrink. By this experiment, the atmospheric pressure is equalized on both surfaces of the lung, and the organ assumes a bulk determined by its elasticity and weight. Owing to this resi- liency of the lungs, and to their consequent tendency to recede from the pleura costalis/ there is less pressure upon all the parts against 1 On the Diseases of the Chest, &c., 4th edit., Lond. 1834: reprinted in this country, Philad. 1835. b See, on this subject, Trousseau and Belloc on Laryngeal Phthisis, translated by Dr. W;irder, of Cincinnati, for Dunglison's Amer. Med. Library, p. 81, Philad. 1839. c Horner's Lessons in Pract. Anat, p. 179, Philad. 1836; and Special and General Anat 4th edit, Philad. 1839. J Philos. Transact, for 1832, p. 301. e Precis,&c. ii. 325. 1 J. Carson, on the Elasticity of the Lungs, in Philos. Transactions for 1820; and Inquiry into the Causes of Respiration, &c. 2d edit., Lond. 1833. 106 RESPIRATION. which the lungs are applied; and, accordingly, the heart is not exposed to the same degree of pressure as the parts external to the chest; and the degree of pressure is still farther reduced,when the chest is fully dilated, the lungs farther expanded, and their elastic resiliency increased. Many'physiologists have pointed out three degrees of inspiration, but it is manifest that there may be innumerable shades between them:—1. Ordinary gentle inspiration, which is owing simply to the action of the diaphragm; or, in addition, to a slight elevation of the chest. 2. Deep inspiration, where, with the depression or contrac- tion of the diaphragm, there is evident elevation of the thorax; and, lastly, forced inspiration, when the air is strongly drawn in, by the rapid dilatation, produced byt he action of all the respiratory mus- cles that elevate the chest directly or indirectly. Many trials have been instituted for determining the quantity of air taken into the lungs at an inspiration; and considerable diversity, as might be expected, exists in the evaluations of different experi- menters." We have just remarked, that, in the same individual, the inspiration may be gentle, deep, or forced; and, in each case, the quantity of air inspired will necessarily differ. There is, likewise, considerable diversity in individuals, as regards the size of the chest; so that an approximation can alone be attained. The fol- lowing table sufficiently exhibits the discordance of authors on this point. Many, however, of the estimates, which seem so extremely discrepant, may probably be referred to imperfection in the mode of conducting the experiment, as well as to the causes above men- tioned: Cubic inches at each Inspiration. Cubic inches at each Inspiration. Reil ......... 42 to 100 40 35 to 38 Dalton, ..... Herholdt,....... Allen and Pepys, - - . Sir H. Davy,..... Abernethy and Mojon, 35 30 to 40 30 20 29 20 16A 15~to 40 14 13 to 17 12 6 to 12b Menzies, \ Sauvages, ) Hales, / Haller, f Ellis, > - - . . Sprengel, [ Snmmering, V Thomson, A Bostock, J In passing through the mouth, nasal fossae, pharynx, larynx, tra- chea, and bronchi, the inspired air acquires pretty nearly the tem- perature of the body; and, if the air has been cool, the same quantity a Dr. Marshall Hall has devised a pneumatometer for this purpose. See art Irrita- bility, in Cyclop, of Anat. and Physiol. July, 1840. b Bostock's Essay on Respiration, Liverpool, 1804; and Elementary System of Phv siology, 3d edit. p. 314, Lond. 1836; also, Rudolphi, Grundriss der Phvsioloe-ie u s w Berlin, 1821; and C. T. Coathupe, in Philos. Magaz. June, 1839. ^ glG' Ul S' " MECHANICAL PHENOMENA.—EXPIRATION. 107 by weight occupies a much larger space in the lungs, owing to its rarefaction in those organs. In its passage, too, it becomes mixed with the halitus, which is constantly exhaled from the mucous mem- brane of the air-passages; and, in this condition, it enters the air- cells, and becomes mixed, by diffusion, with the residuary air in the lungs after expiration. It is obvious, that if we knew the exact capacity of the lungs in an individual when in health, we might be able to determine the extent of solidification in pulmonary affections by the diminution in their capacity. Owing, however, to our want of this requisite pre- liminary knowledge, the test is not of much avail. 2. EXPIRATION. An interval, scarcely appreciable, elapses after the accomplish- ment of inspiration, before the reverse movement of expiration suc- ceeds; and the air is expelled from the chest. The great cause of this expulsion is the restoration of the chest to its former dimensions; and the elasticity of the yellow tissue composing the bronchial rami- fications, which have been put upon the stretch by the air rushing into them during inspiration. The restoration of the chest to its dimensions may be effected simply by the cessation of the contraction of the muscles, that have raised it, and the elasticity of the cartilages, which connect the bony portions of the ribs with the sternum or breast-bone. In active expi- ration, however, the ribs are depressed by the action of appropriate muscles, and the chest is thus still farther contracted. The chief expiratory muscles are the triangularis sterni, the broad muscles of the abdomen, rectus abdominis, sacro-lumbalis, longissimus dorsi, serratus posticus inferior, &c. Haller1 conceived that the ribs, in expiration, are successively depressed towards the last rib; which is first fixed by the abdominal muscles and quadratus lumborum. The intercostal muscles then act and draw the ribs successively downwards. Magendieb contests the explanation of Haller; and the truth would seem to be, that the muscles, just mentioned, parti- cipate with the intercostals in every expiratory movement. By this action, the capacity of the chest is diminished; the lungs are cor- respondency pressed upon, and the air issues by the glottis. It has been already remarked, that, during expiration, the arytenoidei muscles contract, and the glottis appears to close. Still, space suffi- cient is left to permit the exit of the air. It has been asked—is the air expired precisely that which has been taken in by the previous inspiration? It is impossible to empty the lungs wholly by the most forced expiration. A portion still remains; and hence it has been assumed, that the use of inspiration is to constantly renew the air remaining in the air-cells. On this * Element Physiol, viii. 4. b Precis, &c. ii. 324. 108 RESPIRATION. subject we are not well informed; but it is probable that the lighter and more rarefied air mixes, by diffusion, with the newly-arrived and denser medium. Many experiments have been made to determine the change of bulk which air experionces by being respired. Ac- cording to Sir Humphry Davy,1 it is diminished, by a single inspira- tion, from 7yh to T±?th*part of its bulk. Cuvier makes it about J^th; Allen and Pepys a little more than a half per cent. Berthollet from 0.69 to 3.70 per cent.; and Bostock ^th,—as the average diminution.* Assuming this last estimate to be correct, and forty cubic inches to be the quantity of air drawn into the lungs at each inspiration, it will follow, that half a cubic inch disappears each time we respire. This, in a day, would amount to 14,400 cubic inches, or to rather more than eight cubic feet. The experiments of MM. Dulong and Despretz make the diminution considerable. The latter gentleman placed six small rabbits in forty-nine quarts of air for two hours, at the expiration of which time the air had diminished one quart. A portion of the inspired air must consequently have been absorbed. Attempts have been made to estimate the quantity of air remain- ing in the lungs after respiration; but the sources of discrepancy are here as numerous as in the cases of inspiration or expiration. Goodwyn6 estimated it at 109 cubic inches; Menzies*1 at 179 ; Jurin6 at 220; Fontanaf at 40; and Cuvier, after a forced inspiration, at from 100 to 60. Davyg concluded, that his lungs, after a forced expiration, still retained 41 cubic inches of air; after a natural expiration they contained 118 cubic inches; after a natural inspira- tion, 135; after a forced inspiration, 254 ; by a full forced expira- tion after a forced inspiration, he threw out 190 cubic inches; after a natural inspiration, 78.5 ; after a natural expiration, 67.5. It is impossible, from such variable data, to deduce any thing like a satisfactory conclusion ; but if we assume with Bostock,h (and Dr. Thomson' is disposed to adopt the estimate,) 170 cubic inches as the quantity, that may be forcibly expelled, and that 120 cubic inches will be still left in the lungs, we shall have 290 cubic inches as the measure of the lungs in their natural or quiescent state ; to this quantity, 40 cubic inches are added by each ordinary inspiration, giving 330 cubic inches as the measure of the lungs in their distended state. Hence it would seem, that about one-eighth of the whole contents of the lungs is changed by each respiration; and that rather more than two-tbirds can be expelled by a forcible expiration. Supposing, that each act of respiration occupies three seconds, or that we respire twenty times in a minute, a quantity of * Researches, Chemical and Philosophical, p. 431, Lond. 1800. »> Physiology, 3d edit. Lond. 1836. t Op. citat p. 36. ^ Op. citat p. 31. e Philosoph. Trans, vol. xxx. p. 758. r Philosoph. Trans, for 1799, p. 355. « Op. citat. p. 411. h Elementary System of Physiology, vol. ii. 25, 34, Lond. 1826; reprinted in this country, Boston, 1825 and 1828. ' System of Chemistry, vol. iv. MECHANICAL PHENOMENA—EXPIRATION. 109 air, rather more than 2f times the whole contents of the lungs, will be expelled in a minute, or about four thousand times their bulk in twenty-four hours. The quantity of air, respired during this period, will be 1,152,000 cubic inches, about 666^ cubic feet. Such is Bos- tock's estimate. It is the residuary air, that gives to the lungs the property of floating on the surface of water, after they have once received the breath of life, and no pressure, that can be employed, will force out the air, so as to make them sink. Hence, the chief proofs, whether a child has been born alive or dead, are deduced from the lungs. These proofs constitute the docimasia pulmonum, Lungenprobe, or A t h e m p r o b e,a (" Lung-proof or Respi- ration-proof,") of the Germans.b Expiration, like inspiration, has been divided into three grades: ordinary, free, and forced; but it must necessarily admit of multi- tudinous shades of difference. In ordinary passive respiration, expi- ration is effected solely by the relaxation of the diaphragm. In free active respiration, the muscles that raise the ribs are likewise relaxed, and there is a slight action of the direct expiratory mus- cles. In forced expiration, all the respiratory muscles are thrown into action. In this manner, the air makes its way along the air- passages through the mouth or nostrils or both ; carrying with it a fresh portion of the halitus from the mucous membrane. This it deposits, when the atmosphere is colder than the temperature ac- quired by the respired air, and if the atmosphere be sufficiently cold, as in winter, the vapour becomes condensed as it passes out, and renders expiration visible. The number of expirations in a given time differs considerably in different individuals. Dr. Hales reckons them at twenty. A man, 'on whom Menzies made experiments, breathed only fourteen times in a minute. Sir Humphry Davy made between twenty-six and twenty-seven in a minute. Dr. Thomson about nineteen, and Ma- gendie fifteen. Our own average, is sixteen. The average, deduced from the few observers, that have recorded their statement,—or twenty per minute,—has generally been taken ; but we are satisfied it is above the truth; eighteen would be nearer the general average; and it has accordingly been admitted by many. Eighteen in a minute give twenty-five thousand nine hundred and twenty in the twenty-four hours. The number is influenced, however, by various circumstances. The child and the female, and perhaps also the aged, breathe more rapidly than the adult male. MM. Hourmann and Dechambrec examined two hundred and fifty-five women, be- tween the ages of sixty and ninety-six, the average number of whose 1 Wagner, in art. Athemprobe, in Encycl. Worterb der Medicinisch. Wissenschaft. B. iii. S. 616, Berlin, 1829. b See, Beck's Medical Jurisprudence, 6th edit. Albany, 1838; Mr. Alfred S. Taylor, in Guy's Hospital Reports, for Oct. 1837, p. 318; and Medical Monographs, Dunglison's Medical Library, p. 553, Philad. 1838. c Arehiv. Gener. de Medecine, Nov. 1835; and British and Foreign Med. Rev. April, 1836, p. 555. vol. n. 10 110 RESPIRATION. respirations was 21.79 per minute. We find as much variety, too, in man as we do in the horse; whilst some men are short, others are long-winded; and this last condition may be improved by appropriate training; to which the pedestrian and the prize-fighter, equally with the horse, are submitted for some time before they are called upon to exhibit their powers. In sleep, the respiration is generally deeper, less frequent, and appears to be effected greatly by the intercostals and diaphragm.1 Motion has also a sensible effect in hurrying the respiration, as well as distension of the stomach by food, certain mental emotions, &c: its condition during disease becomes, also, a subject of interesting study to the physician, and one that has been much facilitated by the acoustic method, introduced by Laennec. To his instrument—the stethoscope—allusion has already been made. By it or by the ear applied to the chest, we are able to hear dis- tinctly the respiratory murmur and its modifications; and thus to judge of the nature of the pulmonary affection when existent. But this is a topic that appertains more especially to pathology. 3. RESPIRATORY PHENOMENA CONCERNED IN CERTAIN FUNCTIONS. There are certain respiratory movements concerned in effecting other functions, which require consideration. Some of these have already been topics of discussion. Adelonb has classed them into: First. Those employed in the sense of smell, either for the purpose of conveying the odorous molecules into the nasal fossae; or to repel them and prevent their ingress. Secondly. The inspiratory action employed in the digestive function, as in sucking. Thirdly. Those connected with muscular motion when forcibly exerted; and parti- cularly in straining or the employment of violent effort. Fourthly. Those concerned in the various excretions, either voluntary,—as in defecation and spitting; or involuntary,—as in coughing, sneezing, vomiting, accouchement, &c; and lastly, such as constitute pheno- mena of expression—as, sighing, yawning, laughing, crying, sobbing, &c. Some of these, that have already engaged attention, do not demand comment; others are topics of considerable interest, and require investigation. 1. Straining. The state of respiration is much affected during the more active voluntary movements. Muscular exertion, of what- ever kind, when considerable, is preceded by a long and deep inspi- ration ; the glottis is then closed; the diaphragm and respiratory muscles of the chest are contracted, as well as the abdominal mus- cles which press upon the contents of the abdomen in all directions. At the same time that the proper respiratory muscles are exerted, those of the face participate, owing to their association through the medium of particular nerves. By this series of actions, the chest is rendered capacious; and the force, that can be developed, is augmented, in consequence of the trunk being rendered immovable * Adelon, Physiologie de I'Homme, iii. 185. • b ibid. p. 188. MECHANICAL PHENOMENA-STRAINING. m as regards its individual parts; which thus serves as a fixed point for the muscles that arise from it, so that they are enabled to employ their full effect.8 The physiological state of muscular action, as connected with the mechanical function of respiration, is happily described by Shak- speare, when he makes the 5th Harry encourage his soldiers at the siege of Harfleur.b In the effort required for effecting the various excretions, a simi- Fig. 119. lar action of the respiratory muscles takes place. The organs, from which these excretions have to be re- moved, exist either in the thorax or abdomen; and in all cases, they have to be compressed by the parietes of those cavities. See Fig. 119. A full inspiration is first made; the expiratory muscles, with those that close the glottis, are then forcibly and simultaneous- ly contracted, and by this means the thoracic and ab- dominal viscera are com- pressed. Some difference, however, exists, according as the viscus,to be emptied, is seated in the abdomen or thorax. In the evacuation of the faeces, the lungs are first filled with air; and, whilst the muscles of the larynx contract to close the glottis, those of the abdomen contract also; and as the lung, in conse- c . •iii • A. Right lung. B. Left lung. C. Right ventricle of the quence Ot the included air, heart. D. Right auricle of the heart. E. Vena cava supe- rfcioto ihp ncppnt nf flip rior- F. F. Subclavian veins. G,G. Internal jugular veins. icaiaia uic aauciu ui mc jj. Ascending aorta. I. Pulmonary artery. K. Dia- diaphragm, the compres-P|irasm- L> hA Right and left lobes of theiiver. m. Liga- . | s , ,r mentum rotundum. N. Fundus of gall-bladder. O. Sto- SlOn bears Upon the large mach. P. Spleen, a, a. Situation of the kidneys, behind intestine. The same hap-the intestines' R;R" Sma"intes,ines- pens in the excretion of the urine, and in accouchement. 2. Coughing and Sneezing.—When the organ, that has to be ■ Ibid. p. 190; and art. Effort, in Diet de Med. vii. 319, Paris, 1823. b " Stiffen the sinews, summon up the blood; Now set the teeth, and stretch the nostrils wide; Hold hard the breath and bend up every spirit To his full height." King Henry V. iii. 1. Thoracic and Abdominal Viscera. 112 RESPIRATION. cleared, is in the thorax,—as in coughing to remove mucus from the air-passages,—the same action of the muscles of the abdomen is invoked; but the glottis is open to allow the exit of the mucus. In this case, the expiratory muscles contract convulsively and forcibly, so that the air is driven violently from the lungs, and, in its passage, sweeps off the irritating matter and conveys it out of the body. To aid this, the muscular fibres, at the posterior part of the trachea and larger bronchial tubes, contract, so as to diminish the calibre of these canals; and, in this way, expectoration is facilitated. The action differs, however, according as the expired air is sent through the nose or mouth; in the former case, consti- tuting sneezing; in the latter, coughing. The former is more violent than the latter, and is involuntary; whilst the latter is not necessarily so. In both cases the movement is excited by some external irri- tant, applied directly to the ^mucous membrane of the windpipe or nose; or by some modified action in the very tissue of the part, which acts as an irritating cause. In both cases the air is driven forcibly forward, and both are accompanied by sounds that cannot be mistaken. In these actions, we have striking exemplifications of the extensive association of muscles, through the system of respira- tory nerves, to which we have so often alluded. The pathologist, too, has repeated opportunities for observing the extensive sympathy between distant parts of the frame, as indicated by the actions of sneezing and coughing, especially of the former. If a person be exposed for a short period to the partial and irregular application of cold, so that the capillary action of a part of the body is modified, as where we get the feet wet, or sit in a draught of air, a few minutes will frequently be sufficient to exhibit sympathetic irritation in the Schneiderian membrane of the nose, and sneezing. Nor is it necessary, that the capillary action of a distant part shall be modi- fied by the application of cold. We have had the most positive evidence, that if the capillary circulation be irregularly excited, even by the application of heat, whilst the rest of the body is re- ceiving none of its influence, inflammation of the mucous membrane of the nasal fossae and fauces follows with no less certainty. 3. Blowing the Nose.—The substance, that has to be excreted by this operation, is composed of the nasal mucus, the tears sent down the ductus ad nasum, and the particles deposited on the membrane by the air, in its passage through the nasal fossae. Commonly, these secretions are only present in quantity sufficient to keep the mem- brane moist, the remainder being evaporated or absorbed. Fre- quently, however, they exist in such quantity as to fall by their own gravity into the pharynx, where they are sent down into the stomach by deglutition, are thrown out at the mouth, or make their exit at the anterior nares. To prevent this last effect more especially, we have recourse to blowing the nose. This is accomplished by takin^ in air, and driving it out suddenly and forcibly, closing the mouth at the same time, so that the air may issue by the nasal fossae and clear them; the nose being compressed so as to make the velocity PHENOMENA CONNECTED WITH EXPRESSION. 113 of the air greater, as well as to express all the mucus that may be forced forwards. 4. Spitting differs somewhat according to the part in which the mucus or matter to be ejected is seated. At times, it is exclusively in the mouth; at others in the back part of the nose, pharynx, or larynx. When the mucus or saliva of the mouth has to be excreted, the muscular parietes of the cavity, as well as the tongue,'contract so as to eject it from the mouth; the lips being at times approxi- mated, so as to render the passage narrow, and impel the sputa more strongly forward. The air of expiration may be, at the same time, driven forcibly through the mouth, so as to send the matter to a considerable distance. The practised spitter sometimes astonishes us with the accuracy and power of propulsion of which he is ca- pable. When the matter to be evacuated is in the nose, pharynx, or larynx, it requires to be brought, first of all, into the mouth. If in the posterior nares, the mouth is closed, and the air is drawn in forcibly through the nose, the pharynx being at the same time con- stricted so as to prevent the substances from passing down into the oesophagus. The pharynx now contracts, from below to above, in an inverse movement from that required in deglutition, and the farther excretion from the mouth is effected in the manner just de- scribed. Where the matters are situate in the air-passages, the action may consist in coughing; or, if higher up, simply in hawking. A forcible expiration, unaccompanied by cough, is, indeed, in many cases, sufficient to detach the superfluous mucous secretion from even the bronchial tubes. In hawking, the expired air is forcibly sent forwards, and the parts about the fauces are suddenly con- tracted so as to diminish the capacity of the tube and propel the matters onwards. The noise is produced by their discordant vibra- tions. Both these modes bear the general name of expectoration. When these secretions are swallowed, they are subjected to the digestive process; a part is taken up, and the remainder rejected; so that they belong to the division of recremento-excrementitialfluids of some physiologists. 4. RESPIRATORY PHENOMENA CONNECTED WITH EXPRESSION. It remains to speak of the expiratory phenomena that strictly form part of the function of expression, and depict the moral feeling of the individual who gives utterance to them. 1. Sighing consists of a deep inspiration, by which a large quan- tity of air is received slowly and gradually into the lungs, to com- pensate for the deficiency in the due aeration of the blood which precedes it. The most common cause of sighing is mental uneasi- ness ; it also occurs at the approach of sleep, or immediately after waking. In all these cases the respiratory efforts are executed more imperfectly than under ordinary circumstances: the blood consequently does not circulate through the lungs in due quantity, 10* 114 RESPIRATION. but accumulates more or less in these organs, and in the right side of the heart; and it is to restore the due balance, that the deep in- spiration is now and then established. 2. Yawning, oscitancy, oscitation ox gaping, is likewise a full, deep, and protracted inspiration, accompanied by a wide separation of the jaws, and followed by a prolonged and sometimes sonorous ex- piration. Yawning is excited by many of the same causes as sigh- ing. It is not, however, the expression of any depressing passion, but is occasioned by any circumstance that impedes the necessary aeration of the blood; whether this be retardation of the action of the respiratory muscles, or the air being less rich in oxygen. Hence we yawn at the approach of sleep, and immediately after waking. The inspiratory muscles, fatigued from any cause, experience some difficulty in dilating the chest; the lungs are consequently not pro- perly traversed by the blood from the right side of the heart: oxy- genation is, therefore, not duly effected, and an uneasy sensation is induced, which is put an end to by the action of yawning, which allows the admission of a considerable quantity of air. We yawn at the approach of sleep, because the agents of respiration, becoming gradually more debilitated, require to be now and then excited to fresh activity, and the blood needs the necessary aeration. Yawning on waking seems to be partly for the purpose of stimulating the respiratory muscles to greater activity, the respiration being always slower and deeper during sleep. It is of course impossible to explain, why the respiratory nerves should be those that are chiefly con- cerned, under the guidance of the brain, in these respiratory move- ments of an expressive character. The fact, however, is certain; and it is remarkably proved by the circumstance, that yawning can be excited by even looking at another affected in this manner; nay, by simply looking at a sketch, and by even thinking of the action. The same also applies to sighing and laughing, and especially to the latter.a 3. Pandiculation or stretching is a frequent concomitant of yawn- ing, and appears to be established instinctively to arouse the exten- sor muscles to a balance of power, when the action of the flexors has been predominant. In sleep, the flexor muscles exercise that preponderance which in the waking state, is exerted by the exten- sors. This, in time, is productive of some uneasiness; and, hence, at times during sleep, but still more at the moment of wakino-, the extensor muscles are roused to action, to restore the equipoise; or, perhaps, as the muscles of the upper extremities, and those con- cerned directly or indirectly in respiration, are chiefly concerned in the action, it is exerted for the purpose of arousing the respiratory muscles to increased activity. By Dr. Good,b yawning and stretching have been regarded as morbid affections and amongst the signs of debility and lassitude:__ a Adelon, art. Baillement, in Diet, de Medecine, iii. 211, Paris, 1821 • and Physio- logie de I'Homme, 2de edit. iii. 196. ' b Study of Medicine, class 4, ord. 3, gen. 2, sp. 6. LAUGHING-WEEPING. 115 " Every one," he remarks, " who resigns himself ingloriously to a life of lassitude and indolence will be sure to catch these motions as a part of that general idleness which he covets. And, in this manner, a natural and useful action is converted into a morbid habit: and there are loungers to be found in the world, who, though in the prime of life, spend their days as well as their nights in a perpetual routine of these convulsive movements, over which they have no power; who cannot rise from the sofa without stretching their limbs, nor open their mouths to answer a plain question without gaping in one's face. The disease is here idiopathic and chronic; it may perhaps be cured by a permanent exertion of the will, and ridicule or hard labour will generally be found the best remedies for calling the will into action." 4. Laughing is a convulsive action of the muscles of respiration and voice, accompanied by a facial expression, which has been explained elsewhere. It consists of a succession of short, sonorous expirations. The air is first inspired so as to fill the lungs. To this succeed short, interrupted expirations, with simultaneous contrac- tions of the muscles of the glottis, so that this aperture is slightly- contracted, and the lips assume the tension, necessary for the pro- duction of sound. The interrupted character of the expirations is caused by convulsive contractions of the diaphragm, which con- stitute the greater part of the action. In very violent laughter, the respiratory muscles are thrown into such forcible contractions, that the hands are applied to the sides to support them. The convulsive action of the thorax likewise interferes with the circulation through the lungs; the blood, consequently, stagnates in the upper part of the body; the face becomes flushed; the sweat trickles down the forehead, and the eyes are suffused with tears; but this is appa- rently owing to mechanical causes; not to the lachrymal gland being excited to unusual action, as in weeping. At times, however, we find tfie latter cause in operation, also. 5. Weeping. The action of weeping is very similar to that of laughing; although the causes are so dissimilar. It consists in an inspiration, followed by a succession of short, sonorous expirations. The facial expression, so diametrically opposite to that of laughter, has been depicted in another place. Laughter and weeping appear to be characteristic of humanity. Animals shed tears, but this does not seem lo be accompanied with the mental emotion that characterizes crying in the sense in which we employ the term. It has, indeed, been affirmed by Steller,a that the phoca ursina or ursine seal; by Pallas,b that the camel; and by Humboldt,' that a small American monkey, shed tears when labour- ing under distressing emotions. The last scientific traveller states, that " the countenance of the titi of the Orinoco,—the simia sciurea a Nov. Comm. Academ. Scient Petropol. ii. 353. b Sainmlungen Historisch. Nachricht iiber die Mongolischen Volkerschaften, Th. i. 177. c Recueil d'Observations de Zoologie, &c, i. 333, 116 RESPIRATION. of Linnaeus,—is that of a child; the same expression of innocence; the same smile; the same rapidity in the transition from joy to sorrow. The Indians affirm, that it weeps like man, when it expe- riences chagrin; and the remark is accurate. The large eyes of the ape are suffused with tears, when it experiences fear or any acute suffering." Shakspeare's description of the weeping of the stag,— "That from the hunter's aim had ta'en a hurt," is doubtless familiar to most of our readers.0 We have less evidence in favour of the laughter of animals. Le Cat,b indeed, asserts, that he saw the chimpanse both laugh and weep. The ourang-outang, carried to Great Britain, from Batavia, by Dr. Clarke Abel, never laughed; but he was seen occasionally to weep.c • 6. Sobbing still more resembles laughing, except that, like weep- ing, it is usually indicative of the depressing passions; and generally accompanies weeping. It consists of a convulsive action of the dia- phragm; which is alternately raised and depressed, but to a greater extent than in laughing and with less rapidity. It is susceptible of various degrees, and has the same physical effects upon the circula- tion as weeping. Dr. Wardropd considers laughter, crying, weep- ing, sobbing, sighing, &c. as efforts made with a view to effect cer- tain alterations in the quantity of blood in the lungs and heart, when the circulation has been disturbed by mental emotions. 7. Panting or anhelation consists in a succession of alternate, quick, and short inspirations and expirations. Their physiology, however, does not differ from that of ordinary respiration. The object is, to produce a frequent renewal of air in the lungs, in cases where the circulation is unusually rapid; or where, owing to disease of the thoracic viscera, a more than ordinary supply of fresh air is demanded. We can, hence, understand, why dyspnoea should be one of the concomitants of most of the severe diseases of the chest; a " The wretched animal heaved forth such groans, That their discharge did stretch his leathern coat Almost to bursting ; and the big round tears Coursed one another down his innocent nose* In piteous chase; and thus the hairy fool, Much marked of the melancholy Jaques, Stood on th' extremest verge of the swift brook, Augmenting it with tears." As You Like It, ii. 1. b Traite de l'Existence du Fluide des Nerves, p. 35. c Lectures on Physiology, Zoology, and the Natural History of Man p 236 Lond 1814. d On the Nature and Treatment of Diseases of the Heart, part i. p. 62, Lond. 1837. * " The alleged ' big round tears,' which ' course one another down the innocent nose' of the deer, the hare and other animals when hotly pursued, are in fact only sebaceous matter, which, under these circumstances, flows in profusion from a collec- tion of follicles in the hollow of the cheek."—Fletcher's Rudiments of P/ivsinlrxrv part ii. b. p. 50, Edinb. 1836. . J V Sh PHENOMENA CONNECTED WITH RESPIRATION. ll? and why it should occur whenever the air we breathe does not con- tain a sufficient quantity of oxygen. The panting, produced by running, is owing to the necessity for keeping the chest as immova- ble as possible, that the whole effort may be exerted on the muscles of locomotion; and thus suspending, for a time, the respiration, or admitting only of its imperfect accomplishment. This induces an accumulation of blood in the lungs and right side of the heart; and panting is the consequence of the augmented action necessary for transmitting it through the vessels. b. Chemical Phenomena of Respiration. Having studied the mode in which air is received into, and expelled from, the lungs, we have now to inquire into the changes produced on the venous blood—containing the products of the va- rious absorptions—in the lungs, as well as on the air itself. These changes are effected by the function of sanguification, hamatosis, respiration—in the restricted sense in which it is employed by some —arterialization of the blood, decarbonization, aeration, atmosphen- zation, &c. With the ancients this process was but little understood. It was generally believed to act as the means of cooling the body; and, in modern'times, Helvetius revived the notion, attributing to it the office of refrigerating the' blood,—heated by its passage through the long and narrow channels of the circulation,—by the cool air constantly received into the lungs. The reasons, that led to this opinion, were:—that the air, which enters the lungs in a cool state, issues warm; and that the pulmonary veins, which convey the blood from the lungs, are of less dimension than the pulmonary artery, which conveys it to them. From this it was concluded, that the blood, during its progress through the lungs, must lose somewhat of its volume or be condensed by refrigeration. The warmth of the expired air can, however, be readily accounted for; whilst it is not true that the pulmonary veins are smaller than the pulmonary artery. The reverse is/indeed, the fact; and it is equally obvious, that the doctrine of Helvetius does not explain how we can exist in a temperature superior to our own: this ought, in his hypothesis, to be impracticable/ Another theory, which prevailed for some time, was:—that during inspiration the vessels of the lungs are unfolded, as it were, and that thus the passage of the blood from the right side of the heart to the left, through the lungs, is facilitated. Its progress was, indeed, conceived to be impossible during expiration, in consequence of the considerable flexures of the pulmonary vessels. The discovery of the circulatian of the blood gave rise to this theory; and Hallerb attaches considerable importance to it, when taken in connexion with the changes effected upon the blood in the vessels. It is inac- » Adelon, Physiologie de I'Homme, edit. cit. iii. 201. >> Element. Physiol, viii. 118 RESPIRATION. curate, however, to suppose, that the circulation of the blood through the lungs is mechanically interrupted, when respiration is arrested. The experiments of Williams3 and Kayb would seem to show that the interruption is owing to the non-conversion of venous into arterial blood, and to the non-adaptation of the radicles of the pulmonary veins for any thing but arterial blood, owing to which causes stagnation of blood supervenes in the pulmonary radicles.0 Numerous other objections might be made to this view. In the first place, it supposes, that the lungs are emptied at each expiration; and, again, if a simple deploying or unfolding of the vessels were all that is required, any gas ought to be sufficient for respiration,— which is not the fact. In these different theories, the principal object of respiration is overlooked—the conversion of the venous blood and its various absorptions, conveyed to the lungs by the pulmonary artery, into arterial blood. This is effected by the contact of the inspired air with the venous blood; in which they both lose certain elements, and gain others. Most physiologists have considered that the whole function of haematosis is effected in the lungs. Chaussier,d however, has presumed, that the air, in passing through the cavities of the nose and mouth, and the different bronchial ramifications, expe- riences some kind of elaboration, by being agitated with the bron- chial mucus; similar to what he conceives to be effected by the mucus on the aliment in its passage from the mouth to the stomach; but his view is conjectural in both one case and the other. Legallois,e again, thought, that haematosis commences at the part, where the chyle and lymph are mixed with the venous blood, or in the subclavian veins. This admixture, he conceives, occurs more or less immediately; is aided in the heart, and the conversion is completed in the lungs. To this belief he was led by the circum- stance, that when the blood quits the lungs it is manifestly arterial, and he thought, that what the products of absorption lose or gain in the lungs is too inconsiderable to account for the important and extensive change; and that therefore.it must have commenced pre- viously. Facts, however, are not exactly in accordance with the view of Legallois. They seem to show, that the blood of the pul- monary artery is analogous to that of the subclavian veins; and hence it is probable, that there is no other action exerted upon the fluid in this part of the venous system, than a more intimate admix- ture of the venous blood with the chyle and lymph in their passage through the heart. a Edinb. Med. and Surg. Journ. vol. lxxvii. 1823. b Edinb. Med. and Surg. Journ. vol. xxix.; and the Physiology and Pathology, &c. of Asphyxia, Lond. 1834. c See the article "Asphyxia," by the author, in the " American Cyclopedia of Practi- cal Medicine and Surgery," part x. Philad. 1836; also, Dr. W. P. Alison, in the Fourth Report of the British Association, and in Edinb. Med. and Surg. Journal, for Jan. 1836. and Dr. J. Reid, on the order of succession in which the vital actions are arrested in Asphyxia, Edinb. Med. and Surg. Journ. April, 1841, p. 437. d Adelon's Physiologie de I'Homme, iii, 205. e Annales de Chimie, iv. 115; Thomson's Chem. 5th edit, iv.,619, Lond. 1817. HAEMATOSIS 119 The changes, wrought on the air by respiration, are considerable. It is immediately deprived of a portion of both of its main con- stituents—oxygen and azote; and it always contains, when expired, a quantity of carbonic acid greater than it had when received into the lungs, along with an aqueous and albuminous exhalation to a considerable amount. Oxygen is consumed by the respiration of all animals, from the largest quadruped to the most insignificant insect; and, if we exa- mine the expired air, the deficiency is manifest. Many attempts have been made to estimate the precise quantity consumed during respiration; but the results vary essentially from each other; partly owing to the fact, that the amount, consumed by the same animal in different circumstances, is not identical. Menzies1 was probably the first that attempted to ascertain the quantity consumed by a man in a day. According to him, 36 cubic inches are expended in a minute; and, consequently, 51840 in the twenty-four hours, equal to 17496 grains. Lavoisierb makes it 46048 cubic inches, or 15541 grains. This was the result of his earlier experiments; and, in his last, which he was executing at the time when he fell a victim to the tyranny of Robespierre, he made it 15592.5 grains; correspond- ing largely with the results of his earlier observations. The experi- ments of Sir Humphry Davyc coincide greatly with those of La- voisier. He found the quantity consumed in a minute to be 31.6 cubic inches; making 45504 cubic inches, or 15337 grains in twenty-four hours. The results obtained by Messrs. Allen and Pepysd make it much less. They consider the average consumption to be, in the twenty-four hours, under ordinary circumstances, 39534 cubic inches, equal to 13343 grains. Now, if we regard the experi- ments of Lavoisier and Davy, between which there is the greatest coincidence, to be an approximation to the truth, it will follow, that in a day, a man consumes rather more than 25 cubic feet of oxy- gen ; and as the oxygen amounts to only about one-fifth of the respired air, he must render 125 cubic feet of air unfit for supporting combustion and respiration. The experiments of Crawford, Jurine, Lavoisier and Seguin Prout, Fyfe, and Edwards,6 have proved, that the quantity of oxygen consumed varies according to the condition of the functions and of the system generally. Seguinf found, that muscular exertion increases it nearly fourfold. Prout,s who gave much attention to the subject, was induced to conclude, from his experiments, that moderate exercise increases the consumption; but if the exercise be continued so as to induce fatigue, a diminished consumption takes place. The exhilarating passions also appeared to increase the a A Dissertation on Respiration, p. 21, Edinb. 1796. b Memoir, de I'Academ. des Sciences, 1789, 1790. c Researches, &c. p. 431. d Philosoph. Transact for 1808. e De l'Influence des Agens Physiques sur la Vie, p. 410, Paris, 1824; or Hodgkin and Fisher's translation. f Mem. de I'Academ. des Sciences, 1789 and 1790. ? Annals of Philos. ii. 330, iv. 331, and xiii. 269. 120 RESPIRATION. quantity; whilst the depressing passions and sleep, the use of alcohol and tea, diminished it. He discovered, also, that the quantity of oxygen consumed is not uniformly the same during the twenty-four hours. Its maximum occurred between 10 A. M. and 2 P. M., or generally between 11 A. M. and 1 P. M.; its minimum commenced about 81 P. M., and it continued nearly uniform till about 3^ A. M. Dr. Fyfea found, that the quantity was likewise diminished by a course of nitric acid, by a vegetable diet, and by affecting the system with mercury. Temperature, also, has an influence. Crawfordb found, that a Guinea-pig, confined in air at the temperature of 55°, consumed double the quantity which it did in air at 104°. He also observed, in such cases, that the venous blood, when the body was exposed to a high temperature, had not its usual dark colour; but, by its florid hue, indicated that the full change had not taken place in its constitution, in the course of circulation. We may thus understand the great lassitude and yawning, induced by the hot wreather of summer; and the languor and listlessness which are so characteristic of those who have long resided in torrid climes. Dr. Prout conceives, that the presence or absence of the sun alone regulates the variation in the consumption of oxygen which he has described; but the deduction of Dr. Fleming0 appears to us more legitimate,—that it keeps pace with the degree of mus- cular action, and is dependent upon it. Consequently, a state of increased consumption is always followed by an equally great decrease, in the same manner as activity is followed by fatigue. The disagreement of experimenters, as respects the removal of nitrogen or azote from the air, during respiration, is still greater than in the case of oxygen. Priestley, Davy, Humboldt, Henderson, Cuvier, Pfaff, and Thomson, found a less quantity exhaled than was inspired. Spallanzani, Lavoisier and Seguin, Vauquelin, Allen and Pepys, Ellis, and Dalton, inferred that neither absorption nor exha- lation takes place,—the quantity of that gas, in their opinion, under- going no change during its passage through the air-cells of the lungs; whilst Jurine, Nysten, Berthollet, and Dulong and Des- pretz, on the contrary, found an increase in the bulk of the azote.d In this uncertainty, most physiologists have been of opinion that the azote is entirely passive in the function. The facts, ascertained by Dr. W. F. Edwards,6 of Paris, shed considerable light on the causes of this discrepancy amongst observers. He has satisfactorily shown that, during the respiration of the same animal, the quantity of azote may, at one time, be augmented, at another, diminished, and, at a third, wholly unchanged. These phenomena he has traced to the influence of the seasons, and he suspects that other causes have a share in their production. In nearly all the lower animals that were the subjects of experiment, an augmentation of azote was observable during summer. Sometimes, indeed, it was so slio-ht » Annals of Philos. iv. 334, and Bostock's Physiol, i. 350. b Qp. cit p 387 <= Philosophy of Zoology, Edinburgh, 1822. " d Bostock, op. citat. 3d edit' p 356 e Op. citat. p. 462. ' r' ILEMATOSIS. 121 that it might be disregarded; but, in numerous other instances, it was so great as to place the fact beyond the possibility of doubt; and, on some occasions, it almost equalled the whole bulk of the animal. Such were the results of his observations until the close of October, when he noticed a sensible diminution in the nitrogen of the inspired air, and the same continued throughout the whole of winter and the beginning of spring. Dr. Edwards considers it pro- bable, that, in all cases, both exhalation and absorption of azote are going on; that they are frequently accurately balanced, so as to exhibit neither excess nor deficiency of azote in the expired air, whilst, in other oases, depending, as- it would appear, chiefly upon temperature, either the absorption or the exhalation is in excess, producing a corresponding effect upon the composition of the air of expiration. But. not only has the respired air lost its oxygenous portion, it has gained, as we have remarked, an accession of carbonic acid, and, likewise, a quantity of serous vapour. If we breathe through a tube, one end of which is inserted into a vessel of lime-water, the fluid soon becomes milky, owing to the formation of carbonate of lime, which is insoluble in water. Carbonic acid must consequently have been given off from the lungs. In the case of this gas, again, the quantity, formed in the day, has been attempted to be computed. Jurine conceived, that the amount, in air once respired in natural respiration, is in the enormous pro- portion of -j^di or Tjth. Menzies, that it is ^\h; and, from his esti- mate of the total quantity of air respired in the twenty-four hours, he deduced the amount of carbonic acid formed to be 51840 cubic inches, equal to 24105.6 grains. Lavoisier and Seguin,* in their first experiments, valued it at 17720.89 grains; but in the very next year they reduced their estimate more than one-half;—to 8450.20 grains; and, in Lavoisier's last experiment, it was farther reduced to 7550.4 grains. Sir Humphry Davy's estimate nearly corre- sponds with that of the first experiment of Lavoisier and Seguin,— 17811.36 grains; and Messrs. Allen and Pepys accord pretty nearly with him. These gentlemen found, that atmospheric air, when inspired, issued on the succeeding expiration, charged with from 8 to 6 per cent, of carbonic acid gas; but this estimate exceeds con- siderably that of Dr. Apjohn,b of Dublin, who, in his experiments, found the expired air to contain only 3.6 per cent, of this gas. The experiments and observations of Crawford, Prout, Edwards, and others, to which we have referred—as regards the consumption of oxygen, under various circumstances—apply equally to the quantity of carbonic acid formed, which always bears a pretty close propor- tion to the oxygen consumed. These experiments also account, in 1 Memoir, de I'Academ. des Sciences, p. 609, Paris, 1790. bEdinb. Med. and Surg. Journal, Jan. 1831; Dublin Hospitab Reports, vol. v.; and Select Medico-Chirurgical Tansactions, p. 230, Philad. 1831. See, also, Mr. Coathupe, Philos. Magaz. June, 1839. VOL. II. 11 122 RESPIRATION. some degree, for the discrepancy in the statements of different indi- viduals on this subject. It has been a question amongst physiologists, whether the quan- titv of carbonic acid gas given out is equal in bulk to the oxygen taken in. In Priestley's* experiments, the latter had the preponde- rance. Menzies and Crawford found them to be equal. Lavoisier and Seguin supposed the oxygen, consumed in the twenty-four hours, to be 15661.66 grains; whilst the oxygen, required for the formation of the carbonic acid given out, was no more than 12924 grains; and Sir Humphry Davy, in the same time, found the oxygen consumed to be 15337 grains, whilst the carbonic acid produced was 17811.36 grains; which would contain 12824.18 grains of oxygen. The ex- periments of Allen and Pepys seem, however, to show that the oxygen which disappears is replaced by an equal volume of car- bonic acid; and hence, it was supposed, that the whole of it must have been employed in the formation of this acid. The^y, conse- quently, accord with Menzies and Crawford; and thcview is em- braced by Dalton, Prout, Ellis, Henry, and other distinguished indi- viduals.11 On the other hand, the view of those, who consider that the quantity of carbonic acid produced is less than that of the oxygen which has disappeared, is embraced by Thomson, and by Dulong and Despretz. In the carnivorous animal, they found the difference as much as one-third; in the herbivorous, on the average, only one-tenth. The more recent experiments of Dr. Edwards have shown, that here, also, the discordance has not depended so much upon the different methods and skill of the operators, as upon a variation in the results arising from other causes; and he con- cludes, that the proportion of oxygen consumed, to that employed in the production of carbonic acid, varies from more than one- third of the volume of carbonic acid to almost nothing; that the variation depends upon the particular animal species, subjected to experiment; upon its age, or on some peculiarity of constitution, and that it differs considerably in the same individual at different times. It would appear, then, that the whole of the oxygen, which re- spiration abstracts from the air, is not accounted for, in all cases, by the quantity of carbonic acid formed; and that, consequently, a portion of it disappears altogether. It has been supposed by some, that a part of the watery vapour, given off during expiration, is occasioned by the union of a portion of the oxygen of the air with hydrogen from the blood in the lungs; but this view is entirely con- jectural. This subject, with the quantity of vapour combined with the expired air, will be the subject of inquiry under the head of Secretion. The air likewise loses, during inspiration, certain foreign mat- ters that may be diffused in it. In this way, medicines have been a Experiment?, &c. on different kinds of Air, vol. iii. b Bostock's Ihysio'ogy, 3d edit. p. 352, Lend. 1836. ILEMATOSIS. 123 attempted to be conveyed into the system. If air, charged with odorous particles,—as with those of turpentine,—be breathed for a short time, their presence in the urine will be detected; and it is probably in this manner, that miasmata produce their effects on the frame. All these substances pass immediately through the coats of the pulmonary veins by imbibition, and, in this way, speedily affect the system. These changes, produced in the air during respiration, are easily shown, by placing an animal under a bell-glass until it dies. On examining the air, it will be found to have lost a portion of its oxy- gen and azote and to contain carbonic acid and aqueous vapour. Let us now inquire whether the changes produced in the respired air are connected with those effected on the blood in the lungs. In its progress through the lungs, this fluid has been changed from venous into arterial. It has become of a florid red colour; of a stronger odour; of a higher temperature by nearly two degrees, according to some,3 but others have perceived no difference; of less specific gravity ; and it coagulates more speedily, according to most observers, but Thackrahb observed the contrary.0 That this con- version is owing to the contact of air in the lungs we have many proofs. Lowerd was one of the first, who clearly pointed out, that the change of colour occurs in the capillaries of the lungs. Prior to his time, the most confused notions had prevailed on the subject, and the most visionary hypotheses had been indulged. On opening the thorax of a living animal, he observed the precise point of the circulation at which the change of colour takes place, and he showed, that it is not in the heart, since the blood continues to be purple, when it leaves the right ventricle. He then kept the lungs artifi- cially distended, first with a regular supply of fresh air, and after- wards with the same portion of air without renewing it. In the former case, the blood experienced the usual change of colour. In the second, it was returned to the left side of the heart unchanged. Experiments, more or less resembling those of Lower, have been performed by Goodwyn,6 Cigna, Bichat,f Wilson Philip, and nume- rous others, with similar results. The direct experiments of Priestley^ more clearly showed, that the change, effected on the blood, was to be ascribed to the air. He found, that the clot of venous blood, when confined in a small quantity of air, assumed a scarlet colour, and that the air expe- rienced the same change as by respiration. He afterwards exa- * Magendie, Precis de Physiologie, ii. 343; and Dr. J. Davy, in Philos. Transact. for 1814. b Inquiry into the Nature and Properties of the Blood, p. 42, Lond. 1819. e See, on this subject, J. Muller's Handbuch, u. s. w. Baly's translation, p. 323; and Burdaeh's Physiologie als Erfahrungswissenschaft, Band. iv. s. 381, Leipz. 1832. d Tractatus de Corde, &c. c. iii. Amstelod. 1761. e The Connexion of Life with Respiration, &c, Lond. 1788. f Recherches Physiol, sur la Vie et la Mort, Paris, 1800. s Experiments, &c. on different kinds of Air, &c. Lond. 1781. 124 RESPIRATION. mined the effect produced on the blood by the gaseous elements of the atmosphere separately, as well as by the other gaseous fluids that had been discovered. The clot was reddened more rapidly by oxygen than by the air of the atmosphere, whilst it was reduced to dark purple by nitrogen, hydrogen, and carbonic acid. Since Priestley's time, the effect of different gases on the colour of venous blood has been investigated by numerous individuals. The following is the result of their observations, as given by The- nard.a It must be remarked, however, that all the experiments have been made on blood, when out of the body; and it by no means follows, that precisely the same changes would be accom- plished if the fluid were circulating in the vessels. Gas. Colour. Remarks. Atmospheric air - -Ammonia - - - -Gaseous oxide of carbon Deutoxide of azote Carbuietted hydrogen Azote ------Carbonic acid - - -Hydrogen - - - -Protoxide of azote Arsenuretted hydrogen Sulphuretted hydrogen Hydrochloric gas - -Sulphurous gas - - Rose red. Do. Cherry red. Slightly violet redl Do. Do. Brown red. Do.» Do. Do. C Deep violet, passing < gradually to a green-([ ish brown. Maroon brown. "J Black brown. f Blackish brown, ! J passing by degrees [ 1 to a yellowish [ white. J The blood employed had been beaten, and, consequently, deprived of its fibrine. These three gases coagulate the blood at the same time. It is sufficiently manifest, then, from the disappearance of a part of the oxygen from the inspired air, and from the effects of that gas on venous blood out of the body, that it forms an essential part in the function of sanguification. But we have seen, that the expired air contains an unusual proportion of carbonic acid. Hence carbon, either in its simple state or united with oxygen, must have been given off from the blood in the vessels of the lungs. To account for these changes on chemical principles has been a great object with chemical physiologists at all times. At one time, the conversion of venous into arterial blood was supposed to be a kind of combustion; and, according to the notion of combustion then prevalent, it was presumed to consist in the disengagement of phlo- giston ; in other words, the abstraction or addition of a portion of phlogiston, made the blood, it was conceived, arterial or venous; a Traite de Chimie, &c. 5e edit. Paris, 1827. b Muller says he agitated blood with hydrogen, but could perceive no change of colour. Handbuch, u. s. w. Baly's translation, p. 322, Lond. 1838. H^MATOSIS 125 and the removal of phlogiston was looked upon as the principal use of respiration. This view was modified by Lavoisier, who proposed one of the chemical views to be now mentioned. Two chief chemical theories, have been framed to explain the mode in which the carbon is given off. The first is that of Black,3 Priestley,b Lavoisier,0 and Crawford ;d—that the oxygen of the in- spired air attracts carbon from the venous blood, and that the car- bonic acid is generated by their union. The second, which has been supported by Lagrange6 Hassenfratz/ Edwards,^ and others,— that the carbonic acid is generated in the course of the circulation, and is given off from the venous blood in the lungs, whilst oxygen gas is absorbed. The former of these views is still maintained by many physiolo- gists. It is conceived, that the oxygen, derived from the air, unites with certain parts of the venous blood,—the carbon and the hydro- gen,—owing to which union carbonic acid and water are found in the expired air; the venous blood, thus depurated of its carbon and hydrogen becomes arterialized; and, in consequence of these various combinations, heat enough is disengaged to keep the body always at the due temperature. According to this theory, as we have seen in the views of Priestley, Lavoisier, &c. respiration is assimilated to combustion. The resemblance, indeed, between the two processes is, at first sight, considerable. The presence of air is absolutely neces- sary for respiration; in every variety of respiration the air is robbed of a portion of its oxygen; and hence a fresh supply is continually needed; and respiration is always arrested before the whole of the oxygen of the air is exhausted, and this partly on account of the residuary azote, and the carbonic acid gas given off during expira- tion. Lastly, it can be continued much longer when an animal is confined in pure oxygen gas than in atmospheric air. All these cir- cumstances likewise prevail in combustion. Every kind of com- bustion requires the presence of air. A part of the oxygen is con- sumed; and, unless the air be renewed, combustion is impossible. It is arrested, too, before the whole of the oxygen is consumed, owing to the residuary azote, and the carbonic acid formed; and it can be longer maintained in pure oxygen than in atmospheric air. More- over, when the air has been respired, it becomes unfit for combus- tion,—and conversely. Again, the oxygen of the air, in which combustion is taking place, combines with the carbon and hydrogen of the burning body; hence the formation of carbonic acid and water; and as, in this combination, the oxygen passes from the state of a very rare gas, or one containing a considerable quantity 2 Lectures on the Elements of Chemistry, by Robison, ii. 87, Edinb. 1803. b Philosoph. Trans, for 1776, p. 147. c Mem. de l'Acad. des Sciences, pour 1777, p. 185. <» On Animal Heat, 2d edit Lond. 1788. e Annales de Chimie, ix. 269. f Ibid. ix. 265. « De l'lnfluence des Agens Physiques, &c. p. 411, Paris, 1823; and Hodgkin and Fisher's translation. 11* 126 RESPIRATION. of caloric between its molecules, to the condition of a much denser gas, or even of a liquid, the whole of the caloric, which the oxygen contained in its former state, can no longer be held in the latter, and it is accordingly disengaged; hence the heat, which is given off. In like manner, in respiration, the oxygen of the inspired air it is conceived, combines with the carbon and hydrogen of the venous blood, giving rise to the formation of carbonic acid and water; and, as in these combinations, the oxygen passes from the state of a very rare to that of a denser gas, or of a liquid, there is a considerable disengagement of caloric, which becomes the source of the high temperature maintained by the human body. M. Thenard* admits a modification of this view,—sanguification being owing, he conceives, to the combustion of the carbonaceous parts of the venous blood, and probably of its colouring matter, by the oxygen of the air. This chemical theory, which originated chiefly with Lavoisier, and La Place and Seguin, was adopted by many physiologists with but little modification. Mr. Ellis imagined, that the carbon is separated from the venous blood by a secretory process; and that, then, coming into direct contact with oxygen, it is converted into carbonic acid. The cir- cumstance that led him to this opinion was his disbelief in the possibility of oxygen being able to act upon the blood through the animal membrane or coat of the vessel in which it is confined. It is obvious, however, that to reach the blood circulating in the lungs, the oxygen must, in all cases, pass through the coats of the pul- monary vessels. These coats, indeed, offer little or no obstacle, and, consequently, there is no necessity for the vital or secretory action suggested by Mr. Ellis. Priestley and Hassenfratz exposed venous blood to atmospheric air and oxygen in a bladder. In all cases, the parts of the blood, in contact with the gases, became of a florid colour. The experiments of Faust, Mitchell, and others (vol. i. p. 48) are, in this aspect, pregnant with interest. They prove the great facility with which the tissues are penetrated by the gases, and confirm the facts developed by the experiments of Priestley, Hassenfratz and others. The second theory,—that the carbonic acid is generated in the course of the circulation,—was proposed by Lagrange, in conse- quence of the objection he saw to the former hypothesis__that the lung ought to be consumed by the perpetual disengagement of caloric taking place within it; or, if not so, that its temperature ought, at least, to be superior to that of other parts. He accordingly sug- gested, that, in the lungs, the oxygen is simply absorbed, passes into the venous blood, circulates with it, and unites, in its course, with the carbon and hydrogen, so as to form carbonic acid and water, which circulate with the blood and are finally exhaled from the lungs. 5 Traite de Chimie, edit, citat. H.E.MATOSIS. 127 The ingenious and apparently accurate experiments of Dr. Ed- wards* prove convincingly, not only that oxygen is absorbed by the pulmonary vessels, but that carbonic acid is exhaled from them. When he confined a small animal in a large quantity of air, and continued the experiment sufficiently long, he found, that the rate of absorption was greater at the commencement than towards the termination of the experiment; whilst at the former period, there was an excess of oxygen present, and at the latter an excess of carbonic acid. This proved to him that the diminution was depen- dent upon the absorption of oxygen, not of carbonic acid. His experiments, in proof of the exhalation of carbonic acid, ready formed, by the lungs, are decisive. Spallanzani had asserted, that when certain of the lower animals are confined in gases, containing no oxygen, the production of carbonic acid is uninterrupted. Upon the strength of this assertion, Edwards confined frogs in pure hydro- gen, for a length of time. The result indicated, that carbonic acid was produced, and, in such quantity as to show, that it could not have been derived from the residuary air in the lungs; as it was, in some cases, equal to the bulk of the animal. The same results, > although to a less degree, were obtained with fishes and snails,— the animals on which Spallanzani's observations were made. The experiments of Edwards were extended to the mammalia. Kittens, two or three days old, were immersed in hydrogen : they remained in this situation, for nearly twenty minutes, without dying, and on examining the air of the vessel after death, it was found, that they had given off a quantity of carbonic acid greater than could pos- sibly have been contained in their lungs at the commencement of the experiment. The conclusion, deduced by Dr. Edwards, from his various experiments, is, " that the carbonic acid expired is an exhalation proceeding wholly or in part from the carbonic acid contained in the mass of blood." Several experiments were sub- sequently made by M. Collard de Martigny,b who substituted azote for hydrogen; and, in all cases, carbonic acid gas was given out in considerable quantity. These and other experiments would seem, then, to show, that, in the lungs, carbonic acid is exhaled, and that oxygen and azote are absorbed. They would also seem to prove the existence of car- bonic acid in venous blood, respecting which so much dissidence has existed amongst chemists. (See p. 61.) Allusion has already been made to the fact, that gelatine is not met with in the blood, and to the idea of Dr. Prout,c that its forma- tion from albumen must be a reducing process. This process, he considers to be one great source of the carbonic acid, which exists in venous blood. Gelatine contains three or four per cent, less a Op. citat. p. 437, and Messrs. Allen and Pepys, in Philos. Transactions for 1829. b Journal de Physiologie, x. 111. For an account of various experiments relative to the exhalation of carbonic acid, during respiration in gases which contain no oxygen, see Muller's Handbuch, u. s. w., Baly's translation, p. 338, Lond. 1838. c Bridge water Treatise, Amer. Edit. p. 280, Philad. 1834. 128 RESPIRATION. carbon than albumen; it enters into the structure of every part of the animal frame, and especially of the skin; the skin, indeed, contains little else than gelatine. Dr. Prout considers it, therefore, most proba- ble, that a large part of the carbonic acid of venous blood is formed in the skin, and analogous textures. " Indeed," he adds, " we know, that the skin of many animals gives off carbonic acid, and absorbs oxygen ;—in other words, performs all the offices of the lungs;—a function of the skin perfectly intelligible, on the supposition, that near the surface of the body, the albuminous portions of the blood are always converted into gelatine." Gmelin, Tiedemann, and Mitscherlich,1 and Stromeyer,b affirm, however, on the strength of experiments, that the blood does not contain free carbonic acid gas, but that it holds a certain quantity in a state of combination, which is set free in the lungs, and commingles with the expired air. The views of Gmelin and Tiedemann, and Mitscherlich on this subject, are as follows. It may be laid down as a truth, that the greater part, if not all, of the properties of secreted fluids are not dependent upon any act of the secreting organs, but are derived from the blood, which again must either owe them to the food, or to changes effected on it within the body. These changes are probably accom- plished in part, during the process of digestion, but are doubtless mainly effected on the lungs by the contact of the blood with the air. Now, most of the animal fluids, when exposed to the air generate, by the absorption of oxygen, acetic or lactic acid, and this is aided by an elevated temperature like that of the lungs. In their theory of respiration, the azote of the inspired air is but sparingly absorbed; by far the greater proportion remaining in the air-cells. The oxygen, on the other hand, penetrates the membranes freely, mino-les with the blood, combines partly with the carbon and hydrogen of that fluid, and generates carbonic acid and water, which are thrown off with the expired air, whilst the remainder combines with the organic particles of the blood, forming new compounds, of which the acetic and lactic acids are some; these unite with the carbonated alkaline salts of the blood, and set the carbonic acid free, so that it can be thrown off by the lungs. The acetate of soda, thus formed during the passage of the blood through the lungs, is deprived of its acetic acid by the several secretions, especially by those of the skin and kidneys, and the soda again combines with the carbonic acid, which, during the circulation of the blood through the body, is formed by the decomposition of its organic elements. Carbonate of soda is thus regenerated and conveyed to the lungs, to be again decomposed by the fresh formation of acids in those organs. A similar view, in many respects, is held by Professor Arnold.0 As it is more than probable, he remarks, that the carbonic acid 4 Tiedemann und Treviranus, Zeitschrift fiir Physiol. B. v. H. i. b Schweigger's Journal fur Chemie, u. s. w. Ixiv. 105. c Lehrbuch der Physiologie des Menschen, Zurich, 1836-7; and Brit and For Med Rev. Oct 1B39, p. 481. See, on this subject, Dr. J. Davy, Researches, Physiolofficai and Anatomical, Dunglison's Amer. Med. Lib. Edit., p. 80, Philad 1840 H^MATOSIS. 129 occurs in the venous blood, united with some substance from which it is separated, with greater or less rapidity, by the contact of the atmospheric air; and as, further, the carbonate of the protoxide of iron greedily withdraws oxygen from the atmosphere, at the same time parting with its carbonic acid and becoming changed into a peroxide, it may reasonably be supposed, he thinks, that the carbonic acid of the venous blood is united with the iron of the red colouring matter, and that it is set free during the act of respiration, by the reciprocal action of the blood and air. The protoxide, at the same time, by absorption of oxygen, becomes a peroxide, which, during the circulation of the blood through the capillaries, again parts with its oxygen. Carbon is at the same time eliminated'from the blood, and unites with the liberated oxygen to form carbonic acid, which is thrown out by the lungs, whilst oxygen is again absorbed. Chaussier and Adelon,3 again, regard the whole process of haema- tosis as essentially organic and vital. They think, that an action of selection and elaboration is exerted both as regards the reception of the oxygen and the elimination of the carbonic acid. But their arguments on this point are unsatisfactory, and are negatived by the facility with which oxygen can be imbibed, and with which car- bonic acid transudes through animal membranes. In their view, the whole process is effected in the lungs, as soon as the air comes in contact with the vessel containing the venous blood. The imbibi- tion of oxygen they look upon as a case of ordinary absorption; the transudation of carbonic acid as one of exhalation; both of which they conceive to be, in all cases, vital actions, and not to be likened to any physical or chemical operation. Admitting, then, that the oxygen and a portion of nitrogen abso- lutely enter the pulmonary vessels, of which we appear to have direct proof, are they, it has been asked, separated from the air in the air-cells, and then absorbed; or does the air enter, undecom- posed, into the vessels, and then furnish the proportion of each of its constituents necessary for the wants of the system, the excess being rejected? Could it be shown that such a decomposition is actually effected at the point of contact between the pulmonary vessels and the air in the lungs, it would seem, at first, to prove the notion of Ellis,b and of Chaussier and Adelon, that an action of selec- tion, or of vitality is exerted; but the knowledge we have attained of late, of the transmission of gases through animal membranes, would suggest another explanation. The rate of transmission of carbonic acid is greater than that of oxygen; and that of oxygen greater than that of azote, (see vol. i. p. 48.) We can hence under- stand, that more oxygen than azote may pass through the coats of the pulmonary blood-vessels, and can comprehend the facility with which the carbonic acid, formed in the course of the circulation, permeates the same vessels, and mixes with the air in the lungs. a Physiologie de I'Homme, edit. cit. iii. 254. b An Enquiry into the Changes induced on Atmospheric Air, &c. Edinb. 1807; and Further Enquiries, Edinb. 1816. 130 RESPIRATION. Sir Humphry Davy is of opinion, that the whole of the air is absorbed, and that the surplus quantity of each of the constituents is subsequently discharged. In favour of this view, he remarks, that air has the power of acting upon the blood through a stratum of serum, and he thinks that the undecomposed air must be absorbed before it can arrive at the blood in the vessels. It is obvious, how- ever, from the different penetrating powers of the gases—oxygen and azote—which compose it, that the proportion of those con- stituents cannot be the same in the interior as at the exterior of the pulmonary vessels. Muller,a however, accords with Davy, and supposes that the air, on entering the lungs, is decomposed in con- sequence of the affinity of the oxygen for the red particles of the blood ; carbonic acid being formed, which is exhaled in the gaseous form, along with the greater part of the nitrogen. It has been remarked, that when oxygen is applied to venous blood, the latter assumes a florid colour. On what part of the blood, then, does the oxygen act ? The general belief is, upon the red globules. The facts, which we have stated in the description ,of venous blood, have shown, that these globules appear to consist of a colourless nucleus, surrounded by a coloured envelope; that both of these are devoid of colour, whilst they exist as chyle and lymph; but that, in the lungs, the contact of air changes the envelope to a florid red. Some, indeed, have believed, that both the envelope and its colour are added in the lungs. The coloration of the blood, con- sequently, seems to be effected in the lungs; but whether this change is of any importance in haematosis is doubtful. Several tissues of the body are not supplied with red blood; in many animals, the red colour does not exist; and, in all, it can perhaps only be esteemed an evidence, that the other important changes have been accom- plished in the lungs. Recently, the opinion has been revived, that the oxygen of the air acts upon the iron, which Engelhartb and Rose0 have detected in the colouring matter, but how we know not. It is asserted, that if the iron be separated, the rest of the colouring matter, which is of a venous red colour, loses the property of becoming scarlet by the contact of oxygen. A different view of arterialization has been advanced by Dr. Stevens/1 According to him, the colouring matter of the blood is naturally very dark; is rendered still darker by acids, and acquires a florid hue from the addition of chloride of sodium, and from the neutral salts of the alkalies generally. The colour of arterial blood * Handbuch, u. s. w., Baly's translation, p. 334, Lond. 1838; see, also, Magnus, in Annales de Chime et de Physique, Nov. 1837. b Comment, de Vera Materie Sanguini Purpureum Colorem Impertientis Natura. Gott. 1825. c Edinburgh Med, and Surg. Journal, for Jan. 1827. d Observations on the Healthy and Diseased Properties of the Blood, Lond, 1832; and Proceedings of the Royal Society, for 1834-5, p. 334. See, also, Dr. Robert'e. Rogers, in"Amer, Journ, of the Med. Scienoes, p. 282, Aug. 1836; and Mr. Ancell Lectures on the Physiology and Pathology of the Blood, Feb, 1, 1840, p. 686, HAEMATOSIS. 131 is ascribed by him to hematosine reddened by the salts contained in the serum ; the characters of venous blood to the presumed pre- sence of carbonic acid, which, like other acids, darkens hematosine; and the conversion of venous into arterial blood to the influence of the saline matter in the serum being restored by the separation of carbonic acid. If we take a firm clot of venous blood, cut off a thin slice, and soak it for an hour or two in repeatedly renewed portions of distilled water; in proportion as the serum is washed away, the colour of the clot deepens, and, when scarcely any serum remains, the colour, by reflected light, is quite black. In this state, it may be exposed to the atmosphere, or a current of air may be blown upon it, without any change of tint whatever; whence it would follow, that when a clot of venous blood, moistened with serum, is made florid by the air, the presence of serum is essential to the phenomenon. The serum is believed, by Dr. Stevens, to contribute to this change by means of its saline matter; for when a dark clot of blood, which oxygen fails to redden, is immersed in a pure solution of salt, it quickly acquires the crimson tint of arterial blood, and loses it again when the salt is abstracted by soaking in distilled water. The facts, detailed by Stevens, are confirmed by Mr. Prater,* and by Dr. Turner,b of the London University. The latter gentleman, assisted by Professor Quain, of the same institution, performed the following satisfactory experiment. He collected some perfectly florid blood from the femoral artery of a dog; and on the following day, when a firm coagulum had formed, several thin slices were cut from the clot with a sharp penknife, and the serum was removed from them by distilled water, which had just before been briskly boiled, and allowed to cool in a well-corked bottle. The water was gently poured on these slices, so that while the serum was dissolved, as little as possible of the colouring matter should be lost. After the water had been poured off, and renewed four or five times, occupy- ing in all about an hour, the moist slices were placed in a saucer, at the side of the original clot, and both portions were shown to several medical friends, all of whom unhesitatingly pronounced the unwashed clot to have the perfect appearance of arterial blood, and the washed slices to be as perfectly venous. On restoring one of the slices to the serum, it shortly recovered its florid colour; and another slice, placed in a solution of bicarbonate of soda, instantly acquired a similar tint;—yet, as we have seen, the carbonate of soda is con- sidered by Messrs. Gmelin, Tiedemann, and Mitscherlich, to exist in venous or black blood ! In brightening, in this way, a dark clot by a solution of a salt or a bicarbonate, Dr. Turner found the colour to be often still more florid than that of arterial blood; but the colours were exactly alike when the salt was duly diluted. Dr. Turner remarks, that he is at ' Expcrim. Inquiries in Chemical Physiology, part. i. on the Blood, Lond. 1832. b Elements of Chemistry, 5th edit, by F. Bache, p. 609, Philad. 1835. 132 RESPIRATION. a loss to draw any other inference from this experiment, than that the florid colour of arterial blood is not due to oxygen, but, as Dr. Stevens affirms, to the saline matter of the serum. The arterial blood, which was used, had been duly oxygenized within the body of the animal, and should not in that state have lost its tint by the mere removal of its serum; and he adds, the change from venous to arterial blood appears, contrary to the received doctrine, to consist of two parts essentially distinct: one is a chemical change, essential to life, accompanied by the absorption of oxygen, and the evolution of carbonic acid; the other depends on the saline matter of the blood, which gives a florid tint to the colouring matter after it has been modified by the action of oxygen. " Such," says Dr. Turner, " appears to be a fair inference from the facts above stated; but being drawn from very limited observations, it is offered with diffi- dence, and requires to be confirmed or modified by future re- searches." But we are perhaps scarcely justified in inferring from the experiments of Stevens, Turner, and others, more than the fact, that a florid tint is communicated to blood by sea-salt, and by the neutral salts of the alkalies in general, and indeed by admixture with sugars; whilst acids render it still darker. The precise changes that occur during the arterialization of the blood in the lungs, are still unknown; and if we rely on the recent experiments of Gmelin, Tiedemann, and Mitscherlich, venous blood cannot owe its colour to free carbonic acid, because none is to be met with in it; whilst the presence of the carbonates of alkalies ought to communicate the florid hue to it. Since Dr. Stevens first published his opinions, the subject has been farther investigated by J)r. William Gregory, and by Mr. Irvine. They introduced portions of clot, freed, by washing, from serum, into vessels containing pure hydrogen, nitrogen, and carbonic acid, placed over mercury. As soon as the strong saline solution came in contact with them, the colour of the clot, in all the true gases, changed from black to bright red, and the same change was found to take place in the Torricellian vacuum. On repeating these experiments with the serum of the blood, and a solution of salt in water of equal strength with the serum, no change took place until atmospheric air, or oxygen gas, was admitted. It therefore appears —as properly inferred by the late Mr. Egerton A. Jennings, from whom we have an interesting " Report on the Chemistry of the Blood as Illustrative of Pathology,"1—that though saline matter may be necessary to effect the change of colour from that of venous to that of arterial blood, still, with so dilute a saline solu- tion, as that which exists in serum, the presence of oxygen is like- wise necessary. Dr. Davyb dissents, however, from those conclusions, and is dis- * Transactions of the Provincial Medical and Surgical Association vol. iii. Wor- cester and London, 1835. b Researches, Physiological and Anatomical, Dunglison's Amer Med Lib Edit p. 96, Philad. 1840. ILEMATOSIS. 133 posed to infer, from all the facts with which he is acquainted, that the colour of the blood, whether venous or arterial, that is, dark or florid, is independent of the saline matter in the serum, considered in relation to agency; and that, according to the commonly re- ceived view, oxygen is the cause of the bright hue of the arterial fluid, and its consumption and conversion into carbonic acid, the cause of the dark hue of the venous—the saline matter being nega- tive in regard to colour, and its chief use being, in his opinion, " to preserve the red globules from injury, prevent the solution of their colouring matter, retain their forms unchanged, and to bear them in their course through the circulation." The slight diminution, if it exists, in the specific gravity of arterial blood is considered, but we know not on what grounds, to depend on the transpiration, which takes place into the air-cells, and which was formerly thought to be owing to the combustion of oxygen and hydrogen. This will engage us in another place, as well as the changes produced in its capacity for heat, on which several inge- nious speculations have been founded, to account for animal tem- perature. The other changes are at present inexplicable, and can only be understood hereafter by minute chemical analysis, and by an accurate comparison of the two kinds of blood,—venous and arterial. It is manifest, from the preceding detail, that our knowledge re- garding the precise changes effected upon the air and the blood by respiration is by no means definite. We may, however, consider the following points established. In the first place:—the air loses a part of its oxygen, and of its azote ; but this loss varies according to numerous circumstances. 2dly, It is found to have acquired carbonic acid, the quantity of which is also variable. 3dly, The bulk of the air is diminished; but the extent of this likewise differs. 4thly, The blood when it attains the left side of the heart, has a more florid colour. 5thly, This change appears to be caused by the contact of oxygen. Gthly, The blood in the lungs gets rid of a quantity of carbonic acid. 7thly, The oxygen taken in is more than necessary for the carbonic acid formed. 8thly, The consti- tuents of the air pass directly through the coats of the pulmonary vessels, and certain portions of each are discharged or retained, according to circumstances. Lastly, A quantity of aqueous vapour, containing albumen, is discharged from the lungs, but this is a true secretion, and not a consequence of respiration.1 c. Cutaneous Respiration, fyc. A question, again, has arisen, whether any absorption and exha- lation of air, and conversion of blood from venous to arterial, take place in any other part of the body than the lungs. The reasons, urged in favour of the affirmative of this question, are ;—that, in the * Bostock's Physiology, 3d edit. p. 361 and 377, Lond. 1836. VOL. II. 12 134 RESPIRATION. lower classes of animals, the skin is manifestly the organ for the reception of air; that the mucous membrane of the lungs evidently absorbs air, and is simply a prolongation of the skin, resembling it in texture; and, lastly, that when a limited quantity of air has been placed in contact with the skin of a living animal, it has been ab- sorbed, and found to have experienced the same changes as are effected in the lungs. Mr. Cruikshank1 and Mr. Abernethyb ana- lyzed air, in which the hand or foot had been confined for a time, and detected in it a considerable quantity of carbonic acid. Jurine, having placed his arm in a cylinder hermetically closed, found, after it had remained there two hours, that oxygen had disappeared, and that 0.08 of carbonic acid had been formed. These results were confirmed by Gattoni.0 On the other hand, Drs. Priestley,' Klapp,e and Gordon/ could never perceive the least change in the air under such circumstances. Perhaps in these, as in all cases where the respectability of testimony is equal, ihe positive should be adopted rather than the negative. It is probable, however, that absorption is effected with difficulty; and that the cuticle, as we have elsewhere shown, is placed on the outer surface to obviate the bad effects which would be induced by heterogeneous gaseous, miasmatic, or other absorption. We have seen that some of the deleterious gases, as sulphuretted hydrogen, are most powerfully penetrant, and, if they could enter the surface of the body with readiness, unfortunate results might supervene. In those parts where ihe cuticle is extremely delicate, as in the lips, some con- version of the venous blood into arterial may be effected, and this may be a great cause of their florid colour. According to this view, the arterialization of the blood occurs in the lungs chiefly, owing to their formation being so admirably adapted to the pur- pose, and it is not effected in other parts, because their arrange- ment is unfavourable for such result.8 d. Effects of the Section of the Cerebral Nerves on Respiration. It remains for us to inquire into the effect produced on the lungs by the cerebral nerves distributed to them,—or rather, into what is the effect of depriving the respiratory organs of their nervous influence from the brain. The only cerebral or encephalic nerves, distributed to them, are the pneumogastric or eighth pair of Willis, which, we have seen, are sent, as their name imports, to both the lungs and the stomach. The section of these nerves early suggested * Experiments on the Insensible Perspiration, &c. Lond. 1795. See also Edwards Sur l'lnfluence des Agens Physiques, p. 12; and Hodgkin and Fisher's translation. ' b Surgical and Physiological Essays, part ii. p. 115, Lond. 1793. c Diet, des Sciences Medicales, art Peau. d Experiments and Observations on different kinds of Air, ii. 193 an(j v iqq Lond 1774. ' ' e In-myural Essay on Cuticular Absorption, p. 24, Philad. 1805. f Ellis's Inquiry into the changes of Atmospheric Air, &.c. p. 355 Edinb 1837 Sec also, Madden's Experimental Inquiry on Cutaneous Absorption, p. 'j30 Lond 1838 g Muller's Handbuch u. s. w. Baly's translation, p. 334, Lond'. 1838 ' EFFECTS -OF DIVIDING CEREBRAL NERVES. 135 itself to physiologists, but it is only in recent times that the pheno- mena resulting from it have been clearly comprehended. The ope- ration appears to have been performed as long ago as the lime of Rufus of Ephesus, and was afiervvards repeated by Chirac, Bohn, Duverney, Vieussens, Schrader, Valsalva, Morgagni, Haller, and numerous other distinguished physiologists.1 It is chiefly, however, in very recent times, and especially by the labours of Dupuytren, Duma's, De Blainville, Provencal, Legallois, Magendie, Breschet, Hastings, Broughton, Brodie, Wilson Philip, and Dr. John Reid, that the precise effects upon the respiratory and digestive functions have been appreciated.1" When the nerves are divided in a living animal, on both sides at once, the animal dies more or less promptly; at times, immediately after their division, but sometimes it lives for a few days; Magendie says never beyond three or four. The effects produced upon the voice, by the division of the pneu- mogastric nerves above the origin of the recurrents, have been referred to under another head, (vol. i. p. 413.) Such division, however, does not simply implicate the larynx, but necessarily affects the lungs, as well as the stomach. As regards the larynx, precisely the same results are produced by dividing the trunk of the pneumogastric above the origin of the recurrents, as by the division of the recurrents themselves: the muscles, whose function it is to dilate the glottis, are paralyzed; and, consequently, during inspira- tion, no dilatation takes place; whilst the constrictors, which receive their nerves from the superior laryngeal, preserve all their action, and close the glottis, at times so completely, that the animal dies immediately from suffocation. But if the division of these nerves should not induce instant death in this manner, a series of symptoms follows, considerably alike in all cases, which goon until the death of the animal. These phenomena, according to Magen- die,0 are the following:—respiration is, at first, difficult; the inspi- ratory movements are more extensive and rapid, and the animal's attention appears to be particularly directed to them; the locomo- tive movements are less frequent, and evidently fatigue; frequently the animal remains entirely at rest; the formation of arterial blood is not prevented at first, but soon, on the second day for instance, the difficulty of breathing augments, and the inspiratory efforts become gradually greater. The arterial blood has now no longer the vermilion hue which is proper to it. It is darker than it ought to be. Its temperature falls. Respiration requires the exertion of all the respiratory powers. At length, the arterial blood is almost * Haller. Element. Physiologies. b See vol. i. p. 541; Fletcher's Rudiments of Physiology, part ii. b. p. 56, Edinb. 1836; Legallois, Sur le Principe de la Vie, p. 170, Paris, 1812; Bostock's Phvsiol., edit. cit. p. 390; Ley, in Append, to Essay on Laryngismus Stridulus, p. 424, Lond. 1836; and an interesting paper entitled '•Experiirient.il Investigation into the Func- tions of the Eighth Pair of Nerves," by Dr. John Reid, in Edinb. Med. and Surg. Journ. for April, 1839. c Precis, &c. 2de. edit. ii. 355. 136 RESPIRATION like the venous, and the arteries contain but little of it; the body gradually becomes cold, and the animal dies. On opening the chest, the air-cells, the bronchi, and frequently even the trachea, are found filled by a frothy fluid, which is sometimes bloody; the substance of the lung is tumid; the divisions and even the trunk of the pulmonary artery are greatly distended with dark, almost black, blood ; and extensive effusions of serum and even of blood are found in the parenchyma of the lungs. Experiments have, likewise, shown that, in proportion as these symptoms appeared, the animals consumed less and less oxygen, and gave off a progressively dimi- nishing amount of carbonic acid.a From the phenomena that occur after the section of these nerves on both sides, it would seem to follow, that the first effect is exerted upon the tissue of the lungs, which, being deprived of the nervous influence they receive from the brain, are no longer capable of exerting their ordinary elasticity or muscularity, whichsoever it may be. Respiration, consequently, becomes difficult; the blood no longer circulates freely through the capillary vessels of the lungs; the consequence of this is, that transudation of its serous portions, and occasionally effusion of blood, owing to rupture of small vessels, takes place, filling the air-cells more or less; until, ultimately, all communication is prevented between the inspired air and the blood- vessels of the lungs, and the conversion of the venous into arterial blood is completely precluded. Death is then the inevitable and immediate consequence. The division of the nerve on one side affects merely the lung of the corresponding side; life can be continued by the action of one lung only. It is, indeed, a matter of astonishment how long some individuals have lived when the lungs have been almost wholly obstructed. Every morbid anatomist has had repeated opportuni- ties for observing, that, in cases of pulmonary consumption, for a length of time prior to dissolution, the process of respiration must have been wholly carried on by a very small portion of lung. From his experiments on this subject, Sir Astley Cooper infers, that the pneumogastric nerve is most important;—1st, in assisting in the support of the function of the lungs, by contributing to the changing of the venous into arterial blood; 2dly, in being necessary to the act of swallowing, and 3dly, in being very essential to the digestive process; whilst Dr. John Reid is of opinion, that the pul- monary branches seem to be the nerves, chiefly concerned in trans- mitting to the medulla oblongata the impressions which excite respiratory movements, and are thus principally afferent nerves; but it is possible, he adds, that they contain motor filaments also.b The experiments of Dr. Wilson Philip0 and others moreover a See Sir Astley Cooper, in Guy's Hospital Reports, part i. 468, Lond 1836 • also Dr. J. Reid, Edinb. Med. and Surg. Journ. p. 163, for Jan. 1838. b Edinb. Med. and Surg. Journ. April, 1839. c Experimental Inquiry into the Laws of the Vital Functions, &c. 2d edit. p. 223 Lond. 1818; also, Journal of Science and Arts, viii. 72; and art Galvanism in Ure's Diet, of Chemistry, 2d edit. Lond. 1823. OF ANIMALS. 137 show,—what has been more than once inculcated,—the great simi- larity between the nervous and galvanic fluids. When the state of dyspnoea was induced by the division of the pneumogastric nerves, the galvanic current was passed from one divided extremity to the other, and, in numerous cases, the dyspnoea entirely ceased. The results of these experiments induced him to try the effect of gal- vanism in cases of asthma. By transmitting its influence from the nape of the neck to the pit of the stomach, he gave decided relief in every one of twenty-two cases, four of which occurred in private practice, and eighteen in the Worcester Infirmary. Sir A. Cooper1 instituted similar experiments on the phrenic nerves. As soon as these were tied, the most determined asthma was produced ; breathing went on by means of the intercostal mus- cles ; the chest was elevated to the utmost by them; and in expira- tion the chest was as remarkably drawn in. The animals did not live an hour; but they did not die suddenly, as they do from pres- sure on the carotid and vertebral arteries. The lungs appeared healthy, but the chest contained more than its natural exhalation. He also tied the great sympathetic; but little effect was pro- duced: the animal's heart appeared to beat more quickly and feebly than usual. The animal was kept seven days, and one nerve was ulcerated through, and the other nearly so at the situa- tion of the ligatures. No particular alteration of any organ was observed, on examination. Lastly, Sir Astley tied all three nerves on each side, the pneumo- gastric, phrenic, and grand sympathetic: the animal lived little more than a quarter of an hour, and died of dyspnoea. From these experiments, he infers, that the sudden death, which he found in his experiments to take place from pressure on the sides of the neck, cannot be attributed to any injury of the nerves, but to an impediment to the due supply of blood to the great centre of nervous influence. e. Respiration of Animals. In concluding the subject of respiration, we may briefly advert to the different modes in which the process is effected in the classes of animals, and especially in birds, the respiratory organ of which constitute one of the most singular structures of the animal economy. The lungs themselves,—as in the marginal figure of the lungs, &c, of the ostrich, (Fig. 120,)—are comparatively small, and are adhe- rent to the chest,—where they seem to be placed in the intervals of the ribs. They are covered by the pleura only on their under surface, so that they are, in fact, on the outside of the cavity of the chest. A great part of the thorax, as well as of the abdomen, is occupied by membranous air-cells, into which the lungs open by considerable apertures. Besides these cells, a considerable portion a Op. cit. p. 475. 12* 138 RESPIRATION. of the skeleton forms receptacles for air, in many birds; and if we break a long bone of a bird of flight, and blow into it, the body of the bird being immersed in water, bubbles of air will escape from the bill. The object, of course, of all this, is to render the body light, and thus to faci- ,--• litate its motions. Hence the largest and most numerous bony cells are found in such birds as have the highest and most rapid flight, as the eagle. The barrels of the quills are likewise hollow, and can be filled with air, or emptied at pleasure. In addition to the uses just mentioned, these receptacles of air diminish the necessity of breathing so frequently, in the rapid and long-continued mo- tions of several birds, and in the great vocal exertions of sing- ing birds. Tlioracic and Abdominal Viscera of the Ostrich. \r\ fishes, in the place of lungS a. Heart, lodged in one great air-cell. b. The . £ J hrnnrhisv nr trills which stomacll. c. The intestines, surrounded by large We nnQ OranCMCB Or glllS, WHICH air-ceiis. d. The trachea dividing into bronchi. are placed behind the head on c, e. The lungs. 1,2,3./,/. Other great air-cells, i -i i i ,, communicating with other cells and with the each Side, and have a movable Lieftiof if mTadee°penings by"**""*"'t ill-cover. By the throat, which is connected with these organs the water is conveyed to the gills, and distributed through them: by this means, the air, contained in the water, which according to Biot, Humboldt,1 and Provencal, Configliachi, and Thomson,b is richer in oxygen than that of the atmosphere, having from 29 to 32 parts in the 100, instead of 20 or 21, comes in contact with the blood circulating through the gills. The water is afterwards dis- charged through the branchial openings,—aperturce branchiales,— and consequently, they do not expire along the same channel as they inspire. Lastly, in the insect tribe,—in the white-blooded animal,—we find the function of respiration effected altogether by the surface of the body; at least, so far as regards the reception of air, which passes into the body through apertures termed stigmata, the external 1 Memoir de la Societe PArcueil, i. 252, and ii. 400; Annals of Philosophy v. 40 ; and Richerand's Elements de Physiologie, 18eme 6dit par M Berard aine d 141 Bruxelles, 1837. ' 'v' b Dr. Thomson found that 100 cubic inches of the water of the river Clyde contained 3.113 inches of air; and that the air contained 29 per cent, of oxygen Edinb New Philosoph. Journal, xxi. 370, Edinb. 1836. ' CIRCULATION. jgg termination of trachea, or air-tubes, whose office it is to convey the air to different parts of the system. In all these cases we find precisely the same changes effected upon the inspired air, and especially, that oxygen and azote have disappeared, and that carbonic acid is contained in nearly equal bulk with the azote in the residuary air.a CHAPTER IV. CIRCULATION. The next function to be considered is that by which the products of the various absorptions, converted into arterial blood in the lungs, are distributed to every part of the body,—a function of the most important character to the physiologist, and the pathologist, and without a knowledge of which, it is impossible for the latter to comprehend the doctrine of disease. Assuming the heart to be the great central organ of the function, the circulatory fluid must set out from it, be distributed through the lungs, undergo aeration there, be sent to the opposite side of the heart, whence it is distributed to every part of the system, and be thence returned, by the veins, to the right side, from which it set out,—thus performing a complete circuit. It is not easy to ascertain the total quantity of blood, circulating in both arteries and veins. Many attempts have been instituted for this purpose, but the statements are most diversified, partly owing to the erroneous direction followed by the experimenters, but, still more, to the variation that must be perpetually occurring in the amount of fluid, according to age, sex, temperament, activity of secretion, &c. Harvey and the earlier experimenters formed their estimates, by opening the veins and arteries freely on a living ani- mal, collecting the blood that flowed, and comparing this with the weight of the body. The plan is, however, objectionable, as the whole of the blood can never be obtained in this manner, and the proportion discharged varies in different animals and circumstances. By this method, Moulins found the proportion in a sheep to be ^gd; King, in a lamb, jVh ; in a duck, -3-Vth; and in a rabbit, -g^th. From these and other observations, Harvey concluded, that the weight of the blood of an animal is to that of the whole animal as 1 to 20. a Roget's Animal and Vegetable Physiology, ii. 221, Amer. Edit.; and Tiedemann, Traite Complet de Physiologie de I'Homme, par Jourdan, p. 302, Paris, 1831, 140 CIRCULATION. Drelincourt, however, found the proportion in a dog to be nearly T'oth ; and Moor, tV0-" An animal, according to Sir Astley Cooper," generally expires, as soon as blood, equal to about TVth of the weight of the body, 13 abstracted. Thus, if it weighs sixteen ounces, the loss of an ounce of blood will be sufficient to destroy it: ten pounds will destroy a man weighing one hundred and sixty pounds; and, on examining the body, blood will still be found—in the small vessels especially—even although every facility may have been afforded for draining them. Experiments have, however, shown, that no fixed proportion of the circulating fluid x:an be indicated as necessary for the maintenance of life. In the experiments of Rosa, asphyxia occurred in young calves when from three to six pounds, or from 73d to 2V1'1 of their weight, had been abstracted, but in older ones not until they had lost from twelve to sixteen pounds, or from TVth to |th of their weight. In a lamb, asphyxia supervened on a loss of twenty-eight ounces, or 2VI1 of its weight, and in a wether, on a loss of sixty-one ounces, or jVd of its weight. Blundellc found that some dogs died after losing nine ounces, or gVth of their weight; and others withstood the abstraction of a pound, or tVUi of their weight; and Piorry affirms, that dogs can bear the loss of ^th of their weight, but if a few ounces more be drawn, they succumb. From all the experiments and observations, Burdachd concludes, that, on the average, death occurs when |ths or ^ths, of the mass of blood is lost, although he has observed it in many cases, as in haemoplysis, to supervene on the loss of ^th, and even of ^th. The following table exhibits the computations of different physio- logists, regarding the weight of the circulating fluid—arterial and venous. lbs. lbs. Harvey, } Lister, f - 8 - 10 F. Hoffmann, - - 28 Moulin s, I Abildguard, ) Blumenbach, i Lobb, V Haller, Young, - 28 to 30 - 40 Lower, } Sprengel, Muller and Burdach, 10 to 15 - 20 Hamberger, Keill, - 80 - 100e Quesnai,... - 27 Although the absolute eslimate of Hoffmann is below the truth, his proportion is probably nearly accurate. He conceives, that the weight of the blood is to that of the whole body as 1 to 5. Accord- ingly, an individual, weighing one hundred and fifty pounds, will a Haller, Elementa Physiologies, iv. 2, seq. b Principles and Practice of Surgery, p. 33, Lee's edition, Lond. 1836. c Researches Physiological and Pathological, p. 66 and 94, Lond. 1825. d Die Physiologie als Erfahrungswissenschaft, iv. 101 &. 334, Leipzig] 1832 e Haller, op. citat; and Hcrbst, Comment. Historico-critica, &c, de SanguinisQuan- titate, Gotting. 1822. 6 CIRCULATION. 141 have about thirty pounds of blood; one of two hundred pounds, forty; and so on. Of this, one-third is supposed to be contained in the arteries, and two-thirds in the veins. The estimate of Haller is, perhaps, near the truth; the arterial blood being, he conceives, to the venous, as 4 to 9. If we assume, therefore, that the whole quantity of the blood is thirty pounds in a man weighing one hun- dred and fifty pounds,—which is perhaps allowing too much,—nine pounds, at least, may be contained in the arteries, and the remainder in the veins.* The lower classes of animals differ essentially, as we shall find hereafter, in their organs of circulation: whilst in some, the appa- ratus appears to be confounded with the digestive; in others, the blood is propelled without any great central organ; and in others, again, the heart is but a single organ. In man, and in the upper classes of animals, the heart is double ;—consisting of two sides, or really of two hearts, separated from each other by a septum. In the dugong, the two ventricles are almost entirely detached from each other.b As all the blood of the body has to be emptied into this central organ, and to be subsequently sent from it; and as its flow is continuous, two ca- vities are required in each heart,—the one to receive the blood, the other to propel it. This last contracts and di- lates alternately. The cavity or cham- ber of each heart, which receives the blood, is called auricle, and the vessels that transport it thither are the veins; the cavity by which the blood is pro- iprted forwards is called vrv fricle and Heart of the Dugong. jeciea iorwaras is cauea vemncie, arm D The rjght auricle E The rjght the Vessels, along Which the blOOd IS ventricle. K. The left auricle. L. The sent, are the arteries. One of these A.^neaorta. ' epumonaryartery- hearts is entirely appropriated to the circulation of venous blood, and hence has been called the venous heart,—also the right or anterior heart, from its situation,—and the pulmonary from the pulmonary artery arising from it. The other is for the circulation of arterial blood, and is hence called the arterial heart, also the left or posterior, from its situation, and the aortic heart, because the aorta arises from it. In Fig. 122, the two hearts are separated from each other, and shown to be distinct organs in the adult, although in the subject a Good's Study of Medicine, Physiological Proem to class Hasmatica; Haller, op. citat.; Rudolphi, Grundriss der Physiol, i 40; Brandt, in art. Blut, in Encyclopad. Worterb. der Medic. Wissenschaft v. 598, Berlin, 1830; and Mr. Ancell, Lectures on the Physiol', and Pathology of the Blood, in Lond. Lancet, May 16, 1840, p. 257. b Koget's Animal and Vegetable Physiology, Amer. Edit. ii. 200, Philad. 1836. 142 CIRCULATION. The right and left Hearts, separated. they seem to form but one. Between the two, after birth, there is not the slightest commu- l The right ventricle. 0. The pulmonarv In the septum between the right and artery. left auricle, there is a superficial depression, about the size of the point of the finger, which is the vestige of the foramen ovale,—an important part of the circulatory apparatus of the foetus. The opening, through which the auricle projects its blood into the ventricle, is situate down- wards and forwards, as is seen in Fig. 124. Fig. 124. The inner surface of the proper auricle, or that which more particularly resembles the ear of a quadruped,—the remain- der being sometimes called the sinus, venosus or sinus venarum cavarum,—is distinguished by hav- ing a number of fleshy pillars in it, which, from their supposed re- semblance to the teeth of a comb, are called musculi pectinati. They are mere varieties, however, of the columnce carnece of the ven- tricles. The right ventricle or pulmo- nary ventricle is situate in the an- terior part of the heart; the base and apex corresponding to those of the heart. Its cavity is generally greater than that of the left side, and its parietes not so thick, owing to their merely having to force the blood through the lungs. It communicates with the auricle by the auriculo-ventricular opening—the ostium venosum; and the Section of the Pulmonic Heart. Right auricle. B. Right ventricle. C Pul- monary artery. 144 CIRCULATION. only other opening into it is that which communicates with the inte- rior of the pulmonary artery. The opening, between the auricle and ventricle, is furnished with a tripartite valve, called tricuspid ot triglochin; and the pulmonary artery has three others, called sig- moid or semilunar. From the whole edge of the tricuspid valve, next the apex of the heart, small, round, tendinous cords, called chordae tendinece, are sent off, which are fixed, as represented in Fig. 124, to the extremities of a few strong columnce carnece. These tendinous cords are of such a length as to allow the valve to be laid against the sides of the ventricle, in the dilated state of that organ, and to admit of its being pushed back by the blood, until a nearly complete septum is formed, during the contraction of the ventricle. The semilunar or sigmoid valves are three in number, situate around the artery. When these fall together, there must necessa- rily be a space left between them. To obviate the inconvenience, that would result from the existence of such a free space, a small granular body is attached to the middle of the margin of each valve; and, these coming together, as at A, Fig. 125, when the valves are shut down, complete the dia- Fig. 125. phragm, and prevent any blood from pass- ing back to the heart. These small bodies are termed, from their reputed discoverer, corpuscula Arantii, and also corpuscula Mor- gagnii; or, from their resemblance to the seed of the sesamum, corpuscula sesamoi- dea. The valves, when shut, are concave towards the lungs, and convex towards the ventricle. Immediately above them the artery bulges out, forming three sacculi or semilunar valves dosed. sinuses, called sinuses of Valsalva. These are often said to be partly formed by the pressure of the blood upon the sides of the vessels. The structure is doubtless ordained, and is admirably adapted for a specific pur- pose, namely, to allow the free edges of the valves to be readily caught by the refluent blood, and thus to facilitate their closure. Within the right ventricle, and especially towards the apex of the heart, many strong eminences are seen, which are called columnce carnece, (Fig. 124.) These run in different directions, but the strongest of them longitudinally with respect to the ventricle. They are of various sizes, and form a beautifully reticulated texture. Their chief use probably is, to strengthen the ventricle and prevent it from being over-distended; in addition to which they may tend to mix the different products of absorption. The corporeal, left, aortic or systemic heart,—called also the heart of red blood,—has likewise an auricle and a ventricle. The left auricle is considerably thicker and stronger but smaller than the right; and is likewise divided into sinus venosus and proper auricle, which form a common cavity. The columns, in the latter, are like CIRCULATORY APPARATUS. 145 those of the right auricle, but less distinct. From the under part of the auricle, a circular passage, termed ostium arteriosum or auricu- lar orifice leads to the posterior part of the base of the cavity of the left ventricle. The left auricle receives the blood from the pul- monary veins. The left or aortic ventricle is situate at the posterior and left part of the heart. Its sides are three times thicker and stronger than those of the right ventricle, to permit the much greater force which it has to exert; for, whilst the right ventricle merely sends its blood to the lungs, the left ventricle transmits it to every part of the body. It is narrower and rounder, but considerably longer, than the right ventricle, and forms the apex of the heart. The internal surface of this ventricle has the same general appear- ance as the other, but differs from it in having its columnce carneee larger, more numerous, firmer, and stronger. In the aperture of communication with the corresponding auricle, there is here, as in the opposite side of the heart, a ring or zone, from which a valve, essentially like the tricuspid, goes off. It is stronger, however, and divided into two principal portions only: the chordae tendinre are also stronger and more numerous. This valve has been termed mitral, from some supposed resemblance to a bishop's mitre. At the fore and right side of the mitral valve, and behind the commencement of the pulmonary artery, a round open- ing exists, which is the mouth of the aorta. Here are three semilu- nar valves, with their corpuscula Arantii, exactly like those of the pulmonary artery, but a little stronger; and, on the outer side of the semilunar valves, are the sinuses of Valsalva, a little more pro- minent than those of the pulmonary artery. The structure of the two hearts is the same. A serous membrane covers both, which is an extension of the inner membrane of the pericardium. The substance of the heart is essentially muscular. The fibres run in different directions, longitudinally and transversely, but most of them obliquely. Many pass over the point, from one heart to the other, and all are so involved as to render it difficult to unravel them. The cavities are lined by a thin membrane, the endocardium, which differs somewhat in the two hearts;—being in one a prolon- gation of the inner coat of the aorta, and in the other of the venae cavas. On this account, the inner coat of the left heart is but slightly extensible, more easily ruptured, and considerably disposed to ossify; that of the right heart, on the other hand, is very exten- sible, not readily ruptured, and but little liable to ossify. M. Des- champs" has recently described a membrane which is situate between the endocardium and the cellular tissue that lines the mus- cular structure at its inner surface, and belongs essentially to the elastic fibrous tissue. The tissue of the heart is supplied with blood by the cardiac or coronary arteries—the first division of the aorta; and * Gazette Medicale de Paris, No. 10, and Encyclographie des Sciences Medicales, Avril, 1840, p. 281. VOL. II. 13 146 CIRCULATION. their blood is conveyed back to the right auricle by the coronary veins. The nerves, which follow the ramifications of the coronary arteries, proceed chiefly from a plexus, formed by the pneumo- gastric nerves, and great sympathetic. In both hearts, the auricles are much thinner and more capacious than the ventricles; but they are themselves much alike in structure and size. The observation, that the right ventricle is larger than the left, is as old as Hippocrates, and has been attempted to be accounted for in various ways. Some have ascribed it to original conformation; others to the blood being cooled in its passage through the lung, and therefore occupying a smaller space when it reaches the left side of the heart. "Haller* and Meckel1- assert that it is dependent upon the kind of death;0 that if the right ventricle is usually more capacious, it is owing to the lung being one of the organs that yields first, thus occasioning accumulation of blood in the right cavities of the heart; and they state that they succeeded, in their experiments, in rendering either one or the other of the ven- tricles more capacious, according as the cause of death arrested first the circulation in the lung or in the aorta; but the experiments of Legallois,d and Seilere especially of the former,—with mercury poured into the cavities,—on dogs, cats, Guinea-pigs, rabbits, in the adult, the child, and the still-born foetus, have shown, that, except in the foetus, the right ventricle is more capacious, whether death has been produced by suffocation, in which the blood is accumulated in the right side of the heart, or by hemorrhage; and Legalloisf thinks that the difference is owing to the left ventricle being more muscular, and, therefore, returning more upon itself.8 The two hearts, united together by a median septum, form, then, one organ, which is situate in the middle of the chest, (see Fig. 115,) between the lungs, and consequently in the most fixed part of the thorax. Figure 125* is reduced from one carefully made from nature by Dr. Pennock.h It represents the normal position of the heart and great vessels. According to Carus,' the weight of the heart compared with that of the body is as 1 to 160. M. J. Weber* found the proportion, in one case, as 1 to 150; Dr. Clendinningk that of the male 1 to 160; that of the female 1 to 150; and Laennec considered the organ to be of a healthy size when equal to the fist of the individual. Cruveilhier estimates the mean weight at six or seven ounces. a Element. Physiol, iv. 3. 3. b Handbuch der Menschlichen Anatomie, Halle, 1817, s. 46; and the translation from the French version by Dr. Doane, Philad. 1832. c Clendinning, Report to the British Association, Lond. Med. Gaz. Nov. 13, 1840. d Diet des Sciences Medicales, v. 440. e Art. Herz, in Anat. Physiol. Real Worterb. iv. 32, Leipz. 1821. f CEuvres, Paris, 1824. " e Burdach, Physiologie, u. s. w., iv. 214. h Medical Examiner, April 4, 1840. ' Introduction to Comp. Anat. translated by R. T. Gore, Lond. 1827. J Hildebrandt's Handbuch der Anatomie, von E. H. Weber, Braunschweig 1831 Band. iii. s. 125. s' k Journal of the Statistical Society of London, July, 1838. CIRCULATORY ORGANS. 147 Bouillaud1 weighed the hearts of thirteen subjects, in whom, from the general habit, the previous state of health, and the mode of death, there was every reason to believe they were in the natural state. The mean was eight ounces and three drachms.b From all his data he is led to fix the mean weight of the heart, in the adult, from the 25th to the 60th year, at from 8 to 9 ounces. Fig. 125.* P Outline of Sternum. C.C. Clavicles. 1, 2, 3, 4, 5, 6, &r, The. ribs. 1'. 2'. 3', 4'. 5/ 6,' &c. Carti la"es of the ribs. 4". Right and left nipples, a. Right ventricle, ft. Left ventricle, c. Septum between the ventricles, d. Right auricle, e. Left auricle. /. The aorta. /'. Needle passing through aortic valves, g. Pulmonary arlerv g'■ Needle passing thronsh valves of pulmonary artery. A. Vena c;iva descenders, i. Line of direction of mitral valve; the dottPd portion posterior to the right ventricle. >'• Needle passed into the mitral valve at its extreme left. k. Line of tri- cuspid valve, o. Trachea. Dr. Clendinning carefully examined nearly four hundred hearts of persons of both sexes, and of all ages above puberty. The result was about nine ounces avoirdupois. The dimensions of the heart, according to Lobstein and Bouil- laud, are as follows: » Traite Clinique des Maladies du Occur, &c. Paris, 1835. b See, also, Dr. Gross, Elements of Pathological Anatomy, ii. 124, Boston, 1839. 148 CIRCULATION. Weight of heart, 9 to 10 ounces; length from base to apex, 5 inches 6 lines; breadth at the base, 3 inches; thickness of walls of left ventricle, 7 lines; do. Fig. 126. at a finger's breadth above the apex, 4 lines; thickness of walls of right ventricle, 2i lines; do. at apex, h a line; thickness of right au- ricle, 1 line ; do. of left auri- cle, ^ a line. It" need scarcely, how- ever, be said, that the weight and dimensions of the organ must vary according to the age, sex, &c. of the indi- vidual. M. Bizof found, that the influence of stature on its size was slight; and not such as might have been expected a priori; as in individuals of the male sex above sixty inches, and in females above fifty-five inches in height, the mean dimensions of the organ, especially its breadth, were less than in persons of lower stature. He found the width of the shoulders to furnish a better proportionate stan- 1. Right auricle. 2. Right ventricle. 3. Left auricle, dard of its measures,---the 4. Left ventricle. 5. Pulmonary aitery. 6. Its left f]j(,tanf.f, LptwPPn thp arm branch, which subdivides and passes to the left lung, ui&iduue UUlWtLU Wie dCIO- 7. Commencement of the right branch, which afterwards filial Doint of the clavicles subdivides into: 7, 7, 7. Branches to the right lung. i i i i i i i i' 8, 8. Aorta. 9. Vena cava descendens. JO. Vena cava and the length and breadth ascenrtens. 11. Apex of the heart, formed by left ventri- r .1 L__ f ■ • • de. 12, 12, 12, 12. Pulmonary veins proceeding to left OI lne neai t increasing in auricle. 13, 14. Coronary artery. tolerably regular ratio. The heart is surrounded by its proper capsule, called the pericar- dium—a fibro-serous membrane, which is composed of two layers. The outermost of these is fibrous, semi-transparent, and inelastic; strongly resembling the dura mater in its texture. Its thickness is greater at the sides than below, where it rests upon the diaphragm; or than above, where it passes along the great vessels which com- municate with the heart. The inner layer is of a serous character, and lines the outer, giving the polish to its cardiac surface; it is then reflected over the heart, and adheres to it by cellular substance. Like other serous membranes, it secretes a fluid, which is termed liquor pericardii, to lubricate the surface of the heart. This Heart in situ. 2. Right ventricle. * M^moires de la Societe Medicale d'Observation de Paris, torn, lere, Paris, 1836. CIRCULATORY APPARATUS. 149 fluid is always found in greater or less quantity after death; and a question has arisen regarding the amount that must be considered morbid. This must obviously vary according to circumstances. It seldom, however, in the healthy condition, is above a tea-spoonful. When its quantity is augmented, along with inflammation of the membrane, the disease hydropericarditis exists. The great use of the pericardium is probably to keep the heart constantly moist by the exhalation effected from it; and, also, to restrain the movements of the heart, which, under the influence of the emotions, sometimes leaps inordinately. If the pericardium be divided in a living animal, the heart is found to bound, as it were, from its ordinary position; and hence the expression—"leaping of the heart," during emotion—is physiologically accurate. b. Arteries. The arteries are solid, elastic tubes, which arise, by a single trunk, from the ventricle of each heart, and gradually divide and subdivide, until they are lost in the capillary system. The large artery, which arises from the left ventricle, and conducts the blood to every part of the body,—even to the lungs, so far as regards their nutrition,—is, as wre have seen, the aorta, and that, which arises from the right ventricle and conveys the venous blood to the lungs, for aeration, is the pulmonary artery. Neither the one nor the other is a continuation of the proper tissue of the ventricles; the inner membrane is alone continuous, the muscular structure of the heart being united to the fibrous coat of the arteries, by means of an intermediate fibrous tissue. The aorta, as soon as it quits the left ventricle, passes beneath the pulmonary artery, is entirely concealed by it, and ascends to form a curvature with the convexity upwards, the summit of which rises to within three quarters of an inch or an inch of the superior edge of the sternum. This great curvature is called the cross or arch of the aorta. The vessel then passes downwards, from the top of the thorax to nearly as far as the sacrum, where it divides into two trunks, one of which proceeds to each lower extremity. In the whole of this course, it lies close to the spine, and gives off the va- rious branches that convey arterial blood to the different parts of the body. Of the immense multitude of these ramifications, an idea may be formed, when we reflect, that the finest pointed needle cannot be run into any part of the surface of the body, without blood,—probably both arterial and venous,—flowing. The larger arteries are all situate deeply, and are thus remote from external injury. They communicate freely with each other, and their anastomoses are more frequent as the arteries become smaller and farther from the heart. At their final terminations, they communicate with the veins and the lymphatics. The branches of the aorta, when taken collectively, are of greater capacity than the parent trunk, and this inequality goes on augment- 13* 150 CIRCULATION. ing; so that the ultimate divisions of an artery are of a much greater capacity than the trunk of the vessel. Hence, the arterial system has been considered to represent, in the aggregate, a cone, whose apex is at the heart, and the base in the organs. As all the minute arterial ramifications are not visible, it is obvi- ously impracticable to discover the ratio between their united capa- city and that of the aorta at its origin; yet the problem has been attempted. Keill, by experiments made upon an injected subject, considered it to be as 44507 to 1. J. C. A. Helvetius and Sylva as 500 to 1. Senac estimated, not their capacities but their diameters, and he conceived the ratio of these to be as 118,490 to 90,000; and George Martine affirmed, that the calibre of a parent arterial trunk is equal to the cube root of the united diameters of the branches.1 The pulmonary artery strongly resembles the aorta. Its dis- tribution has been already described as a part of the respiratory organs, (page 92.) The arteries are composed of different coats in superposition, respecting the number of which anatomists have not been entirely of accord. Some have admitted five, others four, but at the present day, three only are received;—first, an external or cellular, called also nervous, and cartilaginous by Vesalius, and tendinous by Heis- ter, which is formed of condensed cellular substance, and has con- siderable strength and elasticity, so that if a ligature be applied tightly round the vessel, the middle and internal coats may be com- pletely cut through, whilst the outer coat may remain entire. Scarpa is not disposed to admit this as one of the coats. He considers that it is only an exterior envelope, to retain the vessel in situ. The next coat is the middle, muscular or proper coat, the cha- racter of which has been the subject of much discussion. It is com- posed of yellow, circular fibres, which do not appear individually to pass entirely around the vessel. This coat was, at one time, almost universally believed to be muscular. Such was the opinion of Hun- ter;1' and hence the muscularity of the arteries was regarded as an agent in the circulation. Careful examination does not, however, exhibit the characters of the muscular tissue. The latter is soft, extensible, contractile, and of a red colour; the arterial tunic is firm, solid, elastic, easily ruptured, and of a yellow colour. Henlec ad- vances the. opinion, that its structure is intermediate between cel- lular and muscular tissue; its microscopic elements being broad and very flat, slightly granulated fibres or bands, which lie in rings around the internal membrane, and are about 0.003 lines in dia- meter. These with a system or network of dark streaks con- stitute the middle coat of the artery. Nysten,d Magendie,e and Miillerf applied the galvanic stimulus to it, but without effect; and » Haller, Elementa Physiologic, torn. iv. b On the Blood, p. 124, Lond. 1794. « Casper's Wochenschrift, May 23,1840, and Brit, and For. Med. Rev. Oct. 1840. p. 551. d Recherches de Physiologie, &c. p. 325, Paris, 1811. « Precis, 2d edit. ii. 387, Paris, 1825. { Handbuch der Physiologie, Baly's translation, p. 205, Lond. 1838. CIRCULATORY APPARATUS. 151 it is known, that this is the most sensible test of irritability. The middle coat appears to be a tissue of a peculiar character, the base of which is formed by the tissu jaune, or yellow tissue of the later comparative anatomists. It is proper to remark, that the heart also seems equally unsusceptible of the galvanic stimulus; or at least is not affected by it like the voluntary muscles. In the cases of two executed criminals, which we had opportunity of observ- ing, although all degrees of galvanism were applied, half an hour after the drop fell, no motion whatever was perceptible; yet the voluntary muscles contracted perceptibly, and continued to do so for an hour and a half after execution. The same fact is recorded in the galvanic experiments of Dr. Ure, detailed in another part of this work, (vol. i. p. 362,) and is attested by Bichat, Treviranus and others. Humboldt, Pfaff, J. F. Meckel, Wedemeyer, and J. Muller, however, affirm the contrary. The last observer states,1 that with a single pair of plates he excited contractions not only in a frog's hearCwhich had ceased to beat, but also in that of a dog, under similar circumstances. Into the subject of the cause of the heart's action, we shall, however, inquire presently. Miillerb suggests, that in the capability to contract under the in- fluence of cold as exhibited in the experiments of Schwann, referred to hereafter, the contractile tissue of the arteries resembles that of the dartos, and that which is found in many parts of the skin, as about the nipple and follicles, although the physical characters of the latter are so different from elastic- tissue. The third or inner coat is smooth and polished, and is a continua- tion of the membrane which lines the ventricles. It resembles the serous membranes, and is lubricated by a kind of serous exhala- tion.0 The arteries receive the constituents that belong to every living part,—arteries, veins, lymphatics, and nerves. The arteries pro- ceed not from the vessels themselves, which they nourish, but from adjacent trunks, as we have remarked of the vasa vasorum, to which class they really belong. The nerves proceed from the great sympathetic, form plexuses around the vessels, and accompany them through all their ramifications. By some anatomists, the arteries of the head, neck, thorax and abdomen, are conceived to be supplied from the great sympathetic, whilst those of the extremi- ties are supplied from the nerves of the spinal marrow. It is pro- bable, however, that more accurate discrimination might trace the dispersion of the twigs of the great nervous system of involuntary motion on all these vessels. The organization of the arteries renders them very tough and extremely elastic, both of which qualities are necessary to enable them to withstand the impulse of the blood sent from the heart, and * Handbuch, u. s. w. translation, p. 205. i> Arehiv. fur 1836, and Lond. Med. Gazette, May, 1837. c For some speculations as to the agency of this secretion in the production of the buffy state of the blood, &c, see M. Romain Gcrardin, in Journal des Connaisances Medico-Chirurgicales, Mars, 1836. 152 CIRCULATION. to react upon the fluid so as to influence its course. It is, likewise, by virtue of this structure, that the parietes retain their form in the dead body,—one of the points that distinguish them from the veins. The vitality of the arteries is inconsiderable. Hence their diseases are by no means numerous or frequent; an important fact, seeing that their functions are eminent, and their activity in- cessant. c. Intermediate or Capillary System. The capillary or intermediate vessels are the vessels of extreme minuteness, by some considered to be formed by the termination of the arteries and the commencement of the veins; by others to be a distinct set of vessels. This system forms a plexus, which is distributed over every part of the body, and constitutes, in the aggregate, what is meant by the capillary system. It admits of two great divisions, one of which is situate at the termination of the branches given off from the aorta, and is called the general capillary system; the other at the termination of the branches of the pulmo- nary artery,—the pulmonic capillary system. Although the capillary system of man does not admit of detection by the unaided sight, its existence is evidenced by the microscope;" by injections, which can develope it artificially in almost every organ; by the application of excitants, and by inflammation. The parietes of the vessels frequently cannot be distinguished from the substance of the organs;—the colour of the blood, or the matter of the injection alone indicating their course. In some parts, these vessels are so minute as not to admit the red particles of the blood, whilst, in others, the red particles always circulate. This diversity has given rise to the distinction of the capillaries into red and white. There are certain textures, again, which receive neither the one nor the other,—the corneous and epidermous, for example. The ancients were of opinion, that the arteries and veins are separated by an intermediate substance, consisting of some fluid effused from the blood, and which they called in consequence, paren- chymal The notion is, indeed, still entertained, and is supported by microscopical observations. In the examination of delicate and transparent tissues, currents of moving globules are seen with many spaces of apparently solid substances, resembling small islets, sur- rounded by an agitated fluid. If it be irritated, by thrusting a fine needle into it, the motion of the globules becomes more rapid, new currents arise where none were previously perceptible, and the whole becomes a mass of moving particles, the general direction of which tends towards the points of irritation. But although a part of the apparatus of intermediate circulation may be arranged, as we shall see presently, in this manner, there are reasons for°he belief, « See Berres, in Magendie on the Blood, Bell's Select Medical Library Edit d 170 Philad. 1839. ' P- - t» Galen., Adminis,trat. Anatom. vi. 2. CIRCULATORY APPARATUS. 153 that a more direct communication between the arteries and the veins exists also. The substance of an injection passes from one set of vessels into the other without any evidence of intermediate extrava- sation. The blood has been seen, too, passing in living animals, directly from the arteries into the veins. Leeuenhoek1 and Mal- pighi,b on examining the swim-bladders, gills, and tails of fishes, the mesentery of frogs, &c.—which are transparent,—saw this distinctly; and the fact has been proved by the observations of Cowper, Che- selden, Hales, Spallanzani, Thomson, Cuvier, Configliachi, Rus- coni, Dbllinger, Carus, and others.0 The artery and vein termi- nate in two different ways;—at times, after the artery has become extremely minute, by sending off numerous lateral branches, as Haller states he noticed in the swim-bladders of fishes; at others, by pro- ceeding parallel to each other, and communicating by a multitude of transverse branches. This communication takes place between both the red and the white capillaries and their corresponding veins. The capillary vessels have been esteemed, by some, to belong chiefly to the arteries, the venous radicles not arising almost imper- ceptibly from the capillary system, as the arteries terminate in it, but having a marked size at the part where they quit this system, which strikingly contrasts writh the excessive tenuity of the capillary arterial vessels, whilst between the capillary system and the arteries, there is no distinct line of demarcation. The opinion of Bichat'' was, that this system is entirely independent of both arteries and veins; and Autenrieth6 imagined, that the minute arteries unite to form trunks, which again divide before communicating with the veins, so as to represent a system analogous to that of the vena portse. The experiments of Dr. Marshall Hall/on the batrachia, which were performed with signal care, led him to the following conclusions, which agree with those of Bichat, so far as regards the independent existence of a capillary system. The minute vessels, he says, may be considered as arterial, so long as they continue to divide and subdivide into smaller and smaller branches. The minute veins are the vessels that gradually enlarge from the suc- cessive addition of small roots. The true capillary vessels are distinct from these. They do not become smaller by subdivision, or larger by conjunction, but they are characterized by continual and successive union and division, or anastomoses, whilst they retain a nearly uniform diameter. The last branches of the arterial system, and the first root of the venous, Dr. Hall remarks, may be deno- minated minute, but the term "capillary" must be reserved for, and appropriated to, vessels of a distinct character and order, and of an » Select Works, containing his Microscopical Discoveries, by Samuel Hooke, p. 90, Lond. 1778. b Epist. de Pulmonibus, 1661, and ILiller, Element. Physiol. c Tiedemann's Traite de Physiol, trad, par Jourdan, p. 345, Paris, 1831. d Anatomie Generale, torn. i. e Physiologie, ii. 138. f A Critical and Experimental Essay on the Circulation, &c. Lond. 1830 ; Amer. Edit. Philad. 1835. 154 CIRCULATION. intermediate station, carrying red globules, and perfectly visible by means of the microscope. The capillary arteries are distinct in structure—as we shall see they are in office—from the larger arteries. All the coats of these minute vessels diminish in thickness and strength, as the tubes lessen in size, but more especially the middle coat, which, according to Wedemeyer,8 may still be distinguished by its colour in the trans- verse section of any vessels whose calibre is no less than the tenth of a line; but entirely disappears in vessels too small to receive the wave of blood in a manifest jet. But while the coats diminish, the nervous filaments, distributed to them, increase; the smaller and thinner the capillary, the greater the proportionate quantity of its nervous matter. The coats of the capillaries, becoming successively thinner and thinner, at length disappear altogether, and the vessels- many of them at least—terminate in membraneless canals formed in the substance of the tissues. The blood is contained—according to Wedemeyer, Gruithuisen,b Dollinger,c Carus,d and others,e in the different tissues, in channels, which it forms in them; even under the microscope, the stream is seen to work out for itself, easily and rapidly, a new passage in the tissues, which it penetrates, and it seems certain, that in the figura venosa of the egg, the blood is not surrounded by vascular parietes/ Of these fine capillaries,—the diameter of which, in parts finely injected, varies from the ToVoth to the -joVoth. and the Toloom °f an inch,s and even more,h—some, according to Wedemeyer, commu- nicate with veins. In the others, there are no visible openings or pores in the sides or ends, by which the blood can be extravasated, preparatory to its being imbibed by the veins. There is nowhere apparent a sudden passage of the arterial into the venous stream; no abrupt boundary between the division of the two systems. The arterial streamlet winds through long routes before it assumes the nature, and takes the direction of a venous streamlet. The ultimate capillary rarely passes from a large arterial into a large venous branch. Many speculations have, however, been indulged, regard- ing the mode in which the vascular extremities of the capillary system are arranged.1 Bichat regarded it as a vast reservoir, a TJntersuchungen tiber den Kreislauf des Bluts, u. s. w. Hannover, 1828, s. 180; and Meckel's Arehiv. 1828. b Medicinisch-chirurgisch. Zeitung, s. 312, Salzburg, 1822; Organozoonomie, Mun- chen, 1811; and Beitrage zur Physiognosie und Eautognosie, Milnchen, 1812. c Was ist Absonderung? u. s. w. Wurzburg, 1819; Denkschrift der Miinchner Aka- demie, 1818-1820, vii. 169; Meckel's Arehiv. vi. 186, Hal. 1820; and Journal des Progr6s, ix. d Arehiv. iv. 413, Hal. 1818; Blutumlauf in den Larven, u. s. w. p. 12, Leipz. 1827; and Tiedemann, loc. citat. ° Burdaeh, op. cit. iv. 191. f J. Mailer's Handbuch, u. s. w. Baly's translation, p. 216; and Geddings, art. Arteries, in American Cyclopedia of Practical Medicine, ii. 305, Philad. 1836. e Mailer, op. cit. p. 211. h Krause, in Muller's Arehiv. Heft. 1,1837; and Brit, and For. Med. Rev. July, 1838, p. 218. ' See, on this subject, Wilbrand, Physiologie des Menschen, s. 152, Giessen, 1815. PHYSIOLOGY OF THE CIRCULATION. 155 whence originate, besides veins, vessels of a particular order, whose office it is to pour out, by their free extremity, the materials of nutrition,—vessels, which had been previously imagined by Boer- haave, and are commonly known under the appellation of exhalants. Mascagnia supposed that the final arterial terminations are pierced, towards their point of junction with the veins, by lateral pores, through which the secreted matters transude;—but these points will farther engage attention under the heads of Nutrition, and Secretion. d. Veins. The veins have already been described under Venous Absorption. 2. PHYSIOLOGY OF THE CIRCULATION. The blood, contained in the circulatory apparatus, is in constant motion. The venous blood, brought from every part of the body, is emptied into the right auricle; from the right auricle it passes into the corresponding ventricle; the latter projects it into the pulmonary artery, by which it is conveyed to the lungs, passing through the capillary system into the pulmonary veins. These convey it to the left auricle; from the left auricle it enters the corresponding ven- tricle ; and the left ventricle sends it into the aorta, along which it passes to the different organs and tissues of the body, through the general intermediate or capillary system, which communicates with the veins: these last vessels return the blood to the part whence it set out. This entire circuit includes both the lesser and the greater circulation. It was not until the commencement of the seventeenth century, that any precise ideas were entertained regarding the general cir- culation. In antiquity, the most erroneous notions prevailed; the arteries being generally looked upon as tubes for the conveyance of some aerial fluid to, and from, the heart, whilst the veins conducted the blood, but whither or for what precise purpose was not under- stood. The names, given to the principal arterial vessel—the aorta —and to the arteries, sufficiently show the functions originally ascribed to them, both being derived from the Greek, ewip, « air," and T^ipsiv, «to keep;" and this is farther confirmed by the fact, that the trachea or windpipe was originally termed an artery,—the apnjpia ■rpaxeia of the Greeks,—the aspera arteria of the Latin writers. In the time of Galen, however, the arteries were known to contain blood; and he seems to have had some notions of a circulation. He remarks, that the chyle, the product of digestion, is collected by the meseraic veins and carried to the liver, where it is con- verted into blood; the supra-hepatic veins then convey it to the pulmonary heart; thence it proceeds in part to the lungs, and the » Vasor. Lymph. Corpor. Human. Histor., Sen. 1817; and Prodromo della Grande Anatomie, Firenz. 1819. 156 CIRCULATION. remainder to the rest of the body, passing through the median septum of the auricles and ventricles. This limited knowledge of the circulation continued through the whole of the middle ages; the functions of the veins being universally misapprehended; and the general notion being, that they also convey blood from the heart to the organs; from the centre to the circumference^ It was not until after the middle of the sixteenth century, that the lesser circulation, or that through the lungs, was comprehended, by the labours of Michael Servetus*—who fell a victim to the persecution and intole- rance of Calvin,—and of Andrew Caesalpinus, and Realdus Colum- bus. It has, indeed, been imagined, that they possessed some notion of the greater circulation. However this may have been, all nations unite in awarding to Harvey the merit, if not of entire originality, of at least of having first clearly described it. The honour of the discovery is, therefore, his; and by it his name has been ren- dered immortal, for its importance to the physiology and pathology of the animal fabric is overwhelming. How vague and inaccurate must have been the notions of the earlier pathologists regarding the doctrine of acute diseases, in which the circulation is always largely affected,—diseases, which, according to the estimate of some writers, constitute two-thirds of the morbid states to which man- kind are liable. It was in the year 1619, that Harvey attained a full knowledge of the circulation; but his discovery was not pro- mulgated until the year 1628; in a tract, to which the merit of clearness, perspicuity and demonstration has been awarded by all.b Yet so strong is the force of prejudice, and so difficult is it to dis- card preconceived notions, that it was remarked, according to Hume,c that no physician in Europe, who had reached forty years of age, ever, to the end of his existence, adopted Harvey's doctrine of the circulation; and Harvey's practice in London diminished extremely for a tirrie from the reproach drawn upon him by that great and signal discovery.*1 Of the truth of the course of the blood, as established by Harvey, we have numerous and incontestable evidences, which it may now be almost a work of supererogation to adduce. Of these the fol- lowing are some of the most striking. First. If we open the chest of a living animal, we find the heart alternately dilating and con- tracting so as manifestly to receive and expel the blood in reciprocal succession. Secondly. The valves of the heart, and of the great arteries, which arise from the ventricles* are so arranged as to allow a See the unnoticed theories of Servetus, by Geo. Sigmond, M. D., Lond. 1823; Hecker, Lehre vom Kreislauf von Harvey, Berlin, 1831; Haller. Element. Physiol, iv. 4, 17; Martine, Edinb. Med. Essays, ii. 67; SprengePs Hist, de Medecine, par Jourdan, torn. iv.; Dr. J. R. Coxe, Inquiry into the Claims of Dr. W. Harvey to the Discovery of the Circulation, &c, Philad, 1834; and Gerdy, in art. Circulation, Diction, de Medecine, 2de edit. viii. 68, Paris, 1834. b Exercitat. Anatom. de Moth Cordis et Sanguinis, Francof, 1628, Glasguae, 1751. c History of England, chap. lxii. d See, also, Purkinje, in art. Circulatio Sanguinis, in Encyclop. Worterb. der Medicin. Wissenschaft. vii. 695, Berlin, 1831. PHYSIOLOGY OF THE CIRCULATION. 157 the blood to flow in one direction, and not in another; and the same may be said of those veins, which are directed towards the heart. The tricuspid valve permits the blood to flow only from the right auricle into the corresponding ventricle; the sigmoid valves admit it to enter the pulmonary artery, but not to return ; and, as there is, in the adult, no immediate communication between the right and left sides of the heart, the blood must pass along the pulmonary artery and by the pulmonary veins to the left auricle. The mitral valve, again, is so situate, that the blood can only pass in one direction from auricle to ventricle; and, at the mouth of the aorta, the same valvular arrangement exists, as at the mouth of the pulmonary artery, permitting the blood to proceed along the artery, but pre- venting its reflux. Thirdly. If an artery and a vein be wounded, the blood will be observed to flow from the part of the vessel nearest the heart in the case of the artery; from the other extre- mity in that of a vein. The ordinary operation of blood-letting at the flexure of the arm affords us an elucidation of this. The bandage is applied above the elbow, for the purpose of compress- ing the superficial veins, but not so tightly as to compress, also, the deep-seated artery. The blood passes along the artery to the extremity of the fingers, and returns by the veins, but its progress back to the heart by the subcutaneous veins being prevented by the ligature, they become turgid; and, if a puncture be made, the blood flows freely. If, however, the ligature be applied so forcibly as to compress the main artery, the blood no longer flows to the extremity of the fingers; there is none, consequently, to be returned by the veins; they do not rise properly; and if a punc- ture be made no blood flows. This is not an unfrequent cause of the failure of an inexperienced phlebotomist. If the bandage, under such circumstances, be slackened, the blood will resume its course along the artery, and a copious stream will issue from the orifice, which did not previously transmit a drop. This operation, then, exhibits the fact of the flow of blood along the arteries from the heart, and of its return by the veins. From what has been said, too, it will be obvious, that if a ligature be applied to both vessels, the artery will become turgid above the ligature, the vein below it. Fourthly. The microscopical experiments of Leeuenhoek, Malpighi, Spallanzani, and others, have exhibited to the eye the passage of the blood in successive waves by the arteries towards the veins, and its return by the latter. Lastly. The fact is farther demon- strated by the effects of transfusion of blood, and of the injection of substances into the vessels; both of which operations will be alluded to in another place.8 In tracing the physiological action of the different parts of the circulatory apparatus, we shall follow the order observed in the anatomical sketch; and describe, in succession, the circulation in the heart, in the arteries, in the capillary vessels, and in the veins ; 1 Bostock's Physiology, 3d edit. p. 213, Lond. 1836. VOL. II. 14 158 CIRCULATION on all of which points there has been much interesting diversity of opinion, and much room for ingenious speculation, and for farther improvement. a. Circidation in the Heart. It has been already observed, that when the heart of a living animal is exposed, it is remarked to undergo alternate contraction and dilatation. The mode, in which the circulation through the heart is accomplished, is generally considered to be as follows:— the blood is received into the two auricles at the same time, and is transmitted into the two great arteries synchronously. In order that the heart shall receive blood, it is necessary that the auricle should be dilated. This movement is partly, perhaps, effected by virtue of the elasticity which it possesses in its structure. Let us suppose it to be once filled ; the stimulus of the blood excites it to contraction, and the blood is thus sent into the corresponding ventricle. As soon, however, as it has emptied itself, the stimulus is withdrawn; and, by virtue of its elasticity, it returns to the state in which it was prior to contraction. An approach to a vacuum is thus formed in the cavity, and the blood is solicited tow-ards it from the veins, until it is again filled and its contraction is renewed. When the right auricle contracts there are four channels by which the blood might be presumed to pass from it,—the two terminations of the vense cava?, the coronary vein, and the auriculo-ventricular communication. The constant flow of blood from every part of the body prevents it from readily returning by the venas cava?, whilst the small quantity, which, under other circumstances, might have entered the coronary vein, is prevented by its valve. To the flow of the blood through the aperture into the ventricle, which is in a state of dilatation, there is no obstacle, and accordingly it takes this course, raising the tricuspid valves. It may be remarked, that physiologists are not entirely of accord regarding the reflux of blood into the vena? cava?. Some think that this always occurs to a slight extent; others, that it is never present in the physiological or healthy state. Its existence is un- equivocal, where an obstacle occurs to the due discharge of the blood into the ventricle. For example, if any impediment exists to the flow of blood along the pulmonary artery, either owing to mechanical obstruction or to diminished force of the ventricle, the reflux will be manifested by a kind of pulsation in the veins, which Haller has called the venous pulsed The blood, having attained the right ventricle, by the effort exerted by the contraction of the auricle, and by the aspiration exerted by the dilatation of the cavity through the agency of its a Elliotson's Lumleyan Lectures on the Recent Improvements in the Art of Distin- guishing the Various Diseases of the Heart, Lond. 1830; and Human Physiology, p. 190, Lond. 1840. Also, Bricheteau's Clinique Medicale, p. 214, Paris, 1835, or trans- lation by the author in Dunglison's American Medical Library, Philad. 1837 ; and J. J. Allison, American Journal of the Medical Sciences, Feb. 1839, p. 313. IN THE HEART. 159 elastic structure, the ventricle contracts. Into it there are but two apertures,—the auriculo-ventricular, and the mouth of the pulmo- nary artery. By the former, much of the blood cannot escape, owing to the tricuspid valve, which acts like the sail of a ship,—the blood distending it, as the wind does a sail, and the chorda? tendineae retaining it in position, so that the greater part of the blood is pre- cluded from reflowing into the auricle. This auriculo-ventricular valve is not, however, as perfect as that of the left heart. The observations of Mr. Kinga show, that whilst the structure of the mitral valve is adapted to close accurately all communication between the left auricle and ventricle during the contraction of the latter, that of the tricuspid valve is designedly calculated to permit, when closed, the flow of a certain quantity of blood into the auricle. The comparatively imperfect valvular function of the tricuspid was shown by various experiments on recent hearts, in which it was found, that fluids, injected through the aorta into the left ventricle, were perfectly retained in that cavity, by the closing of the mitral valve, but that when the right ventricle was similarly injected through the pulmonary artery, tlje tricuspid valves generally allowed the escape of die fluid in streams, more or less copious, in consequence of the incomplete apposition of their margins. This peculiarity of structure in the tricuspid, Mr. King regards as an express provision against the mischiefs that might result from an excessive afflux of blood to the lungs, —the tricuspid thus acting as a safety valve, and being more especially advantageous in incipient diseased enlargements of the right ventricle. The only other way the blood can escape from the right ventricle is by the pulmonary artery, the sigmoid valves of which it raises. These had been closed like flood-gates, during the dilatation of the ventricle; but they are readily pushed outwards, by the column transmitted from the ventricle. Such is the circulation through one heart,—the pulmonic. The same explanation is applied to the other,—the systemic ; and hence ii is, that the structure, as well as the functions of the heart, is so much better comprehended, by conceiving it to be constituted of two essentially similar organs. The above description is that which is usually given of the circu- lation through the heart. There is great reason, however, for the belief, that too much importance has been assigned to the distinct contraction of the auricles. If we examine their anatomical arrange- ment we discover, that there are no valves at the mouths of the great veins which open into them, and that, although, in the proper auricular or dog's ear portion, muscular fibres, and columns.— somewhat analogous to those of the columnse carnese of the ven- tricles, and probably destined for similar uses—exist, the parietes of the main portions of the auricles—or those that constitute the venous sinuses—are but little adapted for any thing like energetic 1 Guy's Hospital Report?, No.'iv. for April, 1837. 160 CIRCULATION contraction. In experiments on living animals observation shows, that the rhythmic acts of dilatation and contraction are more sig- nally exhibited by the ventricle, whilst in some monsters the'auri- cles are wanting, and in birds they are very small. M. Despine, too, considers the auricles, in receiving or transmitting blood to have only a vermicular motion, not one of contraction; and in an interesting case of monstrosity, described by Dr. T. Robinson,8 of Petersburg, Virginia, no distinct systole and diastole of the auricles could be detected. Besides, if we admit both an active power of dilatation,and of contraction in the ventricles, any similar action of the auricles would seem to be superfluous. In the state of active dilatation of the ventricles, the blood is drawn into their cavities; and as soon as they enter into contraction, the auriculo-ventricular valves prevent the farther entrance into them of the blood arriving in the auricles by the large veins, and give occasion to the disten- tion of the auricles; in this way, the dilatation of the auricles, syn- chronous with the contraction of the ventricles, is accounted for. As soon as the ventricle has emptied itself of its blood, it dilates actively ; the blood then passes suddenly from the auricle into its cavity through the auriculo-ventricular opening. From careful experiments instituted by Drs. Pennock and Moore,b they drew the following conclusion:—the ventricles contract and the auricles dilate at the same time, occupying about one-half the whole time required for contraction, diastole, and repose. Imme- diately at the termination of the systole of the ventricle, its diastole succeeds, occupying about one-fourth of the whole time, synchro- nously with which the auricle diminishes, by emptying a portion of its blood into the ventricle, but without muscular contraction. The remaining fourth is devoted to the repose of the ventricles, near the termination of which the auricle contracts actively, with a short, quick motion, thus distending the ventricles with an additional quantity of blood ; this motion is propagated immediately to the ventricles, and their systole takes place, thus rendering their con- tractions almost continuous. From the termination of their diastole to the commencement of their systole, the ventricles are in a state of perfect repose, their cavities remaining full, but not distended; whilst those of the auri- cles are partially so, during the whole time. It appears probable,-that the great use of the auricles—in which we include the sinuses—is to act as true "sinuses" or gulfs for the reception of the blood proceeding from every part of the body;— and that little effect is produced on the circulation by their varving condition.0 The state of the heart in which the ventricles are dilated is termed its Diastole ; that, in' which they are contracted, its Systole. * American Journal of the Medical Sciences, No. xxii. for February, 1833. b Medical Examiner, Nov. 2,1839, and Dunglison's American Medical Intelligencer, Dei. 16, 1839, p. 277. c See, on this subject, Elliotson's Human Physiology, p. 174, Lond. 1840. IN THE HEART. 161 Since the valuable improvement, introduced by Laennec in the discrimination of diseases of the chest by audible evidences, it has been discovered, that the heart is not in a state of incessant activity, but that it has, like other muscles, its intervals of repose. If we apply the ear or the stethoscope to the precordial region, we hear," first, a dull, lengthened sound,a which according to Laennec is syn- chronous with the arterial pulse, and is produced by the contrac- tion of the ventricles. This is instantly succeeded by a sharp, quick sound like that of the valve of a bellows or the lapping of a dog. This corresponds to the interval between two pulsations, and is owing to the contraction of the auricles. The space of time, that elapses between this and the sound of the contraction of the ventricles, is the period of repose. The relative duration of these periods is as follows:—one-half, or somewhat less, for the contrac- tion of the ventricles; a quarter, or somewhat more, for the con- traction of the auricles; and the remaining quarter for the period of total cessation from labour. So that in the twenty-four hours the ventricles work twelve hours and rest twelve; and the auricles work six and rest eighteen. Such is the view of Laennec; but it is manifestly erroneous. Ocular observation on living animals, as Dr. Alisonb has remarked, shows that the emptying of the auricle precedes that of the ventricle, and that the interval of rest is between the contraction of the ventricle, and the next contraction or empty- ing of the auricle: between the contraction of the auricle, and that of the ventricle, there is no appreciable interval. Pucheltc thinks it most probable that the first sound is caused by the impulse of the blood against the walls of the ventricle during the contraction of the auricles, and the second by the impulse of the blood against the commencement of the arteries during the contraction of the ven- tricles. M. Despine thinks that the first sound is produced by the contraction of the ventricle, and that the second is owing to their dilatation.*1 Our knowledge, indeed, of the cause of the sounds rendered by the heart, is sufficiently imprecise: this is farther proved by the circumstance, that Magendie ascribed the. first sound to the shock or impulsion of the apex of the heart during its diastole, and the second to the impulsion of the base of the heart during its systole; but the results of more recent ex- periments6 lead him to infer, that the first sound is owing to the contraction of the ventricles, and to the impulse of the apex of the heart against the ribs, and the second sound to a similar impulse produced by their dilatation. Bouillaud/ after direct examination, attributes the double sound or tic-tac to the play of the valves of the heart. Rouanets ascribes the first or dull sound to the a A Treatise on the Diseases of the CBest, translated by Dr. Forbes, 4th edit. Lond. 1834. b Outlines of Physiology, Lond. 1831. c System der Medicin. th. i. Auflage 2te, s. 149, Heidelb. 1835. (1 Revue Medicale, Oct. 1831. e Annales des Sciences Naturelles, 1834, f Jom-nal Hebdomad. No. ix. 1834. « Ibid. No. xcvii. 14* 162 CIRCULATION shock or impulse of the tricuspid and mitral valves against the auriculo-ventricular orifices, and the second or clear sound to the succussion of the blood in the distended aorta and pulmonary artery backwards against the semilunar valves, during the dilatation of the ventricles; and a similar opinion is entertained by Dr. Hopea and by Mr. Mayo.b Mr. Carlisle0 and Dr. Williams* refer the first sound, with Laennec, to the systole of the ventricles, and the second to the obstacle presented by the semilunar valves to the return of the blood from the arteries into the heart,—and Messrs. Corrigan,6 Pigeauxf and Stokes8 thought the first sound to be owing to the systole of the venous sinuses, and the second to the systole of the ventricles—an opinion, which Burdachb thinks is best founded, but which, as we have seen, is manifestly erroneous.1 Drs. Pennock and Moore,J who agree in the main with Dr. Hope, found the first sound, the impulse, and the systole of the ventricles to be synchronous; and the second sound to be synchronous with the diastole of the ven- tricles. The first sound, they suggest, may be a combination of that caused by the contraction of the auricles, the flapping of the auriculo-ventricular valves, the rush of blood from the ventricles, and the sound of muscular contraction. In four of their experi- ments, when the heart was removed from the body, the ventri- cles cut open and emptied of their contents, and the auriculo- ventricular valves elevated, a sound resembling the first was still heard, which they attribute chiefly to muscular contraction. The second sound they refer exclusively to the closure of the semilunar valves by the refluent blood from the aorta and pulmonary artery. " This," they remark, " is proved by the greater intensity of this sound over the aorta than elsewhere, the blood having a strong tendency to return through the valvular opening; by the greater feebleness of the sound over the pulmonary artery, which is short, and soon distributes its blood through the lungs, thus producing but slight impulse upon the valves in the attempt to regurgitate; by the disappearance of the sound when the heart becomes congested and contracts feebly; and, finally, on account of its entire extinction when the valve of the aorta was elevated." The results of these experiments accord closely with the views we have entertained and taught on this subject,k but the matter is still open for further investigation. a For an elaborate account of the Experiments on the Action and Sounds of the Heart, up to the period of publication of this work, see Dr. Hope, Treatise on Diseases of the Heart, 3d edit. p. 9, Lond. 1839. b Outlines of Human Pathology, p. 465, Lond. 1836. c Report of the Third Meeting of the British Association for the Advancement of Science; and Amer. Journal of Med. Sciences, p. 477, for Feb. 1835. d A Rational Exposition of the Physical Signs of Diseases of the Lungs and Pleura Amer. Edit., Philad. 1830. e Dublin Medical Trans, vol. i. New Series. f Bulletin des Sciences Medicales, par Ferussac, xxv. 272. e Edinb. Med. and Surg. Journal, vol. xxxiv. h Die Physiologie als Erfahrungswissenschaft, iv. 219, Leipz. 1832. 1 Mailer's Handbuch, u. s. w. Baly's translation, p. 176, Lond. 1838. J Op. citat. k See Elliotson's Human Physiology, part I. p. 175, Lond. 1840; Hope, op. citat.; IN THE HEART. 163 It has been a question with physiologists, whether the cavities of the heart completely empty themselves at each contraction. Senac,3 and Thomas Bartnoline," from their experiments, were long ago led to answer the question negatively. On the other hand, Haller0 entertained an opposite opinion,—suggested, he remarks, by his experiments, but, perhaps, notwithstanding all his candour, con- nected, in some manner, with his doctrine of irritability, which could not easily admit the presence of an irritant in a cavity which had ceased to contract. It has been remarked by Magendie,d that if we notice the heart of a living animal, whilst it is in a state of action, it is obvious, that the extent of the contractions cannot have the effect of completely emptying the-ventricles; but it must, at the same time, be admitted, that such experiments are inconclusive, inasmuch as they exhibit to us the action of the organ under power- fully deranging influences, and such as could be readily conceived to modify materially the extent of the contractions. They certainly are insufficient to prove, that, whilst an animal is in a physiological condition, the auricles and ventricles are not emptied of their con- tents by their contraction. The objection that has been urged against the opposite view, that there would always be stagnant blood in the cavities of the heart, is not valid. The experiments of Venturi,6 have shown, that even in an ordinary hy- draulic appara- Fig. 127. tus, the motion of a stream, passing through a vessel of wa- ter, is commu- nicated to the fluid, which is at rest in the vessel, so that an incessant change is pro- duced. ---Let us suppose a stream of water Gerhard, on the Diagnosis of Diseases of the Chest, Philad. 1836; Bouillaud, Traite Clinique des Maladies du Coeur, Paris, 1835; Raciborski, Manual of Auscultation, by Fitzherbert, p. 102, Lond. 1835; C. J. B. Williams, Lectures on the Chest, in Lond. Lancet, reprinted in Bell's Select Medical Library, Philad. 1839; Drs. Williams, Todd and Clcndinning, in Lond. Med. Gaz. Dec. 10, 1836; Drs. Williams and Todd's Report to the British Association at Liverpool, for Sept. 1837, in Lond. Med. Gaz. p. 392, Dec. 1837; Drs. Clendinning, Todd and Williams's Report to the British Association for 1838-39, ibid. Oct. 7, 1840, p. 71; and that of Dr. Clendinning to the same Association, for 1839-40, ibid. Oct. 16, 1840, p. 104; Oct. 23, p. 152; Oct. 30, p. 186, and Nov. 13, p. 267. a Traite de la Structure du Coeur, &c. 2d edit. Paris, 1774. i> Disscrtat. de Corde, Hath. 1648. c Element. Physiol, iv. ll Precis, &c. torn. ii. e Sur la Communication Laterale du Mouvement dans les Fluides, Paris, 1798; and Sir C. Bell, in Animal Mechanics, p. 35, Library of Useful Knowledge, Lond. 1829. 164 CIRCULATION to enter the vessel D E F B, Fig. 127, which is full of fluid, by the pipe A C, and that opposite to this pipe is the tube S M B R. The stream will pass up this tube higher than the vessel, and discharge itself at B V. At the same time, the fluid in the vessel will be observed to be in motion, and, in a few seconds, the level in the vessel will fall from D B to H M. During the systole of the heart, the organ is suddenly carried forward; and although it appears to be rendered shorter, its point strikes the left side of the chest opposite the interval between the fifth and seventh true ribs; producing what is called the " beating of the heart." The cause of this phenomenon was, at one period, a topic of warm controversy. Borelli,a Winslow, and others, affirmed, that it was owing to the organ being elongated during contraction; but to this it was replied by Bassuel,b that if such elongation took place, the tricuspid and mitral valves, kept down by the columnse carneoe, could not possibly close the openings between the corresponding auricles and ventricles. Recent experiments by Drs. Pennock and Moore0 exhibited to them, that the expulsion of the blood from the ventricles was effected by an approximation of the sides of the heart, and not by a contraction of the apex towards the base; and that, during the systole, the heart performs a spiral movement and becomes elongated. Senacd ascribed the beating of the heart to three causes, and his views have been adopted by most physiologists:—1, to the dilatation of the auricles, which occurs during the contraction of the ventricles; 2, to the dilata- tion of the aorta and pulmonary artery by the introduction of the blood, sent into them by the ventricles; and 3, to the straightening of the arch of the aorta, owing to the blood being forced against it by the contraction of the left ventricle. Dr. William Hunter6 con- sidered the last cause quite sufficient to explain the phenomenon, and many physiologists have assented to his view. Sir David Barryf instituted some experiments, upon this subject. He opened the thorax of a living animal, and, by passing his hand into the cavity, endeavoured to ascertain the actual condition of the heart and great vessels, as to distention and relative position. He per- formed seven experiments of this kind, from which he concluded, that the vena cava is considerably increased in size during inspira- tion, which he ascribes, as will be better understood hereafter, to the partial vacuum then formed in the chest. He supposes, that the force exerted by the venous blood on entering the heart, in conse- quence of the expansion of the chest and the great vessels behind the heart, pushes the organ forwards, and thus causes it to strike against the ribs. Drs. Pennock and Moore,& however, in their a De Motu Animalium, Lugd. Bat. 1710. b Magendie's Precis, &c. ii. 395. c Med. Examiner, Nov. 2, 1839. d Traite de la Structure du Coeur, &c. Paris, 1749. c John Hunter, Treatise on the Blood, &c. f Exp. Researches on the influence of atmospheric pressure upon the circulation, Lond. 1826. s Op. citat. IN THE HEART. 165 experiments, found the impulse to be synchronous with, and caused by the contraction of the ventricles, and that, when felt externally, it arose from the striking of the apex of the heart against the thorax. This is probably the true explanation; yet Muller* thinks that great uncertainty rests as to whether the impulse is produced during the contraction or dilatation of the ventricles. The systole of the heart is admitted by all to be active. Some physiologists are disposed to think the diastole passive,—that is— the effect of relaxation of the fibres or of the cessation of contrac- tion. Pechlin, Perrault, Hamberger, Despine, Alison, and nume- rous others, have supported an opposite view;—affirming that direct experiment on living animals shows, that positive effort is exerted at the time of the dilatation of the cavities;—a view strikingly con- firmed by the case of monstrosity related by Dr. Robinson.b His opinion is, that the force of the diastole was in that case, equal to, if not greater than that of the systole. It has been suggested, that if the course of all the fibres, composing the muscular parietes of the organ, were better known, this apparent anomaly might perhaps be as easily explained as in the ordinary case of antagonist muscles. It is probable, however, that the active force, exerted in the dilata- tion of these cavities, is that of elasticity; and that when the con- traction of the muscular fibres has ceased, this is aroused to action, and promptly restores the organ to its previously dilated condition. According to this view, the natural state would be that of dilatation. We shall see, hereafter, that this elasticity is probably one of the agents of the circulation of the blood along the vessels. The cause of the heart's action has been a deeply interesting question to the physiologist, and, in the obscurity of the subject, has given rise to many and warm controversies. From the first mo- ment of foetal existence, at which the heart becomes perceptible, till the cessation of vitality, it continues to move. By many of the ancients this was supposed to be owing to an inherent pulsific virtue,^ which enabled it to contract and dilate alternately,—a mode of expression, which, in the infancy of physical science, was frequently employed to cover ignorance, and which has been properly and severely castigated by Moliere.d It was in ridicule of the same failing that Swift represents the action of a smokejack as depending on a meat-roasting power.6 1 Handbuch, u. s. w. Baly's translation, p. 175, Lond. 1838. b Amer. Journal of the Medical Sciences, No. xxii. Feb. 1833. See, also, a case of partial Ectopia Cordis, by Dr. John O'Bryen, in Lond. Lancet, for July 7,1838, p. 520. 5 Haller, Elemcnta Physiologice, ii. 6. d " Mihi a doctore Domandatur causam et rationem quare Opium facit dormire. A quoi respondeo; Quia est in eo Virtus dormitiva, Cujus est natura Sensus assoupire." he Malade Imaginaire, Intermede iii. e Fletcher's Rudiments of Physiology, P. ii. a, p. 52, Edinb. 1836. 166 CIRCULATION Descarlesa imagined that an explosion took place in the ventricles as sudden as that of gunpowder. With equal nescience the phe- nomenon was ascribed, by Van Helmont,b to his imaginary archasus; and by Stahl,0 and the rest of the animists, to the anhna, soul or intelligent principle, which is supposed to preside over all the mental and corporeal phenomena. Stahl was, however, one of the first that attempted any rational explanation of the heart's action. Its muscular tissue; the similarity of its contractions to those of ordinary muscles, with the exception of their not being voluntary; the fact of its action being modified by the passions, &c. led him to liken its movements to those of ordinary muscles. He admitted, that, generally,we possess neither perception of, nor power over, its motions; but he affirmed, that habit alone had rendered them involuntary; in the same manner as certain muscular twitchings or tics, which are at first voluntary, may become irresistible by habit. A strong confirmation of this opinion was drawn from the celebrated case of the honourable Colonel Townshend, (called by Adelond and other French writers, Captain Towson,) who was able, (not all his life, as Adelon asserts, but a short time before his death,) to suspend the movements of his heart at pleasure. This case is of so singular a character, in a physiological as well as pathological point of view, that we shall give it in the words of Dr. George Cheyne,6 one of the physicians who attended him, and whose character for veracity is beyond suspicion. "Colonel Townshend, a gentleman of excellent natural parts, and of great honour and integrity, had, for many years, been afflicted with constant vomitings, which had made his life painful and miserable. During the whole time of his illness he had observed the strictest regimen, living on the softest vegetables and lightest animal food; drinking asses' milk daily, dven in the camp; and for common drink, Bristol water, which, the summer before his death, he had drank on the spot. But his illness increas- ing, and his strength decaying, he came from Bristol to Bath in a litter, in autumn, and lay at the Bell Inn. Dr. Baynard, who is since dead, and I were called to him, and attended twice a day for about the space of a week: but, his vomitings continuing still in- cessant, and obstinate against all remedies, we despaired of his recovery. While he was in this condition, he sent for us early one morning; we waited on him with Mr. Skrine, his apothecarv, (since dead also;) we found his senses clear, and his mind calm; his nurse and several servants were about him. He had made his will and settled his affairs. He told us he had sent for us to give him some account of an odd sensation he had for some time observed and felt in himself, which was that composing himself, he could die or expire when he pleased, and yet by an effort, or somehow, he could come to life again; which it seems he had sometimes tried before he had a Tract, de Homine, p, 167, Amst. 1677. b Ortus Medicin. &c. Amstel, 16 IS. <= Theoria vera Medica, Hal. 1737 ; Sprengel's Hist, de Medecine, par Jourdan, v, 195, Paris, 1815. l d Physiologie de I'Homme, edit. cit. iii. 302, * Treatise on Nervous Diseases, p, 307. IN THE HEART. 167 ecnt for us. We heard this with surprise; but as it was not to be accounted for from tried common principles, we could hardly believe the fact as he related it, much less give any account of it; unless he should please to make the experiment before us, which we were unwilling he should do, lest, in his weak condition, he might carry it too far. He continued to talk very distinctly and sensibly above a quarter of an hour, about this (to him) surprising sensation, and insisted so much on our seeing the trial made, that we were at last forced to comply. We all three felt his pulse first; it was dis- tinct, though small and thready; and his heart had its usual beating. He composed himself on his back, and lay in a still posture, some time. While I held his right hand, Dr. B. laid his hand on his heart, and Mr. S. held a clean looking-glass to his mouth. I found his pulse sink gradually, till at last I could not feel any, by the most exact and nice touch. Dr. Baynard could not feel the least motion in his heart, nor Mr. Skrine the least soil of breath on the bright mirror he held to his mouth. Then each of us, by turn, examined his arm, heart and breath, but could not by the nicest scrutiny dis- cover the least symptom of life in him. We reasoned a long time about this odd appearance as well as we could; and all of us judg- ing it inexplicable and unaccountable; and finding he still continued in that condition, we began to conclude indeed that he had carried the experiment too far, and at last were satisfied that he was ac- tually dead, and were just ready to leave him. This continued about half an hour, by nine o'clock in the morning, in autumn. As we were going away, we observed some motion about the body, and upon examination found his pulse and the motion of his heart gradually returning; he began to breathe gently and speak softly; we were all astonished, to the last degree, at this unexpected change, and after some further conversation with him, and among ourselves, went away fully satisfied as to all the particulars of this fact, but confounded and puzzled, and not able to form any rational scheme, that might account for it. He afterwards called for his attorney, added a codicil to his will, settled legacies on his servants, received the sacrament, and calmly and composedly expired about five or six o'clock that evening." It is manifest that this case—unaccountable as it is, in many respects—can add no weight to the views of the Stahlians. It is as strange, as it is inexplicable. The opinion with them, that the heart's action is a muscular function, was accurate. The error lay in placing it amongst the voluntary functions. It belongs to the involuntary class, equally with many of the muscles concerned in deglutition, and with those of the stomach and intestines; and how well is it for us, as Sir Charles Bell has remarked, that the actions of this and other organs, directly instrumental to the organic func- tions, are placed out of our control! " A doubt—a moment's pause of irresolution—a forgetfulness of a single action at its appointed time—would otherwise have terminated our existence."1 * See Fletcher's Rudiments of Physiology, part ii. I. p. 71, Edinb. 1836- 168 CIRCULATION In an oriental journal, Mr. H. M. Twedela has published a case, even more extraordinary than that of Col. Townshend,—of a Hin- doo, thirty years of age, who " is said, by long practice, to have acquired the art of holding his breath, by shutting the mouth, and stopping the interior opening of the nostrils with the tongue." This man submitted to be buried for a month, and was dug out alive at the expiration of that period. " He was taken out in a per- fectly senseless state—his eyes closed, his hands cramped and pow- erless—his stomach shrunk very much, and his teeth jammed so fast together, that they were forced to open his mouth with an iron instrument to pour a little water down his throat. He gradually recovered his senses, and the use of his limbs, and was restored to perfect health! The doctrine of Haller* on the heart's action rested upon the vis insita or irritability to which he referred all muscular contractions, whether voluntary or involuntary. This property, as stated in another place, he conceived to be possessed by muscles as muscles, independently of all nervous influence. The heart, being a muscle, enjoyed it of necessity; and the irritant, which developed it inces- santly, was the blood. In evidence of this, he observes, that its con- tractions are always more forcible and rapid, when the blood is more abundant; and that they occur successively in the cavities of the heart as the blood reaches them. So completely did Haller assign the heart's action to this irritability, that he denied the nerves any influence over it; resting his belief on the admitted facts, —that the heart will continue to beat after decapitation; after the division of the spinal marrow in the neck; and of the nerves distri- buted to the organ; and, even, after it has been entirely removed from the body. How far the opinions of this great man are cor- rect, respecting the power of contraction residing in the heart, as he conceived it to do in other muscles, we shall inquire presently. The heart, however, is, doubtless, indirectly, under the nervous influence. We see it affected in the various emotions; sometimes augmenting its action violently, at others retarding it. These circumstances have led some individuals to adopt a kind of inter- mediate opinion, and to regard the nervous influence as one of the conditions necessary for all muscular contraction, just as the due circulation of blood is one of those conditions; and to admit, at the same time, the separate existence of a vis insita. S6mmering,c and Behrendsd have, indeed, asserted that the cardiac nerves are not distributed to the tissue of the heart, but merely to the ramifications of the coronary arteries; and hence, that these nerves are not concerned in the functions of the organ, but only in its nutrition; but this is denied by Scarpa,6 and by the generality of anatomists/ a India Journal of Medical and Physical Sciences; and Amer. Journ. of the Medical Sciences, p. 250, Nov. 1837. b Op. citat. c Corpor. Human. Fabric, iii. § 32. d Dissert, qua Demonstrat. Cor. Nervis Carere, Mogunt 1792; and in Ludwigii Script. Neurol. Min. i. 1. e Tabulae Neurologica?, &c. Ticin. 1794. { Seiler, in art. Herz. in Anat. Phys. Real. Worterb. iv. 33, Leipz. 1821; and Mailer's Handbuch, Baly's translation, p. 190, Lond. 1838. IN THE HEART. 169 Although the emotions manifestly affect the heart, direct experi- ments exhibit but little influence over it on the part of the nerves. This, indeed, we have seen, is one of the grounds for the doctrine of Haller. Willis" divided the eighth pair of nerves; yet the action of the heart persisted for days. Similar results followed the section of the great sympathetic. Magendieb states, that he removed, on several occasions, the cervical ganglions, and the first thoracic; but was unable to determine any thing satisfactory from the operation, in consequence of the immediate death of the animal from such extensive injury as was inevitable. He observed, however, no direct influence on the heart. We have numerous examples of the comparative independence of the organ, as regards the encephalon. Decapitated reptiles have lived for months; and anencephalous infants or those born with part of the brain only, have vegetated during the whole period of pregnancy, and for some days after birth. Legalloisc kept several decapitated mammiferous animals alive; and maintained the heart in action, (having taken the precaution to, tie the vessels of the neck for the purpose of preventing hemorrhage,) by employing artificial respiration, so as to keep up the conversion of venous into arterial blood, and thus to insure to the heart a supply of its appropriate fluid. We find, too, that in fracture of the skull, in apoplexy, and in congenerous affections, the functions of the heart are the last to be arrested. The result of his own experiments led Legallois to infer, that the power of the heart is altogether derived from the spinal marrow; and he conceived, that through the cardiac nerves it is influenced by this portion of the cerebro-spinal axis, and is liable to be affected by the passions, because the spinal marrow is itself influ- enced by the brain. Dr. Wilson Philipd has, however, shown, that the facts do not warrant the conclusions; and he has exhibited, by direct experiment, that the brain has as much influence as the spinal marrow over the motions of the heart, when the circumstances of the experiment are precisely the same. The removal of the spinal marrow, like that of the brain, if the experiment be performed cau- tiously and slowly, does not sensibly affect the motion of the heart,— the animal having been previously deprived of sensibility. In these experiments, the circulation ceased quite as soon without, as with, the destruction of the spinal marrow. Loss of blood appeared to be the chief cause of its cessation; and pain would have contributed to the same effect, if the animal had been operated on, without having been previously rendered insensible. Mr. Clift,e the ingenious conservator of the Museum of the Royal ' Cerebri Anat. cap. xxiv. in Oper., Genev., 1776. b Precis, &c. ii. 401. See, also, Pommer, Beitrage zur Natur-und Heilkunde. Heil- bronn, 1831; Sir A. Cooper, in Guy's Hospital Reports, i. 470, Lond. 1836; Muller, op. citat. p. 198; and Burdach, op. citat. iv. 457. c Sur le Principe de la Vie, p. 138. d An Experimental Inquiry into the Laws of the Vital Functions, &,c. p. 62, Lond. 1817. e Philosoph. Transact, for 1815. VOL. II. 15 170 CIRCULATION College of Surgeons of London, made a series of experiments to ascertain the influence of the spinal marrow on the action of the heart in fishes, and he found, that, whether the heart be exposed or not, its action continues long after the brain and spinal marrow are destroyed, and still longer when the brain is removed without injury to its substance. Similar results were obtained by Treviranus on the frog, and by Saviole on the chick in ovo. Zinn and Ent too found, that after the destruction of the cerebellum, to which Willis ascribed the heart's action, it continued to beat.a All these facts plainly exhibit, that, although the heart is indirectly influenced by the brain or spinal marrow, it is not directly acted upon by either one or the other, and that its action can be main- tained for some time, after the destruction of one or both, provided artificial respiration be kept up; but even this last agent is unneces- sary: the heart will continue to beat, even after it has been removed from the body. In the case of the rattlesnake, Dr. Harlanb observed the heart, torn from the body, continue its contractions for ten or twelve hours; and in the monstrous foetus, observed by Dr. T. Robinson,0 its motion continued for some time after the auricles and ventricles had been laid open; the organ roughly handled, and thrown into a basin of cold water. We are compelled, then, if we do not admit the whole of the Hallerian doctrine of irritability, to presume, that there is something inherent in the structure of the heart, which enables it to contract and dilate, when appropriately stimulated; and it is not even necessary, that this should be by the fluid, to which it is habituated. It is certain, that the organ, when separated from the body, may be stimulated to contraction, by being immersed in warm water, or pricked with a sharp-pointed instru- ment. In some experiments by Sir B. Brodie,d he emptied the heart of its blood, and found that it still contracted and relaxed alternately. Similar experiments were instituted by Mr. Mayo,6 and with like results, from which he concludes that the alternations of contraction and relaxation in the heart depend upon something in its structure. The conclusion is, indeed, irrefutable, if we add to these evidences the results of some experiments by Prof. J. K. Mitchell/ of Phila- delphia. In 1823, being engaged in dissecting a sturgeon—Acipen- ser brevirostrum ?—its heart was taken out and laid on the ground, and, after a time, having ceased to beat, was inflated with the breath, for the purpose of drying it. Hung up in this state, it began again to move, and continued for ten hours to pulsate regularly, though more and more slowly; and when last observed in motion, the auri- 1 Burdach's Physiologie als Erfahrungswissenschaft, &c. iv. 454, Leipz. 1832. See, also, Muller, op. citat. p. 191. b Medical and Physical Researches, p. 103, Philad. 1835. c Amer. Journ. of the Med. Sciences, No. xxii. Feb. 1833. d Cooke's Treatise on Nervous Diseases, Introd. p. 61, Lond. 1820-23. Amer. Edit. Boston, 1824. "- Outlines of Human Physiology, 4th edit. p. 46, Lond. 1837. ' f American Journal of the Medical Sciences, vii. 58, Philad. 1830. IN THE HEART. 171 cles had become so dry as to rustle when they contracted and dilated. He subsequently repeated the experiment with the heart of a Testudo serpentaria or snapper, and found it to beat well under the influence of oxygen, hydrogen, carbonic acid, and nitrogen, thrown into it in succession. Water also stimulated it,—perhaps more strongly,—but made its substance look pale and hydropic, and, in one minute, destroyed action beyond recovery. The heart is the generator of one of the forces that move the blood. This force has been the subject of much calculation, but the results have been so discordant as to throw discredit upon all mathematical investigations on living organs; a circumstance which renders it unnecessary to state the different plans that have been pursued in these estimations. They are all given in the elabo- rate work of Haller,a to which the reader, who may be desirous of examining them, is referred. Borellib conceived the force exerted by the left ventricle to be equivalent to 180,000 pounds; Senacc to 40 pounds; Halesd to 51 pounds 5 ounces; Jurin6 to 15 pounds 4 ounces; whilst Keillf conceived it not to exceed from 5 to 8 ounces! The mode adopted by Hales has always been regarded the most satisfactory. By inserting a glass tube into the carotid of various animals, he noticed how high the blood rose in the tube. This he found to be, in the dog, 6 feet 8 inches; in the ram, 6 feet 5^ inches; in the horse, 9 feet 8 inches; and he estimated, that, in man, it would rise as high as 7^ feet. Now, a tube, whose area is one inch square and two feet long, holds nearly a pound of water. We may there- fore reckon the weight, pressing on each square inch of the ventricle, to be, on a rough estimate, three pounds and three-quarters, or four pounds; and if we consider, with Michelotti, the surface of the left ventricle to be fifteen square inches, it will exert a force, during its contraction, capable of raising sixty pounds.^ Its extent is more frequently, however, estimated at 10 square inches, and the force developed would therefore be forty pounds; but this is, of course, a rude approximation. In such a deranging experiment, the force of the heart cannot fail to be modified; and it is so much affected by age, sex, temperament, idiosyncrasy, &c. that the attainment of accurate knowledge on the subject is impracticable. The indefinite character of our information on this matter is sufficiently shown by the investigations of Poiseuille,h which led him to suppose, that the force with which the heart propels the blood in the human aorta is about 4 pounds, 3 ounces, and 43 grains. 1 Elementa PhysiologiaB, torn. ii. Lausann. 1757-1766. b De Moti'i Animalium, part ii. Lugd. Bat. 1710. cTraite de la Structure du Coeur, Paris, 1749. J Statical Essays, &c. 4th edit. vol. ii. e Philosophical Transactions, for 1718 and 1719. fTrntamina Medico-Physica, &,c. Lond. 1718. e Martini, Lezioni di Fisiologia, tomo sesto, p. 420, Torino, 1828; and Arnott's Ele- ments of Physics, Amer. Edit. vol. i. 2d edit. Philad. 1835. h Sec Magendie's Journal de Physiologie, x. 241 ; Edinb. Med. and Surg. Journ. xxxii. 28 ; Burdach's Physiologie als Erfahrungswissenschaft, iv. 294; and G. T. Mor- gan's First Principles of Surgery, p. 26, Lond. 1837, or Dunglison's American Med. Lib. Edit., Philad. 1838. 172 CIRCULATION By means of an instrument, which, from its use, he terms " hae- madynamometer," the same physiologist has endeavoured to show, that the blood is urged forward with as great a momentum in a small artery, far from the heart, as in any important branch near it. In other words, that there is a uniform amount of pressure exerted by the blood upon the coats of the arteries in every part of the body; —those in the immediate vicinity of the heart being distended by an equal force with those the most remote from it. M. Poiseuillea made the experiment on the carotid, and on the muscular branch of the thigh of the horse, and notwithstanding the very great dissimilarity in the diameter, and distance from the heart, of the two tubes, the displacement of the mercury was exactly the same in both. This inference, if correct,—and the experiments have been repeated by Magendieb with corresponding effects,—are important in a thera- peutical point of view, as they would lead to the belief, that if it be desirable to lessen the quantity of the circulating fluid, it is of little consequence what vessel is opened. b. Circulation in the Arteries. The blood propelled from the heart, by the series of actions we have described,enters the two great blood-vessels;—the pulmonary artery from the right ventricle, and the aorta from the left; the former of which sends it to the lungs, the latter to every part of the system ; and, in both vessels, it is prevented from returning into the corresponding ventricles by the depression of the semilunar valves. We have now to inquire into the circumstances, which act upon it in the arteries, or whether it i^ the contraction of the ventricle, which is alone concerned in its progression. Harveyc and the whole of the mechanical physiologists regarded the arteries as entirely passive in the circulation, and as acting like so many lifeless tubes; the heart being, in their view,the sole agent in the circulation. We have, however, numerous reasons for be- lieving that the arteries are concerned, to a certain degree, in the progression of trie blood. If we open a large artery, in a living animal, the blood flows in distinct pulses; but this effect gradually dhninishes as the artery recedes from the heart, and ultimately ceases in the smallest arterial ramifications;—seeming to show, that the force, exerted by the heart, is not the only one concerned in propelling the blood through these vessels. It is manifest, too, that if the action of the heart were alone concerned, the blood ought to flow out of the aperture, when the artery is opened, at intervals coinciding with the contractions of the heart; and that during the a Magendie, Journal de Physiologie, ix. 46. b Lecons sur le Sang, &c. or translation in London Lancet, Sept. 1838 to March 1839, and in Bell's Select Medical Library, p. 57, Philad. 1839. See, also, some obser- vations on these experiments by Dr. G. C. Holland, in Edinb. Med. and Surg. Journal, Jan. 1841, p. 28. c Exercitatio Anat. De Moth Cordis et Sanguinis, &c. Rotterd. 1648. IN THE ARTERIES. 173 diastole of the artery, no blood ought to issue. This, however, is not the case, notwithstanding the authority of Bichat, and some others is in its favour. The flow is uninterrupted, but in jets or pulses, coinciding with the contractions of the ventricles.1 Again, if two ligatures be put round an arterial trunk, at some distance from each other, and a puncture be made between the ligatures, the blood flows with a jet,—indicating that compression is exerted upon it; and if the diameter of the artery be measured with a pair of compasses, before and after the puncture, it will be found manifestly smaller in the latter case;—an experiment which shows the fallacy of a remark of Bichat,—that the force with which the arteries return upon themselves is insufficient to expel the blood they contain. An experiment of Magendieb exhibits this yet more clearly. He exposed the crural artery and vein in a dog, and passed a ligature behind the vessels, tying it strongly at the posterior part of the thigh, so that the blood could only pass to the limb by the artery, and return by the vein. He then measured, with a pair of compasses, the diameter of the artery; and, on pressing the vessel between his fingers, to intercept the course of blood in it, the artery was observed to diminish perceptibly in size below the part com- pressed, and to empty itself of the blood it contained. On readmitting the blood, by removing the fingers, the artery became gradually distended at each contraction of the heart, and resumed its previous dimensions. These facts prove, that the arteries contract; but the kind of contraction has given occasion to much discussion. It has been imagined, by some physiologists, that their proper coat is muscular, and that they exert a similar action on the blood to that of the heart; dilating to receive it from that organ, and contracting to propel it onwards;—their systole being synchronous with the systole of the auricles and the diastole of the ventricles, and their diastole with that of the auricles, and the systole of the ventricles. The principal reasons, urged in favour of this view, are;—the fact of the circula- tion being effected solely by the arteries in acardiac foetuses, and in animals which have no heart;—the assertion of MM. Lamure and Lafosse, that they noticed, in an experiment with the carotid artery, similar to that described above, that the vessel continued to beat between the ligatures;—the affirmations of Verschuir,0 Bikker, Giulio, and Rossi,d Thomson,e Parry/ Hastings^ Wedemeyer, and numerous others, that when they irritated arteries with the point of a scalpel or subjected them to the electrical and galvanic influences, they exhibited manifest contractility; and lastly, the fact, that the 1 Magendie, Precis, &c. ii. 388. b Journal de Physiologie, i. Ill; and Precis, &c. ii. 386. c De Arteriar. et Venar. vi Irritabili, &c., Groning. 1766. d Elemens de Medec. Operat., Turin, 1806. e Lectures on Inflammation, p. 83, Edinb. 1813; also, 2d Amer. Edit., Philad. 1831. f On the Arterial Pulse, p. 52, Bath, 1816. b On Inflammation of the Mucous Membrane of the Lungs, p. 20, Lond. 1820. 15* 174 CIRCULATION pulse is not perfectly synchronous in different parts of the body, which ought to be the case, were the arteries not possessed of any distinct action. The chief objection to the views, founded on the muscularity of the middle coat, is the want of evidence of the fact. In the ana- tomical proem to the function of the circulation, it was stated, that this coat does not seem to consist of the fibrous or muscular tissue; and that the experiments of Magendie, Nysten, and others, had not been able to exhibit any contraction, on the application of the ordi- nary excitants of muscular irritability. The chemical analyses of Berzelius1 and Youngb also show, that the transverse fibres differ essentially from those of proper muscles. Again, if an artery be exposed in a living animal, we observe none of that contraction and dilatation which is perceptible in the heart; although a manifest pulsation is communicated to the finger placed over it. The phenomena of the pulse will engage attention speedily. We may merely remark, at present, that the pulsations are manifestly more dependent upon the action of the heart than upon that of the arteries. In syncope, they entirely cease; and whilst they continue beneath an aneurismal tumour, because the continuity of the vessel is not destroyed, they completely cease beneath a ligature, so applied round an artery as to cut off the flow of blood. Bichat attached an inert tube to the carotid artery of a living animal, so that the blood could flow through it: the same kind of pulsation was observed in it as in the artery. To this he adapted a bag of gummed taffeta, so as to simulate an aneurismal tumour: the pulsations were evidenced in the bag. If, again, arterial blood be passed into a vein, the latter vessel, which has ordinarily no pulsation, now begins to beat; whilst, if blood from a vein be directed into an artery, the latter ceases to beat.0 Another class of physiologists have reduced the whole of the arterial action to simple elasticity; a property, which the yellow tissue that composes the proper membrane of the artery, seems to possess in an unusual degree. Such is the opinion of Magendie.d " Admitting it to be certain," he remarks, " that contraction and dilatation occur in the arteries, I am far from thinking, with some authors of the last century, that they dilate of themselves, and con- tract in the manner of muscular fibres. On the contrarv, I am certain, that they are passive in both cases, that is, that their dila- tation and contraction are the simple effect of the elasticity of their parietes, put in action by the blood, which the heart sends inces- santly into their cavity,"—and he farther remarks, that there is no difference, in this respect, between the large and the small arteries. As regards the larger arteries, it is probable, that this elasticity is a View of the Progress of Animal Chemistry, p. 25, Lond. 1813. b An Introduction to Medical Literature, p. 501, Lond. 1813. c Adelon, Physiol, de I'Homme, edit. cit. iii. 380; and art. Circulation, in Diet, de Medecine, lere edit. v. 321, Paris, 1822. d Precis, &c. edit. cit. ii. 387. IN THE ARTERIES. 175 the principal but not the only action exerted; and that it is the cause, why the blood flows in a continuous, though pulsatory, stream, when an opening is made into them; thus acting, like the reservoir of air in certain pumps. In the pump A B, represented in the marginal figure, were there no air-vessel C, the water would flow through the pipe E at each stroke of the piston, but the stream would be interrupted. By means of the air-vessel, this is reme- died. The water, at each stroke, is sent into the vessel; the air contained in the air-vessel is thus compressed, and its elasticity thereby augmented; so that it keeps up a constant pressure on the surface of the water, and forces it out of the vessel, through the pipe D, in a nearly uniform stream. Now, in the heart, the contraction of the ventricle acts like the depression of the piston; the blood is propelled into the artery in an interrupted man- ner, but the elasticity of the blood- vessel presses upon the blood, in the same manner as the air, in the air- vessel, upon the water within it; and thus the blood flows along the vessel in an uninterrupted, although pulsatory, stream.* There are many difficulties, however, in the way of admitting the whole of the action of the arteries in the circulation to be dependent upon simple elasticity. The heart of a salamander was opened by Spallanzani,b yet the blood continued to flow through the vessels for twelve minutes after the operation. The heart of a tadpole was cut out, yet the circulation was maintained for some time in several of the vascular ramifications of the tail. The heart of the chick in ovo was destroyed immediately after contraction; the arterial blood look a retrograde direction, and the momentum of the venous blood was redoubled. The circulation continued in this manner for eighteen minutes. Dr. Wilson Philipc states, that he distinctly saw the circulation in the smaller vessels, for some time after the heart had been removed from the body, and a similar observation was made by Dr. Hastings.11 The latter gentleman states, that in the large arterial trunks, and even in the veins, he has noticed, in the clearest manner, their contraction on the application of various stimulants, both chemical and mechanical. It is, moreover, well known, that if a small living artery be cut across, it will soon con- 1 Weber's Hildebrandt's Anatomie, iii. 69, Braunschweig, 1830. ,»> Experiments on the Circulation, &c. translated by R. Hall, Lond. 1801. « An Experimental Inquiry into the Laws of the Vital Functions, Lond. 1817; and Lond. Med. Gazette, for March 25th, 1837, p. 952. d Op. citat. p. 51. Section of a Forcing Pump. 176 CIRCULATION tract, so as to arrest hemorrhage; and that, whilst an animal is bleeding to death, the arteries will accommodate themselves to the decreasing quantity of blood in the vessels, and contract beyond the degree to which their elasticity could be presumed to carry them; and that after death they will again relax. Dr. Parry found, that the artery of a living animal, if exposed to the air, will sometimes contract in a few minutes to a great extent; in such case, only a single fibre of the artery may be affected, narrowing the channel in the same way as if a thread were tied round it. The experiments which have been instituted for the purpose of discovering the dependence of the arterial action on the nervous system, have likewise afforded evidences of their capability of assuming a contractile action, and have led to a better compre- hension of those cases of what have been called local determina- tions of blood. Dr. Philip found, that the motion of the blood in the capillaries is influenced by stimulants applied to the central parts of the nervous system, which must be owing to the capillaries possess- ing a power of contractility, capable of being aroused to action by the nervous influence. The experiments of Sir Everard Home3 are, however, more applicable, as they were directed to the larger arteries, respecting which the greatest doubts have been entertained. The carotid artery of a dog was laid bare; the par vagum and great sympathetic, which, in that animal, form one bundle, were separated from it by a flattened probe, for one-tenth of an inch in length; the head and neck of the dog were then placed in an easy position, and the pulsations of the carotid artery were attended to by all present, for two minutes, in order that the eye might be accustomed to their force in a natural state. The nerve, passing over the probe, was then slightly touched with caustic potassa. In a minute and a half, the pulsations of the exposed artery became more distinct. In two minutes, the beats were stronger; in four minutes, their violence was lessened; and in five minutes, the action was restored to its natural state. The experiment was repeated, with analogous results, upon a rabbit. In that animal, the par vagum was separated from the intercostal nerve; and it was found, that, when the par vagum alone was irritated, no increase took place in the force of the action of the artery. " The carotid artery," says Sir Everard, " was chosen as the only artery in the body of sufficient size, that can be readily exposed, to which the nervous branches, supplying it, can be traced from their trunk. This experi- ment was repeated three different times, so as to leave no doubts respecting the result." These experiments demonstrate, that, under the nervous influence, an increase or diminution may take place in the contraction of an artery; and they aid us in the explanation of those cases, in which the circulation has been accomplished, where the heart has been altogether wanting or completely defective in structure. * Lectures on Comparative Anatomy, iii. 57, Lond. 1823. IN THE CAPILLARIES. 177 Sir Everard instituted some farther experiments, with the view of determining whether heat or cold has the greatest agency in stimulating the nerves to produce this effect upon the artery. The wrist of one arm was surrounded by bladders filled with ice; and after it had remained in that state for five minutes, the pulse of the two wrists was felt at the same time. The beats in that which had been cooled, were found lobe manifestly stronger. A similar expe- riment was now made with water, heated to 120° or 130° of Fah- renheit. The pulse was found to be softer and feebler in the heated arm. When one wrist was cooled and the other heated, the stroke of the pulse, in the cooled arm, had much greater force than that of the heated one. These experiments were repeated upon the wrists of several young men and young women of different ages, with uniform results. Lastly, we have remarked, and shall have occasion to refer to the matter again, that certain animals, which have no heart," have cir- culating vessels in which contraction and dilatation are perceptible. This is the case with the class vermes of Cuvier, and can be seen very distinctly in the lumbricus marinus or lug, the leech, &c. The fact has been invoked both by the believers in the muscular con- tractility of arteries, and by those who conceive the contractility to be peculiar; but our acquaintance with the intimate structure of the coats of the vessels, in those animals, is too minute for us to assert more than that they are manifestly contractile. From these and other considerations, the majority of physiologists have admitted a contractile action, not simply in the capillary ves- sels, but in the larger arterial trunks; and, at the present day the most general and satisfactory opinion appears to be, that, in addi- tion to the highly elastic property possessed by the middle coat, it is capable of being thrown into contraction; that, in the larger ves- sels, this contraction is but little exerted, the action of the artery being mainly produced by its elasticity; but that, in the smaller arterial ramifications, the contractility is more apparent; and, in the capillary vessels, is scarcely equivocal. To this action of con- tractility, necessarily connected with the life of the vessel, and dif- fering from both muscular contractility and simple elasticity, Dr. Parryb gave the name tonicity. c. Circulation through the Capillaries. The agency of the capillary vessels in the circulation has been a subject of contention. It was the opinion of Harvey, and the opinion is embraced by J. Muller,0 that the action of the heart is alone suf- a See a case of this kind in the human foetus, by Dr. J. S. B. Jackson, of Boston, in the Ami rican Journal of the Medical Sciences, for February, 1838, p. 362; and another by Dr. Houston, in the Dublin Journal of Med. Sciences. No. xxix. See, also, Prof, Graves, Lond. Med. Gaz. June 30, 1838, p. 562. bOn the Arterial Pulse, p. 52, Bath, 1816. c Handbuch, u. s. w. Baly's translation, p. 220, Lond. 1838. 178 CIRCULATION ficient to send the blood through the whole circuit; but we have seen, that, even when aided by the elasticity and contractility of the arterial trunks, the pulsations of the heart become imperceptible in the smaller arteries; and, hence, that there is some show of reason for the belief, that, in the capillary vessels, the force may be entirely spent. Such, indeed, is the opinion of Bichat, who regards the capillaries as organs of propulsion, and alone concerned in returning the blood to the heart through the veins. Dr. Marshall Hall,1 on the other hand, denies that we have any proof of irritability in the true capillaries; and Magendieb conceives the contraction of the heart to be the principal cause of the passage of the blood through these vessels. In support of this view he adduces the following experiment. Having passed a ligature round the thigh of a dog, so as not to compress the crural artery or vein, he tied the vein near the groin, and made a small opening into the vessel. The blood immediately issued with a considerable jet. He then pressed the artery between the fingers, so as to prevent the arterial blood from passing to the limb. The jet of venous blood did not, how- ever, stop. It continued for some moments, but went on diminish- ing, and the flow was arrested, although the vein was filled throughout its whole extent. When the artery w Enquiry into the Moving Powers employed in the Circulation of the Blood, Lond. 1784. c Inquiry into the Causes of the Motion of the Blood, 2d edit. Lond. 1833. d Physiology, by Elliotson, 4th edit. Lond. 1828; Tiedemann's Traite de Physiol. par Jourdan, p. 347 ; and Burdach's Physiologie als Erfahrungswissenschaft, iv. 270, Leipz. 1832. e Lehre vom Kreislauf des Blutes, Nurnberg, 1826. f Handbuch, u. s. w. Baly's translation, p. 173, FORCES THAT PROPEL THE BLOOD. 185 elasticity instantly restores it to its dilated condition ; a vacuum is formed, and the blood rushes in to fill it. This action has been compared by Dr. Bostock,* and by Dr. Southwood Smith,b Prof. Turner,0 and others, to that of an elastic gum bottle, which, when filled with water, and compressed by the hand, allows the fluid to be driven from its mouth with a velocity proportionate to the com- pressing force. But the instant the pressure is removed, elasticity begins to operate, and if the mouth of the bottle be now immersed in water, a considerable quantity of that fluid will be drawn up into the bottle, in consequence of the vacuum formed within it. The existence of this force is confirmed by D611inger,d—who, when examining the embryo of birds, saw the blood advance along the veins, whilst the venous trunks poured it into the auricles at the moment when they dilated to receive it; as well as by Dr. T. Robinson,6 who was forcibly struck with the activity with which the diastole was effected, in the case of monstrosity, more than once referred to.f , Another accessory force, which has been invoked, is the suction power of the chest, or the inspiration of venous blood, as it has been termed. This is conceived to be effected by the same mechanism as that which draws air into the chest. The chest is dilated during inspiration; an approach to a vacuum occurs in the thorax; and the blood, as well as the air, is forcibly drawn towards that cavity. On the other hand, during expiration, all the thoracic viscera are compressed; the venous blood is repelled from the chest, and the arterial blood reaches its destination with greater celerity, owing to the action of the expiratory muscles being added to that of the left ventricle. Haller,8 Lamure,h and Lorry' had observed, that the blood, in the external jugular vein, moves under manifestly different influences, during inspiration and expiration. Generally, when the chest is dilated in inspiration, the vein empties itself briskly, becomes flat, and its sides are, occasionally, accurately applied against each other;—but, during expiration, the vein rises and becomes filled with blood ;—effects, which are more evident, when the respiratory movements are more extensive. The explanation of this phenome- non, by Haller and Lorry, is the one given above. To discover whether the same thing happens to the venae cavae, Magendie introduced a gum elastic catheter into the jugular vein, so as to penetrate the vena cava and even the right auricle;—the » Physiology, 3d edit. p. 251, Lond. 1836. b Animal Physiology, (Library of Useful Knowledge) p. 83, Lond. 1829. c Edinb. Medico-Chirurg. Transact, iii. 225. d Denkschriften der Konigl. Akademie der Wissenschaft. zu Munchen, vii. 217; and Burdach, op. citat. p. 272. e Amer. Journ. of the Med. Sciences, No. xxii. f See, also, D. H. Hayne, in Medicin. Jarbuch. des k. k. Osterreich. Staates. B. xv. s. 125, Wicn; and Good's Book of Nature, i. 349, Lond. 1826. s Elementa Physiologioe, torn. ii. h Mem. de i'Aead. des Sciences, pour 1749, ' Magendie, Precis, &c. ii. 416. 16* 186 CIRCULATION. blood was observed to flow from the extremity of the tube at the time of expiration only. During inspiration, air was rapidly drawn into the heart, giving rise to the symptoms to be mentioned here- after, which attend the reception of air into that organ. Similar results were obtained, when the tube was introduced into the crural vein in the direction of the abdomen. So far as regards the larger venous trunks, therefore, the influence of respiration on the circula- tion is sufficiently evidenced.1 It can be easily shown, by opening an artery of the limbs, that expiration manifestly accelerates the motion of arterial blood; especially in forced expiration, and during violent exertion. In animals, subjected to experiment, it is impracticable to excite either the forced expiration or the violent effort at pleasure; but we can, as a substitute, compress the sides of the chest with the hands, according to the plan recommended by Lamure, when the blood will be found to flow more or less copiously, in proportion to the pressure exerted. It occurred to Magendie, that this effect of respiration on the course of the blood in the arteries might influence the flow along the veins. To prove this, he passed a ligature round one of the jugular veins of a dog. The vessel emptied itself beneath the liga- ture, and became turgid above it. He then made a slight puncture, with a lancet, in the distended portion; and in this way obtained a jet of blood, which was not sensibly modified by the ordinary respiratory movements, but became of triple or quadruple the size, when the animal struggled. As it might be objected to this experi- ment, that the effect of respiration was not transmitted by the arteries to the open vein, but rather by the veins that had remained free, which might have conveyed the blood—repelled from the vena cava—towards the tied vein, by means of anastomoses,—the experi- ment was varied. The dog has not, like man, large internal jugular veins, which receive the blood from the interior of the head. The circulation from the head and neck is, in it, almost wholly confined to the external jugular veins, which are extremely large; the inter- nal jugulars being little more than vestiges. By tying both of these veins at once, Magendie made sure of obviating, in great part, the reflux in question; but, instead of this double ligature diminishing the phenomenon under consideration, the jet became more closely connected with the respiratory movement; for it was manifesflv modified even by ordinary respiration, which was not the case when a single ligature was employed. From these and other experiments, Magendie properly concludes, that the turgescence of the veins must not be ascribed, with Haller, Lamure, and Lorry, simply to the reflux of the blood of the vena? cavae into the branches opening directly or indirectly into them; but that it is partly owing to the blood being sent in larger quantitv into the veins from the arteries.b » See, also, Poiscuille, in Magendie's Journal de Physiologie, viii. 272. b Precis, &c., ii. 421. FORCES THAT PROPEL THE BLOOD. 187 In the same manner are explained—the rising and sinking of the brain, which, as was observed in an early part of this work, (vol. i. p. 80,) are synchronous with expiration and inspiration. During expiration, the thoracic and abdominal viscera are compressed; the blood is driven more into the branches of the ascending aorta, and it is, at the same time, prevented from returning by the veins: owing to the combination of these causes, the brain is raised during expiration. In inspiration, all this pressure is removed; the blood is free to pass equally by the descending, as by the ascending, aorta; the return by the veins is ready, and the brain therefore sinks.1 We can thus, also, explain why the face is red and swollen during crying, running, straining, and the violent emotions ; and why pain is augmented in local inflammations of an extremity,—as in cases of whitlow, and when respiration is hurried or impeded by running, crying, &c. The blood accumulates in the part, owing to the compound effect of increased flow by the arteries, and im- peded return by the veins. The same explanation applies to the production of hemorrhage by any violent exertion ; and Bourdonb affirms, that he has always seen hemorrhage from the nose largely augmented during expiration; diminished at the time of inspiration, and arrested by prolonged inspiration;—a therapeutical fact of some interest. It is manifest, then, that the circulation is modified by the move- ments of inspiration and expiration,0—the former facilitating the flow of blood to the heart by the veins, and the latter encouraging the flow by the arteries; and we shall see hereafter, that there is great reason for the belief, that the dilatation of the chest,—which constitutes the first inspiration of the new-born child,—is a great cause of the establishment of the new circulation; the same dilata- tion, which causes the entrance of air into the air-cells, soliciting the flow of blood, or the " inspiration of venous blood," as Magendied has termed it. In a paper read before the Royal Society of Lon- don, in June, 1835, Dr. Wardrop,6 after remarking, that he considers inspiration as an auxiliary to the venous, and expiration to the arte- rial circulation, attempts, on this principle, to explain the influence exerted on the circulation, and on the action of the heart, by various modes of respiration, whether voluntary or involuntary, in different circumstances. Laughter, crying, weeping, sobbing, and sighing, he regards as efforts made with a view to effect certain alterations a This motion of the brain must not be confounded with that which is synchronous with the contraction of the left ventricle; and which is owing to the pulsation of the arteries at the base of the brain. b Recherches sur le Mecanisme de la Respiration et sur la Circulation du Sang, Paris, 1820. c Dr. Clendinning's Report to the Brit. Association, 1839-40, Lond. Med. Gazette, Nov. 13, 1840, p. 270. '• Precis, &c, ii. 416. e On the Nature and Treatment of the Diseases of the Heart; with some new views of the Physiology of the Circulation, Lond. 1837. 188 CIRCULATION. in the quantity of blood in the lungs and heart, when the circulation has been disturbed by mental emotions. The influence of ordinary respiration can, however, be but trifling; yet it has been brought forward by Sir David Barry* as the efficient cause of venous circulation. His reasons for this belief are,—the facts just mentioned, regarding the influence of inspiration on the flow of blood towards the heart, and certain ingeniously modified experiments, tending to the elucidation of the same result. He introduced one end of a spirally convoluted tube into the jugular vein of an animal, and plunged the other into a vessel filled with a coloured fluid. During inspiration, the fluid passed from the vessel into the vein; during expiration, it remained stationary in the tube, or was repelled into the vessel. Dr. Bostockb remarks, that he was present at some experiments, which were performed by Sir David, at the Veterinary College in London, and it appeared sufficiently obvious, that when one end of a glass tube was inserted either into the large veins, into the cavity of the thorax, or into the pericar- dium,—the other end being plunged into a vessel of coloured water, —the water was seen to rise up the tube during inspiration, and to descend during expiration. The conclusion of Sir David fronvthese experiments, is most comprehensive;—that "the circulation in the great veins depends upon atmospheric pressure in all animals pos- sessing the power of contracting and dilating a cavity around that point, to which the centripetal current of their circulation is direct- ed ;" and he conceives, that as, during inspiration, a vacuum is formed around the heart, the equilibrium of pressure is destroyed, and the atmosphere acts upon the superficial veins, propelling their contents onwards to supply the vacuum. Independently of other objections, there are a few, which appear to us convincing against this sole agency of ordinary respiration in effecting venous circulation. According to Sir David's hypothesis, blood ought to arrive at the heart at the time of inspiration only; and as there are, in the average, seventy-two contractions of the heart for every eighteen inspirations; or four contractions, or—what is the same thing—four dilatations of the auricle for each respira- tion; one of these only ought to be concerned in the propulsion of blood, whilst the rest should be bloodless; yet we feel no difference in the strength of the four pulsations. It is clear, too, if we adopt Sir David's reasoning, that, of the four pulsations, two, and conse- quently two dilatations of the auricles, must occur during expiration, at which time the capacity of the chest is actually diminished. Moreover, holding the breath ought to suspend the circulation; and the respiratory influence cannot be invoked to explain the circula- tion in the foetus or in aquatic animals. At the most, therefore, respiration can only be regarded as a feeble auxiliary in the circu- lation. In favour of Dr. Barry's opinion of the efficiency of at- * Experimental Researches on the Influence of Atmospheric Pressure upon the Cir- culation of the Blood, &c. Lond. 1826. b Physiology, 3d edit. p. 330, Note, Lond. 1836. FORCES THAT PROPEL THE BLOOD. 189 mospheric pressure in causing the return of blood by the veins, he adduces the fact,—already referred to, under the head of Absorption,—that the application of an exhausted vessel over a poisoned wound prevents the absorption of the poison; but this, as we have seen, appears to be a physical effect, which would apply equally to any view of the subject. In all these cases, the elastic resilience of the lungs, by contri- buting to diminish the atmospheric pressure upon the outer surface of the auricles, may, likewise, as suggested by Dr. Carson,1 have some agency in soliciting the blood into these cavities, but the agency cannot be great. There is another circumstance of a purely physical nature, which may exert some influence upon the flow of the blood along the veins; viz. the expanded termination of the venae cavae in the right auricle. To explain this, it is necessary to premise a detail of a few hydraulic facts. If an aperture A, Fig. 130, exist in a cistern X, the Fig. 130. water will not issue at the aperture by trr a stream of uniform size; but, at a short distance from the reservoir, it will be contracted as at B, consti- tuting what has been termed the vena contracla. Now, it has been found, that if a tube, technically called an adjutage, be attached to this aperture, so as to accurately fit the stream, as at A B, Fig. 131, as much fluid will flow from the reservoir as if the aper- ture alone existed. Again, if the pipe B C be attached to the adjutage A B, the expanded extremity at A will occasion the flow of water, from the reservoir, to be greater than it would Fig. 131. be, if no such expanded ex- tremity existed, in the ratio, ac- cording to Ven- turi, of 12.1 to 10; and if to the tube B C,a trun- cated conical tube C D, be attached, the length of which is nearly nine times the diameter of C; and the diameter of C to that of D be as 1 to 8; the flow of * Philosoph. Transact, for 1820, and An Inquiry into the Causes of Respiration, &c. 3d edit. Liverpool, 1833. 190 CIRCULATION. water will be augmented in the proportion of 24 to 12.1; so that, by the two adjutages A B and C D, the expenditure through the pipe B C is increased in the ratio of 24 to 10. This fact,—the result of direct experiment, and so important to those who contract to supply water by means of pipes,—was known to the Romans. Private persons, according to Frontinus,1 were in the habit of purchasing the right of delivering water in their houses from the public reservoirs, but the law prohibited them from making the conducting pipe larger than the opening allowed them in the reservoir, within the distance of fifty feet. The Roman legislature must, therefore, have been aware of the fact, that an adjutage with an expanded orifice, would increase the flow of water; but they were ignorant that the same effect would be induced beyond the fifty feet. Let us apply this law to the circulation. In the first place, at the origin of the pulmonary artery and aorta, there is a manifest nar- rowness, formed by the ring at the base of the semilunar valves (see Fig. 124 ; and this might be conceived unfavourable to the flow of the blood along those vessels during the systole of the ventricles; but from the law, which has been laid down, the narrowness would occupy the natural situation of the vena contracta, and, therefore, little or no effect would be induced. The discharge would be the same as if no such narrowness existed. We have seen, again, that the vena cava becomes of larger calibre as it approaches the right auricle, and finally terminates in that cavity by an expanded aper- ture. This may have a similar effect with the expanded tube C D, Fig. 131, which doubles the expenditure.11 In making these conjectures,—some of which have been adduced by Sir Charles Bell,—it is proper to observe, that, in the opinion of some natural philosophers, the effect of the adjutage is entirely due to atmospheric pressure, and that no such acceleration occurs, pro- vided the experiment be repeated in vacuo. Sir Charles Bell0 con- ceives, that " the weight of the descending column in the reservoir being the force, and this operating as a vis a tergo, it is like the water propelled from the jet d'eau, and the gradual expansion of the tube permits the stream from behind to force itself between the filaments, and disperses them, without producing that pressure on the sides of the tube, which must take place, where it is of uniform calibre." It is on this latter view only, that these sin- gular hydrostatic facts can be applied to the doctrine of the cir- culation. In addition to the movements, impressed on the blood by the parietes of the cavities in which it moves, it has been considered by many physiologists,—as by Harvey, Glisson, Bohn, Albinus, Rosa, * Lat. Oudendorp, Lugd. Bat. 1731. b Venturi, Sur la Communication Laterale du Mouvement dans les Fluides Paris 1798; and Pouillet, Elemens de Physiologie, i. 205, Paris, 1832. c Animal Mechanics, p. 40, in Library of Useful Knowledge, Lond. 1829. FORCES»THAT PROPEL THE BLOOD. 191 Tiedemann, G. R. Treviranus,1 Rogerson," Alison,0 and others, — to possess a power of automatic or self-motion. Broussais asserts, that he has seen experiments,—originally performed by P. A. t abre, which showed, that the blood, in the capillary system, frequently moves in an opposite direction to that given it by the heart,—re- peated by M. Sarlandiere, on the mesentery of the frog. In tnese, the blood was seen to rush, for some moments, towards the point irritated, and, when a congestion had taken place there, they re- marked, that the globules took a different direction, and traversed vessels, which conveyed them in an opposite course, and a few seconds afterwards, these were again observed to return with equal rapidity to the point from which they had been repelled. Tiede- mann' has collected the testimonies of various individuals on this point. Haller,* Spallanzani,- Wilson Philip/ G. R. Treviranus^ and others, have remarked, by the aid of the microscope, that the blood continued to move in the vessels of different animals, but chiefly of frogs, for some time after the great vessels had been tied, or the heart itself removed ;-a fact which Tiedemann also, often witnessed. C. F. Wolff,k Rolando,1 Dbllinger, and Pander- Prevost and Dumas," Von Bar,0 and others saw globules of blood in motion in the incubated egg, before the formation of either vessels or heart; and Hunter, Gruithuisen, and Kaltenbrunner observed—in the midst of the cellular tissue of inflamed parts, in tissues undergoing regeneration, and during the cicatrization ot wounds,-bloody points placed successively in contact with each other, forming small currents, which represented new vessels and united to those alreadv existing. The fact, indeed, that the embryo forms its own vessels, and that blood in motion can be detected before vessels are in esse, is a sufficient proof,—were there no other, » Tiedemann, Traite Complet de Physiologie de I'Homme, traduit par Jourdan i. 348, Paris, 1831; and Richerand's Physiologie, 13eme edit, par Berard a.ne, p. 131, Bruxelles, 1837. : i££S 'ZIFS^£&&1!£: i83, ^ ™. *. j. g»^ * ^TsS^pSS^^A 398, Lond 1835; and Messrs. Emmerson and Reader, in Edinb. Med. and Surg. Journal, April 183b. • Traite de Physiologie, &c. translated by Drs. Bell and La Roche, 3d edit. p. a/4, Phfnod' S" g °Per> Minor-L115'Sect a h E^per.Vn the Circulation, &c. in Engl, by R. Hall, Lond. 1801. » Philos. Transact. 1815; and Medico-Chirurg. Trans, vol. xn i Vermischte Schriften, i. 102. kQTheoria Generations, Hal. 1759. 1 Dizionario Periodico di Medicina, Torino, 182-2-18^. . „„:„„„„ -Dissert, sist. Hist. Metamorphoseos quam Ovum Incubatum pnonbus quinque Diebus subit, Wirceb. 1817. .. 1Q0_ n Annales des Sciences Naturelles, torn. xn. p. 415, Dec. 1W/. o Ueber Entwickelungsgesehichte der Thiere u. s. w Th. i. Kg the absence of the requisite data, a recent writer has gone so far as to affirm the average .velocity of the blood in the aorta, to be about eight inches per second; whilst " the velocity in the extreme capillaries is found to be often less than one inch per minute." A similar estimate was made by Dr. Young;" Hales,b too, estimated the velocity of the blood leaving the heart at 149.2 feet per minute, and the quantity of blood passing through the organ every hour at twenty times the weight of the blood in the body; but the judicious physio- logist knows well, that in all operations, which are partly of a vital character, the results of every kind of calculation must be given with caution and humility. In the larger animals, as the whale, the quantity of the fluid circulating in the aorta must be prodigious. Dr. Hunter, in his account of the dissection of a whale, states that the aorta was a foot in diameter, and that ten or fifteen gallons of blood were probably thrown out of the heart at each stroke; so that this vessel is in the whale actually larger than the main pipe of the old water-works at London Bridge; and the water, rushing through the pipe, it has been conceived, had less impetus and velo- city than that gushing from the heart of this leviathan.0 The velocity of the circulating fluid in the minute vessels is gene- rally thought to be less than in the larger ;d and their united calibres to be much greater than that of the trunk with which they commu- cate. Were this the case, the diminution of velocity would be in accordance with a law of hydrodynamics;—that when a liquid flows through a full pipe, the quantity which traverses the different sec- tions of the pipe, in a given time, must be every where the same; so that where the pipe is wider the velocity diminishes ; and,on the contrary, where it is narrower the velocity increases. This would not Seem, however, to be consistent with the experiments of Poi- seuille, already referred to, which appear to show, that the pressure exerted on the blood in different parts of the body—as measured by the column of mercury, which the blood in different arteries will sustain—is almost exactly the same. The cause of error in the common belief, that the capacity of the arterial tubes increases in proportion to their distance from the heart, has been explained by Mr. Ferneley.e It is true, he observes, that the sum of the diameters of the branches is considerably greater than that of the trunk. Thus a trunk, 7 lines across, may divide into two branches of 5 lines each, or a trunk of 17 into three branches of 10, 10, and 9^; but when their areas are compared, the correspondence is as close as can be reasonably expected, when the nature of the measurement is taken into account. In the first case, the area of the trunk is represented by the square of 7—that is, 49; whilst the area of each branch will be 25, and the sum of a Med Literature, Lond. 1813. b Statical Essays, vol. ii. Lond. 1829. c Paley's Natural Theology; and Animal Physiology, p. 75, Library of Useful Knowledge, Lond. 1829. d Prof. R. J. Graves, in Lond. Med. Gazette for June 30, 1838, p. 559. e Lond. Med. Gaz. Dec. 7, 1839. VELOCITY OF THE CIRCULATION. 197 the two will be 50. In the second instance, the area of the trunk will be 17 squared, or 289; whilst that of the branches is the sum of 100, 100, and 90^, making 290i.a From what, has been said, regarding the curvatures and angles of vessels, it will be understood, that the blood must proceed to diffe- rent organs with different velocities. The renal artery is extremely short, straight, and large, and must consequently transmit the blood very differently to the kidney, from what the tortuous carotid does to the brain; or the spermatic artery to the testicle. A different impulse must, consequently, be given to their corresponding organs by these different vessels. A great portion, however, of the impulse of the heart must fail to reach the kidney, short as the renal artery is, owing to its passing off from the aorta at a right angle; and, hence, the impulse of the blood on the kidney may not be as great as might be imagined at first sight. The tortuosity of the carotid arteries is such as to greatly destroy the impetus of the blood; so that but trifling hemorrhage takes place when the brain is sliced away on a living animal, although it is presumed, that one-eighth of the whole quantity of blood is sent to the encephalon. Dr. Rush supposed, that the use of the thyroid gland is to break the afflux of blood to the brain; for which its situation between the heart and the head appeared to him to adapt it; and he adduced, as farther arguments, the number of arteries which it receives, although effecting no secretion; as well as the effect on the brain, which he conceived to be caused by diseases, and by extirpation, of the thyroid; the operation having actually occasioned, in his opinion, in one case, inflammation of the brain, rapidly terminating fatally; and, likewise, the fact that goitre is often accompanied by idiotism. The opinion, however, is so entirely conjectural, and some of the facts, on which it rests, so question- able, that it does not demand serious examination. This leads us to remark, that the thyroid gland, as well as other organs, with whose precise functions we are totally unacquainted— as the thymus, spleen, and supra-renal capsules,—have been con- ceived to serve as diverticula or temporary reservoirs to the blood, when, owing to particular circumstances, that fluid cannot circulate properly in other parts. Lieutaud having observed, that the spleen is always larger when the stomach is empty than when full, consi- dered that the blood, when digestion is not going on, reflows into the spleen, and that thus this organ becomes a diverticulum to the stomach. The opinion has been indulged by many, with more or less modification. Dr. Rush's view was yet more comprehensive. He regarded the spleen as a diverticulum, not simply to the stomach, but to the whole system, when the circulation is violently excited, as in passion, or in violent muscular efforts, at which times there is danger of sanguineous congestion in different organs; and in sup- port of his view, he invoked the spongy nature of the spleen; the 1 Brit, and For. Med. Rev. April, 1840, p. 422. 17* 198 CIRCULATION. frequency of its distension ; the large quantity of blood distributed to it; its vicinity to the centre of the circulation; and the sensation referred'to it, in running, laughing, ccc. Broussais" has still farther extended the notion of diverticula. He affirms, that they always exist in the vicinity of organs, whose functions are manifestly intermittent. In the foetus, the blood does not circulate through the lungs as when respiration has been established: diverticula, he, therefore, considers to be necessary: these are the thymus and thy- roid glands. The kidneys do not act in utero: hence the use of the supra-renal capsules as diverticula. At birth, these organs are either wholly obliterated, if the organs to which they previously acted as diverticula have continuous functions; or they are only partly obliterated, if the functions are intermittent. Thus, the spleen continues as a diverticulum to the stomach, because its functions are intermittent through life; and the thymus disappears, when respiration is established: the liver and the portal system he regards as a reservoir, inservient to the reception of the blood, in cases of impediment to the circulation in different parts of the body. These notions are entirely hypothetical. We shall see, hereafter, that our ignorance of the offices of the spleen, thymus, &c, is ex- treme ; and we have already shown, that much more probable uses can be assigned to the portal system. The insufficiency of the doctrine of diverticula by Broussais is strikingly evidenced by the fact that whilst the thymus gland disappears gradually in the progress of age, the thyroid remains, as well as the supra-renal capsules.b g. The Pulse. We have had occasion, more than once, to refer to the subject of the pulse, or to the beat felt by the finger when applied over any of the larger arteries. Opinions have varied essentially regarding its cause. Whilst most physiologists have believed it to be owing to distension of the arteries, caused by each contraction of the left ventricle; some have admitted a systole and diastole of the vessel itself; some, as Bichat and Weitbrecht,c having thought that it is owing to the locomotion of the artery; others, that the impulse of the heart's contraction is transmitted through the fluid blood, as through a solid body; and others, as Dr. Youngd and Dr. Parry,6 that it is owing to the sudden rush forward of the blood in the artery without distension. * Commentaires des Propositions de Pathologie, &c. Paris, 1829; and Drs. Hays and Griffith's translation, p. 214, Philad. 1832. b Adelon, Physiologie de I'Homme, torn. iii. 328, 2de edit, Paris, 1829. c Comment. Acad. Imper. Scient. Petropol. ad Ann. 1734 &, 1735, Petrop. 1740. d Croonian lectures, in Philos. Transact, for ] 809, Part i. e An Experimental Inquiry into the Nature, Causes, and Varieties of the Arterial Pulse, by Caleb Hillier Parry, Lond. 1816; also, Additional Experiments on the arte- ries of warm-blooded animals, &c. by Ch. Henry Parry, M. D. &c. Lond. 1819 ; Dr. Prichard, in Transact, of the Provincial Med. and Surg. Association, iv. 16 Lond. 1836. PULSE. 199 Bichat was one of the first, who was disposed to doubt, whether the dilatation of the artery, which was almost universally admitted", really existed; or if it did, whether it was sufficient to explain the phenomenon; and, since his time, numerous experiments have been made by Dr. Parry, the result of which satisfied him, that not the smallest dilatationcan be detected in the larger arteries, when they are laid bare during life; nor does he believe, that there is such a degree of locomotion of the vessel as can account for the effect produced upon the finger. He ascribes the pulse, therefore, to " impulse of distention from the systole of the left ventricle, given by the blood, as it passes through any part of an artery contracted within its natural diameter." Dr. Bostock1 appears to coincide with Dr. Parry, if we understand him rightly, or at all. " According to this (Dr. Parry's) doctrine," he remarks, " we must regard the artery as an elastic and distensible tube, which is at all times filled although with the contained fluid not in an equally condensed state, and that the effect produced upon the finger depends upon the amount of this condensation, or upon the pressure which it exercises upon the vessel, as determined by the degree, in which it is capable of* being compressed. Where there is no resistance to the flow of the blood along the arteries, there is no variation, it is conceived, in their diameter, and it is only the pressure of the finger or some other substance against the side of an artery that produces its pulse.b Most of the theories of the pulse take the contractility of the artery too little into account. In pathology, where we have an opportunity of observing the pulse in various phases, we meet with sensations, communicated to the fingers, which it is difficult to explain upon any theory, except that of the compound action of the heart and arteries. The impulse is obviously that of the heart, and although the fact of distention escaped the observation of Bichat, Parry, Weitbrecht, Lamure, Dollinger, Rudolphi,0 Jager,d and others, we ought not to conclude, that it does not occur. It is, indeed, difficult for us to believe, that such an impulse can be communicated to a fluid filling an elastic vessel without pulsatory distention super- vening. In opposition, too, to the negative observations of Bichat and Parry, we have the positive averment of Dr. Hastings, and of Poiseuille,6 Oesterreicher, Segalas, and Wedemeyer, that the alter- nate contraction and dilatation of the larger arteries was clearly seen/ The pulsations of the different arteries are pretty nearly synchro- » Physiology, 3d edit. p. 246, Lond. 1836. b Good's Study of Medicine, Physiological Proem to the ckss Haematica. c Grundriss der Physiologie, &c. Berlin, 1821. d Tractatus Anatomico-physiologicus de Arteriarum Pulsd. Virceb. 1820. e Repertoire generate d'Anatomie, &c. par Breschet, 1829, torn. vi. and vii. and Ma- gendie's Journal de Physiol, viii. and ix. f Burdach's Physiologie als Erfahrungswissenchaft, torn. iv. Lsipz. 1832. For a mode of estimating the arterial distention, see Poiseuille, in Magendie's Journal de Physiologie, ix. 44, and Jules Herison's description of an instrument—the Sphygmo- meter—which makes the action of the arteries apparent to the eye. 200 CIRCULATION. nous with that of the left ventricle. Those of the vessels near the heart may be regarded as almost wholly so, but an appreciable interval exists in the pulsations of the more remote vessels." We have remarked, that the arterial system is manifestly more or less affected by the nerves distributed to it; that it may be stimu- lated by irritants, applied to the great nervous centres, or to the nerves passing to it; and this is, doubtless, the cause of many of the modifications of arterial tension, that we notice in disease. No inflammation can affect any part of the system, for any length of time, without both heart and arteries participating, and affording us unequivocal signs of such inflammation. This, however, is a subject that belongs more especially to pathology. The ordinary number of pulsations, per minute, in the healthy adult male, is from seventy to seventy-five; but this varies greatly according to temperament, habit of life, position,—whether lying, sitting, or standing,b &c. Dr. Guy,c from numerous observations, found the pulse, in healthy males, of the mean age of 27 years, in a state of rest, 79 when standing; 70, sitting, and 67, lying; the difference between standing and sitting being 9 beats; between sitting and lying, 3 beats; and between standing and lying, 12 beats. When all exceptions to the general rule were excluded, the numbers were: standing, 81; sitting, 71; and lying, 66;—the difference between standing and sitting being 10 beats; between sitting and lying, 5 beats; and between standing and lying, 15 beats. The effect produced upon the pulse by change of posture, Dr. Guy ascribes to muscular contraction, whether employed to change the position of the body, or to main- tain it in the same position. In some individuals in perfect health, the number of beats is sin- gularly few. The pulse of a person, known to the author, was on the average thirty-six per minute; and Lizzarid affirms, that he knew a person in whom it was not more than ten. It is not impro- bable, however, that in these cases, obscure beats may have taken place intermediately, and yet not have been detected. In a case of pericarditis, in which the author felt great interest, the pulse exhibited a decided intermission, every few beats, yet the heart beat its due number of times; the intermission of the pulse at the wrist consist- ing in the loss of one of the beats of the heart. It was not impro- bable but that in this case, the contractility of the aorta was un- usually developed by the inflammatory condition of the heart; and that the flow of blood from the ventricle was thus occasionally diminished or entirely impeded. The quickest pulse, which Dr. a Dr. Allen Thomson, in art. Circulation, Cyclopaedia of Anatomy and Physiology, P. vii. p. 664, Lond, 1836; and Mailer's Handbuch, u. s. w. Baly's translation, p. 200. b Dr. M'Donnel, in Dublin Journal of Med. and Chemical Science, Sept. 1835. ' Guy's Hospital Reports, No. vi. April, 1838, p. 92. d Raccolta D'Opusculi Scientifici, p. 265; and Good's Study of Medicine, Physiolo- gical Proem to class iii. Hcematica. See Cases of Slowness of the Pulse, by Mr. Mayo, Lond. Med. Gaz. May 5, 1838, p. 232. PULSE. 201 Elliotson" ever felt, was 208, counted easily, he says, at the heart, though not at the wrist. The pulse of the female is usually eight or ten beats in a minute quicker than that of the male. In infancy, it is generally irregular, intermitting, and always rapid, and it gradually becomes slower in the progress of age. It is, of course, impossible to arrive at any accurate estimate of the comparative frequency at different periods of life, but the average of the following numbers, on the authority of Heberden,b Sbmmering,0 and Muller,d may, on the whole, be regarded as approximations. Ages. Number of beats per minute, according to Heberden. Sommering. Muller. In the embryo, ... — — 150 At the birth, 130 to 140 Do. Db. One month, ... 120 — — One year,.... 120 to 108 120 115 to 130 Two years, 108 to 90 110 100 to 115 Three years, ... 90 to 80 90 90 to 100 Seven years, ... 72- — 85 to 90 Twelve years, ... 70 — — Puberty, .... — 80 80 to 85 Adult, .... — 70 70 to 75 Old age, .... — 60 50 to 65 Researches by MM. Hourmann and Dechambre,6 do not, how- ever, accord with these estimates in respect to the smaller number of pulsations in the aged. MM. Leuret and Mitivie had suspected an error in this matter from an examination of 71 of the aged inmates of the Bicetre and La Salpetriere. MM. Hourmann and Dechambre examined 255 women between the ages of 60 and 96, and found the average number of the pulse to be 82.29. The pulse—strange to say—may be wholly absent, without the health seeming to be interfered with. A case of this kind is referred to by Prof. S. Jackson/ as having occurred in the mother of a physician of Philadelphia. The pulse disappeared during an attack of acute rheumatism, and could never again be observed during her iife. Yet she was active in body and mind, and possessed unusual health. In no part of the body could a pulse be detected. Dr. Jack- 1 Human Physiology, p. 215, Lond. 1840. b Med. Transact, ii. 21. Also, Blumenbach's Elements of Physiology, by Elliotson, p. 89, 4th edit., Lond. 1828. c See, also, Quetelet sur I'Homme, &c., ii. 80, Paris, 1835; Dr. Knox, in Edinb. Med. and Surg. Journ., April, 1837 ; Mr. Gorham on the Pulse of Infants, in Lond. Med. Gazette, Nov. 25,1837; and Valleix, Clinique des Maladies des Enfans Nouveau- nes, Paris, 1838. d Handbuch der Physiologie, Baly's translation, p. 171, Lond. 1838. e Arehiv. General, de Med. pour 1835. f The Principles of Medicine, founded on the Structure and Functions of the Animal Organism, p. 492, Philad. 1832. See, also, a case of complete disappearance of the beating of the heart, in Gazette Medicale, Nov. 21,1836; and analogous cases in Parry on t,he Pulse, Bath, 1816; in Medico-Chirurg. Review, xix. 285, and ibid. April, 1836, 202 CIRCULATION. son attended her during a part of her last illness—inflammation of the intestines;—no pulse existed. She died whils the was absent from the city, and no examination was made to elucidate the cause of this remarkable phenomenon. Between the number of pulsations and respirations there would not appear to be any fixed relation. In many individuals the ratio in health is 4 to 1," but in disease it varies greatly. Dr. Elliotsonb alludes to a case of nervous disease in a female, at the time in. no danger, whose respiration was 106, and pulse 104. Dr. Knox has made some observations on the pulsations of the heart and on its diurnal revolution and excitability,0 from which he infers: 1. The velocity of the heart's action is in a direct ratio to the age of the individual,—being quickest in young persons, slowest in the aged. There may be exceptions to this, but they do not affect the general law. 2. There are no data to determine the question of an average pulse for all ages. 3. There is a morning acceleration and an evening retardation in the number of the pul- sations of the heart, independently of any stimulation by food, &c. 4. The excitability of the heart undergoes a daily revolution; that is, food and exercise affect the heart's action most in the morning and during the forenoon, least in the afternoon, and least of all in the evening. Hence it might be inferred that the pernicious use of spirituous liquors must be greatly aggravated in those who drink before dinner. 5. Sleep does not farther affect the heart's action than by a cessation of all voluntary motion, and by a recumbent position. 6. In weak persons, muscular action excites the action of the heart more powerfully than in strong and healthy individuals; but this does not apply to other stimulants, to wine, for example, or to spirituous liquors. 7. The effects of the position of the body, in increasing or diminishing the number of pulsations, is solely attributable to the muscular exertion required to maintain the body in the sitting or erect posture: the debility may be measured by altering the position of the person from a recumbent to a sitting or the erect position. 8. The most powerful stimulant to the heart's action is muscular exertion. The febrile pulse never equals this.d h. Uses of the Circulation. The chief uses of the circulation are,—to transmit to the lungs the products of absorption, in order that they may be converted into arterial blood; and to convey to the different organs this arterial blood, which is not only necessary for their vitality, but is the fluid by which the different processes of nutrition, calorification and se- a Quetelet, op. citat. p. 87. b Human Physiology, p. 215, Lond. 1835. See, also, Dr. Ch. Hooker, of New Haven, Connecticut, in Boston Medical and Surgical Journal, for May 16, 23, &c, 1838. c Edinburgh Medical and Surgical Journal, April, 1837. d Dr. Guy, op. citat; and in Edinb. Med. and Surg. Journal, p. 90, Jan. 1841 USES. 203 cretion are effected. These functions will engage us next. We may remark, in conclusion, that the agency of the blood, as the cause of health or insalubrity, has had greater importance assigned to it than it merits; and that although it may be the medium, by which the source of disease is conveyed to other organs, we cannot look to it as the seat of those taints that are commonly referred to it. "Upon the whole," says Dr. Good," "we cannot but regard the blood as, in many respects, the most important fluid of/ the ani- mal machine; from it all the solids are derived and nourished, and all the other fluids are secreted; and it is hence the basis or com- mon pabulum of every part. And. as it is the source of general health, so it is also of general disease. In inflammation, it takes a considerable share, and evinces a peculiar appearance. The miasms of fevers an'd exanthems are harmless to every part of the system, and only become mischievous when they reach the blood; and emetic tartar, when introduced into the jugular vein, will vomit in one or two minutes, although it might require, perhaps, half an hour if thrown into the stomach, and in fact it does not vomit till it has reached the circulation. And the same is true of opium, jalap, and most of the poisons, animal, mineral and vegetable. If imperfectly elaborated, or with a disproportion of some of its constituent prin- ciples to the rest, the whole system partakes of the evil, and a dys- thesis or morbid habit is the certain consequence; whence tabes, atrophy, scurvy, and various species of gangrene. And if it be- comes once impregnated with a peculiar taint, it is wonderful to remark the tenacity with which it retains it, though often in a state of dormancy and inactivity for years, or even entire generations. For as every germ and fibre of every other part is formed and re- generated from the blood, there is no other part of the system, that we can so well look to as the seat of such taints, or the predisposing cause of the disorders I am now alluding to; often corporeal, as gout, struma, phthisis; sometimes mental, as madness; and occa- sionally both, as cretinism." This picture is largely overdrawn. Setting aside the pathological allusions, which are erroneous in assigning to the blood what properly belongs to the system of nutrition, how can we suppose a taint to con- tinue for years, or even entire generations, in a fluid which is per- petually undergoing renovation, and, at any distinct interval cannot be presumed to have one of its quondam particles remaining ? Were all hereditary diseases derived from the mother, we could better comprehend this doctrine of taints ; inasmuch as, during the whole of fcetal existence, she transmits the pabulum for the support of her offspring: the child is, however, equally liable to receive the taint from the father, who supplies no pabulum, but merely a secre- tion from the blood at a fecundating copulation, and from that mo- ment cannot exert any influence upon the character of his progeny. The impulse to this or that organization or conformation must be a Loc. citat. 204 CIRCULATION. given from the moment of union of the particles, furnished by each parent at a fecundating intercourse ; and it is probable, that no subsequent influence is exerted even by the mother. She affords the pabulum, but the embryo accomplishes its own construction, as independently of the parents as the chick in ovo. i. Transfusion and Infusion. The operation of Transfusion,—as well as of Infusion of medi- cinal agents,—was adduced by us in an early part of this chapter, to prove the course of the circulation to be by the arteries into the veins. Both these operations were suggested by the discovery of Harvey. The former, more especially, was looked upon as a means of curing all diseases, and of renovating the aged, ad libitum. The cause of every disease and decay was presumed to reside in the blood, and consequently, all that was conceived to be necessary was to remove the faulty fluid, and to substitute pure blood obtained from a healthy animal in its place. As a therapeutical agent, the history of this operation does not belong to physiology. The detail of the fluctuation of opinions re- garding it, and its total disuse, are given at some length in the His- tories of Medicine, to which we must refer the reader." There are some interesting physiological facts, however, that cannot be passed over. MM. Prevost and Dumas found that the vivifying power of the blood does not reside so much in the serum as in the red par- ticles. An animal bled to syncope was not revived by the injec- tion of water or of pure serum at a proper temperature; but if blood of one of the same species was used, the animal seemed to acquire fresh life at every stroke of the piston, and was at length restored. Transfusion has been revived by Dr. Blundell,b of London, and by MM. Prevost and Dumas ;c-the first of whom has employed it with safety, and he thinks with happy effects, in extensive uterine hemorrhage. All these gentlemen remark, that it can only be adopted, with perfect safety, in animals of like kinds, or in those, the globules of whose blood are of similar configuration. MM. Pre- vost and Dumas, Dieffenbach'1 and Bischoff,e all agree as to the the veins of birds. This influence, according to Muller, is in some deadly influence of the blood of the mammalia when injected into way connected with the fibrine of the blood. Experiments have a Sprengel's Hist, de Med. par Jourdan, iv. 120, Paris, 1815; also, Bostock's Phy- siology, 3d edit. p. 213, Lond. 1836; Pierer, art. Transfusion des Bluts, in Anatom. Physiol.; Real Worterb. B. viii. Altenburg, 1829 ; Dr. J. P. Kay, in art. Transfusion, Cyclopaedia of Practical Medicine, P. xxi. 246, Lond. 1834; and E. Grafe, art. Infusion und Transfusion, Encyc. Worterb. der Medicin. Wissenschaft. xviii. s' 434 Berlin. 1838. b Medico-Chirurgical Transactions, ix. 56; and x. 296 ; and appendix to AshwelPs Practical Treatise on Parturition, London 1828. c Bibliotheque Universelle, xvii. 215. d Die Transfusion des Blutes, Berlin, 1828. e Mailer's Arehiv. 1835; cited in Baly's translation of J. Muller's Handbuch u. s. w. IN ANIMALS. 205 certainly shown, that blood deprived of fibrine acts most injuriously when injected into the vessels." The introduction of the practice of infusing medicinal agents into the blood was coeval with that of transfusion. Both, indeed, are affirmed to have been commenced in 1657, at the suggestion of Sir Christopher Wren.b It is a singular fact, that in cases of infu- sion, medicinal substances are found to exert their specific actions upon certain parts of the body, precisely in the same manner as if they had been received into the stomach. Tartar emetic, for example, vomits, and castor oil purges, not only as certainly, but with much greater speed; for whilst the former, as before remarked, requires to be in the stomach for fifteen or twenty minutes, before vomiting is excited, it produces its effect in one or two minutes, when thrown into the veins. Dr. E. Hale, Junr. of Boston, has published an interesting pamphlet on this subject.0 In it he traces the history of the operation, and details several interesting experi- ments upon animals; and one upon himself, which consisted in the introduction of a quantity of castor oil into the veins. In this experiment, he did not experience much inconvenience immediately after the injection; but very speedily he felt an oily taste in the mouth, which continued for a length of time, and the medicine acted powerfully as a cathartic. Considerable difficulty was experienced in the introduction of the oil, to which circumstance Magendied ascribes Dr. Hale's safety; for it is found, by experiments on animals, that viscid fluids, such as oil, are unable to pass through the pulmonary capillaries, in conse- quence of which the circulation is arrested, and death follows. Such also appears to have been the result of the experiments of Dr. Hale with powdered substances. The injection of medicines into the veins has been largely prac- tised at the Veterinary School of Copenhagen, and with complete success,—the action of the medicine being incomparably more speedy, and the dose required much less. It is rarely employed by the physician, except in his experiments on animals; but it is obvious, that it might be had recourse to, with happy effects, where narcotic and other poisons have been taken, and where the mecha- nical means for their removal are not at hand.e 3. CIRCULATORY APPARATUS IN ANIMALS. In concluding this subject, a brief allusion to the circulatory appa- » Mngendie on the Blood, in Lond. Lancet, and Bell's Select Medical Library Edit. p. 154, Philad. 1839. See, also,-on the different effects of transfusion of arterial and venous blood on animals, Bischoff, in Muller's Arehiv. Heft iv. 1838, and Brit, and For. Med. Rev. April, 1839, p. 548. b Sprengel, op. citat. iv. 121. c Boylston Medical Prize Dissertations, for the years 1819, and 1821, p. 100, Boston, 1821. d Precis, &c, ii. 430. e See on the Infusion of different Medicinal Agents, Mr. Blake, Edinb. Med. and Surg. Journal, April, 1839. VOL. II. 18 206 CIRCULATION ratus of other parts of the animal kingdom may be interesting and instructive. In the mammalia in general, the inner structure of the heart is the same as in man, but its situation differs materially; and, in some of them, as in the stag and pig, two small flat bones, called bones of the heart, exist, where the aorta arises from the left ventricle. In the amphibious mammalia and the cetacea, it has been supposed that the foramen ovale, situate in the septum between the auricles, is open as in the human foetus, to allow those animals to pass a con- siderable time under water without breathing; but the observations of Blumenbach, Cuvier, and others seem to show, that it is almost always closed. Sir Everard Home found it open in the sea otter, in two instances; but these are regarded by naturalists as excep- tions to the general rule. In several of the web-footed mammalia and cetacea, as in the common otter, the sea otter, and the dolphin, particular vessels are found to be always greatly enlarged and tortuous;—a structure which has been chiefly noticed in the vena cava inferior, and which is supposed to serve the purpose of a diverticulum, whilst the animal is under water, or to receive a part of the returning blood, and to retain it until respiration can be resumed. In birds, the structure of the heart universally possesses a singular peculiarity. Instead of the right ventricle having a membranous valve, as in the left, and as in all the mammalia, it is provided with a strong, tense, and nearly triangular muscle, -which aids in the propulsion of the blood from the right side of the heart into the lungs. This is presumed to be necessary, in consequence of their lungs not admitting of expansion like those of the mammalia, and of their being connected with numerous air-cells. The heart of reptiles or amphibia in general consists either of only one ventricle, or of two ventricles; which freely communicate, so as essentially to consti- tute but one. The number of auricles always corresponds with that of the ventricles. That the cavities—auricular or ventricular—are, however, single, although apparently double, is confirmed by the fact, that, in all, there is only a single artery proceeding from the heart, which serves both for the pulmonic and systemic circulations. After this vessel has left the heart, it divides into two branches, by one of which a part only of the blood is con- veyed to the lungs, whilst the other proceeds to different parts of the body. These two portions are united in the heart, and after being mixed together are sent again through the great artery. In these animals, therefore, aeration is circulation u the Frog, obviously less necessary than in the higher IN ANIMALS. 207 Circulation in Fishes. classes; and we can thus understand many of their peculiarities; how the circulation may continue, when the animal is so situate as to be incapa- ble, for a time, of respiration; and the great resistance to ordinary deranging in- fluences, by which they are characterized. The marginal figure (Fig. 132) represents the circulatory apparatus of the frog; in which E is the ventricle andD the auricle. From the former arises the aorta F, which soon divides into two trunks. These, after sending branches to the head and neck, turn downwards, (O and P,) and unite in the single trunk A. This vessel sends ar- teries to the body and limbs, which ulti- timately terminate in veins, and unite to form the vena cava C. From each of the trunks into which the aorta bifurcates at its origin, arise the arteries F. These are distributed to the lungs, and communicate with the pulmonary veins, which return the blood to the auricle, D, where it becomes mixed with the blood of the systemic circulation. In the tadpole state, the circulation is bran- chial, as in fishes. The heart then sends the whole of its blood to the branchice or gills, and it is returned by veins following the course of the dotted lines M and N, (Fig. 132,) which unite to form the descending aorta. As the lungs undergo their developement, small arterial branches arise from the aorta and are distri- buted to those organs, and in proportion as these arteries enlarge, the original branchial arteries diminish, until ultimately they are obli- terated, and the blood flows wholly through the enlarged lateral trunks, O and P, which, by their union, form the descending aorta. In fishes, the heart is extremely small, in pro- portion to the body; and its structure is simple; consisting of a single auricle and ventricle, D and E, (Fig. 133.) From the ventricle E an arterial trunk arises, which, in most fishes, is expanded, into a kind of bulb, F, as it leaves the heart, and proceeds straight forward to the branchice or gills, G and H." From these, the blood passes into a large artery, A, analogous a a Respiratory ceils. to the aorta, which proceeds along the spine, bc. 1'J^^V'Td. and conveys the blood to the various parts of Glands connected with the the system ; and, by the vena cava, C, the blood /p^il.' g. uterus68'" 208 NUTRITION. is returned to the auricle. This is, consequently, a case of single circulation. Insects appear to be devoid of blood-vessels. Cuvier examined all the organs in them, which, in red-blooded animals, are most vascular, without discovering the least appearance of a blood-ves- sel, although extremely minute ramifications of the trachea were obvious in every part. Insects, however, both in their perfect and larva state, have a membranous tube running along the back, in which alternate dilatations and contractions are perceptible; and which has been considered as their heart; but it is closed at both ends, and no vessels can be perceived to originate from it. To this the innumerable ramifications of the trachea convey the air, and thus, as Cuvier has remarked, " le sang ne pouvant aller chercher fair, e'est l'air qui va chercher le sang;" ("the blood not being able to go in search of air—the air seeks the blood.") Carus has, however, discovered a continuous circulation through arteries and veins in a kw of the perfect insects, and especially in some larvae. Lastly, in many genera of the class vermes, particularly amongst the molluscous and testaceous animals, there is a manifest heart, which is sometimes of a singular structure. Some of the bivalves are affirmed to have as many as four auricles; whilst many animals, as the leech and Lumbricus marinus, have no heart; but circula- ting vessels exist, in which contraction and dilatation are percep- tible. The marginal figure, (Fig. 134,) of the interior of a leech, given by Sir Everard Home, will exhibit the mode of circulation and respiration in that animal. There is no heart, but a large vessel exists on each side of the animal. The water is received, through openings in the belly, into the cells or respiratory organs, and passes out through the sarne.a CHAPTER V. NUTRITIOX. The investigation of the phenomena of the circulation has exhi- bited the mode in which arterial blood is distributed over the body in mjnute vessels, not appreciable by the naked eye, and often not even with the microscope, and so numerous, that it is impossible a Roget's Animal and Vegetable Physiology, Amer. Edit., ii. 137, Philad. 1836; art. Circulation, by Dr. Allen Thomson, in Cyclopaedia of Anat. and Physiol., p. 641, Lond. 1836; and Die Formen der Blutbahn in der Thierreihe, von J. Muller, in Bur- dach's Physiologie, u. s. w., i. 141, Leipz. 1832. NUTRITION. 209 for the finest-pointed instrument to be forced through the skin with- out penetrating one, and perhaps several. We have seen, likewise, that, in the capillary system of vessels, this arterial blood is changed into venous; and it was observed, that in the same system, parts are deposited or separated from the blood, and certain phenomena accomplished, into the nature of which we have now to inquire, beginning with those of nutrition, which comprise the incessant changes that are taking place in the body, both of absorption and deposition, and which effect the decomposition and renovation of each organ. Nutrition is well defined by Adelona as the action, by which every part of the body, on the one hand, appropriates or assi- milates to itself a portion of the blood distributed to it; and, on the other, yields to the absorbing vessels a portion of the materials that previously composed it. The precise character of the apparatus, by which this important function is accomplished, we have no means of knowing. All admit, however, that the old matter must be taken up by absorbents, and the new be deposited by arteries, or by vessels, continuous with them. As the precise arrangement of these minute vessels is not perceptible by the eye, even when aided by powerful instruments, their arrangement has given rise to much controversy. Whilst some have imagined lateral pores in the capillary system of vessels, for the transudation of nutritive deposits; others have presumed, that inconceivably small vessels are given off from the capillary system, which constitute a distinct order, and whose function it is to exhale the nutritive substance. Hence, they have been termed exhalants or nutritive exhalants ; but the physiological student must bear in mind, that whenever the term is used by writers, they do not always pledge themselves to the existence of any distinct set of vessels, but merely mean the capillary vessel, whatever may be its nature, which is the agent of nutrition, and conveys the blood to the different tissues. In investigating the physiology of nutrition, two topics necessa- rily divide our attention; 1st, The action of decomposition, by which the organ yields to the absorbing vessels a portion of its consti- tuents; and 2dly, The action of composition, by which the organ assimilates a part of the arterial blood that enters it, and supplies the loss, which it has sustained by the previous action of decompo- sition. The former of *feese actions obviously belongs to the function of absorption; but itfe physiology, it will be recollected, was deferred, in consequence of its close application to the function we are now considering. It comprises what is meant by interstitial, organic or decomposing absorption, and does not require many comments, after the long investigation of the general phenomena of absorption into which we entered. The conclusion, at which we then arrived, was, —that the chyliferous and lymphatic vessels form only chyle and * Physiologie de I'Homme, torn. iii. p. 359, 2de edit., Paris, 1829. 18* 210 NUTRITION. lymph respectively, refusing the admission of all other substances; that the veins admit every liquid which possesses the necessary tenuity; and that, whilst all the absorptions,—which require the substance acted upon to be decomposed and transformed,—are effected by the chyliferous and lymphatic vessels, those that demand no alteration are accomplished through the coats of the veins by imbibition. It is easy, then, to deduce the agents to which we refer the absorption of decomposition. As it is exerted on solids, and as these cannot pass through the coats of the vessel in their solid con- dition, it follows, that other agents than the veins must accomplish the process; and, again, as we never find in the lymphatic vessels any thing but lymph, and as we have every reason to believe that an action of selection is exerted at their extremities, similar to that of the chyliferous vessels on the heterogeneous substances exposed to them, we naturally look to the lymphatics as the main, if not the sole organs, concerned in the absorption of solids. It has been maintained, by some physiologists, that the different tissues are endowed with a vital attractive and elective force, which they exert upon the blood;—that each tissue attracts only those con- stituents of which it is itself composed; and thus, that the whole function of nutrition is an affair of elective affinity; but this, ob- viously, cannot be the force that presides over the original forma- tion of the tissues in the embryo. An attraction cannot be exerted by parts not yet in existence. To account for this, it has been imagined, that a peculiar force is destined to preside over formation and nutrition, and to this force various names have been assigned. By most of the ancients it was termed facultas formalrix, nutrix, auctrix; by Van Helmont,a Bias alterativum; and by Bacon,b motas assimilalionis. It was the facultas vegetativa of Harvey ;c the anima vegetativa of Stahl ;d the puissance du moule interieur of Buffon;e the vis essentialis of C. F. Wolff/ the Bildungstrieb or nisus formativus of Blumenbach and most of the German writers.^ This force is meant, when writers speak of the plastic force, force of nu- trition, force of formation, and force of vegetation. Whatever diffe- rence there may be in the terms selected, all appear to regard it as charged with maintaining, for a certain length of time, livino- bodies and all their parts, in the possession of their due composition, organi- zation, and vital properties, and of putting them in a condition, during a certain period of their existence, to produce beings of the same kind as themselves. It is obvious, however, that none of these terms elucidate the intricate phenomena of nutrition, and that none express more than—that living bodies possess a vital force under the action of which formation and nutrition are accomplished. a Opera, pars i. b Novum Organum, lib. ii.' aphor. 48. c De Generatione Animaliurn, Lond. 1651, p. 170. A Theoria Medica Vera. Hal. 1708. e Histoire Naturelle, torn. ii. f De Generatione, Hal. 1759. s Ueber der Bildungstrieb, u. s. w., Getting. 1794; Comment. Societ. Gotting. torn. viii.; Elliotson's Blumenbach's Physiology, 4th edit., Lond. 1828, p. 490; and Tiede- mann's Traite de Physiologie, par Jourdan, p. 405, Paris, 1831. NUTRITION. 211 Under the idea, that all the vessels of the intermediate system are possessed of coats, it is not easy to comprehend how either nutrition or secretion can be accomplished. Lateral pores, as we shall see under the head of Secretion, have been imagined, but this supposed arrangement, provided it existed, which has not been, and cannot easily be demonstrated, would not materially elucidate the subject; but if we adopt the opinion, before referred to, that many of the vessels of the capillary system consist of metnbraneless or coatless vessels, we can comprehend, that by the elective and attractive forces possessed by the tissues and exerted by them on the blood, materials may be obtained from that fluid as it passes through the intermediate system, which may be inservient to the nutrition of the various tissues that are bathed by it,—the mode in which the blood is dis- tributed through the tissues resembling that in which the water of a river is distributed through a marsh, conveying to the vegetable bodies that flourish on its surface, the materials for their nutrition. To adopt the language of an intelligent and philosophical writer/ "In every part of the body, in the brain, the heart, the lung, the muscle, the membrane, the bone, each tissue attracts only those constituents of which it is itself composed. Thus the common current, rich in all the proximate constituents of the tissues, flows out to each. As the current approaches the tissue, the particles appropriate to the tissue feel its attractive force, obey it, quit the stream, mingle with the substance of the tissue, become identified with it, and are changed into its own true and proper nature. Meantime, the particles which are not appropriate to that particular tissue, not being attracted by it, do not quit the current, but, passing on, are borne by other capil- laries to other tissues, to which they are appropriate, and by which they are apprehended and assimilated. When it has given to the tissues the constituents with which it abounded, and received from them particles no longer useful, and which would become noxious, the blood flows into the veins, to be returned by the pulmonic heart to the lung, where, parting with the useless and noxious matter it has accumulated, and replenished with new proximate principles, it returns to the systemic heart, by which it is again sent back to the tissues." Particles of blood are seen to quit the current, and mingle with the tissues; particles are seen to quit the tissues, and mingle with.the current; but all that we can see, as Dr. Smith has remarked, with the best aid we can get, does but bring us to the confines of the grand operations that go on, of which we are altogether igno- rant.11 We have said, that the main, if not the sole agents of the absorp- tion of solids, are the lymphatics. Almost all admit, that they re- ceive the product of absorption; but all do not admit, that the action a The Philosophy of Health, by Dr. Southwood Smith, vol. i., p. 405, London, 1835. See, also, Dr. W. Sweetser, on the functions of the extreme capillary vessels, in health and disease, in Dissertations on Cynanche Trachealis or Croup, &c, p. 63, Boston, 1823. b See, also, C. H. Schultz, Der Lebensprocess im Blutes, Berlin, 1822. 212 NUTRITION. of taking up solid parts is accomplished immediately by the ab- sorbents. They who think, that a kind of spongy tissue or " paren- chyma" is situate at the radicles of the absorbent vessels, believe that this sponge possesses a vital action of absorption, when bodies, possessing the requisite constitution and consistence, are put in con- tact with it; but they maintain that the solid parts of the body are broken down by the same agents—the extreme arteries—which secreted them, and that, when reduced to the proper fluid condition, they are imbibed by the parenchyma, and conveyed into the lym- phatics. If the existence of this sponge were demonstrated, the above explanation would be the only one, perhaps, that could be admitted; for the sponge could scarcely be conceived to do more than imbibe; it could not break down the solid textures, and reduce them to lymph—the only fluid, which, as we have seen, is ever met with in the lymphatic vessels. But its existence is altogether sup- posititious. Besides, the arrangement has not been invoked in favour of the chyliferous vessels, which are so analogous in their organiza- tion and functions to the lymphatics. It has not been contended, that the arteries of the intestinal canal form the chyle from the ali- mentary matters in the small intestine, and that the office of the chy- liferous vessels is restricted to the reception of this chyle, imbibed and brought in contact with their radicles by this ideal sponge or parenchyma. We have before shown, that there is every reason for the belief, that a vital action of selection and elaboration exists at the very radicles of the chyliferous vessels; and the same may be inferred of the radicles of the lymphatics. The great difficulty is in believing how either exhaling artery, or absorbing lymphatic can reduce the solid matter—of bone, for example—to the necessary constitution and consistence to enter the lymphatics; but we can conceive, that the latter as readily as the former, by virtue of its vital properties— for the operation must be admitted by all to be vital—and by means of its contained fluid, may soften the solid so as to admit of its being received into the vessel. We leave then, wholly unexplained, the mysterious operation by which these absorbents are enabled to reduce to their elements, bone, muscle, tendon, &c, and to recompose them into the form of lymph. Dr. Bostock2 fancifully suggests, that the first step in this series of operations is.the death of the part, by which expres- sion he means, that it is no longer under the influence of arterial action. "It therefore ceases to receive the supply of matter which is essential to the support of all vital parts, and the process of decomposition necessarily commences." The whole of his remarks on this subject, are eminently gratuitous, and appear to be suggested by his extreme unwillingness to ascribe the process to any thing but physical causes. If there is, however, any one phenomenon of the animal economy, which is more manifestly referable to vital action a Physiol., edit. cit. p. 625. NUTRITION. 213 than another, it is the function of nutrition, both as regards the absorption of parts already deposited; and the exhalation of new; and it is wise to confess our utter ignorance of the mode in which it is accomplished. We know that the blood contains most of the principles that are necessary for the nutrition of organs, and that it must contain the elements of all. Fibrine, albumen, fat, osmazome, salts, &c. exist in it, and these are deposited, as the blood traverses the tissues; but whv one should be selected by one set of vessels, as by the exhalants of bone, and another by another set, and in what manner the elements of those, not ready formed in the blood, are brought too-ether, is totally unknown to us. Blood has been de- signated as "liquid flesh,"—chair coulante— but something more than simple transudation through vessels is necessary to form it into flesh and to give it the compound organization of fibrine, gelatine, osmazome, &c—in the form of muscular fibre and cellular mem- brane—which we observe in the muscle. Nothing, perhaps, more clearly exhibits our want of knowledge on the subject than the following vague attempt at solving the mys- tery by one of the most distinguished physiologists of the age. " Some immediate principles, that enter into the composition of the oro-ans or of the fluids, are not found in the blood,—such as gelatine, unc acid, &c. They are consequently formed at the expense of other principles, in the parenchyma of the organs, and by a chemi- cal action, the nature of which is unknown to us, but which is not the less real, and must necessarily have the effect of developing heat and electricity." a , The microscopical researches of Schwann and Schleiden nave led them to affirm, that the new-forming tissues of vegetables origi- nate from a liquid gum or vegetable mucus, and those of animals pro- bably from the liquor sanguinis, after transudation from the capillary vessels. This substance itself, in a state fully prepared for the forma- tion of the tissue, is termed by them intercellular substance and Lyto- blastoma. In the first instance, it exhibits minute granular points, which grow and become more regular and defined from the agglome- ration of the minuter granules around the larger, constituting nuclei or cyloblasts, having, when fully formed, and in fact formed before them, one or more well-defined bodies within them, called nucleoli. From the cyloblasts, cells are formed. A transparent vesicle grows over each, and becomes filled with fluid: this gradually extends and becomes so large that the cytoblast appears like a small body within its walls. The form of the cells is at first irregular, then more regular, and they are alternately, flattened by pressure against each other, assuming different form's in different tissues. Such is their descrip- tion of the vegetable cells from which all the tissues of plants take » Mikroskopische Untersuchungen uber die Uebereinstirnmung in der ftruktur und dem Wachstum der Thiere und" Pflanzen, von Dr. Th Schwann und Schleiden in Muller's Arehiv. p. 137, 1838; and an interesting notice of the same, ra Brit, and For. Med. Review, p. 495, April, 1840. 214 NUTRITION. their origin. In like manner, the tissues of animals are formed from a fluid, in which first nucleoli, then nuclei or cytoblasts, and then cells are developed. The globules of lymph, pus, and mucus, ac- cording to them, are cells with their walls distinct and isolated from each other: horny tissues are cells with distinct walls, but united into coherent tissues; bone, cartilage, &c. are formed of cells whose walls have coalesced; cellular tissues, tendon, &c. are cells which have split into fibres, and muscles, nerves and capillary ves- sels are cells of which both the walls and cavities have coalesced. The component matter of the cells appears to differ from that of the intercellular substance, so that the cells must possess a vital power, by which they not only attract but change the substance brought into contact with them, or in other words, they have a power of self-nutrition. That this is probably independent of the nerves is shown by an experiment of Dr. Sharpey, in which the reproduction of a portion of the tail of a salamander took place, although it was cut off, after the organ had been completely para- lysed by dissecting out at its root a portion of the spinal cord, together with the arches of the vertebra?/ It is the action of nutrition, that occasions the constant fluctua- tions in the weight and size of the body, from the earliest embryo condition till advanced life. The cause of the developement or growth of organs and of the body generally, as well as of the limit, accurately assigned to such developement, according to the animal or vegetable species, is dependent upon vital laws that are unfathom- able. Nor are we able to detect the precise mode in which the growth of parts is effected. It cannot be simple extension, for the obvious reason that the body and its various compartments augment in weight as well as in dimension. In the large trees of our forests we find a fresh layer or ring added each year to the stem, until the full period of developement; and it has been supposed that the growth of the animal body may be effected in a similar manner, both as regards its soft and harder materials,—that is, by layers deposited externally. That the long bones lengthen at their extre- mities is proved by an experiment of Mr. Hunter. Having exposed the tibia of a pig, he bored a hole into each extremity of the shaft, and inserted a shot. The distance between the shots was then accurately taken. Some months afterwards, the same bone was examined, and the shots were found at precisely their original dis- tance from each other; but the extremities of the bone had extended much beyond their first distance from them. The flat bones also increase by a deposition at their margins, and the long bones by a similar deposition at their periphery,—addi- tional circumstances strongly exhibiting the analogy between the successive developement of animals and vegetables. a Ancell, Lectures on the Physiology, &c. of the Blood, in Lond, Lancet p. 157, April 25, 1S40, NUTRITION. 215 Exercise or rest, freedom from, or the existence of, pressure produce augmentation of the size of organs or the contrary; and there are certain medicines, as iodine, which occasion the emacia- tion of particular organs only—as of the female mamma?. The effects of disease is likewise, in this respect, familiar and striking.* The ancients had noticed the changes effected upon the body by the function we are considering, and attempted to estimate the period at which a thorough conversion might be accomplished, so that not one of its quondam constituents should be present. By some, this was supposed to be seven years; by others, three. It is hardly necessary to say, that in such a calculation we have nothing but conjecture to guide us. The nutrition of the body and of its parts varies, indeed, according to numerous circumstances. It is not the same during the period of growth as subsequently, when the absorption and deposition are balanced, so far at least as concerns . the augmentation of the body in one direction. Particular organs have, likewise, their period of developement, at which time the nu- trition of such parts must necessarily be more active,—the organs of generation, for example, at the period of puberty; the enlarge- ment of the mamma?, in the female; the appearance of the beard and the amplification of the larynx in the male, &c: all these changes occur after a determinate plan. The activity of nutrition appears to be increased by exercise, at least in the muscular organs; hence the well-marked muscles of the arm in the prize-fighter, of the legs in the dancer, &c. The muscles of the male are, in general, much more clearly defined ; but the difference be- tween those of the hard-work- ing female and of the inactive male may not be very apparent. There are several textures of the body that do not experi- ence nutrition, but, when once deposited, appear to remain permanently, such as the epi- dermis, the nails, the teeth, the colouring matter of the skin, and, it is presumed, the carti- lages,—especially the inter- articular. The most active in their nutrition are the glands, muscles, and skin, which alter their character—as to size, colour and consistence—with great Rapidity; whilst the Fig. 135. Tattooed Head of a New Zealand Chief. a See the author's General Therapeutics, p. 319, Philad. 1836. 216 NUTRITION. tendons, fibrous membranes, bones, &c, are much less so, and are altered more slowly by the effect of disease. A practice, which prevails amongst certain professions and people, would seem at first sight to show that the nutrition of the skin cannot be energetic. Sailors are frequently in the habit of forcing gunpowder through the cuticle with a pointed instrument, and of figuring the initials of their names upon the arm in this manner: the particles of the gunpowder are thus driven into the cutis vera and remain for life. The operation of tattooing, or of puncturing and staining the skin, prevails in many parts of the globe and espe- cially in Polynesia, where it is looked upon as greatly ornamental. The art is said to be carried to its greatest perfection in the Washing- ton or New Marquesas Islands ;a where the wealthy are often covered with various designs from head to foot; subjecting themselves to a most painful operation for this strange kind of personal decoration. The operation consists in puncturing the skin with some rude instru- ment, according to figures previously traced upon it, and then rubbing into the punctures a thick dye, frequently composed of the ashes of the plant that furnishes the colouring matter. The marks, thus made, are indelible. Magendieb asks:—" How can we recon- cile this phenomenon with the renovation, which, according to authors," (and he might have added, according to himself,) "hap- pens to the skin?" It does not seem to us to be in any manner connected with the nutrition of the skin. The colouring matter is an extraneous substance, which takes no part in the changes con- stantly going on in the tissue in which it is imbedded ; and the cir- cumstance seems to afford a negative argument in favour of venous absorption. Had the substance possessed the necessary tenuity it would have entered the veins like other colouring matters; but the particles are too gross for this, and hence they remain free from all absorbent influence. CHAPTER VI. CALORIFICATION. The function, which we have now to consider, is one of the most important to organic existence, and one of the most curious in its causes and results. It has, consequently, been an object of inte- resting examination with the physiologist, both in animals and plants, and as it has been presumed, by a large class of speculatists, to be greatly owing to respiration, it has been a favourite topic with the chemist also. Most of the hypotheses, devised for its expla- a Lawrence's Lectures on Physiology, &c., p. 411, Lond. 1819. b Precis, &c. edit. cit. ii. 483. TEMPERATURE OF ANIMALS. 217 nation, have, indeed, been of a chemical character; and hence it will be advisable to premise a few observations regarding the physical relations of caloric or the matter of heat,—an imponderable body, according to common belief, which is generally distributed throughout nature. It is this that constitutes the temperature of bodies, —by which is meant, the sensation of heat or cold, which we ex- perience, when bodies are touched by us; or the height at which the mercury is raised or depressed by them, in the instrument called the thermometer;—the elevation of the mercury being caused by the caloric entering between its particles, and thus adding to its bulk; and the depression being produced by the abstraction of caloric. Caloric exists in bodies in two states;—in the free, uncombined or sensible, and in the latent or combined. In the latter case, it is intimately united with the other elementary constituents of bodies, and is neither indicated by the feelings nor by the thermometer. It has,, consequently, no agency in the temperature of bodies ; but, by its proportion to the force of cohesion, it determines their con- dition ;—whether they shall be solid, liquid or gaseous. In the for- mer case, caloric is simply interposed between the molecules, and is incessantly disengaged, or abstracted from surrounding bodies; and, by impressing the surface of the body or by acting upon the thermometer, it indicates to us their temperature. Equal weights of the same body, at the same temperature, con- tain the same quantities of caloric; but equal weights of different bodies, at the same temperature, have by no means the same quan- tities. The quantity, which one body contains, compared with that in another is called its specific caloric, or specific heat; and the power or property, which enables bodies to retain different quan- tities of caloric, is called capacity for caloric. If a pound of water, heated to 156°, be mixed with a pound of quicksilver at 40°, the resulting temperature is 152°,—instead of 98°, the exact mean. The water, consequently, must have lost four degrees of temperature, and the quicksilver gained 112°; from which we deduce, that the quantity of caloric, capable of raising one pound of mercury from 40° to 152° is the same as that required to raise one pound of water from 152° to 156°; or, in other words, that the same quantity of heat, which raises the temperature of a pound of water four de- grees, raises the same weight of mercury one hundred and twelve degrees. Accordingly, it is said, that the capacity of water for heat is to that of mercury, as 28 to 1 ; and that the specific heat is twenty-eight times greater. All bodies are capable of giving and taking free caloric, and con- sequently, all have a temperature. If the quantity given off be great, the temperature of the body is elevated. If it take heat from the thermometer, it is cooler than the instrument. In inorganic bodies, the disengagement of caloric is induced by various causes; such as electricity, friction, percussion, compres- sion, the change of condition from a fluid to a solid state ; and by vol. n. 19 218 CALORIFICATION. chemical changes, giving rise to new compounds, so that the ca- loric, which was previously latent, becomes free. If, for example, two substances, each containing a certain amount of specific heat, unite, so as to form a compound, whose specific heat is less, a por- tion of caloric must be set free, and this will be indicated by a rise in the tempeature. It is this principle, which is chiefly concerned in some of the theories of calorification. The subject of the equilibrium and conduction of caloric has already been treated of, under the sense of touch, (vol. i. p. 101); where several other topics were discussed, that bear more or less upon the present inquiry. It was there stated, that inorganic bodies speedily attain the same temperature, either by radiation or conduction; so that the different objects in an apartment will exhibit the same degree of heat by the thermometer, but the temperature of animals, being a vital operation, they retain the degree of heat peculiar to them, with but little modification from external temperature. There is a difference, however, in this respect, sufficient to cause the partition of animals into two great divisions—the warm-blooded and the cold-blooded; the for- mer comprising those whose temperature is high, and hut little influenced by that of external objects;—the latter those whose temperature is greatly modified by external influences. The range of the temperature of the warm-blooded—amongst which are all the higher animals—is limited ; but of the cold-blooded ex- tensive/1 The following table exhibits the peculiar temperature of various animals in round numbers;—that of man being 98° or 100°, when taken under the tongue. The temperature in the axilla is something less. In the latter situation, Dr. Edwardsb found it to vary, in twenty adults, from 96° to 99° Fahrenheit, the mean being 97°.5. Animals. Arctic fox,..... Arctic wolf,..... Squirrel, ..... Hare,...... Whale,...... Arctomys citillus, zizil,—in summer, Do. when torpid, Goat, ...... Bat, in summer, .... Musk,...... Marmota bbbac,—Bobac, - House mouse, .... Arctomys marmota, marmot—in summer, Do. when torpid, a Turner's Elements of Chemistry, 5th Amer. Edit., by Prof. F. Bache, from 5th Lon- don, p. 5, Philad. 1835. b De l'lnfluence des Agens Physiques, &c, Paris, 1824; and Hodgkin and Fisher's translation, Lond. 1832. c Parry's Second Voyage to the Arctic Regions. d Nov. Species Quadruped, de Glirium Ordine, Erlang. 1774. e An Account of the Arctic Regions, Edinb. 1820. f Bibliotheque Univers. xvii. 294. 105 104 Observers. Temperature. Capt. Lyon.c 107 Do. ) Pallas.d C Do. ) Scoresby.e £ Pallas. 103 Pallas. 80 to 84 Prevost and Dumas/ 103 £: \ i» Do. 101 or 102 Do. 101 . Do. 101 or 102 Do. 43 TEMPERATURE OF ANIMALS. 219 Rabbit,.....- - - Delaroche. 100*?n104 Polar Bear,......- Capt. Lyon. 100 D0 iootoio3 Sheep,........ Do. k Ox ..... Do. J Guinea-pig, ." .".---- Delaroche. 100 to 102 iZ7,ysgli\ : : : : : '- »*: 11 Young wolf,....... Do. b 96 Fringilla arctica, Arctic finch, - - - pn1"1' > HI Rubecola, redbreast,..... Pallas. $ Fringilla linaria, lesser red poll, - - - Do. 11U or in Falco palumbarius, goshawk, - ' - - - Do. ( HO Caprimulgus Europceus, European goat-sucker, Do. J Emberiza nivalis, snow-bunting, - Do. IU9 to 11U Falco lanarius, lanner,..... *r0, ^ Fringilla carduelis, goldfinch, ... - Do. r Corvus corax, raven, .... - Despretz. > Turdus, thrush, (of Ceylon,) - J<-P^7 S Tetrao perdrix, partridge, .... Pallas. J Anas clypeata, shoveler, ----- Do. Tringa pugnax, ruffe,..... Do. Scolopax limosa, lesser godwit, ... Do. Tetrao tetrix, grouse,..... Do. \, jqq Fringilla brumalis, winterfinch, - - - Do. Loxia pyrrhula, ....-- Do. Falco nisus, sparrowhawk, ... - Do. Vultur Barbatus, - - - - - - Do. Anser pulchricollis, .... - Do. \ Calymbus auritus, dusky grebe, ... Do. f jq7 Tringa vanellus, lapwing, (wounded) - - Do. I Tetrao lagopus, ptarmigan, ... - Do. ; Fringilla domestica, house-sparrow, - - Do. iu/to in Striz passerina, little owl, - - Do. ^ Hamatopus estralagus, sea-pie, ... Do. F Anas penelope, wigeon,..... jr°- / Anas strcpera, gadwalL ----- Do. \ Pelecanus carbo, ------ °- Falco ossifragus, sea-eagle, - T)° V 105 Falica atra, coot,...... °" C Anas acuta, pintail-duck, .... Do. J Falco mihus, kite, (wounded) . - - - Do. / 104 Merops apiaster, bee-eater, .... ■**?■' < r. _ . iviartine. j iroose, ------- t\ r Hen,........ "°- > 103 to 107 r» . - - Do. I Dove, .------ r»i t\ i . Do. ) Duck, -..... p lkg ^ Ardea stellaris,...... D > 103 Falco albicollis, ------ T) ' \ Picas major, - ------ SchulJ;e. 89 to 91 Cossus hgmperda,......!p ^ fotedoMarmorata,' -" -' -' -" -' RnSphL- 74 * Med. and Philos. Essays, Lond. 1740; and De Similibus Animalibus et Animal. Colore, &c, Lond. 1740. b Nov. Comment. Acad. PetropoL xiii. 419. c Annales de Chimie, xxvi. 337, Amst. 1824. a Edinb. Philos. Journal, Jan. 1826. . . • Grundriss der Physiol., &c, band i. 166; Tiedemann's Traite de Physiologie par Jourdan, p. 438, Paris, 1831; and P. H. Berard, art. Chaleur Ammale, in Diet, de Med, 2de edit. viL 177, Paris, 1834. 220 CALORIFICATION. According to the above table it will be observed, that the inha- bitants of the Arctic regions—whether belonging to the class of mammalia or birds—are among those whose temperature is highest. That of the Arctic fox is, indeed, probably higher than the amount given in the table, being taken after death, when the temperature of the air was as low as —14° of Fahrenheit, and when loss of heat may be supposed to have taken place rapidly. The temperature of the smaller insects it is, of course, impracti- cable to indicate; but we can arrive at an approximation in those that congregate in masses, as the bee and the ant; for it is impos- sible to suppose, with Maraldi, that the augmented temperature is' dependent upon the motion and friction of the wings and bodies of the busy multitudes. Juch,a found that when the temperature of the atmosphere was—18° of Fahrenheit, that of a hive of bees was 44°: in an ant-hill, the thermometer stood at 68° or 70°, when the temperature of the air was 55°; and at 75°, when that of the air was 66°; and Hausmannb and Renggerc saw the thermometer rise, when put into narrow glasses in which they had placed scarabsei and other insects/1 Berthold detected the elevation of heat only when several insects were collected together, not in one isolated from the rest. This Mr. Newport2 affirms, must have arisen from his having ascertained the temperature only whilst the insect was in a state of rest: for Mr. Newport found, that although during such a state, the tempera- ture of the insect was very nearly or exactly that of the surrounding medium, yet when the insect was excited or disturbed, or in a state of great activity from any cause, the thermometer rose in some instances, even to 20° Fahr. above the temperature of the atmo- sphere,—for instance to 91°, when the heat of the air was 71°. The power of preserving their temperature within certain limits, is not, however, possessed exclusively by animals. The heat of a tree, examined by Mr. Hunter,f was found to be always several degrees higher than that of the atmosphere, when the temperature of the air was below 56° of Fahr.; but it was always several degrees below it when the weather was warmer. Some plants develope a considerable degree of heat, during the period of blooming. This was first noticed by De Lamarck^ in the Arum italicum. In the Arum cordifolium, of the Isle of Bourbon, Hubert found, when the temperature of the air was 80°, that of the spathe or sheath was as high as 134°; and Bory De St. Vincenth observed a similar eleva- * Ideen zu einer Zoochemie, i. 90. b De Animal. Exsanguium Respiratione, p. 65. c Physiologische Untersuchung uber die Insecten, p. 40, Tubing. 1817. d Tiedemann, op. citat. p. 511. e Philosoph. Transact, for 1837, part ii. p. 259. See Dr. W. B. Carpenter, Principles of General and Comparative Physiology, p. 372, Lond. 1839 ; and some experiments proving the same point in Dr. M. Paine's Medical and Physiological Commentaries, ii. 76, New York, 1840. 1 Philos. Transact. 1775 and 1778. s Encyclop. Method, iii. 9. h Voyage dans les Quatre Principales lies des Mers d'Afrique, ii. 66. TEMPERATURE OF ANIMALS. 221 tion, although in a less degree, in the Arum esculenium, esculent arum or Indian kale." The animal body is so far influenced by external heat as to rise or fall with it; but the range, as we have already remarked, is limited in the warm-blooded animal,—more extensive in the cold- blooded. Dr. Currie found the temperature of a man plunged into sea-water at 44° sink, in the course of a minute and a half after immersion, from 98° to 87°; and, in other experiments, it descended as low as 85°, and even to 83°.b It was always found, however, that, in a few minutes, the heat approached its previous elevation; and in no instance, could it be depressed lower than 83°, or 15° below the temperature at the commencement of the operation. Similar experiments have been performed on other warm-blooded animals. Hunter found the temperature of a common mouse to be 99°, when that of the atmosphere was 60°: when the same animal was exposed, for an hour, to an atmosphere of 15°, its heat had sunk to 83° ;c but the depression could be carried no farther. He found, also, that a dormouse,—whose heat in an atmosphere at 64°, was 8H0,—when put into air, at 20°, had its temperature raised, in the course of half an hour to 93°; an hour after, the air being at 30°, it was still 93°; another hour after, the air being at 19°, the heat of the pelvis was as low as 83°,—an experiment, which strongly proves the great counteracting influence exerted, when animals are exposed to an unusually low temperature. In this experiment, the dormouse had maintained its temperature about 70° higher than that of the surrounding medium, and for the space of two hours and a half. In the hibernating torpid quadruped the reduction of tempera- ture, during their torpidity, is considerable. Jennerd found the temperature of a hedgehog, in the cavity of the abdomen, towards the pelvis, to be 95°, and that of the diaphragm 97° of Fahrenheit, in summer, when the thermometer in the shade stood at 78°; whilst in the winter, the temperature of the air being 44°, and the animal torpid, the heat in the pelvis was 45°, and of the diaphragm 48|-°. When the temperature of the atmosphere was at 26°, the heat of the animal, in the cavity of the abdomen, where an incision was made, was reduced as low as 30° ; but—what singularly exhibits the power, possessed by the system, of regulating its temperature,— when the same animal was exposed to the cold atmosphere of 26° for two days, its heat, in the rectum, was raised to 93°, or 67° above that of the atmosphere. At this time, however, it was lively and active, and the bed, on which it lay, felt warm. In the cold-blooded animal, we have equal evidence of the gene- ration of heat. Hunter found, that the heat of a viper, placed a Sir J. E. Smith, Introduction to the Study of Botany, 7th edit., by Sir W. J. Hooker, p. 47, Lond. 1833 ; Tiedemann, p. 492 ; and Carpenter, op. citat. p. 368. b Philosoph. Transact, for 1792, p. 199. c Ibid. 1778, p. 21. d Hunter on the Animal Economy, p. 99, 2d edit., Lond. 1792, or Owen's edit, in Bell's Select Med. Lib. p. 165, Philad. 1840. See, also, a paper on the Hibernation of the Myoxus Glis, by J. J. Czermak, in Med. Jahrb. des K. K. Oester. Staates, b. xv. s. 277, Wien. 1836 ; and Mailer's Handbuch, u. s. w., Baly's translation, p. 76, Lond. 1838. 19* 222 CALORIFICATION. in a vessel at 10°, was reduced, in ten minutes, to 37°; in the next ten minutes, the temperature of the vessel being 13°, it fell to 35°; and in the next, ten minutes, the vessel being at 20°, to 31°.a In frogs, he was able to lower the temperature to 31°; but beyond this point it was not possible to lessen the heat, without destroying the animal. In the Arctic regions, the animal temperature appears to be steadily maintained, notwithstanding the intense cold that prevails; and we have already seen, that the animals of those hyperborean latitudes possess a more elevated temperature than those of more genial climes. In the enterprising voyages, undertaken by the British government for the discovery of a northwest passage, the crews of the ships were frequently exposed to the temperature of —40° or—50° of Fahrenheit's scale; and the same thing happened during the disastrous campaign of Russia in 1812, in which so many of the French army perished from cold. The lowest tempera- ture noticed by Captain Parryb was —55° of Fahrenheit. Captain Franklin,0 on the northern part of this continent, observed the thermometer on one occasion—Feb. 7, 1827,—as low as —58° of Fahrenheit; and M. Von Wrangeld states that, in January, on the north coast of Siberia, the cold reaches —59° of Fahrenheit; but the greatest observed natural cold was marked by Captain Back6 in his expedition to the Arctic regions: on the 17th of January, 1834, the thermometer stood at —70° of Fahrenheit, or 102° below the freezing point! During the second voyage of Captain Parry/ the following temperatures of animals, immediately after death, were taken prin- cipally by Captain Lyon. Temperature of the 1821. Animal. Atmosphere. Nov. 15. An Arctic fox ... 106|° - - - — 14° Dec. 3. Do. .... 101£ - . . _ 5 Do. .... 100 - - . — 3 11. Do......• 101J - - . _ 21 15. Do...... 99| - - - _ 15 17. Do......98 - - . _ 10 19. Do......99| - - - — 14 1822. Jan. 3. Do. - - - - 104£ - - - — 23 9. A white hare - - - - 101 - - . —- 21 10. An Arctic fox - - - - 100 - . . _ 15 17. Do. - - - - - 106 . . . _ 32 24. Do......103 - . . _ 27 Do......103 . ." _ 27 Do......102 . . . _ 25 27. Do. - ... 101 . . . _ 32 Feb. 2. A wolf.....105 . . . _ 27 * Op. citat. b Journal of a.Voyage for the Discovery of a Northwest Passage, Amer Edit p 130 Philad. 1821. ' c Narrative of a Second Expedition to the Shores of the Polar Sea &c Amer Edit p. 24.5, Philad. 1835. d Reise des Kaiserlich. Russischen Flotten, Lieutenants Ferdinand Von Wren?eL Langs der Nordkiiste von Siberien, u. s. w., Berlin, 1839. e Narrative of the Arctic Land Expedition to the mouth of the Great Fish river &c. in the years 1833, 1834, and 1835, Lond. 1836. f Op. citat. p. 157. EFFECTS OF DEPRESSED TEMPERATURE. 223 These animals must, therefore, have to maintain a temperature at least 100° higher than that of the atmosphere, throughout the whole of winter; and it would appear as if the counteracting energy becomes proportionately greater as the temperature is more depressed. It is, however, a part of their nature to be constantly eliciting this unusual quantity of caloric, and therefore they do not suffer. Where animals, not so accustomed, are placed in an un- usually cold medium, the efforts of the system rapidly exhaust the nervous energy; and when this becomes so far depressed as to in- terfere materially with the function of calorification, which we shall find is to a certain extent under the nervous influence, the tempera- ture sinks, and the individual dies lethargic—or, as if struck with apoplexy. The ship Endeavour, being on the coast of Terra del Fuego, on the 21st of December, 1769, Messrs. Banks, Solander, and others were desirous of making a botanical excursion upon the hills on the coast, which did not appear to be far distant. The party, con- sisting of eleven persons, were overtaken by night on the hills, during extreme cold. Dr. Solander, who had crossed the mountains which divide Sweden from Norway, knowing the almost irresistible de- sire for sleep produced by exposure to great cold, more especially when united with fatigue, enjoined his companions to keep moving, whatever pains it might cost them, and whatever might be the re- lief promised by an indulgence in rest. "Whoever sits down," said he, " will sleep, and whoever sleeps will wake no more." Thus admonished, they set forward, but whilst still upon the bare rock, and before they had got among the bushes, the cold suddenly became so severe as to produce the effects that had been dreaded. Dr. Solander himself was the first who found the desire irresistible, and insisted on being suffered to lie down. Mr. Banks, (afterwards Sir Joseph,) entreated and remonstrated in vain. The doctor lay down upon the ground, although it was covered with snow; and it was with the greatest difficulty that his friend could keep him from sleeping. Richmond, one of the black servants, began to linger and to suffer from the cold, in the same manner as Dr. Solander. Mr. Banks, therefore, sent five of the company forward to get a fire ready at the first convenient place they came to; and himself, with four others, remained with the doctor and Richmond, whom, partly by persuasion and partly by force, they carried forward; but when they had got through the birch and swamp, they both declared they could go no farther. Mr. Banks had again recourse to entreaty and expostulation, but without effect. When Richmond was told, that if he did not go on, he would, in a short time, be frozen to death, he answered, that he desired nothing but to lie down and die. Dr. Solander was not so obstinate, but was willing to go on, if they would first allow him to take some sleep, although he had before ob- served, that to sleep was to perish. Mr. Banks and the rest of the party found it impossible to carry them, and they were consequently suffered to sit down, being partly supported by the bushes, and, in 224 CALORIFICATION. a few minutes they fell into a profound sleep. Soon after, some of the people, who had been sent forward, returned with the welcome intelligence, that a fire had been kindled about a quarter of a mile farther on the way. Mr. Banks then endeavoured to rouse Dr. Solander, and happily succeeded, but, although he had not slept five minutes, he had almost lost the use of his limbs, and the soft parts were so shrunk, that his shoes fell from his feet. He'con- sented to go forward with such assistance as could be given him, but no attempts to relieve Richmond were successful. He, with another black left with him, died. Several others began to lose their sensibility, having been exposed to the cold near an hour and a half, but the fire recovered them.1 The preceding history is interesting in another point of view be- sides the one for which it was more especially adduced. Both the individuals, who perished, were blacks, and it has been a common observation, that they bear exposure to great heat with more impu- nity, and suffer more from intense cold, than the white variety of the species. As regards inorganic bodies, it has been satisfactorily shown, that the phenomena of the radiation of caloric are connected with the nature of the radiating surface; and that those surfaces, which radiate most, possess, in the highest degree, the absorbing power; in other words, bodies that have their temperatures most readily raised by radiant heat are those that are most easily cooled by their own radiation. In the experiments of Professor Leslieb it was found, that a clean metallic surface produced an effect upon the thermometer equal to 12 ; but when covered with a thin coat of glue its radiating power was so far increased as to produce an effect equal to 80 ; and, on covering it with lamp-black, it became equal to 100. We can thus understand why, in the negro, there should be a greater expense of caloric than in the white, owing to the greater radiation: not because as much caloric may not have been elicited as in the white. In the same manner we can under- stand that, owing to the greater absorbing power of his skin, he may suffer less from excessive heat than the white; and this is per- haps the great use of the dark rete mucosum. To ascertain, whether such be the fact, tke following experiments were instituted by Sir Everard Home.0 He exposed the back of his hand to the sun at twelve o'clock, with a thermometer attached to it, another thermometer being placed upon a table with the same exposure. The temperature, indicated by that on his hand, was 90°; by the other, 102°. In forty-five minutes blisters arose, and coagulable lymph was thrown out. The pain was very severe. In a second experiment, he exposed his face, eyelids, and the back of his hand to water heated to 120°; in a few minutes they became painful; and, when the heat was farther increased, he was unable to bear it; a See, on the effects of Cold, Sir H. Halford, in Lond. Med. Gazette, for March 11, 1837, p. 902. * On Heat, Edinb. 1804; and Dr. Stark, in Philosoph. Transact, part ii. for 1833. c Lect. on Comp. Anat. iii. 217, Lond. 1823. EFFECTS OF DEPRESSED TEMPERATURE. 225 but no blisters were produced. In a third experiment, he exposed the backs of both hands, with a thermometer upon each, to the sun's rays. The one hand was uncovered ; the other had a covering of black cloth, under which the ball of the thermometer was placed. After ten minutes, the degree of heat of each thermometer was marked, and the appearance of the skin examined. This was repeated at three different times. The first time, the thermometer under the cloth stood at 91°, the other thermometer at 85°; the second time, they indicated respectively 94° and 91° ; and the third time, 106° and 98°. In every one of these trials, the skin, that was uncovered, was scorched, whilst the other had not suffered in the slightest degree. From all his experiments, Sir Everard concludes, that the power of the sun's rays to scorch the skin of animals is destroyed, when applied to a black surface ; although the absolute heat, in conse- quence of the absorption of the rays, is greater. When cold is applied to particular parts of the body, the heat of those parts sinks lower than the minimum of depressed temperature. Although Hunter was unable to heat the urethra one degree above the maximum of elevated temperature of the body, he succeeded in cooling it 29° lower than the minimum of depressed temperature, or to 58°. He cooled down the ears of rabbits until they froze; and when thawed, they recovered their natural heat and circulation. The same experiment was performed on the comb and wattles of a cock. Resuscitation was, however, in no instance practicable where the whole body had been frozen.1 The same observer found, that the power of generating heat, when exposed to a cooling influ- ence, was possessed even by the egg. An egg, which had been frozen and thawed, was put into a cold mixture along with one newly laid. The latter was seven minutes and a half longer in freezing than the other. In another experiment, a fresh-laid egg, and one which had been frozen and thawed, were put into a cold mixture at 15°; the thawed one soon rose to 32°, and began to swell and congeal; the fresh one sank to 29^°, and, in twenty-five minutes after the dead one, it rose to 32°, and began to swell and freeze. All these facts prove, that when the living body is exposed to a lower temperature than usual, a counteracting power of calorifica- tion exists ; but that, in the human species, such exposure to cold is incapable of depressing the temperature of the system lower than about 15° beneath the natural standard. In fish, the vital principle can survive the action even of frost. Captain Franklin found, that those which they caught in Winter Lake, froze as they were taken out of the net; but if, in this completely frozen state, they were thawed before the fire, they recovered their animation. This was especially the case with a carp, which recovered so far as to leap about with some vigour after it had been frozen for thirty-six hours.b a Sir E. Home's Lect. &c. iii. 438. b Sec, also, Dr. W. B. Carpenter, art. Life, in Cyclop, of Anat. and Physiol. Sept. 1840. 226 CALORIFICATION. On the other hand, when the living body is exposed to a tempera- ture greatly above the natural standard, an action of refrigeration is exerted ; so that the animal heat cannot rise beyond a certain num- ber of degrees;—to a much smaller extent in fact than it is capable of being depressed by the opposite influence. Boerhaavea maintained the strange opinion, that no warm-blooded animal could exist in a temperature higher than that of its own body. In some parts of Virginia, there are days in every summer, in which the thermometer reaches 98° of Fahrenheit; and in other parts of this country, it is occasionally much higher. The meteorological registers show it to be at times as high as 108° at Council Bluffs, in Missouri; at 104° in New York ; and at 100° in Michigan;0 whilst in most of the states, on some days of summer, it reaches 96° or 98°. At Sierra Leone, Messrs. Watt and Winterbottomc saw the thermometer frequently at 100°, and even as high as 102° and 103°, at some distance from the coast. Adamson saw it at Senegal as high as 108^°. Brydone affirms, that when the sirocco blows in Sicily the heat rises to 112°.d Dr. Chalmers observed a heat of 115oe in South Carolina; Humboldt' of 110° to 115° in the Llanos or Plains near the Orinoco; and Captain Tuckey asserts, that on the Red Sea he never observed the thermometer at midnight under 94°; at sunrise under 104°; or at mid-day under 112°. In British India it is asserted to have been seen as high as 130°.s So long ago as 1758, Governor Ellis*1 of Georgia had noticed how little the heat of the body is influenced by the external atmosphere. "I have frequently," he remarks, "walked an hundred yards under an umbrella with a thermometer suspended from it by a thread, to the height of my nostrils, when the mercury has rose to 105°, which is prodigious. At the same time I have confined this instrument close to the hottest part of my body, and have been astonished to observe, that it has subsided several degrees. Indeed I never could raise the mercury above 97° with the heat of my body." Two years after the date of this communication, the power of resisting a much higher atmospheric temperature was discovered by acci- dent. MM. Duhamel and Tillet,' in some experiments for destroy- ing an insect, that infested the grain of the neighbourhood,—having a Observatio docet nullum animal quod pulmones habent, posse in aere vivere, cujus cadem est temperies cum suo sanguine; Element. Chemiae. i. 275, Lug. Bat. 1732 ; and Haller, Element. Physiologic, torn. ii. ■> Meteorological Register, for the years 1822, 1823, 1824, and 1825, from observa- tions made by the surgeons at the military posts of the United States. See, also, a similar register for the year 1826, 1827, 1828, 1829, and 1830, Philad. 1840. c Account of the Native Africans, vol. i, p. 32 and 33. d Lawrence's Lectures on Physiology, &c., p. 306, London, 1819. e Account of the Weather and Diseases of South Carolina, London, 1776. f Tableau Physique des Regions Equatoriales. s Prof. Jameson, in British India, Amer. edit. iii. 170, New York, 1832. For an account of the highest temperature, observed in different climates, see the author's "Elements of Hygiene," p. 96; art. Atmosphere, by the author in the Cyclopaedia of Practical Medicine, Philadelphia, 1836; Annuaire du Bureau des Longitudes, 1825; and Elemens de Physique, par Pouillet, iv. 637, 2de edit. Paris, 1832. h Philosophical Transactions, 1758, p. 755. ' Memoir, de PAcademie des Sciences de Paris, 1762, p. 186. EFFECTS OF ELEVATED TEMPERATURE. 227 occasion to use a large public oven, on the same day in which bread had been baked in it, were desirous of ascertaining its temperature. This they endeavoured to accomplish by introducing a thermometer into the oven at the end of a shovel. On being withdrawn, the thermometer indicated a degree of heat considerably above that of boiling water; but M. Tillet, feeling satisfied that the thermometer had fallen several degrees in approaching the mouth of the oven, and seeming to be at a loss how to rectify the error, a girl,—one of the servants of the baker, and an attendant on the oven,—offered to enter and mark with a pencil the height at which the thermometer stood within the oven. The girl smiled at M. Tillet's hesitation at her proposition, entered the oven, and noted the temperature to be 260° of Fahrenheit. M. Tillet, anxious for her safety, called upon her to come out; but she assured him she felt no inconvenience from her situation, and remained ten minutes longer when the ther- mometer had risen to 280° and upwards. She then came out of the oven, with her face considerably flushed, but her respiration by no means quick or laborious. These facts excited considerable interest, but no farther experi- ments appear to have been instituted, until, in the year 1774, Dr. Geo. Fordyce, and Sir Charles Blagdena made their celebrated trials with heated air. The rooms, in which these were made, were heated by flues in the floor. Having taken off his coat, waistcoat, and shirt, and being provided with wooden shoes, tied on with list, Dr. Fordyce went into one of the rooms, as soon as the thermometer indicated a degree of heat above that of boiling water. The first impression of this heated air upon his body was exceedingly disa- greeable ; but, in a few minutes, all uneasiness was removed by copious perspiration. At the end of twelve minutes, he left the room very much fatigued, but not otherwise disordered. The thermometer had risen to 220°. In other experiments, it was found, that a heat even of 260° could be borne with tolerable ease. At this tempera- ture, every piece of metal was intolerably hot; small quantities of water, in metallic vessels, quickly boiled; and streams of moisture poured down over the whole surface of his body. That this was merely the vapour of the room, condensed by the cooler skin, was proved by the fact, that when a Florence flask, filled with water of the same temperature as the body, was placed in the room, the vapour condensed in the like manner upon its surface, and ran down in streams. Whenever the thermometer was breathed upon, the mercury sank several degrees. Every expiration—especially if made with any degree of violence—communicated a pleasant im- pression of coolness to the nostrils, scorched immediately before by the hot air rushing against them when they inspired. In the same manner, their comparatively cool breath cooled their fingers, when- ever it reached them. " To prove," says Sir Charles Blagden, "that there was no fallacy in the degree of heat shown by the thermo- * Philosophical Transactions for 1775, p. 111. 228 CALORIFICATION. meter, but that the air, which we breathed, was capable of pro- ducing all the well-known effects of such an heat on inanimate matter, we put some eggs and beef-steak upon a tin frame, placed near the standard thermometer, and farther distant from the cockle than from the wall of the room. In about twenty minutes, the eggs were taken out roasted quite hard; and in forty-seven minutes, the steak was not only dressed, but almost dry. Another beef-steak was rather overdone in thirty-three minutes. In the evening, when the heat was still greater, we laid a third beef-steak in the same place; and as it had now been observed, that the effect of the heated air was much increased by putting it in motion, we blew upon the steak with a pair of bellows, which produced a visible change on its surface, and seemed to hasten the dressing: the greatest part of it was found pretty well done in thirteen minutes." In all these experiments, and similar ones were made in the fol- lowing year, by Dobson,1 of Liverpool, the heat of the body, in air of a high temperature, speedily reached 100°; but exposure to 212°, and more, did not carry it higher. These results are not, how- ever, exactly in accordance with those of MM. Berger and Dela- roche,1" deduced from experiments performed in 1806. Having exposed themselves, for some time, to a stove,—the temperature of which was 39° of Reaumur or 120 of Fahrenheit,—their tempera- ture was raised 3° of Reaumur, or 6f ° of Fahrenheit; and M. De- laroche found, that his rose to 4° of Reaumur, or 9° of Fahrenheit, when he had remained sixteen minutes in a stove, heated to 176° of Fahrenheit. According to Sir David Brewster,c—the distinguished sculptor, Chantry, exposed himself to a temperature yet higher. The furnace which he employs for drying his moulds, is about 14 feet long, 12 feet high, and 12 feet broad. When raised to its highest tempera- ture, with the doors closed, the thermometer stands at 350°, and the iron floor is red-hot. The workmen often enter it at a temperature of 340°, walking over the iron floor with wooden clogs, which are, of course, charred on the surface. On one occasion, Mr. Chantry, accompanied by five or six of his friends, entered the furnace, and after remaining two minutes, they brought out a thermometer, which stood at 320°. Some of the party experienced sharp pains in the tips of their ears, and in the septum of the nose, whilst others felt a pain in the eyes. In some experiments of Chabert, who exhibited his powers as a " Fire King," in this country as well as in Europe, he is said to have entered an oven with impunity, the heat of which was from 400° to 600° of Fahrenheit. Experiments have shown, that the same power of resisting excessive heat is possessed by other animals. Drs. For- dyce and Blagden shut up a dog in a room, the temperature of which * Philosophical Transactions for 1775, p. 463. b Exper. sur les Effects qu'une forte Chaleur produit sur l'Economie, Paris, 1805; and Journal de Physique, lxiii. 207, lxxi. 289, and lxxvii. 1. c Letters on Natural Magic, p. 281, Amer. Edit., New York, 1832. EFFECTS OF ELEVATED TEMPERATURE. 229 was between 220° and 236°, for half an hour; at ihe end of this time a thermometer was applied between the thigh and flank of the animal; and, in about a minute, the mercury sank to 110°; but the real heat of the body was certainly less than this, as the ball of the thermometer could not be kept a sufficient time in proper contact; and the hair, which felt sensibly hotter than the bare skin, could not be prevented from touching the instrument. The temperature of this animal, in the natural state, is 101°. We find in the case of aquatic animals, some astonishing cases of adaptation to the medium in which they live. Although man is capable of breathing air, heated to above the boiling point of water with impunity, we have seen, that he cannot bear the contact of water much below that temperature. Yet we find certain of the lower animals—as fishes—living in water at a temperature, which would be entirely sufficient to boil them if dead. In the thermal springs of Bahia, in Brazil, many small fishes are seen swimming in a rivulet, which raises the thermometer to 88°, when the temperature of the air is only 77^°. Sonnerat, again, found fishes existing in a hot spring at the Manillas, at 158° Fah.; and MM. Humboldt and Bonpland, in travelling through the province of Quito in South America, perceived them thrown up alive, and apparently in health, from the bottom of a volcano, in the course of its explosions, along with water and heated vapour, which raised the thermometer to 210°, or only two degrees short of the boiling point.1 Dr. Reeve found living larvas in a spring, whose temperature was 20S°; Lord Bute saw confervse and beetles in the boiling springs of Albano, which died when plunged into cold water; and Dr. Elliotson knew a gentleman, who boiled some honeycomb, two years old, and, after extracting all the sweet matter, threw the refuse into a stable, which was soon filled with bees.b When the heating influence is applied to a part of the body only, as to the urethra, the temperature of the part, it has been affirmed, is not increased beyond the degree to which the whole body may be raised. From all these facts, then, we may conclude, that when the body is exposed to a temperature, greatly above the ordinary standard of the animal, a frigorific influence is exerted ; but this is effected at a great expense of the vital energy; and hence is followed by con- siderable exhaustion, if the effort be prolonged. In the cold-blooded animal, the power of resisting heat is not great; so that it expires in water not hotter than the human blood occasionally is. Dr. Ed- wards found that a frog, which can live eight hours in water at 32°, is destroyed in a few seconds in water at 105°: this appears to be the highest temperature that cold-blooded animals can bear. Observation has shown, that although the average temperature " Animal Physiology, Library of Useful Knowledge, p. 3. b Physiology, p. 247, Lond. 1840; also, Hodgkin and Fisher's Appendix to their translation of Edwards, Sur l'lnfluence des Agens Physiques, &c., p. 467; and Car- penter, Principles of General and Comparative Physiology, p. 154, Lond. 1839. vol. ii. 20 230 CALORIFICATION. of an animal is such as we have stated in the table, particular circumstances may give occasion to some fluctuation. A slight difference exists, according to sex, temperament, idiosyncrasy, &c. MM. Edwards and Gentil found the temperature of a young female half a degree less than that of two boys of the same age. Edwards' tried the temperature of twenty sexagenarians, thirty-seven septua- genarians, fifteen octogenarians, and five centenarians, at the large establishment of Bicetre, and he observed a slight difference in each class. John Davyb found, that the temperature of a lamb was a degree higher than that of its mother; in five new-born children, the heat was about half a degree higher than that of the mother, and it rose half a degree higher in the first twelve hours after birth. Dr. Holland,0 too. found that the mean temperature of forty infants exceeded that of the same number of adults by If-0 : twelve of the children possessed a temperature of 100° to 103^°. Edwards, on the other hand, found, that, in the warm-blooded animal, the faculty of producing heat is less, the nearer to birth; and that in many cases, as soon as the young dropped from the mother, the tempera- ture fell to within a degree or two of that of the circumambient air; and he moreover affirms, that the faculty of producing heat is at its . minimum at birth, and that it increases successively to the adult age. His trials on children, at the large Hopital des Enfans of Paris, and on the aged, at Bicetre, showed that the temperature of infants, one or two days old, was from 93° to 95° of Fahrenheit; of the sexagenarian from 95° to 97°; of the octogenarian 94° or 95°; and that, as a general rule, it varied according to the age. In his experiments connected with this subject, he discovered a striking analogy between warm-blooded animals in general. Some of these are born with the eyes closed; others with them open: the former, until the eyes are opened, he found to resemble the cold-blooded animal; the latter—or those born with the eyes open—the warm- blooded. Thus, he remarks, the state of the eyes, although having no immediate connexion with the production of heat, may yet coin- cide with an internal structure influencing that function, and it cer- tainly furnishes signs, which indicate a remarkable change in this respect; for, at the period of the opening of their eyes, all young mammalia have nearly the same temperature as adults. Now, in accordance with analogy, a new-born infant, at the full period, having its eyes open, should have the power of maintaining a pretty uniform temperature during the warm seasons; but, if birth should take place at the fifth or sixth month, the case is altered; the pupil is generally covered with the membrana pupillaris, which places the young being in a condition similar to that of closure of the eyelids in animals. Analogy, then, would induce us to conclude, that, in such an infant, the power of producing heat should be inconsider- a De l'lnfluence des Agens, &c, p. 436, Paris, 1826. b Philosoph. Transact, p. 602, for 1814. c An Inquiry into the Laws of Life, &c., Edinb. 1829; and Despretz, in Edinb. Journal of Science, &c, iv. 185. CIRCUMSTANCES INFLUENCING 231 able, and observation confirms the conclusion; although we ob- viously have not the same facilities, as in the case of animals, of exposing the infant to a depressed temperature. The temperature of a seven months' child, though well swathed, and near a good fire, was, within two or three hours after birth, no more than 89.6° Fahrenheit. Before the period at which this infant was born, the membrana pupillaris disappears; and it is probable, as Dr. Edwards has suggested, if it had been born prior to the disappearance of the membrane, its power of producing heat might have been so feeble, that it would scarcely have differed from that of mammalia born with their eyes closed.* The state of the system, as to health or disease, also influences the evolution of heat. Dr. Francis Home,b of Edinburgh, took the heat of various patients at different periods of their indispositions. He found that of two persons, labouring under the cold stage of an intermittent, to be 104°; whilst, during the sweat and afterwards, it fell to 101°, and to 99°. The highest degree, which he noticed in fever, was 107°.° We have often witnessed the thermometer at 106° in scarlatina and in typhus, but it probably rarely exceeds this, although it is stated to have been seen as high as 112°,d and this is the point designated as " fever heat," on Fahrenheit's scale. M. Edwards alludes to a case of tetanus, in a child, the particulars of which were communicated to him by M. Prevost of Geneva, in which the temperature rose to 110.75° Fahrenheit/5 Hunterf found the interior of a hydrocele, on the day of operation, to raise the mercury to 92° ; on the following day, when inflammation had com- menced, it rose to 99°. The fluid, obtained from the abdomen of an individual, tapped for the seventh time for dropsy of the lower belly, indicated a temperature of 101°. Twelve days thereafter, when the operation was repeated for the eighth time, the tempera- ture was 104°. Dr. Granvilleg has asserted that the temperature of the uterine system sometimes rises as high as 120°—the elevation seeming to bear some ratio to the degree of action in the organ. We have frequently been struck with the seemingly elevated tem- perature of the vagina under these circumstances, but we cannot help suspecting some inaccuracy in the observations of Dr. Gran- ville, the temperature, he indicates, being so much higher than has ever been noticed in any condition of the system. Under this feel- ing, several experiments were made, at the author's request, by Dr. Barnes,h one of the resident physicians of the Philadelphia Hospital, which exhibit only a slight difference between the temperature of the vagina and that of the uterus during parturition. In two cases, * Op. cit., and Analytical Review of Hodgkin and Fisher's translation, by the author of this work, in Amer. Journ. of Medical Sciences, p. 150, for May, 1834. b Medical Facts and Experim. Lond. 1759. c Currie's Medical Reports, Liverpool, 1798, and Philad. 1808. >> G. T. Morgan's First Principles of Surgery, p. 80, Lond. 1837. e Edwards, op. citat. p. 490. f On the Blood, &c. p. 296, Lond. 1794. s Philos. Transact, p. 262, for 1825; and Sir E. Home, in Lect. on Comp. Anat. v, 201, Lond. 1828. b Dunglison's American Medical Intelligencer, Feb, 15, 1839, p. 346. 232 CALORIFICATION. the temperature of the labia was 100°, and in a third 105°; whilst that of the uterus, was 100°, 102°, and 106° respectively. Dr. James Curiie had himself bled; and during the operation, the mercury of a thermometer, which he held in his hand, sank, at first slowly and afterwards rapidly, nearly 10°; and when he fainted, the assistant found, that it bad sunk 8° farther. MM. Edwards and Gentil assert, that they have likewise observed diurnal variations in the temperatare of individuals, and these pro- duced, apparently, by the particular succession in the exercise of the different organs; as where intellectual meditation was followed by digestion. These variations, they affirm, frequently amounted to two or three degrees, between morning and evening.* M. Chevallierb has investigated the temperature of the urine on issuing from the bladder. This he did not find to vary from ex- ternal temperature, but it was effected by rest, fatigue, change of regimen, remaining in bed, &c. The lowest temperature, which was observed on rising in the morning, was about 92°; the highest, after dinner, and when fatigued, 99°. In the case of another per- son, the temperature of the urine was never lower than 101°, and occasionally upwards of 102°, when he was fatigued. Such are the prominent facts connected with the subject of ani- mal heat. It is obvious, that it is altogether disengaged by an action of the system, which enables it to counteract, within certain limits, the extremes of atmospheric heat and cold. The animal body, like all other substances, is subjected to the laws regarding the equilibrium, the conduction, and the radiation of caloric; but, by virtue of the important function we are now considering, its own temperature is neither elevated nor depressed by those influences to any great amount. Into the seat and nature of this mysterious process, and the various ingenious theories that have been indulged, we shall now inquire. Physiologists have been by no means agreed, regarding the organs or apparatus of calorification. Some, indeed, have affirmed that there is not, strictly speaking, any such apparatus; and that animal heat is a result of all the other vital operations. Amongst those, too, who admit the existence of such an apparatus, a diffe- rence of sentiment prevails; some thinking, that it is local, or effected in a particular part of the body; others, that it is general, or dis- seminated through the whole economy. Under the name caloricite Chaussier admits a primary vital pro- perty, by virtue of which living beings disengage the caloric on which their proper temperature is dependent, in the same manner as they accomplish their other vital operations, by other vital pro- perties ; and in support of this doctrine, he adduces the circum- stance, that each living body has its own proper temperature; which is coexistent only with the living state; is common to every living part; ceases at death; and augments by every cause, that 1 See Purkinje, in art. Calor Animali3, in Encyclop. Worterbuch der Medicin. Wis- senschaft. Band. vi. s. 530, Berlin, 1831. b Essai sur la Dissolution de la Gravelle, &c. p. 120, Paris, 1837. SEAT OF 233 excites the vital activity. It has been properly objected, however, to this view, that the same arguments would apply equally to many other vital operations,—and that it would be obviously improper to admit, for each of these functions, a special vital principle. The notion has not experienced favour from the physiologist, and is, we believe, confined to the individual from whom it emanated.* Boin,b again, considers that no particular organ is specially charged with the disengagement of caloric ; but that it is the corn- digestion, respiration, circulation, nutrition, secretion, &c. The mon resultant of all the vital actions,—nervous and muscular, of arguments, which he adduces, in favour of his position, are,—that the exercise of any of these functions actually modifies the tempera- ture of the body; that mental labour heats the head,—hence the excitement witnessed in the maniac, and the great resistance to cold for which he is distinguished; and that, during emotion, we are hot or cold, whatever may be the condition of the atmosphere. The action of the various organs of the body has, doubtless, con- siderable influence in modifying the disengagement of heat; and it is probable, that it takes place in the different organs, referred to by Boin, but not, perhaps, directly in consequence of the functions they accomplish. Amongst those who admit that calorification is a local action, some have believed, that the caloric is disengaged in a particular organ, whence it is distributed to every part of the body ; whilst others conceive, that every part disengages its own caloric and has its special temperature. So striking a phenomenon as animal temperature could not fail to attract early attention; and accordingly, we find amongst the ancients various speculations on the subject. The most prevalent was,—that its seat is in the heart; that the heat is communicated to the blood in that viscus, and is afterwards sent to every part of the system; and that the great use of respiration is to cool the heart; but this hypothesis is liable to all the objections, which apply to the notion of any organ of the body acting as a furnace,—that such organ ought to be calcined ; and it has the additional objection, applicable to all speculations, regarding the ebullition and efferve- scence of the blood as a cause of heat, that it is purely conjectural, without the slightest fact or argument in its favour. It was not, indeed, until the chemical doctrines prevailed, that any thing like argument was adduced in support of the local disengagement of heat: the opinions of physiologists then settled almost universally upon the lungs; and this, chiefly, in consequence of the observation, that animals, which do not breathe, have a temperature but little superior to the medium in which they live; whilst man and ani- mals that breathe, have a temperature considerably higher than the medium heat of the climate in which they exist, and one which * Art. Caloricite, by Coutanceau, in Diet, de Medecine, torn. iv. Paris, 1822; and Adelon's Physiologie de I'Homme, torn. iii. 407, 2de edit., Paris, 1829. b Dissertation sur la Chaleur Vitale, Paris, 1802. 20* 234 CALORIFICATION. is but little affected by changes in the thermal condition of that medium ; and, moreover, that birds, which breathe, in proportion, a greater quantity of air than man, have a still higher temperature than he. Mayow,a whose theory of animal heat was, in other respects, sufficiently unmeaning, affirmed, that the effect of respiration is not to cool the blood, as had been previously maintained, but to gene- rate heat, which it did by an operation analogous to combustion. It was not, however, until the promulgation of Dr. Black's doctrine of latent heat, that any plausible explanation of the phenomenon appeared.b According to that distinguished philosopher, a part of the latent heat of the inspired air becomes sensible; consequently, the temperature of the lungs, and of the blood passing through them, must be elevated ; and, as the blood is distributed to the whole sys- tem, it communicates its heat to the parts as it proceeds on its course. But this view was liable to an obvious objection, which was, indeed, fatal to it, and so Black himself appears to have thought, from his silence on the subject. If the whole of the caloric were disengaged in the lungs, as in a furnace, and were distributed through the blood-vessels, as heated air is transmitted along con- ducting pipes, the temperature of the lungs ought to be much greater than that of the parts more distant from the heart; so great indeed, as to consume that important organ in a short space of time. The doctrine, maintained by Lavoisier0 and Seguin, was ;—that the oxygen of the inspired air combines with the carbon and hydro- gen of the venous blood, and produces combustion. The caloric, given off, is then taken up by the blood-vessels, and is distributed over the body. The arguments, which they adduced in favour of this view, were:—the great resemblance between respiration and combustion, so that if the latter gives off heat, the former ought to do so likewise;—the fact that arterial blood is somewhat warmer than venous;—and certain experiments of Lavoisier and La Place/ which consisted in placing animals in the calorimeter, and com- paring the quantity of ice which they melted, and, consequently, the quantity of heat, which they gave off, with the quantity of car- bonic acid produced; and finding, that the quantity of caloric, which would result from the carbonic acid formed, was exactly that dis- engaged by those animals. Independently, however, of other ob- jections, this hypothesis is liable to those already urged against that of Black, which it closely resembles. The objection, that the lungs ought to be much hotter than they really are—both absolutely and relatively—was attempted to be obviated by Dr. Crawford6 in a most ingenious and apparently * Tract, quinque, Oxon. 1674. b Bostock's Physiology, 3d edit. p. 440, Lond. 1836. c Mem. de 1'Acad. des Sciences pour 1777, 1780, and 1790. d Memoir, de 1'Acad. des Sciences pour 1780. e Exp. &c. on Animal Heat, 2d edit. Lond. 1788; Henry's Elements of Chemistry, vol. ii.; and Fleming's Philosophy of Zoology, i. 387, Edinb. 1822. THEORIES OF CALORIFICATION. 235 logical manner. The oxygen of the inspired air, according to him, combines with the carbon given out by the blood, so as to form carbonic acid. But the specific heat of this is less than that of oxygen: and accordingly, a quantity of latent caloric is set free; and this caloric is not only sufficient to support the temperature of the body, but also to carry off the water—which was supposed to be formed by the union of the hydrogen and the oxygen—in the state of vapour, and to raise the temperature of the inspired air considerably. So far the theory of Crawford was liable to the same objections as those of Black, and Lavoisier and Seguin. He affirmed, however, that the same process by which the oxygen of the inspired air is converted into carbonic acid, converts likewise the venous into arterial blood; and as he assumed from his experiments, that the capacity for caloric of arterial blood is greater than that of venous, in the proportion of 1.0300 to 0.8928; he conceived, that the caloric, set free in the formation of the carbonic acid, in place of raising the temperature of the arterial blood, is employed in saturating its increased capacity, and in maintaining its temperature at the same degree with the venous. According to this view, therefore, the heat is not absolutely set free in the lungs, although arterial blood contains a greater quantity of caloric than venous; but when, in the capillaries, the arterial , becomes converted into venous blood, or into blood of a less capacity for caloric, the heat is disengaged, and occasions the temperature of the body. If the facts, which served as a foundation for this beautiful theory of animal heat, were not false, the deductions would be irresistible; and, accordingly, it was at one time almost universally received, especially by those who consider that all vital operations can be assimilated to chemical processes; and it is still favoured by many. "The animal heat," observes a recent writer,* "has been accounted for in different ways by several ingenious physiologists; from the aggregate of their opinions and experiments I deduce, that heat is extricated all over the frame, in the capillaries, by the action of the nerves, during the change of the blood, from scarlet arterial to purple venous; and also whilst it is changing in the lungs from purple to scarlet. There is a perpetual deposition by the capillary system of new matter, and decomposition of the old all over the frame, influenced by the nerves; in this decomposition there is a continual disengagement of carbon, which mixes with the blood returning to the heart, at the time it changes from scarlet to purple; this decomposition, being effected by the electric agency of the nerves, produces constant extrication of caloric; again, in the lungs that carbon is thrown off and united with oxygen, during which caloric is again set free, so that we have in the lungs a charcoal fire constantly burning, and in the other parts a wood fire, the one pro- ducing carbonic acid gas, the other carbon, the food supplying a Dr. Billing, First Principles of Medicine, 2d edit. p. 19, Lond, 1837. 236 CALORIFICATION. through the circulation the vegetable (or what answers the same end, animal) fuel, from which the charcoal is prepared which is burned in the lung."* But numerous objections arise against this view. In the first place, we have elsewhere endeavoured to show that respiration is not a com- bustion ; and that our knowledge is limited to the fact, that oxygen is taken into the pulmonary vessels, and carbonic acid given off, but we have no means of knowing whether the one goes immediately to the formation of the other. Dr. Crawford had inferred from his experiments, that the specific heat of oxygen is 4.7490; of carbonic acid, 1.0454; of azote, 0.7936; and of atmospheric air, 1.7900; but the more recent experiments of Delaroche and Berard make that of oxygen, 0.2361; of carbonic acid, 0.2210; of azote, 0.2754; and of atmospheric air, 0.2669; a difference of such trifling amount, that it has been conceived that the quantity of caloric, given out by oxygen during its conversion into carbonic acid, would be insuffi- cient to heat the residual air, which is expelled in breathing, to its ordinary elevation. Secondly. The elevation of temperature of one or two degrees, which appears to take place in the conversion of venous into arterial blood, although generally believed, is not as- sented to by all. The experiments instituted on this point have been .few and imprecise. Thirdly. M. Dulong,b—on repeating the experi- ments of Lavoisier and La Place, for comparing the quantities of caloric given off by animals, in the calorimeter, with that which would result from the carbonic acid, formed during the same time in their respiration—did not attain a like result. The quantity of caloric disengaged by the animal was always superior to that which would result from the carbonic acid formed. Fourthly. The esti- mate of Crawford, regarding the specific heat of venous and arterial blood, has been contested. He made that of the former, we have seen, 0.8928 ; of the latter, 1.0300. The result of the experiments of Dr. John Davyc give 0.903 to the former, and 0.913 to the latter; and in another case, the result of which has been adopted by Ma- gendie, the specific heat of the venous was greater than that of the arterial blood, in the proportion of .852 to .839. Granting, how- ever, that the case is as stated by Crawford, it is insufficient to ex- plain the phenomena. It has, indeed, been attempted to show, that if the whole of the caloric, set free in the manner mentioned, were immediately absorbed, it would be insufficient for the consti- tution of the arterial blood; and that, instead of the lung running the risk of being calcined, it would be threatened with congelation. But the theory of Crawford was most seriously assailed by other experiments, tending to show, that the function of calorification is derived from the great nervous centres. When an animal is de- capitated, or when the spinal marrow, or the brain, or both, are destroyed, the action of the heart may still be kept up, provided the " See, also, Elliotson, Human Physiology, p. 238, Lond. 1840. b Magendie's Journal de Physiologie, iii. 45. c Philos. Transactions for 1814. THEORIES OF CALORIFICATION. 237 lungs be artificially inflated. In such case, it is found, that the usual change in the blood, from venous to arterial, is produced; and that oxygen is absorbed and carbonic acid exhaled as usual. Sir Benjamin Brodie,a in performing this experiment, directed his attention to the point,—whether animal heat is, under such circumstances, evolved, and the temperature maintained, as where the brain and spinal marrow are entire—and he found, that although the blood appeared to undergo its ordinary changes, the generation of animal heat seemed to be suspended; and consequently, if the inspired air hap- pened to be colder than the body, the effect of respiration was to cool the animal; so that an animal, on which artificial respiration was kept up, became sooner cold than one killed at the same time and left undisturbed. The inference, deduced from these experiments, was, that instead of circulation and respiration maintaining the heat, they dissipate it; and that as the heat is diminished by the destruction of the nervous centres, its disengagement must be ascribed to the action of those centres, and particularly to that of the encephalon. M. Chossatb has endeavoured to discover the precise part of the nervous system engaged in calorification; but the results of his experiments have not been such as to induce him to refer it exclu- sively, with Sir B. Brodie, to the encephalon. He divided the brain, anterior to the pons varolii, in a living animal, so that the eighth pair of nerves were uninjured. Respiration, consequently, conti- nued, and inflation of the lungs was unnecessary. Notwithstanding this serious mutilation, the circulation also went on; and Chossat observed distinctly, that arterial blood circulated in the arteries. Yet the temperature of the animal gradually sank, from 104° Fahr., —its elevation at the commencement of the experiment,—to 76°, in twelve hours, when the animal died. It seemed manifest to M. Chossat, that, from the time the brain was divided, heat was no longer given off, and the body gradually cooled as it would have done after death. Farther than this,—he noticed, that the time, at which the refrigeration occurred most rapidly, was that in which the circulation was most active,—at the commencement of the ex- periment. In other experiments, M. Chossat paralysed the action of the brain by a violent concussion, and by injecting a strong decoction of opium into the jugular vein,—keeping up respiration at the same time artificially. The results were the same. From these experiments, he drew the conclusion, that the brain has a direct influence over the production of heat. His next experiments were directed to the discovery of the me- dium through which the brain acts,—the eighth pair of nerves, or spinal marrow. He divided the eighth pair of nerves in a dog, and kept up artificial respiration. The temperature sank gradually, and, » Philos. Trans, for 1811 and 1812. b Sur la Chaleur Animale, Paris, 1820; Adelon, op. cit. iii. 416; Coutanceau, in art. Chaleur Animale, Diet, de Med. iv. 17, Paris, 1822 ; and P. H. Berard, art. Chaleur Animale, Diet, de Med. 2de edit. vii. 206, Paris, 1834. 238 CALORIFICATION. at the expiration of sixty hours, when the animal died, it was reduced to 68° of Fahrenheit. Yet death did not occur from asphyxia or suspension of the phenomena of respiration, as the lungs crepitated, exhibited no signs of infiltration, and were partly filled with arterial blood. It appeared to M. Chossat to expire from cold. As, how- ever, the mean depression of heat was less than in the preceding experiments, he inferred that a slight degree of heat is still disengaged after the section of the eighth pair, whilst after injury done to the brain directly, heat is no longer given off. Again, he divided the spinal marrow beneath the occiput, and although artificial respiration was maintained, as in the experiments of Brodie, the temperature gradually fell, and the animal died ten hours afterwards, at a heat of 79°; and as death occurred in this case so much more speedily than in the last, he inferred, that the influence of the brain over the production of heat is transmitted rather by the spinal marrow than by the eighth pair of nerves. In his farther experiments, Chossat found, that when the spinal marrow was divided between each of the twelve dorsal vertebrae, the depression of temperature occurred less and less rapidly, the lower the intervertebral section, and it was imperceptible at the lowest; he therefore concluded, that the spinal marrow did not act directly in the function, but indirectly through the trisplanchnic nerve. To satisfy himself on this point, he opened a living animal on the left side, beneath the twelfth rib, and removed the suprarenal capsule of that side, dividing the trisplanchnic where it joins the semilunar plexus. The animal gradually lost its heat, and died ten hours afterwards in the same state, as regarded temperature, as when the spinal marrow was divided beneath the occiput. Desiring to obtain more satisfactory results,—the last experiment applying to only one of the trisplanchnic nerves,—he tied the aorta, which supplies both with the materials on which they operate, be- neath the place where it passes through the arch of the diaphragm, at the same time preventing asphyxia by inflating the lungs. The animal lost its heat much more rapidly, and died in five hours. In all these cases, according to Chossat, death occurred from cold ; the function, by which the caloric, constantly abstracted from the sys- tem by the surrounding medium, is generated, having been rendered impracticable. To obtain a medium of comparison, he killed seve- ral animals by protracted immersion in cold water, and found, that the lowest temperature, to which the warm-blooded could be re- duced, and life persist was 79° of Fahrenheit M. Chossat also alludes to cases of natural death by congelation, which he conceives to destroy in the manner we have before suggested, by diminution of the nervous energy, as indicated by progressive stupor, and by debility of the chief functions of the animal economy. Lastly:—on killing animals suddenly, and attending to the pro- gress of refrigeration after death, he found it to be identical with that which follows direct injury of the brain, or division of the spinal marrow beneath the occiput. THEORIES OF CALORIFICATION. 239 A view, somewhat analogous to this of M. Chossat, has been embraced by Sir Everard Home.* He conceives, that the pheno- menon is restricted to the ganglionic part of the nervous system, and he rests the opinion chiefly upon the position, that there are certain animals, which have a brain, or some part equivalent to one, but whose temperature is not higher than that of the surround- ing medium; whilst, on the other hand, all the animals that evolve heat are provided with ganglia. The doctrines of Brodie, Chossat, and Home have been considered by the generality of the chemists,—by Brande,b Thomson,0 and Paris,d—to be completely subversive of the chemical doctrines, which refer the production of animal heat to the respiratory func- tion; and their position,—that it is a nervous function,—has seemed to be confirmed by the facts attendant upon injury done to the nerves of parts, and by what is witnessed in paralytic limbs, the heat of which—as we shall see—is generally and markedly inferior to that of the sound parts. But there are many difficulties in the way of admitting, that the nervous system is the special organ for the pro- duction of animal temperature. Dr. Wilson Philip,6 from a repeti- tion of the experiments of Sir Benjamin Brodie, was led to conclude, that the cause, why the temperature of the animal body diminished more rapidly, when artificial inflation was practised, than when the animal was left undisturbed, was—too large a quantity of air having been sent into the lungs; and he found, that when a less quantity was used, the cooling process was sensibly retarded by the inflation. The experiments of Legallois,f Hastings/ and Williams,h although differing from each other in certain particulars, corroborate the conclusion of Dr. Philip, and, what is singular, they would appear to show, that the temperature occasionally rises during the experi- ment; facts, which would rather confirm the view, that respiration is greatly concerned in the evolution of heat. Many of the facts, detailed by Chossat, are curious, and exhibit the indirect agency of the nervous system, but his conclusion, that the trisplanchnic is the great organ for its developement, is liable to the objections we have urged regarding the theory, which looks upon the heart, or the lungs as furnaces for the disengagement of caloric, that they ought to be consumed in a short space of time by the ope- ration. All the facts, however, exhibit, that, in the upper classes of animals, the three great acts of innervation, respiration and circu- lation are indirectly concerned in the function; not that any one is the special apparatus. M. Edwards has attempted to show, that it is more connected with the second of these than with either of the * Philos. Trans, p. 257, for 1825; Journal of Science and Arts, xx. 307 ; and Lect. on Comparative Anat. v. 121 and 194, Lond. 1828. b Manual of Chemistry, vol. iii. ° System of Chemistry, vol. iv. d Medical Chemistry, p. 327, Lond. 1825. e An Experimnntal Inquiry into the Laws of the Vital Functions, 3d edit. p. 180. f Annales de Chimie, iv. 5, Paris, 1817. b Wilson Philip, op. cit.; and Journal of Science, &c. xiv. 96. b Edinb. Medico-Cbirurgical Transact, ii. 192. 240 CALORIFICATION. others. Thus, animals, whose temperature is highest, bear privation of air the least; whilst cold-blooded animals suffer comparatively little from it; and young animals are less affected by it than the adult. Now, the greater the temperature of the animal, and the nearer to the adult age, the greater is the consumption of oxygen. He farther observed, that whilst the seasons modify calorification, they affect also respiration; and that if, in summer, less heat is eli- cited, and in winter more, respiration consumes less oxygen in the former season than in the latter. The experiments of Legallois, as well as those instituted by Ed- wards, led the latter to infer, that there is a certain ratio between heat and respiration, in both cold-blooded and warm-blooded ani- mals, and in hibernating animals, both in the periods of torpidity and of full activity. When the eighth pair of nerves is divided in the young of the mammalia, a considerable diminution is produced in the opening of the glottis; so that, in puppies, recently born, or one or two days old, so little air enters the lungs, that when the experi- ment is made in ordinary circumstances, the animal perishes as quickly as if it was entirely deprived of air. It lives about half an hour. But, if the same operation be performed upon puppies of the same age, benumbed with cold, they will live a whole day. In the first case, M. Edwards thinks, and plausibly, the small quantity of air is insufficient to counteract the effect of the heat; whilst, in the other, it is sufficient to prolong life considerably, and he deduces the following practical inferences applicable to the adult age, and parti- cularly to man. A person, he remarks, is asphyxied by an excessive quantity of carbonic acid in the air he breathes; the pulse is no longer perceptible; the respiratory movements cannot be discerned, but his temperature is still elevated. How should we proceed to re- call life. Although the action of the respiratory organs is no longer visible, all communication with the air is not cut off. The air is in contact with the skin, upon which it exerts a vivifying influence: it is also in contact with the lungs, in which it is renewed by the agita- tion constantly taking place in the atmosphere, and by the heat of the body, which rarefies it. The heart continues to beat, and main- tains a certain degree of circulation, although not perceptible bythe pulse. The temperature of the body is too high to allow the feeble respiration to produce upon the system all the effect of which it is capable. The temperature must then be reduced; the patient must be withdrawn from the deleterious atmosphere; be stripped of his clothes, in order that the air may have a more extended action upon his skin; be exposed to the cold, although it be winter, and cold water be thrown upon his face until the respiratory movements re- appear. This is precisely the treatment adopted in practice to revive an individual from a state of asphyxia. If, instead of cold, continued warmth were to be applied, it would be one of the most effectual means of extinguishing life. This consequence, like the former, is confirmed by experience. In sudden faintings, where the pulse is weak or imperceptible, the action of the respiratory organs diminished, * THEORIES OF CALORIFICATION. 241 and sensation and voluntary motion suspended, persons, the most ignorant of medicine, are aware, that means of refrigeration must be employed,—such as exposure to air, ventilation, and sprinkling with cold water. In violent attacks of asthma, also, when the extent of respiration is so limited that the patient experiences a sense of suffocation, he courts the cold air even in the severest weather; opens the windows; breathes a frosty air, and finds himself re- lieved. As a general rule, an elevated temperature accelerates the respi- ratory movements, but the degree of temperature, requisite to pro- duce this effect, is not the same in all. The object of this accelerated respiration is, that more air may come in contact with the lungs, in a given time, so as to reanimate what the heat depresses. It is proper to remark, however, that we meet with many excep- tions to the rule endeavoured to be laid down by M. Edwards, as regards the constant ratio between heat, and respiration. Experi- ments on the lower animals, and pathological cases in man, have shown, that lesions of the upper part of the spinal marrow give occasion, at times, to an extraordinary developement of heat. In the case of a man at St. George's Hospital, London, labouring under a lesion of the cervical vertebrae, Sir B. Brodie observed the tem- perature to rise to 111°, at a time when the respirations were not more than five or six in a minute.* • Drs. Graves and Stokesb give the case of a patient, who laboured under a very extensive de- velopement of tubercles, had tubercular abscesses in the upper por- tions of both lungs, and general bronchitis. In this case, at a period when the skin was hotter than usual, and the pulse 126, the respirations were only 14 in the minute; besides, as Dr. Alison0 has remarked, the temperature of the body is not raised by voluntarily increasing or quickening the acts of respiration: but by voluntary exertions of other muscles, which accelerate the circulation, and thus necessitate an increased frequency of respiration ; a fact, which would seem to show that calorification is dependent not simply on the application of oxygen to the blood, but on the changes that take place during circulation, and to the maintenance of which the oxy- genation of the blood is one essential condition. Moreover, in the foetus in utero, there is, of course, no respiration; yet its tempera- ture equals, and indeed is said to even exceed, that of the mother ; and we know that its circulation is more rapid, and its nutrition more active.*1 That innervation is indirectly concerned in the phenomenon is 1 Lond. Med. Gazette, for June 1836, and G. T. Morgan's First Principles of Surgery, p. 85, Lond. 1837. b Dublin Hospital Reports, vol v. See, also, Dr. Graves, Clinical Lectures, Dungli- son's Amer. Med. Lib. Edit. p. 126, Phil. 1838; Dr. John Davy, Researches, Physio- logical and Anatomical, Amer. Med. Lib. Edit. p. 89, Philad. 1840. c Outlines of Physiol. Lond. 1831. d See, also, on the connexion of respiration with calorification, P. H. Berard, art. Chaleur Animale, in Diet, de Med. 2de edit. vii. 175, Paris, 1834; Dr. Southwood Smith's Philosophy of Health, vol. ii. Lond. 1838; and Mr. Newport on the Tempera- VOL. II. 21 242 CALORIFICATION. proved by the various facts which have been referred to; and Le- gallois, although he does not accord with Sir B. Brodie, conceives, that the temperature is greatly under the influence of the nervous system, and that whatever weakens the nervous power, propor- tionally diminishes the capability of producing heat. Dr. Philip, too, concluded from his experiments, that the nervous influence is so intimately connected with the power of evolving heat, that it must be looked upon as a necessary medium between the different steps of the operation. He found, that if the galvanic influence be applied to fresh drawn arterial blood, an evolution of heat, amounting to three or four degrees, takes place, whilst the blood assumes the venous hue and becomes partly coagulated. He regards the pro- cess of calorification as a secretion; and explains it upon his general principle of the identity of the nervous and galvanic influences, and of the necessity for the exercise of such influence in the function of secretion.* Mr. H. Earleb found the temperature of paralysed limbs to be slightly lower than that of sound limbs, and the same effect upon calorification is observed to supervene on traumatic injuries of the nerves. In a case of hemiplegia, of five months' duration, under the author's care at the Blockley hospital, the thermometer in the right—the sound—axilla of the man stood at 96^° ; in the axilla of the paralysed side at 96°. The difference in lemperature of the hands was more signal. The right hand carried the mercury to 87,° whilst the left raised it no further than 79^°. In another case—that of a female—of two weeks' duration, accompanied with signs of cerebral turgescence, the temperature in the axilla of the sound side was 100° ; in that of the paralysed 98.25°; of the hand of the sound side, 94°; of the other 90°.c It is a general fact, that the temperature of the paralyzed side in hemiplegia is less than that of the sound side; yet the irregularity of nervous action is so great, and the power of resistance to excitant or depressing agents so much diminished, that the author has not unfrequently found the temperature to bs more elevated.d Lastly, that the circulation is necessary to calorification, we have evidence in the circumstance, that if the vessels, proceeding to a part be tied, animal heat is no longer disengaged from it. It is manifest, then, that in animals, and especially in the warm- blooded, the three great vital operations are necessary for the disengagement of the due temperature, but we have no sufficient evidence of the direct agency of any one, and we see heat elicited in the vegetable, in which these functions are at all events rudi- ture of Insects, and its Connexion with the Functions of Respiration and Circulation in this class of invertebrated animals, from the Philos. Transact, part ii. 4to p. 77, Lond. 1837. * Ley, in Appendix to Essay on Laryngismus Stridulus, &c. p. 374, Lond. 1836. b Medico-Chirurgical Transactions, vii. 173, Lond. 1819. c See Nasse, Untersuchungen zur Physiologie und Pathologie, Bonn. 1835-6. d See the author in his American Med. Intelligencer, Oct. 15, 1838, p. 225. THEORIES OF CALORIFICATION. 243 mental; and the existence of one of them—innervation—perhaps more than doubtful.* The view of those, who consider, that the disengagement of caloric occurs in the intermediate system or system of nutrition of the whole body, appears to us the most consistent with observed phenomena. These views have varied according to the physical circumstances, that have been looked upon as producing heat. By some, it has been regarded as the product of effervescence of the blood and humours; by others, as owing to the disengagement of an igneous matter, or spirit from the blood ; by others, to an agitation of the sulphureous parts of the blood; whilst Boerhaaveb and Douglas0 ascribe it to the friction of the blood against the parietes of the vessels, and of the globules against each other. In favour of the last hypothesis, it was urged, that animal heat is in a direct ratio with the velocity of the circulation, the circumference of the vessels, and the extent of their surface; and that thus we are able to explain, why the heat of parts decreases in a direct ratio with their distance from the heart; and the greater heat of the arterial blood, in the lungs, was accounted for, by the supposition, that the pulmonary circulation is far more rapid. Most of these notions are entirely hypothetical. The data are generally incorrect, and the deductions characteristic of the faulty physics of the period in which they were indulged. The correct view, it appears to us, is, that caloric is disengaged in every part, by a special action, under the nervous influence, and the presence of arterial blood; the latter eilher fur- nishing the materials, or merely acting as a stimulus. In this man- ner, calorification becomes, like nutrition, a function executed in the capillary system, and therefore appropriately considered in this place. It has been remarked by Tiedemann/ that the intussusception of alimentary matters, and their assimilation by digestion and respira- tion, the circulation of the humours, nutrition and secretion, the renewal of materials accompanying the exercise of life, and the constant changes of composition in the solid and liquid parts of the organism,—all of which are under the nervous influence,—partici- pate in the evolution of heat, and we deceive ourselves when we look for the cause in one of those acts only. In some experiments by Dr. Robert E. Rogers,6 of Philadelphia, he found that when re- cently drawn venous blood contained in a freshly removed pig's bladder was immersed in oxygen gas, there was a remarkable eleva- tion of temperature, doubtless produced by the physical acts of the * Dr. W. B. Carpenter, Principles of General and Comparative Physiology, p. 379, Lond. 1839. b Gerard Van Swieten. Comment in Boerhaav. Aphorism. &c. § 382, 675, Lugd. Bat. 1742-1772. c On Animal Heat, p. 47, Lond. 1747. d Traite de Physiologie, &c. trad, par Jourdan, p. 514, Paris, 1831; Ley, op. cit. Appendix, p. 303; and Collard de Martigny, in Journal Complementaire des Sciences Medicales, xliii. 268, Paris, 1832. e Amer. Journ. of the Med. Sciences, p. 297, for Aug. 1836. 244 CALORIFICATION. transmission of the gases from without the animal membrane to within, and the exosmose of the carbonic acid from the blood. Dr. Davya performed some experiments which led to the same results. In one of these, he took a very thin vial, of the capacity of eight liquid ounces, and carefully enveloped it in bad conducting sub- stances—namely, several folds of flannel, of fine oiled paper, and of oiled cloth. Thus prepared, and a perforated cork being provided, holding a delicate thermometer, two cubic inches of mercury were introduced, and immediately after it was filled with venous blood kept liquid by agitation. The vial was then corked, and shaken. The thermometer included was stationary at 45°. After five minutes, during which it remained stationary, it was withdrawn; the vial closed by another cork, was transferred inverted to a mercurial bath, and 1^ cubic inch of oxygen was introduced. The common cork was returned, and the vial was well agitated for about a minute: the thermometer was now introduced; it rose immediately to 46°, and by continuing the agitation, it rose further to 46.5°, and very nearly to 47°. This experiment was made on the blood of the sheep. These and other experiments of a similar character, in Dr. Davy's opinion, appear to favour the idea, that animal heat is owing, first, to the fixation or condensation of oxygen in the blood in the lungs, in its,conversion from venous to arterial; and secondly, to the com- binations into which it enters in the circulation in connexion with the different secretions and changes essential to animal life. It is by the theory of the general evolution of caloric in the capillary system, or in the system of nutrition, that we are capable 'of accounting for the increased heat that occurs in certain local affections, in which the temperature greatly exceeds that of the same parts in health. By some, it has been doubted, whether, in cases of local inflammation, any such augmentation of temperature exists, but the error seems to have arisen from the temperature of the part, in health, having generally been ranked at blood heat; whereas, we shall find, that it differs essentially in different parts. Dr. Thomson found, that a small inflamed spot, in his right groin, gave out, in the course of four days, a quantity of heat, sufficient to have heated seven wine-pints of water from 40° to 212°; yet the temperature was not sensibly less than that of the rest of the body at the end of the experiment, when the inflammation had ceased.b Of the mode in which heat is evolved in the capillaries, it is im- possible for us to arrive at any satisfactory information. The result alone indicates, that the process has been accomplished. In the present state of our knowledge, we are compelled to refer it to some vital action, of the nature of which we are ignorant; but which seems to be possessed by all organized bodies,—vegetable as well as animal. By supposing, that calorification is effected in every part of the a Proceedings of the Royal Society for 1837-8, No. 34, and Researches, Physiologi- cal and Anatomical, Dunglison's American Med. Lib. Edit. p. 89, Philad. 1840. b Annals of Philosophy, ii. 27. THEORIES OF CALORIFICATION. 245 body, we can understand why different portions should have different temperatures; as the activity of the function may vary, in this re- spect, according to the organ.* Chopart and Dessault found the heat of the rectum to be 100°; of the axilla and groin, when covered with clothes, 96°; and of the chest 92°. Dr. Davyb found the tem- perature of a naked man, just risen from bed, to be 90° in the mid- dle of the sole of the foot; 93° between the inner ankle and tendo achillis; 91.5° in the middle of the shin; 93° in the calf; 95° in the ham; 91° in the middle of the thigh; 96.5° in the fold of the groin; 95° at three lines beneath the umbilicus; 94° on the sixth rib of the left side; 93° on the same rib of the right side; and 98° in the axilla. MM. Edwards and Gentil found the temperature of a strong adult male, to be, in the rectum and mouth, 102°; in the hands 100°; in the axilla and groins 98° ; on the cheeks, 97° ; in the prepuce and the feet, 96°; and on the chest and abdomen 95°. All these experiments, it is obvious, concern only the temperature of parts, which can be readily modified by the circumambient medium. To judge of the comparative temperature of the internal organs, Dr. Davy killed a calf, and noted the temperature of dif- ferent parts, both external and internal. The blood of the jugular vein raised the thermometer to 105.5°; and that of the carotid artery to 107°. The heat of the rectum was 105.5°; of the metatarsus 97°; of the tarsus 90°; of the knee 102°; of the head of the femur 103° ; of the groin 104°; of the under part of the liver 106°; of the sub- stance of that organ 106°; of the lung 106.5°; of the left ventricle 107°; of the right 106° ; and of the substance of the brain 104°. In the case of fistulous opening into the stomach, observed by Dr. Beaumont,0 the thermometer indicated a difference of three- fourths of a degree between the splenic and pyloric orifices of the stomach ; the temperature of the latter being more elevated. It is not easy to account for these differences without supposing that each part has the power of disengaging its own heat, and that the communication of caloric is not sufficiently ready to prevent the difference from being perceptible. It was stated early in this section, that man possesses the power of resisting cold as well as heat within certain limits, and of pre- serving his temperature greatly unmodified. Let us inquire into the direct and indirect agents of these counteracting influences. As the mean temperature of the warmest regions does not exceed 85° of Fahrenheit, it is obvious that he must be constantly disengag- ing caloric to the surrounding medium :—still, his temperature re- mains the same. This is effected by the mysterious agency which we have been considering, materially aided, however, by several circumstances, both intrinsic and extrinsic. The external envelope of the body is a bad conductor of caloric, * J. Hunter, Observations on the Animal fficonomy, Lond. 1786. b Philosoph. Transact, for 1814. c Exp. and Observations on the Gastric Juice, p. 274, Plattsburg, 1833. 21* 246 CALORIFICATION. and therefore it protects the internal organs, to a certain extent, from the sudden influence of excessive heat or cold. But the cuta- neous system of man is a much less efficient protection than that of animals. In the warm-blooded animals, in general, the bodies are covered with hair or feathers. The whale is destitute of hair; but, besides the protection which is afforded by the extraordinary thick- ness of its skin, and the stratum of fat—a bad conductor of caloric —with which the skin is lined, as the animal constantly resides in the water, it is not subjected to the same vicissitudes of temperature as land animals. The seals, bears, and walruses, which seek their food in the same seas, sleep on land. They have a coating of hair to protect them. In the cases of some of the birds of the genus Anas, of northern regions, we meet with a singular anomaly,—the whole of the circumference of the anus being devoid of feathers; but, to make amends for this deficiency, the animal has the power of secreting an oleaginous substance, with which the surface is kept constantly smeared. It may be remarked, that we do not find the quantity of feathers on the bodies of birds to be proportionate to the cold of the climates in which they reside, as is pretty universally the case regarding the quantity of hair on the mammalia. Man is compelled to have recourse to clothing, for the purpose of preventing the sudden abstraction or reception of heat. This he does by covering himself with substances which are bad conductors of caloric, and retain an atmosphere next to the surface, which is warmed by the caloric of the body. He is compelled, also, in the colder seasons, to have recourse to artificial temperature. It will be obvious, from what has already been said, that the greater the degree of activity of any organ or set of organs, the greater will be the heat developed; and in this way muscular exer- tion and digestion influence its production. By an attention to all these points, and by his acquaintance with the physical laws relative to the developement.and propagation of caloric, man is enabled to live amongst the arctic snows, and to exist in climates, where the temperature is frequently for a length of time upwards of 150° lower than that of his own body. The contrivances adopted in the polar voyages, under the direction of Captain Parry and others, are monuments of ingenuity directed to obviate one of the greatest obstacles to prolonged existence in in- hospitable regions, for which man is naturally incapacitated, and for which he attains the capability solely by the exercise of that superior intellect with which he has been vested by the Author of his being. In periods of intense cold, the extreme parts of the body do not possess the necessary degree of vitality to resist congelation, unless they are carefully protected. In the disastrous expedition of Napo- leon to Russia, the loss of the nose and ears was a common casualty; and, in arctic voyages, frost-bites occur in spite of every care.* a Larrey, Memoires de Chirurgie Militaire et Campagnes, torn. iv. p. 91, 106, & 123, Paris, 1817. CALORIFICATION. 247 When the temperature of the whole body sinks to about 78° or 79°, death takes place, preceded by the symptoms of nervous de- pression, which have been previously depicted. The counteracting influence, which is exerted, when the body is exposed to a temperature greatly above the ordinary standard of the animal, is as difficult of appreciation as that by which calorifi- cation is effected. The probability is, that, in such case, the disen- gagement of animal heat is suspended; and that the body receives heat from without, by direct, but not by rapid, communication, owing to its being an imperfect conductor of caloric. Through the agency of this extraneous heat, the temperature rises a limited number of degrees; but its elevation is checked by the evaporation, constantly taking place through the cutaneous and pulmonary trans- pirations. For this last idea we are indebted to Franklin,* and its correctness and truth have been amply confirmed. MM. Berger and Delaroche put into an oven, heated to from 120° to 140°, a frog, one of those porous vessels, called alcarazas—which permit the transudation of the fluid, within them, through their sides—filled with water at the animal heat, and two sponges, imbibed with the same water. The temperature of the frog at the expiration of two hours, was 99°; and the other bodies continued at the same. Having substituted a rabbit for the frog, the result was identical. On the other hand, having placed animals in a warm atmosphere, so saturated with humidity that no evaporation could occur, they received the caloric by communication, and their temperature rose; whilst inert, evaporable bodies, put into a dry stove, became but slightly warmed;—much less so, indeed, than the warm-blooded animals in the moist stove.b Hence they concluded, that evapora- tion is a great refrigerative agent when the body is exposed to ex- cessive heat; a conclusion which is likewise confirmed by the loss in weight, which animals sustain by the experiment. Dr. Edwards, in his experiments on the influence of physical agents on life, found, that warm-blooded animals have less power of producing heat, after they have been exposed for some time to an elevated temperature, as in summer,—whilst the opposite effect occurs in winter. He instituted a series of experiments, which con- sisted in exposing birds to the influence of a freezing mixture, first in February, and afterwards in July and August, and observing'in what degree they were cooled by remaining in this situation for equal lengths of time; the result of which was, that the same kind of animal was cooled six or eight times as much in the summer as in the winter months. This principle he presumes to be of great importance in maintaining the regularity of the temperature at the different seasons; even more so than evaporation, the effect of which, in this respect, he thinks, has been greatly exaggerated. a Works, iii. 294, Philad. 1809; and Sparks's edit. vi. 213, Boston, 1838. b Delaroche, in Journal de Physique, Ixxi. 289, Paris, 1810; Coutanecau, Diet, de Med. v. 23; and Magendie's Precis, ii. 509. 248 SECRETION. From several experiments on yellowhammers made at different periods in the course of the year, it would result, that the averages of their temperature ranged progressively upwards from the depth of winter to the height of summer, within the limits of five or six degrees of Fahrenheit, and the contrary was observed in the fall of the year. Hence, Dr. Edwards infers, and with every probability, that the temperature of man experiences a similar fluctuation.8 When exposed to high atmospheric temperature, the ingenuity of man has to be as much exerted as in the opposite circumstances. The clothing must be duly regulated according to physical principles,11 and perfect quietude be observed, so that undue activity of any of the organs that materially influence the disengagement of animal heat may be prevented. It is only within limits, that this refrigeratory action is sufficient. At a certain degree, the transpiration is inadequate, the temperature of the animal rises, and death supervenes. CHAPTER VII. SECRETION. We have yet to describe an important and multiple function, which also takes place in the intermediate system—in the very tis- sue of our organs—and which separates from the blood the various humours of the body. This is the function of secretion,—a term which has been applied both to the operation and the product. Thus, the liver is said to separate the bile from the blood by an action of secretion, and the bile is said to be a secretion. The organs that execute the various secretory operations differ greatly from each other. They have, however, been grouped by anatomists into three classes, each of which will require a general notice. 1. ANATOMY OF THE SECRETORY APPARATUS. The secretory organs have been divided into the exhalant, the follicular, and the glandular. The remarks made respecting the exhalant vessels, under the head of nutrition, will render it unnecessary to allude, in this place, to any of the apocryphal descriptions of them, especially as their very existence is supposititious. Many, indeed, imagine them to be nothing more than the minute radicles of ordinary arteries. a De l'Influence des Agens Physiques, p. 489; and Hodgkin and Fisher's transla- tion, Lond. 1832. b See the chapter on Clothing in the author's "Elements of Hygiene," p. 388, Philad. 1835. SECRETORY APPARATUS. 249 The follicle or crypt has the form of an ampulla or vesicle, and is situate in the substance of the skin, and mucous membranes; se- creting a fluid for the purpose of lubricating those parts. In the exhalant vessel, the secreted fluid passes immediately from the blood-vessel, without being received into any excretory duct; and, in the follicle, there is essentially no duct specially destined for the excretion of the humour. The follicle is membranous and vascular, having an internal cavity into which the secretion is poured; and the product is ex- creted upon the surface beneath which it is situate, either by a cen- tral aperture, or by a very short duct—if duct it can be called— generally termed a lacuna. Fig. 136. Secreting Arteries, and Nerves of the Intestines. a a. A portion of the intestine, b b. Part of the aorta, c c. Nerves following the branches of the aorta, to supply the intestine. The gland is of a more complex structure than the last. It con- sists of an artery which conveys blood to it; of an intermediate body,—the gland, properly so called,—and of an excretory duct to carry off the secreted fluid, and to pour it on the surface of the skin or mucous membrane. The blood-vessel, that conveys to the gland the material from which the secretion has to be operated, enters the organ, at times, by various branches; at others, by a single trunk, and ramifies in the tissue of the gland ; communicating at its extremities with the origins of the veins and of the excretory ducts. These ducts arise by fine radicles at the part where the arterial ramifications terminate; and they unite to form larger and less numerous canals, until they terminate in one large duct, as 250 SECRETION. in the pancreas; or in several, as in the lachrymal gland; the duct generally leaving the gland at the part where the blood-vessel enters. Of this we have a good exemplification in the kidney, (Fig. 139.) Besides these vessels, veins exist, which communicate with the vessels that convey blood to the gland, both for the formation of the humour and the nutrition of the organ, and which return the resi- duary blood to the heart. Lymphatic vessels are likewise there; and nerves,—which proceed from the ganglionic system,—form a network around the secreting arteries, as in Fig. 136, accompany them into the interior of the organ, and terminate, like them, in- visibly. Bordeu* was of opinion, that the glands, judging from the parotid, are largely supplied with nerves. The nerves, however, do not all belong to it, some merely crossing it in their course to other parts. Bichat,b from the small number sent to the liver, was induced to draw opposite conclusions to those of Bordeu. These may be looked upon as the great components of the glan- dular structure. They are bound together by cellular membrane, and have generally an outer envelope. The intimate texture of these organs has been a topic of much speculation. It is generally considered, that the final ramifications of the arterial vessels, with the radicles of the veins and excretory ducts, and the final ramifications of the lymphatic vessels and nerves, form so many small lobules, composed of minute, granular masses. Such, indeed, is the appearance the texture presents, when examined by the naked eye. Each lobule is conceived to contain a final ramification of the vessel or vessels that convey blood to the organ, a nerve, a vein, a lymphatic, and an excretory duct,—with cellular tissue binding them together. When the organ has an external membrane, it usually forms a sheath to the various vessels. The lobated structure is not equally apparent in all the glands. It is well seen in the pancreas, and in the salivary and lachrymal. The precise mode in which the blood-vessel, from the blood of which the secretion is effected, communicates with the excretory duct, does not admit of detection. Some have supposed, that between the termination of the blood-vessel and the commencement of the duct, a secretory vessel', or a spongy tissue specially charged with the function, exists, which conveys the secreted humour into the excre- tory duct. Of this, however, we have no evidence. Professor Miiller0 maintains, that the glandular structure consists essentially of a duct with a blind extremity, on whose parieties plexuses of blood-vessels ramify, from which the secretions are immediatelv produced,—a view which is confirmed by the pathological appear- ances, in a case of disease of the portal system, that fell under » Sur les Glandes, in 03uvres Completes, par M. Richerand, Paris, 1818. b Anat. General, torn. ii. c De Glandular. Secernent. Structura Penitiori, &c, Lips. 1830 ; or the English Edit., by Mr. Solly, Lond. 1839. PHYSIOLOGY OF SECRETION. 251 the author's observation, and is referred to under the Secretion of Bile. The opinion of Malpighi* was similar. He affirmed that such glands as the liver are composed of very minute bodies, called acini, from their resemblance to the stones of grapes; that these acini are hollow internally, and are covered externally by a network of blood- vessels ; and that these minute blood-vessels pour into the cavities of the acini the secreted fluid, from which it is subsequently taken up by the excretory ducts. Ruysch,b however, held, that the acini of Malpighi are merely convoluted vessels, and that they are continuous with the excretory ducts. In Malpighi's view, the secretory organ is a mere collection of follicles ; in Ruysch's, simply an exhalant membrane variously convoluted. " The chief, if not the only dif- ference," says a popular writer,0 " between the secreting structure of glands and that of simple surfaces, appears to consist in the dif- ferent number and the different arrangement of their capillary vessels. The actual secreting organ is in both cases the same,— capillary blood-vessel; and it is uncertain whether either its peculiar arrangement, or greater extent in glandular texture, be productive of any other effect than that of furnishing the largest quantity of blood-vessels within the smallest space. Thus convoluted and packed up, secreting organ may be procured to any amount that may be required, without the inconvenience of bulk and weight."d It is manifest then, that the simplest form of the secretory appa- ratus is this simple capillary vessel; and that the follicles and glands are structures of a more complex organization. 2. PHYSIOLOGY OF SECRETION. The uncertainty which rests upon the intimate structure of secre- ting organs, and upon the mode in which the different blood-vessels communicate with the commencement of the excretory duct, enve- lopes the function, executed by those parts, in obscurity. We see the pancreatic artery pass to the pancreas, ramify in its tissue, become capillary, and escape detection; and we see other vessels becoming larger and larger, and emptying themselves into vessels of greater magnitude, until, ultimately, all the secreted humour is con- tained in one large duct, which passes onwards and discharges its fluid into the small intestine. Yet if we follow the pancreatic artery as far back as the eye can carry us, even when aided by glasses of considerable magnifying power, or if we trace back the pancreatic duct as far as practicable, we find, in the former vessel, always arte- rial blood, and in the latter, always pancreatic juice. It must conse- * Opera Omnia, &c, p. 300, Lugd. Batav. 1687. b Epist. Anatom. qua Respondet Viro Clarissimo Hermann. Boerhaav., p. 45, Lugd. Batav. 1722. c Dr. Southwood Smith, in Animal Physiology, p. 115; Library of Useful Knowledge, Lond. 1829. d See Beclard, in art. Glande, Diet, de Med. x. 256, Paris, 1824. 252 SECRETION. quently, be between the part at which the artery ceases to be visible, and at which the pancreatic duct becomes so, that secretion is effected; and we cut the knot by asserting, that it occurs in the very tissue, parenchyma, or in the capillary system of the secretory organ. Conjecture, in the absence of positive knowledge, has been busy, at all times, in attempting to explain the mysterious agency by which we find such various humours separated from the same fluid; and, according as chemical, or mechanical, or exclusively vital doctrines have prevailed in physiology, the function has been referred to one or other of those agencies. The general belief, amongst the physiologists of the sixteenth and seventeenth centuries, was, that each gland pos- sesses a peculiar kind of fermentation, which assimilates to its own nature the blood passing through it. The notion of fermentation was, indeed, applied to most of the vital phenomena. It is now totally abandoned owing to its being purely imaginary, and inconsistent with all our ideas of the vital operations. When this notion passed away, and the fashion of accounting for physiological phenomena on mechanical principles usurped its place, the opinion prevailed, that the secretions are effected through the glands as through filters. To admit of this mechanical result, it was maintained, that all the secreted fluids exist ready formed in the blood, and that, when they respec- tively arrive at the different secretory organs, they pass through, and are received by the excretory ducts. Descartes" and Leibnitzb were warm supporters of this mechanical doctrine, although their views differed materially with regard to the precise nature of the opera- tion. Descartes supposed, that the particles of the various humours are of different shapes, and that the pores of the glands have respec- tively a corresponding figure; so that each gland permits those par- ticles only to pass through it which have the shape of its pores. Leibnitz, on the other hand, likened the glands to filters, which had their pores saturated with their own peculiar substance, so that they admitted this substance to pass through them, and excluded all others, —as paper, saturated with oil, will prevent the filtration of water. The mechanical doctrine of secretion was taught by Malpighi and by Boerhaave,c and it continued to prevail even till the time of Hal- ler. All the secretions were conceived to be ready formed in the blood, and the glands were looked upon as the sieves or strainers to , convey off the appropriate fluids or humours. In this view of the subject, all secretion was a transudation through the coats of the vessels,—particles of various sizes passing through pores adapted to them.d The mechanical doctrine of transudation, in this shape, is founded upon supposititious data; and the whole facts and arguments are so manifestly defective, that no refutation is necessary. It is now, indeed, wholly abandoned. MM. Magendie and Fodera have, a Tractatus de Homine, p. 18, Amstel. 1677. b Haller, Element. Physiol, vii. 3. c Prselectiones Academicaj, &c. edit. A. Haller. § 253, Gotting. 1740-1743. d Mascagni, Nova per Poros Inorganicos Secretionum Theoria. Rom. 1793, torn. ii. PHYSIOLOGY OF SECRETION. 253 however, revived the mechanical doctrine of late years, but under an essentially different form; and one applicable especially to the exhalations. The former gentleman,* believing that many of the exhalations exist ready formed in the blood, thinks, that the charac- ter of the exhaled fluid is dependent upon the physical arrangement of the small vessels, and his views repose upon the following experi- ments. If, in the dead body, we inject warm water into an artery passing to a serous membrane, as soon as the current is established from the artery to the vein, a multitude of minute drops may be observed oozing through the membrane, which speedily evaporate. If, again, a solution of gelatine, coloured with vermilion, be injected into all the vessels, it will often happen, that the gelatine is deposited around the cerebral convolutions, and in the anfractuosities, without the colouring matter escaping from the vessels, whilst the latter is spread over the external and internal surface of the choroid. If, again, linseed oil, also coloured with vermilion, forms the matter of the injection, the oil, devoid of colouring matter, is deposited in the articulations, that are furnished with large synovial capsules, no transudation takes place at the surface of the brain, or in the interior of the eye. Magendie asks, if these are not instances of true secretion taking place post mortem, and evidently dependent upon the physical arrangement of the small vessels; and whether it is not extremely probable, that the same arrangement must, in part at least, preside over exhalation during life 1 Fodera,b to whose experiments on the imbibition of tissues we had occasion to allude under the head of absorption, embraces the views of Magendie. If the vessels of a dead body, he remarks, be injected, the substance of the injection is seen oozing through the vessels; and if an artery and a vein be exposed in a living ani- mal, a similar oozing through the parietes is observable. This is more manifest if the trunk, whence the artery originates, be tied,— the fluid being occasionally bloody. If the jugular veins be tied, not only does cedema occur in the parts above the ligatures, but there is an increase of the salivary secretion. It is not necessary to adduce the various experiments of Fodera, relating to this topic, or those of Harlan, Lawrence and Coates, or of Dutrochet, Faust, Mitchell, and others. They are of precisely the same character as those that we have previously described regarding the imbibition of tissues; and transudation is only imbibition or soaking from within to without: Magendie and Fodera, indeed, conclude, that one pri- mary physical cause of exhalation is the same as that of absorption, —namely, imbibition. Another physical cause, adduced by Magendie, is the pressure experienced by the blood in the circulatory system, which, he con- ceives, contributes powerfully to cause the more aqueous part to pass through the coats of the vessels. If water be forcibly injected, * Precis. &c. edit. cit. ii. 444. b Magendie's Journal de Physiologie, iii. 35; and Recherches, &c. sur PAbsorption •et P Exhalation, Paris, 1824. vol. ii. 22 254 SECRETION. by means of a syringe, into an artery, all the surfaces, to which the vessel is distributed, as well as the larger branches and the trunk itself, exhibit the injected fluid oozing in greater abundance accord- ing to the force exerted in the injection. He farther remarks, that if water be injected into the veins of an animal, in sufficient quantity to double or treble the natural amount of blood, a considerable dis- tension of the circulatory organs is produced; and, consequently, the pressure, experienced by the circulating fluid, is largely aug- mented. If any serous membrane be now examined,—as the peri- toneum,—a serous fluid is observed issuing rapidly from its surface, which accumulates in the cavity, and produces a true dropsy under the eyes of the experimenter, and, occasionally, the colouring part of the blood transudes at the surface of certain organs, as the liver, spleen, &c. Hamberger, again, broached the untenable physical hypothesis, that each secreted humour is deposited in its proper secretory organ, by virtue of its specific gravity.* It is obvious, that all these speculations proceed upon the belief, that the exhalations exist ready formed in the blood; and that, consequently, the act of secretion, so far as concerns them, is one of separation or of secerning,—not of fresh formation. That this is the case with the more aqueous secretions is probable, and not impossible with regard to the rest. Organic chemistry is subject to more difficulties in the way of analysis than inorganic ; and it can be readily understood, that, in a fluid so heterogeneous fas the blood, the discovery of any distinct humour may be impracticable. Of course, the elements of every fluid, as well as solid, must be con- tained in it; and we have already seen, that not merely the inor- ganic elements, but the organic or compounds of organization, have been detected by the labours of Chevreul and others. There are, indeed, some singular facts connected with this subject. MM. Pro- vost and Dumasb having removed the kidneys in cats and dogs, and afterwards analyzed the blood, found urea in it—the characteristic element of urine. This principle was contained in greater quantity, the longer the period that had elapsed after the operation; whilst it could not be detected in the blood, where the kidneys existed. The experiment was soon afterwards repeated by Vauquelin and Segalasc with the same results. The latter introduced urea into the veins of an animal, whose kidneys were untouched; he was unable to detect the principle in the blood; but the urinary secretion was largely augmented after the injection. Whence he concludes that urea is an excellent diuretic. More recently, MM. Gmelin and Tiedemann, in association with M. Mitscherlich,d have arrived, experimentally, * See Adelon, Physiologie de I'Homme, 2de edit. iii. 455, Paris, 1829 ; and Riche- rand's Elemens de Physiologie, 13eme edit, par M. B6rard ain6, p. 176, Bruxelles, 1837. b Annales de Chimie, torn. xxii. & xxxiii. 90. c Magendie, Precis, &c. ii. 478. d Tiedemann und Treviranus, Zeitschrift fiir Physiol. B. v. Heft i; and Brit, and Foreign Review, p. 592, for April, 1836. THEORIES. 255 at the same conclusions as MM. Prevost and Dumas. The exis- tence of urea in the fluid ejected from the stomach of the animal was rendered probable, but there were no traces of it in the faeces or the bile. The animal died the day after the extirpation of the second kidney. They were totally unable to detect either urea, or sugar of milk in the healthy blood of the cow. These circumstances would favour the idea, that certain of the secretions may be formed in the blood, and may simply require the intervention of a secreting organ to separate them ;* but the mode in which such separation is effected, is entirely inexplicable under the doctrine of simple mechanical filtration or transudation. It is unlike any physical process, which can be imagined. The doctrines of filtration and transudation can apply only to those exhalations, in which the humour has undergone no apparent change; and it is obviously impossible to specify these, in the imperfect state of our means of analysis. In the ordinary aqueous secretions, simple transudation may embrace the whole process; and, therefore, it is unnecessary to have recourse to any other explanation ; especially after the experiments instituted by Magendie, supported by patholo- gical observations in which there has been partial oedema of the legs, accompanied by more or less complete obliteration of the veins of the infiltrated part,—the vessels being obstructed by fibrinous coagula, or compressed by circumjacent tumours. It is obvious, that ascites or dropsy of the lower belly may be frequently occa- sioned by obstruction of the portal circulation in the liver, and that in this way, we may account for the frequency with which we find a union of hydropic and hepatic affections in the same individual. The same pathological doctrine, founded on direct observation, has been extended to phlegmatia dolens or swelled leg; an affection occurring in the puerperal state, and which has often been found connected with obstruction in the great veins that convey the blood back from the lower extremity. The generality of physiologists have regarded the more complex secretions—the follicular and the glandular—as the results of chemi- cal action ; and under the view, that these secretions do not exist ready formed in the blood, and that the elements alone are contained in that fluid, it is impossible not to admit that chemical agency must be exerted. In support of the chemical hypothesis, which has ap- peared under various forms,—some, as Keill,b presuming that the secretions are formed in the blood, before they arrive at the place appointed for secretion ; others, that the change is effected in the glands themselves,—the fact of the formation of a number of sub- stances from a very few elements, provided these be united in different proportions, has been adduced. For example: take the elementary bodies, oxygen and azote. These, in one proportion, form atmo- spheric air; in another, nitrous oxide; in another, nitric oxide? in a » Dr. W. Philip, in Lond. Med. Gazette for March 25th, 1837, p. 952. b Tentamina Medico-Physica, iv.; and Haller, Element. Physiolog. &c. vii. 3. 256 SECRETION. fourth, hyponitrous acid; in a fifth, nitrous acid; in a sixth, nitric acid, &c. substances which differ as much as the various secretions differ from each other and from the blood. Many of the compounds of orga- nization likewise exhibit by their elementary composition, that but a slight change is necessary, in order that they may be converted into each other. Dr. Prout* has exhibited this close alliance between three substances—urea, lithic acid, and sugar—and has shown how they may be converted into each other, by the addition or subtraction of single elements of their constituents. Urea is composed of two atoms of hydrogen, and one of carbon, oxygen and azote respec- tively ; by removing one of the atoms of hydrogen and the atom of nitrogen, it is converted into sugar; by adding to it an additional atom of carbon, into lithic acid. Bostock,b—who is disposed to push the application of chemistry to the explanation of the functions as far as possible,—to aid us in conceiving how a variety of substances may be produced from a single compound, by the intervention of physical causes alone, sup- poses the case of a quantity of the materials adapted for the vinous fermentation being allowed to flow from a reservoir, through tubes of various diameters, and with various degrees of velocity. " If we were to draw off portions of this fluid in different parts of its course or from tubes, which differed in their capacity, we should, in the first instance, obtain a portion of unfermented syrup; in the next, we should have a fluid in a state of incipient fermentation; in a third, the complete vinous liquor; while, in a fourth, we might have acetous acid." Any explanation, however, founded upon this loose analogy, is manifestly too physical: this Bostock admits, for he subsequently remarks, that "if we adopt the chemical theory of secretion, we must conceive of it as originating in the vital action of the vessels, which enables them to transmit the blood, or certain parts of it, to the various organs or structures of the body, where it is subjected to the action of those reagents, which are necessary to the production of these changes." The admission of such vital agency, in some shape, seems to be indispensable. Attempts have been made to establish secretion as a nervous action; and numerous arguments and experiments have been brought forward in support of the position. That many of the secretions are affected by the condition of the mind is known to all. The act of crying, in evidence of joy or sorrow; the aug- mented action of the salivary glands at the sight of pleasant food; the increased secretion of the kidney during fear or anxiety, and the experimental confirmation, by Mr. Hunter, of the truth of the common assertion—that the she-ass gives milk no longer than the impression of the foal is on her mind; the skin of her foal, thrown over the back of another, and frequently brought near her, being sufficient to renew the secretion,—sufficiently indicate, that the a Medico-Chirurg. Transact, viii. 540. b Physiol. 3d edit. p. 519, Lond. 1836, THEORIES. 257 organs of secretion can be influenced through the nervous system in the same manner as the functions of nutrition and calorification." The discovery of galvanism naturally suggested it as an im- portant agent in the process,—or rather suggested, that the nervous fluid strongly resembles it. This conjecture seems to have been first hazarded by Berzelius, and by Sir Everard Home i1* and, about the same time, an experiment was made by Dr. Wollaston,c which he conceived to throw light upon the process. He took a glass tube, two inches high, and three quarters of an inch in diameter; and closed it at one extremity with a piece of bladder. He then poured into the tube, a little water, containing ^ioth of its weight of muriate of soda, moistened the bladder on the outside, and placed it upon a piece of silver. On curving a zinc wire so that one of its extremities touched the piece of metal, and the other dipped into the liquid to the depth of an inch, the outer surface of the bladder immediately indicated the presence of pure soda; so that, under this feeble electric influence, the muriate of soda was decomposed, and the soda, separated from the acid, passed through the bladder. M. Foderad performed a similar experiment, and found, that whilst ordinary transudation frequently required an hour before it was evidenced, it was instantaneously exhibited under the galvanic influence. On putting a solution of prussiate of potassa into the bladder of a rabbit; forming a communication with the solution by means of a copper wire; and placing on the outside, a cloth soaked in a solution of sulphate of iron, to which an iron wire was attached; he found, by bringing these wires into communication with the galvanic pile, that the bladder or the cloth was suddenly coloured blue, according as the galvanic current set from without to within, or from within to without;—that is, according as the iron wire was made to communicate with the positive pole, and the copper wire with the negative, or conversely. But it is not necessary that there should be any communication with the galvanic pile. If an animal membrane, as a bladder containing iron filings, be immersed in a solution of sulphate of copper, the sulphuric acid will penetrate the membrane to reach the iron, with which it forms a sulphate, and the metallic copper will be deposited on the lowerj surface of the membrane;' the animal membrane in such case, offering no obsta- cle to the action of the ordinary chemical affinities. The disposition, with some of the chemical physiologists, is to resolve secretion into a mere play of electric affinities. Thus, M. Donnef affirms, that from the whole cutaneous surface is secreted 1 For several examples of the same kind, see Fletcher's Rudiments of Physiology, part ii. b. p. 10, Edinb. 1836. b Lectures on Comp. Anat. iii. 16, Lond. 1836; and v. 154, Lond. 1828. c Philosoph. Mag. xxxiii. 438. d Magendie's Journal de Physiologie, iii. 35; and Researches, &c, sur PAbsorption et PExhalation, Paris, 1824. • Dr. Robert E. Rogers in the American Journal of the Medical Sciences, p. 291, for August, 1836. See, also, the observations of Prof. Mitchell and Dr. Draper, referred to at pages 78 and 79 of this volume. r Annales de Chimie, &c., lvii. 400; and Journal Hebdomad., Fev. 1834. 22* 258 SECRETION. an acid humour, whilst the digestive tube, except in the stomach, secretes an alkaline mucus; and hence, he infers, that the external acid, and the internal alkaline membranes of the human body repre- sent the two poles of a pile, the electrical effects of which are appre- ciable by the galvanometer. On placing one of the conductors of the instrument in contact with the mucous membrane of the mouth, and the other in contact with the skin, the magnetic needle, he affirms, deviated fifteen, twenty, and even thirty degrees, according to its sensibility; and its direction indicated, that the mucous or alkaline membrane took negative, and the cutaneous membrane, positive electricity. He further asserts, that, between the acid stomach and the alkaline liver, extremely powerful electrical currents are formed. These experiments do not, however, aid us materially in our solution of the phenomena of secretion. They exhibit merely electric phe- nomena dependent upon difference of chemical composition. This is, indeed, corroborated by the experiments of M. Donne* himself on the secretions of vegetables. He observed electrical phenomena of the same kind in them, but, he says, electric currents in vegetables are not produced by the acid or alkaline conditions of the parts as in animals, the juice of fruits being always more or less acid. Ex- periments of M. Biot, however, show, that the juices, which arrive by the pedicle, are modified in some part of the fruit, and M. Donne thinks it is perhaps to this difference in the chemical composition of the juices of the two extremities, that the electrical phenomena are to be attributed. The effects of the section of the pneumogastric nerves on the functions of digestion and respiration have been given elsewhere, at some length. It was there stated, that when digestion was suspended by their division, Dr. Wilson Philip* was led to ascribe the suspension to the secretion of the gastric juice having been arrested; an opinion, which Sir B. Brodie had been induced to form previously, from the results of experiments, which showed, that the secretion of urine is suspended by the removal or destruction of the brain; and that when an animal is destroyed by arsenic, after the division of the pneumo- gastric nerves, all the usual symptoms are produced, except the pecu- liar secretion from the stomach. Sir B. Brodie did not draw the conclusion, that the nervous influence is absolutely necessary to secretion, but that it is a step in the process, and the experiments of Magendieb on the effect of the division of the nerve of the fifth pair on the nutritive secretion of the cornea, confirm the position. We have, indeed, numerous evidences, that the nervous, system cannot be indispensable to secretion. In all animals, this power must exist, yet there are some in which no nervous system is apparent. Bostock' has given references, in a note, to cases of monstrous or deformed foetuses, born with many of their organs fully developed, yet where there was no nervous system. It may be said, however, that, in all s Lond. Med. Gazette for March 18, and March 25, 1837. b Precis, &c. ii. 489. c Physiology, edit. cit. p. 525, Lond. 1836. THEORIES. 259 these cases, an organic nervous system must have existed; but setting aside the cases of animals, we have the most indisputable testimony of the existence of secretion in the vegetable, in which there is no nervous system, or, at the most, a rudimental one; yet •the function is accomplished as perfectly, and perhaps in as multiple a manner, as in man. It is manifest, therefore, that this is one of the vital actions occurring in the very tissue of organs, of which we have no more knowledge than we have of the capillary actions in general. All that we know is, that in particular organs various humours are secreted from the blood, some of which can be detected in that fluid, others not, but we are ignorant of the precise agency, by which this mysterious process is effected.* In cases of vicarious secretion, we have the singular phenomenon of organs assuming an action for which they were not destined. It the secretion from the kidney, for example, be arrested, urine is oc- casionally found in the ventricles of the brain, and, at other times, a urinous fluid has been discharged by vomiting or by cutaneous tran- spiration :b the capillaries of these parts must, consequently, have assumed the functions of the kidney, and to this they must have been excited by the presence of urea, or of the elements of the urinary secretion in the blood—a fact, which exhibits the important in- fluence, that the condition of the blood must exert on the secre- tions, and, indeed, on nutrition in general. It is thus that many ot our remedial agents, alkalies, the preparations of iodine, fee- produce their effects. They first enter the mass of blood, and, by circulating in the capillary system, induce a modification of its func- tions. There are other cases, again, in which the condition of the blood being natural, the vessels of nutrition may take on morbid ac- tion. Of this we have examples in the ossification of organs, which, in the healthy condition, have no osseous constituent; in the deposi- tion of fat in cases of diseased ovaria; and in the altered secretions produced by any source of irritation in a secreting organ. In describing the physiology of the different secretions, one ot three arrangements has usually been adopted; either according to the nature of the secreting organ, the functions of the secreted fluid, or its chemical character. , , „. i , j u tvt „ The first of these has been followed by Bichat and by Magen- die,6 who have adopted the division into exhaled, follicular and glandular secretions. It is the arrangement followed by Lepelletier, Except that he substitutes the term perspiratory for exhaled. Ac- cording to the second, embraced byBoyer,* Sabatier, and Adelon/ they are divided into recrementitial secretions, or such as are taken up by internal absorption and re-enter the circulation, and into ex- a Elliotson's Human Physiology, i. 261 Lond 1840; and Carpenter, Principles of General and Comparative Physiology, p. 350, Lond. 18J9. > Haller, Elementa Physiologioe, lib. yn. b. i.J 9. c Precis de Physiologie, 2de edit. p. ii. 343, Pans, 1185. d Anatomie, 2de edit i. 8, Paris, 1803. • Traite Complet d'Anatomie, Paris, 1791. f Physiologie de I'Homme, edit. cit. iii. 438. 260 SECRETION. crementitial, or such as are evacuated from the body and constitute the excretions. Some physiologists add a third division—the recre- mento-excrementitial,—in "which a part of the humour is absorbed and the remainder ejected. Lastly, the division according to chemical character, has been followed, with more or less modifica- tion, by Plenck,* Richerand,b Blumenbach,0 Young,d and Bostock:e the last of whom, one of the most recent writers, has eight classes: —the aqueous, albuminous, mucous, gelatinous, fibrinous, oleaginous, resinous, and saline. To all of these classifications cogent objec- tions might be made. The one we shall follow is the anatomical, not because it is the most perfect, but because it is the course that has been usually adopted throughout this work. OP THE EXHALATIONS. All the exhalations take place in the areolae and internal cavities of the body, or from the skin and mucous membranes:—hence their division into internal and external. The former are re crementitial, the latter recremento-excrementitial. To the class of internal exha- lations belong: 1. The serous exhalation. 2. The serous exhalation of the cellular membrane. 3. The adipous exhalation of the cel- lular membrane. 4. The exhalation of the marrow. 5. The syno- vial exhalation. 6. The exhalation of the colouring matter of the skin, and of other parts; and 7. The areolar exhalation. To the class of external exhalations belong; 1. That of the skin or cuta- neous transpiration. 2. The exhalation of the mucous membranes. 1. INTERNAL EXHALATIONS. a. The Serous Exhalation. This is the fluid secreted by the serous membranes that line the various cavities of the body;—as the pleura, pericardium, perito- neum, arachnoid coat of the brain, and tunica vaginalis testis. Rudolphif asserts, that serous membranes are incapable of inflam- mation, are not vascular, and do not secrete; but that the secretions of shut sacs take place from the subjacent parts, and transude the serous membranes, which, in his view, are, consequently, a kind of cuticle. In a physiological consideration this is not of moment; and anatomically it only concerns the layer that covers the surface, whether it resemble the cuticle or not. From these membranes a fluid is exhaled, which is of an albumi- nous character, considerably resembling the serum of the blood, » The Chemico-Physiological Doctrine of the Fluids, &c. translated by Dr. Hooper, Lond. 1797. b Elemens de Physiologie, 13 eme 6dit. chap. vi. Bruxelles, 1837. « Physiology, by Elliotson, 4th edit. Lond. 1828. d Medical Literature, p. 104, Lond. 1813. e Physiology, 3d edit. p. 48, L->nd. 1836. t Grundriss der Physiologie, 113; and Hodgkin's Lectures on the Morbid Anatomy of the Serous and Mucous Membranes, P. i. p. 27, Lond. 1836. EXHALATIONS—SEROUS—ADIPOUS. 261 except in containing less albumen. M. Donne* says it is always alkaline in the healthy state. In health, this fluid never accumulates in the cavities; the absorbents taking it up in proportion as it is deposited; but if, from any cause, the exhalants should pour out a larger quantity than usual, whilst the absorbents are not propor- tionably excited, accumulation may take place; or the same effect may ensue if the exhalants pour out no more than their usual quan- tity, whilst the absorbents do not possess their due activity. Under either circumstance, we have an accumulation or dropsy. The exhaled fluid probably transudes through the parietes of the arteries, and re-enters the circulation by imbibition through the coats of the veins. If we kill an animal and open it immediately after- wards, this exhalation appears in the form of a halitus or vapour, and the fluid is seen lubricating the free surface of the membrane. This, indeed, appears to be its principal office; by which it favours the motion of the organs upon each other. The serous exhalations probably differ somewhat in each cavity, or according to the precise structure of the membrane. The dif- ference between the chemical character of the fluid of the dropsy of different cavities would lead to this belief. As a general rule, accord- ing to Dr. Bostock,b the fluid from the cavity of the abdomen con- tains the greatest proportion of albumen, and that from the brain the least; but many exceptions occur to this.0 b. Serous Exhalation of the Cellular Membrane. The cellular membrane, wherever existing, is kept moist by a serous fluid, analogous to that exhaled from serous membranes, and which appears to have the same uses,—that of facilitating the motion of the lamellas or plates on each other, and consequently of the organs, between which the cellular tissue is placed/1 When this secretion collects, from the causes mentioned in the last section, the disease, called adema or anasarca, is induced. c. Adipous Exhalation of the Cellular Membrane. Considerable diversity of opinion has prevailed regarding the pre- cise organ of the secretion of fat. Haller supposed that the sub- stance exists ready formed in the blood, and that it simply transudes through the pores of the arteries; and Chevreul and others have given some countenance to this opinion, by the circumstance of their having met with a fatty matter in that fluid. Anatomists have, like- wise, been divided upon the subject of the precise tissue into which the fat is deposited; some believing it to be the ordinary cellular tissue, into which it is dropped by the agency of appropriate vessels; a Journal Hebdomad. Fevrier, 1834. b Op. citat. p. 485. c Burdach's Physiologie als Erfahrungswissenschaft, v. 184, Leipz. 1835. d Weber's Hildebrandt's Handbuch der Anatomie, i. 232, Braunschweig, 1830. 262 SECRETION. others, as Malpighi* and William Hunter,b believing in the existence of a peculiar adipous tissue, consisting, according to Beclard,0 of small bursas or membranous vesicles, which inclose the fat, and are found in the areola? of the cellular tissue. These vesicles are said to vary greatly in size: generally, they are round and globular; and, in certain subjects, receive vessels, that are very apparent. They form so many small sacs without apertures, in the interior of which are filaments arranged like septa. In fatty subjects, these adipous vesicles are very perceptible, being attached to the cellular tissue andneighbouring parts by a vascular pedicle. M. Raspaild affirms, that there is the most striking analogy be- tween the nature of the adipous granules and that of the amylaceous grains. As in the case of fecula, each adipous granule is composed of at least one integument, and an inclosed substance, both of which are as slightly azoted as fecula; and both fecula and fat are equally inservient to the nutrition of the organs of developement: whenever there is excess of life and activity, the fat is seen to disappear, and whenever there is rest, it accumulates in its reservoirs. If a por- tion of fat be examined, it is found to consist of an outer vesicle with strong membranous parietes, containing small adipous masses readily separable from each other, each invested with a similar, but slighter, vesicular membrane; and these, again, contain others still more minute, until ultimately we come to the vesicles that invest the adipous granules themselves. Each of these masses adheres, at some point of its surface, to the inner surface of the vesicle that incloses it by a hilum in the same manner as the grain of fecula. All the vesicles, but especially the outermost and strongest, have a reddish vascular network on their surface, the vessels of which augment in size, as they approach the part where the vesicle is adherent, and there they open into one of the vessels of the larger vesicle that incloses them. The arrangement of this tissue, as well as the quantity of fat, varies in different parts of the body. It is always found in the orbit, on the sole of the foot, and at the pulps of the fingers and toes. The subcutaneous cellular tissue, and that covering the heart, kidneys, &c, also generally contain it: but it is never met with in the eyelids, scrotum, or within the cranium.6 Fat is exhaled by the secretory vessels in a fluid state; but after it is deposited, it becomes more or less solid. According to the researches of ChevreuP" and Braconnot, human fat is almost always a De Omento, Pinguedine et Adiposis Ductibus, in Oper. Lond. 1687. b Medical Observations and Inquiries, vol. ii. Lond. 1757. c Art. Adipeux, in Dictionnaire de Medecine, torn. i.; and Elements of General Anatomy, translated by Togno, p. 128, Philad. 1830. d Chimie Organique, p. 183, Paris, 1833. e Geddings, art. Adipose Tissue, in Amer. Cyclop, of Pract. Medicine, part ii. p. 215, Philad. 1833 ; and Craigie, art. Adipose Tissue, in Cycl. Anat. and Physiol, part i. p. 56, Lond. 1835. 3 * { Recherches Chimiques sur les Corps Gras, &c, Paris, 1823; Magendie's Journal de Physiologie, torn. iv.; Von Schlechtendal, art. Fett, in Encycl. Worterb. der Medic. Wissenseh. xii. 131, Berlin, 1835; Henle, ibid. xii. 135; and W. T. Brande, art. Fat, Cyclopaed. Anat. and Physiol. August, 1837, p. 231. EXHALATIONS-ADIPOU & 263 of a yellow colour ; inodorous, and composed of two portions;—the one fluid, and the other concrete, which are themselves composed, but in different proportions, of two new immediate principles, to which the former chemist gave the names elaine and stearine respec- tively. It is probable, that chemical analysis would exhibit the fat to vary in different parts of the body, as its sensible properties are manifestly different. Sir Everard Home,a on loose analogies and inconclusive arguments, has advanced the opinion, that it is more than probable, that fat is formed in the lower portion of the intestines, and from thence is carried, through jhe medium of the circulating blood, to be deposited in almost every part of the body. " When there is a great demand for it, as in youth, for carrying on growth, it is laid immediately under the skin, or in the neighbourhood of the abdomen. When not likely to be wanted, as in old age, it is depo- sited in the interstices of muscular fibres, to make up in bulk for the wasting of these organs." M. de Blainvilleb is of opinion, that fat is derived from venous blood, and that it is exhaled through the coats of the vessels. This opinion he founds on the mode in which the fat is distributed in the omenta along the course of the vein; and he affirms, that he has seen it flow out of the jugular vein in a dead elephant. But this last fact, as Lepelletierc has judiciously remarked, proves nothing more than that the fat—taken up by the absorbents, from the vesicles, in which it had been deposited by the exhalants—had been conveyed into the venous blood with other absorbed matters. It in no wise shows, that the venous blood is the pabulum of the secretion, or that the veins accomplish it. The uses of the fat are both general and local. The great general use is, by some physiologists, conceived to be,—to serve as a provi- sion in cases of wasting indisposition; when the digestive function is incapacitated for performing its due office, and emaciation is the consequence. In favour of this view, the rapidity with which fat disappears after slight abstinence has been urged, as well as the facts, connected with the torpidity of animals, which are always found to diminish in weight during this state. Professor Mangili, of Pavia, procured two marmots from the Alps, on the 1st of December. The larger weighed 25 Milanese ounces; the smaller only 22ith; on the 3d of January, the larger had lost fths of an ounce, and the smaller Hlhs- 0n the 5th of February, the larger weighed only 22£; the smaller 21. Dr. Monro kept a hedgehog from the month of November to the month of March following, which lest, in the meanwhile, a considerable portion of its weight. On the 25th of December, it weighed 13 ounces and 3 drachms; on the 6th of February, 11 ounces and 7 drachms; and on the 8th of March, 11 ounces and 3 drachms. The loss was 13 grains daily.d The local uses of fat are chiefly of a physical character. On the » Lect. on Comp. Anat. i. 468, Lond. 1814, and vol. vi., Lond. 1828; and Philos. Transact. 1821, p. 34. b De POrganisation des Animaux, &c, Paris, lw5. c Physiologie Medicale et Philosophique, ii. 496, Paris, 1832. d Fleming's Philosophy of Zoology, ii. 59, Edinb. 1822. 264 SECRETION. sole of the foot it diminishes the effects of pressure, and its use is the same on the nates: in the orbit, it forms a kind of cushion, on which the eyeball moves with facility; and when in certain limits it gives that rotundity to the frame, which we are accustomed to regard as symmetry. Dr. Fletcher," indeed, considers its principal use to be, to fill up interstices, and thus to give a pleasing contour to the body. In another place, it was observed, that fatty substances are bad con- ductors of caloric; and hence that it may tend to preserve the tem- perature of the body in cold seasons ; a view which is favoured by the fact, that many of the arctic animals are largely supplied with fat beneath the common integuments; and it has been affirmed, that fat people generally suffer less than lean from the cold of winter. It is obviously impracticable to estimate, accurately, the total quantity of fat in the body. It has been supposed, that, in an adult male of moderate size, it forms 2Vth of the whole weight; but it is doubtful whether we ought to regard this as even an approximation; the data being so inadequate. In some cases of polysarcia or obesity, the bulk of the body has been enormous. The case of a girl is de- tailed, who weighed 256 pounds, when only four years old.b A man of the name of Bright, at Maiden, England, weighed 728 pounds; and the celebrated Daniel Lambert, of Leicester, England, weighed 739 pounds a little before his death, which occurred in the fortieth year of his age.c The circumference of his body was three yards and four inches; of his leg one yard and one inch. His coffin was six feet four inches long ; four feet four inches wide ; and two feet four inches deep. Dr. Elliotsond says he saw a female child, but a year old, who weighed sixty pounds. She had begun to grow fat at the end of the third month. In these cases, the specific gravity of the body may be much less than that of water.6 It is said, that some time ago there was a fat lighterman on the river Thames, " who had fallen overboard repeatedly, without any farther incon- venience than that of a good ducking; since though he knew nothing whatever of the art of swimming, he always continued to flounder about like a firkin of butter, till he was picked up."f In some of the varieties of the human family we meet with sin- gular adipous deposits. In the Bosjesman female vast masses of fat accumulate on the buttocks, which give them the most extravagant appearance. The projection of the posterior part of the body, in one subject, according to Barrow,g measured five inches and a half 1 Rudiments of Physiology, part iii., by Dr. Lewins, p. 71, Edinb. 1837. b Philos. Transact No. 185. c Good's Study of Medicine, Class vi. Ord. 1. Gen. 1. Sp. 1. d Human Physiology, Lond. 1841, P. i. 301; and Fletcher's Rudiments of Physiology, Edinburgh, 1835, P. i. p. 123. e Art. Schwimmen in Pierer's Anat. Phys. Real Worterb. vii. 392, Altenburg, 1827; and Weber's Hildebrandt's Handbuch der Anatomie, B. i. s. 244, Braunschweig, 1830. For various eases of great obesity, see Choulant, in art. Fett bereitung, in Pierer, op. citat B. 3. s. 53; A. L. Richter, in Encyclopadisches Worterbuch der Medicinischen Wissenschaften, Band. i. s. 733, art. Adiposis, Berlin, 1828; and Fletcher's Rudiments of Physiology. t Fletcher, op. citat p. 71. « Travels, p. 281. EXHALATIONS—ADIPOUS. 265 from a line touching the spine. " This protuberance," he remarks, " consisted of fat, and when the woman walked, had the most ridicu- lous appearance imaginable, every step being accompanied with a quivering and tremulous motion, as if two masses of jelly were attached behind." The " Hottentot Venus," who had several pro- jections, measured more than nineteen inches around the haunches; and the projection of the hips exceeded 64; inches. Dr. Somerville* found on dissection, that the size of the buttocks arose from a vast mass of fat, interposed between the integuments and muscles, which equalled four fingers' breadth in thickness. It is singular, that, according to the statement of this female, which is corroborated by the testimony of Mr. Barrow, the deposition does not take place till the first pregnancy. Pallasb has described a variety of sheep—the ovis steatopyga or "fat-buttocked,"—which is reared in immense flocks by the pastoral tribes of Asia. In it; a large mass of fat covers the nates and occupies the place of the tail. The protuberance is smooth beneath, and resembles a double hemisphere, when viewed behind; the os coccygis or rump-bone being perceptible to the touch in the notch between the two. They consist merely of fat; and, when very large, shake in walking like the buttocks of the female Bosjesman. Mr. Lawrence0 remarks, that there are herds of sheep in Persia, Syria, Palestine and some parts of Africa, in which the tail is not wanting as in the ovis steatopyga, but retains its usual length and becomes loaded with fat. The circumstances, which favour obesity, are absence of activity and of excitement of all kinds; hence, for the purpose of fattening animals in rural economy, they are kept in entire darkness,—to de- prive them of the stimulus of light, and to favour sleep and muscular inactivity. Castration—by abolishing one kind of excitability—and the time of life at which the generative functions cease to be exerted, especially in the female, are favourable to the same result. d. Exhalation, of the Marrow. A fluid, essentially resembling fat, is found in the cavity of long bones, in the spongy tissue of short bones, and in the areola? of bones of every kind. This is the marrow. The secretory organ is the very delicate membrane which is perceptible in the interior of the long bones, lining the medullary cavity, and sending prolongations into the compact substance, and others internally, which form septa and spaces for the reception of the marrow. The cells, thus formed, are distinct from each other. From the observations of Howship,d it would seem probable, that the oil of bones is deposited in longitu- dinal canals, that pass through the solid substance of the bone, and through which its vessels are transmitted. This oil of bones is the * Medico-Chirurgical Transactions, vii. 157. b Spicilegia Zoologica. fasc. xi. p. 63. c Lectures on Physiology, Zoology, &c. p. 427, Lond, 1819. d Medico-Chirurg. Trans, vii. 393. vol. ii. 23 266 SECRETION. marrow of the compact structure, the latter term being generally restricted to this secretion when contained in the cavities of long bones; that which exists in the spongy substance being termed, by some writers, the medullary juice. The medullary membrane, called also the internal periosteum, con- sists chiefly of blood-vessels ramifying on an extremely delicate cel- lular tissue, in which nerves may likewise be traced. Berzelius examined marrow obtained from the thigh-bone of an ox, and found it to consist of the following constituents:—pure adipous matter, 96; skins and blood-vessels, 1; albumen, gelatine, extractive, peculiar matter, and water, 3. The marrow is one of the corporeal components, of whose use we can scarcely offer a plausible conjecture. It has been supposed to render the bones less brittle; but this is not correct, as those of the foetus, which contain little or no marrow, are less brittle than those of the adult; whilst the bones of old persons, in which the medullary cavity is extremely large, are more brittle than those of the adult. It is possible that it may be placed in the cavities of the bones,— which would otherwise be so many vacant spaces,—to serve the general purposes of the fat, when it is required by the system. The other hypotheses, that have been entertained on the subject, are not deserving of notice. e. Synovial Exhalation. Within the articular capsules, and the bursse mucosas,—which have been described under the head of muscular motion,—a fluid is secreted, which is spread over the articular surfaces of the bones, and facilitates their movements. Havers* considered this fluid to be secreted by synovial glands,— for such he conceived the reddish cellular masses to be, that are found in certain articulations. Hallerb strangely regarded the syno- via as the marrow, which had transuded through the spongy extre- mities of the bones; but, since the time of Bichat, every anatomist and physiologist has ascribed it to the exhalant action of the syno- vial membrane, which strongly resembles the serous membranes in form, structure, and functions, and whose folds constitute the pro- jections, which Havers mistook for glands.0 This membrane exists in all the movable articulations, and in the channels and sheaths in which the tendons play. The generality of anatomists regard the articular capsules as shut sacs; the membrane being reflected over the incrusting cartilages. Magendie, however, affirms, that he has several times satisfied himself, that the mem- branes do not pass beyond the circumference of the cartilages. From the inner surface of these membranes the synovia is exhaled, in the same manner as in other serous cavities. * De Ossibus, serm iv. c. 1; and Osteologia Nova, Lond. 1691. b Element. Physiol, iv. 11. c Beclard's Elements of General Anat., by Togno, p. 140. EXHALATIONS-SYNOVIAL. 267 Margueron* analyzed the synovia, obtained from the posterior extremity of the ox, and found it to consist of fibrous matter, 11.86; albumen, 4.52; chloride of sodium, 1.75; soda, 0.71; phosphate of lime, 0.70; and water, 80.46. M. Donne'1' says it is always alkaline in health; but in certain diseases it sometimes becomes acid. f. Exhalation of the Colouring Matter of the Skin and other parts. The nature of the exhalation, which constitutes the colouring matter of the rete mucosum, has already engaged our attention, when treating of the skin, under the Sense of Touch. It is presumed to be exhaled by the vessels of the skin, and to be deposited beneath the cuticle, so as to communicate the colours that characterize the different races. Such are regarded as the secretory organs by most anatomists and physiologists; but Gaultier,0 whose researches into the intimate constitution of the skin have gained him much celebrity, is of opinion, that it is furnished by the bulbs of the hair; and he assigns, as reasons for this belief, that the negro, in whom it is abundant, has short hair; that the female, whose hair is more beau- tiful and abundant than that of the male, has the fairest skin; and that when he applied blisters to the skin of the negro, he saw the colouring matter oozing from the bulbs of the hair, and deposited at the surface of the rete mucosum. Breschet, again, describes a par- ticular chromatogenous apparatus, for producing the colouring mat- ter, which is composed of a glandular or secreting parenchyma, situate a little below the papilla?, and having excretory ducts, which pour the colouring principle on the surface of the true skin. This mingles with the soft and diffluent mucous matter, the admixture producing the "pretended reticular body of Malpighi," and the epi- dermis or cuticle."1 He describes particular organs, or a " blenno- genous apparatus," for the secretion of this mucous matter. They consist of a glandular parenchyma, or organ of secretion, in the substance of the true skin; and of excretory ducts, which issue from the latter and deposit the mucous matter between the papillae. The composition of this pigment cannot be determined with pre- cision, owing to its quantity being too small to admit of examina- tion. Chlorine deprives it of its black hue, and renders it yellow. A negro, by keeping his foot for some time in water impregnated with this gas, deprived it of its colour and rendered it nearly white; but, in a few days, the black colour returned with its former inten- sity, This experiment was made with similar results on the fingers of a negro. Blumenbach6 thought, that the mucou.s pigment was formed chiefly of carbon ; and the notion has received favour with many. The uses of this pigment—as well as of that which lines the cho- a Annales de Chimie, xiv. 123. b Journal Hebdomad. Fevrier, 1834. <■ Recherches sur POrganisation de la Peau de I'Homme, &c. Paris, 1809, and 1811. d Nouvelles Recherches sur la Structure de la Peau, Paris, 1835. • Instit Physiol. § 274; and Elliotson's translation, 4th edit. Lond. 1828, 268 SECRETION. roid coat of the eye, the posterior surface of the iris, and of the ciliary processes—are detailed in another place.* g. Areolar Exhalation. Under this term, Adelonb has included different recrementitial secretions effected within the organs of sense, or in parenchymatous structures,—as the aqueous, crystalline, and vitreous humours of the eye, and the liquor of Cotugno, all of which have already en- gaged attention; the exhalation of a kind of albuminous, reddish, or whitish lymph into the interior of the lymphatic ganglions, and into the organs, called, by Chaussier, glandiform ganglions, and by Be- clard, sanguineous ganglions;—namely:—the thymus, thyroid, supra- renal capsules, and spleen. We know but little, however, of the fluids formed in these various parts. They have never been ana- lyzed, and their uses are inappreciable. By some physiologists, a fluid is supposed to be exhaled from the inner coat of the arterial, venous and lymphatic vessels. We are unaware, however, of the nature of this fluid. Its chief use is pre- sumed to be, to lubricate the interior of the vessel, and to prevent adhesion between it and the fluid circulating within it. 2. EXTERNAL EXHALATIONS. a. Cutaneous Exhalation or Transpiration. A transparent fluid is constantly exhaled from the skin, which is generally invisible, in consequence of its being converted into vapour as soon as it reaches the surface; but, at other times, owing to aug- mentation of the secretion, or to the air being loaded with humidity, it is apparent on the surface of the body. When invisible, it is called the insensible transpiration or perspiration; when perceptible, sweat. In the state of health, according to Thenard,0 this fluid reddens litmus paper; yet the taste is rather saline—resembling that of com- mon salt—than acid. Allusion has already been made to the views of M. Donne,d who considers, that the external acid, and the inter- nal alkaline membranes of the human body represent the two poles of a pile, the electrical effects of which are appreciable by the gal- vanometer. The smell of the perspiration is peculiar, and becomes almost in- supportable when concentrated, and especially when subjected to distillation. The fluid is composed, according to Thenard, of much water, a small quantity of acetic acid, chloride of sodium, and perhaps of potassium, a very little earthy phosphate, a trace of oxide of iron, and an inappreciable quantity of animal matter. Berzelius6 regards * See, on the subject of the Pigments, Burdach's Physiologie als Erfahrungswissen- schaft, v. 176, Leipz. 1835. b Physiologie de I'Homme, 2de edit torn. iii. 483, Paris, 1829. c Traite de Chimie, torn. iii. d Journal Hebdomad., Fevrier, 1834. e Medico-Chir. Trans, iii. 256, and Bostock, ibid. xiv. 424. EXHALATIONS-CUTANEOUS. 269 it as water, holding in solution the chlorides of potassium and sodium, lactic acid, lactate of soda, and a little animal matter; and Anselmino,* as consisting of a solution of osmazome, chlorides of sodium and calcium, acetic acid and an alkaline acetate, sali- vary matter, sulphates of soda and potassa, and calcareous salts, with mucus, albumen, sebaceous humour, and gelatine in variable proportions. Raspailb strangely regards the sweat as an acid pro- duct of the disorganization of the skin. In a memoir presented to the Academie Royale des Sciences, of Paris, MM. Breschet and Roussel de Vauzeme have endeavoured to show, that there exists in the skin an apparatus for the secretion of the sweat, consisting of a glandular parenchyma, which secretes the liquid, and of ducts, which pour it on the surface of the body. These ducts are said to be arranged spirally, and to open very obliquely under the scales of the epidermis. To this apparatus they apply the epithet "diapnogenous;" and to the ducts the epithet " sudoriferous or hidrophorus."c Numerous experiments have been instituted for the purpose of discovering the quantity of transpiration that takes place in a given time. Of these, the earliest were by Sanctorius,—for which he is more celebrated than for any other of his labours,—after whom the transpiration was called perspirabile sanctorianum.A For thirty years, this indefatigable experimentalist weighed daily, with the greatest care, his solid and liquid ingesta and egesta, and his own body, with the view of deducing the loss sustained by the cutaneous and pulmonary exhalations. He found, that every twenty-four hours, his body returned sensibly to the same weight, and that he lost the whole of the ingesta;—five-eighths by transpiration, and three-eighths by the ordinary excretions. For eight pounds of in- gesta, there were only three pounds of sensible egesta, which con- sisted of forty-four ounces of urine, and four of faeces. It is lamentable to reflect, that so much time was occupied in the attain- ment of such insignificant results. The self-devotion of Sanctorius gave occasion, however, to the institution of numerous experiments of the same kind; as well as to discover the variations in the exha- lation, according to age, climate, &c. The results of these have been collected by Haller,e but they afford little instruction; espe- cially as they were directed to the transpiration in general, without affording us any data to calculate the proportion exhaled from the lungs compared with that constantly taking place by the cutaneous surface. Rye/ who dwelt in Cork, lat. 51° 54', found, in the three winter months—December, January, and February, that the quantity * Physiologie Medicale et Philosophique, ii. 452, Paris, 1832. b Chimie Organique, p. 505, Paris, 1832. c Breschet, Nouvelles Recherches sur la Structure de la Peau, Paris, 1835; also, Plumbe, on Diseases of the Skin, p. 12, Lond. 1837. d Avs Sanctorii de Statica Medicina, cum Comment. Martini Lister. Lugd. Bat. 1711. e Elem. Physiol, xii. 2, 10. f Rogers, on Epidem. Diseases, Appendix, Dubl. 1734. 23* 270 SECRETION. Jrine. Perspiration. 42T777 53 40TO 60 37 63 37 50 of urine was 3937 ounces; of the perspiration, 4797: in the spring months—March, April, and May—the urine amounted to 3558; the perspiration to 5405; in the summer months—June, July, and August—the urine amounted to 3352; the perspiration to 5719; and in the three autumnal months—September, October, and No- vember—the quantity of urine was 3369; that of the perspiration 4471. The daily average estimate, in ounces, was as follows:— Winter, - Spring, ----- Summer, - Autumn, - thus making the average daily excretion of urine, throughout the year to be a little more than 39 ounces; and of the transpiration, 56 ounces. Keill,* on the other hand, makes the average daily perspiration, 31 ounces; and that of the urine 38; the weight of the faeces being 5 ounces, and that of the solid and liquid ingesta, 75 ounces. His experiments were made at Northampton, England, lat. 52° 11'. Bryan Robinsonb found, as the result of his observations in Ireland, that the ratio of the perspiration to the urine was, in summer, as 5 to 3; in winter, as 2 to 3; whilst in April, May, October, November, and December, they were nearly equal. In youth, the ratio of the perspiration to the urine, was as 1340 to 1000; in the aged, as 967 to 1000. Hartmann, when the solid and liquid ingesta amounted to 80 ounces, found the urine discharged 28 ounces; the faeces 6 or 7 ounces; and the perspirable matter, 45 or 46 ounces. De Gorter,0 in Holland, when the ingesta were 91 ounces, found the perspira- tion to amount to 49 ounces; the urine to 36; and the faeces to 8. Dodartd asserts, that in France, the ratio of the perspiration to the faeces, is as 7 to 1; and to the whole egesta as 15 to 12 or 10. The average perspiration in the twenty-four hours, he estimates at 33 ounces and 2 drachms; and Sauvages, in the south of France,found that when the ingesta were 60 ounces in the day, the transpiration amounted to 33 ounces; the urine to 22; and the faeces to 5. Most of these estimates were made in the cooler climates,—the " regiones borealesT—as Haller6 has, not very happily, termed them. According to Lining/ whose experiments were made in South Carolina, lat. 32° 47', the perspiration exceeded the urine in the warm months; but in the cold, the latter had the preponderance. The following table gives the average daily proportion of the urine and perspiration, for each month of the year, in ounces,—as quoted by Haller. a Tentamina Medico-Phys.—Appendix, Lond. 1718. b Dissertation on the Food and Discharges of Human Bodies, Dublin, 1748. c De Perspiratione Insensibili, Lugd. Bat. 1736. d Memoir, de 1'Acad. des Sciences, ii. 276. e Op. citat. { Philos. Transact for 1743 and 1745. EXHALATIONS—CUTAN EOUS. 271 Urine. Perspiration. December, . 70.81 42.55 January, . 72.43 39.97 February, . 77.86 37.45 March, . 70.59 43.23 April, . 59.17 47.72 May, . 56.15 58.11 June, . 52.90 71.39 July, . 43.77 86.41 August, . 55.41 70.91 September, . 40.60 77.09 October, . 47.67 40.78 November, - 63.16 40.97 After the period at which Haller wrote, no experiments of any moment were adopted for appreciating the transpiration. Whenever trials were instituted, the exhalation from both the skin and the lungs was included in the result, and no satisfactory means were adopted for separating them, until Lavoisier and Seguin* made their cele- brated experiments. Seguin inclosed himself in a bag of gummed taffeta, which was tied above the head, and had an aperture, the edges of which were fixed around the mouth by a mixture of turpen- tine and pitch. By means of this arrangement, the pulmonary tran- spiration alone escaped into the air. To estimate its quantity, it was merely necessary for M. Seguin to weigh himself in the sack, by a very delicate balance, at the commencement and termination of the experiment. By repeating the experiment out of the sack, he deter- mined the total quantity of the transpired fluid; so that, by deduct- ing from this the quantity of fluid exhaled from the lungs, he obtained the amount of the cutaneous transpiration. He, moreover, kept an account of the food, which he took; of the solid and liquid egesta; and, as far as he was able, of every circumstance that could influ- ence the transpiration. The results—as applicable to Paris—at which Lavoisier and Seguin arrived, by a series of well-devised and well-conducted experiments, were the following:— First. Whatever may be the quantity of food taken, or the varia- tions in the state of the atmosphere, the same individual, after having increased in weight by the whole quantity of nourishment taken, returns daily, after the lapse of twenty-four hours, to nearly the same weight as the day before;—provided he be in good health; his diges- tion perfect; that he is not fattening, or growing; and avoids all kinds of excess. Secondly. If, when all other circumstances are identical, the quantity of food varies; or if—the quantity of food being the same—the effects of transpiration differ'; the quantity of the excrements augments or diminishes, so that every day at the same hour, we return nearly to the same weight; proving, that when digestion goes on well, the causes, which concur in the loss or excre- tion of the food taken in, afford each other mutual assistance;—in the state of health one charging itself with what the other is unable a Memoir, de PAcademie des Sciences de Paris, Paris, 1777 & 1790. 272 SECRETION. to accomplish. Thirdly. Defective digestion is one of the most direct causes of the diminution of transpiration. Fourthly. When digestion goes on well, and the other causes are equal, the quantity of food has but little effect on the transpiration. Seguin affirms, that he has very frequently taken at dinner two pounds and a half of solid and liquid food; and, at other times, four pounds; yet the results, in the two cases, differed but little from each other; provided only, that the quantity of fluid did not vary materially in the two cases. Fifthly. Immediately after dinner, the transpiration is at its minimum. Sixthly. When all other circumstances are equal, the loss of weight, induced by insensible transpiration, is at its maximum during digestion. The increase of transpiration during digestion compared with the loss sustained when fasting, is, on an average, 2fV grains per minute. Seventhly. When circumstances are most favourable, the greatest loss of weight, caused by insensible transpi- ration, was, according to their observations, 32 grains per minute; consequently 3 ounces, 2 drachms and 48 grains, poids de marc, per hour; and 5 pounds in twenty-four hours; under the calculation, that the loss is alike at all hours of the day, which is not, however, the fact. Eighthly. When all the accessory circumstances are least favourable, provided only that digestion is properly accomplished, the smallest loss of weight is 11 grains per minute;1 consequently, 1 ounce, 1 drachm and 12 grains per hour; and 1 pound, 11 ounces and 4 drachms in the twenty-four hours. Ninthly. Immediately after eating, the loss of weight, caused by the insensible perspiration, is 10j grains per minute, during the time at which all the extraneous causes are most unfavourable to transpiration; and 19^grains per minute, when these causes are most favourable and the internal causes are alike. " These differences," says M. Seguin, " in the transpiration after a meal, according as the causes, influencing it, are more or less favourable, are not in the same ratio with the dif- ferences, observed at any other time when the other circumstances are equal; but we know not how to account for the phenomenon." Tenthly. The cutaneous transpiration is immediately dependent both on the solvent virtue of the circumambient air, and on the power possessed by the exhalants of conveying the perspirable fluid as far as the surface of the skin. Eleventhly. From the average of all the experiments it seems, that the loss of weight caused by the insensi- ble transpiration is 18 grains per minute; and that, of these 18 grains, 11, on the average, belong to the cutaneous transpiration, and 7 to the pulmonary. Twelfthly. The pulmonary transpiration, compared with the volume of the lungs, is much more considerable than the cutaneous, compared with the surface of the skin. Thirteenthly. When every other circumstance is equal, the pulmonary transpira- tion is nearly the same before and immediately after a meal; and if, on an average, the pulmonary transpiration be \1\ grains per minute before dinner, it is 17T7o grains after dinner. Lastly. Every other intrinsic circumstance being equal, the weight of the solid excrements is least during winter. EXHALATIONS—CUTANEOUS. 273 Although these results are probably fairly deduced from the experiments; and the experiments themselves were almost as well conceived as the subject admits of, we cannot regard the estimates as more than approximations. Independently of the fact, that the envelope of taffeta must necessarily have retarded the exhalation by shutting off the air, and caused more to pass off by pulmonary transpiration ; the perspiration must incessantly vary according to circumstances within and without the system; some individuals, too, perspire more readily than others: and this is dependent, as we have seen, upon climate and season,—and likewise upon the quan- tity of fluid received into the digestive organs. From all these and other causes, Bichat is led to observe, that the endeavour to deter- mine the quantity of the cutaneous transpiration is as vain as to endeavour to specify what quantity of water is evaporated every hour, by a fire, the intensity of which is varying every instant. To attempt, however, the solution of the problem, experiments were likewise undertaken by Cruikshank,* and by Abernethy. Their plan consisted in confining the hand, for an hour, in an air-tight glass jar, and collecting the transpired moisture. Mr. Abernethy, having weighed the fluid collected in the glass, multiplied its quantity by 38^, the number of times, he conceived the surface of the hand and wrist to be contained in the whole cutaneous surface. This gave 2^ pounds, as the quantity exhaled from the skin in the twenty- four hours, upon the supposition, that the whole surface perspires to an equal extent. These experiments have been repeated by Dr. William Wood,b of Newport, England, with some modifications. He pasted around the mouth of a jar one extremity of a bladder, the ends of which were cut away, and the hand being passed through the bladder into the jar, the other extremity was bound to the wrist with a ligature, not so tight, however, as to interfere, in any degree, with the circulation. The exact weight of the jar and bladder had previously been ascertained. During the experiment, cold water was applied to the outer surface of the jar, to cause the deposition of the fluid accumulated within. The result of his expe- riments was as follows: Exp. Time of day. Temperature in ap-trtment. Pulse per minute. Fli aid collected ia an hour. 1. 2. 3. 4. 5. 6. Noon. -Do. -Do. -Do. -9 P.M.. Do. - - 663 -. -- 66 -- 66 -- 61 -- 62 -- 62 - - 84 -- 78 -- 78 -- 84 -- 80 -- 75 - - 32 grs. 32 26 32 26 23 Mean. 63.8 79.8 28.5 The next thing was to estimate the proportion, which the surface of the hand and wrist bears to the whole surface of the body. * Experiments on the Insensible Perspiration, p. 5, Lond. 1795. b An Essay on the Structure and Functions of the Skin, &c., Edinb. 1832. 274 SECRETION. Abernethy reckoned it as 1 to 38|, whilst Cruikshank computed it as 1 to 60 ! Dr. Wood does nof adopt the estimate of either. He thinks, however, that the estimate of the former as regards the surface of the hand and wrist, which he makes seventy square inches, is near the truth, having found it to correspond both with his own measurements, and the reports of the glovers. Mr. Abernethy's estimate of the superficial area of the whole body—2700 square inches, or above eighteen square feet, he properly regards as too high. Perhaps the most general opinion is, that it amounts to sixteen square feet, or 2304 square inches; but Haller did not think it exceeded thirteen square feet or 2160 square inches. Dr. Wood adopts the former of these, and is disposed to think, that the pro- portion of the surface of the hand and fingers, taken to the extremity of the bone of the arm, does not fall short of 1 to 2, which if we adopt the ratio of the quantity, that he found transpired per hour, gives, for the whole body, about forty-five ounces, or nearly four pounds troy in the twenty-four hours. This is considerably above the result of the experiments of either Seguin, or Abernethy; yet, on reviewing the experiments, Dr. Wood is not disposed to think it far from the truth. Upwards of fifty years ago, Dr. Dalton, of Manchester, under- took a series of experiments similar to those of Sanctorius, Keill, Hartmann and Dodart.* The first series of experiments he made upon himself, in the month of March, for fourteen days in succes- sion. The aggregate of the articles of food consumed in this time was as follows,—bread, 163 ounces avoirdupois; oaten cake, 79 ounces; oatmeal, 12 ounces; butcher's meat, 54^ ounces; potatoes, 130 ounces; pastry, 55 ounces; cheese, 32 ounces;—Total of solid food, 525^ ounces; averaging 38 ounces daily:—of milk, 435^ ounces; beer, 230 ounces; tea, 76 ounces ;—Total, 741£, averaging 53 ounces of fluid daily. The daily consumption was, consequently, 91 ounces; or nearly six pounds. During the same period, the total quantity of urine passed was 680 ounces; and of faeces, 68 ounces;—the daily average being,—of urine, 48£ ounces; of freces, 5 ounces; making 53^. If we subtract these egesta from the in- gesta, there will remain 37^ ounces, which must have been exhaled by the cutaneous and'pulmonary transpirations, on the supposition that the weight of the body remained stationary. To test the influence of difference of seasons, Dr. Dalton resumed his investigations, in the month of June of the same year. The re- sults were as might have been anticipated,—a less consumption of solids and a greater of fluids; a diminution in the evacuations and an increase in the insensible perspiration. The average of solids, consumed per day, was 34 ounces; of fluids, 56 ounces;—total, 90 ounces; the daily average of the evacuations,—urine, 42 ounces; faeces, 4^,—leaving a balance of nearly 44 ounces, for the daily loss by perspiration, or one-sixth more than during the cooler season, * Manchester Memoirs, vol, v, EXHALATIONS—CUTANEOUS. 275 He next varied the process, with the view of obtaining the quan- tity of perspiration, and the circumstances attendant upon it more directly. He procured a weighing beam, that would turn with one ounce. Dividing the day into periods of four hours in the forenoon, four or five hours in the afternoon, and nine hours in the night—or from ten o'clock at night to seven in the morning, he endeavoured to find the perspiration corresponding to these periods respectively. He weighed himself directly after breakfast, and again before dinner, observing neither to take nor part with any thing in the interval, except what was lost by perspiration. The difference in weight indicated such less. The same course was followed in the after- noon and in the night. This train of experiments was continued for three weeks in November. The mean hourly losses by transpi- ration were;—in the morning, 1.8 ounce avoirdupois;—afternoon, 1.67 ounce;—night, 1.5 ounce. During twelve days of this period, he kept an account of urine corresponding in time with perspira- tion. The ratio was as 46 to 33. From the whole of his investigation of this subject, Dr. Dalton concludes;—that of six pounds of aliment taken in the day, there appears to be nearly one pound of carbon and azote together, the remaining five pounds are chiefly water, which seems necessary as a vehicle to introduce the other two elements into the circula- tion, and also to supply the lungs and membranes with moisture; that very nearly the whole quantity of food enters the circulation, for the fasces constitute only J?th part, and of these a part—bile— must have been secreted; that one great portion is thrown off by the kidneys,—namely, about half of the whole weight taken, but probably more or less according to climate, season, &c.; that ano- ther great portion is thrown off by means of insensible perspiration, which may be subdivided into two portions, one of which passes off by the skin—amounting to one-sixth part, and the other five-sixths are discharged from the lungs in the form of carbonic acid, and of water or aqueous vapour. Since the time of Lavoisier and Seguin, Dr. Edwards* has made some experiments, for the purpose of illustrating the effect produced upon cutaneous transpiration by various circumstances to which the body is subjected. His first trials were made on cold-blooded animals, in which the cutaneous transpiration can be readily sepa- rated from the pulmonary, owing to the length of time, that they are capable of living without respiring. All that is necessary is to weigh the animal before and after the experiment, and to make allowance for the ingesta and egesta. In this way he discovered, that the body loses successively less and less in equal portions of time; that the transpiration proceeds more rapidly in dry than in moist air; in the extreme states nearly in the proportion of 10 to 1; that temperature has, also, considerable influence,—.the transpira- * Sur lTnfluence des Agens Physiques, Paris, 1822, and Hodgkin and Fisher's trans- lation, Lond. 1832; see, also, an analytical review, by the author of this work, in the Amer. Journ. of the Med. Sciences, for May, 1834. 276 SECRETION. tion, at 68° of Fahrenheit, being twice as much; and, at 104°, seven times as much as at 32°. He likewise found, that frogs transpire, whilst they are in water, as is shown by the diminution which they experience while immersed in that fluid, and by the appearance of the water itself, which becomes perceptibly impregnated by the matter excreted by the skin. In warm-blooded animals, he found, as in the cold-blooded, the transpiration become less and less in proportion to the quantity of fluid evaporated from the body; and he observed the same difference between the effects of moist and dry air, and between a high and a low temperature. The effects of these agents were essentially the same on man as on animals. He found, that the transpiration was more copious during the early than the latter part of the day; that it is greater after taking food; and, on the whole, appeared to be increased during sleep.* Whenever the fluid, which constitutes the insensible transpiration, does not evaporate, owing to the causes referred to at the com- mencement of this article, it appears on the surface in the form of sensible perspiration or sweat. It has been supposed by some phy- siologists, that the insensible and sensible perspirations are two dis- tinct functions. Such appears to be the opinion of, Haller, and of Edwards, who regards the former as a physical evaporation,—the latter as a vital transudation or secretion,b but no sufficient reason seems to exist, why we should not regard them as different degrees of the same function. It is, indeed, affirmed, that the sweat is generally less charged with carbonic acid than the vapour of trans- piration ; and that it is richer in salts, which are deposited on the skin, and are sometimes seen in the form of white flocculi; but our knowledge on this matter is vague. Particular parts of the body perspire more freely, and sweat more readily than others. The forehead, armpits, groins, hands, feet, &c. exhibit evidences of this most frequently; some of these, perhaps, owing to the fluid, when exhaled, not evaporating readily,—the con- tact of air being impeded. It is presumed, likewise, that the sweat has not every where the same composition. Its odour certainly varies in different parts of the body. In the armpits and feet it is more acid: in the violent sweats, accompanying acute rheumatism, this acidity always attracts attention; and in the groins, its odour is strong and rank. It differs, too, greatly in individuals, and especially in the races. In the red-haired, it is said to be unusually strong; and in the negro, during the heat of summer, it is alliaceous and overwhelming. By cleanliness, the red-haired can obviate the un- pleasant effect, in a great measure, by preventing undue accumula- tion in the axilla, groins, &c; but no ablution can remove the odour * For various estimates, relative to the quantity of the cutaneous transpiration, see Burdach's Physiologie als Erfahrungswissenschaft, v. 196, Leipz. 1835. b Edwards, Sur PInfluence des Agens Physiques, &c.; Drs. Hodgkin and Fisher's translation, Lond. 1832; also, the author's Elements of Hygiene, p. 63, Philad. 1835; and his General Therapeutics, p. 278, Philad. 1836. EXH A LATIONS—CUTANEOUS. 277 of the negro, although cleanliness can detract from its intensity. Each race appears to have its characteristic scent.; and, according to Humboldt, the Peruvian Indian, whose smell is highly developed by education, can distinguish the European, the American Indian, and the negro, in the middle of the night, by this sense alone. Some physiologists have doubted, whether this odorous matter of the skin belongs properly to the perspiration, and have presumed it to be the product of specific organs. This is, however, conjectural; and the experiments of Thenard, as well as the facts we have just mentioned, would rather seem to show, that the matter of sweat itself has, within it, the peculiar odour. The fact of the dog tracing its master to an immense distance, and discovering him in a crowd, has induced a belief, that the scent may be distinct from the matter of sweat; but the supposition is not necessary, if we admit the matter of perspiration to be itself odorous. Besides the causes before referred to, the quantity of perspiration is greatly augmented by running or by violent exertion of any kind; especially if the temperature of the air be elevated. Warm fluids favour it greatly, and hence their use, alone or combined with sudo- rifics, where this class of medicines is indicated. Magendie* con- ceives, that being readily absorbed, they are also readily exhaled. This may be true; but the perspiration breaks out too rapidly to admit of this explanation. When ice-cold drinks are taken in hot weather, the cutaneous transpiration is instantaneously excited. The effect, consequently, must be produced by the refrigerant influence of the cold medium on the lining membrane of the stomach,—this influence, being propagated, by sympathy, to every part of the capil- lary system. The same explanation is applicable to warm drinks, whilst the hot exert a sympathetic effect on the skin by virtue of their stimulant properties exerted on the mucous membrane. With regard to the uses of the insensible transpiration, it has been supposed to preserve the surface supple, and thus to favour the exercise of touch; and also, by undergoing evaporation, to aid in the refrigeration of the body. It is probable, however, that these are quite secondary uses under ordinary circumstances, and that the great office, performed by it, is to remove a certain quantity of fluid from the blood: hence it has been properly termed the cutaneous depuration. In this respect, it bears a striking analogy to the urine, which is the only other depuratory secretion, with the exception of the pulmonary transpiration, which we shall find essentially resembles the cutaneous. Being depuratory, it has been conceived, that any interruption to the transpiration must be attended with the most serious conse- quences ; accordingly most diseases have, from time to time, been ascribed to this cause. There is, however, so great a compensation existing between the urinary and cutaneous depurations, that if one be augmented, the other is decreased,—and conversely. Besides, it * Precis de Physiologie, 2de edit. ii. 455. vol. ii. 24 278 SECRETION. is well known that disease is more apt to be induced by partial and irregular application of cold than by frigorific influences of a more general character. The Russian vapour-bath exemplifies this; the bather frequently passing with impunity from a temperature of 130° into cold water. The morbific effect—in these cases of fancied check given to perspiration—is derangement of the capillary vessels engaged in the important functions of nutrition, calorification, and secretion, and the extension of this derangement to every part of the system.* As the sensible transpiration or sweat is probably only the insen- sible perspiration in increased quantity, with the addition of salts, and other matters that are not evaporable, its uses demand no spe- cial notice. b. Pulmonary Transpiration. The pulmonary transpiration, to which we have so often alluded, bears a striking analogy to the cutaneous. Sir B. Brodie and Ma- gendie, from the examination of cases of fistulous opening into the trachea, deny that it comes from the lungs, believing it to be formed by the moist mucous lining of the nose, throat, &c.; but this view has been disproved by Paoli and Regnoli, in the case of a young female, whose trachea had been opened, and in whom, at the tem- perature of 39° Fahr., watery vapour was distinctly expired through the canula. Mojonb strangely supposes the vapour of the breath to be a watery fluid secreted by the thyroid gland, and suspended in the respired air, from its volatility, caused by the presence of caloric. At one time, it was universally believed to be owing to the com- bustion of the air, with the hydrogen and carbon given off from the lungs;0 but we have elsewhere shown, that no such combustion occurs; and, besides, the exhalation takes place, when gases, con- taining no oxygen, have been respired by animals. It is now almost universally admitted to be exhaled into the air-cells of the lungs from the pulmonary artery chiefly, but partly from the bronchial arteries, distributed to the mucous membrane of the air-passages. Much of the vapour, Dr. Prout conceives, is derived from the chyle in its passage through the lungs ; and thus, he thinks, the weak and delicate albumen of the chyle is converted into the strong and per- fect albumen of the blood. Several interesting experiments have been made on this exhala- tion, by Magendie, Milne Edwards, Breschet, and others. If water be injected into the pulmonary artery, it passes into the air-cells," in myriads of almost imperceptible drops, and mixes with the air con- tained in them. Magendied found, that its quantity might be aug- a This subject has been expatiated upon in another work, by the author, on General Therapeutics, Philad. 1836. See, also, his Elements of Hygiene, p. 69, Philad. 1835. b Leggi Fisiologiche, &c. translated by Skene, p. 76, Lond. 1827. c Bostock's Physiology, 3d edit. p. 359. «• Precis, &c. ii. 346. EXHALATIONS-PULMONARY. 279 mented at pleasure on living animals, by injecting distilled water, at a temperature approaching that of the body, into the venous system. He injected into the veins of a small dog a considerable amount of water. The animal was at first in a state of real plethora, the ves- sels being so much distended that it could scarcely move ; but, in a few minutes, the respiration became manifestly hurried, and a large quantity of fluid was discharged from the mouth, the source of which appeared evidently to be in the pulmonary transpiration considera- bly augmented. Not only, however, is the aqueous portion of the blood exhaled in this manner; but experiment shows, that many substances, intro- duced into the veins by absorption, or by direct injection, issue by the lungs. Weak alcohol, a solution of camphor, ether and other odorous substances, when thrown into the cavity of the peritoneum or elsewhere, were found, by Magendie, to be speedily absorbed by the veins, and conveyed to the lungs, where they transuded into the bronchial cells, and were recognised by the smell in the expired air. Phosphorus, when injected, exhibited this transmission in a singular and evident manner. Magendie,* on the suggestion of M. Armand de Montgarny, " a young physician," he remarks, "of much merit," now no more, injected into the crural vein of a dog, half an ounce of oil, in which phosphorus had been dissolved; scarcely had he finished the injection, before the animal sent through the nostrils clouds of a thick, white vapour, which was phosphoric acid. When the experiment was made in the dark, these clouds were luminous. M. Tiedemann1 injected a drachm of the expressed juice of garlic into a vein in the thigh of a middle-sized dog: in the space of three seconds the breath smelt strongly of garlic. When spirit of wine was injected, the exhaled vapour was recognised when the injection was scarcely over. MM; Breschet and Milne Edwards0 have made several experi- ments, for the purpose of discovering, why the pulmonary transpi- ration expels so promptly the different gases and liquid substances received into the blood. Considering properly, that exhalation dif- fers only from absorption in taking place in an inverse direction, these gentlemen conjectured, that it ought to be accelerated by every force, that would attract the fluids from within to without; and such a force they conceive inspiration to be, which, in their view, solicits the fluids of the economy to the lungs, in the same mechanical manner as it occasions the entrance of air into the air- cells. In support of this view, they adduce the following experi- ments. To the trachea of a dog, a pipe, communicating with a bellows, was adapted, and the thorax was largely opened. Natural respira- tion was immediately suspended; but artificial respiration was kept * Precis, &c. ii. 348. b Tiedemann and Treviranus, Zeitschrift for Physiologie, vol. v. part n.; and British and Foreign Medical Review, i. 241, Lond. 1836. c Recherches Experimentales sur PExhalation Pulmonaire, Paris, 1826. 280 SECRETION. up by means of the bellows. The surface of the air-cells was, in this way, constantly subjected to the same pressure; there being no longer diminished pressure during inspiration, as when the thorax is sound, and the animal breathing naturally. Six grains of cam- phorated spirit were now injected into the peritoneum of the animal; and, at the same time, a similar quantity was injected into another dog, whose respiration was natural. In the course of from three to six minutes, the odorous substance was detected in the pulmonary transpiration of the latter; but in the other it was never manifested. In the first animal, they now exposed a part of the muscles of the abdomen, and applied a cupping-glass to it; when the smell of the camphor speedily appeared at the cupped surface. Their conclu- sion was, that the pulmonary surface, having ceased to be subjected to the suction force of the chest, during inspiration, the exhalation was arrested, whilst that of the skin was developed as soon as an action of aspiration was exerted upon it by the cupping-glass. Into the crural veins of two dogs;—one of which breathed na- turally, and the other was circumstanced as in the last experiment, —they injected the essential oil of turpentine. In the first of these, the substance was soon apparent in the pulmonary transpiration; and, on opening the body, it was discovered, that the turpentine had impregnated the lung and the pleura much more strongly than the other tissues. In the other animal, on the contrary, the odour of the turpentine was scarcely apparent in the vapour of the lungs ; and, on dissection, it was not found in greater quantity in the lungs than in the other tissues;—in the pleura than in the peritoneum. From the results of these experiments, MM. Breschet and Edwards conclude, that each inspiratory movement constitutes a kind of suc- tion, which attracts the blood to the lungs; and which causes the ejection, through the pulmonary surface, of the liquid and gaseous substances that are mingled with that fluid, more than through the other exhalant surfaces of the body. In their experiments, these gentlemen did not find that the exhalation was effected with equal readiness in every part of the surface, when the cupping-glass was applied in the manner that has been mentioned. The skin of the thigh, for example, did not indicate the odour of camphorated alco- hol, as that of the region of the stomach. The chemical composition of the pulmonary transpiration is pro- bably nearly identical with that of the sweat; appearing to consist of water, holding in solution, perhaps, some saline and albuminous matter; but our information, on this matter, derived from the che- mist, is not precise. Collard de MartignyV experiments make it consist, in 1000 parts,—of water 907, carbonic acid 90; animal matter—the nature of which he was unable to determine—3 parts. Chaussier found, that by keeping a portion of it in a close vessel, exposed to an elevated temperature, a very evident putrid odour was exhaled on opening the vessel. This could only have arisen from the existence of animal matter in it. » Magendie's Journal de Physiologie, x. 111. EXHALATIONS—PULMONA RY. 281 The pulmonary transpiration being liable to all the modifications which affect the cutaneous, it is not surprising, that we should meet with so much discordance in the estimates of different individuals, regarding its quantity in a given time. Hales* valued it at 20 ounces in the twenty-four hours; Sanctorius,b Menzies,0 and Dr. William Wood,d at 6 ounces; Abernethy6 at 9 ounces; Lavoisier and Seguinf at 171 ounces, poids de marc; Thomson^ at 19 ounces, and Dalton at from 1 pound 8f ounces,h to 20^ ounces avoirdupois.' The uses it serves, in the animal economy, are identical with those of the cutaneous depuration. It is essentially depuratory. Experi- ments, some of which have been detailed, have sufficiently shown, that volatile substances introduced, in any way, into the circulatory system are rapidly exhaled into the bronchial tubes—if not adapted for the formation of arterial blood. Independently, therefore, of the lungs being the great organ of respiration, they play a most impor- tant part in the economy, by throwing off those substances, that might be injurious, if retained. c. Exhalation of the Mucous Membranes. The mucous membranes, like the skin, which they so strongly resemble in their structure, functions, and diseases, exhale a similar transpiratory fluid; which has not, however, been subjected to che- mical examination. It is, indeed, almost impracticable to separate it from the follicular secretions, poured out from the same membrane; and from the extraneous substances, almost always in contact with it. It is probably, however, similar to the fluid of the cutaneous and pulmonary depurations, both in character and use. FOLLICULAR SECRETIONS. The follicular secretions must, of necessity, be effected from the skin or the mucous membranes; as the follicles or crypts are met with there only. They may, therefore, be divided into two classes; —1st, the mucous follicular secretion ; and 2d, the cutaneous follicu- lar secretion. a. Mucous Follicular Secretion. The whole extent of the great mucous membranes,—lining the alimentary canal, the air-passages, and the urinary and genital organs,—is the seat of a secretion, the product of which has received, in the abstract, the name of^mucus; although it differs somewhat » Statical Essays, ii. 322, Lond. 1767. b Medicina Statica, Aphor. v. c Dissertation on Respiration, p. 54, Edinb. 1796. d Essay on the Structure, &c, of the Skin, Edinb. 1832. e Surgical and Physiol. Essays, p. 141, Lond. 1793. f Mem de la Societe Royale de Medecine, pour 1782-3; Annal. de Chimie, v. 264; and Mem. de 1'Acad. des Sciences, pour 1789. s System of Chemistry, vol. iv. h Manchester Memoirs, 2d series, ii. 29. ' Ibid. vol. v. 24* 282 SECRETION. according to the situation and character of the particular follicles, whence it proceeds. Still, essentially, the structure, functions, and product are the same. According to M. Donne,* its character is alkaline in health; in disease often acid. In the history of the dif- ferent functions, in which some of the mucous membranes are con- cerned, the uses of this secretion have been detailed; and in those that will hereafter have to engage attention, in which other mucous membranes are concerned, their uses will fall more conveniently under notice then. But few points, will, therefore, require explana- tion at present. The mucus, secreted by the nasal follicles, seems alone to have been subjected to chemical analysis. Fourcroy and Vauquelinb found it composed of precisely the same ingredients as the tears. Accord- ing to the analysis of Berzelius,0 its contents are as follows:—water, 933.7; mucus, 53.3; chlorides of potassium and sodium, 5.6; lactate of soda, with animal matter, 3.0; soda, 0.9; albumen and animal matter, soluble in water, but insoluble in alcohol, with a trace of phosphate of soda, 3.5. According to Raspail,d mucus is the mere product of the healthy and daily disorganization, or wear and tear of the mucous membranes. Every mucous membrane, he affirms, exfoliates in organized layers, and is thrown off, more or less, in this form ; whilst the serous membranes either do not exfoliate, or their exfoliation (excoriation) is resolved into the liquid form, to be again absorbed by the organs; but this—like many other of M. Raspail's speculations—is a generalization which does not appear to be war- ranted by the facts; the slightest examination, indeed, exhibits, that the general physical character of the mucus is very different from that of the membranes which form it: still, mucus, when examined by a microscope of high magnifying powers—and this the author had an opportunity of doing through the hydroxygen microscope— does present, here and there, appearances of shreds similar to those described "by Raspail. The great use of mucus, wherever met with, is to lubricate the surface on which it is poured.6 b. Follicular Secretion of the Skin. This is the sebaceous and micaceous humour, observed in the skin of the cranium, and in that of the pavilion of the ear. It is also the humour, which occasionally gives the appearance of small worms beneath the skin of the face, when it is forced through the external aperture of the follicle; and which, when exposed to the air, causes the black spots sometimes observable on the face. The cerumen is, likewise, a follicular secretion, as well as the whitish, odorous and fatty matter which forms under the prepuce of the a Journal Hebdomad. Fevrier, 1834. '•> Journal de Physique, xxxix. 359. c Med. Chirurg. Transactions, torn. iii. d Chimie Organique, p. 246, and p. 504, Paris, 1832. e Burdach's Physiologie als Erfahrungswissenschaft, v. 235, Leipz. 1835. GLANDULAR—OF THE SALIVA. 283 male, and in the external parts of the female, where cleanliness is disregarded. The humour of Meibomius is also follicular, as well as that of the caruocula lachrymalis. The use of this secretion is,—to favour the functions of the part over which it is distributed. That, which is secreted from the skin, is spread over the epidermis, hair, &c. giving suppleness and elasti- city to the parts, rendering the surface smooth and polished, and thus obviating the evils of abrasion that might otherwise arise. It is also conceived that its unctuous nature may render the parts less permeable to humidity.* GLANDULAR SECRETIONS. The glandular secretions are seven in number; those of the tears, saliva, pancreatic juice, bile, urine, sperm, and milk. a. Secretion of the Tears. The lachrymal apparatus, being a part of that accessory to vision, was described under another head, (vol. i. p. 212.) As we meet with the tears, they are not simply the secretion of the lachrymal gland, but of the conjunctiva, and occasionally of the caruncula lachrymalis and follicles of Meibomius. They have a saline taste; mix freely with water; and, owing to the presence of free soda, communicate a green tint to the blue infusion of violets. Their chief salts are the muriate and phosphate of soda. Accord- ing to Fourcroy and Vauquelin,b the animal matter of the tears is mucus; but it is presumed, by some, to be 'albumen or an analogous principle. This secretion is more influenced by the emotions than any other; and hence it is concerned in the expressions of lively joy or sorrow, especially of the latter. b. Secretion of the Saliva. The salivary apparatus has likewise engaged attention elsewhere. It consists of a parotid gland on each side, situate in front of the ear, and behind the neck and ramus of the jaw; a submaxillary, beneath the body of the bone; and a sublingual, situate immediately beneath the tongue;—the parotids and submaxillary glands having each but one excretory duct;—the sublingual several. All these ducts pour the fluid of their respective glands into the mouth, where it collects, and becomes mixed with the exhalation of the mucous membrane of the mouth, and the secretion from its follicles. It is this mixed fluid that has been generally analyzed by the chemist. When collected, without the action of sucking, it is translucent, slightly opaque, very frothy, and ultimately deposits a nebulous a Burdach, op. cit. vi. 245. b Journal de Physique, xxxix. 256. 284 SECRETION. sediment. It usually contains free alkali; in rare cases, during meals, Professor Schultz,* of Berlin, found it acid; and, during fast- ing, it is occasionally neutral. Mitscherlich,b indeed, affirms that it is acid whilst fasting, but becomes alkaline during eating,—the alkaline character disappearing at times with the first mouthful of food. The average amount of the secretion in the twenty-four hours does not probably exceed four ounces.0 According to Berzelius/ its constituents are—water, 992.2; pe- culiar animal matter, 2.9; mucus, 1.4; chlorides of potassium and sodium, 1.7; lactate of soda, and animal matter, 0.9 ; soda, 0.2. Drs. Bostock6 and Thomas Thomsonf think, that the " mucus" of Berzelius resembles coagulated albumen in its properties. In the tartar of the teeth, which seems to be a sediment from the saliva, Berzelius found 79 parts of earthy phosphate; 12.5 of undecomposed mucus; 1 part of a matter peculiar to the saliva, and 7.8 of an animal matter solu- ble in muriatic acid. This animal matter, according to the micro- scopic experiments of Raspail,8 is composed of the deciduous frag- ments from the mucous membrane of the cavity of the mouth ; and he considers that the saliva is nothing more than an albuminous solution, mixed with different salts, which are capable of more or less modifying its solubility in water, and of shreds or layers of tissue. MM. Leuret and Lassaigneh analyzed pure saliva, obtained from an individual labouring under salivary fistula, and found it to con- tain,—water, mucus, traces of albumen, soda, chloride of potassium, chloride of sodium, carbonate and phosphate of lime;—and Messrs. Tiedemann and Gmelin1 affirm,—and their analysis agrees pretty closely with that of Van SettenJ'—that the saliva contains only one or two-hundredths of solid matter, which are composed of a pecu- liar substance, called salivary matter or ptyaline, osmazome, mucus, perhaps albumen, a little fat containing phosphorus, and the inso- luble salts—phosphate and carbonate of lime. Besides these, they detected the following soluble salts;—acetate, carbonate, phosphate, sulphate, muriate, and sulpho-cyanate of potassa.k Treviranus1 thinks the saliva contains a peculiar acid, to which he gives the name Blausaure, properly combined with an alkali; but its chemical properties resemble the sulpho-cyanic acid so greatly, that * Hecker's Wissenschaftliche Annalen, B. ii. H. 1. § 32, 1835. b Rullier and Raige Delorme, in art. Digestion, Diet, de Medecine, 2de edit. x. 300, Paris, 1835. c Mitscherlich, Rust's Magazine, Bd. xxxvi. S. 491. d Medico-Chirurgical Transactions, iii. 242. e Physiol, ed. cit. p. 487. f System of Chemistry, vol. iv. s Nouveau Systeme de Chimie Organique, p. 454. h Recherches, &c., sur la Digestion, p. 33, Paris, 1826. ' Recherches, &c, sur la Digestion, par Jourdan, Paris, 1827. i De Saliva ejusque Vi et Utilitate, Groning. 1837 ; and Brit, and For. Med. Review, Jan. 1839, p. 236. k Magendie's Precis Elementaire, ii. 63; and Burdach's Physiologie, u. s. w., v. 251, Leipz. 1835. 1 Biologie, Band iv. § 330. GLANDULAR—OF THE PANCREATIC JUICE. 285 according to Kastner* they may be taken for each other. Messrs. Tiedemann and Gmelin, and M. Donne,b found the saliva invariably alkaline, when the functions of the stomach were well performed. The latter gentleman considered acidity of the stomach a diagnostic symptom of gastritis; and Dr. Robt. Thomson0 found the acid re- action in all cases of inflammation of the mucous and serous mem- branes. With the view of testing these experiments, Mr. Laycockd instituted numerous experiments, and affords the tabular results of no less than 567 observations. His deductions do not accord with those of M. Donne. They are as follows:—1. The saliva may be acid without any apparent disease of the stomach, and when the individual is in good health. 2. It is alkaline during different degrees of gastric derangement, as indicated by the tongue. 3. It may be alkaline, acid and neutral, when the gastric phenomena are the same; and, consequently, acidity of the saliva is not a diagnostic mark of gastric derangement; and, lastly—in general it is alkaline in the morning, and acid in the evening. As the salivary secretion forms an important part in the processes preparatory to the stomachal digestion, its uses have been detailed in the first volume of this work. c. Secretion of the Pancreatic Juice. The pancreas or sweetbread, (Fig. 138, G.,) secretes a juice or humour, called succus pancreaticus or pancreatic juice. Its texture resembles that of the salivary glands ; and hence it has been called by some the abdominal salivary gland. It is situate transversely in the abdomen, behind the stomach, towards the concavity of the duodenum; is about six inches in length, and between three and four ounces in weight. From the results of six examinations, Dr. Gross6 gives the following as the mean weight and dimensions. Weight, 2\ ounces; length, 7 inches; breadth at the body and splenic extremity, 16^ lines; breadth at the neck, 12 lines; at the head, 2 inches and 3 lines; thickness at the body, neck, and splenic extremity, 4 lines; thickness at the head, 8 lines. Becourt found the average length of thirty-two to be 8 inches; and the weight between 3 and 4 ounces/ It is of a reddish-white colour, and firm consistence. Its excretory ducts terminate in one,—called the duct of Wirsung,—which opens into the duodenum, at times separately from the ductus communis choledochus, but close to it; at other times, being confounded with, or opening into it.s * Ficinus, in art. Speichel, in Pierer's Anat. Physiol. Real Worterbuch, vii. 634, Altenb. 1827. b Archives Generales, Mai and Juin, 1835. c Records of General Science, Dec. 1836. a Lond. Med. Gazette, Oct. 7, 1837. e Elements of Pathological Anatomy, ii.'357, Boston, 1839. f Recherches sur le Pancreas, ses Fonctions et ses Alterations Organiques, These, Strasbourg, 1830, cited by Mondiere, Archives Generales de Medecine, Mai, 1836. b Precis Elementaire, i. 462; J. P. Mondiere, op. cit. 286 SECRETION. The quantity of fluid, secreted by the pancreas, does not seem to be considerable. Magen- die, in his experiments, was struck with the small quan- tity discharged. Frequently, scarcely a drop issued in half an hour; and, occasionally, a much longer time elapsed. Nor did he find that the flow, according to the common opinion and to probability, was more rapid whilst diges- tion was going on. It will be readily understood, therefore, that it cannot be an easy task to collect it. De Graaf,* a Biliary and Pancreatic Ducts. Dutch anatomist, affirms, that a. The hepatic duct, formed by a branch from the u o,]rf.Pp,Jpd Uv intrndnrino- right, and one from the left lobe of the liver, b. Fundus ufc; SUCCCeaea, Dy lnirOOUCing of gall-bladder, c d. Body and neck of gallbladder. int0 the intestinal end of the e. Cystic duct. /. Ductus communis choledochus. g, g. . ,, Trunk and branches of the pancreatic duct. h. Ter- excretory dUCt, 8. Small quill, mination of the ductus communis choledochus and the . • .*• • i • 1 zl j ductus pancreaticus. i. The duodenum. terminating in a phial fixed under the belly of the animal. Magendie,b however, states, that he tried this plan several times, but without success ; and he believes it to be impracticable. The plan he adopts is to expose the intestinal orifice of the duct; to wipe, with a fine cloth, the surrounding mucous membrane; and as soon as a drop of the fluid oozes, to suck it up by means of a pipette or small glass tube. In this way, he collected a few drops, but never sufficient to undertake a satisfactory analysis. Messrs. Tiedemann and Gmelinc make an incision into the abdomen; draw out the duodenum, and a part of the pancreas; and, opening the excretory duct, insert a tube into it; and a similar plan was adopted success- fully on a horse by MM. Leuret and Lassaigne.d The difficulty, experienced in collecting a due quantity, is a pro- bable cause of some of the discrepancy amongst observers, reo-ardinf its sensible and chemical properties. Some of the older physiolo- gists affirm it to be acidulous and saline; others assert that it is alkaline.6 The majority of those of the present day compare it with the saliva, and affirm it to be inodorous, insipid, viscid, limpid, and of a bluish-white colour/ The latest experimenters by no means accord with each other. According to Magendie, it is of a slightly yellowish hue, saline taste, devoid of smell, occasionally alkaline, and partly coagulable by heat. MM. Leuret and Lassaigne found that of the horse—of which they obtained three ounces,—to be alkaline, a Tract, de Pancreat. Lugd. Bat. 1671; Haller. Elem. Physiol., lib. xxii. b Precis. &c, ii. 462. Ci Recherches, &c, i. 41. d Recherches &c. p. 49. e Haller. Elem. Physiol, vi. 10; Autenrieth's Physiologie, Band ii. § 623;' and Seiler, in art. Pancreas, Pierer's Anat. Physiol. Real Worterb., Band vi. 100 Altenb. 1825! f Fourcroy and Thomson, in their Systems of Chemistry. GLANDULAR—OF THE BILE. 287 and composed of 991 parts of water in 1000; of an animal matter, soluble in alcohol; another, soluble in water; traces of albumen and mucus; free soda; chloride of sodium; chloride of potassium, and phosphate of lime. In their view, consequently, the pancreatic juice strongly resembles saliva. MM. Tiedemann and Gmelin succeeded in obtaining upwards of two drachms of the juice in four hours ; and, in 100 parts, they found from five to eight of solid. These solid parts consisted of osmazome; a matter which became red by chlo- rine ; another analogous to caseine, and probably associated with salivary matter; much albumen; a little free acid, probably the acetic ; the acetate, phosphate, and sulphate of soda, with a little potassa; chloride of potassium, and carbonate and phosphate of lime :—so that, according to these gentlemen, the pancreatic juice differs from the saliva in containing:—a little free acid, whilst the saliva is alkaline; much albumen, and matter resembling caseine; but little mucus and salivary matter, and no sulpho-cyanate of potassa.* The precise use of the pancreatic juice in digestion—as we have previously seen—is not determined. Brunnerb removed almost the whole pancreas from dogs, and tied and cut away portions of the duct; yet they lived apparently as well as ever. It is not presuma- ble, therefore, that the secretion can be possessed of very important uses. d. Secretion of the Bile. The biliary secretion is, also, a digestive fluid, of which we have spoken in the appropriate place. The mode, however, in which the process is effected, has not yet been investigated. The apparatus consists of the liver, which accomplishes the for- mation of the fluid ; the hepatic duct,—the excretory channel, by which the bile is discharged; the gall-bladder, in which a portion of the bile is retained for a time; the cystic duct—the excretory chan- nel of the gall-bladder; and the ductus communis choledochus, or choledoch duct, formed by the union of the hepatic and cystic ducts, and which conveys the bile immediately into the duodenum. The liver, (A, A, Fig. 103, and A, A, Fig. 138,) is the largest gland in the body; situate in the abdomen beneath the diaphragm, above the stomach, the arch of the colon, and the duodenum; filling the whole of the right hypochondrium, and more or less of the epigastrium, and fixed in its situation byduplicatures of the peritoneum, called ligaments of the liver. The weight of the human liver is generally, in the adult, about three or four pounds. Some make the average about five pounds.c In disease, however, it sometimes weighs twenty or twenty- * Burdach's Physiologie, u. s. w., v. 257, Leipz. 1835. b Experimenta nova circa Pancreas. Amstel. 1683; and J. T. Mondiere, op. cit., in a Memoire, crowned by the Societe Medicale d'Emulation, of Paris, and entitled " Re- cherches pour servir a l'Histoire Pathologique du Pancreas." c W. J. E. Wilson, art. Liver, Cyclop, of Anat. and Phys. Sept. 1840. 288 SECRETION. five pounds; and, at other times, not as many ounces. Its shape is irre- gular, and it is divided into three chief lobes, the right, the left, and the lobulus spigelii. 'Its upper convex surface touches every where the arch of the diaphragm. The lower concave surface corresponds to the stomach, colon, and right kidney. On the latter surface, two fis- sures are observable;—the one passing from before to behind, and lodging the umbilical vein in the foetus—called the horizontal sulcus or fissure, great fissure or fossa umbilicalis; the other, cutting the last at right angles, and running from right to left, by which the different nerves and vessels proceed to and from the liver, and called the prin- cipal fissure, or sulcus transversus. The liver itself is composed of the following anatomical elements: 1. The hepatic artery, a branch of the coeliac, which ramifies minutely through the substance of the organ. The minuter branches of this artery are arranged somewhat like the hairs in a painter's brush, and have hence been called the penicilli of the liver. Mr. Kiernan* believes, that the blood, which enters the liver by the hepatic artery, fulfils three functions:—it nourishes the organ; supplies the excretory ducts with mucus; and, having fulfilled these objects, it becomes venous ; enters the branches of the portal veins, and not the radicles of the hepatic, as usually supposed, and contri- butes to the secretion of bile. 2. The vena porta, which we have elsewhere seen to be the common trunk of all the veins of the diges- tive organs and of the spleen. It divides like an artery, its branches accompanying those of the hepatic artery. Where the vein lies in the transverse fissure, it is of great size, and has hence been called sinus vence portce. The possession of two vascular systems, containing blood, is peculiar to the liver, and has been the cause of some difference of opinion, with regard to the precise material—arterial or venous —from which the bile is derived. According to Mr. Kiernan, the * Philosophical Transactions, for 1833, p. 711. See, also, Elliotson's Humaif Physio- logy, p. 93, Lond. 1840. Fig. 138. Abdominal and Pelvic Viscera. A, A. Concave surface of liver turned up- wards, and to the right side. B. Lobulus spi- gelii. Between B and C\ the porta of the liver. D. Ligamentum rotundum. E, P. Gall-blad- der. G. The pancreas. H. The spleen. I. The ribs. K, K. The kidneys. L, L. Renal veins. M, M. Ureters. N. Aorta. O. Sper- matic arteries. Q,, Q., Common iliac arteries. R. Vena cava. S. The spermatic veins. U, U. Common iliac veins. V. End of colon. X. Commencement of the rectum. Y, y. Uri- nary bladder. GLANDULAR—OF THE BILE. 289 portal vein fulfils two functions: it carries the blood from the hepa- tic artery, and the mixed blood to the coats of the excretory ducts. This vessel has been called the vena arteriosa, because it ramifies like an artery, and conveys blood for secreting: but, as Mr. Kier- nan has observed, it is an arterial vein in another sense, as it is a vein to the hepatic artery, and an artery to the hepatic veins. 3. The excretory ducts or biliary ducts. These are presumed to arise from acini, communicating, according to some, with the extremities of the vena portae; according to others, with radicles of the hepatic artery; whilst others have considered, that the radicles of the hepa- tic ducts have blind extremities, and that the capillary blood-vessels which secrete the bile, ramify on them. This last arrangement of the biliary apparatus in the liver was well shown in an interesting pathological case, which fell under the care of Professor Hall, in the Baltimore Infirmary, and which was examined after death in the author's presence. The particulars of the case have been detailed, with some interesting remarks by Professor Geddings.* In this case, in consequence of cancerous matter obstructing the ductus communis choledochus the whole excretory apparatus of the liver was enormously distended; the common duct was dilated to the size of the middle finger: at the point where the two branches that form the hepatic duct emerge from the gland, they were large enough to receive the tip of the middle finger; and as they were proportionately dilated to their radicles, in the intimate tissue of the liver, their termination in a blind extremity was clearly exhibited. These blind extremities were closely clustered together, and the ducts, proceeding from them, were seen to converge, and to termi- nate in the main trunk for the corresponding lobe. At their com- mencement, the excretory ducts are termed pori biliarii. These ultimately form two or three large trunks, which issue from the liver by the transverse fissure, and end in the hepatic duct. 4. Lymphatic vessels. 5. Nerves, in small number, compared with the size of the liver, some proceeding from the eighth pair; but the majority from the solar plexus, and following the course and divisions of the hepa- tic artery. 6. The supra-hepatic veins or vence cavce hepaticce, which arise in the liver by imperceptible radicles, communicating, accord- ing to common belief, with the final ramifications of both the hepa- tic artery and vena portas. They return the superfluous blood, carried to the liver by these vessels, by means of two or three trunks, and six or seven branches, which open into the vena cava inferior. These veins generally pass, in a convergent manner, • towards the posterior margin of the liver, and cross the divisions of the vena portae at right angles. 7. The remains of the umbilical vein, which, in the foetus, enters at the horizontal fissure. This vein, after respiration is established, becomes converted into a ligamentous substance, called, from its shape, ligamentum rotundum or round ligament. a North American Archives of Medical and Surgical Science, for June, 1835, p. 157. vol. ii. 25 290 SECRETION. The parenchyma, or substance formed by these anatomical ele- ments, it is difficult to describe; and although the term liver-coloured is used in common parlance, it is not easy to say what are the ideas attached to it. The organ has two coats;—the outer, derived from the perito- neum, which is very thin, transparent, easily lacerable, and vascu- lar, and is the seat of the secretion, operated by serous membranes in general. It does not cover the posterior part, or the excavation for the gall-bladder, the vena cava, or the 'fissures in the concave surface of the liver. The inner coat is the proper membrane of the liver. It is thin, but not easily torn, and it covers not only every part of the surface of the liver, but'also the large vessels that are proper to the organ. The condensed cellular substance,—which unites the sinus of the vena porta? and its two great branches, the hepatic artery, the common biliary duct, lymphatic glands, lympha- tic vessels, and nerves in the transverse fossa or fissure of the liver, —was described by Glisson as a capsule; and hence has been called the capsule of Glisson. The gall-bladder, (Figs. 103, 137, and 138,) is a small membra- nous pouch, of a pyriform shape, situate at the inferior and con- cave surface of the liver, to which it is attached, and above the colon and duodenum. A quantity of bile is usually found in it. It is not met with in all animals. It is wanting in the elephant, horse, stag, camel, rhinoceros, and goat; in certain of the cetacea; in some birds, as the ostrich, pigeon, and parrot; and is occasionally defi- cient in man. Its largest part, or fundus, Figs. 137 and 138, is turned forwards; and, when filled, frequently projects beyond the anterior margin of the liver. Its narrowest portion, cervix or neck is turned backwards, and terminates in the cystic duct. Externally, it is partly covered by the peritoneum, which attaches it to the liver, and to which it is, moreover, adherent by cellular tissue and vessels. Internally, it is rugous; the folds being reticulated, and appearing somewhat like the cells of a honey-comb. Anatomists have differed with regard to the number of coats proper to the gall-bladder. Some have described two only;—the peritoneal and mucous; others have added an intermediate cellular coat; whilst others have reckoned four;—a peritoneal coat,—a thin stratum of muscular fibres, passing in different directions, and of a pale colour,—a cellular coat, in which a number of blood-vessels is situate, and an internal mucous coat. The existence of the mus- ,cular coat has been denied by perhaps the generality of anatomists; but there is reason for believing in its existence. Amussat saw muscular fibres distinctly in a gall-bladder dilated by calculi; and Dr. Monro,* the present Professor of Anatomy in the University of Edinburgh, asserts, that he has seen it contract, in a living animal, for half an hour, under mechanical irritation, and assume the shape of an hour-glass. The mucous coat forms the rugae to which we * Elements of the Anatomy of the Human Body, Edinb. 1825. GLANDULAR-OF THE BILE. 291 have already alluded. In the neck, and in the beginning of the cystic duct, there are from three to seven—sometimes twelve— semilunar duplicatures, which retard the flow of any fluids inwards or outwards. These are sometimes arranged spirally, so as to form a kind of valve, according to Amussat.* On the inner surface of the gall-bladder, especially near its neck, numerous follicles exist; the secretion from which is said to fill the gall-bladder, when that of the bile has been interrupted by dis- ease, as in yellow fever, scirrhus of the liver, &c. The hepatic duct, Fig. 137, a, is the common trunk of all the excretory vessels of the liver; and makes its exit from that organ by the transverse fissure. It is an inch and a half in length, and about the diameter of an ordi- nary writing quill. It is joined, at a very acute angle, by the duct from the gall-bladder—the cystic duct, Fig. 137, e, to form the ductus communis choledochus. The cystic duct is about the same length as the hepatic. The ductus communis choledochus is about three, or three and a half, inches long. It descends behind the right extremity of the pancreas, through its substance; passes for an inch obliquely between the coats of the duodenum, diminishing in diame- ter; and ultimately terminates by a yet more contracted orifice, on the inner surface of the intestine, at the distance of three or four inches from the stomach. The structure of all these ducts is the same. The external coat is thick, dense, strong, and generally supposed to be of a cellular character; the inner is a mucous membrane, like that which lines the gall-bladder.b The secretion of bile is probably effected like the other glandular secretions; but modified, of course, by the peculiar structure of the liver. We have seen that the organ differs from every other secre- tory apparatus, in having two kinds of blood distributed to it:— arterial blood by the hepatic artery; and venous blood by the vena portae. A question has consequently arisen—from which of these is the bile formed 1 Anatomical inspection throws no light on the subject; and, accordingly, argument is all that can be adduced on one side or the other. The most common and the oldest opinion is, that the bile is separated from the blood of the vena portae; and the chief reasons adduced in favour of this belief, are the following: First. The blood of the portal system is better adapted than arterial blood for the formation of bile, on account of its having, like all venous blood, more carbon and hydrogen, which are necessary for the production of a humour as fat and oily as the bile; and, as the experiments of Schultz0 and others have proved, that the portal blood contains more fat than that of the other veins and arteries, it has been imagined, by some, that the blood, in crossing the omen- * Magendie's Precis, &c. ii. 464. b For a full account of the Normal Anatomy of the Liver, see W. J. E. Wilson, Cyclop. Anat. and Physiol., Sept. 1840. c Rust's Magazine, B. xliv.; Gazette Medicale, Aug. 15, 1835 ; and Amer. Journ. Med. Sciences, p. 445, Aug. 1836. See, also, Lafargue, Bullet. Medical, du Midi, Fevrier, 1839. 292 SECRETION. turn, becomes loaded with fat. Secondly. The vena portae ramifies in the liver, after the manner of an artery, and evidently communi- cates with the secretory vessels of the bile. Thirdly. It is larger than the hepatic artery; and more in proportion to the size of'the liver; the hepatic artery seeming to be merely for the nutrition of the liver, as the bronchial artery is for that of the lung. In answer to these positions, it has been argued; that there seems to be no more reason why the bile should be formed from venous blood than the other fatty and oleaginous humours—the marrow and fat for example,—which are derived from arterial blood. It is asked, too, whether, in point of fact, the blood of the vena portae is more rich in carbon and hydrogen? and whether there is a closer chemical rela- tion between the bile and the blood of the vena portae, than between the fat and arterial blood 1 The notion of the absorption of fat from the omentum, it is properly urged, is totally gratuitous. Secondly. The vena portae does not exist in the invertebrated animals, and yet, in a number of them, there is an hepatic apparatus, and a secretion of bile. Thirdly. Admitting that the vena portae is distributed to the liver after the manner of an artery; is it clear, it has been asked, that it is inservient to the biliary secretion 1 Fourthly. If the vena portae be more in proportion to the size of the liver than the hepatic' artery, the latter appears to bear a better ratio to the quantity of bile secreted; and, Lastly, it is probable, as has been shown in another place, that the liver has other functions connected with the portal system, in the admixture of heterogeneous liquids absorbed from the intestinal canal.* Similar views to those here expressed are entertained by Pro- fessor Giacomini,b of Padua; he considers, 1. That the system of the vena portae belongs less to the circulatory than to the absorbent system. 2. That the fluid which it contains is not real blood, but one that has not yet undergone the process of organic assimilation ; and, 3. That the liver is an excretory organ, which deprives the fluid of the vena portse of the principles that pass into the bile and are improper for assimilation. In the absence of accurate knowledge, derived from direct experi- ment, physiologists have usually embraced one or the other of these exclusive views. The generality, as we have remarked, assign the function to the vena portae. Bichat, on the other hand, ascribes it to the hepatic artery. Broussais0 thinks it probable, that the blood of the vena portse is not foreign to the formation of the bile, since it is confounded with that of the hepatic artery in the parenchyma of the liver; " but to say with the older writers, that the bile cannot be formed but by venous blood, is, in our opinion," he remarks, "to advance too bold a position, since the hepatic artery sends branches a Adelon, art. Foie, (Physiol.) in Diet, de Med. ix. 193, Paris, 1824; and Physiol. de I'Homme, torn. iii. 505, Paris, 1829. b Encyolograph, des Sciences Medicales, Avril, 1840. c Traite de Physiologie, &,c., Dr. Bell and Laroche's translation, 3d edit. p. 456, Philad. 1832; Seiler, art. Leber, in Anat. Phys. Real Worterb. v. 736, Leipz. 1821; and Conwell's Treatise on the Liver, p. 54, London, 1835, GLANDULAR-OF THE BILE. 293 to each of the glandular-acini, that compose the liver." Magendie likewise concludes, that nothing militates against the idea of both kinds of blood serving in the secretion; and that it is supported by anatomy; as injections prove, that all the vessels of the liver,—arte- rial, venous, lymphatic, and excretory,—communicate with each other. Mr. Kiernan, as we have seen, considers that the blood of the hepatic artery is inservient to the secretion, but not until it has become venous, and entered the portal veins. He, with all those that coincide with him in the anatomical arrangement of these parts —denies that there is any communication between the ducts and the blood-vessels; and he asserts that if injections pass between them, it is owing to the rupture of the coats of the vessels. Experiments on pigeons, by M. Simon,* of Metz, showed, that when the hepatic artery was tied, the secretion of bile continued, but that if the veins of the porta and the hepatic veins were tied, no trace of bile was subsequently found in the liver. It would thence appear, that in these animals the secretion of bile takes place from venous blood; but inferences from the ligature of those vessels have been very discordant. In two cases, in which Mr. Phillips tied the hepatic artery, the secretion of bile was uninterrupted: yet the same thing was observed in three other cases, in which the ligature was applied to the trunk of the vena portae. The view, that ascribes the bile to the hepatic artery, appears to us the most probable. It has all analogy in its favour. We have no disputed origin as regards the other secretions. They all pro- ceed from arterial blood; and function sufficient, we think, can be assigned to the portal system, without conceiving it to be concerned in the formation of bile. (See p. 36 of this volume.) We have, more- over, pathological cases, which would seem to show that bile can be formed from the blood of the hepatic artery. Mr. Abernethyb met with an instance, in which the trunk of the vena portae terminated in the vena cava; yet bile was found in the biliary ducts. A similar case is given by Mr. Lawrence ;c and the present Professor Monro,d details a case communicated to him by the late Mr. Wilson, of the Windmill Street School, in which there was reason to suppose, that the greater part of the bile had been derived from the hepatic artery. The patient, a female, thirteen years old, died from the effects of an injury of the head. On dissection Mr. Wilson found a large swelling at the root of the mesentery, consisting of several absorbent glands in a scrofulous state. Upon cutting into the mass, he acci- dentally observed a large vein passing directly from it into the vena cava inferior, which, on dissection, proved to be the vena portae; and on tracing the vessels entering into it, one was found to be the inferior mesenteric vein; and another, which came directly to meet it, from behind the stomach, proved to be a branch of the splenic * Edinb. Med. and Surg. Journal, xc. 229 ; and Mayo's Outlines of Human Physio- logy, 3d edit. p. 130, Lond. 1833. b Philosoph. Transact, vol. lxxxiii. c Medico-Chirurgical Transact, iv. 174. d Elements of Anatomy, Edinb. 1825. 25* 294 SECRETION. vein, but somewhat larger, which ran upwards by the side of the vena cava inferior, and entered that vein immediately before it passes behind the liver. Mr. Wilson then traced the branches of the trunk of the vessel corresponding to the vena portae sufficiently far in the mesentery and mesocolon, to be convinced, that it was the only vessel that returned the blood from the small intestines, and from the caecum and colon of the large. He could trace no vein passing into the liver at the cavity of the porta; but a small vein descended from the little epiploon, and soon joined one of the larger branches of the splenic vein. The hepatic artery came off in a distinct trunk from the aorta, and ran directly to the liver. It was much larger than usual. The greater size of the hepatic artery, in this case, would favour the idea, that the arterial blood had to execute some office, that ordinarily belongs to the vena portae. Was this the formation of bile ? The case seems, too, to show, that bile can be formed from the blood of the hepatic artery. In Professor Hall's patient, (p. 281,) the vena portae and its bifurca- tion were completely filled with encephaloid matter, so that no blood could pass through it to the liver; the secretion of the bile could not, consequently, be effected through its agency. It has been pre- sumed, however, that in such cases, portal blood might still enter the liver through the extensive anastomoses, which Professor Retzius,* of Stockholm, found to exist between the abdominal veins. That gentleman observed, when he tied the vena portae near the liver, and threw a coloured injection into the portion below the ligature, that branches were filled, some of which, proceeding from the duodenum, terminated in the vena cava; whilst others, arising from the colon, terminated in the left emulgent vein. In subsequent investigations, he< observed an extensive plexus of minute veins ramifying in the cellular tissue on the outer surface of the peritoneum, part of which was connected with the vena portae, whilst the other part termi- nated in the system of the vena cava. In a successful injection, these veins were seen anastomosing very freely, in the posterior part of the abdomen, with the colic veins, as well as those of the kidneys, pelvis, and even with the vena cava. The arrangement, pointed out by Retzius, accounts for the mode in which the blood of the abdominal venous system reaches the cava, when the vena portae is obliterated from any cause; and it shows the possibility of portal blood reaching the liver so as to be inservient to the biliary secretion, but does not, we think, exhibit its probability. When bile is once secreted in the tissue of the liver, it is received into the minute excretory radicles, whence it proceeds along the ducts, until it arrives, from all quarters, at the hepatic duct. A difference of sentiment exists regarding the flow of the bile from 3 Ars Berattelse af Setterblad, 1835, s. 9; and Zeitschrift fiir die Gcsammte Heil- kunde, Feb. 1837, s. 251; also, Muller's Handbuch, u. s. w., Baly's translation p. 185 Lond. 1837. » r > GLANDULAR—OF THE BILE. 295 the liver and gall-bladder into the duodenum. According to some, it is constantly passing along the choledoch duct; but the quantity is not the same during digestion as at other times. In the intervals, a part only of the secreted bile attains the duodenum ; the remainder ascends along the cystic duct, and is deposited in the gall-bladder. During digestion, however, not only the whole of the secretion arrives at the duodenum, but all that which had been collected in the interval is evacuated into the intestine. In support of this view it is affirmed, that bile is always met with in the duodenum; that the gall-bladder always contains more bile when abstinence is pro- longed, whilst it is empty immediately after digestion. The great difficulties have been, to explain how the bile gets into the gall-bladder, and how it is expelled from that reservoir. In many birds, reptiles, and fishes, the hepatic duct and the cystic duct open separately into the duodenum ; whilst ducts, called hepato- cystic, pass directly from the liver to the gall-bladder. In man, however, the only visible route, by which it can reach that reser- voir, is by the cystic duct, the direction of which is retrograde; and, consequently, the bile has to ascend against gravity. The spiral valve of Amussat has been presumed to act like the screw of Archi- medes, and to facilitate the entrance of the refluent bile, but this appears to be imaginary. It is, indeed, impossible to see any analogy between the corporeal and the hydraulic instrument. The arrangement of the termination of the choledoch duct in the duo- denum has probably a more positive influence. The embouchure is the narrowest part of the duct, the ratio of its calibre to that of the hepatic duct having been estimated at not more than one to six, and to the calibre of its own duct as one to fifteen. This might render it impracticable for the bile to flow into the duodenum as promptly as it arrives at the embouchure ; and, in this way, collect- ing in the duct, it might reflow into the gall-bladder. Amussat, indeed, affirms, that this can be demonstrated on the dead body. By injecting water or mercury into the upper part of the hepatic duct, the injected liquid was found to issue both by the aperture into the duodenum, and by the upper aperture of the cystic duct into the gall-bladder. With regard to the mode in which the gall-bladder empties itself during digestion, it is probably by a contractile action. We have seen that, it has not usually been admitted to possess a muscular coat, but that it is manifestly contractile. The chyme, as it passes into the duodenum, excites the orifice of the choledoch duct; this excitement is propagated along the ducts to the gall-bladder, which contracts; but, according to Amussat, it does not evacuate its con- tents suddenly, for the different planes of the spiral valve are applied against each other, and only permit the flow to take place slowly. This he found was the case, in the subject, when water was in- jected into the gall-bladder, and pressed out through the cystic duct." * Adelon, Physiol, de I'Homme, iii. 494; and art. Foie, op. citat. 296 SECRETION. Other physiologists have presumed, that although the bile is secreted in a continuous manner, it only flows into the duodenum at the time of chylification; at other times, the choledoch duct is contracted, so that the bile is compelled to reflow through the cystic duct into the gall-bladder; and it is only when the gall-bladder is filled, that it passes freely into the duodenum. Independently, however, of other objections to this view, vivisections have shown, that if the orifice of the choledoch duct be exposed, whatever may be the cir- cumstances in which the animal is placed, the bile is seen issuing guttatim at the surface of the intestine. The biliary secretion, which proceeds immediately from the liver, —hence called hepatic bile, differs from that obtained from the gall- bladder, which is termed cystic bile. The latter possesses greater bitterness, is thicker, of a deeper colour, and is that which has been usually analyzed. It is of a yellowish-green colour, viscid, and slightly bitter. Its chemical properties have been frequently exa- mined ; yet much is still needed, before we can consider the analysis satisfactory. It has been examined by Boerhaave, Verheyen, Bag- livi, Hartmann, Macbride, Ramsay, Gaubius, Cadet, Fourcroy, Maclurg, Thenard, Berzelius, Chevreul, Leuret and Lassaigne, Frommherz and Gugert, Schultz, Vogel, John, Treviranus, Tiede- mann and Gmelin, &c. &c. Thenard's* analysis of 1100 parts of human bile is as follows:—water, 1000; albumen, 42; resinous matter, 41; yellow matter, 2 to 10; free soda, 5 or 6; phosphate, muriate, and sulphate of soda, phosphate of lime, and oxide of iron, 4 or 5. According to Chevallier, it contains also a quantity of picro- mel. Berzeliusb calls in question the correctness of Thenard's ana- lysis, and gives the following:—water, 908.4 ; picromel, 80; albu- men, 3.0; soda, 4.1; phosphate of lime, 0.1; common salt, 3.4; phosphate of soda, with some lime, 1.0. The results of Dr. DavyV analysis of healthy bile were as follows:—water, 86.0 ; resin of bile, 12.5 ; albumen, 1.5. Lastly, the experiments of Gmelin, for which he is highly complimented by Berzelius,d although Berzelius consi- ders, that some of the products may have been formed by the re- action of elements upon each other—yielded the following results— an odorous material, like musk; cholesterine; oleic acid; margaric acid; cholicacid; resin of bile; taurin (gallen-asparagin); picromel; colouring matter; osmazome; a substance, which, when heated, had the odour of urine; a substance resembling birdlime, gleadine; albumen (?); mucus of the gall-bladder; caseine, or a similar sub- stance ; ptyaline, or a similar matter; bicarbonate of soda; carbo- nate of ammonia; acetate of soda; oleate, margarate, cholate, and * Mem. de la Societe d'Arcueil, i. 38, Paris, 1807. b Med. Chirurgical Transactions, iii. 241. c Monro's Elements of Anatomy, i. 579. d Henle, art. Galle, in Encyclop. Worterb. u. s. w., p. 126 ; art. Bile, by Mr. Brande, in Cyclop, of Anat. and Physiol, part iv. p. 374, Lond. 1835 ; Orfila, art. Bile, in Diet de Medecine, i. 355, Paris, 1821; and Burdach's Physiologie als Erfahrungswissen- schaft, v. 260, Leipz. 1835. GLANDULAR-OF THE BILE. 297 phosphate of potassa and soda ; muriate of soda and phosphate of lime. Cadet* considered bile as a soap with a base of soda, mixed with sucrar of milk—a view, which Raspailb considers to harmo- nize with observed facts. Every other substance met with in the bile, Raspail looks upon as accessary. Lastly, it has been more recently analyzed by Muratori,c who assigns it the following consti- tuents ;—water, 832; peculiar fatty matter, 5; colouring matter, 11; cholesterine combined with soda, 4; picromel of Thenard, 94.86 ; extract of flesh (Estratto di came), 2.69 ; mucus, 37 ; soda, 5.14; phosphate of soda, 3.45; phosphate of lime, 3; and chlo- ride of sodium, 1.86. Berzeliusd is engaged in an elaborate ana- lysis, which will doubtless be one of the most accurate we possess. The specific.gravity of bile, at 6° centigrade, according to The- nard, is 1.026. Schultz found that of an ox, after feeding, at 15° to be 1.026 ; of a fasting animal, 1.030. Hepatic and cystic bile do not appear to differ materially from each other, except in the greater concentration of the different ele- ments in the latter. Leuret and Lassaigne6 found them to be alike in the dog. Orfila/ however, affirms, that human hepatic bile does not contain picromel. The great uses of the bile have been detailed under the head ot digestion. It has been conceived to be a necessary depurative ex- cretion ; separating from the blood matters that would be injurious if retained. This last idea is probable; but our knowledge of the precise changes, produced in the mass of blood by it, are extremely limited. The view has been ingeniously contended for by MM. Tiedemann and Gmelin,8 who regard the function of the liver to be supplementary to that of the lungs—in other words, to remove carbon from the system. The arguments, adduced in favour of their position, are highly specious, and ingenious. The resin of the bile, they say, abounds most in herbivorous animals, whose food contains a great disproportion of carbon and hydrogen. The pulmonary and biliary apparatuses are in different tribes of animals, and even in different animals of the same species, in a state of antagonism to each other. The size of the liver, and the quantity of bile are not in proportion to the quantity of food and frequency of eating, but inversely proportionate to the size and perfection of the lungs. Thus, in warm-blooded animals, which have large lungs, and live always in the air, the liver, compared with the body, is proportionally less than in those that live partly in water. The liver is proportionally still larger in reptiles, which have lungs with large cells incapable of rapidly decarbonizing the blood,—and in fishes, which decarbonize the blood but slowly by the gills> and, above all, in molluscous ani- 1 Experiences sur la Bile des Hommes, &c. in Mem. de I'Academ. de Paris, 1767. b Chimie Organique, p. 451, Edinb. 1833. c Bulletino Mediche di Boloyna, p. 160, Agosto et Settembre, 1836. d Annalcn der Chemie und Pharmacie, xxxiii. 139, Journal de Pharmacie, Jan. 1840. e Recherches, &c. sur la Digestion, Paris, 1825. f Elem. de Chimie, Paris, 1817. s Die Verdaung nach Versuch. &c. traduit par Jourdan, Paris, 1827. See, also, Lafargue, Bullet. Medical du Midi, Fevrier, 1839. 298 SECRETION. mals, which effect the same change very slowly, either by gills, or by small imperfectly developed lungs. Again,—the quantity of venous blood, sent through the liver, increases as the pulmonary system becomes less perfect. In the mammalia, and in birds, the vena portae is formed by the veins of the stomach, intestines, spleen, and pancreas; in the tortoise, it receives also the veins of the hind legs, pelvis, tail,—and the vena azygos: in serpents, it receives the right renal, and all the intercostal veins; in fishes the renal veins, and those of the tail and genital organs. Moreover, during the hibernation of certain of the mammalia, when respiration is sus- pended, and no food taken, the secretion of bile goes on. Another argument is deduced from the physiology of the foetus, in which the liver is proportionally larger than in the adult, and in which the bile is secreted copiously, as appears from the great increase of the meconium during the latter months of utero-gestation. Their last argument is drawn from pathological facts. In pneumonia and phthisis, the secretion of bile, according to their observations, is increased; in diseases of the heart the liver is enlarged; and in the morbus caeruleus, the liver retains its foetal proportion. In hot cli- mates, too, where, in consequence of the greater rarefaction of the air, respiration is less perfectly effected than in colder, a vicarious decarbonization of the blood is established by an increased flow of bile. That the separation of the bile from the blood, however, is not an indispensable function, is shown by Dr. Blundell,* who gives the cases of two children that lived for four months, appa- rently well fed and healthy, and on opening their bodies, it was found that the biliary ducts terminated in a cul-de-sac, and that con- sequently not a drop of bile had been discharged into the intestines. Lastly;—Mr. Voisin,b considers the liver to be a secreting organ, the office of which is the depuration not only of the venous blood, but, as we have before shown, of the chyle. If the excretion of the bile be prevented from any cause, we know that derangement of health is induced; but it is probable that its agency in the production of disease is much overrated; and that, as Broussais has suggested, the source of many of the affections, termed bilious, is in the mucous membrane lining the stomach and intestines; which, owing to the heterogeneous matters constantly brought into contact with it, must be peculiarly liable to be morbidly affected. When irritation exists there, we can easily understand how the secre- tion from the liver may be consecutively modified; the excitement spreading directly along the biliary ducts to the secretory organ. e. Secretion of Urine. This is the most extensive secretion accomplished by any of the glandular structures of the body, and is essentially depurative; its suppression giving rise to formidable evils. The apparatus consists a Stokes, Theory and Practice of Medicine, Dunglison's American Medical Library Edition, p. 104, Philad. 1837. b Nouvel Apercu sur la Physiologie du Foie et les Usages de la Bile, &c. Paris, 1833, GLANDULAR—OF THE URINE. 299 of the kidneys, which secrete the fluid; the ureters, which convey the urine to the bladder; the bladder itself, which serves as a reservoir for the urine; and the urethra, which conveys the urine externally. These will require a distinct consideration. The kidneys are two glands situate in the abdomen; one on each side of the spine, (Fig. 138, K, K,) in the posterior part of the lumbar region. They are without the cavity of the peritoneum, which covers them at the anterior part only, and are situate in the midst of a considerable mass of adipous cellular tissue. The right kidney is nearly an inch lower down than the left, owing to the thick posterior margin of the right lobe of the liver pressing it downwards. Occasionally, there is but one kidney; at other times, three have been met with. They have the form of the haricot or kidney-bean, which has, indeed, been called after them; and are situate ver- tically—the fissure being turned inwards. If we compare them with the liver, their size is by no means in proportion with the extensive secretion effected by them. Their united weight does not amount to more than six or eight ounces. They are hard, solid bodies, of a brown colour. The sanguiferous vessels, which convey and return the blood to them, as well as the excretory duct, communicate with the kidney at the fissure. The anatomical constituents of these organs are;—1. The renal ar- tery, which arises from the abdominal aorta at a right angle, and, after a short course, enters the kidney, ramifying in its substance. 2. The excretory ducts, which arise from every part of the tissue, in which the ramifi- cations of the renal artery terminate, and end in the pelvis of the kidney. (Fig. 139.) 3. The renal veins, which receive the superfluous blood, after the urine has been separated from it, and terminate in the renal or emulgent vein, which issues at the fissure, and opens into the abdominal vena cava. 4. Of lymphatic vessels, arranged in two planes—a superficial and a deep- seated, which terminate in the lumbar glahds. 5. Of nerves, which proceed from the semilunar ganglion, solar plexus, &c, and which surround the renal artery as with a network, fol- lowing it in all its ramifications. 6. Of cellular membrane, which, as in every other organ, binds the parts to- gether. These anatomical elements, by their union, constitute the organ as we find it. When the kidney is divided longi- tudinally, it is seen to consist of two substances, which differ in Section of the Kidney. a, a. The cortical substance, b, b. The tubular portion, c, c, c. c. The papillae, d. The pelvis : and e. The ureter. 300 SECRETION. their situation, colour, consistence, and texture. The one of these, and the more external, is called the cortical or glandular substance. It forms the whole circumference of the kidney; is about two lines in thickness; of less consistence than the other; of a pale red colour; and receives almost entirely the ramifications of the renal artery. The other and innermost is the tubular, medullary, uriniferous, conoidal or radiated substance. It is more dense than the other; less red; and seems to be formed of numerous minute tubes, which unite in conical bundles of unequal size, and the base of which is turned towards the cortical portion; the apices forming the papilla or mammillary processes, and facing the pelvis of the kidney. The papillae vary in number, from five to eighteen; are of a florid colour; and upon their points or apices are the terminations of the uri- niferous tubes, large enough to be distinguished by the naked eye. Around the root of each papilla a membranous tube arises called calix or infundibulum: this receives the urine from the papilla, and conveys it into the pelvis of the kidney, which may be regarded as the commencement of the ureter. Similar ideas, with regard to the precise termination of the blood- vessel, and the commencement of the excretory duct, have prevailed, as in the case of the liver and other glands: their intimate structure, however, escapes detection. In the quadruped, each kidney is made up of numerous lobes, which are more or less intimately united, according to the species. In birds, the kidneys consist of a double row of distinct, but con- nected, glandular bodies, placed on both sides the lumbar vertebrae. The ureter is a membranous duct, which extends from the kidney to the bladder. It is about the size of a goosequill; descends through the lumbar region; dips Fig. 140. into the pelvis by crossing in front of the primitive iliac vessels and the inter- nal iliac; crosses the vas deferens at the back of the bladder, and, penetrating that viscus obliquely, ter- minates by an orifice, ten or twelve lines behind that of the neck of the bladder. At first, it penetrates two of the coats only of that viscus; running for the space of an inch between the mucous and muscular coats, and then entering Bladder, Urethra, fyc. A. Crus penis. B. Bulb of the urethra. C. Membranous .1 •. part of the urethra. D. Prostate gland. E. Vesiculee semi- lie Cavity. nales. F, F. Vasa deferentia. G. Ureter. H. Upper part of Trip nrptpr« the bladder, covered by peritoneum. have two coats. The outermost is a dense fibrous membrane; the innermost a thin mucous layer, con- GLANDULAR-OF THE URINE. 301 tinuous at its lower extremity with the inner coat of the bladder .and at the upper end supposed, by some, to be reflected, over the papillae, and even to pass for some distance into the tubuh unnifen. The bladder is a musculo-membranous sac, situate in the pelvis, anterior to the rectum, and behind the pubes Its superior-end is called the upper fundus; and the lower end, the inferior fundus or bas-fond; the body being situate between the two. The part^where it joins the urethra is the neck. The shape and situation of the organ are influenced by age and by sex. In very young mfants, i is cylin- droid, and rises up almost wholly into the abdomen. In the adult female, who has borne many children, it is nearly spherical; has its greatest diameter transverse, and is more capacious than in the "like the other hollow viscera, the bladder consists of several coats. 1. The peritoneal coat, which covers only the fundus and back part. Towards the lower portion the organ is invested by cellular membrane, which takes the place of the peritoneal coat of the fundus. This tissue is very loose, and permits the distension and contraction of the bladder. 2. The muscular coat is very strong; so much so, that it has been classed amongst the distinct muscles, under the name detrusor urina. The fibres are pale,and pass in various directions. Towards the lower part of the bladder, they are particularly strong; arranged in fasciculi, and form a kind ot network of muscles inclosing the bladder. In cases of stricture ot the urethra, where much effort is necessary to expel the urine, these fasciculi acquire considerable thickness and strength. 3. Ihe mucous or villous coat is the lining membrane, which is continuous with that of the ureters and urethra, and is generally rugous, m consequence of its being more extensive than the muscular coat without. It is furnished with numerous follicles, which secrete a fluid to lubricate it. Towards the neck of the organ, it is thin and white, though reddish in the rest of its extent. A fourth coat, called the cellular, has been reckoned by most anatomists, but it is nothing more than cellular tissue uniting the mucous and muscular " The part of the internal surface of the bladder, situate imme- diately behind and below its neck, and occupying the space between it and the orifices of the ureters, is called the vesicle triangle, tngo- nus Lieutaudi or trigone vesical. The anterior angle of the triangle looks into the orifice of the urethra, and is generally so prominent, that it has obtained the name uvula vesica. It is merely a pro- jection of the mucous membrane, dependent upon the subjacent third lobe of the prostate gland, which, in old people, is frequently enlarged, and occasions difficulty in passing the catheter. The neck of the bladder penetrates the prostate gland, but, at its commencement, it is surrounded by loose cellular tissue, containing a very large and abundant plexus of veins. The internal layer of muscular fibres is here transverse; and they cross and intermix with each other, in different directions, forming a close, compact vol. ii. 26 302 SECRETION. tissue, which has the effect of a particular apparatus for retaining the urine, and has been called the sphincter. Anatomists have not usually esteemed this structure to be distinct from the muscular coat at large; but Sir Charles BeUa asserts, that if we begin the dissection by taking off the inner membrane of the bladder from around the orifice of the urethra, a set of fibres will be discovered, on the lower half of the orifice, which, being carefully dissected, will be found to run in a semicircular form around the urethra. These fibres make a band of about half an inch in breadth, particu- larly strong on the lower part of the opening; and having ascended a little above the orifice, on each side, they dispose of a portion of their fibres in the substance of the bladder. A smaller and some- what weaker set of fibres will be seen to complete their course, surrounding the orifice on the upper part. The arteries of the bladder proceed from various sources, but chiefly from the umbilical and common pudic. The veins return the blood into the internal iliacs. They form a plexus of considera- ble size upon each side of the bladder, particularly about its neck. The lymphatics accompany the principal veins of the bladder, and, at the under part and sides, pass into the iliac glands. The nerves are from the great sympathetic and sacral. The urethra is the excretory duct of the bladder. It extends, in the male, from the neck of the bladder to the extremity of the glans; and is from seven to ten inches in length. In the female it is much shorter. The male urethra has several curvatures in the state of flaccidity of the penis; but is straight, or nearly so, if the penis be drawn forwards and upwards, and if the rectum be empty. The first portion of this canal, which traverses the prostate gland, is called the prostatic portion. Into it open,—on each side of a carun- cle, called the verumontanum, caput gallinaginis or crista ureihralis, —the two ejaculatory ducts, those of the prostate, and, a little lower! the orifice of Cowper's glands. Between the prostate and the bulb is the membranous part of the urethra, which is eight or ten lines long. The remainder of the canal is called the corpus spongiosum or spongy portion, because surrounded by an erectile sponoy tissue. It is situate beneath the corpora cavernosa, and passes forward to terminate in the glans; the structure of which will be considered under Generation. At the commencement of this portion of the urethra is the bulb of the urethra, Fig. 140, B; the structure of which resembles that of the corpora cavernosa of the penis—to be described hereafter. The dimensions of the canal are various. At the neck of the bladder, it is considerable; behind the caput gallinaginis it contracts, and immediately enlarges in the forepart of the prostate. The membranous portion is narrower; and, in the bulb, the channel enlarges. In the body of the penis, it diminishes successively, till it * Anatomy and Physiol. 5th Amer. Edit., by Dr. Godman, ii. 375 New York 1829 PhihAl'sS. SUbJCCt' ^ H°rner' SpeCkl and General Aaatomy. »• S2. 5th edit.; GLANDULAR--OF THE URINE. 303 nearly attains the glans, when it is so much increased in size as to have acquired the name fossa navicularis. At the apex of the glans it terminates by a short vertical slit. Mr. Shaw* has described a set of vessels, immediately on the out- side of the internal membrane of the urethra, which, when empty, are very similar, in appearance, to muscular fibres. These vessels, he remarks, form an internal spongy body, which passes down to the membranous part of the urethra, and forms even a small bulb there. Dr. Horner,b however, says, that this appeared to him to be rather the cellular membrane connecting the canal of the urethra with the corpus spongiosum. The whole of the urethra is lined by a very vascular and sensible mucous membrane, which is continued from the inner coat of the bladder. It has, apparently, a certain degree of contractility, and therefore, by some anatomists, is conceived to possess muscular fibres. Sir Everard Home, from the results of his microscopical observations, is disposed to be of this opinion. This is, however, so contrary to analogy, that it is probable the fibres may be seated in the tissue surrounding it. The membrane contains numerous folli- cles, and several lacunae, one or two of which, near the extremity of the penis, are so large as occasionally to obstruct the catheter, and to convey the impression that a stricture exists. The prostate and the glands of Cowper, being more concerned in generation, will be described hereafter. There are certain muscles of the perineum, that are engaged in the expulsion of the urine from the urethra; and some of them in defecation and in the evacuation of the sperm likewise; as the ac- celeratores urince or bulbo-urelhrales, which propel the urine or semen forward ;c the transversus perinei or ischio-perinealis, which dilates the bulb for the reception of the urine or semen; the sphincter ani, which draws down the bulb, and thus aids in the ejection of the urine or sperm; and the levator ani, which surrounds the extremity of the rectum, the neck of the bladder, the membranous portion of the urethra, the prostate gland, and a part of the vesiculae seminales, and assists in the evacuation of the bladder, vesiculae seminales, and prostate. A part of the levator, which arises from the pubis and assists in inclosing the prostate gland, is called by Sommering com- pressor prostata. Between the membranous part of the urethra, and that portion of the levator ani which arises from the inner side of the symphysis pubis, a reddish, cellular, and very vascular substance exists, which closely surrounds the canal, has been described by Mr. Wilson"1 under the name compressor urethra, and is termed, by some of the French anatomists, muscle de Wilson. By many, how- a Manual of Anatomy, ii. 118, Lond. 1822. b Lessons in Practical Anatomy, 3d edit. p. 272, Philad. 1836; and Amer. Journal of the Medical Sciences, p. 538, for Feb. 1832. c For Dr. Horner's views on the origin of the acceleratores urinre, see his Special and General Anat. ii. 101, Philad. 1839. d Lectures on the Structure and Physiology of the Urinary and Genital Organs, Lond. 1821. 304 SECRETION. ever, it is considered to be a part of the levator ani. Amussat asserts, that the membranous part of the urethra is formed, exter- nally, of muscular fibres, which are susceptible of energetic con- traction, and Magendie* confirms his assertion. With regard to the urinary organs of the female:—the kidneys and ureters have the same situation and structure as those of the male. The bladder also, holds the same place behind the pubis, but rises higher when distended. It is proportionally larger than the bladder of the male, and is broader from side to side, thus allowing the greater retention to which females are often necessitated. The urethra is much shorter, being only about an inch and a half, or two inches long, and it is straighter than in the male, having only a slight curve downwards between its extremities, and passing almost hori- zontally under the symphysis of the pubis. It has no prostate gland, but is furnished, as in the male, with follicles and lacunae, which provide a mucus to lubricate it. In birds in general, and in many reptiles and fishes, the urine, prior to expulsion, is mixed with the excrement in the cloaca. Nothing analogous to the urinary organs has been detected in the lowest classes of animals, although in the dung of the caterpillars of certain insects, traces of urea have been met with. The urine is separated from the blood in the kidneys. According to Raspail,b it is a kind of caput mortuum, rejected into the urinary bladder by those glands. The proofs of this separation are easy and satisfactory; but with regard to the mode in which the opera- tion is effected, we are in the same darkness that hangs over the glandular secretions in general. The transformation must, however, occur in the cortical part of the organ; for the tubular portion seems to consist only of a collection of excretory ducts, and, if we cut into it, urine oozes out. The urinary secretion takes place continuously. If a catheter be left in the bladder, the urine drops constantly; and in cases of ex- strophia of the bladder—a faulty conformation, in which the organ opens above the pubes, so that a red mucous surface, formed by the inner coat of the bladder, is seen in the hypogastric region, in which two prominences are visible, corresponding to the openings of the ureters—the urine is seen to be constantly passing out at these open- ings.0 After the secretion has been effected in the cortical substance, it flows through the tubular portion, and issues guttatim through the apices of the papillae into the pelvis of the kidney, whence it pro- ceeds along the ureter to the bladder. When the uriniferous cones are slightly compressed, the urine issues in greater quantity, but, instead of being limpid, as when it flows naturally, it is thick and troubled. Hence a conclusion has been drawn, that it is really filtered through the hollow fibres of the medullary or tubular por- tion. If this were the case, what must become of the separated a Precis, &c. ii. 472. »> Chimie Organique, p. 505, Paris, 1833. c See note of a case of this kind, by the author, in Amer. Med. Intelligencer i. 137 • and another, by Dr. Pancoast, ibid. p. 147, Philad. 1838 GLANDULAR—OF THE URINE. 305 thick portion? Ought not the tubes to become clogged up with it? And is it not more probable, that compression, in this case, forces out with the urine some of the blood that is connected with the nutrition of the organ ? The fresh secretion constantly taking place in the kidney causes the urine to flow along the tubuli uriniferi to the pelvis of the organ, whence it proceeds along the ureter, if we are in the erect attitude, by virtue of its gravity; the fresh fluid, too, continually secreted from the kidney, pushes on that which is before it; and, moreover, there is not improbably some degree of contractile action exerted by the ureters themselves; although, as in the case of the excretory ducts in general, such a power has been denied them. These are the chief causes of the progression of the urine into the bladder, which is aided by the pressure of the abdominal contents and muscles, and, it is supposed, by the pulsation of the renal and iliac arteries; but the agency of these must be trivial. The orifices of the ureters form the posterior angles of the trigone vesical, and are contracted somewhat below the size of the ducts themselves. They are said, by Sir Charles Bell,a to be furnished with a small fasciculus of muscular fibres, which runs backwards from the orifice of the urethra, immediately behind the lateral mar- gins of the triangle, and, when it contracts, stretches the orifice of the ureter so as to permit the urine to enter the bladder with facility. As the urine enters, it gradually distends the organ until the quan- tity has attained a certain amount. It cannot reflow by the ureters, on account of the smallness of their orifices and their obliquity; and as the bladder becomes filled,—owing to the duct passing for some distance between the muscular and mucous coats,—the sides are pressed against each other, so that the cavity is ob- literated. (Fig. 141.) As, however, the ureters have a tendency to lose this obliquity of insertion, in propor- tion as the bladder is emptied, the two bands of muscular fibres which run from the back of the prostate gland to the orifices of the ureters, not only assist in emptying the blad- der, but, at the same time, pull down A the orifices of the ureters, and thus tend to preserve the obliquity.b Moreover, when we are in the erect Fig. 141. Entrance of the Ureter into the Bladder. Cavity of the bladder. B. Ureter. C. Vesical orifice of the ureter. 1 Anatomy and Physiology, 5th American edit;, by Godman, ii. 381, New York, 1827. b Sir C. Bell, op. cit., and in Medico-Chirurgical Transactions, vol. iii. 26* 306 SECRETION. attitude, the urine would have to enter the ureters against gravity. These obstacles are so effective, that if an injection be thrown for- cibly and copiously through the urethra into the bladder, it does not enter the ureters. On the other hand, equally powerful impedi- ments exist to its being discharged through the urethra. The infe- rior fundus of the bladder is situate lower than the neck; and the sphincter presents a degree of resistance, which requires the blad- der to contract forcibly on*its contents, aided by the abdominal muscles to overcome it. Magendie3 considers the contraction of the levatores ani to be the most efficient cause of the retention of the urine; the fibres which pass around the urethra pressing its sides against each other and thus closing it. The urine accumulates in the bladder until the desire arises to expel it: the number of times that a person in health and in the mid- dle period of life, discharges his urine in the twenty-four hours, varies; whilst some evacuate the bladder but twice, others may be compelled to do so as many as twelve or fourteen times. Nine times, according to Dr. Thomas Thomson,b is a common number. The quantity, too, discharged at a time, varies. The greatest quantity observed by Dr. Thomson was 25^ cubic inches, or some- what less than a pint, the most common quantity being from seven to nine cubic inches. During the stay of the urine in the bladder, it is believed to be deprived of some of its more aqueous portions by absorption, and to become of greater specific gravity, and more coloured; it is here that those depositions are apt to take place which constitute calculi; although we meet with them in the kid- neys and ureters also. As in every excretion, a sensation first arises, in consequence of which the muscles required for the ejection of the secreted matter are called into action. This sensation arises whenever the urine has accumulated to the necessary extent, or when it possesses irri- tating qualities, owing to extraneous substances being contained in, or deposited from it; or if the bladder be unusually irritable from any morbid cause, the sensation may be repeatedly—nay, almost incessantly—experienced. The remarks that have been made on the sensations accompanying the other excretions, are equally appli- cable here. The impression takes place in the bladder; such im- pression is conveyed to the brain, which accomplishes the sensa- tion ; and, consecutively, the muscles, concerned in the excretion, are called into action by volition. Physiologists have differed regarding the power of volition over the bladder. Some have affirmed that it is as much under cerebral control as the muscles of locomotion; and they have urged, in sup- port of this view, that the bladder receives spinal nerves, which are voluntary; that it is paralysed in affections of the spinal marrow, like the muscles of the limbs: and that a sensation, which seems destined to arouse the will, is always the precursor of its action. * Precis, &c. edit. cit. ii. 473. b British Annals of Medicine, p. 6. Jan. 1837. GLANDULAR—OF THE URINE. 307 Others again have denied, that the muscular fibres of the bladder are contractile under the will; and they adduce the case of other reservoirs,—the stomach and the rectum, for example,—whose in- fluence in excretion we have seen to be involuntary; as well as the fact that we no more feel the contraction of the bladder than we do that of the stomach or intestines; and they affirm, that the action of the bladder itself has been confounded with that of the accessory muscles, which are manifestly under the influence of the will, and are important agents in the expulsion of the fluid from the bladder. The views, last expressed, appear to be most accurate, and the catenation of phenomena seems to be as follows:—the sensation to expel the urine arises; the abdominal muscles are thrown into con- traction by volition; the viscera are thus pressed down upon the pelvis; the muscular coat of the bladder, is at the same time, stimu- lated to contraction; the levatores ani and the sphincter fibres are relaxed, so that the resistance of the neck of the organ is diminished, and the urine is forced out through the whole extent of the urethra, being aided in its course, especially towards the termination, by the contractile action of the urethra itself, as well as by the levatores ani and acceleratores urinae muscles. These expel the last drops by giving a slight succussion to the organ, and directing it upwards and forwards ; an effect which is aided by shaking the organ to free it from the drops that may exist in the part of the canal near its extremity. The gradually diminishing jet, which we notice, as the bladder is becoming empty, indicates the contraction of the muscu- lar coat of the organ; whilst the kind of intermittent jet, coincident with voluntary muscular exertion, indicates the contraction of the urethral muscles. When we feel the inclination to evacuate the bladder, and do not wish to obey it, the same muscles,—the leva- tores ani, the acceleratores urinae, and the fibres around the mem- branous portion of the urethra and the neck of the bladder—are thrown into contraction, and resist that of the bladder. Such is the ordinary mechanism of the excretion of urine. The contraction of the bladder is, however, of itself sufficient to expel its contents. Magendiea affirms, that he has frequently seen dogs pass urine when the abdomen was opened, and the bladder removed from the influence of the abdominal muscles; and he farther states, that if, in a male dog, the bladder, with the prostate and a small portion of the membranous part of the urethra, be removed from the body, the bladder will contract after a few moments, and pro- ject the urine, with an evident jet, until it is entirely expelled. Urine—voided in the morning by a person who has eaten heartily, and taken no more fluid than sufficient to allay thirst—is a transpa- rent, limpid fluid, of an amber colour, saline taste, and a peculiar odour. Its specific gravity is estimated by Chossat at from 1.001 to 1.038; by Cruikshank,'from 1.005 to 1.033; by Prout, from a Precis, ii. 474. 308 SECRETION. 1.010 to 1.015; by Gregory, from 1.005 to 1.033;' by Christison,b on the average, 1.024 or 1.025; by F. D'Arcet, from 1.001 to 1.060 !c by Rayer,d on the average, 1.018; and by Dr. Bostock and Martin Solon,6 1.020; by Elliotson,1" from 1.015 to 1.025; and Dr. Thos. Thomson5 found it in an individual, from 50 to 60 years of age and in perfect health, to be, on the average, 1.013; the lowest specific gravity, during ten days, being 1.004; and the highest, 1.026. Dr. Thomson has published some tables'1 showing the quantity of urine passed at different times during ten days by the individual in question, and the specific gravity of each portion. These tables do not accord with the opinion generally entertained, that the heaviest urine is voided on rising in the morning. No generalization can, indeed, be made on this subject. The tempera- ture of the urine when recently voided, varied in one case from 92° to 95°. It is slightly acid, for it reddens vegetable blues. Although at first quite transparent, it deposits an insoluble matter on standing; so that urine, passed at bed-time, is found to have a light cloud floating in it by the following morning. This substance consists, in part, of mucus from the urinary passages; and, in part, of the super-urate of ammonia, which is much more soluble in warm than in cold water. The urine is extremely prone to decomposition. When kept for a few days, it acquires a strong smell, which, being sui generis, has been called urinous; and as the decomposition proceeds, the odour becomes extremely disagreeable. The urine, as soon as these changes commence, ceases to have an acid reaction, and the earthy phosphates are deposited. In a short time, a free alkali makes its appearance; and a large quantity of the carbonate of ammonia is generated. These phenomena are owing to the decomposition of urea, which is almost wholly resolved into carbonate of ammonia. Dr. Henry1 affirms, that the following substances have been satis- factorily proved to exist in healthy urine,—water, free phosphoric acid, phosphate of lime, phosphate of magnesia, fluoric acid, uric acid, benzoic acid, lactic acid, urea, gelatine, albumen, lactate of ammonia, sulphate of potassa, sulphate of soda, fluate of lime, muriate of soda, phosphate of soda, phosphate of ammonia, sulphur, and silex. One of the most recent and elaborate analyses has been given by Berzelius.-1' He states it to consist—in 1000 parts, of water, 933.00; urea, 30.10; sulphate of potassa, 3.71; sulphate of soda, 3.16; phosphate of soda, 2.94; muriate of soda, 4.45; phos- a Burdach, Die Physiologie als Erfahrungswissenschaft. v. 271, Leipz. 1835. b On Granular Degeneration of the Kidneys, p. 34, Edinb. 1839; and Dunglison's American Med. Library Edit., Philad. 1839. c L'Experience, No. Iv., Aug. 1838. d Traite des Maladies des Reins, &c, torn, i., Paris, 1839. e De PAlbuminurie, ou Hydropisie Causee par Maladie des Reins, Paris, 1838. f Human Physiology, p. 293, Lond. 1835. s British Annals of Medicine, p. 5, Jan. 1837. b Op. citat. p. 6. 1 Elements of Experimental Chemistry, vol. ii. ) Med. Chirurgical Transact, vol. iii.; and Annals of Philos. ii. 423. GLANDULAR—OF THE URINE. 309 phate of ammonia 1.65; muriate of ammonia, 1.50; free lactic acid, lactate of ammonia, animal matter, soluble in alcohol, and urea not separable from the preceding, 17.14; earthy phosphates, with a trace of fluate of lime, 1.00; lithic acid, 1.00; mucus of the bladder, 0.32; silex, 0.03. Dr. Prouf found 100 parts to consist of lithic acid, 90.16; potassa, 3.45; ammonia, 1.70; sulphate of potassa, with a trace of muriate of soda, .95; phosphate of lime, carbonate of lime, and magnesia, .80; and animal matter, consist- ing of mucus and a little colouring matter, 2.94.b M. Raspail0 thinks it " possible" that uric acid is merely a mix- ture of organic matter (albumen) with an acid cyanide of mercury; so that the results of analysis may differ according as the analyzed substances may have been more or less separated from the organic matter. The physical and chemical characters of uric acid, he thinks, accord very well with this hypothesis. The yellowish-red incrustation, deposited on the sides of chamber utensils, is the uric or lithic acid. This is the basis of one of the varieties of calculi. The quantity of urine, passed in the twenty-four hours, is very variable. Boissier states it at 22 ounces; Hartmann at 28; Dr. Robt. Willisd at from 30 to 40; Prout at 32; Robinson at 35; Von Gorter at 36 ; Keill at 38; Rye at 39; Bostock at 40; Sanctorius at 44; Stark at 46; Dalton at 48^; Haller at 49; Christison at from 35 to 50; Dr. Thomas Thomson at 53; and Lining at from 56 to 59 ounces.8 On the average, it may be estimated at perhaps two pounds and a half; hence the cause of the great size of the renal artery, which, according to the estimate of Haller, conveys to the kidney a sixth or eighth part of the whole blood. Its quantity and character vary according to age, and, to a certain extent, according to sex. We have already seen, under the head of cuta- neous exhalation, how it varies, according to climate and season; and it is influenced by the serous, pulmonary, and cellular exhala- tions likewise: one of the almost invariable concomitants of dropsy is diminution of the renal secretion. Its character, too, is modified by the nature of the substances received into ihe blood. Rhubarb, turpentine, and asparagus materially alter its physical properties; whilst certain articles stimulate the kidney to augmented secretion, or are diuretics. The urine does not appear to be intended for any local function. Its use seems to be restricted to the removal of the elements of the a Annals of Philos. v. 415. See, also, an analysis by Prof. Thomas Thomson, in Records of General Science, ii. 3. b For the appearances presented by the urine under the microscope, see Quevenne, Vigla, I'Experience, Dec. 1837, Janvier, 1838, & Mars, 1838; Donne, ibid. Janvier, 1838; and for some new researches on Human Urine, see Lecanu, Journal de Phar- macie, Nov. &. Dec. 1839. See, also, art. Harn (Chemisch), Encyclopad. Worterbuch der Medicin. Wissensch., B. xv. s. 465, Berlin, 1837. c Op. citat, p. 507. d Urinary Diseases and their Treatment, Bell's Library Edit. p. 14, Philad. 1839. e Burdach, op. citat. v. 271. 310 SECRETION. substances, of which it is composed, from the blood; hence, it is solely depuratory and decomposing. How this decomposition is accomplished we know not. We have already referred to the ex- periments, performed by MM. Prevost and Dumas, Segalas, Gmelin, Tiedemann and Mitscherlich, in which urea was found in the blood of animals whose kidneys had been extirpated ; an inquiry has con- sequently arisen,—how it exists there? Prior to these experiments, ,it was universally believed, that its formation is one of the myste- rious functions executed in the intimate tissue of the kidney.a It is proper to add, however, that neither Prevost and Dumas, Tiedemann and Gmelin nor M. Lecanub could detect the smallest trace of urea in the blood of animals placed under ordinary circumstances. Urea, which, according to Wohler, is a cyanide of ammonia, contains a very large proportion of azote, so that, it has been ima- gined, the kidney may possibly be the outlet for an excess of azote, or for preventing its accumulation in the system,—in the same manner as the lungs and liver have been regarded as outlets for superfluous carbon. The quantity of azote, discharged in the form of urea, is so great, even in those animals whose food does not essentially contain this element, that it has been conceived a neces- sary ingredient in the nutrition of parts, and especially in the forma- tion of fibrine, which, wre have seen, is a chief constituent of the blood, and of every muscular organ. The remarks, made on the absorption of azote during respiration, indicate how it is received into the system; and it has been presumed, that the superfluous por- tion is thrown off in the form of urea. The experiments of MM. Prevost and Dumas, and of the other physiologists, would certainly favour the conclusion, that urea may exist ready formed in the blood, and that the great function of the kidney may be to separate it along with the other constituents of the urine. Adelon0 ascribes the source of the urea to the products of inter- stitial decomposition. He conceives, that, in this shape, they are received into the blood, and that the office of the kidneys is to sepa- rate them. All this is necessarily conjectural, and it must be ad- mitted, that our knowledge of the subject is by no means ample, and that we must wait for farther developements. Certain it is, that the removal of the constituents of the urinary secretion from the blood is all-important. Experiments on animals have shown, that if it be suppressed by any cause for about three days, death usually super- venes, and the dangers to man are equally imminent. Yet there are some strange cases of protracted suppression on record. Haller mentions a case in which no urine had been secreted for twenty-two weeks; and Dr. Richardson*1 one of a lad of seventeen, who had never made any and yet felt no inconvenience. a Annales de Chimie, xliii. 64, and Raspail's Chimie Organique, p. 506. b Etudes Chimiques sur le Sang Humain, Paris, 1837. c Physiologie de I'Homme, torn, iii., Paris, 1829. d Philos. Transact, for 1713; and 'Elliotson's Blumenbach's Physiology, 4th edit. Lond. 1828. ' 5 CONNEXION BETWEEN STOMACH AND KIDNEYS. 3H a. Connexion between the Stomach and the Kidneys. In consequence of the rapidity with which fluids, received into the stomach, are sometimes voided by the urinary organs, it has been imagined, either that vessels exist, which communicate directly between the stomach and bladder, or that the fluid passes through the intermediate cellular tissue, or by means of the anastomoses of the lymphatics. In support of the opinion, that a more direct passage exists, the assertion of Chirac,—that he saw the urinary bladder become filled with urine, when the ureters were tied, and that he excited urinous vomiting, by tying the renal arteries, is adduced. It has been farther affirmed, that the oil, composing a glyster, has been found in the bladder. Darwin," having administered to a friend a few grains of nitrate of potassa, collected his urine at the expiration of half an hour, and had him bled. The salt was detected in the urine, but not in the blood. Brande made similar experiments with the prus- siate of potassa, from which he inferred, that the circulation is not the only medium of communication between the stomach and the urinary organs, without, however, indicating the nature of the sup- posed medium; and this view is embraced by Sir Everard Home,b Wollaston, Marcet, and others. Lippi,c of Florence, thinks he has found an anatomical explanation of the fact. According to him, the chyliferous vessels have not only numerous inosculations with the mesenteric veins, either before their entrance into the mesenteric glands, or whilst they traverse the glands ; but, when they attain the last of those glands, some of them proceed to open directly into the renal veins, and into the pelves of the kidneys. At this place, according to him, the chyliferous vessels divide into two sets; the one, ascending, and conveying the chyle into the thoracic duct; the other, descending and carrying the drinks into the renal veins and pelves of the kidneys. He affirms, that the distinction between these two sets is so marked, that an injection, sent into the former, goes exclusively into the thoracic duct, whilst if it be thrown into the latter it passes exclusively to the kidneys. These direct vessels Lippi calls vasa chylopoietica urinifera. If the assertions of Lippi were anatomical facts, it would ob- viously be difficult to doubt some of the deductions; other anatomists have not, however, been so fortunate as he; and, consequently, it may be well to make a few comments. Some of these chylopoietica urinifera, he affirms, open into the renal veins. This arrangement, it is obvious, cannot be invoked to account for the shorter route,— the royal road to the kidney : the renal vessel is conveying the blood * Zoonomia, xxix. 3. b Philosophical Transactions, xcviii. 51, and ci. 163, for 1808 and 1811 ; and Lec- tures on Comparative Anatomy, i. 221, Lond. 1814; and iii. 138, Lond. 1823. c Illustrazioni Fisiologiche e Patologice del Sistema Linfatico-Chilifero, &c. Firenz. 312 SECRETION. back from the kidney, and every thing that reaches it from the intestines, must necessarily pass into the vena cava, and ultimately attain the kidney through the renal artery. The vessels, therefore, that end in the renal veins, must be put entirely out of the question, so far as regards the topic of dispute; and our attention be concen- trated upon those that terminate in the pelvis of the kidney. Were this termination proved, we should be compelled, as we have remarked, to bow to authority; but not having been so, it may be stated as seemingly improbable, that the ducts in question should take the circuitous course to the pelvis of the kidney, instead of proceeding directly to the bladder. We know then, anatomically, nothing of any canal existing between the stomach and the bladder; and we have not the slightest evidence,—positive or relative,—in favour of the opinion, that there is any transmission of fluid through the intermediate cellular tissue. We have, indeed, absolute testimony against it. MM. Tiedemann and Gmelin, having examined the lymphatics and cellular tissue of the abdomen, in cases where they had administered indigo and essence of turpentine to animals, discovered no traces whatever of them, whilst they could be detected in the kidney. The facts, again, refered to by Chirac, are doubtful. If the renal arteries be tied, the secretion cannot be effected by the kidney; yet, as we have seen, in the case of extirpated kidneys, urea may exist in the blood, and, consequently, urinous vomitings be possible. If the ureters be tied, the secretion being practicable, death will occur if the suppression be protracted; and, in such case, the secreted fluid may pass into the vessels, and readily give a urinous character to the perspiration, vomited matters, &c. &c. The experiments of Darwin, Brande, Wollaston, and others only demonstrate, that these gentlemen were unable to detect in the blood that which they found in the urine. Against the negative results attained by these gentlemen, we may adduce the positive testimony of Fodera," an experimentalist of weight, especially on those mat- ters. He introduced into the bladder of a rabbit a plugged catheter, and tied the penis upon the instrument to prevent the urine from flowing along its sides. He then injected into the stomach a solu- tion of the ferrocyanate of potassa. This being done, he frequently removed the plug of the catheter, and received the drops of urine on filtering paper: as soon as indications of the presence of the salt appeared in the urine by the appropriate tests,—which usually required from five to ten minutes after its reception into the stomach, —the animal was killed; and, on examining the blood, the salt was found in the serum taken from the thoracic portion of the vena cava inferior, in the right and left cavities of the heart, in the aorta, the thoracic duct, the mesenteric glands, the kidneys, the joints, and in the mucous membrane of the bronchi. Magendie,b too, states, as the result of his experiments,—First. a Recherches Experimentales sur 1'Absorption et PExhalation, Paris, 1824. b Precis, &c. ii. 477. GLANDIFORM GANGLIONS. 313 That whenever prussiate of potassa is injected into the veins, or is exposed to absorption in the intestinal canal, or in a serous cavity, it speedily passes into the bladder, where it can be readily recog- nised in the urine. Secondly. That if the quantity of prussiate injected be considerable, it can be detected in the blood by reagents; but if the quantity be small, it is impossible to discover it by the ordinary means. Thirdly. That the same thing happens if the prus- siate of potassa be mixed with the blood out of the body. Fourthly. That the salt can be detected, in every proportion, in the urine. We may conclude, therefore, with Dr. Hale," who has written an interesting paper on this subject, that the existence of any more direct route from the stomach to the bladder than the circulatory system and the kidneys is disproved; and the absorption of fluids must be considered to be effected through the vessels described under the Absorption of Drinks. Such are the glandular secretions, which we shall consider in this place. There are still two important fluids, the sperm and the milk, whose uses will have to be detailed under the next class of functions. GLANDIFORM GANGLIOXS. There are several organs,—as the spleen, thyroid, thymus, and supra-renal capsules,—which are termed glands by many anato- mists; but which Chaussier has termed glandiform ganglions. Of the uses of these we know little or nothing. Yet it is necessary, that the nature of the organs, and their fancied functions should meet with notice. The offices of the thyroid, thymus, and supra-renal capsules,—being chiefly confined to foetal existence,—will not require consideration here. a. The Spleen. The spleen is a viscus of considerable size, situate in the left hypochondriac region, (Fig. 138, H,) beneath the diaphragm, above the left kidney, and to the left of the stomach. Its medium length is about four and a half inches; its thickness two and a half inches ; and its weight about eight ounces.b It is of a soft texture, somewhat spongy to the feel, and easily torn. In a very recent subject, it is of a grayish-blue colour; which, in a few hours, changes to a purple, so that it resembles a mass of clotted blood. At its inner surface, or that which faces the stomach and kidney, a fissure exists, by which the vessels, nerves, &c. enter or issue from the organ. The anatomical elements of the spleen are:—1. The splenic * Dissertation on the Question :—Is there any communication from the Stomach to the Bladder more direct than through the Circulatory System and the Kidneys ? In Boylston Prize Dissertations for the years 1819 and 1821, Boston, 1821. b Dr. Gross, Elements of Pathological Anatomy, ii. 344, Boston, 1839. VOL. II. 27 314 GLANDIFORxM GANGLIONS. artery, which arises from the cceliac, and after having given off branches to the pancreas and the left gastro-epiploic artery, divides into several branches, which enter the spleen at the fissure, and ramify in the tissue of the organ, so that it seems to be exclusively formed by them. (Fig. 113.) Whilst the branches of the artery are still in the duplicature of the gastro-splenic omentum, and before they ramify in the spleen, they furnish the vasa brevia to the sto- mach. The precise mode of termination of the arteries in the spleen is unknown. The communication of the arteries with the veins does not, however, appear to be as free as in other parts of the body, or the anastomoses between the minute arteries as numerous. If, according to Assolant," one of the branches of the splenic artery be tied, the portion of the spleen to which it is distributed dies; and if air be injected into one of these branches, it does not pass into the others; so that the spleen would appear to be a con- geries of several distinct lobes; and in certain animals the lobes are so separated as to constitute several spleens. A similar appearance is occasionally seen in the human subject. 2. The splenic vein arises by numerous radicles in the tissue of the spleen: these be- come gradually larger, and less numerous, and leave the fissure of the spleen by three or four trunks, which ultimately, with veins from the stomach and pancreas, unite to form one, that opens into the vena portae. It is without valves, and its parietes are thin. These are the chief constituents. 3. Lymphatic vessels, which are large and numerous. 4. Nerves, proceeding from the cceliac plexus: they creep along the coats of the splenic artery,—upon which they form an intricate plexus,—into the substance of the spleen. 5. Cellular tissue, which serves as a bond of union be- tween these various parts; but is in extremely small quantity. 6. A proper membrane, which envelopes the organ externally; adheres closely to it, and furnishes fibrous sheaths to the ramifications of the artery and vein; keeping the ramifications separated from the tissue of the organ, and sending prolongations into the parenchyma, which give it more of a reticulated than spongy aspect. 7. Of blood, according to many anatomists, but blood differing from that of both the splenic artery and vein ; containing, according to Vauquelin, less colouring matter and fibrine, and more albumen and gelatine, than any other kind of blood. This, by stagnating in the organ, is con- ceived to form an integrant part of it. Malpighib believed it to be contained in cells; but others have supposed it to be situate in a capillary system intermediate to the splenic artery and vein.c Assolant and Meckeld believe, that the blood is in a peculiar state of combination and of intimate union with the other organic elements of the viscus, and with a large quantity of albumen; and that this a Recherches sur la Rate, Paris, 1801. b Op. Omnia, part ii. Lond. 1687; and Op. Posthum. p. 42, Lond. 1697. c Seiler, in art. Milz, in Pierer's Anat. Physiol. Worterbuch, B. v. s. 322, Altenburg, 1832. <* Handbuch, &c. traduit par Meckel et Jourdan, iii. 476, Paris, 1825. THE SPLEEN. 315 combination of the blood forms the dark brown pulpy substance, contained in the cells formed by the proper coat, and which can be easily demonstrated bv tearing or cutting the spleen and scraping it with the handle of a knife. These cells and the character of the tissue of the spleen are exhibited in the marginal figure, (b ig. M.) In addition to the pulp, many anato- mists assert, that they have met i»ff. 142. with an abundance of rounded cor- puscles, varying in size from an almost imperceptible magnitude to a line or more in diameter. By Malpighi, these were conceived to be granular corpuscles, and, by Ruysch,3 simply convoluted vessels. Andralb affirms, that by repeated washings, the spleen is shown to consist of an infinite number of cells, which communicate on the one hand together, and, on the other, directly with the splenic veins. The latter, when the inner surface of the large subdivisions of the sple- nic veins are examined, appear to have a great number of perforations, through which a probe passes direct- ly into the cells of the organ. The farther the subdivisions of the vein examined are from the trunk, the section of the sPieen. larger are these perforations, and still farther on, the coats of the vein are not a continued surface, but are split into filaments, which do not differ from those forming the cells, and are continuous with them.c Besides the proper membrane, the spleen also receives a peritoneal coat; and, between the stomach and the organ, the peritoneum forms the gastro-splenic epiploon or gastro-splenic ligament, in the duplicature of which are situate the vasa brevia. Lastly: the spleen is capable of distension and contraction ; and is possessed of little sensibility in the healthy state. It has no ex- cretory duct. The hypotheses, which have been indulged on the nature of the spleen, are beyond measure numerous and visionary ;d and, after all, we are in the greatest obscurity as to its real uses. * Meckel, op. citat. b Precis, d'Anatomie Pathologique, torn. ii. part i. p. 416, Paris, 1832. c See, r_lso, Sir E. Home's Lectures on Comparative Anatomy, iii. 148 ; Dr. Warner on the Distribution of the Splenic Vein, in the spleen of the ox and sheep, in American Journal of the Med. Sciences, Feb. 1836, p. 541; and Weber's Hildebrandt's Handbuch der Anatomie, u. s. w. Band iv. s. 328, Braunschweig, 1822. d Seilcr, op. citat. v. 328. 316 GLANDIFORM GANGLIONS. Many of these hypotheses are too idle to merit notice; such are those, that consider it to be the seat of the soul,—the organ of dreaming,—of melancholy and of laughter,—of sleep and the vene- real appetite,—the organ that secretes the mucilaginous fluids of the joints, that serves as a warm fomentation to the stomach, and so on. It was long regarded as a secretory apparatus, for the formation of the atrabilis,—of a fluid intended to nourish the nerves,—of the gastric juice,—of a humour intended to temper the alkaline cha- racter of the chyle or bile, &c. The absence of an excretory duct would be a sufficient answer to all these speculations, if the non- existence of the supposititious humours were insufficient to exhibit their absurdity. MM. Tiedemann and Gmelina consider its functions to be iden- tical with those of the mesenteric glands. They regard it as a ganglion of the absorbent system, which prepares a fluid to be mixed with the chyle and effect its animalization. In favour of the view, that it is a part of the lymphatic system, they remark, that it exists only in those animals that have a distinct absorbent system ; that its bulk is in a ratio with the developement of the absorbent system; that the lymphatics predominate in the structure of the organ; that its texture is like that of the lymphatic ganglions; and lastly, that, on dissecting a turtle, they distinctly saw all the lymphatics of the abdomen passing first to the spleen, then leaving that organ of larger size, and proceeding to the thoracic duct. In support of their second position, that it furnishes some material towards the animalization of the chyle, they adduce;—the large size of the splenic artery, which manifestly, they conceive, carries more blood to the spleen than is needed for its nutrition; and they affirm, that, in their experiments, they have frequently found, whilst digestion and chylosis were going on, the lymphatic vessels of the spleen gorged with a reddish fluid, which was carried by them into the thoracic duct, where the chyle always has the most- rosy hue; and they add, that a substance injected into the splenic artery, passes readily into the lymphatics of the spleen. Lastly, after extir- pating the spleen in animals, the chyle appeared to them to be more transparent; no longer depositing coagula; and the lymphatic gan- glions of the abdomen seemed to have augmented in size. Views, similar to these, have been maintained by Sir Everard Home.b Chaussier, as we have seen, classes the spleen amongst the glandi- form ganglions, and affirms that a fluid is exhaled into its interior of a serous or sanguineous character, which, when absorbed, assists in lymphosis. Many, again, have believed, that the spleen is a sanguineous, not a lymphatic ganglion, but they have differed regardinglhe blood on which it exerts its action; some maintaining, that it prepares the » Versuche iiber die Wege auf welchen Substanzen aus dem Magen und Darmkanal ins Blut gelangen, p. 86, Heidelb. 1820. b Philosoph. Transactions for 1S08 and 1811; and Lect. onComp. Anatomy, loc. cit. THE SPLEEN. 317 blood for the secretion of the gastric juice; others, for that of the bile. The former of these views is at once repelled by the fact, that the vessels which pass from the splenic artery to the stomach, leave that vessel before it enters the spleen. The latter has been urged, of late, by M. Voisin.a He thinks, the principal use of the spleen is to furnish to the liver, blood containing those materials that enter into the composition of the bile; but this view, also, rests on very uncertain data and deductions. Since the period of Haller, the blood of the splenic vein has been presumed to differ essentially from that of other veins, which has led to the belief, that some elaboration is effected in the spleen so as to fit the blood for the secretion of the bile. It has been described as more aqueous, more albuminous, more unctuous, and blacker than other venous blood; to be less coagulable, less rich in fibrine, and the fibrine it does contain to be less animalized. Yet these affirma- tions have been denied; and even were they admitted, we have no positive knowledge, that such changes better adapt it for the forma- tion of bile by the liver. The ideas that have existed, regarding its acting as a diverticulum for the blood, have been mentioned under the head of Circulation. By some, it has been supposed to act as such in the intervals of digestion ;b or, in other words, to be a diverticulum to the stomach : by others, its agency in this way is believed to apply to the whole circulatory system, so that when the flow of blood is impeded or arrested in other parts, it may be received into the spleen. Such a view was entertained by Dr. Rush.c It is hard to say which of these speculations is the most ingenious. None can satisfy the judicious physiologist, especially when he con- siders the comparative impunity consequent on extirpation of the organ. This was an operation performed at an early period. Pliny affirms that it was practised on runners to render them more swift. From animals the spleen has been repeatedly removed, and although many of these have died in consequence of the operation, several have recovered.*1 Adelon6 refers to the case of a man who was wounded by a knife under the last false rib of the left side. Surgical attendance was not had until twelve hours afterwards; and, as the spleen had issued at the wound, and was much altered, it was considered necessary to extirpate it. The vessels were tied; the man got well in less than two months, and has ever since enjoyed good health. Sir Charles Bellf asserts, that an old pupil had given him an » Nouvel Apercu sur la Physiologie du Foie, et les Usages de la Bile, Paris, 1833. b Dr. W. Stukely, Of the Spleen, its Description and History, Uses and Diseases &c, Lond. 1722. c Coxe's Medical Museum, Philad. 1807; art. Milz. in Pierer's op. cit. s. 328- and Mr. Hake, Proceedings of the Royal Society, No. 39, June 20,1839. d J. H. Schulze, de Splene Canibus Exciso, Hal. 1735; Morgagni, Animad. Anat. iii. Animad. xxv. Lugd. Bat. 1741. e Physiol, de I'Homme, 2de tun)s upwards> and obtains the name of vas deferens. The testes of most animals, that procreate but once a year, are 143. * Elements of the Anat. of the Human Body, by Monro, tertius, ii. 179, Edinb. 1825. GENERATIVE APPARATUS—MALE. 331 comparatively small during the months when they are not excited. In man, the organ before birth, or rather during the greater part of gestation, is an abdominal viscus; but, about the seventh month of foetal existence, it gradually descends through the abdominal ring into the scrotum, which it reaches in the eighth month, by a me- chanism to be described hereafter. In some cases, it never descends, but remains in the cavity of the abdomen, giving rise to considera- ble mental distress in- many instances, and exciting the idea, that there may be a total absence of the organs, or that if they exist, they cannot effect the work of reproduction. The uneasiness is needless, the descent appearing to be by no means essential. It has been sufficiently demonstrated that individuals, so circumstanced, are capable of procreation. In many animals, the testicles are always internal; whilst, in some, they appear only in the scrotum during the season of amorous excitement. Fodera has indeed as- serted, that the crypsorchides, or those whose testes have not de- scended, are occasionally remarked for the possession of unusual prolific powers and sexual vigour.* It appears, that there is a set of barbarians at the back of the Cape of Good Hope, who are generally possessed of but one testicle, or are monorchides; and Linnaeus, under the belief that this is a natural defect, has made them a distinct variety of the human species. Mr. Barrow has noticed the same singularity; but Dr. Goodb thinks it doubtful, whether, like the want of beard amongst the American savages, the destitution may not be owing to a barbarous custom of extirpation in early life. The deviation is not, however, more singu- lar than the unusual formation of the nates and of the genital organs of the female in certain people of these regions, to which we shall have to refer. The possession of a single testicle appears to be sufficient for procreation. At times, the testicles are extremely small, but capable of exe- cuting all their functions. Mr. Wilson0 was consulted by a gentle- man, on the point of marriage, respecting the propriety of his entering into that state, whose penis and testicles very little exceeded in size those of a youth of eight years of age. He was twenty-six years old, but had never experienced sexual desire until he became acquainted with the lady whom he proposed to make his wife; after which he had repeated erections, with noc- turnal emissions. He married; became the father of a family; and when he was twenty-eight years old, the organs had increased to the usual size of those of the adult. In certain cases, the testes are drawn up against the abdominal * "Ces organes paraissant tirer du bain chaud ou ils se trouvent plong6s plus d'apti- tude a la secretion que lorsqu'ils sont descendus au dehors dans leurs enveloppes ordi- naires!"—Traite de Mddecine Ligale, i. 370, Paris, 1813. b Physiological Proem to class Genetica, Study of Medicine, vol. iv. c Lectures on the Structure and Physiology of the Male Urinary and Genital Organs, &c. Lond. 1821. 332 GENERATION. ring so as to encourage the idea, that there are no testes in the scrotum, and Professor Gross* has given the cases of two boys, one fourteen, the other eleven years of age, who were said to have been castrated, and a medical practitioner deposed to the absence of the testes; which, however, were found to be situate in the groin, a little below the external ring, whence, by a little traction, they could be easily forced down into the scrotum. The testicle is connected with the abdominal ring by means of the spermatic cord, a fasciculus of about half an inch in diameter, which can be readily felt through the skin of the scrotum. It is formed, essentially of the vessels and nerves that pass to or from the testicle;—the spermatic artery, spermatic veins, lymphatics and nerves of the organ, and the vas deferens, or excretory duct. These are bound together by means of cellular tissue; and, externally, a membranous sheath of a fibrous character envelopes the cord, and keeps it distinct from the surrounding parts, and especially from the scrotum. When the cord has passed through the abdominal ring, its various elements are no longer held together, but each passes to its particular destination. The scrotum or purse is a continuation of the skin of the inner side of the thighs, the perineum, and the penis. It is symmetrical, the two halves being separated by a median line or raphe. The skin is of a darker colour here than elsewhere; is rugous, studded with follicles, and sparingly furnished with hair. This may be considered its outermost coat. Beneath this is the dartos,—a reddish, cellular membrane, which forms a distinct sac for each testicle; and a sep- tum—the septum scroti—between them. Much discussion has taken place regarding the nature of this envelope; some supposing it to be muscular, others cellular. Breschet and Lobstein affirm, that it does not exist in the scrotum before the descent of the testes, and they consider it to be formed by the expansion of the gubernaculum testis. Meckel, however, suggests, that it constitutes the transition between the cellular and muscular tissues, and that there exists between it and other muscles the same relation that there is between the muscles of the superior and inferior animals. It consists of long fibres considerably matted together, and passing in every direction, but which are easily separable by distension with air or water, and by slight maceration.1" The generality of anatomists conceive it to be of a cellular character, yet it is manifestly contractile, corrugates the scrotum, and probably consists of muscular tissue also. Dr. Horner,0 indeed, affirms that he dissected a subject in January, 1830, in which the fibres were evidently muscular, although interwoven. Beneath the dartos a third coat exists, which is muscular:—it is called the cremasler or tunica erythroiaes. It arises from the lesser » Western Journal of Medicine and Surgery, May, 1841, p. 355. b Meckel's Handbuch, u. s. w., Jourdan's French translation, iii. 622, Paris, 1825, and Weber's Hildebrandt's Handbuch der Anatomie, iv. 382, Braunschweig, 1832. c Special and General Anat., 5th edit, p. 94, Philad. 1839, and Lessons on Practical Anatomy, 3d edit. p. 273, Philad. 1836. GENERATIVE APPARATUS—MALE. 333 oblique muscle of the abdomen, passes through the abdominal ring, aids in the formation of the spermatic cord, and terminates insen- sibly on the inner surface of the scrotum. It draws the testicle upwards. The cellular substance, that connects the dartos and cremaster with the tunica vaginalis, has been considered by some as an addi- tional coat, and termed tunica vaginalis communis. The tunica vaginalis or tunica elytrotdes is a true serous mem- brane, enveloping the testicle and lining the scrotum; having, conse- quently, a scrotal and a testicular portion. We shall see, hereafter, that it is a dependence of the peritoneum, passing before the testicle in its descent, and afterwards becoming separated from any direct communication with the abdomen. The vas deferens or excretory duct of the testicle commences at the globus minor of the epididymis, (C, Fig. 143,) which is itself, we have seen, formed of a convoluted tube. This, when unfolded, according to Monro, measures as much as thirty-two feet. As soon as the vas deferens quits the testicle, it joins the spermatic cord, passes upwards to the abdominal ring, separates from the blood- vessels on entering the abdomen, and descends downwards and inwards to the posterior and inferior part of the bladder, passing between the bas-fond of the latter and the ureter. It then converges towards its fellow along the under extremity of the bladder, at the inner margin of the vesicula seminalis of the same side, and ulti- mately opens into the urethra near the neck of the bladder. (Fig. 140.) At the base of the prostate, it receives a canal from the vesicula, and continues its course to the urethra under the name of ejaculatory duct. The vas deferens has two coats, the outermost of which is very firm and almost cartilaginous; but its structure is not manifest. The inner coat is thin, and belongs to the class of mucous membranes. The vesicula seminales, E, Fig. 140, are considered to be two con- voluted tubes,—one on each side,— which are two inches or two inches and a half long, and six or seven lines broad at the fundus, and are situate at the lower fundus of the bladder, between it and the rectum and behind the prostate gland. At the anterior extremities they ap- proach each other very closely,being separated only by the vasa defe- rentia. When inflated and dried, they present the appearance of cells; but are generally conceived to be .1 l • l l • 1 » j___~ vesicula seminalis tubes, which, being convoluted, are toryduct. brought within the compass of the vesiculae. When dissected and stretched out, they are four or five Fig. 144. Section of the Vesicula Seminales, $c. V. Section of vas deferens. S. Section of Section of ejacula- 334 GENERATION. inches long by about one-fourth of an inch in diameter. Amussat,* however, denies this arrangement of the vesicula?: he affirms, that he has discovered them to be formed of a minute canal of consider- able length, variously convoluted, the folds of which are united to each other by cellular filaments, like those of the spermatic vessels. At the anterior part, termed the neck, a short canal passes off, which unites at an acute angle with the vas deferens, to form the ductus ejaculotorius. The vesicula? are formed of two membranes; the more external like that of the vas deferens, and capable of contracting in the act of ejaculation; and an internal lining, of a white, delicate character, a little like that which lines the interior of the gall-blad- der, and supposed to be mucous. Although the vesiculae are mani- festly contractile, no muscular fibres have been detected in them. They are found filled, in the dead body, with an.opaque, thick, yel- lowish fluid, very different, in appearance, from the sperm ejacu- lated during life. The prostate gland, (Fig. 140, D,) is an organ of very dense tissue, embracing the neck of the bladder, and penetrated by the urethra, which traverses it much nearer its upper than its lower surface. The base is directed backwards, the point forwards, and its inferior surface rests upon the rectum, so that, by passing the finger into the rectum, enlargements of the organ may be detected. The prostate was once universally esteemed glandular, and it is still so termed. It is, now, generally and correctly regarded as an ag- glomeration of several small follicles, filled by a viscid whitish fluid. These follicles have numerous minute excretory ducts, which open on each side of the caput gallinaginis. The glands of Cowper are two small, oblong bodies; of the size of a pea; of a reddish colour, and of a somewhat firm tissue. They are situate anterior to the prostate, parallel to each other, and at the sides of the urethra. Each has an excretory duct, which creeps obliquely in the spongy tissue of the bulb, and opens before the veru- montanum. The male organ or penis consists of the corpus cavernosum and corpus spongiosum; parts essentially formed of an erectile tissue, and surrounded by a very firm elastic covering, which prevents over-distension, and gives form to the organ. The corpora cavernosa constitute the great body of the penis. They are two tubes which are united and separated by an imper- fect partition. Within them a kind of cellular tissue exists, into which blood is poured, so as to cause erection. The posterior ex- tremities of these cavernous tubes are called crura penis. These separate in the perineum, each taking hold of the ramus of the pubis; and, at the other extremity, the cavernous bodies terminate in rounded points under the glans penis. The anatomical elements of the internal tissue of the corpora cavernosa, are,—the ramifica- tions of the cavernous artery, which proceeds from the internal 1 Magendie's Precis, &c. ii, 514. GENERATIVE APPARATUS-MALE. 335 pudic ; those of a vein bearing the same name; and probably, nerves, although they have not been traced so far. All these elements are supported by filamentous prolongations from the outer dense enve- lope. A difference of opinion prevails amongst anatomists with re- gard to the precise arrangement of these prolongations. Some con- sider them to form cells, or a kind of spongy structure, on the plates of which the ramifications of the cavernous artery and vein and of the nerves terminate, and into which the blood is extravasated. Others conceive, that the internal arrangement consists of a plexus of minute arteries and veins, supported by the plates of the outer membrane, interlacing like the capillary vessels, but with this addi- tion, that, in place of the minute veins becoming capillary in the plexus, they are of greater size, forming very extensible dilatations and networks, and anastomosing freely with each other. If the cavernous artery be injected, the matter first fills the ramifications of the artery, then the venous plexuses of the cavernous bodies, and it ultimately returns by the cavernous vein, having produced erec- tion. The same effect is caused still more readily by injecting the > cavernous vein. J. Miiller, who has recently investigated the struc- ture of the male organ, has discovered two sets of arteries in the organ differing from each other in size, mode of termination and uses: the first he calls Rami nutritii, which are distributed upon the parietes of the veins and throughout the spongy substance, dif- fering in no respecct from the nutritive arteries of other parts. The second set he calls arteria helicina. They differ from the nutritive vessels in form, size, and distribution. They are short and are given off from the larger branches as well as from the finest twigs of the artery: most of them come off at a right angle, and project into the cavity of the spongy substance, either terminating abruptly or swelling out into a clublike process without again subdividing. Almost all these arteries have this character, that they are bent like a horn, so that the end describes half a circle or somewhat more. These arteries have a great resemblance to the tendrils of the vine, whence their name—arteria helicina. A minute examination of them, either with the lens or with the microscope, shows that, although they at all times project into the venous cavi- ties of thee orpora cavernosa, they are not entirely naked, but are covered with a delicate membrane, which under the microscope appears granular.* The researches of Valentinb are not, however, in accordance with those of Muller. The result of numerous exa- minations has convinced him that the helicine arteries are not pecu- liar vessels, but merely minute arteries that have been divided or * For a farther description of these vessels, see, J. Muller, art. Erectiles Gewebe, Encycl. Worterbuch der Medic. Wissench. xi. 452, Berlin, 1834 ; Handbuch der Phy- siologie, u. s. w. Baly's translation, Lond. 1838; and Abhandlungen der Koniglich. Akademie der Wissenschaft. zu Berlin, s. 93, Berlin, 1837; also, Dr. Hart, in art. Erectile Tissue, in Cyclop. Anat. and Physiol, part x., p. 146, June, 1837. b Mailer's Arehiv. far Anatomie, u. s. w. and Lond. Med. Gazette, June 23, 1838, p. 543. 336 GENERATION. torn, and that the real distribution of the vessels of the corpora cavernosa follows in every respect the most simple laws. The researches of Muller have led him to infer, that, both in man and the horse, the nerves of the corpora cavernosa Are made Fig- 145 UP °^ Drancnes proceeding from the organic as well as the animal system, whilst the nerves of animal life alone provide the nerves of sensation of the penis.* Attached to the corpora cavernosa, and running in the groove beneath them, is a spongy body of simi- lar structure,—the corpus spongiosum urethra,—through which the urethra passes. It commences, posteriorly, at the bulb of the urethra,—already de- scribed under the Secretion of Urine,— and terminates anteriorly in the glans, which is, in no wise, a dependency of section of tte Penis. the corp0ra cavernosa, but is separated A. External membrane or sheath of r .i___l„ „ „„„»•„ „c (U/V;„ „.,lo, the penis, b. corpus cavemosum. d. from them by a portion of their outer corpus spongiosum urethra. membranes; so that erection may take place in the one, and not simultaneously in the other; and injections into the corpora cavernosa of the one do not pass into those of the other. The glans appears to be the final expansion of the erectile tissue which surrounds the urethra. The posterior circular margin of the glans is called the corona glandis, and behind this is a depres- sion termed the cervix, collum or neck. Several follicles exist here, called the glandula odorifera Tysoni, which secrete an unctuous humour called the smegma praputii, which often accumulates largely, where cleanliness is not attended to. The penis is covered by the skin, which forms, towards the glans, the prepuce or foreskin. The cellular tissue, which unites it to the organ is lax, and never contains fat. The inner lamina of the pre- puce being inserted circularly into the penis, some distance back from the point, the glans can generally be denuded, when the pre- puce is drawn back. The under and middle part of the prepuce is attached to the extremity of the glans by a duplicature, called the franum praputii, which extends to the orifice of the urethra. The skin is continued over the glans, but it is greatly modified in its structure, being smooth and velvety, highly delicate, sensible, and vascular. Lastly. In addition to the acceleratores urina, the transversus perinei, the sphincter ani, and the levator ani muscles, which we have described as equally concerned in the excretion of urine and semen, the erector penis or ischio-cavernosus muscle is largely con- nected with the function of generation. The genital organs of man • Lond. Med. Gazette, April 23d, 1836, and Abhandlung. u. s. w. s. 117. SPERM. 337 are, in reality, merely an apparatus, for a glandular secretion, of which the testicle is the gland; the vesiculae seminales are supposed to be the reservoirs; and the vas deferens and urethra the excretory ducts;—the arrangement which we observe in the penis being for the purpose of conveying the secreted fluid into the parts of the female. 1. SPERM. The sperm, sperma or semen is secreted by the testicles from the blood of the spermatic artery, by a mechanism, which is no more understood than that of secretion in general. When formed, it is received into the tubuli seminiferi, and passes along them to the epididymis, the vas deferens, and the vesiculae seminales, where it is generally conceived to be deposited, until it is projected into the urethra, under the venereal excitement. That this is its course is sufficiently evidenced by the arrangement of the excretory ducts, and by the function which the sperm has to fulfil. De Graaf," how- ever, adduces an additional proof. On tying the vas deferens of a dog, the testicle became swollen under excitement, and ultimately the vas deferens gave way between the testicle and the ligature. The 'causes of the progression of the sperm through the ducts are,—the continuity of the secretion by the testicle, and a contrac- tion of the excretory ducts themselves. These are the efficient agents. It has been a question with physiologists, whether the secretion of the sperm is constantly taking place, or whether, as the function of generation is accomplished at uncertain intervals, the secretion may not likewise be intermittent. It is impossible to arrive at any positive conclusion on this point. It would seem, however, unneces- sary for the secretion to be effected at all times; and it is more probable, that when the vesiculae seminales are emptied of their contents, during coition, a stimulus is given to the testes by the ex- citement, and they are soon replenished. This, however, is more and more difficult in proportion to the number of repetitions of the venereal act, as the secretion takes place at best but slowly. By some, the spermatic and pampiniform plexuses have been regarded as diverticula to the testes during this intermission of action. The sperm passes slowly along the excretory ducts of the testicle, owing partly to the slowness of the secretion, and partly to the ar- rangement of the ducts, which as we have seen, are remarkably convoluted, long, and minute. The use of the vesiculae seminales has been disputed. The ma- jority of physiologists regard them to be reservoirs for the sperm, and to serve the same purpose as the gall-bladder in the case of the bile. Others, however, have supposed, that they secrete a fluid of a peculiar nature, the use of which may probably be to dilute the * De Virorum Organ. Gener. Inserv., in Med. Oper. Omn. Amstel. 1705. vol. ii. 29 338 GENERATION. sperm, and others, again, infer, that they are both seminal reservoirs, and secreting organs, furnishing mucus, or perhaps some other fluid for admixture with the semen.* Dr. John Davy found spermatozoa in the fluid of the vesiculae, but except in two instances no animalcules could be seen in the fluid expressed from the divided substance of the testes. He inva- riably found, however, extremely minute, dense spherules, which he conjectures to be the ova of the spermatozoa.b They are manifestly not essential to the function of generation, as they do not exist in all animals. The dog and cat kind, the bear, opossum, sea-otter, seal, &c, possess them not; and there are several in which there is no direct communication between the duct and the vas deferens, which open separately into the urethra. This circumstance, however, with the fact, that they generally contain, after death, a fluid of different appearance and properties from those of the sperm,—with the glandular structure, which their coats seem to possess, in many instances,—is opposed to the view, that they are simple reservoirs for the semen, and favours that which ascribes to them a peculiar secretion. Where this commu- nication between the duct of the vesicles and the vas deferens exists, a reflux of the semen may take place, and an admixture between the sperm and the fluid secreted by them. It is not improbable, however, as Adelonc suggests, that all the excretory ducts of the testicle may act as a reservoir; and in the case of animals, in which the vesiculae are wanting, they must possess this office exclusively. If we are to adopt the description of Amussat as an anatomical fact, the vesiculae themselves are constituted of a convoluted tube, having an arrangement somewhat resembling that which prevails in the excretory ducts of the-testes.d That the excretory ducts of the testes may serve as reservoirs is proved by the fact, that impregnation is practicable after thorough castration. This has been doubted both as regards animals and man, but there is no question of the fact as regards the former.e The author's respectable friend, Dr. Pue, of Baltimore, related to him unquestionable instances of the kind. In one case, a boar was observed on one side of a hedge, striving to get at some sows in heat on the other side. The boar was castrated, and no inconve- nience being apprehended, he was turned loose into the field With the sows. In five minutes after the operation, he had intercourse with one of the sows, and subsequently with others. The first sow brought forth a litter, but none of the others were impregnated. In another case, after a horse had been castrated, it was recol- lected, that the male organ had not been washed—which, it seems, is looked upon as advisable. To save inconvenience, it was sug- a Dr. John Davy, in Edinb. Med. and Surg. Journ. for July, 1838, p. 12; and Re- searches, Physiological and Anatomical, Dunglison's Amer. Med. Libr. Edit. p. 363, Philad. 1840. *> Ibid. p. 373. c Physiologie de I'Homme, 2de edit. iv. 15, Paris, 1829. d Magendie's Precis, &c. ii. 348. e Varro, De Re Rustica, lib. ii. cap. 5. SPERM. 339 gested, that the same effect might be produced by putting him to a mare, then in the stable, and in heat. This was done, and, in due time, the mare brought forth a foal, unequivocally the result of this sexual union. Mr. Walton Hamilton,—a great breeder of horses, in Saratoga county, New York,—informed the author's friend, Mr. Nicholas P. Trist, United States consul at the Havana, that he, also, had known several instances of impregnation after castration.* It is to be presumed, that the power of procreation can exist for a short time only after the operation; yet a secretion may take place from the lining membrane of the ducts, and vesiculae, and from the prostate and other follicles, but this secretion cannot supply the place of the sperm. Sir A. Cooper gives the case of a man, who stated to him, that for nearly the first twelve months after complete castration, he had emissions in coitu, or the sensation of emissions. Afterwards, he had erections and intercourse at distant intervals, but without the sensation of emission.6 It has been asked, how does it happen, that the sperm, in its pro- gress along the vas deferens, does not pass directly on into the urethra by the ejaculatory duct, instead of reflowing into the sper- matic vesicles? This, it has been imagined, is owing to the exist- ence of an arrangement at the opening of the ejaculatory duct into the urethra, similar to that which prevails at the termination of the choledoch duct in the duodenum. It is affirmed, by some, that the prostate exerts a pressure on the ductus ejaculatorius, and that the opening of the duct into the urethra is smaller than any other part of it; by others, that the ejaculatory ducts are embraced, along with the neck of the bladder, by the levator ani, and consequently, that the sperm finds a readier access into the ducts of the vesiculae seminales. The sperm—lac maris, male's milk, propagalory or genital liquor, vitale virus, vital or quickening venom—is of a white colour, and of a faint smell, which, owing to its peculiar character, has been termed spermatic. It is of a viscid consistence, of a saline, irritating taste, and appears composed of two parts, the one more liquid and trans- parent, and the other more grumous. In a short time after emission, these two parts unite and the whole becomes more fluid. When examined chemically, the sperm appears to be of an alkaline, and albuminous character. Vauquelin0 analyzed it and found it to be composed,—in 1000 parts,—of water, 900; animal mucilage, 00; soda, 10; calcareous phosphate, 30. John's analysis'1 accords with this. Berzelius affirms, that it contains the same salts as the blood * See some remarks, by the author, in his American Medical Intelligencer, p. 146, July 15, 1837; and by Dr. Warrington, ibid. p. 244, Oct. 1. b Observations on the Structure and Diseases of the Testis, Lond. 1830; and J. Mailer, in art. Erection, Encyclopad. Worterb. der Medic. Wissensch. xi. 460, Berl. 1834. c Annales de Chimie, ix. 64. d Chemische Tabellen des Thierreichs, s. 169, Nurnberg, 1814; and Burdach's Phy- siologie, u. s. w., i. 111. 340 GENERATION. along with a peculiar animal matter—spermaline. After citing these analyses, Raspail* observes, that if any thing be capable of humiliating the pride of the chemist, it is assuredly the identity he is condemned to discover amongst substances, which, notwith- standing, fulfil such different functions. No analysis has been made of the sperm as secreted by the tes- ticle. The fluid examined has been the compound of the pure sperm and the secretions of the prostate gland and of those of Cowper. The thicker, whitish portion is considered to be the secretion of the testicles;—the more liquid and transparent, the fluids of the accessory glands or follicles. Some authors have imagined, that a sort of halitus or aura is given off from the sperm, which they have called the aura seminis, and have considered to be sufficient for fecundation. The fallacy of this view will be exhibited hereafter. Others have discovered, by the microscope, numerous minute bodies in the sperm, seminal animalcules,—spermatozoa or zoospermes,—which they have con- ceived to be important agents in generation.b By careful examination, according to Wagner,0 other minute, round, granulated bodies may almost always be detected; which are, in all cases, much less numerous than the spermatozoa. These bodies he distinguishes by the names seminal granules—granula seminis. Both elements of the sperm are suspended in a small quantity of perfectly homogeneous fluid, transparent and clear as water. " Pure semen, therefore, in its most perfect state, consists principally of seminal animalcules and seminal granules, both of which are enveloped in a small quantity of fluid." This fluid Wagner calls liquor seminis; and he suggests, in connexion with the discoveries of Schwann and Schleiden, referred to at page 213 of this volume, whether, in the developement of the spermatozoa, the liquor seminis may not be regarded as a matrix, (zellenkeimstoff, cystoblastema, Schwann,) in which the granular nuclei are developed as cyloblasts, which again put forth their covering or cyst as a cellular wall: the finely granular contents would then have to be considered as the cell-fluid. The cytoblasts disappear as soon as the spermatozoa are evolved in their contents, and the cells burst and cast out the animalcules, as the cells of the algae scatter abroad their sporules.d These animalcules, however, have been denied to be peculiar to this fluid, and have been regarded as infusory animal- cules, similar to those met with in all animal infusions; by others, they have been esteemed organic molecules of the sperm. Virey,6 1 Chimie Organique, p. 386, Paris, 1833. b Adelon, in art. Generation, of Diet, de Med. torn, x.; and Physiologie de I'Homme, iv. 17. See, also, Burdach's Physiologie, i. 112, for the various opinions on this sub- ject; and M. Donne, in Gazette Medicale de Paris, Juin 3, 1837. c Elements of Physiology, translated from the German, by Robert Willis, M. D. part i. p. 4, Lond. 1841. d Wagner, op. cit. p. 27. e Art. Generation, in Diet, des Sciences Medicales; and Philosophic d'Histoire Na- turelle, Paris, 1835. SPERM. 341 —a physiologist, strangely fantastic in his speculations,—conceives, that as the pollen of vegetables is a collection of small capsules, containing within them the true fecundating principle, which is of extreme subtilty, the pretended spermatic animalcules are tubes containing the true sperm, and the motion we observe in thern is owing to the rupture of the tubes; whilst Raspail* is led to think, that they are mere shreds, (lambeaux) of the tissues of the genera- tive organs, ejaculated with the sperm, which describe involun- tary movements by virtue of the property they possess of aspiring and expiring. In confirmation of this, he states, that if we open an ovary of the mussel, we may observe, alongside the large ovules, myriads of moving shreds, whose form and size are infinitely varied, and which possess nothing resembling regular organization. They bear evident marks of laceration. Now, these shreds, he conceives, may affect greater regularity in certain classes of animals of a more elevated order; but, he concludes, that however this may be, the spermatic animalcules, which have hitherto been classed amongst those incerta sedis, may be provisionally placed in the genus cerca- ria—that is, amongst infusory, agastric animals having a kind of tail—which Raspail considers the simplest of animated beings, and to live only by " aspiration and expiration." Wagner also re- marks, that the expression cercaria seminis, applied to the sper- matozoon, can only" be a collective title, and that the manifold forms of spermatozoa, which he has found to occur in the seminal fluid of a great number of animals, must be viewed in the light of so many different species. Ehrenberg refers them to the haustellate entozoa.b The author has examined the sperm with microscopes of high magnifying power, but without being able to satisfy himself, that the°minute bodies, contained in it, are animalcular. In a powerful hydroxygen microscope, not the slightest appearance of animalcules presented itself. Sir Everard Home and Mr. Bauer0 were equally unsuccessful, and they were led to conclude, that the appearance of living animalcules in the semen is not real, but the effect of a micro- scop?c deception. Wagner,d however, considers, that they are essential elements of the seminal fluid, and bear a specific relation to the generative act, and that they are thus far comparable to the blood-globules; which present themselves in the same manner as essential typically organized constituents of the blood amid the liquor sanguinis, "just as the spermatozoa present themselves amid the liquor seminis. The question of their animality he considers, however, to be undetermined as their internal organization had not been detected. In the appendix, however, to Dr. Wagner's work, Dr. Willis6 remarks, that'in the examination of the sperma- tozoa of the bear, Dr. Valentin** had settled the question of the orga- » Op. citat. p. 389. «> For a full account of these animalcules, see Wagner, op. citat. p. 6. « Lect. on Comp. Anat. v. 337, Lond. 1828. a Op. citat. p. 34. e Ibid. p. 228. f Nov. Act. Acad. C. L. Natur. Curios, vol. xi. 1839. 29* 342 GENERATION. nization and consequently the true animal nature of the seminal animalcule. The agency of the sperm in fecundation will be considered here- after. It may be observed, however, that in all examinations of it, whether by the microscope or otherwise, we must bear in mind, the caution to which we have adverted more than once, as appli- cable to the examination of animal fluids in general,—that we ought not to conclude positively, from the results of our observations of the fluids when out of the body, that they possess precisely the' same characteristics when in it; and this remark is especially applicable to the sperm, which varies manifestly in its sensible properties a short time after it has been excreted. The sperm being the great vivifying agent,—the medium by which life is communicated from generation to generation,—it has been looked upon as one of the most important if not the most im- portant of animal fluids; and hence it is regarded, by some physio- logists, as formed of the most animalized materials, or of those that constitute the most elevated part of the new being—the nervous system. The quantity of sperm secreted cannot be estimated. It varies according to the individual, and to his extent of voluptuous excite- ment, as well as to the degree of previous indulgence in venereal pleasures. Where the demand is frequent, the supply is larger; although when the act is repeatedly performed, the absolute quan- tity at each copulation may be less.* b. Genital Organs of the Female. The genital organs of the male effect fewer functions than those of the female. They are inservient to copulation and fecundation only. Those of the female,—in addition to parts, which fulfil these offices,—comprise others for gestation and lactation. The soft and prominent covering to the symphysis pubis—which is formed by the common integuments, elevated by fat, and, at the age of puberty covered by hair, formerly termed tressoria—is called the mons veneris. The absence of this hair has, by the vulgar, been esteemed a matter of reproach; and it was formerly the custom, when a female had been detected a third time in incontinent practices, in the vicinity of the Superior Courts of Westminster, to punish the offence by cutting off the tressoriab in open court. Below this, are the labia pudendi or labia majora, which are two large, soft lips, formed by a duplicature of the common integument, with adipous matter interposed. The inner surface is smooth, and studded with a Theophrastus, Pliny, and Athenaaus assert, that with the help of a certain herb, an Indian prince was able to copulate seventy times in twenty-four hours!—Theophr. 1. c. v., Plin. 1. xxvi. c. 9, and Athenaeus, 1. i. c'12. See, also, art. Cas rares, in Diet. des Sciences Medicales. b Chitty's Practical Treatise on Medical Jurisprudence, part i. p. 390, Amer. Edit. Philad. 1836. GENERATIVE APPARATUS—FEMALE. 343 sebaceous follicles. The labia commence at the symphysis pubis, descend to the perinaum, which is the portion of integument, about an inch and a half in length, between the posterior commissure of the labia and the anus. This commissure is called the franum labiorum, franulum perinai or fourchette. The opening between the labia is the vulva or fossa magna. At the upper junction of the labia, and within them, a small organ exists, called the clitoris or superlabia, which greatly resembles the penis. It is formed of corpora cavernosa, and is terminated ante- riorly by the glans, which is covered by a prepuce, consisting of a prolongation of the mucous membrane of the vagina. Unlike the penis', however, it has no corpus spongiosum, or urethra attached to it; but it is capable of being made erect by a mechanism similar to that which applies to the penis; and it has two erector muscles,— the erectores clitoridis,—similar to the erectores penis. Anciently, if a female was detected a fourth time in incontinence in the vicinity of the Superior Courts of Westminster, the clitoris was amputated in open court.* Extending from the prepuce of the clitoris, and within the labia majora, are the labia minora or nympha, the organization of which is similar to that of the labia majora. They gradually enlarge as they pass downwards, and disappear when they reach the orifice of the vagina. A singular variety is observed in the organization of those parts amongst the Bosjesmen or Bushmen, the tribe to whose peculiarities of organization we have already had occasion to refer. Discordance has, however, prevailed regarding the precise nature of this pecu- liarity, some describing it as existing in the labia, others in the nymphae, and others again, in a peculiar organization; some] deem- ing it natural, others artificial. Dr. Somerville,b who had numerous opportunities for observation and dissection, asserts, that the mons veneris is less prominent than in the European, and is either desti- tute of hair, or thinly covered by a small quantity of a softrwoolly nature; that the labia are very small, so that they seem at times to be almost wanting; that the loose, pendulous, and rugous growth, which hangs from the pudendum, is a double fold; and that it is proved to be the nymphae, by the situation of the clitoris at the commissure of the folds, as well as by all other circumstances; and that they sometimes reach five inches below the margin of the labia; Le Vaillant0 says nine inches. Cuvierd examined the Hottentot- Venus, and found her to agree well with the account of Dr. Somer- ville. The labia were very small; and a single prominence descended between them from the upper part. It divided into two * Chitty's Practical Treatise on Medical Jurisprudence, part i. p. 391, Amer. Edit. Philad. 1836. b Medico-Chirurgical Transactions, vii. 157. c Voyage dans l'lnterieur d'Afriq.ue, p. 371. d Memoir, du Museum, iii. 266; and Broc, Essai sur les Races Humaines, p. 87, Paris, 1836. 344 GENERATION. lateral portions, which passed along the sides of the vagina to the inferior angle of the labia. The whole length was about four inches. When she was examined naked by the French Savans, this forma- tion was not observed. She kept the tablier, ventrale cutaneum, or, as it is termed by the Germans, s c h ii r z e (' apron,') carefully con- cealed, either between her thighs, or yet more deeply; and it was not known, until after her death, that she possessed it. Both Mr. Barrow* and Dr. Somerville deny that the peculiarity is artificially excited. In warm climates, the nymphae are often greatly and inconve- niently elongated, and amongst the Egyptians and other African tribes, it has been Fig. 146. the custom to extir- pate them, or to diminish their size. This is what is meant by circumci- sion in the female. The vagina is a canal, which ex- tends between the vulva and the ute- rus, the neck of which it embraces. It is sometimes called the vulvo- uterine canal, and is from four to six inches Jong, and an d. inch and a half, or two inches in di- ameter. It is situ- ate in the pelvis, between the bladder before, and the rectum behind; it is slightly curved, with the concavity forwards, and is narrower at the middle than at the extremities. Its inner surface has numerous—chiefly transverse—rugae, which become less in the progress of age, after repeated acts of copulation, and especially after accouchement. The vagina is composed of an internal mucous membrane, sup- plied with numerous mucous follicles, of a dense cellular membrane, and, between these, a layer of erectile tissue, which is thicker near the vulva; but is, by some, said to extend even as far as the uterus. It is termed the corpus spongiosum vagina. It is chiefly situate around the anterior extremity of the vagina, below the clitoris, and at the base of the nymphae; and the veins of which it is constituted are called plexus retiformis. The upper portion of the vagina, to a small * Travels, p. 279, 280; see, also, Lawrence's Lectures on Physiology, Zoology, &c. Lond. 1819; and Dr. D. D. Davis, in Principles, &c. of Obstetric Medicine, i. 54. Lond. 1836. Lateral view of the Female Organs. A. Section of os pubis. B. Section of spine and acrum. C. Uri n. kjc^uv/n ui uo puuie. jd. oeuwuii ui splint: aim sacrum. %j. ( nary bladder, moderately distended, and rising behind the pubis. The urethra. E. The uterus.' G. The vagina, embracing the n of the womb, with the os uteri projecting into it. GENERATIVE APPARATUS—FEMALE. extent, is covered by the peritoneum. The sphincter or constrictor vagina muscle surrounds the orifice of the vagina, and covers the plexus retiformis. It is about an inch and a quarter wide; arises from the body of the clitoris, and passes backwards and down- wards, to be inserted into the dense, white substance, in the centre of the perineum, which is common to the transversi perinei muscles, and the anterior point of the sphincter ani. Fig. 147. Anterior view of the Female Organs. Near the external aperture of the vagina is the hymen or vir- ginal, or vaginal valve, which is a more or less extensive, mem- branous duplicature, of variable shape, and formed by the mucous membrane of the vulva where it enters the vagina, so that it closes the canal, more or less completely. It is generally very thin, and easily lacerable; but is sometimes extremely firm, so as to prevent penetration. It is usually of a semilunar shape; sometimes oval from right to left, or almost circular, with an aperture in the middle, whilst, occasionally, it is entirely imperforate, and of course pre- vents the issue of the menstrual flux. It is easily destroyed by mechanical violence of any kind, as by strongly rubbing the sexual organs of infants by coarse cloths, and by ulcerations of the part; hence its absence is not an absolute proof of the loss of virginity, as it was of old regarded by the Hebrews. Nor is its presence a positive evidence of continence. Individuals have conceived, in whom the aperture of the hymen has been so small as to prevent penetration. Its general semilunar or crescentic shape has been 346 GENERATION. considered to explain the origin of the symbol of the crescent assigned to Diana—the goddess of chastity.* Around the part of the vagina, where the hymen was situate, small, reddish, flattened, or rounded tubercles—the caruncula myr- tiformes seu hymenales—afterwards exist, which are of various sizes, and are formed, according to the general opinion, by the remains of the hymen: Beclard and J. Cloquetb consider them to be folds of the mucous membrane. Their number varies from two to five, or six. Fig. 148. Female Organs. o. Fundus uteri, b. Body of the uterus, c. Neck of the uterus, d. Os uteri, e. Vagina. /,/. Fallopian tubes, g.g. Broad ligaments of the uterus. A, A. Round ligaments, p, p. Fimbriated extremities of the Fallopian tube. 0,0. Ovaries. 1,1. Ligaments of the ovary. The uterus is a hollow organ, for the reception of the foetus, and its retention during gestation. It is situate in the pelvis, between the bladder—which is before, and the rectum behind, and below the convolutions of the small intestines. Fig. 146 gives a lateral view of their relative situation, and Fig. 147, of their position, when regarded from before. It is of a conoidal shape, flattened on the anterior and posterior surfaces; rounded at the base, which is above, and truncated at its apex, which is beneath. It is of small size; its length being only about two and a half inches; its breadth one and a half inch at the base, and ten lines at the neck; its thickness about an inch. It is divided into the fundus, body, and cervix or neck. The fundus is the upper part of the organ, which is above the insertion of the Fallopian tubes. The body is the part between the insertion of the tubes and the neck; and the neck is the lowest and narrowest portion, which projects and opens into the vagina. a Chitty, op. citat. p. 389, and Beck's Medical Jurisprudence, 5th edit. i. 113, Albany. 1836. For an elaborate description of the Hymen and Hymenal Caruncles, see De- villiers, Revue Medicale, Mai, 1840; and Encyeloarraph. des Sciences Medicales, Juin, 1840, p. 65. See, also, Virey, Gazette Medicale, No. xxiii., Paris, 1840. b Dictionnaire de Medecine, &c, art. Caroncule, Paris, 1821. GENERATIVE APPARATUS—FEMALE. 347 Interior of the Uterus. At each of the two superior angles are—the opening of the Fal- lopian tube, the attachments of the ligament of the ovary, and that of the Fig. 149. round ligament. The inferior angle is formed by the neck, which projects into the vagina to the distance of four or five lines, and terminates by a cleft, situate crosswise, called os tinea, os uteri or vaginal orifice of the uterus. The aperture is bounded by two lips, which are smooth and rounded in those that have not had children; jagged and rugous in those who are mothers,—the anterior lip being somewhat thicker than the posterior. It is from three to five lines long, and is generally more or less open, espe- cially in those who have had chil- dren.* The internal cavity of the uterus is very small in proportion to the bulk of the organ, owing to the thickness of the parietes, which almost touch internally. It is divided into the cavity of the body, and that of the neck, (Fig. 149.) The former is triangular. The tubes open into its upper angles. The second cavity is more long than broad; is broader at the middle than at. either end, and at the upper part, where it communicates with the cavity of the body of the uterus, an opening exists, called the internal orifice of the uterus: the external orifice being the os uteri. The inner surface has several transverse rugae, which are not very prominent. It is covered by very fine villi, and the orifices of several mucous follicles are visible. The marginal figure (Fig. 150) exhibits the cavity of the uterus, as seen by a vertical lateral section. The precise organization of the uterus has been a topic of interesting inquiry amongst anatomists. It is usually considered to be formed of two parts, a mucous membrane internally, and the proper tissue of the uterus, section of the uterus. which constitutes the principal part of the substance. The mucous membrane has been esteeemed a pro- longation of that which lines the vagina. It is very thin; of a red hue in the cavity of the body of the organ; white in that of the neck. Chaussier, Ribes, and Madame Boivin, however, deny its a See, on the Neck of the Uterus in the Young Female, Dr. Marc D'Espine, in Arehiv. General, de Medecine, Avril, 1836; and Dunglison's American Medical Intelli- gencer, i. 103, Philad. 1838. 348 GENERATION. existence. Chaussier asserts, that having macerated the uterus and a part of the vagina in water, in vinegar, and in alkaline solutions; and having subjected them to continued ebullition, he always observed the mucous membrane of the vagina stop at the edge of the os uteri; and Madame Boivin,—a well-known French authoress on obstetrics, who has attended carefully to the anatomy of those organs during pregnancy,—says, that the mucous membrane of the vagina termi- nate by small expansible folds, and by a kind of prepuce, under the anterior lip of the os uteri. In their view, the inner surface of the uterus is formed of the same tissue as the rest of it.* The proper tissue of the organ is dense, compact, not easily cut, and somewhat resembles cartilage in colour, resistance, and elasticity. It is a whitish, homogeneous substance, penetrated by numerous minute vessels. In the unimpregnated state, the fibres, which seem to enter into the composition of the tissue, appear ligamentous and pass in every direction, but so as to permit the uterus to be more readily lacerated from the circumference to the centre than in any other direction. The precise character of the tissue is a matter of conten- tion amongst anatomists. To judge from the changes it experiences during gestation, and by its energetic contraction in delivery, it would seem to be decidedly muscular, or at least capable of as- suming that character; but, on this point, we shall have occasion to dwell hereafter. The uterus has, besides the usual organic constituents,—arteries, veins, lymphatics, and nerves. The arteries proceed from two sources;—from the spermatic, which are chiefly distributed to the fundus of the organ, and towards the part where the Fallopian tubes terminate; and from the hypogastric, which are sent especially to the body and neck. Their principal branches are readily seen under the peritoneum, which covers the organ: they are very tortuous; frequently anastomose, and their ramifications are lost in the tissue of the viscus, and on its inner surface. The veins empty themselves partly into the spermatic, and partly into the hypogastric. They are even more tortuous than the arteries; and, during pregnancy, they dilate and form what have been termed the uterine sinuses. The nerves are derived partly from the great sympathetic, and partly from the sacral pairs. The appendages of the uterus are:—1. The ligamenta lata or broad ligaments, which are formed by the peritoneum. This mem- brane is reflected over the anterior and posterior surfaces and over the fundus of the uterus, and the lateral duplicatures of it form a broad expansion, and envelope the Fallopian tubes and ovaria. These expansions are the broad ligaments. (See Fig. 148, g, g, and Fig. 147.) 2. The anterior and posterior ligaments, which are four in number and are formed by the peritoneum. Two of these pass from the uterus to the bladder,—the anterior; and two between » Velpeau, Traite Elementaire de 1'Art des Accouchemens, i. 77, Paris, 1829, 2d Amer. Edit, by Dr. Meigs, Philad. 1838; and Adelon, Physiologie de PHomme, 2de edit. iv. 26. GENERATIVE APPARATUS—FEMALE. 349 Fallopian Tube. the rectum and uterus,—the posterior. 3. The ligamenta rotunda or round ligaments, which are about the size of a goosequill, arise from the superior angles of the fundus uteri, and, proceeding obliquely downwards and outwards, pass out through the abdominal rings to be lost in the cellular tissue of the groins. They are whitish, some- what dense cords, formed by a collection of tortuous veins and lymphatics, of nerves, and of longitudinal fibres, which were, at one time, believed to be muscular, but are now generally considered to consist of condensed cellular tissue. 4. The Fallopian or uterine tubes; two conical, tor- tuous canals, four or five inches in length; situate in the same broad liga- ments that contain the ovaries and extending from the superior angles of the uterus as far as the lateral parts of the brim of the pelvis. (Figs. 147, 148, and 151.) The uterine extremity of the tube, (Figs. 149 and 151,) is extremely small, and opens into the uterus by an aperture so minute, as to scarcely admit a hog's bristle. The other extremity is called the pavilion. It is trumpet-shaped, fringed, and commonly inclined towards the ovary, to which it is attached by one of its longest fimbriae. This fringed portion is called corpus fimbriatum or morsus diaboli. The Fallopian tubes, consequently, open at one end into the cavity of the uterus, and at the other through the peritoneum into the cavity of the abdomen. They are covered externally by the broad ligament, or peritoneum; are lined internally by a mucous membrane, which is soft, villous, and has many longitudinal folds; and between these coats is a thick, dense, whitish membrane, which is possessed of contractility; although muscular fibres cannot be detected in it.* Santorini asserts, that in robust females the middle membrane of the tubes has two muscular layers; an external, the fibres of which are longitudinal, and an internal, whose fibres are circular. The ovaries, (Figs. 148 and a Fig. 152. b 152,) are two ovoid bodies, of a pale red co- lour, rugous, and nearly of the size Qvary Section of c^ary. of the testes of • the male. They are situate in the cavity of the pelvis, and are 1 Weber's Hildebrandt's Handbuch der Anatomie, Band iv. s. 422, Braunschweig' 1832. 30 VOL. II. 350 GENERATION. contained in the posterior fold of the broad ligaments of the uterus. At one time they were conceived to be glandular, and were called the female testes; but as soon as the notion prevailed, that they con- tained ova, the term ovary Or egg-vessel was given to them. ' The external extremity of the ovary has attached to it one of the prin- cipal fimbriae of the Fallopian tube. The inner extremity has a small fibro-vascular cord inserted into it: this passes to the uterus to which it is attached behind the insertion of the Fallopian tube, and a little lower. It is called the ligament of ihe ovary, and is in the pos- terior ala of the broad ligament. It is solid, and has no canal. The surface of the ovary has many round prominences, and the peritoneum—forming the indusium—envelopes the whole of it, except at the part where the ovary adheres to the broad ligament. The precise nature of its parenchyma or stroma is not determined. When torn or divided longitudinally, as in Fig. 152, b, it appears to be constituted of a cellulo-vascular tissue. In this, there are from fifteen to twenty spherical vesicles—ovula Graafiana or folliculi Graafian?—varying from half a line to three lines in diameter. Roedererb asserts that he found in the ovary of one woman thirty, in that of another about fifty. These are filled with an albuminous fluid, which is colourless or yellowish, and may be readily seen by dividing the vesicles carefully with the point of fine scissors. The fluid from the ovary of a mare was examined by Lassaigne, and found to contain albumen, with chlorides of sodium and potas- sium.0 The experiments of Carusd have shown, that the vesicles exist even in the foetus. In these vesicles, we shall see hereafter, the ovum is contained. The arteries and veins of the ovaries belong to the spermatics. The arteries pass between the two layers of the broad ligament to the ovarium, as- suming there a beautiful convoluted ar- rangement, very similar to the convolu- ted arteries of the testis. These vessels tra- verse the ovary nearly in parallel lines, as in the marginal figure, forming numerous minute twigs, which have an irregular knotty appearance, from their tortuous condition, and appear to be chiefly distri- buted to the Graafian vesicles." The nerves of the ovaries, which are extremely delicate, are from the renal plexuses; and their lym- phatics communicate with those of the kidneys. Such is the anatomy of the chief organs concerned in the func- tion of generation. Those of lactation we shall describe hereafter. ■ Weber's Hildebrant's Handbuch der Anatomie, B. iv. 458, Braunschweig, 1832. b Stannius, art. Eierstock, in Encycl. Worferb. x. 188, Berl. 1836. c Dupuy's Journal de Medec. Veterin for July, 1826, p. 336. d Gazette Medicale de Paris, Aug. 12, 1837. e E. Rigby, System of Midwifery, Amer. edit. p. 23, Philad. 1841. MENSTRUATION. 351 1. MENSTRUATION. Before proceeding to the physiology of generation, there is one function, peculiar to the female, which will require consideration. This consists in a periodical discharge of blood from the vulva, occurring from three to six days in every month, during the whole time that the female is capable of conceiving, or from the period of puberty to what has been termed the critical age. This discharge is called the catamenia, menses, flowers, &c, and the process men- struation. It seems to be possessed by the human species alone.* F. Cuvier, however, asserts that he has discovered indications of it in the females of certain animals; but it is usually denied that this is any thing more than the exudation of a bloody mucus.b In some females, menstruation is established suddenly, and with- out any premonitory symptoms; but, in the greater number, it is preceded and accompanied by some inconvenience. The female complains of signs of plethora, or general excitement,—indicated by redness and heat of skin, heaviness in the head, oppression, quick pulse, and pains in the back or abdomen; whilst the discharge com- mences drop by drop, but continuously- During the first twenty- four hours, the flow is not as great as afterwards, and is more of a serous character; but, on the following day, it becomes more abun- dant and sanguineous, and gradually subsides, leaving, in many females, a whitish, mucous discharge, technically termed leucorrhaea, and, in popular language, the whites. The quantity of fluid lost, during each menstruation, varies greatly, according to the individual and to the climate. Its average is sup- posed to be from six to eight ounces in temperate climes. By some, it has been estimated as high as twenty, but this is an exaggeration. The menstrual fluid proceeds from the interior of the uterus, and not from the vagina. At one time, it was believed, that in the inter- vals between the flow of the menses, the blood gradually accumu- lates in some parts of the uterus, and when these parts attain a cer- tain degree of fulness, they give way and the blood flows. This office was ascribed to the cells,—which were conceived to exist in the substance of the uterus between the uterine arteries and veins,— and, by some, to the veins themselves, which, owing to their great size, were presumed to be reservoirs, and hence were called uterine sinuses. The objection to these views is,—that we have no evidence of the existence of any such accumulation; and that when the inte- rior of the uterus of one who has died during menstruation is examined, there are no signs of any such rupture as that described: the enlarged vessels exist only during pregnancy or during the ex- panded state of the uterus; the veins, in the unimpregnated uterus, being extremely small, and totally inadequate for such a purpose. The menstrual fluid is a true exhalation, effected from the inner surface of the uterus. This is evident from the change in the lining membrane of the organ during the period of its flow. It is rendered a Blumenbach, De Gener. Human. Variet. ed. 3, p. 51, Gotting. 1795. b Art. Generation, by Dr. Allen Thomson, in Cyclop, of Anatomy and Physiology, part xiii. p. 441, Feb. 1838. 352 GENERATION. softer and more villous, and exhibits bloody spots, with numerous pores from which the fluid may be expressed. An injection, sent into the arteries of the uterus, also readily transudes through the lining membrane. The appearance of the menstrual fluid in the cavity of the uterus, during the period of its flow ; its suppression in various morbid conditions of the organ; and the direct evidence, furnished to Ruysch, Blundell,a Sir C. Clarke,b and others, in cases of prolapsus or of inversio uteri, where the fluid has been seen dis- tilling from the uterus, likewise show that it is a uterine exhalation. It has been a question, whether the fluid proceeds from the arteries or veins; and this has arisen from the circumstance of its being regarded as mere blood; but it is in truth little like blood, except in colour; and it may be distinguished from blood by the smell, which is sui generis, and also by its not being coagulable. " It is," says Mr. Hunter, " neither similar to blood taken from a vein of the same person, nor to that which is extravasated by acci- dent in any other part of the body, but is a species of blood, changed, separated, or thrown off from the common mass by an action of the vessels of the uterus, similar to that of secretion, by which action the blood loses the principle of coagulation and, I suppose, life." The principle of coagulation does not exist, owing, according to Lavagna,c Toulmouche, and J. Muller,d to absence of fibrine. Retzius6 asserts, that he has detected in it free phosphoric and lactic acids, by the presence of which, he conceives, the fibrine is kept in a state of solution and prevented from coagulating. The fluid has the properties, according to Brande, of a very concentrated solution of the colouring matter of the blood in a dilute serum.f Dr. Burowg examined twelve ounces of menstrual blood, which had been retained in the uterus by an imperforate hymen. The fluid was of a dirty reddish brown, colour, of the consistence of syrup, very adhesive, and entirely devoid of odour. It abounded in albumen, and was very little susceptible of putrefaction. When examined with the microscope, almost all the blood-globules were found to have lost their regular form, and to resemble the granules, observed in pus which has been for a long time exposed to the air, or retained within the cavity of an abscess. These blood-globules were suspended in a transparent fluid. On stirring the blood for a considerable time, no perceptible change was produced to the eye, but under the microscope numerous delicate transparent lamellae were seen floating in the serum, which Dr. Burow regarded as por- tions of fibrine, a substance sparingly present—as has been remarked —in menstrual blood. 1 Principles and Practice of Obstetricy, Amer. edit. p. 49, Washington, 1834. b On Diseases of Females, attended with Discharges, Amer. edit. Philad. 1824; see, also, Dr. D, Davis, in Principles, &c. of Obstetric Medicine, i, 256, Lond. 1836. c Brugnatelli, Giornale di Fisica, &c. p. 397,1817 ; Desormeaux, in Diet, de Medec. xiv. 181. d Handbuch der Physiologie, Baly's translation, p. 256, Lond. 1837. e Ars Berattelse af Setterblad, 1835, Seite 19—quoted in Zeitschrift for die Gesammte Medicin. Marz, 1837, S. 390. { Philos. Transact, cii. 113; and Blundell, op. cit. p. 46. s Mttller's Arehiv. No. vii. 1840; and Brit, and For. Med. Rev. July, 1840, p. 287. ! MENSTRUATION. 353 The red colour of the menstrual fluid was found by Remak* to be owing to the presence of blood-globules, and the intensity of the colour to their number. The fact of injections, sent into the arteries, transuding through the inner lining of the uterus is in favour of the exhalation taking place from the arteries, and the analogy of all the other exhalations is confirmatory of the position. Still there are many eminent phy- siologists and obstetricians who regard the discharge as a monthly hemorrhage. The efficient cause of menstruation has afforded ample scope for speculation and hypothesis.b As its recurrence corresponds to a revolution of the moon around the earth, lunar influence has been invoked; but, before this solution can be admitted, it must be shown, that the effect of lunar attraction is different in the various relative positions of the moon and earth. There is no day in the month, in which numerous females do not commence their menstrual flux, and, whilst the discharge is beginning with some, it is at its acme or decline with others. The hypothesis of lunar influence must there- fore be rejected. In the time of Van Helmont,c it was believed, that a ferment exists in the uterus, which gives occasion to a periodical intestine motion in the vessels, and a recurrence of the discharge; but inde- pendently of the want of evidence of the existence of such a ferment, the difficulty remains of accounting for its regular renovation every month. Local and general plethora have been assigned as causes, and many of the circumstances, that modify the flow, favour the opinion. The fact of, what has been called, vicarious menstruation has been urged in support of this view. In these cases, instead of the men- strual flux taking place from the uterus, hemorrhages occur from various other parts of the body, as the breast, lungs, ears, eyes, nose, &c. It does not seem, however, that in any of these cases, the term menstruation is appropriate; inasmuch as the fluid is not menstrual, but consists of blood periodically extravasated. Still, they would appear to indicate, that there is a necessity for the monthly evacuation or purgation, Reinigung, as the French and Germans term it; and that if this be obstructed, a vicarious hemorrhage may be established; yet the loss of several times the quantity of blood from the arm, previous to, or in the very act of, menstruation does not always prevent, or interrupt the flow of the catamenia; and in those maladies, which are caused by their obstruction, greater relief is afforded by the flow of a few drops from the uterus itself, than by ten times the quantity from any other part. Some of the believers in local plethora of the uterus have maintained, that the arteries of the pelvis are more relaxed in the * Medicinische Zeitung, Dec. 25, 1839. See, also, Mr. Ancell, Lectures on the Physiology and Pathology of the Blood, April 25, 1840, p. 149. b Dr. D. Davis, op. cit. i. 259. c Opera, edit. 4, p. 440, Lugd. Bat. 1667; and Haller, Elementa Physiologiae, vii. 1. 30* 354 GENERATION. female than in the male; and the veins more unyielding; hence, that the first of these vessels convey more blood than the second return. It has been also affirmed, that whilst the arteries of the head predominate in man, by reason of his being more disposed for intellectual meditation; the pelvic and uterine arteries predominate in the female, owing to her destination being more especially for reproduction. Setting aside all these gratuitous assumptions, it is obvious, that a state, if not of plethora, at least of irritation, must occur in the uterus every month, which gives occasion to the menstrual secre- tion; but, as Adelon* has properly remarked, it is not possible to say, why this irritation is renewed monthly, any more than to ex- plain, why the predominance of one organ succeeds that of another in the succession of the ages. The function is as natural, as instinc- tive to the female, as the developement of the whole sexual system at the period of puberty. That it is connected most materially with the capability of reproduction is shown by the fact, that it does not make its appearance until puberty,—the period at which the young female is capable of conceiving,—and that it disappears at the cri- tical time of life, when conception is impracticable. It is arrested, too, as a general rule, during pregnancy and lactation; and in amenorrhcea or obstruction of the menses, fecundation is not readily effected. In that variety, indeed, of menstruation, which is accom- plished with much pain at every period, and is accompanied by the secretion of a membranous substance having the shape of the ute- rine cavity, conception may be esteemed impracticable. Professor Hamilton, of the University of Edinburgh, was in the habit of adducing this, in his lectures, as one of two circumstances—the other being the want of a uterus—that are invincible obstacles to fecundation. Yet, in the case of dysmenorrhoea, of the kind men- tioned, if the female can be made to pass one monthly period without suffering, or without the morbid secretion from the uterine cavity, she will sometimes become pregnant, and the whole of the evil will be removed: for, the effect of pregnancy being to arrest the catamenia, the morbid habit is usually got rid of during gesta- tion and lactation, and does not subsequently recur. Gallb strangely supposed, that some general, but extraneous cause of menstruation exists,—not the influence of the moon; and he affirms, that, in all countries, females generally menstruate about the same time; that there are, consequently, periods of the month in which none are in that condition; and he affirms, that all females may, in this respect, be divided into two classes:—the one com- prising those who menstruate in the first eight days of the month, and the other, those who are " unwell"—as it is termed by them, in some countries—in the last fortnight. He does not, however, attempt to divine what this cause may be. We are satisfied that his » Physiologie de I'Homme, 2de edit. iv. 48, Paris, 1829. b Sur les Fonctions du Cerveau, iv. p. 355. MENSTRUATION. 355 positions are erroneous. Attention to the matter has led" us to the knowledge, already expressed, that there is no period of the moon, at which the catamenial discharge is not taking place in some; and we have not the slightest reason for supposing, that, on the average, more females are menstruating at any one part of the month than at another.* It would seem, however, that there are circumstances in the economy, which, as in the case of fevers, give occasion to something like periodicity at intervals of seven days ; fo? example, Mr. Roberton,b of Manchester, England, asserts, that of 100 women the catamenia returned every fourth week in 68 ; every third week in 28; every second week in 1; and at irregular intervals in 10; these varieties usually existing as family and constitutional pecu- liarities. It is scarcely necessary to notice the visionary speculations of those who have regarded menstruation as a mechanical conse- quence of the erect attitude; or the opinion of Roussel,c that it originally did not exist, but that being produced artificially by too succulent and nutritious a regimen, it was afterwards propagated from generation to generation; or, finally, that of Aubert, who maintained, that if the first amorous inclinations were satisfied, the resulting pregnancy would totally prevent the establishment of menstruation. The function, it need scarcely be repeated, is instinctive, and forms an essential part of the female constitution. Recently, M. Gendrind has revived a view entertained by Mr. Cruikshank6 and others, that menstruation is dependent upon changes occurring periodically in the ovary. Many cases have been observed by Cruikshank, Robt. Lee,f Gendrin and others, in which, on the dissection of females who have died during men- struation, evidences have been afforded of the rupture of an ovarian vesicle; whence it has been inferred, that during the whole of that period of life when the capability of conception continues, there is a constantly successive developement of vesicles and their con- tained ovules in the ovary, and that, at each epoch of menstruation, a vesicle having reached the surface of the ovary becomes'the foyer of a peculiar organic action, in which all the organs of gene- ration participate; and that the result of this action is the rupture of the vesicle and the loss of the infecund ovum, either by expulsion from the uterus or by destruction in the ovary. < The age, at which menstruation commences, varies in individuals and in different climates. It has been esteemed a general law, that 8 See art. Generation, by Dr. Allen Thomson, in Cycl. Anat. and Physiol., part xiii. p. 440, Feb. 1838. b Edinburgh Med. and Surg. Journal, xxxvin. 237. c Systeme Physique, &c., de la Femme, p. 13, Paris, 1809. d Traite Philosophique de Medecine Pratique, Paris, 1838-9. e See Brit, and For. Med. Review, Oct. 1840, p. 592. f M. Negrier, cited in Dunglison's Amer. Med. Intelligencer, July 15, 1840, p. 121. See, also, Dr. Robt. Lee, art. Ovaria, Cyclopaedia of Pract. Medicine; Dr. Laycock, on the Nervous Diseases of Women, p. 42, Lond. 1840; and Dr. R. Willis, in note to Wagner's Elements of Physiology, p. 69, Lond. 1841. 356 GENERATION. the warmer the climate, the earlier the discharge takes place, and the sooner it ceases; but there is reason for doubting the correct- ness of this prevalent belief.* With us the most common period of its commencement is from thirteen to fifteen years. Mahomet is said to have consummated his marriage with one of his wives, " when she was full eight years old."b Of 450 cases, observed at the Manchester Lying-in Hospital, in England,0 menstruation com- menced m the eleventh year in 10; in the twelfth in 19; in the thirteenth in 53; in the fourteenth in 85; in the fifteenth in 97; in the sixteenth in 76; in the seventeenth in 57; in the eighteenth in 26; in the nineteenth in,23; and in the twentieth in 4. Men- struation commonly ceases in the temperate zone at from forty to fifty years. These estimates are, however, liable to many exceptions. In rare cases, the catamenia have appeared at a very early age, even in child- hood ; and again, the menses, with powers of fecundity, have con- tinued, in particular instances, beyond the ages that have been specified: some of these protracted cases have had regular cata- menia ; in others, the discharge, after a long suppression, has re- turned. Of 77 individuals they ceased in 1 at the age of 35; in 4 at 40; in 1 at 42; in 1 at 43; in 3 at 44; in 4 at 45; in 3 at 47; in 10 at 48; in 7 at 49; in 26 at 50; in 2 at 51; in 7 at 52; in 2 at 53; in 2 at 54; in 1 at 57 ; in 2 at 60 ; and in 1 at 70. Of the 10,000 pregnant females, registered at the Manchester Hospital, 436 were upwards of 40 years of age; 397 from 40 to 45; 13 in their 47th year; 8 in their 48th; 6 in their 49th; 9 in their 50th; 1 in her 52d; 1 in her 53d; and 1 in her 54th. Mr. Roberton asserts, that as far as he could ascertain,—and especially in the thre"e cases above 50 years,—the catamenia continued up to the period of con- ception.d In the statement sent to Parliament by Bartholomew Mosse, when endeavouring to procure a grant for the Dublin Lying-in Hospital, he mentions, that 84 of the women delivered under his care were between the ages of 41 and 54 ; 4 of these were in their 51st year, and 1 in her 54th. A relation of Haller had two sons after her fiftieth year; and children are said to have been born,jeven after the mother had attained the age of sixty.6 Holdefreund relates the case of a female, in whom menstruation continued till the age of seventy-one ;f Bourgeois till the age of eighty; and Hagendorn till ninety; however, it is probable, that these were not cases of true menstruation, but perhaps of irregularly periodical discharges of true blood from the uterus or vagina.^ * Dr. A. Thomson, op. citat. p. 442. b Prideaux's Life of Mahomet, p. 30, Lond. 1718. c Roberton, op. citat. d See Montgomery, on the Signs and Symptoms of Pregnancy, p. 160, Lond. 1837. e See a case of this kind in Transylvania Journal, ix. 185, Lexington, 1836. f See a case by Dr. Strassberger, of recurrence of menstruation at 80, after it had ceased at 42 years of age, in Medicin. Zeitung, s. 248, Nov. 30, 1836. s Dr. D. Davis, Principles, &c., of Obstetric Medicine, i. 239, London, 1836; and C. W. Mehliss, Ueber Virilescenz und Rejuvenescenz Thierischer KOrper, s. 75, Leipz. 1838. MENSTRUATION. 357 Asa general rule, the appearance of the menses denotes the capa- bility of being impregnated, and their cessation the loss of such capability. Yet, females have become mothers without ever having menstruated. Fodere* attended a woman, who had menstruated but once—in her 17th year,—although 35 years of age, healthy, and the mother of five children. Morgagni instances a mother and daughter, both of whom were mothers before they menstruated. Sir E. Homeb mentions the case of a young woman, who was married before she was seventeen, and having never menstruated, became pregnant; four months after her delivery, she became pregnant again; and four months after the second delivery, she was a third time preg- nant, but miscarried. After this she menstruated for the first time, and continued to do so for several periods, when she again became pregnant; and Mr. Harrison,0 at a meeting of the Westminster Medical Society remarked, that he knew an instance in which the mother of a large family had never menstruated;—yet Dr. Deweesd and Dr. Campbell6 assert, that there is not a properly attested in- stance on record, of an individual conceiving, previous to the esta- blishment of the catamenia : the latter gentleman admits, however, (hat when an individual has once been impregnated, she may con- ceive again, several times in succession, without any recurrence of the catamenia between these different conceptions,—because he has known a case of this kind, but not of the other! During the existence of menstruation, the system of the female is more irritable than at other times; so that all exposure to sudden and irregular checks of transpiration should be avoided, as well as every kind of mental and corporeal agitation, otherwise the process may be'impeded, or hysterical and other troublesome affections be excited. The sacred volume exhibits the feeling entertained towards the female, whilst performing this natural function. Not only was she regarded " unclean" in antiquity; she was looked upon, as Dr. Elliotson has remarked,1" as mysteriously deleterious. In the time of Pliny,g a female, during menstruation, was considered to blight corn, destroy grafts and hives of bees, dry up fields of corn, cause iron and copper to rust and smell, drive dogs mad, &c. &c.; and Dr. Elliotson says it is firmly believed by many, in England, that meat will not take salt if the process be conducted by a female so circumstanced.1* The temperature of the vagina does not appear to be affected by menstruation or pregnancy.* a Medecine Legale, i. 393, Paris, 1813. b Philosoph. Transact, cvii. 258; and Lect. on Comp. Anat. iii. 298. c Lond. Lancet, Jan. 19, 1839, p. 619. d Compend. System of Midwifery, 8th edit. Philad. 1836. e Introduction to the Study of Midwifery, Edinb. 1833. f Elliotson's Blumenbach, p. 465, Lond. 1828. s Histor. Natural, xxvii. h See, also, Velpeau Traite des Accouchemens, i. 117, Paris, 1829 ; Dr. D. Davis, op. citat. i. 278; Choulant, Art. Menstruation, in Pierer's Anat. Phys. Worterb. v. 161, Altenb. 1823; Burdach, Die Physiologie als Erfahrungswissenschaft, i. 237,2te Auflage, Leipz. 1835; and Petrequin, Recherches sur la Menstruation, Paris, 1835, analyzed by M. Cunier, in Bulletin Medical Beige, Juillet, 1838, p. 192. 1 Fricke, Zeitschrift fur die Gesammte Medicin, Nov. 1838. 358 GENERATION. c. Sexual Ambiguity. The sexual characteristics, in the human species, are widely separate; and the two perfect sexes are never, perhaps, united in the same individual. Yet such an unnatural opinion has been sup- posed to exist; from the fabulous son of 'Epu,7]g and A> Adelon, Physiologie de THomme, iv. 66, Paris, 1829 ; and Wagner, Elements of Physiology, by Dr. R. Willis, p. 68, Lond. 1841. c Sir E. Home, Lect. onComp. Anat. iii. 315 ; and Burdach's Physiologie, u. s. w. i. 506. 368 GENERATION. In some experiments on generation, Prevost and Dumas fecun- dated artificially the ova of the frog. Having expressed the fluid from several testicles, and diluted it with water, they placed the ova in it. These were observed to become tumid and developed; whilst other ova, placed in common water, merely swelled up, and in a few days became putrid. They observed, moreover, that the mucus, with which the ova are covered in the oviduct,—the part correspond- ing to the Fallopian tube in the mammalia,—assists in the absorption of the sperm, and in conducting it to the surface of the ovum; and that in order to succeed in these artificial fecundations, the sperm must be diluted: if too much concentrated its action is less. They satisfied themselves likewise, that the chief part of the sperm pene- trates as far as the ova, as animalcules could be detected moving in the mucus covering their surface, and these animalcules they con- ceive to be the active part of the sperm. It is not, however, universally admitted, that the positive contact of sperm with the- ovum is indispensable to fecundation. Some physiologists maintain, that the sperm proceeds no further than the upper part of the vagina; whence it is absorbed by the vessels of that canal, and conveyed through the circulation to the ovary. This is, however, the most improbable of all the views that have been indulged on this topic; for if such were the fact, impregnation ought to be effected as easily by injecting sperm into the blood- vessels,—the female being, at the time, in a state of voluptuous excitement. It has been directly overthrown, too, by the experi- ments of Dr. Blundell* on the rabbit, who found, that when the communication between the vagina and the uterus was cut off, impregnation could not be accomplished, although the animal admitted the male as many as fifty times, generally at intervals of two or three days or more. Yet, it is evident—Dr. Blundell remarks —that much of the male fluid must have been deposited in the vagina, and absorbed by veins or lymphatics.1" Others have presumed, that when the sperm is thrown into the vagina, a halilus or aura—the aura seminis—escapes from it, makes its way to the ovary, and impregnates an ovum. Others, again, think, that the sperm is projected into the uterus, and that in this cavity it undergoes admixture with the germ furnished by the female; whilst a last class, with more probability in their favour, maintain that the sperm is thrown into the uterus, whence it passes through the Fallopian tube to the ovary, the fimbriated extremity of the tube, at the time, embracing the latter organ. The late Dr. Dewees,c suggested, that after the sperm is deposited on the labia pudendi or in the vagina, it may be taken up by a set of vessels—which, he admitted, have never been seen in the human " Principles and Practice of Obstetricy, Castle's edit. p. 56, Amer. edit Washington, 1834. S *> See an Experiment with a similar object, by Dr. Harlan, Medical and Physical Researches, p. 627, Philad. 1835. c A Compendious System of Midwifery, 7th edit. Philad. 1835. FECUNDATION. 369 female—whose duty it is to convey the sperm to the ovary. This conjecture he conceives to have been in part confirmed by the dis- covery of ducts, leading from the ovary to the vagina, in the cow and sow, by Dr. Gartner, of Copenhagen. The objections that may be urged against his hypothesis, Dr. Dewees remarks, " he must leave to others." We have no doubt, that his intimate acquaintance with the subject could have suggested many that are pertinent and cogent. It will be obvious, that if we admit the existence of the ducts, described by Gartner, it by no means follows that they are certainly inservient to the function in question. Independently, too, of the objection that they have not been met with in the human female, it may be urged that if we grant their existence, there would seem to be no reason, why closure of the os uteri, after impregnation, or interruption of the vulvo-uterine canal, by division of the vagina— as in the experiments of Dr. Blundell on rabbits, or division of the Fallopian tubes, should prevent subsequent conception, in the first case during the existence of pregnancy; in the two last, for life. These vessels ought, in both cases, to continue to convey sperm to the ovary, and extra-uterine pregnancies or superfcetation ought to be constantly occurring. MM. Prevost and Dumas* are the most recent writers, who main- tain, that fecundation takes place in the uterus, and they assign the following reasons for their belief. First. That in their experiments, they always found sperm in the cornua of the uterus, and they con- ceive it natural, that fecundation should be operated only where sperm is. Secondly. That in those animals, whose ova are not fecundated until after they have been laid, fecundation must neces- sarily be accomplished out of the ovary; and Thirdly, that in their experiments on artificial fecundation, they have never been able to fecundate ova taken from the ovary. In reply to the first of these positions it has been properly remarked by Adelonb that the evidence of MM. Prevost and Dumas, with regard to the presence of sperm elsewhere than in the uterus, is only of a negative character; and that, on the other hand, we have the positive testimony of physiologists in favour of its existence in the Fallopian tubes and ovary. Haller asserts, that he found it there; and MM. Prevost and Dumas afford us evidence against the position they have assumed respecting the seat of fecundation. They affirm, that on the first day after copulation, the sperm was dis- coverable in the cornua of the uterus, and that it was not until after the lapse of twenty-four hours, that it had attained the summits of the cornua. Once they detected it in the Fallopian tubes;—a cir- cumstance which is inexplicable under the view, that fecundation is accomplished in the uterus. Leeuenhoek and Hartsbker also found it in some cases in the Fallopian tube; and still more recently, Bis- * Annales des Sciences Naturelles, iii. 113. b Physiologie de I'Homme, 2de edit. iv. 68, Paris, 1829. 370 GENERATION. choff, Wagner,' and Dr. M. Barryb have discovered spermatozoa in the fluid collected from the surface of the ovary, and within the capsular prolongations of the Fallopian tubes that enclose the ovaria. In reply to the second argument it may be remarked, that analo- gies drawn from the inferior animals are frequently very loose and unsatisfactory, and ought consequently to be received with caution. This is peculiarly one of these cases; for fecundation, in the case adduced, is always accomplished out of the body, and analogy might with equal propriety be invoked to prove, that in the human female fecundation must also be effected externally. In answer to the third negative position of MM. Prevost and Dumas, the positive experiments of Spallanzani may be adduced, who succeeded in producing fecundation in ova, that had been pre- viously separated from the ovary. The evidence, that conception takes place in the ovary, appears to us convincing. Ovarian pregnancy offers irresistible proof of it. Of this, Mr. Stanley of Bartholomew's Hospital has given an in- structive example ;c and a still more extraordinary instance is related by Dr. Granville.d Other varieties of extra-uterine preg- nancy are confirmative of the same position. At times, the foetus is found in the cavity of the abdomen,—the ovum seeming to have escaped from the Fallopian tube when its fimbriated extremity grasped the ovary to receive the ovum and convey it to the cavity of the uterus. At other times, the foetus is developed in the Fallo- pian tube,—as in the marginal figure,—some impediment having existed to the passage of the ovum from the ovarium to the uterus. This impediment can, indeed, be excited anificially so as to give rise to tubal pregnancy. Nuck applied a ligature around one of the cornua of the uterus of a Fig. 153. bitch, three days after copula- tion; and he found, afterwards, two foetuses arrested in the Fal- lopian tube between the liga- ture and the ovary. Von Baere detected an ovulum in its pas- sage along the Fallopian tube in a bitch, and Raspail asserts, that he once met with an ovule, still attached to the ovary, which contained an embryo/ It is obvious, then, from these facts, either that fecundation occurs in the ovarium, or else that the ovum, when fecundated in the 1 Elements of Physiology, translated by Dr. Robt. Willis, part i. on Generation, p. $6, Lond. 1841. b Philos. Transactions for 1839, p. 315. c Medical Transactions, vol. vi. d Philosophical Transactions, for 1820. eDe Ovi Mammalium et Hominis Genesi, Lips. 1827. f Chimie Organique, p. 262, Paris, 1833. FECUNDATION. 371 uterus, travels along the Fallopian tube to the ovarium, and from thence back again to "the uterus, which is not probable.* Besides, that the ovaries are indispensable agents in the function of genera- tion is shown by the well-known fact, that their removal, by the operation of spaying, not only precludes reproduction but takes away all sexual desire. A case is detailed of a natural defect of this kind in an adult woman, who had never exhibited the slightest desire for commerce with the male, and had never menstruated. On dissec- tion, the ovaria were found deficient; and the uterus was not larger than an infant's.b But to prevent impregnation, it is not even necessary that the ovaries should be removed. It is sufficient to deprive them of all immediate communication with the uterus, by simply dividing the Fallopian tubes. On this subject Haighton0 instituted numerous experiments, the result of which was, that after this operation a foetus was in no instance produced. The operation is much more simple than the ordinary method of spaying by the removal of the ovaries, and it has been successfully practised, at the recommenda- tion of the author, on the farm of his friend Thomas Jefferson Ran- dolph, Esq. of Virginia. It does not seem that the simple division of the Fallopian tubes takes away the sexual desire, as Haighton supposed. Dr. Blundell has proposed this division of the tubes, and even the removal of a small portion of them, so as to render them completely impervious, wheri the pelvis is so contracted as not to admit of the birth of a living child in the seventh month; and he goes so far as to affirm, that the operation is much less dangerous than delivery by perforating the head, when the pelvis is greatly contracted. We have already remarked, that sperm has been found in the cavity of the uterus, and even in the Fallopian tubes. Fabricius ab Acquapendente maintained that it could not be detected there; and Harvey contended, that in the case of the cow, whose vagina is very long, as well as in numerous other animals, the sperm cannot possibly reach the uterus, and that there is no reason for supposing that it ever does. In addition, however, to the facts already cited, we may remark, that Mr. John Hunterd killed a bitch in the act of copulation, and found the semen in the cavity of the uterus, con- veyed thither, in his opinion, per solium. Ruysch," discovered it in the uterus of a woman taken in adultery by her husband and killed by him ; and Hallerf in the uterus of a sheep killed forty-five minutes after copulation. An interesting case, in relation to this point, has been published by Dr. H. Bond,s of Philadelphia. A young female, after having passed a part of the night with a male friend, destroyed * Granville's Graphic Illustrations of Abortion, p. iii. Lond. 1834. b Philosoph. Transactions-for 1805. c Philosoph. Transact, for 1797. <* Philosoph. Transact, for 1817. e Thesaur. Anat. iv.; and Adversaria Anat. Med. Chirurg. Dec. 1. 1 Element. Physiol, viii. 22. s American Journal of the Medical Sciences, No. xxvi. for February, 1834, p. 403. 372 GENERATION. herself early in the morning, by taking laudanum. On cutting open the uterus, it was found to be thickly coated with a substance having the appearance, and the strong peculiar odour, of the sperm. One of the Fallopian tubes was laid open, and found to contain, appa- rently, the same matter, but it was not ascertained whether it pos- sessed the seminal odour. Blumenbach* supposes, that, during the venereal orgasm, the uterus sucks in the sperm. It is impossible to explain the mode in which this is accomplished, but the fact of the entrance of the fluid into the uterus, and even as far as the ovarium seems unquestion- able. This Dr. Blundellb admits, but he is disposed to think, that, in general, the rudiments from the mother, and the fecundating fluid meet in the uterus; as, in his experiments on rabbits, he found— from the formation of corpora lutea, the developement of the uterus and the accumulation of water in the uterine cavity—that the rudi- ments may come down into the uterus, without a previous contact of the semen. His experiments, however, appear to us to prove nothing more, than that infecund ova may be discharged from the ovarium, and that if they are prevented from passing externally, owing to closure of the vagina or cervix uteri, the uterine pheno- mena, alluded to, may occur. They do not invalidate the argu- ments already adduced to show, that the ovum must be fecundated in the ovarium. It has been suggested by Dr. Bostock0 that the ciliary molions, which have been observed by Purkinje, Valentin,"1 and others in the mucous membranes of the air-passages and which have been like- wise detected in the generative organs, and whose office appears to be to propel substances along them, may have something to do with the propulsion of the sperm towards the ovary. Dr. Sharpey,6 how- ever, remarks, that the direction of these motions, in those organs, is from within outwards, so that he conceives it to be difficult to assign any other office to them than that of conveying outwards the secretion of the membrane, unless we suppose that they also bring down the ovum into the uterus. Prof. Wagnerf considers, that the sperm reaches the ovary, partly by the ciliary motions, which begin in the cervix uteri; partly by the contractions of the tubes, and partly by the motility of the spermatozoa. Future observations may shed farther light on this subject. Granting, then, that conception occurs in the ovarium and, that sperm is projected into the uterus, with or without the actions referred to; in what manner does the sperm exert its fecun- a Elements of Physiology, by Elliotson, 4th edit. p. 467, Lond. 1828. b Principles, &c. of Obstetricy, edited by Thomas Castle, M. D. F L S Amer. Edit. p. 56, Washington, 1834. = Physiology, 3d edit. p. 654, Lond. 1836. d Mttller's Arehiv. B. i.; and translation in Dublin Journal of Med. and Chem. Science, May, 1835; and in Edinb. New Philos. Journal, for July, 1835. e Ait. Cilia, Cyclop, of Anat. and Physiology, part vii. p. 633, July, 1836. See, also, Muller, Elements of Physiology by Baly, p. 857, Lond. 1838; and vol. i. p. 465 of this work. f Elements of Physiology, translated by Robert Willis, M. D. part i. p. 72, Lond. 1841. FECUNDATION. 373 dating agency on the ovarium? It is manifestly impossible, that the force of projection from the male can propel it, not only as far as the cornua of the uterus, but also through the narrow media of communication between the uterus and ovary by the Fallopian tubes. This difficulty suggested the idea of the aura seminis or aura semi- nalis, which, it was supposed, might readily pass into the uterus, and through the tubes to the ovary. Haighton, indeed, embraced an opinion more obscure than this, believing that the semen penetrates no farther than the uterus, and acts upon the ovaria by sympathy; and this view has been adopted by some distinguished individuals. In opposition to the notion of the aura seminis, we have some striking facts and experiments. In all those animals, in which fecundation is accomplished out of the body, direct contact of the sperm appears necessary. Spallanzani, and MM. Prevost and Dumas found, in their experiments on artificial fecundation, that they were always unsuccessful when they simply subjected the ova to the emanation from the sperm. Spallanzani took two watch- glasses, capable of being fitted to each other, the concave surface of the one being opposed to that of the other. Into the lower he put ten or twelve grains of sperm, and into the upper about twenty ova. In the course of a few hours, the sperm had evaporated, so that the ova were moistened by it; yet they were not fecundated, but fecun- dation was readily accomplished by touching them with the sperm that remained in the lower glass. A similar experiment was per- formed by MM. Prevost and Dumas. They prepared about an ounce and a half of a fecundating fluid from the expressed humour of twelve testicles, and as many vesiculae seminales. With two and a half drachms of this fluid they fecundated more than two hundred ova. The remainder of this fluid was put into a small retort, to which an adopter was attached. In this, forty ova were placed, ten of which occupied the hollowest part, whilst the rest were placed near the beak of the retort. The appara- Fig. 154. tuswas put under the receiver of an air- pump, and air suffi- cient was withdrawn to diminish the pres- sure of the atmo- sphere one-half. The rays of the sun were now Hirprtfvl nnnn A. The retort containing the sperm. B. The adopter containing I1UVV Uirccieu upon tueova. c. Body of the retort, d. Beak of the retort. the body of the re- tort, until the temperature within rose to about 90°; after the lapse of four hours, the experiment was stopped, when the following were the results. The eggs, at the bottom of the adopter, were bathed in a transparent fluid, the product of distillation. They had become tumid as in pure water, but had undergone no developement. The eggs, near the beak of the retort, were similarly circumstanced, but vol. n. 32 374 GENERATION. all were readily fecundated by the thick sperm, which remained at the bottom of the retort. No aura, no emanation from the sperm consequently appeared to be capable of impregnating the ova. Absolute contact was indispensable.* This is probably the case with the human female, and if so, the sperm must proceed from the uterus along the Fallopian tube to the ovarium.b The common opinion is, that during the intense excite- ment at the time of copulation, the tube is raised, and its digitated extremity applied to the ovarium. The sperm then proceeds along it,—in what manner impelled we know not,—and attains the ovary. According to Blundell and others, during the time of intercourse, the whole of the tube is in a state of spontaneous movement. Cruikshank pithed a female rabbit, when in heat, and examined the uterine system very minutely. The external and internal parts of generation were found black with blood; the Fallopian tubes were twisted like writhing worms, and exhibited a very vivid peristaltic motion, and the fimbriae embraced the ovaria, like fingers laying hold of an object, so closely and so firmly as to require some force, and even slight laceration to disengage them. Haller states, that by injecting the vessels of the tube in the dead body, it has assumed this kind of action. De Graaf, too, affirms, that he has found the fimbriated extremity adhering to the ovary, twenty-seven hours after copulation; and Magendie, that he has seen the extremity of the tube applied to a vesicle. As excitement would appear to be necessary to cause the digi- tated extremity of the Fallopian tube to embrace the ovary, it would seem probable, that a female could not be impregnated without some consciousness of the sexual union. This may be imperfect, as during sleep, or when in a state of stupor—either from spirituous liquors or narcotics—but still some feeling must probably be engendered in order that fecundation may take place. As the aura seminis appears to be insufficient for impregnation, it is obviously a matter of moment, that the sperm should be projected as high up into the vagina as possible. It has been often observed, that where the orifice of the urethra does not open at the extremity of the glans, but beneath the penis, or at some distance from the point, the individual has been rendered less capable of procreation. In a case, that fell under the care of the author, the urethra was opened opposite the corona glandis by a sloughing syphilitic sore, and the aperture continued, in spite of every effort to the contrary. The individual was married, and the father of three or four children; but after this occurrence he had no increase of his family. Many medico-legal writers have considered, that when the urethra termi- nates at some other than its natural situation, impotence is the neces- sary result,—and that although copulation may be effected, impregna- * Rudolphi, art. Aura Seminalis, in Encyclopad. Worterbuch der Medicinisch. Wissenschaft, B. iv. s. 452, Berlin, 1830; and Huter, ait. Empfangniss. ibid. x. 628, Berlin, 1834. b Dr. Allen Thomson, art. Generation, in Cyclop, of Anat. and Physiol, part. xiii. p. 462, Feb. 1838. FECUNDATION. 375 tion is impracticable. Zacchias,* however, gives a positive case to the contrary. Belloc,b too, asserts, that he knew a person, in whom the orifice of the urethra terminated at the root of the fraenum, who had Jour children that resembled the father, two having the same mal- formation; and Dr. Francis refers to the case of an inhabitant of New York, who, under similar circumstances, had two children. Many such cases are, indeed, on record.0 We cannot, therefore, regard it as an absolute cause of impotence, but the inference is just, that if the semen be not projected far up into the vagina, and in the direction of the os uteri, impregnation is not likely, to be accom- plished ; a fact, which it might be of moment to bear in mind, where the rapid succession of children is an evil of magnitude. Yet, not- withstanding this weight of evidence, it has been affirmed by Pro- fessor Heim,d that impregnation may take place by the simple contact of the sperm with the lower part of the abdomen. The answer to this view, by D'Outrepont,e appears to us, however, over- whelming. Heim relies on statements made by the parties that no penetration existed; but D'Outrepont properly observes, that when- ever this has been alleged in a case of pregnancy, he has found, when the parties were strictly questioned, that one or both of them admitted, that the male organ might have been in the vagina, or at least within the vulva. The part, then, to which the sperm is applied is the ovary. Let us now inquire into the changes experienced by this body after a fecundating copulation. Fabricius ab Acquapendente/ having killed hens a short time after they had been trodden, examined their ovaries, and observed,— amongst the small yellow, round granula, arranged racemiferously, which constitute those organs,—one having a small spot, in which vessels became developed. This increased in size, and was after- wards detached, and received by the oviduct; becoming covered, in its passage through that tortuous canal and the cloaca, by parti- cular layers, especially by the calcareous envelope; and being ulti- mately extruded in the form of an egg. Harvey,5 in his experiments on the doe, made similar observations. He affirms, positively, that the ovary furnishes an ovum, and that the only difference, which exists amongst animals in this respect, is, that, in some, the ovum is hatched after having been laid, whilst, in others, it is deposited in a reservoir—a womb—where it undergoes successive changes. De Graafh instituted several experiments on rabbits, for the pur- pose of detecting the series of changes in the organs from concep- tion till delivery. Half an hour after copulation, no alteration was perceptible, except that the cornua of the uterus appeared a little a Quccstiones Medico-Legales, Lugd. 1674. b Cours de Medecine Legale, p. 50, Paris, 1819. c Beck's Elements of Medical Jurisprudence, 5th edit. p. 71, Albany, 1835; and Traill's Outlines of a Course of Lectures on Med. Jurisprudence, p. 26, Edinb. 1840, or American Edition, by the author, Philad. 1841. A Wrochenschrift far die Gesammte Heilkunde ; and Gazette Medicale, Sept. 26,1836. e Neue Zcitschrift for Geburtskunde, von Busch, d'Outrepont und Ritgen, B. iv. H. ii., Berlin, 1836; and Dunglison's Amer. Med. Intelligencer, p. 275, Nov. 1, 1837. f Opera., Lips. s De Generatione, p. 228. * Tom. i. 310. 376 GENERATION. redder than usual. In six hours, the coverings of the ovarian vesi- cles or vesicles of De Graaf seemed reddish. At the expiration of a day from conception, three vesicles in one of the ovaries, and five in the other, appeared changed, having become opaque and reddish. After twenty-seven, forty, and fifty hours, the cornua of the uterus and the tubes were very red, and one of the tubes had laid hold of the ovary; a vesicle was in the tube, and two in the right cornu of the uterus. These vesicles were as large as mustard seed. They were formed of two membranes, and were filled by a limpid fluid. On the fourth day, the ovary contained only a species of envelope, called, by De Graaf, n follicle: this appeared to be the capsule, which had contained the ovum. The ovum itself was in the cavity of the uterus, had augmented in size, and its two envelopes were very dis- tinct. Here it remained loose until the seventh day, when it formed an adhesion to the uterus. On the ninth day, De Graaf observed a small opaque point, a kind of cloud, in the transparent fluid that filled the ovum. On the tenth day, this point had the shape of a small worm. On the eleventh, the embryo was clearly perceptible; and, from this period, it underwent its full developement, until the thirty-first day, when delivery took place. Malpighi* and Vallisnierib also observed, in their experiments, that after a fecundating copulation, a body was developed at the surface of the ovary, which subsequently burst, and suffered a smaller body to escape. This was laid hold of by the tube, and conveyed by it to the uterus. It is not, however, universally ad- mitted, that this body is the impregnated ovum; some affirming, that it is a sperm similar to that of the male; and others, that it is an amorphous substance, which, after successive developements, becomes the new individual.0 Haller exposed the females of sheep and of other animals to the males on the same day; and killed them at different periods after copulation, for the purpose of detecting the whole series of changes by which the vesicle is detached from the ovary and conveyed to the uterus. Half an hour after copulation, one of the vesicles of the ovary appeared to be prominent; to have on its convexity a red, bloody spot, and to be about to break; in an hour or more, the vesicle gave way, and its interior seemed bleeding and inflamed. What remained of the vesicle in the ovary, and appeared to be its envelope, gradu- ally became inspissated, and converted into a body of a yellowish colour, to which Haller gave the name corpus luteum. The cleft, by which the vesicle escaped, was observable for some time, but, about the eighth day, it disappeared. On the twelfth day, the corpus luteum became pale and began to diminish in size. This it continued to do until the end of gestation; and ultimately became a small, hard, yellowish or blackish substance, which could always be distinguished in the ovarium, by the cicatrix left by it. Its size a De Formatione Pulli in Ovo, Lond. 1673; and De Ovo Incubato, Lond. 1686. b Istoria della Generazione dell'Uorno, Discorsi Academ. iv. Venez. 1722-1726. c Adelon, Physiologie de I'Homme, iv. 74. FECUNDATION. 377 was greater, the nearer the examination was made to the period of conception. In a bitch, for example, on the tenth day, it was half the size of the ovary; yet it proceeded, in that case, from one vesicle only. In multiparous animals, as many corpora lutea existed as foetuses. The experiments of Haller* have been frequently repeated and with similar results. Magendie,b whose trials were made on bitches, observed, that the largest vesicles of the ovary were greatly aug- mented* in size, thirty hours after copulation; and that the tissue of the ovary, surrounding them, had acquired greater consistence, had changed colour, and become of a yellowish-gray. This part was the corpus luteum. It, as well as the vesicles, increased for the next three or four days; and seemed to contain, in its areolae, a white, opaque fluid, similar to milk. The vesicles now successively rup- tured the externa] coat of the ovary, and passed to the surface of the organ, still adhering to it, however, by one side. Their size was sometimes that of a common hazlenut, but no germ was per- ceptible in them. The surface was smooth, and the interior filled with fluid. Whilst they were passing to the uterus, the corpus luteum remained in the ovary, and underwent the changes referred to by Haller. In similar experiments, instituted by MM. Prevost and Dumas,c no change was perceptible in the ovary during the first day after fecundation; but, on the second day, several vesicles enlarged, and continued to do so for the next four or five days, so that, from being two or three millimetres in diameter, they attained a diameter of eight. From the sixth to the eighth day, the vesicles burst, and allowed an ovule to emerge, which often escaped observation, owing to its not being more than half, a millimetre in diameter, but was clearly seen by MM. Prevost and Dumas by the aid of the micro- scope. This part they term ovule, in contradistinction to that deve- loped in the ovary, which they call vesicle. The latter has the appearance, at its surface, of a bloody cleft, into which a probe may be passed; and in this way it can be shown, that the vesicle has an interior cavity, which is the void space left by the ovule after its escape from the Ovarium into the Fallopian tube. On the eighth day, in the bitch, the ovule passes into the uterus. All the ovules do not, however, enter that cavity at the same time;—an interval of three or four days sometimes occurring between them. When they attain the uterus, they are at first free and floating; and, if examined with a microscope magnifying twelve diameters, they seem to consist of a small vesicle, filled with an albuminous, trans- parent fluid. If examined in water, their upper surface has a mammiform appearance, with a white spot on the side. This is the cicatricula. These ovules speedily augment in size, and, on the twelfth day, foetuses can be recognised in them. * Element. Physiologiae, xxix. b Precis de Physiologie, edit, citat. ii. 534. e Annales des Sciences Naturelles, iii. 135. 32* 378 GENERATION. Similar experiments, with like results, have been made by Von Baer,* Seiler,b and others. Von Baer found that in the centre of a granular layer, situate generally towards the most prominent part of the vesicle, to which he gives the name " proligerous disc or layer," discus proligerus, discus vitellinus, stratum proligerum—a very minute spheroidal body exists, which is seldom above 20-0-™ p- ,55 of an inch in diameter. This is the true ovum or ovule of MM. Prevost and Dumas, which is already formed in the ovary prior to fecundation. In the centre of the proligerous disc on the side to- wards the interior of the vesicle, a small rounded prominence, termed cumulus exists, and on the oppo- site side, a small cuplike cavity hollowed out in the cumulus. This a. Granular membrane, b. Proligerous disc. Cavity is for the reception of the c. Ovum. d. Inner wall or ovisac, and outer -,,„„ TU„ v^r,v~;nr.l Cr...*^ t~___ walls of the Graafian vesicle, e. Indusium of OVUm. 1 he marginal figure, from the ovary- Mr. T. Wharton Jones, represents a section of the Graafian vesicle and its contents, showing the situation of the ovum. According to Dr. Martin Barry,c the ovum of mammalia, when completely formed, is situate at first in the centre of the ovisac, where it is supported by an equable diffusion of granules throughout the fluid of the latter. The ovisac, about the same time, begins to acquire a covering or tunic, so that the ovisac is now the inner membrane. The peculiar granules of the Graafian vesicle arrange themselves to form three structures,—the membrana granulosa, of authors, and two structures not hitherto described, one of which Dr. Barry proposes to name tunica granulosa, and the other, which is rather an assemblage of structures than a single structure, retinacula. The tunica granulosa is a spherical covering proper to the ovum, which, at a certain period, in some animals at least, is seen to have tail-like appendages, consisting of granules similar to its own. The retinacula consist of a central mass containing the ovum in its tunica granulosa, and of cords or bands extending from this central mass to the membrana granulosa. These structures, at a certain period, become invested by a membrane. The offices of the retinacula, according to Dr. Barry, appear to be,—first to suspend the ovum in the fluid of the Graafian vesicle,—next to convey it to a certain part of the periphery of this vesicle—and subsequently to retain it in the latter situation, and likewise to promote its expul- * De Ovi Mammalium, &c. Epist. Lips. 1827. b Das Ei und Die Gebarmutter des Menschen, Dresd. 1832; Burdach's Physiologie als Erfahrungswissenschaft, Th. ii. Leipz. 1828; and Purkinie, art Ei in Encvclop Worterb. der Medicin. Wissensch. x. 107, Berl. 1834. « Philosophical Transactions, pp. 301, 341. FECUNDATION. 379 sion from the ovary. The particular part of the periphery of the Graafian vesicle to which the ovum is conveyed is uniformly that directed towards the surface of the ovary. The mass of granules escaping with the ovum on the bursting of a Graafian vesicle under the compressor, is composed chiefly of the tunica granulosa and the ruptured retinacula. The " cumulus" of Professor von Baer, is made up of the parts called, by Dr. Barry, the tunica granulosa, and the central portion of the retinacula; and the bandiike portions, col- lectively, of what Dr. Barry calls the retinacula, mainly contribute to produce the appearance denominated the " flat disc" by Professor von Baer. In the mammalia a thick and highly transparent membrane, according to Dr. Barry, is formed external to the proper membrane of the yolk, whilst the latter is in the ovary. This is the true cho- rion, the inner part of the substance of the chorion, in its early stages, is in a fluid state, so that the yolk-ball moves freely in it, but it subsequently acquires more consistence. There is not any struc- ture corresponding to the chorion in the ovary of other vertebrated animals. The following, in Dr. Barry's opinion, is the order of formation, as to time, of the more prominent parts of the ovum, and the Graafian vesicle in mammalia: 1. The germinal vesicle, with its contents and of its envelope, pe- culiar granules. 2. The proper membrane of the ovisac, which forms around this envelope of granules. 3. The yolk, which forms around the germinal vesicle. 4. The proper membrane of the yolk, which makes its appearance whilst the yolk is still in an incipient state. 5. The chorion. 6. The covering or tunic of the ovisac, and about the same time, the peculiar granules of the ovisac arrange themselves to form— The tunica granulosa, The retinacula, and The membrana granulosa. Such of these structures as are present in the ovary of other verte- brata appear to originate in the same order as to time.* From the above facts, then, we may conclude, that the sperm excites the vesicles in the ovaries to developement; that the ova, within the germinal part, burst their covering, are laid hold of by the Fallopian tube, and conveyed to the uterus, where they remain during the period of gestation. The exact time, required by the ovum or ova to make their way into the uterus, has not been accurately determined. Cruikshankb found, that in rabbits forty-eight hours were necessary. Haighton0 1 Proceedings of the Royal Society, for 1838. b Philosoph. Transactions, for 1797. c Ibid, lxxxvii. 304. 380 GENERATION. divided one of the Fallopian tubes in a rabbit; and, having exposed the animal to the male, he observed that gestation occurred only on the sound side. On making this section after copulation, he found, that if it were executed within the two first days, the descent of the ovules was prevented; but if it were delayed for sixty hours, the ovules had passed through the tube and were in the cavity of the uterus. A case, too, is quoted by writers on this subject, on the authority of a surgeon named Bussieres, who observed an ovoid sac, about the size of a hazlenut and containing an embryo, half in the Fallopian tube and half adherent to the ovary.* The minuteness of the calibre of the Fallopian tube is not as great a stumbling-block in the way of understanding how this pas- sage is effected, as might appear at first sight. The duct is, doubt- less, extremely small in the ordinary state; but it admits of con- siderable dilatation. Magendieb asserts, that he once found it half an inch in diameter. Moreover, the size of the ovum, as we have just seen, is only j^th part of an inch. The period that elapses between a fecundating copulation and the passage of the ovum from the ovarium to the uterus, is different in different animals. In sheep it occurs, according to Hallerc and Kuhlemannd on the seventeenth day. In rabbits, it is uncertain, but occurs generally, on the third or fourth day after copulation;* in bitches on the fifth, according to some, but not till after the lapse of ten or twelve days, according to others ;f and in the human female, perhaps about the same time; yet Mr. Burns infers from analogical evidence, that we should be more justified in the belief that the ovum, in the human female, does not enter the uterus until at least three weeks after conception.5 Maygrier refers to a case of abor- tion twelve days after copulation; the abortment consisting of a vesicle, shaggy on its surface and filled by a transparent fluid. One of the most instructive cases that we possess on this subject is given by Sir Everard Home,h and although as Dr. Granville' has re- marked, it has lately been the fashion to doubt the accuracy of the case, or to esteem it morbid,-1' there is reason to believe it correct, from the circumstance of Mr. Bauer's microscopic examination of the ovulum, and description of its structure corresponding with the more recent discoveries of Professor Boer. A servant-maid, twenty- a Adelon, Physiologie de I'Homme, edit. cit. iv. 77. b Precis, &c. edit. cit. p. 536. c Element. Physiol, viii. 59. & Observ. quasdam circa Negotium Generationis in Ovibus fact. Gotting. 1753. e Recherches sur la Generation des Mammiferes par Coste, Suivies de Recherches sur la Formation des Embryons, par Delpech et Coste, Paris, 1834. f Wagner, Elements of Physiology, by Willis, p. 137, Lond. 1841. « The Principles of Midwifery, &c. 3d edit. p. 132, Lond. 1814. h Philosophical Transactions for 1807, p. 252; and Lectures on Comparative Ana- tomy, iii. 288, Lond. 1823. ' Graphic Illustrations of Abortion, &c. p. vii. Lond. 1834. i Weber's Hildebrandt's Handbuch der Anatomie, iv. 465, Braunschweig, 1832; Dr. Allen Thompson, in art. Generation, Cyclop, of Anat. and Physiol. P. xiii. p. 454, Feb. 1838; and Dr. John Davy, Researches, Physiological and Anatomical, Dunglison's Amer. Med. Libr. Edit. p. 379, Philad. 1840. FECUNDATION. 381 one years of age, had been courted by an officer, who had promised her marriage, in order that he might more easily accomplish his wishes. She was but little in the habit of leaving home, and had not done so for several days, when she requested a fellow-servant to remain in the house, as she was desirous of calling upon a friend, and should be detained some time. This was on the 7th of January, 1817. After an absence of several hours, she returned with a pair of new corsets, and other articles of dress which she had purchased. In the evening she got one of the maid-servants to assist her in trying on the corsets. In the act of lacing them, she complained of considerable general indisposition, which disappeared on taking a little brandy. Next day, she was much indisposed. This was attributed to the catamenia not having made their appearance, although the period had arrived. On the following day, there was a wildness in her manner, and she appeared to suffer great mental distress. Fever supervened, which confined her to her bed. On the 13th, she had an epileptic fit, followed by delirium, which con- tinued till the 15th, when she expired in the forenoon. On making inquiries of her fellow-servants, many circumstances were mentioned which rendered it highly probable, that on the morning of the 7th, when she was immediately on the point of menstruating, her lover had succeeded in gratifying his desires ; and that she had become pregnant on that day, so that, when she died, she was in the seventh or eighth day of impregaation. Dissection showed the uterus to be much larger than in the virgin state arid considerably more vascular. On accurately observing the right ovarium, in company with Mr. Clift, Sir Everard noticed, upon the most prominent part of its outer surface, a small ragged orifice. This induced him to make a longi- tudinal incision in a line close to this orifice, when a canal was found leading to a cavity filled with coagulated blood and surrounded by a narrow yellow margin, in the structure of which the lines had a zig-zag appearance. The cavity of the uterus was then opened, by making an incision through the coats from each angle: and from the point where these incisions met, a third incision was continued down through the os uteri to the vagina. The os uteri w7as found completely blocked up by a plug of mucus, so that nothing could have escaped by the vagina ; the orifices leading to the Fallopian tubes were both open, and the inner surface of the cavity of the uterus was composed of a beautiful efflorescence of coagulable lymph resembling the most delicate moss. By attentive examination, Sir Everard discovered a small, spherical, transparent body con- cealed in this efflorescence, which was the impregnated ovum. This was submitted to the microscopic investigations of Mr. Bauer, who made various drawings of it, and detected two projecting points, which were considered to mark out, even at this early period, and before the ovum was attached to the uterus, the seat of the brain and spinal marrow. This case shows, that an ovum had left the ovarium, and that it was in the interior of the uterus, prior to the seventh or eighth day after impregnation. Weber and Von Baer, have each recorded a case in which there was an opportunity for 382 GENERATION. examining the embryo, probably eight days after a fecundating copu- lation; but no ovum was detected either in the uterus or tubes. On comparing the degree of advancement of the foetus in the ovum, described by different observers, with that of the foetus in the dog, cat, and sheep, at known periods, Dr. Allen Thomson,1! hazards the opinion, that the human ovum does not arrive in the uterus before the eleventh or twelfth day after conception. Valentin, indeed, thinks the twelfth or fourteenth day. From this discrepancy, how- ever, amongst observers, it is manifest that our knowledge on the matter is by no means fixed or definite. But, it has been asked, is it a mere matter of chance, which of the ovarian vesicles shall be fecundated; or are there not some that are riper than.the rest, and that receive by preference, the vivifying influence of the sperm? MM. Prevost and Dumas have shown, that such is the case with oviparous animals. They found, in their experiments, that not only were the vesicles of the ovaries of frogs of different sizes, but that the largest were always first laid, whilst the smallest were not to be deposited until subsequent years. In all the animals, whose eggs were fecundated externally, they seemed evidently prepared or maturated.b We have, too, the most indubitable evidence that birds—although unquestionable virgins —may lay infecund eggs. Analogy would lead us to believe, that something similar may happen to the viviparous animal, and direct observation has confirmed the position. Not longer ago than the year 1808, the existence of the corpora luteain the ovaria was held to be full proof of impregnation. In that year, Charles Angus, Esq. of Liverpool, England, was tried at the Lancaster Assizes, for the murder of Miss Burns, a resident of his house.0 The symptoms previous to her decease, and the appearances observed on dissection were such as to warrant the suspicion that she had been poisoned. The uterine organs were also found to be in such a state as to induce a belief, that she had.been delivered a short time before her death, of a foetus, which had nearly arrived at maturity. It was not, however, until after the trial, that the ovaria were examined, in the presence of a number of physicians, and a corpus luteum was distinctly per- ceived in one of them. The uterus was taken to London and shown to several of the most eminent practitioners there, all of whom appear to have considered that the presence of a corpus luteum proved the fact of pregnancy beyond a doubt.d Such, indeed, is the positive averment of Haller,6 an opinion which was embraced by Haighton/ who maintained that they furnish " incontestable proof" of previous impregnation. It was this belief,—coupled with the fact, that division of the Fallopian tubes, in his experiments, prevented impregnation, whilst corpora lutea were found, notwithstanding, in the ovary,— * Art. Generation, in Cyclop, of Anat. and Physiol. P. xiii. p. 454, Feb. 1838. b Huter, art. Empfangniss, in Encyclopad. Worterb. der Medicin. Wissensch. x. 629, Berlin, 1834. c Edinb. Med. and Surg. Journal, v. 220. d Beck's Medical Jurisprudence, 6th edit. i. 247, New York, 1838. e Element. Physiolog. xxix. 1. f Philosoph. Transact, lxxxvii. 159. FECUNDATION—CORPUS LUTEUM. 383 which led him to the strange conclusion, that the semen penetrates no farther than the uterus, and acts upon the ovaria by sympathy. Sir Everard Home* affirms, that corpora lutea exist independently of impregnation. " Upon examining," says he, " the ovaria of several women, who had died virgins, and in whom the hymen was too perfect to admit of the possibility of impregnation, there were not only distinct corpora lutea, but also small cavities around the edge of the ovarium, evidently left by ova, that had passed out at some former period;" and he affirms, that whenever a female quadruped is in heat, one or more ova pass from the ovarium to the uterus, whether she receives the male or not. This view of the subject appears to have been first propounded by Blumenbach,b who remarks that the state of the ovaria of females, who have died under strong sexual passion, has been found similar to that of rabbits during heat; and he affirms, that in the body of a young woman, eighteen years of age, who had been brought up in a convent, and had every appearance of being a virgin, Vallisnieri found five or six vesicles pushing forward in one ovarium, and the corresponding Fallopian tube redder and larger than usual, as he had frequently observed in animals during heat. Bonnet, he adds, gives the history of a young lady, who died vehemently in love with a man of low station, and whose ovaria were turgid with vesicles of great size. It has been already remarked, under Menstruation, that the periodical recurrence of the function has been supposed to consist in the production and developement of vesicles in the ovary, that is, of a matured ovum which is periodically brought forward either to be expelled with the menstrual flux, or to be destroyed in the ovary; a view which was entertained by Cruikshank, and has been recently urged strongly by Gendrin. Buffon, again, maintained, that instead of the corpus luteum of Haller being the remains of the ovule, it is its rudiment; and that the corpus exists prior to fecundation,—as he, also, found it in the virgin. Lastly, Dr. Blundell0 states, that he has in his possession a preparation, consisting of the ovaries of a young girl, who died of cholera under seventeen years of age, with the hymen, which nearly closed the entrance of the vagina, unbroken. In these ovaries, the corpora lutea are no fewer than four; two of them being a little obscure, but easily perceptible by an experienced eye. The remaining two are very distinct, and differ from the corpus luteum of genuine impregnation merely by their more diminutive size and the less extensive vascularity of the contiguous parts of the ovary. " In every other respect," says Dr. Blundell, •' in colour and form, and the cavity which they contain, their appearance is perfectly natural, indeed, so much so, that 1 occasionally circulate them in a Philosoph. Transact, for 1817 and 1819 ; and Lectures on Compar. Anat. iii. 304. b Comment. Soc. Roy. Scient. Gotting. ix. 128; and Elliotson's edit, of his Physio- logy, 4th edit. p. 468, Lond. 1828. c Researches Physiol, and Pathological, p. 49, Lond. 1825. 384 GENERATION. Fig. 156. Corpus Luteum in the third month. the class-room, as accurate specimens of the luteum upon the small scale." Mr. Stanley* confirms the fact of the corpora lutea of virgins being of a smaller size than those that are the consequences of impreg- nation; and Dr. Montgomeryb says, that he has seen many of these virgin corpora lutea, " as they are unhappily called," and has pre- served several specimens of them, but not in any instance, did they present what he would regard as even an approach to the assem- blage of characters belonging to the true corpus luteum,—the result of impregnation; from which, according to him, they differ in the following particulars:—1. There is no prominence or enlargement of the ovary over them. 2. The external cicatrix is almost always wanting. 3. There are often several of them found in both ovaries, especially in subjects who have died of tubercular diseases, such as phthisis, in which case they appear to be merely depositions of tubercle, and are frequently without any discoverable connexion with the Graafian vesicles. 4. They present no trace whatever of vessels in their substance, of which they are in fact entirely destitute, and of course cannot be injected. 5. Their tex- ture is sometimes so infirm, that it seems to be merely the remains of a coagulum, and at others ap- pears fibro-cellular, like that of the internal structure of the ovary; but never presents the soft, rich, lobulated, and regularly glandular appearance, which Hunter meant to express, when he described them as " tender and friable like glandular flesh." 6. In form they are often triangular, or square, or of some figure bounded by straight lines; and 7. They never present, either the cen- tral cavity, or the radiated or stelliform white line, which results fronyts closure.0 Figures 156 and 157 represent the corpus luteum in the third and at the end of the ninth month respectively. They • are taken from Dr. Montgomery. It is not yet decided at what period the central cavity disappears or closes up to form the stellated line. Dr. Montgomery a Transactions of the Royal College of Physicians of London, vol. vi. b An Exposition of the Signs and Symptoms of Pregnancy, &c. p. 245, Lond. 1837, or Dunglison's Amer. Med. Lib. Edit. Philad. 1839; and art. Signs of Pregnancy and Delivery, in Cyclop, of Pract. Medicine, Lond. 1833. c See Dr. E. Rigby, System of Midwifery (Tweedie's Library of Medicine) p. 10, London, 1841; or American Edit. p. 27, Philad. 1841; and Dr. R. Paterson, Edinb. Med. and Surg. Journ. Jan. 1840. Fig. 157. Corpus Luteum at the end of the ninth month. FECUNDATION—CORPUS LUTEUM. 385 thinks he has invariably found it existing up to the end of the fourth month. He has one specimen in which it was closed in the fifth month, and another in which it was open in the sixth, but later than this he has never found it. The structure of the corpus luteum is of a peculiar kind, arid is not distinctly seen in small animals or in those that have numerous litters; but in the cow, which commonly has only one calf at a birth, it is so large, according to Sir Everard Home,' that, when magnified, the structure can be made out. It is a mass of thin con- volutions, bearing a greater resemblance to those of the brain than to any other organ. Its shape is irregularly oval, with a central cavity, and, in some animals, its substance is of a bright orange- colour, when first exposed. The corpora lutea are found to make their appearance immediately after puberty, and they continue to succeed each other, as the ova are expelled, till the period arrives when impregnation can no longer be accomplished. Sir Everard's theory, regarding these bodies, is, that they are glands, formed pur- posely for the production of ova,—and a similar view is entertained by Seiler',b—that they exist previous to, and are unconnected with, sexual intercourse,—and, when they have fulfilled their office of forming ova, they are removed by absorption, whether the ova be fecundated or not. Fig. 158. Corpora Lutea. Figures, 158, a and b, afford an external and internal view of a human ovary, that did not contain the ovum, from which a child had been developed. It was taken immediately after the child was * Lect. on Comp. Anat. iii. 303. b Das Ei und die Gcbarmutter des Menschen, u. s. w. Dresd. 1832; and Stannius, art. Eierstock, in Encycl. Wnrterb. der Medicin. Wissensch. x. 193, Berl. 1834. See, also, Weber's Hildebrandt's Handbuch der Anatomie, iv. 464, Braunschweig, 1832. vol. ii. 33 386 GENERATION. born. The corpus luteum is nearly of the full size, a and b, Fig. 159, afford an external and internal view Of the ovarium, in which the impregnated ovum had been formed. The latter figure exhibits how much the corpus luteum had been broken down. In it we see a new corpus luteum forming. From all these facts, then, we are perhaps justified in concluding with Sir Everard Home,3 and Messrs. Blundell, Saumarez,b Cuvier, and others,0 that something resembling a corpus luteum may be produced independently even of sexual intercourse, by the mere excitement of high carnal desire, during which it is probable, that the digitated extremity of the Fallopian tube embraces the ovary, a vesicle bursts its covering, and a yellow body remains. The ovule is conveyed along the tube into the uterus, but, being infecund, it undergoes no farther developement there; so that unimpregnated ova may, under such circumstances, be discharged, as we observe in the oviparous animal. Fig. 159. Corpora Lutea. When pregnancy is over, the corpus luteum gradually diminishes in size and disappears. Dr. Montgomery remarks, that the exact period of its total disappearance he is unable to state, but that he has found it distinctly visible so late as the end of five months after delivery at the full time, but not beyond this period. It would appear, therefore, that in a few months after the termination of pregnancy, all » Op. cit iii. 304. b A New System of Physiology, i. 337; see Granville's Graphic Illustrations of Abortion, part vi. Lond. 1834; and Dr. Allen Thomson, in art. Generation, Cyclop. Anat. and Physiol, part xiii. p. 450, for Feb. 1838. c For a history of the opinions entertained at various times regarding the corpus luteum, see Dr. Paterson, Edinb. Med. and Surg. Journal, April, 1841, p. 402. THEORIES. 387 traces of the corpus luteum are lost, and that, consequently, it will be impossible to decide how frequently impregnation has taken place, merely by examining the ovaries.* c. Theories of Generation. We have now endeavoured to demonstrate the part performed by the two sexes in fecundation. We have seen that the material furnished by the male is the sperm; that afforded by the female an ovum. The most difficult topic of inquiry yet remains,—how the new individual results from their commixture? Of the nature of this mysterious process we are indeed profoundly ignorant; and if we could make any comparison between the extent of our ignorance on the different vital phenomena, we should be disposed to decide, that the function of generation is, perhaps, the least intelligible. The new being must be stamped instantaneously as by the die. From the very moment of the admixture of the materials, at a fecundating copulation, the embryo must have within it the powers necessary for its own formation, and under impulses communicated by each parent,—as regards likeness, hereditary predisposition, &c. From this moment the father has no communication with it; yet we know, that it will resemble him in its features and in its predis- positions to certain morbid states,—whilst the mother probably exerts but a slight and indirect control over it afterwards, her office being chiefly to furnish the homunculus with a nidus, in which it may work its own formation, and with the necessary pabulum. We have seen, that even so early as the seventh and eighth day after fecundation, two projecting points—it has been asserted—are ob- served in the ovum, which indicate the future situations of the brain and spinal marrow. Our want of acquaintance with the precise character of this im- penetrable mystery will not, however, excuse us from passing over some of the ingenious hypotheses, that have been entertained on the subject. These have varied according to the views that have prevailed respecting the nature of the sperm; and to the opinions indulged regarding the matter furnished by the ovary. Drelincourt,b who died in 1697, collected as many as two hundred and sixty hypotheses of generation; but they may all, perhaps, be classed under two,—the system of epigenesis and that of evolution. 1. Epigenesis.—According to this system, which is the most ancient of all, the new being is conceived to be built up of materials furnished by both sexes, the particles composing those materials having previously possessed the arrangement necessary for con- stituting it, or having suddenly received such arrangement. Still, it is requisite that these particles should have some controlling agent to regulate their affinity, different from any of the ordinary forces 1 Rigby, op. cit. Eng. Edit. p. 11; Amer. Edit. p. 27, Philad. 1840. b Novem Libelli de Utero, Conceptione, Fcetu, &c. Lugd. Bat. 1632. 388 GENERATION. of matter; and hence a force has been imagined to exist, which has been termed cosmic, plastic, essential, nisus formativus—ihe B i 1 d u n g s t r i e b of the Germans—force of formation, &c. Hippocrates* maintains, that each of the two sexes possesses two kinds of seed, formed by the superfluous nutriment, and by fluids constituted of materials proceeding from all parts of the body, and especially from the most essential,—the nervous. Of these two seeds, the stronger begets males, the weaker females. In the act of generation, these seeds become mixed in the uterus, and by the influence of the heat of that organ, they form the new individual —by a kind of animal crystallization—male or female, according to the predominance of the stronger or the weaker seed. Aristotleb thought that it is not by seed that the female participates in generation, but by the menstrual blood. This blood he conceived to be the basis of the new individual, and the principles furnished by the male to communicate to it the vital movement, and to fashion it. Empedocles, Epicurus, and various other ancient physiologists, contended, that the male and female respectively contribute a seminal fluid, which equally co-operate in the generation and de- velopement of the foetus, and that it belongs to the male or female sex, or resembles more closely the father or the mother, according as the orgasm of the one or the other predominates, or is accompa- nied by a more copious discharge.0 Lactantius, in quoting the views of Aristotle on generation, fanci- fully affirms, that the right side of the uterus is the proper chamber of the male foetus, and the left of the female,—a belief, which ap- pears to be still prevalent amongst the vulgar, in many parts of Great Britain. But he adds, if the male or stronger semen should, by mistake, enter the left side of the uterus, a male child may still be conceived; yet as it occupies the female department, its voice, face, &c. will be effeminate. On the contrary^if the weaker or female seed should flow into the right side of the uterus, and a female foetus be engendered, it will exhibit evidences of a masculine character. The idea of Aristotle, with regard to the menstrual blood, has met with few partisans, and is undeserving of notice. That of Hippo- crates, notwithstanding the objections which we now know to apply to it,—that the female furnishes no sperm, and that the ovaria are probably in no respect analogous to the testes of the male,—has had numerous supporters amongst the moderns, being modified to suit the scientific ideas of the time, and of the individual. Descartes, for example, considered the new being to arise from a kind of fer- mentation of the seed furnished by both sexes. Pascal, that the sperm of the male is acid, and that of the female alkaline; and that * Trtpt yotxt; in Oper. Omnia, edit. A. Foesio. Genev. 1657-1662. b De Generatione Animalium, &c. i. 19. 0 " Semper enim partus duplici de semine constat; Atque utrique simile est magis id quodeumque creatur." Lucret. lib. iv. THEORIES—EPIGENESIS. 389 they combine to form the embryo. Maupertuis* maintained, that, in each seed, parts exist, adapted for the formation of every organ of the body, and that, at the time of the union of the seed in a fecundating copulation, each of the parts is properly attracted and aggregated by a kind of crystallization.b The celebrated hypothesis of the eloquent but too enthusiastic Buffon0 is but a modification of the Hippocratic doctrine of epige- nesis. According to him, there exist in nature two kinds of matter, —the living and the dead; the former perpetually changing during life, and consisting of an infinite number of small, incorruptible par- ticles or primordial monads, which he called organic molecules. These molecules, by combining in greater or less quantity with dead matter, form all organized bodies; and, without undergoing destruc- tion, are incessantly passing from vegetables to animals, in the nutrition of the latter, and are returned from the animal to the vege- table by the death and putrefaction of the former. These organic molecules, during the period of growth, are appropriated to the developement of the individual; but, as soon as he has acquired his full size, the superfluous molecules are sent into depot in the genital organs, each molecule being invested with the shape of the part sending it. In this way he conceived the seed of both sexes to be formed of molecules obtained from every part of the system. In the commixture of the seeds, during a fecundating copulation, the same force that assimilates the organic molecules to the parts of the body for their nourishment and increase, causes them, in this hypothesis, to congregate for the formation of the new individual; and, according as the molecules of the male or female predominate, so is the embryo male or female. The ingenuity of this doctrine was most captivating; and it appeared so well adapted for the explanation of many of the phenomena of generation, that it had numerous and respectable votaries. It accounted for the circumstance of procreation being impracticable, until the system had undergone its great develope- ment at puberty. It explained why excessive indulgence in venery occasions emaciation and exhaustion; and why, on the other hand, the castrated animal is disposed to obesity,—the depot having been removed by the mutilation. The resemblance of the child to one parent rather than to the other was supposed to be owing to the one furnishing a greater proportion of organic molecules than the other; and as more males than females are born, the circumstance was ascribed to the male being usually stronger, and therefore furnishing a stronger seed, or more of it. Prior to this hypothesis, Leeuenhoekd had discovered what he considered to be spermatic animalcules in the semen; but Buffon contested their animalcular nature, and regarded them as his vital particles or organic molecules; whilst he looked upon the ovarian * Venus Physique, Paris, 1751. b Physiologie de I'Homme, iv. 85, Paris, 1829. c Histoire Naturelle, torn. xvii. &c, Paris, 1799. d Arcana Naturee, Lugd. Bat. 1685. 33* 390 GENERATION. vesicle as the capsule that contained the sperm of the female. The opinions of Buffon were slightly modified by Blumenbach,* and by Darwin.b The former, like Buffon, divided matter into two kinds, possessing properties essentially different from each other;— the inorganic and the organized; the latter possessing a peculiar creative or formative effort, which he called Bildungstrieb or nisus formativus,—a principle in many respects resembling gravita- tion, and endowing every organ, as soon as it acquires structure, with a vita propria. This force he conceived to preside over the arrangement of the materials, furnished by the two sexes in gene- ration. Darwin preferred to the term organic molecules that of vital germs, which he says are of two kinds, according as they are secreted or provided by male or female organs, whether animal or vegetable. In the subdivision, however, of the germs the term molecule is retained; but it is limited to those of the female; the vital germs or particles, secreted by the female organs of a bud or flower, or the female particles of an animal, being denominated by him molecules with formative propensities; whilst those secreted from the male organs are termed fibrils with formative appetencies. To the fibrils he assigns a higher degree of organization than to the molecules. Both, however, he asserts, have a propensity or appetency to form or create, and "they reciprocally stimulate and embrace each other and instantly coalesce; and may thus popularly be compared to the double affinities of chemistry." Subtile as these hypotheses are, they are open to forcible objec- tions of which a few only will suffice. The notion of this occult force is identical with that, which, we shall see hereafter, has pre- vailed as regards life in general, and it leaves the subject in the same obscurity as ever. What do the terms plastic, cosmic, or vege- tative force, or Bildungstrieb express, which is not equally con- veyed by vital force,—that mysterious property, on which so many unfathomable processes of the animal body are dependent, and of the nature or essence of which we know absolutely nothing? The objection, urged against the doctrine of Hippocrates,—that we have no evidence of the existence of female sperm—applies equally to the hypotheses that have been founded upon it; and even were we to grant, that the ovarium is a receptacle for female sperm, the idea, that such sperm is constituted of organic molecules, derived from every part of the body, would still be entirely gratuitous. We have no facts to demonstrate the affirmative; whilst there are many circum- stances, that favour the negative. The individual, for example, who has lost some part of his person—nose, eye, or ear, or has had a limb amputated, still begets perfect children; yet whence can the molecules, in such cases, have been obtained 1 It is true, that if the mutilation affect but one parent, the organic molecules of the lost part may still exist in the seed of the other; but we ought, at least, to expect » Ueber den Bildungstrieb, Gotting. 1791; Comment. Societat. Gotting. torn, viii.; and Elliotson's Blumenbach's Physiology, 4th edit. p. 490, Lond. 1828. b Zoonomia, Lond. 1796. THEORIES—EVOLUTION. 391 the part to be less perfectly formed in the embryo, which it is not. Where two docked horses are made to engender, the result ought, a fortiori, to be imperfect, as the organic molecules of the tail could not be furnished by either parent, yet we find the colt, in such cases, perfect in this appendage. An elucidative case is also afforded by the foetus. If we admit the possibility of organic molecules con- stituting those parts that exist in the parents, how can we account for the formation of such as are peculiar to foetal existence. Whence are the organic molecules of the navel-string, or of the umbilical vein, or of the ductus venosus, or the ductus arteriosus, or the umbilical arteries obtained ? These and other objections have led to the abandonment of the theory of Buffon, which remains merely as a monument of the author's ingenuity and elevation of fancy. 2. Evolution. According to this theory, the new individual pre- exists in some shape in one of the sexes, but requires to be vivified by the other, in the act of generation; after which it commences the series of developements or evolutions, which lead to the forma- tion of an independent being.a The great differences of sentiment, that have prevailed under this view, have been owing to the part which each sex has been conceived to play in the function. Some have considered the germ to exist in the ovary, and to require the vivifying influence of the male sperm to cause its evolution. Others have conceived the male sperm to contain the rudiments of the new being, and the female to afford it merely a nidus, and pabulum during its developement. The former class of physiologists have been called ovarists;—the lattter spermatists, seminists, and animalculisls. The ovarists maintain, that the part furnished by the female is an ovum from the ovary; and this ovum they conceive to be formed of an embryo and of particular organs for the nutrition and first deve- lopement of the embryo; and adapted for becoming, after a series of changes or evolutions, a being similar to the one whence it has emanated. The hypothesis was suggested by the fact, that in many animals but a single individual is necessary for reproduction; and it is easier, perhaps, to conceive this individual to be female than male; as well as by what is noticed in many oviparous animals. In these, the part, furnished by the female, is manifestly an ovum or egg; and in many, such egg is laid before the union of the sexes, and is fecundated, as we have seen, externally. By analogy, the inference was drawn, that this may happen to the viviparous animal also. The notion is said, but erroneously, to have been first of all advanced by Joseph de Aromatariis.b It was developed by Harvey,0 who strenuously maintained the doctrine omne vivum ex ovo. The 1 C. Windischmann, art. Evolutions Theorie, Encylopad. Worterb. der Medicinisch. Wissensch. xi. 615, Berlin, 1834. b Epist. de Generatione Plantarum ex Seminibus, Venet. 1625. c Exercitationes de Generatione Animalium, Lond. 1651. 392 GENERATION. anatomical examinations of Sylvius, Vesalius, Fallopius, De Graaf,8 Malpighi,b Vallisnieri0 and others,—by showing, that what had been previously regarded as female testes, and had been so called, were organs containing minute vesicles or ova, and hence termed, by Steno, ovaria,—were strong confirmations of this view, and startling objections to the ancient theory of epigenesis; and the problem appeared to be demonstrated, when it was discovered that the vesicle, or ovum leaves the ovarium, and passes through the Fallopian tube to the uterus. The chief arguments that have been adduced in favour of this doctrine are:—First. The difficulty of conceiving the formation, ab origine, of an organized body, as no one part can exist without the simultaneous existence of others. Secondly. The existence of the germ prior to fecundation in many living beings. In plants, for example, the grain exists in a rudimental state in the flower, before the pollen, which has to fecundate it, has attained maturity. In birds, too, the egg must pre-exist, as we find that those, which have never had intercourse with the male, can yet lay. This is more strikingly manifest in many fishes, and in the balracia or frog kind; where the egg is not fecundated until after extrusion. Spallanzani, moreover, asserts, that he could distinguish the pre- sence of the tadpole in the unfecundated ova of the frog; and Haller, that of the chick in the infecund egg; at least he has seen them containing the yolk, which, in his view, is but a dependence of the intestine of the foetus, and if the yolk exists, the chick exists also. Thirdly. The fact, before referred to, that in certain animals, a single copulation is capable of fecundating several successive generations. In these cases, it is argued, the germ of the different generations must have existed in the first. Fourthly. The fact of natural and accidental encasings, inclusions, or emboitements; as in the bulb of the hyacinth, in which the rudiments of the flower are distinguishable; in the buds of trees, in which the branches, leaves, and flowers, have been detected in miniature, and greatly convoluted; in the jaws of certain animals, in which the germs of different series of teeth can be detected; in the volvox, a transparent animal, which exhibits several young ones encased in each other; in the common egg, which occasionally has another within it; and in the instances on record, in which human foetuses have been found in the bodies of youths, of which there is a striking example in the Musuem of the Royal College of Surgeons of London; and a simi- lar case in a boy of fourteen years of age, has been related by Dupuytren. Recently, a most singular case of the kind occurred to M. Velpeau.d A tumour was removed from the scrotum of a young man, aged 27, which was found to contain almost all the elements of a human body. Its exterior was evidently tegumentary, and the greater part of its substance was a mixture of lamellae and fibres » De Organis Mulierum, &c, Lugd. Bat. 1672. b Append, ad Opera Omnia, Lugd. Bat. 1687. c Istoria della Generazione dell 'Uomo. Discorsi Acad, i.-iv. Venez 1722-1726 i Gazette Medicale, Fev. 15,1840. THEORIES—EVOLUTION. 393 like cellular, adipose, muscular and fibrous tissues. In the interior there were two cysts filled with a substance like albumen or the vitreous humour •" another cyst, as large as a partridge's egg, con- tained a greenish semi-fluid matter like meconium; and a fourth contained a dirty yellow grumous mass surrounded by hairs: the mass consisted of sebaceous matter and scales of epidermis; the hairs had no bulbs. A tuft of hair, which protruded externally from a kind of ulcer at the posterior part,—and which, with the fact of the tumour being congenital, induced M. Velpeau to consider it to be foetal,—proceeded from the cyst that contained the me- conium-like substance, and gave the opening into it somewhat the appearance of an anus. In the midst of all these, numerous per- fectly organized portions of a skeleton were found, consisting of bones resembling more or less the clavicle, scapula, humerus, sphe- noid bone, sacrum, portions of vertebrae, and others whose names could not be determined. A peculiarity of this case of monstrosity by inclusion was, that the second foetus did not act as a foreign body in the other, but had a separate and independent existence and power of growth within itself. The tumour had its own colour and consistence, and a sensibility entirely independent of the person to whom it was attached. The man himself pierced it several times with a knife without feeling the least pain; and yet, all the wounds that were made in it bled, inflamed and cicatrized like those of any other part of the body. Perhaps, the explanation of these extraordinary cases by Dr. Blun- dell* is as philosophical as any that could be devised. A seed or egg, he remarks, though fecundated, may lie for years without being evolved. A serpent may become inclosed under the eggshell of the goose; the shell probably forming over it as the animal lies in the oviduct of the bird. These facts Dr. Blundell applies to the pheno- menon in question. When the boy was begotten, a twin was begotten at the same time,—but, while the former underwent his developement in the usual manner, the impregnated ovum of his companion lay dormant, and, unresistingly, became closed up within the fraternal structure, as the viper in the eggshell. For a few years, these living rudiments generally lie quiet within the body, and ultimately become developed so as to occasion the death of both. " The boy," he remarks—speaking of one of the cases—" became pregnant with his twin brother, his abdomen formed the receptacle, where, as in the nest of a bird, the formation was accomplished." Cases of this kind of arrest of developement occasionally occur, where two or more ova are fecundated at the same time, or in succession. To this we shall refer under Superfcetation.b s Principles and Practice of Obstetricy, edited by Dr. Castle, Lond. 1834; American edition, Washington. . b See a case of " Abdominal Enadelphia or Monstrosity by Inclusion," by M. Roux, du Var, with reflections by M. Geoffroy Saint-Hilaire, in Gazette Medicale de Paris, No. 35,'Aont 27, 1836; and Researches on Monstrosity by Inclusion in Animals, sug- gested'by a case of the kind in a Human Foetus, by M. Charvet, in Archives Gene- rales de Medecine, Nov. 1838. 394 GENERATION. Fifthly. The fact of the various metamorphoses that take place in certain animals. Of these we have the most familiar instances in the batracia, and in insects. The forms which they have succes- sively to assume are evidently encased. In the chrysalis, the outlines of the form of the future butterfly are apparent; and in the larva we observe those of the chrysalis. The frog is also apparent under the skin of the tadpole. 'Sixthly. The fact of arti- ficial fecundation, which has been regarded, by the ovarists, as one of the strongest proofs of their theory; the quantity of sperm employed, as in the experiments of Spallanzani, already detailed, being too small, in their opinion, to assist in the formation of the new individual, except as a vivifying material. Lastly. They invoke the circumstance of partial reproduction, of which all living bodies afford more or less manifest examples;—as the reproduction of the hair and nails in man; of the teeth in the rodentia;—of the tail in the lizard; of the claw in the lobster; of the head in the snail, &c, &c. All these phenomena are, according to them, owing to each part possessing, within itself, germs destined for its repro- duction, and requiring only favourable circumstances for their developement. The partisans of the doctrine of epigenesis, how- ever, consider these last facts as opposed to the views of the ova- rists ; and they maintain, that, in such cases, there is throughout a fresh formation. The chief objections, that have been urged against the hypothesis of the ovarists, are:—First. The resemblance of the child to the father—a subjeet which we shall refer to presently. The ovarists cannot of course deny that such resemblance exists; and they ascribe it to the modifying influence exerted by the male sperm, but without being able to explain the nature of such influence. They affirm, however, that the likeness to the mother is more frequent and evident. Certain cases of resemblance are, indeed, weighty stum- bling blocks to ovism, or to the doctrine of a pre-existent germ in the female. It is a well-known fact, that six-fingered men will beget six-fingered children. How can we explain this upon the principle of the pre-existence of the germ in the female, and of the part played by the male sperm being simply that of a vivificative agent; and must we suppose, in the case of monstrosities, that such germs have been originally monstrous ? Secondly. The production of hybrids is one of the strongest counter-arguments. They are produced by the union of the male and female of different species. Of these, the mule is the most familiar instance—the product of the ass and the mare. This strikingly participates in the qualities of both parents, and, consequently, the pre-existing germ in the female must have been more than vivified by the sexual intercourse. Its structure must have been altogether changed, and all the germs of its future offspring annihilated, as the mule is seldom fertife. If a white woman marries a negro, the child is a mulatto; and if the successive generations of this woman are continually united to negroes, the progeny will ultimately become entirely black; or, at THEORIES—EVOLUTION. 395 least the white admixture will escape recognition. As a general rule, the offspring of different races has an intermediate tint between that of the parents: and the proportions of white and black blood, in different admixtures, have even been subjected to calculation, in countries where negroes are common. The following table repre- sents these proportions, according to the principles sanctioned by custom. Parents. Negro and white, White and mulatto, Negro and mulatto, White and terceron, Negro and terceron, White and quarteron, Negro and quarteron, The two last are considered to be respectively white and black; and of these the former are white by law, and consequently free, in the British West India Islands.* All these cases exhibit the influence exerted by the father upon the character of the offspring, and are great difficulties in the way of supposing that the male sperm is simply a vivifier of the germ pre-existing in the female.b Thirdly. The doctrine of the ovarists does not account for the greater degree of fertility of cultivated plants and of domesticated animals. Fourthly. The changes, induced by the succession of ages on the animal and vegetable species inhabiting the surface of the globe, have been adduced against this hypothesis. In examining the geological charac- ter of the various strata that compose the earth, it has been observed by geologists that many of these contain imbedded the fossil remains of animals and vegetables. Now, those rocks on which others rest are the oldest, and the successive strata above these are more and more modern, and it has been found that the organic fossil remains in the different strata differ more and more from the present inha- bitants of the surface of the globe in proportion to the depth we descend; and that the remains of those beings, that have always been the companions of man, are found only in the most recent of the alluvial deposits,—in the upper crust of the earth. In the older rocks the impressions are chiefly of the less perfect plants—as the ferns and reeds; and of the lower animals—the remains of shells and corals; whilst fish are uncommon. In the more recent strata, the remains of reptiles, birds and quadrupeds are apparent, but all of them differ essentially from the existing kinds, and in none of the formations of more ancient date has the fossil human 1 Lectures on Physiology, Zoology, and the Natural History of Man, p. 299, Lond. 1819. b Rudolphi, Grundriss der Physiologie, u. s. w. B. i. s. 54, Berl. 1823; Burdach, Phy- siologie als Erfahrungswissenschaft, u. s. w., B. i. s. 516; and Berndt, art. Bastard- thiere in Enc. Worterb. u. s. w., B. v. s. 53, Berl. 1830. Offspring. mulatto, Degree of Mixture. \ white, i black. terceron, griffo or zambo, j or black terceron, \ 3 4 [ 1 4" 4 ___ 3 4 quarteron, black quarteron, quinteron, black quinteron, 7 1 1 5 T6" 1 1 6 __ 1 ___ ___ 7 ___ 1 ___ 76 ___ 15 ___ 16 396 GENERATION. skeleton been met with. The pretended human bones, conveyed by Spallanzani from the Island of Cerigo—the ancient Cythera—are not those of the human species any more than the bones of the Homo diluvii testis of Scheuchzer; and the skeleton of the savage Galibi, conveyed from Guadaloupe and deposited in the British Museum, is imbedded in a calcareous earth of modern formation. From these facts it has been concluded, that man is of a date posterior to ani- mals, in all countries where fossil bones have been discovered.* These singular facts, furnished by modern geological inquiry, have been attempted to be explained by the supposition, that the present races of animals are the descendants of those whose remains are met with in the rocks, and that their difference of character may have arisen from some change in the physical constitution of the atmosphere, or of the surface of the earth, producing a corre- sponding change in the forms of organized beings. It has been pro- perly remarked, however, by Dr. Fleming,b that the effect of circum- stances on the appearance of living beings is circumscribed within certain limits, so that no transmutation of species was ever ascer- tained to have taken place, whilst the fossil species differ as much from the recent kinds, as the last do from each other; and he adds, that it remains for the abettors of the opinion to connect the extinct with the living races, by ascertaining the intermediate links or transitions. This will probably ever be impracticable. The dif- ference, indeed, between the extinct and the living races is in several cases so extreme, that many naturalists have preferred believing in the occasional formation of new organized beings. Linnaeus was bold enough to affirm, that, in his time, more species of vegetables were in existence than in antiquity, and hence, that new vegetable species must necessarily have been ushered into being; and Wildenow embraced the views of Linnaeus. De Lamarck,0 one of the most distinguished naturalists of the day, openly professes his belief, that both animals and vegetables are incessantly changing under the influence of climate, food, domestication, the crossing of breeds, &c, and he remarks, that if the species now in existence appear to us fixed in their characters, it is because the circumstances that modify those species require an enormous time for action, and would consequently require numerous generations to establish the fact. The manifest effect of climate, food,&c. on vegetables and animals, he thinks, precludes the possibility of denying those changes on theoretical considerations; and what we call lost species are, in his view, only the actual species before they experienced modification. It is proper, however, to observe, that the representations on the wall of one of the sepulchres in the valley of Beban el Molook, at Thebes, which are regarded by ChampoUion as having been executed upwards of two thousand years before the Christian era, enable the a Principles of Geology, by Charles Lyell, Esq. F. R. S. i. 241, 4th edit. Lond. 1835. b Philosophy of Zoology, i. 26, Edinb. 1?>22. c Philosophic Zoologique, edit. cit. torn. i.; and Lyell's Principles of Geology, op. citat. ii. 407. THEORIES—EVOLUTION. 397 features of the Jew and of the negro, amongst others, to be recog- nised as easily as the representations of their descendants of the present day; "so that, for the space of at least three thousand eight hundred years, no modification of the kind referred to by Lamarck seems to have occurred in the human species. Another explanation has been offered for these geological facts, and for the rotation, which we observe in the vegetable occupants of particular soils in successive years. It has been supposed, that as the seeds of plants and the ova of certain animals are so exces- sively minute as to penetrate wherever water or air can enter; and as they are capable of retaining the vital principle for an indefinite length of time, of which we have many proofs, and of undergoing evolution whenever circumstances are favourable, the crust of the earth may be regarded as a receptacle of germs, each of which is ready to expand into vegetable or animal forms, on the occurrence of conditions necessary for their developement. This is the hypo- thesis of panspermia or dissemination of germs, according to which the germs of the ferns and reeds were first expanded, and after- wards those of the staminiferous or more perfect vegetables; and, in the animal kingdom, first the zoophyte, and gradually the being more elevated in the scale; the organized bodies of the first period flourishing, so long as the circumstances, favourable to their deve- lopement, continued, and then making way for the evolution of their successors,—the changes effected in the soil by the growth and decay of the former probably favouring the evolution of the latter; which, again, retained possession of the soil so long as cir- cumstances were propitious.* The changes that take place in forest vegetation are favourable to this doctrine. If, in Virginia, the forest trees be removed so as to make way for other growth, and the ground be prepared for the first cultivation, the Phytolacca decandra or poke, which was not previously perceptible on the land, usurps the whole surface. When Mr. Madison went with Gen. Lafayette to the Indian treaty, they discovered, that wherever trees had been blown down by a hurri- cane, in the spring, the white clover had sprung up in abundance, although the spot was many miles distant from any cleared land; and it°has often been remarked, that where, during a drought in the spring, the woods have taken fire and the surface of the ground has been torrefied, the water-weed has made its appearance in im- mense quantities, and occupied the burnt surface. The late Judge Peters, having occasion to cut ditches on his land, in the western part of Pennsylvania, was surprised to find every subterraneous tree that was met with, different from those at the time occupving the surface; and Mr. Madison informed the author, that in the "space of sixty or seventy years, he had noticed the fol- lowing spontaneous rotation of vegetables:—1. Mayweed; 2. Blue a Fleming, op citat. i. 28; and Purkinje, art. Erzeugung, in Encyl. Worterb. der Medicin. Wissensch. xi., 537, Berlin, 1834. vol. n. 34 398 GENERATION. centaury; 3. Bottle-brush-grass; 4. Broomstraw; 5. White clover; 6. Wild carrot; and the last is now giving way to the blue grass.* The doctrine of panspermia is, however, totally inapplicable to the viviparous animal, in which the ovum is hatched within the body, and which, consequently, continues to live after the birth of its pro- geny ; and the facts furnished us by geology, seem clearly to show, that the developement of the animal kingdom has been successive, not simultaneous; but, under what circumstances the different ani- mals were successively ushered into being, we know not. Lastly, as regards the ovarists themselves ;—they differ in essen- tial points: whilst some are favourable to the doctrine of the dissemi- nation of germs, believing, as we have seen, that ova or germs are disseminated over all space, and that they only undergo develope- ment under favourable circumstances, as when they meet with bodies capable of retaining them, and causing their growth, or which resemble themselves; others assert, that the germs are in- closed in each other, and that they are successively aroused .from their torpor, and called into life, by the influence of the seminal fluid; so that not only did the ovary of the first female contain the ova of all the children she had, but one only of these ova contained the whole of the human race. This was the celebrated system of emboilement des germes or encasing of germs, of which Bonnetb was the propounder, and Spallanzani the promulgator. Yet how monstrous for us to believe, that the first female had, within her, the germs of all mankind, born, and to be born; or to conceive, that a grain of Indian corn contains within it all the seed, that may hereafter result from its culture. In this strange hypothesis—as Professor Elliotson0 observes—there must have been an uncommon store of germs prepared at the beginning, for the ovaria of a single sturgeon have contained 1,467,500 ova.d Many of the ovarists, again, and they alone who have any thing like probability in their favour, believe, that the female forms her own ova, as the male forms his own sperm, by a secretory action; and, so far as the female is concerned in the generative process, we shall find that this is the only philosophical view; but it is imperfect in not admit- ting of more than a vivifying action in the materials furnished by the male. About the middle of the seventeenth century, Bamme or Van Hammen, Leeuenhoek,6 and Hartsbker,f discovered a prodigious number of small moving bodies in the sperm of animals, which they regarded as animalcules.^ This gave rise to a new system of ■ Prichard, Researches on the Physical History of Man, i. 39 ; and Carpenter, Principles of General and Comparative Physiology, p. 141, London, 1839. b Considerat. sur les Corps. Organises, vol. i. and ii., Amst. 1762. c Blumenbach's Physiology, by Elliotson, 4th edit. p. 494, Lond. 1828. d Petit, Memoir, de I'Academ. des Sciences, 1733. e Oper. iii. 285, and iv. 169, Lugd. Bat. 1722. f Journal des Scavans, pour 1678; and Essai de Dioptrique, p. 227, Paris, 1694. s Haller, Element. Physiol, vol. vii. 27; Rudolphi, art. Animalcul'a Seminalia,.in Encyclopad. Worterb. der Medicin. Wissenschaft. ii. 597, Berlin, 1828; and Sprengel, Histoire de Medecine, par Jourdan, iv. 309, Paris, 1815. THEORIES—EVOLUTION. 399 generation, directly the reverse of that of Harvey,—that of genera- tion ab animalculo maris. As, in the Harveian doctrine, the germ was conceived to be furnished by the mother and the vivifying influence to be alone exerted by the male, so, in this doctrine, the entire formation was regarded as the work of the father, the mother affording nothing more than a nidus, and appropriate pabulum for the homunculus or rudimental foetus.* The spermatic doctrine was soon embraced by Boerhaave, Keill, Cheyne, Wolff, Lieutaud and others.b The pre-existing germ was accordingly now referred exclusively to the male; and, by some, the doctrine of emboitemenl or encasing was extended to it. In support of this hypothesis, the spermatists urged,—that the ani- malcules they discovered, were peculiar to the semen, and that they exist in the sperm of all animals capable of generation; that they differ in different species, but are always identical in the sperm of the same animal, and in that of individuals of the same species; that they are not perceptible in the sperm of any animal until the age at which generation is practicable, whilst they are wanting in infancy and decrepitude; that their number is so considerable, that a drop of the sperm of a cock, scarcely equal in size to a grain of sand, contains 50,000; and lastly, that their minute size is no obstacle to the sup- position, that generation is accomplished by them; the disproportion between the trees of our forest and the seed producing them being nearly if not entirely as great as that between the animalcule and the being it has to develope. Leeuenhoek estimated the dimensions of those of the frog at about the l-10,000th part of a human hair, and that the milt of a cod may contain 15,000,000,000,000,000 of them. The difficulty with the spermatists or animalculists was to deter- mine the mode in which the homunculus attains the ovary, and effects the work of reproduction. Whilst some asserted it to be only requisite, that the sperm should attain the uterus, whither it attracted the ovum from the ovarium; others imagined that the animalcule travelled along the Fallopian tube to the ovary; entered one of the ovarian vesicles; shut itself up there for some time, and then re- turned into the cavity of the uterus, to undergo its first developement, through the medium of the nutritive substance contained in the vesicle; and a celebrated pupil of Leeuenhoek even affirmed, that he not only saw these animalcules under the shape of the tadpole, as they were generally described, but that he could trace one of them, bursting through the envelope that retained it, and exhibiting two arms, two legs, a human head and a heart!0 Although this doctrine was extremely captivating, and, for a time, kept the minds of many eminent philosophers in a state of delusive enthusiasm; insomuch that Dr. Thomas Morgan/ in a work, pub- * Mohrenheim, Nova Conceptionis atque Generationis Theoria. Regiom. 1794. b Bostock's Physiology, 3d edit. p. 642, Lond. 1836. c Adelon, Physiologie de I'Homme, edit. cit. iv. 94. d Mechanical Practice of Physic, Lond. 1735. 400 GENERATION. lished in 1731, thus expresses himself regarding it:—"That all generation is from an animalculum pre-existing in semine maris, is so evident in fact, and so well confirmed by experience and observation, that I know of no learned men, who in the least doubt of it;" it was, subsequently, strongly-objected to by many; and the great fact on which it rested—the very existence of the spermatic animalcules—was, and is, strenuously contested. Linnaeus* discredited the observations of Leeuenhoek; Verheyen denied the existence of the animalcules, and undertook to demon- strate that the motion, supposed to be traced in them, was a mere microscopic delusion :—whilst Needhamb and Buffon regarded them as organic molecules.0 Of late years, MM. Prevost and Dumasd have directed their attention to the subject; and their investigations, as on every other topic of physiological inquiry, are worthy of the deepest regard. The results of their examinations have led them to confirm the existence of these animalcules, and likewise to consider them as the direct agents of fecundation. By means of the microscope they detected them in all the animals, whose sperm they examined, and these were numerous. Whether the fluid was observed after its excretion by a living animal, or after its death, in the vas deferens or in the testicle, the animalcules were detected in it with equal facility. They consider these bodies to be characteristic of the sperm, as they found them only in that secretion; being wanting in every other humour of the body, even in those that are excreted with the sperm, as the fluids of the prostate, and of the glands of Cowper; and although similar in shape, and size, and in the character of their locomotion in the individuals of the same species, they are of various shapes and dimensions in different species. In passing through the series of genital organs these animalcules experience no change, being as perfect in the testicle as at the time of their excretion; and they controvert the remark of Leeuenhoek, that they are met with apparently of different ages. The animalcules were manifestly endowed with spontaneous motion, which gradually ceased,—in the sperm obtained during life by ejaculation, in the course of two or three hours; in that taken from the vessels after death, in fifteen or twenty minutes, and in eighteen or twenty hours, when left in its own vessels after death. In farther proof of the position, that these animalcules are the fecun- dating agents, MM. Prevost and Dumas assert, that they are only met with whilst reproduction is practicable:—that, in the human species, they are not found in infancy or decrepitude; and, in the majority of birds, are only apparent in the sperm, at the periods • Bostock's Physiology, 3d edit. p. 643, London, 1836. b New Microscopical Discoveries, Lond. 1745. c Haller, Element. Physiologies, xxvii. a Mem. de la Societe Physique de Geneve, i. 180, and Annales des Sciences Na- turelles, torn. i. and ii. THEORIES—EVOLUTION. 401 fixed for their copulation; facts which, in their opinion, show, that they are not mere infusory animalcules. MM. Prevost and Dumas moreover affirm, that they appeared to be connected with the physiological condition of the animal furnishing them; their motions being rapid or languishing, accord- ing as the animal was young or old, or in a state of health or dis- ease. They state, also, that in their experiments on the ova of the mammiferous animal they observed animalcules filling the cornua of the uterus, and remaining there alive and moving, until the ovule descended into that organ, when they gradually disappeared; and they argue in favour of the influence of these animalcules;—that the positive contact of the sperm is necessary for fecundation, and that the aura seminis is totally insufficient;—that the sperm, in twenty- four hours, loses its fecundating property, and it requires about this time for the animalcules to gradually cease their movements and perish; and, lastly, that having destroyed the animalcules in the sperm, the fluid lost its fecundating property. One of these experi- ments consisted in killing all the animalcules in a spermatized fluid, —whose fecundating power had been previously tested,—by re- peated discharges of a Leyden phial: another consisted in placing a spermatized fluid on a quintuple filter, and repeating this until all the animalcules were retained in the filter; when it was found, that the fluid, which passed through, had no fecundating power, whilst the portion retained by the filter had the full faculty; a result that had been obtained by Spallanzani, who found, besides, that he was capable of effecting fecundation with water in-which the papers, used as filters, had been washed. Recently, M. Donne* has investi- gated the mode in which the zoospermes are affected in the blood, the milk, the vaginal and uterine mucus in the healthy state, in the purulent matter of chancres, and of blennorrhoea, in the saliva, urine, &c. He observed these animalcules continue to live, and to move in some of those fluids, whilst in others they died instantane- ously. For instance, the blood, the milk and pus did not affect them: in the mucus of the vagina and uterus they generally lived well; but in the saliva and urine they died almost instantaneously. M. Donne, too, affirms, that there are cases in which the mucus of the vagina and uterus acquire properties that are deleterious to the zoospermes, and he is of opinion, that this is a cause of sterility. This deleterious property according to M. Donne, occasionally resides in the vaginal mucus; but at others, in a still higher degree in the mucus of the uterus; and he endeavoured to discover, whether the mucus of the two membranes presented any peculiar characters or signs of disease, and he affirm ,sthat he particularly noticed the excessive acidity of the one, and the marked alkaline character of the other. The mucus secreted by the vagina as far as the orifice of the os uteri differed from that which flowed from within the cervix uteri, independently of its physical characters, by a different reaction. * Gazette Medicale de Paris, No. xxii., 3 Juin, 1837. 34* 402 GENERATION. M. Donne* found the vaginal mucus always acid—the uterine always alkaline, and he thinks that the deleterious influence exerted by them on the zoospermes depended on excess of acidity in the one, and excess of alkali in the other. All this, however, it need scarcely be said, requires substantiation. Professor Wagner,* who has entered at great length into the con- sideration of the spermatozoa, accords with the general conclusions of M. Donne: some of his experiments, however, instituted for the most part on the spermatozoa of the lower ainmals, led him to dif- ferent conclusions. He found, for example, that they almost always lived in saliva; also in urine, when it was kept warm and was not too concentrated. He has repeatedly detected them in the urine of persons, whom he suspected of masturbation. Dr. John Davyb affirms, that on examining the fluid from the urethra after stool in a healthy man, he had always detected spermatozoa in it; and Dr. Robt. Willisc asserts, that under the same circumstances, and even after the mere evacuation of the bladder, he has several times discovered spermatozoa in the fluid of the urethra ; but the subjects of his observation were never strong or healthy men ; they mostly laboured under anomalous nervous symptoms, which, he thinks, were in all likelihood connected with an irritable or disordered state of the vesiculae seminales and prostate part of the urethra. MM. Prevost and Dumas, and Rolando, conjecture that the sper- matic animalcule forms the nervous system of the new being, and that the ovule furnishes only the cellular framework in which the organs are formed; but this is mere hypothesis. The essays of these ingenious experimenters would seem to prove the existence of peculiar animalcules in the sperm, and their apparent agency in the generative process; yet, as we have before seen,d all this has been recently questioned, and Raspail6 is disposed to regard the fancied animalcules as mere shreds of the tissues of the genera- tive organs ejaculated with the sperm. It is scarcely necessary to remark, that all the objections which were urged against the system of the ovarists, as regards the proof in favour of an active participation of both sexes in the work of reproduction, are equally applicable to the views of those animal- culists, who refer generation exclusively to the spermatic animal- cule/ Such are the chief theories that have been propounded on the subject of generation. It has been already observed, that the par- ticular modifications are almost innumerable. They may all, how- ever, be classed with more or less consanguinity under some of the doctrines enumerated. Facts and arguments are strongly against any view that refers the whole process of formation to either sex. « Elements of Physiology, by Dr. Willis, p. 20, Lond. 1841. b Edinburgh Medical and Surgical Journal, vol. 1. * Wagner, op. citat. p. 21, (note). . * Page 341 of this volume. • Chimie Organique, p. 389, Paris, 1833. ' Burdach's Physiologie als Erfahrungswissenschaft, 2te Auflage, i. 112, Leipz. 1835. THEORIES—EVOLUTION. 403 There must be a union of materials furnished by both, otherwise it is impossible to explain the similarity in conformation to both parents, which is often so manifest. Accordingly, this modified view of epigenesis is now adopted by most physiologists:—that at a fecundating copulation, the secretion of the male is united to a material, furnished by the ovarium of the female; that from the union of these elements the embryo results, impressed, from the very instant of such union, with life, and with an impulse to a greater or less resemblance to this or that parent, as the case may be; and that the material, furnished by the female, is as much a secretion resulting from the peculiar organization of the ovarium, as the sperm is from that of the testicle,—life being susceptible, in this manner, of communication from father to child, without a necessity for invoking the incomprehensible and revolting doctrine of the pre- existence of germs. This admixture of the materials furnished by both sexes accounts for the likeness that the child may bear to either parent, whatever may be the difficulty in understanding the precise mode in which they act in the formation of the foetus. It has been attempted, how- ever, by some, to maintain, that the influence of the maternal ima- gination during a fecundating copulation may be sufficient to impress the germ, within her, with the necessary impulse; and the plea has been occasionally urged in courts of justice. Of this we have an example in a well-known case, tried in New York, eight-and-twenty years ago. A mulatto woman was delivered of a female bastard child, which became chargeable to the authorities of the city. When interrogated, she stated that a black man of the name of Whistelo was the father, who was accordingly apprehended, for the purpose of being assessed with the expenses. Several physicians, who were summoned before the magistrates, gave it as their opinion that it was not his child, but the offspring of a white man. Dr. S. Mitchill, however, who, according to Dr. Beck, seemed to be a believer in the influence of the imagination over the foetus, thought it probable that the negro was the father. Owing to this difference of senti- ment, the case was carried before the mayor, recorder, and several aldermen. It appeared in evidence, that the colour of the child was somewhat dark, but lighter than the generality of mulattos, and that its hair was straight, and had none of the peculiarities of the negro race. The court very properly decided in favour of Whistelo, and of course against the testimony of Dr. Mitchill, who, moreover, main- tained, that as alteration of complexion has occasionally been no- ticed in the human subject,—as of negroes turning partially white, —and in animals, so this might be a parallel instance.* The opinion does not seem entitled to much greater estimation than that, of the poor Irishwoman, in a London police report, who ascribed the fact 1 Beck's Medical Jurisprudence, 6th edit. i. 500, Philad. 1838. See, also, for some ridiculous stories- of this kind, Demangeon, Du Pouvoir de l'lmagination sur le Phy- sique et le Moral de I'Homme, p. 201, Paris, 1834. 404 GENERATION. of her having brought forth a thick-lipped, woolly-headed urchin to her having eaten some black potatoes, during her pregnancy! It is obvious, that the effect of the maternal imagination can only be invoked—by those who believe in its agency on the future ap- pearance of the foetus—in the case of those animals in which copu- lation is a part of the process. Where the eggs are first extruded and then fecundated, all such influence must be out of the question; and even in the viviparous animal we have seen, that experiments on artificial impregnation have shown, that not only has the bitch < been fecundated by sperm injected into the vagina, but that the resulting young have manifestly resembled the dog, whence the sperm had been obtained.* The strongest case in favour of the influence of the maternal imagination is given by Sir Everard Home. b An English mare was covered by a quaga,—a species of wild ass from Africa, which is marked somewhat like the zebra. This happened in the year 1815, in the park of Earl Morton, in Scotland. The mare was only covered once; went eleven months, four days, and nineteen hours, and the produce was a hybrid, marked like the father. The hybrid remained with the dam for four months, when it was weaned and removed from her sight. She probably saw it again in the early part of 1816, but never afterwards. In February, 1817, she was covered by an Arabian horse, and had her first foal—a filly. In May, 1818, she was covered again by the same horse, and had a second. In June, 1819, she was covered again, but this year missed; but in May, 1821, she was covered a fourth time, and had a third;—all being1 marked like the quaga. Similar facts have been alluded to by other writers. Haller' , remarks, that the female organs of the mare seem to be corrupted by the unequal copulation with the ass, as the young foal of a horse from a mare, which previously had a mule by an ass, has something asinine in the form of its mouth and lips; and Becherd says, that when a mare has had a mule by an ass, and afterwards a foal by a horse, there are evidently marks in the foal of the mother having retained some ideas of her former paramour,—the ass; whence such horses are commended on account of their tolerance and other simi- lar qualities. It has been even affirmed, that the human female, when twice married, bears children occasionally to the second hus- band, which resemble the first both in bodily structure and mental powers.6 The mode in which the influence is exerted, in this and similar cases, is unfathomable; and the fact itself, although indisputable, is astounding. Sir Everard Homef thinks that it is one of the strongest * See page 367 of this volume. b Philosoph. Transact, for 1821, p. 21; and Lectures on Comparative Anatomy, iii. 307. c Element. Physiol, viii. 104. d Physic. Subterran., Lips. 1703. e See art. Generation, by Dr. Allen Thomson, Cyclop. Anat. and Physiol., P. xiii. p. 468, for Feb. 1838. 1 Lectures, &c. iii. 308. CONCEPTION. 405 proofs of the effect of the mind of the mother upon her young that has ever been recorded. Although we are totally incapable of sug- gesting any satisfactory solution, it appears to us more probable, that the impression must have been made in these cases on the genital system, and probably upon the ovarian vesicle, rather than upon the mind of the animal.* d. Conception. Conception usually occurs without the slightest consciousness on the part of the female; and hence the difficulty of reckoning the precise period of gestation. Certain signs, as shivering, pains about the umbilicus, &c. are said to have occasionally denoted its occur- rence, but these are rare exceptions, and the indications afforded by one are often extremely different from those presented by another. In those animals, in which generation is only accomplished during a period of generative excitement, the period of conception can be determined with accuracy; for, in by far the majority of such cases, a single copulation will fecundate,—the existence of the state of heat indicating that the generative organs are ripe for conception. In the human female, where the sexual intercourse can take place at all periods of the year, conception is by no means as likely to follow a single intercourse; for, although she may be always susceptible of fecundation, her genital organs are perhaps at no one time so powerfully excited as in the animal during the season of love. It is not for the physiologist to inquire into the morbid causes of sterility in either male or female; nor is it desirable to relate all the visionary notions which have prevailed regarding the circumstances that favour conception. It would certainly seem more likely to super- vene when the Venereal orgasm occurs simultaneously in both par- ties; and when the sperm is thrown well forwards towards the mouth of the uterus. We bave already shown, that preternatural openings of the urethra, which interfere with this projection of the sperm in the proper direction, render fecundation less probable. It has been generally affirmed by writers, that conception is apt to take place more readily immediately after menstruation; either, it has been imagined, because the uterus continues slightly open, so as to admit the sperm more easily into its cavity, or because the whole apparatus is in a state of some excitement. This opinion is proble- matical ; and, accordingly, a female is in the habit of reckoning from a fortnight after her last menstrual period; for as she might have fallen with child immediately after one menstruation, or not until im- mediately preceding the following menstruation ; a difference of three weeks might occur; and she, therefore, takes the middle point be- * See, on the Theories of Generation, Buffon, Nat. Hist. vol. ii. chap. 5; Kurt Spren- gel's Hist.de la Medecine, i. 231, Jourdan's translation, Paris, 1815; Dr. A. Thom- son, op. cit. p. 427; Adelon, Physiologie de I'Homme, 2de edit. p. 81, Paris, 1829; Meigs's Philadelphia Practice of Midwifery, p. 83, Philad. 1838; and Seiler, art.Erzeug- ung, in Pierer's Anat. Phys. Worterb. ii. 802, Leipz. und Altenb. 1818. 406 GENERATION. tween those periods; that is, ten days or a fortnight after her last menstruation, or, what is the same thing, ten days or a fortnight before the first obstructed menstruation. Sir Everard Home,* how- ever, differs on this topic from the generality of physiologists,— affirming that, in the human species, the fulness of the vessels of the womb, prior to menstruation, corresponds with the state of heat in the female quadruped, and shows that, at that period, the ova are most commonly fit for impregnation. " The females in India," he observes, " where from the warmth of the climate, all the internal economy respecting the propagation of the species goes on more kindly than in changeable climates, reckon ten months as the period of utero-gestation.b In the Apocrypha, the wisdom of Solomon, chap. vii. v. 2,—' And in my mother's womb was fashioned to be flesh in the time of ten months.' This circumstance seems to prove, that immediately before menstruation, when all the appendages of the womb are loaded with blood, the ova and ovaria are more fre- quently ready fori impregnation, in the climates most congenial for propagation; and therefore the mode of reckoning is from the pre- vious menstruation, which is ten months before the birth." It has been attempted to ascertain what age and season are most prolific. From a register, kept by Dr. Bland, of London, it would appear, that more women between the ages of twenty-six and thirty years, bear children than at any other period. Of two thousand one hundred and two women delivered, eighty-five were from fifteen to twenty years of age; five hundred and seventy-eight from twenty- one to twenty-five; six hundred and ninety-nine from twenty-six to thirty; four hundred and seven from thirty-one to thirty-five; two hundred and ninety-one from thirty-six to forty; thirty-six from forty-one to forty-five ; and six from forty-six to forty-nine. At Marseilles, according to Raymond, women conceive most readily in autumn and chiefly in October; next in summer; and lastly in winter and spring; the month of March having fewest conceptions. Morand says, that July, May, June, and August, are the most frequent months for conception; and November, March, April, and October, successively, the least frequent. At the Ha- vana, according to tables by the author's friend, Don Ramon de la Sagra,c the monthly number of births, amongst the white population, during a period of five years,—from 1825 to 1829,—was in the fol- lowing order:—October, September, November, December, August, July, June, April, May, January, March, and February. February, January, March and April are, therefore, the most frequent months for conception at the Havana,—June, July, May and September the least so. Mr. Burnsd asserts, that the register" for ten years of an extensive parish in Glasgow renders it probable that August and September are most favourable for conception. M. Villerme, from * Lectures on Comparative Anatomy, iii. 297. b These were of course lunarmonths; although Sir Everard clearly does not think so. c Historio Economico-Politica y Estadistica de la Isla de Cuba, Habana 1833 d Principles of Midwifery, 3d edit. p. 126, Lond. 1814. CONCEPTION. 407 an estimate founded on eight years' observations in France, com- prising 7,651,437 births, makes the ratio of conceptions as follows: May, June, April, July, February, March and December, January, August, November, September and October:—and lastly, Dr. Gou- verneur Emerson,* who has employed himself most profitably on the Medical Statistics of Philadelphia, has furnished a table of the number of births, during each month, for the ten years ending in 1830; according to which, the numbers are in the following order: December, September, January, March, October, August, Novem- ber, February, July, May, April and June,—the greatest number of conceptions occurring, consequently, in April, January, and May,— the least in October, August and September. The human female is uniparous,—one ovum only, as a general rule, being fecundated : numerous other animals are multiparous, or bring forth many at a birth. The, law, howrever, on this subject is not fixed. Occasionally, the human female will bring forth twins, triplets or quadruplets, whilst the multiparous animal is not always delivered of the same number. It is impossible to account for those differences. The ovarists refer them to the female; the animalculists to the male; and facts have been found to support both views. Certain females, who have been frequently married, have been multiparous with each husband; and analogous facts have occurred to males under similar circumstances. Menage cites the case of a man, whose wife brought him twenty-one children in seven deliveries ; and the same individual having im- pregnated his servant-maid she brought forth triplets likewise. In 1755, it is asserted, a peasant was presented to the Empress of Russia, who was seventy years of age, and had been twice married. His first wife had fifty-seven children at twenty-one births. In four deliveries she had four children at each; in seven, three; and in six, two. This appears to be the ne plus ultra of such cases! In the Hospice de la Alaterniie, of Paris, it has been observed, that twins occur once in about eighty cases. In the Westminster Hos- pital, the same ratio has been found to prevail. In the British Lying-in Hospital, the proportion was not greater than 1 in 91; whilst in the Dublin Lying-in Hospital the cases were nearly twice as frequent, or about Tin 57. Dr. Collinsb properly remarks on the singular circumstance, that in Ireland, the proportional number of women giving birth to twins is nearly a third greater than in any other country of which he had been able to obtain authentic records. He states the proportion in France to be one in every 95 births ; in Germany, one in 80; in England, one in 92; in Scotland, one in 95 ; and in Ireland, one in 62." Of 129,172 women delivered in the Lying-in Hospital, Dublin, 2062 gave birth to twins; 29 produced three at a birth, which is in the proportion of one in 4450; and one 1 Amer. Journ. of the Med. Sciences, for Nov. 1831. b A Practical Treatise on Midwifery, Lond. 1835; republished in Bell's Select Library, Philad. 1838. 408 GENERATION. i only gave birth to four. In this country, the average, according to Dr. Dewees, is about 1 in 75. Triplet cases were found to occur in the Hospice de la Maternite, of Paris, about once in 9000 times; and in the Dublin Hospital once in 5050 times; the balance being largely in favour of the prolific powers of the Irish. Dr. Dewees affirms, that in more than 9000 cases, he has not met with an instance of triplets. Of 36,000 cases in the Hospice de la Maternite not one brought forth four children; yet there are cases on record where five have been born at a birth.* Beyond this number the tales of authors ought perhaps to be esteemed fabulous. In referring to the following table it will be found to prevail, as a general rule, amongst quadrupeds, that the largest and most formi- dable bring forth the fewest young, and that the lower tribes are unusually fruitful; the number produced compensating, in some measure, for their natural feebleness, which renders them constantly liable to destruction. On the other hand, were the larger species to be as prolific as the smaller, the latter would soon be blotted from existence. What would have been the condition of animated nature, if the gigantic mastodon, once the inhabitant of our plains, could have engendered as frequently and as numerously as the rabbit. For wise purposes, it has also been ordained, that the more for- midable animals seldom begin the work of reproduction until they have nearly attained their full size; whilst those that bring forth many commence much earlier. Lastly, there is some correspondence, likewise, between the dura- tion of gestation and the size of the animal. Animals. Duration of ges- Number Animals. Duration of ges- Number tation. of young. tation. of young. Ape, - - about 9 months, 1 Lioness, 4 or 5 Bat, - - . 2 Tigress, - 4 or 5 Rat, - - 5 or 6 weeks, 5 or 6 Cat, 8 weeks, 4 or 5 Mouse, - - . 6 to 10 Seal, - 2 Hare, - - 30 days, 4 or 5 11 months 1 Rabbit, - - Do. Do. Mare, - and some > 1 Guinea-pig, 3 weeks, 5 to 12 days, 3 Squirrel, 6 weeks, 4 or 5 Ewe, 5 months, 1 or 2 Mole, - - . 4 or 5 Goat, 4£ months, 1,2, or 3 Bear, - - . 2 or 3 Cow, 9 months, lor 2 Otter, - - 9 weeks, 4 or 5 Reindeer, 8 months, 2 Bitch, - - 9 weeks, 4 to 10 Hind, - Do. lor 2 Ferret, - - 6 weeks, 6 or 7 6 to 12 ) and more \ Wolf, - . 10 weeks, 5 to 9 bOW, 4 months, Opossum, - . 4 or 5 Camel, . 12 months, 1 Kangaroo, . 1 Walrus, 9 months, 1 Jackall, . 6 to 8 Elephant, 2 years, 1 Fox, . . 10 weeks, 4 or 5| Whale, 9 or 10 mos. 1 or 2<> a Dr. Garthshore, in Philos. Transact, for 1787, Kleinert's Repertorium, and Amer. Journ. of the Med. Sciences, Feb. 1838, p. 459 ; also, Bulletino delle Scienze Mediche, Agosto e Scttembre, 1838; and Brit, and For. Med. Rev. Oct. 1839, p. 564. x b ?C?'o^ this subJect> Dr- Laycock, on the Nervous Diseases' of Women, p. 48, Lond. 1840. CONCEPTION. 409 Conception being entirely removed from all influence of volition, it is obviously impracticable, by any effort of the will, either to modify the sex of the foetus, or its general physical and moral cha- racters. Yet idle and absurd schemes have been devised for both one and the other. The older philosophers, as Hippocrates and Aristotle, believed that the right testicle and ovary furnished rudi- ments of males; and the same organs, on the left side, those of females: some of the old writers, de Re Rustica, assert that this was the result of their experiments with the ram. These statements gave rise to a pretended " art of procreating the sexes at pleasure," which has even been seriously revived in our own time. Mr. John Hunter published an experiment in the Philosophical Transactions, which was instituted for the purpose of determining whether the number of young be equally divided between the ovaria. He took two sows from the same litter, deprived one of an ovarium, and counted the number of pigs each produced during its life. The sow with two ovaria had one hundred and sixty-two: the spayed sow only seventy-six. Hence he inferred, that each ovarium had nearly the same proportion. In this experiment, he makes no mention of the interesting fact regarding the proportion of the males in the two cases, and whether they were not all of the same sex in the sow that had been spayed. Had his attention been drawn to this point, the results would have been sufficient to arrest the strange hypothesis brought forward by Millot,* who boldly affirmed that males are pro- duced by the right ovarium,and females by the left; asserting, that he could so manage the position of the woman during copulation, that she should certainly have a boy or a girl, as might have been determined upon: and he published the names of mothers, who had followed his advice, and had succeeded in their wishes. A case, related by Dr. Granville, of London, to the Royal Society,b has completely exhibited the absurdity of this doctrine. A woman, forty years of age, died at the Hospice de la Maternite, of Paris,— six or seven days after delivery,—of what had been supposed to be a disease of the heart. The body was opened in the presence of Dr. Granville, and the disease was found to be aneurism of the aorta. On examining the uterus, it was found to be at least four times the size of what it is during the unimpregnated state. It h^.d acquired its full developement on the right side only, where it had the usual pyriform convexity; whilst the left formed a straight line scarcely half an inch distant from the centre, although it was more than two inches from the same point to the outline of the right side. The Fallopian tube and the ovarium, with the other parts on the right side, had the natural appearance; but they were not to be found on the left. Yet this woman had been the mother of eleven children of both sexes; and a few days before her death had been delivered of * Millot, l'Art de Procreer les Sexes a Volonte, nouvelle edit.; avec une Preface sur les divers Systemes Physiologiques de la Generation, par M. Breschet, Paris, 1829. b Philos. Transact, for 1808, p. 308. VOL. II. 35 410 GENERATION. twins;—one male and one female.* M. Jadelot, too, has given the dissection of a female, who had been delivered of several children— boys and girls; yet she had no ovary or Fallopian tube on the right side. Lepelletierb asserts that he saw a similar case in the Hospital at Mans, in 1825, and the Recueils of the Societe, de Medecine, of Paris, contains the history of an extra-uterine gestation, in which a male foetus was contained in the left ovary. Independently of this decisive case, it has been found that when one of the ovaries has been entirely disabled by disease, the other has conceived of both sexes. In rabbits, an ovary has been removed; yet both male and female foetuses have subsequently been engen- dered; and if the gravid uterus of one of those animals be examined, male and female foetuses will be found in the same cornu of the uterus, all of which, owing to the peculiar construction of the uterus, —the cornu forming the main part of the organ,—must manifestly have proceeded from the corresponding ovary. We are totally unaware, therefore, of the circumstances that give rise to the sex of the new being, although satisfied that it is in no respect influenced by the desires of the parents. We shall see, indeed, hereafter, that some distinguished physiologists believe, that the sex is not settled at the moment of conception, and that it is determined at a later period, after the embryo has undergone a certain developement. It is an ancient opinion, which seems to be in some measure con- firmed by what we notice in certain animals, that the character of the offspring is largely dependent upon the moral and physical qua- lities of the parent;—and a Dr. Robert, of Paris, in a dissertation under the pompous title of Megalanthropogenesis, has fancifully maintained, that the race of men of genius may be perpetuated by uniting them to women possessed of the same faculties. Similar views are maintained by Claude Quillet.0 It is an old opinion, that the procreative energy of the parents has much to do with the mental and corporeal activity of the off- spring. Hence it is, that bastards have been presumed to excel in this respect. Such is the view of Burton,d and the same idea is put, by Shakspeare, into the mouth of Edmund.6 This, we have no doubt, is erroneous. Much depends upon the condition of the parents as regards their organization and strength of constitution. The remark—" fortes creantur fortibus et * Sir E. Home, Lect. on Comp. Anat. iii. 300. b Physiologie Medicale et Philosophique, iv. 333, Paris, 1833. c Quilleti Callipcsdia, sive de Pulchrae Prolis Habendae Ratione, &c, Lond. 1708. d Anatomy of Melancholy, vol. ii. e «i Why brand they us With base ? with baseness ? bastardy ? base ? base ? Who in the lusty stealth of nature take More composition and fierce quality Than doth, within a dull, stale, tired bed Go to the creating a whole tribe of fops Got 'tween sleep and wake!" King Lear, i. 2. CONCEPTION. 411 bonis"—is true within certain limits; but we have no proof that the ardour of the procreative effort can have any such influence; and the ratio of instances of bastards, who have been signalized for the possession of unusual vigour—mental or corporeal—to the whole number of illegitimates, is not greater than in the case of those born in wedlock.5 It would appear, too, that the number of male children is greater in cases of legitimate than of illegitimate births. Mr. Babbageb has compared the ratio in different countries, from which he has deduced the following table:— Legitimate Births. Number of Births observed. Illegitimate Births. Number of Births observed. Females. Males. Females Males. France, Naples, Prussia, Westphalia, Montpellier, 10,000 10,000 10,000 10,000 10,000 10,657 10,452 10,609 10,471 10,707 9,656,135 1,059,055 3,672,251 151,169 25,064 10,000 10,000 10,000 10,000 10,000 10,484 10,267 10,278 10,039 10,081 673,047 51,309 212,804 19,950 2,735 Mean, | 10,000 10,575 10,000 10,250 To elucidate the effect of the condition of the parent on the future progeny, M. Girou de Buzareinguesc gave a violent blow to a bitch, whilst lined, in consequence of which she was paraplegic for some days. She brought forth eight pups, all of which, except one, had the hind legs wanting, malformed, or weak. It has been attempted to show, also, that the corporeal vigour of the parents has much to do even with the future sex. M. Girou instituted a series of experiments on different animals, but especially on sheep, to discover, whether a greater number of male or female lambs may not be produced at the will of the agricul- turist. The plan, adopted to insure this result, was to employ very young rams in that division of the flock whence it was desired to obtain females; and strong and vigorous rams, of four or five years of age, in that from which males were to be procured. The result would seem to show, that the younger rams begat females in greater proportion, and the older, males. M. Girou asserts, that females commonly predominate amongst animals, which live in a state of " polygamy," and it is asserted, that the same fact has been observed, in Turkey, and Persia, in our own species; but statistical facts are wanting on this subject. From the researches of Hofackerd and Sadler,e it would seem, that, as a general rule, when the mother is older than the father, fewer boys » Elliotson's Blumenbach's Physiology, 4th edit. p. 496, Lond. 1828. b Brewster's Journal of Science, New Series, No. 1; and Quetelet, Sur I'Homme, i. 47, Paris, 1835. c Menioire sur les Rapports des Sexes, &c. Paris, 1836; and a farther Memoir, in Revue Medicale, 1837; and Encyglograph. des Sciences Medicales, Janv. 1838. See, also, a notice of the first Memoir by Dr. G. Emerson, in Amer. Journ. of the Medical Sciences, p. 171, May, 1837. * Annales d'Hygtene, p. 537, July, 1829. e The Law of Population, ii. 343, Lond. 1830; and Quetelet sur I'Homme, i. 53, Paris, 1835. 412 GENERATION. are born than girls, and the same is observed where they are of equal age, but the greater the excess of age on the part of the father, the greater will be the ratio of boys born.a It appears that the proportion of males born to the females is every where pretty nearly the same. The calculations of Hufe- land give the numbers in Germany as 21 to 20; those of Girou, in France, make the proportions as 21 to 19.69; and in Paris as 21 to 20.27; and the census of Great Britain, taken in 1821, estimates them as 21 to 20.006. In the Dublin Lying-in Hospital, during ten years, the ratio was as 21 to 19.33; and in the Eastern District of the Royal Maternity Charity of London, during the year 1830, it was as 21 to 19.64. In Philadelphia, according to the tables of Dr. Emerson,b the proportion from 1821 to 1830, was as 21 to 19.43. In the whole of Europe the proportion is estimated as 106 to 100.c Although, however, a greater number of males may be born, they seem more exposed to natural or accidental death, for amono-st adults the balance is much less in their favour, and, indeed, the number of adult females rather exceeds that of the males. Dr. Emersond states, that of the children born in Philadelphia, during the ten years included between 1821 and 1830, amounting, accord- ing to the returns made to the Board of Health, to 64,642, there were 2,496 more males than females. But, notwithstanding the males at birth exceeded the females about 7^ per cent., the census of 1830 shows, that by the fifth year, the male excess is reduced to about 5 per cent., and at ten years to only 1 per cent.; and that reduction still going on, the females* between the ages of 10 and 15, exceed the males about 8 per cent.; and between 15 and 20, 7.3 per cent.; facts, which clearly authorize the deduction'of Quetelet,6 that during the early stages of life there are agencies operating to reduce the proportion of the male sex. Dr. Emerson's investigation exhibits clearly, that the greater liability of males to accidents did not furnish a sufficient reason for their greater mor- tality;—the deaths, reported in the Philadelphia bills, under the head of casualties, constituting but a small proportion of the whole mor- tality ; and this—when burns and scalds are included—being more considerable in the case of the female. The gross male mortality under the twentieth year, for the three years above mentioned exceeded the female in the ratio of 7.94 per cent. The diseases, which seemed to be particularly obnoxious to the 1 See, on this subject, Mr. A. Walker, Intermarriage, Amer. Edit. p. 219 New York 1839. b Amer. Journ. of the Med. Sciences, for Nov. 1835. c Quetelet, Sur I'Homme, i. 43, Paris, 1835. See, also.Transactions of the Statistical Society of London, vol. i. part i. Lond. 1837; and a notice of the volume by Dr. Emerson, in American Journal of the Medical Sciences, p. 444, for Feb. 1838; Dr. Allen Thom- son, art. Generation, Cyclop. Anat. and Physiol, part xiii. p. 478, Feb. 1838; and Bur- dach's Physiologie als Erfahrungswissenschaft, i. 587, 2te Auflage, Leipz. 1835. d American Journal of the Medical Sciences, for Nov. 1835, p. 56 e Sur I'Homme, i. 156, Paris, 1835. SUPERFfETATION. 413 male sex, were, according to the Philadelphia bills, the following— arranged in the order of their decreasing mortality:—Inflammation of the brain, inflammation of the bowels, bronchitis, croup, inflam- mation of the lungs, fevers of all kinds (except scarlet), convulsions, general dropsy, dropsy of the head, and small-pox. To these sources of mortality may be added those under the head of casualties and others vaguely designated debility, decay, &c. The few cases in which the deaths of females predominated were—consumptions, dropsy of the chest, scarlet fever, burns and scalds, and hooping- cough. It would appear that about one infant in twenty is still-born. The cause of this is* a difficult inquiry; as well as that of the greater ratio—double—in cities than in the country; in some cities than in others; amongst male infants rather than females; in ihe winter than in the summer; amongst the illegitimate rather than the legiti- mate. It is an interesting topic of investigation for the medical statistician.* e. Superfixtation. It has been an oft agitated question, whether, after an ovule has been impregnated and passed down into the cavity of the uterus, another ovule may not be fecundated; so that the products of two conceptions may undergo their respective developements in the uterus, and be delivered at an interval corresponding to that between the conceptions. Many physiologists have believed this to be pos- sible, and have given it the name of superfalation. The case, cited from Sir Everard Home, of the young female, who died on the seventh or eighth day after conception, exhibits that the mouth of the womb is at a very early period completely obstructed by a plug of mucus; and that the inner surface of the uterus is lined'by an efflorescence of coagulable lymph, the nature of which will be described under the next head. When such a change has been effected, it would seem to be im- possible for the male sperm to reach the ovary; and, accordingly, the general belief is, that superfcetation is only practicable prior to these changes,—which may perhaps require twenty-four hours for their accomplishment,—and where there is a second vesicle ripe for impregnation. Of this kind of superfcetation it is probable, that twin and triplet cases are often, if not always, examples; one ovule being impregnated at one copulation, and another at the next.b It seems also to be common in animals. The dog-breeders have often re- marked, that a bitch, after having been lined, will readily admit a * See the author in American Med. Intelligencer, for Sept. 1, 1837, p. 203, and ibid. Oct. 1, 1836, p. 252; Dr. Avery, in Transact, of the Med. Society of the State of New York, iii., part ii. p. 179, Albany, 1837; Quetelet, Sur I'Homme, p. 122, Paris, 1835; Brit, and For. Med. Review, July, 1837, p. 234; Dr. Emerson, in American Journ. of the Medical Sciences, Feb. 1838, p. 444; and Prof. Rau, of Bern, Ueber die Unna- tiirliche Sterblichkeit der Kinder in ihrem ersten Lebensjahre, Bern, 1836, cited in Brit, and For. Med. Rev. April, 1839, p. 593. *> Art. Zwillinge, in Pierers Anat. Physiol. Real. Worterb. Band viii., Altenb. 1829. 35* 414 GENERATION. dog of a very different kind to copulate with her; and where this has occurred, two different descriptions of puppies have been brought forth; some resembling each of the fathers. Sir Everard Home1 states, that a setter bitch was lined in the morning by a pointer. The bitch went out with the game-keeper, who had with him a Russian setter of his own, which also lined her in the course of the afternoon. She had a litter of six puppies; two only of which were preserved. One of these bore an exact resemblance to the pointer, the other to the Russian setter,—the male influence being predomi- nant in each. Of this kind of superfcetation, superfecundation or double concep- tion we have several instances on record ;—of which the following are amongst the most striking, the male parents of the respective foetuses having differed in colour. The first is the well-known case, cited by Buffon,b of a female at Charleston, South Carolina, who was delivered in 1714 of twins, within a very short time of each other. One of these was black, the other white. This circum- stance led to an inquiry, when the woman confessed, that on a par- ticular day, immediately after her husband had left his bed, a negro entered her room, and compelled her to gratify his wishes, under threats of murdering her. Several cases of women in the West India islands having had, at one birth, a black and a white child, are recorded; and Dr. Moseley6 gives the following case, which is very analogous to that described by Buffon. A negro woman brought forth two children at a birth, both of a size, one of which was a negro, the other a mulatto. On being interrogated, she said, that a white man, belonging to the estate, came to her hut one morning before she was up, and that she received his embraces soon after her black husband had quitted her. Sir Everard Homed likewise asserts, that a particular friend of his " knows a black woman, who has two children now alive, that are twins and were suckled together; one quite black, the other a mulatto. The woman herself does not hesitate in stating the circumstances: one morning just after her husband had left her, a soldier, for whom she had a partiality came into her hut, and was connected with her, about three or four hours after leaving the embraces of her husband." One of the author's pupils, Dr. N. J. Huston, then of Harrisonburg, Virginia, also communicated to him the particulars of a female who was delivered in March, 1827, of a negro child and a mulatto, on the same night. Where negro slavery exists, such cases are sufficiently numerous.* So far, therefore, as regards the possibility of a second vesicle being fecundated, prior to the closure of the os uteri by the tena- cious mucus and the fiocculent membranous secretion from the interior of the uterus, or by the decidua, no doubt, we think, can be ' Lect. on Comp. Anat. iii. 302. b Hist. Nat. de I'Homme, Pubertc. c A Treatise on Tropical Diseases, p. 111. d Op. citat. e See, for an enumertion of cases, Beck's Medical Jurisprudence, 6th edition, i. 222; and Dr. Allen Thomson, in Cyclop. Anat. and Physiol., part xiii. p. 469, for Feb. 1838. PREGNANCY. 415 entertained; but, except in cases of double uterus, it would seem to be impracticable afterwards; although cases have been adduced to show its possibility. Still these may perhaps be explained under the supposition, that the uterine changes, above referred to, may not be as rapidly accomplished in some cases as in others; and, again, the period of gestation is not so rigidly fixed, but that children, begotten at the same time, or within twenty-four hours, may still be born at a distance of some weeks from each other. A case hap- pened to the author in which nearly three weeks elapsed between the birth of twins, in whose cases the ova were probably fecundated either at the same copulation or within a few hours of each other. It may happen, too, that although two ova may be fecundated, both embryos may not undergo equal developement.* One, indeed, may be arrested at an early stage, although still retaining the vital principle. In such a case, the other will generally be found larger than common. A case of this kind occurred recently in the prac- tice of Professor Hall, of the University of Maryland. On the 4th of October, 1835, a lady was delivered of a female foetus, 2 inches and 10 lines in length. This occurred about half-past eight in the morning; and, at two o'clock on the following morning, she was delivered of a second child, which weighed 9^ pounds. The foetus, whose developement was arrested, was seen by the author. When first extruded, it gave no evidences of decay, and in colour and general characters resembled the foetus of an ordinary abortion.11 f. Pregnancy. When the fecundated ovum has been laid hold of by the fim- briated extremity of the Fallopian tube, and through this channel, —perhaps by the contraction of the tubes and the ciliary motions of its lining membrane0—has reached the cavity of the uterus, it forms a union with this viscus, to obtain the nutritive fluids, that may be required for its developement, and to remain there during the whole period of pregnancy or utero-gestation;—a condition which will now require some consideration. Immediately after a fecundating copulation, and whilst the chief changes are transpiring in the ovary, certain modifications occur in the uterus. According to some, it dilates for the reception of the ovum. Bertrandi found this to be the case in extra-uterine preg- nancy, and in females whom he opened at periods so near to con- ception, that the ovum was still floating in the uterus. Its substance appeared at the same time redder, softer, less compact, and more vascular than usual. In the case to which we have more than once alluded from Sir Everard Homed the lining of the uterus was 1 Wagner's Elements of Physiology, by Willis, p. 79, Lond. 1841. b For similar cases, of which many are on record, see Dr. Saml. Jackson, formerly of Northumberland, Pa., now of Philadelphia, in American Journal of the Medical Sciences, May, 1838, p. 237, and May, 1839, p. 256; also, Dr. J. G. Porter, ibid. Aug. 1840, p. 307. c Wagner, op. citat. p. 137. d Lect. on Comp. Anat. iii. 209, Lond. 1823. 416 GENERATION. covered by a beautiful flocculent appearance, about the seventh or eighth day after impregnation. The soft flocculent membrane, which forms in this way, is the membrana caduca or decidua, decidua externa, first described by Hunter; the epichorion of Chaus- sier; the tunica exterior ovi, t. caduca, t. crassa; Fig. 160. membrana cribrosa; membrana ovi materna, mem- brana mucosa; decidua cellularis and spongiosa, of others. In a case observed by Von Baer at a very early period, when the decidua was still in a pulpy state, the villi of the lining membrane of the uterus, which' aJdhbetweeSn thl'vn" m tne unimpregnated state are very short, were is the decidua. The found to be remarkably elongated; and between the uterine vessels are .... , . ' ,, ° , seen extending into villi, and passing over them, was a substance not fngl,oeo1.suthe:redform' organized, but merely effused, and evidently the decidua at an extremely early age.a The arrangement of this membrane has given rise to some dis- cussion.1' The opinions of most of the anatomists of the present day are in favour of one or two views. It is maintained by some, th^t one of the first effects of conception is to cause the secretion of a considerable quantity of a sero-albuminous substance from the inner surface of the uterus ; so that the organ becomes filled with it. At first, when the ovum arrives in the uterus, it falls into the midst of this secretion, gradually absorbing a part by its outer sur- face for its nutrition. The remainder is organized into a double membrane, one corresponding to the uterus, the other adhering to the ovum. This sero-albuminous substance has been assimilated, both to the white, with which the eggs of birds become invested in passing through the oviduct, and to the viscid substance, that enve- lopes the membranous ova of certain reptiles. It is conceived by some to plug up both the orifices of the Fallopian tubes, and that of the uterus; and according to Krummacherc and Dulrochet,d it has been seen extending into the tubes ; whilst the remains of that, which plugged up the os uteri, has been recognised in the shape of a nipple on the top of the aborted ovum. To this substance, Bres- chet6 has given the name Hydroperione. By others, it is held that the decidua is slightly organized even prior to the arrival of the ovum, lining the whole of the cavity and being devoid of apertures; so that when the ovum passes along the tube and attains the cornu of the uterus, it pushes the decidua before it; the part so pushed a Von Baer, op. citat.; and Wagner's Physiology, by Willis, p. 184, Lond. 1841. b Weber's Hildebrandt's Handbuch der Anatomie, iv. 486, and 515, 1832; Purkinje, art. Ei, Encyclop. Worterb. der Medicin. Wissensch.x. 107, Berlin, 1834; W. Hunter's Anatomical Description of the Human Gravid Uterus and its Contents, Lond. 1794; and Carus, Zur Lehre von der Schwangerschaft, u. s. w., Abth. ii. s. 5. c Diss, sistens Observationes quasd. Anatom. circa Velamenta Ovi humani. Duisb. 1790. d Mem. de la Societe Medicale d'Emulation, viii. P. i. 1817. e Etudes Anatomiques, Physiologiques, et Pathologiques de l'ffiuf dans l'Espece Humaine, &c, Paris, 1832. PREGNANCY. 417 forwards constituting the tunica decidua reflexa or ovuline, and enve- loping the whole of the ovum except at the part where the decidua leaves the uterus to be reflected over it. This is the seat of the future placenta. Such is the opinion of Velpeau," Wagner,b and others. At the point Fig. 161. of reflection of the de- cidua reflexa, there is a thick stratum of a substance precisely similar to the deci- dua reflexa, which attaches the ovum to the side of the uterus, and which blends intimately on the outer side of the re- flex fold with the de- cidua vera. This thick stratum is termed the decidua serotina, from its ap- pearing to have been formed at a later period. It is repre- sented in the margi- nal illustration from Wagner. The view of Mr. Burns0 differs from this in suppo- sing that the deci- dua consists of two layers, the innermost of which has no aper- ture, so that the ovum on attaining the cornu of the uterus pushes it forwards, and forms the decidua protrusa or decidua reflexa. Impregnation, Vel- peau says, occasions a specific excitation in the uterus, promptly followed" by an exhalation of coagulable matter. This concretes, and is soon transformed into a kind of cyst or ampulla, filled with a transparent or slightly rose-coloured fluid. This species of cyst Section of Uterus with the Ovum somewhat advanced. a. Gelatinous mass plugging up the cervix uteri, b. Fallopian tube. c. Decidua vera, c 2. Process of the decidua vera in the right Fallopian tube, e e. Points of reflection of the decidua re- flexa. /. Decidua serotina. g. Allantois. A. Umbilical vesicle with its pedicle in the umbilical cord. t. Amnion. K. Chorion ; —between the two the space for the albumen. ■ Traite Elementaire de l'Art des Accouchemens, i. 231, Paris, 1829; or Meigs' translation, 2d edit. p. 246, Philad. 1838; also, Velpeau, Embryologie ou Ovologie Hu- maine, Paris, 1833; and a copious Analysis, by the author, in Amer. Journ. Med. Sciences, Aug. 1834, p. 389. b Op. citat. p. 188. c Principles of Midwifery, 3d edit. p. 147, Lond. 1814. 418 GENERATION. is in contact with the whole surface of the uterine cavity, and sometimes extends into the commencement of the tubes, and most frequently into the upper part of the cervix uteri, in the form of solid, concrete cords; but is never, he says, perforated naturally, as Hunter, Bojanus, Lee and others have maintained. The de- cidua uteri, according to Velpeau, retains a pretty considerable thickness, especially around the placenta, until the end of gestation; the decidua reflexa, on the contrary, becomes insensibly thinner and thinner, so that at the full period it is at times of extreme tenuity. Towards the third or fourth month—a little sooner or later—they touch and press upon each other, and remain in a more or less perfect state of contiguity, until the expulsion of the secundines; but, Velpeau asserts, they are never confounded, and such appears to be the view of BischofF The decidua—the true as wrell as the reflect- ed—is esteemed by Velpeau a simple concretion,—a layer without regular texture,—the product of an excretion from the lining mem- brane of the uterus ; on this account, he terms it, " anhistous mem- brane" (from av, privative, and ioVo£ "a web") or "membrane without texture." There has, indeed, been a striking dissatisfaction with the name " decidua." Besides the appellatives already given, Dutrochet has proposed to call it epione, Breschet, perione, Seiler, membrana uteri interna evoluta and Burdach, nidamentum.b The use of the decidua is, in Velpeau's opinion, to retain the fecundated ovum to a given point of the uterine cavity; and if his views of its arrangement were correct, the suggestions would be good. In favour of this arrangement, a good deal might be said. If there were apertures in the decidua corresponding to the Fallo- pian tubes, it would seem, that the ovum ought more frequently to fall into the serous-albuminous matter about the cervix uteri, and attachment of the placenta over the os osteri ought, perhaps, to occur more frequently than it is known to do. Under M. Velpeau's doc- trine, the attachment of the placenta ought rather to be near the cornu of the uterus, which is, in fact, the case. Of 34 females, who died in a state of pregnancy at the Hopital de Perfectionnemeni, an examination of the parts exhibited, that, in twenty, the centre of the placenta corresponded to the orifice of the Fallopian tube : in three it was anterior to it; in two posterior ; in three beneath; and in six near the fundus of the uterus. It is not so easy to subscribe to his assertions regarding the " anorganic" nature of the decidua. Many excellent observers have affirmed, not only that this membrane exists between the placenta and the uterus, which M. Velpeau's view, of course, renders impossible, but that numerous vessels pass between it, the uterus, and the placenta. We know, too, that the safest and most effectual mode of inducing premature labour is to detach the decidua from the cervix uteri, or, in other words, to break up the » Wagner, op. citat. p. 190 (note). b Burdach, Die Physiologie als Erfahrungswissenschaft, B. ii.; Bojanus, Isis, 1821, H. iii.; and Robt. Lee's Remarks on the Pathology and Treatment of some of the most important Diseases of Women, London, 1833. PREGNANCY. 419 vessels that form the medium of communication between it and the lining membrane of the uterus. It may be said, indeed, that the mere separation of the " anorganic pellicle"—as M. Velpeau desig- nates it—is a source of irritation, and may excite the uterus to the expulsion of its contents, and this is possible; but he affirms, that no tissue attaches the decidua to the uterus; and that it adheres to the inner surface of the organ merely in the manner of an excreted membraniform shell (plaque). The views of Lepelletier1 and Raspaif0 coincide with those of Velpeau as to the decidua being an excretion; but those of the latter are modified by his peculiar opinions. He maintains, that the surfaces of an organ—whether external or internal—having once fulfilled their appropriate functions, become detached and give place to the layer beneath them; and we have before remarked, that he considers the secretions of the mucous and serous mem- branes to be constituted of the detritus of those membranes. Now, that which happens to the intestinal canal and the bladder must likewise happen, he affirms, to the uterus, and, as at the period of ^ gestation, it surpasses in developement, elaboration, and vitality, every other living organ, it ought necessarily to cast off its layers, in proportion as they have executed the work of elaboration. These deciduous layers constitute the decidua, on which, he says, traces of a former adhesion to the parietes of the uterus, and of the three apertures into the organ, may be met with. But the very existence of a decidua reflexa has been denied. It is so by J6rg,c Samuel,'1 and by Dr. Granville, who affirms that it is now scarcely admitted by one in ten of the anatomists of the Euro- pean continent.6 He refers to a specimen of an impregnated uterus in the Museum of the Royal College of Surgeons of London, which exhibits distinctly a round ovum, suspended naturally within the decidua, as a globe may be supposed to hang from some point of the interior of an objong sac; and to two specimens, in the collec- tion of Sir Charles Clarke, exhibiting an ovulum, which has already penetrated about an inch into the cavity of the uterine decidua; but neither in these, nor in the specimen of the Royal College, is any part of the uterine decidua pushed forward. The ovum appears to have its natural covering; and, in the College specimen, there is a large space between them and the deciduous lining of the uterus. Dr. Granville regards the decidua reflexa to be the external mem- brane of the ovum, to which Professor Boer, of Konigsberg, gave the name " cortical membrane," and which Dr. Granville terms cortex ovi.1 It has received various names. By Albinus, it was termed involucrum membranaceum; by Hoboken, membrana retiformis * Physiologie Medical et Philosophique, iv. 339, Paris, 1833. b Chimie Organique, p. 270, Paris, 1833. c Das Gebarorgan des Menschen, u. s. w. Leipz. 1808. d De Ovorum Mammal. Velament. Wirceb. 1816; and art. Ei, in Encycl. Wdrterb. der Med. Wissensch. x. 107, Berlin, 1834. e See, also, Dewees, Compendious System of Midwifery. f Graphic Illustrations of Abortion, &c. p. v. Lond. 1834. 420 GENERATION. chorii; by Rocderer, membrana filamentosa ; by Blumenbach, mem- brana adventitia; and by Osiander, membrana crassa.* To this membrane—and to the decidua uteri, as connected with the pla- centa—we shall have to refer hereafter. Such is the uncertain state of our information on this interesting topic of intra-uterine anatomy. The decidua manifestly does not belong to the ovum; for it not only exists prior to the descent of the ovum, into the uterus, but is even formed, according to Breschet,b in all cases of extra-uterine pregnancy. (See Fig. 162.) Chaussier saw it in several cases of tubal gestation. It existed in a case of abdominal pregnancy, cited by Lallemant, and, according to Adelon,c Evrat affirms, that one is se- creted after every time of sexual intercourse,—which is apocryphal. Fig. 162. Extra- Uterine Pregnancy. a. The uterus, its cavity laid open. b. Its parietes thickened, as in natural pregnancy, e. A portion of decidua separated from its inner surface, d. Bristles to show the direction ofthe Fallo- pian tubes, c. Right Fallopian tube distended into a sac which has burst, containing the extra- uterine ovum. /. The foetus, g. The chorion, h. The ovaries; in the right one is a well marked corpus luteum. t. The round ligament. Recently, Dr. Robert Lee"1 has shown, that the decidua is not formed within the uterus in all cases of extra-uterine gestation. In ten cases detailed by him, and in one other cited from Chaussier, the decidua was seen distinctly surrounding the ovum in the Fallo- pian tube. When the ovum attains the interior of the uterus, which it does * Burdach's Physiologie als Erfahrungswissenschaft, ii. 75, he refers to the various views on the subject of the decidua reflexa. See, also, Velpeau, in op. cit.; and Pur- kinje, art. Ei, in Encyclop. Worterb. der Medicin. Wissensch. x. 107, Berlin, 1834. b Repert. General, d'Anatomie, p. 165, pour 1828. c Physiologie de I'Homme, 2de edit. iv. 110, Paris, 1829. <> Lond. Med. Gazette, June 5, 1840. PREGNANCY. 421 in the first five or six days after conception, it forms, in a short space of time, a connexion with the uterus by means of the pla- centa, in the mode to be mentioned hereafter. During the develope- ment of the embryo, it is requisite that the uterus should be cor- respondency enlarged, in order to afford room for it, as well as to supply it with its proper nutriment. These changes in the uterine system will engage us exclusively at present. In the first two months, the augmentation in size is not great, and chiefly occurs in the pelvis; but, in the fourth, the increase is more rapid. The uterus is too large to be contained in the pelvis, and consequently rises into the hypogastrium. During the next four months, it increases in every direction, occupying a larger and larger space in the cavity of the abdomen, and crowding the viscera into the flanks and the iliac regions. At the termination of the eighth month, it almost fills the hypogastric and umbilical regions; and its fundus approaches the epigastric region. After this, the fundus is depressed and approaches the umbilicus, leaving a flatness above, which has given rise to the old French proverb:—En ventre plat enfant y a. During the first five months of utero-gestation, the womb expe- riences but little change, maintaining a conoidal shape. After this, however, the neck diminishes in Fig 163. Fig. 164. length, and is ulti- mately almost en- tirely effaced. The organ has now a decidedly ovoid shape, and its bulk is, according to Haller and L mother, and Dr. Dewees himself. The lady was, at the time, within a week of her menstrual period; and, as the catamenia appeared as usual, she was induced to hope, that she had escaped impregnation. Her catamenia did not, however, make their appearance at the next period; the ordinary signs of pregnancy supervened: and in nine months and thirteen days, or in two hundred and ninety-three days from the visit of the husband, she was delivered.b In his evidence before the House of Peers, in the case just alluded to, Dr. Granville stated his opinion, that the usual term of utero- gestation is as we have given it; but he, at the same time, detailed the case of his owrn lady, in whom it had been largely protracted. Mrs. Granville passed her menstrual period on the 7th of April, and on the 15th of August following she quickened;—that is, four months and six or seven days afterwards. In the early part of the first week in January, her confinement was expected, and a medical friend desired to hold himself in readiness to attend. Labour pains came on at this time, but soon passed away; and Mrs. G. went on till the 7th of February, when labour took place, and the delivery was speedy. The child was larger and stronger than usual, and was considered by Dr. Granville,—as well as by Dr. A. T. Thom- son, the Professor of Materia Medica in the University of London, —to be a ten months' child. Now, if, in this case, we calculate, that conception occurred only the day before the interruption of menstruation, three hundred and six days must have elapsed be- tween impregnation and birth; and if we take the middle period between the last menstruation and the interruption, the interval must have been three hundred and sixteen, or three hundred and eighteen days. The limit, to which the protraction of pregnancy may possibly extend, cannot be assigned. It is not probable, however, that it ever varies largely from the ordinary period. The University of Heidel- berg allowed the legitimacy of a child, born at the expiration of thirteen months from the date of the last connubial intercourse; and a case was decided by the Supreme Court of Friesland, by which a child was admitted to the succession, although it was not born till three hundred and thirty-three days from the husband's death; or only a few days short of twelve lunar months. These are instances of the we plus ultra of judicial philanthropy, and, perhaps we might * A Compendious System of Midwifery, 7th edit. Philad. 1835. b See a case of protracted gestation communicated by Dr. James R. Manley to Dr. T. R. Beck, in Amer. Journ. of the Medical Sciences, Jan. 1831, p. 59. PARTURITION. 431 say, credulity. Still, although extremely improbable, we cannot say that they are impossible. This much, however, is clear, that real excess over two hundred and eighty days is by no means frequent; and we think, in accordance with the civil code now in force in France, that the legitimacy of an infant born three hundred days after the dissolution of marriage may be contested; although we are by no means disposed to affirm, that if the character of the woman be irreproachable, the decision should be on the side of illegitimacy. Professor Hamilton, indeed, says he is "quite certain," that the term allowed by the French code is too limited, and he is inclined to regard ten calendar months, which he believes to be the established usage of the Consistorial Court of Scotland, as a good general rule, liable to exceptions, upon satisfactory evidence that menstruation had been obstructed for a certain period.* i. Parturition. At the end of seven months of utero-gestation, and even a month earlier, the foetus is capable of an independent existence; provided, from any cause, delivery should be hastened. This is not, however, the full period, and although labour may occur at the end of seven months, the usual course is for the foetus to be carried until the end of nine calendar months. If it be extruded prior to the period at which it is able to maintain an independent existence, the process is termed abortion or miscarriage; if between this time and the full period, it is called premature labour. With regard to the causes, that give rise to the extrusion, we are in utter darkness. It is in truth as inexplicable as any of the other instinctive operations of the living machine. Yet although this is generally admitted, the discussion of the subject occupies a consi- derable space in the works of some obstetrical writers.1" Our know- ledge appears to be limited to the fact, that when the foetus has undergone a certain degree of developement, and the uterus a cor- responding distension, its contractility is called into action, and the uterine contents are beautifully and systematically expelled. Nor can we always fix upon the degree of distention, that shall give occasion to the exertion of this contractile power. Sometimes, it will supervene after a few months of utero-gestation so as to pro- duce abortion; at other times it will happen when the foetus is just viable; and at others, again, and in the generality of cases, it is not elicited until the full period. In cases of twins, the uterus will admit of still greater distention before its contractility is aroused. A day or two preceding labour, a discharge is occasionally ob- served from the vagina of a mucous fluid, more or less streaked with blood. This is termed the show, because it indicates the com- mencement of some dilatation of the neck, or mouth of the womb, —the forerunner of labour or travail. * Op. cit, Amer. Med. Library edit. p. 59. b Dewees, Compendium of Midwifery. 432 GENERATION. Natural Labour. Fig. 166. The external organs, at the same time, become tu- mid and flabby. The ori- fice of the uterus, if an examination be made, is perceived to be enlarging; and its edges are thinner. Along with this, slight grinding pains are expe- rienced in the loins and abdomen. ,After an uncer- tain period, pains of a very different character come on, which commence in the loins, and appear to bear down towards the os uteri. These are not con- stant, but recur, at first after long intervals, and subsequently after shorter; —the body of the uterus manifestly contracting with great force, so as to press the ovum down against the mouth of the womb, and to dilate it. In this way, the membranes of the ovum protrude through the os uteri with their contained fluid, the pouch being occasionally termed the bag of waters. Sooner or later the mem- branes give way, the waters are discharged, and the uterus contracts so as to embrace the body of the child, which was previous- ly impracticable, except through the medium of the liquor amnii. At the commencement of labour, the child's head has not entered the pelvis, the occiput, as in the marginal figure, (Fig. 166) being generally towards the left acetabulum; but, when the uterine contractions become more violent, and are accom- panied by powerful efforts on the part of the abdominal muscles, the head enters the Head of the Foetus in the Pelvis. pelvis, the mOUth ©f the PARTURITION. 433 womb becomes largely dilated, and the female is in a state of agita- tion and excitement, owing to the violence of the efforts, and the irre- sistible desire she has of assisting them as far as lies in her power. When the head has entered the pelvis, in the position described, in which the long diameter corresponds to the long diameter of the pelvis, it describes, laterally, an arc of a circle, the face passing into the hollow of the sacrum, and the occiput behind the arch of the pubis, (as in Fig. 167.) By the continuance of the pains, the head presents at the vulva. The pains now become urgent and forcing. The os coccygis is pushed backwards, and the perineum is distended,—at times so considerably as to threaten, and even to effect laceration; the anus is also forced open and protruded; the nymphae and carunculae of the vagina are effaced; the labia sepa- rated, and the head clears the vulva, Fig. 168. from the occiput to the chin, expe- riencing a vertical ..••"' rotation as de- .<' picted in Fig. 168. / "... When the head is / extruded,the shoul- j ders and rest of the I body readily fol- \ low, on account of \ their smaller di- \ mensions. The child, however, still remains attached lo the mother by the navel-string, which has to be tied, and divided at a few fingers' breadth from the umbilicus. After the birth of the child, the female has generally a short interval of repose; but, in a few minutes, slight bearing down pains are experienced, owing to the contraction of the uterus for the separation of the placenta, and of the membranes of the ovum, called the secundines or afterbirth. The process of parturition is accomplished in a longer or shorter time in different individuals, and in the same individual in different labours, according to the particular conditions of the female and foetus. The parts, however, when once dilated, yield much easier afterwards to similar efforts, so that the first labour is generally the most protracted. After the separation of the secundines, the female is commonly vol. ii. 37 Extrusion of the Head. 434 GENERATION. left in a state of debility and fatigue ; but this gradually disappears. The uterus also contracts; its vessels become tortuous, small, and their orifices are plugged up. For a short time, blood continues to be discharged from them; but as they become obliterated by the return of the uterus to its usual size, the discharge loses its sangui- neous character, and is replaced by one of a paler colour, called the lochia, which gradually disappears, and altogether ceases in the course of two or three weeks after delivery. For a day or two after delivery, coagula of blood form in the in- terior of the uterus, especially in the second and subsequent labours, which excite the organ to contraction for their expulsion. These contractions are accompanied with pain, and are called after pains; and as their object is the removal of that, which interferes with the return of the uterus to its proper dimensions, it is obvious that they ought not to be officiously interfered with. Whilst the uterus is contracting its dimensions, the other parts gradually resume the condition they were in prior to delivery; so that, in the course of three or four weeks, it is impracticable to pro- nounce positively, whether delivery has recently taken place or not. Labour, as thus accom- Fig. 169. plished, is more deserving of the term in the human fe- male than in animals ; and this is partly owing to the large size of the foetal head, and partly to the circum- stance, that in the animal the axis of the pelvis is the same as that of the body, whilst, in the human fe- male, the axis of the brim, as represented by the dotted straight lines in Fig. 168, forms a considerable angle with that of the outlet. The position of the child, exhibited in Fig. 166,—with the face behind and the oc- ciput before,—constitutes the usual presentation in natural labour. Of twelve thousand six hundred and thirty-three children, born at the Hospice de la Maternite of Paris, twelve thousand one hundred and twenty, according to M. Jules Clo- quet, were of this presentation; sixty-three had the face turned for- ward; one hundred and ninety-eight were breech presentations; (see Fig. 169;) in one hundred and forty-seven cases the feet presented; and in three, the knees. All these, however, are cases in which labour can be effected without assistance; the knee and feet presentations Breech Presentation. PARTURITION. 435 being identical, as regards the process of delivery, with that of the breech. But, whenever any other part of the foetus presents, the position is unfavourable, and requires that the hand should be intro- duced into the uterus, with the view of bringing down the feet, and converting the case into a foot presentation. The following table, drawn up from data furnished by Velpeau, will show the comparative number of presentations, according to the experience of the individuals mentioned. TABLE EXHIBITING THE RATIO OF PRESENTATIONS IN 1000 CASES. ACCORDING TO Merri Mde. Mde. Hospital man. Bland. Boivin. Lacha-pelle. Nagele. Lovati of the Faculte. Boer. Regular, or of the vertex, 924 944 969 933 933 911 980 I. Occipito anterior, 908 944 910 895 a. Occipito-cotyloid (left) 760 717 537 Do. (right) 179 209 b. Occipito-pubian, 0.29 II. Occipito-posterior, 9.4 9 a. Fronto-cotyloid (left) 5.3 7.3 b. Do. (right) 4.4 2.9 Face presentation, 2.2 2.6 3.6 4.6 8.8 Mento-iliac (right) 2.6 Of the pelvis, 36 28 29 36 47 29 Of the foot, 12.7 9.4 14 10.3 Of the knees, 0.19 0.40 Of the breech, 23 13 18 22 19 Of the trunk, 4.6 5.3 4.8 Requiring Forceps, 6.6 4.7 4.6 3.4 36 5.7 --------- Turning, 16 4.7 7.8 7.2 5.9 --------- Cephalotomy, 3.3 5.2 4.77 0.53 2.4 1.5« It is found that the period of the twenty-four hours has some influence upon the process of parturition; about five children being born during the night for four during the day.b The parturient and child-bed condition is not devoid of danger to the female; yet the mortality is less than is generally, perhaps, ima- gined. The number of deaths, during labour and subsequently, connected therewith, has been stated to be in Berlin as 1 in 152 ;c in Konigsberg, as 1 in 168 ; and in Wirtemberg, as 1 in 175; a pro- portion much less than during the last century. Dr. Collinsd states, * Velpeau, Traite Elementaire de l'Art des Accouchemens, Paris, 1829; or Meigs's translation, 2d edit. Philad. 1838. See, also, on the same subject, Dr. Collins, Practical Treatise on Midwifery, Lond. 1835. b Quetelet Sur I'Homme, i. 102, Brux. 1835; Dr. Buek, Nachricht von dem Gesund- heits-Zustande der Stadt Hamburg, von N. H. Julius, s. 157, Hamburg, 1829 ; and Dun- glison's Amer. Med. Intelligencer, Sept. 1,1837, p. 213. c Casper, Bcitrage zur Mcdicinisch. Statistik, u. s. w. Berl. 1825 ; and Elements of Medical Statistics, by Dr. B. Hawkins, Lond. 1829. See, also, Quetelet, i. 130; and Amer. Med. Intelligencer, Oct. 16, 1837, p. 265. d Op. citat. p. 366. 436 GENERATION. that of of 16,414 women, delivered in the Dublin Lying-in Hospital, 164 died, or in the proportion of 1 in 100 ; and if, he observes, from this number we deduct the deaths from puerperal fever, which may be considered accidental, the proportion becomes greatly diminished, viz. to 1 in 156 deliveries; and again, if we subtract the deaths from causes not the results of childbirth, the mortality, from effects arising in consequence of parturition, is vastly reduced, viz. to 1 in 244. The further details of this subject belong more appropriately to obstetrics. j. Lactation. When the child has been separated from the mother, and con- tinues to live by the exercise of its own vital powers, it has still to be dependent upon her for the nutriment adapted to its tender con- dition. Whilst in utero this nutriment consisted of fluids placed in contact with it, but, after birth, a secretion serves this purpose, which has to be received into the stomach and undergo the digestive process. This secretion is the milk. It is prepared by the mamma or breasts, the number, size, and situation of which are characteristic of the human species. Instances are, however, on record of three or more distinct mammae in the same individual.* Two such cases are described by Dr. G. C. M. Roberts, of Baltimore.b At times, two nipples are met with on one breast. Three cases of the kind are given by Tiedemann. In some instances, the supernumerary breasts have been on other parts of the body.0 Each breast contains a mammary gland, surrounded by the fat of the breast, and resting on the pectoralis major muscle. It is formed of several lobes, united by a somewhat dense cellular tissue, and consisting of smaller lobules, which seem, again, composed of round granulations, of a rosy-white colour, and of about the size of a poppy seed. These granula or acini, according to Reil,a cannot be dis- tinguished in the mammae of the virgin. The glandular granula give origin to ihe excretory ducts, called tubuli lactiferi or galacto- phori, which are tortuous, extensible, and transparent. These enlarge and unite with each other, so that those of each lobe remain distinct from, and have no communication with, the ducts of any other lobe. All these finally terminate in sinuses, or reser- voirs, near the base of the nipple, which are fifteen or eighteen in * Dr. Robt. Lee, London Medical Gazette, Jan. 20,1838; Medico-Chirurg. Transact. vol. xxi., Lond. 1838; and Mr. Thursfield, Lond. Med. Gaz. Match 3, 1828, p. 898. b Baltimore Medical and Surgical Journal, ii. 497, Baltimore, 1834. c Art. Cas Rares, in Diction, des Sciences Medicales; Journal de Physiologie, par Magendie, Janv. 1827 ; Hedenus, art. Brust (weibliche,) in Encyclop. WOrterbueh der Medicin. Wissenschaft. vi. 352, Berlin, 1832; art. Brustwarze, ibid. p. 406; Davis's Principles and Practice of Obstetric Medicine, ii. 777, Lond. 1836; and Petrequin in Gazette Medicale de Paris, No. xiii. Avril 1, 1837. d Schlemm, art. Bruste, in Encyclop. Worterb. der Medicin. Wissenschaft. vi. 332, Berlin, 1831. LACTATION. 437 number, and open on the nipple, without having communication with each other. The size and shape of the breast are chiefly caused by the cellu- lar tissue in which the mammary gland is situate: this is covered by a thin layer of skin, which is extremely soft and delicate, and devoid of folds. In the middle of the breast is the tubercle, called the nipple, mammella, or teat,—a prominence consisting of an erec- tile spongy tissue, differing in colour from the rest of the breast. The nipples do not project directly forwards, but forwards and outwards, for wise purposes,* which have been thus depicted by Sir Astley Cooper.—" The natural obliquity of the mammella or nipple forwards and outwards, with a slight turn of the nipple up- wards, is one of the most beautiful provisions in nature both for the mother and her child. To the mother, because the child rests upon her arm and lap, in the most convenient position for sucking; for if the nipple and breast had projected directly forwards, the child must have been supported before her in the mother's hands in a most inconvenient and fatiguing position, instead of its reclining upon her side and arm. But it is wisely provided by nature, that when the child reposes upon its mother's arm, it has its mouth directly applied to the nipple, which is turned outwards to receive it, whilst the lower part of the breast forms a cushion upon which the cheek of the infant tranquilly reposes." The erection of the nipple, which is so manifest during the pro- cess of suckling, and can be readily produced by handling it, has been supposed to be owing to an arrangement similar to that of the corpora cavernosa penis, or to a venous circle surrounding the nipple ;b but Sir Astley Cooper attributes it simply to an afflux of blood into the capillaries of the part. Around the nipple is the areola, which is of a rosy hue in youth, but becomes darker in the progress of life, and the capillary system of which is so delicate as to blush, like the countenance, under simi- lar emotions. The changes, produced on the areola by gestation, have been already described. The skin, at the base of the nipple, and on its surface, is rough, owing to the presence of a number of sebaceous follicles, called by Sir Astley Cooper the " tubercles of the areola," which secrete a fluid for the lubrication of the part, and for defending it from the action of the secretions of the mouth of the infant during lactation. Numerous arteries, veins, nerves and lymphatics,—the anatomical constituents of organic textures in general,—also enter into the composition of the mammae and nipples.6 The secretion of milk is liable to longer intermissions than any * On the Anatomy of the Breast, p. 12, London, 1840. b Prof. Sebastian, Tijdschrift voor Natuurlijke Geschiedenis en Physiologie, door J. Van der Hoeven en W. H. de Vriese, 2de Deel, bl. i., Amsterdam, 1835. c See, on the Intimate Structure of the Mammary Glands, Sir Astley Cooper, op. cit.; and Mr. Solly, art. Mammary Glands, Cyclop, of Anatomy and Physiology, part xxi., April, 1841. 37* 438 GENERATION. other function of the kind. In the unmarried and chaste female, although the blood, whence milk is formed, may be constantly pass- ing to the nipple, no secretion takes place from it. It is only during gestation and some time afterwards, as a general rule, that the necessary excitation exists to produce it. Yet although largely allied to the generative function,—the mammae undergoing their chief developement at puberty and becoming shrivelled in old age,— the secretion may arise independently of impregnation; for it has been witnessed in the unquestionable virgin, in the superannuated female, and even in the male sex. The fact as regards the unim- pregnated female is mentioned by Hippocrates. Baudelocque* states, that a young girl at Alencon, eight years old, suckled her brother for the space of a month. Dr. Gordon Smithb refers to a manuscript in' the collection of Sir Hans Sloane, which gives an account of a woman, at the age of sixty-eight, who had not borne a child for more than twenty years, and who nursed her grand- children, one after another.6 Professor Hall of the University of Maryland, related to the author the case of a widow, aged fifty, whom he saw giving suck to one of her grandchildren, although she had not had a child of her own for twenty years previously. The secretion of milk was solicited by putting the child to her breast during the night, whilst weaning it. Dr. Francis, of New York, describes the case of a lady, who, fourteen years previously, was delivered of a healthy child after a natural labour. " Since that period," he remarks, " her breasts have regularly secreted milk in great abundance, so that, to use her own language, she could at all times easily perform the office of a nurse:" and Dr. Kennedy/ of Ashby-de la Zouch, has described the case of a woman, who men- struated during lactation, suckled children uninterruptedly through the full course of forty-seven years, and, in her eighty-first year, had a moderate, but regular supply of milk, which was rich, and sweet, and did not differ from that yielded by young and healthy mothers. In a note, with which the author has been recently favoured by Dr. Samuel Jackson—formerly of Northumberland county, Pa., now of Philadelphia—a case is described, of a lady, certainly above sixty-five years of age, who nursed one of her daughter's twins. She had not borne a child for many years, and was suddenly endowed with a full flow of milk. A lady of Northumberland observed to Dr. Jackson, " that she could not but admire the beautiful fulness and contour of her bosom."6 Dr. Richard Clarke/ of Union Town, South Alabama, gives the case of a lady, who had never borne a child, and who was requeste4 * Art. d'Accouchement, i. 188, Paris, 1822. b Forensic Medicine, p. 484. c See a similar case, by Mr. Temple, in North of England Med. and Surg. Journal, i. 230. d Medico-Chirurgical Review for July, 1832. e A similar case is given by Audubert, in Journal de la Societe de Medecine Pratique de Montpellier; and Encyclographie des Sciences Medicales, Fevrier, 1841, ji.299. f Dunglison's American Medical Intelligencer, April 16, 1838, p. 19. LACTATION. 439 to take charge of an infant, during the illness of its mother. In the course of the night, the infant became restless and fretful, and the lady—to quiet it—put her nipple into its mouth. This was done from time to time, until the milk began to flow. An interesting fact, connected with this case was, that some time afterwards she conceived, and at the expiration of the usual term was delivered of a fine child. Dr. Clarke refers to other cases, which would appear to show, in another form, the intimate and mysterious sympathy that exists between the mammae and the uterus. But these, and cases of a similar nature, of which there are many on record,1 do not possess the same singularity as those of the function being executed by the male. Yet we have the most unquestionable authority in favour of the occurrence of such instances. A Bishop of Corkb relates the case of a man who suckled his child after the death of his wife. Humboldt adduces one of a man, thirty-two years of age, who nursed his child for five months on the secretion from his breasts; Captain Franklin,0 gives a similar instance; and Professor Hall, of the University of Maryland, exhibited to his obstetrical class, in the year 1827, a coloured man, fifty-five years of age, who had large, soft, well-formed mammae, rather more conical than those of the female, and projecting fully seven inches from the chest; with perfect and large nipples. The glandular structure seemed to the touch to be exactly like that of the female. This man, accord- ing to Professor Hall, had officiated as wet-nurse, for several years, in the family of his mistress, and he represented, that the secretion of milk was induced by applying the children, entrusted to his care, to the breasts, during the night. When the milk was no longer required, great difficulty was experienced in arresting the secretion. His genital organs were fully developed.*1 It appears, therefore, that the secretion of milk may be caused, independently of a uterus, by soliciting the action of the mammary glands, but that this is a mere exception to the general rule, accord- ing to which the secretion is as intermittent as gestation itself. We have noticed, as one of the signs of pregnancy, that the breasts become enlarged and turgid, denoting the aptitude for the formation of the fluid; and it not unfrequently happens that, towards the mid- dle and latter periods of pregnancy, milk will distil from the nip- ples. This fluid, however, as well as that which flows from the breasts during the first two or three days after delivery, differs somewhat from milk, containing more serum and butter, and less caseum, and it is conceived to be more laxative, so as to aid the expulsion of the meconium. This first milk is called colostrum, pro- togala, &c, and, in the cow, constitutes the biestings or beastings. 1 Elliotson's Blumenbach, 4th edit. p. 509, 1828. * Philos. Trans, xii. 813. c Narrative of a Journey to the Polar Sea, p. 157. d For similar cases, see C. W. Mehliss, Ueber Virilescenz und Rejuvenescenz thieri- scher Korper, s. 41 & 71, Leipz. 1838; Belloc, Cours de Medec. Legale, p. 52, Paris, 1819; Fodere, Traite de Medecine Legale, i. 440; Coxe's Medical Museum, i. 267; Beck's Medical Jurisprudence, 6th edit. i. 188, New York, 1838; and Montgomery on the Signs and Symptoms of Pregnancy, p. 70, London, 1837, or Dunglison's Ameriean Medical Library Edition, Philadelphia, 1838. 440 GENERATION. Generally, about the third day after confinement, the mammae become tumid, hard, and even painful, and the secretion from this time is established, the pain and distention soon disappearing. It is hardly necessary to discuss the views of Richerand," who considers the milk to be derived from the lymph; of others who derive it from the chyle; of Raspail, who is disposed to think, that the mammary glands are in connexion, by media of a communication yet unknown, with the mucous surface of the stomach, and that they subtract, from the alimentary mass, the salts and organizing materials which enter into the composition of the milk; or of Girard of Lyons, who gratuitously asserts, that there is in the abdomen an apparatus of vessels,—intermediate between the uterus and mammae, —which continue inactive, except during gestation, and for some time after delivery, but, in those conditions, are excited to activity.11 All these notions are entirely hypothetical, and there is no reason for believing, that this secretion differs from others, as regards the kind of blood from which it is separated. The separation takes place in the tissue of the gland, and the product is received by the lactiferous ducts, along which it is propelled by the fresh secretion continuously arriving, and by the contractile action of the ducts themselves, the milk remaining in the ducts and sinuses, until the mammae are, at times, considerably distended and painful. The excretion of the milk takes place only at intervals. When the lactiferous ducts are sufficiently filled, a degree of distention and uneasiness is felt, which calls for the removal of the contained fluid. At times, the flow occurs spontaneously; but, commonly, only when solicited either by sucking or drawing the breast, the secretion under such circumstances being very rapid, and the contraction of the galactophorous ducts such as to project the milk through the orifices in a thready stream. Milk is a highly azoted fluid, composed of water, caseum, sugar of milk, certain salts,—as the muriate, phosphate, and acetate of potassa, with a vestige of lactate of iron and earthy phosphate,—and a little lactic acid. According to Berzelius,0 cow's milk consists of cream, and milk properly so called,—the cream consisting of butter, 4.5; cheese, 3.5; whey, 92.0;—and the whey, of milk and salt, 4.4;— the milk containing water, 928.75;—cheese, with a trace of butter, 28.01; sugar of milk, 35.00; muriate of potassa, 1.70; phosphate of potassa, 0.25; lactic acid, acetate of potassa, and lactate of iron, 6.00; and phosphate of lime, 0.30.d Raspail8 defines milk to be an aqueous fluid, holding albumen and * Nouveaux Elemens de Physiologie, 7eme edit, Paris, 1817. b Adelon's Physiologie de I'Homme, 2de 6dit. iv. 141, Paris, 1839. c Medico-chirurgical Transactions, vol. iii. d See, on the Microscopic Examination, &c. of the Milk, Donne, Du Lait, et en par- ticulier de celui des Nourrices, &c, Paris, 1837, or notice thereof in Brit, and For. Med. Rev., July, 1838, p. 181. See, also, Donne, Comptes rendus, Sept. 18, 1839, or Dun- glison's Amer. Med. Intelligencer, Jan. 1, 1840, p. 306; and Nasse, Muller's Arehiv. 1840, Heft, iii, or Brit, and For. Med. Rev., Jan. 1841, p. 228. e Chimie Organique, p. 345, Paris, 1833. LACTATION. 441 oil in solution, by means of an alkali, or alkaline salt, which he suggests may be the acetate of ammonia,—and, in suspension, an immense number of albuminous and oleaginous globules. The following table exhibits the discrepant results of the investigations of Brisson, Boyssou, Stipriaan Luiscius and Bondt, Schubler, and John, in 1000 parts of the milk of different animals—as given by Burdach.' Observers. Specific gravity. Butter. Cheese. Sugar of milk. Water. Extract. $ C Brisson, » j Boyssou, 10409 38.24 51.26 20.73 886.19 3.45 g \ Luiscius, 10350 58.12 153.75 41.87 746.25 =■ f John, 54.68 31.25 39.06 875.00 a , Brisson, 10324 | \ Boyssou, 24.88 39.40 31.33 900.92 3.45 * < Luiscius, 10280 26.87 89.37 30.62 853.12 % 1 Schubler, 24.00 50.47 77.00 848.53 * John, 23.43 93.75 39.06 843.75 g ( Brisson, 10341 J 1 Boyssou, 29.95 52.99 20.73 892.85 3.45 3 ) Luiscius, 10360 45.62 91.25 43.75 819.37 5? \ John, 11.71 105.45 23.43 849 39 a ( Brisson, 10364 «, 1 Boyssou, 0.57 18.43 32.25 938.36 10.36 g J Luiscius, 10450 0.00 16.25 87.50 896.25 =; V John, 0.00 64.84 35.15 900.00 > ( Brisson, 10355 £ j Boyssou, 0.92 19.58 39.97 932.60 6.91 3 ] Luiscius, 10230 0.00 33.12 45.00 921.87 ;= \ John, 0.00 11.71 46.87 941.40 Brisson, 10203 Boyssou, 32.25 11.52 46.08 903.92 6.91 Luiscius, 10250 30.00 26.87 73.12 870.00 John, 23.43 15.62 39.06 921.87 From this table, an approximation may be made, as to the main differences between the milk of those animals, but it is not easy to explain the signal discrepancy amongst observers as to the quantity of the different materials in the milk of the same animal. Much, of course, may be dependent upon the state of the milk at the time of the experiment, but this can scarcely account for the whole dis- crepancy. From a great number of experiments, MM. Deyeux and Parmen- tierc classed six kinds of milk, which they examined, according to * Physiologie als Erfahrungswissenschaft, B. ii. and v. 2te Auflage, s. 259, Leipz. 1835. b Sec, also, MM. O'Henry and A. Chevalier, Journal de Pharmacie, Juin et Juillet, 1839 ; M. Lecanu, ibid., Avril, 1839; MM. D'Arcet et Petit. Revue Medicale, Fev. ou Mirs, 1839; and Sir Astley Cooper and Dr. G. Bird in Sir Astley Cooper on the Anatomy of the Breast, Lond. 1840. c Precis d'Experiences, &c. sur les differentes especes de Lait, Strasbourg, an vii. 1790. 442 GENERATION. the following table, as regards the relative quantity of the materials they contained. Caseum. Butter. Sugar of milk. Serum. Goat. Sheep. Cow. Sheep. Cow. Goat. Woman. Ass. Mare. Ass. Woman. Mare. Ass. Woman. Mare. Woman. Ass. Mare. Cow. Goat. Sheep. Cow. Goat. Sheep. Human milk, therefore, contains more sugar of milk and less cheesy matter than that of the cow; hence it is sweeter, more liquid, less coagulable, and incapable of being made into cheese. When human milk is first drawn, it is of a bluer colour than that of the cow. It resembles rather whey, or cow's milk much diluted with water. If allowed to rest, it separates, like the milk of other animals, into cream and milk, the quantity of the cream being one- fifth to one-third of that of the milk. The milky portion, however, appears semi-transparent like whey, instead of being white and opaque like that of the cow. During the first days of its remaining at rest, abundance of cream and a little curd are separated, and lactic acid is developed. The specific gravity of human milk was found by Dr. Rees to be 1.0358, and the solid contents 12 per cent. The specific gravity of the cream was 1.021.a The quantity and character of the milk differ according to the quantity and character of the food,—a circumstance, which was one of the greatest causes of the belief, that the lymphatics or chy- liferous vessels convey to the mammae the materials for the secre- tion. The milk is, however, situate in this respect like the urine, which varies in quantity and quality, according to the amount and kind of solid or liquid food taken. The milk is more abundant, thicker, and less acid, if the female lives on animal food, but pos- sesses the opposite qualities when vegetable diet is used. It is apt, also, to be impregnated with heterogeneous matters, taken up from the digestive canal. The milk and the butter of cows indicate unequivocally the character of their pasturage, especially if they have fed on the turnip, wild onion, &c. Medicine, given to the mother, may in this way act upon the infant.b Serious—almost fatal—narcotism was induced in the infant of a professional friend of the author, by a dose of morphine administered to his wife. The quantity of milk secreted is not always in proportion to the bulk of the mammae: a female whose bosom is of middle size often secretes more than another in whom it is much more developed;— the greater size being usually owing to the larger quantity of adi- 1 Sir Astley Cooper, op. cit. >> See, on this subject, and also for an analysis of the Milk, Simon, Journal de Phar- jnacie, Juin, 1839, and Sir Astley Cooper on the Anatomy of the Breast, Lond. 1840. EMBRYOLOGY. 443 pous tissue surrounding the mammary gland, and this tissue is in nowi-e concerned in the function. The secretion of milk usually continues until the period when the organs of mastication of the infant have acquired the necessary developement for the digestion of solid food: it generally ceases during the second year. For a great part, or the whole of this time, the menstrual flux is suspended; and if both the secretions,—mam- mary and menstrual,—go on together, the former is usually impo- verished and in small quantity. Whilst lactation continues, the female is less likely to conceive; and hence the importance,—were there not even more weighty reasons,—of the mother's suckling her own child, in order to prevent the too rapid succession of children. From observations, made at the Manchester Lying-in Hospital, on one hundred and sixty married women, Mr. Robertona concludes, that in seven out of eight women, who suckle for as long a period as the working classes in England are in the habit of doing—about fifteen and a half months on the average—there will be an interval of fifteen months between parturition and the commencement of the subsequent pregnancy;—and that, in a majority of instances, when 'suckling is prolonged to even nineteen or twenty months, pregnancy does not take place till after weaning. When menstruation recurs during suckling, it is an evidence that the womb has, again, the organic activity, that befits it for impregnation. CHAPTER II. FCETAL EXISTENCE.--EMBRYOLOGY. The subject of foetal existence forms so completely a part of the function we are considering, that its investigation naturally suc- ceeds that of the part performed by the parents in its production; and more especially as the developement of the foetus is synchronous with all the uterine changes that have been pointed out. By most writers on physiology, it has been the custom to include this subject under the same head as generation, but the anatomy and physiology of the foetus have recently been so much studied as to sanction their separation. 1. ANATOMY OF THE FffiTTJS. The uncertainty, which hangs over the immediate formation of the new individual, has been already mentioned: and it is not neces- sary for us to do more than refer to the previous description of the different views regarding the predominance of the paternal or ma- » Edinb. Med. and Surg. Journ. Jan. 1837. 444 EMBRYOLOGY. ternal influence over the character of the product of generation. The microscopical observations of Mr. Bauer, under the superin- tendence of Sir Everard Home,a would seem to show, that the human ovum and that of the quadruped consist of a semitransparent, elastic, gelatinous substance, enveloped in two membranous cover- ings; that this substance is formed in the ovarium independently of the male influence, but requires the application of such influence to undergo its developements. Von Baerb is also of opinion, that the chorion exists ready formed in the ovulum of the ovary; but Valentin0 and Dr. Allen Thomson1' think it probable that the chorion is added to the ovulum after it has left the Graafian vesicle,—that is, during its passage from the ovary to the uterus, somewhat in the same manner as the albumen or shell is added to the egg of the oviparous animal in its passage through the oviduct. The latter observer properly remarks, however, that the chorion, in its struc- ture and functions differs much from those parts of the egg of the bird;—in almost every quadruped being inservient to useful purposes in establishing a union between the ovum and the uterus, by the placenta or some analogous structure. The period, at which the embryo is first perceptible in the ovule," differs in different animals. Haller asserts, that in the sheep, whose term of gestation is five months, he could observe nothing more than a homogeneous mucus for the first sixteen days; but, at this time, membranes seemed to envelope the ovule and to give it shape; and on the twenty-fifth day, an opaque point indicated the foetus. Haighton, in experimenting on rabbits, could detect no change be- fore the sixth day, and the foetus was not perceptible till the tenth. In the case, related by Sir Everard Home, to which we have so fre- quently referred, the embryo was perceptible, under the microscope of Mr. Bauer, and although its weight did not probably exceed a grain, the future situation of the brain and spinal marrow was appa- rent. One of the earliest specimens of the human ovum is depicted by Velpeau.6 He had reason for believing that it was discharged on the fourteenth day after sexual intercourse. This ovum is de- scribed to have been of the size of a pea—the foetus already formed, although very small, and all the points of structure in both foetus and ovum corresponding with one another so as to show that the pro- duct was natural. After the tenth day, and especially after the fifteenth, the ovule can be separated into two distinct sets of parts,—the dependencies of the foetus, and the foetus itself. These, in the course of pregnancy, be- come more and more readily separable. Each will require some » Lect. on Comp. Anat. iii. 292, Lond. 1823. b De Ovi Mammalium et Hominis Genesi, Lips. 1827. « Handbuch der Entwickelungsgeschichte, u. s. w., and a translation from it, by Dr. Martin Barry, in Edinb. Med. and Surg. Journ., p. 393, for April, 1836. d Art. Generation, in Cyclop, of Anat. and Physiol, part xiii. p. 453, for Feb. 1838. e Embryologie ou Ovologie Humaine, Paris, 1834; and Dr. Allen Thomson, art Generation, Cyclop, of Anat. and Physiol, part iii. p. 454, Feb. 1838. ANATOMY OF THE F(ETUS—CHICK IN OVO. 445 consideration. Prior to this, however, it may be well to refer to the changes that the e^s undergoes during incubation; in which we have an opportunity of observing the transmutations at all periods of foetal formation, independently of any connexion with either parent. The subject has engaged the attention of physiologists of all ages; but it is chiefly to those of more modern times—as Hunter, Cuvier, Dutrochet,a Pander,5 Rolando, Sir Everard Home, Prevost and Dumas, Von Baer, Kuhlemann,c Dbllinger, D'Alton, Oken,d Purkinje,6 Rathke, C. F. Wolff, Breschet, Burdach, Reichert, Krause, Seiler, Bojanus, Meckel, E. H. Weber, Valentin, Coste, Owen, Sharpey, Velpeau, Flourens, Allen Thomson, T. W. Jones, Bischoff, Schwann and Schleiden, J. Muller, Rudolph Wagner and Martin Barry—the two last of whom received, about the same time, medals for their researches'; the former from the Institute of France, and the latter from the Royal Society of London—that we are in- debted for more precise information on the subject; although, unfor- tunately, they are by no means of accordance on many points. The investigations of Sir Everard Home, aided by those of the excellent microscopic observer, Mr. Bauer,f are accompanied by engravings, some of which we shall borrow in elucidation of the following brief description. The egg of a bird,—of a hen for example,—consists of two descrip- tions of parts;—those which are but little concerned in the deve- lopement of the new being, and which remain after the chick is hatched,—as the shell and the membrane lining it,—and such as undergo changes along with those of the chick and co-operate in its formation,—as the white, the yolk, and the cicatricula or molecule. The shell is porous, to allow of the absorption of air through it; and of the evaporation of a part of the albumen or white. In the ova- rium it is albuminous, but in the cloaca becomes calcareous. The membrane, membrana testa seu albuminis, that lines the shell, is of a white colour, and consists of two layers, which separate from each other at the greater end of the egg, and leave a space filled with air, owing to the evaporation of the white and the absorption of air. This space is larger the older the egg, and is called the folliculus aeris or air-chamber. The albumen or white does not exist whilst the egg is attached to the ovary. It is deposited between the yolk and the shell, as the egg passes through the oviduct. Of the white there are two distinct kinds;—the outermost, thin and fluid, which evaporates in part, and is less abundant in the old than in the fresh * Journal de Physique, p. 88, for 1819. b Beitrage zur Entwickelungsgeschichte des Huhnchens im Ei, Wurz. 1817. c Observ. quredam circa Negotium Generationis in ovibus fact, Gotting. 1753. ' Isis, 1829, p. 407. e Svinboke ad Ovi AviumHistoriam ante Incubationem, p.16,Wratislav.1825; andart. Ei, in Encyclopad. Worterb. der Medicin. Wissenschaft. Band x. 107, Berl. 1834. See, also, Tiedemann, in Handbuch der Zoologie, Heidelb. 1814; Seiler, art. Ei, Pierer's Anat. Phys. Real. Worterb. Band ii. s. 459, Leipz. und Altenb. 1818; and art. Embryo, ibid. s. 522. f Sir E. Home's Lectures on Comp. Anat. iii. 427. VOL. II. 38 446 EMBRYOLOGY. laid egg, and another, situate within the last, which is much denser, and only touches the shell at the smaller extremity of the egg by a prolongation of its substance, which has been called theligament of ihe white. The yolk or Fig. 170. Ovarium of the laying Hen; natural size. The Ova at different stages of increment. yolk-ball, vitellus,seems to be at first sight a semifluid mass with- out organization; but on closer examination, it is found to consist of a yolk-bag, two epidermic membranes, which envelope it as well as the cicatricula or molecule. Two prolongations of these membranes, knotty, and terminating in a flocculent extremity in the albumen, called chalaza or poles, are attached to the two ends of the egg and thus suspend it. It is also surrounded by a proper membrane; and lastly, under the epi- dermic coats of the yolk, and upon its pro- per coat lies the cica- tricula, macula, tread of the cock, or gela- tinous molecule from It is found before the which the future embryo is to be formed yolk leaves the ovarium. The external membrane of the yolk, when it quits the yolk-bag, is very thin and delicate; its surface is studded over with red dots, which disappear in its passage along the oviduct. When this mem- brane is removed, there is a natural aperture in the thick, spongy covering under it, through which is seen the cicatricula or molecule, surrounded by an areola, halo or circulus. On examination, this areola proves to be nothing more than that part of the surface of the yolk, which is circumscribed by the margin of the aperture. The molecule or cicatricula itself, (Fig. 172,) has a granulated appearance; and, according to Sir Everard Home,a is made up, in the centre, of globules srWh part of an inch in diameter, sur- rounded by circles of a mixed substance; about two-thirds consist- * Op. cit. iii. 426. ANATOMY OF THE FCETUS—CHICK IN OVO. 447 ing of the same small globules, and one-third of larger oval globules, about fgVotn part of an inch in diameter; the last resembling in shape the oval red globules of the blood in the bird. Besides the globules, there is some fine oil, which appears in drops, when the parts are immersed in water. Oval globules and oil are also met with in the yolk itself, but in small proportion and devoid of colour. If the ovum, according to Valentin,1 be lacerated and its contents minutely examined, the cicatricula is found like a grayish white disk, which in its whole periphery is dense, granular and opaque, but in the centre presents a clear nongranular, and perfectly diapha- nous point. Purkinje found, that when he removed the dark granular mass, by suc- tion with a small tube, there remained a perfectly transparent vesicle, filled with a pellucid lymph, which had a decidedly spherical form, but being extremely deli- cate, was very easily lacerated, and its fluid escaped. As he found this, which later naturalists have named—after its dis- coverer—the " Purkinjean vesicle," in the ova of the ovarv, but could not see it in ova, which had already entered the ovi- Sl£ ^Kl'y TuTyoik0™: duct, he save it the name "germinal vesi-Vesicle of Pu,rkinJe imbedded in the . , ,£,. . D . . cumulus, c. Vitellary membrane, d. ClC. ihe granular membrane,---ltS Inner and outer layers of the capsule thickened portion, the so called cicatri- 0Jva%« ovum- *■ Indusium of the cula,—and the germinal vesicle, constitute those parts of the ovum, which pass immediately into the original foundation of the embryo, the blastoderma or " germinal mem- brane."1' When the egg leaves the ovarium, (Fig. 170,) the egg ovarial yolk- bag gives way at the median line, and the yolk drops into the com- mencement of the oviduct. The yolk-bags are exceedingly vascular, the outer membrane of the yolk being connected to them by vessels and fasciculi of fibres, but being readily separable from them. During the first hours of incubation no change is perceptible in the egg, but, about the seventh, the molecule is evidently enlarged, and a mem- brane, containing a fluid substance, is observable. This membrane is the Amnion, Colliquamentum, Sacculus Colliquamenti, JVidus pulli or Areola pellucida Wolfii, or transparent area. At this time a white Section of a hen's egg within the Ovary. * Handbuch der Entwickelungsgeschichte des Menschen, u. s. w. Berlin, 1835; Edin- burgh Med. and Surg. Journ. April, 1836, p. 393; and in Bernhardt, Symbolce ad ovi Mammalium Historiam ante Prregnationem, Wratisl. 1834. See, also, Dr. A. Thomson, art. Generation, in Cyclofwed. of Anatomy and Physiology, Feb. 1838, part xiii. p. 452 ; Burdach, Physiologie als Erfahrungswissenschaft, 2te Auflage, i. 87, Leipz. 1835 ; Mr. Thomas Wharton Jones, on the First Changes in the Ova of the Mammifera, in Philos. Transact, part ii. for 1837, p. 339 ; and Dr. Martin Barry, Philosoph. Transact. 1838, pp. 301, 341; 1839, p. 307, and 1839-40. b See Fig. 155, and the accompanying description, at page 378, of this volume; also, R. Wagner, Elements of Physiology, translated by R. Willis, M. D. p. 87, Lond. 1S41. 448 EMBRYOLOGY. line is perceptible in the molecule, which is the rudimental foetus; and, even at this early period, according to Sir Everard Home,a the brain and spinal marrow can be detected. The areola has extended itself; and the surface, beyond the line which formed its boundary, has acquired the consistence of a membrane, and has also a distinct line by which it is circumscribed. This Sir Everard calls the outer areola. In the space between these two areolae are distinct dots of an oily matter. Fig. 172. Fig. 173. New laid Egg with its Molecule, fyc. Egg thirty-six hours after incubation. In twelve hours the rudiments of the brain, are more distinct, as well as those of the spinal marrow. A dark line or primitive trace or streak may now be discovered in the cicatricula towards the centre of the transparent area, lying in the transverse axis of the egg, and swollen at the extremity, which lies to the left when the smaller end of the egg is turned from us. The larger extremity indi- cates the place where the head is afterwards formed, and occupies nearly the centre of the transparent area. As incubation proceeds, the whole cicatricula expands; towards the twelfth or fourteenth hour the germinal membrane divides into two layers of granules, the uppermost being entitled the serous or animal layer; the lower the mucous or vegetative layer,—the former being more extended than the latter. In a few hours later, the separation of the germinal membrane becomes more distinct, and between the serous and the mucous layers there appears a new layer, called the vascular. In one or other of the three primitive layers—serous, mucous, or vas- cular—is contained the germ of all the tissues and organs of the body, and it is conceived, that their histogeny admits of a distinct group- » Op. cit. iii. 426. ANATOMY OF THE FCETUS—CHICK IN OVO, 449 ing. The serous layer, for example, is presumed to give origin to the organs of animal life—the brain, spinal marrow, the organs of the senses,the skin,muscles,tendons, ligaments, cartilages,and bones; from the mucous layer originate the organs of vegetative life—the intestinal canal, lungs, liver, spleen, pancreas, and other glands; and from the vascular layer the heart and vascular system are presumed to arise. It is not decided to which layer the reproductive system should be assigned. According to Dr. Barry,a there does not occur in the maminiferous ovum any such phenomenon as the splitting of a germinal membrane into the " so called serous, vascular, and mucous laminae. Nor is there any structure entitled to be denomi- nated a germinal membrane, for it is not a previously existing mem- brane, which originates the germ, but it is the previously existing germ which, by means of a hollow process, originates a structure having the appearance of a membrane." In thirty-six hours, the head is turned to the left side. The cere- brum and cerebellum appear to be distinct bodies. The iris is per- ceptible through the pupil. The intervertebral nerves are nearly formed; those nearest the head being the most distinct. A portion of the heart is seen. At this period, under the inner areola, apparently at the termination of the spinal marrow, a vesicle begins to protrude, which is seen earlier in some eggs than in others. The while of egg is found to be successively absorbed by the yolk, so that the latter is rendered more fluid and its mass augmented. The first appearanc'e of red blood is discerned on the surface of the yolk-bag towards the end of the second day. A series of points is observed, which form grooves; and these closing constitute vessels, the trunks of which become connected with the chick. The vascular surface itself is called figura venosa, area or area vasculosa; and the vessel, by which its margin is defined, vena terminalis and circulus venosus. The trunk of all the veins joins the vena portae, whilst the arteries, that ramify on the yolk-bag, arise from the mesenteric artery of the chick, and have hence been called omphalo-mesenteric. In two days and a half, the spinal marrow has its posterior part inclosed; the auricles and ventricles of the heart are perceptible, and the auricles are filled with red blood. An arterial trunk from the left ventricle gives off two large vessels,—one to the right side of the embryo, the other to the left,—sending branches over the whole of the areolar membrane, which is bounded on each side by a large trunk carrying red blood; but the branches of the two trunks do not unite, there being a small space on one side, which renders the circle incomplete. This Sir Everard Home calls the areolar circulation. In three days, the outer areola has extended itself over one-third of the circumference of the yolk, carrying the marginal arteries alone with it to the outer edge, but diminished in size. The brain is much enlarged ; the cerebellum being yet the larger of the two. » Op. cit. and Wagner's Elements of Physiology, p. 153, (note,) Lond. 1841. 38* 450 ExVIBRYOLOGY. The spinal marrow and its nerves are most distinctly formed ; and the eye appears to want only the pigmentum nigrum. The right ventricle of the heart contains red Fig. 174. blood; the arteries can be traced Egg, opened three days after incubation. optic nerve and pigmentum nigrum of the eye are visible. The outer areola extends half over the yolk, with which a larger portion of the white is now mixed. In five days, the vesicle has acquired a great size and become exceedingly vascular; the yolk, too, has become thinner, in con- sequence of its admixture with more of the albumen. In six days, the vascular membrane of the areola has extended farther over the yolk. The vesicle, at this time, has suddenly expanded itself in the form of a double night-cap over the yolk, and its coverings are beginning to inclose the embryo, the outermost layer being termed the chorion, the innermost the middle membrane. The amnion contains a fluid in which the embryo is suspended by the vessels of the vesicular membrane. The brain has become enlarged so as to equal in size the body of the embryo. Its vessels are distinctly seen. The two eyes equal the whole brain in size. The parietes of the thorax and abdomen have begun to form; and the wings and legs are nearly completed, as well as the bill. At this period muscular action has been noticed. In seven days, the vesicle,—having extended over the embryo,— has begun to inclose the areolar covering of the yolk, and a pulsa- tion is distinctly seen in the trunk that supplies the vesicular bag with blood. The pulsations were, in one case, seventy-nine in a minute, whilst the embryo was kept in a temperature of 105°; but when the temperature was diminished, they ceased, and when again raised to the same point, they were reproduced. The muscles of the limbs now move with vigour. ANATOMY OF THE FfETUS—CHICK IN OVO. 45] In eight days, the anastomosing branches of the vesicular circu- lation have a strong pulsation in them. Fig. 175. Fig. 176. Egg, five days after Incubation. Egg, ten days after Incubation. In nine days, the vesicle has nearly inclosed the yolk. In ten days, no portion of the yolk is observable on the outside of the vesicle. The embryo being taken out of the amnion,—now become full of water,—the thorax is found to be completely formed, and the roots of the feathers very distinct. The contents of the egg, during the formation of the embryo, become much diminished in quantity, and the void space is gra- dually occupied by a gas, which was examined by Mr. Hatchett, and found to be atmospheric air deposited at the great end of the egg between the layers of the membrane lining the shell. Even prior to incubation, there is always a small portion of air in this place which is supposed to be employed in aerating the blood, from the time of its first acquiring a red colour, till superseded in that office by the external air acting through the egg-shell upon the blood in the vessels of the vesicular membrane, with which it is lined. Between the period of fourteen and eighteen days, the yolk be- comes completely inclosed by the areolar membrane; and, at the expiration of the latter period, the greater part of the yolk is drawn into the body, as in Fig. 177. At twenty days, the chick is com- pletely formed, the yolk is entirely drawn in, and only portions of the membrane belonging to the vesicle are seen externally. The yolk-bag has a narrow tube, ductus vitellarius, ductus vitelli intesti- 452 EMBRYOLOGY. nalis and apophysis, half an inch long, connecting it with the intes- tine, eight inches above the openings of the caeca into the gut. Fig. 177. Fig. 178. The whole of these changes, which, in the viviparous animal, are effected within the womb of the mother, take place in the incubated chick by virtue of its own powers; and without any assistance, except that of the atmospheric air and of a certain degree of warmth. In the course of incubation, the yolk becomes constantly thinner and paler, by the admixture of the white; and, at the same time, innumerable fringe-like vessels, with flocculent extremities, of a singular structure, form on the inner surface of the yolk-bao-, and hang into the yolk. The office of these is presumed to'be, to absorb the yolk and to convey it into the veins of the yolk-bag, where it is assimilated to the blood and applied to the nutrition of the new being. Blumenbach states, that in numerous and varied microsco- pical examinations of the yolk-bag, in the latter weeks of incuba- tion, he thinks he has observed the actual passage of the yolk from the yellow flocculent vessels of the inner surface of the bao- into the blood-vessels which go to the chick. He has, at all events, seen manifest yellow streaks in the red blood contained in those veins. When the chick has escaped from the shell, the yolk, we have seen, is not exhausted, but is received into the abdomen, and as it communicates with the intestinal tube, it is, for some time, a source of supply to the young animal, until its strength is equal to DEPENDENCIES OF THE FfETUS. 453 the digestion of its appropriate food. The highly vascular chorion is manifestly an organ of aeration, like the placenta of the mam- malia.1 The changes induced in the mammalia greatly resemble those in the bird. a. Dependencies of the Fcctus. These are the parts of the ovum, that form its parietes, attach it to the uterus, connect it with the foetus, and are inservient to the nutrition and developement of the new being. They are generally conceived to consist,—First, of two mem- branes, according to common belief, which constitute the parietes of the ovule, and which are concentric ; the outermost, called the chorion,—the innermost, filled with a fluid, in which the foetus is placed, and called the amnion or amnios. By Boer and Granville,b a third and outer membrane has been admitted,—the cortical mem- brane or cortex ovi. Secondly, of a spongy, vascular body, situate without the chorion, covering about one-quarter of the ovule, and connecting it with the uterus,—the placenta. Thirdly, of a cord of vessels,—extending from the placenta to the foetus, the body of which is penetrated at the umbilicus, by the vessels, called the um- bilical cord or navel siring; and lastly, of three vesicles—the umbili- cal, allantoid, and erythroid, which are considered to be concerned in foetal nutrition. 1. The chorion (which has received various names,)0 is the outer- most of the membranes of the ovule. About the twelfth day after conception, according to Velpeau,*1 it is thick, opaque, resisting, and flocculent at both surfaces. These flocculi, in the part of the ovum that corresponds to the tunica decidua reflexa, aid its adhe- sion to that membrane; but, in the part where the ovum corre- sponds to the uterus, they become developed to constitute the pla- centa. At its inner surface, the chorion corresponds to the amnion. These two membranes are, however, separated during the earliest period of foetal existence, by a gelatinous or albuminous fluid ;e but at the expiration of three months, the liquid disappears and they are afterwards in contact. By many anatomists, the chorion is conceived to consist origi- nally of two laminae; and by Burdachf these have been distinguished by different names; the outer lamina being called by him exocho- 1 For a minute and recent account of the developement of the chick, illustrated by numerous engravings, see R. Wagner's Elements of Physiology, translated by Robert Willis, M. D. p. 80, London, 1841. See. also, Burdach, Die Physiologie als Erfahrung- swissenschaft, 2tc Band, 2te Auflage, Leipz. 1837, and Towne, Guy's Hospital Reports, Oct. 1839, p. 385. b Graphic Illustrations of Abortion, Lond. 1834. c Haller, Element. Physiol, viii. 188; Burdach's Physiologie als Erfahrungswissen- scaft, ii. 57; and Velpeau, Embryologie, Paris, 1833. d Embryologie ou Ovologie Humaine, Paris, 1833. e Purkirije, art. Ei, Encyclopad. Worterbuch der Medicinisch. Wissenschaft. x. 149, Berlin, 1834. 1 Op. citat. ii. 57. 454 EMBRYOLOGY. rino ; the inner, endochorion. Velpeau denies this, and asserts, that he has never been able to separate them, even by the aid of previous maceration.* As the placenta is formed on the uterine side of the chorion, the membrane is reflected over the foetal surface of that organ, and is continued over the umbilical cord, as far as the umbilicus of the foetus, where it is confounded with the skin, of which it conse- quently appears to be a dependence. As pregnancy advances, the chorion becomes thinner, and less tenacious and dense, so that at the full period, it is merely a thin, transparent, colourless membrane, much more delicate than the amnion. Haller, Blumenbach and Velpeau affirm it to be devoid of vessels; but, according to Wrisberg, it receives some from the umbilical trunks of the foetus, and, according to others, from the decidua. Dutrochet conceives it to be an extension of the foetal bladder. Its vascularity, according to Dr. Granville, is proved by its diseases, which are chiefly of an inflammatory character, ending in thicken- ing of its texture; and he affirms, that there is a preparation in the collection of Sir Charles Clarke, which shows the vessels of the chorion as evidently as if they were injected. 2. The amnion lines the chorion concentrically. It is filled with a serous fluid, and contains the foetus. In the first days of foetal existence, it is thin, transparent, easily lacerable, and somewhat resembling the retina. At first, it adheres to the chorion only by a point, which corresponds to the abdomen of the foetus; the other portions of the membranes being separated by the fluid already men- tioned, called the false liquor amnii. Afterwards, the membranes coalesce, and adhere by very delicate cellular filaments; but the adhesion is feeble, except at the placenta and umbilical cord. In the course of gestation, this membrane becomes thicker and tougher; and, at the full period, it is more tenacious than the chorion, elastic, semitransparent and of a whitish colour. Like the chorion, it covers the foetal surface of the placenta, envelopes the umbilical cord, passes to the umbilicus of the foetus, and commingles there with the skin.b It has been a question, whether the amnion is supplied with blood- vessels. Velpeau denies it: Haller and others have maintained the affirmative. Haller asserts, that he saw a branch of the umbilical artery creeping upon it. The fact of the existence of a fluid within it, which is presumed to be secreted by it, would also greatly favour the affirmative. But, admitting that it is supplied with blood-vessels, a difference has existed, with regard to the source whence they proceed; and anatomical investigation has not succeeded in dis- * See, also, Weber's Hildebrandt's Handbuch der Anatomie, iv. 492, Braunschweig, 1832; Seiler, in Picrer's Medicinisch. Real Worterb. ii. 470, Leipz. und Altenb. 1818; Huter, art. Eihilute, in Encyclop. Worterb. der Medicin. Wissensch. xi. 237, Berlin, 1834; and Purkinje, art. Ei, in Encyclop. Worterb. der Medicin. Wissensch. x. 144, Berlin, 1834. b Velpeau, Embryologie, &c, Paris, 1833, DEPENDENCIES OF THE FCETUS. 455 pelling it. Monro affirms, that on injecting warm water into the umbilical arteries of the foetus, the water oozed from the surface of the amnion. Wrisberg asserts, that he noticed the injection to stop between the chorion and amnion ; and Chaussier obtained the same results as Monro, by injecting the vessels of the mother. The amnion contains a serous fluid, the quantity of which is in an inverse ratio to the size of the new being; so that its weight may be several drachms, when that of the foetus is only a few grains. At first, the liquor amnii,—for so it is called,—is transparent; but, at the full period, it has a milky appearance, owing to flocculi of an albuminous substance held in suspension by it. It has a saline taste, a spermatic smell, and is viscid and glutinous to the touch. Vauque- lin and Buniva" found it to contain, water, 98.8; albumen, chloride of sodium, soda, phosphate of lime, and lime, 1.2. That of the cow, according to these gentlemen, contains amniotic acid; but Prout, Dulong, and Labillardiere and Lassaigne were not able to detect it. Dr. Rees analyzed several specimens. He found its specific gravity to be about 1.007 or 1.008, and its mean composition in two cases at 7^ months to be as follows: water, 986.8; albumen (traces of fatty matter), 2.8 ; salts soluble in water, 3.7 ; albumen from albumi- nate of soda, 1.6; salts soluble in alcohol, 3.4; lactic acid, urea, 1.7. Total, 1000. The salts consisted -of chloride of sodium, and car- bonate of soda, with traces of alkaline sulphate and phosphate.b Dr. Voglc analyzed it at two different periods of pregnancy, at 3^ months and 6 months, and found the constituents to vary as follows: 3£ Months Water,.......978.45 Alcoholic extract, consisting of uncertain ) q fiq animal matter and lactate of soda, - ( Choride of sodium,.....5.95 Albumen (as residuum,) .... 10.79 Sulphate and phosphate of lime, and loss, - 0.14 1000. 1000. Specific gravity,......1.0182 - - " 1.0092 No inferences can, however, be drawn from these cases as to the proportion of solid matters at different periods of utero-gestation, inasmuch as the subject of the first case died of an inflammatory disease; the other, in a state of cachexia. Proutd found some sugar of milk in the liquor amnii of the human female; Berzelius detected fluoric acid in it; Scheele, free oxygen ;e and Lassaigne/ in one * Annales de Chimie, torn, xxxiii.; and Memoir, de la Societe Medicale d'Emula- tion, iii. 229. b Ancell, Lectures on the Physiology and Pathology of the Blood, April 25, 1840, p. 154. c Mailer's Arehiv.; and Brit, and For. Med. Review, July, 1838, p. 248. i Annals of Philosophy, v. 417. e Dissert, de Liquoris Amnii Arteria? Asperse Fcetuum Humanorum Natura et Usu, &c, Copenh. 1799. f Arehiv. General, de Med., ii. 308. 990.29 0.34 2.40 6.77 0.30 456 EMBRYOLOGY. experiment, a gas resembling atmospheric air; in others a gas com- posed of carbonic acid and azote. J. Miiller,3 however, was never able to detect oxygen in it. The chemical history of this substance is, consequently, sufficiently uncertain, nor is its origin placed upon surer grounds;—some physiologists ascribing it to the mother, others to the foetus;—opinions fluctuating, according to the pre- sumed source of the vessels, that supply the amnion with arterial blood. It has even been supposed to be the transpiration of the foetus, or its urine. One reply to these views is, that we find it in greater relative proportion when the foetus is small. Meckel thinks, that it chiefly proceeds from the mother, but that, about the termi- nation of pregnancy, it is furnished in part by the foetus. The functions, however, to which, as we shall see, it is probably inser- vient, would almost constrain us to consider it a secretion from the maternal vessels; and what perhaps favours this notion is the fact, that if a female be made to take rhubarb for some time prior to parturition, the liquor amnii will be found tinged with it.b It is in- teresting, also, to recollect, that, in the experiments of Dr. Blundell, —which consisted in obliterating the vulvo-uterine canal in rabbits, and, when they had recovered from the effects of the injury, putting them to the male,—although impregnation did not take place, the wombs,—as in extra-uterine pregnancy,—were evolved, and the waters collected in the uterus. The fluid, consequently, must, in these cases, have been secreted from the interior of the uterus. May not the liquor amnii be secreted, in this manner, throughout the whole of gestation, and pass through the membranes of the ovum by simple imbibition ? and may not the fluid secretions of the fetus, which are discharged into the liquor'amnii, pass through the mem- branes, and enter the system of the mother, in the same way'( The quantity of the liquor amnii varies in different individuals, and in the same individual, at different pregnancies, from four ounces to as many pints. Occasionally, it exists to such an amount as to throw obscurity even over the very fact of pregnancy. An instance of this kind, strongly elucidating the necessity of the most careful attention on the partof the practitioner in such cases, occurred in the practice of a respectable London practitioner,—a friend of the author. The abdomen of a lady had been for some time enlarging by what was supposed to be abdominal dropsy: fluctuation was evident, yet the case appeared to be equivocal. A distinguished accoucheur, and a surgeon of the highest eminence, were called in consultation, and after examination the latter declared, that " it was an Augean stable, which nothing but the trocar could clear out." As the lady, however, was even then complaining of inter- mittent pain, it was deemed advisable to make an examination per vaginam. The os uteri was found dilated and dilating, and in a few hours after this formidable decision, she was delivered of a • Handbuch der Physiologie, i. 305, Berlin, 1833. b Granville, Graphic Illustrations of Abortion, p. xxi., Lond. 1834. DEPENDENCIES OF THE F(ETUS. 457 healthy child, the gush of liquor amnii being enormous. After its discharge the lady was reduced to the natural size, and the dropsy, of course, disappeared! 3. The cortical membrane or cortex ovi is, according to Boer and Granville,* the one, which is usually regarded as a uterine produc- tion, and denominated the decidua reflexa. It surrounds the ovule when it descends into the uterus, and envelopes the shaggy chorion. This membrane is destined to be absorbed during the first months of utero-gestation, so as to expose the next membrane to the con- tact of the decidua, with which a connexion takes place in the part where the placenta is to be formed..In that part, Boer and Granville consider, that the cortex ovi is never altogether obliterated, but only made thinner; and in process of time it is converted into a mere pellicle or envelope, which not only serves to divide the filiform vessels of the chorion into groups or cotyledons, in order to form the placenta, but also covers those cotyledons. This Dr. Granville calls the membrana propria. 4. Placenta. This is a soft, spongy, vascular body, formed at the surface of the chorion, adherent to the uterus, and connected with the foetus by the umbilical cord. The placenta is not in existence during the first days of the embryo state; but its formation com- mences, perhaps, with the arrival of the embryo in the uterus. In the opinion of some, the flocculi, which are at first spread uni- formly over the whole external surface of the chorion, gradually congregate from all parts of the surface into one, uniting with ves- sels proceeding from the uterus, and traversing the decidua, to form the placenta; the decidua disappearing from the uterine surface of the placenta about the middle of pregnancy, so that the latter comes into immediate contact with the uterus. In the opinion of others, the placenta is formed by the separation of the layers of the chorion, and by the developement of the different vessels, that creep between them. Velpeaub maintains, that the placenta forms only at the part of the ovule, which is not covered by the true decidua, and which is immediately in contact with the uterus; and that it results from the developement of the granulations that cover this part of the chorion; these granulations or villi, according to Velpeau, being gangliform organs containing the rudiments of the* placental vessels. Others,0 again, regard it as formed by the growth of the vessels of the uterus into the decidua serotina. The mode in which the placenta is attached to the uterus has always been an interesting question with physiologists; and it has been revived, of late, by Messrs. Lee,d Radford,e and others. A com- mon opinion has been, that the large venous canals of the uterus are a Graphic Illustrations of Abortion, part iv., Lond. 1835. b Embryologie ou Ovologie Humaine, p. 63. c Von Baer, Entwickelungsgeschichte, u. s. w., s. 279. - Philosoph. Transactions for 1832; and Remarks on the Pathology and Treatment of some of the most important Diseases of Women, Lond. 1833. ' On the Structure of the Human Placenta, Manchester, 1837. vol. 11. 39 458 EMBRYOLOGY. uninterruptedly continuous with those of the placenta. Wharton and Reuss\ and a number of others, conceive that, at an early period of pregnancy, the part of the uterus, in contact with the ovum, becomes fungous or spongy, and that the fungosities, which constitute the uterine placenta, commingle and unite with those of the chorion so intimately, that laceration necessarily occurs when the placenta is extruded; and Dubois goes so far as to consider the milk fever as a true traumatic disease, produced by such rupture! The opinion of Messrs. Lee, Radford, Velpeau and others is, that the maternal vessels do not terminate in the placenta; but that apertures—por- tions scooped out, as it were,—exist in their parietes, which are closed up, according to the two first gentlemen, by the true decidua,— according to Velpeau, by a membranule or anorganic pellicle, which he conceives to be thrown out on the fungous surface of the placenta, or by some valvular arrangement, the nature of which has not been discovered; but these apertures have no connexion, in his opinion, with any vascular orifice, either in the membrane or the placenta. The mode, therefore, in which these authors consider the placenta to be attached to the uterus is, so far as it goes, somewhat unfavour- able to the idea generally entertained, that the maternal vessels pour their fluid into the maternal side of the placenta, whence it is taken up by the radicles of the umbilical vein. Whatever blood is exhaled must necessarily pass through the decidua, according to Lee and Radford; or through the pellicle, according to Velpeau. More recently, Dr. Leeb has somewhat modified his views, and now believes, that the circulation in the human ovum, in the third month of gestation, is carried on in the following manner:—The maternal blood is conveyed by the arteries of the uterine decidua into the interstices of the placenta and villi of the chorion. The blood, which has circulated in the placenta, is returned into the veins of the uterus by the oblique openings in the decidua covering the pla- centa. The blood, which has circulated between the villosities of the chorion, passes through the openings in the decidua reflexa into the cavity between the two deciduous membranes, whence it is taken up by the numerous apertures and canals that exist, according to him, in the uterine decidua, and so passes into the veins of the uterus. Biancini6 maintains, that a number of flexuous vessels con- nect the uterus directly with the placenta, which are developed immediately after the period of conception. These utero-placental vessels, he says, are not prolongations of the uterine vessels, but a new production. Recently, Dr. John Reidd has carefully examined into this point of anatomy. On separating the adhering surfaces of the uterus and * Novcs quaedam Observationes Circa Structuram Vasor. in Placent. Human, et pecu- liarem hujus cum Utero Nexum, Tubing. 1784. b London Med. Gazette, Dec. 1838; and Amer. Journ. of the Med. Sciences, May, 1839, p. 189. c Sul Commercio Sanguigno tra la Madre e il Feto, Piea, 1833. * Edinb. Med. and Surg. Journ. Jan. 1841, p. 4. DEPENDENCIES OF THE F(ETUS. 459 placenta cautiously under water, he satisfied himself, but not without considerable difficulty, of the existence of the utero-placental vessels described by the Hunters. After a portion of the placenta had been detached in this manner, Dr. Reid's attention was attracted towards a number of rounded bands passing between the uterine surface of the placenta and the inner surface of the uterus, several of which could be drawn out in the form of tufts from the mouths of the uterine sinuses. On slitting up some of the uterine sinuses with the scissors, these tufts could be seen ramifying in their interior. These were ascertained to be prolongations of the foetal placental vessels, and to protrude into the open mouths of certain of the uterine sinuses, and in those placed next the inner surface of the uterus only. These tufts were surrounded externally by a soft tube, similar to the soft wall of the utero-placental vessels, which passed between the margin of the open mouths of the uterine sinuses and the edges of the orifices in the decidua through which the tufts protruded into the sinuses. On examining the tufts, as they lay in the sinuses, it was evident, that though they were so far loose, and could be floated about, yet they were bound down firmly at various points by reflections of the inner coat of the venous system of the mother upon their outer surface. Dr. Reid farther satisfied himself that the interior of the placenta is composed of numerous trunks and branches, each including an artery, and an accompanying vein, every one of which, he believes, is closely ensheathed in prolongations of the inner coat of the vascu- lar system of the mother, or at least in a membrane continuous with it. According to this view of the structure of the placenta, the inner coat of the vascular system of the mother is prolonged over each individual tuft, so that when the blood of the mother flows into the placenta through tho curling arteries of the uterus, it passes into a large sac formed by the inner coat of the vascular system of the mother, which is intersected in many thousands of different direc- tions, by the placental tufts projecting into it like fringes, and pushing its thin wall before them in the form of sheaths, which closely envelope both the trunk and each individual branch composing these tufts. From this sac, the maternal blood is returned by the utero- placental veins without having been extravasated, or without having left the maternal system of vessels. Into this sac in the placenta, containing the blood of the mother, the tufts of the placenta hang like the bronchial vessels of certain aquatic animals, to which they have a marked analogy. This sac is protected and strengthened on the foetal surface of the placenta by the chorion, on the uterine surface by the decidua vera, and on the edges or margin by the decidua reflexa. In this view, the foetal and maternal portions are every where intimately intermixed with tufts of minute placental vessels, their blunt extremities being found lying immediately under the chorion covering its foetal surface, as well as towards its uterine surface. 'The discovery of the prolongations of the foetal placental vessels 460 EMBRYOLOGY. into some of the uterine sinuses, Dr. Reid thinks, is principally valuable, as it presents us with a kind of miniature representation of the whole structure of the placenta; and the reason why the pla- cental tufts are not perceptible on the uterine surface of the pla- centa expelled in an accouchement is, that they are so strongly bound down by the reflection of the inner coat of the uterine sinuses that they are torn across. Professors Alison, Allen Thomson, and J. Y. Simpson inspected the preparations of Dr. Reid, and expressed themselves satisfied that the placental tufts were prolonged into the uterine sinuses, and that the inner coat of the veins was prolonged upon them. Dr. Sharpey, too, confirms the views of Dr. Reid from his own observation of impregnated uteri. A somewhat similar view to that of Dr. Reid is entertained by E. H. Weber.a In whatever manner originally produced, the placenta is distin- guishable in the second month, at the termination of which it covers two-thirds, or, at the least, one-half of the ovum; after this, it is observed lo go on successively increasing. Prior to the full term, however, it is said to be less heavy, more dense, and less vascular, owing—it has been conceived—to several of the vessels, that formed it, having become obliterated and converted into hard, fibrous fila- ments ; a change, which has been regarded as a sign of maturity in the foetus, and a prelude to its birth. At the full period, its extent has been estimated at about one- fourth of that of the ovum; its diameter from six to nine inches; its circumfe- rence twenty-four inches; its thickness from an inch to an inch and a half at the centre, but less than this at the circumference;b and its weight, with the umbilical cord and mem- branes, from twelve to twenty ounces. All this is subject, however, to much variation. It is of a circu- lar shape, and the cord is usually inserted into its centre. It maybe attached to any part of the uterus, but is usually found to- wards the fundus. Of its two surfaces, that which corresponds to the uterus is divided into irregularly rounded lobes or cotyledons, * Hildebrandt's Handbuch der Anatomie des Menschen,iv.496, Braunschweig, 1832, See, also, Wagner, op. cit. p. 201, and Dr. Reid, op. cit. p. 11. b Burdach's Physiologie als Erfahrungswissensch. ii. 403. Fig. 179. Uterine surface of the Placenta. DEPENDENCIES OF THE FfETUS. 461 and it is covered by a soft and delicate cellulo-vascular membrane, which by many is considered to be the decidua vera.a Wrisberg,b Lobstein,c and Desormeaux,d however, who consider, that the decidua disappears from behind the placenta about the fourth or fifth month, regard it as a new membrane; and Bojanus, believing it to be Fig. 180. produced at a later period than the decidua vera, gives it the name of membrana decidua serotina* (See Fig. 161, page 417 of this volume.) Breschet, again, maintains that two la- minae—decidua vera and deci- dua reflexa—are found inter- vening between the uterus and placenta,1" whilst Velpeau maintains that the true deci- dua never exist there! The fatal or umbilical sur- face is smooth,polished, cover- ed by the chorion and amnion, Fmtalsurfaceof the Piacenta. and exhibits the distribution of the umbilical vessels, and the mode in which the cord is attached to the organ. The following are the anatomical constituents of the placenta, as usually described by anatomists. First. Blood-vessels, from two sources, the mother and the foetus. The former proceed from the uterus, and consist of arteries and veins, of small size but considerable number. The vessels, which proceed from the foetus, are those that constitute the umbilical cord;—viz. the umbilical vein, and the umbilical arteries. These vessels, after having penetrated the foetal surface of the placenta, divide in the substance of the organ, so that each lobe has an arterial and a venous branch, which ramify in it, but do not anastomose with the vessels of other lobes. Secondly. Expansions of the chorion, which are described by some as dividing into cellular sheaths, and accompanying the vessels to their final ramifications;—an arrangement which is, however, contested by others. Thirdly. White filaments, which are numerous in propor- tion to the advancement of pregnancy, and which seem to be obliterated vessels. Fourthly. A kind of intermediate cellular tissue, serving to unite the vessels together, and which has been regarded, by some anatomists, as an extension of the decidua accompanying * See Dr. John Reid, Edinb. Med. and Surg. Journal, Jan. 1841, p. 8. b Observ. Anat. Obstetric, de Structura Ovi et Secundinar. Human. &c. Gotting. 1783. c Essai sur la Nutrition du Foetus, Strasbourg, 1802. d Art. 03uf Humain, in Diet, de Medecine. e I?is, von Oken, fur 1821. r Memoir, de I'Academ. Royal, de Medec. torn. ii. Pari?, 1833. 39* 462 EMBRYOLOGY. those vessels. Lastly. A quantity of blood poured into this interme- diate cellular tissue, which may be removed by washing. In addition to these constituents, a glandular structure has been presumed to exist in it; as well as lymphatic vessels.3 Fohmann" affirms, that the umbilical cord, in addition to the blood-vessels, consists solely of a plexus of absorbents, which may be readily injected with mercury. This has been done also by Dr. Mont- gomery, of Dublin. These lymphatics of the cord communi- cate with a network of lymphatics, seated between the placenta and the amnion, the termination of which Fohmann could not de- tect, but he thinks they pass to the uterine surface of the placenta. These vessels proceed to the umbilicus of the child,, and chiefly unite ' with the subcutaneous lymphatics of the abdominal parietes ^follow the superficial veins; pass under the crural arches; ramify on the iliac glands; and terminate in the thoracic duct. Lobstein and Meckel say they have never been able to detect lymphatics in the cord. Chaussier and Ribesc and Mr. Caesar Hawkinsd describe nerves in the placenta proceeding from the great sympathetic of the foetus. The uterine and the foetal portions of the placenta are generally described as quite distinct from each other, during the two first months of foetal life; but afterwards they constitute one mass. Still, the uterine vessels remain distinct from the foetal; the uterine arte- ries and veins communicating freely with each other, as well as the foetal arteries and veins; but no direct communication existing be- tween the maternal and foetal vessels. Until of late, almost every obstetrical anatomist adopted the division of the placenta into two parts, constituting—as it were—two distinct placentae,—the one maternal, the other foetal. Messrs. Lee, Radford, and others have, however, contested this point, and have affirmed, with Velpeau, that the human placenta is entirely foetal. The very fact, indeed, of the existence of a membrane, or—as M. Velpeau calls it—a '; mem- branule," between the placenta and the uterus, would destroy the idea of any direct adhesion between the placenta and uterus, and make the placenta wholly foetal. Yet the point is still contested,—by those especially, who consider that the maternal vessels ramify on one surface of the placenta, and the foetal on the other.6 It is generally supposed, that the placenta is most frequently attached to the right side of the uterus, but Nagelef found the oppo- site to be the fact in his examinations. In six hundred cases, which * Granville, op. citat. p. xix. b Sur les Vaisseaux Absorbans du Placenta, &c. Liege, 1832; and Amer. Journ. May, 1835, p. 174. c Journal Universel des Sciences Medicales, i. 233. A Sir E. Home, Lect. on Comp. Anat. v. 185, Lond. 1828; Lond. Lancet, June, 1833; and Messrs. Mayo and Stanley, Report on the Preparations of Impregnated Uteri in the Hunterian Museum, Lancet, June, 22, 1833. e See Weber's Hildebrandt's Handbuch der Anatomie, iv. 495, Braunschweig, 1832. f Die geburtshiilfliche Auscultation, Mainz, 1838; and Brit, and For. Med. Review, Oct. 1839, p. 371. DEPENDENCIES OF THE FCSTUS. 463 he carefully ausculted, the placenta was found in two hundred and thirty-eight cases on the left side, and in one hundred and forty-one on the right. 5. Umbilical cord.—From the foetal surface of the placenta a cord of vessels passes, which enters the umbilicus of the foetus, and has hence received the name umbilical cord, as well as that of navel- string. It forms the medium of communication between the foetus and the placenta. During the first month—Pockels* says the first three weeks—of fcetal existence, the cord is not perceptible; the embryo appearing to be in contact, by the anterior part of its body, with the mem- branes of the ovum. Such, at least, is the description of most ana- tomists ; but Velpeaub says it is erroneous. The youngest embryo he dissected had a cord. At a fortnight and three weeks old, the length is three or four lines; and, he thinks, his examinations lead him to infer, that, at every period of fcetal developement, the length of the cord is nearly equal to that of the body, if it does not exceed it a little. In an embryo, a month old, Beclardc observed vessels creepinc, for a certain space, between the membranes of the ovum, from the abdomen of the foetus to a part of the chorion, where the rudiments of the future placenta were visible. During the fifth week, the cord is straight, short, and very large, owing to its containing a portion of the intestinal canal. It presents, Fig. 181. also, three or four dilatations, sepa- rated by as many contracted por- tions or necks; but these gradually disappear; the cord lengthens, and be- comes smaller, and occasionally it is twisted, knotted, and tuberculated :„ « „* l Umbilical Cord. in a strangely in- explicable manner, (Fig. 181.) After the fifth week it contains^- besides the duct of the umbilical vesicle—the omphalo-mesenteric vessels, and a portion of the urachus, or of the allantoid, and of the intestines. At about two months, the digestive canal enters the abdo- men : the urachus, the vitelline canal—to be mentioned presently— and the vessels become obliterated, so that, at three months, as at the full period, the umbilical cord is composed of three vessels,— ■ * Ncue Beitrage zur Entwickelungsgeschichte des Menschlichen Embryo, in Isis von Oken, 1825. b Embryologie, ou Ovologie Humaine, Paris, 1833. c Embryologie, ou Essai Anatomique sur le Fetus Humain, Paris, 1821. 464 EMBRYOLOGY. the umbilical vein, and two arteries of the same name,—of a pecu- liar jelly-like substance, and it is surrounded, as we have seen, by the amnion and chorion. The vessels will be more particularly described hereafter. They are united by a cellular tissue, containing the jelly of the cord, or of Wharton, a thick albuminous secretion, which bears some resemblance to jelly, and the quantity of which is very variable. In the foetus, the cellular tissue is continuous with the sub-peritoneal cellular tissue; and in the placenta, it is considered to accompany the ramifications of the vessels. The length of the cord varies, at the full period, from twelve inches to forty-eight. The most common length is eighteen inches/ It has been already remarked, that Chaussier, Ribes, and Hawkins have traced branches of the great sympathetic of the foetus as far as the placenta; and the same has been done by Durr,b Rieck,c and others. 6. Umbilical vesicle.—This vesicle, called also intestinal vesicle, appears to have been first carefully observed by Albinus.d Dr. Gran- ville,' however, Tascribes its discovery to Bojanus/whilst others have assigned it to Diemerbroeck.g It was unknown to the ancients; and, amongst the moderns, is not universally admitted to be a physiolo- gical condition. Osiander and Dollinger class it amongst imaginary organs; and Velpeau remarks, that out of about two hundred vesicles, which he had examined, in foetuses under three months of developement, he had met with only thirty in which the umbilical vesicle was in a state, that could be called natural. Under such circumstances, it is not easy to understand how he could distinguish the physiological from the pathological condition. If the existence of the vesicle be a part of the physiological or natural process, the majority of vesicles ought to be healthy or natural; yet he pro- nounces the thirty in the two hundred to be alone properly formed; and, of consequence, one hundred and seventy to be morbid or un- natural. This vesicle is described as a small pyriform, round or spheroidal sac; which, about the fifteenth or twentieth day after fecundation, is of the size of a common pea. It probably acquires its greatest dimen- sions in the course of the third or fourth week. After a month, Velpeau always found it smaller. About the fifth, sixth or seventh week it is of about the size of a coriander seed. After this, it be- comes shrivelled and disappears insensibly. It seems to be situate * Dr. Churchill, in Dublin Journal of Med. Science, March, 1837. b Dissert. Sistens Funicul. Umbilic. Nervis carere, Tubing. 1815. c Ultrum Funiculus Umbilicalis Nervis polleat aut careat, Tubing. 1816. d Annotat. Academic, lib. i. p. 74. e Graphic Illustrations of Abortion, p. xii. Lond. 1834. f Meckel's Arehiv. iv. s. 34; and Journ. Complement dujDict. des Sciences Medicales ii. 1818, p. 84. s Opera, p. 304, Ultraject. 167'2; see Mackenzie, in the Edinburgh Medical and Sur- gical Journal for January, 1836, p. 46; and D'Zondi, Supplement ad Anatom. et Phy- siol, pottissimum comparat. Lips. 1806. For a list of those who have described it, see Purkinje, in art. Ei, of Encyclopad. Medicin. Worterb. x. 156, Berlin, l'834; and Weber's Hildebrandt's Handbuch der Anatom. iv. DEPENDENCIES OF THE FCETUS. 465 between the chorion and amnion, and is commonly adherent either to the outer surface of the amnion, or to the inner surface of the chorion, but, at times, is situate loosely between them. Fig. 182. Diagram of the Fmtus and Membranes about the sixth week, (from Carus.) a. Chorion. 6. The larger absorbent extremities, the site of the placenta, c. Allantois. d. Amnion. e. Urachus. e. Bladder. /. Vesicula umbilicalis. g. Communicating canal between the vesicula umbilicalis and intestine, h. Vena umbilicalis. i i. Arteriae umbilicales. I. Vena omphalo-mese- raica. k. Arteria omphalo-meseraica. n. Heart, o. Rudiment of superior extremity, p. Rudiment of lower extremity. The characters of the vitelline pedicle, as Velpeau terms it, which attaches the vesicle to the embryo, vary according to the stage of gestation. At the end of the first month, it is not less than two, nor more than six lines long, and about a quarter of a line broad. Where it joins the vesicle, it experiences an infundibuliform expansion. Its continuity with the intestinal canal appears to be undoubted.3 Up to twenty or thirty days of embryonic life, the pedicle is hollow, and, in two subjects, M. Velpeau was able to press the contained fluid from the vesicle into the abdomen, without lacerating any part.b Generally, the canal does not exist longer than the expiration of the fifth week, and the obliteration appears to proceed from the umbilicus towards the vesicle. The parietes of the vitelline pouch—as M. Velpeau also calls it, from its analogy to the vitelline or yolk-bag of the chick—are strong and resisting; somewhat thick, and difficult to tear. As the umbilical vesicle of brutes has been admitted to be con- tinuous with the intestinal canal, anatomists have assigned it and its 1 Purkinje, art. Ei, in op. cit. x. 157. b See, also, R. Wagner, Elements of Physiology, translated by Robert Willis, M. D. p. 194, Lond. 1841. 466 EMBRYOLOGY. pedicle three coats. Such is the view of Dutrochet. Velpeau has not been able to detect these in the human foetus. He admits, how- • ever, a serous surface, and a mucous surface. The vesicle is evidently supplied with arteries and veins, which are generally termed omphalo-mesenteric or omphalo-mesaraic, but, by Velpeau, vitello-mesenteric, or, simply, vitelline. The common belief is, that they communicate with the superior mesenteric artery and vein; but Velpeau says he has remarked, that they inosculate with one of the branches of the second or third order of those great vessels (canaux); with those, in particular, that are distributed to the caecum. These vessels he considers to be the vessels of nutrition of the umbilical vesicle. The fluid, contained in the vesicle, which Velpeau terms the vitelline fluid, has been compared, from analogy, to the vitellus or yolk of egg. In a favourable case for examination, Velpeau found it of a pale yellow colour; opaque; of the consistence of a thickish emulsion; different in every respect from serosity, to which Albinus, Boerhaave," Wrisberg1' and Lobstein6 compared it, and from every other fluid in the organism; and he regards it as a nutritive sub- stance—a sort of oil—in a great measure resembling that, which constitutes the vitelline fluid of the chick in ovo.A 7. Allantoid vesicle or allantois.—This vesicle—called also mem- brana farciminalis and membrana intestinalis—has been alternately admitted and denied to be a part of the appendages of the human foetus, from the earliest periods until the present day. It has been seen by Emmert, Meckel, Pockels, Velpeau, Von Baer, Burdach and others.*5 It is situate between the chorion and amnion, and communicates, in animals, with the urinary bladder by a duct called urachus. It has been observed in the dog, sheep, cow, in the saurian and ophidian reptiles, birds, &c. M. Velpeauf was never able to detect any communication with the bladder in the human subject, and he is compelled to have recourse to analogy to infer, that any such channel has in reality existed. From all his facts—which are not numerous or forcible—he " thinks himself authorized to say," that from the fifth week after conception till the end of pregnancy, the chorion and amnion are separated by a transparent colourless, or slightly greenish-yellow layer. This layer, instead of being a simple serosity, is lamellated, after the manner of the vitreous humour of the eye. It diminishes in thickness, in proportion to the de- velopement of the other membranes. The quantity of fluid, which its meshes inclose, is, on the contrary, in an inverse ratio with the * Haller, Elementa Physiol, viii. 208. b Descript. Anat. Embrvonis, Gotting. 1764. c Op. cit. p. 42. / • 6 d See, on this and other topics of Embryology, Von Siebold's Journal fur Geburtshulfe, xiv. Heft 3, Leipz. 1835; and Brit, and For. Med. Review, i. 241, Lond. 1836. e Purkinje, art. Ei, in Encyc. Wort, der Medicin. Wissensch. xi. 151, Berlin, 1834. f Embryologie ou OvologicHumaine, Paris, 1833. See, also, Burdach, Die Physio- logie als Erfahrungswissenschaft, ii. 530; Weber's Hildebrandt's Handbuch der Ana- tomie, iv. 509, Braunschweig, 1832; and Meckel's Handbuch, u. s. w., Jourdan and Breschet's French translation, iii. 768, Paris, 1825. DEVELOPEMENT OF THE FC2TUS. 467 progress of gestation. Becoming gradually thinner, it is ultimately formed into a homogeneous and pulpy layer, by being transformed into a. simple gelatinous or mucous layer (enduit,) which wholly disappears, in many cases, before the period of accouchement. Between the reticulated body, as Velpeau terms it, and the allan- toid of oviparous animals, he thinks, there is the greatest analogy. Yet the fluid of the allantoid is very different from the urine, which is supposed, by some, to exist in the allantoid of animals. This fluid, we shall find, has been considered inservient to the nutrition of the new being, but, after all, it must be admitted, that our ideas regarding the vesicle, in man, are far from being determinate. 8. Erythroid vesicle.—This vesicle was first described by Dr. Pockels, of Brunswick, as existing in the human subject. It had been before observed in the mammalia. According to Pockels,3 it is pyriform; and much longer than, though of the same breadth as, the umbilical vessel. Within it, the intestines are formed. Velpeau, however, asserts, that he has never been able to meet with it; and he is disposed to think, that none of the embryos, depicted by Pockels, and by Seiler,b were in the natural state. Such, too, is the opinion of Weber.c According to most obstetrical physiologists, when pregnancy is multiple, the ova in the uterus are generally distinct, but contiguous to each other. By others, it has been affirmed, that two or more children may be contained in the same ovum, but this appears to require confirmation. The placenta of each child, in such multiple cases, maybe distinct; or the different placentae may be united into one, having intimate vascular communications with each other. At other times, in twin cases, but one placenta exists. This gives origin to two cords, and at others to one only, which afterwards bifurcates, and proceeds to both foetuses. Maygrier,d however, affirms uncon- ditionally, that there is always a placenta for each foetus; but that it is not uncommon, in double pregnancies, to find the two placentae united at their margins; the circulation of each foetus being dis- tinct, although the vessels may anastomose. This was the fact in a case of quadruple pregnancy, communicated by M. Capuron to the Academie Royale de Medecine, in Jan. 10th, 1837. b. Developement of the Foetus. The ovule does not reach the uterus until towards the termination of a week after conception. On the seventh or eighth day, it has the appearance referred to in the case so often cited from Sir Everard Home; the future situations of the brain and spinal marrow being recognisable with the aid of a powerful microscope. On the thir- a Isis, von Oken, p. 1342, 1825. b Das Ei und Die Gebarmutter des Menschen, u. s. w. p. 24, Dresd. 1832. c Weber's Hildebrandt's Handbuch der Anatomie, iv. 518, Braunsch. 1832. d Nouvelles Demonstrations d'Accouchemens, Paris, 1822-26. 468 EMBRYOLOGY. teenth or fourteenth day, according to Maygrier, the ovum is per- ceptible in the uterus, and of about the Fig. 183. size of a pea,—according to Pockels, of a Ovum and Embryo, twenty-one days old. About the forty-fifth day, the shape of the child is determinate; and it now, in the language of some anatomists, ceases to be the embryo, and becomes the fatus. According to others it does not become entitled to the latter name until after the beginning of the fourth month.b The limbs resemble tubercles, or the shoots of vegetables; the body lengthens, but preserves its oval shape, the head bearing a considerable proportion to the rest of the body. The base of the *■ Isis, von Oken, December, 1825; and Granville's Graphic Illustrations of Abortion, part vii., Lond. 1834. •> Valentin, in art. Frxtus, Encyclopad. Worterb. der Medicin. Wissensch. xii. 355, Berlin, 1835. DEPENDENCIES OF THE F(ETUS. 469 Fig. 185. Fatus at forty-five trunk is pointed and elongated. Blackish points, or lines, indicate the presence of the eyes, mouth, and nose; and simi- lar, parallel points correspond to the situation of the vertebrae. Length ten lines. In the second month, most of the parts of the foetus exist. The biack points which represented the eyes, enlarge in every dimension ; the eyelids are sketched, and are extremely transparent; the nose begins to stand out; the mouth increases, and becomes open; the brain is soft and pulpy; the heart is largely de- veloped, and opaque lines set out from it; which are the first traces of large vessels. Prior to this period —very early indeed—substances or bodies are perceptible, which were first described, as existing in the fowl, by Wolff,a and in the mammalia by Oken,b and which have been called by the Germans, after their discoverers, Wolffische oder Okensche Korper, (" bodies of Wolff or Oken.") According to J. Muller, they disappear in man very early, so that but slight remains of them are perceptible after the ninth or tenth week of pregnancy. They cover the region of the kidneys and renal cap- sules, which are formed afterwards, and they are presumed to be the organs of urinary secre- tion during the first periods of fcetal existence.0 The fingers and toes are distinct. In the third month, the eyelids are more deve- loped and firmly closed. A small hole is per- ceptible in the pavilion of the ear. The alae nasi are distinguishable. The lips are very distinct, and approxi- mate, so that the mouth is closed. The genital organs of both sexes undergo an extraordinary increase during this month. The penis is very long; the scrotum empty, frequently containing a little water. The vulva is very apparent, and the clitoris promi- nent. The brain, although still pulpy, is considerably developed, as well as the spinal marrow. The heart beats forcibly. The lungs are insignificant; the liver very large, but soft and pulpy, and appears to secrete scarcely any bile. The upper and lower limbs are developed. Weight two and a half ounces ; length three and a half inches. During the fourth month, all the parts acquire great advancement and character, except perhaps the head and the liver, which in- crease less in proportion than the other parts. The brain and spinal marrow acquire greater consistence: the muscular system, which began to be observable in the preceding month, is now distinct; Fatus at two months. ' Theoria Generationis, Hal. 1759. b Oken und Kieser, Beitrage zur Vergleichend. Zoologie, Anatomie und Physiologie, H. i. p. 74, Bamberg und Wurzburg, 1806; and Rathke, in Weber's Hildebrandt's Handbuch der Anatom. iv. 440. 0 Valentin, op. citat. p. 380. . vol. ii. 40 470 EMBRYOLOGY. and slight, almost imperceptible, movements begin to manifest them- selves. The length of the foetus is, at the end of one hundred and twenty days, five or six inches; the weight four or five ounces. Fatus at three months, in its membranes. During the fifth month, the developement of every part goes on; but a distinction is manifest amongst them. The muscular system is well marked, and the movements of the foetus unequivocal. The head is still very large, compared with the rest of the body, and is covered with small, silvery hairs. The eyelids are glued together. Length seven to nine inches; weight six or eight ounces. If the fcetus be born at the end of five months, it may live for a few minutes. In the sixth month, the dermis begins to be distinguished from the epidermis. The skin is delicate, smooth, and of a purple colour; especially on the face, lips, ears, palms of the hands and soles of the feet. It seems plaited, owing to the absence of fat in the subcutane- ous cellular tissue. The scrotum is small, and of a vivid red hue. The vulva is prominent, and its lips are separated by the projection of the clitoris. The nails appear, and, towards the termination of the month, are somewhat solid. Should the fcetus be born now, it is sufficiently developed to breathe and cry, but it dies in a few hours. Length, at six months, ten or twelve inches. Weight under two pounds. During the seventh month, all the parts are better proportioned. DEVELOPEMENT OF THE FCETUS. 471 The head is directed towards the orifice of the uterus, and can be felt by the finger introduced into the vagina, but it is still very mova- ble. The eyelids begin to separate, and the membrane, which pre- viously closed the pupil—the membrana pupillaris—to disappear. The fat is more abundant, so that the form is more rotund. The skin is redder, and its sebaceous follicles are formed, which secrete a white, cheesy substance—the vernix caseosa—that covers it; and the testicles are in progress to the scrotum. The length at seven months is fourteen inches; the weight under three pounds. In the eighth month, the fcetus increases proportionably more in breadth than in length. All its parts are firmer and more formed. The nails exist; and the child is now certainly viable or capable of supporting an independent existence. The testicles descend into the scrotum; the bones of the skull, ribs, and limbs are more or less completely ossified. The length is sixteen inches; the weight four pounds and upwards. , At the full period of nine months, the organs have acquired the developement necessary for the continued existence of the infant. Length eighteen or twenty inches; weight six or seven pounds. Ac- cording to Dr. Granville, length 22 inches; weight from five to eight pounds. Dr. Deweesa says the result of his experience, in this country, makes the average weight above seven pounds. He has met with two ascertained cases of fifteen pounds, and several, which he believed to be of equal weight. Dr. Moore, of New York, had several cases, where the weight was twelve pounds; and a case occurred in that city in 1821, of a foetus, born dead, which weighed sixteen and a half pounds. Dr. Traill0 once weighed a child at the moment of birth, which weighed 14 pounds, and Mr. Park, of Liver- pool, found another to weigh 15 pounds; and a case has been re- corded by Mr. J. D. Owens, in which a still-born child measured 24 inches in length, and weighed seventeen pounds twelve ounces.0 Where there are twins in utero, the weight of each is usually less than in a uniparous case, but their united weight is greater. Duges, of Paris, found that in 444 twins, the average weight was four pounds, and the extreme weights three and eight pounds. The whole of this description amounts to no more than an approxi- mation to the truth. The facts will be found to vary greatly in indivi- dual cases, and, therefore, according to individual experience; and this accounts for the great discordance in the statements of different observers."1 This discordance is strongly exemplified in the follow- ing table, containing the estimates of the length and weight of the fcetus at different periods of intra-uterine existence, as deduced by * Compendious System of Midwifery, 8th edit. Philad. 1836. b Outlines of a Course of Medical Jurisprudence, 2d edit. p. 16, Edinb. 1840, or Amer. Edit, with Notes by the author of this work, p. 27, Philad. 1841. c London Lancet, Dec. 22, 1833. d Burdach's Physiologie als Erfahrungswissenschaft, Band ii.; Valentin, art. Foetus, in Encyc. Worterb, der Medicin. Wissensch, xii. 372, Berlin, 1835; and Trattato Gene- rale di Ostetricia, di Dr. Asdrubali, 2de edizione, i. 152, Roma, 1812, 472 EMBRYOLOGY. Dr. Becka from various observers, and as given by Maygrierb on his own authority, and by Dr. Granville0 as the averages of minute and accurate observations made by Autenrieth, Sommering, Bichat, Pockels, Carus, &c. confirmed by his own observations made on several early ova, and many foetuses examined in the course of seventeen years' obstetrical practice. It is proper to remark, that the Paris pound, poids de marc, of sixteen ounces, contains 9216 Paris grains, whilst the avoirdupois contains only 8532.5 Paris grains; and that the Paris inch is 1.065977 English inch. At 30 days, 2 months, 3 do. 4 do. 5 do. 6 do. 7 do. 8 do. Beck. Maygrier. Granville. Beck. Maygrier. Granville. Length. Weight. 3 to 5 lines 2 inches 3i do. 5 to 6 do. 7 to 9 9 to 12 12 to 14 16 10 to 12 lines. 4 inches 6 do. 8 do. 10 do. 12 do. 14 do. 16 do. 1 inch 3 inches 9 inches 12 do. 17 do. 2 ounces 2 or 3 ounces 4 or 5 do. 9 or 10 1 to 2 pounds 2 to 3 do. 3 to 4 do. 9 or 10 grains 5 drachms 2| ounces 7 or 8 do. 16 ounces 2 pounds 3 do. 4 do. 20 grains 1£ ounce 1 pound 2 to 4 pounds 4 to 5 d». The difficulty must necessarily be great in making any accurate estimate during the early periods of fcetal existence; and the changes in the after months are liable to considerable fluctuation. Chaussier affirms, that after the fifth month, the foetus increases an inch every fifteen days, and Maygrier adopts his estimate. The former gentle- man has published a table of the dimensions of the fcetus at the full period, deduced from an examination of more than fifteen thousand cases. From these we are aided in forming a judgment of the probable age of a fcetus in the latter months of utero-gestation;—a point of interest with the medico-legal inquirer. At the full period, the middle of the body corresponds exactly with the umbilicus; at eight months, it is three-quarters of an inch, or an inch higher. At seven months it approaches still nearer the sternum; and at six months it falls exactly at the lower extremity of that bone; hence, if we depend upon these admeasurements, should the middle of the body of the fcetus be found to fall at the lower extremity of the ster- num, we may be justified in concluding that the fcetus is under the seventh month, and consequently not viable or rearable. A striking circumstance, connected with the developement of the fcetus, is the progressive diminution in proportion between the part of the body above the umbilicus and that below it. At a very early period of fcetal life, (see Figs. 185, and 186,) the cord is attached near the base of the trunk; but the parts beneath become gradually de- veloped, until its insertion ultimately falls about the middle of the body.d » Medical Jurisprudence, 6th edit. i. 276, New York, 1838. b Nouvelles Demonstrations d'Accouchemens, Paris, 1822-26. c Graphic Illustrations of Abortion, &c, p. xi., Lond. 1834. See Seiler, art. Embryo in Anat. Phys. Real Worterb. ii. s. 530, Leipz. und Altenb. 1818.